JPS6029744A - Process for forming pattern - Google Patents

Abstract

PURPOSE:To make formation of submicron pattern of high accuracy easier and to increase throughput of an electron beam exposing device by using a thermally crosslinking and decomposing type photosensitive resin comprising a copolymer having high efficiency for decomposition together with a copolymer having high resistance to dry-etching. CONSTITUTION:On a substrate, positive photosensitive resin film for electron beam (EB) exposure is formed which consists of a mixture of a base first copolymer prepd. by copolymerising a monomer having resistance to dry etching with methacrylic acid and a second copolymer functioning as a crosslinking material and being prepd. by copolymerising a monomer having high decomposition efficiency with p-chloroformylphenyl methacrylate. Then, the film is heat-treated to cause crosslinking in both copolymers, and the second copolymer is decomposed selectively by irradiating with EB, then the decomposed part is removed by dissolving in a solvent to form a positive pattern from the photosensitive resin. Because of the excellent plasmatic property of the resin film, a submicron pattern is formed with high sensitivity and high resolution, and formation of submicron pattern for a semiconductor device is facilitated with high accuracy, and throughput of EB exposure is increased.

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a method for forming turns on a photosensitive resin used as a mask during dry etching of metals, semiconductors, and insulators, and particularly relates to a method for forming turns on a photosensitive resin used as a mask during dry etching of metals, semiconductors, and insulators. 0(b) on a method for forming a positive resin pattern using beam exposure technology Background of the technology In the manufacturing field of semiconductor deposition circuits (IC), performance areas, electrode contact windows, wiring EP'' turns are photosensitive. It is often formed by dry etching using a pattern made of resin (resist) as a mask.
As C becomes more highly integrated and its nodules become finer and more dense, electron beams (E
B) Efforts have been made to increase the use of drawing exposure technology.

In addition, positive type resists that can obtain submicron resolution are often used, and recently, the dry etching resistance that can be used as a mask for the above dry etching process and the high sensitivity to electron beams have mutually influenced each other. Thermal cross-linking and decomposition type resists are now being used, which have the advantages of being able to be selected independently without giving a It has become.

(c) Prior art and problems Polymer #/)'B It is widely known that the crosslinking point of flO is easily generated by the reaction between carboxylic acid and acid chloride, and the conventional thermal crosslinking point is formed by a combination.

However, since these crosslinking monomers have low surface plasma properties, even when a polymer with high dry etch resistance is used as the base polymer of the resist, the crosslinking monomers are It is decomposed and loses weight. Therefore, in order to maintain the maskability of the resist film, it is necessary to form the resist film thickly, which lowers the resolution during exposure and causes pattern deformation during dry etching. There was a problem that it became difficult to form a micron pattern.

(d) Purpose of the Invention The present invention provides a positive mask pattern that has high dry etching resistance (plasma resistance) that does not cause film loss during dry etching and has excellent resolution.
It provides a highly sensitive forming method using electron beam exposure, and its purpose is to improve the throughput of electron beam exposure equipment and to form highly accurate submicron patterns in semiconductor devices, etc. The goal is to make it easier.

(e) Structure of the invention That is, the present invention provides a pattern forming method in which a first copolymer serving as a paste in which a monomer having dry etching resistance and methacrylic acid are copolymerized is placed on a substrate, and a highly decomposable Forming a positive type photosensitive resin film for electron beam exposure consisting of a mixture of a crosslinking agent in which a monomer having high efficiency and p-chloroformylphenyl methacrylate are copolymerized and a second copolymer, Heat treatment is performed to crosslink the first copolymer and second copolymer in the photosensitive resin film, and the photosensitive #resin film is selectively irradiated with an electron beam to remove the electron beam irradiation area. The second copolymer is decomposed, and then the region of the photosensitive resin film that has been irradiated with the electron beam is selectively dissolved and removed using a solvent, thereby forming a positive image of the photosensitive I1H film. It is characterized by comprising a step of forming a mold pattern.

(f) Examples of the invention The present invention will be described below with reference to examples.

In conventional thermally crosslinked positive resists for electron beam (EB) exposure, crosslinking is performed using a combination of methacrylic acid and methacrylic acid chloride, as described above. Since the plasma resistance of these cross-linking monomers is low, when the base resist film is exposed to plasma irradiation, the main chain near the cross-linking point is cut and the resist film has a low molecular weight, which makes the paste polymer dry resistant. Even if a polymer with high etching properties was used, the dry etching resistance (f:l) was reduced to a certain extent, resulting in the thinning of the film as described above.

Therefore, in the present invention, p-chloroformylphenyl methacrylate is obtained by introducing a phenyl group (betain) having an electron-absorbing effect into the crosslinking monomer, that is, the above-mentioned methacrylic acid chloride, and this is used as a crosslinking monomer. By using this, a positive pattern is formed using a high plasma resistance resist that prevents decomposition during plasma irradiation.The above p-chloroformylphenyl methacrylate is, as is generally known, esterified from methacrylic acid chloride. It is obtained by introducing chlorine ((J?) into

In the present invention, the p-chloroformylphenyl methacrylate is used as a crosslinking agent by copolymerizing it with a monomer that has increased one-part efficiency (F; Bid degree) by adding four strongly polar groups or elements. Using. That is, for example (
P-1) A copolymer with α-chlorotrifluoroethyl acrylate shown in formula (P-2) and a copolymer with trichloroethyl methacrylate shown in formula (P-2).

In both (P-1) and (P-2), the ratio of p-chloroformylphenyl methacrylate is preferably 1 to 5.

Although the sensitivity of the crosslinking agent is somewhat lowered due to the six phenyl groups mentioned above, by combining it with a monomer having high decomposition efficiency as described above, performance can be obtained where the crosslinking effect can be ignored.

In addition, in the method of the present invention, a copolymerization system of a monomer whose plasma resistance is enhanced by the base polymer of the resist, etc., and methacrylic acid is used, and in the examples, ease of synthesis is treated. A copolymer of α-methylstyrene and methacrylic acid represented by formula (B-1) was used from the viewpoint of ease of use.

Then, q:r in formula (B-1) was set to 3 near, the average molecular weight Mw was set to 78,000, and the degree of dispersion was set to 421.

In the first embodiment, the Pace 4 Rimmer K (P-
2) A crosslinking agent consisting of a copolymer of α-chlorotrifluoroethyl acrylate and p-chloropolmylphenyl methacrylate with m:n=95:5 was added to 10
[:TnoJ%] was added to make a heavy cloth solution, which was coated onto a substrate to a thickness of about 0.5 to 0.6 [μm] using a spin cord method, and then 145 to 150 [μm] was added in nitrogen (N2). :'
Cross-linking is carried out at a temperature of 80 [minutes] at a temperature of 5 x 10-6 [C/crl', for example, and a positive pattern is formed using a strong resist at a strength of 5 x 10-6 [C/crl'.

At this point, the test pattern gives a l of 0.7 (μm).
A high-resolution eave having /S has been obtained. In addition, the plasma resistance (dry etching resistance) of the resist pattern is as follows: 95 = carbon tetrafluoride (CF'4) and oxygen (02)
5 was used as the etching gas, the etching gas pressure was 0.3 [Torr], and the high frequency (13.56 ml
lz) Plasma treatment was performed at a power of 170 [:W:] to obtain a low eratinbrae of 400 [:A/min]. This value shows that the dry etching resistance has been improved by about 1.3 to 1.4 times compared to 550 [fill] of a similar conventional resist using a crosslinking agent shown in formula (P-11) below. It is shown that.

In the second example, the same base polymer as above (
P-2) m of trichloroethyl methacrylate and p-chloroformylphenyl methacrylate shown in formula:
Using a resist film containing the same crosslinking agent as in the above example (10 [moA'%]) consisting of a copolymer of n = = 95:5,
A positive resist pattern was formed by exposure and development in the same manner as in the above example, and the dry etching resistance of the resist pattern was determined by plasma treatment at 420 [^/min] under the same conditions as above. Obtaining a low etching rate. This value is 550Cfiy' in a similar conventional resist using a crosslinking agent shown in the following formula (P-12-).
This shows that the dry etching resistance was improved by about 1.3 to 1.4 times.

1 The molecular weight of the photosensitive polymer shown in the above formulas (P=1) and (P-2) is preferably several hundred thousand, and in this example, (P-1)K is A compound with an average molecular weight of 220,000 was used, and a compound with an average molecular weight of 300,000 was used for (P-2'). In addition, the photosensitive agent Borima (P-11) in the resist used for comparison of dry etching properties was Mw
= 300,000, (P-12) has Mw = 400,000.

(, 9) Effects of the Invention As explained above, according to the present invention, it is possible to form a 111[plasma-like, extremely positive photosensitive resin 111 pattern with high sensitivity and a high 161 image resolution of submicrons. be able to.

Therefore, the present invention facilitates the formation of high-intensity submicron patterns in semiconductor devices and the like, and is also effective in improving the throughput of electron beam exposure equipment.

Claims (1)

[Claims] On the substrate, a first copolymer serving as a base is prepared by copolymerizing a monomer with high dry etching resistance and methacrylic acid, and a monomer with high decomposition efficiency and p-chloroformylphenyl methacrylate are copolymerized. A positive-working photosensitive resin for electron beam exposure consisting of a mixture with a second copolymer serving as a crosslinking agent and a second copolymer serving as a crosslinking agent is formed. The @1 polymer and the second polymer are crosslinked, and the A'' photosensitive resin film is irradiated with an electron beam to decompose the second copolymer in the 5z electron beam irradiation area. λ'), after the photosensitive resin film, the region of the photosensitive resin film irradiated with the electron beam is selectively removed using a solvent to form a positive pattern of the photosensitive resin film. A butter/forming method characterized by: