JPS62137547A - mask inspection equipment - 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 [Technical Field] The present invention relates to a technique that is effective when applied to mask inspection, and particularly to mask inspection performed using a pattern transferred to a resist. Note that the mask referred to herein also includes a reticle used for reduction exposure.

[Background technology]

In the process of manufacturing semiconductor devices, so-called masks are frequently used for forming circuits, wiring, and the like.

The above-mentioned mask generally has a light-shielding film made of chromium <cr> or the like in a predetermined pattern adhered to a transparent substrate such as glass. Then, the mask is placed on the semiconductor wafer,
By irradiating light from above, a light-shielding film pattern (hereinafter also referred to as a mask pattern) is transferred to the resist deposited on the wafer, and the transferred resist pattern is used to create various circuits, wiring, etc. formation takes place.

Therefore, if a mask pattern has a shape defect, a similar defect will occur in circuits, wiring, etc. formed on a semiconductor wafer. Therefore, it is necessary to previously inspect the formed mask and the mask before use to ensure that there are no abnormalities in the shape of the mask pattern due to adhesion of foreign matter or the like.

The following methods can be considered for the above mask inspection. First, a transparent substrate on which resist III is deposited is prepared,
The cough resist film is exposed and developed using the required mask to transfer the mask pattern.

Next, light is irradiated from above the transparent substrate having the resist pattern onto which the mask pattern has been transferred, and the transmitted light is received by the lower light receiving section to read the light absorption pattern caused by the resist pattern. Check the shape defects of the mask pattern from the pattern.

When performing mask inspection using the above method, if a commonly used mercury lamp or the like is used as a light source, the light contains light in a wavelength range that is not absorbed by the resist film, so it is not possible to obtain sufficient contrast. Therefore, the inventor found that there is a problem in inspection accuracy when using the above light source.

Regarding masks, please refer to Kogyo Kenkyukai Co., Ltd., 1932.
Published November 15, 1981, "Electronic Materials", Betsuji, 1981.
It is explained below on page 2 03.

[Purpose of the invention]

An object of the present invention is to provide a technique that can improve the accuracy of mask inspection performed using a mask pattern transferred to a resist film attached to a transparent substrate.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, the wavelength range that the resist film absorbs is 450
Sample light supply unit that can supply light below nm! By installing it on one side of part ii, it is possible to detect the resist pattern formed on the inspection transparent substrate placed on the sample mounting part with good contrast, thereby improving the accuracy of the mask pattern, which is the original pattern of the resist pattern. It can be easily inspected.

〔Example〕

FIG. 1 is a schematic explanatory diagram of a mask inspection apparatus according to an embodiment of the present invention. Further, FIG. 2 is a graph showing a light transmittance curve for a resist film.

The mask inspection apparatus of this embodiment has an arm 2 in an xy drive section 1.
The sample storage unit 3 is connected to the sample storage unit 3 via the sample storage unit 3, and a light supply unit 6 consisting of a high-pressure mercury lamp (light source) 4 and an interference filter (spectroscope) 5 is installed above the sample storage unit 3. has been done. Further, a light receiving section 7 is arranged below the sample storage section 3, and the light receiving section 7 and the XIJ movement section 1 are interlocked with each other via a control section 8. Note that a hole for transmitting light is formed in the center of the sample holding section 3.

Next, the operation of this embodiment will be explained.

First, a novolac-based resist material is applied to a transparent substrate made of quartz, and heated to a predetermined temperature to form a resist I/film. Next, a mask pattern of a desired mask is transferred onto the resist film using a conventional method.

The transparent substrate 10 on which the resist pattern 9 with the mask pattern transferred as described above is formed is placed on the sample mounting section 3 as shown in FIG. 1.

Next, from the light supply section 6, a beam of 450 nm or less, preferably 3
The transparent substrate 10 is irradiated with light in a wavelength range of 50 nm or less, and the transmitted light is detected by the light receiving section 7. At that time, the sample mounting section 3 is moved by the xy drive section 1, and the resist pattern 9 is
The entire area of the mask is irradiated with light, and as a result, it is possible to inspect the original pattern of the mask.

In this embodiment, by passing the light from the high-pressure mercury lamp through the interference filter 5 and separating it into 45
Only light in the wavelength range of 0 nm or less is used for inspection. As a result, highly accurate mask inspection becomes possible.

That is, as shown in the light transmission curve for the resist film in FIG. 2, the resist film has the property of transmitting light having a wavelength exceeding 450 nm to a considerable extent. The resist film used here was made of the novolak resin used in -m, and added with a predetermined amount of naphthoquinone diazide as a sensitizer. Specifically, the resist film had a thickness of 9 μm, which was prepared by coating the above resin on a quartz substrate and then pre-baking it at 90° C. for 10 minutes. On the other hand, it has sufficient absorption ability for light having a wavelength of 450 nm or less, particularly 350 nm or less.

Therefore, when the resist pattern 9 is irradiated with light of 450 nm or less, clear light absorption occurs at the position where the resist pattern 9 exists. Therefore, in the light-receiving section 7, the light-transmissive part of the glass alone and the non-transparent part of the resist pattern 9 can be sensed with sufficient contrast.

If light in a wavelength range exceeding 450 nm is irradiated at the same time, a considerable amount of light will also pass through the resist pattern 9, making it impossible to sense the presence or absence of the pattern 9 with good contrast. Furthermore, since the wavelength is long, the resolution is also reduced, further reducing the inspection accuracy.

Note that as the interference filter 5, for example, a metal interference filter can be used to selectively supply light in a narrow wavelength range of 450 nm or less, thereby further improving the inspection accuracy.

〔effect〕

(1) 4500m, which is the wavelength range that the resist film absorbs
By installing a light supply unit capable of supplying the following light on one side of the sample mounting unit and installing a light receiving unit on the other side, the light that can be formed on the transparent substrate for inspection placed on the sample*2 part is installed. By being able to detect a resist pattern with good contrast, it is possible to accurately inspect a mask pattern that is an original pattern of a resist pattern.

(2) According to (1) above, a semiconductor device can be manufactured using a mask with no defects in the mask pattern, so that an improvement in yield can be achieved.

(3) By supplying light in a desired narrow specific wavelength range to the light supply section, contrast can be further improved, and inspection accuracy can be further improved.

(4) By forming the light supply unit with a light source and a spectroscope, light in a desired wavelength range can be easily supplied even when a light source with a wide wavelength range is used.

(5) By using an optical filter as a 6-spectroscope, light in a desired wavelength range can be easily supplied.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, although the light supply unit is shown to be composed of a light source and a spectroscope, it may not have a spectroscope as long as the light source itself can selectively supply light of 450 nm or less. Although the case where a high-pressure mercury lamp is used as a light source and an optical filter is used as a spectroscope has been described, other light sources such as a He-Ne laser generator may also be used, and other sources such as a prism may be used as a spectrometer. It may be a spectrometer.

In addition, although we have explained that the resist film used for mask inspection is made of novolac resin, it is not limited to this, and commonly used resists also have sufficient absorption for light of 450 nm or less, regardless of whether it is positive or negative. exists, so it is naturally applicable.

Furthermore, it is also possible to conduct inspection by incorporating a light absorber into the resist and irradiating it with light corresponding to a specific absorption wavelength of the light absorber.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a mask inspection apparatus according to an embodiment of the present invention, and FIG. 2 is a graph showing a light transmittance curve for a resist film. DESCRIPTION OF SYMBOLS 1... XY drive part, 2... Arm, 3... Sample mounting part, 4... High pressure mercury lamp (light tA), 5... Interference filter (spectroscope), 6... Light supply section, 7... Light receiving section, 8... Control section, 9... Resist pattern, 1
0...Transparent substrate. Figure 1 Figure 2 Aocho (/L7jC)

Claims (1)

[Scope of Claim] A mask inspection device comprising a light supply section and a light receiving section capable of supplying light of 1,450 nm or less, and a sample mounting section located between the light supply section and the light receiving section. 2. The mask inspection apparatus according to claim 1, wherein the wavelength of the light from the light supply section is 350 nm or less. 3. The mask inspection apparatus according to claim 1, wherein the light supply section is capable of selectively supplying light in a specific wavelength band within a narrow wavelength range. 4. The mask inspection apparatus according to claim 1, wherein the light supply section comprises a light source and a spectrometer. 5. The mask inspection apparatus according to claim 3, wherein the spectroscope is an interference filter or a prism.