Wafer processing apparatus and wafer processing method

Abstract

The present invention relates to a wafer processing apparatus and a wafer processing method, and more particularly, to a wafer processing apparatus for trimming an edge of a wafer using a plurality of laser beams and a wafer processing method using the same. The present invention provides a wafer processing apparatus for trimming an edge portion of a wafer, characterized by comprising: a first laser head for forming a first modified surface in the edge portion along a height direction of the wafer; and a second laser head for forming a second modified surface in the edge portion along a diameter direction of the wafer, the first modified surface and the second modified surface acting as a peelable interface when the edge portion is removed by an external force.

Description

Technical Field

[0001] This invention relates to an apparatus and method for processing wafers, specifically a wafer processing apparatus that uses multiple laser beams to trim the edges of a wafer, and a wafer processing method using the same. Background Technology

[0002] Semiconductor chips are manufactured by forming multiple devices through processes such as deposition (forming a predetermined film on the surface of a semiconductor material wafer), etching (forming a predetermined pattern on the film formed on the wafer), and physical or chemical polishing or cleaning of the wafer surface. These devices are then divided into regions containing each device using a dicing device. Typically, after polishing the back side of the wafer (before devices are formed) to the designed thickness, it is diced into device chips. However, polishing the back side of the wafer creates sharp, knife-edge-like edges, causing stress concentration and cracks to propagate into the areas where devices are formed, resulting in wafer damage.

[0003] To address this issue, as described in prior art document KR10-2022-0157822A, a technique is proposed that involves using a cutting blade to circumferentially cut the edge of the wafer, irradiating it with a laser beam to remove the damaged layer, and then grinding the opposite side of the wafer to thin it. Edge trimming further prevents wafer cracking by processing the chamfered portion of the wafer edge into a vertical surface.

[0004] However, hybrid bonding of two or more wafers (wafer-to-wafer, hereinafter referred to as "W2W wafer") presents a problem where the cutting blade can easily damage the device due to cracks during wafer trimming. While it is possible to pre-trimme each wafer and then bond them via hybrid bonding, the trimming process involves using cutting blades and water polishing to remove debris, generating a large amount of waste that becomes a source of contamination in the hybrid bonding process, making it difficult to apply in practice. In other words, in W2W hybrid bonding, where contamination needs to be managed at the nanometer level, the method of pre-trimming the edges with cutting blades cannot be used.

[0005] Therefore, a trimming technique is needed that can accurately remove the edges of W2W wafers without generating contaminants after hybrid bonding.

[0006] (Patent Document 1) KR10-2022-0157822A (2022.11.29) Summary of the Invention

[0007] The purpose of this invention is to provide a wafer processing apparatus and method that can remove the edges of mixed-bonded W2W wafers without generating pollution sources.

[0008] In particular, the aim is to provide a wafer processing apparatus that can analyze the degree of wafer curvature by measuring the height of the upper surface of the W2W wafer and accurately remove the wafer edge based on this information.

[0009] According to an embodiment of the present invention, a wafer processing apparatus is a wafer processing apparatus for trimming the edge portion of a wafer, characterized in that the wafer processing apparatus includes: a first laser head for forming a first modified surface on the edge portion along the height direction of the wafer; and a second laser head for forming a second modified surface on the edge portion along the diameter direction of the wafer, wherein when the edge portion is removed by external force, the first modified surface and the second modified surface act as a peeling interface.

[0010] In one embodiment of the present invention, a first laser beam emitted from the first laser head and a second laser beam emitted from the second laser head may be transmitted through the outer surface of the wafer to form the first modified surface and the second modified surface, respectively.

[0011] In one embodiment of the present invention, the second laser head further includes a beam splitter for splitting the laser source, and the second laser beam may be a plurality of beams split by the beam splitter.

[0012] In one embodiment of the present invention, the wafer processing apparatus may further include a height measuring sensor for measuring the height of the outer surface of the wafer, and the focusing position of the first laser head and the focusing pattern of the second laser head may be corrected based on the height distribution of the outer surface measured by the height measuring sensor.

[0013] In one embodiment of the present invention, the height measurement sensor may measure the height of the outer surface of the edge portion, and the calibration of the first laser head and the second laser head may be performed only at the edge portion.

[0014] In one embodiment of the present invention, the wafer processing apparatus may further include a first controller for controlling the first laser head and a second controller for controlling the second laser head. The first controller and the second controller are connected to a control unit that controls the entire wafer processing apparatus and the edge portion is trimmed by the correction.

[0015] In one embodiment of the present invention, the first controller controls the movement distance of the first laser head and the second controller controls the movement distance of the second laser head to be within 10 micrometers.

[0016] In one embodiment of the present invention, the spacing between the beams of the plurality of second laser beams split by the beam splitter may be limited to the range of 3 micrometers to 30 micrometers.

[0017] In one embodiment of the present invention, the first modified surface may be formed by the aggregation of first modified portions in the shape of spots formed by the first laser head, and the second modified surface may be formed by the aggregation of second modified portions in the shape of spots formed by the second laser head, wherein the first modified portion and the second modified portion include cracks generated by laser processing.

[0018] In one embodiment of the present invention, the control unit may measure the height of the outer surface of the wafer using the height measurement sensor during the period when the first laser head and the second laser head are about to be started.

[0019] In one embodiment of the present invention, the control unit may perform a first patterning step, which generates a height contour image based on the height distribution of the outer surface of the wafer measured by the height measurement sensor, divides the surface of the edge portion into multiple segmentation units (cells) of a certain size, and maps them to have the same height value within the segmentation units.

[0020] In one embodiment of the present invention, in the first patterning step, the height value mapped to each of the segmented units may be the median of the height measured by the height measurement sensor within the corresponding segmented unit.

[0021] In one embodiment of the present invention, the control unit may perform a second patterning step after the first patterning step, wherein the second patterning step maps the segmentation units within a certain range to have the same height value based on the distance of the segmentation unit from the center of the wafer.

[0022] In one embodiment of the present invention, the wafer may be a W2W wafer (Wafer-to-Wafer) manufactured by hybrid bonding.

[0023] In another aspect of the present invention, the wafer processing method utilizes a wafer processing apparatus comprising: a first laser head forming a first modified surface along the height direction of the wafer at an edge; a second laser head forming a second modified surface along the diameter direction of the wafer at the edge; a height measuring sensor measuring the height of the outer surface of the wafer; and a control unit, characterized in that the control unit controls the first laser head and the second laser head such that when the edge is removed by external force, the first modified surface and the second modified surface act as a peeling interface, the wafer processing method comprising: a wafer outer surface height measurement step, measuring the height of the outer surface using the height measuring sensor; and a laser focus position correction step, correcting the focus position of the first laser head and the focus pattern of the second laser head based on the height distribution measured by the height measuring sensor.

[0024] In one embodiment of the present invention, the following steps may be performed before the laser focusing position correction step and after the wafer outer surface height measurement step: a height image generation step, generating a height contour image based on the height distribution of the outer surface of the wafer measured by the height measurement sensor; an edge region segmentation step, dividing the surface of the edge portion into multiple segmentation units (cells) of a certain size; and a first patterning step, mapping the segmented units to have the same height value.

[0025] In one embodiment of the present invention, in the first patterning step, the height value mapped to each of the segmented units may be the median of the height measured by the height measurement sensor within the corresponding segmented unit.

[0026] In one embodiment of the present invention, a second patterning step may be performed after the first patterning step, wherein the second patterning step maps the segmentation units, which are within a certain range based on the distance of the segmentation unit from the center of the wafer, to have the same height value.

[0027] In one embodiment of the present invention, the wafer may be a W2W wafer (Wafer-to-Wafer) manufactured by hybrid bonding.

[0028] In another aspect, the wafer processing apparatus of the present invention is a wafer processing apparatus for trimming the edge portion of a W2W (Wafer-to-Wafer) wafer manufactured by hybrid bonding. The apparatus is characterized by comprising: a first laser head for forming a first modified surface along the height direction of the wafer at the edge portion; a second laser head having a beam splitter comprising a beam splitter for forming a second modified surface along the diameter direction of the wafer at the edge portion using multiple laser beams; a height measurement sensor for measuring the height of the outer surface of the wafer; a first drive unit for driving the first laser head; a second drive unit for driving the second laser head; a first controller for controlling the first drive unit; a second controller for controlling the second drive unit; and a control unit for controlling the entire wafer processing apparatus, wherein the control unit controls the first controller and the second controller, such that when subjected to external force... When removing the edge portion, the first modified surface and the second modified surface act as the peeling interface. Furthermore, the control unit corrects the focusing position of the first laser head and the focusing pattern of the second laser head based on the height distribution of the outer surface measured by the height measurement sensor. The wafer processing apparatus performs the following steps: a height image generation step, generating a height contour image based on the height distribution measured by the height measurement sensor; an edge region segmentation step, dividing the surface of the edge portion into multiple segmentation units (cells) of a certain size; a first patterning step, mapping the median height within each segmentation unit to a height; and a second patterning step, mapping segmentation units whose distance from the center of the wafer is within a certain range to have the same height value.

[0029] According to one embodiment of the present invention, the edges of mixed-bonded W2W wafers are removed without generating a source of contamination.

[0030] According to one embodiment of the present invention, edge trimming is performed using multiple lasers, which has the effect of preventing cracks from spreading from the edge to the inside during the grinding of W2W wafers.

[0031] According to one embodiment of the present invention, unlike the existing cutting method using blades, a modified part is formed inside the wafer using a transmitted laser, thus achieving the effect of not generating processing contaminants.

[0032] According to one embodiment of the present invention, even if the surface of the W2W wafer is uneven due to warpage, the laser processing position can be adjusted using the upper surface height information, thus having the advantage of accurately removing edges.

[0033] According to one embodiment of the present invention, unlike existing methods that grind the entire edge region, there is an advantage that only the annular edge portion processed by dual lasers can be peeled off in one go, thus shortening the process time. Attached Figure Description

[0034] Figure 1 This is a diagram illustrating an example of a W2W wafer fabricated via hybrid bonding.

[0035] Figure 2 This is a simplified perspective view of a wafer processing apparatus according to an embodiment of the present invention.

[0036] Figure 3 This is a simplified structural diagram of a wafer processing apparatus according to an embodiment of the present invention.

[0037] Figure 4 This is a diagram illustrating an example of a wafer processing apparatus according to an embodiment of the present invention using multiple lasers to form modified surfaces.

[0038] Figure 5 This is a diagram illustrating a method for controlling a laser head during the formation of a modified surface in a wafer processing apparatus according to an embodiment of the present invention.

[0039] Figure 6 This is a schematic diagram illustrating the correction of laser processing by a wafer processing apparatus according to an embodiment of the present invention.

[0040] Figure 7 This is a schematic diagram illustrating the first patterning step of patterning edge height in a wafer fabrication apparatus according to an embodiment of the present invention.

[0041] Figure 8 This is a schematic diagram illustrating the second patterning step of repatterning the edge height in a wafer fabrication apparatus according to an embodiment of the present invention.

[0042] Figure 9 This is a diagram illustrating the edge removal apparatus for removing the edges of a W2W wafer according to an embodiment of the present invention.

[0043] Figure 10 This is a diagram showing a cross-section of the edge of a W2W wafer after edge removal using an edge removal device according to an embodiment of the present invention.

[0044] Figure 11 This is a diagram showing a grinding apparatus grinding one side of a wafer according to an embodiment of the present invention.

[0045] Figure 12 This is a process flow diagram illustrating a wafer fabrication method according to an embodiment of the present invention.

[0046] Figure 13This is a process flow diagram illustrating the laser processing correction step in a wafer processing method according to an embodiment of the present invention.

[0047] (Explanation of reference numerals in the attached diagram)

[0048] 11: Outer surface of the first wafer

[0049] 30: W2W wafer

[0050] 31: Edge

[0051] 40: First laser head

[0052] 41: First laser beam

[0053] 50: Second laser head

[0054] 51: Second laser beam

[0055] 60: Height Measurement Sensor

[0056] 73: Second modified surface

[0057] 74: First Modified Surface

[0058] 77: Segmentation Unit

[0059] 92: Remove unit Detailed Implementation

[0060] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, so as to enable those skilled in the art to implement the invention. However, the present invention can be implemented in various different forms and is not limited to the embodiments described herein.

[0061] To clearly illustrate the present invention, parts unrelated to the description have been omitted, and the same or similar components are marked with the same reference numerals throughout the specification.

[0062] Furthermore, in multiple embodiments, the same reference numerals are used to describe only representative embodiments of the constituent elements having the same structure, while in other embodiments, only structures different from the representative embodiments are described.

[0063] In the specification as a whole, when a part "includes" a certain constituent element, unless otherwise stated otherwise, it means that it may also include other constituent elements rather than exclude other constituent elements.

[0064] In addition, in the specification as a whole, the term "trimming" a component means, unless otherwise specified, removing the edges, excess material, or unnecessary parts of that component.

[0065] In the overall specification, "modified part" refers to a modified point (spot) generated inside the wafer through laser processing. It also includes micro-cracks generated in a specific direction as the laser energy instantly melts and solidifies the part, causing changes in volume and mechanical properties.

[0066] Furthermore, in the overall specification, "modified surface" refers to a three-dimensional surface formed by the aggregation of the modified parts, meaning that it includes not only the modified spots formed by laser processing, but also the cracks generated around them.

[0067] Unless otherwise defined, all terms used herein, including technical or scientific terms, shall have the same meaning as commonly understood by one of ordinary knowledge in the art to which this invention pertains. Terms such as those defined in commonly used dictionaries shall be interpreted as having the same meaning as in the relevant technical context, and shall not be ideally or excessively interpreted as having a formal meaning unless expressly defined in this application.

[0068] First, using Figures 1 to 3 A wafer processing apparatus according to an embodiment of the present invention will be described in detail. Figure 1 This is an example of a W2W wafer fabricated through hybrid bonding. Figure 2 as well as Figure 3 This is a simplified structure of a wafer processing apparatus according to an embodiment of the present invention.

[0069] Hybrid bonding typically involves activating the wafer surfaces (the surfaces to be bonded) through plasma processing in a W2W stacking manner, followed by bonding the wafers together. Hybrid bonding offers the advantage of simultaneously achieving both electrical connections and physical bonding between chips. Compared to existing technologies like TSV (Through-Silicon Via), hybrid bonding ensures higher connection density and superior signal transmission performance, thus making it a preferred 3D integration technology.

[0070] On the other hand, when contaminants caused by edge cutting are present on the wafer surface during the hybrid bonding process, the bonding quality may be affected. Therefore, there is a need for a device that can perform edge cutting on the W2W wafer itself without contaminants after the bonding between wafers is completed.

[0071] Figure 1This diagram illustrates a W2W wafer 30 fabricated via hybrid bonding. A first wafer 10 and a second wafer 20, both circular in shape, can be bonded together to form the W2W wafer 30 (a bonded wafer or a composite wafer). The first device layer 12 of the first wafer 10, on which devices are formed, and the second device layer 22 of the second wafer 20, on which devices are formed, can be bonded together after plasma surface activation and then strongly bonded through pressing, bonding, and subsequent heat treatment. The unbonded side of the W2W wafer 30 may have a first outer wafer surface 11 and a second outer wafer surface 21.

[0072] The first device layer 12 and the second device layer 22 can refer to the device formation surface formed by semiconductor device manufacturing processes on each of the first wafer 10 and the second wafer 20, or they can be layers comprising multiple dies bonded to each of the first wafer 10 and the second wafer 20 by separate die bonding processes. That is, the hybrid bonding in the embodiments of the present invention should be understood to include bonding between wafers or bonding between dies pre-bonded on the wafer.

[0073] Generally, the circular W2W wafer 30 may include an annular edge 31 without devices formed. A central portion 32 with devices formed is provided inside the edge 31. For example... Figure 1 As shown, the edge portion 31 is formed along the outer periphery of the W2W wafer 30, and its outer cross section is smooth and curved outward. When the outer surfaces 11 and 21 are ground to adjust the thickness of the wafer to the design value, only a portion of the curved cross section of the edge portion 31 is removed, forming a sharp knife-edge, which can also generate cracks under weak impact and become the starting point for inward expansion.

[0074] Figure 2 A wafer processing apparatus according to an embodiment of the present invention is shown. The wafer processing apparatus of the present invention, as a device for trimming the edge portion of a wafer, may include a first laser head 40 for processing in the height direction of the wafer and a second laser head 50 for processing in the diameter direction of the wafer.

[0075] The first laser head 40 and the second laser head 50 are independently constructed, and the first laser head 40 and the second laser head 50 can be controlled by independent controllers as described later. Figure 3 49 and 59) respectively control their positions and the intensity of the laser beam. The first laser beam 41 emitted from the first laser head 40 can penetrate the outer surface 11 of the first wafer 10 and be focused on the hybrid bonding interface. Figure 1The first device layer 12 and the second device layer 22 are bonded to adjacent portions, thereby forming a modified surface in the height direction of the wafer with a "|" shape. Moreover, the second laser beam 51 emitted from the second laser head 50 can penetrate the first wafer outer surface 11 of the first wafer 10 and be focused on the adjacent portions of the hybrid bonding bonding surfaces, thereby forming a modified surface in the diameter direction of the W2W wafer 30 with a "-" shape from the outside to the inside.

[0076] The second laser head 50 also includes a beam splitter (not shown) that divides the laser source into multiple beams. The split second laser beam 51 can also transmit through the outer surface 11 of the first wafer, while simultaneously dividing the modified portion (see reference) Figure 4 Multiple modified sections are formed (71) simultaneously along the diameter of the W2W wafer 30, thus shortening the process time. The beam splitter can be a reflective or transmissive beam splitter, a dichroic prism, or an optical fiber distributor, etc.

[0077] like Figure 2 As shown, in a wafer processing apparatus according to an embodiment of the present invention, a height measuring sensor 60 may be further included on the upper side of the W2W wafer 30, capable of measuring the height of a first outer surface 11 of the outer surface of the W2W wafer 30. The height measuring sensor 60 particularly accurately measures the height near the edge portion 31 in the first outer surface 11 and transmits the height distribution to a control unit 110 that controls the entire wafer processing apparatus, thereby allowing the focusing position of the first laser head 40 and the focusing pattern of the second laser head 50 to be corrected based on this information. The focusing position is determined by a modification section modified by the first laser beam 41 and the second laser beam 51, which determines the shape of the edge portion to be removed by subsequent processes. The method for correcting the focusing position of the first laser head 40 and the focusing pattern of the second laser head 50 will be described in detail later.

[0078] like Figure 2 As shown, when laser processing is performed on the edge using the first laser head 40 and the second laser head 50, the W2W wafer 30 can be rotated by the chuck 80 that holds it, and the modified surface formed by the first laser beam 41 (see reference) Figure 4 74) becomes a ring-shaped strip, and the modified surface formed by the second laser beam 51 (refer to) Figure 4 73) becomes a hollow, annular disk. Specific details will be explained later. Figure 2 The diagram shows that the W2W wafer 30 is laser-processed while rotating via the chuck 80, but the first laser head 40 and the second laser head 50 can also rotate while the W2W wafer 30 is stationary.

[0079] Then use Figure 3The control structure of a wafer processing apparatus according to an embodiment of the present invention will be described in detail.

[0080] According to an embodiment of the present invention, the wafer processing apparatus may further include a first driving unit 47 for moving the first laser head 40, and may further include a second driving unit 57 for moving the second laser head 50. The first driving unit 47 is controlled by a separately configured first controller 49, which is centrally controlled by a control unit 110 that controls the entire wafer processing apparatus. The second driving unit 57 is controlled by a separately configured second controller 59, which is centrally controlled by the control unit 110 that controls the entire wafer processing apparatus.

[0081] The first driving unit 47 can drive the first laser head 40 up and down in the height direction of the wafer, and can also move it forward, backward and left and right, thereby flexibly adjusting the focusing position of the first laser beam 41. The second driving unit 57 can drive the second laser head 50 left and right in the diameter direction of the wafer, and can also move it forward, backward and up and down, thereby flexibly adjusting multiple positions focused by the second laser beam (51).

[0082] The movement control of the first drive unit 47 and the second drive unit 57 can be controlled with a pitch of less than 10 micrometers, taking into account the crystal orientation of a typical wafer.

[0083] like Figure 3 As shown, in a wafer processing apparatus according to an embodiment of the present invention, a measuring sensor 60 that can measure the height of the outer surface of the W2W wafer 30 can be selectively integrated with the first controller 49 and the second controller 59 and fabricated into a package to correct the focusing position of the first laser head 40 and the focusing pattern of the second laser head 50. This provides the advantages of simplifying system design and setup by integrating into a single package, accelerating data exchange speed, and simplifying maintenance.

[0084] The second laser head 50 also includes a splitter (not shown) for splitting the laser source into multiple beams. The split second laser beams 51 can also penetrate the outer surface 11 of the first wafer, while forming multiple modified portions. For single-crystal wafers, cleaving is easy on specific crystal planes including crystal faces, and the spacing between the split beams of the second laser beams 51 can be determined by considering the crystal planes. For example, for a {100} single-crystal wafer, cleaving is easy on specific crystal planes including crystal face {111}, so the spacing between the split beams of the second laser beams 51 can be determined in the range of 3 micrometers to 30 micrometers. More preferably, the splitting should be within 10 micrometers to reduce the generation of cracks extending along the {111} crystal plane.

[0085] According to an embodiment of the present invention, the wafer processing apparatus may further include a chuck 80 for adsorbing and holding the W2W wafer 30. During laser processing of the edge portion 31, the chuck 80 rotates via a rotation shaft 81 connected to its lower portion, simultaneously rotating the W2W wafer 30. The rotational speed of the chuck 80 is controlled by a control unit 110, and the annular strip-shaped modified surface (see reference) generated by the first laser head 40... Figure 4 74) and the annular disk-shaped modified surface generated by the second laser head 50 (see reference). Figure 4 73) is appropriately formed so that it can be easily peeled off by process external force through the removal device 90 described later.

[0086] Next, using Figure 4 as well as Figure 5 The wafer processing method using a wafer processing apparatus according to an embodiment of the present invention and the morphology of the modified surface formed therefrom are described in detail.

[0087] Laser modification is performed inside the W2W wafer 30 using a first laser beam 41 and a second laser beam 51. Figure 4 The first laser beam 41 moves along the z-axis, i.e., along the height of the wafer 30, to form a first modified portion 72. The second laser beam 51 moves from the outside to the inside along the diameter of the wafer 30 to form a second modified portion 71. Here, laser modification refers to a portion of the wafer becoming different from its surroundings in terms of density, refractive index, mechanical strength, or other physical properties. The modified portion or the modified surface formed therefrom can be, for example, divided into regions of crack initiation, solidification after melting, insulation failure, and refractive index change, and also includes cases where all of these states coexist.

[0088] More specifically, the first modified portion 72 can be a series of continuously modified points (spots) along the z-axis direction, i.e., along the height direction of the wafer 30. The points modified by the laser beams 41 and 51 may undergo instantaneous melting and solidification by the laser energy, resulting in changes in volume and mechanical properties, including micro-cracks (not shown) in a specific direction. When external force is applied by the edge removal device 90, these cracks at the points can facilitate the peeling of the edge portion 31.

[0089] The spacing between the points formed by the first laser beam 41 is a spacing set while the first laser head 40 moves in the z-axis direction. This spacing can be set by the first controller 49 to a degree that allows cracks included in the points to connect with cracks formed at the surrounding points. Thus, the first modified portions 72 converge to form an annular strip-shaped first modified surface 74 that can be easily removed through the points and their cracks, allowing for removal in the removal step (see reference). Figure 9 as well as Figure 12 In S40), it is easily peeled off by the removal device 90.

[0090] Furthermore, the spacing between the points formed by the second laser beam 51 is equal to the distance between the points formed by the second laser head 50 in the vertical direction. Figure 4 The spacing set while moving along the x-axis can be configured by the second controller 59 to a distance such that the crack at the point can connect with the cracks formed at the surrounding points. Thus, the plurality of second modified portions 71 converge to form an annular disk-shaped second modified surface 73 that can be easily removed through the point and its cracks, allowing for removal in the removal step (see reference). Figure 9 as well as Figure 12 The material is easily peeled off in the S40 by the removal device 90.

[0091] The second laser beam 51 is split into multiple beams by a beam splitter, and after forming multiple modified points, it is quickly moved to the focal point to be formed by reconnecting the multiple points.

[0092] On the other hand, the height H of the first modified surface 74 of the W2W wafer 30 in the z-axis direction can be set to be less than the thickness T of the first wafer 10 and greater than the design value to be removed by subsequent grinding of the outer surface 11 of the first wafer.

[0093] In one embodiment of the present invention, if the shapes of the first modified surface 74 and the second modified surface 73 are completed by a laser edge modification step, such as... Figure 4 As shown, the cross-section is formed into an "L"-shaped modified surface.

[0094] Next, using Figure 6 A detailed description of a laser processing correction method using a height measurement sensor 60 in a wafer processing apparatus according to an embodiment of the present invention.

[0095] In one embodiment of the present invention, if the hybrid-bonded W2W wafer 30 is rotated, the edge portion 31 of the first wafer 10 is simultaneously processed in the height direction (z-axis direction) and the vertical direction (-x-axis direction) using multiple laser beams 41 and 51. At this time, the height change rate of the upper surface of the first wafer 10, i.e., the degree of curvature, is measured by a height measurement sensor 60, and the focusing position of each laser beam 41 and 51 is corrected based on this.

[0096] First, in a wafer processing apparatus according to an embodiment of the present invention, if the W2W wafer 30 is attached to the chuck 80, then while the height measuring sensor 60 is operating, the height of the edge portion 31 of the W2W wafer 30 is measured while the chuck 80 rotates at a constant speed. The height measuring sensor 60, as a single sensor, can be an ultrasonic distance sensor, a laser distance sensor, an infrared distance sensor, or a 3D camera sensor that measures depth using two or more cameras. Alternatively, it can be composed of a sensor unit that selectively combines multiple sensors to simultaneously measure the height of multiple points.

[0097] The height measurement sensor 60 can selectively operate during preparation for driving the first laser head 40 and the second laser head 50 to measure the height of the outer surface 11 of the W2W wafer 30. Additionally, as... Figure 5 As shown, the height measurement sensor 60 can measure not only the height of the edge portion 31, but also the height of the center portion 32 of the W2W wafer 30.

[0098] Next, according to an embodiment of the present invention, the control unit 110 generates a height image (3D surface profiling) of the W2W region in the wafer 30 area based on the height information of each part input from the height measurement sensor 60. For example... Figure 6 As shown, the height image can be a contour image that can be plotted on the surface of wafer 30. Additionally, in one embodiment of the invention, the surface of the edge portion 31 is segmented into multiple segmentation units 77. The size of the segmentation unit 77 is related to the accuracy of the focusing position control of the laser beams 41 and 51; excessive segmentation may lead to difficulties in control and increased processing time. Figure 6 In this diagram, light and dark represent height, thus it can be seen that each element corresponding to a position within a specific segmentation unit 77 has a different height value than the others. Next, in one embodiment of the invention, the information is converted into controllable information for the first laser head 40 and the second laser head 50 through multiple patterning steps.

[0099] use Figure 6 as well as Figure 7 The first patterning step (S24) according to an embodiment of the present invention will be described in detail.

[0100] In the first patterning step (S24) of the present invention, the height distribution is determined according to the segmentation units 77 divided by the edge region segmentation, and the median in each segmentation unit 77 is mapped to a representative height. That is, in Figure 7In the diagram, the internal height of segmentation unit 77, marked with ①, has a constant distribution and varies, but is mapped to its median A, and the height of all regions within that segmentation unit 77 is replaced with A. Similarly, the internal height of segmentation unit 77, marked with ②, has a constant distribution and varies, but is mapped to its median B, and the height of all regions within that segmentation unit 77 is replaced with B. Likewise, the internal height of segmentation unit 77, marked with ③, has a constant distribution and varies, but is mapped to its median C, and the height of all regions within that segmentation unit 77 is replaced with C. For example... Figure 6 As shown, since the height of each segmentation unit 77 is constant according to the first patterning step (S24), it can be seen that the brightness and darkness of the 3D image are the same in each segmentation unit 77.

[0101] Next, using Figure 6 and Figure 8 The second patterning step (S25) according to an embodiment of the present invention will be described in detail.

[0102] In the second patterning step (S25) of the present invention, smoothing is performed based on the first patterning result to reduce the variability of the height distribution. For more detailed explanation, for example... Figure 8 As shown, segmentation units 77 whose distance from the center of W2W wafer 30 to the center of segmentation unit 77 is within a certain range are marked as the same group. Similar to the first patterning step (S24), the median height within each group can be replaced with the height of all segmentation units 77 belonging to each group. Figure 8 As shown, at the center of W2W wafer 30, the partitioning unit 77 with radius r1 is labeled as group ①, and its height is replaced by its median. Additionally, at the center of W2W wafer 30, the partitioning unit 77 with radius r2 is labeled as group ②, and its height is replaced by its median. Figure 8 As shown, if the second patterning step (S25) ends, the heights of the segmentation units 77 with the same radius become the same, and they also have the same brightness.

[0103] In one embodiment of the present invention, by first patterning, specific segmentation units 77 have the same height value, and by second patterning, segmentation units 77 at the same distance from the center of the W2W wafer 30 have the same height value overall. This reduces the number of times the focusing positions of the first laser beam 41 and the second laser beam 51 are controlled based on the height distribution, thus reducing working time. For example, in order to form the first modified surface 74, the control unit 110 can instruct the first controller 49 to calculate the distance (radius) from the center of the W2W wafer 30 to the first modified surface 74, and correct the processing position of the first laser head 40 based on the height value of the segmentation unit 77 located at that distance. The first controller 49, receiving the instruction from the control unit 110, controls the first drive unit 47 to correct the focusing position of the first laser beam 41. At this time, the first modified surface 74 is located at the same distance from the center of the W2W wafer 30, and only one correction is sufficient.

[0104] like Figure 8 As shown, in the second patterning step (S25) according to an embodiment of the present invention, although the segmentation units 77 located at the same distance from the center of the W2W wafer 30 are mapped to have the same height value, they can also be selectively patterned to be divided by angles, so that even at the same distance, they have different values. For example, the angles of the overall disk-shaped W2W wafer 30 can be divided at 90-degree intervals, so even the segmentation units 77 at the same distance can be mapped to have different heights according to quadrants. Alternatively, the 90-degree intervals can be selectively divided more finely into 45-degree intervals.

[0105] In one embodiment of the invention, a removal device 90 is used to remove the edge portion 31 that has been laser-processed by the first laser head 40 and the second laser head 50. For example... Figure 9 As shown, in one embodiment of the present invention, the removal device 90 is used to peel off the edge portion 31 of the laser-modified W2W wafer 30, and may include a holding stage 91 for adsorbing and supporting the W2W wafer 30 and a removal unit 92. Additionally, the removal unit 92 may further include a plurality of generally hook-shaped holding members 93. First, the laser-modified W2W wafer 30 with the edge portion 31 is adsorbed onto the holding stage 91, and the removal unit 92 is lowered. At this time, the holding members 93 are positioned away from each other from the W2W wafer 30, and will not contact the W2W wafer 30 during the descent of the removal unit 92.

[0106] If the removal unit 92 is sufficiently lowered to be directly above the W2W wafer 30, such as Figure 9As shown, the removal device 90 brings the plurality of gripping members 93 close together to the point where they can hook onto the edge 31 of the W2W wafer 30. If the gripping members 93 are brought to the point where they can only hook onto the edge 31 and peel off, the removal unit 92 is lifted, peeling off the modified area of ​​the edge 31 in one step, i.e., the area divided into the first modified surface 74 and the second modified surface 73 (see reference). Figure 4 ).

[0107] In one embodiment of the present invention, the first modified surface 74 and the second modified surface 73 are pre-processed into an approximately "L" shape at the edge portion 31 using the first laser head 40 and the second laser head 50. The mechanical strength of the modified surfaces is weakened relative to other areas of the W2W wafer 30, and they can be easily peeled off in one step by the removal device 90. Furthermore, the height distribution of the outer surface 11 of the W2W wafer 30 is measured using the height measurement sensor 60 employed in one embodiment of the present invention, and the positions of the first modified surface 74 and the second modified surface 73 are corrected through the first patterning step (S24) and the second patterning step (S25). Therefore, even if the W2W wafer 30 warps and its surface bends, the edge portion 31 can be accurately removed according to the design dimensions. Moreover, unlike existing technologies using cutting blades, this method has the advantage of not generating contaminants during edge trimming.

[0108] It is possible Figure 10 It is confirmed that the cross-section of the W2W wafer 30 with edge portion 31 is removed by a wafer processing method according to an embodiment of the present invention. It is known that the upper part of edge portion 31 is trimmed along the first modification surface 74 and the second modification surface 73.

[0109] In one embodiment of the present invention, such as Figure 11 As shown, the first outer surface 11 of the W2W wafer 30, whose edge portion 31 has been trimmed, can be thinned using a grinding wheel 100. Mechanical and chemical polishing can be performed using a grinding wheel 100 equipped with a polishing pad 102, with the first outer surface 11 of the W2W wafer 30 facing upwards, held in place by the chuck stage 105. The grinding wheel 100 rotates at a constant speed via a spindle 101, and the chuck stage 105 also rotates, thus reducing the height of the first outer surface 11. Selectively, while rotating, the grinding wheel 100 moves forward, backward, left, and right in a specific pattern to avoid leaving polishing marks on the W2W wafer 30.

[0110] In the wafer processing flow according to an embodiment of the present invention, since the edge portion 31 is pre-trimmed to an accurate size using the first laser head 40 and the second laser head 50, a knife-edge will not form on the edge portion 31 during the thinning process using the grinding wheel 100. This avoids the formation of cracks on the edge portion 31 that could spread into the interior of the wafer 30.

[0111] Next, using Figure 12 This paper details a wafer fabrication method according to an embodiment of the present invention.

[0112] A wafer fabrication method according to an embodiment of the present invention may include a laser processing correction step (S20), an edge modification step (S30), and an edge removal step (S40). In one embodiment of the present invention, firstly, a W2W (Wafer-to-Wafer) wafer 30 is fabricated by bonding multiple wafers 10, 20 through a wafer forming step (S10). The bonding method may be hybrid bonding. Figure 1 As shown, the first device layer 12 of the first wafer 10 and the second device layer 22 of the second wafer 20 are bonded together by hybrid bonding. Alternatively, one side of the first wafer 10 may form an unbonded first wafer outer surface 11, and one side of the second wafer 20 may form an unbonded second wafer outer surface 21. On the other hand, as... Figure 1 Unlike the previous version, the second wafer 20 of the present invention can be a wafer used simply for support without forming the second device layer 22.

[0113] Next, in the laser processing correction step (S20), with Figure 2 as well as Figure 3 As an example, the height distribution of the outer surface 11 of the first wafer to be ground on the W2W wafer 30 is measured by the height measurement sensor 60 of the wafer processing apparatus, and the processing positions of the first laser head 40 and the second laser head 50 are corrected based on this, i.e., the focusing positions of the first laser beam 41 emitted from the first laser head 40 and the second laser beam 51 emitted from the second laser head 50. The laser processing correction step (S20) is used to correct the flatness of the outer surface 11 of the first wafer in the hybrid-bonded W2W wafer 30, assuming that the bottom surface of the first wafer 10 is flat. More specifically, the focusing starting position of the first laser beam 41 and the focusing pattern information of the second laser beam 51 are corrected based on the measured height distribution. For example, if the thickness of the first wafer 10 of the W2W wafer 30 is 775 micrometers, and the focusing target position of the first laser beam 41 is at a depth of 725 micrometers relative to the outer surface 11 of the first wafer, and the height distribution at this position is +5 micrometers, then the focusing position of the first laser beam 41 is corrected to 720 micrometers through correction.

[0114] Reference Figure 4 The position of the first laser beam 41 is only for correcting the initial focusing position, while the position of the second laser beam 51 is in the center direction of the W2W wafer 30 during the rotation of the chuck 80. Figure 5 Move it along the -x axis and repeatedly correct it.

[0115] Next, in the edge modification step (S30), multiple laser heads 40 and 50 are used to form a first modified surface 74 and a second modified surface 73 on the edge portion 31 of the W2W wafer 30. The first modified surface 74 refers to the surface formed by the first laser head 40 from the focusing starting position of the corrected first laser beam 41 along the height direction of the W2W wafer 30. Figure 4 The first modified portion 72, which forms a point shape, is a continuous surface formed by moving along the z-axis direction. Additionally, the second modified surface 73 refers to the surface formed by the second laser head 50 starting from the edge of the W2W wafer 30 and extending along the center direction of the W2W wafer 30. Figure 5 The second modified portion 71, which is formed in a point shape while moving in the -x-axis direction, has multiple continuously formed surfaces. The focusing position of the second laser beam 51 is continuously corrected during processing based on the height distribution measured by the height measurement sensor 60, so that the second modified surface 73 can be accurately formed even when the wafer 30 is bent.

[0116] Next, in the edge removal step (S40) according to an embodiment of the present invention, the edge portion 31 of the W2W wafer can be removed by external force using the removal device 90. For example... Figure 9 As shown, with the holding stage 91 of the removal apparatus 90 holding and supporting the W2W wafer 30 after the edge modification step (S30), the removal unit 92 is moved to apply external stress to the edge portion 31, where the first modified surface 74 and the second modified surface 73 are formed in an approximately "L" shape. The edge removal step (S40) is similar to the process of mechanically debonding composite wafers, where the holding member 93 is brought into the edge portion 31 and then lifted to apply shear force in the thickness direction. The W2W wafer 30, with the process completed through the edge removal step (S40), is shown... Figure 10 .

[0117] According to an embodiment of the present invention, the wafer grinding step (S50) is a process of grinding the outer surface 11 of the W2W wafer 30, from which the edge portion 31 is removed, to thin it to a desired level of thickness. Figure 11 As shown, while the grinding wheel 100 rotates, the outer surface 11 of the W2W wafer 30 is mechanically and chemically ground by the grinding pad 102 attached to its lower part. Selectively, the grinding wheel 100 can be moved back and forth and left and right while grinding, or the W2W wafer 30 can be rotated together while grinding.

[0118] Next, using Figure 13 The laser processing correction steps (S20) will be explained in more detail.

[0119] The laser processing correction step (S20) according to an embodiment of the present invention includes a wafer upper surface height measurement step (S21), a height image generation step (S22), an edge region segmentation step (S23), a first patterning step (S24), a second patterning step (S25), and a laser focus position correction step (S26). The laser focus position correction step (S26) has been described in sufficient detail above, so the description will focus on the patterning steps (S24, S25).

[0120] According to an embodiment of the present invention, the wafer upper surface height measurement step (S21) is a process of acquiring the height distribution of the outer surface 11 of the W2W wafer 30 using a height measurement sensor 60. More specifically, the process of acquiring the height distribution using the height measurement sensor 60 can be performed simultaneously with the chuck 80, which holds the W2W wafer 30, rotating at a constant speed during the preparation of the first laser head 40 and the second laser head 50. The wafer upper surface height measurement step (S21) can selectively measure only the edge portion 31, as shown in Figure 6, or it can also measure the height distribution of the center portion 32 of the W2W wafer 30. When the height measurement sensor 60 is a single sensor, the measurement can be performed while moving the position of the height measurement sensor 60. In the form of a measurement unit combining multiple sensors, the height of multiple points can be measured simultaneously, and the measurement can be moved to the next measurement position.

[0121] Next, in the height image generation step (S22), the control unit 110 can generate a height image (3D surface profiling) within the wafer 30 region based on the height dimensions of each part input from the height measurement sensor 60. The height image can be a contour line drawn on the surface of the wafer 30. If the height measurement sensor 60 only measures the height of the edge portion 31, then the contour line is formed only at the edge portion 31 of the W2W wafer 30.

[0122] Next, according to an embodiment of the present invention, the edge region segmentation step (S23) is the process of segmenting the surface of the edge portion 31 of the W2W wafer 30 into multiple segmentation units 77. The segmentation units 77 are divided to cover the entire edge portion 31, and the shape of each segmentation unit 77 is preferably square. The size of the segmentation unit 77 is related to the accuracy of the focusing position control of the laser beams 41 and 51; excessive segmentation may lead to difficulties in control and longer processing time. Figure 6As shown, each of the positions corresponding to the positions inside a specific segmentation unit 77 has a different height value than the others.

[0123] Next, in the first patterning step (S24), the height distribution is confirmed according to the segmentation units 77 divided by the edge region segmentation step (S23), and the median in each segmentation unit 77 is mapped to a representative height. As previously described, Figure 7 The height of segmentation unit 77, marked with ①, has a constant distribution and varies, but is mapped to its median A, and the height of all regions within that segmentation unit 77 is replaced with A. Similarly, the height of segmentation unit 77, marked with ②, has a constant distribution and varies, but is mapped to its median B, and the height of all regions within that segmentation unit 77 is replaced with B. Using the same method, the height of segmentation unit 77, marked with ③, has a constant distribution and varies, but is mapped to its median C, and the height of all regions within that segmentation unit 77 is replaced with C.

[0124] Next, the second patterning step (S25) is a smoothing step that reduces the volatility of the high-level distribution, based on the result of the first patterning step (S24). For example, as... Figure 8 As shown, segmentation units 77 whose distance from the center of W2W wafer 30 to the center of segmentation unit 77 is within a certain range are marked as the same group. Similar to the first patterning step (S24), the median height within each group can be replaced with the height of all segmentation units 77 belonging to each group. Figure 8 As shown, at the center of W2W wafer 30, the dividing unit 77 with radius r1 is marked as group ①, and its height is replaced by its median. Additionally, at the center of W2W wafer 30, the dividing unit 77 with radius r2 is marked as group ②, and its height is replaced by its median.

[0125] Although the second patterning step (S25) according to an embodiment of the present invention maps the segmentation units 77 located at the same distance from the center of the W2W wafer 30 to the same height value, it can also be selectively patterned to divide by angles so that even at the same distance, they have different values. For example, the angles of the overall disk-shaped W2W wafer 30 can be divided at 90-degree intervals, and even the segmentation units 77 at the same distance can be mapped to different heights according to quadrants.

[0126] Next, in the laser focusing position correction step (S26) according to an embodiment of the present invention, based on the mapping height distribution of each segmentation unit 77 obtained from the second patterning step (S25), the focusing position of the first laser beam 41 emitted from the first laser head 40 and the focusing pattern of the second laser beam 51 emitted from the second laser head 50 are corrected. More specifically, the height information of the segmentation unit 77 ultimately mapped by the control unit 110 is stored in a separately set database (not shown). Once the processing position on the W2W wafer 30 is determined, the height information of the segmentation unit 77 corresponding to the position is read and correction is performed. The position of the first laser beam 41 is only corrected at the focusing start position, while the second laser beam 51 is in the center direction of the W2W wafer 30 during the rotation of the chuck 80. Figure 5 It moves along the -x axis and is repeatedly corrected.

[0127] This embodiment and the accompanying drawings are merely illustrative of a portion of the technical concept included in this invention. It is obvious to those skilled in the art that variations and specific embodiments that can be readily derived within the scope of the technical concept included in the specification and drawings of this invention are all included within the scope of the claims of this invention.

[0128] Therefore, the concept of the present invention should not be limited to the illustrated embodiments, but also includes the appended claims. All equivalent or modified versions of the claims fall within the scope of the present invention.

Claims

1. A wafer processing apparatus for trimming the edge portion of a wafer, characterized in that, The wafer processing apparatus includes: A first laser head forms a first modified surface at the edge along the height direction of the wafer; and The second laser head forms a second modified surface at the edge along the diameter direction of the wafer. When the edge portion is removed by external force, the first modified surface and the second modified surface act as a peeling interface.

2. The wafer processing apparatus according to claim 1, characterized in that, The first laser beam emitted from the first laser head and the second laser beam emitted from the second laser head penetrate the outer surface of the wafer to form the first modified surface and the second modified surface, respectively.

3. The wafer processing apparatus according to claim 2, characterized in that, The second laser head also includes a beam splitter for splitting the laser source. The second laser beam is a plurality of beams split by the beam splitter.

4. The wafer processing apparatus according to claim 1, characterized in that, The wafer processing apparatus further includes: A height measurement sensor measures the height of the outer surface of the wafer. The focusing position of the first laser head and the focusing pattern of the second laser head are corrected based on the height distribution of the outer surface measured by the height measurement sensor.

5. The wafer processing apparatus according to claim 4, characterized in that, The height measurement sensor measures the height of the outer surface of the edge portion. The calibration of the first laser head and the second laser head is performed only at the edge.

6. The wafer processing apparatus according to claim 4, characterized in that, The wafer processing apparatus further includes a first controller for controlling the first laser head and a second controller for controlling the second laser head. The first controller and the second controller are connected to the control unit that controls the entire wafer processing apparatus and the edge portion is trimmed by the correction.

7. The wafer processing apparatus according to claim 6, characterized in that, The first controller controls the movement distance of the first laser head and the second controller controls the movement distance of the second laser head to be within 10 micrometers.

8. The wafer processing apparatus according to claim 3, characterized in that, The spacing between the beams of the plurality of second laser beams split by the beam splitter is limited to the range of 3 micrometers to 30 micrometers.

9. The wafer processing apparatus according to claim 1, characterized in that, The first modified surface is formed by the aggregation of point-like first modified parts formed by the first laser head. The second modified surface is formed by the aggregation of point-like second modified portions formed by the second laser head. The first modified portion and the second modified portion include cracks caused by laser processing.

10. The wafer processing apparatus according to claim 6, characterized in that, During the preparation for startup of the first laser head and the second laser head, the control unit uses the height measurement sensor to measure the height of the outer surface of the wafer.

11. The wafer processing apparatus according to claim 6, characterized in that, The control unit performs a first patterning step, which generates a height contour image based on the height distribution of the outer surface of the wafer measured by the height measurement sensor, divides the surface of the edge into multiple segmentation unit shapes of a certain size, and maps them to have the same height value within the segmentation unit.

12. The wafer processing apparatus according to claim 11, characterized in that, In the first patterning step, the height value mapped to each segmentation unit is the median of the height measured by the height measurement sensor within the corresponding segmentation unit.

13. The wafer processing apparatus according to claim 12, characterized in that, The control unit performs a second patterning step after the first patterning step, the second patterning step mapping segmentation units that are within a certain range based on the distance of the segmentation unit from the center of the wafer to have the same height value.

14. The wafer processing apparatus according to claim 4, characterized in that, The wafer is a W2W wafer manufactured by hybrid bonding.

15. A wafer fabrication method utilizing a wafer fabrication apparatus, the wafer fabrication apparatus comprising: A first laser head forms a first modified surface at the edge of the wafer along the height direction of the wafer; The second laser head forms a second modified surface at the edge along the diameter direction of the wafer; A height measurement sensor for measuring the height of the outer surface of the wafer; and a control unit, characterized in that, The control unit controls the first laser head and the second laser head such that when the edge portion is removed by external force, the first modified surface and the second modified surface act as a peeling interface. The wafer fabrication method includes: a wafer outer surface height measurement step, wherein the height of the outer surface is measured using the height measurement sensor; and... The laser focusing position correction step corrects the focusing position of the first laser head and the focusing pattern of the second laser head based on the height distribution measured by the height measurement sensor.

16. The wafer fabrication method according to claim 15, characterized in that, Before performing the laser focusing position correction step and after completing the wafer outer surface height measurement step, the following steps are performed: The height image generation step generates a height contour image based on the height distribution of the outer surface of the wafer measured by the height measurement sensor. The edge region segmentation step divides the surface of the edge into multiple segmentation units of a certain size; as well as The first patterning step involves mapping within the segmented units to have the same height value.

17. The wafer fabrication method according to claim 16, characterized in that, In the first patterning step, the height value mapped to each segmentation unit is the median of the height measured by the height measurement sensor within the corresponding segmentation unit.

18. The wafer fabrication method according to claim 17, characterized in that, A second patterning step is performed after the first patterning step, which maps segmentation units that are within a certain range based on the distance of the segmentation unit from the center of the wafer to have the same height value.

19. The wafer fabrication method according to claim 15, characterized in that, The wafer is a W2W wafer manufactured by hybrid bonding.

20. A wafer processing apparatus for trimming the edge portion of a W2W wafer manufactured by hybrid bonding, characterized in that, The wafer processing apparatus includes: A first laser head forms a first modified surface along the height direction of the wafer at the edge. The second laser head has a beam splitter for a beam-splitting laser source and forms a second modified surface at the edge along the diameter direction of the wafer using multiple laser beams. A height measurement sensor measures the height of the outer surface of the wafer; The first driving unit drives the first laser head; The second driving unit drives the second laser head; A first controller controls the first drive unit; A second controller controls the second drive unit; and The control unit controls the entire wafer processing apparatus. The control unit controls the first controller and the second controller such that when the edge portion is removed by external force, the first modified surface and the second modified surface act as a peeling interface. Furthermore, the control unit corrects the focusing position of the first laser head and the focusing pattern of the second laser head based on the height distribution of the outer surface measured by the height measurement sensor. The wafer processing apparatus performs the following steps: The height image generation step generates a height contour image based on the height distribution measured by the height measurement sensor; The edge region segmentation step divides the surface of the edge into multiple segmentation units of a certain size; The first patterning step involves mapping the median height within each segmented unit to a height; and The second patterning step maps the segmentation units, which are within a certain range based on the distance of the segmentation unit from the center of the wafer, to have the same height value.

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