JP2012009720A - Wafer holder and exposure equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease adsorption distortion which causes an exposure error even if particles are adhered to a wafer support face of a pin in a wafer holder.SOLUTION: A wafer holder 1 is provided with a groove 6b on a wafer support surface 6a. A contact area between a wafer support member 6 and a wafer is decreased by a projection area of the groove 6b. Consequently, occurrence frequency of a situation in which particles are caught between the wafer holder 1 and the wafer when the wafer holder 1 adsorbs and holds the wafer can be decreased.

Description

  The present invention relates to a wafer holder for attracting and holding a wafer made of a material such as a semiconductor, glass, or ceramic.

  This type of wafer holder is provided in an exposure apparatus used for manufacturing a semiconductor circuit or the like (see, for example, Patent Document 1). As this wafer holder, a holder substrate in which a large number (for example, 30,000 to 50,000) of minute pins are erected at a predetermined interval and a wafer support surface is formed on the top of each pin is used. Yes.

Japanese Patent Laid-Open No. 10-177942

  However, in such a wafer holder, since the number of pins is large, particles (fine particles such as dust) may adhere to the wafer support surface of the pins in the process up to exposure by the exposure apparatus. Assuming such a case, when the wafer is sucked and held by the wafer holder, the wafer sucking that causes the exposure error is avoided as much as possible to prevent the occurrence of an exposure error by interposing particles between the wafer holder and the wafer. It is desired to eliminate distortion as much as possible.

  SUMMARY OF THE INVENTION In view of such circumstances, the present invention provides a wafer holder and an exposure apparatus capable of reducing wafer suction distortion that causes an exposure error even when particles are attached to the wafer support surface of the pins. The purpose is to provide.

  In the first wafer holder according to the present invention, the wafer support member (3, 4, 6) is provided on the holder substrate (2), and the wafer (W) is provided on the wafer support surface (3a, 4a, 6a) of the wafer support member. Can be formed to form a sealed space (S) surrounded by the wafer and the holder substrate, and by making the sealed space negative pressure, the wafer can be sucked and held on the wafer support member. A wafer holder (1), wherein the wafer support surface is provided with a groove (6b).

  An exposure apparatus according to the present invention is an exposure apparatus (30) having the wafer holder (1) according to any one of claims 1 to 4.

  Here, in order to explain the present invention in an easy-to-understand manner, the description has been made in association with the reference numerals of the drawings representing the embodiments. However, it goes without saying that the present invention is not limited to the embodiments.

  According to the present invention, since the groove is provided on the wafer support surface of the wafer holder, the contact area between the wafer support member and the wafer is reduced by the projected area of the groove. As a result, even when particles adhere to the wafer support surface, it is possible to reduce the frequency of occurrence of a situation in which particles are sandwiched between the two when the wafer is attracted and held by the wafer holder. Therefore, it is possible to reduce the wafer suction distortion that causes an exposure error.

1 is a configuration diagram showing a basic configuration of an exposure apparatus according to Embodiment 1 of the present invention. FIGS. 2A and 2B are front views showing the vicinity of the wafer holder of the exposure apparatus shown in FIG. 1, in which FIG. 1A is a state diagram in which the wafer is held on the center up, and FIG. It is a figure which shows the wafer holder which concerns on the same Embodiment 1, Comprising: (a) is the perspective view, (b) is the expansion longitudinal cross-sectional view. It is a perspective view which shows the pin of the wafer holder which concerns on Embodiment 2 of this invention. It is a perspective view which shows the pin of the wafer holder which concerns on Embodiment 3 of this invention.

Embodiments of the present invention will be described below.
Embodiment 1 of the Invention

  In the first embodiment, pins 6 and ring-shaped seals 3 and 4 are used as a wafer support member, pins 6 are used as protrusions, and vacuum suction holes 7 are used as ventilation means.

  1 to 3 are diagrams according to Embodiment 1 of the present invention. 2 and 3 are illustrated with emphasis on ease of understanding, the dimensional ratio of each component is not necessarily accurate.

  As shown in FIG. 1, the exposure apparatus 30 according to the first embodiment includes an illumination optical system 32, and the illumination optical system 32 includes an alignment optical system 36. A light source 33 is disposed in the vicinity of the illumination optical system 32 (on the left side in FIG. 1) so as to supply exposure light such as ultraviolet rays to the illumination optical system 32.

  Further, as shown in FIG. 1, a mask stage 37 for placing the mask R is installed below the illumination optical system 32 so as to be movable in a horizontal direction (a direction perpendicular to the vertical direction in FIG. 1). . A mask exchange system 38 is disposed in the vicinity of the mask stage 37 (left side in FIG. 1), and the mask stage 37 can be moved in the horizontal direction by the mask exchange system 38.

  Further, as shown in FIG. 1, a wafer stage 31 is installed below the mask stage 37 so as to be movable in the horizontal direction. On the wafer stage 31, a wafer W having a surface coated with a photosensitive agent is placed. Can be placed. A stage control system 35 is disposed in the vicinity of the wafer stage 31 (left side in FIG. 1). The stage control system 35 can move the wafer stage 31 in the horizontal direction.

  A projection optical system 34 for projecting the pattern of the mask R on the mask stage 37 onto the wafer W on the wafer stage 31 is installed between the mask stage 37 and the wafer stage 31 as shown in FIG. Has been.

  Further, as shown in FIG. 1, the exposure apparatus 30 includes a main control unit 39. The main control unit 39 includes the alignment optical system 36, the light source 33, the mask exchange system 38, and the stage control system 35 described above. It is connected.

  As shown in FIG. 2, the wafer stage 31 includes a wafer base 21, a Y stage 22, an X stage 23, a Z tilt drive unit 24, a sample stage 25, a wafer holder 1, an expansion / contraction mechanism 27, and a center up 26. The center-up 26 has three columnar spindle portions 26a, 26b, and 26c. Here, the Y stage 22 is mounted on the upper side of the wafer base 21 so as to be movable in the Y direction (direction perpendicular to the paper surface of FIG. 2), and the X stage 23 is placed on the upper side of the Y stage 22 in the X direction (FIG. 2). It is mounted movably in the left and right direction. A sample stage 25 is supported on the upper side of the X stage 23 via a Z tilt drive unit 24, and an alumina wafer holder 1 is fixed to the upper side of the sample stage 25. Further, a center up 26 is supported on the upper side of the X stage 23 through a telescopic mechanism 27 so that the center up 26 can be moved up and down. It is in a fitted state.

  Therefore, in this wafer stage 31, by extending the expansion / contraction mechanism 27 and raising the center up 26, the wafer W can be held on the center up 26 as shown in FIG. By contracting the expansion / contraction mechanism 27 and lowering the center up 26, the wafer W can be held on the wafer holder 1 as shown in FIG.

  The wafer holder 1 has a disc-shaped holder substrate 2 as shown in FIG. On the surface 2 a of the holder substrate 2, a ring-shaped seal 3 having a trapezoidal cross section is formed integrally with the holder substrate 2 in the form of being arranged in an annular shape at the periphery. Further, in the holder substrate 2, three circular center-up pin holes 5 are arranged in the vicinity of the center of the holder substrate 2 at equal angular intervals (that is, 120 ° intervals) on the circumference. The holder substrate 2 is formed to penetrate from the front surface 2a to the back surface 2b in the thickness direction. The center-up pin holes 5 are loosely fitted with the spindle portions 26a, 26b, and 26c of the center-up 26 described above. Cylindrical annular seals 4 are formed around the center up pin holes 5 respectively. Further, on the surface 2 a of the holder substrate 2, 30,000 to 50,000 frustum-shaped minute pins 6 are formed integrally with the holder substrate 2 in a form in which the pins 6 are arranged almost evenly. Further, in the holder substrate 2, six circular vacuum holes 7 are arranged on the straight line along the radial direction of the holder substrate 2 at equal angular intervals, respectively, from the front surface 2a to the back surface 2b of the holder substrate 2. The holder substrate 2 is formed so as to penetrate in the thickness direction.

Further, as shown in FIG. 3B, wafer support surfaces 3a and 4a are formed flat on the tops of the annular seals 3 and 4, respectively. On the other hand, as shown in FIG. 3, each pin 6 has a wafer support surface 6a formed flat on the top. A groove 6b is formed in a straight line on the wafer support surface 6a, and both ends of the groove 6b are opened in a sealed space S described later. As a method of forming the groove 6b of the pin 6, laser processing that performs fine processing using a laser beam such as an excimer laser or a CO ₂ laser is preferable in that no processing distortion remains. A wafer suction surface P is virtually formed on the wafer holder 1 so as to connect the wafer support surfaces 3a, 4a, and 6a.

  When the wafer W is placed on the wafer suction surface P of the wafer holder 1, the wafer W is in contact with the wafer support surfaces 3a and 4a of the annular seals 3 and 4 and the wafer support surface 6a of each pin 6 simultaneously. Thus, as shown in FIG. 3B, the sealed space S is formed in a form surrounded by the wafer W and the holder substrate 2. In this state, the operation in which the gas in the sealed space S is exhausted to the outside through the vacuum suction hole 7 to make the sealed space S have a negative pressure, that is, the vacuum suction operation is performed, so that the wafer W becomes the annular seal 3, 4. The wafer W can be sucked and held by the wafer holder 1 while being in contact with the wafer support surfaces 3 a and 4 a and the wafer support surface 6 a of each pin 6.

  The size of the holder substrate 2 is 150 to 450 mm in diameter and 8 to 19 mm in thickness. The size of the zonal seal 3 is 150 to 300 μm in width and 30 to 500 μm in height. Each ring-shaped seal 4 has a width of 150 to 300 μm and a height of 30 to 500 μm. The size of the center up pin hole 5 is 8 mm in diameter. Each pin 6 has a tip diameter of 150 to 300 μm and a height of 30 to 500 μm. The interval between the pins 6 is 1.6 to 2.2 mm. The groove 6b of each pin 6 has a width of 50 to 70 μm and a depth of 5 to 30 μm. The size of each vacuum hole 7 is about 0.5 to 3 mm in diameter.

  And when manufacturing devices, such as a semiconductor device, using this exposure apparatus 30, it follows the following procedure.

  First, the mask R is placed on the mask stage 37. In addition, after placing the wafer W on the wafer holder 1 of the wafer stage 31, the wafer W is attracted and held by the wafer holder 1 by performing the above-described vacuuming operation.

  In this state, based on a command from the main controller 39, exposure light is irradiated from the light source 33 to the illumination optical system 32, and the pattern of the mask R is projected onto the wafer W and transferred.

  Thereafter, the wafer W is separated from the wafer holder 1 by releasing the vacuuming operation.

  Finally, if various post-treatments are performed on the wafer W, the device is completed.

  In the manufacturing process of such a device, since the grooves 6b are provided on the wafer support surface 6a of each pin 6 of the wafer holder 1, the pins 6 and the wafer W are separated by the projected area of these grooves 6b. The contact area is reduced. As a result, even when particles are adhered to the wafer support surface 6a of the pins 6, when the wafer W is attracted and held by the wafer holder 1, the frequency of occurrence of a situation where the particles are sandwiched between the two can be reduced. it can. Therefore, it is possible to reduce the suction distortion of the wafer W that causes an exposure error.

  Moreover, since these grooves 6b are opened in the sealed space S, the inside of the grooves 6b becomes negative pressure when the wafer W is sucked and held. Therefore, even when particles are attached to the wafer support surface 6a of the pins 6, these particles can be discharged via the grooves 6b. Therefore, it is possible to further reduce the suction distortion of the wafer W that causes an exposure error.

Further, since the grooves 6b are provided in the wafer support surface 6a of each pin 6 of the wafer holder 1, and these grooves 6b are opened in the sealed space S, all the grooves are released when the vacuuming operation is canceled. Air flows rapidly into 6b. Therefore, the wafer W can be separated from the wafer holder 1 simultaneously with the release of the evacuation operation, and the occurrence of linking (that is, a phenomenon in which the wafer W remains stuck to the wafer holder 1 even if the evacuation operation is released). It can be avoided. As a result, the number of processed wafers W (throughput) can be increased.
[Embodiment 2 of the Invention]

  FIG. 4 is a diagram according to Embodiment 2 of the present invention.

  In the wafer holder 1 according to the second embodiment, as shown in FIG. 4, the first embodiment described above except that the grooves 6 b formed on the wafer support surface 6 a of the pins 6 are not straight but cross-shaped. It has the same configuration. The cross-shaped groove 6b has four end portions opened to the sealed space S.

Therefore, the second embodiment has the same effects as the first embodiment described above.
Embodiment 3 of the Invention

  FIG. 5 is a diagram according to Embodiment 3 of the present invention.

  The wafer holder 1 according to the third embodiment has the same configuration as that of the above-described first embodiment except that the groove 6b is not opened in the sealed space S as shown in FIG.

Therefore, in the second embodiment, since the grooves 6b are provided in the wafer support surface 6a of each pin 6 of the wafer holder 1, the contact between the pins 6 and the wafer W is equivalent to the projected area of these grooves 6b. The area is reduced. As a result, in the manufacturing process of the device using the exposure apparatus 30, even when particles are attached to the wafer support surface 6 a of the pins 6, It is possible to reduce the frequency of occurrence of a situation where particles are sandwiched between them. Therefore, it is possible to reduce the suction distortion of the wafer W that causes an exposure error.
[Other Embodiments of the Invention]

  In the first and third embodiments described above, the case where the grooves 6b formed on the wafer support surface 6a of the pins 6 are in a straight line will be described. In the second embodiment described above, the wafer support surface 6a of the pins 6 is described. The case where the groove 6b formed in the shape of a cross is in the shape of a cross. However, the shape of the groove 6b is not limited to these, and may be, for example, a “two” shape, a “three” shape, a cross beam shape, a * shape, a star shape, a concentric shape, or a spiral shape. .

  In the first embodiment described above, the case where both ends of the straight groove 6b formed in the pin 6 are open to the sealed space S will be described. In the second embodiment described above, the pin 6 is formed on the pin 6. The case where four end portions of the formed cross-shaped groove 6b are open to the sealed space S has been described. However, in order to achieve the effects described in the first and second embodiments, it is sufficient that at least one portion of the groove 6b is opened.

  In the first to third embodiments, the wafer holder 1 in which the pins 6 are formed with the grooves 6b on the wafer support surface 6a has been described. However, as long as the above-described evacuation operation is not hindered, the same applies to the wafer support surfaces 3a and 4a of the annular seals 3 and 4 in place of the grooves 6b of the pins 6 or in addition to the grooves 6b of the pins 6. It is also possible to form grooves.

  In the above-described first to third embodiments, the case where the protrusion is the pin 6 has been described. The present invention can be similarly applied to a wafer holder 1 having a pyramid shape and the like.

  In the first to third embodiments, the alumina wafer holder 1 has been described. However, materials other than alumina (for example, Altic (alumina + TiC ceramics), SiC, SiC-CVD SiC (SiC substrate surface coated with SiC by chemical vapor deposition (CVD)), AlN, low thermal expansion ceramics It is also possible to apply the present invention to the wafer holder 1 composed of the like.

  In the first to third embodiments described above, the wafer holder 1 has been described in which six circular vacuum holes 7 having a diameter of about 0.5 to 3 mm are arranged on the holder substrate 2 in a straight line at equal angular intervals. However, the size, shape, number, and arrangement method of the evacuation holes 7 can be arbitrarily set as long as the evacuation function is achieved when the wafer W is attracted and held on the wafer adsorption surface P of the wafer holder 1.

  In the first to third embodiments described above, the case where the ventilation means is the vacuum suction hole 7 has been described. However, ventilation means other than the vacuum suction hole 7 (for example, a ventilation groove) can be used instead or in combination. .

  Further, in the first to third embodiments, the case where the groove 6b of the pin 6 is formed by laser processing has been described. However, the method of forming the groove 6b of the pin 6 is not limited to laser processing. For example, the groove 6b of the pin 6 can be formed by sandblasting, dry etching, wet etching, or the like.

  The present invention is particularly useful for an exposure apparatus that requires accuracy of flatness.

DESCRIPTION OF SYMBOLS 1 ... Wafer holder 2 ... Holder substrate 2a ... Front surface 2b ... Back surface 3, 4 ... Ring zone seal (wafer support member)
3a, 4a ... Wafer support surface 5 ... Center up pin hole 6 ... Pin (protrusion, wafer support member)
6a …… Wafer support surface 6b …… Groove 7 …… Vacuum drawing hole (venting means)
21 …… Wafer base 22 …… Y stage 23 …… X stage 24 …… Z tilt drive unit 25 …… Sample stage 26 …… Center up 26a, 26b, 26c …… Spindle unit 27 …… Extension mechanism 30 …… Exposure Equipment 31 ... Wafer stage 32 ... Illumination optical system 33 ... Light source 34 ... Projection optical system 35 ... Stage control system 36 ... Alignment optical system 37 ... Mask stage 38 ... Mask exchange system 39 ... Main control Part P …… Wafer suction surface R …… Mask S …… Enclosed space W …… Wafer

Claims (5)

A wafer support member is provided on the holder substrate, and a wafer is placed on the wafer support surface of the wafer support member to form a sealed space surrounded by the wafer and the holder substrate. A wafer holder capable of attracting and holding the wafer on the wafer support member,
A wafer holder, wherein a groove is provided on the wafer support surface.   The wafer holder according to claim 1, wherein the groove opens to the sealed space.   The wafer support member includes a plurality of protrusions, and the wafer support surface is formed flat on the top of each protrusion, and the wafer is supported by contacting the wafer with the wafer support surfaces. The wafer holder according to claim 1, wherein:   4. The wafer holder according to claim 1, wherein the holder substrate is provided with ventilation means for exhausting the gas in the sealed space to make the sealed space have a negative pressure. 5. .   An exposure apparatus comprising the wafer holder according to claim 1.

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