JP2007266091A - Slit plate of spatial image sensor, spatial image sensor and exposure apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slit plate in which a time required to draw an alignment mark is short, and a manufacturing cost is low. <P>SOLUTION: This slit plate is provided on a spatial image sensor to be attached on a wafer stage in order to align a reticle stage and the wafer stage in an exposure apparatus. In this slit plate of the spatial image sensor, the alignment mark to be provided on the slit plate for aligning the slit plate includes a checkered pattern. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a slit plate of an aerial image sensor, an aerial image sensor, and an exposure apparatus that are attached to a wafer stage of an exposure apparatus for aligning a reticle stage and a wafer stage.

  In an exposure apparatus using energy rays, in order to project a reticle pattern onto a sensitive substrate (wafer) with high accuracy, it is necessary to align the reticle stage and wafer stage with high accuracy. .

  In an exposure apparatus for EUV (Extreme Ultraviolet) lithography (hereinafter referred to as EUV exposure apparatus) using soft X-rays having a wavelength of about 11 to 14 nanometers, the reticle stage and wafer stage are aligned (aligned). Therefore, a method of detecting a projected image of the reticle alignment mark formed on the reticle stage with a spatial image sensor installed on the wafer stage is used (for example, Patent Document 1).

  FIG. 4 is a diagram showing the configuration of the aerial image sensor.

  As shown in FIG. 4, the aerial image sensor includes a slit plate 101, a frame 103, and a photodetector 105. The aerial image sensor is installed on the wafer stage 107.

  FIG. 5 is a diagram illustrating the configuration of the slit plate 101.

  As shown in FIG. 5, slit marks 201 and 203 are formed on the slit plate 101 in the X-axis direction and the Y-axis direction orthogonal to each other. The slit widths and periods of the slit marks 201 and 203 are formed to be the same as the width and period of the projected image of the reticle alignment mark on the wafer stage.

  The reticle stage and the wafer stage are relatively scanned at a low speed, the output of the photodetector 105 is observed, and alignment (alignment) is performed so that the output of the photodetector 105 is maximized. It is necessary to measure the relative distance between the position at which the reticle alignment mark is projected onto the wafer stage and the position of the aerial image sensor with an accuracy of several nanometers or less. For this reason, it is preferable that the reticle alignment mark and the slit of the aerial image sensor have a sufficiently small period.

  As described above, the slit marks 201 and 203 on the slit plate 101 are used to align the reticle stage and the wafer stage. Therefore, in the step of installing the aerial image sensor on the wafer stage 107, the slit plate 101 is aligned (aligned) with high precision with respect to the frame 103, and further, in the step of installing the aerial image sensor on the wafer stage 107, the wafer It is necessary to align (align) the stage 107 with high accuracy.

  FIG. 6 is a diagram showing the aerial image sensor installed on the wafer stage 107.

  In the manufacturing process of the aerial image sensor, the worker needs to align (align) the slit plate 101 with the frame 103 with high accuracy. Further, in the process of installing the aerial image sensor on the wafer stage 107, an operator needs to align (align) the aerial image sensor with respect to the wafer stage 107 with high accuracy. Therefore, an alignment mark 205 is attached to the slit plate 101 as shown in FIG. An operator observes the alignment mark 205 using an optical microscope, or performs alignment with the naked eye.

  FIG. 7 is a diagram showing an example of the configuration of a conventional alignment mark 205.

  As shown in FIG. 7, the alignment mark 205 includes a rectangular mark 207 and a cross mark 209. As described above, since the alignment mark 205 is an object to be observed using an optical microscope or to be observed with the naked eye, one side of the rectangular mark 207 is several hundred micrometers.

  The slit marks 201 and 203 on the slit plate 101 are drawn by an electron beam drawing apparatus. As the electron beam drawing apparatus, a point beam electron beam drawing apparatus is used so as to draw the slit with the above-mentioned small period. On the other hand, the alignment mark 205 of the slit plate 101 is often drawn by the same electron beam drawing apparatus. However, since the point beam electron beam drawing apparatus has a small area that can be drawn per hour, it takes a long time to draw a rectangular pattern having a side of several hundred micrometers. Therefore, the manufacturing cost of the slit plate is increased.

JP 2005-32889 A

  Under the above background, there is a need for a slit plate and an aerial image sensor with a short time for drawing an alignment mark and a low manufacturing cost.

  The slit plate according to the present invention is provided in an aerial image sensor attached to a wafer stage in order to align the reticle stage and the wafer stage in the exposure apparatus. The slit plate of the aerial image sensor according to the present invention is characterized in that an alignment mark attached on the slit plate for aligning the slit plate includes a checkered pattern.

  Since the alignment mark attached on the slit plate includes a checkered pattern, it is not necessary to draw a blank part of the checkered pattern when the alignment mark is drawn by the electron beam drawing apparatus. Therefore, it is possible to shorten the time for drawing with the electron beam drawing apparatus as compared with the conventional alignment mark which needs to draw the whole of the rectangle of the alignment mark.

  On the other hand, an alignment mark in which a checkerboard pattern is drawn to form a rectangle, for example, is recognized in the same manner as an alignment mark in which the entire area is drawn to form a rectangle, and thus performs the same function.

  As described above, according to the present invention, it is possible to reduce the manufacturing cost of the slit plate by shortening the drawing time by the electron beam drawing apparatus as compared with the conventional alignment mark.

  FIG. 1 is a diagram illustrating a configuration of an alignment mark of a slit plate according to an embodiment of the present invention.

  In FIG. 1, the drawn area is indicated by diagonal lines. The alignment mark is composed of a checkered pattern part forming a rectangle 208 as a whole and a cross mark 209. The checkered pattern of the rectangle 208 includes a drawn rectangular region 211 and a non-drawn rectangular region 213. In FIG. 1, the unit of the number indicating the size is millimeter.

  The cross mark 209 is used when alignment (alignment) is performed with higher accuracy than when the rectangle 208 is used.

  FIG. 2 is a diagram showing a configuration of a drawn rectangular area 211 in the alignment mark.

  As shown in FIG. 2, the drawn rectangular region 211 also has a checkered pattern. The checkered pattern of the drawn rectangular area 211 includes a drawn rectangular area 215 and an undrawn rectangular area 217. In FIG. 2, the unit of the number indicating the size is millimeter.

  The area of the slit 208 alignment mark drawn in the rectangle 208 is 1 / of the area of the slit plate alignment mark drawn in the rectangle 207 shown in FIG. 4. Therefore, if the area where the cross mark 209 is drawn is ignored, the area of the drawn area of the slit plate alignment mark shown in FIG. 1 is the drawing area of the slit plate alignment mark shown in FIG. It is about 1/4 of the area of the formed region. As a result, the drawing time of the alignment mark of the slit plate shown in FIG. 1 of the electron beam drawing apparatus is about 1 / second of the drawing time of the alignment mark of the slit plate shown in FIG. 4. Thus, the drawing time of the alignment mark of the slit plate according to the embodiment of the present invention of the electron beam drawing apparatus is significantly shortened as compared with the alignment mark of the conventional slit plate.

  In the manufacturing process of the aerial image sensor, the worker uses the alignment marks on the slit plate 101 to align the slit plate 101 with the frame 103 with high accuracy (alignment). Further, in the process of installing the aerial image sensor on the wafer stage 107, the operator uses the alignment mark on the slit plate 101 to align the aerial image sensor with respect to the wafer stage 107 with high accuracy (alignment). To do. An operator observes the alignment mark 205 using an optical microscope, or performs alignment with the naked eye.

  Since the checkerboard pattern forms a rectangle 208 as a whole, the worker can recognize and align the rectangle 208 in the same manner as the rectangle 207 in the conventional alignment mark shown in FIG. it can.

  FIG. 3 is a diagram schematically showing a configuration of an EUV exposure apparatus according to an embodiment of the present invention.

  The EUV exposure apparatus includes an illumination optical system IL including a light source. The EUV light emitted from the illumination optical system IL is reflected by the folding mirror 11 and applied to the reticle 13.

  The reticle 13 is held on the reticle stage 15 with the pattern surface facing downward in the direction of gravity. The reticle stage 15 can move in the scanning direction (Y-axis direction), the direction orthogonal to the scanning direction (X-axis direction), and the optical axis direction (Z-axis direction).

  The EUV light reflected by the reticle 13 enters the projection optical barrel 17. The EUV light incident on the projection optical column 17 is sequentially reflected by the reflecting mirrors M 1 to M 6 and finally enters the wafer 19.

  The wafer 19 is disposed on the wafer stage 107. The wafer stage 107 can move in the X-axis direction, the Y-axis direction, and the optical axis direction (Z-axis direction) in a plane orthogonal to the optical axis.

  On the wafer stage 107, an aerial image sensor (not shown) is formed. As described above, the aerial image sensor is used to align the reticle stage 15 and the wafer stage.

It is a figure which shows the structure of the alignment mark of a slit board by one Embodiment of this invention. It is a figure which shows the structure of the drawn rectangular area | region in the alignment mark by one Embodiment of this invention. It is a figure which shows schematically the structure of the EUV exposure apparatus by one Embodiment of this invention. It is a figure which shows the structure of an aerial image sensor. It is a figure which shows the structure of a slit board. It is a figure which shows the aerial image sensor installed on the wafer stage. It is a figure which shows an example of a structure of the conventional alignment mark.

Explanation of symbols

101 ... Slit plate, 103 ... Frame, 105 ... Photo detector, 201, 203 ... Slit mark, 205 ... Alignment mark

Claims (6)

  In an exposure apparatus, a slit plate of an aerial image sensor attached to a wafer stage for aligning a reticle stage and a wafer stage, and an alignment mark attached on the slit plate for aligning the slit plate is a checkered pattern The slit board characterized by including.   The slit plate according to claim 1, wherein the alignment mark includes at least one rectangle, and the rectangle includes a checkered pattern.   3. The slit plate according to claim 1, wherein the rectangular portion that is not a white background of the checkered pattern further comprises a checkered pattern.   The slit plate according to claim 1, wherein the alignment mark further includes a cross mark.   An aerial image sensor comprising the slit plate according to claim 1. The aerial image sensor according to claim 5, wherein alignment of a reticle stage on which a pattern-formed reticle is placed and a wafer stage on which a wafer on which the pattern is projected is placed is performed on the wafer stage. An exposure apparatus configured as described above.

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