Polymer and a forming method of a micro pattern using the same

Details Polymer and a forming method of a micro pattern using the same Polymer and a forming method of a micro pattern using the same

1999-04-29

2001-05-01

Ashton, Rosemary E. (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Imaging affecting physical property of radiation sensitive...

Radiation sensitive composition or product or process of making

C430S315000, C430S329000, C526S262000, C526S264000, C526S281000

Reexamination Certificate

active

06225020

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a polymer useful as a photoresist in a lithographic process for fabricating a semiconductor device, and a method of forming a micro pattern using the same. More specifically, the present invention relates to a polymer which can be used in a photoresist composition for forming an ultra-micro pattern in the manufacture of 4G and 16G DRAM semiconductor chips using short wavelength light sources, such as KrF (248 nm), ArF (193 nm), an e-beam, or an ion-beam. The polymer of the present invention is particularly useful in a photoresist composition for the top surface image (TSI) process using silylation, or can be used for a single-layer photoresist.
In the manufacturing process of a semiconductor element, a photoresist is generally used to form a pattern with a fixed form on a semiconductor element. To obtain the desired photoresist pattern, a photoresist solution is coated on a surface of a semiconductor wafer, the coated photoresist is exposed to patterned light, and then the wafer undergoes a developing process. As a result, a photoresist pattern is formed on the wafer.
If the photoresist pattern is manufactured using a conventional silylation process, the photoresist is usually composed of diazonaphthoquinones compounds and a novolac resin, or a photo acid generator and polyvinyl phenol resin. When the photoresist resin is exposed to the patterned light source (e.g. ArF, KrF, or I line) and then baked, an alcohol group (R—O—H) is formed in the resin at the exposed regions. After baking, the photoresist resin is silylated with a silylation agent such as hexamethyl disilazane or tetramethyl disilazane. In the silylation process, an N—Si bond is first formed, but since the N—Si bond is weak, it then reacts with the R—O—H group in the photoresisit polymer to form a R—O—Si bond. The photoresist resin with bonded silicon atoms then undergoes a dry developing using O
2
plasma to form a silicon oxide film. The lower portions of the silicon oxide film remain even after the development of the photoresist and as a result, the desired pattern is formed.
The above-described silylation process for forming a photoresist pattern has several deficiencies when it is used with shorter wavelength radiation. In particular, when a KrF eximer laser is used as the light source to expose known photoresist polymers, it is impossible to form an ultra-micro pattern less than 0.10 &mgr;m L/S using the silylation process. When an ArF light source is used, the lens of the exposer can be damaged due to the high energy level of the ArF light. Therefore, the photoresist must be exposed to a lower amount of energy, for example, less than 10 mJ/cm2. If the photoresist is not exposed sufficiently to this lower energy, the desired pattern is not formed.
SUMMARY OF THE INVENTION
It has been found that the unique photoresist polymers of the present invention solve the above-described problems of the prior art. The heat-resistant character of the polymers of this invention allow the high temperatures required by the post-exposure baking and silylation steps of the TSI process to be obtained. The polymers of the present invention are particularity suited for use in chemically amplied photoresists wherein a photoresist pattern can be resolved even using a small amount of energy (e.g., 10 mJ/cm
2
), thereby preventing the damage to the lens of the exposer and the photoresist pattern collapse or insufficient resolution which occurs in the prior art during the formation of the micro pattern using an ArF (193 mn) light source. In addition, the polymers of the present invention are advantageously used in the silylation process wherein a chemically amplified photoresist and O
2
plasma are used to form a silicon oxide film which increases the etching and heat resistance of the photoresist such that an acceptable micro pattern can be formed using the dry developing process.
In one embodiment, the present invention relates to a polymer which is suitable for use as a single layer photoresist, and preferably as a photoresist in the TSI process. Preferred photoresist polymers of the present invention are represented by the following Formula 1:
wherein, R
1
is a C
1
-C
10
straight- or branched-chain alkyl group, or a benzyl group; R
2
is a C
1
-C
10
primary, secondary or tertiary alcohol group; m and n independently represent a number from 1 to 3; and X, Y, and Z are the respective polymerization ratios of the co-monomers; the ratio X:Y:Z preferably being (10-80 mol %):(10-80 mol %):(10-80 mol %).
Another embodiment of the present invention relates to a preparation method for the polymer represented by the above Formula 1.
In still another embodiment, the present invention relates to a photoresist composition containing the polymer represented by the above Formula 1, a solvent, and a photoacid generator.
In a further embodiment, the present invention relates to a method of forming a micro pattern using the above-described photoresist composition.


REFERENCES:
patent: 4857435 (1989-08-01), Hopf et al.
patent: 5312717 (1994-05-01), Sachdev et al.
patent: 5843624 (1998-12-01), Houlihan et al.
patent: 6001739 (1999-12-01), Konishi
patent: 6028153 (2000-02-01), Jung
patent: 2 320 717 (1998-07-01), None
patent: 5-297591 (1993-11-01), None
Aldrich Chemical Catalog, 1990-91, pp. 618, 984, 985.

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