JPH0352673A - Method for applying photoresist - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Industrial Application Fields] This research focuses on stampers, LSIs,
This paper relates to a method for coating photoresists on substrates used in the manufacturing process of liquid crystal displays and other devices. [Prior Art] Conventionally, in the spin coating of photoresist, there are two rotation stages, the photoresist is dropped onto the substrate in the first stage, and several thousand rpm is applied in the second stage. The photoresist film was formed on the substrate by rotating at m.m. [Problems to be Solved by the Invention] However, the above-mentioned conventional techniques have the following problems when applying photoresist to large-area circular or square substrates. Large-area substrates are inevitably heavy, so in order to accurately rotate them at several thousand rpm, it is necessary to improve the performance and accuracy of parts involved in rotation, such as the motor of the coating device, which increases cost. Also, if the board is made of glass,
Is the board itself unable to withstand centrifugal force at several thousand rpm? i12
There were cases where it was destroyed. Furthermore, the photoresist that had been shaken off by the rotation at several thousand rpm collided with the inner wall of the coating device, and a portion of it bounced back and reattached to the substrate, causing defects.
The present invention is intended to solve these problems, and its purpose is to improve the quality and yield of the photoresist coating process in the manufacturing process of various products. [Means for Solving the Problems] The photoresist coating method of the present invention includes two or more rotation stages for maintaining a constant rotation speed for a certain period of time in the process of coating the photoresist on a substrate by rotation, and the first The photoresist solution is dropped onto the substrate in the rotation stage, and in the second rotation stage, the rotation speed is approximately 190 rpm, and the holding time is 6 seconds or more. [Example] Masaaki Moto will be described below based on an example.

Here, we will discuss in detail the manufacturing process of stampers used in optical memory manufacturing. In this manufacturing process, a photoresist is coated on a glass substrate with a thickness of several mm, the photoresist film is exposed to a laser beam that is modulated in accordance with the signals required for optical memory, and after development, a photoresist is obtained. Nickel i! on photoresist pattern! A stamper is manufactured by attaching a cast film and shaping the electroformed film. Therefore, the height of the pattern formed on the standber is basically the same as the photoresist thickness, and since the photoresist thickness directly affects the signal quality, a uniform resist film thickness is required within the plane and between the substrates. ．． After cleaning and drying a glass substrate with a thickness of 6 mm and a diameter of 200 mm, a photoresist was applied using a rotary coating device. The target photo register thickness is approximately 1,000 people,
In order to keep the coating rotation speed in the range of 100 orpm or less, preliminary experiments were conducted regarding the viscosity of the photoresist solution.
2.5 and 4.5 cP. As for coating conditions, experiments were conducted using a rotation pattern as shown in Figure 2, with various levels of four factors: number of rotation stages, rotation speed, holding time, and time required to reach the rotation speed of the next rotation stage. As a result, although interactions were observed between each factor, it was found that the factor that most affected the distribution of photoresist thickness within the substrate was the rotation speed of the second rotation stage. That is, as shown in FIG.
As shown in the figure, the holding time of the second rotation stage is also correlated with the photoresist thickness distribution. The results shown in Figures 3 and 4 and other factors have little effect on the distribution of photoresist thickness, so the coating conditions that make the distribution of photoresist thickness within the substrate most uniform are the rotation of the second rotation stage. The speed should be approximately 190 rpm, and the holding time should be 6 seconds or more. Furthermore, since the rotation speeds of the first and third rotation stages affect the photoresist thickness, the photoresist thickness can be adjusted by the rotation speeds. An example of the relationship between the third stage rotation speed and the photoresist thickness is shown in FIG.

Here, the first stage rotation speed was fixed at 2 Orpm and the second stage rotation speed was fixed at 190 rpm. From Figure 5, when the photoresist liquid viscosity is 2.5 cP, the third stage rotation speed must be 30 Orpm in order to make the photoresist thickness 1000.
It is sufficient to do this. Figure 1 shows the rotation pattern when forming a photoresist film for 1000 people. The variation (range) of photoresist thickness within the substrate surface at each measurement point shown in Figure 5 is as shown in Table 1, and the range was within 25 people. There were no defects caused by rebound, and the only defects were due to adhesion of foreign matter. Further, an example of the relationship between the first stage rotation speed and the photoresist thickness is shown in FIG. This means that the photoresist liquid viscosity is 2.5 cP, the second stage rotation speed is 190 rpm, and the third stage rotation speed is 300. This is an example where the rpm is fixed, but as in the case of Fig. 5, the range of photoresist thickness was within 25 people. Defects due to rebound depend on the shape of the inner wall of the coating device and the diameter of the substrate shown in Table 1, but can be considered to occur at approximately 100 rpm or higher. Therefore, if the third stage rotational speed must be increased above 100 rpm to obtain the desired photoresist thickness, it is necessary to change the viscosity of the photoresist liquid. Furthermore, even when using a square substrate, it was possible to form a photoresist film of the same quality. As mentioned above, unlike photoresist coating that conventionally required high rotation speeds of several thousand rpm, we have established uniform photoresist coating conditions in a rotation range of several hundred rpm, which places less stress on the rotation system of the coating equipment. In addition, because the centrifugal force on the substrate was drastically reduced, the substrate was virtually no longer destroyed, and defects due to photoresist liquid splashing also no longer occurred. [Effects of the Invention] As described above, according to the present invention, in the process of spin-coating photoresist on a substrate, there are two or more rotation stages that maintain a constant rotation speed for a certain period of time, and in the first rotation stage, By dropping the photoresist solution onto the substrate and setting the rotation speed to about 19 orpm and holding time for 6 seconds or more in the second rotation stage, a photoresist film with a uniform thickness can be formed on the substrate surface using the photoresist solution. It can be formed without causing defects due to rebound. In other words, by establishing a technique for forming a uniform, defect-free photoresist film in the hundreds of ppm range, it has the effect of improving quality and yield, especially in the photoresist coating process on large-area substrates. ．． In addition, since coating equipment does not need to rotate at several thousand rpm, the performance and accuracy of the equipment's rotating system can be reduced, and wear on the rotating system can be ignored, making it possible to It also has the effect of reducing costs.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic diagrams of the rotation pattern in the present invention, FIG. 3 is a diagram showing the relationship between the second stage rotation speed and the film thickness distribution in the substrate radial direction in the present invention, and FIG. A diagram showing the relationship between the second stage holding time and the film thickness range, Figure 5 is a diagram showing the relationship between the third stage rotation speed and film thickness in the present invention, and Figure 6 is a diagram showing the relationship between the first stage rotation speed and the film thickness in the present invention. Diagram showing the relationship between film thickness. 1...First rotation stage 2...Second rotation stage 3...Third rotation stage 1 1 force 1 1 2 2 Kaya J 1z Piece ■j1l Makimimi et al.

Claims (2)

[Claims] (1) In the process of spin-coating photoresist onto a substrate, there are two or more rotation stages that maintain a constant rotation speed for a certain period of time, and the first rotation stage drops the photoresist solution onto the substrate, and the second rotation stage At the stage, the rotation speed is approximately 190 rpm,
A photoresist coating method characterized by a holding time of 6 seconds or more (2) In the process of spin coating the photoresist on the substrate, the viscosity of the photoresist liquid is set from 2.5 to 6.5 cP, and there are three rotation stages that maintain a constant rotation speed for a certain period of time;
In the first rotation stage, the photoresist is dropped onto the substrate, in the second rotation stage, the rotation speed is approximately 190 rpm and the holding time is 6 seconds or more, and in the third rotation stage, the rotation speed is increased to 190 rpm.
to 1000 rpm, and the thickness is 500 to 3000 Å.
2. The photoresist coating method according to item 1, which comprises forming a photoresist film of