JPS6360526B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for photoresist coating (particularly spray coating) in a PR step in manufacturing a semiconductor device.

In general, typical photoresist coating methods used in the PR process in semiconductor device manufacturing methods include spinner coating, dip coating, and spray coating, but special processes that require a thick film, such as resist When performing dry honing using a mask, when increasing the thickness of the metal film in stencil PR, when improving chemical resistance is required, reduce the negative impact of scratches on the PR film surface due to the thickening of the PR film. When necessary, it is almost impossible to apply the above-mentioned coating when forming a U-groove on a semiconductor wafer surface by group etching to achieve film thickness uniformity, and various problems arise. is left behind. To obtain a thick film, spinner coating requires that the film thickness differs between the central and peripheral parts of the semiconductor wafer due to the rotation direction and centrifugal force, as shown in Figures 1 and 2. I am. That is, as shown in FIG. 1, the photoresist 2 becomes thicker at the periphery of the semiconductor wafer 1. Further, as shown in FIG. 2A, the semiconductor wafer 11 having a U-groove surface is also coated in the same way by group etching, and as is clear from FIG. 2B, which is an enlarged view of this, part a is The film thickness is extremely thin, while it is thick at part b, and the variation in film thickness is large, making it difficult to control the exposure amount. Here f is the centrifugal direction. Also, in dip coating, the coating state is as shown in FIG.
, and the film thickness becomes uneven.
It becomes difficult to control the exposure amount. In spray coating, the state of the film is determined by the dry state of the resist during spray coating, and if the resist dries quickly during spray coating, the semiconductor wafer 21, as shown in FIGS.
If it is too late, the state will be similar to deep coating as shown in FIGS. 6 and 7, and the C portion will become thinner. (However, the film thickness is uniform). Conventionally, coating was performed with the drying speed of the latter being slow, but when coating a semiconductor surface with a U-groove, the resist flows and the film thickness at the C portion is reduced as shown in Figure 7B. It is nearly impossible to apply photoresist films to the above-mentioned special processes, such as thinning.

SUMMARY OF THE INVENTION An object of the present invention is to provide a photoresist coating method that prevents the above-mentioned problems and makes it possible to apply a photoresist film to the above-mentioned special processes.

In the photoresist spray coating method of the present invention, during spray coating, the resist is kept in a semi-dry state and then coated onto the wafer surface, particularly at the corners of the semiconductor wafer surface where U-grooves have been formed by group etching. This method not only prevents the resist from flowing, but also prevents pinholes in the coating film and forms a thick film. The state of the coating film in photoresist spray coating is determined by the dry state of the resist at the time of spray coating. That is, it is determined by conditions such as the viscosity of the resist, the pressure and distance of the spray nozzle, the flow rate of the resist, the temperature in the spray coating chamber, and the humidity (including the exhaust speed). Temperature and humidity in the spray coating room (including exhaust speed)
The viscosity of the resist should be kept constant and the viscosity should be such that it does not draw strings during spray coating, e.g.
7cp, and the spray nozzle pressure is, for example, 4.0Kg/
cm distance is 20cm, and control the resist flow rate. Further, the film thickness is controlled by the number of times of coating. By coating the resist in a semi-dry state using this method, the results shown in FIG.
As shown in FIG. 9, even if the semiconductor wafer surface is flat or has a U-groove formed by group etching, a thick film can be obtained with a uniform film thickness. It becomes possible to apply a photoresist film to Also, in Figure 9B, which is an enlarged version of Figure 9A, d
It is shown that the thickness of the part is also uniform.

[Brief explanation of drawings]

1, 2A, 3, 4, 5A, 6 and 7A are cross-sectional views showing the state of resist on a semiconductor wafer by coating methods according to the prior art, respectively. Yes, Figure 2B,
FIG. 5B and FIG. 7B are enlarged views showing a part of FIG. 2A, FIG. 5A, and FIG. 7A, respectively. 8 and 9A are cross-sectional views showing the state of a resist on a semiconductor wafer according to an embodiment of the present invention, and FIG. 9B is an enlarged cross-sectional view showing a part of FIG. 9A. It is a diagram. In addition, in the figure, 1, 11, 21, 31, 4
1, 51, 61, 71, 81 are semiconductor wafers,
2, 12, 22, 32, 42, 52, 62, 7
2 and 82 are resists, a, b, c, and d are portions of the resist, and f is a centrifugal direction.

Claims (1)

[Claims] 1. A method for manufacturing a semiconductor device, which comprises spraying a photoresist on the surface of a semiconductor wafer in a semi-dry state.