WO2025183008A1 - Composition for fixing materials temporarily, laminate, and method for manufacturing semiconductor device - Google Patents

Abstract

Provided is a composition for fixing materials temporarily, the composition containing a polyamide acid and a solvent. The polyamide acid is constituted by a monomer comprising a tetracarboxylic acid dianhydride and a diamine. The monomer includes a monomer (A) having a structure represented by formula (1), at 10 mol% or more with respect to the total monomer. The monomer (A) contains a diamine (a1) represented by formula (1-1), at 9-40 mol% with respect to the total monomer.

Description

Temporary fixing material composition, laminate, and method for manufacturing semiconductor device

The present invention relates to a temporary fixing material composition, a laminate, and a method for manufacturing a semiconductor device.

In recent years, technological developments have been underway to stack semiconductor chips in order to increase the integration and density of semiconductor elements. Furthermore, in the field of power semiconductors, there is a need to reduce conduction loss in order to save energy. These demands have led to a need to reduce the thickness of semiconductor wafers to 100 μm or less.

The process of reducing the thickness of a semiconductor wafer (thinning process) is also known as backgrinding. Backgrinding of semiconductor wafers involves polishing the semiconductor wafer while it is fixed to a rigid support substrate (such as a glass substrate) to prevent cracking, and then performing processes such as backside circuit formation on the wafer, after which the processed semiconductor wafer is peeled off from the support substrate.

Various compositions are known as temporary fixing materials for fixing semiconductor wafers to support substrates. For example, compositions containing polyimide resin or its precursor are known (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2020-128452

Such a temporary fixing material composition is applied to a semiconductor wafer, and then the solvent is removed by heating, resulting in a film-like temporary fixing material (temporary fixing material layer).The semiconductor wafer and supporting substrate are then bonded together via this temporary fixing material layer.At this time, the temporary fixing material layer is heated to melt and soften it, thereby adhering the semiconductor wafer and supporting substrate together.

However, temporary fixing material compositions containing highly heat-resistant resins, such as those disclosed in Patent Document 1, require high film-forming temperatures when removing the solvent and forming a film. Furthermore, when bonding the support substrate, a high bonding temperature is required to melt or soften the temporary fixing material layer. This could potentially damage devices formed on the semiconductor wafer. From the perspective of reducing such damage to devices, there is a need for temporary fixing materials that have good film-forming properties that allow film formation even at low film-forming temperatures, and good bonding properties that allow the support substrate and semiconductor wafer to be bonded in close contact even at low bonding temperatures.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a composition for a temporary fixing material for obtaining a temporary fixing material with excellent film-forming and laminating properties. It also aims to provide a laminate obtained using the composition and a method for manufacturing a semiconductor device.

The above problem can be solved by the following configuration.
[1] A composition for a temporary fixing material, comprising a polyamic acid and a solvent, wherein the polyamic acid comprises a polyaddition unit of a diamine and a tetracarboxylic dianhydride, the monomer composed of the tetracarboxylic dianhydride and the diamine comprises a monomer (A) having a structure represented by formula (1) in an amount of 10 mol % or more relative to the total amount of the monomers, and the monomer (A) comprises a diamine (a1) represented by formula (1-1) in an amount of 9 mol % or more and 40 mol % or less relative to the total amount of the monomers.
Temporary fixing composition.
(In formula (1) and formula (1-1),
R ¹ to R ³ each represent a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms;
a to c are each an integer of 0 to 3,
m and n are each an integer of 0 to 3.
[2] The temporary fixing material composition according to [1], wherein the content of the diamine (a1) relative to the total amount of the monomers is 10 mol % or more and 35 mol % or less.
[3] The temporary fixing material composition according to [1], wherein the diamine further contains at least one of a diamine (a2) represented by formula (1-2) and a diamine (b) represented by formula (2).
(In formula (1-2) and formula (2),
R ¹ to R ⁵ each represent a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms;
a to e each represent an integer of 0 to 3,
Z is a divalent group selected from the group consisting of an oxygen atom, a ^methylene group, and ^-CRcRd ( ^Rc and ^Rd are each a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms), and m and n are each an integer of 0 to 3.
[4] The temporary fixing material composition according to [3], wherein a molar ratio (a1/a2+b) of the diamine (a1) to at least one of the diamine (a2) and the diamine (b) is 1/99 to 75/25.
[5] The temporary fixing material composition according to any one of [1] to [4], wherein the temporary fixing material composition has a glass transition temperature of 120 to 165°C when heated to imidize the polyamic acid and form a film.
[6] The temporary fixing material composition according to any one of [1] to [5], wherein the temporary fixing material composition has a melting temperature of 165 to 230°C in a melt viscoelasticity measurement when heated to imidize the polyamic acid and form a film.
[7] The temporary fixing material composition according to any one of [1] to [6], wherein the temporary fixing material composition has a loss tangent (tan δ) of 1 to 10 at 250°C when heated to imidize the polyamic acid and form a film.
[8] The temporary fixing material composition according to any one of [1] to [7], wherein the gradient of the loss tangent (tan δ) at 250 to 300°C when the temporary fixing material composition is heated to imidize the polyamic acid and form a film is 0.1 to 0.8.
[9] A laminate having a substrate and a temporary fixing material layer disposed on the substrate,
a laminate in which the temporary fixing material layer contains a polyimide containing a polycondensation unit of a diamine and a tetracarboxylic dianhydride, the monomer composed of the tetracarboxylic dianhydride and the diamine contains a monomer (A) having a structure represented by formula (1) in an amount of 10 mol % or more relative to the total amount of the monomers, and the monomer (A) contains a diamine (a1) represented by formula (1-1) in an amount of 9 mol % or more and 40 mol % or less relative to the total amount of the monomers.
(In formula (1) and formula (1-1),
R ¹ to R ³ each represent a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms;
a to c are each an integer of 0 to 3,
m and n are each an integer of 0 to 3.
[10] A method for manufacturing a semiconductor device, comprising: a step of applying the temporary fixing material composition according to any one of [1] to [8] onto a substrate, and then heating the composition to imidize the polyamic acid and form a temporary fixing material layer; a step of heating the temporary fixing material layer to a temperature equal to or higher than its melting temperature and bonding a support substrate; and a step of grinding a surface of the substrate to which the support substrate is bonded, on the side opposite to the temporary fixing material layer.

The present invention provides a temporary fixing material composition that exhibits excellent film-forming and laminating properties. It also provides a laminate obtained using the composition and a method for manufacturing a semiconductor device.

1A to 1F are schematic cross-sectional views showing a method for manufacturing a semiconductor device according to an embodiment of the present invention. 2A to 2D are schematic cross-sectional views showing a method for manufacturing a semiconductor device according to one embodiment of the present invention.

As a result of intensive research, the present inventors have found that a polyamic acid containing at least a predetermined amount of a monomer (monomer (A) having a structure represented by formula (1) described below) in which two ether bonds are bonded to a benzene ring at meta positions as a central skeleton, and which, within the monomer (A), contains a predetermined amount of a terminal meta-substituted monomer (diamine (a1) represented by formula (1-1) described below) in which an amino group and an ether group are bonded to a benzene ring at meta positions as a terminal skeleton, produces a polyimide having good thermal decomposition resistance (T _d5 ), a low glass transition temperature (Tg) suitable for film formation, and a low melting temperature suitable for lamination. The inventors have found that this allows for the production of a temporary fixing material with excellent film-forming properties and lamination properties.

On the other hand, among the monomers (A), there are terminal para-substituted monomers (such as the diamine (a2) described below) in which an amino group or an acid dianhydride group and an ether group are bonded at para positions relative to the benzene ring as a terminal skeleton, which have a flexible yet more rigid structure. In addition to the monomers (A), terminal para-substituted monomers such as pBAPP (such as the diamine (b) described below) also have a flexible yet more rigid structure.

Therefore, it is preferable to further adjust the molar ratio of terminal meta-substituted units to terminal para-substituted units in the monomers constituting the polyamic acid (for example, the molar ratio of diamine (a1) described below to the total amount of diamines (a2) and (b)), thereby further reducing the tangent loss (tan δ (250°C)) of the resulting polyimide in the high temperature range and its temperature-dependent variation. This makes it less likely that the temporary fixing material will melt and flow excessively, even in high-temperature processes at 250°C or higher, and makes it less likely that voids (air bubbles) will form. This further improves high-temperature adhesion and void resistance.

The following provides a detailed description of a temporary fixing material and a temporary fixing material composition according to one embodiment of the present invention. In this embodiment, a temporary fixing material used in the manufacture of semiconductor devices and a temporary fixing material composition for obtaining the same will be described as an example. Note that in this specification, a numerical range expressed using "to" means a range that includes the numerical values before and after "to" as the lower and upper limits.

1. Temporary Fixing Material Composition The temporary fixing material composition according to this embodiment contains a polyamic acid and a solvent.

1-1. Polyamic Acid Polyamic acid contains polyaddition units of tetracarboxylic dianhydride and diamine.

(Monomer (A))
The monomer composed of a tetracarboxylic dianhydride and a diamine (hereinafter also simply referred to as "monomer") includes a monomer (A) having a structure represented by the following formula (1).

In formula (1), ^R1 is a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms. Of these, a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms is preferred, and a methyl group is more preferred. Examples of the substituent include a halogen atom such as a fluorine atom.
a is an integer of 0 to 3, preferably 0 or 1.

As shown in formula (1), the monomer (A) has a structure in which two ether bonds are bonded to a benzene ring at meta positions as a central skeleton. Such a monomer (A) has moderate rigidity and high flexibility. This allows the Tg and melting temperature of the resulting polyimide to be lowered while maintaining the thermal decomposition resistance (T _d5 ). In other words, a temporary fixing material having a low Tg suitable for film formation and a low melting temperature suitable for lamination can be obtained.

The content of monomer (A) relative to the total amount of monomers is 10 mol% or more. When the content of monomer (A) is 10 mol% or more, the flexibility of the resulting polyimide can be further increased. As a result, the Tg and melting temperature of the resulting polyimide can be further reduced. The content of monomer (A) is preferably 15 mol% or more. There is no particular upper limit to the content of monomer (A), but from the perspective of further suppressing melting or softening at high temperatures, for example, 250°C or higher, it is preferably 60 mol% or less.

The monomer (A) contains a diamine (a1) represented by formula (1-1).

R ¹ to R ³ and a to c in formula (1-1) have the same meanings as R ¹ and a in formula (1), respectively.

In formula (1-1), m and n are each an integer from 0 to 3. It is preferable that m and n are each 0 or 1, and more preferably 0.

The content of diamine (a1) relative to the total amount of monomers is 9 mol% or more and 40 mol% or less. When the content of diamine (a1) is 9 mol% or more, the glass transition temperature (Tg) and melting temperature of the resulting polyimide can be further lowered. This allows the film formation temperature and lamination temperature of the temporary fixing material to be further lowered. When the content of diamine (a1) is 40 mol% or less, melting or softening of the resulting polyimide at high temperatures can be further suppressed. From the same perspective, the content of diamine (a1) is preferably 10 mol% or more and 35 mol% or less, and more preferably 20 mol% or more and 30 mol% or less.

The diamine (a1) represented by formula (1-1) has a structure in which an amino group and an ether bond are bonded to a benzene ring at meta positions not only in the central skeleton but also in the terminal skeleton. This results in greater flexibility, and the Tg and melting temperature of the resulting polyimide can be lowered.

Examples of diamine (a1) represented by formula (1-1) include 1,3-bis(3-aminophenoxy)-4-trifluorobenzene, 1,3-bis(3-aminophenoxy)-5-trifluorobenzene, 1,3-bis(3-amino-5-trifluoromethylphenoxy)benzene, 1,3-bis(3-amino-5-trifluoromethylphenoxy)-5-trifluoromethylbenzene, etc.

Monomer (A) may further contain a diamine or tetracarboxylic dianhydride other than those mentioned above.

For example, the monomer (A) may further contain a diamine (a2) represented by formula (1-2). The diamine (a2) has a terminal skeleton in which an amino group and an ether bond are bonded at para-positions relative to a benzene ring, and therefore has a more moderate rigidity than the diamine (a1). This allows the tan δ (250°C) of the resulting polyimide to be appropriately reduced, and the slope of tan δ at 250 to 300°C to be further reduced. This makes it difficult for the temporary fixing material to melt and flow, even during high-temperature processes, and makes it easier to maintain a moderate hardness, thereby further improving high-temperature adhesion. Furthermore, the formation of bubbles is also less likely, thereby further suppressing voids.

R ¹ to R ³ , a to c, m and n in formula (1-2) have the same meanings as R ¹ to R ³ , a to c, m and n in formula (1-1), respectively.

Examples of diamine (a2) represented by formula (1-2) include 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(4-aminophenoxy)-4-trifluorobenzene, etc.

The monomer (A) may further contain a tetracarboxylic dianhydride represented by formula (1-3).

R ¹ to R ³ , a to c, m and n in formula (1-3) have the same meanings as R ¹ to R ³ , a to c, m and n in formula (1-1), respectively.

(Other Monomers)
The monomers constituting the polyamic acid may further contain other monomers in addition to the monomer (A).

The other monomer is a monomer that does not have the structure represented by formula (1). From the standpoint of further increasing the thermal decomposition resistance of the resulting polyimide and further suppressing melting or softening at high temperatures, the monomer preferably includes a monomer that contains an aromatic ring (aromatic monomer).

Among these, the other monomer preferably includes at least one of a diamine (b) represented by formula (2) and a tetracarboxylic dianhydride (b') represented by formula (2'). This allows the resulting polyimide film to maintain its flexibility while further improving its thermal decomposition resistance and further suppressing melting or softening at high temperatures.

R ⁴ to R ⁵ , d to e, m and n in formulas (2) and (2′) have the same meanings as R ¹ to R ³ , a to c, m and n in formula (1-1), respectively.

X and Y in formulas (2) and (2') represent a divalent group selected from the group consisting of an oxygen atom, a methylene group, and -CR ^a R ^b (wherein R ^a and R ^b each represent a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms); -CR ^a R ^b is preferred, and -C(CH ₃ ) ₂ is more preferred.

Examples of diamine (b) represented by formula (2) include bis[4-(4-aminophenoxy)phenyl]methane and 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

Examples of tetracarboxylic dianhydride (b') represented by formula (2') include 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride) (pBPADA).

The total amount of diamine (b) represented by formula (2) and tetracarboxylic dianhydride (b') represented by formula (2') is not particularly limited, but is preferably 30 to 90 mol% based on the total amount of monomers. When this total amount is 30 mol% or more, the flexibility of the polyimide is maintained while further improving thermal decomposition resistance and reducing melting or softening at high temperatures. From the same perspective, it is more preferable that the total amount be 40 to 80 mol% based on the total amount of monomers.

The diamine (a1) represented by formula (1-1), the diamine (a2) represented by formula (1-2), the diamine (b) represented by formula (2), and the tetracarboxylic dianhydride represented by formula (2') all have aromatic rings and ether bonds. Because aromatic rings easily absorb laser light, polyimides having these structures have ether bonds that are easily decomposed by the heat generated by absorbing laser light, which also improves removability by LLO (laser lift-off).

The other monomer may include other diamines or other tetracarboxylic dianhydrides other than those mentioned above. Examples of other tetracarboxylic dianhydrides include aromatic tetracarboxylic dianhydrides having a biphenyl skeleton, such as 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA); aromatic tetracarboxylic acid dianhydrides having a diphenyl ether skeleton that do not fall under category 1-1); aromatic tetracarboxylic acid dianhydrides having a hexafluoroisopropylidene skeleton such as 2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride (6FDA); and aromatic tetracarboxylic acid dianhydrides having a fluorene skeleton such as 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF). These aromatic tetracarboxylic acid dianhydrides have appropriate rigidity, and therefore tend to further increase the thermal decomposition resistance (T _d5 ) of the resulting polyimide.

(composition)
Among the above monomers, the molar ratio (a1/a2+b) of the diamine (a1) represented by formula (1-1) to at least one of the diamine (a2) represented by formula (1-2) and the diamine (b) represented by formula (2) is not particularly limited, but is preferably 1/99 to 75/25, and more preferably 20/80 to 70/30. When the molar ratio of (a1) is equal to or greater than the lower limit, the Tg and melting temperature of the resulting temporary fixing material can be lowered, thereby further improving film-forming properties and lamination properties. When the molar ratio of (a1) is equal to or less than the upper limit, the molar ratio of (a2+b) becomes high, thereby making it possible to further reduce the tan δ (250°C) and tan δ slope of the resulting temporary fixing material, thereby further improving high-temperature adhesion and void resistance.

The proportion of aromatic monomer contained in the total amount of the above-mentioned monomers constituting the polyamic acid is not particularly limited, but from the viewpoint of further improving thermal decomposition resistance and further suppressing melting or softening at high temperatures, it is preferably 40 mol% or more, and may be 100 mol%.

(Physical Properties)
The molecular terminals of the polyamic acid may be either acid anhydride groups or amino groups. From the viewpoint of increasing the solubility of the temporary fixing material in a solvent, it is preferable that the proportion of molecular terminals that are acid anhydride groups is higher than the proportion of molecular terminals that are amino groups. On the other hand, from the viewpoint of increasing heat resistance, it is preferable that the proportion of molecular terminals that are amino groups is higher than the proportion of molecular terminals that are acid anhydride groups.

For example, to increase the proportion of molecular terminals that are acid anhydride groups, the amount of tetracarboxylic dianhydride (a moles) can be made greater than the amount of diamine (b moles). Specifically, the molar ratio of diamine (b moles) to tetracarboxylic dianhydride (a moles) contained in the polyamic acid is not particularly limited, but b/a is preferably 0.90 to 0.999, and may be 0.90 to 0.95. When b/a is 0.999 or less, the molecular terminals of the resulting polyimide are more likely to be acid anhydride groups, which makes it easier to increase the solubility of the film. b/a can be specified as the charge ratio of tetracarboxylic dianhydride (a moles) to diamine (b moles).

From the perspective of facilitating film formation, the intrinsic viscosity η of the temporary fixing material composition is preferably 0.3 to 2.0 dL/g, and more preferably 0.5 to 1.5 dL/g. The intrinsic viscosity (η) of the temporary fixing material composition is the average value measured three times using an Ubbelohde viscosity tube at 25°C when polyamic acid is dissolved in N-methyl-2-pyrrolidone (NMP) to a concentration of 0.5 g/dL.

The intrinsic viscosity (η) of the temporary fixing material composition can be adjusted by the molar ratio (b/a) of diamine (b moles) to tetracarboxylic dianhydride (a moles). By keeping the molar ratio (b/a) within the above range, it is possible to achieve an appropriate solids concentration while keeping η appropriately small, making it possible to form a thicker film-like temporary fixing material.

The solvent may be any solvent used in preparing polyamic acid, and is not particularly limited as long as it can dissolve the diamine and tetracarboxylic dianhydride. For example, aprotic polar solvents and alcoholic solvents can be used.

Examples of aprotic polar solvents include N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolidinone, 3-methoxy-N,N-dimethylpropanamide, gamma-butyrolactone, epsilon-caprolactone; and ether compounds such as 2-methoxyethanol, 2-ethoxyethanol, 2-(methoxymethoxy)ethoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol ... These include ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monoethyl ether, tetraethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, polyethylene glycol, polypropylene glycol, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether.

Examples of alcohol-based solvents include methanol, ethanol, 1-propanol, 2-propanol, tert-butyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol, diacetone alcohol, etc.

These solvents may be used alone or in combination of two or more. Among them, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, 3-methoxy-N,N-dimethylpropanamide, gamma-butyrolactone, dimethyl sulfoxide, or a mixed solvent of two or more of these are preferred.

The concentration of polyamic acid in the temporary fixing material composition is preferably 5 to 50% by mass, and more preferably 10 to 35% by mass, from the perspective of improving coatability, etc.

1-3. Physical Properties of the Temporary Fixing Material Composition The temporary fixing material composition preferably has a low Tg and melting temperature from the viewpoint of improving film-forming properties and lamination properties when heated to imidize the polyamic acid and form a polyimide-containing film (temporary fixing material).

Furthermore, from the viewpoint of improving high-temperature adhesion and void resistance even in high-temperature processes when made into the film, it is preferable that the temporary fixing material composition have small loss tangent (tan δ) and small temperature-dependent fluctuations. Furthermore, from the viewpoint of improving removability with a solvent when made into the film, it is preferable that the temporary fixing material composition also have good solubility.

In other words, the film obtained by heating the temporary fixing material composition preferably satisfies the following (1) and (2), and more preferably also satisfies (3) to (6).

(1) Glass transition temperature (Tg)
The Tg of the film is 120 to 165°C. When the Tg of the film is 120°C or higher, the molecules are less likely to move excessively during film formation, and the surface precision of the resulting coating film can be further improved. When the Tg of the film is 165°C or lower, the film formation temperature for removing the solvent and performing imidization can be lowered. From the same viewpoint, the Tg of the resulting film is preferably 125 to 165°C, and more preferably 130 to 160°C.

The Tg of the film can be measured by the following method.
The temporary fixing material composition is applied to a glass plate, heated from 50°C to 250°C at a rate of 5°C/min in the atmosphere, and held at 250°C for 30 minutes to imidize the polyamic acid, thereby obtaining a film. The obtained film is cut into a size of 5 mm wide and 22 mm long. The Tg of the cut film is measured using a thermal analyzer (e.g., TMA-50 manufactured by Shimadzu Corporation). Specifically, the measurement is performed in the atmosphere at a heating rate of 5°C/min in a tensile mode (100 mN) to obtain a TMA curve. The glass transition temperature (Tg) of the obtained TMA curve is determined by extrapolating the curve before and after the inflection point of the TMA curve due to the glass transition.

The Tg of the above film can be adjusted, for example, by the content of monomer (A) or the molar ratio (a1/(a2+b)) of diamine (a1) to diamine (a2) and/or diamine (b). For example, increasing the content of monomer (A) or the molar ratio (a1/(a2+b)) tends to lower the Tg of the film.

(2) Melting Temperature The melting temperature of the film is 165 to 230°C. When the melting temperature is 230°C or lower, the film exhibits melt fluidity at a relatively low temperature, making it easier to spread the film more uniformly over the entire bonding surface during lamination, thereby further improving lamination properties. When the melting temperature is 165°C or higher, the film is less likely to melt during film formation, making it possible to further improve the thickness precision of the coating film. From the same viewpoint, the melting temperature of the film is more preferably 170 to 225°C.

(3) Complex Viscosity As described above, the melt viscosity (complex viscosity) of the film at the melting temperature is 40,000 mPa·s or less. When the complex viscosity is 40,000 mPa·s or less, the viscosity is appropriately low when heated to the melting temperature or higher. Therefore, when, for example, a support substrate and a substrate are thermocompression-bonded via the film, the film is easily melted or softened, and therefore easily spreads uniformly and adheres. The lower limit of the complex viscosity is not particularly limited, but from the viewpoint of more stable support during processing of the substrate, it can be, for example, 1,000 mPa·s or more. From the same viewpoint, the complex viscosity of the film is preferably 1,000 to 30,000 mPa·s, more preferably 1,000 to 20,000 mPa·s, and even more preferably 2,000 to 15,000 mPa·s.

(4) Loss Tangent (tan δ) and Its Slope The tan δ (250°C) of the film is preferably 1 to 10. When tan δ (250°C) is 1 or more, the film can be more melted at the lamination temperature, thereby further improving lamination properties. On the other hand, when tan δ (250°C) is 10 or less, the film is less likely to melt even in a high temperature range of 250°C or higher, thereby enabling more stable support of the substrate even in high-temperature processes. From the same viewpoint, tan δ (250°C) is more preferably 2 to 9.

Furthermore, the slope of tan δ of the above film at 250 to 300°C is preferably 0.1 to 1. If the slope of tan δ is 0.1 or more, the above film can be more easily melted at the lamination temperature, thereby improving lamination properties. On the other hand, if the slope of tan δ is 1 or less, the melt fluidity is less likely to change with slight temperature changes, making it less likely that voids will occur even at high temperatures of 300°C or higher. From the same perspective, the slope of tan δ at 250 to 300°C is more preferably 0.1 to 0.8.

The melting temperature, complex viscosity and tan δ can be measured by melt viscoelasticity measurement.
First, the film prepared for Tg measurement is cut into a plurality of pieces each having a diameter of 15 to 25 mm, and these are stacked to form a sample having a thickness of 0.5 to 2 mm.
Next, the prepared sample is set in an ARES-G2 rheometer manufactured by TA Instruments, and heated to a predetermined temperature at a frequency of 1 Hz and a heating rate of 3°C/min, and the melt viscoelasticity is measured. In the obtained measurement results, when focusing on the temperature range higher than the glass transition temperature, the point at which the storage modulus and loss modulus become equal (the temperature at which tan δ = 1) is the melting point, and the temperature at this melting point is defined as the melting temperature. The melt viscosity at the melting temperature (melting point) is defined as the complex viscosity.

The melting temperature, complex viscosity, and tan δ of the above film can be adjusted, for example, by the content of diamine (a1) or the molar ratio (a1/(a2+b)) of diamine (a1) to diamine (a2) and/or diamine (b). For example, increasing the content or molar ratio (a1/(a2+b)) of diamine (a1) tends to lower the melting temperature and complex viscosity of the film. On the other hand, decreasing the content or molar ratio (a1/(a2+b)) of diamine (a1) tends to lower the tan δ and its slope of the film.

(5) 5% weight loss temperature (T _d5 )
From the same viewpoint as above, the 5% weight loss temperature (T _d5 ) of the film in an air atmosphere is preferably 400° C. or higher. The upper limit of T _d5 of the film is not particularly limited, but may be, for example, 600° C.

The 5% weight loss temperature (T _d5 ) of the sample can be measured using a thermogravimetric analyzer. Specifically, the film prepared for Tg measurement is cut into small pieces, and a sample (approximately 5 mg) is accurately weighed on the analyzer. The scanning temperature is set to 30 to 900°C, and the sample is heated at a temperature increase rate of 10°C/min in an air atmosphere while air gas is flowing at 50 mL/min. The 5% weight loss temperature (T d5 ) of the sample can be measured as the temperature at which the mass of the sample decreases by 5%.

(6) Solubility The film preferably has high solubility in a solvent, from the viewpoint of facilitating removal from a substrate after use. Specifically, the film prepared for Tg measurement is immersed in N-methyl-2-pyrrolidone at 80°C for 5 minutes, and then filtered through filter paper. The dissolution rate, expressed by the following formula, is preferably 90% or more, and more preferably 95% or more.
Dissolution rate (%) = [1 - [(weight of filter paper after filtration and drying) - (weight of filter paper before use)] / (weight of film before immersion)] x 100

The solubility can be measured by the following procedure.
First, the film was cut into a sample measuring 2.0 cm x 2.0 cm and 20 μm thick, and the weight of the sample (weight of the film before immersion) was measured in advance. The weight of the filter paper before use was also measured in advance.
Next, the sample is added to N-methyl-2-pyrrolidone (NMP) to a concentration of 1% by mass to prepare a solution, and the resulting solution is left to stand in an oven heated to 80°C for 10 minutes. Thereafter, the solution is removed from the oven, filtered through filter paper, and then dried under reduced pressure at 100°C. The weight of the filter paper after filtration and drying is then measured.
The obtained measured values are applied to the above formula to calculate the dissolution rate. These operations are carried out twice, and the average value is taken as the dissolution rate (%).

The solubility of the above film tends to increase, for example, by increasing the content of monomer (A) or by using diamine (b) represented by formula (2) or tetracarboxylic dianhydride (b') represented by formula (2'). Furthermore, decreasing the diamine/acid dianhydride ratio tends to increase the solubility of the resulting film.

The film-like material obtained by heating a coating of the temporary fixing material composition and imidizing the polyamic acid has a suitably low Tg, as well as a suitably low melting temperature and complex viscosity, as described above. Therefore, this film-like material can be suitably used as a temporary fixing material, for example, for semiconductor manufacturing.

2. Method for Manufacturing a Semiconductor Device FIGS. 1A to 1F and 2A to 2D are schematic diagrams showing a method for manufacturing a semiconductor device according to one embodiment of the present invention.

1A to 1F and 2A to 2D, the method for manufacturing a semiconductor device according to this embodiment includes the steps of: 1) applying a temporary fixing material composition to a substrate 11, followed by heating to form a temporary fixing material layer 12 (see FIGS. 1A and 1B); 2) bonding a support substrate 13 to the substrate 11 while heating the temporary fixing material layer 12 (see FIG. 1C); and 3) grinding the surface of the bonded substrate 11 opposite the temporary fixing material layer 12 (see FIGS. 1D and 1E). In this embodiment, the following steps may be further performed: 4) further processing the back surface of the ground substrate 11 (see FIG. 1F); 5) mounting the resulting substrate 11 on dicing tape 15 fixed to a dicing frame (see FIG. 2A); 6) irradiating the support substrate 13 with laser light to peel the support substrate 13 from the temporary fixing material layer 12 (see FIGS. 2B and 2C); and 7) dissolving and removing the remaining temporary fixing material layer 12 in a solvent (see FIG. 2D).

Step 1) The above-described temporary fixing material composition is applied onto a substrate 11, and then heated to form a temporary fixing material layer 12 (see FIGS. 1A and 1B).
Specifically, a temporary fixing material composition is applied onto a substrate 11, and then heated to imidize the polyamic acid, thereby forming a temporary fixing material layer 12. In this way, a laminate L1 including the substrate 11 and the temporary fixing material layer 12 containing polyimide is obtained (see FIG. 1B ).

The substrate 11 is preferably a semiconductor substrate containing at least one material selected from the group consisting of silicon, silicon carbide, gallium nitride, gallium oxide, and sapphire. The semiconductor substrate may be a substrate on which devices such as diodes, transistors, integrated circuits (ICs), and power elements are formed. The temporary fixing material layer 12 may be disposed on the circuit-forming surface, or on a surface different from the circuit-forming surface.

The temporary fixing composition can be applied by, for example, spin coating or spray coating.

The applied temporary fixing material composition can be heated, for example, using an oven or a hot plate. The heating temperature may be any temperature at which the solvent can be removed to the point where the polyamic acid contained in the temporary fixing material composition is imidized and forms a self-supporting film.

When imidizing in one step, imidization can be achieved by raising the temperature from 20-50°C to a temperature range of 180-300°C and holding the temperature at that temperature for a specified time. Specifically, the temperature to be reached is preferably 180-300°C, more preferably 200-300°C. The rate of temperature rise is preferably 1-20°C/min, more preferably 2-10°C/min. Furthermore, the holding time at the temperature is preferably 20-60 minutes, more preferably 20-30 minutes.

When imidization is carried out in two stages, the first stage is preferably at 50 to 150°C, more preferably at 50 to 120°C. The second stage is preferably at 150 to 350°C, more preferably at 200 to 300°C. The holding time in each stage is preferably 2 to 15 minutes, more preferably 2 to 10 minutes. There are no particular limitations on the temperature change or time between each stage.
The polyimide contained in the temporary fixing material layer 12 is an imidized version of the polyamic acid described above, and contains polycondensation units of diamine and tetracarboxylic dianhydride. The monomer composition is the same as above.

There are no particular restrictions on the thickness of the temporary fixing material layer 12, as long as it is thick enough to stably support the substrate 11 with the support substrate 13. The thickness of the temporary fixing material layer 12 can be, for example, approximately 1 to 100 μm.

Step 2) Next, the temporary fixing material layer 12 is heated to a temperature equal to or higher than its melting point, and a support substrate 13 is attached (see FIG. 1C).

The support substrate 13 may be any rigid substrate, such as a resin substrate, ceramic substrate, or glass substrate. From the perspective of performing LLO, the support substrate 13 is preferably a transparent support substrate such as a glass substrate. There are no particular restrictions on the thickness of the support substrate 13, but it is preferably thicker than the thickness of the temporary fixing material layer 12, and may be, for example, 50 to 1000 μm.

The heating temperature of the temporary fixing material layer 12 may be any temperature as long as it is equal to or higher than the melting temperature. The melting temperature refers to the melting temperature of the film obtained by heating the temporary fixing material composition described above. Specifically, the heating temperature during lamination can be equal to or higher than the melting temperature and equal to or lower than 350°C.

The method for heating the temporary fixing material layer 12 is not particularly limited, and can be performed using an oven, hot plate, or the like, as described above. A predetermined pressure may also be applied during lamination to achieve thermocompression bonding.

Step 3) Next, the surface (back surface) of the substrate 11 to which the support substrate 13 is bonded, opposite to the temporary fixing material layer 12, is ground (see FIGS. 1D and 1E ). As a result, the substrate 11 is thinned to a predetermined thickness or less.

Step 4) Next, the rear surface of the ground substrate 11 is further processed. For example, after ion implantation or annealing is performed on the rear surface of the ground substrate 11, a collector layer may be formed to form a transistor 14 (insulated gate bipolar transistor, IGBT) (see FIG. 1F). Alternatively, a resist may be formed on the rear surface of the ground substrate 11, and patterning may be performed.

Step 5) Next, the ground substrate 11 is mounted on a dicing tape 15 attached to a dicing frame using, for example, a wafer mounter (see FIG. 2A).

Step 6) Next, a step of irradiating a laser beam through the support substrate 13 to peel the support substrate 13 from the temporary fixing material layer 12 (see FIGS. 2B and 2C).

The laser light can have a wavelength of 200 to 360 nm (preferably 355 nm). When irradiated with laser light, the aromatic rings in the polyimide contained in the temporary fixing material layer 12 absorb the light and generate heat, which breaks the ether bonds and makes the layer easier to peel.

Step 7) After the support substrate 13 is peeled off, the remaining temporary fixing material layer 12 is brought into contact with a solvent, whereby the temporary fixing material layer 12 is dissolved in the solvent and removed (see FIG. 2D).

(effect)
In this embodiment, in step 1), the temporary fixing material layer 12 can be formed by applying a temporary fixing material composition and then heating it at a low film-forming temperature. In step 2), the temporary fixing material layer 12 has a low melting temperature, so it can be sufficiently melted even at a low bonding temperature, and the substrate 11 and the support substrate 13 can be favorably bonded together. As a result, the substrate 11 can be stably supported by the support substrate 13 during thinning processing without causing thermal damage to the substrate 11.

Furthermore, when the polyamic acid contained in the temporary fixing material composition further contains diamine (a2) or diamine (b), the temporary fixing material layer 12 can be made less likely to melt or soften excessively even at high temperatures. As a result, even during high-temperature processes such as steps 3) and 4), higher adhesion and void resistance can be obtained.

The present disclosure will be described below with reference to examples. The examples should not be construed as limiting the scope of the present disclosure.

1. Preparation of materials 1-1. Polyamic acid (monomer (A))
APB-N: 1,3-bis(3-aminophenoxy)benzene (diamine (a1))
TPE-R: 1,3-bis(4-aminophenoxy)benzene (diamine (a2))

(Other Monomers)
p-BAPP: 2,2-bis(4-(4-aminophenoxy)phenyl)propane (diamine (b))
Bisaniline M: 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene pBPADA: 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride) (tetracarboxylic dianhydride (b'))

1-2. Solvents NMP: N-methyl-2-pyrrolidone DMI: 1,3-dimethyl-2-imidazolidinone

2. Preparation of temporary fixing material composition [Examples 1 to 9, Comparative Examples 1 to 6]
Tetracarboxylic dianhydride and diamine of the type and amount (mol %) shown in Table 1 were blended into a solvent shown in Table 1. The resulting mixture was stirred at 45°C for 5 hours or more in a flask into which dry nitrogen gas could be introduced. As a result, a temporary fixing material composition, which was a polyamic acid varnish of the concentration shown in Table 1, was obtained.

3. Evaluation 3-1. Evaluation of temporary fixing material composition (viscosity)
The viscosity of the obtained temporary fixing material composition was measured at 25°C using an E-type viscometer.

(Intrinsic viscosity (η))
The obtained temporary fixing material composition was diluted with NMP so that the resin concentration was 0.5 g/dL, and the intrinsic viscosity η of the solution was measured three times using an Ubbelohde viscometer (size number 1) at 25°C in accordance with JIS K7367-1:2002, and the average value was used.

3-2. Evaluation of temporary fixing materials (production of temporary fixing materials)
The temporary fixing material composition was applied to a glass plate, and the temperature was increased from 50° C. to 250° C. at a rate of 5° C./min in the atmosphere, and then maintained at 250° C. for 30 minutes. As a result, the polyamic acid contained in the temporary fixing material composition was imidized, and a temporary fixing material that was a polyimide film was obtained.

(Glass transition temperature (Tg))
The prepared temporary fixing material was cut into a size of 5 mm wide and 22 mm long to prepare a sample. The glass transition temperature (Tg) of the obtained sample was measured using a thermal analyzer (e.g., TMA-50 manufactured by Shimadzu Corporation). Specifically, the temperature was raised from below 50°C to 250°C at a heating rate of 5°C/min in an air atmosphere, and measurement was performed in a tensile mode (100 mN) to obtain a TMA curve. In the obtained curve, the value of the glass transition temperature (Tg) was obtained by extrapolating the curve before and after the inflection point of the TMA curve due to the glass transition.
The glass transition temperature is an index for evaluating film-forming properties. If the glass transition temperature was 120° C. or higher and 165° C. or lower, it was evaluated as ◯, and if it was higher than 165° C., it was evaluated as ×.

(5% weight loss temperature (T _d5 ))
The 5% weight loss temperature (T _d5 ) of the sample was measured using a thermogravimetric analyzer (TGA-60) manufactured by Shimadzu Corporation. Specifically, the sample (approximately 5 mg) was accurately weighed on the analyzer, and the scanning temperature was set to 30 to 900°C. The sample was heated in an air atmosphere at a temperature increase rate of 10°C/min while flowing air gas at 50 mL/min. The temperature at which the sample mass decreased by 5% was defined as T _d5 .

(melting temperature, complex viscosity, tan δ)
The prepared temporary fixing material was cut into a plurality of pieces each having a diameter of 15 to 25 mm, and these were stacked to form a sample having a thickness of 0.5 to 2 mm.
Next, the prepared sample was placed in a TA Instruments ARES-G2 rheometer and heated to a predetermined temperature at a frequency of 1 Hz and a heating rate of 3°C/min, and the melt viscoelasticity was measured. In the obtained measurement results, the point at which the storage modulus and loss modulus become equal (the temperature at which tanδ = 1) in the temperature range above the glass transition temperature was determined as the melting point, and the temperature at this melting point was taken as the melting temperature. The melt viscosity at the melting temperature (melting point) was also taken as the complex viscosity. Furthermore, the values of tanδ at 250°C and 300°C were read, and the slope of tanδ from 250 to 300°C was calculated from these values.

The melting temperature was used as an index for evaluating lamination properties. A melting temperature of 165°C or higher and 230°C or lower was evaluated as ◯, and a melting temperature lower than 165°C was evaluated as x.
Tan δ (250°C) is an index for evaluating high-temperature adhesion. Tan δ (250°C) of 1 to 10 was judged as ◯, and tan δ of less than 1 or more than 10 was judged as △.
The slope of tan δ is an index for evaluating void resistance. If the slope of tan δ was 0.1 or more and 0.8 or less, it was judged as ⊚, if it was more than 0.8 and 1 or less, it was judged as ○, and if it was less than 0.1, it was judged as △.

(Resolubility)
The prepared temporary fixing material was cut into a size of 2.0 cm x 2.0 cm to prepare a sample.
Next, the sample was placed in N-methyl-2-pyrrolidone (in an amount such that the sample was 1% by mass), and the resulting solution was left to stand in an oven heated to 80°C for 10 minutes. The solution was then removed from the oven, and the state of dissolution of the sample was visually observed. If the solution did not waver or there was no sample residue when shaken, it was judged to be "soluble," and if the solution wavered or there was sample residue when shaken, it was judged to be "not soluble."

The compositions and evaluation results of the temporary fixing material compositions of Examples 1 to 9 and Comparative Examples 1 to 6 are shown in Table 1, and the evaluation results of the temporary fixing materials are shown in Table 2.

As shown in Table 1, the temporary fixing materials of Comparative Examples 1 to 6, which contain polyimide that does not contain at least monomer (A) or has a content of less than 10 mol%, have a high Tg of 170°C or higher and a high melting temperature.

In contrast, the temporary fixing materials of Examples 1 to 9, which contain polyimides containing 10 mol% or more of monomer (A) and 9 mol% to 40 mol% of diamine (a1), have a low Tg of 165°C or less and a relatively low melting temperature.

From these findings, it can be seen that the temporary fixing materials of Examples 1 to 9, which contain polyimide containing 10 mol% or more of monomer (A) and 9 mol% or more and 40 mol% or less of diamine (a1), have a low film formation temperature suitable for film formation and a low bonding temperature suitable for bonding.

In particular, it can be seen that by setting the molar ratio a1/(a2+b) to 25/75 or higher, high-temperature adhesion and void resistance can be further improved.

The present invention provides a temporary fixing material composition that exhibits excellent film-forming and laminating properties. It also provides a laminate obtained using the composition and a method for manufacturing a semiconductor device.

This application claims priority from Japanese Patent Application No. 2024-30356, filed February 29, 2024. The entire contents of the specification and drawings of that application are incorporated herein by reference.

REFERENCE SIGNS LIST 11 Substrate 12 Temporary fixing material layer 13 Support substrate 14 Transistor 15 Dicing tape L1 Laminate

Claims (10)

A temporary fixing material composition comprising a polyamic acid and a solvent,
The polyamic acid contains polyaddition units of diamine and tetracarboxylic dianhydride,
the monomer composed of the tetracarboxylic dianhydride and the diamine contains a monomer (A) having a structure represented by formula (1) in an amount of 10 mol % or more relative to the total amount of the monomers, and the monomer (A) contains a diamine (a1) represented by formula (1-1) in an amount of 9 mol % or more and 40 mol % or less relative to the total amount of the monomers;
Temporary fixing composition.
(In formula (1) and formula (1-1),
R ¹ to R ³ each represent a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms;
a to c are each an integer of 0 to 3,
m and n are each an integer of 0 to 3. the content of the diamine (a1) relative to the total amount of the monomers is 10 mol % or more and 35 mol % or less;
The temporary fixing material composition according to claim 1 . The diamine further includes at least one of a diamine (a2) represented by formula (1-2) and a diamine (b) represented by formula (2),
The temporary fixing material composition according to claim 1 or 2.
(In formula (1-2) and formula (2),
R ¹ to R ⁵ each represent a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms;
a to e each represent an integer of 0 to 3,
X is a divalent group selected from the group consisting of an oxygen atom, a ^methylene group, and ^-CRcRd ( ^Rc and ^Rd are each a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms), and m and n are each an integer of 0 to 3. the molar ratio (a1/a2+b) of the diamine (a1) to at least one of the diamine (a2) and the diamine (b) is 1/99 to 75/25;
The temporary fixing material composition according to claim 3 . The temporary fixing material composition has a glass transition temperature of 120 to 165°C when heated to imidize the polyamic acid and form a film.
The temporary fixing material composition according to any one of claims 1 to 4. The temporary fixing material composition has a melting temperature of 165 to 230°C in a melt viscoelasticity measurement when heated to imidize the polyamic acid and form a film.
The temporary fixing material composition according to any one of claims 1 to 5. the temporary fixing material composition has a loss tangent (tanδ) of 1 to 10 at 250°C when heated to imidize the polyamic acid and form a film;
The temporary fixing material composition according to any one of claims 1 to 6. The temporary fixing material composition has a slope of loss tangent (tanδ) of 0.1 to 0.8 at 250 to 300°C when the temporary fixing material composition is heated to imidize the polyamic acid and form a film.
The temporary fixing material composition according to any one of claims 1 to 7. A laminate,
A substrate and a temporary fixing material layer disposed on the substrate,
the temporary fixing material layer contains a polyimide containing a polycondensation unit of a diamine and a tetracarboxylic dianhydride,
the monomer composed of the tetracarboxylic dianhydride and the diamine contains a monomer (A) having a structure represented by formula (1) in an amount of 10 mol % or more relative to the total amount of the monomers, and the monomer (A) contains a diamine (a1) represented by formula (1-1) in an amount of 9 mol % or more and 40 mol % or less relative to the total amount of the monomers;
Laminate.
(In formula (1) and formula (1-1),
R ¹ to R ³ each represent a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms;
a to c are each an integer of 0 to 3,
m and n are each an integer of 0 to 3. a step of applying the temporary fixing material composition according to any one of claims 1 to 8 onto a substrate, and then heating the composition to imidize the polyamic acid, thereby forming a temporary fixing material layer;
a step of heating the temporary fixing material layer to a melting temperature or higher to bond a support substrate;
grinding a surface of the substrate to which the support substrate is bonded, the surface being opposite to the temporary fixing material layer;
Including,
A method for manufacturing a semiconductor device.