JPH0469408B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention reduces the moving distance of the wafer stage by rotating the wafer when exposing the wafer using an exposure device, more specifically, a stepper device, thereby reducing the size of the wafer stage. The present invention relates to a stepper device that improves the precision of its movement.

The technique of transferring a pattern onto a wafer using a lens allows batch exposure when the wafer size is about 5 cm (2 inches), and transfers exposure from the mask to the wafer on a one-to-one basis.

However, as the size of wafers increases and the demands for finer patterns become larger, batch exposure becomes impossible, and a method has been developed in which the entire wafer is divided into several parts and exposed stepwise.Currently, there is a method that exposes each chip one by one. It is taken.

[Conventional technology]

A reduction projection type exposure apparatus shown in FIG. 4 is used for the stepwise exposure described above, and in the same figure,
21 is an illumination optical system, 22 is a reticle, 23 is a condenser lens, 24 is a step monitor optical system, 2
5 is a reticle alignment optical system, 26 is a reticle alignment optical system;
ITV camera, 27 is a reduction projection lens, 28 is an autofocus detection system, 29 is an X-axis interferometer, 30
is a Y-axis interferometer, 31 is a wafer, 32 is a wafer alignment optical system, 33 is an XY stage, 34 is a reference mark, 35 is an ITV camera, and 36 is a He-Ne
A laser light source is shown. The XY stage 33 is a known stage movable in the X direction and the Y direction.

There are two alignment methods for reduction projection exposure equipment.
One is the off-axis method, and as shown in Figure 2, the reticle is positioned using the two
This is done using a book alignment optical system, and on the wafer side, there are three
Perform positioning using a book microscope. Thereafter, the stage on which the wafer is placed is moved, and the amount of movement is measured by a laser interferometer, and the wafer is sent to a predetermined exposure position.

Although the off-axis method can obtain good SN signals using a dedicated microscope, there are two problems. First, after the alignment is completed, the wafer must be moved to the exposure position, that is, the position of the optical axis of the projection lens. Although the amount of movement during that time was measured by a laser interferometer, the wafer 31
If there is yawing in the XY stage 33 on which it is mounted, an error that cannot be ignored will occur. to avoid this
Three microscopes, Wx, Wy, and WQ, are placed on the X and Y axes passing through the optical axis, respectively, and are designed to eliminate so-called Atsube's errors.

[Problem that the invention seeks to solve]

Current exposure equipment, especially stepper equipment, requires a moving distance equal to the diameter of the wafer, so as the diameter of the wafer becomes larger, the moving stage (XY stage) also becomes larger, reducing accuracy and reducing the overall length of the exposure equipment. There is a problem that the size of the

[Means for solving problems]

The present invention provides an exposure apparatus that solves the above-mentioned problems.The present invention provides an exposure apparatus that solves the above-mentioned problems. /Four…
...After exposing 1/n (where n is a positive integer) portion, the wafer is rotated by 1/2, 1/4...1/n by operating the wafer stage, respectively, and the above exposure is performed. This is performed using an exposure apparatus characterized in that the operation is repeated to expose the entire surface of the wafer.

[Effect]

The above-mentioned exposure apparatus, particularly the stepper apparatus, is used to expose a sample such as a wafer to 1/2, 1/4...1/n.
By rotating the wafer stage and reducing the movement of the stage in, for example, the X direction, the moving distance of the wafer stage is reduced, and the XY stage is made smaller and more precise.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

The present invention takes advantage of the fact that the stepper device exposes chips one by one, and during exposure, rotates the wafer by 1/2, 1/4... to reduce the travel distance of the wafer stage. For that purpose, the XY stage 33 is rotated 1/2, 1/4...

An embodiment in which the wafer is rotated by 1/2 will be described with reference to FIG.

First, as shown in FIG. 1a, the upper half of the wafer 31 is exposed. For this purpose, the wafer stage starts from chip 31a at the left end of the top row in the figure.
Move in the X direction by chips and move to the rightmost chip 3
Expose 1m. In addition, in the drawings, the chip is schematically shown with large dimensions for the sake of simplification.

Next, it moves one chip in the Y direction from the chip 31m, and moves in the X direction opposite to the previous one. Alternatively, it may be moved to the tip below tip 31a and moved in the X direction in the same manner as described at the beginning.

When the exposure of the upper half of the wafer is completed in the manner described above, the wafer 31 is rotated 1/2 and the image shown in FIG.
Expose the remaining half as shown in . According to this exposure method, the wafer stage moves in the X direction by the diameter of the wafer, but only needs to move in the Y direction by a distance that is half the diameter of the wafer.

An example of rotating the wafer by 1/4 is shown in Figure 2. First, as shown in Figure a, the upper left quarter of the wafer is
The wafer is exposed from chips 41a to 41n, and then the wafer is rotated 1/4 and the fourth chip is exposed as shown in FIG.
Expose the lower 1/4 of the area exposed in figure a as before, then the next 1/4 as shown in figure c.
Then, finally, the remaining 1/4 part is exposed as shown in d of the same figure. In this example, the wafer stage only needs to move a distance of half the diameter of the wafer in the X and Y directions. In FIG. 2 as well, the chip is schematically illustrated with larger dimensions.

In the embodiment shown in FIG. 3, first, the radially outermost chip 51a of the wafer is exposed, as shown in FIG. 3a. Next, the wafer is rotated 1/n, and the outermost chip 52a in the radial direction of the wafer is exposed as shown in FIG. Chip 51 located directly below
b is exposed, and the above-described exposure is sequentially repeated up to the vicinity of the center of the wafer.

Alternatively, the same operations as described above may be repeated, starting from the chip closest to the center of the wafer in the radial direction of the wafer. It is appropriate to choose whether to start exposure from the outside or near the center of the wafer, but it is preferable to change the rotation of the wafer as appropriate near the center of the wafer.

By doing this, the movement of the wafer stage in the X direction is half the wafer diameter or zero,
Since the movement in the Y direction is reduced to half the wafer diameter, equipment miniaturization is achieved, reducing cost and increasing accuracy.

The above was an example of wafer exposure, but
The scope of application of the present invention is not limited to that case, but can also be applied to inspection devices and the like.

〔Effect of the invention〕

As explained above, according to the present invention, when operating a wafer stage for exposure or inspection purposes, the stage can be moved in the X direction by rotating the wafer by 1/2, 1/4...1/n. Since the movement in the Y direction is reduced to 1/2 or 0 of the wafer diameter, and the movement in the Y direction is reduced to 1/2 of the wafer diameter, this is very effective in reducing the size of the device and increasing precision.

[Brief explanation of drawings]

Figure 1 a, b, Figure 2 a to d, Figure 3 a,
4b is a plan view showing the rotation of a wafer according to the present invention, and FIG. 4 is a layout diagram of a conventional reduction exposure apparatus. In the figure, 31 is a wafer, 33 is an XY stage, 31a...31m, 41a...41n, 51
a, 51b, 52a, and 52b indicate chips, respectively.

Claims (1)

[Claims] 1 After exposing 1/2, 1/4...1/n (where n is a positive integer) of the wafer by moving the wafer stage on which the wafer is placed in the XY directions, operate the wafer stage to remove the wafer. 1/2 and 1/4 respectively
An exposure apparatus characterized by having a configuration in which the above-described exposure is performed by rotating the wafer by 1/n, and the above operation is then repeated to expose the entire surface of the wafer.