JPH07106221A - Manufacturing method of semiconductor element - Google Patents

Abstract

PURPOSE:To enable the overlapping precision to be simultaneously checked by a method wherein the reticle rotation in exposure step is enabled to be checked furthermore a reticle rotation mark is made in a vernier pattern. CONSTITUTION:A vernier pattern 3 is provided on a scribe line 2 formed on a reticle while a reticle rotation mark is made on the same X axis or Y axis to make the vernier pattern 3 and the reticle rotation mark overlap with each other thereby enabling the reticle rotation to be checked in the processing step. Besides, the reticle rotation can be checked by checking the vernier pattern 3. Furthermore, the overlapping precision with the immediately before step as well as the reticle rotation in processing step can be checked by checking the vernier pattern 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepper used in a lithography process of a semiconductor device,
It is particularly suitable for checking reticle rotation.

[0002]

2. Description of the Related Art A lithographic process is always used to form a semiconductor element on a semiconductor substrate, and a reduction exposure apparatus or stepper is used in the exposure process. An enlarged mask or reticle is used prior to this exposure process. To manufacture. In the manufacture of such a semiconductor device, a number of masks are used to form a semiconductor wafer-circuit pattern, and it is necessary to accurately align the semiconductor wafer and the mask.

The stepper has a reticle of 1 / 2.5 to 1 /
It is an apparatus which reduces the size to 10 and transfers a predetermined pattern onto a semiconductor wafer by a step and repeat method.

Vernier patterns arranged at the four corners of the reticle.
A predetermined pattern is transferred onto the semiconductor wafer by a step-and-repeat method. Further, after implanting the impurities into the semiconductor wafer, the stepper is aligned with the pattern using another reticle, and then the pattern is transferred by the step-and-repeat method.

There is a method of reading the overlay accuracy and the reticle rotation with the preceding process by reading the vernier patterns inserted in the four corners of the reticle during this process. There is also known a method of reading a vernier value by exposure according to a reticle rotation measuring program of a stepper and calculating a reticle rotation.

The reticle is a glass substrate formed in a pattern with a size of 2.5 to 10 times the original size. The reticle is optically manufactured by using a pattern generator and an electronic beam.
There is a method of drawing.

The master mask has a reticle of 1 / 2.5-
It is a mask produced by a step-and-repeat method using a repeater while reducing the size to 1/10 times to the original size. In order to transfer a predetermined pattern onto the semiconductor wafer using the reticle, a stepper and a step-and-repeat method are used.

Therefore, when the reduction ratio is large, the reticle serves as a working mask and only one to several semiconductor chips are exposed on the semiconductor wafer at one time. For this reason, in the whole surface exposure, there are cases where the exposure field a is subjected to step-and-repeat exposure in three modes as shown in FIGS. As shown in each figure, the exposure field a is divided into a plurality of sections 1 to
The entire surface of the semiconductor wafer-1 is exposed with 9 shots.

By the way, an active element or a passive element is built in the semiconductor wafer-1, and a scribe line installed around it is subdivided by using a blade dicer to obtain a semiconductor chip.

4 of the reticle corresponding to the scribe line
A method is also known in which a vernier pattern is installed in a corner, and when the exposure field a is exposed by the step-and-repeat method, the vernier pattern is overlapped to obtain a difference.

[0011]

In the method of using a resist for measuring a reticle rotation of a stepper and confirming it with a resist covering a silicon semiconductor wafer, the reticle rotation of a product pattern is indirectly measured. Reticle rotation for each product cannot be confirmed in order to guarantee the quality.

Further, when vernier patterns are installed at the four corners of the reticle, it is impossible to specify which process is the wrong process for misalignment between the second exposure and the first exposure. Therefore, when reticle rotation occurs, it is necessary to separately evaluate whether it occurs in the first process or the second process, and if it occurs in the first process, try again (re-PEP: The Photo Engraving Process) cannot be performed and the lot cannot be used.

The present invention has been made in view of the above circumstances. In particular, the reticle rotation mark can be measured in the exposure step, and the reticle rotation mark is put in the vernier pattern to superimpose the reticle rotation marks. The accuracy can be checked at the same time.

[0014]

A semiconductor device according to the present invention is characterized in that a reticle rotation is measured by using an overlay check mark provided in an exposure field using a stepper reticle. There is a feature of the manufacturing method.

[0015]

A vernier pattern is provided on the scribe line formed on the reticle, and a reticle rotation mark is formed outside the pattern on the same X-axis or Y-axis to make a vernier pattern and a reticle rotation. By overlapping the marks, it becomes possible to investigate the reticle rotation in the processing process. Also, the reticle rotation can be investigated by investigating the vernier pattern.

Further, it is a method of examining the overlay accuracy with the immediately preceding step and the reticle rotation of the processing step by examining the vernier pattern.

[0017]

Embodiments of the present invention will be described with reference to FIGS. As shown in FIG. 4, the reticle pattern 1
A scribe line 2 is provided on the X-axis and Y-axis, and a vernier pattern 3 is provided on the X-axis, and a reticle rotation mark 4 is provided outside the reticle pattern 1 corresponding to the vernier pattern 3. Set up. On the contrary, in FIG. 5, a vernier pattern 3 is formed on the Y-axis and a reticle rotation mark 4 is formed at a position corresponding thereto. That is, the burner pattern 3 and the reticle rotation mark 4 may be installed at any position on the scribe line.

FIG. 6 shows an example in which a vernier pattern 3 is formed on the scribe line 2, and FIG. 7 shows an example in which a reticle rotation mark 4 is formed outside the reticle pattern 5. As described above, in order to transfer a predetermined pattern to the semiconductor substrate using the stepper and reticle, exposure is performed by the step-and-repeat method using the reticle 3 shown in FIG. Therefore, the patterns shown in FIG. 8 are obtained by superposing the patterns shown in FIGS. 4 of FIG.
4 ′ and 4 ″ represent the amount of overlay misalignment.

In this case, the reticle rotation is 0 μm.
Then, the reticle rotation marks 4'are in the middle of the vernier pattern 3, while the reticle rotation marks 4 and 4'appear to be inside. As a result, it becomes possible to investigate the reticle rotation. The shaded area in FIGS. 6 and 7 is the Cr surface to be installed on the reticle.

Even when the vernier pattern 3 is formed by a so-called punching pattern, a swaying result can be obtained.

[0021]

As described above, in the method of manufacturing a semiconductor device according to the present invention, the reticle rotation can be measured without increasing the pattern area of the reticle, and the pitch of the reticle rotation mark can be measured. By making variable, it is possible to easily investigate with a microscope whether it is within the desired accuracy. In the conventional vernier pattern, it was not possible to investigate the reticle rotation in the know process, but the method of the present invention makes it possible and the same vernier pattern allows the accuracy of superimposition with the preceding process to be simultaneously achieved. I can confirm.

Conventionally, when a reticle rotation occurs, it is necessary to check whether or not the previous process is caused by the process, but according to the present invention, the reticle rotation at the process may be investigated. Therefore, even if the reticle rotation occurs, it can be corrected by re-doing, and the workability is greatly improved.

[Brief description of drawings]

FIG. 1 is a top view showing an example in which one exposure field a is performed by one shot.

FIG. 2 is a top view showing an example in which four exposure fields a are performed by four shots.

FIG. 3 is a top view showing an example of performing 9 exposure fields a with 9 shots.

FIG. 4 is a top view in which a vernier pattern and a reticle rotation mark are arranged on the Y axis of a reticle used in the method of manufacturing a semiconductor device of the present invention.

FIG. 5 is a top view in which a vernier pattern and a reticle rotation mark are arranged on the X axis of a reticle used in the method of manufacturing a semiconductor device of the present invention.

FIG. 6 is an example of a reticle pattern of the vernier pattern of the present invention.

FIG. 7 is an example of a reticle pattern of the reticle rotation mark of the present invention.

FIG. 8 is an example of a semiconductor substrate on which shot patterns are superposed by a step-and-repeat process using a stepper.

[Explanation of symbols]

 1: semiconductor substrate, a: exposure field, 2: scribe line, 3: vernier pattern, 4, 4 ', 4 ": misalignment of superposition, 5: outside reticle pattern.

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor device, characterized in that a reticle rotation is measured by using a reticle for a stepper and an overlay checking mark provided in an exposure field.