JPH098017A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To manufacture a semiconductor device excellent in a yield wherein a polyamide acid resin film whose thickness is uniform up to an outer periphery and which is free from fluctuation after a coater is removed can be formed on a wafer and generation of cracks can be prevented during a wrapping process by the method of the invention. CONSTITUTION: A method for manufacturing a semiconductor device comprises steps of dripping polyamide acid resin liquid 2 at a center of a horizontally placed wafer 1 to have it spin-coated, forming a polyamide acid resin film 2 having a substantially uniform thickness by heating the entire wafer by hot blast blowing 5 or far-infrared-ray heating 7 while the wafer is being rotated, and then forming a polyimide resin film by making the polyamide resin film into imide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device having an excellent yield.

[0002]

2. Description of the Related Art A polyimide resin having excellent heat resistance, electric insulation and flatness of a coating film is used as a surface protection film of a semiconductor element. The protective film forming method is a spin coating device (spin coater). The film forming method used occupies the mainstream. In the conventional method, as shown in FIG. 2 (a), the wafer 11 is suction-attached to a wafer suction fixing head 13 of a spin coater, and a liquid polyamic acid resin 12, which is a polyimide precursor, is placed almost at the center of the wafer 11. , The wafer suction fixing head 13 is rotated at a rotation speed within a practical range. The liquid polyamic acid resin 12 is spread evenly on the wafer 11 from the center of rotation toward the outer periphery (this state is shown in FIG. 2B). After a lapse of a predetermined time, the rotation is stopped, the wafer 11 is separated from the suction fixing head 13,
Heat for several minutes on a hot plate heated in the range of 80 to 150 ° C to form a thin film of polyamic acid resin 12 on wafer 11, and further heat to 300 to 500 ° C to imidize polyamic acid resin. Then, a polyimide protective film is formed. Here, it is necessary to form a polyamic acid resin thin film having a uniform film thickness.

[0003]

However, in this conventional method, the thin film of the polyamic acid resin 12a on the outermost peripheral portion of the wafer 11 becomes thicker as shown in FIG. And the film thickness B of the outermost periphery is 2 to 3
It has the doubled drawback. When a polyimide film obtained by imidizing a thin film of the polyamic acid resin 12 at 300 to 500 ° C is subjected to basic etching, the outermost peripheral film is thicker than the central part of the wafer, and thus the polyimide film at the outermost peripheral part is insufficiently etched. Occurs, and the product yield decreases. Furthermore, the difference in the polyimide film thickness on the wafer is 2-3
Lapping (polishing) of the backside of the wafer, because it doubles
There was a defect that cracks were generated from the outermost periphery of the wafer during the process.

The present invention has been made to solve the above-mentioned drawbacks, and a semiconductor having an excellent yield in which a polyimide film having a uniform film thickness is formed on a wafer to prevent cracks from occurring during the lapping process. It is intended to provide a method for manufacturing a device.

[0005]

As a result of intensive studies to achieve the above object, the present inventor has found that the thick film at the outermost peripheral portion is gradually formed after the spin coating is stopped. The present invention has been completed by finding that the above-mentioned objects can be achieved by heating and baking.

That is, according to the present invention, a polyamic acid resin solution is dropped on the center of a horizontal wafer to perform spin coating, and the entire surface of the wafer is heated while continuing the rotation of the wafer to be substantially uniform. A method for manufacturing a semiconductor device is characterized in that a polyamic acid resin film having a different thickness is formed, and then the polyamic acid resin is imidized to form a polyimide resin film.

Hereinafter, the present invention will be described.

The polyamic acid resin used in the present invention is not particularly limited as long as it is a precursor of polyimide, and those generally used for protecting semiconductors can be widely used. This method of forming a protective film can be applied to polyimide-based materials for other uses such as resists.

Examples of the heating device used in the present invention include hot air blowing, heat radiation from a hot plate, microwaves, far infrared rays, etc., but there is no particular limitation as long as the wafer can be heated over almost the entire surface. The type of heat source and the heating method are not limited.

Next, a method of manufacturing a semiconductor device according to the present invention will be described with reference to the drawings.

1A to 1C are views for explaining a method of forming a protective film of a semiconductor device according to each heating method.

First, the wafer 1 is suction-mounted on the wafer suction-fixing head 13 using the same spin coating apparatus as shown in FIG. 2 for explaining the conventional method, and a liquid of polyimide precursor, which is a polyimide precursor, is almost centered on the wafer 1. Place the polyamic acid resin 2 and set the wafer suction fixing head 13 at 500 to 1000 rpm.
The polyamic acid resin film is spread on the wafer 1 by rotating the wafer suction fixing head 13 for 10 times.
Rotate for 30 to 60 seconds at a rotation speed of 00 to 3000 rpm.

Further, at a rotational speed of 500 to 1000 rpm, 30 to 30
At the same time as rotating for 120 seconds, heated air 5 is blown from the air blowing portion 4 toward the entire surface of the wafer to heat the surface of the wafer 1 to 80 to 150 ° C, and the film thickness varies even if the wafer is removed from the coating apparatus. To form a baked polyamic acid resin film. This state is shown in FIG.

Far-infrared rays 7 are emitted from a far-infrared ray generating section 6 provided on the upper surface of the wafer in place of the heated air 5, and the wafer surface is heated to 80 to 150 ° C. to polyamide. An acid resin film can also be formed. Also,
From the bottom of the wafer suction fixing head 13 to the panel hitter 8
The upper surface of the wafer is heated to 80 ~
It is also possible to form a baked polyamic acid resin film by heating to 150 ° C. This state is shown in FIG.

In the polyamic acid resin film thus formed on the wafer, the number of rotations of the wafer, the rotation time (heating time), and the heating temperature of the upper surface of the wafer are arbitrarily set depending on the viscosity and the resin solid content of the applied polyamic acid resin. do it,
It can be applied so that the uniform thickness of the coating film is maintained even after the wafer is detached from the wafer suction fixing head. The polyamic acid resin film having a uniform film thickness which does not change even after the removal is formed by imidizing the polyamic acid resin to form a polyimide film.

[0016]

According to the method of manufacturing a semiconductor device of the present invention, the polyamic acid resin is spin-coated on the wafer and the entire surface of the wafer is heated, so that the film thickness is uniform and does not change without a separate heating step. A resin film can be formed.

[0017]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1 A flask equipped with a stirrer, a cooler and a nitrogen inlet tube was placed in a flask.
4,4'-Diaminodiphenylmethane 5.95g (0.030 mo
l) and bis (4-aminophenyl) ether 14g (0.07mo
l) and 218 g of N-methyl-2-pyrrolidone, and 21.36 g (0.02) of pyromellitic dianhydride under a nitrogen atmosphere at room temperature.
98 mol) was added and the mixture was stirred at room temperature for 10 hours to synthesize a polyamic acid resin solution. Polyamic acid resin powder obtained by reprecipitating a part of this polyamic acid resin solution with methyl alcohol was dissolved in N-methyl-2-pyrrolidone to give 0.5 g / 10
When the logarithmic viscosity was measured at 30 ° C with a 0 ml concentration, it was 1.01d.
It was l / g.

The polyamic acid resin solution thus prepared was dropped onto a silicon wafer and a spin coater was operated at 700 r.
The wafer was rotated at pm for 30 seconds, then at 3500 rpm, and heated at 95 ° C for 90 seconds while being rotated at 1000 rpm for 90 seconds. After this, the thickness of the polyamic acid resin film in the central portion of the wafer was 10 μm, and the thickness of the polyamic acid resin film in the outermost peripheral portion of the wafer was also 10 μm.

The polyamic acid resin film on this wafer was coated with 20
The polyimide resin film having a thickness of 5 μm was formed by heating at 0 ° C. for 30 minutes and at 350 ° C. for 60 minutes. The wafer on which this polyimide resin film was formed was treated with a basic polyimide etching solution (hydrazine hydrate / ethylenediamine = 70:
When the wafer was immersed in 30% by volume at 30 ° C., the entire surface of the wafer could be etched in the same etching time in both the central portion and the outermost peripheral portion.

Example 2 The same operation as in Example 1 was carried out except that far infrared rays were applied to the entire surface of the wafer instead of blowing heated air from the surface to the entire surface of the wafer. When this wafer was etched in the same manner as in Example 1, the entire surface of the wafer could be etched in the same etching time in both the central portion and the outermost peripheral portion.

Example 3 The same operation as in Example 1 was carried out except that the entire surface of the wafer was heated by a pipe heater instead of blowing heated air from the surface to the entire surface of the wafer. When this wafer was etched in the same manner as in Example 1,
The entire surface of the wafer could be etched in the same etching time in both the central portion and the outermost portion. However, since the pipe heater cannot be brought into contact with the wafer suction fixing head, heating is performed by heat conduction by radiation, so the heating time was set longer than in Example 1.

Comparative Example After spin-coating a polyamic acid resin solution on a wafer using a spin coater, the wafer was removed from the apparatus and heated at 95 ° C. for 3 minutes to form a polyamic acid resin film at the center of the wafer. A polyamic acid resin film having a thickness of 10 μm was obtained.
At this time, the polyamide acid resin film on the outermost periphery of the wafer had a ring-like shape with a width of 3 mm and a film thickness of 20 μm. This wafer
The film was heated at 200 ° C. for 30 minutes and at 350 ° C. for 60 minutes to form a polyimide resin film having a thickness of about 4.5 μm near the center of the wafer. The wafer on which this polyimide resin film was formed was immersed in a basic polyimide etching solution (hydrazine hydrate / ethylenediamine = 70/30% by volume) at 30 ° C. However, etching was insufficient at the outermost peripheral portion, and the yield was reduced.

[0024]

As is apparent from the above description, according to the method of manufacturing a semiconductor device of the present invention, a polyamic acid resin film having a uniform film thickness can be formed on a wafer, and the wafer can be formed during the lapping process. It is possible to manufacture a semiconductor device in which the generation of cracks is prevented and the yield is excellent.

[Brief description of drawings]

FIG. 1A to FIG. 1C are schematic views illustrating each heating method in a method for manufacturing a semiconductor device of the present invention.

FIG. 2A and FIG. 2B are schematic diagrams illustrating steps of a conventional protective film forming method.

FIG. 3 is a partial cross-sectional view of a wafer showing a state of the outer periphery of the wafer by a conventional protective film forming method.

[Explanation of symbols]

 1, 11 Wafer 2, 12 Polyamic acid resin film 13 Wafer suction fixed head 4 Heated air blowing part 5 Heated air 6 Far infrared ray generation part 7 Far infrared ray 8 Pipe heater 9 Heat conduction

Claims (1)

[Claims] 1. A horizontally oriented wafer is coated with a polyamic acid resin solution by dripping a polyamic acid resin solution and spin-coated, and the entire surface of the wafer is heated while continuing the rotation of the wafer to form a film having a substantially uniform film thickness. A method of manufacturing a semiconductor device, comprising forming a polyamic acid resin film, and then imidizing the polyamic acid resin to form a polyimide resin film.