JPS61151536A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To enable a micropattern to be formed by forming a photosensitive polymer material having Si-(Si)n bonds, n being an integer of 1-5, in the molecule, on an org. layer, exposing it to light, and selectively dissolving the exposed parts with a cellosolve type solvent. CONSTITUTION:The org. layer formed on a substrate is coated with the soln. of the photosensitive polymer material having repeating units each represented by formula I, R1 being a divalent org. group, each of R2-R5 being methyl, ethyl, propyl, or phenyl, and an being an integer of 1-5, and dried to form the photosensitive polymer layer. It is selectively exposed to light, and developed with the cellosolve type solvent to form a resist pattern. Said material is highly sensitive to UV rays, and a micropattern can be formed by the ordinary lithographic tecnique, and a positive type resist pattern can be obtained by exposing a photoresist layer made of said material and developing this latent pattern with the cellosolve type solvent to dissolve off the exposed parts selectively.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for forming a fine resist pattern, in which photolithography technology is used especially in a board with excellent dry etching resistance, and will continue to be used in the future. It seems likely that graphical techniques will continue to be used.

In recent years, in order to increase the density and integration of semiconductor devices, it has been required to form fine patterns with a width of 1 μm or less. To meet this requirement, dry etching techniques are replacing traditional wet etching techniques. Resist materials used in photolithography techniques are required to have high sensitivity and high resolution, as well as excellent resistance to dry etching.

To form ultra-fine resist patterns.

Although it naturally depends on the type of resist material and phosphorography method used, it is extremely effective to reduce the thickness of the resist used.

However, since wiring etc. have already been formed on substrates for semiconductor devices and the like before resist is applied, the substrate surface is not smooth, and thinning the resist film leads to an increase in resist defects such as pinholes. Not practical.

Furthermore, from the viewpoint of resistance to dry etching, the resist film thickness cannot be made too thin.

Recently, resist patterns with high resolution and excellent dry etching resistance have been developed.

(JlM, Mo
Ranand DoMaydan, J., Vac.
Sci, Technol, 16i6).

1620-4 (1979)). In the three-layer resist method, as shown in FIG. 1, a first organic layer 2 (for example, phenol novolank resin, film thickness 1 to 2 μm) is formed on a substrate 1, and a second inorganic material R3 ( For example, a metal vapor deposition film or a silicon dioxide film (thickness: 0.2t1rn) is formed, and on top of this, a third resist layer 4 (thickness: 0.2-0.3μrr) is formed.
After forming L) and patterning the third resist layer with light or soft X-rays, etching the second inorganic layer,
Using this as a mask, the first organic layer 3 is dry-etched using oxygen plasma or the like.
This is a method of forming. Note that the third resist layer is removed during oxygen plasma etching.

The characteristics of this three-layer resist method are that ultra-fine patterns can be obtained by making the third resist layer thinner, and that a material with excellent dry etching resistance is used for the first organic layer. The object is to obtain a resist film having excellent dry etching resistance.

However, since this method requires a long process, it is strongly desired to simplify the process.

In addition, it is extremely difficult to form a second inorganic layer on the first organic layer because it is usually performed by a vapor deposition method or the like, and there has been a strong desire for improvement.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the above-mentioned prior art and provide a method for forming a fine resist pattern with a simple process. [Summary of the Invention] This is the result of extensive research to find a resist material that has both the properties of the second and third layers in Figure 1.

A photosensitive polymer material having Si+Si+ bonds (wherein R represents an integer from 1 to 5) in the molecule is formed on the first organic layer, irradiated with light, and developed using a cellosolve solvent. We have discovered that a fine resist pattern can be formed by selectively dissolving the light-irradiated areas with a liquid.

In other words, the above-mentioned photosensitive polymer material has high sensitivity to ultraviolet rays, 1 fine patterns can be formed by ordinary photolithography technology, and the patterned resist film is extremely resistant to oxygen plasma. High (・
It is highly resistant and has the characteristic that it does not cause any film peeling even when exposed to oxygen plasma for a long period of time.

Furthermore, when a photoresist layer made of the above-mentioned photosensitive polymer material is patterned by irradiation with light and developed with a cellosolve-based solvent, only the light-irradiated areas are dissolved in the cellosolve-based solvent, resulting in a positive resist pattern. It has a percentage mark.

Therefore, when performing microfabrication on a wiring board with one level difference, first coat an organic layer made of phenol novolac resin or the like to a thickness of 1 to 1000 pm as the lower layer, dry it, and then form the upper layer with Si in the molecule. ←Si+ bond (
However, a composite resist structure is prepared by coating an organic layer made of a photosensitive polymer material with a thickness of 01 to 03 μm, and the upper layer is coated with the desired shape through a mask. After a portion is exposed to light, developed using a cellosolve solvent, and buttered, the lower layer may be dry etched using oxygen plasma using the buttered upper layer as a mask.

It can be seen that if patterning is performed using the composite resist layer thus prepared, the following advantages are obtained.

(1) Since the difference in solubility in the developer between the light irradiated area and the non-irradiated area is extremely large, a resist pattern can be formed with a small irradiation dose.

(2) Since the resist layer (5 in FIG. 2) can be made thinner, extremely fine patterns can be formed.

(3) By using an organic layer having high resistance to chlorine-based or fluorine-based dry etching gases as the lower layer, it is possible to form a resist pattern with excellent dry etching resistance.

(4) Since both the upper layer and the lower layer can be coated by a conventional spin coating method, a composite resist layer can be formed by an extremely simple method.

Next, one material used in the present invention will be explained. What are the sensitive organic polymer materials used in photoresists?

(However, in formula 1, R1 is a divalent organic group, R2+ R3r
R4 and R5 represent either a methyl group, an ethyl group, a propyl group, or a phenyl group, and R represents an integer from 1 to 5) A polymeric material whose main component is a repeating unit is used. .

In the general formula, R1 is a divalent organic group, specifically (5)
A divalent organic group that has only an aromatic ring structure.

(B) A divalent organic group having an aromatic ring structure and a chain structure, (Q alkylene group, or (D) a divalent organic group containing a heteroatom, etc.).

, −(j(2+CH2−, etc.).

(Specifically, q is -CH2CH2, CH2CH2
CH2- etc.

(2) Specifically, +O+, -()- and. In the aromatic ring contained in the above-mentioned organic group.

It is also possible to use one substituted with one or more halogen atoms, alkyl groups, etc. for example.

In the general formula -R21R3r R4 and R5 are methyl groups.

It represents an ethyl group, a propyl group, or a phenyl group, and may be the same organic group, but from the viewpoint of solubility of the polymer material, two or more organic groups (for example, * R2+ R4 is a methyl group, Ra pRs is an ethyl group)
It is desirable that the

The polymer material of the present invention is toluene and xylene.

It is used by dissolving it in a general-purpose organic solvent such as benzene or p-cymene. The concentration is preferably 5 to IQ wt%.

Also, what is the average molecular weight of the polymer material of the present invention?

Toooo to 50,000 is preferable from the viewpoint of resist sensitivity.

Examples of the developer used in the present invention include cellosolve-based solvents such as methyl cellosolve, ethyl cellosolve, and loop tyl cellosolve.

These may be used alone or in combination of two or more. Further, this cellosolve-based solvent may be used in combination with general-purpose organic solvents such as toluene, isoamyl acetate, isopropyl alcohol, and cyclohexanone.

The resist material used in the above-mentioned invention is as follows.

The 5i-si bond is efficiently cleaved by light irradiation.

The molecular weight of the polymer decreases, and silyl radicals generated by light irradiation react with oxygen, forming siloxane bonds (-
8i-0-8i). As a result, the light irradiated area is selectively solubilized in a developer consisting of a cellosolve solvent,
A positive resist pattern can be obtained. The above-mentioned resist material has extremely high resistance to oxygen plasma, and no film deterioration is observed even if it is left in oxygen plasma for a long time. This is considered to be because a 5i02-like film is formed on one surface layer by exposure to oxygen plasma.

In addition, in the two-layer resist method using the resist material used in the present invention as the upper layer, the lower organic layer may be made of, for example, phenol novolac resin, cresol novolak resin, polyimide resin, polymethacrylic acid ester polymer, polystyrene, ketone, etc. Examples include polymers such as

In the two-layer resist method, what is particularly important is that the lower layer is not swollen when the upper resist layer is applied, and that dissolved polymers are not re-attached during development, and cellosolve solvents are excellent from this perspective as well. .

Also to improve the sensitivity of the resist.

It is effective to add a general-purpose radical scavenger such as 2.6-di-t-butyl-cresol or 2.6-di-t-butyl-p-benzoquinone.

[Embodiments of the invention]

Synthesis Example 1 16.0% of ethylmethyljethoxysilane was placed in a 500rrL three-bottle flask equipped with a stirrer, a condenser, and a 9-dropping funnel.
2g, magnesium 2.43p and tetrahydrofuran i
o ornl was added and stirred, and 100 ml of a tetrahydrofuran solution containing 11.8 N of p-dibromobenzene was added dropwise from the dropping funnel under a nitrogen stream over about 3 hours. After dripping,
The mixture was further refluxed for about 5 hours while stirring was continued. After refluxing, it was filtered, the solvent was distilled off, and p-bis(ethylmethylethoxysilyl)benzene 10.5% was distilled under reduced pressure. !
? (Yield: 68%) (Boiling point: 122-125℃ 73m
I got diI.

NMR spectrum (CDC13) δ(1)1111)
: 0.42(S).

0.86-1.08 (→, 1.26(t), 3.
74(q), 7.56(J') Next, the p- obtained earlier
Bis(ethylmethylethoxysilyl)benzene 9.3
By refluxing g and acetyl chloride 12.9 hours for about 5 hours, p-bis(chloroethylmethylsilyl)benzene 8.6.9 (yield: 98%) (boiling point: 131~
135°C/3m*Hg) was obtained.

NMR spectrum (CDCA'a) δ(4): 0.
68 (J).

1.12(y), 7.68(#) Synthesis Example 2 1.2 g of sodium was added to a 200rrL three-bottle flask equipped with a stirrer, a condenser, and a dropping funnel under a nitrogen stream.
30 rrtl of a toluene solution containing 5.8 g of p-bis(chloroethylmethylsilyl)benzene obtained in Synthesis Example 1 was slowly added dropwise to about 5,077 Ll of the Tescher's toluene solution, and the mixture was heated at 70 to 80°C for about 20 hours. After heating, the obtained polymer was mixed with benzene-ethanol (1:
1 by vol,) solution with a yield of about 65%.

44 words CH3) (C2H3) Si (CH3) (
C2H3) ÷ white polymer powder (melting point: 186-189)
°C) was obtained.

Number average molecular weight: 2500O NMR spectrum (C6D5.) δ (IP): 0.
34 (J=).

0, g4 (broatL s ), 7.28 (-
r) Synthesis Example 3 Methylphenyldiethoxysilane 123 was placed in a 500 ml three-necked flask equipped with a stirrer and a condenser with 9 dropping funnels.
g, magnesium 14g and tetrahydrofuran 100r
rLl was added and stirred, and a tetrahydrofuran solution of p-dibromobenzene 699 xoomi was added dropwise from the dropping funnel under a nitrogen stream over about 3 hours. After dripping, t? The mixture was further refluxed for about 5 hours while stirring was continued. After refluxing, P was separated, the solvent was then distilled off, and parabis(methylphenylethoxysilyl)benzene 93,9 (yield near 8%) (boiling point: 213-b NMR spectrum (CC14) δ< wa): o, r6
<3H.

S + Me-8t-), 1.36 (3H,t, C
H3C), 3.94 (2H,q, ClI2-8L)
+7.4~7.8 (7H, yi, ringprot
ons) Next, 92 g of the previously obtained para-bis(methylphenylethoxysilyl)benzene and 250 y of acetyl chloride were refluxed for about 5 hours to obtain para-bis(chloromethylphenylphenyl A'/It) with a yield of 94%. /l/ ) to 7 sef82. S' (boiling point: 229-232°C/3 m
x) (@) was obtained.

NMR spectrum (CC14) δ (Ilplm): 1
．． 00 (3H.

s, Me-8i), 7.5-7.8 (7H, m,
ring protons') Synthesis Example 4 Into a 300 WL three-bottle flask equipped with a stirrer and a condenser and a dropping funnel, add 1 to about 100 ml of toluene desparate solution containing 5 g of sodium under a nitrogen stream.Synthesis Example 3
10 omJ of a benzene solution containing 15 g of para-bis(chloromethylphenylsilyl)benzene obtained above was slowly added dropwise, and the mixture was heated at 70 to 80°C for about 20 hours. After heating, the obtained polymer was mixed with benzene-ethanol (1:1 byvo
l) Reprecipitation with solution.

With a yield of about 65% ÷73-8i (CHa)(C5Hs)
) (C6H5) (melting point: 155-163°C) was obtained.

Number average molecular weight: 34.00O NMR spectrum (C6D6”lδ(Wa) + 0.
64 (3H.

s, Me-86), 7.26 and 7.30
(7H, ringprotons) Example 1 A 0.2 μm thick polymer film was formed by spin coating a 5% by weight solution of the polymer obtained in Synthesis Example 2 in toluene on a silicon substrate.
Bake at 0°C for 30 minutes.

A 500W xenon-mercury lamp (irradiation intensity: 254?Lm) was passed through this through a quartz mask.

20 mW/cnt) was irradiated for 10 seconds. After irradiation, the image was immersed in ethyl cellosolve for 1 minute, developed, and then rinsed with isopropyl alcohol.

A positive resist pattern with a line width of 0.5 μm was obtained.

Example 2 As shown in FIG.
roposit 1370) to a thickness of 2 μm,
After baking at 00G for 30 minutes, a 5% by weight solution of the polymer obtained in Synthesis Example 4 in toluene was spin-coated to form a 0.3 μm thick polymer thin film, and baked at 100° C. for 30 minutes.

A first organic layer 2 and a photosensitive polymer layer 7 were formed.

To this, 1507aJ 1Crd (at 254rLm
), the film was developed using ethyl cellosolve-isoamyl acetate (95:5 by volume) for 15 seconds, and rinsed with isopropyl alcohol.

Next, oxygen plasma etching (etching conditions:
RF 200W, 02 pressure: 3mtorr,
Cuff-hyass voltage: -120 to -100V)
The lower organic layer was etched in about 20 minutes.

In this way, it was possible to form a fine pattern 5 with an aspect ratio of 3 or more and a line width of 0.5 μm.

Examples 3 to 10 Resist was formed and patterned in the same manner as in Example 2 under the conditions shown in Table 1, and it was confirmed that extremely fine resist patterns with an aspect ratio of 3 or more could be formed extremely easily. .

juice)・Exposure conditions: 200mJ/(n(at 254a
m') Irradiation/lower organic layer: polyimide film (2.0μ
Oxygen plasma conditions: RF 200W, 0
2 pressure: 3rntorr cathode bias voltage knee 120~-toov - The mixing ratio of the developer and the rinse solution is expressed as a volume ratio.

〔Effect of the invention〕

As is clear from the above explanation, by using the method for forming a resist pattern according to the present invention, it is possible to form an ultra-fine resist pattern with a small amount of light irradiation, and it is extremely suitable for manufacturing ultra-fine semiconductor devices, etc. It is.

[Brief explanation of the drawing]

The first figure is a schematic cross-sectional view showing a resist structure formed by a three-layer resist method. FIG. 2 is a schematic cross-sectional view showing a resist structure formed by a two-layer resist method. l...substrate, 2... first organic layer. 3... Second inorganic layer, 4... Third resist layer. 5... Fine pattern, 6... Silicon substrate. 7... Photosensitive polymer layer. Procedural amendment (voluntary)

Claims (1)

[Claims] 1. On the organic layer of the substrate on which the organic layer is formed, the general formula (1
) A solution of a photosensitive polymer material having repeating units represented by is applied and dried to form a photosensitive polymer layer,
A method for forming a resist pattern, which comprises selectively irradiating light and then developing with a cellosolve solvent to dissolve and remove the light irradiated areas. ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・[1] (However, in the formula, R_1 is a divalent organic group, R_2, R_3
, R_4 and R_5 represent either a methyl group, an ethyl group, a propyl group, or a phenyl group, and n represents an integer from 1 to 5) 2. In claim 1, the general formula (1) A method for forming a resist pattern, in which a solution of a photosensitive polymer material having the repeating unit shown above contains 90 to 95 wt% of a solvent and 10 to 5 wt% of a solute. 3. A method for forming a resist pattern according to claim 1, wherein the photosensitive polymer layer has a thickness of 0.1 to 0.3 μm. 4. The method for forming a resist pattern according to claim 1, wherein the cellosolve solvent is at least one selected from methyl cellosolve and ethyl cellosolve.