JPS58123726A - Method of converting resist into ash-like substance - Google Patents

Abstract

PURPOSE:To treat a resist for ashing in non-oxidizing atmosphere, by a method wherein nascent hydrogen or hydrogen atom is used when a resist coated on a substance to be treated is processed for ashing. CONSTITUTION:Chromium film 12 of 1,000Angstrom in thickness is deposited by evaporation on quartz substrate 11, and PMMA resist 13 of 1mum in thickness is deposited thereon. Pattern is drawn using an electron beam drawing apparatus. The specimen is immersed in isoamyl alcohol and a resist 13 is developed thereby pattern is formed. The specimen is disposed in a plasma etching apparatus of parallel plate type and selective etching of the chromium film 12 is performed. The plasma etching apparatus is evacuated, and then H2 gas is introduced therein and the resist 13 is removed.

Description

[Detailed description of the invention] Invention technology public funds The present invention relates to a method for ashing resist.

Technical background of the invention and its problems Conventionally, in the resist removal process in the manufacture of semiconductor devices, a dead ashing method using oxygen plasma has been used. In this method, Ueno is placed in a plasma generation chamber having a circular structure, and the plasma generation chamber is evacuated in advance, and then oxygen is introduced into the chamber. By applying high-frequency power (by coupling) to start a discharge between each electrode, the resist is removed by decomposing the resist into carbon monoxide, carbon dioxide, water, etc. using nine oxygen radicals generated by the discharge.

Since acid lAf Tsuzuma can remove resist easily and quickly, the above method has recently been used not only for ashing but also for mask transfer technology having a three-layer structure. Jin's technique is a method for preventing a one-turn dimension difference caused by a difference in resist film thickness between the top and bottom parts seen in a stepped part, and is particularly effective in forming/forming a fine aluminum wiring pattern. In the three-layer structure mask transfer technology, first a 5tO2 film 2 is deposited on a St substrate 1 as shown in Figure 1.
A step is prepared in advance, and a Mut-81 alloy film 3 is placed on top of this step.
Deposit. At this time, irregularities exist on the surface of the Muj-81 alloy film 3 along the 810 and the difference in the film 2. Then, for the purpose of planarization, an organic material film 4 is spin-coated on the Mut-St alloy film s to a thickness of 2 to 3 μm. Next, a mask material 5 is deposited on the organic material film 4 to act as a mask when cutting and cutting the mosquito M4, and a resin for forming holes and turns is applied onto the mask material 5 (see FIG. 1). As shown in the figure, the mask material 5 is selectively etched using the resist 6 which has been turned through the phosphorography process as a mask, and then the organic material film 4 is selectively etched using oxygen plasma using the mask material 5 and the resist 6 as one mask. .

Etching (ashing) is performed to form an etching mask for the Mut-ah alloy film 3.

As described above, the resist ashing method using oxygen plasma is used not only in the resist removal process after etching and etching, but also in the arm turn formation process. However, in such a method, the following (1)
(2) It had the following drawbacks: (1) Since the lower oxide of chromium is volatile, it cannot be used in the resist removal process during chrome mask manufacturing.

(2) When using the above-mentioned three-layer structure mask transfer technique, when etching the organic material film 4 with oxygen plasma, after etching the Mut-St alloy film 3, the normal one-layer etching process is performed. If etching is done with a resist mask, there will be a lot of residue.

Purpose of the Invention The purpose of the present invention is to ash the resist in a non-oxidizing atmosphere, thereby making it effective in the resist removal process during chromium mask manufacturing and the organic material film etching process in three-layer mask transfer technology. It is an object of the present invention to provide a resist ashing method that can be applied to various applications.

Summary of the Invention Resist is a well-known polymeric material, which has a main skeleton of long □ chains of carbon-carbon bonds and also contains photosensitive groups and the like. The present inventors focused on H2 gas as a means of vaporizing such materials. That is, the present inventors
It has been shown that by exciting the resist with light emitted by H2 plasma and then applying atomic energy, the carbon-carbon skeleton can be cut and the resist can be vaporized as a hydrocarbon gas with a relatively small molecular weight. I found it. Figure 2 shows the ashing rate of /zo-type 7 otoresist (trade name 0FPR-800, manufactured by Tokyo Ohka) against 0□ plasma and H2 plasma, and the curve P in the figure shows the rate of resist exposure to H2f plasma. The curve Q shows the resist film thickness versus the time of exposure to 02 Glazma.

The above resist was deposited to a thickness of 1 film on a Si substrate and heated at 80°C.
Silibake for 10 minutes at 140℃, followed by 10 minutes at 140℃. I did a stobake. Deraz, the condition is 0 2 e
112 both IT@rr) The applied high frequency power is 500
It was set as W. As can be seen from Fig. 2, the resist removal rate of H2 gas plasma is 0, about 1/2 of that of gas plasma.
However, it is clear that the resist can also be removed using an H2 gas glazma.

The present invention focuses on this point and provides a method in which nascent hydrogen or hydrogen atoms are used to ash the resist on the workpiece.

Effects of the Invention According to the present invention, it is possible to ash the resist by using H, 2 gas without using 02 gas. In other words, it is possible to ash the resist in a non-oxidizing atmosphere. When this rounding is applied, for example, to a resist removal process during the manufacture of a chrome mask, the resist can be effectively removed without causing oxidation of the chromium film. Further, even when applied to an organic material film etching process in a three-layer mask transfer technique, the organic material film can be effectively etched without causing oxidation of the layer.

Embodiment of the Invention FIGS. 3(a) to 3(c) are cross-sectional views showing an embodiment in which the present invention is applied to a chrome mask forming process. First, as shown in FIG.
000Xl [thickly evaporated and PMM
A (z-rimethyl methacrylate) resist 13 to 1
After the film was deposited to a thickness of .mu.m, many turns were drawn using an electron beam drawing device at an accelerating voltage of 20 kV and an e-dose of 12 .mu.c/am''.

Thereafter, the above sample was immersed in isoanther alcohol to form a resist 13, and a resist/arm turn was formed.Next, the above sample was placed in a parallel plate plasma etching apparatus, and a c ct4 pressure of 0 was applied. -04 Torr
The chromium film 12 was selectively etched under the condition of an applied high-frequency power of 200 W as shown in FIG. Next, the inside of the plasma etching apparatus was heated to 5×10 To
After evacuation to below rr, H2 gas is introduced and the pressure is reduced to l.
Torr *The resist 13 was removed for 20 minutes under the condition of applied high frequency power of 500 W. However, when the 4th turn of chromium l [12 (7)] was observed under a microscope, it was confirmed that the ROM mask had residual resist, decreased chromium, and lacked momentum as shown in Figure 3 (C). .

FIGS. 4(a) to 4(f) are cross-sectional views showing other embodiments in which the present invention is applied to a wiring pattern forming process.

First, as shown in FIG.
0. A step of 1 μm is made in the film 22, and an At-st alloy film 23 is placed on top of the step as shown in the same figure.
Then, as shown in FIG. 4(c), a digital photoresist 24 (
0FPR-800 (product name, manufactured by Tokyo Ohka Chemical Co., Ltd.) was spin-coated to a thickness of 2 μm, and then a 3000X film thickness was applied on the resist 24.
A molybdenum silicide film 25 and a resist 26 were sequentially deposited.

Next, an arm turn as shown in FIG. 4(d) is formed on the uppermost renost 26 by a lithography process. Using this resist pattern as a mask, the CF410□ mixed gas pressure was set to 0.
4τerr, the molybdenum silicide film 25 is selectively etched with an applied high-frequency power of 300 W, and then the etching is performed as shown in Fig. 4←)
As shown in the figure, the molybdenum silicide film 25 and :::・,
and the resist 26 as a mask. Pressure 0-01 Tor
The resist 24 was selectively etched under conditions of an applied high frequency power of 200 W'.

Next, the sample was placed in a parallel plate type etching apparatus, and the Mut-S1 alloy film 23 was selectively etched under the conditions of a cct7ct2 gas pressure of 0.04 Torr and an applied high frequency power of 200W. Thereafter, as shown in FIG. 4(f), the resist 24 was removed and the AA thus obtained was removed.
The wiring pattern had little residue and good 4-turn accuracy.

It should be noted that the present invention is not limited to the above-mentioned death embodiment, and can be implemented with various modifications without departing from the gist thereof. For example, when removing the resist, 0.
The high frequency power applied during pressure may be determined as appropriate according to the specifications. Furthermore, it goes without saying that the workpiece is not limited to aluminum or chromium.

[Brief explanation of the drawing]

Figure 1 (,) (b) is a cross-sectional view showing the pattern formation process using the three-layer mask transfer technique, and Figure 2 is a 4I diagram showing the ashing rate of resist in O3, II, and f plasmas. 3(a) to 3(e) are cross-sectional views showing an embodiment in which the present invention is applied to a chrome mask forming step,
No. 41 El←) to (f) a Cross-sectional view showing another embodiment in which the present invention is applied to a mother turn forming process using a three-layer structure mask transfer technique. 1]...Quartz substrate, 12 ...Chrome film, 13°24
．． 26...Resist, 21...81 substrate, 22...
・S Kame 0 film, 23...Muz-st alloy film, 25...
Mo17 f Densilicide film. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 3 Figure 4 Fufu

Claims (2)

[Claims] (1) A resist ashing method that uses nascent hydrogen or hydrogen atoms to ash the resist coated on the workpiece. (2) A method for ashing a resist according to claim 1, wherein the workpiece is a resin film or a aluminum film.