JPH0239520A - Resist film thickness measuring method - Google Patents

Abstract

PURPOSE:To enable measurement of the thickness of a resist film in each process by detecting the light reflected from the art that a semiconductor chip is not formed at the periphery of a semiconductor wafer. CONSTITUTION:Prior to applying coating liquid, reference measurement by a film measuring device 11 is done first. At this time, it is adjusted in advance such that an optical fiber 12 may be positioned above the surplus region 4a of a semiconductor wafer 1 at a point of time when a position detector 13 detected, e.g., the end of an orientation flat 2 by slowly rotating the semiconductor wafer 1. And according to the detection signal of the position detector 13, it is stored in advance as read-in of the reflected light signal at the film thickness measuring device 11, that is, as reference. Hereafter, resist liquid is supplied from a nozzle 14 so as to form a resist film, and again the optical fiber 12 of the film thickness measuring device 11 and the position detector 13 are shifted to the vicinity of the semiconductor wafer 1 so as to read reflected light signals from the part in the surplus region 4a and that there is no step such as wafer ID, etc., and compares them with the results of reference measurement to calculate the thickness of the resist film.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a method for measuring resist film thickness.

(Prior Art) In general, in the semiconductor manufacturing process, a predetermined pattern is transferred by performing film lithography on a semiconductor wafer multiple times to form a large number of semiconductor chips on one semiconductor wafer. tends to be highly integrated,
There is also a tendency for the patterns to become finer.

On the other hand, in order to accurately transfer fine patterns using photolithography, it is necessary to accurately form a resist film to a predetermined thickness, so improvements have been made to coating equipment, and it is now possible to reduce variations in film thickness by four methods. A spin coating apparatus that can achieve an error within an error range of about 5 nm has been developed.

In addition, as a method for measuring such resist film thickness,
A method has been developed in which the resist film thickness is measured by irradiating the substrate surface with light and detecting the reflected light from the substrate surface and the resist film surface.

(Problems to be Solved by the Invention) However, with the resist film thickness measuring method described above, the resist film thickness cannot be measured unless the base is flat. On the other hand, in the process of forming semiconductor chips on semiconductor wafers, multiple photolithography processes are performed, but in many cases, only the first photolithography process is performed when the base is flat; This means that it is only during this first photolithography process that the resist film thickness can be measured.

For this reason, in the past, it has not been practically done to measure the resist film thickness by incorporating a resist film thickness measuring device into the manufacturing line, but due to changes in ambient temperature etc., spin coating equipment etc. The thickness of the resist formed by the method may change, and the line width of the pattern formed may change due to the change in the thickness of the resist.

The present invention has been made in response to such conventional circumstances, and it is an object of the present invention to provide a resist film thickness measuring method that can measure the film thickness of a resist film formed on a semiconductor wafer in each process of semiconductor manufacturing. That is.

[Structure of the Invention] (Means for Solving the Problems) That is, the present invention includes the steps of emitting light and detecting the reflected light of the light to measure the thickness of a resist film formed on the surface of a semiconductor wafer. The method is characterized in that the thickness of the resist film is measured by detecting the reflected light from a portion of the peripheral edge of the semiconductor wafer where no semiconductor chip is formed.

(Function) In the method for measuring resist film thickness of the present invention having the above configuration, reflected light from a region on the peripheral edge of a semiconductor wafer where no semiconductor chips are formed, that is, a region with a flat base, is detected and the thickness of the resist film is measured. Set the thickness to all+. Therefore, it is possible to measure the thickness of a resist film formed on a semiconductor wafer in each step of semiconductor manufacturing.

(Example) Hereinafter, embodiments of the method of the present invention will be described with reference to the drawings.

The semiconductor wafer 1 is formed into a roughly circular shape, and an orientation flat 2 is formed by cutting out a part of the periphery of the semiconductor wafer 1.
is provided. Further, on the surface of the semiconductor wafer 1, a large number of substantially rectangular semiconductor chips 3 which are in the process of being manufactured are formed. Furthermore, since the rectangular semiconductor chips 3 are arranged side by side on the circular semiconductor wafer 1, an extra region 4 where no semiconductor chips are formed is formed around the region where these semiconductor chips 3 are formed. There is. In this embodiment, the a+++ determination of the resist film thickness is performed by measuring the reflected light from the surplus region 4a formed in the vicinity of the orientation flat 2 among the surplus regions 4, for example.

That is, as shown in FIG. 2, the semiconductor wafer 1 is placed on a wafer mounting table 10 of a spin coating apparatus, and the spin coating apparatus is provided with a film thickness measuring device 11.

The film thickness measuring device 11 transmits light from a light source to a predetermined portion from the tip of the optical fiber 12 through a filter that makes the resist film not sensitive to the wavelength, such as a wavelength of 580 nm or more. After irradiating the optical fiber 12 as a beam, only the light with a predetermined wavelength selected by the filter among the reflected light incident from the tip of the optical fiber 12 is input to the light receiving element and converted into an electrical signal.
The film thickness is calculated by inputting it to the arithmetic unit via the amplifier and A/D converter.
It is configured to determine pI.

In addition, near the tip of the optical fiber 12, for example, a light receiving element and a light emitting element are provided facing each other.
A position detection device 13 for detecting the orientation flat 2 of the semiconductor wafer 1 is provided.

Then, before applying the coating liquid by supplying the coating liquid from the nozzle 14, a reference measurement is first performed using the film thickness determination device 11. At this time, for example, the semiconductor wafer 1 is slowly rotated in the direction of the arrow shown in FIG. The positional relationship between the optical fiber 12 and the position detection device 13 is adjusted in advance so that the optical fiber 12 and the position detection device 13 are located above the surplus area 4a. Then, according to the detection signal of the position detection device 13, the reflected light signal is read in the film thickness measurement device 11 and stored as a reference.

After that, the optical fiber 12 and position detection device 13 of the film thickness measurement device 11 are moved from the vicinity of the semiconductor wafer 1,
The resist solution is supplied from the nozzle 14 in a state where the resist solution is prevented from adhering, and the drive control device 15 and the drive device 16 rotate the semiconductor wafer 1 at high speed to uniformly apply the resist solution to the surface of the semiconductor wafer 1. to form a resist film.

Thereafter, the optical fiber 12 of the film thickness measuring device 11 and the position detecting device 13 are moved to the vicinity of the semiconductor wafer \1 again, and a portion of the surplus area 4a of the semiconductor wafer 1 is measured in the same manner as in the reference '4p1 determination described above. A reflected light signal from a portion without a step such as a wafer ID is read and compared with a reference Jlll determination result stored in a memory to calculate the resist film thickness.

That is, in the resist film thickness measurement method of this example,
By detecting the orientation flat 2 with the position detection device 13, the film thickness measurement device 11 detects the surplus region 4a of the semiconductor wafer 1 where no semiconductor chips are formed.
Since the resist film thickness is determined by measuring the reflected light from the resist film i91, it is possible to measure the film thickness of the resist film formed on the semiconductor wafer 1 in each step of semiconductor manufacturing.

Therefore, for example, by sending this measurement data to the host computer 17 and sending a command from the host computer 17 to the drive control device 15 to adjust the spin speed of the spin coating device, the thickness of the resist film can be controlled to a predetermined thickness. This makes it possible to manufacture high-quality semiconductor chips.

In the above embodiment, the coating device has a film thickness of l1I.
Although we have described an example in which the IJ constant device 11 is incorporated, for example, as shown in FIG. In the case of the processing apparatus, a measuring device 24 consisting of the above-mentioned mounting table 10, film thickness measuring device 11, etc. is provided before and after the coating device 21, and the film thickness is measured by measuring reflected light before and after coating. It can also be configured like this.

In addition, as shown in Fig. 4, there is a transport robot 3 in the center.
A coating device 31, a hot plate 32, a developing device 33, etc. were provided around the device, and a transfer robot 30 was configured to allow semiconductor wafers to be loaded and unloaded into each of the devices as desired. If it is a processing device, only one measuring device 34 consisting of a mounting table] 0, a film thickness A11l determining device 11, etc. is provided, and one measuring device 3 is installed.
In step 4, the film thickness can also be determined by measuring the reflected light before and after coating.

[Effects of the Invention] As described above, by using the method for determining resist film thickness of the present invention, it is possible to measure the thickness of a resist film formed on a semiconductor wafer in each step of semiconductor manufacturing.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a semiconductor wafer for explaining a method according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a measuring device for explaining a method according to an embodiment of the present invention, and FIGS. The figure shows an example of the arrangement of measuring devices. 1... Semiconductor wafer, 2... Orientation flat, 3... Semiconductor chip, 4
... Surplus area, 4a... Surplus area for measuring reflected light, 12... Optical fiber of film thickness gauge 1 determination device. 13... Position detection device.

Claims (1)

[Claims] (1) When measuring the thickness of a resist film formed on the surface of a semiconductor wafer by irradiating light and detecting the reflected light of this light, A method for measuring resist film thickness, comprising: measuring the thickness of the resist film by detecting the reflected light.