JPH04111339A - Stage for semiconductor wafer - Google Patents

Abstract

PURPOSE:To detect a distortion in a semiconductor wafer so as to prevent the occurrence of defocusing and measurement errors caused by the distortion by providing numerous through holes through a stage main body from its semiconductor wafer placing face and a light reflecting type distance measuring instrument to the through holes. CONSTITUTION:Optical fibers 12 are inserted into through holes 13 formed through a stage main body 3 in vertical direction from the wafer placing face 3a of the main body 3. When a wafer 1 is attracted by suction to the main body 3 in a distorted state due to a foreign matter 8 between the wafer 1 and face 3a, the quantity of the reflecting light from the wafer 1 made incident to a light receiving section 15 through the fiber 12 facing the distorted part increases. A light reflecting type distance measuring instrument main body 11 detects the increase in light quantity and, when the distance from the rear surface of the wafer 1 to the leading end of the optical fiber 12 is larger than a specific value, generates an alarm. When this stage is used, therefore, the distortion in the wafer 1 can be detected and the foreign matter 8 can be removed before the wafer 1 is subjected to an exposing process, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor wafer stage that attracts and holds a semiconductor wafer on a wafer mounting surface.

[Conventional technology]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing apparatus such as a wafer exposure apparatus, a semiconductor wafer is placed on a stage and exposed to light. A conventional stage of this type will be explained with reference to FIGS. 5 and 6.

FIG. 5 is a cross-sectional view showing a part of a conventional semiconductor wafer stage, in which a semiconductor wafer is attracted. FIG. 6 is a plan view of a conventional semiconductor wafer stage in which a wafer is attracted. In these figures, 1 is a semiconductor wafer (hereinafter simply referred to as a wafer), 2 is
is a stage on which this wafer 1 is attracted. The stage 2 includes a stage body 3 on which the wafer 1 is placed, and a boss portion 4 connected to a vacuum suction device (not shown). is formed. This wafer mounting surface 3a is formed with high precision so that the flatness of the wafer 1 will not decrease when the wafer 1 is mounted. Also, this stage 2
A vacuum suction hole 5 communicating with a vacuum suction device is bored through the boss portion 4 and the stage body 3.

The vacuum suction hole 5 communicates with a suction groove 6 opened in the wafer placement surface 3a, and the vacuum suction device suctions air from the vacuum suction hole 5 to vacuum suction the wafer 1 onto the wafer placement surface 3a. It is configured so that it can be Note that 7 indicates a semiconductor shot chip formed on the wafer 1.

In the conventional stage 2 configured in this manner, the wafer 1 is vacuum-adsorbed onto the wafer mounting surface 3a of the stage main body 3, and the wafer 1 is exposed in this state.

[Problem to be solved by the invention]

However, in the conventional stage 2, if foreign matter adheres to the wafer mounting surface 3a when vacuum suctioning the wafer 1, the wafer 1 is distorted by the foreign matter as shown in FIG. 5, and the flatness in the suction state is affected. will decrease. In addition, in FIG. 5, 8 indicates a foreign substance attached to the wafer mounting surface 3a, and A
indicates the distortion dimension of the wafer 1 caused by the foreign matter 8 being sandwiched between the wafer mounting surface 3a and the wafer 1.

When the wafer 1 is distorted in this way, a stepper or the like is used to measure the line width.
Defocus occurs during measurement of pattern overlay, etc., and semiconductor chips formed in areas where this defocus occurs will be defective.

The range of this out-of-focus area is shown in Figure 6.
Indicated by

[Means to solve the problem]

The semiconductor wafer stage according to the present invention has a stage main body with a large number of through holes opening to the semiconductor wafer mounting surface,
These through holes are equipped with light reflection type distance measuring devices that measure the dimensions to the back surface of the semiconductor wafer on the stage body by reflecting light onto the back surface of the semiconductor wafer.

[For production]

It is detected that the semiconductor wafer is distorted when the distance between the back surface of the semiconductor wafer and the light reflection type distance measuring device becomes larger than a set value.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4.

FIG. 1 is a sectional view showing an enlarged main part of a semiconductor wafer stage according to the present invention, FIG. 2 is a plan view of the semiconductor wafer stage according to the present invention, and FIG. 3 is a semiconductor wafer stage according to the present invention. FIG. 4 is a cross-sectional view showing an enlarged view of the sensor of a light reflection type distance measuring device used in the present invention, and FIG. 4 is a graph showing the relationship between the amount of reflected light and the gap distance when the light reflection type distance measuring device is used. In these figures, the above-mentioned figures 5 and 6
For parts that are the same or equivalent to those explained in the figures,
The same reference numerals are given and detailed explanation is omitted. In these figures, 11 is the main body of the light reflection type distance measuring device, 12 is an optical fiber as a sensor of the main body of the light reflection type distance measuring device,
The light reflection distance measuring device main body 11 and the optical fiber 12 constitute a light reflecting distance measuring device. The optical fiber 12 is installed in a through hole 13 formed in the stage body 3. This through hole 13 is located on the wafer mounting surface 3.
A hole is formed vertically through the stage main body 3 so as to open at the wafer mounting surface 3.
It is provided over the entire surface of a.

In this embodiment, the through hole 13 is formed at the second position.
As shown in the figure, the through holes 13 are set to correspond to the folds drawn by imaginary lines on the wafer mounting surface 3a, and the through holes 13 are arranged in parallel at equal intervals.

This interval is set to 5 to 10 m. Further, in this embodiment, the through hole 13 is communicated with a vacuum suction device, and the wafer 1 is vacuum suctioned onto the wafer mounting surface 3a by suctioning air through the through hole 13.

As shown in FIG. 3, the optical fiber 12 is provided with a light emitting section 14 that radiates light onto the back surface of the wafer 1 at the center in the radial direction, and a light emitting section 14 that irradiates light onto the back surface of the wafer 1 on the outside of the light emitting section 14.
A light receiving section 15 is provided into which light reflected from the back surface of the light receiving section 15 is incident. The optical fiber 12 is installed in the through hole 13 with its tip separated from the wafer placement surface 3a by about 0.1 to 0.3 μm, and is connected to the light reflection distance measuring device main body 11. There is. Note that 16 in FIG. 3 indicates wafer 1.
Shows the reflected light reflected from the back surface of

The light reflection distance measuring device main body 11 measures the distance (gap distance) from the back surface of the wafer 1 to the tip of the optical fiber 12 based on the intensity of light received by the light receiving section 15 (the amount of light reflected on the back surface of the wafer 1). However, if this distance exceeds a standard value (for example, 0.5 μm) that allows distortion of the wafer 1, an alarm is generated. That is, as shown in FIG. 4, the amount of reflected light incident on the light receiving section 15 increases in proportion to the gap distance, so that distortion occurs in the portion of the wafer 1 facing the optical fiber 12. If the gap distance becomes longer due to a change in the distance, the amount of the reflected light increases by that amount.

The light reflection distance measuring device main body 11 has a structure that measures the gap distance from the amount of reflected light. Note that the middle part of FIG. 4 shows the gap distance (for example, 0.3 μm) when the wafer 1 without distortion is attracted to the stage 2.

In the stage 2 on which the optical fiber 12 is attached in this way, when the wafer 1 is attracted to the stage main body 3 and distorted with the foreign object 8 sandwiched between it and the wafer mounting surface 3a, as shown in FIG. In the optical fiber 12 facing this distorted portion, the amount of reflected light incident on the light receiving section 15 increases. The light reflection type distance measuring instrument body 11 detects this and sounds an alarm if the gap distance is larger than a specified value.

Therefore, according to this stage 2, it is possible to detect the distortion of the wafer 1 by detecting that the distance between the back surface of the wafer 1 and the optical fiber 12 has become larger than a set value. The foreign matter 8 can be removed before applying.

It goes without saying that the present invention can be applied not only to inspection equipment but also to wafer chaffing, mask holders, etc. of coater developers, etc.

〔Effect of the invention〕

As explained above, the semiconductor wafer stage according to the present invention has a stage body with a large number of through holes that open to the semiconductor wafer mounting surface, and these through holes are provided with holes on the back side of the semiconductor wafer on the stage body. Since a light reflective distance measuring device that measures the dimension to the back surface by reflecting light is installed, the distance between the back surface of the semiconductor wafer and the light reflective distance measuring device is wider than the set value (by which the semiconductor wafer It is detected that the semiconductor wafer is distorted.Therefore, it is possible to reliably prevent defocus and measurement errors caused by distortion of the semiconductor wafer.Also, it is possible to prevent errors immediately after the semiconductor wafer is attracted to the stage body. This has the effect of improving the operating rate of the device because it can be detected and re-adsorbed immediately.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a sectional view showing an enlarged main part of the semiconductor wafer stage according to the present invention, FIG. 2 is a plan view of the semiconductor wafer stage according to the present invention, and FIG. FIG. 4 is a cross-sectional view showing an enlarged view of the sensor of the light reflection type distance measurement device used in the semiconductor wafer stage of the present invention, and FIG. 4 shows the relationship between the amount of reflected light and the gap distance when the light reflection type distance measurement device is used. This is a graph showing. FIG. 5 is a sectional view showing a part of a conventional semiconductor wafer stage, and FIG. 6 is a plan view of the conventional semiconductor wafer stage with a wafer attached thereto. 1...Wafer, 2...Stage, 3...Stage body, 3a...Wafer mounting surface, 11...
Light reflection type distance measuring device body, 12... Optical fiber, 1
3...Through hole.

Claims (1)

[Claims] In a semiconductor wafer stage in which a semiconductor wafer is attracted to a wafer placement surface of a stage body, the stage body is provided with a number of through holes that open to the semiconductor wafer placement surface;
A semiconductor wafer stage characterized in that these through holes are equipped with a light reflection type distance measuring device that measures the dimension to the back surface of the semiconductor wafer on the stage main body by reflecting light onto the back surface of the semiconductor wafer.