JPH04304616A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To provide a formation method for a resist pattern in forming a pattern excellent in resolution by removing the electrification of the resist layer during the formation of a pattern, and keeping the distance between a wafer and an X-ray mask constant. CONSTITUTION:The resist pattern formation method prevents the electrification of a resist layer by the ionization during proximity exposure using radiation and prevents the fluctuation of the distance between a mask and a wafer being arranged in close vicinity by conductively treating the surface layer of the radiation sensitive resist layer with a cationic or ampholytic surface active agent.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to large-scale integrated circuits (LS
The present invention relates to a lithography method used when printing a fine pattern such as I) on a wafer or the like by radiation exposure.

0002

[Prior Art] Large-scale integrated circuits represented by DRAM are currently in the mass production period of 4M DRAM, and even 16M DRAM.
Technology is rapidly progressing from M to 64M DRAM. Along with this, the minimum line width required for devices has also been reduced from half a micron to a quarter micron. These semiconductor devices are transferred from a mask to a semiconductor substrate using near-ultraviolet light or far-ultraviolet light, but the line width of devices that can be processed using these wavelengths of light is approaching its limit. Further, the depth of focus inevitably decreases with miniaturization. Therefore, a lithography technique using X-rays with an even shorter wavelength has been devised, and there are great expectations that this will solve the above problems at the same time.

0003

[Problem to be solved by the invention] However, when exposed to radiation with high photon energy such as X-rays,
When attempting to form a resist pattern, the ionization effect of X-rays reaching the photosensitive resin layer coated on the substrate causes the photosensitive resin layer to become electrically charged, causing the X-ray mask placed close to the wafer to become charged. Due to electrical effects, the distance between these wafers and the X-ray mask cannot be kept constant,
Furthermore, a serious problem may arise in that the mask and wafer come into contact with each other. If the distance between the wafer and the mask changes, the extent of the spread of exposure light within the resist due to diffraction phenomena will change, and as a result, the reproducibility of the shape and line width of the resist after development will no longer be obtained.
Furthermore, a problem may arise in that a desired resolution cannot be obtained. In addition, in the worst case, it is several μm to several tens of μm.
In some cases, the wafer and the mask, which were kept at a distance of Therefore, an object of the present invention is to provide a resist pattern forming method that eliminates charging of the resist layer during pattern formation, maintains a constant distance between the wafer and the X-ray mask, and forms a pattern with excellent resolution.

0004

[Means for Solving the Problems] The above object is achieved by the following present invention. That is, the present invention provides a resist pattern forming method using a radiation proximity exposure method, which includes:
By treating the surface layer of the radiation-sensitive resist layer with a cationic or amphoteric surfactant to make it conductive, the resist layer is prevented from being charged due to ionization during radiation exposure, and the distance between the mask and the wafer, which are placed in close proximity, can be reduced. This is a resist pattern forming method characterized by preventing.

[0005]

[Function] By treating the surface layer of the radiation-sensitive resist with a cationic or amphoteric surfactant, it is possible to prevent the resist from being charged. It is possible to prevent variations in the mask distance.

[0006]

[Preferred Embodiment] When the purpose of exposure is to manufacture semiconductor devices, cationic surfactants that can be used in the method of the present invention include, for example, tetradecylamine acetate, octadecylamine acetate, quaternary Compounds that do not contain an alkali metal element, such as quaternary ammonium chloride, quaternary ammonium sulfate, and quaternary ammonium nitrate, can be used. In addition, if the purpose of exposure is not a semiconductor device such as micromechanics,
For example, dodecyltrimethylammonium chloride,
Coconut alkyltrimethylammonium chloride, octadecyltrimethylammonium chloride, tetradecyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride, tetramethylammonium chloride, etc. can also be used. When performing surface treatment on the surface layer of a resist, it is desirable to dissolve these cationic or amphoteric surfactants in an appropriate solvent, form a film by spin coating, and then dry by heat treatment. The solvent used for spin coating is
Ion-exchanged water or alcohols such as methanol, ethanol, n-propanol, isopropyl alcohol, etc. can be used depending on the material.

[0007] The other components used in the method of the present invention, such as the wafer, resist, X-ray mask, exposure method, and development method, may all be conventionally known components and are not particularly limited. As illustrated in FIG. 1, in the case of the conventional technique in which the surface layer of the resist is not subjected to antistatic treatment, the resist layer becomes electrically charged during close exposure, resulting in an X-ray transparent film having an X-ray absorber pattern. As a result, the resolution of the pattern formed on the resist layer decreases, and in extreme cases, the mask and resist layer come into close contact. On the other hand, in the case of the method of the present invention, the resist layer is not charged during pattern formation, and therefore the distance between the resist layer and the X-ray mask does not change, so a pattern with excellent resolution stability can be formed. be able to.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples. It goes without saying that the present invention is not limited to the following embodiments.

Example 1 Methyl sulfate of dimethyldihydroxyethylammonium as an antistatic agent was dissolved in ion-exchanged water and filtered through a 0.2 μm Teflon membrane filter to prepare an antistatic agent solution for spin coating. 1μ negative resist SAL-601 resist manufactured by Shipley
The film was coated onto a silicon wafer with a spinner to a thickness of m, and then prebaked on a hot plate at 105°C for 1 minute. The above ion-exchanged aqueous solution of the antistatic agent was spin-coated onto this using a spinner, and the resultant was further dried by heating at 105° C. for 1 minute. Next, this wafer and an X-ray mask were fixed facing each other at a distance of 10 μm, and after X-ray exposure was performed using a Rh X-ray tube, post-exposure baking was performed at 110° C. for 1 minute. Development was carried out by immersion in Shipley's MF-312 for 10 minutes. When the cross-sectional shape of the obtained resist pattern was observed using a SEM, there was no deterioration in the pattern shape, and the reproducibility of the line width of the resist was also good. Further, no contact between the mask and the wafer occurred.

Example 2 Trimethylacetoxymethylammonium as an antistatic agent was dissolved in ion-exchanged water and filtered through a 0.2 μm Teflon membrane filter to prepare an antistatic agent solution for spin coating. After applying a positive resist RAY-PF resist manufactured by Hoechst to a thickness of 1 μm onto a silicon wafer using a spinner,
Prebaked at 10°C for 1 minute. The above ion-exchanged aqueous solution of the antistatic agent was spin-coated onto this using a spinner, and the resultant was further dried by heating at 110° C. for 1 minute. Next, this wafer and an X-ray mask were fixed facing each other at a distance of 10 μm, and after X-ray exposure was performed using a Rh X-ray tube, post-exposure baking was performed at 120° C. for 1 minute. Developed using Hoechst AZ developer (diluted 3 times with ion-exchanged water)
It was immersed in water for 2 minutes. When the cross-sectional shape of the obtained resist pattern was observed using a SEM, there was no deterioration in the pattern shape, and the reproducibility of the line width of the resist was also good. Further, no contact between the mask and the wafer occurred.

Comparative Example A resist pattern was prepared in the same manner as in Example 1, except that the resist surface layer was not treated with an antistatic agent as described in Example 1, and the line width of the resist was evaluated using a length measurement SEM. When tested, the reproducibility of the line width of the resist was found to be poor.

[0011]

[Effect] According to the present invention as described above, by treating the surface layer of a radiation-sensitive resist with a cationic or amphoteric surfactant, the resist is prevented from being charged, and by preventing this charging, it is possible to prevent the resist from becoming electrically charged. Fluctuations in the distance between the wafer and the mask due to repulsive force or attractive force can be prevented.

0012

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating close exposure when no antistatic treatment is performed on the resist surface layer.

FIG. 2 is a diagram illustrating proximity exposure when antistatic treatment is performed on the resist surface layer.

[Explanation of symbols]

1: X-ray mask 2: Resist layer 3: Wafer

Claims (1)

[Claims] Claim 1: In a resist pattern forming method using a radiation proximity exposure method, the surface layer of a radiation-sensitive resist layer is treated with a cationic or amphoteric surfactant to make the resist layer conductive, thereby reducing the resistance of the resist layer due to ionization during radiation exposure. A method for forming a resist pattern, which is characterized by preventing charging and preventing variations in the distance between a mask and a wafer that are placed in close proximity.