JPS63220140A - Pattern forming method - Google Patents

Abstract

PURPOSE:To permit sufficient exhibition of the performance of an exposing device having a shallow depth of focus by adhering a material which absorbs a 2nd energy beam to the exposed part on the surface of a thin org. film and exposing the entire surface of the thin org. film with the 2nd energy beam. CONSTITUTION:Only the part near the surface of, for example, a positive resist 2 is used for the primary energy beam exposing and is selectively exposed by deep UV light 3, by which only the part near the surface of the resist 2 is modified. The modified part is then selectively dyed by a chemical material, for example, dye or the like which absorbs the light 4 of the secondary energy beam exposing. The entire surface is in succession thereof exposed by the light 4 having good transmittance through the resist, for example, UV light, as the secondary energy beam and the positive resist 2 except only the dyed part is developed and removed. The sufficiently high resolution is thereby obtd. when this method is applied to the exposing device of the shallow depth of focus, for example, device such as excimer stepper.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to photorinography technology used in semiconductor device manufacturing and the like. More specifically, the invention relates to resist pattern formation in photolithography.

BACKGROUND OF THE INVENTION In recent years, with the development of semiconductor device manufacturing technology, there has been a demand for photolithography technology for processing on the order of 0.5 microns.

In terms of equipment, technologies to break through the 0.5 μm order include shortening the wavelength of conventional steppers, increasing NA, excimer laser steppers, X-ray steppers, and direct seeding electron beam exposure devices.

However, the problem that the invention sought to solve was the high HA (numerical aperture of the lens) of conventional steppers.
Excimer steppers are currently considered to be the most promising because there are limits to how much light can be used and wavelengths can be shortened, mask mounting is difficult with X-ray steppers, and throughput is low with electron beam exposure. However, even excimer steppers are not without problems. In other words, the following Rayleigh equation 0 formula % λ: Exposure wavelength, NA: Numerical aperture of lens If you want to improve the resolution at the same wavelength, you must increase the NA, but if you increase the NA, it is shown in 2〇 The disadvantage is that the depth of focus (F, D) becomes shallow.

On the other hand, many methods have been proposed and tried in resist process technology. For example, multilayer resist (MLR)
) method 1 reflective coating (ABC) method, contrast enhancement (CEL) method, portable conformal (
There are the PCM) method, the Image Repersal (IR) method, etc.

Although both methods have the effect of covering depth of focus deterioration in photoprocessing, they have problems such as complicated processes and small depth of focus expansion effects, and are not very practical.

That is, the conventional resist process technology cannot sufficiently cope with the deterioration in depth of focus caused by shorter wavelengths and higher NA in excimer steppers.

The present invention relates to pattern formation such as a photoresist process developed in view of the drawbacks of conventional resist processes as described above, and is a resist process technology that can fully utilize the performance of exposure equipment with a shallow depth of focus such as an excimer stepper. This is what we tried to provide.

Means for Solving the Problems The pattern forming method of the present invention includes the steps of: coating an arbitrary substrate with an organic thin film whose chemical properties change in response to a first energy beam; selectively exposing the vicinity to the first energy beam; attaching a substance that selectively absorbs the second energy beam to the exposed portion of the surface of the organic thin film; and the second energy beam. exposing the entire surface of the organic thin film to light;
The exposed organic thin film is developed to form a pattern.

For production The resist process of the present invention is MLR, CEL.

This enables a resist process that utilizes only all the good points of PCM, IR method, etc.

That is, the first energy beam exposure uses, for example, only the vicinity of the surface of the positive resist and selectively exposes it to a deep
Exposure is performed with UV light (for example, KrF excimer light; 248 nm) to modify only the vicinity of the surface of the resist. next,
The modified area is then selectively dyed with a chemical substance, such as a dye, that absorbs the light of the second energy beam exposure.

This book is characterized by exposing the entire surface of the resist to a second energy beam that is highly transparent to the resist, such as UV light, and developing and removing the positive resist, leaving only the already dyed parts. If the resist pattern forming method of the invention is used, only a very thin portion near the surface of the positive resist is selectively exposed in the first exposure, so that the ML
This means that the advantages of R have been incorporated. Furthermore, by dyeing the selectively exposed areas, the close masking effect in the CEL process can be achieved.

By selectively forming a light absorption pattern on the resist, the advantages of PCM are also incorporated. Furthermore, by forming a positive resist pattern by exposing the second metal forming surface, the effects of the IR method can also be incorporated.

Therefore, the resist pattern forming method of the present invention (Dye
Image Reversal: Die, Image
The reversal method (DIR method) is highly effective when forming ultra-fine resist patterns, for example, at a level of 0.5 μm or less.

Examples Below, the resist pattern forming method of the present invention (DIR method)
An example will be described using process cross-sectional diagrams.

First, as shown in FIG. 1, an ordinary positive resist 2 (for example, AZ1400°, AZ4000°. A
Z5200 (both Hoechst products)] to 1 to 2 μm
Coat to a thickness of . Next, as the first exposure, dee
PUV light (deep ultraviolet, for example, KrF excimer light) 3 is selectively irradiated for a short time to selectively expose the vicinity of the surface of the positive resist 2 (FIG. 2). At this time, the main polymer of these normally used positive resists 2 is deep.
Since it absorbs most of the UV light, even if the exposure is multiplied to some extent, only the surface layer with a thickness of 0.1 to 0.2 μm is selectively exposed in a pattern, and only the surface is exposed in an extremely thin layer. A pattern 2o is formed. Therefore, in this step, the same effect as when applying thin resists in layers and selectively exposing only the upper resist layer can be obtained in the same way as with multilayer resists.

That is, a high-resolution exposure device with a shallow depth of focus can be used, and a high-resolution, sharp fine pattern 2o with a width of 0.6 μm or less can be obtained.

Next, the surface layer 2 of the selectively exposed positive resist is
0, the photoreaction of formula (2) occurs only with naphthoquinonediazide light as a photosensitive material.

Therefore, only the 1000H groups generated in this first exposure are selectively dyed with ordinary alkaline dyes (for example, red for tsukushin, yellow for auramine, black for black by aniling black, etc.) to create a dyed layer. 3o (Fig. 3). At this time, the red, yellow, and black alkaline dyes must be at least 450%
All light with a wavelength of nm or less is absorbed. Therefore, the second
For the next exposure, if the entire surface is exposed using light 4 having a wavelength longer than the deep UV light described above, for example, 450 nm or less, only the undyed portion 200 of the resist 2 will be selectively exposed (Fig. 4). ). That is, in this step, C
This means that three effects of the EL method, PCM method, and IR method are incorporated at once.

Finally, only the undyed portion 200 is removed by developing with a positive resist developer, and similarly to the IR method, a high resolution resist of about 0.5 μm opposite to the mask pattern is created using a positive resist. Pattern 5 is obtained (Figure 5).

In the above example, an example was shown in which KrF excimer light was used as the light for the first exposure and UV light was used for the second exposure. It is also possible to use light of the same wavelength as the light.

In addition, alkaline dye was used to dye the pattern, but the second
It is clear that the substance is not limited to dyes as long as it absorbs the light of the next exposure light and can be selectively attached to the exposed pattern area.For example, aniline etc. can also be used.
It can be used because it absorbs linear light.

Furthermore, although we have shown an example of selectively dyeing only the exposed areas, conversely, the same effect cannot be obtained by dyeing areas other than the exposed areas, except that the pattern is reversed. it is obvious.

First, the light for the next exposure is not limited to excimer laser light, but also X-rays, electron beams, ion beams, etc., and the light for the second exposure is not limited to q-rays, but also i-rays. rays, visible light, soft X-rays, etc. may be used.

Furthermore, the organic thin film is not limited to a positive type resist, but may be one in which a chemical reaction occurs on the polycarbonate resin with an isothermal energy beam, and a substance that absorbs or does not transmit the second energy beam can be selectively attached. If so, it is available.

In the method of the present invention, only the surface area of the resist is used for the first exposure of the pattern, so the exposure equipment is
Even if the depth of focus becomes shallow due to A and short wavelengths, it is still usable and has the effect of making full use of the device's resolution.

That is, compared to the conventional multilayer resist process (MLR method), only one coating step is required. Furthermore, since resist removal requires only one development, the process is greatly simplified.

Furthermore, since no heat treatment step is required compared to the conventional image reversal process (IR method), the process stability is good.

Furthermore, unlike the contrast enhancement method (CEL method), since there is no photobleaching film on the top surface of the resist, the exposure time can be significantly shortened, sufficient contrast can be obtained, and the coating process can be done only once.

Furthermore, compared to the anti-reflection coating method (ARC method), only the vicinity of the resist surface is exposed, and the pattern exposure light does not reach the bottom of the resist, so there is no reflection from the substrate surface, and pattern resolution can be greatly improved.

Compared to the portable conformal (PCM) method, it is possible to easily form a patterned light-absorbing layer with high contrast on the resist surface without the need for two-layer coating, resulting in effects such as greatly improving the resolution of the resist pattern. Certain Effects of the Invention As described above, the resist pattern forming method of the present invention can be applied to exposure equipment with a shallow depth of focus, such as an excimer stepper, without making any significant improvements compared to conventional resist process technology. It has the advantage of being able to obtain sufficiently high resolution when applied to the device. Therefore, in the future, as the miniaturization of semiconductor devices progresses, it will be very effective in improving photolithography technology.

[Brief explanation of the drawing]

1 to 6 are process cross-sectional views for explaining a resist process according to an embodiment of the present invention.〇1...Substrate, 2...Positive resist, 3... ...First
'th deep UV light, 4... second exposure light,
6...Resist pattern, 30...Dyeing layer. Name of agent: Patent attorney Toshio Nakao and 1 other person
Is

Claims (8)

[Claims] (1) Applying an organic thin film whose chemical properties change in response to the first energy beam on an arbitrary substrate;
selectively exposing the vicinity of the surface of the organic thin film with the first energy beam; attaching a substance that selectively absorbs the second energy beam to the exposed portion of the surface of the organic thin film; A pattern forming method comprising: exposing the entire surface of the organic thin film with a second energy beam; and developing the exposed organic thin film to form a pattern. (2) The pattern forming method according to claim 1, wherein the organic thin film is a positive resist. (3) The pattern forming method according to claim 2, wherein the substance that absorbs the energy beam is a dye. (4) The pattern forming method according to claim 1, wherein the first and second energy beams are ultraviolet rays. (5) The pattern forming method according to claim 1, wherein the wavelength of the first energy beam is shorter than the wavelength of the second energy beam. (6) The pattern forming method according to claim 1, wherein the first energy beam is far ultraviolet excimer light. (7) The pattern forming method according to claim 3, wherein the dye is an alkaline dye. (8) The pattern forming method according to claim 2, wherein the positive resist contains a ▲ group that includes a mathematical formula, a chemical formula, a table, etc.