JP7691307B2 - Method for producing cured polyimide film - Google Patents

Description

The present invention relates to a method for producing a polyimide cured film.

Conventionally, polyimide resins, which have excellent heat resistance, electrical properties, and mechanical properties, have been used as insulating materials for electronic components, and passivation films, surface protective films, and interlayer insulating films for semiconductor devices. Among these polyimide resins, those provided in the form of photosensitive polyimide precursor compositions can easily form heat-resistant relief pattern films by applying the composition, exposing it to light, developing it, and subjecting it to a thermal imidization treatment by curing. Such photosensitive polyimide precursor compositions have the characteristic of enabling significant process shortening compared to conventional non-photosensitive polyimide materials.

Meanwhile, semiconductor devices (hereinafter also referred to as "elements") are mounted on printed circuit boards by various methods according to the purpose. Conventional elements have generally been produced by wire bonding, which connects the external terminals (pads) of the element to the lead frame with thin wires, but recently, from the viewpoint of high-speed transmission and thin package height, a semiconductor chip mounting technology called fan-out wafer level packaging (FOWLP) has been proposed. FOWLP is a mounting technology in which a wafer that has been subjected to pre-processing is diced to produce individual chips, the individual chips are reconstructed on a support, sealed with molding resin, and a rewiring layer is formed after peeling off the support.

In recent years, there is an urgent need to develop packages for the new communication standard, the fifth generation mobile communication system (5G). Unlike conventional 4G technology, 5G uses millimeter wave (10 GHz to 80 GHz) frequency bands, enabling high speed and large capacity, low signal latency, and simultaneous connection of multiple terminals, which were not possible with conventional communications. In the millimeter wave band, the effect of transmission loss in the signal wiring of the printed wiring board is large, and there are concerns about heat generation and transmission delays. Therefore, in order to reduce transmission loss, an antenna in package (AiP) has been developed in which the front-end module (FEM) that transmits and receives radio waves is integrated with the antenna (see, for example, Patent Document 1 below). Since the wiring length is short in AiP, it is possible to suppress transmission loss, which increases in proportion to the wiring length.

US Patent Application Publication No. 2016/0104940

On the other hand, there is a limit to how much transmission loss can be suppressed through package design, and improvements in materials are also needed. If the dielectric constant or dielectric tangent (tan δ) of the insulating material used to form the wiring is high, the dielectric loss increases and the transmission loss increases. In particular, although polyimide has excellent insulation performance and film properties, the imide group itself is a polar functional group, so it has a high dielectric constant and dielectric tangent, and there is a demand for a reduction in its dielectric properties.

In view of the above-mentioned state of the art, the problem to be solved by the present invention is to provide a method for producing a polyimide cured film that exhibits a low dielectric tangent, has a low frequency dependency of the dielectric tangent, and has a high thermal weight loss temperature, a method for producing a cured relief pattern, and a polyimide cured film obtained by the method.

The inventors unexpectedly discovered that the above problems can be solved by controlling the pressure during heating within a specific range in a method for producing a polyimide cured film using a photosensitive resin composition containing a polyimide precursor as a raw material, and thus completed the present invention.

｛式中、Ｒ₂₁とＲ₂₂は、それぞれ独立に、水素原子又は炭素数１～６の１価の有機基であり、そして＊は接続部を表す。｝で表される構造を有するポリイミドの、再配線用層間絶縁膜形成用ポリイミド硬化膜。
［１０］前記ポリイミドが、下記式：

｛式中、＊は、接続部を表す。｝で表される構造の内の少なくとも１つを含む、前記［９］に記載の再配線用層間絶縁膜形成用ポリイミド硬化膜。
［１１］３２０℃に加熱した際の重量減少率が、０．０１％～０．５％であり、かつ、３５０℃に加熱した際の重量減少率が、０．１％～１．５％である、前記［９］又は［１０］に記載の再配線用層間絶縁膜形成用ポリイミド硬化膜。
［１２］３２０℃に加熱した際の重量減少率が、０．０１％～０．５％であり、かつ、３５０℃に加熱した際の重量減少率が、０．１％～１．５％であり、かつ、摂動方式スプリットシリンダ共振器法により周波数４０ＧＨｚで測定した際の誘電正接が、０．００２１～０．００８５である、再配線用層間絶縁膜形成用ポリイミド硬化膜。
［１３］前記ポリイミド前駆体が、下記一般式（１）：

｛式中、Ｘ₁は、炭素数６～４０の４価の有機基であり、Ｙ₁は、炭素数６～４０の２価の有機基であり、ｎ₁は、２～１５０の整数であり、そしてＲ₁とＲ₂は、それぞれ独立に、水素原子又は炭素数１～４０の１価の有機基である。但し、Ｒ₁とＲ₂の内の少なくとも一方は、下記一般式（２）：

（式中、Ｒ₃、Ｒ₄とＲ₅は、それぞれ独立に、水素原子又は炭素数１～３の１価の有機基であり、そしてｍ₁は、２～１０の整数である。）で表される基である。｝で表される構造を有する、前記［１］～［８］のいずれかに記載のポリイミド硬化膜の製造方法。
［１４］前記感光性樹脂組成物が、光重合開始剤を含む、前記［１］～［８］、及び［１３］のいずれかに記載のポリイミド硬化膜の製造方法。
［１５］前記一般式（１）中、Ｘ₁が、下記式：

｛式中、Ｒ６は、水素原子、フッ素原子、Ｃ１～Ｃ１０の炭化水素基、及びＣ１～Ｃ１０の含フッ素炭化水素基から成る群から選ばれる１価の基であり、ｌは、０～２から選ばれる整数であり、ｍは、０～３から選ばれる整数であり、そしてｎは、０～４から選ばれる整数である。｝で表される構造の内の少なくとも１つである、前記［１４］に記載のポリイミド硬化膜の製造方法。
［１６］前記一般式（１）中、Ｘ₁が、下記式：

｛式中、＊は、接続部を表す。｝で表される構造の内の少なくとも１つである、前記［１３］～［１５］のいずれかに記載のポリイミド硬化膜の製造方法。 That is, the present invention is as follows.
[1] the steps of:
(1) applying a photosensitive resin composition containing a polyimide precursor onto a substrate to form a photosensitive resin layer on the substrate;
(2) A step of drying and heating the obtained photosensitive resin layer;
(3) a step of exposing the obtained photosensitive resin layer;
(4) a step of developing the obtained photosensitive resin layer; and (5) a step of heating the photosensitive resin layer remaining on the substrate at 150° C. to 250° C. to form a cured film.
wherein the steps (2) and/or (5) are carried out under a pressure of 50 torr or more and 580 torr or less, and the polyimide in the obtained cured polyimide film has an imide group concentration, which is the ratio of imide groups to the molecular weight of a repeating unit containing a structure derived from a tetracarboxylic acid and a diamine, of 12 wt % to 30 wt %.
[2] The method for producing a polyimide cured film according to the above [1], wherein the cured film obtained by the step (5) has a dielectric loss tangent of 0.001 to 0.007 at a frequency of 10 GHz, as measured by a perturbation split cylinder resonator method.
[3] The method for producing a polyimide cured film according to the above [1] or [2], wherein the step (5) is carried out under a pressure of 50 torr or more and 580 torr or less.
[4] The method for producing a polyimide cured film according to [3] above, wherein in the step (5), when the set heat curing temperature is reached, the temperature change from the set temperature is 30.0° C. or less.
[5] The method for producing a polyimide cured film according to any one of [3] to [5] above, wherein in the step (5), in a region in which the temperature change is 9.5° C./min or less, the pressure change is 150 torr or less.
[6] The method for producing a polyimide cured film according to any one of [1] to [5] above, wherein the weight loss rate of the obtained polyimide cured film when heated to 320° C. is 0.01% to 0.5%.
[7] The method for producing a polyimide cured film according to any one of [1] to [6] above, wherein the weight loss rate of the obtained polyimide cured film when heated to 350° C. is 0.1% to 1.5%.
[8] The obtained polyimide cured film has the following formula (i):
0.001<(tanδ40-tanδ10)/tanδ10<0.2 (i)
{wherein tan δ40 is the dielectric tangent at a frequency of 40 GHz as measured by a perturbation type split cylinder resonator method, and tan δ10 is the dielectric tangent at a frequency of 10 GHz as measured by a perturbation type split cylinder resonator method.}. The method for producing a polyimide cured film according to any one of the above [1] to [7],
[9] A dielectric loss tangent of 0.001 to 0.009 when measured at a frequency of 10 GHz by a perturbation split cylinder resonator method, represented by the following general formula (10):

A cured polyimide film for forming an interlayer insulating film for rewiring, the polyimide having a structure represented by the following formula: {wherein R ₂₁ and R ₂₂ are each independently a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms, and * represents a connecting portion.}
[10] The polyimide has the following formula:

{wherein * represents a connection portion.} The polyimide cured film for forming an interlayer insulating film for redistribution wiring according to the above [9], comprising at least one of the structures represented by the following formula:
[11] The polyimide cured film for forming an interlayer insulating film for redistribution wiring according to [9] or [10], wherein the weight loss rate when heated to 320°C is 0.01% to 0.5% and the weight loss rate when heated to 350°C is 0.1% to 1.5%.
[12] A polyimide cured film for forming an interlayer insulating film for redistribution wiring, which has a weight loss rate of 0.01% to 0.5% when heated to 320°C and a weight loss rate of 0.1% to 1.5% when heated to 350°C, and has a dielectric loss tangent of 0.0021 to 0.0085 when measured at a frequency of 40 GHz by a perturbation split cylinder resonator method.
[13] The polyimide precursor is represented by the following general formula (1):

In the formula, _X1 is a tetravalent organic group having 6 to 40 carbon atoms, _Y1 is a divalent organic group having 6 to 40 carbon atoms, _n1 is an integer from 2 to 150, and _R1 and _R2 are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, provided that at least one of _R1 and _R2 is represented by the following general formula (2):

(wherein R ₃ , R ₄ and R ₅ are each independently a hydrogen atom or a monovalent organic group having 1 to 3 carbon atoms, and m ₁ is an integer of 2 to 10).
[14] The method for producing a polyimide cured film according to any one of [1] to [8] and [13], wherein the photosensitive resin composition contains a photopolymerization initiator.
[15] In the general formula (1), X ₁ is the following formula:

{wherein R6 is a monovalent group selected from the group consisting of a hydrogen atom, a fluorine atom, a C1-C10 hydrocarbon group, and a C1-C10 fluorinated hydrocarbon group, l is an integer selected from 0 to 2, m is an integer selected from 0 to 3, and n is an integer selected from 0 to 4.}.
[16] In the general formula (1), X ₁ is the following formula:

{wherein * represents a connecting portion.} The method for producing a polyimide cured film according to any one of the above [13] to [15],

The method for producing a polyimide cured film according to the present invention is capable of providing a polyimide cured film with low frequency dependence of the dielectric tangent and suppressed thermal weight loss at temperatures equal to or higher than the heat curing temperature by performing heating under reduced pressure.

The following provides a detailed description of the form for carrying out the present invention (hereinafter, abbreviated as "embodiment"). Note that the present invention is not limited to the following embodiment, and can be carried out in various modifications within the scope of the gist. Throughout this specification, when a plurality of structures represented by the same symbol in a general formula are present in a molecule, they are each independently selected and may be the same or different from each other, unless otherwise specified. Furthermore, structures represented by a common symbol in different general formulas are also each independently selected and may be the same or different from each other, unless otherwise specified.

[Method for producing cured film]
One embodiment of the present invention is a process for producing a method for the preparation of a semiconductor device comprising the steps of:
(1) applying a photosensitive resin composition containing a polyimide precursor onto a substrate to form a photosensitive resin layer on the substrate;
(2) A step of drying and heating the obtained photosensitive resin layer;
(3) a step of exposing the obtained photosensitive resin layer;
(4) a step of developing the obtained photosensitive resin layer; and (5) a step of heating the photosensitive resin layer remaining on the substrate at 150° C. to 250° C. to form a cured film.
The method for producing a polyimide cured film, comprising the steps of: (1) forming a polyimide cured film by subjecting the polyimide to a pressure of from 50 torr to 580 torr; and (2) forming a polyimide cured film by subjecting the polyimide cured film to a pressure of from 50 torr to 580 torr. The method for producing a polyimide cured film is characterized in that the step (2) and/or (5) is performed under a pressure of from 50 torr to 580 torr.
From the viewpoint of the dielectric loss tangent, the step (5) is preferably carried out under a pressure of 50 torr or more and 580 torr or less.
The pressure is preferably 80 torr to 580 torr, more preferably 100 torr to 500 torr, more preferably 120 torr to 450 torr, and even more preferably 160 torr to 420 torr. Although not bound by any particular theory, heating at a pressure of 580 torr or less lowers the boiling point of the low molecular weight compounds present in the film, making them easier to vaporize, and by removing them from the film, a cured film with low dielectric loss in the high frequency range is obtained. At the same time, since there are fewer components that volatilize when the cured film is heated, the weight loss rate during heating is reduced. Also, although not bound by any theory, heating at a pressure of 50 torr or more does not inhibit the progress of imidization by heat curing, as the solvent molecules do not vaporize immediately after decompression.

Each step will be described below.
[(1) Step of applying a photosensitive resin composition containing a polyimide precursor onto a substrate to form a photosensitive resin layer on the substrate]
In step (1), a photosensitive resin composition containing a polyimide precursor is applied onto a substrate, and then dried as necessary to form a photosensitive resin layer. As the application method, a method that has been conventionally used for applying a photosensitive resin composition, such as a method of applying using a spin coater, a bar coater, a blade coater, a curtain coater, a screen printer, or the like, or a method of spray application using a spray coater, can be used.

[(2) Step of drying and heating the obtained photosensitive resin layer]
In step (2), the coating film made of the photosensitive resin composition can be dried as necessary. Examples of the drying method include air drying, heat drying using an oven or a hot plate, and vacuum drying. Specifically, when air drying or heat drying is performed, the temperature can be 20°C to 140°C, more preferably 80°C to 140°C, and more preferably 80°C to 120°C. The drying time can be 1 minute to 1 hour, more preferably 2 minutes to 30 minutes, and more preferably 2 minutes to 10 minutes. By drying under the above conditions, a photosensitive resin layer can be formed on the substrate.
When the (2) drying/heating step is performed by vacuum drying, the heat source is preferably selected from a hot plate or an infrared lamp. Furthermore, from the viewpoint of heating efficiency under reduced pressure, it is preferable to place the wafer on which the coating film is formed on the heat source and heat it. The (2) drying/heating step can be performed under a pressure of 50 torr or more and 580 torr or less. The change in pressure from the set value is preferably within 150 torr, more preferably within 100 torr, even more preferably within 80 torr, and even more preferably within 60 torr.

[(3) Step of exposing the obtained photosensitive resin layer]
In step (3), the photosensitive resin layer formed in step (1) is exposed to an ultraviolet light source or the like through a photomask or reticle having a pattern, or directly, using an exposure device such as a contact aligner, a mirror projection, or a stepper.
Thereafter, post-exposure baking (PEB) and/or pre-development baking may be performed at any combination of temperature and time as necessary for the purpose of improving photosensitivity, etc. The range of baking conditions is preferably a temperature of 40° C. to 120° C. and a time of 10 seconds to 240 seconds, but is not limited to this range as long as it does not impair the various properties of the negative photosensitive resin composition.

[(4) Step of developing the obtained photosensitive resin layer]
In step (4), when the photosensitive resin composition is a negative type, the unexposed portion of the photosensitive resin layer after exposure is developed and removed. As a development method for developing the photosensitive resin layer after exposure (irradiation), any method can be selected from conventionally known photoresist development methods, such as a rotary spray method, a paddle method, and a dipping method accompanied by ultrasonic treatment. In addition, after development, for the purpose of adjusting the shape of the relief pattern, etc., post-development baking may be performed at any combination of temperature and time as necessary. As a developer used for development, for example, a good solvent for the negative type photosensitive resin composition, or a combination of the good solvent and a poor solvent is preferable. As a good solvent, for example, N-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N,N-dimethylacetamide, cyclopentanone, cyclohexanone, γ-butyrolactone, α-acetyl-γ-butyrolactone, etc. are preferable. As the poor solvent, for example, toluene, xylene, methanol, ethanol, isopropyl alcohol, ethyl lactate, propylene glycol methyl ether acetate, water, etc. are preferable. When a good solvent and a poor solvent are used in combination, it is preferable to adjust the ratio of the poor solvent to the good solvent depending on the solubility of the polymer in the negative photosensitive resin composition. In addition, two or more kinds of each solvent, for example, several kinds, can be used in combination.

[(5) A step of heating the photosensitive resin layer remaining on the substrate at 150° C. to 250° C. to form a cured film]
In step (5) (heat curing step), the photosensitive resin layer (relief pattern) remaining on the plate obtained by the above development is heated to dissolve the photosensitive component and imidize the polyimide precursor (A) to convert it into a cured film made of polyimide. As a method for heat curing, various methods can be selected, such as using a hot plate, an oven, or a temperature-programmable temperature-programmable oven, but a temperature-programmable oven is preferred. The pressure for heating in a temperature-programmable oven can be normal pressure (760 torr), reduced pressure, or pressurized, but reduced pressure (760 torr or less) is preferred.

The heat curing step preferably includes a temperature increase step, a constant temperature step, and a temperature decrease step, and the constant temperature step may be performed at one temperature or at two or more different temperatures. The temperature increase step preferably changes by 10 to 30°C per minute. The heating temperature in the constant temperature step can be performed at 150°C to 250°C, preferably at 170 to 250°C, and more preferably at 170 to 230°C from the viewpoint of the remaining film rate before and after heating. The temperature in the furnace in the constant temperature step preferably changes from the set value by 30.0°C or less, more preferably 20.0°C or less, and from the viewpoint of heating efficiency, preferably 15.0°C or less.
In the constant temperature process, the change in pressure from the set value when the pressure is kept constant is preferably within 150 torr, more preferably within 100 torr, even more preferably within 80 torr, and even more preferably within 60 torr. By keeping the pressure constant, the temperature inside the furnace in the constant temperature process is stabilized. The pressure adjustment process may be performed in any process, but from the viewpoint of uniform temperature, it is preferable to perform it before the temperature increase process. When adjusting the pressure, the inside of the chamber may be replaced with nitrogen, and it is preferable to repeat the decompression and nitrogen replacement two or more times. The oxygen concentration inside the chamber is preferably 10 ppm or less. The temperature decrease process preferably changes by 10 to 50° C. per minute. The heating in the heat curing process can be performed under conditions of 30 minutes to 5 hours, more preferably 1 hour to 3 hours, and more preferably 90 minutes to 3 hours. Air may be used as the atmospheric gas during heat curing, and inert gas such as nitrogen and argon may also be used.

[Cured film]
The resulting polyimide cured film preferably has a predetermined dielectric loss tangent and a predetermined ratio of the peaks near 1380 cm ^-1 and 1500 cm ^-1 in the IR spectrum.
From the viewpoint of satisfying the formula (i) and/or (ii) described below, the photosensitive resin composition used as a raw material in the method for producing a polyimide cured film of the present embodiment preferably contains 100 parts by mass of a polyimide precursor, 0.1 to 10 parts by mass of a photosensitizer, and 50 to 300 parts by mass of a solvent, more preferably contains a photoradical polymerization initiator as the photosensitizer, and further preferably the photosensitive resin composition is a negative type.

<Dielectric tangent>
The resulting polyimide cured film preferably has a dielectric loss tangent of 0.001 to 0.009, more preferably 0.001 to 0.007, and even more preferably 0.003 to 0.0065, as measured at 10 GHz by a perturbation split cylinder resonator method.
The dielectric loss tangent when measured at 28 GHz is preferably 0.0021 to 0.008, more preferably 0.0030 to 0.0075, and even more preferably 0.0035 to 0.0075.
The dielectric loss tangent measured at 40 GHz is preferably 0.0021 to 0.0085, more preferably 0.0030 to 0.0075, and even more preferably 0.0035 to 0.0075.
The dielectric loss tangent measured at 60 GHz is preferably 0.0021 to 0.009, more preferably 0.0030 to 0.0085, and even more preferably 0.0035 to 0.0082. By keeping it in this range, when it is packaged as an AiP or the like, signal delay tends to be reduced.

The obtained polyimide cured film has the following formula (i):
0.001<(tanδ ₄₀ -tanδ ₁₀ )/tanδ ₁₀ <0.2 (i)
{wherein tan _δ is the dielectric tangent at a frequency of 40 GHz as determined by the perturbation split cylinder resonator method, and tan _δ is the dielectric tangent at a frequency of 10 GHz as determined by the perturbation split cylinder resonator method.}, and/or the following formula (ii):
0.001<(tanδ ₆₀ -tanδ ₁₀ )/tanδ ₁₀ <0.29 (ii)
It is preferable to satisfy the relationship represented by the following formula: {wherein tan δ ₆₀ is the dielectric tangent at a frequency of 60 GHz as determined by the perturbation type split cylinder resonator method, and tan δ ₁₀ is the dielectric tangent at a frequency of 10 GHz as determined by the perturbation type split cylinder resonator method.}
When the above formula (i) and/or (ii) is satisfied, the polarity of the cured film can be reduced, thereby reducing the dielectric tangent. In addition, since the resins have good compatibility with each other, the resin composition before curing can be stored without undergoing phase separation, and the resolution during the formation of a relief pattern tends to be maintained.

<IR spectrum>
The obtained polyimide cured film preferably has an IR spectrum ratio of the peak near 1380 ^cm to the peak near 1500 ^cm of 0.30 to 0.54, more preferably 0.35 to 0.54, even more preferably 0.40 to 0.54, and still more preferably 0.45 to 0.54.
By making the peak ratio of 1380 cm ^-1 to 1500 cm ^-1 in the IR spectrum 0.54 or less, it is possible to reduce the polarity of the entire film and suppress an increase in the dielectric tangent. On the other hand, making the peak ratio 0.30 or more is effective in maintaining the toughness of the resin, the adhesion to metals, and the thermal properties.
The IR spectrum can be measured by an ATR-FTIR measuring device shown in the examples described later.

<Weight reduction rate>
From the viewpoint of the frequency dependence of the dielectric loss tangent, the weight loss rate of the obtained polyimide cured film when heated to 320°C is preferably 0.01% to 0.5%, more preferably 0.05% to 0.4%, and the weight loss rate when heated to 350°C is preferably 0.1% to 1.5%, more preferably 0.2% to 1.2%.

[Photosensitive resin composition]
The photosensitive resin composition containing the polyimide includes (A) a polyimide precursor, (B) a photosensitizer, and (D) a solvent, and optionally includes other components. Each component will be described in turn below.

｛式中、Ｘ₁は、炭素数６～４０の４価の有機基であり、Ｙ₁は、炭素数６～４０の２価の有機基であり、ｎ₁は、２～１５０の整数であり、そしてＲ₁とＲ₂は、それぞれ独立に、水素原子又は炭素数１～４０の１価の有機基である。但し、Ｒ₁とＲ₂の内の少なくともいずれかは、下記一般式（２）：

（式中、Ｒ₃、Ｒ₄とＲ₅は、それぞれ独立に、水素原子又は炭素数１～３の１価の有機基であり、そしてｍ₁は、２～１０の整数である。）で表される基である。｝で表される構造単位を有するポリアミドである。 The photosensitive resin composition may be either a negative type or a positive type depending on the desired application, and is preferably a negative type from the viewpoint of the physical properties of the polyimide precursor (A) described below.
(A) Polyimide Precursor (A) The polyimide precursor is a resin component contained in the photosensitive resin composition, and is preferably represented by the following general formula (1):

In the formula, _X1 is a tetravalent organic group having 6 to 40 carbon atoms, _Y1 is a divalent organic group having 6 to 40 carbon atoms, _n1 is an integer from 2 to 150, and _R1 and _R2 are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, provided that at least one of _R1 and _R2 is represented by the following general formula (2):

(wherein R ₃ , R ₄ and R ₅ are each independently a hydrogen atom or a monovalent organic group having 1 to 3 carbon atoms, and m ₁ is an integer of 2 to 10).

The ratio of the monovalent organic group represented by the above general formula (2) to all of R ₁ and R ₂ of the precursor represented by the above general formula (1) contained in the polyimide precursor (A) is preferably 50 mol % to 100 mol % from the viewpoint of high resolution, and more preferably 75 mol % to 100 mol % from the viewpoints of high chemical resistance and sensitivity.

In the above general formula (1), n1 is preferably an integer from 3 to 100, and more preferably an integer from 5 to 70, from the viewpoint of the photosensitive properties and mechanical properties of the photosensitive resin composition.

｛式（２０）中、Ｒ６は、水素原子、フッ素原子、Ｃ１～Ｃ１０の炭化水素基、及びＣ１～Ｃ１０の含フッ素炭化水素基から成る群から選ばれる１価の基であり、ｌは、０～２から選ばれる整数であり、ｍは、０～３から選ばれる整数であり、そしてｎは、０～４から選ばれる整数である。｝で表される構造を有する基が挙げられるが、これらに限定されるものではない。また、Ｘ₁の構造は１種でも２種以上の組み合わせでもよい。上記式（２０）で表される構造を有するＸ₁基は、耐熱性と感光特性とを両立するという点で特に好ましい。 In the above general formula (1), the tetravalent organic group represented by _X1 is preferably an organic group having 6 to 40 carbon atoms, from the viewpoint of achieving both heat resistance and photosensitive properties, and more preferably an aromatic group in which the _-COOR1 group and the _-COOR2 group are in the ortho position relative to the -CONH- group, or an alicyclic aliphatic group. Specific examples of the tetravalent organic group represented by _X1 include organic groups having 6 to 40 carbon atoms containing an aromatic ring, such as the following general formula (20):

{In formula (20), R6 is a monovalent group selected from the group consisting of a hydrogen atom, a fluorine atom, a C1-C10 hydrocarbon group, and a C1-C10 fluorine-containing hydrocarbon group, l is an integer selected from 0 to 2, m is an integer selected from 0 to 3, and n is an integer selected from 0 to 4.}, but is not limited thereto. The structure of X ₁ may be one type or a combination of two or more types. The X ₁ group having the structure represented by formula (20) is particularly preferred in that it has both heat resistance and photosensitive properties.

｛式中、Ｒｙは、それぞれ独立に、ハロゲン原子を含んでもよい炭素数１～１０の１価の有機基を表し、ａは、０～４の整数を表し、Ｃは、酸素原子又は硫黄原子であり、そしてＤは、単結合又は下記式：

で表される少なくとも１種の基である。｝で表される構造が低誘電正接の観点で好ましく、この中でも特に下記式：

又は下記式：

で表される構造が好ましい。 As the structure represented by _X1 , among the structures represented by the above formula (20), the following formula (X1):

In the formula, each Ry independently represents a monovalent organic group having 1 to 10 carbon atoms which may contain a halogen atom, a represents an integer of 0 to 4, C represents an oxygen atom or a sulfur atom, and D represents a single bond or a group represented by the following formula:

From the viewpoint of low dielectric tangent, a structure represented by the following formula is particularly preferred.

Or the following formula:

The structure represented by the following formula is preferred.

で表される構造が、熱重量減少率の観点から好ましい。 The structure represented by _X1 includes the following formula:

The structure represented by the following formula is preferred from the viewpoint of the thermal weight loss rate.

｛式（２１）中、Ｒ６は、水素原子、フッ素原子、Ｃ１～Ｃ１０の炭化水素基、及びＣ１～Ｃ１０の含フッ素炭化水素基から成る群から選ばれる１価の基であり、ｍは、０～３から選ばれる整数であり、そしてｎは、０～４から選ばれる整数である。｝で表される構造が挙げられるが、これらに限定されるものではない。また、Ｙ₁の構造は１種でも２種以上の組み合わせでもよい。上記式（２１）で表される構造を有するＹ₁基は、耐熱性及び感光特性を両立するという点で特に好ましい。 In the above general formula (1), the divalent organic group represented by _Y1 is preferably an aromatic group having 6 to 40 carbon atoms in terms of achieving both heat resistance and photosensitive properties, and is, for example, a group represented by the following formula (21):

{In formula (21), R6 is a monovalent group selected from the group consisting of a hydrogen atom, a fluorine atom, a C1-C10 hydrocarbon group, and a C1-C10 fluorine-containing hydrocarbon group, m is an integer selected from 0 to 3, and n is an integer selected from 0 to 4.}, but is not limited thereto. The structure of Y ₁ may be one type or a combination of two or more types. The Y ₁ group having the structure represented by formula (21) is particularly preferred in that it has both heat resistance and photosensitive properties.

｛式中、Ｒｚは、それぞれ独立に、ハロゲン原子を含んでもよい炭素数１～１０の１価の有機基であり、ａは、０～４の整数であり、Ａは、酸素原子又は硫黄原子であり、そしてＢは、単結合又は下記式：

表される少なくとも１種の基である。｝で表される構造が低誘電正接化の観点から好ましく、さらに下記式：

又は下記式：

又は下記式：

で表される構造が、低誘電正接、低誘電率、リソ性の観点から好ましい。 As the _Y1 group, among the structures represented by the above formula (21), the following formula (Y1):

In the formula, each Rz is independently a monovalent organic group having 1 to 10 carbon atoms which may contain a halogen atom, a is an integer of 0 to 4, A is an oxygen atom or a sulfur atom, and B is a single bond or a group represented by the following formula:

From the viewpoint of reducing the dielectric loss tangent, a structure represented by the following formula is preferred, and further, a structure represented by the following formula:

Or the following formula:

Or the following formula:

The structure represented by the following formula is preferable from the viewpoints of low dielectric tangent, low dielectric constant, and lithographic properties.

In the above general formula (2), _R3 is preferably a hydrogen atom or a methyl group, and _R4 and _R5 are preferably hydrogen atoms from the viewpoint of photosensitive properties. Also, _m1 is an integer of 2 to 10, preferably an integer of 2 to 4, from the viewpoint of photosensitive properties.

In this specification, the term "imide group concentration" refers to the mass ratio of imide groups to the molecular weight of a repeating unit containing a structure derived from a tetracarboxylic acid and a diamine in a polyimide cured film obtained by heating and curing the photosensitive resin composition according to this embodiment.
In this embodiment, the imide group concentration of the obtained polyimide cured film is 12 wt% to 30 wt%, and preferably 12 wt% to 24 wt%. If the imide group concentration is 12 wt% or more, the adhesion between the mold resin and the cured relief pattern tends to be good. The imide group concentration is preferably 12.5 wt% or more, and more preferably 13.5 wt% or more. On the other hand, if the imide group concentration is 30 wt% or less, the dielectric loss tangent of the obtained polyimide cured film tends to be good. The imide group concentration is preferably 24.0 wt% or less, more preferably 23.0 wt% or less, and even more preferably 21.0 wt% or less.

The imide group concentration per repeating unit of the polyimide is calculated using the molecular weights of the tetracarboxylic acid and diamine used in preparing the polyimide precursor according to the following formula (I):
70.02×2/[Mw(A)+Mw(B)]×100 (I)
{In formula (I), Mw(A) represents the molecular weight of the tetracarboxylic acid, and Mw(B) represents the molecular weight of the diamine.} When two or more kinds of tetracarboxylic acids and/or diamines are used, for example, when preparing using two kinds of tetracarboxylic acids and/or diamines, the following formula (II):
70.02×2/[Mw(A1)×a ₁ +Mw(A2)×a ₂ +Mw(B1)×b ₁ +Mw(B2)×b ₂ ]×100 (II)
{In formula (II), Mw(A1) represents the molecular weight of the first tetracarboxylic acid, Mw(A2) represents the molecular weight of the second tetracarboxylic acid, _a1 represents the content of the first tetracarboxylic acid, _a2 represents the content of the second tetracarboxylic acid, Mw(B1) represents the molecular weight of the first diamine, Mw(B2) represents the molecular weight of the second diamine, _b1 represents the content of the first diamine, and _b2 represents the content of the second diamine. However, _a1 , _a2 , _b1 , and _b2 satisfy _a1 + _a2 = 1 and _b1 + _b2 = 1, respectively.}.
The same can be obtained when three or more kinds of tetracarboxylic acids and/or diamines are used. When a tetracarboxylic dianhydride is used as a raw material, the calculation is performed in terms of the tetracarboxylic acid.

(A) Method for Preparing Polyimide Precursor The polyimide precursor containing the structure represented by the above general formula (1) can be obtained by a method comprising: reacting a tetracarboxylic dianhydride containing the above-mentioned tetravalent organic group _X1 having 6 to 40 carbon atoms with (a) an alcohol having a structure in which a monovalent organic group represented by the above general formula (2) and a hydroxyl group are bonded, and, if desired, with (b) an alcohol having a structure other than the group represented by the above general formula (2) to prepare a partially esterified tetracarboxylic acid (hereinafter also referred to as an acid/ester body); and subsequently polycondensing the obtained acid/ester body with a diamine containing the above-mentioned divalent organic group _Y1 having 6 to 40 carbon atoms.

(Preparation of Acid/Ester Forms)
Examples of tetracarboxylic dianhydrides containing a tetravalent organic group X ₁ having 6 to 40 carbon atoms include pyromellitic anhydride, diphenylether-3,3',4,4'-tetracarboxylic dianhydride, benzophenone-3,3',4,4'-tetracarboxylic dianhydride, biphenyl-3,3',4,4'-tetracarboxylic dianhydride, diphenylsulfone-3,3',4,4'-tetracarboxylic dianhydride, diphenylmethane-3,3',4,4'-tetracarboxylic dianhydride, 2,2-bis(3,4-phthalic anhydride)propane, 2,2-bis(3,4-phthalic anhydride)-1,1,1,3,3,3-hexafluoropropane, 4,4'-(4,4'-isopropylidenediphenoxy)acid dianhydride, etc. These can be used alone or in combination of two or more.

(b) Examples of alcohols having a structure other than the group represented by the general formula (2) above include aliphatic alcohols having 5 to 30 carbon atoms or aromatic alcohols having 6 to 30 carbon atoms, such as 1-pentanol, 2-pentanol, 3-pentanol, neopentyl alcohol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 3-octanol, 1-nonanol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, and benzyl alcohol.

By dissolving and mixing the above tetracarboxylic dianhydride and the above alcohol (a) in a reaction solvent in the presence of a basic catalyst such as pyridine, the half-esterification reaction of the acid dianhydride proceeds, and the desired acid/ester body can be obtained. The reaction conditions are preferably a reaction temperature of 20 to 50°C and stirring for 4 to 10 hours.

The reaction solvent is preferably one that dissolves the acid/ester and the polyimide precursor, which is a polycondensation product of the acid/ester and diamines. Examples of reaction solvents include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, tetramethylurea, gamma butyrolactone, ketones, esters, lactones, ethers, halogenated hydrocarbons, hydrocarbons, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, chlorobenzene, o-dichlorobenzene, hexane, heptane, benzene, toluene, and xylene. These may be used alone or in combination as needed.

(Preparation of polyimide precursor)
A known dehydration condensation agent is mixed with the above acid/ester (typically a solution in the above reaction solvent) under ice cooling to convert the acid/ester into a polyacid anhydride, and then a diamine containing a divalent organic group _Y1 having 6 to 40 carbon atoms dissolved or dispersed in a separate solvent is added dropwise to the acid/ester to polycondense, thereby obtaining a polyimide precursor. Examples of the dehydration condensation agent include dicyclohexylcarbodiimide, 1-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline, 1,1-carbonyldioxy-di-1,2,3-benzotriazole, and N,N'-disuccinimidyl carbonate.

Examples of diamines containing a divalent organic group _Y1 having 6 to 40 carbon atoms include p-phenylenediamine, m-phenylenediamine, 4,4-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 4,4'-diaminobenzophenone, 3,4'-diaminobenzidine, 4 ... benzophenone, 3,3'-diaminobenzophenone, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 4,4-bis(4-aminophenoxy)biphenyl, 4,4-bis(3-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]ether, 2,2-bis[4-(4-aminophenoxy)phenyl]ether, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 9,10-bis(4-aminophenyl)anthracene, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 1,4-bis(3-aminopropyldimethylsilyl)benzene, ortho-tolidine sulfone, 9,9-bis(4-aminophenyl)fluorene, 2,2-bis{3-methyl-4-(4- bis{4-(4-aminophenoxy)phenyl}propane, bis{4-(4-aminophenoxy)phenyl}ketone, and those in which some of the hydrogen atoms on the benzene ring of these are substituted with a methyl group, an ethyl group, a hydroxymethyl group, a hydroxyethyl group, a halogen, or the like, such as 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 2,2'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dimethytoxy-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl, and mixtures thereof. However, the diamines are not limited to these.

In order to improve adhesion between the photosensitive resin layer formed on the substrate by applying the photosensitive resin composition onto the substrate and various substrates, diaminosiloxanes such as 1,3-bis(3-aminopropyl)tetramethyldisiloxane and 1,3-bis(3-aminopropyl)tetraphenyldisiloxane can also be copolymerized during preparation of the polyimide precursor (A).

After the polycondensation reaction is completed, the water-absorbing by-product of the dehydrating condensing agent coexisting in the reaction solution may be filtered off as necessary, and then a poor solvent such as water, aliphatic lower alcohol, or a mixture thereof may be added to the reaction solution to precipitate the polymer component. The polymer may be purified by repeating the above-mentioned redissolution and reprecipitation operations. The polymer may then be vacuum-dried to isolate the polyimide precursor. To improve the degree of purification, the polymer solution may be passed through a column packed with an anion and/or cation exchange resin swollen with an appropriate organic solvent to remove ionic impurities.

The molecular weight of the polyimide precursor (A), as measured by gel permeation chromatography in terms of polystyrene equivalent weight average molecular weight, is preferably 8,000 to 150,000, more preferably 9,000 to 50,000, and particularly preferably 18,000 to 40,000. A weight average molecular weight of 8,000 or more is preferable because of good mechanical properties, while a weight average molecular weight of 150,000 or less is preferable because of good dispersibility in the developer and resolution performance of the relief pattern. Tetrahydrofuran and N-methyl-2-pyrrolidone are recommended as developing solvents for gel permeation chromatography. The molecular weight is determined from a calibration curve prepared using standard monodisperse polystyrene. It is recommended to select the standard monodisperse polystyrene from among the organic solvent-based standard samples STANDARD SM-105 manufactured by Showa Denko KK.

(B) Photosensitizer The photosensitive resin composition contains a photosensitizer. In one embodiment, the photosensitizer may be a photopolymerization initiator. The photopolymerization initiator is preferable because it promotes curing of the relief pattern by light irradiation. The photopolymerization initiator is preferably a photoradical polymerization initiator, and examples of the photopolymerization initiator include benzophenone, o-benzoyl methyl benzoate, 4-benzoyl-4'-methyldiphenyl ketone, dibenzyl ketone, fluorenone and other benzophenone derivatives, 2,2'-diethoxyacetophenone, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone and other acetophenone derivatives, thioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, diethylthioxanthone and other thioxanthone derivatives, benzyl derivatives, benzil, benzil dimethyl ketal, benzyl-β-methoxyethyl acetal and other benzyl derivatives, benzoin, benzoin methyl ether and other benzoin derivatives, 1-phenyl-1,2-butanedione-2-(o-methoxy Preferred examples of the photopolymerization initiator include, but are not limited to, oximes such as 1-phenyl-1,2-propanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-benzoyl)oxime, 1,3-diphenylpropanetrione-2-(o-ethoxycarbonyl)oxime, and 1-phenyl-3-ethoxypropanetrione-2-(o-benzoyl)oxime, N-arylglycines such as N-phenylglycine, peroxides such as benzoyl perchloride, aromatic biimidazoles, titanocenes, and photoacid generators such as α-(n-octanesulfonyloxyimino)-4-methoxybenzyl cyanide. Of the above photopolymerization initiators, oximes are more preferred, particularly in terms of photosensitivity.

The amount of the photopolymerization initiator is preferably 0.1 parts by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the polyimide precursor (A). The amount is preferably 0.1 parts by mass or more from the viewpoint of photosensitivity or patterning property, and 10 parts by mass or less from the viewpoint of the physical properties of the photosensitive resin layer after curing of the photosensitive resin composition.

(C) Solvent
The photosensitive resin composition of the present embodiment contains a solvent. As the solvent, it is preferable to use a polar organic solvent from the viewpoint of solubility in the polyimide precursor (A). Specific examples of the solvent include N,N-dimethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N-dimethylacetamide, dimethylsulfoxide, diethylene glycol dimethyl ether, cyclopentanone, γ-butyrolactone, α-acetyl-γ-butyrolactone, tetramethylurea, 1,3-dimethyl-2-imidazolinone, N-cyclohexyl-2-pyrrolidone, and 2-octanone, which may be used alone or in combination of two or more.

The above solvent can be used in an amount ranging from 50 to 300 parts by weight, preferably from 100 to 300 parts by weight, per 100 parts by weight of the polyimide precursor (A), depending on the desired coating thickness and viscosity of the photosensitive resin composition.

From the viewpoint of improving the storage stability of the photosensitive resin composition, a solvent containing an alcohol is preferred. The alcohol that can be suitably used is typically an alcohol that has an alcoholic hydroxyl group in the molecule and does not have an olefinic double bond. Specific examples include alkyl alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and tert-butyl alcohol; lactate esters such as ethyl lactate; propylene glycol monoalkyl ethers such as propylene glycol-1-methyl ether, propylene glycol-2-methyl ether, propylene glycol-1-ethyl ether, propylene glycol-2-ethyl ether, propylene glycol-1-(n-propyl) ether, and propylene glycol-2-(n-propyl) ether; monoalcohols such as ethylene glycol methyl ether, ethylene glycol ethyl ether, and ethylene glycol-n-propyl ether; 2-hydroxyisobutyric acid esters; and dialcohols such as ethylene glycol and propylene glycol. Of these, lactate esters, propylene glycol monoalkyl ethers, 2-hydroxyisobutyrate esters, and ethyl alcohol are preferred, with ethyl lactate, propylene glycol-1-methyl ether, propylene glycol-1-ethyl ether, and propylene glycol-1-(n-propyl) ether being particularly preferred.

When the solvent contains an alcohol that does not have an olefinic double bond, the content of the alcohol that does not have an olefinic double bond in the total solvent is preferably 5% by mass to 50% by mass, and more preferably 10% by mass to 30% by mass, based on the mass of the total solvent. When the content of the alcohol that does not have an olefinic double bond is 5% by mass or more, the storage stability of the photosensitive resin composition is good, while when it is 50% by mass or less, the solubility of the (A) polyimide precursor is good, which is preferable.

[Other ingredients]
The photosensitive resin composition may further contain components other than the above components (A), (B), and (C). Examples of the other components include resin components other than the polyimide precursor (A), a sensitizer, a monomer having a photopolymerizable unsaturated bond, a bonding agent, a thermal polymerization inhibitor, an azole compound, and a hindered phenol compound.

The photosensitive resin composition may further contain a resin component other than the polyimide precursor (A). Examples of resin components that can be contained in the photosensitive resin composition include polyimide, polyoxazole, polyoxazole precursor, phenolic resin, polyamide, epoxy resin, siloxane resin, and acrylic resin. The amount of these resin components is preferably in the range of 0.01 to 20 parts by mass per 100 parts by mass of the polyimide precursor (A).

(A) When preparing a positive-type photosensitive resin composition using a polyoxazole precursor together with a polyimide precursor, a compound having a quinone diazide group, such as a compound having a 1,2-benzoquinone diazide structure or a 1,2-naphthoquinone diazide structure, may be used in combination as a positive-type photosensitive material.

The photosensitive resin composition may optionally contain a sensitizer to improve photosensitivity. Examples of such sensitizers include Michler's ketone, 4,4'-bis(diethylamino)benzophenone, 2,5-bis(4'-diethylaminobenzal)cyclopentane, 2,6-bis(4'-diethylaminobenzal)cyclohexanone, 2,6-bis(4'-diethylaminobenzal)-4-methylcyclohexanone, 4,4'-bis(dimethylamino)chalcone, 4,4'-bis(diethylamino)chalcone, p-dimethylaminocinnamylidene indane, and the like. Non, p-dimethylaminobenzylidene indanone, 2-(p-dimethylaminophenylbiphenylene)-benzothiazole, 2-(p-dimethylaminophenylvinylene)benzothiazole, 2-(p-dimethylaminophenylvinylene)isonaphthothiazole, 1,3-bis(4'-dimethylaminobenzal)acetone, 1,3-bis(4'-diethylaminobenzal)acetone, 3,3'-carbonyl-bis(7-diethylaminocoumarin), 3-acetone ethyl-7-dimethylaminocoumarin, 3-ethoxycarbonyl-7-dimethylaminocoumarin, 3-benzyloxycarbonyl-7-dimethylaminocoumarin, 3-methoxycarbonyl-7-diethylaminocoumarin, 3-ethoxycarbonyl-7-diethylaminocoumarin, N-phenyl-N'-ethylethanolamine, N-phenyldiethanolamine, N-p-tolyldiethanolamine, N-phenylethanolamine, 4-morpholinobenzophenone, isoamyl dimethylaminobenzoate, isoamyl diethylaminobenzoate, 2-mercaptobenzimidazole, 1-phenyl-5-mercaptotetrazole, 2-mercaptobenzothiazole, 2-(p-dimethylaminostyryl)benzoxazole, 2-(p-dimethylaminostyryl)benzthiazole, 2-(p-dimethylaminostyryl)naphtho(1,2-d)thiazole, 2-(p-dimethylaminobenzoyl)styrene, and the like. These can be used alone or in combination (e.g., 2 to 5 types).

The amount of sensitizer to be added is preferably 0.1 to 25 parts by weight per 100 parts by weight of (A) polyimide precursor.

In order to improve the resolution of the relief pattern, the photosensitive resin composition may optionally contain a monomer having a photopolymerizable unsaturated bond. As such a monomer, a (meth)acrylic compound that undergoes a radical polymerization reaction with a photopolymerization initiator is preferred, and examples of such a monomer include, but are not limited to, mono- or diacrylates or methacrylates of ethylene glycol or polyethylene glycol, including diethylene glycol dimethacrylate and tetraethylene glycol dimethacrylate, mono- or diacrylates or methacrylates of propylene glycol or polypropylene glycol, mono-, di- or triacrylates or methacrylates of glycerol, cyclohexane diacrylate or dimethacrylate, diacrylate or dimethacrylate of 1,4-butanediol, 1,6 Examples of the monomer include diacrylate or dimethacrylate of hexanediol, diacrylate or dimethacrylate of neopentyl glycol, mono- or diacrylate or methacrylate of bisphenol A, benzene trimethacrylate, isobornyl acrylate or methacrylate, acrylamide or its derivatives, methacrylamide or its derivatives, trimethylolpropane triacrylate or methacrylate, di- or triacrylate or methacrylate of glycerol, di-, tri- or tetraacrylate or methacrylate of pentaerythritol, and ethylene oxide or propylene oxide adducts of these compounds. These monomers may be used alone or in a mixture of two or more.

The amount of the monomer having a photopolymerizable unsaturated bond is preferably 1 to 50 parts by mass per 100 parts by mass of the polyimide precursor (A).

In order to improve the adhesion between the film formed using the photosensitive resin composition and the substrate, the photosensitive resin composition may optionally contain an adhesive aid. Examples of the adhesive aid include γ-aminopropyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, 3-methacryloxypropyldimethoxymethylsilane, 3-methacryloxypropyltrimethoxysilane, dimethoxymethyl-3-piperidinopropylsilane, diethoxy-3-glycidoxypropylmethylsilane, N-(3-diethoxymethylsilylpropyl)succinimide, N-[3-(triethoxysilyl)propyl]phthala Examples of the adhesive aids include silane coupling agents such as amido acid, benzophenone-3,3'-bis(N-[3-triethoxysilyl]propylamide)-4,4'-dicarboxylic acid, benzene-1,4-bis(N-[3-triethoxysilyl]propylamide)-2,5-dicarboxylic acid, 3-(triethoxysilyl)propyl succinic anhydride, and N-phenylaminopropyl trimethoxysilane, and aluminum-based adhesive aids such as aluminum tris(ethylacetoacetate), aluminum tris(acetylacetonate), and ethylacetoacetate aluminum diisopropylate. These adhesive aids may be used alone or in a mixture of two or more.

Among these adhesive aids, it is more preferable to use a silane coupling agent in terms of adhesive strength. The amount of adhesive aid to be added is preferably in the range of 0.5 to 25 parts by mass per 100 parts by mass of (A) polyimide precursor.

In order to improve the stability of the viscosity and photosensitivity of the photosensitive resin composition, particularly when stored in a state of a solution containing a solvent, the photosensitive resin composition may optionally contain a thermal polymerization inhibitor. Examples of thermal polymerization inhibitors that can be used include hydroquinone, N-nitrosodiphenylamine, p-tert-butylcatechol, phenothiazine, N-phenylnaphthylamine, ethylenediaminetetraacetic acid, 1,2-cyclohexanediaminetetraacetic acid, glycol ether diaminetetraacetic acid, 2,6-di-tert-butyl-p-methylphenol, 5-nitroso-8-hydroxyquinoline, 1-nitroso-2-naphthol, 2-nitroso-1-naphthol, 2-nitroso-5-(N-ethyl-N-sulfopropylamino)phenol, N-nitroso-N-phenylhydroxylamine ammonium salt, and N-nitroso-N(1-naphthyl)hydroxylamine ammonium salt. These thermal polymerization inhibitors may be used alone or in a mixture of two or more.

The amount of thermal polymerization inhibitor to be added is preferably in the range of 0.005 parts by mass to 12 parts by mass per 100 parts by mass of (A) polyimide precursor.

For example, when a substrate made of copper or a copper alloy is used, the photosensitive resin composition may optionally contain an azole compound in order to suppress discoloration of the substrate. Examples of the azole compound include 1H-triazole, 5-methyl-1H-triazole, 5-ethyl-1H-triazole, 4,5-dimethyl-1H-triazole, 5-phenyl-1H-triazole, 4-t-butyl-5-phenyl-1H-triazole, 5-hydroxyphenyl-1H-triazole, phenyltriazole, p-ethoxyphenyltriazole, 5-phenyl-1-(2-dimethylaminoethyl)triazole, 5-benzyl-1H-triazole, hydroxyphenyltriazole, 1,5-dimethyltriazole, 4,5-diethyl-1H-triazole, 1H-benzotriazole, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-benzotriazole, and the like. benzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole, 2-(3-t-butyl-5-methyl-2-hydroxyphenyl)-benzotriazole, 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, hydroxyphenylbenzotriazole, tolyltriazole, 5-methyl-1H-benzotriazole, 4-methyl-1H-benzotriazole, 4-carboxy-1H-benzotriazole, 5-carboxy-1H-benzotriazole, 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1H-tetrazole, 1-methyl-1H-tetrazole, etc. Particularly preferred are tolyltriazole, 5-methyl-1H-benzotriazole, and 4-methyl-1H-benzotriazole. These azole compounds may be used alone or in a mixture of two or more.

The amount of the azole compound is preferably 0.1 to 20 parts by mass per 100 parts by mass of the polyimide precursor (A), and more preferably 0.5 to 5 parts by mass from the viewpoint of photosensitivity characteristics. If the amount of the azole compound per 100 parts by mass of the polyimide precursor (A) is 0.1 parts by mass or more, discoloration of the copper or copper alloy surface is suppressed when the photosensitive resin composition is formed on copper or a copper alloy, while if the amount is 20 parts by mass or less, photosensitivity is excellent, which is preferable.

In order to suppress discoloration of copper, the photosensitive resin composition may contain a hindered phenol compound. Examples of the hindered phenol compound include 2,6-di-t-butyl-4-methylphenol, 2,5-di-t-butyl-hydroquinone, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 4,4'-methylenebis(2,6-di-t-butylphenol), 4,4'-thio-bis(3-methyl-6-t-butylphenol), 4,4'-butylidene-bis(3-methyl-6-t-butylphenol), triethylene glycol-bis [3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N'hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 2,2'-methylene-bis(4-methyl-6-t-butylphenol), 2,2'-methylene-bis(4-ethyl-6-t-butylphenol), pentaerythritol Lithyl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3-hydroxy-2,6-dimethyl-4-isopropylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-trione riazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris(4-s-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris[4-(1-ethylpropyl)-3-hydroxy-2,6-dimethylbenzyl]-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris[4-triethylmethyl-3-hydroxy-2,6-dimethylbenzyl]-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione,

1,3,5-tris(3-hydroxy-2,6-dimethyl-4-phenylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris(4-t-butyl-3-hydroxy-2,5,6-trimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris(4-t-butyl-5-ethyl-3-hydroxy 1,3,5-tris(4-t-butyl-6-ethyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris(4-t-butyl-6-ethyl-3-hydroxy-2,5-dimethylbenzyl)-1,3 ,5-triazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris(4-t-butyl-5,6-diethyl-3-hydroxy-2-methylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris(4-t-butyl-3-hydroxy-2-methylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione Examples of the triazine include, but are not limited to, 1,3,5-tris(4-t-butyl-3-hydroxy-2,5-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris(4-t-butyl-5-ethyl-3-hydroxy-2-methylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, etc. Among these, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione is particularly preferred.

The amount of the hindered phenol compound is preferably 0.1 to 20 parts by mass per 100 parts by mass of the polyimide precursor (A), and more preferably 0.5 to 10 parts by mass from the viewpoint of photosensitivity characteristics. If the amount of the hindered phenol compound per 100 parts by mass of the polyimide precursor (A) is 0.1 parts by mass or more, for example, when a photosensitive resin composition is formed on copper or a copper alloy, discoloration and corrosion of the copper or copper alloy is prevented, while if the amount is 20 parts by mass or less, photosensitivity is excellent, which is preferable.

The photosensitive resin composition may contain an organic compound containing a metal element selected from titanium or zirconium. The organic compound preferably contains one metal element selected from titanium or zirconium in one molecule. The organic group preferably contains a hydrocarbon group or a hydrocarbon group containing a heteroatom. By containing the organic compound, the imidization rate of the photosensitive resin composition increases and the dielectric tangent of the cured film decreases.

Usable organic titanium or zirconium compounds include, for example, those in which an organic chemical is bonded to a titanium or zirconium atom via a covalent or ionic bond.

Specific examples of the organic titanium or zirconium compound are shown below in I) to VII):
I) As the chelate compound, a compound having two or more alkoxy groups is more preferable because it provides the storage stability of the photosensitive resin composition and a good pattern. Specific examples of the chelate compound include titanium bis(triethanolamine)diisopropoxide, titanium di(n-butoxide)bis(2,4-pentanedionate), titanium diisopropoxide bis(2,4-pentanedionate), titanium diisopropoxide bis(tetramethylheptanedionate), titanium diisopropoxide bis(ethylacetoacetate), and compounds in which the titanium atom of these compounds is replaced with a zirconium atom, but are not limited thereto.

II) Examples of tetraalkoxy compounds include, but are not limited to, titanium tetra(n-butoxide), titanium tetraethoxide, titanium tetra(2-ethylhexoxide), titanium tetraisobutoxide, titanium tetraisopropoxide, titanium tetramethoxide, titanium tetramethoxypropoxide, titanium tetramethylphenoxide, titanium tetra(n-nonyloxide), titanium tetra(n-propoxide), titanium tetrastearyloxide, titanium tetrakis[bis{2,2-(allyloxymethyl)butoxide}], and compounds in which the titanium atoms of these compounds are replaced with zirconium atoms.

III) Examples of titanocene or zirconocene compounds include, but are not limited to, pentamethylcyclopentadienyltitanium trimethoxide, bis(η ⁵ -2,4-cyclopentadiene-1-yl)bis(2,6-difluorophenyl)titanium, bis(η ⁵ -2,4-cyclopentadiene-1-yl)bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium, and compounds in which the titanium atom of these compounds is replaced with a zirconium atom.

IV) Examples of monoalkoxy compounds include, but are not limited to, titanium tris(dioctylphosphate) isopropoxide, titanium tris(dodecylbenzenesulfonate) isopropoxide, and compounds in which the titanium atoms of these compounds are replaced with zirconium atoms.

V) Examples of titanium oxide or zirconium oxide compounds include, but are not limited to, titanium oxide bis(pentanedionate), titanium oxide bis(tetramethylheptanedionate), phthalocyanine titanium oxide, and compounds in which the titanium atoms of these compounds are replaced with zirconium atoms.

VI) Examples of titanium tetraacetylacetonate or zirconium tetraacetylacetonate compounds include, but are not limited to, titanium tetraacetylacetonate and compounds in which the titanium atoms of these compounds are replaced with zirconium atoms.

VII) Examples of titanate coupling agents include, but are not limited to, isopropyl tridodecylbenzenesulfonyl titanate.

Among the above I) to VII), the organotitanium compound is preferably at least one compound selected from the group consisting of the above I) titanium chelate compounds, II) tetraalkoxytitanium compounds, and III) titanocene compounds, from the viewpoint of exhibiting a better dielectric tangent. In particular, titanium diisopropoxide bis(ethylacetoacetate), titanium tetra(n-butoxide), and bis(η ⁵ -2,4-cyclopentadiene-1-yl)bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium are preferred.

When an organic titanium or zirconium compound is blended, the blending amount is preferably 0.05 parts by mass to 10 parts by mass, and more preferably 0.1 parts by mass to 2 parts by mass, per 100 parts by mass of the (A) resin. If the blending amount is 0.05 parts by mass or more, a good imidization rate of the photosensitive resin composition and a good dielectric loss tangent of the cured film are achieved, while if the blending amount is 10 parts by mass or less, the storage stability of the photosensitive resin composition is excellent, which is preferable.

｛一般式（１１）中、Ｘ¹及びＹ¹は、一般式（１）中のＸ₁及びＹ₁と同じであり、そしてｍは、正の整数である。｝で表されるものであることが好ましい。
一般式（１）中の好ましいＸ₁とＹ₁は、一般式（１１）で表されるポリイミドにおいても、同様の理由により好ましい。一般式（１１）の繰り返し単位数ｍは、特に限定は無いが、２～１５０の整数であってもよい。 [Polyimide]
The structure of the polyimide contained in the cured relief pattern (cured polyimide film) formed from the polyimide precursor composition is represented by the following general formula (11):

In the general formula (11), X ¹ and Y ¹ are the same as X ₁ and Y ₁ in the general formula (1), and m is a positive integer.
The preferred _X1 and _Y1 in the general formula (1) are also preferred in the polyimide represented by the general formula (11) for the same reasons. The number m of repeating units in the general formula (11) is not particularly limited, but may be an integer of 2 to 150.

Another embodiment of the present invention is a polyimide cured film for forming an interlayer insulating film for rewiring, which has a weight loss rate of 0.01% to 0.5% when heated to 320°C and a weight loss rate of 0.1% to 1.5% when heated to 350°C, and a dielectric loss tangent of 0.0021 to 0.0085 when measured at a frequency of 40 GHz using a perturbation split cylinder resonator method.

[Semiconductor device]
Yet another embodiment of the present invention is a semiconductor device having a cured relief pattern obtained by the above-mentioned method for producing a cured relief pattern, i.e., a semiconductor device having a substrate which is a semiconductor element and a cured relief pattern of polyimide formed on the substrate by the above-mentioned method for producing a cured relief pattern. The method for producing a polyimide cured film according to the present invention can also be applied to a method for producing a semiconductor device which uses a semiconductor element as a substrate and includes the above-mentioned method for producing a cured relief pattern as a part of the process. The semiconductor device of this embodiment can be produced by forming the cured relief pattern formed by the above-mentioned method for producing a cured relief pattern as a surface protective film, an interlayer insulating film, an insulating film for rewiring, a protective film for a flip chip device, a protective film for a semiconductor device having a bump structure, or the like, and combining it with a known method for producing a semiconductor device.

[Display device]
Yet another embodiment of the present invention is a display device including a display element and a cured film provided on the upper part of the display element, the cured film being the above-mentioned cured relief pattern. Here, the cured relief pattern may be laminated in direct contact with the display element, or may be laminated with another layer sandwiched therebetween. For example, the cured film may be a surface protection film, an insulating film, a planarizing film for a TFT liquid crystal display element and a color filter element, a protrusion for an MVA type liquid crystal display device, or a partition wall for a cathode of an organic EL element.

The method for producing a polyimide cured film according to the present invention is useful not only for application to the semiconductor devices described above, but also for applications such as interlayer insulation in multilayer circuits, cover coats for flexible copper-clad boards, solder resist films, and liquid crystal alignment films.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the examples, comparative examples, and production examples, various physical properties were measured and evaluated using the following measurement and evaluation methods.

[Measurement and evaluation methods]
(1) Weight-average molecular weight The weight-average molecular weight (Mw) of each resin was measured by gel permeation chromatography (standard polystyrene equivalent). The column used in the measurement was a "Shodex 805M/806M series" manufactured by Showa Denko K.K., the standard monodisperse polystyrene was "Shodex STANDARD SM-105" manufactured by Showa Denko K.K., the developing solvent was N-methyl-2-pyrrolidone, and the detector was "Shodex RI-930" manufactured by Showa Denko K.K.

(2) Measurement of Dielectric Constant (Dk) and Dielectric Loss Tangent (Df) A 100 nm-thick aluminum (Al) was sputtered onto a 6-inch silicon wafer (manufactured by Fujimi Electronics Co., Ltd., thickness 625±25 μm) using a sputtering device (L-440S-FHL type, manufactured by Canon Anelva Corporation) to prepare a sputtered Al wafer substrate.
The negative photosensitive resin composition was spin-coated on the sputtered Al wafer substrate using a spin coater (D-spin 60A type, manufactured by SOKUDO Corporation), and dried by heating at 110°C for 3 minutes to produce a spin-coated film. Thereafter, the entire surface was exposed to ghi rays at an exposure dose of 600 mJ/cm2 using an aligner (PLA-501F, manufactured by Canon Corporation), and a heat curing treatment was performed for 2 hours at a predetermined temperature under a nitrogen atmosphere using a vacuum gas replacement oven (450PB8-2P-CP, manufactured by YES Corporation) to produce a cured film. The film thickness of the cured film was measured using a step gauge (P-15, manufactured by KLA-Tenchore Corporation). This cured film was cut into a size of 80 mm length x 60 mm width or 40 mm length x 30 mm width using a dicing saw (manufactured by Disco, model name DAD-2H/6T), immersed in a 10% hydrochloric acid aqueous solution, and peeled off from the silicon wafer to obtain a film sample.

The relative dielectric constant and dielectric loss tangent of the film sample were calculated at 10, 28, 40, and 60 GHz by a resonator perturbation method. The details of the measurement method are as follows.
(Measurement method)
Perturbation split cylinder resonator method (device configuration)
Network analyzer: PNA Network analyzer E5224B
(Agilent Technologies)
Split cylinder resonator: CR-710 (manufactured by Kanto Electronics Application Development Co., Ltd., measurement frequency: about 10 GHz), CR-728 (manufactured by Kanto Electronics Application Development Co., Ltd., measurement frequency: about 28 GHz), CR-740 (manufactured by Kanto Electronics Application Development Co., Ltd., measurement frequency: about 40 GHz), CR-760 (manufactured by Kanto Electronics Application Development Co., Ltd., measurement frequency: about 60 GHz)

(3) Measurement of Weight Loss Rate The photosensitive resin composition was spin-coated on a 6-inch silicon wafer so that the film thickness after curing would be about 10 μm, and the wafer was pre-baked on a hot plate at 110° C. for 180 seconds. The wafer was then heated at 230° C. for 2 hours in a nitrogen atmosphere using a vacuum gas replacement oven (450PB8-2P-CP, manufactured by YES Co., Ltd.) to obtain a cured polyimide coating film. The film thickness was measured using a film thickness measuring device, Lambda Ace (manufactured by Dainippon Screen Co., Ltd.). The polyimide coating film obtained was scraped off, and the weight of the film when it reached 230° C. was measured using a thermogravimetric measuring device (manufactured by Shimadzu Co., Ltd., TGA-50) at a temperature rise of 10° C./min from room temperature. The weight of the film when it reached 230° C. was W ₂₃₀ , the weight of the film when it reached 320° C. was W ₃₂₀ , and the weight of the film when it reached 350° C. was W ₃₅₀ , according to the following formula:
320℃ weight loss rate (%) = (W ₂₃₀ - _{W 320} ) / W ₂₃₀
350℃ weight loss rate (%) = (W ₂₃₀ - _{W 350} ) / W ₂₃₀
were calculated, respectively.

[(A) Production of polyimide precursor]
<Production Example 1> (A) Synthesis of polyimide precursor (polymer A-1)
155.1 g of 4,4'-oxydiphthalic dianhydride (ODPA) was placed in a 2-liter separable flask, 134.0 g of 2-hydroxyethyl methacrylate (HEMA) and 400 ml of γ-butyrolactone were added, and 79.1 g of pyridine was added while stirring at room temperature to obtain a reaction mixture. After the heat generation due to the reaction had ceased, the mixture was allowed to cool to room temperature and then left to stand for another 16 hours.

Next, under ice cooling, a solution of 206.3 g of dicyclohexylcarbodiimide (DCC) dissolved in 180 ml of γ-butyrolactone was added to the reaction mixture over 40 minutes while stirring, followed by a suspension of 175.9 g of 2,2-bis{4-(4-aminophenoxy)phenyl}propane (BAPP) suspended in 350 ml of γ-butyrolactone, which was added over 60 minutes while stirring. After further stirring at room temperature for 2 hours, 30 ml of ethyl alcohol was added and stirred for 1 hour, after which 400 ml of γ-butyrolactone was added. The precipitate formed in the reaction mixture was removed by filtration to obtain a reaction liquid.

The reaction solution obtained was added to 3 liters of ethyl alcohol to produce a precipitate consisting of a crude polymer. The produced crude polymer was filtered and dissolved in 1.5 liters of tetrahydrofuran to obtain a crude polymer solution. The obtained crude polymer solution was purified using an anion exchange resin ("Amberlyst ^™ 15" manufactured by Organo Corporation) to obtain a polymer solution. The obtained polymer solution was dropped into 28 liters of water to precipitate the polymer, and the obtained precipitate was filtered and then vacuum dried to obtain a powdered polymer A-1.
The weight average molecular weight (Mw) of this polymer A-1 was measured and found to be 22000. The imide group concentration per repeating unit of the cured polyimide film obtained from polymer A-1 was 19.4 wt %.

<Production Example 2> (A) Synthesis of polyimide precursor (polymer A-2)
Polymer A-2 was obtained by carrying out the reaction in the same manner as in Production Example 1, except that 93.0 g of 4,4'-oxydianiline (ODA) was used instead of 175.9 g of BAPP in Production Example 1.
The weight average molecular weight (Mw) of this polymer A-2 was measured and found to be 22000. The imide group concentration per repeating unit of the cured polyimide film obtained from polymer A-2 was 27.4 wt %.

<Production Example 3> (A) Synthesis of polyimide precursor (polymer A-3)
Polymer A-3 was obtained by carrying out the reaction in the same manner as in Production Example 1, except that 260.2 g of 4,4'-(4,4'-isopropylidenediphenoxy) acid dianhydride (BPADA) was used instead of 155.1 g of ODPA, and 92.88 g of 2,2'-dimethylbiphenyl-4,4'-diamine (m-TB) was used instead of 175.9 g of BAPP in Production Example 1.
The weight average molecular weight (Mw) of this polymer A-3 was measured and found to be 23,000. The imide group concentration per repeating unit of the polyimide cured film obtained from polymer A-3 was 19.1 wt %.

<Production Example 4> (A) Synthesis of polyimide precursor (polymer A-4)
Polymer A-4 was obtained by carrying out the reaction in the same manner as in Production Example 1, except that 109.1 g of pyromellitic anhydride was used instead of 155.1 g of ODPA and 93.0 g of ODA were used instead of 175.9 g of BAPP in Production Example 1.
The weight average molecular weight (Mw) of this polymer A-4 was measured and found to be 20,000. The imide group concentration per repeating unit of the polyimide cured film obtained from polymer A-4 was 33.5 wt %.

[Production of photosensitive resin composition]
The following compounds were used in the examples.
Photoinitiator B-1: TR-PBG-3057 (manufactured by Changzhou Powerful Electronics Co., Ltd.)
Solvent D-1: γ-butyrolactone (GBL)

Example 1
A negative photosensitive resin composition was prepared using polyimide precursor A-1 by the following method. (A) 100 g of A-1 as a polyimide precursor, (B) 5 g of B-1 as a photopolymerization initiator, and (D) 100 g of D-1 were dissolved. The viscosity of the obtained solution was adjusted to about 40 poise by further adding a small amount of GBL to obtain a negative photosensitive resin composition. A cured film was prepared from the composition according to the above-mentioned method and evaluated. The heat curing step (step (5)) was performed at 230° C. for 2 hours at a pressure of 380 torr. The results are shown in Table 1 below.

<Examples 1 to 7 and Comparative Examples 1 to 4>
The composition was adjusted to the compounding ratio shown in Table 1 below, and the temperature and pressure in the heat curing step were also shown in Table 1, and the same evaluation as in Example 1 was carried out.

<Examples 8 and 9>
The compositions were prepared according to the compounding ratios shown in Table 1 below, and the same evaluations as in Example 1 were carried out using the pressures shown in Table 1. The heat curing step was carried out at 150° C. for 1 hour, and then the temperature was raised to 230° C. for 1 hour.

As can be seen from Table 1, the cured film of the embodiment had a low frequency dependency of the dielectric tangent. In addition, the weight loss rate when the cured film was heated to 320°C and 350°C was lower than that of the comparative example.

The method for producing a polyimide cured film according to the present invention can provide a cured film with low frequency dependence of the dielectric tangent and suppressed thermal weight loss at temperatures equal to or higher than the heat curing temperature. Therefore, the method for producing a polyimide cured film according to the present invention can be suitably used in fields such as semiconductor devices and multilayer wiring boards.

Claims (12)

The following steps:
(1) applying a photosensitive resin composition containing a polyimide precursor onto a substrate to form a photosensitive resin layer on the substrate;
(2) A step of drying and heating the obtained photosensitive resin layer;
(3) a step of exposing the obtained photosensitive resin layer;
(4) a step of developing the obtained photosensitive resin layer; and (5) a step of heating the photosensitive resin layer remaining on the substrate at 150° C. to 250° C. to form a cured film.
wherein the steps (2) and/or (5) are carried out under a pressure of 50 torr or more and 580 torr or less, and the polyimide in the obtained cured polyimide film has an imide group concentration, which is the ratio of imide groups to the molecular weight of a repeating unit containing a structure derived from a tetracarboxylic acid and a diamine, of 12 wt % to 30 wt %. The method for producing a polyimide cured film according to claim 1, wherein the cured film obtained in step (5) has a dielectric loss tangent of 0.001 to 0.007 at a frequency of 10 GHz as measured by a perturbation split cylinder resonator method. The method for producing a polyimide cured film according to claim 1 or 2, wherein step (5) is carried out under a pressure of 50 torr or more and 580 torr or less. The method for producing a polyimide cured film according to claim 3, wherein in step (5), when the set heat curing temperature is reached, the temperature change from the set temperature is 30.0°C or less. 5. The method for producing a polyimide cured film according to claim 3, wherein in the step (5), a pressure change is within 150 torr in a region in which the temperature change is 9.5° C./min or less. The method for producing a polyimide cured film according to any one of claims 1 to 5, wherein the weight loss rate of the obtained polyimide cured film when heated to 320°C is 0.01% to 0.5%. The method for producing a polyimide cured film according to any one of claims 1 to 6, wherein the weight loss rate of the obtained polyimide cured film when heated to 350°C is 0.1% to 1.5%. The obtained polyimide cured film had a molecular weight of 1.0 or more and a molecular weight of 1.0 or more.
0.001<(tanδ40-tanδ10)/tanδ10<0.2 (i)
The method for producing a polyimide cured film according to any one of claims 1 to 7, wherein the formula is satisfied: {wherein tan δ40 is the dielectric tangent at a frequency of 40 GHz as measured by a perturbation type split cylinder resonator method, and tan δ10 is the dielectric tangent at a frequency of 10 GHz as measured by a perturbation type split cylinder resonator method.} The polyimide precursor is represented by the following general formula (1):

In the formula, _X1 is a tetravalent organic group having 6 to 40 carbon atoms, _Y1 is a divalent organic group having 6 to 40 carbon atoms, _n1 is an integer from 2 to 150, and _R1 and _R2 are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, provided that at least one of _R1 and _R2 is represented by the following general formula (2):

(wherein R ₃ , R ₄ and R ₅ are each independently a hydrogen atom or a monovalent organic group having 1 to 3 carbon atoms, and m ₁ is an integer of 2 to 10). The method for producing a polyimide cured film according to any one of claims 1 to 9 , wherein the photosensitive resin composition contains a photopolymerization initiator. In the general formula (1), X ₁ is the following formula:

{wherein R6 is a monovalent group selected from the group consisting of a hydrogen atom, a fluorine atom, a C1-C10 hydrocarbon group, and a C1-C10 fluorine-containing hydrocarbon group, l is an integer selected from 0 to 2, m is an integer selected from 0 to 3, and n is an integer selected from 0 to 4.}. The method for producing a polyimide cured film according to claim 9 , wherein the polyimide has at least one of the structures represented by the following formula: In the general formula (1), X ₁ is the following formula:

The method for producing a polyimide cured film according to claim 9 , wherein the polyimide has at least one structure represented by the formula: {wherein * represents a connecting portion.}