JPH0521317A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable easy and inexpensive formation by a simple means and to realize highly accurate mask alignment. CONSTITUTION:A mask alignment pattern 7 which consists of a light nontransmitting film to alignment light B is formed on a surface 1a of a wafer 1, and positioning of the wafer 1 and the mask 52 is carried out based on the pattern 7 when performing mask alignment for a rear 1b thereof. Since mask alignment of the rear 1b of the wafer 1 is carried out by the mask 52 which is set in a front 1a of the wafer 1, transcription by using an exposure device of one-side mask alignment becomes possible and a cost of a semiconductor device is reduced. Furthermore, since mask alignment of front and rear 1a, 1b of the wafer 1 is carried out based on the same mask alignment pattern 7, it is possible to realize highly accurate mask alignment and to form the pattern 7 readily.

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 with improved alignment (mask alignment) between a mask used for pattern transfer in a photolithography method and a semiconductor wafer.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor elements such as LSI, a high-resolution optical projection exposure machine is widely used. When transferring using this exposure machine, the mask and the semiconductor wafer are exposed before exposure. It is necessary to perform mask alignment with. As a method of this mask alignment, an optical system different from the projection optical system detects the pattern on the wafer,
After the positioning is performed, the wafer is moved to a predetermined position within the field of view of the projection optical system to align the mask with the already positioned mask, and the alignment pattern previously formed on the mask and the wafer. Is detected through a projection optical system, and the mask and the wafer are directly aligned with each other.

However, the former method has the advantage that the number of times of mask alignment is small, but on the other hand, since it is necessary to move the aligned wafer to the transfer position, it is difficult to perform highly accurate mask alignment. In recent years, the latter method tends to be adopted. Also,
In order to form a semiconductor layer on the front and back surfaces of a wafer along with high-density integration of semiconductor elements, an optical projection exposure machine of a type in which individual masks are set on the front and back surfaces of the wafer to perform mask alignment is used. ing.

[0004]

However, when the transfer is performed by using such a double-sided mask alignment exposure machine, the semiconductor integrated circuit itself becomes expensive.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing a semiconductor device which can be formed easily and inexpensively by a simple means and which can perform highly accurate mask alignment. I am trying.

[0006]

A method of manufacturing a semiconductor device according to the present invention comprises a step of forming a mask alignment pattern made of a non-transparent film on the surface of a wafer against alignment light, and the above-mentioned pattern as a reference. The step of aligning the mask with the mask set on the front surface side of the wafer, the step of reversing the front and back surfaces of the wafer so that the back surface faces the mask, and the step of reversing the front and back surfaces of the wafer and the mask And a step of performing alignment based on the pattern.

[0007]

According to the above manufacturing method, since the mask alignment on the front and back surfaces of the wafer is performed with the mask set on the front surface side of the wafer, it is possible to perform the transfer using the exposure machine for the single-sided mask alignment. As a result, the semiconductor integrated circuit manufactured by itself becomes inexpensive. Also,
Since the mask alignment on the front and back surfaces of the wafer is performed with reference to the same mask alignment pattern formed on the front surface of the wafer, the alignment between the front and back surfaces of the wafer with the mask is achieved with high accuracy. .. Moreover, since the mask alignment pattern only needs to be formed on one surface of the wafer, the pattern can be easily formed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view for explaining a manufacturing method for forming a mask alignment pattern on a surface of a wafer according to an embodiment of the present invention. As shown in FIG. 1A, for example, a semiconductor wafer 1 made of silicon Si
On the surface 1a of Yotsute to be oxidized to the insulating layer 2 made of silicon dioxide (SiO ₂₎ is deposited and formed. Next, as shown in FIG. 2B, a photoresist film (photosensitive coating) 3 is deposited on the surface of the insulating layer 2, and then, as shown in FIG. A mask 5 on which the working pattern 4 is formed is arranged oppositely, and the photoresist film 3 is irradiated with an activating light ray A such as ultraviolet rays through the mask 5. By this irradiation of the light ray A, the exposed portion 3a and the unexposed portion 3 of the photoresist film 3 are exposed.
b, the exposed portion 3a is fixed, and the unexposed portion 3b is washed to form a desired etching pattern on the photoresist film 3 as shown in FIG. A tangled opening 3c is formed.

In the next etching step shown in FIG. 2 (e), the corrosion resistance to the photoresist film 3 and the corrosion of the insulating layer 3 can be obtained. When the etching solution is used, the insulating layer 2 in the portion corresponding to the small holes 3c of the photoresist film 3 is etched, and the small holes 2a are formed in the insulating layer 2. After that, the photoresist film 3 is removed by a solvent, and the insulating layer 2 having the small holes 2a is deposited on the surface of the semiconductor wafer 1 as shown in FIG. Further, on the exposed surface of the semiconductor wafer 1 and the surface of the insulating layer 2, a non-translucent film 6 made of, for example, aluminum (Al) is deposited as shown in FIG. The insulating layer 2 on the wafer 1 is removed by a corrosive treatment with hydrofluoric acid or other suitable means, and as shown in FIG. 1H, a mask alignment pattern 7 is formed on the surface 1a of the semiconductor wafer 1. Are deposited and formed.

FIG. 2 is a cross-sectional view for explaining an example of a manufacturing process in which a film is formed on the surface of the wafer and etched in the post-process of FIG. As shown in FIG.
Insulating layer 21 made of silicon dioxide on the surface 1a of the (SiO ₂₎
Is deposited and a photoresist film 31 is deposited on the surface thereof as shown in FIG. 2 (b). Then, as shown in FIG. 2 (c), an etching mask 51 is formed on the surface 1a of the wafer 1. Exposure and development are performed in alignment with the alignment pattern 7. This is washed to form a photoresist film 31 having a desired etching pattern as shown in FIG.

In the next etching step shown in FIG. 3E, the insulating layer 21 is corroded through the small holes 31a of the photoresist film 31, and then the photoresist film 31 is etched.
After removing, the insulating layer 21 having the small holes 21a is deposited on the surface of the semiconductor wafer 1 as shown in FIG.

FIG. 3 is a sectional view for explaining an example of a manufacturing process in which a film is formed on the back surface of the wafer and etched in the post-process of FIG. As shown in FIG.
By reversing the front and back surfaces of, after the silicon dioxide on the back surface 1b of the insulating layer 22 made of (SiO ₂₎ was deposited and formed, with the photoresist film 32 on the rear surface deposited as shown in FIG. (B), As shown in FIG. 3C, the etching mask 52 is used as the mask alignment pattern 7 on the back surface 1 b of the wafer 1.
Align with and expose and develop.

At the time of the above alignment, the alignment light B
Infrared light or laser light is used as the light. Although these lights are transmitted through the wafer 1, they are not transmitted through aluminum (Al) forming the pattern 7, so that the mask 52 and the wafer 1 are properly aligned. be able to. After that, as shown in FIG. 7E, the insulating layer 22 is corroded through the small holes of the photoresist film 32, and then the photoresist film 32 is removed. Then, as shown in FIG. Insulating layer 22 having small holes 22a on the back surface 1b
Are deposited and formed.

As described above, the insulating layers 21 and 22 are formed on the front and back surfaces 1a and 1b of the semiconductor wafer 1, and when impurities are injected from the small holes 21a and 22a of these insulating layers 21 and 22, respectively, Front and back surfaces 1a, 1 of the semiconductor wafer 1
The semiconductor layers 8 and 9 are formed in b, and the semiconductor device as shown in FIG. 4 is manufactured.

According to the above manufacturing method, the mask alignment of the front and back surfaces 1a and 1b of the wafer 1 is performed with the masks 51 and 52 set on the front surface 1a side of the wafer 1. Can be used for transfer, and the semiconductor integrated circuit itself manufactured by this can be inexpensive. Further, since the mask alignment of the front and back surfaces 1a and 1b of the wafer 1 is performed with the same mask alignment pattern 7 formed on the front surface 1a of the wafer 1 as a reference, the wafer 1
Alignment with the masks 51 and 52 on the front and back surfaces of is achieved with high accuracy. Moreover, since the mask alignment pattern 7 only needs to be formed on one surface of the wafer 1, it is easy to form the pattern.

[0016]

As described above, according to the manufacturing method of the present invention, the mask alignment can be performed easily and inexpensively by simple means, and highly accurate mask alignment can be performed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a manufacturing method for forming a mask alignment pattern on a surface of a wafer according to an embodiment of the present invention.

2 is a cross-sectional view illustrating an example of a manufacturing process in which a film is formed on the surface of the wafer in the post-process of FIG. 1 and etched.

FIG. 3 is a cross-sectional view illustrating an example of a manufacturing process in which a film is formed on the back surface of the wafer and etched in the post-process of FIG.

FIG. 4 is a cross-sectional view showing an example of a semiconductor device in which a semiconductor layer is formed on the front and back surfaces of the wafer in the post process of FIG.

[Explanation of symbols]

 1 wafer 1a front surface 1b back surface 7 mask alignment pattern 51, 52 mask B alignment light

Claims (1)

Claim: What is claimed is: 1. A step of forming a mask alignment pattern made of a non-translucent film on the surface of a wafer against alignment light, and a step of setting the pattern on the surface side of the wafer with the pattern as a reference. The step of aligning with the mask, the step of reversing the front and back surfaces of the wafer so that the back surface faces the mask, and the reversal of the front and back surfaces of the wafer and the mask with reference to the pattern A method of manufacturing a semiconductor device, comprising the steps of: