JPH02278814A - Exposure of wafer - Google Patents

Abstract

PURPOSE:To accurately decide an exposure position at a peripheral edge part of a wafer, to increase the number of chips available from the wafer and to prevent a wrong chip from being taken by a method wherein a virtual net which uses a unit rectangle as a mesh is put on the whole surface of the wafer, each mesh which is overlapped with the peripheral edge part of the wafer is exposed and the peripheral edge part of the water is exposed. CONSTITUTION:A position of a wafer 1 where a resist film has been formed on the whole surface is decided; after that, the wafer is moved in a step manner by a size of a unit rectangle by using an X-direction linear pulse motor 64 and a Y-direction linear pulse motor 65; only parts where a peripheral edge part of the wafer is included in unit rectangles are exposed. After that, a developing operation is executed; the resist film of the unit rectangles including the peripheral edge part of the wafer is removed. A region of the wafer where the resist film remaining at the inside is a region which can be used as chips. Thereby, an exposure position at the peripheral edge part of the wafer is decided accurately; the number of chips which are available from one wafer can be increased; it is possible to prevent a wrong chip from being taken at a die bonding operation or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a method of exposing a wafer, and particularly to a method of exposing a peripheral portion of a wafer.

The purpose is to accurately determine the peripheral edge exposure position to increase the number of chips that can be taken from one wafer, and to determine the position of the chips on the wafer.

(1) In a wafer exposure method that exposes the peripheral edge of a wafer on which a resist film is formed on the entire surface, a unit rectangle is determined as the minimum exposure area, and a virtual mesh is created over the entire surface of the wafer using the unit rectangle as a mesh. [2] A wafer exposure method that exposes the entire periphery of the wafer by exposing meshes that overlap with the periphery of the wafer mesh by mesh, and [2] the periphery of the wafer with a resist film formed on the entire surface. In a wafer exposure method in which a unit rectangle is defined as the minimum exposure area, and a virtual mesh having the unit rectangle as a mesh is applied to the entire surface of the wafer, the virtual mesh passing through approximately the center of the wafer is The point where the two orthogonal virtual threads intersect with the peripheral edge of the wafer is set as a position confirmation point, and the meshes that overlap with the peripheral edge of the wafer are exposed mesh by mesh, excluding the meshes on both sides of the position confirmation point, The meshes on both sides of the position confirmation point are formed by a wafer exposure method in which an unexposed area including the position confirmation point is formed by moving the meshes on both sides of the position confirmation point and exposing them.

[Industrial application field]

The present invention relates to a method for exposing a wafer, and more particularly to a method for exposing a peripheral portion of a wafer.

In a semiconductor photo process, it is necessary to remove the resist from the periphery of the wafer after forming a resist film over the entire surface of the wafer. The resist coating is usually thicker at the wafer periphery, and some of it may peel off during subsequent steps. Further, when the wafer is stored in the carrier, the peripheral edge of the wafer comes into contact with the groove of the carrier, and the resist in that area may peel off. The peeled resist becomes dust and interferes with subsequent processes. For this reason, after forming a resist film over the entire surface of the wafer, the resist at the periphery of the wafer is removed.

Moreover, in the manufacture of integrated circuits, it is also required to increase the number of chips that can be obtained from one wafer by minimizing the area from which resist is removed at the periphery of the wafer.

Furthermore, when chips are taken from a wafer on which a large number of chips on which device formation has been completed are placed and bonded to a Guibad, it is also required to prevent mix-ups of chips.

[Conventional technology]

Conventionally, as one of the methods for removing the resist at the periphery of a wafer, there is a method as shown in the conventional example (2) in FIG. Fifth
In the figure, l represents a wafer having a resist film formed on its entire surface, 61 represents a wafer stage, 62 represents a rotation motor, 63 represents a stand, and 66 represents an optical lens system forming a part of the n-light device.

In this method, a roughly circular wafer l is rotated around a central axis, and a certain width from the wafer periphery is exposed to light by an optical lens system 66, thereby removing the resist at the wafer periphery. However, due to variations in wafer dimensions and the fact that the shape of chips to be taken from the wafer in the future is rectangular, if the accuracy of wafer positioning is poor, chips near the wafer edge may be placed in later processes. There were problems such as defects occurring and the position of the chips on the wafer not being accurately determined.

There is also an exposure apparatus that does not automatically detect the position of the wafer's periphery and exposes a certain width from the wafer's periphery. Conventional example ■ in FIG. 6 is a diagram for explaining this, and l is a wafer 261 on which a resist film is formed on the entire surface, a wafer stage,
62 is a rotation motor, 63 is a stand, and 66 is an optical lens system forming a part of the exposure device.

67 represents a light emitting system, 68 represents a light receiving system, and 81 represents a moving stage.

In this device, when the shape of the wafer slightly deviates from a circle, the amount of light entering the light receiving system 68 changes, and the amount of change is fed back to the moving stage 81 to move the moving stage 81, so that the peripheral edge of the wafer is always kept at a constant level. It is designed to expose in width.

According to this device, the resist on the wafer edge is removed uniformly with a certain width, which solves the problem of the resist peeling off on the wafer edge and becoming dust, but this device also allows for variations in wafer dimensions. If this occurs, there are problems such as defects occurring in chips near the wafer periphery in later steps or the position of the chips on the wafer not being accurately determined.

[Problem to be solved by the invention]

In view of two or more drawbacks of the conventional method, the present invention solves the problem of resist peeling off at the wafer edge and becoming dust, and
The edge exposure position is precisely determined to prevent defects even in chips near the wafer edge.

Increasing the number of chips that can be obtained from one wafer,
The purpose is to determine the position of chips on a wafer and prevent mix-ups of chips during die bonding, etc.

[Means to solve the problem]

FIG. 1 is a diagram explaining the principle of the present invention. FIG. 1(a) shows a method of exposing the entire wafer periphery, and FIG. 1(b) shows an unexposed area on a part of the wafer periphery for position confirmation. FIG. 4 is a diagram for explaining a method of exposing all the peripheral parts except for the periphery.

In FIGS. 1(a) and (b), ■ is a wafer with a resist film formed on the entire surface, 11 is the periphery of the wafer, 2 is a virtual mesh, 21 is a mesh that overlaps the wafer's periphery, and 22 is a position confirmation. Mesh on both sides of the point, 31.32 is virtual thread, 41
．． 42 represents a position confirmation point, and 51.52 represents an unexposed area.

[1] In a wafer exposure method that exposes the peripheral edge 11 of a wafer 1 on which a resist film is formed on the entire surface, a unit rectangle is determined to be the minimum exposure area, and 6 the unit rectangle is spread over the entire surface of the wafer. A wafer exposure method in which the entire peripheral edge 11 of the wafer 1 is exposed by exposing each mesh 21 that overlaps the peripheral edge 11 of the wafer 1 to light when a virtual 'yI2 as a mesh is applied; 2] In a wafer exposure method that exposes the peripheral portion 11 of the wafer 1 on which a resist film is formed on the entire surface.

When a unit rectangle serving as the minimum exposure area is determined and a virtual mesh 2 with the unit rectangle as a mesh is applied over the entire surface of the wafer,
The point where the two orthogonal virtual threads 31.32 of the virtual network 2 passing through the approximate center of the wafer 1 intersect the peripheral edge 11 of the wafer 1 is defined as a position confirmation point 41.42, and the position confirmation point 41
．． The peripheral edge 11 of the wafer 1 except for the meshes 22 on both sides of the wafer 42
The meshes 21 that overlap with each other are exposed mesh by mesh, and the position confirmation point 41 is
．． A wafer exposure method in which the meshes 22 on both sides of 42 are moved to both sides of the position confirmation point 41.42 and exposed, thereby forming an unexposed area 51.52 including the position confirmation point 41.42. solved by.

[Effect]

In the present invention, first, a unit rectangle that is the minimum exposure area is determined. This unit rectangle corresponds to the shape of the chip to be taken in the future from the wafer.

If a virtual network with meshes of this unit rectangle is applied over the entire surface of the wafer, the area inside the wafer corresponding to the network is an area that can be used for chips in the future.

The area including the wafer periphery that overlaps with the mesh cannot be used as a chip. If the portion of the mesh that overlaps the wafer periphery is exposed to light and the resist film in that portion is removed, the problem that the resist film on the wafer periphery is peeled off in subsequent steps and has an adverse effect is eliminated.

Further, the positions of chips to be taken in the future can be determined by a virtual network having unit rectangles as meshes, and the number of chips that can be used as chips can be maximized.

Furthermore, by setting one position confirmation point and forming an unexposed area that includes that point, the position where chips should be formed on the wafer alone can be determined even if the dimensions vary from wafer to wafer.
The position of the chips within the wafer is determined, and there is no possibility of mixing up chips during die bonding, for example.

The exposure for each mesh of the virtual mesh is 2, for example, the wafer is exposed in the X direction and
Place it on an X-Y stage that moves in the direction, align the directions of both sides of the unit rectangle with the
This is achieved by moving stepwise in units of unit rectangular dimensions and exposing.

The position confirmation points are for determining the Y-axis passing through the center of the wafer and the Y-axis, but since the nominal dimensions of the wafer and chips are known in advance, the positions can be set in advance.

〔Example〕

An embodiment of the present invention will be described below.

FIG. 4 is a diagram for explaining an apparatus for carrying out the present invention. FIG. 4(a) shows a step movement a structure, and FIG. 4(b)
) is a diagram for explaining the arrangement of sensors.

In FIGS. 4(a) and (b), 1 is a wafer with a resist film formed on the entire surface, 61 is a wafer stage, and 62
63 is a rotation motor, 63 is a stand, 64 is an X-direction linear pulse motor, 65 is an X-direction linear pulse motor, 66 is an optical lens system, and 71, 72, and 73 are sensors.

The wafer l is fixed to the wafer stage 61 by vacuum suction. The wafer stage 61 is rotated by a rotation motor 62, and the wafer stage 61 is rotated in the X direction by an X direction linear pulse motor 64.

It moves in the X direction by the X direction linear pulse motor 65.

The wafer l is moved by the rotation motor 62 and the linear pulse aperture 4.65, and the position of the wafer l is determined by sensors 71, 72, and 73 set in advance according to the number of inches of the wafer.

The sensor is, for example, a photosensor, which detects when the peripheral edge of the wafer has reached that position. For example, the sensors 71 and 72 are arranged so that the orientation flat of the wafer 1 is aligned with the X direction, and the sensor 73 is arranged so that the X direction passes through the center of the wafer 1.

After determining the position of the wafer 1 in this way.

The wafer is moved by an X-direction linear pulse motor 64. The X-direction linear pulse motor 65 moves the wafer stepwise by the size of the unit rectangle, and only the area where the peripheral edge of the wafer falls within the unit rectangle is exposed.

FIG. 2 shows Example 2, in which the entire unit rectangle including the peripheral edge of a 6-inch wafer was exposed. In FIG. 2, l represents a wafer on which a resist film is formed on the entire surface, 11 represents the peripheral edge of the wafer, and 21 represents a mesh that overlaps the peripheral edge of the wafer.

First, the dimensions of the unit rectangle are 5 mm both in length and width.

The position of the peripheral edge to be exposed is determined in accordance with the nominal dimensions of the 6-inch wafer. The dimensions of the unit rectangle are.

This corresponds to the size of a chip cut out after element formation.

Next, exposure is started from the position of the orientation flat, for example, and the wafer is exposed by moving the wafer five times one after another by the length or width of the unit rectangle, thereby exposing the entire circumference of the wafer.

Thereafter, the unit rectangular resist film including the periphery of the wafer is removed by development. The wafer area where the resist film remains inside is an area that can be used as a chip.

FIG. 3 is an example (2) in which an unexposed area for position confirmation was left in a part of the periphery of a 6-inch wafer, and the entire unit rectangle including the other periphery was exposed. In Figure 3,
1 is a wafer on which a resist film is formed on the entire surface; 11 is a peripheral edge of the wafer; 21 is a mesh that overlaps with the peripheral edge of the wafer; 4
1.42 is the location confirmation point.

22 represents mesh on both sides of the position confirmation point, and 5L 52 represents an unexposed area.

First, the internal center of the 6-inch wafer according to its nominal dimensions is determined using the sensors 71 to 73 described above. With the center as a reference, position confirmation points 41 and 42 in the X direction and in the X direction for forming an unexposed area are given in advance. The dimensions of the unit rectangle are 5 mm both in length and width.

The position of the peripheral edge to be exposed is determined in accordance with the nominal dimensions of the 6-inch wafer. The dimensions of the unit rectangle are.

Corresponds to the dimensions of the chip.

The meshes on both sides of the position confirmation points 41 and 42 are removed, and the meshes that overlap the wafer peripheral edge 11 are exposed.

The mesh on both sides of the position confirmation point 41 has one position confirmation point 4 in the X direction.
The meshes on both sides of 2 are 1m apart from each other in the X direction.
After moving by l1l, the mesh is exposed.

After exposure and development, a resist with a width of 2 mm remains in an unexposed area 51.52 including the reference confirmation point 41.42.

This resist residue can be used in later steps to confirm the center position of the wafer and determine the position of the chips on the wafer.

In particular, when elements are formed on chips on a wafer and chips are selected from the wafer for die bonding, the center position can be confirmed, so chips with coordinates assigned to one position can be selected without fail.

Even though it is a nominally 6-inch wafer, there is variation in one dimension, but the variation is usually about plus or minus 1 mm, so the dimensions of the unit rectangle are 5IIIIIIl both vertically and horizontally.
There is no problem in practice even if the peripheral portion to be exposed to light is set in advance at a nominal value. For safety, you can also set a margin.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to accurately determine the exposure position on the wafer periphery, increase the number of chips that can be taken from one wafer, and prevent mix-up of chips during die bonding etc. can be prevented.

The present invention is particularly effective in large wafers with a large number of chips, and greatly contributes to the manufacture of integrated circuits.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention. FIG. 1(a) shows the case where the entire periphery of the wafer is exposed, and FIG. 1(b) shows the case where an unexposed area is left at the periphery of the wafer. FIG. 2 is a diagram for explaining Example I. FIG. 3 is a diagram for explaining embodiment (2). FIG. 4 is a diagram for explaining an apparatus for carrying out the present invention,
FIG. 4(a) shows the step movement mechanism, and FIG. 4(b) shows the arrangement of the sensors. FIG. 5 is a diagram for explaining conventional example (2). FIG. 6 is a diagram for explaining conventional example (2). In fig. ■ is a wafer with a resist film formed on its entire surface. 11 is the periphery of the wafer. 2 is a virtual network. 21 is a mesh that overlaps the periphery of the wafer. 22 is the mesh on both sides of the position confirmation point. 31 and 32 are virtual threads forming a virtual network. 41 and 42 are position confirmation points. 51 and 52 are unexposed areas. 61 is the wafer stage. 62 is a rotation motor. 63 is the stand. 64 is a linear pulse smoke in the X direction. 65 is a linear pulse motor 1 in the Y direction, and 66 is an optical lens system. 67 is a light emitting system. 68 is the light receiving system. 71 to 73 are sensors. 81 is the f-hyperactive stage (a) ↑So Sun Moon's Moon 5 ¥ Theory B Moon Picture Man 6 Picture (f 1) + Shi+ Fute14's R theory Rou Picture Man I Picture (Part 2) Ichika

Claims (1)

[Scope of Claims] [1] In a wafer exposure method in which a peripheral portion (11) of a wafer (1) on which a resist film is formed on the entire surface is exposed, a unit rectangle serving as the minimum exposure area is determined, and the entire surface of the wafer is exposed. When a virtual mesh (2) having the unit rectangle as a mesh is applied to the wafer (1), a mesh (21
) is exposed mesh by mesh to expose the peripheral edge (11) of the wafer (1).
) A wafer exposure method characterized by exposing the entire wafer. [2] In a wafer exposure method that exposes the peripheral edge (11) of a wafer (1) on which a resist film is formed on the entire surface, a unit rectangle is determined to be the minimum exposure area, and the unit rectangle is patterned over the entire surface of the wafer. When a virtual net (2) is applied to the wafer (1), two orthogonal virtual threads (31, 32) of the virtual net (2) passing through approximately the center of the wafer (1) are located at the periphery of the wafer (1). The point that intersects the part (11) is the position confirmation point (41, 42).
), and the meshes (
The meshes (21) that overlap with the peripheral edge (11) of the wafer (1) except for the position confirmation points (41, 22) are exposed mesh by mesh.
The meshes (22) on both sides of the position confirmation points (41, 4)
2), the unexposed area (51) including the position confirmation points (41, 42) is exposed.
, 52).