JP2010135426A - Exposure method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a distance of stage movement when exposing a perfect shot and an edge shot separately. <P>SOLUTION: An exposure method includes a step of performing a first sequence for exposing the perfect shot of a wafer 1 and a step of performing a second sequence for exposing the edge shots of regions A and B predetermind to be arranged in parallel to an X-axis direction in the wafer 1 apart from the first sequence. The edge shots contained in the regions A and B are exposed in an exposure order by "X-Winding". In the second sequence for exposing the edge shot, the edge shot contained in the region B is exposed after exposure of the edge shot contained in the region A is completed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exposure method and an exposure apparatus, and more particularly, to an exposure method and an exposure apparatus that perform exposure by a step-and-repeat method.

  The step-and-repeat method is the most widely used exposure method in the manufacture of semiconductor devices. In the step-and-repeat method, after the exposure for one shot is completed, the operation of moving the exposure location according to the size of the shot and performing the exposure for the next shot is repeated. Here, a shot is a unit of exposure, and one shot includes both a case where only a single chip is included and a case where a plurality of chips are included. A step-and-repeat exposure method is disclosed in, for example, Japanese Patent Laid-Open No. 9-115814.

  In general, when exposure by the step-and-repeat method is performed, the drive locus of the wafer stage has a meandering shape. More specifically, as shown in FIG. 1A, a row of shot groups 2 arranged in a certain specific direction on the wafer 1 is sequentially exposed in the specific direction (for example, + X direction), and subsequently Thus, shots in adjacent rows are sequentially exposed in the opposite direction (for example, the −X direction). This procedure is repeated until the exposure for all shots is completed. Hereinafter, the direction in which shots are sequentially exposed in each column is referred to as “step direction”.

  The “step direction” may be either the vertical direction or the horizontal direction of the wafer 1. As shown in FIG. 1A, an exposure method in which the “step direction” is parallel to the X-axis direction is hereinafter referred to as “X-Winding”, and similarly as shown in FIG. 1B. An exposure method in which the “step direction” is parallel to the Y-axis direction is hereinafter referred to as “Y-Winding”. Here, in FIGS. 1A and 1B, when the oriental flat (or notch) is placed downward, the left-right direction of the wafer 1 is defined as the X-axis direction and the up-down direction is defined as the Y-axis direction. “X-Winding” and “Y-Winding” as shown in FIGS. 1A and 1B are used to avoid unnecessary stage movement by improving the exposure throughput by causing the drive locus of the wafer stage to meander. It is valid.

  The hardware configuration of the exposure apparatus is normally designed so that the exposure accuracy is high when either “X-Winding” or “Y-Winding” is performed. That is, an exposure apparatus corresponding to “X-Winding” generally has poor exposure accuracy when exposure is performed by a procedure other than “X-Winding”. Similarly, an exposure apparatus corresponding to “Y-Winding” generally has poor exposure accuracy when exposure is performed in a procedure other than “Y-Winding”.

In step-and-repeat exposure, a complete shot without a chip and an incomplete shot (typically called an edge shot) with a chip located on the outer periphery of the wafer are exposed in different sequences. There are things to do. For example, Japanese Patent Laid-Open No. 2001-319872 discloses postponing exposure of an incomplete shot (typically called an edge shot) that is located on the outer periphery of a wafer and has a chip (see FIG. 2). The purpose of postponing the exposure of the edge shot is to prevent the thermal expansion of the wafer caused by the temperature rise due to the exposure from deteriorating the accuracy of the exposure. For edge shots, the exposure error is not as important. By performing edge shot exposure at the later stage of exposure that is largely affected by temperature rise, the effect of temperature rise on a complete shot can be suppressed.
Japanese Patent Laid-Open No. 9-115814 JP 2001-319872 A

  However, according to the inventor's study, if the exposure method is performed after the edge shot, the normal “X-Winding” or “Y-Winding” as shown in FIGS. 1A and 1B is used. There is a problem that the distance of stage movement becomes long. For example, referring to FIG. 1A, when performing exposure after an edge shot by “X-Winding”, the edge shot 2a at one end (for example, the right end) of a wafer in a column is followed by the other end in the same row ( For example, the edge shot 2b at the left end) is exposed. This increases the distance of stage movement. The same applies to the case where exposure is performed by postponing the edge shot by “Y-Winding”.

  In order to solve the above problems, the present invention employs the means described below. In one aspect of the present invention, the exposure method includes a step of executing a first sequence for exposing a complete shot of a wafer, and a first defined to be arranged in a specific direction on the wafer, separately from the first sequence. Executing a second sequence for exposing the edge shot of the region and the second region. In the exposure of edge shots included in each of the first region and the second region, after the exposure of the edge shot of a certain row is completed, the procedure of exposing the edge shot of the adjacent row is repeated, and (1 ) When only one edge shot is included in the row of exposed edge shots, one edge shot is exposed, and (2) When a plurality of edge shots are included in the column of exposed edge shots When the edge shot row to be exposed is an odd-numbered row, a plurality of edge shots are sequentially exposed in a first direction parallel to a specific direction, and the exposed edge shot row is an even-numbered row. In some cases, a plurality of edge shots are sequentially exposed in a second direction opposite to the first direction. In the second sequence, after the exposure of the edge shot included in the first area is completed, the exposure of the edge shot included in the second area is performed.

  In another aspect of the present invention, an exposure apparatus includes a stage that moves a wafer and an exposure optical system that irradiates the wafer with an exposure beam. At this time, the exposure apparatus moves the stage so that the exposure is performed according to the exposure method described above.

  According to the present invention, the distance of stage movement can be shortened when a complete shot and an edge shot are separately exposed.

  FIG. 3 is a drawing schematically showing a configuration of an exposure apparatus according to an embodiment of the present invention. In the present embodiment, the exposure apparatus 10 includes an illumination optical system 11, a projection optical system 12, an XY stage 13, and a controller 14. The illumination system 11 irradiates the reticle 15 with an exposure beam. The projection optical system 12 projects the exposure beam that has passed through the reticle 15 onto the wafer 1 placed on the XY stage 13. The exposure beam may be an electron beam, X-ray, or light. The XY stage 13 moves a desired shot of the wafer 1 to a position where an exposure beam is projected so that exposure is performed. The controller 14 controls the illumination optical system 11, the projection optical system 12, and the XY stage 13 so that a desired shot is exposed under a desired condition.

  In this embodiment, a complete shot without a chip and an edge shot (that is, an incomplete shot with a chip located on the outer periphery of the wafer) are exposed in different sequences. In the present embodiment, edge shot exposure is performed after complete shot exposure with no chipping. In the present embodiment, special measures are taken in the exposure of the edge shot. Hereinafter, the exposure method performed in the present embodiment will be described in detail.

  FIG. 4A is a diagram illustrating an exposure order when the exposure apparatus 10 supports “X-Winding”. In FIG. 4A (and FIG. 4B), reference numeral 2 indicates each shot of the wafer 1. The circled numbers indicate the exposure order of the shot group 2. First, a complete shot group 2 having no chip is exposed (circled number “1”). The complete shot group 2 exposure sequence is performed in accordance with “X-Winding”. That is, after the shot group 2 of a certain row of the wafer 1 is sequentially exposed in the −X direction, the procedure in which the shots of the adjacent row are sequentially exposed in the + X direction is repeated so that all complete shots are obtained. Group 2 is exposed. In FIG. 4A, the “step direction” in exposure of odd-numbered shots is the −X direction, and the “step direction” in exposure of even-numbered shots is the + X direction.

  Subsequently, edge shot exposure is performed (circled numbers “2” and “3”). In the edge shot exposure sequence, the wafer 1 is divided into two regions: regions A and B aligned in the “step direction” (that is, aligned in the X-axis direction). In FIG. 4A (and FIG. 4B), the broken line indicates the boundary between regions A and B. After the exposure of all edge shots (circle number “2”) belonging to the region A is completed, the exposure of all edge shots (circle number “3”) belonging to the region “B” is performed. The exposure of the edge shot in each of the above is performed according to “X-Winding”. In FIG. 4A, the “step direction” in the exposure of odd-numbered edge shots is the −X direction, and the “step direction” in the exposure of even-numbered shots is the + X direction.

  More specifically, in the example of FIG. 4A, the edge shot of the area A is exposed by the following procedure: First, four edge shots of the column “1” of the area A are sequentially exposed in the −X direction. Thereafter, two edge shots in the column “2” are sequentially exposed in the + X direction. The edge shots in the other rows of the area A are exposed in the same manner. Here, when there is only a single edge shot in one row, the edge shot of the adjacent row is exposed immediately after the edge shot is exposed. For example, in the region A, since there is only a single edge shot in the column “3”, the exposure of the edge shot in the column “4” is performed when the exposure of the edge shot is finished.

  When all the edge shots in area A have been exposed, the edge shots in area B are exposed in the following procedure: First, the four edge shots in row “1” of area B are sequentially exposed in the −X direction. After that, the two edge shots in the column “2” are sequentially exposed in the + X direction. The edge shots in the other rows of the region B are exposed in the same manner. Here, when there is only a single edge shot in one row, the edge shot of the adjacent row is exposed immediately after the edge shot is exposed. For example, in the region B, since there is only a single edge shot in the column “3”, the exposure of the edge shot in the column “4” is performed when the exposure of the edge shot is finished.

  When exposure is performed in such an exposure sequence, it is not necessary to move the XY stage 13 so that the shot at the other end of the same row is exposed after the exposure of the shot at one end of a certain row. That is, one of the edge shots at one end and the edge shot at the other end of each row belongs to the region A and the other belongs to the region B. Therefore, by exposing the edge shots of the area A together and then exposing the edge shots of the area B together, after each edge shot is exposed, the edge shot of the other end is exposed. There is no need to move it to the exposure position. For this reason, the stage moving distance can be shortened.

  Even when the exposure apparatus 10 supports “Y-Winding”, exposure is performed in the same procedure after changing the “step direction” to the Y-axis direction. FIG. 4B is a diagram illustrating an exposure order when the exposure apparatus 10 supports “Y-Winding”.

  First, a complete shot group 2 having no chip is exposed (circled number “1”). The complete shot group 2 exposure sequence is performed in accordance with “Y-Winding”. That is, after a shot group 2 in a certain row on the wafer 1 is sequentially exposed in the -Y direction, a sequence in which shots in adjacent rows are sequentially exposed in the + Y direction is repeated, so that all complete shots are obtained. Group 2 is exposed. In FIG. 4B, the “step direction” in exposure of odd-numbered shots is the −Y direction, and the “step direction” in exposure of even-numbered shots is the + Y direction.

  Subsequently, edge shot exposure is performed (circled numbers “2” and “3”). In the edge shot exposure sequence, the wafer 1 is divided into two regions: regions A and B aligned in the “step direction” (that is, aligned in the Y-axis direction). After the exposure of all edge shots belonging to the region A (circled number “2”) is completed, exposure of all edge shots belonging to the region B (circled number “3”) is performed. Edge shot exposure in each of the regions A and B is performed in accordance with “Y-Winding”. In FIG. 4B, the “step direction” in the exposure of odd-numbered edge shots is the −Y direction, and the “step direction” in the exposure of even-numbered shots is the + Y direction.

  Also in this case, the edge shots in the region A are exposed together, and then the edge shots in the region B are exposed together, so that after each edge shot is exposed, the edge shots at the other end are exposed. Need not be moved to the exposure position. For this reason, the stage moving distance can be shortened.

  It is also possible to divide the wafer 1 into three or more regions and perform edge shot exposure for each region. For example, as shown in FIGS. 5A and 5B, the wafer 1 can be divided into four regions, top, bottom, left, and right, and edge shot exposure can be performed. If a recipe for exposure divided into four areas from top to bottom and left and right is created from the beginning, the left and right two areas (in the case of the exposure apparatus 10 corresponding to “X-Winding”) or the top and bottom two areas (“Y− The exposure recipe is shared between the exposure apparatus corresponding to “X-Winding” and the exposure apparatus corresponding to “Y-Winding”, although the throughput is somewhat lower than that of the exposure apparatus 10 corresponding to “Winding”. Can be used. Thereby, there is no need to create an exposure recipe for each of the exposure apparatus corresponding to “X-Winding” and the exposure apparatus corresponding to “Y-Winding”, and the number of steps for creating the exposure recipe can be reduced.

  Specifically, FIG. 5A is a diagram illustrating an exposure order when the exposure apparatus 10 supports “X-Winding”. First, after a complete shot group 2 having no chip is exposed according to “X-Winding” (circled number “1”), edge shot exposure is performed (circled numbers “2” to “5”).

  In the edge shot exposure, the wafer 1 is divided into four regions, upper, lower, left and right: regions A1, A2, B1, and B2. After the exposure of all edge shots (circle number “2”) belonging to the area A1 is completed, the exposure of all edge shots (circle numeral “3”) belonging to the area A2 is performed. Further, after the exposure of all edge shots (circle numeral “4”) belonging to the area B1 is completed, the exposure of all edge shots belonging to the area B2 (circle numeral “5”) is performed. Edge shot exposure in each of the areas A1, A2, B1, and B2 is performed in accordance with “X-Winding”.

  Here, the area A2 is exposed following the area A1, and similarly, the area B2 is exposed following the area B1. By exposing the edge shots of the area A1 together and then exposing the edge shots of the area A2 together, the stage moving distance can be shortened. Similarly, the stage movement distance can be shortened by exposing the edge shots of the region B1 together and then exposing the edge shots of the region B2 together. The exposure recipe at this time is 1) all edge shot exposures belonging to area A1, 2) all edge shot exposures belonging to area A2, 3) all edge shot exposures belonging to area B1, and 4) all belonging to area B2. The edge shot exposure is performed in this order.

  On the other hand, FIG. 5B is a diagram showing an exposure order when the exposure apparatus 10 supports “Y-Winding”. First, after the complete shot group 2 having no chip is exposed according to “Y-Winding” (circled number “1”), edge shot exposure is performed (circled numbers “2” to “5”).

  Similarly to the case of “X-Winding”, in edge shot exposure when the exposure apparatus 10 supports “Y-Winding”, the wafer 1 is divided into four areas, upper, lower, left and right: areas A1, A2, It is divided into B1 and B2. After the exposure of all edge shots (circle number “2”) belonging to the area A1 is completed, the exposure of all edge shots (circle numeral “3”) belonging to the area A2 is performed. Further, after the exposure of all edge shots (circle numeral “4”) belonging to the area B1 is completed, the exposure of all edge shots belonging to the area B2 (circle numeral “5”) is performed. Edge shot exposure in each of the areas A1, A2, B1, and B2 is performed in accordance with “Y-Winding”.

  The exposure recipe at this time is 1) all edge shot exposures belonging to area A1, 2) all edge shot exposures belonging to area A2, 3) all edge shot exposures belonging to area B1, and 4) all belonging to area B2. The edge shot exposure is performed in this order. This is the same as the exposure recipe in FIG. 5A. In this case, since the stage is moved for each area, the throughput is slightly reduced as compared with the case where the exposure is divided into two upper and lower areas, but the same exposure recipe as the exposure apparatus corresponding to “X-Winding” is used. There is an advantage that it can be used.

FIG. 1A is a diagram showing a conventional exposure method by “X-Winding”. FIG. 1B is a diagram showing a conventional exposure method by “Y-Winding”. FIG. 2 is a diagram showing a conventional exposure method in which exposure of edge shots is postponed. FIG. 3 is a schematic view showing the arrangement of an exposure apparatus according to an embodiment of the present invention. FIG. 4A is a schematic view showing an exposure method in one embodiment of the present invention. FIG. 4B is a schematic view showing an exposure method in another embodiment of the present invention. FIG. 5A is a schematic view showing an exposure method in still another embodiment of the present invention. FIG. 5B is a schematic view showing an exposure method in still another embodiment of the present invention.

Explanation of symbols

1: Wafer 2: Shot 2a, 2b: Edge shot 10: Exposure apparatus 11: Illumination optical system 12: Projection optical system 13: XY stage 14: Controller

Claims (2)

Performing a first sequence of exposing a complete shot of the wafer;
Aside from the first sequence, the step of executing a second sequence for exposing edge shots of the first region and the second region defined to be aligned in a specific direction on the wafer,
In the exposure of edge shots included in each of the first region and the second region, after the exposure of the edge shot of a certain row is completed, the procedure of performing the exposure of the edge shot of the adjacent row is repeated, (1) When only one edge shot is included in the row of exposed edge shots, the one edge shot is exposed, and (2) a plurality of edge shots are included in the column of exposed edge shots. When the edge shot row to be exposed is an odd-numbered row, the plurality of edge shots are sequentially exposed in a first direction parallel to the specific direction, and the edge shot to be exposed When the row is an even-numbered row, the plurality of edge shots are sequentially exposed in a second direction opposite to the first direction,
In the second sequence, after the exposure of the edge shot included in the first area is completed, the exposure of the edge shot included in the second area is performed. A stage for moving the wafer;
An exposure apparatus comprising an optical system that irradiates the wafer with an exposure beam to expose each shot of the wafer,
In addition to the first sequence for exposing a complete shot of the wafer, the stage performs a second sequence for exposing edge shots of the first area and the second area that are defined to be aligned in a specific direction on the wafer. Driven to
In the exposure of edge shots included in each of the first region and the second region, after the exposure of an edge shot of a certain row is completed, the procedure of performing exposure of the edge shot of an adjacent row is repeated, (1) When only one edge shot is included in the row of edge shots to be exposed, the one edge shot is exposed, and (2) a plurality of edge shots are included in the column of edge shots to be exposed. When the edge shot row to be exposed is an odd-numbered row, the plurality of edge shots are sequentially exposed in a first direction parallel to the specific direction, and the edge shot to be exposed When the row is an even-numbered row, the plurality of edge shots are sequentially exposed in a second direction opposite to the first direction,
In the second sequence, after the exposure of the edge shot included in the first region is completed, the exposure of the edge shot included in the second region is performed.

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