JP2002072447A - Method for producing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that in a method for forming patterns on the entire surface of a wafer, the increase of the number of points of measurement in a probe test and a step for cutting a peripheral part are required so as to eliminate the dislocation of the wafer and a photomask in first pattern formation and the problem that in a method in which a pattern is not formed in a defective region of a peripheral part of a wafer, the alignment of the wafer and a photomask cannot be checked and a pattern is liable to be dislocated. SOLUTION: Pre-alignment is corrected in first pattern formation by using a photomask with plural transparent windows on a peripheral part of a wafer. An aligning mark is disposed in the pattern formation and second and later patterns are formed by exposure after alignment using the mark. The lowering of yield due to the dislocation of patterns is prevented and a step related to the removal of defective chips in the peripheral part of the wafer can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device which can easily correct a position by pre-alignment when a desired first pattern is formed on a semiconductor wafer.

[0002]

2. Description of the Related Art A lithography technique is a technique for forming a semiconductor circuit on a wafer by a technique similar to that of a photograph.
This technology is used in all processes such as metal electrode formation. In a general process, first, a photosensitive polymer (photoresist) is formed on a semiconductor substrate by a coating method. The thickness of the photoresist film is adjusted to a desired thickness by its viscosity and the number of rotations of a spinner, and the applied film is heated to remove the solvent. Next, ultraviolet light is irradiated through a photomask or a reticle on which a predetermined circuit pattern is drawn. A photochemical reaction occurs in the photoresist due to the exposure to ultraviolet light, so that the photosensitive portion becomes soluble in the developing solution, and a pattern of the photoresist is formed on the semiconductor substrate. This type of photoresist is called a positive type, and conversely, when the photosensitive portion is insolubilized, it is called a negative type. Next, the semiconductor substrate is etched using the photoresist as a mask to form a desired circuit pattern.

A photomask or reticle corresponding to an IC circuit master is first coated with a resist on a glass substrate coated with a light-shielding film such as chromium based on circuit design data made by CAD, and drawn by an electron beam drawing apparatus. After development, etching is performed to form a reticle having a desired pattern.

[0004] Based on this reticle, a photo repeater
The master mask is a one-tenth to one-time reduction, and is repeatedly transferred onto a glass plate at a size equal to that of an actual circuit. In a mirror projection exposure apparatus, since the mask does not come into contact with the wafer, the master mask is often used.
In a contact proximity device, since a mask and a wafer are in contact with each other, a work mask of the same size is created from the master mask and used in many cases. This master mask or work mask is transferred to a wafer at the same magnification to form a circuit pattern.

In a stepper apparatus, a circuit pattern is formed by repeatedly transferring a wafer to a projected image obtained by reducing a reticle of a desired pattern by a factor of 1/10 to 1 in a stepwise manner.

FIGS. 3 to 6 show two methods of forming a desired first pattern on a wafer by a contact proximity device using the photomask (work mask). The photoresist used is a positive resist.

FIGS. 3 and 4 show a first method of forming a desired first pattern over the entire surface of a wafer.

FIG. 3 shows a photomask 21, in which a desired reticle pattern 22 is transferred so as to cover the entire surface of the wafer to form a pattern region 23, and the outside thereof becomes a light shielding portion 24.

FIG. 4 shows a wafer 26 patterned using the photomask 21. Since the entire surface of the wafer 26 becomes the pattern formation region 27, there is no misalignment between the photomask 21 and the wafer 26. However, wafer 2
Since a region with incomplete quality is formed at the 6 peripheral edges, it is necessary to cut a defective chip at the peripheral edge by marking in a later step.

FIGS. 5 and 6 show a second method, in which a pattern is not formed on a portion of the peripheral edge of a wafer which is inferior in quality. At the peripheral edge of the wafer, imperfect chips are likely to be formed due to the effects of edge rinsing during development and masking due to the jaws that hold down the wafer surface when depositing electrodes, and the formation of a diffusion layer is not characteristic. It is an area lacking reliability such as completeness. For this reason, in order to prevent a chip that may be defective in long-term use from leaking to the user, the chip at the peripheral end is cut again by marking even if the chip has a good initial characteristic.
In order to omit this step, a method in which a pattern is not formed on the peripheral end portion in advance and the chip is characteristically defective is the second method described below.

FIG. 5 shows a photomask 21 in which a desired reticle pattern 22 is transferred to the inner side of the peripheral edge of the wafer to form a pattern area 23, and the peripheral edge of the wafer is a light-shielding portion 2.
4 is assumed.

FIG. 6 shows an example of a wafer 26 on which a pattern is formed using a photomask 21. Since the photomask 21 whose peripheral end is cut is used, no pattern is formed on the light-shielding portion on the mask. However, due to this light-shielding portion, misalignment between the photomask 21 and the wafer 26 cannot be confirmed during patterning. As a result, as shown in FIG. 6, the pattern formation region 27 may be displaced, and the yield may be reduced, or the peripheral edge of the wafer 26 which is incomplete in quality may not be cut.

[0013]

When a desired first pattern is transferred to the entire surface of a wafer, a pattern misalignment due to a poor pre-alignment does not occur, but the peripheral end is an incomplete area in quality. And the number of measurement points increases, and it is necessary to cut the peripheral end by marking.

On the other hand, in a method in which a pattern is not formed on the peripheral edge of the wafer in order to eliminate a chip incomplete at the peripheral edge in terms of quality, the peripheral edge of the wafer is a light-shielding portion on the mask, and the misalignment between the photomask and the wafer. Cannot be confirmed at the time of patterning. For example, the pattern region shifts largely rightward on the wafer, and a pattern shift occurs such that the peripheral end is not cut. As a result, the yield is reduced, and an operation of cutting the incomplete chips on the peripheral edge portion of the wafer by marking, which is unnecessary with this method, must be added.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has been made in consideration of the above problem. When a desired first pattern is exposed on a semiconductor wafer by using a photoresist, a plurality of portions are formed on a portion around a peripheral end of the semiconductor wafer. The method is characterized in that a photomask provided with a plurality of transparent windows is used. Since the peripheral edge of the wafer can be visually viewed from the transparent window, a prealignment correction can be easily performed and a pattern shift can be prevented. Can be provided.

[0016]

1 and 2 show a method of manufacturing a desired first pattern by a contact proximity device using a positive resist according to an embodiment of the present invention.

FIG. 1 shows a photomask provided with a transparent window, which is a feature of the present invention. The photomask 1 forms a pattern region 3 by reducing and projecting a desired reticle pattern 2 to a glass plate by a factor of 1/10 to 1 using a photo repeater in a region inside the peripheral edge of the wafer. The end portion and the outside thereof are referred to as a light shielding portion 4.

Further, the pattern region 3 of the photomask 1
A transparent pattern 5 is provided at three locations by forming a rectangular pattern on the outer periphery at a portion corresponding to the peripheral edge of the wafer with a photo repeater or the like and removing chromium or chromium oxide on the glass plate. In this case, the number of the transparent windows 5 is not limited to this, but it is preferable that the number of transparent windows 5 is three or more for accurate alignment.

The size of the transparent window 5 is, for example, when the diameter of the wafer 6 is 100 mm, the peripheral end is cut by 2 mm for the above-mentioned reason, and at a position 48 mm or more from the center of the wafer 6, the width is about 6 mm and the length is about 6 mm. It is formed into a rectangle of about 11 mm. This size is not limited as long as it does not enter the pattern area.

Using the photomask 1, a desired first pattern is transferred onto a wafer at the same magnification by a contact proximity device. First, the peripheral edge of the wafer is confirmed from the transparent window 5 by pre-alignment, and if the photomask 1 and the wafer are misaligned, the position is corrected by the wafer stage position adjustment grip of the contact proximity device. After the alignment, transfer is performed at the same magnification to form a pattern in a desired area.

FIG. 2 shows the wafer after pattern formation.
Since the pre-alignment correction has been performed, the pattern forming region 7 is arranged at the center of the wafer 6, and the peripheral end portion where a chip incomplete in quality is likely to be formed is not formed. Since this peripheral end is cut at the stage of measuring the initial characteristics, there is no need to cut again by marking.

Further, an alignment mark is formed at the time of forming the first pattern, and exposure is performed in accordance with the mark in the formation of the second and subsequent patterns, whereby a decrease in yield due to a pattern shift can be prevented.

A feature of the present invention resides in that a desired first pattern is formed on a wafer 6 by using a photomask 1 having a plurality of transparent windows provided at a portion corresponding to a peripheral edge of the wafer. Thus, the misalignment between the wafer 6 and the photomask 1 can be visually confirmed at the time of pre-alignment, so that the position can be corrected by the wafer stage position adjusting grip of the contact proximity device, and a pattern area can be formed at a desired position.

Further, an alignment mark is formed at the time of forming the first pattern, and exposure is performed in accordance with the mark at the time of forming the second and subsequent patterns. Not formed.

Thus, since the peripheral end is also cut at the initial measurement stage, it is not necessary to cut again by marking. Further, a decrease in yield due to a pattern shift can be prevented.

On the other hand, in order to avoid misalignment between the photomask and the wafer, patterning is performed on the entire surface of the wafer. However, since a photomask for cutting the peripheral end is used, the number of measurement points in the probe test can be reduced, and This eliminates the need for cutting the peripheral end.

When a negative resist is used as the photoresist, an oxide film or the like remains because a small amount of the resist remains on the peripheral edge of the wafer having the transparent window, but the scribe line is removed in a later step. The same effect can be obtained without any problem.

[0028]

According to the manufacturing method of the present invention, the desired first
When the pattern is formed, the misalignment between the wafer and the photomask can be visually confirmed by the transparent window provided at the peripheral end of the photomask, so that pre-alignment correction is possible,
A pattern region can be formed at a desired position. At this time, an alignment mark is formed, and in the second and subsequent pattern formation, exposure is performed in accordance with the mark, so that a decrease in yield can be prevented,
Wafer edges that are incomplete in quality can be cut.

As a result, the peripheral end portion is cut, and a pattern can be formed only in a region that is complete in terms of quality, and a decrease in yield due to a pattern shift can be prevented.

Further, since it is not necessary to pattern the entire surface to prevent misalignment, the number of measurement points by a probe test can be reduced, and the process of removing a chip incomplete in quality at the peripheral end by marking can be shortened. .

[Brief description of the drawings]

FIG. 1 is a top view illustrating a method for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a top view illustrating a method for manufacturing a semiconductor device according to the present invention.

FIG. 3 is a top view illustrating a conventional method for manufacturing a semiconductor device.

FIG. 4 is a top view illustrating a conventional method for manufacturing a semiconductor device.

FIG. 5 is a top view illustrating a conventional method for manufacturing a semiconductor device.

FIG. 6 is a top view illustrating a conventional method for manufacturing a semiconductor device.

Claims (3)

[Claims] When exposing a desired first pattern to a semiconductor wafer using a photoresist, it is preferable to use a photomask having a plurality of transparent windows provided at a portion corresponding to a peripheral edge of the semiconductor wafer. A method for manufacturing a semiconductor device. 2. The method according to claim 1, wherein the pattern is exposed using a contact proximity device. 3. The method according to claim 1, wherein a desired first pattern is formed on a semiconductor wafer using the photomask.