JPH02106919A - Manufacture of semiconductor device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of patterning a resist on a semiconductor substrate using a photomask.

(Prior art) Recently, when performing submicron-order patterning in a photolithography process, a stepper is used to form a pattern, a gate electrode and a butt electrode are formed on a semiconductor substrate, and then a portion of the stepper is removed. A lift-off method is used. For fine pattern formation using this method, it is essential that the stepper have an inverted tapered shape.

Currently, attempts are being made to form a reverse taper using a positive photoresist. When using a normal positive type photoresist, as shown in Figure 2, the positive type photoresist (3) is coated on the semiconductor substrate (1), and after baking, as shown in the figure (:). Then, exposure is performed using a photomask (4) to form an exposed portion having a reverse tapered shape as shown in FIG. 4(i). Then, heat treatment is performed at a temperature of 90 to 100 degrees Celsius to make the exposed area insoluble in an alkaline developer, and the entire photoresist (3) is exposed to light as shown in FIG. 2(i). Thereafter, development and post-baking are performed to obtain a pattern of the resist (5) having an inverted tapered shape as shown in FIG.

(Problem to be Solved by the Invention) However, as can be seen from Figure Therefore, the angle of the reverse tapered shape of the photoresist is also 8.
The drawback was that it could only be applied at an angle of about 0 to 85 degrees.

For this reason, when exposing a photoresist to form an inverted tapered shape, conditions regarding the exposure amount are strict, making it difficult to easily form an inverted taper and making handling troublesome.

Furthermore, since the angle of the inversely tapered shape is about 80 to 85 degrees, it is difficult for the metal to break when metal is deposited onto the resist side wall.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device that has a large exposure margin and can extremely easily obtain a resist pattern having an inverted tapered shape.

[Structure of the Invention] (Means for solving the problem) When forming a reverse taper pattern of photoresist on a semiconductor substrate, a photoresist with a dye added thereto is applied, and the photoresist is Exposure is performed using a large amount of light and the angle of the reverse taper is controlled.

(Function) Generally, when a photoresist is exposed to light, diazonaphthoquinone in the resist becomes indenecarboxylic acid due to the exposure, and a decarboxylation reaction occurs during subsequent heat treatment.
Becomes insoluble in alkaline developer. If the exposure amount is small, only the upper part of the resist will be exposed and a decarboxylation reaction will occur, and most of the lower part will remain the original photoresist, so when alkaline development is performed, most of it will be scraped off and the pattern will collapse. Sometimes. Furthermore, if the amount of exposure is large, the exposure will occur without forming a taper.

In the case of the present invention, the progress of exposure in the photoresist is slow due to the light absorption effect of the dye in the dye-containing photoresist, so the resist takes on a reverse tapered shape only when exposed to a large amount of light. Unless you increase the amount very much, you will not be able to taper. Therefore, a reverse taper can be formed much more easily than with a normal photoresist, and the exposure margin can be increased. Even if the photoresist film thickness changes, the taper shape can be controlled by adjusting the exposure amount, and the angle of the reverse taper shape can be changed by adjusting the amount of dye in the resist. , it is possible to provide a method for manufacturing a semiconductor device that is extremely easy to handle.

(Embodiment) FIG. 1 shows a method for manufacturing a semiconductor device showing an embodiment of the present invention. The present invention will be described in detail below with reference to FIGS. 1) to iv).

First, as shown in Figure 1), a positive photoresist (2) containing a dye is coated on a semiconductor substrate (1) with a thickness of 1 μm to 3 μm.
After applying the film to a thickness of approximately 1.0 m, heat treatment (pre-baking) at a temperature of around 100°C in a dry atmosphere, and exposing it to light using a photomask 5 (4). (Also) changes into a reverse tapered shape. Since the dye in resist (2) has a light absorption effect, the exposure amount was increased to 3305
It is preferable to do this for sec or more. After that, by heat treatment at 90°C to 100°C in an ammonia gas atmosphere,
The exposed area was made insoluble in the alkaline developer and
The entire resist (2) is exposed as shown in i). Then, as shown in FIG. 4(iv), the resist is developed with an alkaline developer such as ammonium fluoride, and heat treated (bost baking) at around 100° C. to form an inverted tapered photoresist (5). Furthermore, FIG. 3 shows whether or not a reverse taper can be formed in a resist film thickness range of 1.1 to 2.4 μm. As is clear from the figure, the exposure margin, which is the range of exposure amount that can form a reverse taper, is 230 m5ec or more when the resist film thickness is 1.76 μm. As shown in Figure 3, when using a normal positive photoresist, the exposure merge that forms a reverse taper is 60 mm when the resist film thickness is 1.75 μm.
Since it is m5ec, a reverse taper can be formed very easily by using the photoresist (2) containing dye.

Furthermore, regarding the angle (7) of the inverted tapered shape of the resist shown in FIG.
Although the angle is approximately 85 degrees, if a dye-containing positive photoresist is used, the angle can be reduced to 80 degrees or less, and metal step breakage due to metal twisting on the side wall of the resist can be reliably caused. By varying the amount of dye in the photoresist (2), the taper angle (7) of the resist can be controlled. For example, the taper angle (7) can be set in the range of 65 degrees to 75 degrees for a dye containing 2.5%, and can be set in a range of 70 degrees to 80 degrees for a dye containing 1.25%.

[Effects of the Invention] As detailed above, when forming a reverse taper pattern of photoresist on a semiconductor substrate using a mask, by using a photoresist with dye added thereto, The exposure margin is large and a reverse tapered resist pattern can be obtained very easily.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing the manufacturing process of a semiconductor device according to an embodiment of the present invention, FIG. 2 is a partial cross-sectional view showing the manufacturing process of a conventional semiconductor device, and FIG. 3 is a partial cross-sectional view showing the manufacturing process of a semiconductor device according to the present invention. Diagram 4 showing whether or not reverse taper formation is possible depending on the manufacturing method of the device.
The figure shows whether a reverse taper can be formed by a conventional method for manufacturing a semiconductor device. DESCRIPTION OF SYMBOLS 1...Semiconductor substrate, 2...Dye positive photoresist, 3...Positive photoresist, 4...Mask, 5...Exposed part of resist, 6...Unresist Exposure area, 7... Taper angle (1i1 (11)) (4V ((V) Figure 2)

Claims (1)

[Claims] A step of applying a photoresist containing paint on a semiconductor substrate, a step of exposing the photoresist to form a first exposed portion in a reverse tapered shape with respect to the substrate, and heat-treating the entire photoresist. making the first exposed area insoluble in an alkaline developer;
a step of exposing the photoresist to form a second exposed portion around the first exposed portion; and removing the second exposed portion by etching to leave the first exposed portion having an inversely tapered shape. A method for manufacturing a semiconductor device, comprising the steps of: