JPH01138446A - Jig and method for inspecting outward appearance of photomask - Google Patents

Abstract

PURPOSE:To inspect the offset and rotational deviation of the photomask to be inspected easily in a short time by fixing an end part of a reference plate and supporting the photomask to be inspected opposite the plate surface of the reference plate. CONSTITUTION:The outward appearance inspecting jig consists of the reference plate 14 where a reference pattern corresponding to a pattern formed on the photomask 15 to be inspected is formed and a support member 11 which supports the reference plate 14 by fixing its end part and supports the photomask 15 to be inspected opposite the plate surface of the reference plate 14. Then, this outward appearance inspecting jig is used to compare the patterns of the reference plate 14 and object photomask 15 which are supported in parallel to each other to easily and securely detect the offset and rotational deviation of the pattern of the object photomask 15.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a photomask appearance inspection jig and inspection method for inspecting the appearance of photomasks used in semiconductor manufacturing processes.

(Prior Art) A conventional photomask inspection apparatus and its inspection method will be described with reference to FIGS. 2 and 3.

FIG. 2 is a plan view showing an example of a photomask, and FIG. 3 is an enlarged perspective view of a part of one chip area in the pattern shown in FIG.

2. Description of the Related Art Conventionally, length measuring machines, defect inspection devices, and the like have been used as inspection devices for inspecting photomasks. As shown in FIG.
This is for performing long dimension inspection and short dimension inspection. Further, the defect inspection device is a device for detecting defects such as shapes in the pattern 3.

Inspection of a photomask using the above inspection apparatus is performed as follows.

First, the length dimension inspection using the sub-long machine is performed to check the external dimensions of the entire pattern 3, such as dimension A and dimension B, as shown in FIG.
etc., and inspects whether the pattern 3 is formed with predetermined dimensions.

In addition, short dimension inspection using a length measuring machine is performed using pattern 3 in Figure 2.
This is to measure the width, etc. of each fine pattern within one chip area 4 included therein. For example, as shown in FIG. 3, it is inspected whether the width C of a gate pattern 5, which is a fine pattern formed within one chip region 4, is formed according to a predetermined dimension. Incidentally, the width C of the gate pattern 5 is
For example, it has a dimension of about 2.2 μm.

Next, defect inspection is performed on individual fine patterns such as the gate pattern 5 in FIG.
This is to investigate and detect contaminated areas 6, geometrically defective areas 7, and the like.

The short dimension inspection and defect inspection are generally carried out using a photomask 1.
Information obtained from a limited micro area on a surface is collected and processed, and outputs such as fixed data, pass/fail judgment, defect count, etc. are obtained.

(Problems to be Solved by the Invention) However, in the photomask inspection apparatus and inspection method having the above configuration, even if the pattern 3 is offset or rotationally misaligned with respect to the glass substrate 2, the photomask 1 cannot be rejected as a defective product. There was a problem that it could not be detected as

The problem will be explained below using FIGS. 4 and 5. FIG. 4 is a plan view of a photomask with an offset, and FIG. 5 is a plan view of a photomask with a rotational shift.

In FIG. 4, in the pattern 3 formed on the glass substrate 2, the center E of the pattern 3 may be shifted from the center of the glass substrate 2, that is, offset may occur. This offset is used in the mask setting device for setting the glass substrate 2 in the device when forming the pattern 3. For example, when the end of the glass substrate 2 is to be set at the (X, Y) point F, the parameter setting For example (Xl.

Yl) This is caused by setting it at point G.

Further, rotational deviation is a phenomenon in which, as shown in FIG. 5, the centers of the glass substrate 2 and the pattern 3, E, are the same, but there is a deviation α in the direction of rotation. This rotational shift occurs due to an error in the rotational direction when the glass substrate 2 is set in the mask placement device.

When these offsets and rotational deviations occur, there is no problem as long as they are below the allowable value of a transfer device such as a full size aligner and a reduction repeat aligner. However, as the pattern 3 becomes more highly integrated, the precision of the transfer device becomes higher, and as automation progresses, the permissible value tends to become smaller.

Therefore, it is necessary to detect the offset and rotational deviation when inspecting a photomask, but the above-described photomask inspection apparatus and method have a problem in that these cannot be detected accurately. Therefore,
A photomask with offset and rotational deviations is put into a transfer device, and semiconductor devices manufactured thereby have pattern deviations and do not operate normally.

The present invention provides a photomask appearance inspection jig and inspection method that solves the problem of the prior art in that offset and rotational deviation of the photomask cannot be detected.

(Means for Solving the Problems) In order to solve the above problems, the first invention provides a reference plate having a reference pattern formed on a plate surface corresponding to a pattern formed on a photomask to be inspected; A photomask appearance inspection jig is constituted by a support member that fixes and supports the end of the reference plate and supports the photomask to be inspected at a position facing the plate surface of the reference plate.

Further, the second invention is such that a photomask to be inspected on which a pattern is formed and a reference plate on which a reference pattern corresponding to the pattern is formed are placed facing each other, and the relative positional relationship between the pattern and the reference pattern is determined. This is a photomask appearance inspection method for inspecting the appearance of the pattern by comparing and contrasting the patterns.

(Function) According to the first invention, since the photomask appearance inspection jig is configured as described above, the reference plate on which the reference pattern corresponding to the pattern of the photomask to be inspected is formed can be connected to the pattern and the reference pattern. It serves to facilitate comparison and contrast between the two. Further, the support member serves to arrange the photomask to be inspected and the reference plate in parallel and facing each other, thereby allowing the comparison to be performed accurately and easily.

Further, in the inspection method of the second invention, the visual inspection that compares and contrasts the relative positional relationship between the pattern of the photomask to be inspected and the reference pattern of the reference plate enables easy and reliable detection of offset and rotational deviation of the pattern. It works to increase the reliability of the test.

Therefore, the above-mentioned problem can be eliminated.

(Embodiment) FIG. 1 is a perspective view of a photomask appearance inspection jig showing an embodiment of the first invention, and FIG. 6 is a plan view of the reference plate of FIG. 1.

In FIG. 1, this photomask appearance inspection jig has a support member 11. As shown in FIG. The support member 11 has a single-letter shape, and two parallel grooves 12 and 13 are formed inside the support member 11.

In one of the grooves 12 and 13, a reference plate 14 is vertically supported with its two sides fixed. The other groove 13 supports the photomask 15 to be inspected parallel to the reference plate 14 and has a structure that allows the photomask 15 to be inspected to be easily removed. Note that the support member 1
In order to accurately fix the reference plate 14, support the photomask 15 to be inspected with high accuracy, and prevent damage to the photomask 15 to be inspected, which is made of a glass substrate or the like, fluorine material 1 can be precisely processed and can be used as a shock absorbing material. It is desirable to form it with resin etc.

A reference pattern 16 is formed on the surface of the reference plate 14, as shown in FIG. This reference pattern 16 is composed of a large number of scale lines 17 and scale auxiliary lines 18 corresponding to the pattern of the photomask 15 to be inspected.

The interval between the scale line 17 and the scale auxiliary line 18 is, for example, approximately 1/2 to 1/4 m, which is an interval that is easy for humans to see during visual inspection.

The scale lines 17 and the scale auxiliary lines 18 can be formed by a screen printing method or the like.

Using the photomask appearance inspection jig configured as described above, the reference plates 14 supported parallel to each other on the support member 11 are used.
By comparing and contrasting the patterns of the photomask 15 to be inspected with the pattern of the photomask 15 to be inspected, offsets and rotational deviations of the patterns of the photomask 15 to be inspected can be easily and reliably detected.

7 is a plan view of a reference plate of a photomask appearance inspection jig showing another embodiment of the first invention, FIG. 8 is a plan view of a photomask to be inspected corresponding to the reference plate of FIG. 7, and FIG. The figure is a partially enlarged view of the reference plate of FIG. 7 and the photomask to be inspected of FIG. 8 superimposed.

This embodiment differs from the embodiments shown in FIGS. 1 and 6 as follows:
The test pattern 19 is formed as a reference pattern at two locations above and below the reference plate 14, and the test pattern 21 is correspondingly formed at two locations above and below the pattern 20 on the photomask 15 to be inspected. The shapes of the test patterns 19 and 21 are respectively two large and small quadrilateral shapes and a cross shape.

With such a configuration, substantially the same functions and advantages as those of the embodiments shown in FIGS. 1 and 6 can be obtained, and offsets and rotational deviations of the photomask 15 to be inspected can be detected more easily. That is, the reference plate 14 in FIG.
When the photomasks 15 to be inspected in the figure are arranged in parallel, the ninth
Both test patterns 19. overlap as shown in the figure.
By comparing and contrasting 21 at two locations, offset and rotational deviation can be easily detected.

Next, an embodiment of the second invention will be described using FIG. 1 and FIG. 6.

First, the photomask 15 to be inspected is attached to a predetermined position on the support member 11 of the photomask appearance inspection jig, and is placed parallel to and facing the reference plate 14 . .

Next, the reference pattern 16 formed on the reference plate 14 and the pattern of the photomask 15 to be inspected are visually compared and contrasted from the side of the photomask 15 to be inspected.

At this time, since the substrate of the photomask 15 to be inspected is made of a transparent material such as glass, the reference pattern 16
can be easily seen through.

The comparison is made by examining the relative positional relationship between the scale lines 17 and scale auxiliary lines 18 of the reference pattern 16 and the pattern of the photomask 15 to be inspected, and offsets and rotational deviations are easily detected. For example, rotational deviation is inspected by comparing the horizontally parallel scale lines 17-1 with the long dimension of the pattern of the photomask 15 to be inspected.

Further, by comparing the scale 17-2 attached to the end of the scale line 17 with the outline of the pattern of the photomask 15 to be inspected, the amount of offset can be detected.

With the photomask appearance inspection method as described above, the presence or absence of pattern offset and rotational shift in the photomask 15 to be inspected can be easily inspected using a photomask appearance inspection jig with a simple structure. It is also possible to detect the approximate value of the offset amount and rotational deviation. Roughly speaking, if a standard is determined based on the relative relationship between the patterns of both the reference plate 14 and the photomask 15 to be inspected, it can also be used as a means for determining the quality of the photomask 15 to be inspected.

In addition to the photomask appearance inspection method described above, inspection using the photomask appearance inspection jig shown in FIGS. 7 to 9 can also be carried out in the same manner as in Habo.

This inspection method includes a reference plate 14 and a photomask 15 to be inspected.
This is carried out using test patterns 19 and 21 formed at two locations, upper and lower, respectively, on both sides, and the appearance inspection can be carried out more easily and quickly than in the previous embodiment.

In addition, 1. The photomask appearance inspection jig and inspection method of the second invention are not limited to the illustrated embodiments and can be modified in various ways, including the following modifications.

(1) Although the photomask appearance inspection jig and inspection method in Figures 1 and 6 and Figures 7 to 9 are based on visual inspection, this must be done using a light emitting/receiving element. You can also do it. For example, it is also possible to automatically inspect by arranging a light emitting diode and a phototransistor on the reference plate 14 side and on the inspected photomask 15 side in FIG. 1, respectively, and scanning these.

However, in this case, the reference plate 14 needs to be made of a transparent material. Further, it is advantageous for the interval between the scale line 17 and the scale auxiliary line 18 to be as small as, for example, 1/10 #. Such finely spaced scale lines 17 etc. are -
A method similar to that used for patterning a photomask may be used.

(2) The reference pattern 16 in FIG. 6 is not limited to what is shown in the figure, and can be freely formed according to the pattern shape of the photomask 15 to be inspected. For example, the scale lines 17 and scale auxiliary lines 18 may be formed in a grid pattern, or radial auxiliary lines may be added.

(3) The reference plate 14 in FIG. 7 has a test pattern 19.
In addition, scale lines 17, etc. may be formed.

Further, the test pattern 19 is not limited to two locations, upper and lower,
For example, they can be formed on both the left and right sides.

(4) The structure, shape, material, etc. of the photomask appearance inspection jig are not limited to those shown in FIG. For example, support member 1
1 does not have a structure that completely supports the two sides of the reference plate 14 and the photomask 1.5 to be inspected, but may have a structure that partially supports them.

(Effects of the Invention) As explained in detail above, according to the photomask appearance inspection jig of the first invention, the inspection jig has an extremely simple structure and can inspect the offset and rotational deviation of the photomask to be inspected. It can be done easily and in a short time.

Further, according to the inspection method of the second invention, the presence or absence of the offset and rotational deviation can be easily and reliably tested, and the amount of offset and rotational deviation can also be detected. Therefore, a highly reliable test can be performed without disturbing the conventional test process.

[Brief explanation of the drawing]

Figure 1 is 1. A perspective view of a photomask appearance inspection jig showing an embodiment of the second invention, FIG. 2 is a plan view showing an example of a photomask, and FIG. 3 is an enlarged view of a part of one chip area in the pattern of FIG. 4 is a plan view of the photomask with an offset, FIG. 5 is a plan view of the photomask with a rotational shift, FIG. 6 is a plan view of the reference plate in FIG. 1, and FIG. 7 is a plan view of the photomask with rotational deviation. 1. A plan view of a reference plate of a photomask appearance inspection jig showing another embodiment of the second invention, FIG. 8 is a plan view of a photomask to be inspected corresponding to FIG. 7, and FIG. 9 is a plan view of the reference plate of a photomask appearance inspection jig shown in FIG. FIG. 8 is a partially enlarged view of the photomasks to be inspected shown in FIG. 11...Supporting member, 14...Reference plate,
15...Photomask to be inspected, 16...
Standard pattern, 19°21...Test pattern, 20...Pattern. Applicant's agent: Takashi Kakimoto The photomasks of the present invention are shown in Figure 1. A plan view of the photon mat. Partially enlarged view Figure 9

Claims (1)

[Scope of Claims] 1. A reference plate on which a reference pattern corresponding to a pattern formed on a photomask to be inspected is formed, and an end portion of the reference plate is fixed and supported, and the photomask to be inspected is A photomask appearance inspection jig comprising: a support member that supports the reference plate at a position opposite to the plate surface. 2. By arranging a photomask to be inspected on which a pattern is formed and a reference plate on which a reference pattern corresponding to the pattern is formed to face each other, and comparing and contrasting the relative positional relationship between the pattern and the reference pattern. A method for inspecting the appearance of a photomask, comprising inspecting the appearance of the pattern.