JPH0460333B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a method of resist coating in photolithography technology.

(b) Background of the Technology In the production of semiconductor chips, which are the main components of semiconductor devices, photolithography technology, which is applied to wafer processing and the production of masks necessary for the processing, includes a resist coating process.

For resistor coating, it is important that the thickness of the coating be uniform, so a flat plate-shaped object such as a wafer or mask substrate is rotated at a predetermined speed parallel to the surface of the object, and the coating is coated onto the surface. A method of applying a resist to a predetermined thickness is generally used.

(c) Prior Art and Problems Figures 1, 2, and 3 are a plan view a and a side view b showing the order of an example of a conventional method for applying resist, and Figure 4 is a chronological diagram. Figure 5 is a diagram showing the progress and shows the state of resist spreading failure.
1 is the object to be coated, 2 is the spin head, 3 is the nozzle,
A is the resist, S1 and S2 are the rotation speeds, a, b,
c and d indicate time, respectively.

When applying resist A to a flat object 1 such as a wafer or a mask substrate, as shown in FIG. 1, the object 1 is placed on a spin head 2 that rotates the object, The resist A is dripped onto the surface of the object to be coated 1 from the nozzle 3 while the object to be coated 1 is fixed with a chuck or the like and is stationary. Thereafter, as shown in FIG. 2, the object 1 to be coated is rotated at a low speed (rotation speed S1, for example, about 1000 rpm) by driving the spin head 2, and the resist A on the object 1 is coated over the entire surface of the object 1. spread. Subsequently, as shown in FIG.
5000rpm), and remove the excess resist A from the object to be coated 1.
The resist A on the object to be coated 1 is scattered around the area.
The thickness is set to a predetermined value (for example, about 1 μm).

The time course of the operation of this embodiment is as shown in FIG. 4, where the time a for supplying resist A is about 2 seconds, the time b from the end of supplying resist A to the start of low speed rotation is about 1 second, and the time c for low speed rotation. is about 2 seconds, and the high speed rotation time d is about 20 seconds.

Here, when the amount of dropped resist A shown in FIG. 1 is small, the resist A does not spread over the entire surface of the object 1 due to the low speed rotation, and for example, as shown in FIG. 5 (corresponding to FIG. 2 a), become that way. This state does not change much even if the time of the low-speed rotation is extended, and even after the high-speed rotation, uncoated portions remain.

Therefore, in this resist coating method, it is necessary to supply a sufficiently large amount of the resist A, and the amount is extremely large compared to the pure amount applied to the surface of the object 1 to be coated. It has a disadvantage that the amount of resist A used is large due to scattering.

(d) Object of the Invention In view of the above-mentioned conventional drawbacks, the object of the present invention is to rotate a flat plate-shaped object at a predetermined speed parallel to the surface of the object to be coated, and coat the surface with a resist to a predetermined thickness. It is an object of the present invention to provide a resist coating method that requires less amount of the resist when coating the resist.

(e) Structure of the Invention The above object is to rotate a flat object to be coated at a predetermined speed parallel to the surface of the object to coat the surface with a resist to a predetermined thickness. Start rotating the coated body at a first speed, and when the speed reaches a constant speed, start supplying the resist to the center of rotation of the coated body, and when the resist has spread over the entire surface. This is achieved by a resist coating method characterized in that the supply is stopped at a second speed, and then the resist is rotated at a second speed higher than the first speed.

This method is based on the knowledge obtained by the inventor of the present application from his extensive experience, and is based on the knowledge shown in Figure 2 a in the embodiment of the conventional method described above.
To achieve this condition, the amount of resist required is a fraction of that of conventional methods.

(f) Embodiments of the invention Examples of the invention will be described below with reference to the drawings. The same reference numerals indicate the same objects throughout the figures.

6, 7, and 8 are a plan view a and a side view b showing the sequence of an embodiment of the method of applying a resist according to the present invention, and FIG. 9 is a diagram showing the time course thereof. be.

The method of resist coating according to the present invention is a knowledge obtained by the inventor of the present application from extensive experience.

That is, as shown in FIG. 6, the object to be coated 1 is placed on the spin head 2 and fixed in the same manner as in the prior art.
Low speed rotation of the object to be coated 1 (rotation speed S1, e.g. approx.
1000rpm). Immediately, as shown in FIG. 7, the nozzle 3 began to drop and supply the resist A to the center of rotation of the rotating object 1, until the resist A spread over the entire surface of the object 1. By the way, the supply will be stopped. Thereafter, as shown in FIG. 8, the object 1 to be coated is rotated at a predetermined high speed (rotation speed S2, for example, about 5000 rpm), and the excess resist A is scattered around the object 1 to be coated.
The thickness of the upper resist A is set to a predetermined value (for example, about 1μ).
m).

The time course of the operation of this embodiment is as shown in FIG. 9, starting from the start of low-speed rotation, the time c of low-speed rotation is about 2 seconds, the time a of supplying resist A included in that period is about 0.4 seconds, and the high-speed rotation is about 2 seconds. The rotation time d is about 20 seconds. Here, the time d is the same as the conventional example in terms of its operation, but the time c is the same as in the conventional example.
This can be shortened since the supply only needs to be completed. In addition, since it is difficult in practical work to monitor whether resist A has spread over the entire surface of the object 1 to be coated, the dropping of resist A is controlled by time, and at time a, the spread of resist A is controlled. A margin is included for certainty.

The inventor of the present application has realized that by carrying out the resist coating method according to the present invention, it takes about 2 seconds to reliably coat resist A with the same standard.
It was confirmed that the supply time c was only about 0.4 seconds, and the amount of resist A used was actually reduced to 1/5.

(g) Effects of the Invention As explained above, according to the configuration of the present invention, a flat plate-shaped object to be coated is rotated at a predetermined speed parallel to the surface of the object to be coated, and a resist is applied to the surface of the object. It is possible to provide a resist coating method that requires less amount of resist when coating to a predetermined thickness, and has an economical effect that enables a significant reduction in the amount of resist used. The time required for the coating process can be shortened.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are a plan view a and a side view b showing the order of an example of a conventional method for applying a resist, and Figure 4 is a diagram showing the time course of the process. 6, 7, and 8 are plan views showing the sequence of an embodiment of the method of applying a resist according to the present invention.
, side view b, and FIG. 9 are diagrams showing the time course. In the drawings, 1 is the object to be coated, 2 is the spin head, 3 is the nozzle, A is the resist, S1 and S2 are the rotational speeds, and a, b, c, and d are the times, respectively.

Claims (1)

[Scope of Claims] 1. When applying a resist to a predetermined thickness on the surface of a flat plate-shaped object 1 by rotating it at a predetermined speed parallel to the surface of the object 1, Start rotating the body 1 at a first speed S1, and when the speed reaches a constant speed, start supplying the resist to the center of rotation on the surface of the body 1 to be coated, so that the resist covers the entire surface of the body 1. A resist coating method characterized in that the supply is terminated when the resist spreads, and then the object to be coated 1 is rotated at a second speed S2 faster than the first speed S1.