JPS6232783B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device inspection method, and its purpose is to visually inspect the dimensional fidelity and alignment of a photoresist pattern with respect to the pattern design dimensions of a photomask. It is extremely easy to judge.

In the photo-etching process during the manufacturing process of semiconductor ICs and LSIs, the fidelity of the photoresist pattern to the photomask pattern is becoming stricter as the miniaturization rules become smaller. The pattern dimensions of a photoresist pattern are almost determined by the dimensions of a photomask pattern corresponding to the pattern, but can be sufficiently controlled within about ±1 μm by adjusting exposure conditions, development conditions, baking conditions, etc. Therefore, in order to obtain appropriate pattern dimensions, for example, when determining the exposure dose, wafers with various exposure conditions are created and the pattern dimensions are measured at appropriate locations in the mask pattern using a dimension measuring device (such as a telecomputer). The pattern dimensions were compared with the pattern dimensions of the photomask pattern.

With this method, the pattern dimensions of multiple wafers must be measured each time, and the mask pattern dimensions corresponding to those dimensions must be memorized, making it extremely difficult to determine the exposure dose. It was inefficient.

The present invention is intended to improve upon the conventional drawbacks as described above. The present invention will be explained below using FIGS. 1 to 3.

In FIG. 1, 1 is the letter B, and 2 is the register mark corresponding to the B pattern. The alignment key for mask alignment in the B mask used in the photo B process (the process of patterning on a wafer using the B mask) is as shown in Figure 2, where 3 is the alignment key, 4 is the letter B, and the inside of the B pattern. Enter the name 5 of the most important pattern, such as the minimum dimension, etc. (for example, enter 2.8 μm). Then, for example, create patterns 7, 8, 9, and 10 of appropriate lengths with the width of the dimension name 5 to be focused on, two each in the X direction and Y direction, and leave two patterns, with two punches, for a total of four patterns. establish. In FIG. 2, the shaded area is where Cr, for example, is deposited on the mask, and the blank area is the transparent area. Therefore, when a positive resist is used, patterns 7 and 10 are left on the patterned wafer, and patterns 8 and 9 are blanked out. The shape of the dimension judgment region 6 and the dimension name 5 is arbitrary, but the arrangement in the alignment region is designed to be a pattern in the immediate vicinity of the alignment key 3 of the photo-etching process of interest, so that it will not be confused with that of other photo-etching processes, and For example, in visual inspection, alignment accuracy and pattern dimensional fidelity can be seen within the same field of view of a microscope.

On the other hand, the reason why the same patterns 7 and 8 and 9 and 10 are provided after pattern removal is that when proper exposure is performed, for example, these mask patterns are usually formed corresponding to patterns 7 and 8 on a patterned wafer. If the pattern widths are the same and the exposure is overexposed, if a positive resist is used, the width of the pattern corresponding to pattern 8 will remain and the pattern will be wider than the width of the pattern corresponding to pattern 7. It is easy to tell that the image is overexposed. Although the human eye has a large error in measuring absolute dimensions, the error in relative comparison of dimensions is very small, and the present invention can effectively utilize this principle.

In this implementation, the following were installed in the X and Y2 directions:
Depending on the method of mask exposure equipment, some pattern dimensions have directionality, so whether the actual pattern with the dimension of interest is in the ,Y2
It was set in the direction.

In addition, FIG. 3 shows the pattern formed on the wafer after completing the mask alignment in the 3 photo process steps (B, C, and D steps); 11 is C, 12 is D, and 13 is
is D, 14 is 2.0 μm in size, 15, 16, 17,
18 are determination patterns for a size of 2.0 μm.

According to the present invention, the widths of punched and left patterns can be accurately compared, and the pattern dimensions of microfabricated photoresist patterns can be judged each time by using a pattern width measuring device (e.g. Even without measuring with a telecomparator, the judgment can be easily made by visual inspection using a microscope, and more accurate measurements can be made using a pattern width measuring device or the like. When viewed as a whole as shown in Figure 3, it is very easy to see which photo-etching process was faithful to the mask dimensions, or whether the pattern dimensions were larger, etc., all of which remain as a history after the etching process in one place on the chip. This provides sufficient information regarding the process (especially the photo-etch process) for later failure analysis.

As described above, it can be seen that the present invention is very important in relation to future high-precision and microfabrication technology for semiconductor devices, from the viewpoint of a method for inspecting the fidelity of the dimensions of patterns formed on photomasks on wafers.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a part of a mask configuration diagram for explaining the present invention, FIG. 2 is a plan view of the vicinity of the mask alignment key in an embodiment of the present invention, and FIG. 3 is a plan view of B, C, FIG. 6 is a plan view of the vicinity of the mask alignment keys on the wafer after the photo process of D is completed (patterned); 5... Dimension display of interest, 6... Dimension pattern display area, 7, 10... Pattern remaining display pattern,
8, 9... Pattern extraction display pattern.

Claims (1)

[Scope of Claims] 1. Using a photomask with punched and left patterns for checking pattern dimensions in the vicinity of the mask alignment key, the key pattern and the punched and left patterns for checking formed in the photoetching process using the mask are examined under a microscope. A method for inspecting a semiconductor device, comprising visually inspecting it within the same field of view. 2. The method for testing a semiconductor device according to claim 1, characterized in that check patterns are provided in both vertical and horizontal directions.