JPH08339955A - Pattern formation - Google Patents

Abstract

PURPOSE: To eliminate lowering of production efficiency caused by stoppage of a manufacturing device and much effort required for treatment by obtaining a measured film thickness value by measuring a film thickness of a workpiece film and obtaining an optimum exposure time for obtaining an optimum pattern width, based on it. CONSTITUTION: A photoresist film is formed by applying photoresist on a workpiece film formed on a substrate. A photoresist film is exposed for a specified time. A resist pattern of a specified configuration is formed by developing an exposed photoresist film. Relation between a film thickness of a workpiece film and an exposure time for obtaining an optimum pattern width is obtained and a measured film thickness value is obtained by measuring a film thickness of a workpiece film before photoresist is applied. An optimum exposure time corresponding to a measured film thickness is obtained and a specified time is set for an optimum exposure time. Thereby, an optimum exposure time is obtained without performing a treatment for a pilot substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method using a photoresist film, and more particularly to a pattern forming method using photolithography which is useful for microfabrication in the production of semiconductor elements.

[0002]

2. Description of the Related Art In a pattern forming method using a photoresist film, a SiO ₂ film or a Si film formed on a substrate is used.
Multiple interference between the photoresist film and the film to be processed occurs due to the change in the film thickness of the film to be processed such as a ₃ N ₄ film. Therefore, the pattern dimension varies with the film thickness of the film to be processed. It has been confirmed that the phenomenon occurs.

Therefore, a pilot processing method is known as a method for solving the above-mentioned variation in pattern size.

FIG. 3 shows a flow chart of the above-mentioned pilot processing method. First, a photoresist film is applied to a pilot substrate, and then the photoresist film is subjected to pattern exposure and development. Measure. The proper exposure time is obtained from the measurement result, and the photoresist film of the semiconductor element of the product lot is exposed based on the proper exposure time.

[0005]

However, in the above-described pilot processing method, since the proper exposure time is set by using the pilot substrate for each product lot, the product lot is processed until the pilot substrate is processed. However, there is a problem in that the manufacturing apparatus is stopped, the production efficiency is reduced, and a lot of labor is required for processing.

Further, in the above-mentioned pilot processing method, it is expected that it will be considerably difficult to feed back an appropriate exposure time for the pilot substrate to the exposure process when in-line processing is performed.

In view of the above, the present invention seeks an optimum exposure time without performing processing on a pilot substrate, thereby eliminating the decrease in production efficiency due to the stop of the manufacturing apparatus, and much labor for processing. The purpose is not to need.

[0008]

FIG. 2 shows a SiO 2 film to be processed when the thickness of the photoresist film is 1.22 μm.
₂ shows the relationship between the film thickness of ₂ and the pattern size. From FIG. 2, it can be seen that even if the film thickness of the photoresist film does not change, the pattern dimension changes as a sine curve when the film thickness of the processed film changes.

In the manufacturing process of semiconductor devices, the film thickness of the film to be processed is not constant between product lots. This is mainly C for depositing the film to be processed on the substrate.
It is considered that the VD device is a batch type rather than a single-wafer type.

Due to the above two reasons, it is considered that the pilot process must be performed for each product lot.

Therefore, the inventor of the present invention obtains the relationship between the film thickness of the film to be processed and the exposure time for obtaining the optimum pattern width in advance, and measures the film thickness of the film to be processed in advance.
It was found that the optimum exposure time can be obtained by setting the exposure time based on the measured value of the film thickness of the film to be processed, and the present invention has been devised based on the finding.

[0012] Specifically, the solution means taken by the invention of claim 1 is a pattern forming method, wherein a photoresist is applied on a film to be processed formed on a substrate to form a photoresist film. The exposure step includes a forming step, an exposure step of exposing the photoresist film for a predetermined time, and a pattern forming step of developing the exposed photoresist film to form a resist pattern having a predetermined shape. The relationship between the film thickness of the film to be processed and the exposure time for obtaining the optimum pattern width is obtained, and the film thickness of the film to be processed before applying the photoresist is measured to obtain the measured film thickness value. In addition, it is configured to have a step of obtaining an optimum exposure time corresponding to the measured film thickness value from the relationship and setting the predetermined time to the optimum exposure time.

According to a second aspect of the present invention, in order to make the optimum exposure value accurate, in the structure of the first aspect, in the photoresist film forming step, the film thickness of the photoresist film with respect to the target film thickness value is set. A structure having a step of applying the photoresist so as to be within a range of ± 5 nm is added.

[0014]

According to the structure of claim 1, there is a fixed relationship between the film thickness of the film to be processed and the exposure time for obtaining the optimum pattern width. When the thickness value is obtained and the exposure time is obtained from the measured film thickness value and the above relationship, the exposure time becomes the optimum exposure time for obtaining the optimum pattern width.

According to the structure of claim 2, the film thickness of the photoresist film is within ± 5 nm with respect to the target film thickness value, so that the film thickness of the film to be processed and the optimum pattern width are obtained. The relationship between and can be obtained more finely and accurately.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pattern forming method according to an embodiment of the present invention will be described below with reference to the flowchart of FIG.

First, in step 1, the film thickness of a film to be processed, for example, a silicon oxide film (hereinafter referred to as a SiO ₂ film) deposited on a silicon substrate is measured to obtain a measured film thickness value.

Next, in step 2, the SiO ₂
A photoresist film having a thickness of 1.22 μm is applied on the film. Here, a resist for a medium-reflection substrate such as a photoresist for a light die for i-line is used.

Next, in step 3, the optimum exposure time is set from the relationship between the film thickness of the SiO ₂ film deposited on the silicon substrate and the exposure time. FIG. 2 shows the thickness 1.
After the photoresist film 22μm was coated on the SiO ₂ film, it shows a change in pattern size when changing the film thickness of the SiO ₂ film between 200 nm to 350 nm. As is apparent from FIG. 2, a maximum pattern change (ΔP) of 0.12 μm is observed in the thickness of the SiO ₂ film in the line pattern having the target dimension of 0.5 μm.

[0020]

[Table 1] [Table 1] shows that the thickness of the SiO ₂ film is 30 based on the data of FIG.
The exposure time required for forming a 0.5 μm line pattern when changing every 5 nm between 0 nm and 340 nm is shown. Here, Si deposited on the substrate to be processed
The target film thickness of the O ₂ film is 320 nm, and the optimum exposure time for this film thickness is 360 msec. As shown in [Table 1], it can be seen that the optimum exposure time for forming the 0.5 μm line pattern varies with the change in the film thickness of the SiO ₂ film. And the relationship between the film thickness and the optimal exposure time of the SiO ₂ film in the database, by monitoring the thickness of Deposhijon been SiO ₂ film on the silicon substrate, it is possible to set the optimum exposure time.

Next, in step 4, the photoresist film on the silicon substrate is exposed for the optimum exposure time and then developed.

As described above, since the pattern forming method of the present invention adopts the pilot processing omission method, the production efficiency is reduced due to the stop of the manufacturing apparatus as compared with the conventional pilot processing method. It can be suppressed and does not require much effort on the pilot procedure.

Further, in the pattern forming method of the present invention, the film deposited on the silicon substrate is not the SiO ₂ film but is a Si ₃ N ₄ film or the like, which causes multiple interference with the photoresist. It can be effectively used when depositing a film on a silicon substrate.

[0024]

According to the pattern forming method of the first aspect of the present invention, the relationship between the measured film thickness value of the film to be processed and the film thickness of the film to be processed and the exposure time at which the optimum pattern width is obtained. Since the exposure time required from is the optimum exposure time to obtain the optimum pattern width, the optimum exposure time is required without processing the pilot substrate. And the labor required for the pattern forming process can be reduced.

According to the structure of claim 2, since the relationship between the film thickness of the film to be processed and the exposure time for obtaining the optimum pattern width can be obtained more finely and accurately, the optimum exposure time obtained from the above relation can be obtained. Will also be more accurate.

[Brief description of drawings]

FIG. 1 is a flowchart showing a pattern forming method according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a film thickness of SiO ₂ deposited on a substrate and a pattern dimension.

FIG. 3 is a flowchart showing a conventional pattern forming method.

Claims (2)

[Claims] 1. A photoresist film forming step of forming a photoresist film by coating a photoresist on a film to be processed formed on a substrate, and an exposure step of exposing the photoresist film for a predetermined time. And a pattern forming step of developing the exposed photoresist film to form a resist pattern of a predetermined shape, wherein the exposing step includes a film thickness of a film to be processed and an exposure time for obtaining an optimum pattern width. Is obtained, and the film thickness of the film to be processed before applying the photoresist is measured to obtain a measured film thickness value, and the optimum exposure time corresponding to the measured film thickness value is calculated from the relationship. A method for forming a pattern, comprising the step of obtaining and setting the predetermined time to the optimum exposure time. 2. In the photoresist film forming step, the film thickness of the photoresist film is ± 5 nm with respect to a target film thickness value.
The pattern forming method according to claim 1, further comprising a step of applying the photoresist so as to be within the range.