JPS6043824A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable to form the prescribed pattern on an organic resist film by performing an etching by a method wherein an organic substance thin film formed on the surface of a substrate is removed by irradiating ultraviolet rays to said thin film in the atmosphere wherein an oxidizing active seed is generated. CONSTITUTION:After a semiconductor substrate 5 whereon resist is coated has been provided in a housing vessel 1, oxygen of one atmospheric air pressure containing saturated steam, for example, is introduced from a gas introducing hole 2 as atmospheric gas which generates an oxidizing active seed. When the pattern located on a mask 6 to be used for exposure is projected on the semiconductor substrate 5 using an ultraviolet ray emitting source 71, the steam of atmospheric gas and oxygen is dissociated at the ultraviolet ray irradiated part of the substrate 5, and the radical of oxygen atoms is generated. O-radical reacts to an organic resist film, and a volatile low molecular organic compound is also decomposed. As a result, the under layer semiconductor substrate 5 is exposed.

Description

DETAILED DESCRIPTION OF THE INVENTION (a1) Technical Field of the Invention The present invention relates to patterning in the manufacture of semiconductor devices, particularly to a method for developing an organic resist film.

(Background of BL technology) Due to the demand for microfabrication as semiconductor devices become more highly integrated, dry etching is gradually becoming the main etching method used in their manufacturing. It is being done.

When an organic polymer film is used as a mask for etching using the dry method, the development of the mask, that is, the etching may also be performed using the dry method. This is similar to the etching of the diffusion mask layer, etc., and the dry method does not have the problem of swelling unlike the wet method, and is also more effective than the wet method.

This is because it is suitable for forming fine patterns because it has few defects.

(C) Prior art and problems An example of a conventional dry method for developing an organic resist I-mask is as follows.
A resist film containing vinyl carbazole is applied over the entire surface of a semiconductor substrate, and high-energy radiation is irradiated onto the resist film in a predetermined pattern.

As a result, in the irradiated portion of the resist film, the polymer undergoes crosslinking with N-vinylcarbazole, increasing its molecular weight. Thereafter, the N-vinylcarbazole remaining in the unirradiated areas is removed by heating in a vacuum, and the entire surface of the organic resist film is irradiated with gas plasma to perform etching (development). There is a difference in etching speed between the unirradiated areas and a pattern is formed.

As described above, an organic resist mask with openings in a predetermined pattern is formed, but plasma etching equipment is generally large and complex, and requires complex processes such as electron beam irradiation or gas plasma processing. Because of the use of physical or chemical reactions, there are drawbacks such as insufficient reproducibility and complicated process management.Furthermore, irradiation with high-energy rays damages the base substrate coated with resist. had the disadvantage of inducing damage.

(d1 Purpose of the Invention) The present invention provides an efficient method for etching an organic resist using a relatively simple device, without causing 1n scratches on the underlying substrate, and without causing delamination in non-etched areas. It is an object of the present invention to provide an easy-to-use method for etching a film into a predetermined pattern.

(Ei) Structure of the Invention The present invention provides an organic thin film formed on the surface of a semiconductor substrate.
It is characterized in that it is processed into a predetermined number of turns by irradiating and removing ultraviolet rays in an atmosphere that generates oxidizing active species, and the atmosphere that generates oxidizing active species contains oxygen, carbon oxide, carbon dioxide, It is characterized by containing one or more of nitrous oxide, nitrogen oxide, nitrogen dioxide, and water vapor.

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

The figure shows the general configuration of the device used in the present invention,
The container 1 is provided with a gas inlet 2, a gas inlet 3, and a window 4 made of fused silica or calcium fluoride that transmits ultraviolet rays, and an organic resist film is coated directly under the window 4. A semiconductor substrate 5 is arranged. On the other hand, a projection optical system 7 is installed directly above the window 4 to project the pattern of the exposure mask 6 onto the semiconductor substrate 5. The projection optical system 7 includes an ultraviolet light source 71 such as a mercury lamp, a mercury-xenon lamp, a deuterium lamp, an excimer laser, etc.
A parabolic mirror 72 for reflecting and condensing the output light of the ultraviolet light source 71, a converging lens 73, an aperture 4 provided for producing high-quality parallel light, and a projection lens 75. The interior of the projection optical system 7 is as follows:
For example, it is desirable to fill it with a gas such as nitrogen gas that has low absorption of light with a wavelength in the range of 180 nm to 300 nm.

In the above configuration, for example, 01'lR resist (manufactured by Tokyo Ohka) is coated in the container 1 to a thickness of 6000 mm.
After a semiconductor substrate 5 made of silicon or the like is placed, for example, oxygen at 1 atm containing saturated water vapor is introduced from the gas introduction hole 2 as an atmospheric gas that generates oxidizing active species. Further, the temperature of the semiconductor substrate 5 is maintained at about 120° C. by the heater 8.

Here, when the pattern on the exposure mask G is projected onto the semiconductor substrate 5 using, for example, a high-pressure mercury lamp (I KW) as the ultraviolet light emission source 71, the portion of the semiconductor substrate 5 that is irradiated with ultraviolet light is exposed to atmospheric gas. Water vapor (H2O) and oxygen (02) dissociate 1 to produce active species (radicals) of oxygen atoms (0). The O radicals react with the organic resist film on the surface of the semiconductor substrate 5 in the ultraviolet irradiated portion, and decompose the organic resist film into volatile low-molecular organic compounds. As a result, the organic resist film I7 in this portion is reduced, and the underlying semiconductor substrate 5 is finally exposed. Normally, the above OMI? Resist patterning is completed.

In the above, is it okay to use only oxygen as the atmospheric gas that generates the oxidizing active species?The advantage of using water vapor as described above is that the dissociation energy required to generate the O radicals is approximately 4.8 eV (wavelength Approximately 2580
), and the M F11t energy of oxygen is approximately 5.1e
V (approximately 2430 people in terms of wavelength) and z9 is also small,
Also, the absorption of ultraviolet light by 2,400 to 2,600 people is about one order of magnitude higher than that of oxygen. For this reason, the generation efficiency of 0 radicals is high, making it possible to shorten the etching time and reduce the output of the ultraviolet light emitting source.As a result, the organic resist film on the semiconductor device with the MO3 structure, which is sensitive to radiation irradiation, can be etched. In this case, the loss caused to the oxide film or the oxide film-silicon interface on the semiconductor device is small, and the resulting drop in breakdown voltage can be avoided, and the yield can be improved.

In the method of the present invention, since no oxidizing active species are generated in areas other than the areas exposed to ultraviolet rays, the organic resist film does not shrink at all in those areas. Zunawaji,
The gamma value of the organic resist can be ignored as 1, making it possible to process high aspect ratios. In addition, in the method of the present invention, it is possible to perform etching with a relatively high atmospheric gas pressure (for example, 1 atm), which not only increases the etching rate but also reduces the average of 0 radicals. The free path becomes smaller, and the spatial resolution of etching becomes larger (side etching becomes smaller).
This means that it is suitable for processing fine patterns.

Furthermore, the method of the present invention has the following great advantages in industrial applications. In other words, (1) pattern accuracy is determined only by the irradiation optical system and gas pressure, and the reproducibility is improved because there are fewer control parameters, and the temperature of the substrate to be processed can be controlled only by the heater. High-speed processing is possible without deterioration of pattern accuracy due to excessive heating. ■Since the decomposition reaction of the organic resist proceeds only in the ultraviolet irradiated area, there is little contamination from the side walls of the reaction container. (2) Since no electric discharge phenomenon or electron beam irradiation is used in etching processing, the processing equipment system is simple and inexpensive, and maintenance is also easy.

(g1) Effects of the Invention According to the present invention, it is possible to efficiently and accurately etch an organic resist film into a predetermined pattern using a dry method using relatively simple equipment, and to produce semiconductor devices of il'4i quality with high quality. This has the effect of making it possible to manufacture with low yield.

[Brief explanation of drawings]

The drawing is a diagram schematically showing the configuration of an exposure and etching apparatus used for manufacturing a semiconductor device according to the present invention. In the figure, ■ is a container, 2 is a gas inlet, 3 is an exhaust port,
4 is a window, 5 is a semiconductor substrate, 6 is an exposure mask, 7 is a projection optical system, 8 is a heater, 71 is an ultraviolet light source', 72 is a parabolic mirror, 73 is a converging lens, 74 is an aperture, and 75 is a It is a projection lens. -已- r w

Claims (3)

[Claims] (1) Feature 3 is that the organic thin film formed on the surface of the semiconductor substrate is processed into a predetermined pattern by directly irradiating the organic thin film with ultraviolet rays and removing it in an atmosphere that generates oxidizing active species. A method for manufacturing a semiconductor device. (2) The method for manufacturing a semiconductor device according to claim 1, wherein the atmosphere that generates oxidizing active species contains water vapor. (3) Claim 2, characterized in that the atmosphere that generates oxidizing active species contains one or more of oxygen, carbon oxide, carbon dioxide, nitrous oxide, nitrogen oxide, and nitrogen dioxide. A method for manufacturing a semiconductor device according to section 1.