JPS63210840A - Negative type resist material and formation of negative type resist pattern - Google Patents

Abstract

PURPOSE:To obtain the titled material suitable for forming a fine pattern having high aspect ratio with the simple process by cohydrolyzing allyltrichlorosilane, chloromethyltrichlorosilane and aralkyl or aryl trichlorosilane. CONSTITUTION:The silicone which is shown by formula I and is produced by cohydrolyzing allyltrichlorosilane, chloromethyltrichlorosilane and aralkyl or aryltrichlorosilane, is used for the titled material. In the formula, R is benzyl or phenethyl group, etc., X, Y and Z are each shown a percentage. The photoresist film 12 is formed on a silicon substrate 10 having SiO gradient 11, thereby leveled the gradient 11 and formed the resist material layer 13 to obtain the pattern 14. The exposed part of the lower layer of the pattern 14 is etched with O2-RIE. Thus, the process at the time of forming the pattern is remarkably simplified, and the workability in the manufacture of the semiconductor device, etc., is rationalized. ANd, the titled method contributes to the improvement of the production yield.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a resist material for forming a fine resist pattern, and particularly to a method for forming a negative resist pattern with excellent dry etching resistance using electron beams and X-rays. It is something.

(Prior Art) In substrate processing during the manufacturing process of semiconductor devices, a resist pattern is formed on the substrate to be processed, and ion implantation and etching operations are performed using this as a mask.

In recent years, as the height of semiconductor devices has increased significantly by 1 m, there has been a strong demand for microfabrication of substrates at the submicron level. Therefore, dry etching using a reactive gas, which has excellent processing accuracy, is widely used in the etching process. On the other hand, however, such means do not provide sufficient selectivity in etching rate between the substrate to be processed and the resist, so the resist film must be made thick.

In general, on so-called step substrates associated with multilayer wiring, it is necessary to ensure a film thickness that can withstand dry etching, and to flatten the substrate in order to form a resist pattern that reduces dimensional fluctuations on the steps. For example, 2 μm
Even if the resist pattern is thick, it is necessary to
J, it is also necessary to form it with the dimensions below. For miniaturization, it is advantageous to reduce the thickness of the resist layer, and a three-layer resist method, for example, has been proposed as a method to satisfy these conflicting demands (Journal Vacuum Society Technology, J. Vac, Sci.
.

Tachno I, 16(6), 1620-162
4 (1979)).

This method will be explained with reference to FIG. A photoresist layer 2 with a thickness of 2 to 3 .mu.m for flattening steps is formed on a substrate 1, and a 0.1 .mu.m thick 5IO2 intermediate layer 3 and a resist lower layer 4 for patterning are provided in this order. Next, the light
After forming a desired pattern 5 with an energy beam such as an electron beam or soft Xs, and etching the intermediate layer 3 with CHF3 gas plasma, the lower layer 2 is similarly etched with 02 gas plasma to form a resist pattern with a high aspect ratio. It is something that forms. In this method, by making the upper resist layer 4 thinner, resolution is improved and submicron patterns can be formed with good shape.

(Problems to be Solved by the Invention) However, this three-layer resist method has problems such as the formation process becoming complicated as the number of resist layers increases, and the etching process also increases. Simplification was strongly desired.

It is an object of the present invention to provide a resist material and a pattern forming method suitable for eliminating the above-mentioned increase in the number of steps and operational problems and forming a fine pattern with a high aspect ratio in a simple process. do.

(Means for Solving the Problems) In order to solve the above problems, the present inventors considered that a so-called ladder type silicone resin having a cross-linking reactive group was suitable as an electron beam resist, and conducted studies.

In general, ladder-type silicone resins have a high content of silicon and oxygen due to their structural characteristics, so 02-RIEWI
Highly 4-sexual.

Further, as the crosslinking reactive group, high sensitivity can be achieved relatively easily by using a group having high chain reactivity such as an allyl group, but at the same time, resist contrast is inevitably lowered. Therefore, it is recommended to introduce a sequential reaction type group such as a chloromethyl group or a group that increases the glass transition point such as an aromatic ring at the same time as the above-mentioned chain-reactive group. This is effective in preventing pattern deterioration due to swelling over time. However, the introduction of the above-mentioned aromatic ring has a limit as the electron beam energy is partially consumed in stabilizing the resonance of the aromatic ring, resulting in a decrease in sensitivity.

The negative resist material of the present invention is formed by cohydrolyzing allyltrichlorosilane, chloromethyltrichlorosilane, and aralkyl or aryltrichlorosilane, and has the general formula: (CH=CHCH25iO,,) x・(CtCH2S
i0,7□) , -(R8iO,,.]2 (wherein, R is benzyl, phenethyl, phenyl, P
-bromophenyl, P--/bromophenyl.

(x, y, z indicate percentages).

Then, two layers of organic resist are provided on the substrate, and a resist material according to the above general formula is used as the upper layer resist to form a pattern.

In the above general formula representing the resist material of the present invention, the specific values of the percentages X, Y, and Z are determined from the viewpoint of sensitivity to electron beams, or at least 20%, Y is at least 20%, and Z is 10 to 10%. It is desirable that the molecular weight is in the range of 20%, and the molecular weight thereof is 5. It is particularly desirable that it be between ooo and 30,000. R is an aralkyl or aryl group, such as benzyl, phenethyl,
Phenyl.

P-bromophenyl, P--/romophenyl, P-
You can choose from trills. In the above formula, if the range of Z is 10% or less, the resolution will decrease, and 2
If it is 0% or more, it is not recommended because the sensitivity will decrease.

In addition, the resist material of the present invention may be used on a substrate having steps.
The layered resist pattern is specifically formed as shown in FIG. 1, for example. Si0 step with a height of 1.2 μm (
11) A photoresist film I is formed on the silicon substrate 10.
2 is formed to have a thickness of 2 μm to flatten the step 11. Next, a layer of the resist material of the present invention (131, more specifically, a polymer 3 described in Examples below) is formed to a thickness of 0°3 μm, and drawing is performed using an electron beam.The irradiation dose in this case is 6.2 μC/d.
Although it depends on the pattern, it is preferable to use an irradiation amount that results in a residual film of about 0.6. By developing this, a pattern 14 is obtained, and the exposed portion of the lower layer is etched with 02-RIE.
The pattern is μm wide.

(Function) In the present invention, as a substitute for the upper layer and the middle layer in the conventional three-layer resist method, a general-purpose compound obtained by cohydrolysis of allyltrichlorosilane, chloromethyltrichlorosilane, and aralkyl or aryltrichlorosilane is used. A silicone resin represented by the formula is used, and as will be described in detail later, this resin has high sensitivity to electron beams, and has the characteristics of extremely little film loss during reactive ion etching using oxygen gas. have. Therefore, this layer can be made extremely thin, and has an effect suitable for forming a detailed upper layer pattern.

(Example) This invention will be explained below with reference to specific examples.

Prepolymer 1 Preparation of prepolymer 1 Allyltrichlorosilane 3.2 g (18 mo/).

Chloromethyltrichlorosilane 1.1 g (6wol
) and 1.7 g of bromophenyltrichlorosilane (6I
IIllOI) to methyl isobutyl ketone (hereinafter M[B
K) 28m# and tetraheptadurofuran (hereinafter referred to as T
It was dissolved in a 310 mj mixed solvent called HF and cooled to 0°C in a water bath. Next, in this, hetriethylamine (hereinafter referred to as Et3N) 3. Og (30 woj) was added dropwise over 5 minutes, and the resulting solution was stirred for 5 minutes, then 5 g of water was added dropwise over 15 minutes, and stirring was continued for 1 hour. Next, the water bath was removed, and the mixture was heated and refluxed for 4 hours.

After cooling to room temperature, the mixture was diluted with 200 mj of ethyl acetate, and the aqueous layer was removed. The organic layer was washed with water until it became neutral, and then with saturated brine. After drying the obtained organic layer over anhydrous magnesium sulfate, the desiccant was filtered off, and the solvent was distilled off under reduced pressure to obtain 4.4 g of a pale yellow oil. This will be referred to as Prepolymer 1.

Preparation of Prepolymer 2 Allyltrichlorosilane 1.4 g (8meoj)
, chloromethyltrichlorosilane 5.1 g (28f
Except that 1.2 g (4 ml) of P-bromophenyltrichlorosilane and 1.2 g (4 ml) of P-bromophenyltrichlorosilane were used, the amounts of other reagents, reaction conditions, and post-treatment were the same as in Preparation 1 above to obtain 4.2 g of a pale yellow solid. is defined as prepolymer 2.

Preparation of Prepolymer 3: 1.4 g (8 wof) of allyl trichlorosilane, 15.1 g (28 mo of
j) and benzyltrichlorosilane 0.9g (4wao
The same procedure as in Preparation 1 above was carried out except that 1) was used to obtain 4.1 g of a pale yellow solid, which was designated as Prepolymer 3.

Preparation of Aburi Enini Dandan 1 Polymer 1 The above prepolymer 1 2. Og was dissolved in 2.0 g of MIBK and stirred, and after adding 2 g of Et3N O, stirring was continued at room temperature for 2 hours. The mixture was then cooled to 0° C., stirred and pressed into 100 ml of methanol. Stirring was continued for an additional 15 minutes, and the resulting precipitate was filtered off. The obtained precipitate was washed once with 50 ml of cold methanol, and then vacuum dried at room temperature to obtain 1.1 g of colorless polymer 1. Its weight average molecular weight was about 12,000.

Preparation of Polymer 2 Prepolymer 2 described above 2. When Og was treated under exactly the same conditions as in the preparation of Polymer 1, 1.3 g of colorless Polymer 2 (weight average molecular weight of about 21,000) was obtained.

Preparation of Polymer 3 2.0 g of the above Prepolymer 3 was treated under the same conditions as above to obtain 1.3 g of colorless Polymer 3 (weight average molecular weight approximately 19,500).

Preparation of Polymer 4 2.0 g of Prepolymer 2 was treated under the same conditions as above except that the polymerization time was 6 hours, and 1.4 g of colorless Polymer 4 (weight average molecular weight about 23,000) was obtained.

Examples 1 to 5 The prepolymers and polymers obtained as described above were prepared using aromatic solvents such as benzene, toluene, xylene, and chlorobenzene, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, and acetic acid. Ethyl, 2-methoxyethyl acetate, 2-acetic acid
-Ethoxyethyl.

All of these solvents are soluble in esters such as n-butyl acetate, and resist solutions can be prepared using these solvents.

Here, the above prepolymer 2. Polymer 4. Same 5゜ Same 6.
and 7, each with a resin concentration of 25 wt%.

It was dissolved in MIBK to give a concentration of 15 wt%, 15 wt%, 15 wt%, 15 wt%, and filtered through a filter with 0.2 μm pores.

Next, each of the above resist solutions was applied to a thickness of 0.4 to 0.5 μm onto a silicon wafer coated with 2 μm thick hard-baked Microposit 2400 photoresist.
The film was spin-coated to a desired film thickness and baked on a hot plate at 80° C. for 1 minute.

Next, on this substrate, a plurality of patterns were drawn using an electron beam with an accelerating voltage of 20 KV, with 10 sets of 1 μm line and spaces as one pattern, while changing the irradiation dose. Then, this substrate was developed using MIBK as a developer for 1 minute by an immersion method, and rinsed with 2-proper tool for 15 seconds. The residual film thickness of each of the obtained patterns was measured, and the values normalized by the film thickness originally applied were plotted against the logarithm of the irradiation dose to create a characteristic curve. Sensitivity obtained from these (
The irradiation dose when the residual film rate is 0.5) and the γ value (the points where the tangent line at the point of the residual film rate of 0.5 on the curve intersects the straight line with the residual film rate of 0 and 1 are Q, D: Table 1 Next, the 02-RI E #4 properties of the resins shown in Table 1 above were evaluated.Each resist solution was formed on a silicon wafer so that the resist film was 0.4 to 0.5 μm thick, and then heated on a hot plate. Baking was performed at 80° C. for 1 minute.

These were processed using a parallel plate type dry etching car at 02 gas pressure 1
．． 5 Pa, power density 0.08w/c++? , 02
Etching was performed with a gas flow rate of 20 seconds IT+. These times were set as the time (25 minutes) for completely etching a silicon wafer with a 2 μm thick Microposit 2400 photoresist film placed at the same time. After etching, the remaining film thickness of each resist was measured and the etched amount was calculated to be 0.08 μm in Example 2.

Example 1. Same 3. There is almost no difference between 4 and 5, 0.0
It was 7 μm.

Next, a hard-baked microposit photoresist 2400 was applied as a planarization layer on a silicon substrate having a 1 μm wide SiO pattern with a height of 1.2 μm.
The resist solution of Example 4 was further spin-coated and baked on a hot plate at 80° C. for 1 minute to form an upper resist film with a thickness of 0.3 μm. 2 to this
Various patterns were drawn using a 0 KV i4 consonant beam at a dose of 6.2 μc/cd, and development was performed to obtain upper layer patterns. When the two-layer resist pattern obtained by performing etching for 40 minutes under the same conditions as above was observed with a scanning electron microscope, a pattern with a width of 0.5 μm was resolved.
The height was approximately 2.2 μm, the initial thickness was maintained, and the shape was approximately vertical.

(Effect of the invention) As is clear from the above detailed explanation and the results of the examples,
The present invention replaces the upper and middle layers in the conventional three-layer resist method with electron beam-sensitive silicon*N1 obtained from the allyltrichlorosilane, chloromethyltrichlorosilane, and aryl or aralkyltrichlorosilane.
By changing the structure to a two-layer structure, the process during pattern formation is greatly simplified, and the workability in manufacturing semiconductor devices and the like can be significantly streamlined, and at the same time, it can contribute to improving the yield.

[Brief explanation of the drawing]

FIG. 1 is a process explanatory diagram of the method of the present invention, and FIG. 2 is a process explanatory diagram of the conventional method. 10...Substrate, 12...Resist bottom 4.13...
upper layer of resist. Figure 11 Figure 2

Claims (6)

[Claims] (1) Allyltrichlorosilane, chloromethyltrichlorosilane, and aralkyl or aryltrichlorosilane are co-hydrolyzed, with the general formula (CH_2=CHCH
_2SiO_3_/_2)_X・(ClCH_2SiO
_3_/_2)_Y・(RSiO_3_/_2)_Z (wherein, R is benzyl, phenethyl, phenyl, p
- Chlorophenyl, P-bromophenyl, or P-tolyl, and X, Y, and Z indicate percentages) A negative resist material. (2) The negative resist material according to item 1, wherein the material represented by the general formula in item (1) above has a molecular weight of 5,000 to 30,000. (3) If the percentage in the general formula in (1) above is X:
2. The negative resist material according to item 1, wherein Y: 20% or more, Z: 10 to 20%. (4) On the substrate on which the organic polymer layer has been formed, an electron beam-sensitive silicone resin solution represented by the general formula below is applied and dried to form a resist film, and this is selectively irradiated with an electron beam and the non-irradiated A method for forming a negative resist pattern characterized by removing a portion. (CH_2=CHCH_2SiO_3_/_2)_X・
(ClCH_2SiO_3_/_2)_Y・(RSiO
_3_/_2)_Z (However, in the formula, R is benzyl, phenethyl, phenyl, P
- Chlorophenyl, P-bromophyl, or P-tolyl, where X, Y, and Z indicate percentages) (5) The method for forming a resist pattern according to item 4, wherein the unirradiated portions in item (4) are removed by dissolving with a ketone solvent in a conventional manner. (6) The method for forming a resist pattern according to item 4, wherein the unirradiated portions in item (4) are removed by etching using reactive gas plasma.