JP2008518460A - Restoration of hydrophobicity of low-K and ultra-low-K organic silicate films used as intermetallic dielectrics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for restoring hydrophobicity of low-k and extremely low-k organic silicate films used as an intermetallic dielectric.
Often used to reduce RC delay in integrated circuits is a porous organic silicate dielectric film, which is directly bonded to the Si atoms in the silica-like skeleton and its network structure. Has an alkyl or aryl group (to impart hydrophobicity to the material and create voids). Si-R bonds rarely survive the plasma exposure or chemical treatment normally used in processing, and this is especially true for materials having an open pore structure. When the Si-R bond is broken, the material loses hydrophobicity due to the formation of hydrophilic silanol and the low dielectric constant is compromised. Having the general formula (R ₂ N) _X SiR ′ _Y , wherein X and Y are integers from 1 to 3 and 3 to 1, respectively, and R and R ′ are hydrogen, alkyl, aryl, allyl And a novel class of silylating agents selected from the group consisting of vinyl moieties and methods for restoring the hydrophobicity of the material are disclosed. As a result of the silylation treatment, the mechanical strength of the porous organic silicate is also improved.
[Selection] Figure 10

Description

  The present invention relates to interconnect wiring networks on very high performance microelectronic chips used in computers, microprocessors, microcontrollers, sensors, communication equipment, and the like. In particular, the inventive structure described herein relates to significantly reducing signal propagation delays associated with these interconnects. The method of the present invention, detailed and claimed, describes the chemistry and processing methods required to restore the dielectric properties of a low dielectric constant dielectric after it has been rendered hydrophilic by the necessary plasma exposure, as well as porous organics. Provides the chemistry and methods needed to increase its mechanical strength and maintain a low dielectric constant after the silicate dielectric has been deposited and during the process of building the interconnect structure containing these films To do. The invention further relates to a method that allows these materials to be successfully integrated into such a chip.

  High-performance microprocessors, microcontrollers and communication chips enable very fast interaction between active transistor devices used to perform various functions such as logic operations, data storage and retrieval, and supply of control signals. Requires a connection. As transistor device technology advances to the current ultra-large scale integration, the overall computational speed of these advanced chips is beginning to be limited by signal propagation delays in the interconnect wiring between the individual devices on the chip. The signal propagation delay in the interconnect depends on the RC product, where R represents the resistance of the interconnect wiring and C represents the overall capacitance of the interconnect mechanism in which the wiring is embedded. By using copper as the interconnect wiring material instead of aluminum, it became possible to reduce the contribution of resistance to the RC product. The current focus in the microelectronics industry is to reduce the capacitance of the interconnect by using lower dielectric constant (k) insulators when building multilayer interconnect structures on a chip. is there.

One prior art method for fabricating interconnect wiring networks on such a small scale is the dual damascene (DD) process schematically illustrated in FIGS. Referring to FIG. 1, in a standard DD process, an intermetal dielectric (IMD), shown as two layers 1110, 1120, is coated on a substrate 1100. Via level dielectric 1110 and line level dielectric 1120 are shown separately for clarity of the process flow description. In general, these two layers can be made of the same or different insulating films, and in the former case are applied as a single monolithic layer. A hard mask layer or stack 1130 is optionally used to promote etch selectivity and to function as a polishing stop. The wiring interconnect network consists of two types of features: line features that span distances across the chip, and via features that connect lines in different levels of interconnect in a multi-level stack. Historically, both layers are made from inorganic glasses such as silicon dioxide (SiO ₂ ) or fluorinated silica glass (FSG) deposited by plasma enhanced chemical vapor deposition (PECVD).

  Referring to FIGS. 2 and 3, in a dual damascene process, the locations of lines 1150 and vias 1170 are lithographically defined in photoresist layers 1500 and 1510, respectively, and a hard ion is formed using a reactive ion etch process. Transferred into the mask layer and the IMD layer. The process sequence shown in FIGS. 1 to 4 is called the “line first” method. As shown in FIG. 4, after forming the trench, a via pattern 1170 is defined in the photoresist layer 1510 using lithography and the pattern is transferred to a dielectric material to create a via opening 1180. A dual damascene trench and via structure 1190 after the photoresist has been removed is shown in FIG.

  As shown in FIG. 6, the indentation structure 1190 is then coated with a conductive liner material or material stack 1200, which functions to protect the conductor metal lines and vias, and the conductor It functions as an adhesive layer between IMD and IMD. This depression is then filled with a conductive filler material 1210 that covers the surface of the patterned substrate. This filling is most commonly achieved by electroplating copper, but other methods such as chemical vapor deposition (CVD) and other materials such as aluminum or gold can also be used. Next, the filler material and liner material are polished by chemical mechanical polishing (CMP) to be flush with the surface of the hard mask, the structure at this stage is shown in FIG. As shown in FIG. 7, capping material 1220 is deposited as a blanket film, which protects the exposed metal surface and diffuses between the metal and any additional IMD layers deposited thereon. Acts as a barrier. Silicon nitride, silicon carbide, and silicon carbonitride films deposited by PECVD are commonly used as capping material 1220. This process sequence is repeated for each level of interconnection on the device. This process is called a dual damascene process because the two interconnect features are defined simultaneously to form a conductor embedded in the insulator in a single polishing step.

In order to reduce the capacitance, smaller k dielectrics, for example PECVD or spin-on organic silicates with k values in the range of 2.5 to 3.1, can be used with PECVD silicon dioxide based dielectrics. It is necessary to use it instead of the field (k = 3.6 to 4.1). These organic silicates have a silica-like skeleton in which organic groups such as hydrogen and / or alkyl or aryl groups are directly bonded to Si atoms in the network structure. These elemental compositions usually consist of various proportions of Si, C, O, and H. C and H are most often present in the form of a methyl group (—CH ₃ ). The primary function of these methyl groups is to impart hydrophobicity to the material. The second function is to create voids in these films and reduce their polarizability. The k value can be further reduced to 2.2 (very low k) and even less than 2.0 (extremely low k) by introducing porosity into these insulators. For the sake of brevity, these ultra low k and extremely low k materials are collectively referred to herein as ultra low k materials.

  This range of k-materials allows the k-value range to be adjusted, but these materials can be integrated with copper interconnects by the dual damascene process described above or by any other modification of the dual damascene process. There are some difficulties to do. The main difficulty is that organosilicate-based materials are very sensitive to plasma exposure because the oxidation or cleavage of Si-organic group bonds (eg, Si-methyl) is relatively This is because, as a result, silanol (Si—OH) groups are formed in the film by a possible reaction with moisture in the surrounding atmosphere. Silanol absorbs water, thus significantly increasing the dielectric constant and dielectric loss factor of the film, thus negating the performance benefits expected from very low k films. Silanol also increases electrical leakage in the membrane, thus creating a potentially unreliable interconnect structure. As noted above, reactive ion etching and plasma etching are important steps required in the formation of dual damascene trench and via structures and in the removal of the photoresist used to pattern very low k materials. Avoiding plasma damage of this type of film during prior art dual damascene integration is very difficult if not impossible.

He, using the resist removing plasma nonoxidizing consisting some or all of such H _2, N 2, _CO, and several attempts to minimize the hydrophobic losses in the low k film is made Yes. However, it should be noted that none of these plasma chemistries have been fully successful in avoiding the loss of hydrophobicity of very low k materials. This is especially true for porous low-k materials that have a very large surface area and are susceptible to damage during the resist removal process.

  Another way to avoid loss of hydrophobic and dielectric properties of low-k materials is a fluorinated or non-fluorinated organic polymer that is less susceptible to damage during the traditional process plasma exposure associated with dual damascene processing. Base low-k materials such as Dow Chemical's SiLK® dielectric, Honeywell's Flare® and other polyimides, benzocyclobutene, polybenzoxazole, polyphenylene ether based aromatic thermosets And use of chemical vapor deposition polymers such as polyparaxylylene. However, these materials do not have other properties required for low-k dielectric films, such as low thermal expansion and small pore size.

  Another problem facing the successful integration of organic silicate-based porous materials is that they are mechanically very fragile due to their low modulus, fracture strength and hardness, during CMP, dicing and packaging operations Often leads to damage. The mechanical strength of these resins depends on both the void volume and their chemical structure. Their mechanical strength decreases as the porosity increases and as the cage structure of the siloxane skeleton increases. Since maintaining a low dielectric constant is inevitable, it is very difficult to reduce the void volume while maintaining the same mechanical strength.

  Several methods of handling porous organic silicate materials with low mechanical strength (Non-Patent Document 1 by Padhi et al. And Patent Document 1 by Canaperi et al. Assigned to the same assignee as the present invention) have been proposed. However, most of these methods are difficult to implement due to the fact that these methods include non-standard process flows or non-standard tools. They are therefore too expensive to carry out in the manufacturing stage.

  In the literature on porous silica-based membranes (eg, Non-Patent Document 2 by Prakash et al.), Surface modification that introduces hydrophobic end groups during film formation is the surface tension of silylating agent (trimethylchlorosilane-TMCS). Is achieved by wet chemical treatment introduced into the porous network by a low carrier solvent. Such a reaction is called silylation and can be performed on the film during the formation process because there are a large amount of voids and abundant silanols that will otherwise condense and crosslink. Because. So far, similar reactions have been carried out on fully formed films with fewer silanol groups than in the film during the formation process, even after exposure to chemicals in the process that damage the film. Whether it can be done is not clear. In a study published by Chang et al. (Non-Patent Document 3), an attempt was made to restore the hydrophobicity and carbon content of porous OSG films after damage using hexamethyldisilazane (HMDS) as a silylating agent. Yes. However, it is clear from their results that HMDS in any medium cannot fully restore the performance of the porous OSG film. Similarly, TMCS is also not fully effective in restoring dielectric properties. HMDS and TMCS are both monofunctional silylating agents and can only attack one isolated silanol group per molecule on the surface and pore walls of low-k materials. However, organosilicate-based low-k materials have two different types of silanols classified as follows (Gun'ko et al., 4). The first type of silanol is a non-hydrogen bonding silanol, and as such, (1) a single silanol that has no adjacent silanols in the vicinity and is completely uninteractive (also called an isolated silanol), It consists of (2) very weakly interacting silanols, and (3) weakly interacting and non-interacting geminal silanols (also called disilanols). The second type of silanol is hydrogen bonded silanol. Most monofunctional silylating agents readily attack and replace isolated silanols, but generally do not attack the other two types of non-hydrogen bonding silanols as easily. The main factor for this is that the steric hindrance prevents more than one silanol from being easily and simultaneously captured by the monofunctional silylating agent. It is also important to use a silylating agent with the most reactive function that readily silylates the surface and pore walls of low-k materials without releasing corrosive reaction byproducts.

  Hu et al. (Non-Patent Document 5) also published a study investigating the efficiency of dimethyldichlorosilane (DMDCS) as a silylating agent to restore the properties of low-k materials. However, in their studies, it has been reported that dimethyldichlorosilane forms a monolayer on the outermost surface of the membrane and does not penetrate the bulk portion of porous low-k materials. Therefore, it is difficult to restore the bulk dielectric properties of low-k materials unless a suitable silylation medium and silylation conditions are used. In addition, any chlorine-based silylating agent, such as dimethyldichlorosilane and TMCS, is a by-product of hydrogen chloride, which is corrosive and cannot be used in interconnect structures containing copper. .

US Patent Application Publication No. US2004 / 0087135A1 Padhi et al. Electrochem. Soc. , 150 (1), G10-G14, (2003). Prakash et al., Nature, 374, 439 (1995). Chang et al. Electrochem. Soc. 149, 8, F81-F84 (2002). Gun'ko et al. Colloid and Interface Sci. 228, 157-170 (2000). Hu et al. of Electrochem. Soc. , 150 (4) F61-F66 (2003).

  Accordingly, one aspect of the present invention is to provide a low-cost, non-destructive method that increases the mechanical strength by changing the cage to network ratio of the porous organic silicate resin after deposition and curing. is there.

  Accordingly, one object of the present invention is to provide a process flow that utilizes certain types of silylating agents and their utilization to fully restore the hydrophobicity of the material after process exposure without producing corrosive by-products. And to provide. It is a further object of the present invention to provide a method by which the silylating agent of the present invention can be introduced so as to penetrate the bulk portion of the porous low-k material and restore its properties.

  A further object of the present invention is to modify the resin chemistry after deposition and pore formation so as to increase mechanical strength and overcome some major obstacles facing successful integration of porous organic silicates. That is.

  In the present invention, the method of changing the cage-to-network ratio also introduces siloxane bonds that form new networks in the film, thus improving the mechanical properties without significantly increasing the dielectric constant. By However, in order for the silylation reaction to proceed, it is necessary that the organic silicate film has abundant silanols. It is also an object of the present invention to produce these silanols prior to silylation and to ensure that the silylation reaction occurs to a sufficient extent to strengthen the membrane.

  An advantage of the present invention is that material selection for ultra-low-k intermetal dielectrics need not be constrained to account for the effects of plasma and wet cleaning damage to these materials because This is because by using the silylation method taught in the present invention, the original properties of the material can be restored after being damaged. In addition, the availability of a reliable method for recovering the properties of films damaged by plasma exposure allows for reactive ion etching (RIE) and resist removal operations required in dual damascene construction. More process options are possible, resulting in a more robust and lower cost processing method. Finally, the present invention provides a method for improving the mechanical strength of porous organic silicate membranes used as IMD.

Accordingly, the present invention is an organic silicate film having a low k or extremely low k dielectric constant having a hydrogen atom or an alkyl or aryl group bonded to a silicon atom, and is extremely low in a semiconductor chip, a chip carrier, or a semiconductor wafer. Although used as an insulating layer of dielectric constant, it is directed to a method for recovering the properties of an organic silicate film that has undergone a treatment that tends to degrade its properties. The method includes the step of applying a silylating agent comprising aminosilane to the membrane to render the membrane hydrophobic. The aminosilane can have the general formula (R ₂ N) _X SiR ′ _Y , where X and Y are integers from 1 to 2 and 2 to 1, respectively, R and R ′ are hydrogen, Selected from the group consisting of alkyl, aryl, allyl, phenyl and vinyl moieties. The aminosilane is preferably bis (dimethylamino) dimethylsilane.

The aminosilane can have the general formula (R ₂ N) _X SiR ′ _Y R ″ _Z , where X, Y and Z are from 1 to 3, from 3 to 1, and from 1 to 3, respectively. R, R ′ and R ″ are integers and are either hydrogen, alkyl or aryl, allyl, phenyl or vinyl moieties.

The present invention is also directed to the same general method comprising the step of applying a silylating agent to the membrane to render the membrane hydrophobic, said silylating agent having the form R _X H _Y Si-A. Wherein X and Y are integers from 0 to 2 and 3 to 1, respectively, R is any of a hydrogen, alkyl or aryl, allyl, phenyl or vinyl moiety, and A is a silazane. A chloro, amino or alkoxy moiety. The silylating agent can include an amino, chloro or alkoxy terminated monofunctional terminal silylating agent wherein the methyl portion of the silylating agent is at least partially substituted with a hydrogen analog. The silylating agent can also include polymerized siloxanes having amino, alkoxy, chloro or silazane terminal groups. The terminal group of the polymerized siloxane can contain mono- or dialkyl, aryl, vinyl or hydrogen moieties. The siloxane can include an amino-terminated polydimethylsiloxane.

The silylating agent can also have the general formula R _X H _Y Si _Z A, where X and Y are integers from 0 to 5 and 6 to 1, respectively, and Z is from 1 to Equal to 2, R is a hydrogen, alkyl, aryl, allyl, phenyl or vinyl moiety and A is a silazane, chloro, amino or alkoxy moiety.

  In accordance with the present invention, the processing step can include etching the film and removing the photoresist material from the film, wherein the silylating agent is applied after the etching and removal steps. The etching and removal steps can be performed by exposing the film to plasma. Single damascene or dual damascene processes can be used and the step of applying a silylating agent can be performed after the definition of at least one of the interconnect lines and vias and prior to the deposition of the conductors. . The application of the silylating agent can be performed prior to the deposition of the conductive liner.

  The silylating agent is preferably by one of liquid spin coating, immersion of the substrate in liquid, spray coating of the substrate with liquid, dissolution in the gas phase, or supercritical carbon dioxide, preferably , Alkane, alkene, ketone, ether, and co-solvent selected from the group comprising at least one of esters. It is important to apply the silylating agent in the absence of moisture. The film can be annealed at a temperature of preferably at least 350 ° C. or as high as 450 ° C. for a time exceeding 1 minute. The annealing step can be performed before or after applying the silylating agent. The silylating agent is preferably applied at a temperature of at least 25 ° C. The annealing step is performed to promote at least one of condensation of unsilylated silanol in the film and formation of additional siloxane bonds.

The silylating agent can be dissolved in a solvent comprising a low surface tension nonpolar organic solvent selected from the group comprising alkanes, alkenes, ketones, ethers, esters, or any combination thereof. The solvent preferably has a sufficiently low surface tension to penetrate the pores in the membrane. The silylating agent preferably has a concentration between 2 and 10 weight percent in the solvent, but may have a concentration as low as one-half weight percent or more in the solvent. Good.

  The silylating agent can be applied at a temperature between room temperature and above for a time between 1 minute and 1 hour. When applying the silylating agent, stirring or sonication can be utilized. The membrane can be rinsed to remove excess silylating agent. The membrane can be baked preferably at temperatures up to 450 ° C.

The silylating agent can be applied in the gas phase at temperatures between room temperature and 450 ° C. over a period of 30 seconds to 1 hour or substantially at 250 ° C. for 5 minutes. The silylating agent can be applied in supercritical carbon dioxide at a temperature between 25 ° C. and 450 ° C. at a pressure between 1,000 and 10,000 psi over a period of 30 seconds to 1 hour. it can. The silylating agent can also be applied in supercritical carbon dioxide or gas phase media at temperatures in excess of 75 ° C. over a period of more than 30 seconds.
The silylating agent preferably has two functional groups. This can include (bis) dimethylaminodimethylsilane or (bis) dimethylaminomethylsilane.

  The step of applying a silylating agent is performed following treatment of the film by introducing silanol into the film, exposure to ultraviolet radiation, exposure to ozone, exposure to a mild oxidizing plasma, or combinations thereof. The method can be performed in a chemical vapor deposition chamber or an atomic layer deposition chamber.

  The properties recovered by the method according to the present invention include at least one of hydrophobicity, elastic modulus, low dielectric constant, breakdown strength and hardness, dielectric breakdown strength, low dielectric leakage and dielectric reliability. Interconnect structures with such recovered films integrated therein are silicon dioxide, fluorinated tetraethylorthosilicate, fluorinated silica glass, fluorinated or non-fluorinated organic polymers, thermosetting resins, and One or more intermetallic dielectrics selected from the group consisting of chemical vapor deposition polymers can additionally be included. The thermosetting polymer can be based on polyphenylene ether. The chemical vapor deposition polymer can be polyparaxylylene. The additional intermetallic dielectric can be an organic polymer selected from the group of polyimide, benzocyclobutene, polybenzoxazole, aromatics.

  The present invention also describes an intermetallic dielectric comprising an insulating material having a plurality of conductors formed therein, an organic silicate film having a hydrogen atom or an alkyl or aryl group bonded to a silicon atom, and the above method And a surface of the organic silicate film comprising a reaction product between one of the silylating agents and the organic silicate film. The article can be formed as a semiconductor chip, a semiconductor chip carrier or a semiconductor wafer. The surface may be the outer surface of the membrane or the surface of the pores in the membrane.

  These and other aspects, features and advantages of the present invention will become apparent upon further understanding and understanding of the following detailed description of the invention together with the accompanying drawings.

  The variations described with respect to the present invention can be understood in any combination desired for each particular application. Thus, certain limitations and / or embodied improvements described herein may have particular advantages for particular applications, but need not be used for all applications. It is also to be understood that not all limitations need to be satisfied in a method, system and / or apparatus that includes one or more concepts of the invention.

  The first embodiment of the present invention (hereinafter referred to as “Embodiment 1”) relates to the use of a novel class of silylating agents which are silylating agents that are extremely effective in restoring dielectric properties. In addition, Embodiment 1 of the present invention also treats these silylating agents to ensure that the outer surface and bulk portion (including all inner pore walls) of the porous low-k material becomes hydrophobic. The present invention relates to a method to be introduced into a process. Finally, the second embodiment of the present invention discloses specific molecular modifications to make more effective as silylating agents for parts such as silazanes used in the prior art.

In Embodiment 1 of the present invention, the silylating agent of the present invention can be used in a single or dual damascene process to build an interconnect structure, after the definition of interconnect lines and vias, and the conductive liner and interconnect. Introduced prior to the deposition of the filler material including the connecting metal. Specifically, the silylating agent is introduced after the resist is removed following reactive ion etching (RID) of the low-k material. When a dual damascene scheme as shown in FIG. 1 is used, the silylating agent of the present invention is introduced between the process steps of FIGS. The silylating agents detailed in this invention can be used in interconnect structures having dense or porous organic silicates at either the line level or via level, or both. Furthermore, they are porous organosilicate other organic silicates, or, SiO 2, _FSG, fluorinated tetraethylorthosilicate (FTEOS), or used in conjunction with materials such as fluorinated or non-fluorinated organic polymer structure Can be used in the body. The other materials listed can be part of the structure, but they are generally less susceptible to damage of the type described herein during processing and are therefore sensitive to silylation processes. is not.

  The schematic of FIG. 8 shows how the silylating agent used in the present invention recovers the methyl portion in the low-k organic silicate film after it has been removed during normal process plasma exposure. Indicates success. The group that leaves the reactive site of the silylating agent (the “leaving group”) is the group that reacts with silanol to deprotonate it and form a new siloxane bond. Therefore, the reactivity of the leaving group determines the efficiency of the silylation reaction.

In Embodiment 1 of the present invention, a silylating agent of the type represented by the general formula (R ₂ N) _X SiR ′ _Y , wherein X and Y are integers of 1 to 2 and 2 to 1, respectively, Introduced after the definition of the lines and vias that will later hold the interconnect metal. In the above formula, R and R ′ can be any hydrogen, alkyl, aryl, phenyl, allyl, or vinyl moiety that can render the membrane hydrophobic. These silylating agents are commonly referred to as aminosilanes, and are hereinafter referred to as such in this specification. These are referred to as monofunctional or bifunctional bases, respectively, depending on whether the value of X is 1 or 2. Aminosilane is introduced in the liquid phase, in the gas phase (in a furnace or in a CVD chamber), or in a supercritical carbon dioxide medium by a spin-on process. It is very important to handle it without any at all, because if there is any moisture, it may reduce the efficiency of the silylation reaction. In addition, the combination of silylation and subsequent annealing, or the combination of annealing and subsequent silylation or silylation at high temperature (preferably above 350 ° C.) results in a significant reduction in the silanol content in the film, so Preferred over silylation alone. The annealing step also condenses any unsilylated silanol remaining in the film, allowing the formation of additional siloxane bonds that strengthen the film.

When aminosilane is used in a liquid medium, it is preferably dissolved in any nonpolar organic solvent having a low surface tension so that it can efficiently penetrate into the pores. Examples of such solvents include, but are not limited to, hexane, heptane, xylene and the like. The solvent is desirably low volatility as judged by flash point and boiling point, but is not essential. The concentration of aminosilane required for effective silylation can be as low as a 0.5 wt% solution, or it can be used in a liquid state in which the aminosilane is not diluted. The desired range for the most efficient silylation is typically a 2% to 10% solution. The solution is spin-coated on the porous low-k film, or in a wet chemical tank in which a wafer with interconnect features defined in the porous low-k film is immersed for 1 minute to 1 hour or more Can be used. The temperature for silylation can be room temperature or higher. Agitation or sonication during immersion is not essential to promote the reaction, but in some applications can help to increase the reaction rate. After silylation, the wafer can be rinsed in a pure solvent and then baked at temperatures up to 450 ° C. on a hot plate or in an oven.
Liquid phase silylation can also be carried out by spin coating or spray coating of this solution using the solution defined in the above paragraph.

  When performing gas phase silylation with aminosilanes, it is important that the carrier gas be inert and non-oxidizing and that the chamber be free of moisture. When the chamber is humid, the bifunctional and trifunctional aminosilanes can oligomerize to form a single layer or film, respectively. Monolayer and membrane formation is undesirable because the reactivity of the membrane with the silylating agent is generally reduced, and the processing is limited to the outermost surface, and the pores in the bulk of the membrane do not become hydrophobic. Vapor phase silylation can be carried out at temperatures ranging from room temperature to 450 ° C. over 30 seconds to 1 hour or more. The preferred time and temperature for gas phase silylation is 5 minutes at 250 ° C. After gas phase silylation, optional hot plate bake or furnace curing can be performed at temperatures up to 450 ° C. Vapor processing of dielectric films can be performed in free-standing furnaces, flow-through chambers, or processing chambers used for chemical vapor deposition (CVD) or atomic layer deposition (ALD) in the semiconductor industry. can do. The latter two options are particularly attractive because these chambers are designed to create a base vacuum to substantially eliminate moisture and introduce gas species and substrate heating devices. And because the dielectric can be silylated in situ just prior to the interconnect metal deposition step, this silylation can be accomplished by CVD or ALD using a suitable vapor precursor. Can be easily implemented.

Aminosilane When introducing the supercritical (SC) carbon dioxide (CO ₂₎ medium, the aminosilane may be introduced by itself or in combination with any suitable cosolvent. The temperature, pressure and time ranges for silylation based on SC CO ₂ can be as follows: The temperature ranges from 25 ° C. to 450 ° C., the pressure ranges from 1,000 psi to 10,000 psi, and the time ranges from 30 seconds to 1 hour or more.

A bifunctional aminosilane, such as (bis) dimethylaminodimethylsilane (BDDMADS) or (bis) dimethylaminomethylsilane, in SC CO ₂ or gaseous medium at a temperature above 75 ° C. for a time exceeding 30 seconds, then 400 ° C. It is preferable to use annealing at a time exceeding 1 minute. Bifunctional silylating agents are generally more effective than their monofunctional counterparts because, as shown in FIG. 10, two adjacent non-hydrogen bonding silanols, particularly geminal silanols, can be simultaneously used. This is because it has the ability to capture (FIG. 10 shows two adjacent isolated silanols). Monofunctional silylating agents generally have two methyl groups, as shown in FIG. 9, because the three methyl groups sterically hinder another monofunctional silylating agent from readily reacting with adjacent silanols. Two adjacent silanols cannot be captured. Trifunctional silylating agents tend to crosslink to form a membrane that does not penetrate the pores of the low-k membrane. Furthermore, additional silanols may be formed on the unreacted ends of the silylating agent because the trifunctional silylating agent cannot simultaneously capture three silanols.

FIG. 12 shows a comparison between monofunctional, bifunctional and trifunctional chlorine-terminated silylating agents where silylation was performed in a moisture-free environment in the liquid phase. From the FTIR spectrum of FIG. 12, it can be seen that the bifunctional base shows the optimal combination of increased methyl content and decreased silanol content in the film. Similar effects can be achieved with amino-terminated silylating agents, with the additional advantage that the reaction by-products are not corrosive.
As shown in FIG. 13, liquid phase silylation with BDDMMS followed by annealing at 400 ° C. restores the hydrophobicity and methyl content of the porous low-k film.

  Tables 1A and 1B show a comparison of contact angles achieved with BDDMMS, the preferred agent of the present invention, and contact angles with the silylating agent HMDS used in the prior art. As can be seen from Table 1A, BDDMMS is more effective at recovering the contact angle. Table 1B shows that the contact angle of HMDS silylated low-k materials is reduced and the dielectric properties are progressively degraded, whereas the effect of BDDMDS does not decrease after 4 weeks of exposure. . Table 2 shows that BDDMADS recovers after the k of the porous low-k film has increased after exposure to a typical process plasma. Similarly, for films treated with BDDMMS, the dielectric loss and breakdown strength recover to their original values.

  From FIG. 14, it can be seen that silylation changes the structural morphology of the organic silicate, making its skeleton more network-like than cage-like, resulting in improved mechanical properties. This is because the silylation reaction produces siloxane bonds that form a new network that improves the mechanical strength of the film. As seen in the FTIR spectrum of FIG. 14, the infrared peak with a wave number of about 1067 (1 / cm) indicating the degree of the network structure in the film is remarkably increased by the silylation treatment. See Table 3.

  As described above, following the silylation reaction, annealing in a furnace condenses all remaining silanols and produces new siloxane bonds that further increase mechanical strength.

Embodiment 2
Embodiment 1 generally shows the effectiveness of a bifunctional silylating agent, particularly BDMADMS. Embodiment 1 also shows that monofunctional silylating agents such as HMDS and TMCS are as effective as their bifunctional counterparts because of the steric hindrance provided by the three methyl moieties on the silylating agent. Indicates that it is not appropriate. However, it is possible to overcome this problem by appropriately replacing the methyl moiety of the silylating agent with a smaller hydrogen moiety. For example, when tetramethyldisilazane (TMDS) is used instead of HMDS, the steric hindrance is reduced and the silylation reaction becomes more effective. Similarly, successful silylation can be demonstrated by amino, chloro and alkoxy terminated monofunctional silylating agents in which the methyl moiety is at least partially replaced with a hydrogen analog. Therefore, the silylating agent having the general formula R _X H _Y Si-A in which X and Y are integers from 0 to 2 and 3 to 1, respectively, can be used as an effective silylating agent. As explained in the above embodiment, subsequent silylation reaction followed by furnace annealing condenses all remaining silanols and produces new siloxane bonds that further increase mechanical strength.

Embodiment 3
For applications that do not need to penetrate the pores of a porous low-k membrane, it has an amino, alkoxy, chloro or silazane terminal end group on which a mono or dialkyl, aryl, vinyl or hydrogen moiety is attached. The polymerized siloxane can be used to form a single layer on the outermost surface of the low-k film and restore the surface hydrophobicity. An example of such a siloxane is amino-terminated polydimethylsiloxane. It is important to ensure that the molecular weight is small enough so that the silylating agent flows into the gap created by the etching process that forms the trenches and vias in the organic silicate to form the interconnect structure. is there. As explained in the above embodiment, subsequent silylation reaction followed by furnace annealing condenses all remaining silanols and produces new siloxane bonds that further increase mechanical strength.

Embodiment 4
The silylating agent can also be introduced immediately after the film is deposited. The efficiency in this case depends on how much silanol is present in the film after deposition. In this embodiment, the silylating agent can also be introduced after a treatment such as UV / ozone that introduces silanol into the film, or after exposure to a mild oxidizing plasma. As in the previous embodiment, silylation is followed by thermal annealing. The silylating agent described in any of the above three embodiments can be used in this manner. In the case of CVD deposited films, the silylating agent can be co-deposited or introduced into the chamber along with a precursor for the CVD dielectric.

  It should be noted that the foregoing has outlined some of the more suitable objects and embodiments of the present invention. The concept of the present invention can be used for many applications. Thus, although described with respect to particular arrangements and methods, the intent and concepts of the present invention are appropriate and applicable to other arrangements and applications. It will be apparent to those skilled in the art that other modifications to the disclosed embodiments can be made without departing from the spirit and scope of the invention. The described embodiments are to be construed as merely illustrative of some of the more prominent features and applications of the present invention. Other beneficial results can be achieved by applying the disclosed invention in different ways, or modifying the invention in a manner known to those skilled in the art. Therefore, it should be understood that these embodiments are given by way of example and not limitation. The scope of the present invention is defined by the appended claims.

FIG. 3 shows a process flow of a standard dual damascene integration scheme. FIG. 3 shows a process flow of a standard dual damascene integration scheme. FIG. 3 shows a process flow of a standard dual damascene integration scheme. FIG. 3 shows a process flow of a standard dual damascene integration scheme. FIG. 3 shows a process flow of a standard dual damascene integration scheme. FIG. 3 shows a process flow of a standard dual damascene integration scheme. FIG. 3 shows a process flow of a standard dual damascene integration scheme. 1 is a schematic showing the effects of plasma exposure and silylation on the chemistry of ultra low k materials. FIG. 6 is a schematic diagram showing how a monofunctional silylating agent captures only one isolated silanol and blocks adjacent silanols. FIG. 10 is a schematic diagram showing how the bifunctional analog of the drug used in FIG. 9 successfully captures two adjacent silanols simultaneously. 2 shows a series of FTIR spectra showing the effect of monofunctional, bifunctional and trifunctional silylating agents. It is the elements on larger scale of FIG. A comparison of the FTIR spectra and contact angles of the original IMD, plasma-damaged IMD, BDDMMS-treated IMD, and BDDMMS-treated and annealed IMD is shown. Wavenumber functions for the original porous organic silicate IMD, the plasma damaged porous organic silicate IMD, the BDDMADS treated porous organic silicate IMD, and the BDDMADS treated and annealed porous organic silicate IMD Is a graph of the infrared absorbance as.

Explanation of symbols

1100: substrate 1110: via level dielectric 1120: line level dielectric 1130: hard mask layer (stack)
1150: Line location 1170: Via location 1180: Via opening 1190: Dual damascene trench and via structure 1200: Conductive liner material 1210: Conductive fill material 1220: Capping material 1500, 1510: Photoresist layer

Claims (62)

A low-k or extremely low dielectric constant organic silicate film having a hydrogen atom or an alkyl or aryl group bonded to a silicon atom, and a semiconductor chip, a chip carrier, or a low or very low dielectric constant insulating layer in a semiconductor wafer A method for recovering the characteristics of an organic silicate film used therein, wherein the organic silicate film has undergone a treatment that tends to degrade the characteristics,
Applying to the membrane a silylating agent comprising aminosilane so as to render the membrane hydrophobic. The aminosilane has the general formula (R ₂ N) _X SiR ′ _Y , where X and Y are integers from 1 to 2 and 3 to 2, respectively, and R and R ′ are hydrogen, alkyl, 2. The method of claim 1 selected from the group consisting of aryl, allyl, phenyl and vinyl moieties.   The method of claim 1, wherein the silylating agent comprises (bis) dimethylaminodimethylsilane or (bis) dimethylaminomethylsilane. The aminosilane has the general formula (R ₂ N) _X SiR ′ _Y R ″ _Z , where X, Y and Z are integers where X varies from 1 to 3, and Y and Z vary from 3 to 0, respectively. Wherein X + Y + Z is always equal to 4 and R, R ′ and R ″ are any of hydrogen, alkyl, aryl, allyl, phenyl, or vinyl moieties. A method for recovering the characteristics of an organic silicate film that has a hydrogen atom or an alkyl or aryl group bonded to a silicon atom and is in a semiconductor chip, a chip carrier, or a low or very low dielectric constant insulating layer in a semiconductor wafer The organic silicate membrane has undergone a treatment that tends to degrade its properties, and the method comprises:
Applying a silylating agent to the membrane to render the membrane hydrophobic, wherein the silylating agent has the general formula R _X H _Y Si-A, where X and Y are each 0 From 2 to 3 and from 3 to 1, R is either a hydrogen, alkyl, aryl, allyl, phenyl or vinyl moiety, and A is a chloro or alkoxy moiety.
Method. A method for recovering the characteristics of an organic silicate film that has a hydrogen atom or an alkyl or aryl group bonded to a silicon atom and is in a semiconductor chip, a chip carrier, or a low or very low dielectric constant insulating layer in a semiconductor wafer. The organic silicate film has undergone a treatment that tends to degrade its properties, and the method comprises:
Applying a silylating agent to the membrane to render the membrane hydrophobic, the silylating agent comprising a monofunctional end group selected from amino, chloro or alkoxy groups, The methyl portion of the silylating agent is at least partially substituted with a hydrogen analog;
Method. A method for recovering the characteristics of an organic silicate film that has a hydrogen atom or an alkyl or aryl group bonded to a silicon atom and is in a semiconductor chip, a chip carrier, or a low or very low dielectric constant insulating layer in a semiconductor wafer. The organic silicate membrane has undergone a treatment that tends to degrade its properties, and the method comprises:
Applying a silylating agent to the membrane to render the membrane hydrophobic, the silylating agent comprising a polymerized siloxane having amino, alkoxy, chloro or silazane terminal groups.
Method.   8. The method of claim 7, wherein the end group of the polymerized siloxane comprises a mono or dialkyl, aryl, vinyl or hydrogen moiety.   The method of claim 7, wherein the siloxane comprises an amino-terminated polydimethylsiloxane. A method for recovering the characteristics of an organic silicate film that has a hydrogen atom or an alkyl or aryl group bonded to a silicon atom and is in a semiconductor chip, a chip carrier, or a low or very low dielectric constant insulating layer in a semiconductor wafer. The organic silicate membrane has undergone a treatment that tends to degrade its properties, and the method comprises:
Applying a silylating agent to the membrane to render the membrane hydrophobic, wherein the silylating agent has the general formula R _X H _Y Si _Z A, and X and Y are each 0 From 5 to 5 and from 6 to 1, Z is an integer equal to 2, R is a hydrogen, alkyl, aryl, allyl, phenyl or vinyl moiety, and A is a silazane.
Method.   The method of claim 1, wherein the treatment includes etching the film and removing a photoresist material from the film, wherein the silylating agent is applied after the etching and the removal.   The method of claim 11, wherein the etching and removal is performed by exposing the film to a plasma.   A single damascene or dual damascene process is used, and the step of applying the silylating agent is performed after the definition of at least one of the interconnect lines and vias and prior to the deposition of the conductors. The method of claim 1.   14. The method of claim 13, wherein the step of applying the silylating agent is performed prior to conductive liner deposition.   The silylating agent is applied by one of a liquid spin coating, dipping a substrate in a liquid, spray coating a substrate with a liquid, a gas phase method, or a supercritical carbon dioxide dissolution method. Item 2. The method according to Item 1.   The method of claim 1, wherein the silylating agent is dissolved in supercritical carbon dioxide with a co-solvent selected from the group comprising at least one of alkanes, alkenes, ketones, ethers, and esters. .   The method of claim 1, wherein the silylating agent is applied in the absence of moisture.   The method of claim 1, further comprising annealing the film.   The method of claim 18, wherein the annealing is performed at a temperature of at least 350 ° C.   The method of claim 18, wherein the annealing is performed after applying the silylating agent.   The method of claim 18, wherein the annealing is performed prior to applying the silylating agent.   The method of claim 21, wherein the step of applying the silylating agent is performed at a temperature of at least 25 ° C.   The method of claim 18, wherein the annealing is performed to promote at least one of condensation of silanols in the film and formation of additional siloxane bonds.   The method of claim 1, wherein the silylating agent is dissolved in a solvent.   25. The method of claim 24, wherein the solvent is a low surface tension nonpolar organic solvent selected from the group comprising alkanes, alkenes, ketones, ethers, esters, or any combination thereof.   25. The method of claim 24, wherein the solvent has a sufficiently low surface tension to penetrate pores in the membrane.   25. The method of claim 24, wherein the silylating agent has a concentration between 2 and 10 weight percent in the solvent.   25. The method of claim 24, wherein the silylating agent has a concentration of one-half weight percent or more in the solvent.   The method of claim 1, wherein the silylating agent is applied over a period of between 30 seconds and 1 hour.   The method of claim 1, wherein the silylating agent is applied at room temperature or higher.   The method of claim 1, further comprising performing one of agitation or sonication when applying the silylating agent.   The method of claim 1, further comprising rinsing the membrane to remove excess silylating agent.   The method of claim 1, further comprising baking the film.   34. The method of claim 33, wherein the baking is performed at a temperature up to 450C.   The method of claim 1, wherein the silylating agent is applied in the gas phase at a temperature between room temperature and 450 ° C. over a period of 30 seconds to 1 hour.   The method of claim 1, wherein the silylating agent is applied in the gas phase at a temperature of substantially 250 ° C. over a period of 5 minutes.   The silylating agent is applied in supercritical carbon dioxide at a temperature between 25 ° C. and 450 ° C. and a pressure between 1,000 psi and 10,000 psi over a period of 30 seconds to 1 hour. The method of claim 1.   The method of claim 1, wherein the silylating agent is a bifunctional base.   The method of claim 1, wherein the silylating agent is applied in supercritical carbon dioxide or a gas phase medium at a temperature in excess of 75 ° C. for a period in excess of 30 seconds.   40. The method of claim 39, further comprising annealing the layer at 400C for a time greater than 1 minute.   The step of applying the silylating agent is performed following treatment of the film by introducing silanol into the film, exposure to ultraviolet radiation, ozone exposure, exposure to mild oxidizing plasma, or combinations thereof. Item 2. The method according to Item 1.   The method of claim 1, wherein the method is performed in a chemical vapor deposition chamber or an atomic layer deposition chamber.   The restored property of claim 1, wherein the recovered properties include at least one of hydrophobicity, elastic modulus, low dielectric constant, breakdown strength and hardness, dielectric breakdown strength, low dielectric leakage and dielectric reliability. Method.   The method of claim 1, wherein the film comprises one or more additional intermetal dielectrics.   The additional intermetallic dielectric is selected from the group consisting of silicon dioxide, fluorinated tetraethylorthosilicate, fluorinated silica glass, fluorinated or non-fluorinated organic polymers, thermosetting polymers, and chemical vapor deposition polymers. 45. The method of claim 44.   45. The method of claim 44, wherein the additional intermetallic dielectric is an organic polymer selected from the group of polyimide, benzocyclobutene, polybenzoxazole, and aromatic thermosetting polymers.   46. The method of claim 45, wherein the thermosetting polymer is based on polyarylene ether.   46. The method of claim 45, wherein the chemical vapor deposition polymer is polyparaxylylene. An insulating material having a plurality of conductors formed therein;
An intermetallic dielectric comprising an organic silicate film having a hydrogen atom or an alkyl or aryl group bonded to a silicon atom;
A manufactured article comprising a surface of the organic silicate film containing a reaction product of an aminosilane silylating agent and an organic silicate of the film. The aminosilane has the general formula (R ₂ N) _X SiR ′ _Y , where X and Y are integers from 1 to 2 and 3 to 2, respectively, and R and R ′ are hydrogen, alkyl, aryl, 50. The article of claim 49, selected from the group consisting of allyl, phenyl and vinyl moieties.   50. The article of claim 49, wherein the aminosilane is bis (dimethylamino) dimethylsilane. The aminosilane has the general formula (R ₂ N) _X SiR ′ _Y R ″ _Z , where X, Y and Z are integers where X varies from 1 to 3 and Y and Z vary from 3 to 0, respectively. 50. The article of claim 49, wherein X + Y + Z is always equal to 4, and R, R ′, and R ″ are any of hydrogen, alkyl, aryl, allyl, phenyl, or vinyl moieties. An insulating material having a plurality of conductors formed therein;
An intermetallic dielectric comprising an organic silicate film having a hydrogen atom or an alkyl or aryl group bonded to a silicon atom;
A surface of an organic silicate film containing a reaction product of a silylating agent and an organic silicate of the film so as to make the film hydrophobic, wherein the silylating agent has a form of R _X H _Y Si-A. X and Y are integers from 0 to 2 and 3 to 1, respectively, R is any of hydrogen, alkyl, aryl, allyl, phenyl or vinyl moiety, and A is a chloro or alkoxy moiety A manufactured article comprising a surface. An insulating material having a plurality of conductors formed therein;
An intermetallic dielectric comprising an organic silicate film having a hydrogen atom or an alkyl or aryl group bonded to a silicon atom;
A surface of an organic silicate membrane comprising a reaction product of a silylating agent and an organic silicate of the membrane to render the membrane hydrophobic, wherein the silylating agent is selected from amino, chloro or alkoxy groups An article of manufacture comprising a surface comprising a monofunctional group, wherein the methyl portion of the silylating agent is at least partially substituted with a hydrogen analog. An insulating material having a plurality of conductors formed therein;
An intermetallic dielectric comprising an organic silicate film having a hydrogen atom or an alkyl or aryl group bonded to a silicon atom;
A surface of an organic silicate film containing a reaction product of a silylating agent and an organic silicate of the film, the silylating agent comprising a polymerized siloxane having an amino, alkoxy, chloro or silazane terminal group A manufactured article comprising:   56. The article of claim 55, wherein the end groups of the polymerized siloxane comprise mono or dialkyl, aryl, vinyl or hydrogen moieties.   56. The article of claim 55, wherein the siloxane is an amino-terminated polydimethylsiloxane.   56. The article of claim 55, wherein the siloxane is an amino-terminated polydimethylsiloxane. An insulating material having a plurality of conductors formed therein;
An intermetallic dielectric comprising an organic silicate film having a hydrogen atom or an alkyl or aryl group bonded to a silicon atom;
A surface of an organic silicate film containing a reaction product of a silylating agent and an organic silicate film, wherein the silylating agent has a general formula R _X H _Y Si _Z A, and X and Y are each 0 From 5 to 5, from 6 to 1, Z is equal to 2, R is any of hydrogen, alkyl, aryl, allyl, phenyl or vinyl moieties, and A is a silazane. Manufactured goods.   50. The article of claim 49, formed as a semiconductor chip, a semiconductor chip carrier, or a semiconductor wafer.   50. The article of claim 49, wherein the surface is an outer surface of the membrane.   50. The article of claim 49, wherein the surface comprises a surface of a pore in the membrane.

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