JPS5992527A - Pattern for measurement - Google Patents

Abstract

PURPOSE:To perform both measurement inspection and matching inspection using one kind of cell by a method wherein a measurement cell is formed in square framelike shape, and the measurements of the frames are deviated corresponding to the mask so that the frames are formed without overlapping with each other. CONSTITUTION:Measuring patterns 15-17 are formed into square frame shape in such a manner that the center position of each frame will be in coincidence with each other. Also, the length of a side of said frames is to be increased from the pattern 15 toward the pattern 17, and when each of them is printed on the wafer, each of patterns 15A-17A is not overlapped with each other, and they are constituted in such a manner that gaps 18A and 19A are formed between each pattern. The patterns 15A-17A are formed on the patterns 15-17 in such a manner that their lower side will be in parallel with X direction and their right and left sides will be in parallel with Y direction, the outside measurements of the X or Y direction of the patterns 15A-17A are compared with the outside measurements of the patterns 15-17 using a pattern recognition device, thereby enabling to detect the accuracy of measurements.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measurement pattern that facilitates and automates the inspection of element patterns formed by a photolithography process, which is one of the manufacturing processes of semiconductor devices.

In a photolithography process used in the manufacture of semiconductor devices, a plurality of masks each having a different pattern are sequentially printed onto the surface of a semiconductor wafer to obtain a predetermined device pattern. For this reason, if there is a dimensional error in even one of the patterns printed on each mask, or if there is a relative positional shift between the printed patterns on each mask, pattern defects will occur, causing variations in device characteristics and defects. Occur.

Therefore, in the past, a measurement pattern was provided on each mask, the measurement pattern was baked at the same time as the element pattern was baked, and the shape and dimensions of the measurement pattern formed on the wafer were measured after the process was completed. , the quality of the pattern printing of each mask, that is, the quality of the element pattern is inspected. For example, FIG. 1 shows an example of this, in which two masks 1 and 2 are each formed with approximately U-shaped dimension measurement cells (patterns) 3 and 4, and one mask 1 is further formed with rectangular dimension measurement cells (patterns) 3 and 4. Forming a positive type alignment measurement cell 5,
On the other mask 2, a negative-type matching measurement cell 6 smaller in size than the measurement cell 5 is formed concentrically with the measurement cell 5.

Then, these two squares 1 and 2 are sequentially printed on the wafer 7 to form the pattern 3 of each cell/l/3.4, 5, and 6.
a, 4a*5ae6a, each pattern 3a of the dimension measurement cells 3, 4 is formed in the subsequent inspection process.
, 4a, the printing dimensions of each mask can be inspected, and by measuring the frame width of the rectangular frame-shaped patterns 5a, 5a formed by the duplex measurement cells 5, 6, it is possible to inspect the printing dimensions of each mask. The relative positional relationship of the masks can be inspected.

However, for each cell shape like this, two types of cells are required for dimension inspection and alignment inspection, and the dimensions of many patterns for each cell must be measured in the inspection process, especially when the number of masks is large. A problem sometimes arises in that the task of cell formation and dimensional measurement becomes extremely difficult.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a measurement pattern that allows dimensional inspection and alignment inspection to be performed using one type of cell, thereby making cell formation and dimensional measurement operations extremely easy.

In order to achieve this objective, the present invention sets the shape of the measurement cell to be a rectangular frame, and the dimensions of the frame are varied depending on each mask so that the frames are concentric and do not overlap each other. It is something.

Hereinafter, the present invention will be explained with reference to illustrated embodiments.

FIG. 2 schematically shows an embodiment of the present invention.
1 is a group of masks on which a pattern is printed by a photolithography process on a semiconductor wafer 10 on which a required element pattern is formed on the surface of the semiconductor wafer 10. In this example, three masks 12, 13, and 14 are shown. . These masks 12, 13 and 14 are respectively transparent glass substrates 12.
Predetermined different patterns 12 on al 13a #14a
b, 13b.

14b and are used in sequence to print each pattern 12b, 13b, 14b onto the semiconductor wafer 10.

The measurement pattern (cell) is 12.13°14 for each mask.
, that is, patterns 12a and 13a.

It is provided outside the area of 14a, and each mask 12, 13°1
The measurement patterns 15, 16, and 17 of No. 4 are all formed at the same position on the mask. That is, each measurement pattern 1
5.16.17 is formed into a square frame shape, and
Make sure that the center positions of each frame match, and pattern 1
When the side length is increased from 5 to 17 and each pattern is printed on a wafer, the patterns 15A, 16A, and 17A do not overlap as shown in FIG. 3, and gaps 18A and 19A are formed between each pattern. It is configured so that Further, in this example, each pattern 15, 16.degree. 17 is formed in a negative shape, and a positive image is printed on the wafer 10. Further, each of the patterns 15, 16, and 17 is formed so that its lower side is parallel to the so-called X direction (X scanning direction), and its left and right sides are parallel to the Y direction (X scanning direction).

According to the above configuration, the photolithography process is performed using the masks 12, 13, and 14 in order, and the wafer 1
When the required element pattern 10a is completed on the surface of the wafer 100, a measurement pattern 20 shown in FIG. 3 is simultaneously formed on a part of the surface of the wafer 100. This measurement pattern 20
is large, medium.

It is clear from the foregoing that the small square frame patterns 15A, 16A, 17A are arranged concentrically, and each pattern 15A, 16A, 17A is formed as a positive image.

In the inspection using Hakoko's measurement pattern 2o, for example, a pattern recognition device using a laser beam and a CCD is used, and the laser beam is passed approximately through the center of the pattern, once in the X direction and once in the Y direction. Just scan it. By scanning each pattern 15 as shown in detail in FIG.
A, 16A.

17A (7) External dimensions of frame in X direction and Y direction: 1x1.
tyl.

lxs, lyx, lxs, tys can be measured, and the gaps 18A and 19A between each pattern can be measured in the X direction and Y direction.
Dimension in direction tx1. tyl, tyl, tx
4. t7t, tyl, tys.

ty4. can be measured. Therefore, among these, the outer dimensions 1. tx2. M8 * tyl, tF!
By comparing . Can be detected. On the other hand, the opposing dimensions txl and t of each gap 18A, 19A
By comparing x2, tyt, and tym, the relative alignment of the mask 13 with respect to the mask 12 can be detected, and similarly, by comparing and examining the dimensions txA and tx4, and t7s and ty4, the relative position of the mask 14 with respect to the mask 13 can be detected. .

Of course, the dimensional accuracy may be detected by measuring the width dimension and inner dimension of the frame of each pattern 15A, 16A, 17A, or alignment may be detected using these values.

Here, in this embodiment, each pattern 15.16°17 is formed in the shape of a square frame, but it may be formed in the shape of a similar rectangular frame depending on the dimensional processing calculation ability of the inspection device. .

As described below, according to the measurement pattern of the present invention, the measurement pattern to be formed on a plurality of masks is formed into a square frame shape,
In addition, since the patterns on each mask are arranged concentrically with different sizes so that they do not overlap, the dimensional accuracy and accuracy of each mask can be determined by measuring the dimensions of the pattern formed on the wafer 61 times in the X and Y directions. The mutual relative positioning of the masks can be inspected at the same time, thereby making it easier to form a measurement pattern on the mask, and having the effect of simplifying and speeding up the inspection.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining a conventional pattern. FIG. 2 is a schematic diagram for explaining a pattern of the present invention. FIG. 3 is a plan view of a measurement pattern. FIG. 4 is an enlarged view thereof. 10... Wafer, 11... Mask group, 12, 13
゜14...Mask, 15, 16.17...Measurement pattern, 15A, 16A, 17A...Measurement pattern baked in, 18A, 19A...Gap, 20...Baked measurement pattern. Figure 1. Figure 2

Claims (1)

[Claims] 1. In a device in which a plurality of masks are used to form a required element pattern on a wafer, the measurement pattern formed on each mask is formed in the shape of a rectangular frame, and each pattern is A measurement pattern characterized by having different sizes and being set in a concentric position so as not to overlap each other. 2. The measurement pattern according to claim 1, wherein each pattern has a similar rectangular frame shape. 3. The measurement pattern according to claim 2, wherein each pattern has a square frame shape.