JPH0222942B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a high-energy ray-sensitive material that reproduces negative patterns with high precision and has high dry etching resistance, and a method for using the same. [Prior Art] Conventionally, in the manufacture of ICs and LSIs, a substrate to be processed is coated with an organic composition such as a polymer compound called a resist, and a latent image is formed on the resist by irradiating it with high-energy radiation in a pattern. After developing this to form a patterned resist film, the substrate to be processed is immersed in a corrosive liquid to chemically etch the parts of the substrate not covered by the resist or dope with impurities. came. However, as integrated circuits have become more highly integrated in recent years, it has been desired to form even finer patterns.
In particular, the wet method of etching by immersion in a corrosive solution causes side etching, so to avoid this, dry etching methods such as reactive ion etching using gas plasma have become popular. However, since conventional resists are etched by dry etching in the same manner as the substrate to be processed, this problem has been dealt with by increasing the thickness of the resist film. Therefore, a resist material with high dry etching resistance is desired, but a material with sufficient resistance has not yet been found. On the other hand, in order to increase the amount of wiring and realize elements with a three-dimensional array structure, it is desired to form a resist pattern on a substrate with steps. Therefore, it is necessary to make the resist film thicker in order to cover the difference in level. Furthermore, in order to capture high-speed ions without them reaching the substrate, the resist film must be thick. However, with conventional resists,
As the film thickness increases, the resolution decreases, making it impossible to form fine patterns. In order to solve this problem, a method has been proposed in which a resist pattern with a high shape ratio is formed by using multiple layers of resist instead of one layer.
That is, a thick film of an organic polymer material is formed as the first layer, a thin resist material layer is formed as the second layer on top of the thick film, and then the resist material of the second layer is irradiated with high energy rays and developed. Thereafter, by dry etching the organic polymer material of the first layer using the obtained pattern as a mask, a pattern with a high shape ratio can be obtained. However, with this method, when a normal resist is used for the second layer, it may not be possible to obtain a large dry etching rate ratio, that is, the selectivity, between the materials of the first layer and the second layer, or it may take a long time to increase the dry etching rate. Etching time was required. For example, according to Akiya et al. (Proceedings of the 43rd Japan Society of Applied Physics Conference, p. 213), the first layer contains polymethyl methacrylate (hereinafter abbreviated as PMMA).
It has been reported that if dry etching is performed using carbon tetrachloride etching gas in a system using chloromethylated polystyrene as the second layer, the selectivity becomes extremely high and a resist pattern with a high shape ratio can be formed. ing. But in this case,
Since the etching speed of PMMA is also reduced, it takes time to etch thick PMMA, and there is also the disadvantage that the underlying substrate is etched at the same time with carbon tetrachloride. As a multilayer resist system using oxygen plasma, a three-layer resist has been proposed in which an inorganic layer having high oxygen plasma resistance is provided between a first thick film polymer material layer and a second resist layer. In this case, the inorganic layer is dry-etched using a gas such as carbon tetrachloride, carbon tetrafluoride, or argon using a pattern formed with a resist material as a mask.
Next, using the inorganic material pattern as a mask, the organic polymer material layer is dry etched with oxygen. In this case, the oxygen plasma can quickly etch the first layer of thick polymer material.
Since the substrate is not etched at all, a resist pattern having a desired profile can be formed without monitoring the end point of etching. However, it has the disadvantage that the number of steps increases significantly. On the other hand, when a silicone resist with high resistance to dry etching by oxygen plasma is used for the second layer, the oxygen plasma is applied when dry etching the organic polymer material of the first layer using the resist pattern of the second layer as a mask. Because it can be used, resist patterns with high shape ratios can be formed in a short time and with a small number of steps. However, currently known silicone resists have glass transition temperatures considerably lower than room temperature, and polymers with low molecular weights are liquid or semi-liquid, making them extremely difficult to handle and having poor sensitivity to high-energy radiation. On the other hand, when the molecular weight is increased, it becomes rubber-like and becomes slightly easier to handle, and the sensitivity also increases, but it has drawbacks such as swelling in the developing solvent, resulting in a decrease in resolution such as pattern waviness. Furthermore, in order to increase the sensitivity of the crosslinking reaction, a functional group with high chain reactivity, such as a vinyl group, is introduced into the side chain, which also causes a decrease in resolution. [Object of the Invention] The present invention has been made to eliminate these drawbacks, and its purpose is to have high sensitivity and high resolution to high-energy radiation, and to be highly resistant to dry etching. An object of the present invention is to provide a durable high energy radiation sensitive material and a method for using the same. [Structure of the Invention] That is, if the present invention is summarized, the first aspect of the present invention is as follows.
The invention is an invention of a pattern forming material, which has the following general formula: (In the formula, R, R' and R'' are the same or different, hydrogen,
Represents one type of group selected from the group consisting of an alkyl group and a phenyl group, l, m and n represent 0 or a positive integer, l and m are never 0 at the same time, and the phenyl nucleus is 75 The siloxane polymer is characterized by containing a siloxane polymer having a chloromethylation rate of 17% or more and a chloromethylation rate of 17% or more. Further, the second invention of the present invention is an invention of a pattern forming method, in which a film of a high-energy ray-sensitive material is formed on a base material, heat-treated, and then a part of the formed film is irradiated with high-energy rays. In the method of forming a pattern by selectively exposing the film to light and then selectively removing the exposed portion of the film with a developer, the high-energy ray-sensitive material is a material containing a siloxane polymer represented by the above general formula. Characterized by its use. The third invention of the present invention is an invention of another pattern forming method, in which an organic polymer material layer is provided on a base material, a high energy ray sensitive material layer is provided thereon, and then a high energy ray sensitive material layer is provided on the organic polymer material layer. is irradiated in a desired pattern to crosslink the high-energy ray-sensitive material only in the irradiated areas, then immersed in an organic developing solvent to remove the high-energy ray-sensitive material in non-irradiated areas, and then using this as a mask to remove oxygen. In a method of forming a pattern by etching and removing portions of the organic polymer layer not covered with the high-energy ray-sensitive material by dry etching, the high-energy ray-sensitive material is represented by the general formula It is characterized by the use of a material containing a siloxane polymer. Examples of the alkyl group in the general formula in the present invention include a methyl group, an ethyl group, and a propyl group. Furthermore, the content of alkyl groups and hydrogen should be small, preferably less than 25 mol%. On the other hand, the more chloromethylated phenyl groups the better, and preferably 20 mol% or more. The most important point in the present invention is that by introducing chloromethyl groups into silicone polymers containing phenyl groups such as polyphenylmethylsiloxane and polydiphenylsiloxane, it is possible to create high-energy ray-sensitive materials with high sensitivity and high resolution. The point lies in the fact that we have discovered that something will happen. Furthermore, phenyl group-containing silicone polymers can be used not only for oxygen gas but also for CCl ₄ ,
It also showed high resistance to etchant gases used in reactive ion etching, such as CF ₂ Cl ₂ . Moreover, the phenyl nucleus (i.e., the total of unsubstituted phenyl groups and chloromethyl-substituted phenyl groups)
Polymers containing 75 mol% or more become solid at room temperature and dissolve well in organic solvents such as toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, and monochlorobenzene. A thin film can be formed. This property does not change even when chloromethylated, and therefore, whereas conventional silicone resists are liquid or rubber-like,
We were able to make it much easier to handle. As a method for producing a polymer compound represented by the general formula of the present invention, a cyclic phenylsiloxane such as hexaphenylcyclotrisiloxane or octaphenylcyclotetrasiloxane is mixed with an alkali metal hydroxide such as potassium hydroxide or butyl lithium. Examples include a method of chloromethylating polydiphenylsiloxane obtained by ring-opening polymerization with an alkylated alkali metal such as. Further, instead of using cyclic phenylsiloxane alone, it may be copolymerized with tetramethyltetraphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, or the like.
In addition, if you want to form a particularly high-resolution pattern, a monodisperse polymer with a uniform molecular weight is required, but cyclosiloxane is anionically living polymerized using a catalyst such as butyllithium, and the resulting polymer is chloromethylated. By doing so, a desired monodisperse polymer can be obtained. Examples of manufacturing the high-energy ray-sensitive material of the present invention are shown below. Production example 1 50g of octaphenylcyclotetrasiloxane, 100ml of tetrahydrofuran, 250mg of potassium hydroxide
was placed in a glass tube, degassed and sealed, and polymerized at a polymerization temperature of 70℃.
The reaction was allowed to proceed for 24 hours. The contents were poured into a water-methanol (1:4) solution to obtain a white polymer.
The polymer was purified by reprecipitation several times with a methanol-xylene system. The obtained polydiphenylsiloxane had a weight average molecular weight of 1.3×10 ³ , a degree of dispersion of 2.6, and a glass transition temperature of 150°C. Production example 2 10g of hexaphenylcyclotrisiloxane
In addition to 3.7 ml of concentrated sulfuric acid and 10 ml of diethyl ether,
Stir at room temperature for 24 hours. Next, add 20 ml of diethyl ether and 10 ml of water, and stir for another hour. The water in the lower layer is separated, dried over anhydrous potassium carbonate, and heated under reflux at 300°C for 3 hours. The ether was then evaporated to give a white solid. This was purified by reprecipitation with methyl ethyl ketone-methanol, and the weight average molecular weight was 1.9 × 10 ⁴ dispersity.
A polydiphenylsiloxane with Mw/=2.1 was obtained. Production Example 3 10g of hexaphenylcyclotrisiloxane was dissolved in 100ml of toluene, and after thorough deaeration and dehydration, 5ml of a 10% toluene solution of butyllithium was added dropwise to -60
Living polymerization was carried out at ℃ for 10 hours. The reaction solution was poured into methanol to obtain a white solid polymer. This was purified by repeated reprecipitation with methyl ethyl ketone-methanol, and then vacuum-dried. The weight average molecular weight calculated from gel permeation chromatography is =8.9×10 ³ , dispersity/=
It was 1.1. Production Example 4 20g of polydiphenylsiloxane obtained in Production Example 1
was dissolved in 500 ml of chloromethyl methyl ether and reacted at -5°C for 10 hours using 20 ml of stannic chloride as a catalyst. The reaction solution was poured into methanol to obtain a white solid polymer. In the infrared absorption spectrum of this polymer, there was an absorption attributable to di-substituted phenyl at 800 cm ^-1 and an absorption attributable to the methylene group of the chloromethyl group at 2200 cm ^-1 , confirming that it was chloromethylated. did it. From elemental analysis, the chloromethylation rate of this polymer was 20%, and the weight average molecular weight calculated from gel permeation chromatography was 1.2 x 10 ⁴ , and the degree of dispersion was 20%.
Mw/=1.8. Production Examples 5 and 6 The polydiphenylsiloxane obtained in Production Example 2 (Production 5) and the polydiphenylsiloxane obtained in Production Example 3 (Production Example 6) were subjected to exactly the same reaction conditions as Production Example 4,
It was chloromethylated by operation. The chloromethylation rate of this chloromethylated polydiphenylsiloxane was 17% in Production Example 5, and the molecular weight was 3.1×10 ⁴ .
The degree of dispersion was 2.5. In addition, production example 6
Then, =2.2×10 ⁴ and dispersion degree/=1.3. Production Example 7 In Production Example 4, by changing the amount of stannic chloride added, chloromethylated polydiphenylsiloxanes having different chloromethylation rates were obtained. Table 1
shows the amount of stannic chloride added, chloromethylation rate, weight average molecular weight, and degree of dispersion.

[Table] Production Example 8 Polydiphenylsiloxanes with different molecular weights were obtained by changing the reaction temperature in Production Example 1, and then chloromethyl siloxanes with the same chloromethylation rate and different molecular weights were obtained by the same method as Production Example 4. Polydiphenylsiloxane was obtained. Table 2 shows the reaction temperature, polydiphenylsiloxane molecular weight, chloromethylation rate, chloromethylated polydiphenylsiloxane molecular weight, and degree of dispersion.

[Table] Production Example 9 In Production Example 1, a mixture of tetraphenyltetramethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane was added in place of octaphenylcyclotetrasiloxane at a different mixing ratio to synthesize a polymer. Chloromethylation was carried out using the method described below. Table 3 shows the phenyl group content, glass transition temperature, and molecular weight.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 The chloromethylated polydiphenylsiloxane obtained in Production Example 4 was dissolved in methyl isobutyl ketone,
Coat to a thickness of approximately 0.5μm on a silicon wafer and heat at 100℃.
Prebaked in a nitrogen stream for 20 minutes. After prebaking, electron beam irradiation was performed at an accelerating voltage of 20 KV. After irradiation, the wafer was developed with a mixed solvent of methyl ethyl ketone:isopropyl alcohol=4:1, and rinsed with isopropyl alcohol. FIG. 1 shows the relationship between the residual film rate after development and the irradiation amount. That is, FIG. 1 is a graph showing the electron beam sensitive characteristics of the formed resist pattern in terms of the relationship between the electron beam irradiation amount (C/cm ² ) (horizontal axis) and the normalized residual film ratio (vertical axis). As is clear from this graph, the electron beam irradiation dose that leaves 50% of the initial film thickness is 2.0×10 ^-5 C/cm ² , which is a sensitivity that can be used sufficiently for practical purposes. Further, the γ value, which is a measure of resolution and is expressed by the slope of the sensitivity curve as shown in FIG. 1, is 2.5, which is a high value. In fact, after irradiation with an electron beam, a development rinse with the same composition as above was performed, and the 0.5 μm lines/spaces had no so-called whiskers or bridges, and the patterns were separated from each other, resulting in sufficient resolution. Example 2 AZ-1350 resist (manufactured by Shipley) was coated on a silicon wafer to a thickness of 2 μm, and insolubilized by heating at 200° C. for 30 minutes. The chloromethylated polydiphenylsiloxane obtained in Production Example 4 was applied onto this AZ resist to a thickness of about 0.3 μm in the same manner as in Example 1, and prebaked at 100° C. for 20 minutes in a nitrogen stream. After prebaking, electron beam irradiation was performed at an accelerating voltage of 20 KV. After irradiation, it was developed with a mixed solvent of methyl ethyl ketone: isopropyl alcohol = 4:1,
Rinse with isopropyl alcohol. the result
A 0.3 μm line/space pattern was formed on the AZ resist. Thereafter, etching was performed using a parallel plate type sputter etching apparatus using oxygen gas as an etchant gas. (Applied power 50 W, etching chamber pressure 80 mTorr oxygen gas) Under these etching conditions, the etching rate of chloromethylated polydiphenylsiloxane is O, and the etching rate of AZ resist is 800 Å/min. The AZ resist in areas not covered by the methylated polydiphenylsiloxane pattern completely disappeared. After etching
A 0.3 μm line/space pattern could be formed with a film thickness of 2.3 μm. Examples 3 to 5 In the method of Example 1, instead of electron beam irradiation, X
Radiation (Example 3), deep ultraviolet rays (Example 4), and ion beams (Example 5) were used. Table 4 shows the high energy ray irradiation doses at which 50% of the initial film thickness remained.

[Table] Examples 6 to 9 When the chloromethylated polydiphenylsiloxane obtained in Production Example 7 is irradiated with an electron beam by the method of Example 1, the amount of electron beam irradiation (sensitivity) that leaves 50% of the initial film thickness
and γ values are shown in Table 5.

[Table] Example 10 When the chloromethylated polydiphenylsiloxane obtained in Production Example 8 is irradiated with an electron beam by the method of Example 1, the amount of electron beam irradiation (sensitivity) that leaves 50% of the initial film thickness
and γ values are shown in Table 6.

[Table] Examples 11 to 14 The patterns formed by the method of Example 1 were applied to CF ₄ (Example 11), CCl ₄ (Example 12), CCl ₂ F ₂ (Example 13),
Table 7 shows the etching rate when reactive ion etching was performed using Ar (Example 14).

〔Effect of the invention〕

As explained above, the silicone resin obtained by the present invention has a higher glass transition temperature than conventional silicone resins, and also has a chain reaction that inhibits high reactivity and high resolution as a high-energy ray-sensitive group. Because it has a chloromethyl group bonded to a less reactive phenyl group, it has high reactivity and high resolution with respect to high-energy rays. Further, since the cyclic siloxane monomer can be subjected to living polymerization, a resist material having a very small molecular weight distribution, that is, a high resolution can be obtained. In addition, both resins are white powders and have excellent solvent and spin coating properties, making them easier to handle than conventional silicone resins that are almost liquid. Moreover, it has extremely high resistance to dry etching using fluorine-containing gas compared to conventional silicone resins, and also has high resistance compared to conventional styrene-based resists. Therefore, even as a single resist, it has good sensitivity, resolution, and dry etching resistance. In addition, 2 with a thick organic film in the lower layer
When used as the top layer of a layered resist, submicron patterns with significantly high feature ratios can be formed. The above has a great effect on the production of semiconductor devices and the like. Furthermore, in conventional negative-type films, so-called whiskers or bridges are likely to occur between patterns due to the proximity effect and swelling during development, and this effect is particularly significant when the patterns become finer. However, the resist of the present invention has no such proximity effect or swelling, and is highly effective in improving resolution. This effect is even greater when the resist has a two-layer structure, and the number of steps and time can be significantly reduced compared to the multilayer resist method with three or more layers.Also, even in the case of a two-layer resist, the conventional method Although it has been impossible to form a high-resolution thick film pattern due to low imageability and dry etching resistance, by using the resist of the present invention, resolution and shape ratio can be dramatically improved. Therefore, it is possible to form resist patterns economically and in a short time that have sufficient film thickness to be used for pattern formation over steps and high-acceleration ion implantation, and also have high resolution. It produces remarkable effects that are unparalleled anywhere else.

[Brief explanation of drawings]

FIG. 1 is a graph showing the electron beam sensitive characteristics of a resist pattern formed by the method of the present invention in terms of the relationship between the electron beam irradiation amount and the normalized residual film rate.

Claims (1)

[Claims] 1. The following general formula: (In the formula, R, R' and R'' are the same or different, hydrogen,
Represents one type of group selected from the group consisting of an alkyl group and a phenyl group, l, m and n represent 0 or a positive integer, l and m are never 0 at the same time, and the phenyl nucleus is 75 A pattern-forming material characterized by containing a siloxane polymer having a chloromethylation rate of 17% or more and a chloromethylation rate of 17% or more. 2 A film of a high-energy ray-sensitive material is formed on a substrate, heat-treated, and then a part of the formed film is selectively exposed by irradiation with high-energy rays, and then the unexposed parts of the film are selectively exposed with a developer. In the method of forming a pattern by removing the material, the high-energy ray-sensitive material has the following general formula: (In the formula, R, R' and R'' are the same or different, hydrogen,
Represents one type of group selected from the group consisting of an alkyl group and a phenyl group, l, m and n represent 0 or a positive integer, l and m are never 0 at the same time, and the phenyl nucleus is 75 A pattern forming method characterized by using a material containing a siloxane polymer having a chloromethylation rate of 17% or more and a chloromethylation rate of 17% or more. 3 An organic polymer material layer is provided on a base material, a high energy ray sensitive material layer is provided on top of the layer, and then high energy rays are irradiated in a desired pattern to crosslink the high energy ray sensitive material only in the irradiated areas. Then, the high energy ray sensitive material in the non-irradiated area is removed by immersion in an organic developing solvent, and then the organic polymer in the area not covered by the high energy ray sensitive material is removed by dry etching using oxygen using this as a mask. In a method of forming a pattern by etching and removing a material layer, the high energy ray-sensitive material may be of the following general formula: (In the formula, R, R' and R'' are the same or different, hydrogen,
Represents one type of group selected from the group consisting of an alkyl group and a phenyl group, l, m and n represent 0 or a positive integer, l and m are never 0 at the same time, and the phenyl nucleus is 75 A pattern forming method characterized by using a material containing a siloxane polymer having a chloromethylation rate of 17% or more and a chloromethylation rate of 17% or more.