JPH0222533B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a pattern alignment method, and more particularly to a pattern alignment method when manufacturing a semiconductor device using a pair of objective lenses.

(b) Conventional technology The degree of integration of semiconductor devices is increasing year by year, and patterns are becoming increasingly finer. Accordingly, the manufacturing equipment for semiconductor devices is undergoing a revolution, and the optical lithography technology is also shifting from a contact exposure method to a reflection projection exposure method.

Specifically, the exposure technologies include contact exposure method, proximity exposure method, reflective projection method, and reduction projection exposure method, as described in "Latest LSI Process Technology" published by Kogyo Kenkyukai, pages 261 to 264. is known, and the 1:1 exposure method and the 5:1 exposure method are known.
It is roughly divided into reduction exposure methods such as 1 or 10:1.

In a contact exposure method, a proximity exposure method, or a reflective projection method that employs a 1:1 exposure method, a pair of key patterns 11 and 12 are provided on the left and right sides of the mask as shown in FIGS. 3 and 4.
Manual alignment mark 1 for each element
There are 3. Figure 3 shows key pattern 11,1
2 is a top view showing the position where key patterns 11 and 12 are provided, and key patterns 11 and 12 are provided spaced apart on the left and right sides of the wafer. Figure 4 shows the left and right key pattern 11 in Figure 3,
12 and each element pattern around it 14...14
It is an enlarged view of. Normally, the key patterns 11 and 12 occupy one element pattern 14, and are formed by a V-shaped target mark. Each element pattern 14...14 is provided with a manual alignment mark 13 on a pattern (not shown) necessary for forming each element and a blank area inside the pattern such as the periphery or on a scribe line.

In the conventional exposure method, a mask alignment device automatically aligns the mask and wafer using key patterns 11 and 12, and then offset adjustment is performed using each manual alignment mark 13 using an objective lens. After that, each element pattern is printed by exposure. This offset adjustment is for manually correcting errors between the key patterns 11 and 12 and each element pattern that occur when creating a mask, and errors due to distortion of the wafer that occurs during manufacturing.

(c) Problems to be solved by the invention However, in the conventional exposure method, the manual alignment mark 13 is
It was set to be placed on an extension of the target center TC, which is the apex of the ``F'' shape. This is because fine adjustment is performed while simultaneously viewing the left and right manual alignment marks 13 using a pair of objective lenses during offset adjustment. The pair of objective lenses has a mechanism that moves them the same distance inward or the same distance outward, so they can be adjusted to the target center.
This is because when positioned on the TC, the left and right manual alignment marks 13 can be captured simultaneously.

However, fixing the position of the manual alignment mark 13 has the disadvantage that the degree of freedom in pattern design is greatly reduced. In order to avoid this, if the position of the manual alignment mark 13 is changed,
When adjusting the offset, it becomes impossible to view the left and right manual alignment marks 13 at the same time using a pair of objective lenses, resulting in a disadvantage that the offset adjustment requires a large amount of time and the accuracy of alignment decreases.

(d) Means for Solving the Problems The present invention has been made in view of the above-mentioned drawbacks, and the target mark of the key pattern is provided so that the target center is an extension of the scribe center of the scribe line, and the manual alignment mark is provided. Since the manual alignment mark is provided on the extension of the chip center, the manual alignment mark can be set at a position other than the extension of the conventional target center, thereby providing a pattern positioning method that allows freedom in pattern design.

(E) Effect According to the present invention, since the manual alignment mark is provided on the extension of the chip center C,
After automatically aligning with a mask alignment device using a key pattern, the manual alignment mark can be seen at the same time even if the pair of objective lenses is moved left and right, making offset adjustment easy.

(F) Embodiment The pattern alignment method according to the present invention will be described in detail with reference to FIGS. 1 and 2.

The left and right patterns shown in FIG. 1 are enlarged views of key patterns 1 and 2 provided spaced apart on the left and right sides of the mask shown in FIG. 2 and each element pattern (not shown) around them.

The alignment mark according to the present invention is composed of key patterns 1 and 2 and a manual alignment mark 3. As shown in FIG. 2, the key patterns 1 and 2 are spaced apart from each other on the left and right, and each key pattern 1 and 2 is formed so as to occupy usually two elements of the element pattern 5. The shape of the key patterns 1 and 2 is formed by a V-shaped target mark 4, and alignment is made by positioning the V-shaped mark on the wafer between two sets of parallel V-shaped marks provided on the mask side. I do. Although the key patterns 1 and 2 have only one type of target mark 4 in FIG. 1, they have multiple types of target marks 4, and the dashed line connecting the vertices of the target marks 4 is called a target center TC. Therefore, each target mark 4 has a different target center TC. The manual alignment marks 3...3 are provided for each element pattern 5, and are formed by providing instruction marks corresponding to various process steps such as diffusion and etching within a square or rectangular frame.

A feature of the present invention lies in the positional relationship between the key patterns 1 and 2 and the manual alignment marks 3...3. In other words, target center TC of target mark 4 of key patterns 1 and 2 is set to scribe center SC.
Align it with the manual alignment mark 3...
3 is provided on an extension of each chip center C in a margin of each element pattern 5 or on an adjacent horizontal scribe line 6. target mark 4
Since the target center TC is made to coincide with the scribe center SC, the key patterns 1 and 2 are formed using two of each adjacent element pattern 5. Therefore, if the lateral size of the chip is 2l, each manual alignment mark 3...3 is formed on each element pattern 5 at a distance l from the target center TC to the left and right. Note that the triangular manual alignment marks 7...7 provided on the extension of the target center TC are based on conventional rules, and in the present invention, it is possible to select either the present invention or the conventional alignment marks.

According to the present invention, when the pair of objective lenses is moved inward from the target center TC by l, the first
On the key pattern 1 side shown on the left side of the figure, the manual alignment mark 3 located at the chip center C of each element pattern 5 on the right side can be seen as shown by the arrow, and on the key pattern 2 side shown on the right side of Fig. 1, the manual alignment mark 3 can be seen on the left side as shown by the arrow. The manual alignment mark 3 at the chip center C of each element pattern 5 can be seen. Conversely, if the pair of objective lenses is moved outward from the target center TC by l, the manual alignment marks 3...3 on the opposite side can be viewed at the same time. After that, by moving the pair of objective lenses inward or outward by the horizontal size 2l of each element pattern 5, the manual alignment marks 3...3 of each adjacent element pattern 5 can be viewed simultaneously using the pair of objective lenses one after another. be able to.

According to the present invention, after mechanical automatic positioning is performed using key patterns 1 and 2, offset adjustment is performed using a pair of objective lenses. This offset adjustment is performed while moving the pair of objective lenses outward or inward to capture the manual alignment marks 3, .

(G) Effects of the Invention According to the present invention, the manual alignment marks 3...3 can be set at locations other than the extension of the conventional target center TC, so the positions of the manual alignment marks 3...3 can be selected and pattern design is free. You can improve your degree.

Next, in the present invention, even if the position of the manual alignment marks 3...3 is changed, the offset adjustment can be performed while looking at the left and right manual alignment marks 3...3 simultaneously in both fields of view of a pair of objective lenses, just as in the conventional method. Adjustment time can be shortened and alignment accuracy can be improved.

[Brief explanation of drawings]

FIG. 1 is a top view illustrating the pattern alignment method of the present invention, FIG. 2 is a top view illustrating the position of the key pattern used in the present invention, and FIG. 3 is a top view illustrating the position of the conventional key pattern. 4 are top views illustrating a conventional pattern positioning method. 1 and 2 are key patterns, 3...3 are manual alignment marks, 4 is a target mark, 5 is each element pattern, 6 is a scribe line, TC is a target center, C is a chip center, and SC is a scribe center.

Claims (1)

[Claims] 1 After performing automatic alignment using the key pattern using a mask having a key pattern and manual alignment marks provided for each element, offset adjustment is performed using a pair of objective lenses using left and right manual alignment marks. In the pattern alignment method, the target center of the target mark of the key pattern is provided on an extension of the center of a vertical scribe line between each element, the manual alignment mark is provided on an extension of the chip center of each element pattern, and the A pattern alignment method characterized in that offset adjustment is performed by simultaneously viewing the manual alignment mark with a pair of objective lenses.