JPH0345380B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a pattern forming method that can be used for manufacturing semiconductor devices, magnetic bubble devices, optical application parts, and the like. [Prior Art] Regarding resists used in the manufacture of LSIs, a method has been proposed in which the resist has a two-layer structure in order to form a pattern with high definition and a high aspect ratio. That is, a thin upper resist layer is placed on a lower resist layer made of an organic polymer material, and after a pattern of the upper resist layer is formed, the organic polymer layer is etched using oxygen gas plasma using the pattern as a mask. This upper layer resist is required to have excellent oxygen plasma resistance as well as high sensitivity and resolution, and resist materials that incorporate highly sensitive groups into silicon-containing polymers that have excellent oxygen plasma resistance are seen as promising. . However, currently known polysiloxane resists have a glass transition temperature (Tg) lower than room temperature, making them difficult to handle as a resist, and swelling in a developing solvent causes pattern deformation and a decrease in resolution.
Therefore, a two-layer resist using this resist as an upper layer resist has the disadvantage that it is difficult to form a high-resolution pattern. In addition, general polysiloxanes had the disadvantage of poor compatibility with bisazide compounds used as sensitizers (Japanese Patent Laid-Open No.
58-49717). [Problems to be solved by the invention] In the case of silicone-based resists that have silicon in their side chains, the glass transition temperature can be raised, but the resistance to oxygen plasma decreases, so the film thickness must be increased to be used as a transfer mask for the underlying resist. There is a need to. Therefore, even a two-layer resist using this resist as an upper layer resist has the disadvantage that it is difficult to form a high-resolution pattern. The present invention was made to eliminate these drawbacks, and its purpose is to use a phenyl group-containing polysiloxane resist that has high sensitivity to light, high glass transition temperature, and high oxygen plasma resistance as an upper layer resist. An object of the present invention is to provide a pattern forming method using a two-layer resist method. [Means for Solving the Problems] Briefly speaking, the present invention relates to a pattern forming method, in which a lower layer resist made of an organic polymer material having excellent dry etching resistance is coated on a processed substrate. a step of coating an upper resist with excellent oxygen plasma resistance on the lower resist, a step of irradiating ultraviolet rays through a photomask and developing it to form a pattern of the upper resist on the lower resist, and a step of forming an upper resist pattern on the lower resist. In a pattern forming method including each step of transferring to a lower resist layer by oxygen plasma etching,
As the upper layer resist, the following general formula or: (In the formula, X is

【formula】

[Formula] and

[Formula] represents one type of group selected from the group consisting of l,
(m and n are 0 or a positive integer, but l and m are never 0 at the same time) and any of the siloxane polymers represented by the following general formula: (In the formula, R ₁ is a direct bond, -CH ₂ -, -O-,
-CH=CH-, -N=N-, -S-,

【formula】

【formula】

【formula】

[Formula] or

The present invention is characterized by using a resist containing one or more compounds selected from the group consisting of the group represented by the formula: where R ₂ is a hydrogen atom or a halogen atom. Examples of bisazide compounds of the formula include, for example, 3,
3'-dichloro-4,4'-diazide diphenyl methane, 4,4'-diazide diphenyl ether, 4,
4'-Diazidiphenylmethane, 4,4'-Diazidiphenyl sulfone, 3,3'-Diazidiphenyl sulfone, 4,4'-Diazidiphenyl ketone, 2,6-di-(4 '-azodobenzal)-4-methylcyclohexanone and the like. The amount of these added is preferably 0.5 to 30% by weight based on the siloxane polymer of the above formula or the phenylsilsesoxane (ladder siloxane) polymer of the above formula. If it is less than 0.5% by weight, no crosslinking will occur, and if it exceeds 30% by weight, long-term storage stability and coating properties will be poor. The siloxane polymers of the formulas () and () used in the upper resist of the present invention contain a large amount of phenyl groups and therefore have a high glass transition temperature. Incidentally, if the phenyl group content is less than 75%, it becomes gum-like and cannot achieve a high glass transition temperature. Further, by introducing a photosensitive group that causes crosslinking by ultraviolet light into the phenyl group, that is, an acryloyloxymethyl group, a methacryloyloxymethyl group, or a cinnamoyloxymethyl group, it was possible to impart properties as a negative resist.
The main chain siloxane structure is characterized by high resistance to oxygen plasma, and can be used as an upper layer resist of a two-layer resist. Siloxane-based polymers are generally known to have poor compatibility with the bisazide compound represented by the above formula () (Japanese Patent Application Laid-open No. 58-49717), but the introduction of a large number of phenyl groups improves compatibility. improved,
30 for siloxane polymers as mentioned above.
It was possible to add up to % by weight. When polymethylvinylsiloxane does not contain a phenyl group, there is a problem that even at 2% by weight, the azide compound precipitates and the resist film becomes non-uniform. Resist sensitivity can be easily improved by increasing the amount of the bisazide compound added. Figure 1 shows the bisazide compound 2,6-
It is a graph showing the relationship between the amount of di-(4'-azidobenzal)-4-methylcyclohexanone added (wt%, horizontal axis) and sensitivity (mJ/cm ² , vertical axis). Sensitivity was expressed as the exposure amount at which the gel ratio was 50%. As a method for producing the siloxane polymer represented by the general formula of the present invention, first, a cyclic phenylsiloxane is subjected to ring-opening polymerization with an alkali metal hydroxide such as potassium hydroxide, and the resulting polydiphenylsiloxane is chloromethyl methyl A chloromethylated polydiphenylsiloxane is obtained by dropping stannic chloride as a catalyst into an ether solution. Next, there is a method of substituting the chloro group of the chloromethyl group with an acryloyloxy group, a methacryloyloxy group, or a cinnamoyloxy group by reacting it with potassium acrylate, potassium methacrylate, or potassium cinnamate. The method for producing the phenylsilsesquioxane (ladder siloxane) polymer represented by the general formula of the present invention is as follows:

[Formula] (Z is Cl or OCH ₃ ) A phenylsilsesquioxane polymer easily obtained by hydrolyzing a silane compound is chloromethylated in the same manner as above, and then the chloromethyl group is chloromethylated. There is a method of substituting the group with an acryloyloxy group, a methacryloyloxy group, or a cinnamoyloxy group. as a starting material

When a mixture of a silane compound in which a chloromethyl group is introduced into a phenyl group and the phenyltrichlorosilane is hydrolyzed as shown in the formula, the chloromethylation reaction is not necessary. The advantage of this production method is that the chloromethylation rate can be controlled by changing the mixing ratio of the silane compounds as starting materials, that is, the introduction rate of photosensitive groups can be easily controlled. Controlling the introduction rate of photosensitive groups is an important issue because a trade-off exists in that as the introduction rate of photosensitive groups increases, resist sensitivity improves but oxygen plasma resistance decreases. Figure 2 shows the relationship between the photosensitive group introduction rate (%, horizontal axis), sensitivity (mJ/cm ² , vertical axis) and oxygen plasma resistance (vertical axis) of methacryloyloxymethylated phenyl synthesquioxane polymer. This is a graph. 2,6-di-(4'-azidobenzal)-4-methylcyclohexanone was added in an amount of 5% by weight. Oxygen plasma resistance was expressed as etching rate (nm/min). The required characteristics of the upper layer resist are sensitivity of 90mJ/
cm ² or less and the etching rate is 5 nm/min or less, the introduction rate of photosensitive groups (in other words,

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. Example 1 10 g of a siloxane polymer obtained by ring-opening polymerization of hexaphenylcyclotrisiloxane was dissolved in 250 ml of chloromethyl methyl ether and reacted at -5°C for 10 hours using 10 ml of stannic chloride as a catalyst.
The reaction solution was poured into methanol to obtain a chloromethylated siloxane polymer. Elemental analysis showed that the chloromethylation rate was 20%. After dissolving 5 g of this chloromethylated siloxane polymer in 70 ml of dimethylformamide (DMF), 0.9 g of ethyltriethylammonium iodide and 5 g of potassium methacrylate were added, and the mixture was reacted at 30°C for 12 hours to produce methacryloyloxymethylated phenyl polysiloxane. 4g of was obtained. To this was added 5% by weight of 2,6-di-(4'-azidobenzal)-4-methylcyclohexanone to form an upper layer resist. AZ 1350J (manufactured by Shipley, novolac resin) as a lower layer resist on a silicon substrate with silicon oxide on the surface
was coated to a thickness of 1 μm and baked at a low temperature of 80°C for 30 minutes. Apply a 10% by weight solution of chlorobenzene from the upper resist onto the lower resist,
The thickness was 0.2 μm. After pre-baking at 80°C for 10 minutes, ultraviolet light was irradiated through a photomask using an ultra-high pressure mercury lamp (50mJ/cm ² ). After irradiation, it was developed with xylene for 10 seconds and rinsed with methylcyclohexane for 20 seconds to form an upper resist pattern on the lower resist. No change was observed in the lower resist layer during development. Next, oxygen plasma treatment was performed to transfer the pattern of the upper resist layer to the lower resist layer, and a line and space pattern of 0.8 μm could be formed. After dry etching the silicon oxide using this two-layer resist pattern as a mask, the two-layer resist was stripped with methyl isobutyl ketone. No resist residue was observed on the substrate. Examples 2 and 3 In producing the upper resist of Example 1, potassium acrylate (Example 2) or potassium cinnamate (Example 3) was used in place of potassium methacrylate. Pattern formation was performed using the same method as in Example 1, and a pattern with a width of 0.8 μm could be formed. The amount of UV exposure was 40 mJ/cm ² (Example 2).
It was 60 mJ/cm ² (Example 3). Example 4 After 15 g of chloromethylphenyltrichlorosilane and 20 g of phenyltrichlorosilane were dissolved in 100 ml of N-methylpyrrolidone, 50 ml of H ₂ O and 25 ml of concentrated hydrochloric acid were added, and the mixture was left at 25° C. for 24 hours. After washing the precipitate with water, it was dissolved in 100 ml of tetrahydrolane and poured into methanol to determine the chloromethylation rate.
43% chloromethylated polyphenylsilsesquioxane was obtained. After dissolving 5 g of this polymer in 70 ml of DMF, 0.9 g of ethyltrimethylammonium idide and 7 g of potassium methacrylate were added.
The reaction was carried out at ℃ for 12 hours. The reaction solution was poured into methanol to obtain 43% methacryloyloxymethylated polyphenylsilsesoxane. 2,6-
5% by weight of di-(4'-azidobenzal)-4-methylcyclohexanone was added to form an upper resist layer. Pattern formation was carried out in the same manner as in Example 1, and a pattern with a width of 0.8 μm could be formed. The amount of UV exposure was 30 mJ/cm ² . Examples 5 and 6 Potassium acrylate (Example 5) and potassium cinnamate (Example 6) were used in place of potassium methacrylate in the method for manufacturing the upper layer resist of Example 4. A pattern with a width of 0.8 μm was formed in the same manner as in Example 1. The amount of UV exposure was 20 mJ/cm ² (Example 5) and 40 mJ/cm ² (Example 6). Examples 7 to 14 In Example 4, 4,4'-diazide diphenyl ether (Example 7), 4,4' was used instead of 2,6-di-(4'-azidobenzal)-4-methylcyclohexanone. -Diazido diphenyl sulfone (Example 8), 4,4'-Diazido diphenyl methane (Example 9), 3,3'-Diazido diphenyl sulfone (Example 10), 3,3'-Diazido diphenyl sulfone (Example 10), azidodiphenylmethane (Example 11), 4,4'-diazidodibenzalacetone (Example 12), 2,6-di-(4'-azidobenzal)cyclohexanone (Example 13), 3,
3'-dichloro-4,4'-diazidodiphenylmethane (Example 14) was used. A pattern with a width of 0.8 μm was formed in the same manner as in Example 1. Table 1 summarizes the amount of ultraviolet light exposure in each example.

〔Effect of the invention〕

As explained above, the pattern forming method according to the present invention is a two-layer resist method, and the upper layer resist uses a siloxane-based polymer that has high sensitivity to ultraviolet rays, a high glass transition temperature, and high oxygen plasma resistance. There is an advantage that a high-resolution pattern can be obtained. Furthermore, since the obtained two-layer resist pattern can be easily peeled off with a polar solvent after processing the substrate, there is an advantage that no resist residue remains on the substrate.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the amount of bisazide added and sensitivity in one example of the present invention, and Figure 2 is a graph showing the relationship between the photosensitive group introduction rate and photosensitivity and oxygen plasma resistance in one example of the present invention. This is the graph shown.

Claims (1)

[Claims] 1. A step of applying a lower layer resist made of an organic polymer material with excellent dry etching resistance on a processed substrate;
A process of coating an upper resist with excellent oxygen plasma resistance on the lower resist, a process of irradiating ultraviolet rays through a photomask and developing it to form an upper resist pattern on the lower resist, and an oxygen plasma etching process of the upper resist pattern. In a pattern forming method including each step of transferring to a lower resist by a method, as an upper resist, the following general formula or: (wherein, X represents one type of group selected from the group consisting of [formula] [formula] and [formula], l,
(m and n are 0 or a positive integer, but l and m are never 0 at the same time) and any of the siloxane polymers represented by the following general formula: (In the formula, R ₁ is a direct bond, or -CH ₂ -, -O-,
-CH=CH-, -N=N-, -S-, [Formula] [Formula] [Formula] [Formula] is a group represented by [Formula] or [Formula], and R ₂ is a hydrogen atom or a halogen atom) A pattern forming method characterized by using a resist containing one or more compounds selected from the group consisting of compounds represented by: 2. The upper resist has the following formulas:
2. The pattern forming method according to claim 1, wherein the resist includes any siloxane polymer having a ratio of X/[formula] in the range of 0.1 to 0.5 and a bisazide compound represented by the formula. 3. In the step of applying the lower resist, after applying the lower resist, it is baked at a low temperature so that it is soluble in a ketone solvent but insoluble in a developer. The pattern forming method described in section. 4. Any one of claims 1 to 3, wherein the developer used in the step of developing the upper layer resist is an aromatic hydrocarbon solvent or a mixed solvent of an alicyclic compound and an aromatic hydrocarbon. The pattern formation method described. 5. The pattern forming method according to claim 4, wherein in the developing step, an alicyclic compound is used as a rinsing liquid for rinsing.