Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of...
Reexamination Certificate
1999-04-19
2001-04-24
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
C438S782000
Reexamination Certificate
active
06221787
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a treatment apparatus and a treatment method, for example, for coating a substrate with a resist film and developing the exposed resist film.
2. Description of the Related Art
In a manufacturing process of a semiconductor device, there are a series of processes called photolithography in which a resist film is formed on a semiconductor wafer (referred to as a wafer hereinafter), a circuit pattern and the like are reduced by photo-technology to expose the resist film, and the exposed resist film is developed.
In the photolithography processes, as a circuit pattern becomes fine, it becomes important to precisely control the line width of a resist pattern. The line width of a resist pattern changes depending on various conditions such as conditions in resist coating.
For example, a spin coating method is one of methods for coating a wafer with a resist solution. In the spin coating method, with an increase in the rotational frequency of a wafer, centrifugal force increases, whereby film thickness becomes smaller and line width changes. Specifically, film thickness is influenced by the rotational frequency of a motor of a spin chuck, and moreover varied by the temperature and humidity of atmosphere. Therefore, hitherto, a resist film is formed on a test wafer, for example, once in several days to set a desired value of the rotational frequency of the motor required for obtaining optimum film thickness. In a mass-producing process, the temperature and humidity of atmosphere are controlled so as to be fixed, and the formation of a resist film (coating of a resist solution) is performed with the desired value.
SUMMARY OF THE INVENTION
When a workman sets a desired value of rotational frequency, the desired value often changes due to some factor, that is, the desired value is frequently different from a desired value in the last test or in the last test but one, whereby the workman has trouble setting a desired value of rotational frequency. Since a desired value of rotational frequency always changes as described above, frequent tests are required. In addition, even if such adjustment is regularly performed, there are cases where film thickness is outside specified limits in a mass production. In such cases, it is necessary to stop a line and start a test again. As described above, hitherto, the setting operation (test) of a desired value of rotational frequency is performed in a state that any factor of a change in film thickness can not be found out. Thus, execution of stable treatment is difficult and the frequency of tests is high, which results in one of the causes of a reduction in throughput. Moreover, film thickness is outside specified limits in mass production, which causes wafers in which the line width of a resist pattern is poor.
An object of the present invention is to provide an art in which the line width of a resist pattern can be precisely controlled.
To solve the above disadvantages, in the first aspect of the present invention, an apparatus for coating a substrate with a resist film and developing the exposed resist film includes a coating section for coating the substrate with a resist film, a first film thickness detecting section for detecting thickness of the resist film coated on the substrate, and means for setting at least either one condition of a condition for exposing the resist film or a condition for developing the exposed resist film according to the detected thickness of the resist film.
In the present invention, after a resist film is coated, the thickness of the resist film is detected. From a result of the detection, feedforward control of treatment conditions, for example, in an exposure process or a developing process following a resist film coating process is performed. Consequently, the line width of a resist pattern can be precisely controlled.
In the second aspect of the present invention, an apparatus for holding a substrate on a substrate holding section rotated by a driving section, supplying a coating solution to the substrate while rotating the substrate, and forming a coating film over the substrate by spreading the coating solution by centrifugal force of the rotation includes an atmospheric pressure detecting section for detecting atmospheric pressure and a rotational frequency control section for finding a desired value of the rotational frequency of the substrate to comply with targeted thickness of a coating film based on a detected value of atmospheric pressure by the atmospheric pressure detecting section, and controlling the drive section to fix the rotational frequency of the substrate at the desired value.
The present invention is based on acquirement of knowledge that the thickness of a coating film is influenced by atmospheric pressure, whereby the thickness of a coating film is unstable so far. Therefore, based on a detected value of atmospheric pressure, a desired value of the rotational frequency of a substrate to comply with targeted thickness of a coating film is found. Accordingly, even if atmospheric pressure changes, coating treatment is performed at appropriate rotational frequency of the substrate according to the change, whereby film thickness is stabilized. As a result, the frequency of testing operations for checking the relationship between rotational frequency and film thickness can be reduced, and the testing operation is facilitated. Thus, throughput can be improved and the burden imposed on a workman is lightened. In the present invention, taking humidity besides atmospheric pressure into account, a desired value of rotational frequency may be found based on atmospheric pressure and humidity. Further, the temperature of a coating solution may be controlled based on the temperature of atmosphere. Furthermore, thickness of a coating film formed on a substrate may be detected.
REFERENCES:
patent: 4738910 (1988-04-01), Ito et al.
patent: 5968691 (1999-10-01), Yoshioka et al.
patent: 6051349 (2000-04-01), Yoshioka et al.
Dang Phuc T.
Nelms David
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tokyo Electron Limited
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