JPH047816A - Resist coating method - Google Patents

Abstract

PURPOSE:To enable a uniform resist film thickness to be assured by a method wherein, in order to coat a wafer with a resist, the angular velocity of a spinning holding base is changed from high to low rate corresponding to the coating work shifting from the central part to the peripheral part of the wafer. CONSTITUTION:A wafer 11 held on a holding base 12 is rapidly spinned by a motor A 13 with a discharge port 14 arranged on the central part of the wafer 11. The discharge port 14 is shifted toward the peripheral part of the wafer 11 by a feed mechanism 17 corresponding to the revolution of another motor B 16 while discharging the resist 15 little by little from the discharge port 14. At this time, the revolution of the motor 13 is controlled by the control signals converted from the signals from an encoder 18 and inputted in a controller 20 through the intermediary of a detector 19 so as to decelerated as near as the peripheral part corresponding to the distance from the central part of the wafer 11 to the discharge port 14. Through these procedures, the resist film thickness can be made uniform in the whole region of wafer 11 thereby enabling a resist film in high quality having less pinholes made to be formed.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a resist coating method for obtaining a uniform resist film thickness in a photolithography process of a semiconductor manufacturing process. The device has a mechanism for rotating a holding table that holds the semiconductor substrate, a mechanism for detecting its angular velocity, and a mechanism for moving the discharge port for coating the semiconductor substrate in the radial direction of the semiconductor substrate. This is a 1/cyst coating method in which the angular velocity is changed from high to low according to the distance traveled from the center of the substrate to the periphery.By using this method, the resist film thickness becomes uniform over the entire surface of the semiconductor substrate. .A resist film with fewer defects such as pinholes can be obtained.

[Conventional technology]

To form a pattern of a semiconductor device, selective processing t7 is normally performed using a photolithography process. In this photolithography process, a photoresist (hereinafter referred to as "resist") that is sensitive to visible light, ultraviolet rays, X-rays, electron beams, etc. is applied to the surface of a semiconductor substrate (hereinafter referred to as "wafer") depending on the processing precision. A pattern can be formed by performing exposure and development processing.

In recent years, in order to realize highly integrated semiconductor devices such as LSI, it is necessary for the resist film thickness to be as thin and uniform as possible, and to have good adhesion to the underlying film.
Various improvements have been made to satisfy these conditions.

For example, a method was proposed in which the rotational speed of resist coating was changed in two steps as shown in Fig.
0-115224). First, as shown in FIG. 4a, a wafer 1 is held on a holding table 2 of a spin coating device, and an initial resist 3 is discharged onto the center of the wafer. Next, as shown in FIG. 4, by rotating the holding box at high speed, the resist is spread over the entire surface of the wafer like the resist 4 in the first step. Since the resist film at this time is thick, next, as shown in FIG. 4C, by rotating the holding table at low speed for a rather long time, a thin and uniform film thickness can be obtained.

[Problem to be solved by the invention]

In order to form a large number of semiconductor chips from a single wafer, it is necessary to increase the diameter of the wafer, and if resist is applied to such a large diameter wafer, the center of the wafer will be The resist film thickness at the peripheral edge of the wafer becomes thinner due to centrifugal force. Therefore, there was a risk that pinholes would occur at the peripheral edge.

[Means to solve the problem]

In order to solve the above problems, the present invention changes the angular speed at which the holding table rotates from high speed to low speed in response to resist coating while moving from the center to the peripheral edge of the wafer. , which attempts to obtain a uniform resist film thickness.

[Effect]

The resist on a rotating wafer is subjected to a centrifugal force that is proportional to the radius of the wafer and proportional to the square of the angular velocity. Since the dispersion varies depending on the viscosity of the resist, it is possible to check the uniformity of the resist film thickness by determining the functional relationship between the angular velocity changes at the center and periphery of the wafer, depending on the type of resist. can be maintained in the best condition.

C Embodiment] An embodiment of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a perspective view of a resist coating apparatus of the present invention.

A holding table 12 holding a wafer 11 is rotated by a motor A13. On the other hand, the resist 15 is
is discharged onto the wafer. At this time, the discharge port 14 is moved by the feed mechanism 17 according to the rotation of the motor B16 so as to move in the radial direction of the wafer 11. In order to detect the rotational angular velocity of the holding table 12, a signal from the encoder 18 is detected by a detector 19, and is input to a control unit 20 and converted into a control signal. This control signal controls the rotation speed of the motor A13 via the amplifier A21, and also controls the rotation speed of the motor A13 via the amplifier B2.
The rotation speed of the motor B16 is controlled via the motor B16.

Next, a method of applying resist using this resist coating apparatus will be explained. First, the wafer 11 is placed on the holding table 1.
2, the ejection port 14 is placed at the center of the wafer 11, and the motor A13 rotates the wafer at high speed. While discharging the resist 15 little by little from the discharge port 14, the discharge port 14 is moved toward the peripheral edge of the wafer 11 by the feed mechanism 17 according to the rotation of the motor B16. At this time, the rotation speed of the motor A13 is controlled by a control signal obtained by inputting the signal of the encoder 18 to the controller 20 via the detector 19 and converting the signal. The rotation speed of motor A13 is
As shown in FIG. 2, the distance decreases toward the periphery of the wafer 11, corresponding to the distance of the discharge port 14 from the center of the wafer 11.

By changing the rotational speed in this manner, the resist film thickness can be made uniform over the entire region from the center to the periphery of the wafer 11.

When resist was applied with the discharge port 14 of the resist coating apparatus of the present invention fixed at the center of the wafer 11, the resist film thickness was thinner at the peripheral edge, as shown in FIG. Since this change in resist film thickness also depends on the magnitude of resist viscosity, surface tension, etc., it is preferable to calculate the functional relationship of the control section in advance depending on the type of resist.

[Effects of the Invention] If a resist is applied using the embodiments of the present invention, the resist film thickness will be uniform over the entire region from the center to the periphery of the wafer, resulting in fewer pinholes and higher A high quality resist film can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the resist coating device of the present invention, FIG. 2 is a diagram showing changes in angular velocity of the resist coating device of the present invention, and FIG. 3 is a diagram showing the resist coating device of the present invention when the discharge port is fixed. The diagrams showing the resist film thickness and FIGS. 4A to 4C are diagrams showing the conventional resist coating method. 1.11--Wafer 2.12--Holding table 3---Initial resist 4--
------1・----1 First step resist 5-
-1--・-・・・・・・-Second step resist 1
3-・-・--・-----1-Motor A1, t----
--------・----One discharge port 15- ・---------
-1-・Registration 16-・-・・-・-Motor B 17・・・・−・−-−−−・One-feeding mechanism 18-・
...--Encoder 19---1---Detector 20----------Control section 21--
・−・−−−−−Amplifier A22−−−−−−−−−−1・−・Amplifier B Fig. 2 Distance of discharge port of IM/l in wafer Figure 1 shows the change in angular velocity.

Claims (1)

[Claims] A method for applying resist to a semiconductor substrate includes a mechanism for rotating a holding table holding the semiconductor substrate, a mechanism for detecting the rotational angular velocity of the holding table, and a discharge port for applying resist to the semiconductor substrate. and a mechanism for moving the semiconductor substrate in the radial direction, and changing the angular velocity of the holding table from high speed to low speed in accordance with the distance that the discharge port moves from the center of the semiconductor substrate to the peripheral edge of the semiconductor substrate. Application method.