JP3461708B2 - Alignment mark device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment mark device used in a photolithography process in manufacturing a semiconductor device or a liquid crystal display device, and more particularly to an alignment mark device suitable for visual alignment.

[0002]

2. Description of the Related Art As is well known, in a projection exposure apparatus such as a stepper used in a semiconductor wafer manufacturing process, a circuit pattern to be processed is aligned. The pattern is etched, and the mask side alignment mark formed at the corresponding position of the mask having the circuit pattern is aligned with the first light opaque pattern, and then the circuit pattern is exposed.

FIG. 6 shows a conventional reduction projection type exposure apparatus used in a semiconductor device manufacturing process. The reduction projection type exposure apparatus aligns a mask M on which a circuit pattern is formed with a wafer W. Equipped with an alignment device. That is, the exposure light and the illumination light from the exposure light source system 1 reach the dichroic mirror 4 composed of a half mirror through the mirror 2 and the main condenser lens 3, and are reflected vertically downward by the dichroic mirror 4. The surface of the mask M located on the movable table 5 is illuminated.

The exposure light and the illumination light that have passed through the circuit pattern mp of the mask M are incident on the projection optical system 6 that is telecentric on both sides.
An image obtained by reducing the circuit pattern mp at a predetermined magnification is projected on the photoresist layer on the surface of the wafer W on the second movable table 7.

Further, the wafer side alignment mark wm of FIG. 7 (a) for position adjustment for etching processing is provided on the side portion of the circuit pattern wp of the wafer W, and the wafer M alignment mark is provided on the side portion of the circuit pattern of the mask M. The mask side alignment marks mm of FIG. 7B to be used are respectively attached, and the first movable table 5 and the second working table 7 described above are connected to the sheet of FIG. 6 by the drive systems 8 and 9 respectively coupled thereto. The position can be finely adjusted in the rotation direction and the two-dimensional direction in a plane at right angles.

By the way, in the reduction projection type exposure apparatus as described above, the alignment state between the wafer side alignment mark wm and the mask side alignment mark mm is visually observed by using the transmitted light of the dichroic mirror 4 described above, Although the photoresist layer is exposed with the exposure light of the exposure light source system after the complete alignment between the mask M and the wafer W is obtained, the conventional wafer side alignment mark wm and mask side alignment mark mm
For this, the pattern shown in FIG. 7 is used.

That is, the wafer-side alignment mark wm in FIG. 7A is a light-impervious cross pattern 10, and the cross pattern 10 is etched on the surface of the wafer W to align the mask-side alignment in FIG. 7B. The mark mm is composed of the "square" character arrangement pattern 11 having an interval L ₂ slightly larger than the line width L ₁ of the cross pattern 10. When such a cross pattern 10 and a "T" -shaped layout pattern 11 are used, if the wafer-side alignment mark wm and the mask-side alignment mark mm do not match each other, as shown in FIG. As shown in FIG. 9, the first movable table or the second movable table is displayed until the uniform spacing becomes uniform, as shown in FIG. The movable table is finely adjusted.

[0008]

However, since such visual alignment is performed by comparing two intervals of the width of the cross pattern 10 which are spaced apart from each other, it is a work requiring skill and the operator's visual sense. The results differ depending on the individual differences.

As described above, the cross pattern 10 used as the wafer side alignment mark wm is the wafer W.
Since it is formed on the surface of the substrate by an etching process, the line may become thicker than the prescribed line width in FIG. 10 due to the etching. In such a case, FIG. 10 showing a state in which the character arrangement pattern of “Ta” and the cross pattern 10 do not match.
(A), "Ta" character arrangement pattern and cross pattern 10
As can be understood from a comparison with FIG. 10 (b) showing the alignment state with the above, it is practically difficult to visually distinguish the two states.

Further, when the cross pattern 10 becomes thin, the interval width formed around the cross pattern 10 in the aligned state is expanded to about the line width of the cross pattern 10. Becomes difficult to perform, and it becomes impossible to perform precise positioning.

In view of the problems of the conventional alignment mark apparatus as described above, the object of the present invention is that no skill is required for visual alignment operation, there is little error due to the visual individual difference of the operator, and the pattern line The purpose is to obtain an alignment mark device that is less affected by overweight and line thinning.

[0012]

In order to achieve this object, the present invention provides a wafer-side alignment mark and a mask-side alignment mark that are optically combined to be used. A first light non-transmissive pattern, which comprises either one of the plurality of first polygonal pattern elements arranged in a matrix at regular intervals in the row direction, the column direction, and the diagonal direction, and the first light A second light opaque pattern consisting of a second polygonal pattern element interposed between the first polygonal pattern elements and forming a checkerboard pattern with the first polygonal pattern elements when superposed on the opaque pattern. An alignment mark device provided with is proposed.

In the description of the preferred embodiments of the present invention described below, 1) the first polygon pattern element and the second polygon pattern element are square pattern elements, and 2) the first light opaque pattern. Is provided with a light non-transmissive standard point mark indicating the center position of the first polygonal pattern element, and the second light non-transmissive pattern is located at a position corresponding to the standard point mark. It is described that a transparent removal region is formed by removing a part.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in detail below with reference to FIGS. 1A and 1B show an alignment mark device according to the present invention. FIG. 1A shows a wafer side alignment mark A formed on a wafer, and FIG. 1B shows a mask side alignment mark B formed on a mask. There is.

The wafer side alignment mark A shown in FIG. 1A is composed of first light opaque patterns a ₁ which are arranged in a matrix at intervals in the row direction, the column direction and the diagonal direction. That is, in the case of the illustrated example, although the first light non-transmissive patterns a ₁ are formed by the square pattern elements having the intervals “a” in the row direction and the column direction and one side “a”, In a preferred variant of the invention, the first light impermeable pattern a ₁ can also be embodied as another polygonal pattern element. In other words, the important point as the first light opaque pattern a ₁ is, as will be apparent from the following, the first light opaque pattern a 1.
₁ polygonal vertices and these first light opaque patterns a ₁
Since the difference in the visual distance between the polygonal vertices of the second light opaque pattern b ₁ (described later) corresponding to is utilized, there is no reason to be limited to the square pattern element.

At the center of the wafer side alignment mark A, about 1/2 of each side of the square pattern element is formed.
The standard point mark a ₂ is formed by the side of the length, and during the optical alignment between the wafer side alignment mark A and the mask side alignment mark B, which will be described later, the standard point mark a ₂ becomes the mask side alignment mark. It is located corresponding to the removal area b ₂ formed at the center of B.

FIG. 1B shows a mask side alignment mark B. The mask side alignment mark B is a second light opaque pattern b which is arranged in a matrix at intervals in the row direction, the column direction and the diagonal direction. Composed of ₁ . That is, in the case of the illustrated example, these second light opaque patterns b ₁
Like the first light non-transmissive pattern a ₁ , the second light non-transmissive pattern a ₁ is composed of square pattern elements having an interval of “a” in both the row direction and the column direction and having one side of “a”. The array position of the transmission pattern b ₁ is shifted by “a” in the row direction and the column direction with respect to the first light non-transmission pattern a ₁ . In other words, the second sequence position of the light opaque pattern b _1, as shown in FIG. 3, when combined with the first opaque pattern a ₁ of the wafer-side alignment mark A, the first opaque pattern a ₁ And a position which forms a checkerboard pattern, that is, the first light opaque pattern a _{1 at} the corresponding position is deviated by the pitch "a" in the row direction and the column direction.

Further, a removal area b ₂ formed by removing _one second light non-transmissive pattern b ₁ is formed in the central portion of the mask side alignment mark B, and the center of this removal area b ₂ is described above. since the corresponding reference point marks a ₂ that, as shown in FIG. 3, exact match of the first opaque pattern a ₁ 4 one around the same standard point mark a ₂ in the region b ₂ removes the The aligned state is the perfect alignment state.

Since the position according to the illustrated embodiment is configured as described above, the circuit pattern of the mask can be visually aligned with the circuit pattern of the wafer by the following steps.
That is, in the state where the mask-side alignment mark B is slightly deviated to the left with respect to the wafer-side alignment mark A, the first light opaque pattern a ₁ of the wafer-side alignment mark A and the second light-opaque pattern of the mask-side alignment mark B are The light opaque pattern b _{1 has} a relationship as shown in FIG. Therefore, the alignment state as shown in FIG. 3 can be obtained by finely adjusting the position of the wafer and / or the mask located in the alignment device in the left-right direction.

That is, in the completely aligned state of FIG. 3, four first light opaque patterns a ₁ having the standard point mark a ₂ at the center are formed inside the removal area b ₂ of the mask side alignment mark B. Is now inscribed,
You can visually check the rough alignment.
Then, in order to perform further fine adjustment of the wafer-side alignment mark A and / or the mask-side alignment mark B, each of the first light non-transmissive patterns a ₁ is completely moved in the diagonal direction of the second light non-transmissive pattern b ₁ . So as to be located, in other words, the second light opaque patterns a ₁
If the positions are corrected in the two-dimensional plane of the paper of FIG. 3, until the corresponding vertices of the light opaque pattern b ₁ match and the whole becomes a checkered pattern, a complete alignment state is achieved.

By the way, since the wafer-side alignment mark A formed on the surface of the wafer is formed by an etching method, it may be in a thick or thin state in the etching process. It can fully cope with such thick or thin lines. That is, FIG.
Although (a) is an example in which the first light non-transmissive pattern a ₁ is processed into a line thickened state slightly larger than the prescribed size, it may be brought into an aligned state as shown in FIG. 4 (b). This alignment operation is an operation for visually obtaining a state in which the corresponding vertices of the first light opaque pattern a ₁ and the vertices of the second light opaque pattern b ₁ are evenly overlapped with each other. The positioning operation is easy to check.

Also in the case where the first light non-transmissive pattern a _{1 is in} a line thin state, as shown in FIG. 5, the corresponding vertex of the first light non-transmissive pattern a ₁ and the vertex of the second light non-transmissive pattern b ₁ . Since the operation is only for visually obtaining a state in which the distance between and is evenly spaced, the positioning operation is easy to visually confirm.

[0023]

As is apparent from the above description, according to the present invention, the first light non-transmissive pattern of the wafer-side alignment mark and the second light non-transmissive pattern of the mask-side alignment mark formed of polygonal pattern elements. Since only fine adjustment of the wafer and / or the mask is required to form a checkerboard pattern with and, it is possible to perform the alignment operation efficiently without requiring skill. Further, according to the inventions of claims 2 and 3, since the first light non-transmissive pattern and the second light non-transmissive pattern are square pattern elements, they are located at the apexes of the corresponding first light non-transmissive patterns that are positioned in proximity to each other. It becomes easier to visually confirm the position of the apex of the second light non-transmissive pattern, and by forming the standard point mark and the removal area, the center of the mask-side alignment mark coincides with the center of the wafer-side alignment mark. There is an effect that it is easy to visually recognize whether or not it is.

[Brief description of drawings]

1A and 1B are plan views of a mask-side alignment mark and a wafer-side alignment mark used in an alignment mark device of the present invention.

FIG. 2 is a plan view of the alignment mark device when the alignment is defective.

FIG. 3 is a plan view of the alignment mark device during alignment.

4 (a) and 4 (b) are plan views of the same alignment mark device at the time of line thickening at the time of alignment failure and at the time of alignment.

FIG. 5 is a plan view at the time of alignment of the same alignment apparatus at the time of line thinning.

FIG. 6 is a conceptual diagram of a conventional reduction projection type exposure apparatus.

7A and 7B are plan views of a mask-side alignment mark and a wafer-side alignment mark used in a conventional alignment mark device.

FIG. 8 is a plan view of the alignment mark device when the alignment is defective.

FIG. 9 is a plan view of the alignment mark device during alignment.

10 (a) and 10 (b) are plan views of the same alignment mark device at the time of line thickening at the time of alignment failure and at the time of alignment.

FIG. 11 is a plan view of the same alignment apparatus at the time of line thinning during alignment.

[Explanation of symbols]

A Wafer side alignment mark a ₁ First light non-transmissive pattern a ₂ Standard point mark B Mask side alignment mark b ₁ Second light non-transmissive pattern b ₂ Removal area

Claims (3)

(57) [Claims] 1. A wafer-side alignment mark and a mask-side alignment mark that are used in an optically combined manner, wherein either one of the wafer-side alignment mark and the mask-side alignment mark is formed, and a row direction, a column direction, and a diagonal direction are formed. A first light non-transmissive pattern composed of a large number of first polygonal pattern elements arranged in a matrix at regular intervals in the direction, and between the first polygonal pattern elements when superposed on the first light non-transmissive pattern An alignment mark device comprising a second light opaque pattern formed of a second polygonal pattern element that forms a checkered pattern between the first polygonal pattern element and the first polygonal pattern element. 2. The alignment mark device according to claim 1, wherein the first polygon pattern element and the second polygon pattern element are square pattern elements. 3. The first light opaque pattern comprises a light opaque standard point mark indicating the center position of the first polygonal pattern element, and the second light opaque pattern corresponds to the standard point mark. 2. The alignment mark device according to claim 1, wherein a transparent removal region is formed by removing a part of the second polygonal pattern element at the defined position.