System for wafer inspection

Abstract

The present specification discloses an invention capable of detecting the bending of a wafer. The present invention may include a case divided into a first space and a second space by a partition wall, a measuring unit disposed in the first space to generate an upper surface image or a lower surface image of a wafer, an inversion unit that flips the wafer, and a control unit that detects the bending of the wafer based on the upper surface image or the lower surface image.

Description

Technology Field

[0001] The present invention relates to a wafer inspection system capable of detecting warping of a wafer mixed with reflective and non-reflective materials by flipping the wafer over. Background Technology

[0002] A wafer refers to the base plate used in semiconductor manufacturing, and since the condition of the wafer affects the reliability of the semiconductor, it is very important to maintain the condition of the wafer.

[0003] There may be various processes for making semiconductor chips using wafers, such as tape bonding, chip mounting, molding, grinding, and processing. During this process, the wafer may bend due to the difference in thermal expansion coefficients when high and low heat are applied (baking) after molding.

[0004] Since wafer warping affects the reliability of semiconductors, wafer warping is detected during each process.

[0005] However, the wiper ground after molding has a mixture of reflective and non-reflective materials, and there is a problem in that it is difficult to detect bending because there is less reflected information around the non-reflective material. Prior art literature

[0006] Korean published patent publication number "2010-0026651(2010.03.10) The problem to be solved

[0007] The present invention according to one embodiment aims to provide a wafer inspection system capable of detecting warping of a wafer mixed with reflective and non-reflective materials by inverting the wafer and inspecting both sides, thereby solving the aforementioned problem. means of solving the problem

[0008] A wafer inspection system according to one embodiment may include a case, a moving unit disposed within the case for moving a wafer, a measuring unit disposed within the case for supporting a wafer moved by the moving unit and generating an image of the wafer, an inversion unit positioned within the case spaced apart from the moving unit for inverting the wafer when the wafer is delivered, and a control unit that generates an upper surface image of the wafer or a lower surface image of the wafer when the wafer is inverted based on the image generated by the measuring unit, and detects bending of the wafer based on the upper surface image or the lower surface image.

[0009] The above measuring unit may include a light source unit that irradiates pattern light onto the wafer and a receiving unit that receives the pattern light reflected from the upper surface of the wafer to generate the upper surface image, or receives the pattern light reflected from the lower surface of the wafer to generate the lower surface image.

[0010] The above-mentioned inversion unit may include a support plate whose upper surface is adsorbed to the lower surface of the wafer, a connecting rod whose one end is installed on the side of the support plate, and a rotary motor installed at the other end of the connecting rod to rotate the support plate.

[0011] A suction hole is formed on the upper surface of the base plate, a first fluid path is formed inside the base plate and communicates with the suction hole, and a second fluid path is formed inside the connecting rod and communicates with the first fluid path.

[0012] The above-mentioned support plates may be formed as a pair and spaced apart from each other in parallel, and may include a first support plate in which the suction hole is formed, and a second support plate that is extended between the first support plates and has the connecting rod installed on its side.

[0013] The control unit may include an analysis unit that generates a surface height map of the wafer based on the upper surface image or the lower surface image, and an output unit that displays a curved area in the surface height map.

[0014] The analysis unit can generate a top surface height map based on the top surface image, generate a bottom surface height map based on the bottom surface image, and generate a standard height map by matching the top surface height map and the bottom surface height map.

[0015] The analysis unit can select a subpixel among a plurality of pixels of the upper surface image to perform phase unfolding and generate the upper surface height map based thereon, and after inverting the lower surface image based on the center line of the lower surface image, select a subpixel among a plurality of pixels of the lower surface image to perform phase unfolding and generate the lower surface height map based thereon. Effects of the invention

[0016] A wafer inspection system according to one embodiment formed by the above-described configuration can have a measurement unit that generates an upper surface image and a lower surface image of a wafer by means of an inversion unit, and a control unit that can detect the bending of a wafer mixed with reflective and non-reflective materials based thereon.

[0017] Therefore, there is no error in the wafer's positional reproducibility, and detection time can be reduced.

[0018] In addition, chip yield can be improved through wafer process management of mixed materials. Brief explanation of the drawing

[0019] FIG. 1 is a schematic diagram of a wafer inspection system according to one embodiment. Figure 2 is a perspective view of the chuck shown in Figure 1. Figure 3 is a schematic diagram of the measuring unit shown in Figure 1. Figure 4 is a plan view of the inversion section shown in Figure 1. FIG. 5 is a plan view showing the state before the inversion part illustrated in FIG. 1 is placed on the lower side of the wafer. FIG. 6 is a plan view showing the state after the inversion unit illustrated in FIG. 5 is placed on the lower side of the wafer. Figure 7 is an AA section diagram shown in Figure 4, representing the state before the wafer is placed on the support. Figure 8 is an AA section diagram shown in Figure 4, showing the state after a wafer is placed on a support. Fig. 9 is a side view of Fig. 5. Fig. 10 is a side view of Fig. 6. Figure 11 shows the state in which the inversion part illustrated in Figure 10 adsorbs and raises the wafer. Figure 12 shows the state in which the inversion part illustrated in Figure 11 has the wafer flipped. Figure 13 shows the state in which the inversion unit illustrated in Figure 12 lowers the wafer. Figure 14 shows the state in which the wafer is separated from the inversion section shown in Figure 13. Figure 15 is a block diagram of the control unit shown in Figure 1. Figure 16 shows an image of the top surface of the wafer. Figure 17 shows the back image of the wafer in an inverted state. Fig. 18 is an enlarged view of part A shown in Fig. 16. Specific details for implementing the invention

[0020] Hereinafter, an embodiment of the present invention will be described in detail with reference to exemplary drawings. However, this is not intended to limit the scope of the present invention.

[0021] It should be noted that when assigning reference numerals to the components of each drawing, the same components are assigned the same reference numeral whenever possible, even if they are shown in different drawings. Furthermore, in describing the present invention, if it is determined that a detailed description of related known components or functions could obscure the essence of the invention, such detailed description is omitted.

[0022] Furthermore, the size or shape of components depicted in the drawings may be exaggerated for clarity and convenience of explanation. Additionally, terms specifically defined in consideration of the structure and operation of the present invention are intended only to describe embodiments of the present invention and do not limit the scope of the present invention.

[0023] FIG. 1 is a schematic diagram of a wafer inspection system according to one embodiment.

[0024] A wafer inspection system (100) according to one embodiment may include a case (110), a standby unit (113), a measurement unit (120), a movement unit (130), an alignment unit (140), an inversion unit (200), and a control unit (150).

[0025] The case (110) is a structural component that forms the framework of the wafer inspection system (100), and a space is formed inside so that each component can be placed in the space of the case (110), and the interior of the case (110) can be kept dark by shielding light.

[0026] The case (110) is divided into a first space (110a) and a second space (110b) by a partition wall (111), and a gate (112) is installed in the partition wall (111) so that a moving part (130) and a reversing part (200) can move between the first space (110a) and the second space (110b) through the gate (112).

[0027] The measuring unit (120) is placed in the first space (110a) to generate an image (20, illustrated in FIG. 16 and FIG. 17) of the wafer (10). First, it generates an image of the upper surface (20a, illustrated in FIG. 16) of the wafer (10), and when the wafer (10) is inverted by the inversion unit (200), it can generate an image of the lower surface (20b, illustrated in FIG. 17) of the wafer (10).

[0028] A standby section (113) is positioned on the outside of the case (110) to accommodate a wafer (10), and a moving section (130) is positioned in the second space (110b) to transport the wafer (10) from the standby section (113) to the first space (110a).

[0029] The moving part (130) can move forward, backward, left, and right, for example, by using a robot arm equipped with a gripper.

[0030] The alignment unit (140) is placed in the second space (110b) and is mounted before the wafer (10) is transported to the first space (110a) by the moving unit (130), so that the centering position, edge position, and balance of the wafer (10) can be adjusted.

[0031] The inversion unit (200) can be moved in the same way as the moving unit (130) by using, for example, a robot arm, and a suction tool is installed on the robot arm to flip the wafer (10).

[0032] The control unit (150) is installed inside or outside the case (110) and can selectively control the operation of the components forming the wafer inspection system (100) and detect the bending of the wafer (10) based on the image generated by the measurement unit (120).

[0033] That is, the measuring unit (120) can generate an upper surface image and a lower surface image of the wafer (10) by means of the inversion unit (200), and the control unit (150) can detect the bending of the wafer (10) mixed with reflective and non-reflective materials based on this.

[0034] Figure 2 is a perspective view of the chuck shown in Figure 1.

[0035] Referring to FIG. 2, the wafer inspection system further includes a support block (115), and the support block (115) is made up of a plurality of units and can be placed on the upper surface of the chuck (114) to support the wafer (10).

[0036] For example, the support block (115) is composed of three parts and arranged in a triangular shape to stably support smile type and cry type wafers (10).

[0037] Figure 3 is a schematic diagram of the measuring unit shown in Figure 1.

[0038] Referring to FIG. 3, the measuring unit (120) may include a light source unit (121) and a receiving unit (122).

[0039] The light source unit (121) is positioned above the wafer (10) and can irradiate a pattern light, which is visible light, onto one side of the wafer (10).

[0040] More specifically, the light source unit (121) can generate pattern light of the X-axis or Y-axis, shift the phase difference of the pattern light, and irradiate the pattern light onto the wafer (10).

[0041] For example, the light source unit (121) can irradiate pattern light in the X-axis direction four times while moving by λ / 4, and then irradiate pattern light in the Y-axis direction four times while moving by λ / 4.

[0042] The receiving unit (122) is, for example, composed of a lens and a CCD camera and is positioned on one side of the wafer (10) to receive pattern light reflected from the upper surface of the wafer (10) to generate an upper surface image, or to receive pattern light reflected from the lower surface of the wafer (10) to generate a lower surface image.

[0043] FIG. 4 is a plan view of the inversion unit shown in FIG. 1, FIG. 5 is a plan view showing the state before the inversion unit shown in FIG. 1 is placed on the lower side of the wafer, and FIG. 6 is a plan view showing the state after the inversion unit shown in FIG. 5 is placed on the lower side of the wafer.

[0044] The inversion unit (200) may include a base plate (210), a connecting rod (220), a rotary motor (240), a robot arm (230), a pipe (250), and a vacuum pump (260).

[0045] The upper surface of the support plate (210) is fixed by adsorption to the lower surface of the wafer (10), and for this purpose, a suction hole (211) is formed on the upper surface of the support plate (210), and a first flow path (212) is formed inside the support plate (210) and can communicate with the suction hole (211).

[0046] The base plate (210) may include a first base plate (210a) and a second base plate (210b).

[0047] The first support plate (210a) is made up of a pair and is spaced apart from each other parallel, and a suction hole (211) can be formed.

[0048] The suction holes (211) are made up of multiple holes and are spaced apart from each other along the longitudinal direction of the first support plate (210a), so that the wafer (10) can be more firmly adsorbed and fixed to the support plate (210).

[0049] The second support plate (210b) is extended between the first support plates (210a), and a wafer mounting groove (215) corresponding to the edge of the wafer (10) may be formed on the upper surface of the second support plate (210b).

[0050] That is, when the wafer (10) is placed on the support plate (210), the edge of the wafer (10) comes into contact with the wafer mounting groove (215), which can reduce the possibility of the wafer (10) changing position.

[0051] One end of the connecting rod (220) may be fixed by being positioned on the side of the second support plate (210b), or may be extended and formed on the side of the second support plate (210b).

[0052] Here, the connection rod (220) and the second support plate (210b) may be fixed by screw connection, or by known fixing members such as bolts or pieces, or by welding, and such fixing method is applicable to all components forming the wafer inspection system (100).

[0053] A second flow path (221) is formed inside the connecting rod (220) to connect the first flow path (212) and the pipe (250), and the vacuum pump (260) can be connected to the pipe (250).

[0054] For example, an electric motor is used as the rotary motor (240), and the rotary motor shaft is fixed to the other end of the connecting rod (220) so that the base plate (210) can rotate.

[0055] The robot arm (230) is installed with a built-in rotary motor (240) and can move the base plate (210) forward, backward, left, and right.

[0056] That is, a vacuum atmosphere is formed in the first Euro (212) and the second Euro (221) by the operation of the vacuum pump (260), and the wafer (10) is adsorbed and fixed in a state of surface contact with the support plate (210), thereby reducing the possibility of damage to the surface of the wafer (10).

[0057] FIG. 7 is an AA section diagram shown in FIG. 4, showing the state before the wafer is placed on the support plate, and FIG. 8 is an AA section diagram shown in FIG. 4, showing the state after the wafer is placed on the support plate.

[0058] A ring insertion groove (213) may be formed along the circumference of the suction hole (211) on the upper part of the base plate (210), and an elastic body insertion groove (214) may be formed on the lower part of the ring insertion groove (213).

[0059] The inversion part (200) further includes a buffer ring (270) and an elastic body (280), and the buffer ring (270) can be manufactured from a known synthetic resin material having a certain elasticity, such as silicone.

[0060] The buffer ring (270) is inserted into the ring insertion groove (213) and communicates with the suction hole (211), and the upper end of the buffer ring (270) partially protrudes outside the base plate (210) so as to come into contact with the wafer (10) preferentially over the base plate (210).

[0061] For example, the elastic body (280) may be a compression spring and inserted into the elastic body insertion groove (214), with its lower end fixed to the lower surface of the elastic body insertion groove (214) and its upper end fixed to the lower surface of the cushioning ring (270) to support the cushioning ring (270).

[0062] That is, when the wafer (10) comes into contact with the buffer ring (270) before coming into contact with the base plate (210) and an external force is applied to the buffer ring (270), the elastic body (280) is compressed and the impact between the wafer (10) and the buffer ring (270) is offset, so that the wafer (10) comes into contact with the base plate (210), thereby further reducing the possibility of damage to the wafer (10).

[0063] FIG. 9 is a side view of FIG. 5, FIG. 10 is a side view of FIG. 6, FIG. 11 shows the state in which the inversion unit shown in FIG. 10 adsorbs and raises the wafer, FIG. 12 shows the state in which the inversion unit shown in FIG. 11 flips the wafer, FIG. 13 shows the state in which the inversion unit shown in FIG. 12 lowers the wafer, and FIG. 14 shows the state in which the wafer is separated from the inversion unit shown in FIG. 13.

[0064] Looking at the inversion process of the wafer (10), first, the robot arm (230) can insert the support plate (210) between the chuck (114) and the wafer (10) until the edge of the wafer (10) comes into contact with the wafer mounting groove (215).

[0065] Here, one of the support blocks (115) can be placed between the first support plates (210a).

[0066] Afterwards, when the robot arm (230) raises the support plate (210), the lower surface of the wafer (10) comes into contact with the buffer ring (270), and the buffer ring (270) is drawn into the interior of the support plate (210), and furthermore, the lower surface of the wafer (10) comes into contact with the upper surface of the support plate (210).

[0067] Afterwards, when the vacuum pump (260) is operated, the wafer (10) can be adsorbed to and fixed to the support plate (210).

[0068] Afterwards, when the robot arm (230) raises the base plate (210), the wafer (10) is separated from the support block (115), and when the rotary motor (240) is operated, the base plate (210) rotates so that the wafer (10) can be flipped over.

[0069] Afterwards, when the robot arm (230) lowers the support plate (210), the wafer (10) is placed back on the support block (115), and when the operation of the vacuum pump (260) is stopped, the suction force applied to the wafer (10) and the support plate (210) can be released.

[0070] Afterwards, when the robot arm (230) raises the base plate (210), the base plate (210) is separated from the wafer (10), and when the rotary motor (240) operates to rotate the base plate (210) back to its original position, the inversion of the wafer (10) can be completed.

[0071] Meanwhile, the moving part (130) and the alignment part (140) can intervene in the wafer (10) inversion to perform wafer inversion.

[0072] Unlike the above, the inversion unit (200) is fixedly positioned at a set location, and the moving unit (130) can move the wafer (10).

[0073] To explain the sequence of operations, after the wafer (10) is placed on the chuck (114), if the wafer (10) is to be inverted, the moving unit (130) can move the wafer (10) located on the chuck (114). The moving unit (130) can move the wafer (10) to the inversion unit (200). After receiving the wafer (10), the inversion unit (200) can invert the wafer (10) by performing the operation as described above. The moving unit (130) can move the inverted wafer (10) to the alignment unit (140). The moving unit (130) can move the inverted wafer (10), whose position is aligned, back to the chuck (114).

[0074] FIG. 15 is a block diagram of the control unit shown in FIG. 1, FIG. 16 shows an image of the upper surface of the wafer, FIG. 17 shows an inverted image of the lower surface of the wafer, and FIG. 18 is an enlarged view of part A shown in FIG. 16.

[0075] The control unit (150) may include a driving unit (151), a memory unit (152), an analysis unit (153), and an output unit (154).

[0076] The components forming the wafer inspection system (100) are interconnected via a wired or wireless communication network, and the driving unit (151) can selectively control operation by transmitting an operation signal to each component.

[0077] The memory unit (152) can store various data generated by the wafer inspection system (100), including the image, size, edge, and center position of the wafer (10), in real time.

[0078] The analysis unit (153) can select a subpixel (24) among a plurality of pixels (23) in the top surface image (20a) to perform phase unfolding and generate a top surface height map based on this.

[0079] The analysis unit (153) can invert and align the lower image (20b) so that a plurality of pixels (23) in the lower image (20b) are symmetrical with respect to the center line (22) of the lower image (20b), then select a subpixel (24) among the plurality of pixels (23) in the lower image (20b) to perform phase unfolding, and generate a lower height map based on this.

[0080] Here, the subpixel (24) may be selected according to any technique, algorithm, or equation known in the art, and may be configured to select one of a plurality of pixels (23) as the subpixel (24), as shown in FIG. 18, for example.

[0081] In addition, phase unwrapping may include, but is not limited to, minimum norm procedures, path following procedures, Flynn minimum discontinuity procedures, quality-guided phase unwrapping procedures, PUMA (phase unwrapping via max flows) procedures, etc., and may include any unwrapping procedure or operation known in the art for unwrapping the phase.

[0082] The analysis unit (153) can detect bending by matching the upper height map and the lower height map to generate a standard height map of the wafer (10).

[0083] For the bending of the wafer (10), such as the smile and cry types, if the height of the upper surface of the wafer (10) decreases based on the coordinate values ​​of the same pixel (23) in the image, the height of the lower surface increases relatively, so that the upper surface height map and the lower surface height map are matched to estimate the height around the non-reflective material and a standard height map can be generated.

[0084] The output section (154) can display the curved area in the standard height map.

[0085] More specifically, the output unit (154) colors the entire curved area or colors the border of the curved area to outline the curved area, so that the manager can more easily check the curve.

[0086] Although the present invention has been illustrated and described in relation to specific embodiments, it will be obvious to those skilled in the art that the present invention can be modified and changed in various ways without departing from the technical spirit of the invention as provided by the following claims. Explanation of the symbols

[0087] 10: Wafer 20: Image 20a: Top surface image 20b: Bottom surface image 21: Wafer 22: Centerline 23: Pixel 24: Subpixel 100: Wafer Inspection System 110: Case 110a: First space 110b: Second space 111: Bulkhead 112: Gate 113: Waiting Room 114: Chuck 115: Support block 120: Measurement part 121: Light source 122: Receiver 130: Movement section 140: Alignment section 200: Inversion section 210: Base plate 211: Suction port 210a: First support plate 212: 1st Euro 210b: 2nd Support Plate 213: Ring insertion groove 214: Elastic body insertion groove 215: Wafer mounting groove 220: Connecting rod 221: Euro 2 230: Robotic arm 240: Rotary motor 250: Piping 260: Vacuum pump 270: Buffering ring 280: Elastic body 150: Control unit 151: Driving unit 152: Memory unit 153: Analysis Unit 154: Output Unit

Claims

Claim 1 delete Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 A wafer inspection system comprising: a case; a moving unit disposed within the case for moving a wafer; a measuring unit disposed within the case for supporting the wafer moved by the moving unit and generating an image of the wafer; an inversion unit positioned within the case spaced apart from the moving unit for inverting the wafer when the wafer is delivered; and a control unit that generates an upper surface image of the wafer or a lower surface image of the wafer when the wafer is inverted based on the image generated by the measuring unit, and detects the bending of the wafer based on the upper surface image or the lower surface image; wherein the control unit comprises: an analysis unit that generates a surface height map of the wafer based on the upper surface image or the lower surface image; and an output unit that displays a bending area in the surface height map. Claim 7 A wafer inspection system according to claim 6, wherein the analysis unit generates an upper surface height map based on the upper surface image, generates a lower surface height map based on the lower surface image, and generates a standard height map by matching the upper surface height map and the lower surface height map. Claim 8 A wafer inspection system according to claim 7, wherein the analysis unit selects a subpixel among a plurality of pixels of the upper surface image to perform phase unfolding and generates the upper surface height map based thereon, inverts the lower surface image based on the centerline of the lower surface image, selects a subpixel among a plurality of pixels of the lower surface image to perform phase unfolding, and generates the lower surface height map based thereon.

Images