Vacuum chuck and inspection device equipped with same

Abstract

To provide an apparatus for inspecting functions of semiconductor chips in a state of a wafer before dividing the wafer into individual chips even if the wafer is formed with a large warp.SOLUTION: A vacuum chuck includes a plurality of concentric first circumferential grooves 152 formed in the upper surface of a vacuum chuck body 190, a plurality of first holes 154 extending in the vertical direction and formed at intervals in the circumferential direction at respective positions of the plurality of first circumferential grooves, a first communicating hole 158 radially extending and radially communicating with the first hole, a plurality of second holes 132 circumferentially spaced apart at a plurality of concentric locations in the upper surface of the chuck body, a second communicating hole 136 radially extending and radially communicating with the second hole, a second circumferential groove 140 formed on the upper surface side of the chuck body and radially outside the position in which the first hole and the second hole are arranged, and a ring-shaped elastic body that fits into the second circumferential groove. The second circumferential groove is a dovetail groove with the top portion narrower than the bottom portion.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a vacuum chuck for suctioning a semiconductor wafer and an inspection device equipped with the same, and more particularly to a vacuum chuck suitable for suctioning a warped semiconductor wafer and an inspection device equipped with the same. [Background technology]

[0002] As semiconductor devices become faster and more highly integrated, wafer level packages (WLPs) are becoming more widely used, as they have the advantage of reducing the mounting area and the effective inductance of wiring. WLPs package chips on a wafer, and can provide greater bandwidth, speed, and reliability with less power consumption. These advantages enable a wider range of form factors to be offered for multi-chip packages used in mobile consumer devices, high-end supercomputing, games, artificial intelligence, and Internet-related products. In the High Bandwidth Memory (HBM), a type of WLP, multiple memories are stacked on one processor. In its production, a large number of ultra-wideband memory chips, which generally have a rectangular planar shape, are formed on a substrate made of a semiconductor wafer, and then the chips are cut into pieces about 100 to 200 mm in diameter. 2 The semiconductor wafer is divided into a large number of ultra-wideband memories, each about the size of a single chip. In the ultra-wideband memory, the processor and the memory section, in which multiple memories (DRAMs) are stacked vertically, are connected via a silicon interposer, and the connection between the processor and the memory section is connected and placed on the substrate via the silicon interposer.

[0003] When carrying out a functional test of the ultra-wideband memory thus formed, it is clear that the test efficiency is improved by testing each ultra-wideband memory in the wafer state immediately before division, rather than testing each individual ultra-wideband memory chip formed by dividing the semiconductor wafer. In order to collectively test the ultra-wideband memories in the undivided semiconductor wafer state, the semiconductor wafer needs to be flat so that the test probe can be easily positioned at a predetermined position while protecting it. However, as described below, a wafer on which an ultra-wideband memory is formed may be warped, and so a method of individually testing the ultra-wideband memories divided from the semiconductor wafer is currently used.

[0004] On the other hand, there are attempts to inspect general semiconductor chips, not ultra-wideband memories, formed on warped semiconductor wafers while still in the semiconductor wafer state. In a 12-inch wafer with a diameter of φ300 mm on which ultra-wideband memories are formed, the number of ultra-wideband memories may be, for example, 400 or more. Even if the diameter of such a wafer is increased, its thickness is only several hundred μm, so the rigidity of the entire wafer is low, and the wafer is prone to warping and undulation (deformation) due to external forces applied during wafer processing, especially during packaging. Wafer warping is indicated by the difference in height between the periphery and the center, and the value may be several mm.

[0005] However, if the peripheral part of a large-diameter wafer is warped and deformed more than the central part, even if the peripheral part is vacuum-sucked when the wafer is placed on the chuck, the surrounding air is sucked in with the conventional suction diameter, and the peripheral part of the wafer is not sucked into the chuck and the warped state is maintained. If an inspection is performed in a warped state, the inspection probe will contact the wafer surface at an angle, and in the worst case, there is a risk of damaging the wafer or the expensive probe. In order to eliminate such defects caused by the warped wafer, various methods have been proposed to cancel the warp of the wafer during the inspection of the wafer.

[0006] Patent Document 1 describes that the flatness of a substrate such as a wafer having a large warp can be well maintained even when the substrate is held by suction. Specifically, an annular recess is formed in a position surrounding the opening of the communication path on the upper surface of the base, and a lower element of a sealing member made of an annular elastic material is placed in the annular recess. Meanwhile, an upper element of the sealing member is protruded from the upper surface of the base. The upper element is provided with a first portion extending upward while facing inward of the ring, and a second portion extending upward while facing outward of the ring.

[0007] Patent Document 2 also describes that a work stage that vacuum-adsorbs a warped workpiece includes a base having a recess for supplying vacuum, and a suction plate with multiple through holes that is attached to the recess. It also describes that a sealing elastic body is provided on the periphery of the suction plate that adsorbs and holds the warped workpiece.

[0008] Patent Document 3 describes that a wafer processing machine has a suction cup structure that can suction and hold a wafer without being affected by the flatness of the wafer. Specifically, a cylinder made of an elastic material, such as a rubber plate, is provided on the outer periphery of the suction cup, which spreads out like a skirt and extends a predetermined length from the suction surface of the suction cup. As a result, even if a gap occurs between the wafer surface and the suction surface, the cylinder elastically deforms in response to the warping, undulation, or step of the wafer surface and adheres closely to the wafer surface, forming an enclosure. As a result, the gap can be sealed, preventing air and grinding fluid from being sucked in through the suction groove. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2019-4017 A [Patent Document 2] JP 2010-153419 A [Patent Document 3] Japanese Patent Application Publication No. 7-308856 Summary of the Invention [Problem to be solved by the invention]

[0010] In the vacuum chuck described in Patent Document 1, an annular recess is formed on the periphery of a substantially circular ceramic base, and a seal member made of an elastic body is disposed in the annular recess. The elastic body is bellows-shaped and contacts the wafer at its upper end surface. When vacuum-adsorbed, the bellows-shaped or bellows-shaped elastic body expands and contracts to adsorb the wafer to the base without changing the contact position between the wafer and the elastic body. This flattens the wafer and holds it in a predetermined position.

[0011] However, in the vacuum chuck described in Patent Document 1, when the bellows-shaped elastic body is compressed, it is necessary to provide a large groove in the ceramic base to accommodate the elastic body. In addition, since the elastic body is bellows-shaped and not a simple shape, when it is compressed, a part of the elastic body may deviate from smooth deformation and protrude between the upper surface of the ceramic base and the back surface of the wafer in the in-plane direction. If the elastic body protrudes from the groove, there is a risk that foreign matter will adhere to the back surface of the wafer, and if foreign matter adheres, the wafer may be damaged by the suction force when the wafer is sucked. Furthermore, the wafer cannot be positioned at the appropriate position for inspection, and the height of the wafer in the suction direction changes, making it impossible to ensure flatness, and there is a risk of a collision phenomenon with the probe occurring. If the function inspection of the ultra-wideband memory is an inspection under a temperature controlled environment, such as a low-temperature function inspection or a high-temperature function inspection, there is a risk that the set temperature will be shifted if the wafer position is not appropriate.

[0012] In the work stage described in Patent Document 2, a sealant is placed near the periphery of a rectangular base, a workpiece is placed on top of it, and a rectangular suction plate with a hole is placed in the space inside the base partitioned by the sealant.The sealant is shrunk by vacuum suction from the back side of the rectangular suction plate, and the workpiece is made to conform to the flat suction plate.

[0013] However, since this work stage is used for exposure, etc., if a workpiece with a large warp at the periphery is placed on the work stage in a downward convex shape, before vacuum suction, the workpiece will not come into contact with the sealing material, but the center will come into contact with the suction plate, making it difficult to eliminate the warp of the workpiece and suck it. In order to make such a workpiece come into contact with the sealing material before vacuum suction, the height of the sealing material can be increased, but even if the height of the sealing material is increased, the center of the sealing material, which is close to the suction plate, will come into contact with the suction plate immediately during vacuum suction, and the workpiece will tend to be adsorbed while maintaining its warp or with only a slight reduction in warp. On the other hand, if the workpiece is placed on the work stage in an upward convex shape, it is possible for the workpiece to come into contact with the sealing material before vacuum suction. However, in the center of the part partitioned by the sealing material, the distance from the suction plate is too long, making it difficult to obtain a sufficient vacuum suction effect, and the warp will be maintained.

[0014] In the wafer processing machine described in Patent Document 3, a chuck holds a warped wafer by vacuum suction during processing such as peripheral grinding of the wafer. The chuck has an elastic body on the outer periphery, and after the back surface of the wafer is abutted against the elastic body, the wafer is held by the chuck by vacuum suction. At the same time, the wafer is abutted against the elastic body to eliminate a gap between the chuck and the wafer, preventing grinding water and the like from entering the back surface of the wafer. However, the processing machine described in this publication only needs to prevent the intrusion of grinding water, and does not take into consideration the correction of the warp of the wafer itself. In other words, no problem occurs even if peripheral grinding and the like is continued with the wafer in a warped shape.

[0015] The present invention has been made in consideration of the above-mentioned problems of the conventional technology, and has an object to enable functional inspection of semiconductor chips in the wafer state before being divided into individual chips, even in the case of a wafer having a large diameter and therefore a large warp at its peripheral portion. Preferably, it also has an object to enable functional inspection of semiconductor chips in the wafer state all at once. The functional inspection includes a test in a temperature environment, and it also has an object to realize a uniform temperature environment for all semiconductor chips formed on the wafer. The present invention has an object to achieve at least one of these multiple objects. [Means for solving the problem]

[0016] The present invention, which achieves the above object, is characterized in that a vacuum chuck has a disk-shaped chuck body for vacuum-suctioning a semiconductor wafer, the vacuum chuck having a plurality of concentric first circumferential grooves formed on an upper surface of the chuck body, a plurality of first holes extending in a vertical direction of the chuck body and formed at intervals in a circumferential direction at the positions of each of the plurality of first circumferential grooves, a first communication passage extending in a radial direction of the chuck body and communicating the first holes in the radial direction, and a plurality of first communication passages extending in a circumferential direction at a plurality of concentric positions on the upper surface of the chuck body. a second communication passage extending in the radial direction of the chuck body and communicating the second holes in the radial direction of the chuck body; a second circumferential groove formed on the upper surface of the chuck body radially outward from the positions at which the first holes and the second holes are arranged; and a ring-shaped elastic body fitted into the second circumferential groove, the second circumferential groove being a dovetail groove formed so that the radial width at the upper surface of the chuck body is narrower than the radial width at the bottom surface.

[0017] Another feature of the present invention for achieving the above object is a vacuum chuck having a disk-shaped chuck body for vacuum-suctioning a semiconductor wafer, the vacuum chuck comprising: a plurality of concentric first circumferential grooves formed on an upper surface of the chuck body; a plurality of first holes extending in a vertical direction of the chuck body and spaced apart in a circumferential direction at the positions of each of the plurality of first circumferential grooves; first communication passages extending in a radial direction of the chuck body and communicating the first holes in the radial direction; the chuck body having a plurality of second holes formed at positions spaced apart circumferentially from each other, a second communicating passage extending in the radial direction of the chuck body and communicating the second holes in the radial direction of the chuck body, a second circumferential groove formed on the upper surface side of the chuck body radially outward from the positions at which the first holes and the second holes are arranged, and a ring-shaped elastic body fitted into the second circumferential groove, the elastic body being formed into a ring-shaped tube or a solid O-ring shape made of a foamed material.

[0018] In these features, the chuck body may further include a plurality of concentric third circumferential grooves formed on the upper surface thereof, a plurality of third holes extending in the vertical direction of the chuck body and spaced apart in the circumferential direction at the positions of each of the third circumferential grooves, and a third communication passage extending in the radial direction of the chuck body and communicating the third holes in the radial direction, and the third holes may include a hole located radially inward of the first holes and the second holes. Note that the first communication passage may be used as the third communication passage.

[0019] In the above-mentioned features, it is preferable that the hole diameter of the plurality of second holes is formed to be larger than the hole diameter of the first hole, and in the vacuum chuck, a heater for heating the vacuum chuck, or a coolant passage through which a coolant capable of cooling the heater and the vacuum chuck flows, may be arranged below the portion where the first communicating passage and the second communicating passage are formed, and the sum of the radial arrangement of the first holes and the third holes may be greater than the radial arrangement of the second holes.

[0020] Yet another feature of the present invention that achieves the above object is that a wafer inspection apparatus includes a vacuum chuck having any of the above features and a probe card that can collectively measure multiple semiconductor chips formed on the upper surface of the wafer. Effect of the Invention

[0021] According to the present invention, in a vacuum suction chuck for suctioning a wafer and used for functional testing of the wafer, an annular groove is formed near the outer periphery of the vacuum suction chuck, an elastic body is disposed in the vacuum suction chuck and fits into the groove, protruding from the groove higher than the amount of warping of the wafer before vacuum suction, and a vacuum suction passage is formed that opens near the groove, so that functional testing of semiconductor chips can be performed on the wafer before it is divided into individual chips. Also, a uniform temperature environment can be achieved for all the semiconductor chips formed on the wafer. [Brief description of the drawings]

[0022] [Figure 1] 1 is a front view of an embodiment of an inspection device according to the present invention; [Diagram 2] FIG. 2 is a diagram showing an example of a semiconductor wafer inspected by an inspection device; [Diagram 3] 1 is a perspective view of one embodiment of a vacuum chuck according to the present invention; FIG. [Figure 4] FIG. 4 is a top view of the vacuum chuck shown in FIG. [Diagram 5] FIG. 2 is a schematic cross-sectional view of a vacuum chuck. [Figure 6] 5 is a cross-sectional view showing a detailed shape of a suction part of the vacuum chuck shown in FIG. 4. [Figure 7] 4 is a cross-sectional view illustrating vacuum suction of a wafer. FIG. [Figure 8] FIG. 1 is a block diagram of a system for heating and cooling a vacuum chuck. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] An embodiment of a vacuum chuck suitable for wafer inspection according to the present invention and an inspection apparatus equipped with the same will be described below with reference to the drawings. FIG. 1 is a front view of an embodiment of a wafer inspection apparatus 200 equipped with a vacuum chuck 100 according to the present invention. In this wafer inspection apparatus 200, electrical inspection is performed by simultaneously contacting a plurality of probes 264 of a probe card 266 with pads of a semiconductor chip formed on a semiconductor wafer (hereinafter also referred to as a wafer) W. In the electrical inspection, the operating state under various temperature conditions is also checked. For this reason, a means for heating and cooling the wafer W is generally provided.

[0024] 1, the wafer inspection apparatus 200 includes a base 236, a moving base 242 provided on the base 236, and an XYZ-Θ table 240. A vacuum chuck (hereinafter also referred to as a chuck) 100 according to the present invention is disposed on the upper surface of the XYZ-Θ table 240, on which a wafer W is placed and which vacuum-adsorbs the wafer W. As will be described in detail later, the vacuum chuck 100 is connected to a temperature control system 300 provided in the control device 210, and the temperature of the wafer W placed on the vacuum chuck 100 can be controlled. In addition, a vacuum exhaust device 270 such as a vacuum pump is connected to the vacuum chuck 100 to ensure vacuum adsorption of the wafer W.

[0025] The XYZ-Θ table 240 includes an X-axis table 244 for moving the wafer W in the X direction (left-right direction in the figure), a Y-axis table 246 for moving the wafer W in the Y direction (depth direction in the figure), and a Z-axis table 248 for moving the wafer W in the Z direction (up-down direction in the figure). The XYZ-Θ table 240 further includes a Θ table 252 for rotating the wafer W around a vertical axis.

[0026] Support columns 218 are provided on the sides surrounding the XYZ-Θ table 240, and a head stage 234 is provided above the table. An opening is provided in a portion of the head stage 234, and a card holder 262 is attached to the opening. A probe card 266 corresponding to a semiconductor chip 450 (see FIG. 2(a)) to be inspected formed on the wafer W is attached to the card holder 262. Furthermore, a plurality of probes 264 that come into contact with the semiconductor chip 450 are arranged on the probe card 266. The probes 264 have a delicate structure to specifically come into contact with minute terminals on the order of μm formed on the chip 450, and are structured not to apply excessive load. Therefore, the probes 264 are set to approach the wafer W in a predetermined posture and at a predetermined speed during inspection.

[0027] A test head 220 is rotatably provided on the upper end of the support 218. A contact cylinder 268 is provided on the surface of the test head 220 that faces the probe card 266 when the test head 220 rotates, and transmits information detected by the probes 264 to the control device 210 via the test head 220.

[0028] The XYZ-Θ table 240 can move in the left-right direction in the figure via the moving base 242. When the wafer W is transported by the transport unit 230, the XYZ-Θ table 240 moves to the wafer information acquisition / setting position 204 on the right side in the figure, and after placing and suctioning the wafer W on the vacuum chuck 100, acquires position information and chip 450 information using the camera 232 fixed to the head stage 234 and the like. After acquiring the wafer information, the XYZ-Θ table 240 moves to the inspection position 202 on the left side in the figure, and performs inspection using the probe 264 all at once. Here, "all at once" means that the XYZ-Θ table 240 is driven while the wafer W is still suctioned on the vacuum chuck 100 to continuously inspect a plurality of chips 450, preferably all chips 450 formed on the surface of the wafer W.

[0029] Fig. 2 shows an example of a semiconductor wafer W that can be placed on and attracted by the vacuum chuck 100 according to the present invention. Note that the semiconductor wafer W that can be placed on and attracted by the vacuum chuck 100 is not limited to the one shown in Fig. 2, but any semiconductor wafer W can be placed on and attracted by the vacuum chuck 100. In particular, the present vacuum chuck 100 has a special feature in that it can attract even a warped semiconductor wafer W.

[0030] Fig. 2(a) is a top view of a semiconductor wafer W, and Fig. 2(b) is a schematic side view showing an example of a large number of semiconductor chips 450 formed on the semiconductor wafer W. The semiconductor wafer W is a so-called 12-inch wafer with a diameter of φ300 mm, and more than 400 chips 450, each with a width of about 13.3 mm and a length of about 10.9 mm, are formed on a surface on which an orientation flat is formed.

[0031] The semiconductor chip 450 shown in FIG. 2(b) is called an ultra-wideband memory (HBM: High Bandwidth Memory), and includes a processor 410 and a memory (DRAM) 420 stacked in multiple layers (four layers in the figure), with an interface (I / F) 426 disposed below the memory 420 in the stacked portion. The processor 410 and the memory 420 are connected via a silicon interposer (interposer) 430, and the integrated unit of the processor 410 and the memory 420 is connected to a semiconductor wafer substrate (silicon substrate) 400 via the silicon interposer 430. The processor 410 and the silicon interposer 430, the silicon interposer 430 and the semiconductor wafer substrate 400, and the silicon interposer 430 and the interface 426 are connected using terminals 412, 402, 422, etc. formed on the respective portions, and the memories 420 are connected to each other by lead wires 424. The semiconductor chip 450 formed in this manner can cause distortion of the semiconductor chip 450, which is formed to a thickness of several hundred μm, due to the difference in weight between the processor 410 and the stacked memory 420, and the processing method used to form the chip 450.

[0032] An embodiment of the vacuum chuck 100 according to the present invention, which is provided in the inspection device 200 shown in FIG. 1, will be described with reference to FIG. 3 to FIG. 6. FIG. 3 is a perspective view of the vacuum chuck 100, and FIG. 4 is a top view thereof. FIG. 5 is a schematic vertical cross-sectional view of a chuck body 190 provided in the vacuum chuck 100, showing various examples of a chuck having a means for heating and / or cooling the wafer W. FIG. 5(a) shows an example of a chuck having only a heating means, FIG. 5(b) shows an example of the most standard case in which a means for both heating and cooling is provided, and FIG. 5(c) shows an example of a chuck having both a heating means and a cooling means integrated with a vacuum suction unit. In FIG. 5, the left half is shown as a cross section taken at position B in FIG. 4, and the right half is shown as a cross section taken at position A or C in FIG. 4. Figure 6 is a diagram for explaining the details of the suction holes and vacuum seal formed in the chuck body 190, where Figure 6(a) is a vertical cross-sectional view of the chuck body 190 for explaining the positional relationship of the suction holes, and Figure 6(b) is a cross-sectional view for explaining the fitting state of the elastic body.

[0033] In the following description, the standard type vacuum chuck 100 shown in FIG. 5(b) will be taken as an example, but the same applies to the other vacuum chucks 100 shown in FIG. 5(a) and (c). As shown in FIG. 5(b), the vacuum chuck 100 includes a chuck body 190, which is a disk-shaped vacuum suction block located at the top, a disk-shaped cooling block 170 arranged below the chuck body 190, and a disk-shaped heating block 180 arranged below the cooling block 170. These blocks 190, 170, and 180 are integrated using bolts (not shown) or the like to form the cylindrical vacuum chuck 100. The cooling block 170 has a plurality of cooling liquid passages 172 formed therein, through which a cooling liquid such as cooling water cooled by a chiller flows. In addition, a heater 182 is provided in the heating block 180, and is wound in a spiral shape in multiple layers.

[0034] A vacuum suction block 190 forming the top part of the vacuum chuck 100 has conventionally been formed with a large number of holes and grooves for stably suctioning and holding the wafer W. In the present invention, in addition to these conventional holes and grooves, the vacuum chuck 100 is provided with new holes and grooves and an elastic body 110 that fits into the grooves so that it can accommodate a warped wafer W.

[0035] 3 and 4, the chuck body 190 is formed in a circular shape with a diameter larger than that of the wafer W, and a plurality of first suction holes 154 are formed in the radial direction in the portion on which the wafer W is placed in order to suck and fix the flat wafer W. These suction holes 154 are provided at a plurality of locations in the circumferential direction (four locations, positions C in the figure), and are formed in shallow grooves 152 formed in a large number of concentric circles. When the wafer W to be sucked has a diameter of about 300 mm, the number of grooves 152 is preferably 10 or more, more preferably 20 or more, and the number of suction holes 154 in the circumferential direction is preferably 4 or more.

[0036] The number of first suction holes 154 may be reduced on the center side (smaller diameter side) of the chuck body 190. The first suction holes 154 at the same circumferential position are connected to each other by a first communication passage 158 extending in the radial direction from the outer periphery. The outer periphery of the chuck body 190 is provided with vacuum suction pipe connections 120 to which fittings for vacuum suction are attached in accordance with the positions of the first communication passages 158 (see FIG. 3), and the vacuum suction pipe connections 120 are connected to a vacuum exhaust device 270 via pipes (see FIG. 1). As a result, the entire upper surface of the chuck body 190 is vacuum suctioned.

[0037] In this embodiment, a push pin is provided in the center of the chuck body 190 so that the wafer W can be easily removed from the vacuum chuck after the vacuum is released. For this reason, push pin holes 124 are formed at intervals in the circumferential direction in the vacuum chuck. In this way, various processes, including processes for disposing a temperature sensor described later, are performed in the center of the chuck body 190, so that the processes are concentrated therein. In order to avoid excessive processes, the first suction hole 154 is omitted near the center, and a third suction hole 156 for mainly vacuum-suctioning the center of the chuck body 190 is formed at a circumferential position different from the first suction hole 154 (position A in the figure). As in the case of the first suction hole 154, a third communication passage 160 is also formed for the third suction hole 156 from the outer periphery to the center of the chuck body 190. The diameters of the first suction hole 154 and the third suction hole 156 are set to be the same. By vacuum-suctioning the back surface of the wafer W using these first and third suction holes 154, 156, in the case of a flat wafer W, the wafer W can be fixed and held on the vacuum chuck 100 without any hindrance, and various inspections can be performed in the inspection device 200 according to the program. Note that in this embodiment, the third suction hole 156 and the third communication path 160 are provided in positions separate from the first suction hole 154 and the first communication path 158, but one of the multiple first communication paths 158 and the corresponding first suction hole 154 can also be used as the third communication path 160 and the third suction hole 156.

[0038] However, in the case of a large-diameter wafer W in which the semiconductor wafer substrate 400 of the wafer W is very thin relative to its outer diameter, particularly in the case of a wafer W on which a semiconductor chip 450 such as an HBM is formed, the amount of warping becomes large at the periphery, and even if the wafer W is sucked using only the first and third suction holes 154, 156, a gap may be generated between the wafer W and the vacuum chuck 100 at the periphery. In that case, as described above, when inspecting the wafer W, there is a risk that the probe 264 may come into contact with the surface of the wafer W in a position different from the normal position. The probe 264 for inspecting the wafer W is a delicate tool, and if it comes into contact with the wafer W in a position different from the normal or predetermined position, this may cause the expensive probe 264 to be damaged.

[0039] In order to prevent such a problem from occurring, the present invention provides a circumferential groove 140 and a second suction hole 132 for holding the wafer W, particularly its peripheral portion, flat. That is, a circumferential groove 140 into which a sealing elastic body 110 can be fitted is formed near the outer periphery at the position where a φ300 mm wafer is placed. Referring to Fig. 6(b), the cross section of groove 140 is substantially trapezoidal with rounded corners, and is a dovetail groove in which width W2 on the top surface side of chuck body 190 is narrower than width W1 on the bottom surface side.

[0040] The elastic body 110 that fits into the groove 140 is easily deformed, and the portion that protrudes from the groove 140 before vacuum suction remains within the width of the groove 140 during and after vacuum suction, does not shift position and does not get caught between the wafer W and the chuck body 190, and is ultimately entirely housed within the groove 140. The elastic body 110 is a tube made of silicone resin or tetrafluoroethylene resin, or a solid O-ring made of a foam material. Silicon resin is preferable as the foam material.

[0041] When the elastic body 110 is a tube made of tetrafluoroethylene resin, the tube 110 is cut to a predetermined length, formed into a ring shape, and held in the dovetail groove 140 while being deformed. When the tube 110 is held in the dovetail groove 140, the maximum diameter d1 portion of the tube 110 remains in the dovetail groove 140 while retaining almost the original outer diameter (corresponding to the nominal diameter) of the tube 110. In this state, the tube 110 has a natural height h0. This natural height h0 corresponds to the outer periphery of the wafer W to be inspected, or more precisely, the maximum allowable warpage of the wafer W at the position where the elastic body 110 abuts.

[0042] That is, when the amount of warpage of the wafer W at the position where it abuts against the elastic body 110 is h0 or less, the outer periphery of the wafer W is partitioned by the elastic body 110 when the wafer W is placed on the chuck body 190, and a sealed space can be formed between the chuck body 190 and the wafer W. This enables vacuum suction, as described below. On the other hand, when the warpage of the wafer W exceeds h0, a gap is formed at the periphery between the chuck body 190 and the wafer W, and there is a risk that empty suction will occur even if vacuum suction is performed to flatten the wafer W. Since the amount of warpage of most wafers W is 2 mm or less, the size of the dovetail groove 140 and the size of the tube 110 (diameter and thickness, or rigidity) are set so that h0 is 2 mm or more in this embodiment as well.

[0043] When the dovetail groove 140 is formed as described above, a sealed space can be formed between the chuck body 190 and the wafer W, but the sealed space is larger than the gap when vacuum suction is performed using the first suction hole 154 or the third suction hole 156, and a force must be generated to flatten the wafer W against the rigidity of the semiconductor wafer substrate 400 of the wafer W by suction. Therefore, in this embodiment, the second suction hole 132, which has a larger diameter than the first suction hole 154 or the third suction hole 156, is disposed at the center on the outer diameter side of the chuck body 190. As shown in FIG. 4, the second suction holes 132 are provided at a plurality of positions (four positions in this embodiment: positions B) different from the first and third suction holes 154 and 156 in the circumferential direction, and at a plurality of positions on the inner diameter side of the outer diameter position where the circumferential dovetail groove 140 is formed. In this embodiment, the second suction holes 132 are provided at five positions in the radial direction. The second suction holes 132 at the same circumferential position are communicated with each other by a second communication passage 136 formed from the outer periphery toward the center.

[0044] 6(a) shows the positional relationship of the first to third suction holes 154, 132, 156, the first to third communication passages 158, 136, 160, and the dovetail groove 140, overlapping in the circumferential direction. The diameters φD1 and φD3 of the first and third suction holes 154, 156 are about 1 mm, and they are formed at intervals in the radial direction of the chuck body 190. The first communication passage 158 that communicates the multiple first suction holes 154 stops at a position radially outward of the third communication passage 160 that connects the multiple third suction holes 156.

[0045] The second suction holes 132, which are mainly used to correct the warpage on the outer periphery of the wafer W, are formed with a diameter φD2 of about 2 to 3 mm, which is several times the diameters of φD1 and φD3, and are formed at a plurality of positions between the first suction holes 154 in the radial direction and centered on the large diameter side of the chuck body 190. The second communication passages 136 that communicate with the second suction holes 132 extend from the outer periphery of the chuck body 190 toward the center, and their length is generally shorter than that of the first communication passages 158. That is, it can be seen from the arrangement of the second suction holes 132 that the second suction holes 132 contribute to correcting the warpage on the outer periphery of the wafer W. In addition, a full circumferential groove 152 with a depth of 1 mm or less is formed at the radial position of the chuck body 190 where the first suction holes 154 and the third suction holes 156 are formed, thereby reducing suction unevenness. Also, the number of first suction holes 154 and second suction holes 132 in the circumferential direction is approximately the same, but in the radial direction, there are about 10 to 25 first suction holes 154, while there are about 5 second suction holes 132. Therefore, including the third suction hole 156, the total number of the first and third suction holes 154, 156 is greater than the number of the second suction holes 132.

[0046] The above-mentioned dovetail groove 140 having a trapezoidal cross section is disposed on the outer diameter side of the first to third suction holes 154, 132, and 156. That is, the dovetail groove 140 is located on the outer diameter side of the circumferential groove 152 on the outermost peripheral side or the first suction hole 154, and is a seal groove that prevents the first to third suction holes 154, 132, and 156 from sucking air on the outer diameter side of the dovetail groove 140.

[0047] FIG. 7 shows a schematic example of a large-diameter wafer W being sucked using the vacuum chuck 100 of the present invention configured as described above. The vacuum suction method is not limited to this method, and suction may be performed from all suction holes simultaneously or from different types of suction holes simultaneously. FIG. 7(a) shows a state in which the wafer W is placed on the chuck body 190. Vacuum suction is not performed, and the outer periphery of the wafer with a convex warp abuts on the bottom of the elastic body 110, forming an enclosed space between the wafer W and the elastic body 110, and only the weight of the wafer itself acts on the elastic body 110. At this time, the elastic body 110 is statically settled at approximately its natural height or a slightly deformed height h0.

[0048] From this state, as shown in Fig. 7(b), the center of the wafer W, which is almost flat with little warping, is vacuum-adsorbed first using the third suction hole 156. This prevents the wafer W from moving within the horizontal plane during vacuum suction. By fixing the wafer W to the chuck body 190, it is possible to prevent the wafer W from shifting in position due to airflow generated when the peripheral portion is vacuum-adsorbed as shown in Fig. 7(c).

[0049] Next, vacuum suction is performed from the second suction hole 132 together with the first suction hole 154. Note that vacuum suction from the first suction hole 154 may be started after the wafer W has been flattened by vacuum suction from the second suction hole 132. The second suction hole 132 has a diameter several times larger than that of the first suction hole 154, and therefore has a large suction force, making it possible to flatten the wafer W against the rigidity of the wafer W. As described above, suction from the second suction hole 132 generates a large force, and therefore a force that moves the wafer W in a horizontal plane is also likely to be generated. For this reason, suction from the third suction hole 156 and the first suction hole 154 is used in combination.

[0050] Once the wafer W is sucked into the chuck body 190, the sealing action of the elastic body 110 ensures that there is almost no leakage between the wafer W and the suction surface 102 of the chuck body 190, so that vacuum suction can be achieved by using only suction from the first and third suction holes 154, 156, or by using a small amount of suction from the second suction hole 132 in combination.

[0051] Figures 7(d) to (f) are diagrams schematically showing an enlarged state of the elastic body 110 in the ant groove 140 in each state shown in Figures 7(a) to (c). When the back surface of the wafer W is brought into contact with the elastic body 110 in a state where no vacuum suction is performed, the height of the elastic body 110 from the suction surface 102 of the chuck body 190 becomes about the natural height h0. On the other hand, when only the central side of the wafer W is suctioned, the elastic body 110 slightly reduces its height, and the height from the suction surface 102 becomes h1 (<h0). Next, when the wafer W is flattened by vacuum suction from the second suction hole 132, the entire elastic body 110 is substantially accommodated in the ant groove 140 without protruding from the ant groove 140. As a result, the wafer W is completely flattened, and it is possible to prevent the wafer W from tilting and coming into miscontact with the probe 264.

[0052] Figure 8 shows a temperature control block diagram of the wafer W using the heating / cooling block shown in Figure 5. Here, the heating / control of the wafer W will be described taking the case of the standard vacuum chuck 100 shown in Figure 5(b) as an example, but the same applies to other vacuum chucks (Figures 5(a) and (c)). The vacuum chuck 100 on which the wafer W is placed has a built-in heater 182, and although not shown, a coolant flow path is also formed inside.

[0053] The coolant flow path is connected by a coolant pipe 316 to a cooling unit (cooling device) 314 provided in a chiller unit 310 disposed remotely from the inspection device 200. The coolant pipe 316 has a forward pipe 316a for feeding the coolant generated in the chiller unit 310 to the vacuum chuck 100 and a return pipe 316b for returning the coolant heated in the vacuum chuck 100 to the chiller unit 310. The cooling unit 314 is controlled via a signal line 308 by a chiller control unit 312 provided in the chiller unit 310. The heater 182 built in the vacuum chuck 100 is connected by a power line 338 to a heater controller 324 provided in the temperature control device 320, and power is supplied from the heater controller 324.

[0054] In order to uniformly control the surface temperature of the vacuum chuck 100 to a predetermined temperature, for example, at one or multiple points within a range of −10° C. to +100° C. using the heating and cooling mechanism configured in this manner, temperature sensors 334 are embedded at five different points in the vacuum chuck 100. The output of the temperature sensor 334 is input to a 5-channel conversion board (A / D converter) 332 and converted into a digital signal, which is input to a main control device 322 provided in the temperature control device 320 via a signal line 336. The main control device 322 is connected to a heater controller 324 via a signal line 326 and is also connected to a chiller control unit 312 via a signal line 318. Therefore, the temperature of the chucking surface 102 of the vacuum chuck 100 detected by the temperature sensor 334, in other words, the temperature of the wafer W, is fed back to control the temperature of the heater 182 and the temperature of the cooling liquid. At that time, the detection result of a prober (CPU) 222, which is an inspection means arranged opposite to the wafer W, is also fed back to the temperature control device 320.

[0055] As described above, with the vacuum chuck of this embodiment, even a large diameter wafer of 300 mm with a warped edge can be sufficiently flattened if the amount of warping is up to about 2 mm, making it possible to perform functional inspections on the wafer in one go. It was also confirmed that if the wafer warp is downwardly convex, it can be flattened reliably to the above-mentioned warp range, and even if the warp is downwardly convex, it can be flattened reliably up to about 2 mm.

[0056] In addition, in tests and inspections in which the temperature of a wafer W was controlled using the vacuum chuck 100, the warpage tended to be amplified and expanded at high temperatures compared to room temperature. Therefore, a warpage of 2 mm at room temperature becomes 4 mm at 100° C., and even if vacuum suction is attempted at that temperature, a gap exceeding the allowable warpage is formed and vacuum suction is not possible. This kind of defect could be addressed by setting the timing of vacuum suction to room temperature and raising the temperature of the wafer from room temperature to the test and inspection temperature while the wafer is still in vacuum suction. As a result, it was found that even at high temperatures, as long as the wafer W has a warpage of only about 2 mm at that temperature, good test and inspection can be performed regardless of the temperature.

[0057] In the above embodiment, the elastic body is a tube, but by using a solid foamed resin as the elastic body, air is sucked from the internal air bubbles when vacuum suction is applied, and the entire elastic body shrinks, and the entire elastic body can be deformed to be accommodated in the dovetail groove. Therefore, like the tube-type elastic body, the elastic body can be prevented from protruding radially inward and outward from the dovetail groove during vacuum suction, preventing the vacuum suction or preventing the wafer from being tilted when suctioned, and the wafer can be straightened to be flat. When a foamed material is used, the elastic body is solid, so that even when the vacuum suction is released, it almost completely restores to the state before the vacuum suction and recovers its rigidity. Therefore, even when a new wafer is placed, the same state as the previous wafer can be reproduced. In other words, wafers with the same amount of warping can be inspected. This prevents the probe provided in the probe card from being damaged due to contact between the wafer and the probe in an inappropriate position. [Explanation of symbols]

[0058] 100...vacuum chuck, 102...suction surface, 110...elastic body (tube or foamed material O-ring), 120...vacuum suction pipe connection, 124...push pin hole, 132...second (suction) hole, 136...second communication passage, 140...(circumferential) groove or dovetail groove, 152...(circumferential) groove, 154...first (suction) hole, 156...third (suction) hole, 158...first communication passage, 160...third communication passage, 170...cooling block, 172...cooling liquid passage, 180...heating block, 182...heater, 190...suction block (cha 200...(wafer) inspection device, 202...inspection position, 204...wafer information acquisition and setting position, 210...control device, 218...support, 220...test head, 222...prober (CPU), 230...(wafer) transport section, 232...camera, 234...head stage, 236...base, 240...XYZ-Θ table, 242...moving base, 244...X-axis table, 246...Y-axis table, 248...Z-axis table, 252...Θ table, 262...card holder, 264...probe, 266... Probe card, 268...contact cylinder, 270...vacuum exhaust device, 300...temperature control system, 310...chiller unit, 312...chiller control unit, 314...cooling unit (cooling device), 316...coolant piping, 316a...supply piping, 316b...return piping, 318...signal line, 320...temperature control device, 322...main control device, 324...heater control device, 326...signal line, 332...5ch conversion board (A / D converter), 336...signal line, 338...power line, 334...temperature sensor, 400...semiconductor wafer substrate Plate (silicon substrate), 402... terminal, 410... processor, 412... terminal, 420... memory (DRAM), 422... terminal, 424... lead wire, 426... interface (I / F), 430... silicon inclusion (interposer), 450... (semiconductor) chip, d1... maximum diameter of elastic body, D1... first suction hole diameter, D2... second suction hole diameter, D3... third suction hole diameter, h0... natural height of elastic body, h1... height of elastic body (middle position), W... (semiconductor) wafer, W1... dovetail groove width (bottom surface), W2... dovetail groove width (top surface)

Claims

1. A vacuum chuck having a disk-shaped chuck body for vacuum-attaching a semiconductor wafer, a plurality of concentric first circumferential grooves formed on an upper surface of the chuck body; a plurality of first holes extending in a vertical direction of the chuck body and formed at least at a center of the chuck body at intervals in a radial direction of the chuck body at each position of the plurality of first circumferential grooves; a first communication passage extending in the radial direction and communicating the plurality of first holes in the radial direction; a plurality of second holes extending in the vertical direction of the chuck body and formed outside the chuck body at intervals in the radial direction and at a plurality of concentric positions on the upper surface of the chuck body at intervals in the circumferential direction of the chuck body; a second communication passage extending in the radial direction of the chuck body and communicating the plurality of second holes in the radial direction of the chuck body; a second circumferential groove formed on the upper surface side of the chuck body outside all positions at which the first holes and the second holes are disposed; and a ring-shaped elastic body fitted into the second circumferential groove, the second circumferential groove is a dovetail groove; A vacuum chuck characterized in that the hole diameter of the plurality of second holes is formed to be larger than the hole diameter of the first holes so that the suction force of the second holes is greater than the suction force of the first holes when vacuum adsorbed.

2. A vacuum chuck having a disk-shaped chuck body for vacuum-attaching a semiconductor wafer, a plurality of concentric first circumferential grooves formed on an upper surface of the chuck body; a plurality of first holes extending in a vertical direction of the chuck body and formed at least at a center of the chuck body at intervals in a radial direction of the chuck body at each position of the plurality of first circumferential grooves; a first communication passage extending in the radial direction and communicating the plurality of first holes in the radial direction; a plurality of second holes extending in the vertical direction of the chuck body and formed outside the chuck body at intervals in the radial direction and at a plurality of concentric positions on the upper surface of the chuck body at intervals in the circumferential direction of the chuck body; a second communication passage extending in the radial direction of the chuck body and communicating the plurality of second holes in the radial direction of the chuck body; a second circumferential groove formed on the upper surface side of the chuck body outside all positions at which the first holes and the second holes are disposed; and a ring-shaped elastic body fitted into the second circumferential groove, the second circumferential groove is a dovetail groove; The elastic body is formed into a ring-shaped tube or a solid O-ring shape made of a foam material, A vacuum chuck characterized in that the hole diameter of the plurality of second holes is formed to be larger than the hole diameter of the first holes so that the suction force of the second holes is greater than the suction force of the first holes when vacuum adsorbed.

3. A vacuum chuck as described in claim 1 or 2, wherein when the semiconductor wafer is placed on the chuck body so that the outer periphery of the semiconductor wafer abuts against the elastic body, the center is adsorbed by the first hole and the outer periphery is sucked by the second hole.

4. The chuck further comprises a plurality of concentric third circumferential grooves formed on an upper surface of the chuck body, a plurality of third holes extending in the vertical direction of the chuck body at the positions of each of the plurality of third circumferential grooves and formed at intervals in the radial direction and in the circumferential direction in a portion of the chuck body other than the center, and a third communication passage extending in the radial direction and radially connecting the third holes, the third holes have a smaller hole diameter than the second holes; 4. The vacuum chuck of claim 3, wherein the plurality of third holes start to suck the semiconductor wafer together with the second holes.

5. A vacuum chuck as described in claim 4, characterized in that when the semiconductor wafer is adsorbed to the chuck body, the semiconductor wafer is sucked through the first hole and the third hole.

6. A vacuum chuck as described in claim 4, characterized in that when the semiconductor wafer is adsorbed to the chuck body, the suction by the second hole is weakened.

7. 7. The vacuum chuck according to claim 1, wherein a heater for heating the vacuum chuck, or a cooling liquid passage through which a cooling liquid for cooling the heater and the vacuum chuck flows, is disposed below a portion of the vacuum chuck where the first communicating passage and the second communicating passage are formed.

8. 8. A wafer inspection device comprising: a vacuum chuck according to claim 1; and a probe card capable of collectively measuring a plurality of semiconductor chips formed on an upper surface of a wafer.

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