JP2010272624A - Exposure method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure method in which the number of products of good quality obtained on a substrate can be increased while maintaining the quality and without lowering the productivity by making an exposure shot effective by carrying out exposure using a focus measured value of the exposure shot in an exposure region wherein focus measurement can not be performed right before an exposure shot position and an inclination measured value of the substrate when the exposure shot to the exposure region is made. <P>SOLUTION: In the exposure method of carrying out the exposure by dividing a principal surface of the substrate into a plurality of exposure regions including its outer edge part, when exposure regions 104, 106 having their centers outside the outer edge part of the substrate are exposed, neither focus measurement at the positions nor inclination measurement of the substrate is carried out, and an exposure region having its center outside the outer edge part of the substrate is exposed using the focus measured value in the exposure region right before the measurement and the inclination measured value of the substrate to make the exposure shot effective, thereby increasing the number of products of good quality obtained on the substrate while maintaining the quality and without lowering the productivity. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exposure method for printing a reticle pattern on a wafer surface in a semiconductor manufacturing process.

  Conventionally, there are processing equipment (stepper) that fixes and exposes the reticle and the substrate with a processing device that prints the pattern of the reticle on the substrate through an optical system, and equipment (scanner) that moves the reticle and the substrate at the same time for exposure. The reticle pattern is baked on the substrate using two types of products, and the product is manufactured.

  These apparatuses divide the main surface of the substrate into a plurality of exposure areas including its outer edge, and perform exposure so that the substrate surface matches the optimum image of the projection optical system. Since the substrate is moved in the direction of the projection optical system on the moving stage, a focus sensor is used in the exposure apparatus. The focus detection is performed by irradiating the substrate surface with a non-exposure wavelength light beam and receiving the reflected light. Is carried out, and the amount of deviation from the optimal image on the substrate surface is measured, and focusing is performed by controlling the position of the moving stage in the direction of the projection optical system.

  On the other hand, on the outer edge of the substrate, the area that cannot be detected by the focus sensor is set as a fixed band with a fixed width. In this area, there is a case where the pattern cannot be printed.

  This will be described below with reference to the drawings. FIG. 6A shows a wafer map during exposure, and FIG. 6B shows the order of wafer exposure.

  As shown in FIG. 6A, the pattern of the product 607 is printed on the exposure region 603 including the focus measurement effective region 602 in the substrate 601 by one exposure shot. On the wafer surface, there is still a region where the image can be sufficiently printed, but exposure regions 604, 605, and 606 where the product cannot be printed are generated in that region.

  That is, as shown in FIG. 6 (b), the exposure apparatus is prepared from 0 to 16 in the numerical order shown in the figure, but since the forbidden band portion is not exposed, exposure shots 1 to 6 are sequentially arranged in the first column. Then, the exposure shots 9 to 16 are successively performed, and the exposure is continued, and the exposure areas 605, 604 in FIG. 606 is an invalid shot, and the other exposure areas 603 are valid shots. This is because the area that cannot be detected by the focus sensor at the outer edge of the substrate is set as a fixed band with a fixed width, so the amount of defocus cannot be measured in this prohibited band area, and the optimum image cannot be recognized. Therefore, in this area, the pattern cannot be printed, so that invalid exposure areas 604, 605, and 606 are formed.

  As a countermeasure, for example, as described in JP-A-6-029186, focusing is performed by shifting the focus detection point to the boundary line position of the forbidden band on the substrate, and then moving to the original shot exposure position. In this way, a method of exposing a pattern has also been proposed, but in this way, the stage is always moved to the focus detection point, focus detection is performed, and after this operation, the stage is moved to the corresponding exposure area, and then focusing is performed. When the exposure shot is performed, it is difficult to set the movement position from the forbidden band to a point where focus detection is possible, and it is necessary to build a difficult program in order to make the apparatus recognize this.

  In addition, once the stage is moved to the corresponding exposure area, it takes unnecessary movement and time to recognize the focus detection prohibition band, that is, the focus detection prohibition band. Further, focus detection is possible from the prohibition band. It is necessary to determine the setting of the movement position to the point while correlating the baking pattern with the product. Without this, the product quality cannot be maintained, so it is easy to cause quality defects and production with stable quality. Is difficult to realize.

JP-A-6-029186

  As described above, an exposure wafer map for printing a reticle pattern on a substrate through an optical system is created, and the exposure order is shown for a plurality of exposure areas on the map. When the exposure shot is advanced in the order of the first column and the next column, and this is continued, an effective exposure region and an invalid exposure region are generated on the wafer map by the exposure shot.

  This is because the focus measurement effective area of the exposure apparatus is set for the substrate, and when an exposure shot is performed outside this setting area, focus measurement and focusing cannot be performed, so this becomes an invalid exposure area. It is what. Therefore, the product cannot be efficiently baked on the substrate, and the product baking area on the substrate is wasted, so that it is not possible to effectively increase the number of products obtained on the substrate. As a result, the cost of the product cannot be reduced and the productivity is deteriorated.

  Further, as in the invention described in Patent Document 1 invented to solve these problems, after moving the stage to the corresponding exposure region, recognition of the focus detection prohibition band, that is, the focus detection prohibition band is performed. After that, the stage is moved to an area where focus detection is possible, focus detection is performed, and after this operation, the stage is moved to the corresponding exposure area, then focusing is performed, and exposure shot is performed for exposure. Things require wasted movement and time, and productivity is very poor.

  The present invention solves the above-described conventional problems, and in an exposure shot at an outer edge portion of a wafer, when an invalid exposure area in an area where focus measurement cannot be performed is expected to occur, a wafer that creates an array of the corresponding shot Prepare a map that uses the focus measurement value of the exposure shot immediately before and immediately after the above area and the substrate tilt measurement value when creating the map, thereby enabling this by exposing to the invalid exposure area position, quality It is an object of the present invention to provide an exposure method capable of increasing the number of high-quality products obtained on a substrate without reducing productivity while maintaining the above.

  In order to achieve the above object, an exposure method in which a main surface of a substrate is divided into a plurality of exposure areas including its outer edge, and the outer edge exposure area having a center outside the outer edge of the substrate is exposed. In this case, the outer edge exposure area is exposed using the focus measurement value and the substrate inclination measurement value in the exposure area immediately before or immediately after the focus measurement and the substrate inclination measurement at the position. It is.

  In this way, by using the focus measurement value and the substrate tilt measurement value of the exposure shot immediately before or immediately after, it is possible to make the exposure area that has been invalid until now effective, while maintaining productivity while maintaining quality. Without dropping, it is possible to increase the number of high-quality products obtained on the substrate.

  According to the present invention, it is possible to increase the number of high-quality products obtained on a substrate while maintaining high-quality quality and without reducing productivity.

Explanatory drawing of the wafer map in one embodiment of the exposure method of the present invention Explanatory drawing of exposure order based on wafer map of FIG. A graph showing a good quality estimation when the exposure method of the present invention is applied to a stepper The graph which shows the 1st good quality calculation when the exposure method of the present invention is applied to the scanner Explanatory drawing which shows the 2nd good quality calculation when the exposure method of the present invention is applied to the scanner Arrangement diagram of wafer map and explanatory diagram of exposure order in conventional exposure method

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory view of a wafer map in an embodiment of the exposure method of the present invention.

  As shown in FIG. 1, the pattern of the product 107 is printed in one exposure shot on the exposure area 103 including the focus measurement effective area 102 in the substrate 101.

  However, in this case, although there are areas where the wafer can be sufficiently printed on the wafer surface, exposure areas 104, 105, and 106 where the product cannot be printed are generated in that area.

  In the present embodiment, when a product is printed on the wafer (exposure), when an exposure is performed on the outer edge of the wafer, an invalid shot is placed in a region corresponding to the exposure region 604 in FIG. When generating an exposure shot array as shown in FIG. 1 in advance, the focus measurement value of the exposure shot immediately before (one before) the exposure area is always used, The exposure is performed at the position of the exposure area that becomes invalid, and thus the exposure area 104 can be validated.

  That is, when the exposure shots 1 to 6 in the first row of the numerical values shown on the wafer map are printed in the order of printing of the exposure apparatus shown in FIG. 2 and the exposure shots 9 to 16 in the next row are performed, the first row In order to validate the exposure area recognized as invalid in FIG. 6B by the final shot 6 of the exposure shots 1 to 6, the focus measurement value of the shot 6 immediately before the exposure area is used. By printing the exposure area, it is possible to make the exposure area 104 effective.

  When using this exposure shot, in order to create the wafer map of FIG. 1 and recognize that it is an effective shot, the focus measurement of the shot is not performed under the exposure conditions of the exposure apparatus, It is assumed that information on using the focus measurement value of the final exposure shot 6 and using the measurement value of the exposure shot at the same time as tilt correction is given in advance. These pieces of information correspond to software in the exposure apparatus, and can be printed as an effective exposure area 104 as described above by inputting the information when creating the wafer map in FIG. 1 and operating the exposure apparatus. Become. As a result, it is possible to maintain good quality and increase the number of good products on the substrate without reducing productivity.

  Similarly, by using the focus value of the exposure shot 9 shown in FIG. 2, the exposure shot 606 shown in FIG. The exposure area 106 can be printed.

  FIG. 3 shows the result of confirming the quality and confirming the number of products obtained by applying this to an apparatus (stepper) that performs exposure with the reticle and the substrate fixed based on the present embodiment. As shown in the figure, according to the non-defective calculation when the vertical axis represents the yield and the horizontal axis represents the number of effective chips in the shot, the number of non-defective products in the shot by changing the invalid shot to the valid shot is Decreases relative to the number of non-defective products within the effective shot. Although the yield rate of products will decline, the decline in yield rate on the entire board due to invalid shots being effective shots is expected to be within 10%. Therefore, the number of products can be increased without degrading quality.

  In addition, as shown in FIG. 4, the first non-defective product calculation when applied to an apparatus (scanner) that moves the reticle and the substrate at the same time to perform exposure is as follows. If the invalid shot is changed to an effective shot, the non-defective product rate within the effective shot also decreases. is expected. Therefore, the number of products can be increased without degrading quality.

  Furthermore, in the second non-defective product trial calculation when applied to the scanner as shown in FIG. 5, the non-defective product rate in the shot of the valid shot is the product of the product in the valid shot by changing the invalid shot to the valid shot. There is no difference with the yield rate, and it is expected that the number of products can be increased without degrading quality.

  From the above results, it is estimated that by enabling invalid exposure areas, the number of picks can be increased without degrading quality, and the number of picks for representative varieties can be increased by 1.1%. can do.

  In addition, in order to validate the first exposure area and the last exposure area that can be recognized as invalid in the first row of exposure shots, the focus measurement of the exposure shot immediately before the corresponding exposure shot described above is performed. Instead of using the value, the focus measurement value of the exposure shot immediately after (one after) the exposure shot can be used, and the same effect as described above can be obtained.

  That is, at the position of exposure shot 0 in FIG. 2, the focus measurement of the corresponding shot is not performed as the exposure condition of the exposure machine, the focus measurement value of exposure shot 1 immediately after that is used, and the tilt correction is simultaneously performed. By giving information on the use of the next measured value in advance and designating the exposure order, after the exposure shot of the effective shot based on the exposure shot 1 next to the invalid shot based on the exposure shot 0, the invalidity is temporarily set. The shot is returned to the shot location, and after the effective shot is exposed to the next exposure shot, the shot based on the exposure shot 0 is printed as an effective exposure area 105.

  The information corresponds to the software in the exposure apparatus. As described above, the information is input at the time of creating the wafer map, and the exposure apparatus is operated to burn as the effective exposure area 105 as described above. As described above, the number of good products on the substrate can be increased without reducing productivity while maintaining good quality.

  In the present invention, the product pattern can be printed in a form in which the exposure area by the exposure shot to the prohibited band for focus measurement on the substrate is validated, so that the cost increase accompanying the miniaturization of the pattern to be created on the substrate and the It is possible to respond to issues such as the effective use of the exposure area where patterns can be printed on the surface, increasing the number of non-defective products with stable quality, and reducing product costs at a low cost. This is an effective technique for semiconductor manufacturing processes.

101 Substrate 102 Focus measurement effective area 103 Exposure area (effective)
104 Exposure area (effective)
105 Exposure area (effective)
106 Exposure area (effective)
107 products

Claims (2)

  An exposure method in which a main surface of a substrate is divided into a plurality of exposure areas including its outer edge, and exposure is performed when an exposure area having a center outside the outer edge of the substrate is exposed. An exposure method comprising exposing the exposure region using a focus measurement value and a substrate tilt measurement value in an immediately preceding exposure region without performing measurement and substrate tilt measurement.   An exposure method in which a main surface of a substrate is divided into a plurality of exposure areas including its outer edge, and exposure is performed when an exposure area having a center outside the outer edge of the substrate is exposed. An exposure method comprising exposing the exposure region using a focus measurement value and a substrate tilt measurement value in an immediately following exposure region without performing measurement and substrate tilt measurement.

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