JPS5898924A - Minute pattern forming method - Google Patents

Abstract

PURPOSE:To prevent the degradation of the contour of the pattern due to the phenomena such as diffraction and scattering of light and reflection of light at the interface between a photoresist and a substrate, by stopping exposure and development at a leyr in the photoresist film having a specified depth, and performing dry etching at the part deeper than said layer. CONSTITUTION:The semiconductor substrate 1 is coated by a pattern forming film 2, and the positive type photoresist 3 is applied by a spinner method. By using the photomask, the exposure and development are performed. At this time, the exposing time is made 1/2-1/3 the conventional time, and the thickness is made about 1.0mum from the surface of the resist. Then, the photoresist is dissolved by the developing liquid and a removed parts 5 are formed. Resists 6 directly beneath the parts are made to remain by 0.5-1.5mum. The resists 6 are etched away to the interface of the coating fim 2. With the remaining resist 3 as a mask, the ground coating film 2 is etched by an anisotropic etching device. Then, the resist mask 3, used as the etching mask, is removed.

Description

[Detailed description of the invention] The present invention relates to a method for forming fine patterns.

In recent years, there has been a strong demand for high density and low power consumption for semiconductor devices. For this reason, the dimensions of semiconductor elements (the dimensions of each element component) are trending toward miniaturization. For such micro-dimensional processing, conventional photolithography methods using ultraviolet light exposure and quesothoetching methods are difficult, and exposure methods using electron beams and X-rays and dry etching methods have come to be used. There is. However, electron beam exposure and X-ray exposure require limited equipment power;
Because of the disadvantages of being expensive and requiring complicated and time-consuming processes, it has not always been sufficient for processing dimensions of 1 to 2 microns or more.

The present invention has been made for the purpose of further reducing the limit of the dimension of turn formation by the conventional light exposure method.

There are many types of photosensitive films (hereinafter collectively referred to as photoresists) used for forming fine patterns on the market, both positive and negative types.The advantage of positive photoresists is that the exposed areas There is no bridging or swelling caused by polymerization or cross-linking reactions, as is seen in the exposure and development of negative-type rubber thread photoresists. For this reason, positive photoresists are generally used to form fine turns.

However, even in the case of positive-type photoresists, in the conventional light exposure method, a sufficient amount of exposure is performed over the thickness of the photoresist film when forming a latent optical image of ζ-line in the photoresist film.

In such exposure, deterioration of the pattern contour cannot be completely avoided due to phenomena such as diffraction and scattering of light in the photoresist film and reflection of light at the interface between the photoresist and the substrate.

The present invention is a novel photoresist fine pattern forming method that adds dry etching to conventional exposure and development. More specifically, the method involves limiting exposure and development to a predetermined depth layer of the photoresist film, and then dry etching the remaining layers. It is.

Embodiments of the present invention will be described below with reference to the drawings.

Reference numeral 1 in FIG. 1 is, for example, a semiconductor substrate or a glass substrate for a photomask. In this embodiment, a semiconductor silicon substrate 10
0flLfllφ was used. On top of that, pattern forming film 2 (8102, M!, chromium, polysilicon,
It is covered with a film such as a nitride film used in normal semiconductor devices or the manufacturing process of such devices. Note that 5102 was used in this example. Further, a positive type photoresist 3 is applied to a thickness of 1.6 to 2.6 microns by a well-known strip/line coating method.

Next, expose using a photomask as shown in Figure 2.

Perform development. In the exposure and development processing steps at this time, the film is not completely developed up to the film interface 4 and no image is formed.
The exposure time is set to the conventional range, and about 1.0 micron below the surface of the resist is exposed. Next, in the same time as conventional methods, the photoresist is dissolved using a developer as shown in FIG.
．． Leave about 6 microns. Note that the resist film thickness is 1.0
A diameter of micron or more is desirable.

Next, as shown in FIG. 3, using a substrate bias plasma etching apparatus, the resist 6 directly below the above-mentioned resist 6 is etched to the interface of the coating 2 and removed.

At this time, the side walls of the resist opening 7 are formed to be substantially vertical.

Next, using the remaining resist 3 as a mask, as shown in FIG. 4, the base film 2 is etched using an anisotropic dry etching apparatus using a gas with good selectivity between the resist and the base film.

FIG. 6 shows a state in which the photoresist used as an etching mask during etching of the base film 2 has been removed.

In the method of the present invention described above, since the photosensitive area of the photoresist film is limited to the surface layer, light scattering occurs.

Since diffraction or reflection is prevented as much as possible, the fidelity and contrast of the optical image are improved. Furthermore, if the photoresist and then the film are etched using a dry etching device, it is possible to easily form a fine pattern of the conventional circular to precise size. It goes without saying that the method of the present invention can be used not only for visible light exposure, but also for electron beam exposure, etc. However, if the method of the present invention is used for ultraviolet exposure, it will not require expensive equipment. It is possible to form a fine pattern of 2 microns or less without using the method, and it can be applied to photomasks and d manufacturing processes for manufacturing semiconductor devices with high density, high degree of integration, or low dissipation power, and can exhibit great effects.

[Brief explanation of the drawing]

1 to 6 are cross-sectional views showing the manufacturing process of an embodiment of the present invention. 1...Semiconductor substrate, 2...Semiconductor film, 3...Positive photoresist, 4...
Film interface. Name of agent: Patent attorney Ken Nakao and 1 other person 1st
Figure 131! ! □ Figure 4 Figure 5

Claims (1)

[Claims] a step of applying a photoresist film to a predetermined thickness on a predetermined film provided on a substrate surface; a step of exposing and developing a portion of the photoresist film from the surface of the photoresist film to a thickness below the predetermined thickness to form a pattern; A method for forming a fine pattern, comprising the step of etching the photoresist film using anisotropic dry etching.