JPS5819127B2 - Fine pattern formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming a fine negative resist pattern in phosphorography using electron beam or X-ray exposure.

Phosphorography technology using electron beams or X-rays is being put into practical use as a way to overcome the limitations of pattern miniaturization by conventional photolithography, but the resist used in this process is exclusively positive. ing.

The reason for this is that currently available positive resists for electron beam or X-ray exposure have a sensitivity that is one to two orders of magnitude lower than negative resists, but have much higher resolution.

Particularly, when a negative resist is used in electron beam direct exposure, that is, in a method of direct writing by deflecting an electron beam, there is a drawback that formation of a fine pattern becomes more difficult due to the uneven residual film rate characteristic.

In other words, as shown in Figure 1, negative resists have a more gentle residual film rate characteristic than positive resists, so when drawing is done with an electron beam with a broadened intensity distribution, it is difficult to obtain a constant line width. becomes difficult.

For this reason, it has been considered to use a positive resist for electron beam or X-ray exposure.

However, in the manufacture of semiconductor devices and the like, it is often desired to use a negative resist.

For example, one of the problems with the above-mentioned electron beam direct exposure method is that it takes a long time to draw, but depending on the pattern, the area of the part to be irradiated with the electron beam is significantly thicker than the part that does not need irradiation, and While the increase in time is a serious problem, this problem is alleviated if both positive and negative resists can be used.

Therefore, an object of the present invention is to provide a method for forming a fine negative resist pattern in a resist pattern forming method using electron beam or X-ray exposure.

In the fine pattern forming method of the present invention, a negative resist layer, a metal film, and a positive resist layer are sequentially deposited on a substrate, and the positive resist layer is exposed to a predetermined pattern of electron beams or X-rays.
The metal film portion is selectively etched away using the developed positive resist layer as a mask, and then the negative resist layer is exposed to electron beams or X-rays using the vaginal metal film as a mask. The method is characterized in that a negative resist layer of a predetermined pattern is formed by irradiating the negative resist layer with irradiation and then developing the negative resist layer, and this will be explained in detail below.

FIGS. 2a and 2d are diagrams showing a pattern forming method according to an embodiment of the present invention, showing five steps of forming a pattern of a negative resist layer on a 5i02 film 2 formed on the surface of a Si substrate 1. FIG.

゛First, as shown in Fig. 2a, a negative resist layer 3 is coated on the Si substrate 1 on which the 5i02 film is formed, and then a metal film 4 is formed by vapor deposition, sputtering, etc., and then a positive resist layer is formed. 5 is applied and formed.

The negative resist layer 3 is formed by diluting known DAP (diallyl orthophthalate) with an organic solvent and spin-coding the diluted material, for example.

Since the metal film 4 serves as a mask for electron beams or X-rays, it is made of, for example, Au, W, MO, etc. and has a thickness of 2000 mm.
The film is ~3000 feet long.

Further, the positive resist layer 5 is made of, for example, PMMA (polymethyl methacrylate).

When the positive resist layer 5 is irradiated with an electron beam in a predetermined pattern and the positive resist layer 5 is developed, only the area irradiated with the electron beam is removed as shown in Figure 2. A pattern of the positive resist layer 5 is formed.

The positive resist layer 5 may be exposed to X-rays using a mask.

At this time, since the negative resist layer 3 is covered with the metal film 4, it is not exposed to the electron beam or Xi.

Next, after etching the metal film 4 by ion etching or the like using the positive resist layer 5 as a mask, as shown in FIG. Only the negative resist layer 3 to be exposed is exposed.

The positive resist layer 5 may be removed before the exposure step.

To irradiate the entire surface with the electron beam, if the diameter of the electron beam is increased, there is no need to scan the entire surface, and as with the X-ray field, no special operation is required, and the negative resist layer 3 has high sensitivity. Therefore, exposure does not require a long time.

At this time, the exposure area of the negative resist layer 3 is defined by the pattern of the metal film 4 that is in close contact with it, so even if it has a gentle residual film rate characteristic, it is similar to the case of direct electron beam exposure. There is no pattern blurring.

After that, when the negative resist layer 3 is developed, the negative resist layer 3 in the non-exposed area under the metal film 4 is dissolved and removed, and the metal film 4 and the positive resist skin 5j4 thereon are simultaneously removed. (lift-off), and a predetermined pattern of negative resist layer 3 remains as shown in FIG. 2d.

Incidentally, the positive resist layer 5 and the metal film 4 may be removed prior to the development step of the negative resist layer 3.

As is clear from the above embodiments, according to the present invention, a fine pattern of a negative resist layer can be created without using particularly complicated processes, and in particular, even in a method of direct writing with an electron beam. It has the advantage that a fine negative pattern equivalent to a positive resist pattern can be easily formed.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the residual film rate characteristics of a resist for electron beam or X-ray exposure, and FIG. 2 a = d is a diagram showing a pattern forming process in an embodiment of the present invention. In the drawing, 1 is an 81 substrate, 2 is a 5i02 film, 3 is a negative resist layer, 4 is a metal film, and 5 is a positive resist layer.

Claims (1)

[Claims] 1. A negative resist layer, a metal film, and a positive resist layer are sequentially deposited on a substrate, the positive resist layer is irradiated with an electron beam or X-rays in a predetermined pattern, and then developed. The metal film is selectively etched away using the mold resist layer as a mask, and then the negative resist layer is exposed to an electron beam or X using the vaginal metal film as a mask.
1. A method for forming a fine pattern, which comprises irradiating a line and then developing the negative resist layer to form a negative resist layer with a predetermined pattern.