JPS63281008A - Exposing means - Google Patents

Abstract

PURPOSE:To securely prevent a defective pattern from being formed by checking whether or not there is abnormality of flatness on an exposure device side and taking a self-judgement of abnormality like this. CONSTITUTION:An exposing device A which has an automatic focusing device measures the coordinates of three points (or >=3 points) on a wafer 6 and a reference plane for the wafer 6 is found from at least the three monitored points. Then exposing operation is entered, the automatic focusing device controls the lens position of the exposing device A at each exposure position so that a constant interval l to the surface of the wafer 6 is maintained, and the position (height) of the lens which is controlled for each exposure position A is compared with a reference value found from the specific point of the lens for, for example, a rack. Consequently, whether or not there is the abnormality of flatness of a pattern formation body surface is detected by detecting whether or not the difference is smaller than a specific value.

Description

[Detailed Description of the Invention] [Summary] Before exposure, the coordinates of at least three points on the surface of the patterned body are measured to determine a reference plane for the patterned body,
The position of the exposure lens, which is controlled to maintain a constant distance from the surface of the patterned body for each exposure position, is compared with each reference value obtained from a predetermined point on the reference plane corresponding to the exposure position. and detecting whether there is an abnormality in the flatness of the surface of the pattern-formed body by detecting whether the difference is within a tolerance value, the exposure method comprising: If there is a change in flatness, the change in flatness can be reliably checked to prevent the occurrence of defective patterns.

(Industrial Field of Application) The present invention relates to an exposure method for detecting whether there is an abnormality in the flatness of the surface of a patterned object such as a wafer or a glass dry plate.

[Conventional technology]

- When transferring a predetermined pattern onto a wafer, a glass dry plate, etc. using a resist, etc., a stepper, a photorepeater, etc. While moving the side, adjust the automatic focusing device (
A predetermined pattern is formed by focusing the lens using an autofocus device (an autofocus device).

Figure 2 shows a schematic diagram of the automatic focusing device installed in the above-mentioned exposure device, and 1 is a lens (reducing projection lens).
Column parts 2 and 3 with the main body are light emitting parts and light receiving parts, 4 and 5, respectively, provided in the column parts.
are reflecting mirrors, and 6 is a wafer. As shown in FIG. 3, the path of the reflected light sent out from the light emitting section 2, sequentially reflected by the reflecting mirror 4, the surface of the wafer 6, and the reflecting mirror 5, and directed toward the light receiving section 3 is the wafer on which the reflected light is reflected. 6 Varies depending on the top and bottom position of the surface. Therefore, the position (height) of the lens (or the wafer surface) is adjusted as indicated by the symbols 1 to 1'' in FIG. 4 so that the reflected light is always correctly received by the light receiving section 3 (for example, As shown in FIG. 4, by moving the main body up and down with respect to the pedestal, the distance l between the column (lens) and the wafer surface can be kept constant even if the flatness of the wafer surface changes. It can be controlled to keep.

[Problem that the invention seeks to solve]

In this way, the conventional automatic focusing device has a function of controlling the height of the lens body so that the distance l between the lens body and the wafer surface is constant in accordance with the flatness of the wafer. For example, if the flatness of the wafer surface changes gradually, it is possible to automatically adjust the focus according to the change in flatness and form a normal pattern. If the flatness of the wafer surface changes rapidly due to the adhesion of dust, etc., the automatic focusing device will not be able to follow such sudden changes, and There is a problem in that even if there is a nest abnormality, pattern formation is performed, making it impossible to avoid the generation of defective patterns.

The present invention has been made to solve this problem, and as described above, when there is a large flatness abnormality due to dust or the like adhering to the wafer surface, the flatness abnormality is By reliably checking the presence of such abnormalities on the exposure apparatus side and reliably self-determining the presence or absence of such abnormalities, the occurrence of defective patterns can be reliably prevented.

[Means for solving problems]

In order to solve this problem, in the present invention, the coordinates of at least three points on the surface of the patterned body are measured before exposure to determine a reference plane corresponding to the patterned body,
Comparing the position of the exposure lens, which is controlled to maintain a constant distance from the surface of the patterned body for each exposure position, with each reference value determined from a predetermined point on the reference plane for the exposure position, An exposure method is provided that includes a step of detecting the presence or absence of an abnormality in flatness on the surface of the patterned body by detecting whether the difference is within a tolerance value.

[For production]

According to the above configuration, by comparing the position of the lens and the reference value for each exposure position, if the flatness of the surface of the pattern forming body changes rapidly, the flatness is determined. It is possible to reliably check for the presence of anomalies and to reliably prevent the occurrence of defective patterns.

〔Example〕

FIG. 1 is a flowchart for explaining the steps of an exposure method as an embodiment of the present invention, in which for each wafer as a pattern forming body (the same applies to the case of a glass dry plate),
In order to determine whether or not there is an abnormality in the flatness of the wafer, first in step 1, before exposure, using the exposure apparatus having the automatic focusing device, focus on three points (or three points) on the wafer. The coordinates (above) are measured, and a reference plane for the wafer is determined from at least three points monitored in this manner on the stent 2.

Next, in step 3, the exposure operation begins, and the automatic focusing device controls the position of the lens of the exposure device so as to maintain a constant distance l from the wafer surface for each exposure position. The position (height) of the lens controlled in this way is detected, for example, by the relative displacement of the lens with respect to the mount, and then in step 4, the position (height) of the lens thus detected corresponds to the exposure position. The reference value (
2 coordinates of a predetermined point on the reference plane determined by the X and Y coordinates corresponding to the exposure position. As a result of the comparison, if the difference between the position of the lens at the exposure position and the reference value is within a predetermined tolerance range, the process moves to step 5, and each For each exposure position, the lens position is detected (step 3), and the detected lens position is compared with a reference value corresponding to the exposure position (step 4).

In this way, if all the differences between the lens position and the reference value are within the tolerance range and the exposure work for the wafer is completed, the process moves from step 5 to step 6, and the process starts again from step 1 for the next wafer. Each of the above steps is repeated.

On the other hand, during exposure work at a certain exposure position, if in step 4 above the difference between the position of the lens at the exposure position and the reference value exceeds the tolerance range, the process moves to step 7 and a predetermined alarm is set. In addition, in step 8 it is determined whether to stop or continue the exposure operation, and if it is determined to stop, the process moves to step 9 and the operation of the exposure apparatus is stopped.

〔Effect of the invention〕

According to the present invention, when the flatness of the surface of a patterned object changes rapidly, the sudden change (abnormality) in the flatness can be reliably checked, thereby preventing the occurrence of defective patterns. can be reliably prevented.

[Brief explanation of drawings]

FIG. 1 is a flowchart for explaining the steps of an exposure method as an embodiment of the present invention, FIG. 2 is a schematic diagram of an automatic focusing device provided in a general exposure apparatus, and FIG. The figure is a diagram explaining how the path of reflected light changes depending on the vertical position of the wafer surface, and Figure 4 is a diagram showing how the lens body is moved up and down in response to changes in the flatness of the wafer surface. be. (Explanation of symbols) 1... Column section with built-in lens body, 2... Light emitting section, 3... Light receiving section, 4.5... Reflector,
6... Wafer surface. Figure 1: Flowchart for

Claims (1)

[Claims] 1. Before exposure, measure the coordinates of at least three points on the surface of the pattern-formed body to determine a reference plane for the pattern-formed body, and for each exposure position, measure the coordinates of at least three points on the surface of the pattern-formed body, and determine the coordinates of at least three points on the surface of the pattern-formed body for each exposure position. The position of the exposure lens, which is controlled to maintain a distance of An exposure method comprising the step of detecting the presence or absence of an abnormality in flatness on the surface of the patterned body by detecting the presence or absence of an abnormality in flatness on the surface of the patterned body. 2. The pattern forming body is a wafer or a glass dry plate;
An exposure method according to claim 1.