JPH098018A - 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 can be substantially uniform 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 at a center of a horizontally placed wafer 1 to have it spin-coated, forming a polyamide acid resin film 2 whose thickness can be substantially uniform by heating an outermost periphery 3 of the wafer by blowing hot blast 5 or the like while the wafer 1 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. A polyimide film having a uniform film thickness is formed on a wafer to prevent generation of a defective residual film in the etching process and cracks in the lapping process. An object of the present invention is to provide a method for manufacturing a semiconductor device which is prevented and has an excellent yield.

[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 object can be achieved by heating the outermost peripheral portion of the wafer.

That is, according to the present invention, the polyamic acid resin liquid is dropped on the center portion of a horizontal wafer for spin coating, and the outermost peripheral portion of the wafer is heated while continuing the rotation of the wafer to reduce the film thickness. A method of manufacturing a semiconductor device is characterized in that a polyamic acid resin film capable of being substantially uniform 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, and the outer peripheral portion of the wafer is partially heated. It is sufficient if possible, and 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.

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

First, the wafer 1 is suction-attached to a wafer suction-fixing head (not shown) using the same spin coater as that shown in FIG. 2 for explaining the conventional method, and the polyimide precursor is placed substantially on the center of the wafer 1. The liquid polyamic acid resin 2 is placed on the wafer 1, and the wafer 1 is rotated at a rotation speed of about 500 to 1000 rpm to spread the polyamic acid resin film on the wafer 1. Then, the wafer 1 is rotated at a rotation speed of 1000 to 3000 rpm. so
Rotate for 30-60 seconds.

Further, at a rotational speed of 500 to 1000 rpm, 30 to 30
At the same time as forming the polyamic acid resin film by rotating for 120 seconds, as shown in FIG.
The heated air 5 is blown out from the air blowing part 4 toward 80 ° C. to 80 to 150 ° C. In this way, the polyamic acid resin film capable of making the film thickness substantially uniform is formed by partially heating the resin film particularly on the outer peripheral portion. This state is shown in FIG.

As shown in FIG. 1 (b), the heated air is blown out by providing an air blower 4 at the lower part of the wafer 1 and blowing it out, and heating the lower part of the outer periphery of the wafer to 80 to 150 ° C. It is also possible to form a polyamic acid resin film in which heat is conducted and the outer peripheral portion is heated. Also, wafer 1
It is heated by the panel hitter 6 provided below and its conduction heat 7
It is also possible to heat the resin film to 80 to 150 ° C. to form a polyamic acid resin film having a heated outer peripheral portion. This state is shown in FIG.

In this way, it is possible to form a polyamic acid resin film having a substantially uniform film thickness on the wafer. To this end, the number of rotations of the wafer, rotation time (heating time),
The heating temperature of the upper surface of the wafer can be arbitrarily set and coating can be performed. Then, the wafer 1 can be removed from the spin coater and then heated as required to imidize the amide groups and carboxylic acid groups of the polyamic acid resin to form a polyimide resin film.

[0016]

According to the method of manufacturing a semiconductor device of the present invention, by coating the polyamic acid resin on the wafer by rotation and heating the outermost peripheral portion of the wafer to the minimum, the polyamic acid having a uniform film thickness after imidization can be obtained. 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 used.
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 rpm for 90 seconds while being rotated at 1000 rpm for 90 seconds. At this time, the thickness of the polyamic acid resin film in the central part of the wafer was 10 μm, and the thickness of the polyamic acid resin film in the outermost peripheral part 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 heated air was blown from the back surface of the outermost peripheral portion of the wafer instead of blowing the heated air from the outermost peripheral 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 back surface of the wafer was heated by a pipe heater instead of blowing heated air from the surface to the outermost peripheral portion of the wafer in Example 1.
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. However, since the pipe heater heats by heat radiation and heat conduction from the back surface of the wafer, the heating time was set longer than in Example 1.

Comparative Example A polyamic acid resin solution was spin-coated on a wafer using a spin coater, and the wafer was heated at 95 ° C. for 3 minutes. The thickness of the polyamic acid resin film at the center of the wafer is 10
μm, Polyamic acid resin film on outermost part of wafer is 3mm
The width was 20 μm. The wafer was heated at 200 ° C. for 30 minutes and 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 a defective residual film or lapping in the etching process can be achieved. It is possible to prevent the occurrence of cracks in the wafer during a process or the like and manufacture a semiconductor device having an excellent yield.

[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 3 Outermost part of polyamic acid resin film 4 Heated air blowing part 5 Heated air 6 Pipe heater 7 Heat conduction 13 Wafer suction fixing head

Claims (1)

[Claims] 1. A film thickness is made substantially uniform by dripping a polyamic acid resin liquid onto the center portion of a horizontal wafer and spin-coating the same, and heating the outermost peripheral portion of the wafer while continuing the rotation of the wafer. A method of manufacturing a semiconductor device, comprising forming a polyamic acid resin film to be obtained, and then imidizing the polyamic acid resin to form a polyimide resin film.