JPH04336413A - Mask alignment method - Google Patents

Abstract

PURPOSE:To simplify the alignment by aligning the nearly cross-shaped first alignment mark made on a wafer and the nearly cross-shaped second alignment mark made on a photomask. CONSTITUTION:Alignment marks are both cross-shaped. When putting marks on top of each other, the first alignment mark 12 made on a wafer is surrounded by a second alignment mark 2. Out of lines which form the marks, the line m and m' which extend from the center to periphery and come closest to each other are not parallel. These lines do not lie upon each other, and at start of the alignment, each mark can be judged. Thus, the alignment can be performed well after checking the alignment marks respectively made on the wafer and the photomask quickly.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a mask alignment method in the manufacture of semiconductor devices, and in particular, a method for allowing an operator to relatively align a wafer and a photomask by themselves prior to resist baking in a photoetching process. Regarding.

0002

2. Description of the Related Art In a photoetching process, one method of aligning a photomask on a wafer is to provide alignment marks on a wafer and a photomask and align the marks with each other. There is a method to adjust the relative position between the photomask and the photomask. In this method, the alignment mark used is, for example, a cross shape as shown in FIG. In the conventional method, the cross shapes 11 and 12 provided on the wafer and the photomask are similar shapes, and as shown in the figure, by arranging one mark 11 within the other mark 12 evenly spaced over the entire circumference, , completes the alignment of the wafer and photomask.

0003

In the above alignment, the operator aligns the marks while moving the wafer on the XY stage back and forth and left and right using a mouse driver or the like. The spacing between the alignment marks is usually several μm,
If this is narrowed further, alignment work will be hindered. On the other hand, since both alignment marks are equally spaced at intervals of several μm over the entire circumference, final fine adjustment is rather difficult, and the time required for mask alignment tends to be longer. Furthermore, since the operator makes judgments in positioning, there is a risk that patterning may be performed at a position deviated from the optimum position due to the difficulty of fine adjustment.

[0004] The purpose of the present invention is to solve the above problems,
An object of the present invention is to provide a mask alignment method that allows alignment marks to be aligned more easily.

[0005]

[Means for Solving the Problems] The mask alignment method according to the present invention includes a substantially cross-shaped first alignment mark formed on a wafer, and a substantially cross-shaped second alignment mark formed on a photomask. In the method of relatively aligning the positions of the wafer and the photomask by aligning the wafer and the photomask, one of the first and second alignment marks is large enough to completely surround the other, and one of the first and second alignment marks is large enough to completely surround the other. When aligning, alignment marks are used such that among the lines forming each alignment mark, the lines extending from the center to the outer periphery and closest to each other are non-parallel.

[0006]

[Operation] The alignment mark used in the method according to the present invention has a shape as shown in FIG. 1, for example. Both of these alignment marks are in the shape of a cross, and if you overlay them, for example, as shown in the figure,
A first alignment mark 1 formed on the wafer is surrounded by a second alignment mark 2 formed on the photomask. This relationship may be reversed, but in any case, when the marks are superimposed, one of the first and second alignment marks surrounds the other alignment mark. At this time, among the lines forming these marks, the lines that extend from the center to the outer periphery and are closest to each other (
For example, m and m') shown in the figure are non-parallel. These lines never overlap, so when starting alignment,
You can easily identify each mark. Furthermore, if we take the relationship between lines m and m' as an example, a point that is far away from each other (for example, A-A') and a point that is close to each other (for example, B-B
′) exists. Then, the operator can perform rough alignment at a distant point (eg, A-A') and then fine-tune the alignment at a closer point (eg, B-B'). It is easier to judge alignment by making fine adjustments at points that are close to each other. In this way, after the alignment marks formed on the wafer and the photomask are quickly recognized, the alignment work can be adjusted quickly.

[0007]

EXAMPLE In a photoetching process, a wafer and a photomask were aligned using alignment marks shown in FIG. 1, and then exposed to light to form a resist pattern. Next, an etching method is performed, and 5
1 μm between the source and drain formed at μm intervals.
A gate electrode having a gate length of m was formed. The formed gate electrode (G) is connected to the source (S) as shown in FIG.
) and the drain (D). Furthermore, it was confirmed that the operator can easily make judgments in positioning.

On the other hand, when the alignment marks shown in FIG. 3 are used according to the conventional method, the gate electrode (G) is aligned with either the source (S) or the drain (D) as shown in FIG. In some cases, the gate electrode is misaligned in either the up or down direction. Also,
When aligning using the conventional method, the operator had to repeat the alignment several times. As described above, it has been revealed that the mask matching method of the present invention allows mask matching to be performed more quickly and accurately than the conventional method.

[0009] The alignment mark according to the present invention is
Without being limited to the above specific examples, various different shapes and sizes can be used.

0010

As described above, according to the present invention, alignment marks can be aligned more easily. Therefore, in the manufacture of semiconductor devices, the workability of mask alignment is improved, and the possibility that patterning deviates from the optimum position will be formed is reduced. Therefore, the present invention contributes to improving the yield in manufacturing semiconductor devices.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a specific example of an alignment mark according to the present invention.

FIG. 2 is a plan view showing a precisely patterned gate electrode according to the present invention.

FIG. 3 is a plan view showing a specific example of alignment marks used in the conventional method.

FIG. 4 is a plan view showing a gate electrode patterned using a conventional method.

Claims (1)

[Claims] 1. By aligning a substantially cross-shaped first alignment mark formed on the wafer and a substantially cross-shaped second alignment mark formed on the photomask, the alignment between the wafer and the photomask is achieved. In the mask alignment method of relatively aligning the positions, one of the first and second alignment marks has a size that completely surrounds the other, and when one is aligned so as to surround the other, each alignment mark is A mask alignment method characterized in that, among the lines forming the mark, the lines extending from the center to the outer periphery and closest to each other are non-parallel to each other.