Four-point tilt alignment wafer chuck

Abstract

A device includes: a chuck configured to hold a wafer; and an inclined plate disposed below the chuck and adjustably connected to the chuck by a pair of upper screws and a pair of lower screws separately arranged at opposite corners of the chuck. The screw heads of the pair of upper screws rest against the top surface of the chuck such that a clockwise rotation of one of the upper screws pushes the corresponding corner of the chuck toward the inclined plate. The screw heads of the pair of lower screws rest against the bottom surface of the chuck such that a counterclockwise rotation of one of the lower screws pushes the corresponding corner of the chuck away from the inclined plate.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to a provisional patent application filed on Dec. 10, 2021 and designated as U.S. Application No. 63 / 287,974, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a chuck for holding a semiconductor wafer, and more particularly, to a tiltable chuck for mechanical probe testing of a semiconductor wafer. Background Art

[0004] The evolution of the semiconductor manufacturing industry has placed higher demands on yield management and specifically metrology and inspection systems. Critical dimensions are constantly shrinking, but the industry needs to shorten the time to reach high-yield, high-value production. Minimizing the total time from detecting a yield problem to resolving the problem determines the return on investment for semiconductor manufacturers.

[0005] Fabricating semiconductor devices such as logic and memory devices typically involves processing semiconductor wafers or EUV masks using a large number of fabrication processes to form various features and multiple levels of the semiconductor device. For example, lithography is a semiconductor manufacturing process that involves transferring a pattern from a photomask to a photoresist disposed on a semiconductor wafer. Additional examples of semiconductor manufacturing processes include, but are not limited to, chemical mechanical polishing (CMP), etching, deposition, and ion implantation. Multiple semiconductor devices can be fabricated as an arrangement on a single semiconductor wafer, and the semiconductor devices are separated into individual semiconductor devices.

[0006] After a particular step in the semiconductor manufacturing process, an adhesion test can be performed to test the adhesion of a deposited film layer on a wafer substrate held by a chuck. These tests use a wedge probe that contacts the deposited film, leaving a spall mark / fracture. When the wafer substrate is orthogonal to the wedge probe, the accuracy of adhesion can be improved. However, the probe tip cannot be fabricated and mounted to inspection equipment with an alignment tolerance sufficient to be orthogonal to the wafer at installation. Therefore, the angle of the wafer can be calibrated by examining the spall fractures left in the wafer. When the spall fractures are nearly symmetric around the indentation left by the probe, this can indicate that the wafer substrate and the wedge probe are orthogonal. When the spall fractures are more on one side of the indentation left by the probe, it can indicate that the wafer is not orthogonal to the wedge probe. In these cases, it can be desirable to tilt the chuck to be orthogonal to the wedge probe. In some cases, a reference sample can be used to replace the wafer to perform angle calibration.

[0007] Two main mechanisms have been used for chuck tilt alignment: (1) three-point adjustment and (2) gimbal devices:

[0008] Three-point tilt adjustment is based on the incidence of three non-collinear points within a single plane. When adjusting one or both of the points, the plane angle can change. However, chucks with three-point adjustment have low stiffness and stiffness position variations. This can compromise the accuracy of the bond test due to the penetration depth and force measurements depending on the probe position on the wafer. Alignment using this technique is also complex because adjusting one point causes the chuck to tilt on multiple axes. In other words, a single tilt axis can only be precisely adjusted by adjusting both of the points.

[0009] Gimbal devices typically have a single support axis and at least one additional off-axis tilt adjustment. Each axis can be adjusted for tilt alignment. However, the single support axis of gimbal devices also has low stiffness and stiffness position variations, which can compromise the accuracy of the bond test due to different penetration depths and force measurements depending on the probe position on the wafer.

[0010] Accordingly, there is a need for a chuck with high stiffness and low stiffness position variations to improve accuracy during mechanical probe testing. SUMMARY OF THE INVENTION

[0011] Embodiments of the present disclosure provide an apparatus. The apparatus may include a chuck configured to hold a wafer. The apparatus may further include a tilt plate disposed below the chuck. The tilt plate may be adjustably connected to the chuck by a pair of upper screws and a pair of lower screws separately arranged at opposite corners of the chuck. The screw heads of the pair of upper screws rest against the top surface of the chuck such that a clockwise rotation of one of the upper screws can push the corresponding corner of the chuck towards the tilt plate. The screw heads of the pair of lower screws rest against the bottom surface of the chuck such that a counterclockwise rotation of one of the lower screws can push the corresponding corner of the chuck away from the tilt plate.

[0012] According to embodiments of the present disclosure, the apparatus may further include a pair of upper springs around the pair of upper screws and a pair of lower springs around the pair of lower screws. The pair of lower springs and the pair of upper springs may have a pre-load between the bottom surface of the chuck and the top surface of the tilt plate.

[0013] According to embodiments of the present disclosure, a counterclockwise rotation of one of the upper screws can cause the corresponding one of the upper springs to push the corresponding corner of the chuck away from the tilt plate. A clockwise rotation of one of the lower screws can separate the screw head of the lower screw from the bottom surface of the chuck.

[0014] According to an embodiment of the present disclosure, the chuck may include four through holes extending from the top surface of the chuck to the bottom surface of the chuck, and at least a portion of the pair of upper screws and at least a portion of the pair of lower screws may be disposed within the through holes. Each of the through holes may include an upper section that penetrates to the top surface of the chuck and a lower section that penetrates to the bottom surface of the chuck. The diameter of the upper section may be smaller than the diameter of the lower section, which defines an annular surface therebetween. The screw shafts of the pair of upper screws may extend through the upper section and the lower section. The screw heads of the pair of lower screws may be disposed within the lower section, may rest against the annular surface, and may be accessible via the upper section. The pair of upper springs and the pair of lower springs may be disposed within the lower section of each of the through holes and may rest against the annular surface. The inclined plate may include four threaded holes aligned with the four through holes, and the pair of upper screws and the pair of lower screws may be threadedly received by the threaded holes.

[0015] According to an embodiment of the present disclosure, the top surface of the chuck may include a recessed sample area configured to receive the wafer. The top surface of the chuck may further include a reference area configured to receive a reference material. The reference area may be separate from the sample area.

[0016] According to an embodiment of the present disclosure, the apparatus may further include a wedge-shaped indenter. The wedge-shaped indenter may be configured to probe the wafer disposed in the sample area and / or the reference material disposed in the reference area. The chuck may be located in a plane orthogonal to the wedge-shaped indenter.

[0017] According to an embodiment of the present disclosure, the apparatus may further include a base plate disposed below the inclined plate and removably fixed to the inclined plate.

[0018] Embodiments of the present disclosure provide a method. The method may include fixing the chuck on top of an inclined plate using a pair of upper screws and a pair of lower screws separately arranged at opposite corners of the chuck, and placing a wafer on the chuck. The screw heads of the pair of upper screws may rest against the top surface of the chuck such that clockwise rotation of one of the upper screws may push the corresponding corner of the chuck towards the inclined plate. The screw heads of the pair of lower screws may rest against the bottom surface of the chuck such that counterclockwise rotation of one of the lower screws may push the corresponding corner of the chuck away from the inclined plate. A pair of upper springs may surround the pair of upper screws, a pair of lower springs may surround the pair of lower screws, and the pair of lower springs and the pair of upper springs may have prestress between the bottom surface of the chuck and the top surface of the inclined plate.

[0019] According to an embodiment of the present disclosure, the method may further include adjusting the plane of the chuck relative to the inclined plate by counterclockwise rotation of one of the upper screws, which may cause the corresponding one of the upper springs to push the corresponding corner of the chuck away from the inclined plate.

[0020] According to an embodiment of the present disclosure, the method may further include adjusting the plane of the chuck relative to the inclined plate by clockwise rotation of one of the lower screws, which may separate the screw head of the lower screw from the bottom surface of the chuck.

[0021] According to an embodiment of the present disclosure, the method may further include probing the wafer in the sample area disposed on the top surface of the chuck using a wedge-shaped indenter. The chuck may be located in a plane orthogonal to the wedge-shaped indenter.

[0022] According to an embodiment of the present disclosure, the method may further include placing a reference material in a reference area on the top surface of the chuck and probing the reference material using the wedge-shaped indenter. The reference area may be separated from the sample area. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] For a more complete understanding of the nature and objects of the present disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which:

[0024] Figure 1 is a perspective view of an apparatus according to an embodiment of the present disclosure;

[0025] Figure 2 is a top view of an apparatus according to an embodiment of the present disclosure;

[0026] Figure 3 is along Figure 2 sectional view taken along line B-B of;

[0027] Figure 4 is Figure 3 detailed view of detail D of;

[0028] Figure 5 is along Figure 2 sectional view taken along line C-C of;

[0029] Figure 6 is Figure 5 detailed view of detail E of; and

[0030] Figure 7 is a flowchart of a method according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0031] Although the claimed subject matter will be described with reference to specific embodiments, other embodiments, including embodiments that do not provide all of the benefits and features described herein, are within the scope of the present disclosure. Various structural, logical, process step, and electronic changes may be made without departing from the scope of the present disclosure. Accordingly, the scope of the present disclosure is defined only by reference to the appended claims.

[0032] Embodiments of the present disclosure provide an apparatus 100, as Figure 1 and 2 shown. The apparatus 100 may include a chuck 110. The chuck 110 may be configured to hold a wafer 112. The wafer 112 may be circular and have a diameter of up to 300 mm. The wafer 112 may be placed within a sample area 113 on the top surface 111 of the chuck 110. The sample area 113 may be recessed into the top surface 111 of the chuck 110. The sample area 113 may be located at the center of the top surface 111 of the chuck 110. The chuck 110 may be configured to hold a reference sample 114. The reference sample 114 may be a fused silica or aluminum wafer. The reference sample 114 may be used for indirect verification of force and depth measurements or for position calibration of the indenter tip. The reference sample 114 may be placed within a reference area 115 on the top surface 111 of the chuck 110. The reference area 115 may be separate from the sample area 113. For example, the reference area 115 may be located in a corner of the top surface 111 of the chuck 110. The reference area 115 may be smaller than the sample area 113. The reference area 115 may be circular and have a diameter of approximately 10 mm. For the sample area 113 and the reference area 115, the chuck 110 may be capable of holding the wafer 112 and the reference sample 114 simultaneously, so that it may not be necessary to exchange the wafer 112 with the reference sample 114 after performing indenter calibration. The chuck 110 may be configured to hold multiple reference samples 114 within multiple reference areas 115 on the top surface 111 of the chuck 110. The top surface 111 of the chuck 110 may have a circular or polygonal shape. For example, the top surface 111 of the chuck 110 may be square.

[0033] The device 100 may further include an inclined plate 120. The inclined plate 120 may be disposed below the chuck 110. The top surface 121 of the inclined plate 120 may have a circular or polygonal shape. For example, the top surface 121 of the inclined plate 120 may be square. The inclined plate 120 may be larger than the chuck 110. For example, the area of the top surface 121 of the inclined plate 120 may be larger than the area of the top surface 111 of the chuck 110. The inclined plate 120 may be adjustably connected to the chuck 110 by a pair of upper screws 130 and a pair of lower screws 140. The pair of upper screws 130 and the pair of lower screws 140 may be separately disposed in opposite corners of the chuck 110. In other words, one of the pair of upper screws 130 or one of the pair of lower screws 140 may be disposed in each corner of the chuck 110, while the other of the pair of upper screws 130 or the other of the pair of lower screws 140 may be disposed in the opposite corner of the chuck 110. For example, the pair of upper screws 130 and the pair of lower screws 140 may be arranged in a square shape. The pair of upper screws 130 may be the same as the pair of lower screws 140.

[0034] Although screws are used herein, this is intended to refer to threaded rods or other threaded fasteners known in the art. Thus, in the examples, screws may include bolts. The screws used herein may have right-handed threads, where the threads extend clockwise, or left-handed threads, where the threads extend counterclockwise, or any combination thereof.

[0035] As Figure 3 and 4 shown, the pair of upper screws 130 may be socket cap screws. The pair of upper screws 130 may each include a screw head 131 and a screw shaft 132. The screw heads 131 of the pair of upper screws 130 may rest against the top surface 111 of the chuck 110. A clockwise rotation of one of the upper screws 130 may push the corresponding corner of the chuck 110 towards the inclined plate 120.

[0036] As Figure 5 and 6 shown, the pair of lower screws 140 may be socket cap screws. The pair of lower screws 140 may each include a screw head 141 and a screw shaft 142. The screw heads 141 of the pair of lower screws 140 may rest against the bottom surface 116 of the chuck 110. A counterclockwise rotation of one of the lower screws 140 may push the corresponding corner of the chuck 110 away from the inclined plate 120.

[0037] The pair of upper screws 130 and the pair of lower screws 140 may be standard socket cap screws with a coarse pitch. Socket cap screws with a fine pitch may be used, which may allow for a more precise vertical adjustment of the chuck 110 with each rotation of the pair of upper screws 130 and the pair of lower screws 140.

[0038] As Figures 3 - 6 shown in Figures 3 - 6 , the apparatus 100 may further include a pair of upper springs 135 surrounding the pair of upper screws 130 and a pair of lower springs 145 surrounding the pair of lower screws 140. For example, the inner diameter of the pair of upper springs 135 may be greater than the diameter of the screw heads 131 of the pair of upper screws 130, and the inner diameter of the pair of lower springs 145 may be greater than the diameter of the screw heads 141 of the pair of lower screws 140. The pair of upper springs 135 and the pair of lower springs 145 may be helical springs. The pair of lower springs 145 and the pair of upper springs 135 may have a prestress between the bottom surface 116 of the chuck 110 and the top surface 121 of the inclined plate 120. The pair of upper springs 135 and the pair of lower springs 145 may be strong enough to lift the weight of the chuck 110. In other words, the specific springs used may depend on the characteristics of the chuck 110 (e.g., size, weight, material). Accordingly, the pair of upper springs 135 and the pair of lower springs 145 may ensure that the chuck 110 remains spaced apart from the inclined plate 120 and maintains contact with the pair of upper screws 130 and the pair of lower screws 140 during the adjustment process.

[0039] Counterclockwise rotation of one of the upper screws 130 may cause the corresponding one of the upper springs 135 to push the corresponding corner of the chuck 110 away from the inclined plate 120. Clockwise rotation of one of the lower screws 140 may separate the screw head 141 of the lower screw 140 from the bottom surface 116 of the chuck 110, thereby causing one of the lower springs 145 to support the corresponding corner of the chuck 110.

[0040] In some embodiments, the pair of upper screws 130 and the pair of lower screws 140 may be manually rotated. For example, the pair of upper screws 130 and the pair of lower screws 140 may be rotated by a manual screwdriver. In other embodiments, the pair of upper screws 130 and the pair of lower screws 140 may be automatically rotated. For example, the pair of upper screws 130 and the pair of lower screws 140 may be rotated by electric control.

[0041] The chuck 110 may include four through holes 150 extending from the top surface 111 of the chuck 110 to the bottom surface 116 of the chuck 110. The through holes 150 may be non-threaded. At least part of the pair of upper screws 130 and at least part of the pair of lower screws 140 may be disposed within the through holes 150. The remaining portions of the pair of upper screws 130 and the remaining portions of the lower screws 140 may extend out of the bottom surface 116 of the chuck 110. Each through hole 150 may include an upper section 151 that penetrates to the top surface 111 of the chuck 110 and a lower section 152 that penetrates to the bottom surface 116 of the chuck 110. The diameter of the upper section 151 may be smaller than the diameter of the lower section 152. For example, the diameter of the upper section 151 may be smaller than the diameter of the screw heads 131, 141 and may be larger than the diameter of the screw shafts 132, 142. The diameter of the lower section 152 may be larger than the outer diameter of the pair of upper springs 135 and the pair of lower springs 145. The upper section 151 and the lower section 152 may define an annular surface 153 therebetween. As used herein, the annular surface 153 may be regarded as part of the bottom surface 116 of the chuck 110 that is recessed into the through hole 150.

[0042] As Figure 4 shown, the screw shafts 132 of the pair of upper screws 130 may extend through the upper section 151 and the lower section 152 of the corresponding through hole 150 and extend out of the bottom surface 116 of the chuck 110. In this way, the screw heads 131 of the pair of upper screws 130 may rest against the top surface 111 of the chuck 110.

[0043] As Figure 6 shown, the screw heads 141 of the pair of lower screws 140 may be disposed in the lower section 152 of the corresponding through hole 150. The screw heads 141 may rest against the annular surface 153. In this way, the screw heads 141 may be accessible via the upper section 151 to rotate the pair of lower screws 140. For example, a screwdriver may be inserted through the upper section 151 to rotate one of the lower screws 140. The screw shafts 142 of the pair of lower screws 140 may extend through the lower section 152 of the corresponding through hole 150 and extend out of the bottom surface 116 of the chuck 110.

[0044] As Figures 3 - 6 shown, the pair of upper springs 135 and the pair of lower springs 145 may be disposed in the lower section 152 of each through hole 150. The pair of upper springs 135 and the pair of lower springs 145 may rest against the annular surface 153. In this way, the pair of upper springs 135 and the pair of lower springs 145 may have prestress between the annular surface 153 of the chuck 110 and the top surface 121 of the inclined plate 120.

[0045] The inclined plate 120 may include four threaded holes 155. The threaded holes 155 may be aligned with the four through holes 150. For example, the threaded holes 155 may be arranged in a square shape. The pair of upper screws 130 and the pair of lower screws 140 may be received in a screwed manner by the threaded holes 155. The threaded holes 155 may have the same thread as the pair of upper screws 130 and the pair of lower screws 140. The threaded holes 155 may extend at least partially through the inclined plate 120. For example, the threaded holes 155 may extend from the top surface 121 of the inclined plate 120 to the bottom surface 126 of the inclined plate.

[0046] For the device 100 of the present disclosure, the chuck 110 may be fixed to the inclined plate 120 by the pair of upper screws 130 and the pair of lower screws 140 such that when the pair of upper screws 130 are rotated in the clockwise direction and the pair of lower screws 140 are rotated in the counterclockwise direction, the chuck 110 is clamped and compressed between the screw heads 131 of the pair of upper screws 130 and the screw heads 141 of the pair of lower screws 140. In this way, the chuck 110 may be stable and have high stiffness with low position variation. By rotating one of the lower screws 140 in the clockwise direction, the chuck 110 may no longer be compressed between the screw heads 131 of the pair of upper screws 130 and the screw heads 141 of the pair of lower screws 140, such that subsequent or simultaneous clockwise or counterclockwise rotation of one of the upper screws 130 and / or clockwise rotation of the other of the lower screws 140 may change the tilt alignment of the chuck 110 relative to the inclined plate 120. In this way, adjacent upper screws 130 and lower screws 140 may be adjusted simultaneously to tilt the chuck 110 about a single axis.

[0047] It should be understood that the angular range in which the chuck 110 may be tilted relative to the inclined plate 120 may be governed by the side length of the chuck 110 and the separation between the chuck 110 and the inclined plate 120. By increasing the separation between the bottom surface 116 of the chuck 110 and the top surface 121 of the inclined plate 120 relative to the side length of the chuck 110, a larger tilt range may be achieved.

[0048] Returning to Figure 1 and 2 the device 100 may further include a base plate 160. The base plate 160 may be disposed below the inclined plate 120. For example, the bottom surface 126 of the inclined plate 120 may be disposed on the top surface 161 of the base plate 160. The top surface 161 of the base plate 160 may have a circular or polygonal shape. For example, the top surface 161 of the base plate 160 may be square. The base plate 160 may be larger than the inclined plate 120. For example, the area of the top surface 161 of the base plate 160 may be larger than the area of the top surface 121 of the inclined plate 120. In some embodiments, the base plate 160 may be part of a semiconductor tool.

[0049] The base plate 160 can be removably fixed to the inclined plate 120 by a plurality of fixing screws 170. The plurality of fixing screws 170 can be socket head cap screws. The plurality of fixing screws 170 can be evenly spaced on the top surface 121 of the inclined plate 120. For example, the plurality of fixing screws 170 can include four fixing screws 170 arranged in a square shape. The plurality of fixing screws 170 can be arranged on a portion of the top surface 121 of the inclined plate 120 that is not covered by the chuck 110. In this way, when the chuck 110 is fixed to the inclined plate 120, the plurality of fixing screws 170 can be accessible.

[0050] As Figure 4 and 6 shown, the inclined plate 120 can further include a plurality of fixing holes 172 extending from the top surface 121 of the inclined plate 120 to the bottom surface 126 of the inclined plate 120. The fixing holes 172 can be non-threaded. At least a portion of the plurality of fixing screws 170 can be disposed within the plurality of fixing holes 172. The remaining portion of the plurality of fixing screws 170 can extend out of the bottom surface 126 of the inclined plate 120. The plurality of fixing holes 172 can be countersunk or buried in the top surface 121 of the inclined plate 120. In this way, when disposed in the plurality of fixing holes 172, the plurality of fixing screws 170 can be flush with the top surface 121 of the inclined plate 120.

[0051] As shown in Figure 3 and 5 shown, the base plate 160 can include a plurality of receiving holes 175. The plurality of receiving holes 175 can be aligned with the plurality of fixing holes 172. For example, the plurality of receiving holes 175 can be arranged in a square shape. The plurality of fixing screws 170 can be received in a screwed manner by the plurality of receiving holes 175. The plurality of receiving holes 175 can have the same thread as the plurality of fixing screws 170. The receiving holes 175 can extend at least partially through the base plate 160. For example, the receiving holes 175 can extend from the top surface 161 of the base plate 160 to a depth that may not reach the bottom surface 166 of the base plate 160.

[0052] For the device 100 having the base plate 160, the assembled chuck 110 and the inclined plate 120 can be removed from the base plate 160 while maintaining the relative alignment between the chuck 110 and the inclined plate 120.

[0053] Returning to reference Figure 1, the apparatus 100 may further include a wedge-shaped indenter 180. The wedge-shaped indenter 180 may be attached to an arm (not shown) and may be moved using an actuator (not shown). The wedge-shaped indenter 180 may be removed from and / or replaced on the arm. The size and material of the wedge-shaped indenter 180 may depend on the specific application. For example, the wedge-shaped indenter 180 may be diamond. The wedge-shaped indenter 180 may have a linear tip 181. For example, the length of the linear tip 181 may be 50 micrometers. The wedge-shaped indenter 180 may be configured to probe a wafer 112 disposed in the sample area 113 and / or a reference material 114 disposed in a reference area 115 of the chuck 110. The chuck 110 may be located in a plane orthogonal to the wedge-shaped indenter 180. When the chuck 110 is not in a plane orthogonal to the wedge-shaped indenter 180, the plane of the chuck 110 may be adjusted by rotation of one or more of the pair of upper screws 130 and / or one or more of the pair of lower screws 140. In this way, the chuck 110 may be fixed in a plane orthogonal to the wedge-shaped indenter 180 to improve the accuracy of the probing measurement.

[0054] Embodiments of the present disclosure provide Figure 7 the method 200 shown in. The method 200 may include the following steps.

[0055] In step 210, the chuck is fixed on top of the inclined plate using a pair of upper screws and a pair of lower screws separately arranged at opposite corners of the chuck. The top surface of the chuck may have a circular or polygonal shape. For example, the top surface of the chuck may be square. The top surface of the inclined plate may have a circular or polygonal shape. For example, the top surface of the inclined plate may be square. The inclined plate may be larger than the chuck. For example, the area of the top surface of the inclined plate may be larger than the area of the top surface of the chuck. The pair of upper screws and the pair of lower screws may be separately arranged at opposite corners of the chuck. In other words, one of the pair of upper screws or one of the pair of lower screws may be arranged at each corner of the chuck, while the other of the pair of upper screws or the other of the pair of lower screws may be arranged at the opposite corner of the chuck. For example, the pair of upper screws and the pair of lower screws may be arranged in a square shape. The pair of upper screws may be the same as the pair of lower screws. The pair of upper screws and the pair of lower screws may be socket head cap screws, each socket head cap screw including a screw head and a screw cap.

[0056] The screw heads of the pair of upper screws rest against the top surface of the chuck such that a clockwise rotation of one of the upper screws pushes the corresponding corner of the chuck towards the inclined plate. The screw heads of the pair of lower screws rest against the bottom surface of the chuck such that a counterclockwise rotation of one of the lower screws pushes the corresponding corner of the chuck away from the inclined plate. In this way, the chuck is compressed between the screw heads of the pair of upper screws and the screw heads of the pair of lower screws.

[0057] In step 220, the wafer is placed on the chuck. The wafer can be circular and have a diameter of up to 300 mm. The wafer can be placed within a sample area on the top surface of the chuck. The sample area can be recessed into the top surface of the chuck. The sample area can be placed at the center of the top surface of the chuck.

[0058] According to an embodiment of the present disclosure, method 200 may further include the following steps.

[0059] In step 230, a wedge-shaped indenter is used to probe the wafer in the sample area placed on the top surface of the chuck. The sample area can be recessed into the top surface of the chuck. The sample area can be placed at the center of the top surface of the chuck. The wedge-shaped indenter can have a linear tip. The chuck can be located in a plane orthogonal to the wedge-shaped indenter. When the chuck is not in a plane orthogonal to the wedge-shaped indenter, the plane of the chuck can be adjusted by the rotation of one or more of the pair of upper screws and / or one or more of the pair of lower screws. In this way, the chuck can be fixed in a plane orthogonal to the wedge-shaped indenter to improve the accuracy of the probing measurement.

[0060] According to an embodiment of the present disclosure, method 200 may further include the following steps.

[0061] In step 225, a reference material is placed in a reference area on the top surface of the chuck. The reference area can be separated from the sample area. For example, the reference area can be placed in a corner of the top surface of the chuck. The reference area can be smaller than the sample area. For both the sample area and the reference area, the chuck may be capable of holding the wafer and the reference sample simultaneously, so it may not be necessary to exchange the wafer with the reference sample after performing the angle calibration. The chuck can be configured to hold multiple reference samples in multiple reference areas placed on the top surface of the chuck.

[0062] In step 235, the reference material is probed using the wedge-shaped indenter. By probing the reference material, angle calibration of the chuck and / or calibration of the wedge-shaped indenter can be performed before probing the wafer. The wedge-shaped indenter can be lowered to probe the reference material, or the wedge-shaped indenter can be translated relative to the reference material in other ways to achieve the probing.

[0063] It should be understood that steps 225 and 235 can be performed before step 220, between step 220 and step 230, or after step 230, and are not limited herein. For example, the wafer and the reference material can be placed on the chuck simultaneously. By probing the reference material, calibration of the chuck and the indenter can be performed before performing the bonding test on the wafer.

[0064] According to an embodiment of the present disclosure, a pair of upper springs can surround the pair of upper screws, a pair of lower springs can surround the pair of lower screws, and the pair of lower springs and the pair of upper springs can have a prestress between the bottom surface of the chuck and the top surface of the inclined plate. The inner diameter of the pair of upper springs can be greater than the diameter of the screw heads of the pair of upper screws, and the inner diameter of the pair of lower springs can be greater than the diameter of the screw heads of the pair of lower screws. The pair of upper springs and the pair of lower springs can be helical springs.

[0065] Method 200 can further include at least one of the following steps performed after step 230 or step 235.

[0066] In step 240, check the chipping marks generated by the wedge indenter. When using the wedge indenter to probe the wafer or reference material, chipping marks are generated. The chipping marks can be checked to determine the relative alignment of the chuck and the wedge indenter. The check can be performed using an optical microscope, which can be integrated in the probing system. When the chipping marks appear symmetric, the chuck can be orthogonal to the wedge indenter. When the chipping marks appear asymmetric, the chuck can be misaligned with the wedge indenter, such that the plane of the chuck may need to be adjusted to achieve orthogonal alignment. For example, at least one of the following steps can be performed after step 240.

[0067] In step 250, adjust the plane of the chuck relative to the inclined plate by counterclockwise rotation of one of the upper screws, which causes the corresponding one of the upper springs to push the corresponding corner of the chuck away from the inclined plate.

[0068] In step 255, adjust the plane of the chuck relative to the inclined plate by clockwise rotation of one of the lower screws, which separates the screw head of the lower screw from the bottom surface of the chuck.

[0069] After step 250 and / or step 255, steps 250 and / or step 255 can be repeated with different ones of the upper screws and / or lower screws to further adjust the plane of the chuck relative to the inclined plate. When the plane is set to the desired angle (e.g., such that the plane of the chuck is orthogonal to the wedge indenter), the pair of upper screws and the pair of lower screws can be used in step 260 to re-fix the chuck on top of the inclined plate. Specifically, any one of the upper screws that was not rotated in step 250 can be rotated clockwise to push the corresponding corner of the chuck towards the inclined plate, and / or any one of the lower screws that was not rotated in step 255 can be rotated counterclockwise to push the corresponding corner of the chuck away from the inclined plate, thereby clamping and compressing the chuck between the screw heads of the pair of upper screws and the screw heads of the pair of lower screws in the new tilted adjusted position, and the chuck is stable and rigid with low position variation.

[0070] In some embodiments, the pair of upper screws and the pair of lower screws can be rotated manually. For example, the pair of upper screws and the pair of lower screws can be rotated by a manual screwdriver. In other embodiments, the pair of upper screws and the pair of lower screws can be rotated automatically. For example, the pair of upper screws and the pair of lower screws can be rotated by electric control.

[0071] It should be understood that after performing step 260, steps 230 and / or step 235 can be repeated. For example, after adjusting the plane of the chuck to a new tilt position, the wafer or reference material can be probed again with the wedge tip. Then, step 240 can be repeated to inspect the new cleavage marks. If the new cleavage marks appear symmetric, the chuck can be orthogonal to the wedge tip. If the new cleavage marks appear asymmetric, the plane of the chuck may need to be further adjusted, and steps 250 and / or step 255 and step 260 can be repeated until an orthogonal alignment is achieved, which can be confirmed by repeating the probing in steps 230 and / or step 235 and the inspection in step 240.

[0072] For the method 200 of the present disclosure, the chuck can be fixed to the tilt plate by the pair of upper screws and the pair of lower screws such that when the pair of upper screws are rotated in the clockwise direction and the pair of lower screws are rotated in the counterclockwise direction, the chuck is clamped and compressed between the screw heads of the pair of upper screws and the screw heads of the pair of lower screws. In this way, the chuck can be stable and have high stiffness with low position variation. By rotating one of the lower screws in the clockwise direction, the chuck is no longer compressed between the screw heads of the pair of upper screws and the screw heads of the pair of lower screws, such that subsequent or simultaneous clockwise or counterclockwise rotation of one of the upper screws and / or clockwise rotation of the other of the lower screws can change the tilt alignment of the chuck relative to the tilt plate. In this way, adjacent upper and lower screws can be adjusted simultaneously to tilt the chuck about a single axis such that the plane of the chuck is orthogonal to the wedge tip for improving the accuracy of the bonding test.

[0073] Although the present disclosure has been described with respect to one or more particular embodiments, it will be understood that other embodiments of the present disclosure can be made without departing from the scope of the present disclosure. Accordingly, the present disclosure is considered to be limited only by the appended claims and their reasonable interpretation.

Claims

1. A testing device, comprising: a chuck configured to hold a wafer; and an inclined plate disposed below the chuck and adjustably connected to the chuck by a pair of upper screws and a pair of lower screws separately arranged at opposite corners of the chuck; wherein the screw heads of the pair of upper screws rest against the top surface of the chuck such that clockwise rotation of one of the upper screws pushes the corresponding corner of the chuck towards the inclined plate; and wherein the screw heads of the pair of lower screws rest against the bottom surface of the chuck such that counterclockwise rotation of one of the lower screws pushes the corresponding corner of the chuck away from the inclined plate.

2. The testing device according to claim 1, further comprising: a pair of upper springs surrounding the pair of upper screws; and a pair of lower springs surrounding the pair of lower screws; wherein the pair of lower springs and the pair of upper springs have prestress between the bottom surface of the chuck and the top surface of the inclined plate.

3. The testing device according to claim 2, wherein counterclockwise rotation of one of the upper screws causes the corresponding one of the upper springs to push the corresponding corner of the chuck away from the inclined plate.

4. The testing device according to claim 2, wherein clockwise rotation of one of the lower screws separates the screw head of the lower screw from the bottom surface of the chuck.

5. The testing device according to claim 2, wherein the chuck includes four through holes extending from the top surface of the chuck to the bottom surface of the chuck, and at least part of the pair of upper screws and at least part of the pair of lower screws are disposed within the through holes.

6. The testing device according to claim 5, wherein each of the through holes includes: an upper section that penetrates to the top surface of the chuck; and a lower section that penetrates to the bottom surface of the chuck; wherein the diameter of the upper section is smaller than the diameter of the lower section, defining an annular surface therebetween.

7. The testing device according to claim 6, wherein the screw shafts of the pair of upper screws extend through the upper section and the lower section.

8. The testing device according to claim 6, wherein the screw heads of the pair of lower screws are disposed in the lower section, rest against the annular surface, and are accessible via the upper section.

9. The testing device according to claim 6, wherein the pair of upper springs and the pair of lower springs are disposed in the lower section of each of the through holes and rest against the annular surface.

10. The testing device according to claim 5, wherein the inclined plate includes four threaded holes aligned with the four through holes, and the pair of upper screws and the pair of lower screws can be threadedly received by the threaded holes.

11. The testing device according to claim 1, wherein the top surface of the chuck includes a recessed sample area configured to receive the wafer.

12. The testing device according to claim 11, wherein the top surface of the chuck further comprises a reference area configured to receive a reference material, the reference area being separated from the sample area.

13. The testing device according to claim 12, further comprising: a wedge-shaped indenter configured to probe the wafer disposed in the sample area and / or the reference material disposed in the reference area; wherein the chuck is located in a plane orthogonal to the wedge-shaped indenter.

14. The testing device according to claim 1, further comprising: a base plate disposed below the inclined plate and removably fixed to the inclined plate.

15. A testing method, comprising: fixing the chuck on top of the inclined plate using a pair of upper screws and a pair of lower screws separately arranged at opposite corners of the chuck; placing a wafer on the chuck; wherein the screw heads of the pair of upper screws rest against the top surface of the chuck such that clockwise rotation of one of the upper screws pushes the corresponding corner of the chuck towards the inclined plate; and wherein the screw heads of the pair of lower screws rest against the bottom surface of the chuck such that counterclockwise rotation of one of the lower screws pushes the corresponding corner of the chuck away from the inclined plate.

16. The testing method according to claim 15, wherein a pair of upper springs surround the pair of upper screws, a pair of lower springs surround the pair of lower screws, and the pair of lower springs and the pair of upper springs have prestress between the bottom surface of the chuck and the top surface of the inclined plate.

17. The testing method according to claim 16, further comprising: adjusting the plane of the chuck relative to the inclined plate by counterclockwise rotation of one of the upper screws, which causes the corresponding one of the upper springs to push the corresponding corner of the chuck away from the inclined plate.

18. The testing method according to claim 16, further comprising: adjusting the plane of the chuck relative to the inclined plate by clockwise rotation of one of the lower screws, which separates the screw head of the lower screw from the bottom surface of the chuck.

19. The testing method according to claim 15, further comprising: probing the wafer in the sample area disposed on the top surface of the chuck using a wedge-shaped indenter; wherein the chuck is located in a plane orthogonal to the wedge-shaped indenter.

20. The testing method according to claim 19, further comprising: placing a reference material in the reference area on the top surface of the chuck; and probing the reference material using the wedge-shaped indenter; wherein the reference area is separated from the sample area.

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