JPH0222530B2 - - 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, 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...1
4 is an enlarged view of FIG. The key patterns 11 and 12 usually occupy one element pattern 14, and are formed by a square-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, a margin of the pattern around the periphery, or 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 letter. 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. A pair of objective lenses has a mechanism that moves the same distance inward or the same distance outward, so 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 present invention has been made in view of the above-mentioned drawbacks.
By shifting the manual alignment marks to half the size of each element, the number of positions where manual alignment marks can be provided is increased, thereby providing a pattern alignment method that provides a degree of freedom in design.

(E) Effect According to the present invention, since the manual alignment mark is provided at a position shifted from the target center TC by half the size of each element, alignment can be automatically performed by a mask alignment device using a key pattern. After alignment, the manual alignment marks can be viewed at the same time by moving the pair of objective lenses left and right.

(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 provided spaced apart from each other on the left and right, and each key pattern 1 and 2 is formed so as to normally occupy one element pattern. The shape of key patterns 1 and 2 is formed by a V-shaped target mark, and alignment is made by positioning the V-shaped mark on the wafer between two sets of parallelly spaced V-shaped marks provided on the mask side. I do. Although there is only one type of key pattern in FIG. 1, the key patterns 1 and 2 have multiple types of target marks 4, and the dotted line connecting the apexes of the target marks 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, and are provided around each element pattern or on an adjacent scribe line. The manual alignment marks 3...3 are formed by providing instruction marks corresponding to various processes such as diffusion and etching within a square or rectangular frame.

The feature of the present invention lies in the positional relationship between the key patterns 1 and 2 and the manual alignment marks 3...3. That is, the manual alignment marks 3...3 are provided at positions shifted from the target center TC of the target marks 4 of the key patterns 1 and 2 by half the lateral length 2l of each element pattern. When this relationship is satisfied, the manual alignment marks on the left and right sides of the wafer can be viewed simultaneously using a pair of objective lenses that move inwardly or outwardly and equidistantly.

When the pair of objective lenses is moved outward by a distance from the target center TC of key patterns 1 and 2, the distance from the target center TC to the outer manual alignment mark 3 becomes a. Next, when the pair of objective lenses is moved inward by b from the target center TC of key patterns 1 and 2, the distance from the target center TC to the inner manual alignment mark 3 becomes b. Adjacent manual alignment marks 3, 3 are provided for each element pattern, assuming that the horizontal length of the element pattern is 2l, so a+b=2l...(1) holds true. Next, if the distance between target center TC and chip center C is s, and the distance from chip center C to manual alignment mark 3 is x, then x+s=a...(2) x+s=b...(3), (2 )(3), a=b=x+s, and further
From equation (1), it can be seen that a=b=l. Therefore(2)
Substituting into the formula, x+s=l, and x=l-s...(4).

The possible range of s is o≦s≦l. If s=o, then x=l, which means that the manual alignment mark 3 is placed on the vertical scribe line.

Next, if s=l, then x=o, which means that the target center TC is placed on the vertical scrub line and the manual alignment mark 3 is placed on an extension of the chip center C.

Therefore, in the present invention, the l-s
(o≦s≦l) It is sufficient to provide only one manual alignment mark at a distant position. In other words, it is sufficient to provide only one manual alignment mark 3 at a position l away from the target center TC. Therefore, the manual alignment mark 3 can be selected from a position on the scribe line in the vertical direction from the chip center C.

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. In this offset adjustment, the manual alignment mark 3 is placed at a position l away from the target center TC.
. . 3 is provided, so even if the pair of objective lenses is moved outward or inward, the manual alignment marks 3 . . . 3 can always be seen simultaneously in both fields of view.

(G) Effects of the Invention According to the present invention, the manual alignment marks 3...3 can be set at locations other than the conventional target center TC, so the position of the manual alignment marks 3...3 can be selected and the pattern design can be improved. The degree of freedom can be greatly improved.

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 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 positioning 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 is manual alignment mark, 4 is target mark,
TC is the target 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 manual alignment mark is provided at a position half the size of each element from the center line of the target mark of the key pattern, and the offset adjustment is performed by simultaneously viewing the manual alignment mark with the pair of objective lenses. A pattern alignment method featuring: