Vacuum chuck and inspection device having them

Abstract

To enable an inspection of a function of a semiconductor chip in a state of a wafer before it is divided into a chip even if a warping of the wafer is large.SOLUTION: A vacuum chuck comprises: a plurality of concentric circular first circumferential grooves that is formed on an upper side front surface of a vacuum chuck main body; a plurality of first holes that is extended to a vertical direction and is formed with an interval to a peripheral direction at each position of a plurality of first grooves; a first communication hole that is extended to a radial direction and communicates each first hole to the radial direction; a plurality of second holes that is formed to the peripheral direction with the interval at the plurality of concentric circular positions on the upper side front surface of a chuck main body; a second communication hole that is extended to the radial direction, and communicates each second hole to the radial direction; a second circumferential groove that is formed to an outside of the radial direction from the position that is the upper surface side of the chuck main body, and in which each first hole and each second hole are provided; and a ring-like elastic body that is fitted to the second circumferential groove. The second circumferential groove is a dovetail groove of which the upper surface part is narrower than a bottom part.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a vacuum chuck for adsorbing a semiconductor wafer and an inspection apparatus including the same, and more particularly to a vacuum chuck suitable for adsorbing a semiconductor wafer having warpage and an inspection apparatus including the same.

Background Art

[0002] With the progress of high-speed and high-integration of semiconductor devices, wafer level packages (WLPs) having advantages such as reducing the mounting area and also reducing the effective inductance of wiring are widely used. WLP packages chips on a wafer and can obtain lower power consumption, larger bandwidth, speed, and reliability. Taking advantage of these advantages, a wider form factor can be provided for multi-chip packages used in mobile consumer devices, high-end supercomputing, gaming, artificial intelligence, and Internet-related products. In a high-bandwidth memory (HBM), which is a type of WLP, a plurality of memories stacked on one processor are connected. In the production thereof, a large number of high-bandwidth memory chips generally having a rectangular planar shape are formed on a substrate made of a semiconductor wafer, and then the semiconductor wafer is divided into a large number of high-bandwidth memories having a size of about 100 to 200 mm 2 or so. In the high-bandwidth memory, a processor and a memory unit in which a plurality of memories (DRAMs) are stacked in the vertical direction are connected via a silicon interposer, and the connection of the processor and the memory unit is connected and placed on the substrate via the silicon interposer.

[0003] When performing a functional test of the ultra-wideband memory formed in this way, it is obvious that the inspection efficiency is improved by inspecting each ultra-wideband memory in the wafer state immediately before dicing, rather than inspecting each ultra-wideband memory chip individually that is formed by dicing from a semiconductor wafer. In order to inspect the ultra-wideband memories collectively in the state of an undivided semiconductor wafer, the semiconductor wafer needs to be flat so that the inspection probe can be easily positioned at a predetermined position while protecting the inspection probe. However, in the wafer on which the ultra-wideband memory is formed as described below, warpage may occur, and currently, a method of inspecting each ultra-wideband memory chip individually diced from the semiconductor wafer is used.

[0004] On the other hand, there have also been attempts to inspect general semiconductor chips that are not ultra-wideband memories formed on a wafer in the state of the wafer even if the wafer is warped. In a 12-inch wafer with a diameter of φ300 mm on which an ultra-wideband memory is formed, the number of ultra-wideband memories may be, for example, 400 or more. In such a wafer, even if the diameter is increased, its thickness is about several hundred μm, so the rigidity of the entire wafer is low, and during wafer processing, especially when external forces are applied during packaging, the wafer is likely to warp or undulate (deform). The warpage of the wafer is indicated by the height difference between the peripheral part and the central part, and the value may be about several mm.

[0005] By the way, 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, with the conventional suction diameter, the surrounding air will be in a state of being sucked out, and the peripheral part of the wafer will remain warped without being sucked by the chuck. If the inspection is performed in the warped state, the inspection probe will contact the wafer surface obliquely, and in the worst case, the wafer or the expensive probe may be damaged. In order to eliminate the problems caused by such warpage of the wafer, various methods for canceling the warpage of the wafer during inspection have been proposed conventionally.

[0006] Patent Document 1 describes that even when adsorbing and holding a substrate such as a wafer with a large warp, the flatness of the substrate can be maintained well. Specifically, an annular concave portion that is recessed annularly is formed at a position surrounding the opening of the communication path on the upper surface of the base body, and a lower element of a seal member made of an annular elastic material is disposed in the annular concave portion. On the other hand, the upper element of the seal member is projected from the upper surface of the base body. And the upper element is provided with a first portion that extends upward while facing the annular inner side direction and a second portion that extends upward while facing the annular outer side direction.

[0007] Further, Patent Document 2 describes that a work stage that vacuum-adsorbs a warped work includes a base having a recess for supplying vacuum and a suction plate formed with a plurality of through holes attached on the recess. Further, it is also described that an elastic body for sealing is provided at the peripheral portion of the suction plate that adsorbs and holds the warped work.

[0008] Patent Document 3 describes that a wafer processing machine has a suction chuck structure that can adsorb and hold a wafer without being affected by the flatness of the wafer. Specifically, a cylindrical body formed of an elastic material that is a rubber plate and is expanded in a skirt shape and extends a predetermined length from the suction surface of the suction chuck is provided on the outer periphery of the suction chuck. Thereby, even if a gap is generated between the wafer surface and the suction surface, the cylindrical body closely adheres to the wafer surface while elastically deforming according to the warp, undulation, or step of the wafer surface, and forms an enclosure. As a result, the above gap can be sealed, and air and grinding fluid can be prevented from being sucked from the suction groove.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0010] In the vacuum chuck described in Patent Document 1, an annular recess is formed in the peripheral portion of a substantially circular ceramic substrate, and a seal member made of an elastic body is disposed in the annular recess. The elastic body is bellows-shaped or accordion-shaped, and its upper end surface contacts the wafer. When vacuum-sucking, the bellows-shaped or accordion-shaped elastic body expands and contracts to suck the wafer against the substrate without changing the contact position between the wafer and the elastic body. As a result, the wafer is flattened and held at a predetermined position.

[0011] However, in the vacuum chuck described in Patent Document 1, when the accordion-shaped elastic body is contracted, it is necessary to provide a large groove for housing the elastic body in the ceramic substrate. At the same time, since it is bellows-shaped and not a simple shape, when contracted, a part of the elastic body may deviate from smooth deformation and protrude between the upper surface of the ceramic substrate 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 may 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 proper inspection position, the suction direction height of the wafer changes and flatness cannot be ensured, and there is also a risk of generating a collision phenomenon with the probe. If the functional inspection of the ultra-wideband memory is an inspection in a temperature-controlled environment, for example, a low-temperature functional inspection or a high-temperature functional inspection, there is also a risk that the set temperature may deviate if the wafer position is not proper.

[0012] In the work stage described in Patent Document 2, a seal material is disposed near the periphery of a rectangular base, and a work is placed thereon. On the other hand, a rectangular perforated suction plate is disposed in the space inside the base partitioned by the seal material. Then, by vacuum-sucking from the back surface of the rectangular suction plate, the seal material is contracted to make the work conform to the flat suction plate.

[0013] However, since this work stage is used for exposure and the like, when a work with a large warp at the peripheral portion is placed on the work stage in a downward convex shape, in the state before vacuum suction, the work does not contact the sealing material and the central portion contacts the suction plate, making it difficult to eliminate the warp of the work and perform suction. In order to bring the work into contact with the sealing material in the state before vacuum suction for such a work, the height of the sealing material may be increased. However, even if the height of the sealing material is increased, during vacuum suction, the central portion of the sealing material with a short distance from the suction plate immediately contacts the suction plate, and the work tends to be adsorbed while maintaining the warp or with a slightly reduced warp. On the other hand, when the work is placed on the work stage in an upward convex shape, the work can contact the sealing material before vacuum suction. However, at the central portion of the portion partitioned by the sealing material, the distance from the suction plate becomes too long, making it difficult to obtain a sufficient vacuum suction effect, and the warp is maintained.

[0014] In the wafer processing machine described in Patent Document 3, during processing such as peripheral grinding of the wafer, the chuck vacuum-sucks and holds a warped wafer. The chuck has an elastic body at the outer peripheral portion. After bringing the back surface of the wafer into contact with the elastic body, vacuum suction is performed to hold the wafer on the chuck. At the same time, the wafer is brought into contact with the elastic body to eliminate the gap between the chuck and the wafer, preventing grinding water and the like from entering the back surface of the wafer. However, since the processing machine described in this publication only needs to prevent the entry of grinding water, correcting the warp of the wafer itself is not considered. That is, even if peripheral grinding or the like continues with the wafer in a warped shape, no problems occur.

[0015] The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to enable a function test of semiconductor chips even for a wafer having a large diameter and thus having a large warp formed at its peripheral portion, in a state of the wafer before being divided into individual chips. And preferably, it is also an object to enable a function test of semiconductor chips collectively in a wafer state. The function test includes a test in a temperature environment, and it is also an object to realize a uniform temperature environment for all the semiconductor chips formed on the wafer. And the present invention aims to achieve at least one of these multiple objects.

Means for Solving the Problems

[0016] The features of the present invention for achieving the above object are as follows. In a vacuum chuck having a chuck body formed in a disc shape for vacuum-sucking a semiconductor wafer, a plurality of concentric first circumferential grooves formed on the upper surface of the chuck body, a plurality of first holes extending in the vertical direction of the chuck body and formed at intervals in the circumferential direction at each position of the plurality of first circumferential grooves, a first communication path extending in the radial direction of the chuck body and communicating with the first holes in the radial direction, a plurality of second holes formed at intervals in the circumferential direction at a plurality of concentric positions on the upper surface of the chuck body, a second communication path extending in the radial direction of the chuck body and communicating with 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 and radially outside the positions where the first holes and the second holes are disposed, and a ring-shaped elastic body fitted in the second circumferential groove. The second circumferential groove is a dovetail groove formed such that the radial width on the upper surface of the chuck body is narrower than the radial width on 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 that vacuum-adsorbs a semiconductor wafer. The vacuum chuck includes a plurality of concentric first circumferential grooves formed on the upper surface of the chuck body, a plurality of first holes extending in the vertical direction of the chuck body and formed at intervals in the circumferential direction at each position of the plurality of first circumferential grooves, a first communication passage extending in the radial direction of the chuck body and communicating the first holes in the radial direction, a plurality of second holes formed at intervals in the 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 side of the chuck body and radially outside the positions where the first holes and the second holes are disposed, and a ring-shaped elastic body fitted in the second circumferential groove. The elastic body may be formed in a ring-shaped tube or in a solid O-ring shape made of a foaming material.

[0018] Among these features, the vacuum chuck further includes a plurality of concentric third circumferential grooves formed on the upper surface of the chuck body, a plurality of third holes extending in the vertical direction of the chuck body and formed at intervals in the circumferential direction at each position of the plurality of 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. It is preferable that the plurality of third holes include holes located radially inside the plurality of first holes and the plurality of second holes. Note that the first communication passage and the third communication passage may be shared.

[0019] Among the above features, it is preferable that the hole diameters of the plurality of second holes are larger than the hole diameters of the first holes. In the vacuum chuck, a heater for heating the vacuum chuck, or a coolant passage through which a coolant capable of cooling the vacuum chuck circulates, may be disposed below the portions where the first communication passage and the second communication passage are formed. The sum of the number of radially disposed first holes and third holes may be larger than the number of radially disposed second holes.

[0020] Still another feature of the present invention for achieving the above object is that a wafer inspection apparatus includes a vacuum chuck having any of the above features and a probe card capable of collectively measuring a plurality of semiconductor chips formed on the upper surface of the wafer.

Advantages of the Invention

[0021] According to the present invention, in a vacuum suction chuck for sucking a wafer used for functional inspection of the wafer, an annular groove is formed near the outer peripheral edge of the vacuum suction chuck, and an elastic body that protrudes from the groove higher than the amount of warpage of the wafer before vacuum suction is disposed on the vacuum suction chuck in a state of being fitted in the groove, and a vacuum suction passage that opens near the groove is formed. Therefore, the functional inspection of the semiconductor chips can be performed in the state of the wafer before being divided into individual chips. In addition, a uniform temperature environment can be realized for all the semiconductor chips formed on the wafer.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0023] Hereinafter, an embodiment of a vacuum chuck suitable for wafer inspection according to the present invention and an inspection apparatus including the same will be described with reference to the drawings. FIG. 1 is a front view of an embodiment of a wafer inspection apparatus 200 including a vacuum chuck 100 according to the present invention. In this wafer inspection apparatus 200, a plurality of probes 264 provided on a probe card 266 are simultaneously brought into contact with pads of semiconductor chips formed on a semiconductor wafer (hereinafter also referred to as a wafer) W, and an electrical inspection is performed. In the electrical inspection, the operating states at various temperature conditions are also checked. Therefore, means for heating and cooling the wafer W are generally provided.

[0024] As shown in FIG. 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. On the upper surface of the XYZ-Θ table 240, a vacuum chuck (hereinafter also referred to as a chuck) 100 according to the present invention on which the wafer W is placed and which vacuum-adsorbs the wafer W is disposed. As will be described in detail later, the vacuum chuck 100 is connected to a temperature control system 300 included in the control device 210, and is capable of controlling the temperature of the wafer W placed on the vacuum chuck 100. Further, in order to ensure the vacuum adsorption of the wafer W, a vacuum evacuation device 270 such as a vacuum pump is connected to the vacuum chuck 100.

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

[0026] The XYZ-Θ table 240 is surrounded by support columns 218 on the sides, and a head stage 234 is provided above. The head stage 234 is partially provided with an opening, and a card holder 262 is attached to the opening. A probe card 266 corresponding to the semiconductor chip 450 (see Fig. 2(a)) to be inspected formed on the wafer W is attached to the card holder 262. Further, a plurality of probes 264 that contact the semiconductor chip 450 are arranged on the probe card 266. The probe 264 has a delicate structure and is structured so that no extra load acts thereon in order to identify and contact the micro terminals on the order of μm formed on the chip 450. Therefore, the probe 264 is set to approach the wafer W at a predetermined posture and a predetermined speed during inspection.

[0027] A test head 220 is rotatably provided at the upper end of the support column 218. When the test head 220 rotates, a contact cylinder 268 is provided on the surface of the test head 220 facing the probe card 266, and the information detected by the probe 264 is transmitted to the control device 210 via the test head 220.

[0028] The XYZ-Θ table 240 is movable in the left-right direction in the figure via a moving base 242. When the wafer W is being conveyed by the conveying unit 230, the XYZ-Θ table 240 moves to the wafer information acquisition / setting position 204 on the right side in the figure, places and adsorbs the wafer W on the vacuum chuck 100, and then acquires position information and chip 450 information using a camera 232 or the like fixed to the head stage 234. After acquiring the information of the wafer, the XYZ-Θ table 240 moves to the inspection position 202 on the left side in the figure and collectively performs inspections using the probes 264. Here, "collectively" means that while the wafer W is adsorbed on the vacuum chuck 100, the XYZ-Θ table 240 is driven to continuously inspect a plurality of chips 450, preferably all the chips 450 formed on the surface of the wafer W.

[0029] Fig. 2 shows an example of a semiconductor wafer W on which the vacuum chuck 100 according to the present invention can be placed and adsorbed. Note that the semiconductor wafer W on which the vacuum chuck 100 can be placed and adsorbed is not limited to that shown in Fig. 2, and any semiconductor wafer W can be placed and adsorbed. In particular, the present vacuum chuck 100 has a special feature that it can adsorb even a semiconductor wafer W having warpage.

[0030] Fig. 2(a) is a top view of the 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 with a width of about 13.3 mm and a length of about 10.9 mm are formed in the plane where the orientation flat is formed.

[0031] The semiconductor chip 450 shown in Fig. 2(b) is called a high bandwidth memory (HBM), and has a memory (DRAM) 420 in which a processor 410 and multiple layers (4 layers in the figure) are stacked. An interface (I / F) 426 is arranged below the memory 420 of the stacked portion. The processor 410 and the memory 420 are connected via a silicon inclusion (interposer) 430, and the integrated product of the processor 410 and the memory 420 is connected to a semiconductor wafer substrate (silicon substrate) 400 via the silicon inclusion 430. Between the processor 410 and the silicon inclusion 430, between the silicon inclusion 430 and the semiconductor wafer substrate 400, and between the silicon inclusion 430 and the interface 426, they are connected using terminals 412, 402, 422, etc. formed respectively, and between the memories 420 are connected by lead wires 424. The semiconductor chip 450 formed in this way causes factors that warp the semiconductor chip 450 formed to a thickness of several 100 μm due to differences in the weights of the memory 420 stacked with the processor 410 and the processing method when forming the chip 450.

[0032] An embodiment of the vacuum chuck 100 according to the present invention provided in the inspection apparatus 200 shown in FIG. 1 will be described with reference to FIGS. 3 to 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 longitudinal sectional view of the chuck body 190 provided in the vacuum chuck 100, and is a view showing various examples including heating and / or cooling means for the wafer W. FIG. 5(a) is an example when only heating means is provided, FIG. 5(b) is an example of the most standard case including both heating and cooling means, and FIG. 5(c) is an example when both heating and cooling means in which the vacuum suction part and the cooling part are integrated are provided. In FIG. 5, the left half is shown as a cross section at the B position in FIG. 4, and the right half is shown as a cross section at the A or C position in FIG. 4. FIG. 6 is a view for explaining the details of the suction holes and the vacuum seal formed in the chuck body 190. FIG. 6(a) is a longitudinal sectional view of the chuck body 190 for explaining the positional relationship of the suction holes, and FIG. 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 for explanation, but the same applies to the other vacuum chucks 100 shown in FIGS. 5(a) and 5(c). As shown in FIG. 5(b), the vacuum chuck 100 includes a chuck body 190 which is a disc-shaped vacuum suction block located at the uppermost part, a disc-shaped cooling block 170 disposed below the chuck body 190, and a disc-shaped heating block 180 disposed below the cooling block 170. These blocks 190, 170, and 180 are integrated using bolts (not shown) or the like to form a columnar vacuum chuck 100. A plurality of coolant passages 172 are formed in the cooling block 170, and a coolant such as cooling water cooled by a chiller flows through them. Further, a heater 182 is disposed in the heating block 180 and is wound multiple times in a spiral shape.

[0034] In the vacuum suction block 190 that forms the uppermost part of the vacuum chuck 100, a number of holes and grooves have been conventionally formed to stably adsorb and hold the wafer W. In the present invention, in addition to these conventional holes and grooves, a new hole, groove, and elastic body 110 that fits into the groove are provided in the vacuum chuck 100 so as to be able to cope with a warped wafer W.

[0035] As shown in FIGS. 3 and 4, the chuck body 190 is formed in a circular shape with a diameter larger than that of the wafer W. In the portion where the wafer W is placed, a plurality of first suction holes 154 are formed in the radial direction to suck and fixedly hold the flat wafer W. These suction holes 154 are provided at a plurality of locations in the circumferential direction (4 locations, position C in the figure) and are formed in shallow grooves 152 formed concentrically in large numbers. When the wafer W to be adsorbed is about φ300 mm, the number of grooves 152 is preferably 10 or more, more preferably 20 or more, and the number of the suction holes 154 in the circumferential direction is preferably 4 or more.

[0036] Note that on the central side (small-diameter side) of the chuck body 190, the number of the first suction holes 154 may be reduced. Each of the first suction holes 154 at the same position in the circumferential direction is communicated by a first communication path 158 extending in the radial direction from the outer peripheral portion. On the outer peripheral portion of the chuck body 190, a vacuum suction pipe connection portion 120 to which a vacuum suction fitting is attached according to the respective positions of the first communication paths 158 is provided (see FIG. 3) and is connected to a vacuum exhaust device 270 via a pipe (see FIG. 1). Thereby, the entire upper surface of the chuck body 190 is vacuum-sucked.

[0037] In this embodiment, a push pin is disposed at the center of the chuck body 190 so that the wafer W can be easily separated from the vacuum chuck after vacuum release. Therefore, push pin holes 124 are formed in the vacuum chuck at intervals in the circumferential direction. Since various processes including the process for disposing a temperature sensor, which will be described later, are performed at the center of the chuck body 190 in this way, the processes are concentrated. In order to avoid excessive processing, the first suction hole 154 is omitted in the vicinity of the center portion, and the third suction hole 156 for mainly vacuum-sucking the center portion of the chuck body 190 is formed at a circumferential position different from that of the first suction hole 154 (position A in the figure). Similar to the case of the first suction hole 154, a third communication path 160 is formed from the outer periphery to the center of the chuck body 190 for the third suction hole 156. Note that the diameters of the first suction hole 154 and the third suction hole 156 are set to be the same. By vacuum-sucking the back surface of the wafer W using these first and third suction holes 154 and 156, in the case of a flat wafer W, the wafer W can be fixed and held on the vacuum chuck 100 without any problem, and various inspections in the inspection apparatus 200 can be executed according to the program. In this embodiment, the third suction hole 156 and the third communication path 160 are provided at positions different from the first suction hole 154 and the first communication path 158, but one of the plurality of 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] Incidentally, in a large-diameter wafer W in which the semiconductor wafer substrate 400 of the wafer W is very thin with respect to the outer diameter, particularly in a wafer W in which semiconductor chips 450 such as HBM are formed, the amount of warpage increases at the peripheral portion, and a gap may be generated between the wafer W and the vacuum chuck 100 at the peripheral portion even when suction is performed using only the first and third suction holes 154 and 156. In that case, as described above, when attempting to inspect the wafer W, the probe 264 may contact the surface of the wafer W in a posture different from the normal posture. The probe 264 for inspecting the wafer W is a delicate instrument, and when it contacts the wafer W deviating from the normal posture or a predetermined posture, it may contribute to the breakage of the expensive probe 264.

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

[0040] The elastic body 110 fitted into the groove 140 is easily deformable, and the portion protruding from the groove 140 before vacuum suction remains within the width of the groove 140 during and after vacuum suction, and does not cause any displacement and biting between the wafer W and the chuck body 190, and finally all is configured to be accommodated 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 foaming material. As the foaming material, silicone resin is preferable.

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

[0042] That is, when the warpage amount at the position where the wafer W abuts against the elastic body 110 is h0 or less, in the state where the wafer W is placed on the chuck body 190, the outer peripheral portion of the wafer W is partitioned by the elastic body 110, and a sealed space can be formed between the chuck body 190 and the wafer W. Thereby, the vacuum suction described below becomes possible. On the other hand, if the warpage of the wafer W exceeds h0, a gap is formed at the peripheral edge between the chuck body 190 and the wafer W, and there is a risk of air drawing even when performing vacuum suction to flatten the wafer W. In many wafers W, the warpage amount is 2 mm or less. Therefore, also in this embodiment, the size of the anti-aliasing groove 140 and the size (diameter, thickness, or rigidity) of the tube 110 are set so that h0 is 2 mm or more.

[0043] When the anti-aliasing groove 140 is formed as described above, a sealed space can be formed between the chuck body 190 and the wafer W. However, the sealed space is larger than the gap in the case of vacuum suction using the first suction hole 154 and the third suction hole 156, and it is necessary to generate a force 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 having a larger diameter than the first suction hole 154 and the third suction hole 156 is arranged around the outer diameter of the chuck body 190. As shown in FIG. 4, the second suction holes 132 are provided at a plurality of positions different in the circumferential direction from the first and third suction holes 154 and 156 (in this embodiment, four positions: B positions), and at a plurality of positions on the inner diameter side from the outer diameter position where the circumferential anti-aliasing groove 140 is formed. In the case of this embodiment, they 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 path 136 formed from the outer peripheral side toward the center.

[0044] Fig. 6(a) shows the positional relationship among the first to third suction holes 154, 132, 156, the first to third communication passages 158, 136, 160, and the ant groove 140, superimposed in the circumferential direction. The diameters φD1 and φD3 of the first and third suction holes 154 and 156 are about 1 mm, and they are formed at intervals in the radial direction of the chuck body 190. And the first communication passage 158 communicating the plurality of first suction holes 154 stops at a position radially outside the third communication passage 160 connecting the plurality of third suction holes 156.

[0045] A plurality of second suction holes 132 mainly for correcting the warp on the outer peripheral side of the wafer W are formed to have a diameter φD2 of about 2 to 3 mm, which is several times the diameter of φD1 and φD3, and are formed at positions between the first suction holes 154 in the radial direction and at a plurality of positions centered on the large-diameter side of the chuck body 190. The second communication passage 136 communicating the second suction holes 132 extends from the outer peripheral portion of the chuck body 190 toward the center, and its length is generally shorter than that of the first communication passage 158. That is, it can be seen from the arrangement of the second suction holes 132 that the second suction holes 132 contribute to the warp correction of the outer peripheral edge portion of the wafer W. Note that an entire 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, reducing the suction unevenness. Also, the circumferential numbers of the first suction holes 154 and the second suction holes 132 are substantially 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 holes 156, the total number of the first and third suction holes 154 and 156 is larger than the number of the second suction holes 132.

[0046] On the outer diameter side of the first to third suction holes 154, 132, 156, the above-mentioned ant groove 140 with a trapezoidal cross-section is arranged. That is, the ant groove 140 is located on the outer diameter side of the outermost circumferential groove 152 or the first suction holes 154, and it is a seal groove that prevents the first to third suction holes 154, 132, 156 from sucking air on the outer diameter side of the ant groove 140.

[0047] Fig. 7 schematically shows an example of sucking a large-diameter wafer W 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 simultaneously from all suction holes or from different types of suction holes simultaneously. Fig. 7(a) shows a state where the wafer W is placed on the chuck body 190. Vacuum suction is not performed, the outer peripheral portion of the wafer with a convex warp contacts under the elastic body 110, a sealed space is formed between the wafer W, and only the self-weight of the wafer acts on the elastic body 110. At this time, the elastic body 110 is statically determined at a substantially natural height or a slightly deformed height h0.

[0048] From this state, as shown in Fig. 7(b), the central portion of the wafer W with less warp and substantially flat is first vacuum-adsorbed using the third suction hole 156. This prevents the wafer W from moving in the horizontal plane during vacuum suction. By fixing the wafer W to the chuck body 190, the generation of air flow during vacuum adsorption of the peripheral portion shown in Fig. 7(c) prevents the wafer W from being displaced.

[0049] Next, vacuum suction is performed from the second suction hole 132 together with the first suction hole 154. The vacuum suction from the first suction hole 154 may start after the wafer W is flattened by the vacuum suction from the second suction hole 132. Since the diameter of the second suction hole 132 is several times that of the first suction hole 154, the suction force is large, and it is possible to flatten the wafer W against the rigidity of the wafer W. Since the suction from the second suction hole 132 generates a large force in this way, a force that moves the wafer W in the horizontal plane is also likely to be generated. Therefore, suction from the third suction hole 156 and the first suction hole 154 is used in combination.

[0050] Once the wafer W is sucked by the chuck body 190, almost no leakage occurs from between the wafer W and the adsorption surface 102 of the chuck body 190 due to the sealing action of the elastic body 110. Therefore, the vacuum adsorption can be dealt with by only the suction from the first and third suction holes 154 and 156, or by using a slight suction from the second suction hole 132 in combination.

[0051] Figures 7(d) to 7(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 7(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 accidental contact with the probe 264.

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

[0053] The coolant flow path is connected to a cooling unit (cooling device) 314 provided in a chiller unit 310 disposed remotely from the inspection device 200 by a coolant pipe 316. 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 incorporated in the vacuum chuck 100 is connected to a heater controller 324 provided in the temperature control device 320 by a power line 338, 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, one point or multiple points within -10°C to +100°C, temperature sensors 334 are embedded at five different points on the vacuum chuck 100. The output of the temperature sensor 334 is input to a 5-channel conversion board (A / D converter) 332 and changed into a digital signal, and then input to the 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 adsorption 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, and the temperature of the heater 182 and the temperature of the coolant are controlled. At that time, the detection result of the probe (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, according to the vacuum chuck of the present embodiment, even for a 300-mm large-diameter wafer with a warped peripheral portion, if the warpage amount is up to about 2 mm, it can be sufficiently flattened, and it becomes possible to collectively perform functional inspections on the wafer. In addition, it was confirmed that if the warp of the wafer is convex downward, it can be surely flattened up to the above warp range, and even if it is convex downward, it can be surely flattened as long as it is up to about 2 mm.

[0056] In the test and inspection in which the temperature of the wafer W was controlled using this vacuum chuck 100, there was a tendency that the warp was amplified and expanded at high temperatures compared to normal temperatures. Therefore, the warp amount of 2 mm at normal temperature becomes 4 mm at 100°C, and even if an attempt is made to perform vacuum suction at that temperature, a gap exceeding the allowable warp amount is formed and vacuum suction cannot be performed. For such a problem, it was possible to cope by setting the timing of vacuum suction to normal temperature and raising the temperature of the wafer from normal temperature to the test and inspection temperature while maintaining the vacuum suction state. From this, it was found that even at high temperatures, as long as the wafer W has a warp amount of about 2 mm at that temperature state, good tests and inspections can be performed regardless of the temperature.

[0057] In the above embodiment, the elastic body is a tube. However, by using a solid foam resin as the elastic body, when vacuum suction is applied, air is sucked from the internal bubble portion and the entire elastic body contracts, and the entire elastic body can be deformed to be accommodated in the ant groove. Therefore, similar to the tube-shaped elastic body, during vacuum suction, it is possible to prevent the elastic body from protruding radially inward and outward from the ant groove and interfering with the vacuum suction or tilting the wafer during suction, and the wafer can be corrected to be flat. When a foam material is used, since it is solid even after the vacuum suction is released, it almost completely restores to the state before the vacuum suction and also recovers its rigidity. Therefore, even when a new wafer is placed, the same state as the previous wafer can be reproduced. That is, it becomes possible to inspect up to a wafer with the same amount of warpage. Thereby, it is possible to prevent the occurrence of probe breakage caused by the probe provided in the probe card coming into contact with the wafer in an inappropriate posture.

Explanation of Signs

[0058] 100… Vacuum chuck, 102… Suction surface, 110… Elastomer (tube or foamed material O-ring), 120… Vacuum suction pipe connection part, 124… Push pin hole, 132… Second (suction) hole, 136… Second communication path, 140… (Circumferential) groove or chamfer groove, 152… (Circumferential) groove, 154… First (suction) hole, 156… Third (suction) hole, 158… First communication path, 160… Third communication path, 170… Cooling block, 172… Coolant passage, 180… Heating block, 182… Heater, 190… Suction block (chuck body), 200… (Wafer) inspection device, 202… Inspection position, 204… Wafer information acquisition / setting position, 210… Control device, 218… Support column, 220… Test head, 222… Probe (CPU), 230… (Wafer) transfer unit, 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 pipe, 316a… Forward pipe, 316b… Return pipe, 318… Signal line, 320… Temperature control device, 322… Main control device, 324… Heater controller, 326… Signal line, 332… 5ch conversion board (A / D converter), 336… Signal line, 338… Power line, 334… Temperature sensor, 400… Semiconductor wafer substrate (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 elastomer, D1… Diameter of first suction hole, D2… Diameter of second suction hole, D3… Diameter of third suction hole, h0… Natural height of elastomer, h1… Height of elastomer (intermediate position), W… (Semiconductor) wafer, W1… Chamfer groove width (bottom surface), W2… Chamfer groove width (top surface)

Claims

1. In a vacuum chuck for vacuum-adsorbing a semiconductor wafer, grooves formed concentrically on the upper surface of the vacuum chuck, first suction holes formed in the grooves, a plurality of second suction holes formed outside the upper surface at intervals in the circumferential direction, a runner groove formed on the upper surface on the outer circumference of the first suction holes and the second suction holes, an elastic body for sealing fitted into the runner groove, and the hole diameter of the second suction holes is formed larger than the hole diameter of the first suction holes, a vacuum chuck characterized by this.

2. The first suction holes have a plurality of third suction holes and a fourth suction hole, the second suction holes are formed on the runner groove side in the region inside the runner groove, the fourth suction hole is formed at the center of the vacuum chuck, the plurality of third suction holes are formed outside the fourth suction hole and at intervals in the circumferential direction, the vacuum chuck according to Claim 1.

3. When the semiconductor wafer is placed so that the outer peripheral portion of the semiconductor wafer abuts against the elastic body, the center portion of the semiconductor wafer is sucked by the fourth suction hole, and the outer peripheral portion is sucked by the second suction hole, the vacuum chuck according to Claim 2.

4. The plurality of third suction holes start sucking the semiconductor wafer together with the second suction holes, the vacuum chuck according to Claim 3.

5. When the semiconductor wafer is adsorbed, the semiconductor wafer is sucked by the third suction holes and the fourth suction holes, the vacuum chuck according to Claim 4.

6. When the semiconductor wafer is adsorbed, the suction by the second suction holes is weakened, the vacuum chuck according to Claim 4.

7. A wafer inspection apparatus comprising the vacuum chuck according to any one of Claims 1 to 6 and a probe card capable of collectively measuring a plurality of semiconductor chips formed on the upper surface of a semiconductor wafer.

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