Local wafer thinning system and method thereof

Abstract

The invention discloses a local wafer thinning system and a method thereof. The method comprises the following steps: providing a wafer comprising a plurality of crystal grains; determining at least one feature of interest for each of the plurality of dies and determining at least one starting region to be thinned according to the at least one feature of interest, the at least one feature of interest being associated with at least one element formed on an upper surface of the wafer; capturing at least one image of each of the plurality of crystal grains; performing image identification on the at least one image to identify at least one feature of interest of each of the plurality of crystal grains; and performing local laser thinning processing on the lower surface of the wafer in the at least one to-be-thinned starting area of each of the plurality of crystal grains, so that the wafer is locally thinned.

Description

Technical Field

[0001] This invention relates to a system and method for local wafer thinning, and more particularly to a system and method for local wafer thinning using a laser process. Background Technology

[0002] Existing technologies typically employ grinding methods to thin the entire back side of a wafer. When the wafer thickness is reduced too much, especially when it is less than 100 μm, the wafer is prone to bending and warping. Particularly in fields such as Vertical Cavity Surface Emitting Lasers (VCSELs), numerous epitaxial layers form on the front side of the wafer, leading to significant stress accumulation. If the wafer is thinned too much, the warping becomes severe, making the wafer difficult to handle and subsequent processing extremely challenging. Furthermore, using existing grinding methods to thin the entire back side of a wafer typically results in a high breakage rate. For example, when thinning silicon carbide (SiC) wafers used in power devices, such as silicon carbide-metal-oxide-semiconductor field-effect transistors (SiC MOSFETs @ 1200V-6500V) with voltage ratings of 1200V to 6500V, the SiC wafers need to be thinned to a thickness of less than 150μm; however, the breakage rate is typically around 3% to 5%. As another example, when thinning SiC wafers used in radio frequency (RF) devices, sometimes the required thickness of the thinned SiC wafer is less than 100μm; however, the breakage rate will be higher than 5%. On the other hand, existing polishing methods are very expensive.

[0003] Another existing technology attempts to address the warpage problem caused by wafer thinning. This technology uses a smaller grinding wheel with a diameter smaller than the wafer's diameter to grind the back side of the wafer, thinning the central portion of the back side. Only the annular frame at the wafer edge remains un-thinned. While the annular frame at the wafer edge can reduce the degree of wafer warpage, when the central portion of the back side is thinned too much, the support stress in the central portion of the wafer may still be insufficient, or wafer warpage may still occur. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to provide a system and method for wafer thinning, especially for local thinning of wafers, so that the wafer does not warp after being thinned.

[0005] To address the aforementioned problems and achieve the desired effect, the present invention provides a method for local wafer thinning, comprising the following steps: Step A: providing a wafer, wherein the wafer includes a plurality of dies, each of the plurality of dies including at least one element formed on an upper surface of the wafer; Step B: determining at least one feature of interest for each of the plurality of dies, wherein the at least one feature of interest for each of the plurality of dies is respectively associated with at least one element of each of the plurality of dies; Step C: determining at least one thinning start region for each of the plurality of dies based on the at least one feature of interest for each of the plurality of dies; Step D: capturing at least one image of each of the plurality of dies by an image capturing device; Step E: performing image recognition on the at least one image by an image recognition element to identify the at least one feature of interest for each of the plurality of dies; and Step F: performing local laser thinning on a lower surface of the wafer by a laser device in the at least one thinning start region for each of the plurality of dies, such that the wafer is locally thinned in the at least one thinning start region for each of the plurality of dies.

[0006] Furthermore, the present invention provides a system for partial wafer thinning, comprising: a driving device, a carrier device, an image capturing device, a control integration device, and a laser device. The carrier device is disposed on the driving device. The carrier device is used to carry a wafer. The wafer includes a plurality of dies. Each of the plurality of dies includes at least one element formed on an upper surface of the wafer. The image capturing device includes an image capturing element. The driving device causes at least one of a relative displacement and a relative rotation between the image capturing element and the wafer. The image capturing element is used to capture at least one image of each of the plurality of dies. The control integration device is connected to the driving device, the carrier device, the image capturing device, and the laser device to control the driving device, the carrier device, the image capturing device, and the laser device. The control integration device is used to determine at least one feature of interest for each of the plurality of dies and, based on the at least one feature of interest for each of the plurality of dies, to determine at least one thinning start region for each of the plurality of dies. The at least one feature of interest for each of the plurality of dies is associated with at least one element of each of the plurality of dies. The control integration device includes an image recognition element. The image recognition element is used to perform image recognition on at least one image of each of a plurality of dies captured by an image capturing element to identify at least one feature of interest for each of the plurality of dies. A driving device causes at least one of a relative displacement and a relative rotation between a laser device and the wafer. The laser device is used to perform local laser thinning on a lower surface of the wafer in at least one thinning initiation region of each of the plurality of dies, such that the wafer is locally thinned in at least one thinning initiation region of each of the plurality of dies.

[0007] In practice, the method further includes the following step: determining at least one region of interest for each of the plurality of grains based on at least one feature of interest for each of the plurality of grains, wherein the at least one region of interest for each of the plurality of grains is within or identical to at least one thinning start region for each of the plurality of grains.

[0008] In practice, the control integration device is further configured to determine at least one region of interest for each of the plurality of grains based on at least one feature of interest for each of the plurality of grains, wherein the at least one region of interest for each of the plurality of grains is either within or identical to at least one thinning start region for each of the plurality of grains.

[0009] In practice, the step of determining at least one region of interest for each of the plurality of grains is performed after step B and before step F.

[0010] In practice, at least one region of interest for each of the plurality of grains is located within at least one thinning start region for each of the plurality of grains. After local laser thinning, at least one back groove is formed for each of the plurality of grains. The shape of one sidewall of the at least one back groove for each of the plurality of grains is stepped, tapered, or a combination of stepped and tapered.

[0011] In practice, at least one region of interest of each of the plurality of grains is identical to at least one thinning start region of each of the plurality of grains. After local laser thinning, at least one back groove of each of the plurality of grains is formed, and one side wall of the at least one back groove of each of the plurality of grains is upright.

[0012] In practice, after local laser thinning, at least one back groove is formed for each of a plurality of grains, and at least one region of interest for each of the plurality of grains defines a region occupied by a bottom surface of the at least one back groove for each of the plurality of grains.

[0013] In practice, after local laser thinning, the wafer has a desired thickness in at least one region of interest for each of the plurality of grains.

[0014] In practice, after local laser thinning, the wafer has a first desired thickness in one of at least one region of interest of each of the plurality of grains; and the wafer has a second desired thickness in the other of at least one region of interest of each of the plurality of grains, wherein the first desired thickness is less than, equal to or greater than the second desired thickness.

[0015] In practice, at least one feature of interest of each of the plurality of grains is located within or identical to at least one region of interest of each of the plurality of grains.

[0016] In practice, in each of the plurality of grains, at least one region of interest includes a first sub-region of interest and a second sub-region of interest; wherein in each of the plurality of grains, after local laser thinning, the wafer has a first desired thickness within the first sub-region of interest of the at least one region of interest; and the wafer has a second desired thickness within the second sub-region of interest of the at least one region of interest, wherein the first desired thickness is less than, equal to or greater than the second desired thickness.

[0017] In practice, the first required thickness is greater than 100nm.

[0018] In implementation, the plurality of grains has N grains, and the method further includes the following step: dividing M grains out of the N grains into at least two grain groups, wherein any two grain groups of the at least two grain groups respectively include P grains and Q grains out of the M grains, where N≥M≥4, M≥(P+Q)≥4, and N, M, P, and Q are positive integers, where P=Q or P≠Q; wherein, in each of the at least two grain groups, any grain is adjacent to at least one other grain; wherein, in step F, the laser device performs local laser treatment on the lower surface of the wafer in at least one thinning start region in each of the plurality of grains and in a boundary region between at least one thinning start region each of any two adjacent grains in each of the at least two grain groups. Thinning processing involves locally thinning the wafer in at least one thinning start region of each of a plurality of grains and in a boundary region between at least one thinning start region of each of any two adjacent grains in at least two grain groups, to form a non-separated back groove of each of the at least two grain groups, wherein the non-separated back groove of each of the at least two grain groups has an opening; a region occupied by the opening of the non-separated back groove of each of the at least two grain groups is defined by a merged region formed by merging the boundary regions between at least one thinning start region of each grain of each of the at least two grain groups and the at least one thinning start region of each of any two adjacent grains in each of the at least two grain groups.

[0019] In practice, the control integration device is further used to divide M of the N grains into at least two grain groups.

[0020] In practice, a required thickness of the wafer in the boundary region between at least one thinning start region of any two adjacent grains of at least two grain groups is equal to or not equal to a required thickness of the wafer in the at least one region of interest of the two adjacent grains.

[0021] In practice, each of the plurality of grains includes a plurality of sub-grains, and each of the plurality of sub-grains includes at least one element formed on the upper surface of the wafer.

[0022] In practice, at least one feature of interest of each of the plurality of grains is located within or identical to at least one thinning start region of each of the plurality of grains.

[0023] In practice, in each of the plurality of grains, at least one of the starting regions to be thinned is adjacent to another of the starting regions to be thinned; wherein in each of the plurality of grains, a gap between at least one of the starting regions to be thinned and another of the starting regions to be thinned is greater than or equal to 10 μm.

[0024] In practice, step C is performed after step B and before step F.

[0025] In practice, the wafer is opaque, and the upper surface of the wafer is located between the lower surface of the wafer and the image capturing device.

[0026] In practice, the wafer is transparent, and the image capturing device includes an image capturing element and a light source, wherein the upper surface of the wafer is located between the lower surface of the wafer and the light source, and the upper surface of the wafer is located between the lower surface of the wafer and the image capturing element, or the lower surface of the wafer is located between the upper surface of the wafer and the image capturing element.

[0027] In practice, the wafer is made of at least one material selected from the group consisting of: glass, silicon carbide, gallium nitride, gallium nitride on silicon carbide substrate, gallium oxide, silicon, gallium nitride on silicon substrate, gallium arsenide, sapphire, indium phosphide, gallium phosphide, aluminum nitride, zinc selenide, indium arsenide, silicon germanium, diamond, and gallium antimonide.

[0028] To further understand the present invention, preferred embodiments are described below, along with drawings and reference numerals, to explain in detail the specific composition of the present invention and the effects it achieves. Attached Figure Description

[0029] Figure 1 This is a cross-sectional schematic diagram of a specific embodiment of a partial wafer thinning system according to the present invention.

[0030] Figure 2 for Figure 1A schematic diagram of the upper surface of a wafer.

[0031] Figure 3 for Figure 2 A magnified view of region X, which shows a schematic diagram of the upper surface of a grain.

[0032] Figure 4 In order to be in Figure 3 A schematic diagram of a specific embodiment of a region of interest on the upper surface of a grain and a region to be thinned starting point.

[0033] Figure 5 In order to be in Figure 4 A schematic diagram of the region of interest on the lower surface of the grain and the starting region to be thinned.

[0034] Figure 6 To perform local thinning of the wafer before the local laser thinning process of the present invention, along... Figure 5 A schematic diagram of the cross section line A-A'.

[0035] Figure 7 To perform local thinning of the wafer before the local laser thinning process of the present invention, along... Figure 5 A schematic diagram of the cross section line B-B'.

[0036] Figure 8 To perform local thinning of the die in the starting region of the wafer after local laser thinning of the present invention, along... Figure 5 A schematic diagram of the cross section line A-A'.

[0037] Figure 9 To perform local thinning of the die in the starting region of the wafer after local laser thinning of the present invention, along... Figure 5 A schematic diagram of the cross section line B-B'.

[0038] Figure 10 To perform localized thinning of the grain in the starting region to be thinned during the localized laser thinning process of the present invention on the wafer, Figure 5 A three-dimensional schematic diagram of the lower surface of a wafer.

[0039] Figure 11 For the reason Figure 8 A cross-sectional diagram of the grains cut from the wafer.

[0040] Figure 12 In order to be in Figure 3 A schematic diagram of another specific embodiment of a region of interest on the lower surface of a grain and a region to be thinned starting point.

[0041] Figure 13To perform local thinning of the wafer before the local laser thinning process of the present invention, along... Figure 12 A schematic diagram of the cross-section line C-C'.

[0042] Figure 14 To perform local thinning of the die in the starting region of the wafer after local laser thinning of the present invention, along... Figure 12 A schematic diagram of the cross-section line C-C'.

[0043] Figure 15 This is a cross-sectional schematic diagram of another specific embodiment of a region of interest and a region to be thinned in a grain before the wafer is locally thinned by the local laser thinning process of the present invention.

[0044] Figure 16 To perform localized thinning of the grain in the starting region to be thinned during the localized laser thinning process of the present invention on the wafer, Figure 15 A cross-sectional schematic diagram of the grains.

[0045] Figure 17 This is a cross-sectional schematic diagram of another specific embodiment of two regions of interest and two starting regions to be thinned in a die before the wafer is locally thinned by the local laser thinning process of the present invention.

[0046] Figure 18 To perform localized thinning of the grain in the starting region to be thinned during the localized laser thinning process of the present invention on the wafer, Figure 17 A cross-sectional schematic diagram of the grains.

[0047] Figure 19 In order to be in Figure 3 A schematic diagram of another specific embodiment of a region of interest on the lower surface of a grain and a region to be thinned starting point.

[0048] Figure 20 To perform local thinning of the wafer before the local laser thinning process of the present invention, along... Figure 19 A schematic diagram of the cross-section line D-D'.

[0049] Figure 21 To perform local thinning of the die in the starting region of the wafer after local laser thinning of the present invention, along... Figure 19 A schematic diagram of the cross-section line D-D'.

[0050] Figure 22 To perform localized thinning of the grain in the starting region to be thinned during the localized laser thinning process of the present invention on the wafer, Figure 19 A three-dimensional schematic diagram of the lower surface of the wafer.

[0051] Figure 23 For the reason Figure 21 A cross-sectional diagram of the grains cut from the wafer.

[0052] Figure 24 To perform local thinning of the wafer in the starting region of the die after the local laser thinning process of this invention, the wafer moves along... Figure 22 A schematic diagram of the cross section line E-E'.

[0053] Figure 25 This is a cross-sectional schematic diagram of another specific embodiment of a region of interest and a region to be thinned in a grain before the wafer is locally thinned by the local laser thinning process of the present invention.

[0054] Figure 26 To perform localized thinning of the grain in the starting region to be thinned during the localized laser thinning process of the present invention on the wafer, Figure 25 A cross-sectional schematic diagram of the grains.

[0055] Figure 27 This is a cross-sectional schematic diagram of another specific embodiment of a region of interest and a region to be thinned in a grain before the wafer is locally thinned by the local laser thinning process of the present invention.

[0056] Figure 28 To perform localized thinning of the grain in the starting region to be thinned during the localized laser thinning process of the present invention on the wafer, Figure 27 A cross-sectional schematic diagram of the grains.

[0057] Figure 29 This is a cross-sectional schematic diagram of another specific embodiment of a partial wafer thinning system according to the present invention.

[0058] Figure 30 This is a cross-sectional schematic diagram of two grains after the wafer has been locally thinned by the local laser thinning process of the present invention.

[0059] Figure 31 This is a partially enlarged schematic diagram of another specific embodiment of a wafer prior to local thinning by the local laser thinning process of the present invention.

[0060] Figure 32 For use after the wafer has been locally thinned by the local laser thinning process of this invention, Figure 31 A schematic diagram of the lower surface of the wafer.

[0061] Figure 33 This is a partially enlarged schematic diagram of another specific embodiment of a wafer after it has been partially thinned by the local laser thinning process of the present invention.

[0062] Explanation of reference numerals in the attached figures: 1-System for partial wafer thinning; 2-Drive device; 20-Hollow central portion; 3-Image capturing device; 30-Image capturing element; 31-Lens; 32-Light source; 33-Protruding connection; 4-Laser device; 5-Carrier device; 50-Clamping element; 51-Hollow central portion; 6-Wafer; 60-Upper surface of wafer; 61-Grain / Separated independent grain (wafer); 61'-Grain; 611-First grain; 612-Second grain; 613-Third grain; 614-Fourth grain; 615-Fifth grain; 616-Sixth grain; 617-Seventh grain Grain; 618 - Eighth grain; 619 - Ninth grain; 62, 62' - Region of interest; 621 - First sub-region of interest; 622 - Second sub-region of interest; 623 - Third sub-region of interest; 624 - Fourth sub-region of interest; 625 - Fifth sub-region of interest; 63 - Lower surface of wafer; 64, 64' - Region to be thinned starting; 65, 65' - Dashed cutting line; 66 - Boundary region; 67 - Non-separated back groove; 68 - Grain group; 691 - First grain; 692 - Second grain; 693 - Third grain; 694 - Fourth grain; 695 - Fifth grain Grain; 696 - Sixth grain; 697 - Seventh grain; 698 - Eighth grain; 699 - Ninth grain; 7, 7' - Component; 70 - First source electrode; 71 - Second source electrode; 72 - Third source electrode; 73 - Gate electrode; 74 - Gate finger; 75, 75' - Back groove; 751 - First back groove; 752 - Second back groove; 753 - Third back groove; 754 - Fourth back groove; 755 - Fifth back groove; 76, 76' - Bottom surface; 761 - First bottom surface; 762 - Second bottom surface; 763 - Third bottom surface; 764 - Fourth bottom surface; 765 - Fifth bottom surface; 77 - Sidewall / Main sidewall; 77' - Sidewall; 770 - First sidewall; 771 - Second sidewall; 78, 78' - Opening; 8 - Control integration device; 80 - Image recognition element; 801 - Upper electrode; 81 - Lower electrode; 82 - Upper distributed Bragg reflector; 83 - Quantum well region; 84 - Lower distributed Bragg reflector; A—A', B—B', C—C', D—D', E—E' - Profile lines; D, D', D1, D2, D3, D4, D5 - Required thickness; T, T2 - Thickness; T1 - Sidewall thickness; X - Region. Detailed Implementation

[0063] Please see Figure 1 This is a cross-sectional schematic diagram of a specific embodiment of a partial wafer thinning system according to the present invention. The partial wafer thinning system 1 of the present invention includes a driving device 2, an image capturing device 3, a laser device 4, a carrier device 5, and a control integration device 8.

[0064] In this embodiment, the carrier device 5 includes a clamping element 50, wherein the carrier device 5 has a hollow central portion 51. The clamping element 50 surrounds the hollow central portion 51 of the carrier device 5. The clamping element 50 of the carrier device 5 is used to clamp a peripheral edge of a wafer 6, so that the wafer 6 can be carried by the carrier device 5. The carrier device 5 is disposed on the driving device 2. In this embodiment, the wafer 6 is carried by the carrier device 5 with its upper surface 60 facing downward (that is, the lower surface 63 of the wafer 6 facing upward), wherein the wafer 6 includes a plurality of dies 61. Please refer to Figure 2 , it is Figure 1 A schematic diagram of the upper surface of a wafer. Please also refer to... Figure 3 , it is Figure 2 A partially enlarged view of region X, illustrating a schematic diagram of the upper surface of a die. In this embodiment, each of the plurality of dies 61 includes only one element 7 (generally, each of the plurality of dies 61 may include at least one element 7, and / or some other elements, and / or an integrated circuit). In this embodiment, element 7 is a power element (e.g., a power metal-oxide-semiconductor field-effect transistor MOSFET). Element 7 includes a first source electrode 70, a second source electrode 71, a third source electrode 72, a gate electrode 73, and a gate finger 74, wherein the first source electrode 70, the second source electrode 71, the third source electrode 72, the gate electrode 73, and the gate finger 74 are formed on the upper surface 60 of wafer 6, wherein the gate finger 74 has a very fine shape compared to the shape of each of the three source electrodes 70, 71, 72. Element 7 may further include a drain electrode; however, in this embodiment, the drain electrode of element 7 has not been formed. Therefore, the drain electrode of element 7 is not shown in the figure.

[0065] In this embodiment, Figures 1-3The image shows an X-axis, a Y-axis, and a Z-axis, where the Y-axis is perpendicular to both the X-axis and Z-axis, and the X-axis is perpendicular to the Z-axis. In this embodiment, the driving device 2 includes a three-axis moving platform (including an X-axis moving platform, a Y-axis moving platform, and a Z-axis moving platform), wherein the wafer 6 carried by the carrier device 5 can be moved along any one of the X-axis, Y-axis, and Z-axis directions via the driving device 2. Therefore, the driving device 2 can generate a relative displacement between the image capturing device 3 and the wafer 6 carried by the carrier device 5 along any one of the X-axis, Y-axis, and Z-axis directions; and the driving device 2 can also generate a relative displacement between the laser device 4 and the wafer 6 carried by the carrier device 5 along any one of the X-axis, Y-axis, and Z-axis directions. In this embodiment, the drive device 2 has a hollow central portion 20, wherein the hollow central portion 20 of the drive device 2 corresponds to the hollow central portion 51 of the support device 5 and is located below the hollow central portion 51 of the support device 5.

[0066] In this embodiment, the image capturing device 3 includes an image capturing element 30 and a light source 32, wherein the image capturing element 30 has a lens 31. The light source 32 is a coaxial light source. The image capturing element 30 of the image capturing device 3 is used to capture images. The light source 32 is mounted on a protruding connecting portion 33 of the lens 31 for emitting light. One end of the lens 31 faces the upper surface 60 of the wafer 6, wherein the image capturing device 3 is disposed below the hollow central portion 20 of the driving device 2 (or a part of the image capturing device 3 (e.g., a part of the lens 31) is disposed within the hollow central portion 20 of the driving device 2), so that the light emitted by the light source 32 can pass through the lens 31, and then through the hollow central portion 20 of the driving device 2 and the hollow central portion 51 of the carrier device 5, to illuminate at least a portion of the upper surface 60 of the wafer 6 (e.g., at least one die 61), and so that the image capturing element 30 of the image capturing device 3 can capture the image of at least one die 61 (from the upper surface 60 of the wafer 6). In some other embodiments, the light emitted by the light source 32 can illuminate the entire upper surface 60 of the wafer 6, so that the image capturing element 30 of the image capturing device 3 can capture an image of each of the plurality of dies 61 (from the upper surface 60 of the wafer 6).

[0067] In this embodiment, the control integration device 8 is connected to the driving device 2, the carrier device 5, the image capturing element 30 of the image capturing device 3, the light source 32 of the image capturing device 3, and the laser device 4, wherein the control integration device 8 is connected to the carrier device 5 via the driving device 2. The control integration device 8 can control the carrier device 5 to clamp or release the peripheral edge of the wafer 6 via the clamping element 50 of the carrier device 5. The control integration device 8 can control the driving device 2 to drive movement, such as a relative displacement between the image capturing device 3 and the wafer 6 carried by the carrier device 5, and / or a relative displacement between the laser device 4 and the wafer 6 carried by the carrier device 5. The control integration device 8 can control the light source 32 of the image capturing device 3 to emit light to illuminate at least one die 61 or each of the plurality of dies 61. The control integration device 8 can control the image capturing element 30 of the image capturing device 3 to capture an image of at least one die 61 or an image of each of the plurality of dies 61. The control integration device 8 further includes an image recognition element 80, which can receive images captured by the image capturing element 30 of the image capturing device 3, and then perform image recognition on the images captured by the image capturing element 30 of the image capturing device 3. The control integration device 8 can also control the laser device 4 to perform localized laser thinning on the lower surface 63 of the wafer 6.

[0068] The present invention also provides a method for partial wafer thinning, comprising the following steps: Step A: providing a wafer 6 supported by a carrier device 5, wherein the wafer 6 includes a plurality of dies 61, each of the plurality of dies 61 including at least one element 7 formed on an upper surface 60 of the wafer 6; Step B: determining at least one feature of interest for each of the plurality of dies 61 (described in further detail below), wherein the at least one feature of interest for each of the plurality of dies 61 is respectively associated with at least one element 7 formed on the upper surface 60 of the plurality of dies 61; Step C: determining at least one thinning start region (described in further detail below) and at least one region of interest (described in further detail below) for each of the plurality of dies 61 based on the at least one feature of interest for each of the plurality of dies 61, wherein the at least one feature of interest for each of the plurality of dies 61 is respectively within the at least one thinning start region for each of the plurality of dies 61, or is completely identical to the at least one region of interest for each of the plurality of dies 61. At least one region of interest for each of the plurality of grains 61 is respectively (determined to) within at least one thinning start region for each of the plurality of grains 61 (but not identical to at least one thinning start region for each of the plurality of grains 61), or is identical to at least one thinning start region for each of the plurality of grains 61; Step D: At least one image of each of the plurality of grains 61 is captured by an image capturing device 3 (in this embodiment, at least one image of each of the plurality of grains 61 is captured from the upper surface 60 of the wafer 6); Step E: An image recognition element 80 performs image recognition on at least one image to identify at least one feature of interest for each of the plurality of dies 61; and step F: A laser device 4 performs local laser thinning on a lower surface 63 of the wafer 6 in at least one thinning start region for each of the plurality of dies 61 to locally thin the wafer 6 in at least one thinning start region for each of the plurality of dies 61, so that the wafer 6 has a desired thickness in at least one of the at least one region of interest for each of the plurality of dies 61.

[0069] In this invention, the desired thickness of wafer 6 is not a measured thickness of wafer 6. When a user performs local thinning on the lower surface 63 of wafer 6 within a thinning start area of ​​a die 61, the user desires that after local thinning, wafer 6 will have a specific thickness within the thinning start area of ​​die 61, where this specific thickness is the desired thickness. The user relies on experience to achieve the desired thickness of wafer 6 within the thinning start area of ​​die 61 after local thinning. For example, the user can select a suitable laser device 4 and, at a specific laser energy density, perform local thinning on the lower surface 63 of wafer 6 within the thinning start area of ​​die 61 for a specific time (or a specific number of laser pulses). After local thinning, the user can measure the thickness of wafer 6 within the thinning start area of ​​die 61. Users can change parameters, such as different laser devices 4, different wafers (made of different materials), different laser energy densities, or different durations (or different amounts of laser pulses), to compare the differences in results with different parameters. Users can rely on this experience to achieve the desired thickness of wafer 6 in the thinning start region of the die 61 after local thinning of wafer 6. After local thinning of the lower surface 63 of wafer 6 in at least one thinning start region of each of the plurality of dies 61, the user can measure the thickness of wafer 6 in at least one thinning start region of each of the plurality of dies 61. A measured thickness of wafer 6 in at least one thinning start region of each of the plurality of dies 61 is the result measured by the user. The difference between the measured thickness of wafer 6 in at least one thinning start region of each of the plurality of dies 61 and the desired thickness can be controlled to be very small (e.g., less than 2 μm).

[0070] Please see Figure 4 , its purpose is Figure 3 A schematic diagram of a specific embodiment of a region of interest on the upper surface of a grain and a region to be thinned starting point. Please also refer to... Figure 5 , its purpose is Figure 4 A schematic diagram of the region of interest and the starting region for thinning on the lower surface of the die. In this embodiment, wafer 6 is made of silicon carbide (SiC). Wafer 6 has not yet been diced into separate individual dies (wafers). Figures 2-5The dashed dicing lines 65 in the diagram represent the boundaries of each of the plurality of grains 61. After the wafer 6 has been locally thinned by the local laser thinning process of the present invention, and after all back-side processes (optionally) have been completed on a back side of the wafer 6 (e.g., a back-side metal process forming the drain electrode of the element 7), the wafer 6 can be diced along these dashed dicing lines 65 into separate individual grains (wafers). Dicing the wafer 6 into separate individual grains (wafers) can be achieved by blade cutting, laser stealth cutting, plasma cutting, scribing and dicing, or other methods. When dicing the wafer 6 into separate individual grains (wafers), a portion of the area adjacent to the dashed dicing lines 65 is lost. In this embodiment, in each of the plurality of grains 61, each of the three source electrodes 70, 71, 72 of the element 7 occupies a front-side area on the upper surface 60 of the wafer 6 (e.g., ...). Figure 3 (as shown); while in the three back surface regions of the lower surface 63 of wafer 6 (as shown) Figure 5 (As shown) These correspond to the three front-side regions of the three source electrodes 70, 71, and 72 on the upper surface 60 of wafer 6, respectively. In each of the plurality of dies 61, the three back-side regions on the lower surface 63 of wafer 6 are the three corresponding front-side regions of the three source electrodes 70, 71, and 72 of the element 7 on the upper surface 60 of wafer 6, mapped onto the lower surface 63 of wafer 6 along a direction from the upper surface 60 to the lower surface 63 of wafer 6 and perpendicular to the upper surface 60 of wafer 6 (a direction opposite to the Z-axis direction). Each of the three back-side regions on the lower surface 63 of wafer 6 has the same shape and the same area as each of the three corresponding front-side regions of the three source electrodes 70, 71, and 72 of the element 7 on the upper surface 60 of wafer 6. Wafer 6 has a uniform thickness T; therefore, if the drain electrode of element 7 (not yet formed; not shown in the figure) is formed directly on the lower surface 63 of wafer 6 (where wafer 6 has a uniform thickness T), then the on-resistance of element 7 is related to the shortest distance between the drain electrode of element 7 (not shown in the figure) and each of the three source electrodes 70, 71, 72 of element 7. That is, the on-resistance of element 7 is related to the uniform thickness T of wafer 6 within the three front-side regions of the three source electrodes 70, 71, 72 of element 7.

[0071] Since the on-resistance of element 7 is related to the thickness of wafer 6 within the three front regions of the three source electrodes 70, 71, 72 of element 7 (i.e., related to the shortest distance between each of the drain electrode (not shown) and the three source electrodes 70, 71, 72 of element 7), if the lower surface 63 of wafer 6 is subjected to the local laser thinning process of the present invention within the three back regions of a die 61 (corresponding to the three front regions of the three source electrodes 70, 71, 72 of element 7), the thickness of wafer 6 within the three front regions of the three source electrodes 70, 71, 72 of element 7 in die 61 will be locally thinned, and three back grooves of die 61 (not shown) will be formed on the back side of wafer 6. That is, the shortest distance between each of the three source electrodes 70, 71, 72 of the element 7 of the die 61 on the upper surface 60 of wafer 6 and the bottom surface of each of the three back grooves (not shown) of the die 61 is reduced. Then, after a drain electrode (not shown) of the element 7 of the die 61 is formed on the bottom surface of the three back grooves (not shown) of the die 61, the shortest distance between the drain electrode (not shown) of the element 7 of the die 61 and each of the three source electrodes 70, 71, 72 of the element 7 of the die 61 is shortened, thereby reducing the on-resistance of the element 7 of the die 61.

[0072] Therefore, in this embodiment, in each of the plurality of dies 61, the three source electrodes 70, 71, 72 of the element 7 of the die 61 formed on the upper surface 60 of the wafer 6 can be determined as a feature of interest for the die 61. In each of the plurality of dies 61, if the thickness of the wafer 6 within the three front regions (regions occupied by the feature of interest) of the three source electrodes 70, 71, 72 of the element 7 of the die 61 can be locally thinned by the laser device 4 on the lower surface 63 of the wafer 6 in the three corresponding back regions of the die 61, the on-resistance of the element 7 of the die 61 can be effectively reduced; at the same time, the heat dissipation effect of the element 7 of the die 61 can be effectively enhanced. In some embodiments, the criteria for determining the feature of interest of the die 61 can depend on the actual design of the element 7 of the die 61 and the requirements for the performance and characteristics of the element 7 of the die 61.

[0073] However, in this embodiment, the front area of ​​the first source electrode 70 is very close to the front area of ​​the second source electrode 71, and the front area of ​​the second source electrode 71 is also very close to the front area of ​​the third source electrode 72 (e.g., Figure 3As shown, a portion of the very fine gate finger 74 is located between the front region of the second source electrode 71 and the front region of the third source electrode 72; therefore, if the lower surface 63 of the wafer 6 is subjected to the local laser thinning process of the present invention in the three corresponding back regions of the die 61 via the laser device 4, two very thin sidewalls (not shown) will be formed on the back side of the wafer 6. One of the two very thin sidewalls (not shown) on the back side of the wafer 6 corresponds to a front region between the front region of the first source electrode 70 and the front region of the second source electrode 71; while the other of the two very thin sidewalls (not shown) on the back side of the wafer 6 corresponds to a front region between the front region of the second source electrode 71 and the front region of the third source electrode 72. These two very thin sidewalls (not shown) are redundant. Because these two very thin sidewalls (not shown in the figure) are so thin, they could be easily damaged (e.g., cracked) when processing wafer 6; the broken fragments could then contaminate wafer 6, other products, or equipment in the cleanroom. Removing these two very thin sidewalls (not shown in the figure) will not adversely affect the performance or characteristics of component 7. Furthermore, removing these two very thin sidewalls simplifies the process when performing the localized laser thinning of this invention.

[0074] Please see Figure 6 It is to perform local thinning along the wafer before the local laser thinning process of the present invention is carried out. Figure 5 A schematic diagram of the cross-section along section line A-A'. Please also refer to... Figure 7 It is to perform local thinning along the wafer before the local laser thinning process of the present invention is carried out. Figure 5A cross-sectional view along line B-B'. To avoid the formation of these two very thin sidewalls (not shown) after the local laser thinning process of the present invention, the local laser thinning process of the present invention requires processing not only the lower surface 63 of the wafer 6 in the three back face regions (corresponding to the three front face regions of the three source electrodes 70, 71, 72 of the element 7) of each of the plurality of grains 61, but also in one back face region of each of the plurality of grains 61 (corresponding to the front face region between the front face region of the first source electrode 70 and the front face region of the second source electrode 71 of the element 7 of each of the plurality of grains 61) and in another back face region of each of the plurality of grains 61 (corresponding to the front face region between the front face region of the second source electrode 71 and the front face region of the third source electrode 72 of the element 7 of each of the plurality of grains 61). Therefore, in this invention, a thinning start region for each of the plurality of grains 61 can be defined as a specific region for each of the plurality of grains 61, wherein when performing the local laser thinning process of this invention, the laser device 4 performs local laser thinning on the lower surface 63 of the wafer 6 within the specific region (thinning start region) of each of the plurality of grains 61. In this embodiment, a thinning start region 64 for each of the plurality of grains 61 is defined and shown as follows Figures 4-7 In each of the plurality of grains 61, the thinning start region 64 includes: (a) three back-side regions corresponding to the three front-side regions of the three source electrodes 70, 71, and 72 of the element 7; (b) a back-side region corresponding to the front-side region between the front-side region of the first source electrode 70 and the front-side region of the second source electrode 71 of the element 7; and (c) another back-side region corresponding to the front-side region between the front-side region of the second source electrode 71 and the front-side region of the third source electrode 72 of the element 7. After performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, the aforementioned two very thin sidewalls (not shown in the figure) will not appear.

[0075] In fact, in this embodiment, if the three front regions of the three source electrodes 70, 71, 72 of the element 7 of each of the plurality of grains 61, the front region between the front region of the first source electrode 70 and the front region of the second source electrode 71 of the element 7 in each of the plurality of grains 61, and the front region between the front region of the second source electrode 71 and the front region of the third source electrode 72 of the element 7 in each of the plurality of grains 61 are respectively merged into a non-separated front region of each of the plurality of grains 61, then the non-separated front region of each of the plurality of grains 61 is actually a minimum non-separated front region of each of the plurality of grains 61, and the minimum non-separated front region covers the features of interest of each of the plurality of grains 61 (a minimum non-separated front region covering the three front regions of the three source electrodes 70, 71, 72 of the element 7 of each of the plurality of grains 61). That is, in this embodiment, the thinning start region 64 of each of the plurality of grains 61 can be determined as the non-separated frontal region corresponding to each of the plurality of grains 61 respectively.

[0076] After performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, at least one back groove (not shown) of each of the plurality of grains 61 is formed on the back side of the wafer 6. Since the local laser thinning process of the present invention is performed by the laser device 4, the shape of one sidewall of the at least one back groove (not shown) of each of the plurality of grains 61 can be upright (perpendicular to the lower surface 63 of the wafer 6), stepped, tapered (not perpendicular to the lower surface 63 of the wafer 6), or a combination of stepped and tapered shapes. When the local laser thinning process is completed (or stopped), a bottom surface of the at least one back groove (not shown) of each of the plurality of grains 61 is formed, and the area occupied by the bottom surface of the at least one back groove (not shown) of each of the plurality of grains 61 is defined. The area occupied by the bottom surface of at least one back groove (not shown) of each of the plurality of grains 61 must be within (but not identical to) the thinning start area 64 of each of the plurality of grains 61, or identical to the thinning start area 64 of each of the plurality of grains 61. In this invention, a region of interest (not shown) of each of the plurality of grains 61 defines the area occupied by the bottom surface of at least one back groove (not shown) of each of the plurality of grains 61; that is, the region of interest (not shown) of each of the plurality of grains 61 defines the area when the local laser thinning process is completed (or stopped). In this embodiment, a region of interest 62 of each of the plurality of grains 61 is defined and shown as follows Figures 4-7 .

[0077] Please also refer to Figure 8 and Figure 9 They are respectively, after local thinning of the starting area of ​​the grain to be thinned by the local laser thinning process of the present invention on the wafer, along... Figure 5 The cross-sectional diagrams along section lines A-A' and B-B' are shown. Please also refer to... Figure 10 This refers to the process of locally thinning the starting area of ​​the grain in the wafer after the local laser thinning process of the present invention is performed. Figure 5 A three-dimensional schematic diagram of the lower surface of a wafer. In this embodiment, after performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, a back groove 75 of each of the plurality of grains 61 is formed on the back side of the wafer 6. The back groove 75 of each of the plurality of grains 61 has a bottom surface 76, a sidewall 77, and an opening 78 on the lower surface 63 of the wafer 6. In this embodiment, the region of interest 62 of each of the plurality of grains 61 (the region occupied by the bottom surface 76 of the back groove 75 of each of the plurality of grains 61) is respectively (determined to be) identical to the thinning start region 64 of each of the plurality of grains 61; therefore, the sidewall 77 of the back groove 75 of each of the plurality of grains 61 has an upright shape. After performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, the local laser thinning process is completed (or stopped) within the region of interest 62 of each of the plurality of grains 61, such that the wafer 6 has a desired thickness D within the region of interest 62 of each of the plurality of grains 61. Subsequently, a back metal (not shown) can be formed on the lower surface 63 of the wafer 6, the bottom surface 76 of the back groove 75 of each of the plurality of grains 61, and the sidewall 77 of the back groove 75, such that a drain electrode (not shown) of an element 7 of each of the plurality of grains 61 is formed at least on the bottom surface 76 of the back groove 75. The shortest distance between the drain electrode (not shown) of the element 7 of each of the plurality of grains 61 and each of the three source electrodes 70, 71, 72 of the element 7 is shortened; therefore, the on-resistance of the element 7 of each of the plurality of grains 61 can be effectively reduced; at the same time, the heat dissipation effect of the element 7 of each of the plurality of grains 61 can be effectively enhanced.

[0078] exist Figure 10 In this context, wafer 6 has the desired thickness D within the region of interest 62; while wafer 6 has a uniform thickness T (e.g., ...) in the region outside the thinning start region 64 of each of the plurality of grains 61. Figure 8 and Figure 9(As shown). Therefore, wafer 6 not only has a thickness T at a peripheral edge (near the dashed cut line 65) of each of the plurality of grains 61, but also in a front-side region of the gate electrode 73 of element 7, in a front-side region between the front-side region of the gate electrode 73 of element 7 and the front-side region of the first source electrode 70, and in a front-side region between the front-side region of the gate electrode 73 of element 7 and the front-side region of the third source electrode 72. This improves the overall mechanical strength of wafer 6.

[0079] Before the local laser thinning process of the present invention is performed on the lower surface 63 of the wafer 6 by the laser device 4 in the thinning start region of each of the plurality of grains 61, the region of interest and the thinning start region of each of the plurality of grains 61 must be determined. In this embodiment, the region of interest 62 and the thinning start region 64 of each of the plurality of grains 61 may be determined based on the features of interest of each of the plurality of grains 61 (e.g., the features of interest of each of the plurality of grains 61 are respectively related to the performance and characteristics of the element 7 of each of the plurality of grains 61), a shape of the sidewall 77 of the back groove 75 of each of the plurality of grains 61 (e.g., determining that the shape of the sidewall 77 of the back groove 75 is upright, stepped, tapered, or a combination of stepped and tapered), and other criteria (e.g., as mentioned above, in order to remove two very thin sidewalls).

[0080] exist Figures 1-10In an embodiment, the method for partial wafer thinning of the present invention includes the following steps: Step A: A wafer 6 is provided, supported by a carrier device 5, wherein an upper surface 60 of the wafer 6 faces downward (i.e., a lower surface 63 of the wafer 6 faces upward), the wafer 6 includes a plurality of dies 61, and an element 7 (including three source electrodes 70, 71, 72, a gate electrode 73, and a gate finger 74) of each of the plurality of dies 61 is formed on the upper surface 60 of the wafer 6, wherein the wafer 6 has a uniform thickness T; Step B: The three source electrodes 70, 71, 72 of the element 7 of each of the plurality of dies 61 on the upper surface 60 of the wafer 6 are respectively determined to be multiple Step C: Based on the features of interest of each of the plurality of grains 61, determine a thinning start region 64 and a region of interest 62 for each of the plurality of grains 61, wherein the thinning start region 64 for each of the plurality of grains 61 is determined to be a non-separated front region corresponding to each of the plurality of grains 61, wherein the non-separated front region for each of the plurality of grains 61 is (1) the three front regions of the three source electrodes 70, 71, 72 of the element 7 of each of the plurality of grains 61, (2) the front region between the first source electrode 70 and the second source electrode 7 of the element 7 in each of the plurality of grains 61) The front regions between the front regions of 1 and the front regions between the front regions of the second source electrode 71 and the third source electrode 72 of each of the plurality of grains 61, which are merged into a combined region, are each a minimum non-separated front region of each of the plurality of grains 61. The minimum non-separated front regions respectively cover the features of interest of each of the plurality of grains 61 (covering the minimum non-separated front regions of the three front regions of the three source electrodes 70, 71, and 72 of the element 7 of each of the plurality of grains 61), wherein the regions of interest 62 of each of the plurality of grains 61 are respectively (determined to be) identical to the regions of interest of the plurality of grains 61. Step D: At least one image of each of the plurality of grains 61 is captured by an image capturing element 30 of an image capturing device 3 (in this embodiment, at least one image of each of the plurality of grains 61 is captured from the upper surface 60 of the wafer 6); Step E: An image recognition element 80 of a control integration device 8 performs image recognition on at least one image of each of the plurality of grains 61 captured by the image capturing element 30 of the image capturing device 3 to identify the features of interest of each of the plurality of grains 61.And step F: A laser device 4 performs local laser thinning on the lower surface 63 of the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, so as to locally thin the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, so that the wafer 6 has a desired thickness D within the region of interest 62 of each of the plurality of grains 61.

[0081] Please see Figure 11 The reason for this Figure 8 A cross-sectional schematic diagram of the diced grains from the wafer. After the wafer 6 is locally thinned by the local laser thinning process of the present invention, a drain electrode (not shown) of element 7 of each of the plurality of diced grains 61 can then be formed at least on the bottom surface 76 of the back groove 75 of each of the plurality of diced grains 61. The wafer 6 can then be cut into separate individual diced grains (wafers) along these dashed cutting lines 65. Figure 11 One of the separate individual dies (wafers) 61 is shown. The sidewall 77 of the back recess 75 of the separate individual die (wafer) 61 has a sidewall thickness T1. Therefore, not only is the mechanical strength of the entire wafer 6 improved, but the mechanical strength of each separate individual die (wafer) 61 is also improved after multiple dies 61 are cut into separate individual dies (wafers) 61. In this embodiment, the element 7 is a power element. Before performing the die attach process, it is preferable to fill the back recess 75 of the separate individual die (wafer) 61 with a thermally conductive dielectric material to effectively enhance the heat dissipation of the element 7.

[0082] In some embodiments, if the front region of the first source electrode 70 of the element 7 is not very close to the front region of the second source electrode 71 of the element 7, and the front region of the second source electrode 71 of the element 7 is not very close to the front region of the third source electrode 72 of the element 7, then the thinning start region 64 of each of the plurality of grains 61 can be determined as the three back regions of the element 7 of each of the plurality of grains 61 (corresponding to the three front regions of the three source electrodes 70, 71, 72 of the element 7 of each of the plurality of grains 61).

[0083] Please see Figure 12 , its purpose is Figure 3 A schematic diagram of another specific embodiment of a region of interest on the lower surface of the grain and a region to be thinned starting point. Please also refer to... Figure 13 It is to perform local thinning along the wafer before the local laser thinning process of the present invention is carried out. Figure 12 A schematic diagram of the cross-section line C-C'. Figure 12 and Figure 13 The main structure of the specific embodiments and Figures 1 to 7The specific embodiments are structurally similar; however, the region of interest 62 of each of the plurality of grains 61 is respectively (determined) within (but not entirely identical to) the thinning start region 64 of each of the plurality of grains 61. The features of interest and the region of interest 62 of each of the plurality of grains 61 in this embodiment are similar to those in the specific embodiments. Figures 1 to 7 In the embodiments, each of the plurality of grains 61 has the same features of interest and region of interest 62; however, in this embodiment, the thinning start region 64 of each of the plurality of grains 61 is wider than... Figures 1 to 7 The embodiment refers to the thinning start region 64 of each of the plurality of grains 61. Please also refer to Figure 14 This refers to the process of locally thinning the wafer within the starting region of the grain to be thinned using the local laser thinning process of this invention, and then proceeding along... Figure 12 A cross-sectional view along the C-C' section line. After performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, a back groove 75 of each of the plurality of grains 61 is formed on the back side of the wafer 6. The back groove 75 of each of the plurality of grains 61 has a bottom surface 76, a sidewall 77, and an opening 78 on the lower surface 63 of the wafer 6. In this embodiment, the region of interest 62 of each of the plurality of grains 61 is respectively (determined to be) within the thinning start region 64 of each of the plurality of grains 61 (but not entirely the same as the thinning start region 64 of each of the plurality of grains 61); and the shape of the sidewall 77 of the back groove 75 of each of the plurality of grains 61 is (determined to be) tapered (the tapered back groove 75 sidewall 77 can be achieved by a combination of many stepped shapes). The opening 78 of the back groove 75 of each of the plurality of grains 61 occupies an area on the lower surface 63 of the wafer 6 that is identical to the thinning start area 64 of each of the plurality of grains 61. The region of interest 62 of each of the plurality of grains 61 is identical to the region occupied by the bottom surface 76 of the back groove 75 of each of the plurality of grains 61. The region occupied by the opening 78 of the back groove 75 of each of the plurality of grains 61 is wider than the region occupied by the bottom surface 76 of the back groove 75 of each of the plurality of grains 61; therefore, when a back metal (not shown) is formed on the lower surface 63 of the wafer 6, the bottom surface 76 of the back groove 75 of each of the plurality of grains 61, and the sidewall 77 of the back groove 75, this results in a back metal (not shown) of a more uniform thickness. In this embodiment, the wafer 6 has a desired thickness D within the region of interest 62 of each of the plurality of grains 61.

[0084] Please see Figure 15This is a cross-sectional schematic diagram of another specific embodiment of a region of interest and a region to be thinned starting area of ​​a die before the wafer is locally thinned by the local laser thinning process of the present invention. In this embodiment, a wafer 6 includes a plurality of dies 61, wherein each of the plurality of dies 61 includes only one element 7 (the element 7 is not as shown in the diagram). Figure 3 The power device shown has a feature of interest for each of a plurality of dies 61, which is defined as element 7 of each of the plurality of dies 61 on the upper surface 60 of wafer 6. The thinning start region 64 of each of the plurality of dies 61 is defined such that the feature of interest for each of the plurality of dies 61 is within (but not identical to) the thinning start region 64 of each of the plurality of dies 61; the thinning start region 64 of each of the plurality of dies 61 respectively covers an active region of element 7 of each of the plurality of dies 61 on the upper surface 60 of wafer 6. The region of interest 62 of each of the plurality of dies 61 is defined as being within (but not identical to) the thinning start region 64 of each of the plurality of dies 61, and the region of interest 62 of each of the plurality of dies 61 is defined as being identical to the feature of interest of each of the plurality of dies 61. Please also refer to... Figure 16 This refers to the process of locally thinning the starting area of ​​the grain in the wafer after the local laser thinning process of the present invention is performed. Figure 15A cross-sectional schematic diagram of the grains. After performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, a back groove 75 of each of the plurality of grains 61 is formed on the back side of the wafer 6. The back groove 75 of each of the plurality of grains 61 has a bottom surface 76, a sidewall 77, and an opening 78 on the lower surface 63 of the wafer 6. In this embodiment, the region of interest 62 of each of the plurality of grains 61 is respectively (determined to be) within the thinning start region 64 of each of the plurality of grains 61 (but not entirely the same as the thinning start region 64 of each of the plurality of grains 61), and the sidewall 77 of the back groove 75 of each of the plurality of grains 61 has a stepped shape. The area occupied by the opening 78 of the back groove 75 of each of the plurality of grains 61 on the lower surface 63 of the wafer 6 is entirely the same as the thinning start region 64 of each of the plurality of grains 61. Each of the plurality of dies 61 has a region of interest 62 that is contiguous with a region occupied by the bottom surface 76 of the back recess 75 of each of the plurality of dies 61. The region occupied by the opening 78 of the back recess 75 of each of the plurality of dies 61 is wider than the region occupied by the bottom surface 76 of the back recess 75 of each of the plurality of dies 61. The sidewalls 77 (stepped sidewalls) of the back recess 75 of each of the plurality of dies 61 can have different shape designs (e.g., two-step, three-step, or more-step, each step having a different height or a uniform height). The shape design of the sidewalls 77 (stepped sidewalls) of the back recess 75 of each of the plurality of dies 61 can be designed according to the performance or characteristics of the component 7, or other criteria. In this embodiment, the wafer 6 has a desired thickness D within the region of interest 62 of each of the plurality of dies 61.

[0085] Please see Figure 17 This is a cross-sectional schematic diagram of two regions of interest and two thinning start regions of a die before the wafer is locally thinned by the local laser thinning process of the present invention. In this embodiment, a wafer 6 includes a plurality of dies 61, each of the plurality of dies 61 including an element 7 and an element 7', wherein the element 7 and the element 7' are not as shown in the diagram. Figure 3The power device shown has two features of interest for each of a plurality of dies 61, wherein a first feature of interest for each of the plurality of dies 61 is determined as element 7 of each of the plurality of dies 61; and a second feature of interest for each of the plurality of dies 61 is determined as element 7' of each of the plurality of dies 61; wherein a thinning start region 64 for each of the plurality of dies 61 is determined such that the first feature of interest for each of the plurality of dies 61 is within (but not identical to) the thinning start region 64 of each of the plurality of dies 61; the thinning start region 64 of each of the plurality of dies 61 respectively covers an active region of element 7 of each of the plurality of dies 61 on the upper surface 60 of wafer 6; and a thinning start region 64' for each of the plurality of dies 61 is determined to be identical to the first feature of ... The second feature of interest for each of the plurality of grains 61 (the thinning start region 64' of each of the plurality of grains 61 respectively covers an active region of element 7' of each of the plurality of grains 61 on the upper surface 60 of the wafer 6); wherein a region of interest 62 of each of the plurality of grains 61 is respectively (determined to be) within the thinning start region 64 of each of the plurality of grains 61 (but not identical to the thinning start region 64 of each of the plurality of grains 61); and a region of interest 62' of each of the plurality of grains 61 is respectively (determined to be) identical to the thinning start region 64' of each of the plurality of grains 61; wherein a region of interest 62 of each of the plurality of grains 61 is respectively (determined to be) identical to the first feature of interest of each of the plurality of grains 61; and a region of interest 62' of each of the plurality of grains 61 is respectively (determined to be) identical to the second feature of interest of each of the plurality of grains 61. In this embodiment, in each of the plurality of grains 61, there is a gap between the thinning start region 64 and the thinning start region 64'; wherein the gap between the first feature of interest (element 7) and the second feature of interest (element 7') is greater than the gap between the thinning start region 64 and the thinning start region 64'.In this embodiment, in each of the plurality of grains 61, the gap between the thinning start region 64 and the thinning start region 64' is greater than or equal to a gap threshold; therefore, (1) two separate thinning start regions (thinning start region 64 and thinning start region 64' in this embodiment) can be determined, wherein these two separate thinning start regions (thinning start region 64 and thinning start region 64' in this embodiment) respectively cover the first feature of interest (element 7) and the second feature of interest (element 7'), or (2) a non-separate thinning start region can be determined (not shown in this embodiment), wherein this non-separate thinning start region covers the first feature of interest (element 7) and the second feature of interest (element 7'); for example, the non-separate thinning start region can be determined as a merged region formed by merging the thinning start region 64 and the thinning start region 64'. Please also refer to [the literature / reference]. Figure 18 This refers to the process of locally thinning the starting area of ​​the grain in the wafer after the local laser thinning process of the present invention is performed. Figure 17A cross-sectional schematic diagram of the grains. After performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 within the thinning start region 64 and the thinning start region 64' of each of the plurality of grains 61, a back groove 75 of the element 7 of each of the plurality of grains 61 and a back groove 75' of the element 7' are formed on the back side of the wafer 6. The back groove 75 of the element 7 of each of the plurality of grains 61 has a bottom surface 76, a side wall 77, and an opening 78 on the lower surface 63 of the wafer 6. The back groove 75' of the element 7' of each of the plurality of grains 61 has a bottom surface 76', a side wall 77', and an opening 78' on the lower surface 63 of the wafer 6. In this embodiment, the region of interest 62 of each of the plurality of dies 61 is respectively (determined to be) within (but not identical to) the thinning start region 64 of each of the plurality of dies 61, and the sidewall 77 of the back recess 75 of the element 7 of each of the plurality of dies 61 is (determined to be) tapered (the tapered sidewall 77 of the back recess 75 can be achieved by a combination of many steps). The area occupied by the opening 78 of the back recess 75 of the element 7 of each of the plurality of dies 61 on the lower surface 63 of the wafer 6 is identical to the thinning start region 64 of each of the plurality of dies 61. The region of interest 62 of each of the plurality of dies 61 is identical to the area occupied by the bottom surface 76 of the back recess 75 of the element 7 of each of the plurality of dies 61. The area occupied by the opening 78 of the back groove 75 of the element 7 of each of the plurality of dies 61 is wider than the area occupied by the bottom surface 76 of the back groove 75 of the element 7 of each of the plurality of dies 61; therefore, when a back metal (not shown) is formed on the lower surface 63 of the wafer 6, the bottom surface 76 of the back groove 75 of the element 7 of each of the plurality of dies 61, and the sidewall 77 of the back groove 75, this results in a back metal of more uniform thickness (not shown). The region of interest 62' of each of the plurality of dies 61 is respectively (determined) to be identical to the thinning start region 64' of each of the plurality of dies 61; therefore, the sidewall 77' of the back groove 75' of the element 7' of each of the plurality of dies 61 is upright. The area occupied by the opening 78' of the back groove 75' of the element 7' of each of the plurality of dies 61 on the lower surface 63 of the wafer 6 is identical to the thinning start region 64' of each of the plurality of dies 61. The region of interest 62' of each of the plurality of grains 61 is identical to the region occupied by the bottom surface 76' of the back recess 75' of the element 7' of each of the plurality of grains 61. The opening 78' of the back recess 75' of the element 7' of each of the plurality of grains 61 and the bottom surface 76' of the back recess 75' of the element 7' of each of the plurality of grains 61 have identical shapes and identical areas.In this embodiment, wafer 6 has a desired thickness D in the region of interest 62 of each of the plurality of grains 61; and wafer 6 has a desired thickness D' in the region of interest 62' of each of the plurality of grains 61, wherein the desired thickness D is not equal to the desired thickness D' (in this embodiment, the desired thickness D' is greater than the desired thickness D).

[0086] In some embodiments, each of the plurality of grains 61 has a plurality of features of interest. For example, in each of the plurality of grains 61, if a gap between any two separate features of interest of grain 61 is less than a gap threshold, then a non-separated thinning start region 64 of grain 61 will be determined, wherein the non-separated thinning start region 64 of grain 61 covers the two separate features of interest of grain 61; and if a gap between two separate features of interest of grain 61 is greater than or equal to a gap threshold, then (1) a non-separated thinning start region 64 of grain 61 can be determined, wherein the non-separated thinning start region 64 of grain 61 covers the two separate features of interest of grain 61, or (2) two separate thinning start regions of grain 61 can be determined separately, wherein the two separate thinning start regions of grain 61 respectively cover the two separate features of interest of grain 61, and a gap between the two separate thinning start regions of grain 61 must also be greater than or equal to a gap threshold. Therefore, the gap threshold is a minimum gap between two separate thinning initiation regions of grain 61. In some embodiments, the gap threshold is greater than or equal to 120 μm and less than or equal to 150 μm. In other embodiments, the gap threshold is greater than or equal to 100 μm and less than or equal to 120 μm. In other embodiments, the gap threshold is greater than or equal to 80 μm and less than or equal to 100 μm. In other embodiments, the gap threshold is greater than or equal to 50 μm and less than or equal to 80 μm. In other embodiments, the gap threshold is greater than or equal to 20 μm and less than or equal to 50 μm. In other embodiments, the gap threshold is greater than or equal to 15 μm and less than or equal to 20 μm. In other embodiments, the gap threshold is greater than or equal to 10 μm and less than or equal to 15 μm.

[0087] Please see Figure 19 , its purpose is Figure 3 A schematic diagram of another specific embodiment of a region of interest on the lower surface of the grain and a region to be thinned starting point. Please also refer to... Figure 20 It is to perform local thinning along the wafer before the local laser thinning process of the present invention is carried out. Figure 19 A schematic diagram of the cross-section line D-D'. Figure 19 and Figure 20 The main structure of the specific embodiments and Figures 1 to 7The specific embodiments are generally similar in structure; however, the features of interest for each of the plurality of grains 61 include (determined to include) three source electrodes 70, 71, 72, a gate electrode 73, and a gate finger 74 of the element 7 of each of the plurality of grains 61 respectively formed on the upper surface 60 of the wafer 6 (that is, in each of the plurality of grains 61, the features of interest include (determined to include) the element 7 formed on the upper surface 60 of the wafer 6); the thinning start region 64 of each of the plurality of grains 61 is determined respectively, such that each of the plurality of grains 61 The features of interest of each of the plurality of grains 61 are respectively within the thinning start region 64 of each of the plurality of grains 61 (but not entirely identical to the thinning start region 64 of each of the plurality of grains 61; the thinning start region 64 of each of the plurality of grains 61 respectively covers the three source electrodes 70, 71, 72, gate electrode 73 and gate finger 74 of the element 7 of each of the plurality of grains 61 on the upper surface 60 of the wafer 6); and the region of interest 62 of each of the plurality of grains 61 is respectively (determined to be) identical to the thinning start region 64 of each of the plurality of grains 61. That is, in this embodiment, an active region of the element 7 of each of the plurality of grains 61 is respectively within the thinning start region 64 of each of the plurality of grains 61 (but not entirely identical to the thinning start region 64 of each of the plurality of grains 61) and is respectively within the region of interest 62 of each of the plurality of grains 61 (but not entirely identical to the region of interest 62 of each of the plurality of grains 61). Please also refer to Figure 21 This refers to the process of locally thinning the wafer within the starting region of the grain to be thinned using the local laser thinning process of this invention, and then proceeding along... Figure 19 A schematic diagram of the cross-section along the D-D' section line. Please also refer to... Figure 22 This refers to the process of locally thinning the starting area of ​​the grain in the wafer after the local laser thinning process of the present invention is performed. Figure 19A three-dimensional schematic diagram of the lower surface of a wafer. After performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, a back groove 75 of each of the plurality of grains 61 is formed on the back side of the wafer 6. The back groove 75 of each of the plurality of grains 61 has a bottom surface 76, a sidewall 77, and an opening 78 on the lower surface 63 of the wafer 6. In this embodiment, the region of interest 62 of each of the plurality of grains 61 is (determined) identical to the thinning start region 64 of each of the plurality of grains 61; therefore, the sidewall 77 of the back groove 75 of each of the plurality of grains 61 has an upright shape. The area occupied by the opening 78 of the back groove 75 of each of the plurality of grains 61 on the lower surface 63 of the wafer 6 is identical to the thinning start region 64 of each of the plurality of grains 61. Each of the plurality of dies 61 has a region of interest 62 that is identical to a region occupied by the bottom surface 76 of the back recess 75 of each of the plurality of dies 61. The opening 78 of the back recess 75 of each of the plurality of dies 61 and the bottom surface 76 of the back recess 75 of each of the plurality of dies 61 have identical shapes and identical areas. In this embodiment, the wafer 6 has a desired thickness D within the region of interest 62 of each of the plurality of dies 61.

[0088] exist Figure 21 In one embodiment, after the wafer 6 is locally thinned by the local laser thinning process of the present invention, a drain electrode (not shown) of an element 7 of each of the plurality of grains 61 may be formed at least on the bottom surface 76 of the back groove 75 of each of the plurality of grains 61. The wafer 6 may then be diced along these dashed dicing lines 65 into separate individual grains (wafers), wherein... Figure 21 The main structure of each of the separate independent grains (wafers) 61 in the embodiment is similar to Figure 11 The specific embodiments are generally similar in structure; however, the thickness of one sidewall of sidewall 77 is slightly thinner than that of other sidewalls. Figure 11 The sidewall thickness T1 of the sidewall 77 in the embodiment. After the plurality of grains 61 are cut into separate individual grains (wafers) 61, the mechanical strength of each of the separate individual grains (wafers) 61 can also be improved.

[0089] Please see Figure 23 The reason for this Figure 21 A cross-sectional diagram of the grains cut from a wafer. Figure 21In one embodiment, after the wafer 6 is locally thinned by the local laser thinning process of the present invention, a drain electrode (not shown) of an element 7 of each of the plurality of grains 61 may be formed at least on the bottom surface 76 of the back groove 75 of each of the plurality of grains 61. The wafer 6 may then be cut into separate individual grains (wafers) along the sidewall 77 of the back groove 75 of each of the plurality of grains 61 (rather than along these dashed cut lines 65). Figure 23 One of the separated, independent grains (wafers) 61 is shown. Figure 23 In the embodiments, the structure of the separate, independent grains (wafers) 61 does not have a back groove 75 (sidewalls 77 without a back groove 75). Thermal dielectric material can be directly coated on the bottom surface 76 to more effectively enhance the heat dissipation of the component 7.

[0090] In some embodiments, the system 1 for local wafer thinning of the present invention further includes a distance measuring device (not shown) disposed on the lower surface 63 of the wafer 6 (e.g., adjacent to the laser device 4). Before the local laser thinning of the lower surface 63 of the wafer 6 by the laser device 4 within a thinning initiation region 64 of each of the plurality of dies 61 is performed according to the present invention, the distance measuring device is moved to a measuring position on the lower surface 63 of the wafer 6 (e.g., the distance measuring device is moved to a point on the lower surface 63 of the wafer 6, wherein the point is within a thinning initiation region 64 of a die 61). The distance measuring device then measures an initial distance between the distance measuring device and the point on the lower surface 63 of the wafer 6. The distance measuring device is then removed. After performing the local laser thinning process of the present invention on the lower surface 63 of wafer 6 within the thinning start region 64 of each of the plurality of dies 61, the distance measuring device is moved to the measuring position or another measuring position (above another point within a thinning start region 64 of another die 61), and then the distance measuring device measures a final distance between the distance measuring device and a bottom surface 76 of a back groove 75 of die 61 (or a bottom surface 76 of a back groove 75 of another die 61). Since wafer 6 originally has a uniform thickness T; therefore, a measured thickness of wafer 6 can be calculated as follows:

[0091] Measured thickness = Uniform thickness T + Initial distance - Final distance.

[0092] The difference X between the measured thickness of the wafer 6 within the thinning initiation region 64 of the grain 61 and the desired thickness can be controlled to be very small (e.g., less than 2 μm). In some embodiments, the difference X is less than 6 μm. In some embodiments, the difference X is less than 4 μm. In some embodiments, the difference X is less than 2 μm.

[0093] In some embodiments, the system 1 for local wafer thinning of the present invention further includes a distance measuring device (not shown) disposed on the lower surface 63 of the wafer 6 (e.g., adjacent to the laser device 4). Before the local laser thinning of the lower surface 63 of the wafer 6 by the laser device 4 within a thinning start region 64 of each of the plurality of dies 61 is performed according to the present invention, the distance measuring device is moved to a measuring position on the lower surface 63 of the wafer 6 (e.g., the distance measuring device is moved to a point on the lower surface 63 of the wafer 6, wherein the point is within a thinning start region 64 of a die 61). The distance measuring device then measures an initial distance between the distance measuring device and the point on the lower surface 63 of the wafer 6. The distance measuring device is then removed. After the local laser thinning of the lower surface 63 of the wafer 6 by the present invention is performed within a thinning start region 64 of each of the plurality of dies 61, the distance measuring device is moved to a plurality of final measuring positions. Each final measurement position is located on a thinning start region 64 of a grain 61 (multiple final measurement positions correspond to the thinning start region 64 of each of the multiple grains 61); that is, after the local laser thinning process of the present invention, each final measurement position is located on a bottom surface 76 of a back groove 75 of a grain 61. Then, the distance measuring device measures multiple final distances between the distance measuring device and the bottom surface 76 of the back groove 75 of each of the multiple grains 61. Assume there are N grains 61 (1 th Grain 61, 2 nd Grain 61, ..., N th Grain 61) and N final distances (1) were measured. th Final distance, 2 nd Final distance, ..., N th Final distance), then N measured thicknesses (1 th Measure thickness, 2 nd Measuring thickness, ..., N th The thickness (measured) can be calculated. Since wafer 6 originally had a uniform thickness T; therefore, for the i-th (i... th )Cell 61, the i-th (i)th of wafer 6 th The thickness can be calculated as follows:

[0094] i th Measured thickness = Uniform thickness T + Starting distance - i th The final distance, where i = 1…N.

[0095] For the i-th grain 61, where i = 1…N, the i-th measured thickness of the wafer 6 within the thinning start region 64 of the i-th grain 61 and the required thickness are the i-th (i…N) ... thThe difference X can be controlled to be very small (e.g., less than 2 μm). N measured thicknesses (1) of wafer 6 th Measure thickness, 2 nd Measuring thickness, ..., N th The variation in the measured thickness can also be controlled to be very small (e.g., less than 2 μm). In some embodiments, the variation of the N measured thicknesses is less than 6 μm. In some embodiments, the variation of the N measured thicknesses is less than 4 μm. In some embodiments, the variation of the N measured thicknesses is less than 2 μm.

[0096] Please also refer to Figure 24 This refers to the process where, after the wafer undergoes localized thinning of the starting region of the grain in the localized laser thinning process of this invention, the wafer moves along... Figure 22 A schematic diagram of the cross-section along the E-E' section line. Figure 24 In this embodiment, the plurality of grains 61 include at least a first grain 611, a second grain 612, a third grain 613, a fourth grain 614, and a fifth grain 615. The first grain 611 has a first backside groove 751; the second grain 612 has a second backside groove 752; the third grain 613 has a third backside groove 753; the fourth grain 614 has a fourth backside groove 754; and the fifth grain 615 has a fifth backside groove 755. The first grain 611 has a desired thickness D1; ​​the second grain 612 has a desired thickness D2; the third grain 613 has a desired thickness D3; the fourth grain 614 has a desired thickness D4; and the fifth grain 615 has a desired thickness D5; wherein, in this embodiment, the desired thickness D1 = desired thickness D2 = desired thickness D3 = desired thickness D4 = desired thickness D5 = desired thickness D.

[0097] In some embodiments, the required thicknesses D1, D2, D3, D4, and D5 may be completely different. In other embodiments, some of the required thicknesses D1, D2, D3, D4, and D5 may be the same, while others may be different (e.g., required thickness D1 = D2, required thickness D3 = D4, or required thicknesses D1, D3, and D5 may be completely different).

[0098] exist Figure 24In the embodiments, in any two adjacent grains 61 (e.g., the first grain 611 and the second grain 612 are adjacent), the first grain 611 has a unique thinning start region 64 (not shown in the figure), which defines a region occupied by an opening of a first back groove 751 of the first grain 611; the second grain 612 has a unique thinning start region 64 (not shown in the figure), which defines a region occupied by an opening of a second back groove 752 of the second grain 612. The opening of the first back groove 751 of the first grain 611 is adjacent to the opening of the second back groove 752 of the second grain 612; that is, the thinning start region 64 (not shown in the figure) of the first grain 611 is adjacent to the thinning start region 64 (not shown in the figure) of the second grain 612. Therefore, the gap between the opening of the first back groove 751 of the first grain 611 and the opening of the second back groove 752 of the second grain 612 is a gap between the thinning start region 64 (not shown in the figure) of the first grain 611 and the thinning start region 64 (not shown in the figure) of the second grain 612. In any two adjacent grains 61, there is a gap between an opening of a back groove of one of the two adjacent grains 61 and an opening of a back groove of the other of the two adjacent grains 61; in some embodiments, the gap is greater than 100 μm; in other embodiments, the gap is greater than 120 μm; in other embodiments, the gap is greater than 150 μm; in other embodiments, the gap is greater than 170 μm; in other embodiments, the gap is greater than 200 μm; in other embodiments, the gap is greater than 250 μm.

[0099] Please see Figure 25This is a cross-sectional schematic diagram of another specific embodiment of a region of interest and a region to be thinned starting area of ​​a die before the wafer is locally thinned by the local laser thinning process of the present invention. In this embodiment, a wafer 6 includes a plurality of dies 61, wherein each of the plurality of dies 61 includes only one element 7, and the element 7 of each of the plurality of dies 61 is a vertical cavity surface-emitting laser (VCSEL). Emitting Laser), wherein the features of interest of each of the plurality of dies 61 are respectively determined as element 7 of each of the plurality of dies 61 on the upper surface 60 of the wafer 6, wherein the thinning start region 64 of each of the plurality of dies 61 is respectively determined such that the features of interest of each of the plurality of dies 61 are respectively within (but not identical to) the thinning start region 64 of each of the plurality of dies 61; the thinning start region 64 of each of the plurality of dies 61 respectively covers an active region of element 7 (VCSEL) of each of the plurality of dies 61 on the upper surface 60 of the wafer 6, wherein the regions of interest 62 of each of the plurality of dies 61 are respectively (determined to be) identical to the thinning start region 64 of each of the plurality of dies 61. In this embodiment, in each of the plurality of dies 61, element 7 includes an upper electrode 801, a lower electrode 81, and an upper distributed Bragg reflector (DBR). The wafer 6 comprises an upper diffused Bragg reflector 82, a quantum well region 83, and a lower diffused Bragg reflector 84, wherein the lower diffused Bragg reflector 84 is formed on the upper surface 60 of the wafer 6, the quantum well region 83 is formed on the lower diffused Bragg reflector 84, the upper diffused Bragg reflector 82 is formed on the quantum well region 83, the upper electrode 801 is formed on the upper diffused Bragg reflector 82, and the lower electrode 81 is formed on the upper surface 60 of the wafer 6; wherein the upper diffused Bragg reflector 82 includes multiple upper layers; the quantum well region 83 includes multiple middle layers; and the lower diffused Bragg reflector 84 includes multiple... The lower layer includes an upper distributed Bragg reflector 82, a quantum well region 83, and a lower distributed Bragg reflector 84, in which the element 7 (VCSEL) is not located outside the thinning start region 64 (outside the region of interest 62). The feature of interest (element 7 (VCSEL)) of each of the plurality of grains 61 is located within the thinning start region 64 of each of the plurality of grains 61 (but not identical to the thinning start region 64 of each of the plurality of grains 61) and within the region of interest 62 of each of the plurality of grains 61 (but not identical to the region of interest 62 of each of the plurality of grains 61).After so many layers (including multiple upper layers of the upper distributed Bragg reflector 82, multiple middle layers of the quantum well region 83, and multiple lower layers of the lower distributed Bragg reflector 84) are formed on the upper surface 60 of wafer 6, wafer 6 is subjected to enormous stress.

[0100] If a conventional wafer thinning process (e.g., mechanical polishing or chemical mechanical planarization) is performed on the lower surface 63 of wafer 6, the wafer 6 will become thinner after the thinning process (overall thinning). Because the wafer 6 is thinner, it becomes difficult for the wafer 6 to balance the enormous stress caused by the many layers formed on the upper surface 60 of the wafer 6. Therefore, the warping of the wafer 6 becomes severe, and may even lead to edge cracking. Furthermore, when the diameter of the wafer 6 is less than 3 inches, the stress-induced warping of the wafer 6 may be less noticeable, while when the diameter of the wafer 6 is greater than or equal to 4 inches, 6 inches, 8 inches, or larger, the stress-induced warping of the wafer 6 becomes very significant.

[0101] exist Figure 25 In the embodiments, the features of interest of each of the plurality of dies 61 respectively include (determined to include) the element 7 of each of the plurality of dies 61; the thinning start region 64 of each of the plurality of dies 61 is determined such that the features of interest of each of the plurality of dies 61 are respectively within (but not identical to) the thinning start region 64 of each of the plurality of dies 61; the thinning start region 64 of each of the plurality of dies 61 respectively covers an active region of the element 7 of each of the plurality of dies 61 on the upper surface 60 of the wafer 6, and the features of interest 62 of each of the plurality of dies 61 are respectively (determined to be) identical to the thinning start region 64 of each of the plurality of dies 61. Please also refer to Figure 26 This refers to the process of locally thinning the starting area of ​​the grain in the wafer after the local laser thinning process of the present invention is performed. Figure 25A cross-sectional schematic diagram of the grains. After performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, a back groove 75 of each of the plurality of grains 61 is formed on the back side of the wafer 6. The back groove 75 of each of the plurality of grains 61 has a bottom surface 76, a sidewall 77, and an opening 78 on the lower surface 63 of the wafer 6. In this embodiment, the region of interest 62 of each of the plurality of grains 61 is (determined) identical to the thinning start region 64 of each of the plurality of grains 61; therefore, the sidewall 77 of the back groove 75 of each of the plurality of grains 61 has an upright shape. The area occupied by the opening 78 of the back groove 75 of each of the plurality of grains 61 on the lower surface 63 of the wafer 6 is identical to the thinning start region 64 of each of the plurality of grains 61. Each of the plurality of grains 61 has a region of interest 62 that is identical to the region occupied by the bottom surface 76 of the back recess 75 of each of the plurality of grains 61. The opening 78 of the back recess 75 of each of the plurality of grains 61 and the bottom surface 76 of the back recess 75 of each of the plurality of grains 61 have identical shapes and identical areas. In this embodiment, the wafer 6 has a desired thickness D within the region of interest 62 of each of the plurality of grains 61; while the wafer 6 has a uniform thickness T outside the region of interest 62 of each of the plurality of grains 61 (outside the thinning start region 64). Therefore, the mechanical strength of the wafer 6 is improved. The structure of the wafer 6 is sufficient to balance the enormous stress caused by the numerous layers formed on the upper surface 60 of the wafer 6. Therefore, the problem of wafer 6 warping does not occur.

[0102] exist Figure 26 In the embodiments described above, after the wafer 6 is locally thinned by the local laser thinning process of the present invention, if the wafer 6 is cut into separate individual dies (wafers) along these dashed cutting lines 65, each of the separate individual dies (wafers) 61 may have a sidewall 77 of a back groove 75. The thickness of the sidewall 77 of the back groove 75 of each of the separate individual dies (wafers) 61 is slightly less than a thickness T2. The structure of the wafer 6 in a single separate individual die (wafer) 61 is sufficient to balance the enormous stress caused by the many layers formed on the upper surface 60 of the wafer 6. Therefore, not only is the mechanical strength of the entire wafer 6 improved, but the mechanical strength of each separate individual die (wafer) 61 is also improved after multiple dies 61 are cut into separate individual dies (wafers) 61.

[0103] Please see Figure 27This is a cross-sectional schematic diagram of another specific embodiment of a region of interest and a region to be thinned starting area of ​​a die before the wafer is locally thinned by the local laser thinning process of the present invention. In this embodiment, a wafer 6 includes a plurality of dies 61, wherein each of the plurality of dies 61 includes only one element 7 (the element 7 is not as shown in the diagram). Figure 3 (A power device shown), wherein the features of interest of each of the plurality of dies 61 are respectively determined as element 7 of each of the plurality of dies 61 on the upper surface 60 of the wafer 6, wherein the thinning start region 64 of each of the plurality of dies 61 is respectively determined such that the features of interest of each of the plurality of dies 61 are respectively within the thinning start region 64 of each of the plurality of dies 61 (but not identical to the thinning start region 64 of each of the plurality of dies 61; the thinning start region 64 of each of the plurality of dies 61 respectively covers an active region of element 7 of each of the plurality of dies 61 on the upper surface 60 of the wafer 6), wherein the regions of interest 62 of each of the plurality of dies 61 are respectively (determined to be) within the thinning start region 64 of each of the plurality of dies 61 (but not identical to the thinning start region 64 of each of the plurality of dies 61). In this embodiment, in each of the plurality of grains 61, the region of interest 62 includes a first sub-region of interest 621, a second sub-region of interest 622, a third sub-region of interest 623, a fourth sub-region of interest 624, and a fifth sub-region of interest 625. Please also refer to Figure 28 This refers to the process of locally thinning the starting area of ​​the grain in the wafer after the local laser thinning process of the present invention is performed. Figure 27A cross-sectional schematic diagram of the grains. After performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, a back groove 75 of each of the plurality of grains 61 is formed on the back side of the wafer 6. The back groove 75 of each of the plurality of grains 61 has a bottom surface 76 (including a first bottom surface 761, a second bottom surface 762, a third bottom surface 763, a fourth bottom surface 764 and a fifth bottom surface 765), a main sidewall 77, a first sidewall 770, a second sidewall 771 and an opening 78 on the lower surface 63 of the wafer 6. In this embodiment, the region of interest 62 of each of the plurality of grains 61 is respectively (determined to be) within (but not identical to) the thinning start region 64 of each of the plurality of grains 61; and the shape of the main sidewall 77 of the back groove 75 of each of the plurality of grains 61 is (determined to be) tapered (the tapered main sidewall 77 of the back groove 75 can be achieved by a combination of many steps). The shape of the first sidewall 770 and the shape of the second sidewall 771 of the back groove 75 of each of the plurality of grains 61 are determined to be upright. The area occupied by the opening 78 of the back groove 75 of each of the plurality of grains 61 on the lower surface 63 of the wafer 6 is identical to the thinning start region 64 of each of the plurality of grains 61. Each of the plurality of dies 61 has a region of interest 62 that is contiguous with a region occupied by the bottom surface 76 (including the first bottom surface 761, the second bottom surface 762, the third bottom surface 763, the fourth bottom surface 764, and the fifth bottom surface 765) of the back recess 75 of each of the plurality of dies 61. The region occupied by the opening 78 of the back recess 75 of each of the plurality of dies 61 is wider than the region occupied by the bottom surface 76 of the back recess 75 of each of the plurality of dies 61. In this embodiment, the wafer 6 has a desired thickness D1 in the first sub-region of interest 621 and the fifth sub-region of interest 625 of each of the plurality of dies 61; the wafer 6 has a desired thickness D2 in the second sub-region of interest 622 and the fourth sub-region of interest 624 of each of the plurality of dies 61; and the wafer 6 has a desired thickness D3 in the third sub-region of interest 623 of each of the plurality of dies 61; wherein the desired thickness D3 is greater than the desired thickness D1; ​​and the desired thickness D1 is greater than the desired thickness D2.

[0104] The partial wafer thinning method of the present invention does not require photolithographic processes. For example, a photoresist is formed on the lower surface 63 of wafer 6, and then a mask is used for exposure and development to expose the thinning start area 64 of each of the plurality of grains 61. Then, dry etching or wet etching is performed to form the backside groove 75 of each of the plurality of grains 61. If the user wants to form a photolithographic process... Figure 28 The back groove 75 in the embodiment requires many complex procedures to achieve. In contrast, the local wafer thinning method of the present invention can be used to form... Figure 28 The back recess 75 in the embodiment is very simple. Using the partial wafer thinning method of the present invention, not only can back recesses 75 with complex shapes be easily formed, but the depth of the back recess 75 can also be easily controlled. Furthermore, when using a lithography process to form the back recess 75, if the wafer 6 is made of silicon carbide (a very hard material), the etching rate is very slow. This means that more time is needed to etch the silicon carbide wafer 6 to form the back recess 75. In contrast, forming the back recess 75 using the partial wafer thinning method of the present invention is very fast. For example, when using a lithography process to form the back recess 75, if it is made of gallium arsenide (GaAs) (a material not as hard as silicon carbide), the etching rate is faster than etching silicon carbide. However, compared to using a lithography process, forming the back recess 75 using the partial wafer thinning method of the present invention is still faster than etching gallium arsenide using a lithography process (faster than etching gallium arsenide using a lithography process). Furthermore, during the etching of gallium arsenide, the depth variation of the back groove 75 is affected by the temperature gradient and the concentration gradient of the etching solution / gas. Therefore, the depth variation of the back groove 75 will be quite large.

[0105] Please see Figure 29 This is a cross-sectional schematic diagram of another specific embodiment of a partial wafer thinning system of the present invention. Figure 29 The main structure of the specific embodiments and Figure 1The specific embodiments are generally similar in structure; however, the wafer 6 is transparent, the image capturing element 30 of the image capturing device 3 is disposed on the lower surface 63 of the wafer 6 (for example, the image capturing element 30 is disposed next to the laser device 4), and the light source 32 of the image capturing device 3 is disposed below the hollow central portion 20 of the driving device 2. The light source 32 is a non-coaxial light source. The light emitted by the light source 32 can pass through the hollow central portion 20 of the driving device 2 and the hollow central portion 51 of the support device 5 to illuminate at least a portion of the wafer 6 (for example, at least one die 61), and enable the image capturing element 30 of the image capturing device 3 to capture an image of at least one die 61 (the outline of the element 7 of at least one die 61) from the lower surface 63 of the wafer 6 (because the wafer 6 is transparent). In some other embodiments, the light emitted by the light source 32 can illuminate the entire wafer 6, so that the image capturing element 30 of the image capturing device 3 can capture an image of each of the plurality of dies 61 (the outline of the element 7 of each of the plurality of dies 61) from the lower surface 63 of the wafer 6 (because the wafer 6 is transparent).

[0106] In some embodiments, (not shown) the wafer 6 is transparent, the image capturing element 30 of the image capturing device 3 is disposed below the hollow central portion 20 of the driving device 2, and the light source 32 of the image capturing device 3 is a non-coaxial light source, which is disposed above the lower surface 63 of the wafer 6 (for example, the light source 32 is a ring light source disposed between the lower surface 63 of the wafer 6 and the laser device 4; or the light source 32 is disposed next to the laser device 4).

[0107] In some other embodiments, (not shown in the figure) the wafer 6 is transparent, and the image capturing element 30 and the light source 32 of the image capturing device 3 are disposed on the lower surface 63 of the wafer 6 (for example, the image capturing element 30 and the light source 32 are disposed next to the laser device 4).

[0108] In some embodiments, the hollow central portion 51 of the support device 5 may also be non-hollow, wherein the hollow central portion 51 of the support device 5 may be made of a transparent material, such as glass.

[0109] Please see Figure 30 This is a cross-sectional schematic diagram of two grains after the wafer has been locally thinned by the local laser thinning process of the present invention. Figure 30 The main structure of the specific embodiments and Figure 18The specific embodiments are structurally similar; however, the wafer 6 includes a plurality of dies 61 and a plurality of dies 61', each of the plurality of dies 61 including an element 7, and each of the plurality of dies 61' including an element 7', wherein a feature of interest for each of the plurality of dies 61 is respectively determined as element 7 of each of the plurality of dies 61; and a feature of interest ' for each of the plurality of dies 61' is respectively determined as element 7' of each of the plurality of dies 61; wherein a thinning start region 64 for each of the plurality of dies 61 is respectively determined, such that the feature of interest for each of the plurality of dies 61 is respectively located in the thinning start region 64 of each of the plurality of dies 61. Within the thinning initiation region 64 (but not identical to the thinning initiation region 64 of each of the plurality of grains 61); and a thinning initiation region 64' of each of the plurality of grains 61' is respectively determined to be identical to the feature of interest of each of the plurality of grains 61'; wherein a region of interest 62 of each of the plurality of grains 61 is respectively (determined to be) within the thinning initiation region 64 of each of the plurality of grains 61 (but not identical to the thinning initiation region 64 of each of the plurality of grains 61); and a region of interest 62' of each of the plurality of grains 61' is respectively (determined to be) identical to the thinning initiation region 64' of each of the plurality of grains 61'.In this embodiment, after performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 in the thinning start region 64 of each of the plurality of grains 61 and in the thinning start region 64' of each of the plurality of grains 61', a back groove 75 of each of the plurality of grains 61 and a back groove 75' of each of the plurality of grains 61' are formed on the back side of the wafer 6; wherein the back groove 75 of each of the plurality of grains 61 has a bottom surface 76, a sidewall 77 and an opening 78 on the lower surface 63 of the wafer 6; wherein the plurality of grains 61 Each of the plurality of grains 61 has a back groove 75' having a bottom surface 76', a sidewall 77', and an opening 78' on the lower surface 63 of the wafer 6; wherein the sidewall 77 of the back groove 75 of each of the plurality of grains 61 has a tapered shape (the tapered sidewall 77 of the back groove 75 can be achieved by a combination of many steps); wherein the area occupied by the opening 78 of the back groove 75 of each of the plurality of grains 61 on the lower surface 63 of the wafer 6 is identical to the thinning start area 64 of each of the plurality of grains 61; wherein the plurality of grains 61 The region of interest 62 of each of the plurality of grains 61 is identical to the region occupied by the bottom surface 76 of the back groove 75 of each of the plurality of grains 61; wherein the sidewall 77' of the back groove 75' of each of the plurality of grains 61 is upright; wherein the opening 78' of the back groove 75' of each of the plurality of grains 61 occupies a region on the lower surface 63 of the wafer 6 that is identical to the thinning start region 64' of each of the plurality of grains 61; wherein the region of interest 62' of each of the plurality of grains 61 occupies a region identical to the back groove of each of the plurality of grains 61. The bottom surface 76' of 75' occupies a region; wherein the opening 78' of the back groove 75' of each of the plurality of grains 61' and the bottom surface 76' of the back groove 75' of each of the plurality of grains 61' have an identical shape and an identical area; wherein the wafer 6 has a desired thickness D in the region of interest 62 of each of the plurality of grains 61; and the wafer 6 has a desired thickness D' in the region of interest 62' of each of the plurality of grains 61', wherein the desired thickness D is not equal to the desired thickness D' (in this embodiment, the desired thickness D' is greater than the desired thickness D).

[0110] Please see Figure 31This is a partially enlarged schematic diagram of a lower surface of a wafer before it is locally thinned by the local laser thinning process of the present invention, according to another specific embodiment. In this embodiment, a wafer 6 includes a plurality of grains 61, including a first grain 611, a second grain 612, a third grain 613, a fourth grain 614, a fifth grain 615, a sixth grain 616, a seventh grain 617, an eighth grain 618, a ninth grain 619, and some other grains 61. Figure 31 The dashed cutting line 65 in the diagram represents the boundary of each of the plurality of grains 61. A region of interest 62 and a thinning initiation region 64 for each of the first grain 611, the second grain 612, the third grain 613, the fourth grain 614, the fifth grain 615, the sixth grain 616, the seventh grain 617, the eighth grain 618, the ninth grain 619, and some other grains 61 are determined and shown in the diagram. Figure 31 After performing step C (at least after the starting region 64 for thinning of each of the plurality of grains 61 has been determined), the method for partial wafer thinning of the present invention further includes the step of dividing the plurality of grains 61 into grain groups 68, wherein each of the plurality of grain groups 68 comprises at least two grains 61; and wherein, in each of the plurality of grain groups 68, any one grain 61 is adjacent to at least one other grain 61. Figure 31 One of the plurality of grain groups 68 is shown in the middle. Located in Figure 31 A middle grain group 68 comprises nine grains 61 (including a first grain 611, a second grain 612, a third grain 613, a fourth grain 614, a fifth grain 615, a sixth grain 616, a seventh grain 617, an eighth grain 618, and a ninth grain 619); wherein, in the grain group 68, any two adjacent grains 61 have a boundary region 66 between the thinning start regions 64 of the two adjacent grains 61; for example, the first grain 611 and the second grain 612 are two adjacent grains 61, and there is a boundary region 66 between the thinning start regions 64 of the first grain 611 and the thinning start regions 64 of the second grain 612. Please also refer to... Figure 32 This refers to the process after the wafer has been locally thinned using the local laser thinning process of this invention. Figure 31A schematic diagram of the lower surface of the wafer. In this embodiment, in step F of the local wafer thinning method of the present invention, the laser device 4 performs local laser thinning on the lower surface 63 of the wafer 6 not only within the thinning start region 64 of each of the plurality of grains 61, but also within a boundary region 66 between any two adjacent grains 61 in each of the plurality of grain groups 68, so that the wafer 6 is locally thinned within the thinning start region 64 of each of the plurality of grains 61 and within the boundary region 66 between any two adjacent grains 61 in each of the plurality of grain groups 68 (in this embodiment, in Figure 31In the displayed grain group 68, wafer 6 is located in the following areas: the thinning start region 64 of the nine grains 61 (first grain 611 to ninth grain 619); the boundary region 66 between the thinning start regions 64 of the first grain 611 and the second grain 612; the boundary region 66 between the thinning start regions 64 of the second grain 612 and the third grain 613; the boundary region 66 between the thinning start regions 64 of the first grain 611 and the fourth grain 614; and the boundary region 66 between the second grain 612 and the fifth grain 619. The boundary regions 66 between the thinning initiation regions 64 of the 15 grains respectively, the boundary regions 66 between the thinning initiation regions 64 of the third grain 613 and the sixth grain 616 respectively, the boundary regions 66 between the thinning initiation regions 64 of the fourth grain 614 and the fifth grain 615 respectively, the boundary regions 66 between the thinning initiation regions 64 of the fifth grain 615 and the sixth grain 616 respectively, and the boundary regions between the thinning initiation regions 64 of the fourth grain 614 and the seventh grain 617 respectively. The regions 66 within the boundaries between the thinning initiation regions 64 of the fifth grain 615 and the eighth grain 618, the sixth grain 616 and the ninth grain 619, the seventh grain 617 and the eighth grain 618, and the eighth grain 618 and the ninth grain 619 are locally thinned to form the plurality of grain groups 68. Each of the plurality of grain groups 68 has a non-separable back groove 67, wherein the non-separable back groove 67 of each of the plurality of grain groups 68 has an opening; wherein, in any of the plurality of grain groups 68, a region occupied by the opening of the non-separable back groove 67 of the grain group 68 can be defined by a merged region formed by merging the thinning start region 64 of each grain 61 in the grain group 68 and the boundary region 66 between the thinning start regions 64 of any two adjacent grains 61 in the grain group 68 (in this embodiment, in Figure 31 In the grain group 68 shown, the opening of the non-separated back groove 67 is as follows: Figure 32(As shown). The desired thickness of wafer 6 within the boundary region 66 between the thinning start regions 64 of any two adjacent grains 61 in the grain group 68 may be the same as or different from the desired thickness of wafer 6 within the region of interest 62 of any two adjacent grains 61 in the grain group 68. (In this embodiment, the desired thickness of wafer 6 within the boundary region 66 between the thinning start regions 64 of any two adjacent grains 61 in the grain group 68 may be the same as the desired thickness of wafer 6 within the region of interest 62 of any two adjacent grains 61 in the grain group 68.)

[0111] In some embodiments, a wafer 6 includes a plurality of grains 61, wherein the plurality of grains 61 includes N grains 61 (e.g., N = 80, i.e., the wafer 6 includes 80 grains 61); after performing step C (at least after the starting region 64 to be thinned for each of the plurality of grains 61 is determined), the method for partial wafer thinning of the present invention further includes the following step: dividing M of the N grains 61 into at least two grain groups 68, wherein N ≥ M ≥ 4, N and M are positive integers, wherein any two grain groups 68 respectively include P grains 61 and Q grains 61 of the M grains 61, wherein M ≥ (P + Q) ≥ 4, P = Q or P ≠ Q, P and Q are positive integers; that is, any two grain groups 68 may respectively contain the same number of grains 61 or different numbers of grains 61; wherein, in each of the plurality of grain groups 68, any one grain 61 is adjacent to at least one other grain 61. For example, when N>M≥4, the M grains 61 are M of the N grains 61; and when N=M≥4, the M grains 61 are the N grains 61. The M grains 61 among the N grains 61 can be divided into two grain groups 68, three grain groups 68, or more grain groups 68. For example, when N=97 and M=97, these M (97) grains 61 can be divided into 9 grain groups 68 (each of the 9 grain groups 68 includes 9 grains 61) and another 4 grain groups 68 (each of the 4 grain groups 68 includes 4 grains 61). In another example, when N = 97 and M = 81, the M (81) grains 61 can be divided into 6 grain groups 68 (each of the 6 grain groups 68 includes 9 grains 61) and another 3 grain groups 68 (each of the 3 grain groups 68 includes 9 grains 61), while the remaining 16 grains 61 of the N (97) grains 61 are not divided into any grain group 68. To give another example, when N = 97 and M = 81, these M (81) grains 61 can be divided into 5 grain groups 68 (each of the 5 grain groups 68 includes 9 grains 61), another 3 grain groups 68 (each of the 3 grain groups 68 includes 8 grains 61), and another 2 grain groups 68 (each of the 2 grain groups 68 includes 6 grains 61), while the remaining 16 grains 61 of the N (97) grains 61 are not divided into any grain group 68.

[0112] Please see Figure 33This is a partially enlarged schematic diagram of the lower surface of a wafer after it has been partially thinned by the local laser thinning process of the present invention. In this embodiment, a wafer 6 includes a plurality of grains 61, each of which includes nine sub-grains (including a first grain 691, a second grain 692, a third grain 693, a fourth grain 694, a fifth grain 695, a sixth grain 696, a seventh grain 697, an eighth grain 698, and a ninth grain 699); wherein, in each of the plurality of grains 61, the dashed cutting line 65' represents the nine sub-grains (including the first grain 691, the second grain 692, the third grain 693, the fourth grain 694, the fifth grain 695, the sixth grain 696, the seventh grain 697, the eighth grain 698, and the ninth grain 699). The boundary between the eighth sub-grain 698 and the ninth sub-grain 699; wherein each of the nine sub-grains includes at least one element (not shown) formed on the upper surface 60 of the wafer 6; wherein, in each of the plurality of grains 61, a feature of interest is determined as a non-separated region occupied by a combination of at least one element of each of the nine sub-grains; wherein, in each of the plurality of grains 61, a thinning start region 64 is determined such that the feature of interest is within (but not identical to) the thinning start region 64; wherein, in each of the plurality of grains 61, a region of interest 62 (determined to) be identical to the thinning start region 64. After performing the local laser thinning process of the present invention on the lower surface 63 of the wafer 6 within the thinning start region 64 of each of the plurality of grains 61, a back groove 75 of each of the plurality of grains 61 is formed on the back side of the wafer 6. In each of the plurality of grains 61, a back groove 75 has a bottom surface, a sidewall, and an opening on the lower surface 63 of the wafer 6; the sidewall of the back groove 75 is upright; the opening of the back groove 75 occupies an area on the lower surface 63 of the wafer 6 that is identical to the thinning start area 64; the region of interest 62 is identical to the area occupied by the bottom surface of the back groove 75; wherein the dashed cut lines 65' (the boundaries between the nine sub-grains) are within the area occupied by the bottom surface of the back groove 75. The wafer 6 has a desired thickness (not shown) within the region of interest 62 of each of the plurality of grains 61. In this embodiment, the wafer 6 will be diced into a plurality of separate, independent sub-grains along these dashed cut lines 65'. In some embodiments, the wafer 6 will be diced into a plurality of separate, independent grains 61 along these dashed cut lines 65', and then each of the plurality of grains 61 will be diced into nine separate, independent sub-grains along these dashed cut lines 65'.

[0113] exist Figures 8-10 , Figure 21 and Figure 26In one embodiment, the sidewall 77 of the back groove 75 of each of the plurality of grains 61 is upright (perpendicular to the lower surface 63 of the wafer 6); while Figure 14 In one embodiment, the sidewall 77 of the back recess 75 of each of the plurality of grains 61 has a tapered shape (not perpendicular to the lower surface 63 of the wafer 6), but is steep (i.e., the slope of the sidewall 77 is large; for example, the slope of the sidewall 77 is equal to 4, 5, 6, 7, 8, 9, or 10). In some other embodiments, the sidewall 77 of the back recess 75 of each of the plurality of grains 61 has a tapered shape, but is not steep (for example, the slope of the sidewall 77 is equal to 3, 2, or 1). Figure 16 In one embodiment, the sidewall 77 of the back groove 75 of each of the plurality of grains 61 has a stepped shape. In other embodiments, the sidewall 77 of the back groove 75 of each of the plurality of grains 61 may have a combination of stepped and tapered shapes.

[0114] Wafer 6 has a desired thickness D within a region of interest 62 of each of the plurality of grains 61. In some embodiments, the desired thickness D is greater than or equal to 200 μm and less than or equal to 300 μm. In other embodiments, the desired thickness D is greater than or equal to 100 μm and less than or equal to 200 μm. In other embodiments, the desired thickness D is greater than or equal to 50 μm and less than or equal to 100 μm. In some embodiments, the desired thickness D is greater than or equal to 20 μm and less than or equal to 50 μm. In other embodiments, the desired thickness D is greater than or equal to 10 μm and less than or equal to 20 μm.

[0115] exist Figure 28In some embodiments, wafer 6 has a desired thickness D2 within a second sub-region of interest 622 and a fourth sub-region of interest 624 of each of the plurality of grains 61. In some embodiments, the desired thickness D2 is greater than or equal to 200 μm and less than or equal to 300 μm. In some other embodiments, the desired thickness D2 is greater than or equal to 100 μm and less than or equal to 200 μm. In some other embodiments, the desired thickness D2 is greater than or equal to 50 μm and less than or equal to 100 μm. In some embodiments, the desired thickness D2 is greater than or equal to 20 μm and less than or equal to 50 μm. In some other embodiments, the desired thickness D2 is greater than or equal to 10 μm and less than or equal to 20 μm. In some embodiments, the desired thickness D2 is greater than or equal to 5 μm and less than or equal to 10 μm. In some embodiments, the desired thickness D2 is greater than or equal to 2 μm and less than or equal to 5 μm. In some embodiments, the desired thickness D2 is greater than or equal to 1 μm and less than or equal to 2 μm. In some embodiments, the desired thickness D2 is greater than or equal to 500 nm and less than or equal to 1 μm. In some embodiments, the required thickness D2 is greater than or equal to 200 nm and less than or equal to 500 nm. In some embodiments, the required thickness D2 is greater than or equal to 100 nm and less than or equal to 200 nm.

[0116] In some embodiments, the region of interest 62 or the second sub-region of interest 622 has a circular shape, wherein the diameter of the circle of the region of interest 62 or the second sub-region of interest 622 is greater than or equal to 10000 μm and less than or equal to 15000 μm. In other embodiments, the diameter is greater than or equal to 5000 μm and less than or equal to 10000 μm. In other embodiments, the diameter is greater than or equal to 2000 μm and less than or equal to 5000 μm. In other embodiments, the diameter is greater than or equal to 1000 μm and less than or equal to 2000 μm. In other embodiments, the diameter is greater than or equal to 500 μm and less than or equal to 1000 μm. In other embodiments, the diameter is greater than or equal to 200 μm and less than or equal to 500 μm. In other embodiments, the diameter is greater than or equal to 120 μm and less than or equal to 200 μm. In other embodiments, the diameter is greater than or equal to 80 μm and less than or equal to 120 μm. In some other embodiments, the diameter is greater than or equal to 30 μm and less than or equal to 80 μm. In some other embodiments, the diameter is greater than or equal to 10 μm and less than or equal to 30 μm. In some other embodiments, the diameter is greater than or equal to 5 μm and less than or equal to 10 μm.

[0117] In some embodiments, the region of interest 62 or the second sub-region of interest 622 has an elliptical shape, wherein the minor axis of the ellipse of the region of interest 62 or the second sub-region of interest 622 is smaller than the major axis of the ellipse of the region of interest 62 or the second sub-region of interest 622. In some embodiments, the minor axis is greater than or equal to 10000 μm and less than or equal to 15000 μm, and the major axis is less than or equal to 30000 μm. In some other embodiments, the minor axis is greater than or equal to 5000 μm and less than or equal to 10000 μm, and the major axis is less than or equal to 20000 μm. In some other embodiments, the minor axis is greater than or equal to 2000 μm and less than or equal to 5000 μm, and the major axis is less than or equal to 15000 μm. In some other embodiments, the minor axis is greater than or equal to 1000 μm and less than or equal to 2000 μm, and the major axis is less than or equal to 6000 μm. In some other embodiments, the minor axis is greater than or equal to 500 μm and less than or equal to 1000 μm, and the major axis is less than or equal to 3000 μm. In some other embodiments, the minor axis is greater than or equal to 200 μm and less than or equal to 500 μm, and the major axis is less than or equal to 1500 μm. In some other embodiments, the minor axis is greater than or equal to 120 μm and less than or equal to 200 μm, and the major axis is less than or equal to 600 μm. In some other embodiments, the minor axis is greater than or equal to 80 μm and less than or equal to 120 μm, and the major axis is less than or equal to 360 μm. In some other embodiments, the minor axis is greater than or equal to 30 μm and less than or equal to 80 μm, and the major axis is less than or equal to 240 μm. In some other embodiments, the minor axis is greater than or equal to 10 μm and less than or equal to 30 μm, and the major axis is less than or equal to 90 μm. In some other embodiments, the minor axis is greater than or equal to 5 μm and less than or equal to 10 μm, and the major axis is less than or equal to 30 μm.

[0118] In some embodiments, the thinning start region 64 has a circular shape, wherein the diameter of the circle of the thinning start region 64 is greater than or equal to 10000 μm and less than or equal to 15000 μm. In other embodiments, the diameter is greater than or equal to 5000 μm and less than or equal to 10000 μm. In other embodiments, the diameter is greater than or equal to 2000 μm and less than or equal to 5000 μm. In other embodiments, the diameter is greater than or equal to 1000 μm and less than or equal to 2000 μm. In other embodiments, the diameter is greater than or equal to 500 μm and less than or equal to 1000 μm. In other embodiments, the diameter is greater than or equal to 200 μm and less than or equal to 500 μm. In other embodiments, the diameter is greater than or equal to 120 μm and less than or equal to 200 μm. In other embodiments, the diameter is greater than or equal to 80 μm and less than or equal to 120 μm. In some other embodiments, the diameter is greater than or equal to 30 μm and less than or equal to 80 μm. In some other embodiments, the diameter is greater than or equal to 10 μm and less than or equal to 30 μm. In some other embodiments, the diameter is greater than or equal to 5 μm and less than or equal to 10 μm.

[0119] In some embodiments, the thinning start region 64 has an elliptical shape, wherein a minor axis of the ellipse is smaller than a major axis. In some embodiments, the minor axis is greater than or equal to 10,000 μm and less than or equal to 15,000 μm, and the major axis is less than or equal to 30,000 μm. In other embodiments, the minor axis is greater than or equal to 5,000 μm and less than or equal to 10,000 μm, and the major axis is less than or equal to 20,000 μm. In other embodiments, the minor axis is greater than or equal to 2,000 μm and less than or equal to 5,000 μm, and the major axis is less than or equal to 15,000 μm. In other embodiments, the minor axis is greater than or equal to 1,000 μm and less than or equal to 2,000 μm, and the major axis is less than or equal to 6,000 μm. In some other embodiments, the minor axis is greater than or equal to 500 μm and less than or equal to 1000 μm, and the major axis is less than or equal to 3000 μm. In some other embodiments, the minor axis is greater than or equal to 200 μm and less than or equal to 500 μm, and the major axis is less than or equal to 1500 μm. In some other embodiments, the minor axis is greater than or equal to 120 μm and less than or equal to 200 μm, and the major axis is less than or equal to 600 μm. In some other embodiments, the minor axis is greater than or equal to 80 μm and less than or equal to 120 μm, and the major axis is less than or equal to 360 μm. In some other embodiments, the minor axis is greater than or equal to 30 μm and less than or equal to 80 μm, and the major axis is less than or equal to 240 μm. In some other embodiments, the minor axis is greater than or equal to 10 μm and less than or equal to 30 μm, and the major axis is less than or equal to 90 μm. In some other embodiments, the minor axis is greater than or equal to 5 μm and less than or equal to 10 μm, and the major axis is less than or equal to 30 μm.

[0120] In some embodiments, the region of interest 62 has a rectangular shape, wherein a first side of the rectangle of the region of interest 62 is less than or equal to a second side of the rectangle of the region of interest 62. In some embodiments, the first side is greater than or equal to 10000 μm and less than or equal to 15000 μm, and the second side is less than or equal to 30000 μm. In other embodiments, the first side is greater than or equal to 5000 μm and less than or equal to 10000 μm, and the second side is less than or equal to 20000 μm. In other embodiments, the first side is greater than or equal to 2000 μm and less than or equal to 5000 μm, and the second side is less than or equal to 15000 μm. In other embodiments, the first side is greater than or equal to 1000 μm and less than or equal to 2000 μm, and the second side is less than or equal to 6000 μm. In other embodiments, the first side is greater than or equal to 500 μm and less than or equal to 1000 μm, and the second side is less than or equal to 3000 μm. In some other embodiments, the first side is greater than or equal to 200 μm and less than or equal to 500 μm, and the second side is less than or equal to 1500 μm. In some other embodiments, the first side is greater than or equal to 120 μm and less than or equal to 200 μm, and the second side is less than or equal to 600 μm. In some other embodiments, the first side is greater than or equal to 80 μm and less than or equal to 120 μm, and the second side is less than or equal to 360 μm. In some other embodiments, the first side is greater than or equal to 30 μm and less than or equal to 80 μm, and the second side is less than or equal to 240 μm. In some other embodiments, the first side is greater than or equal to 10 μm and less than or equal to 30 μm, and the second side is less than or equal to 90 μm. In some other embodiments, the first side is greater than or equal to 5 μm and less than or equal to 10 μm, and the second side is less than or equal to 30 μm.

[0121] In some embodiments, the thinning start region 64 has a rectangular shape, wherein a first side of the rectangle is less than or equal to a second side. In some embodiments, the first side is greater than or equal to 10000 μm and less than or equal to 15000 μm, and the second side is less than or equal to 30000 μm. In other embodiments, the first side is greater than or equal to 5000 μm and less than or equal to 10000 μm, and the second side is less than or equal to 20000 μm. In other embodiments, the first side is greater than or equal to 2000 μm and less than or equal to 5000 μm, and the second side is less than or equal to 15000 μm. In other embodiments, the first side is greater than or equal to 1000 μm and less than or equal to 2000 μm, and the second side is less than or equal to 6000 μm. In other embodiments, the first side is greater than or equal to 500 μm and less than or equal to 1000 μm, and the second side is less than or equal to 3000 μm. In some other embodiments, the first side is greater than or equal to 200 μm and less than or equal to 500 μm, and the second side is less than or equal to 1500 μm. In some other embodiments, the first side is greater than or equal to 120 μm and less than or equal to 200 μm, and the second side is less than or equal to 600 μm. In some other embodiments, the first side is greater than or equal to 80 μm and less than or equal to 120 μm, and the second side is less than or equal to 360 μm. In some other embodiments, the first side is greater than or equal to 30 μm and less than or equal to 80 μm, and the second side is less than or equal to 240 μm. In some other embodiments, the first side is greater than or equal to 10 μm and less than or equal to 30 μm, and the second side is less than or equal to 90 μm. In some other embodiments, the first side is greater than or equal to 5 μm and less than or equal to 10 μm, and the second side is less than or equal to 30 μm.

[0122] In some embodiments, the region of interest 62 has a polygonal shape. In some embodiments, the region of interest 62 has an L-shaped shape. In some embodiments, the region of interest 62 has a triangular shape. In some embodiments, the region of interest 62 has an oblong shape. In some embodiments, the starting region to be thinned 64 has a polygonal shape. In some embodiments, the starting region to be thinned 64 has an L-shaped shape. In some embodiments, the starting region to be thinned 64 has a triangular shape. In some embodiments, the starting region to be thinned 64 has an oblong shape.

[0123] In this invention, the desired thickness D within the region of interest 62 of each of the plurality of grains 61 is independent of the shape of the region of interest 62 of each of the plurality of grains 61 and is independent of the area of ​​the region of interest 62 of each of the plurality of grains 61.

[0124] In some embodiments, a ratio of the region of interest 62 to the region to be thinned starting 64 (i.e., a ratio of the area occupied by the bottom surface 76 of the back recess 75 to the area occupied by the opening 78 of the back recess 75) is greater than or equal to 0.98 and less than or equal to 1. In some embodiments, the ratio is greater than or equal to 0.95 and less than or equal to 0.98. In some embodiments, the ratio is greater than or equal to 0.9 and less than or equal to 0.95. In some embodiments, the ratio is greater than or equal to 0.8 and less than or equal to 0.9. In some embodiments, the ratio is greater than or equal to 0.7 and less than or equal to 0.8. In some embodiments, the ratio is greater than or equal to 0.6 and less than or equal to 0.7. In some embodiments, the ratio is greater than or equal to 0.5 and less than or equal to 0.6.

[0125] In some embodiments, the ratio of the thinning start region 64 of the grain 61 to a region occupied by the grain 61 (i.e., the ratio of the region occupied by the opening 78 of the back groove 75 to the region occupied by the grain 61) is greater than or equal to 0.95 and less than or equal to 0.98. In some embodiments, the ratio is greater than or equal to 0.9 and less than or equal to 0.95. In some embodiments, the ratio is greater than or equal to 0.85 and less than or equal to 0.9. In some embodiments, the ratio is greater than or equal to 0.8 and less than or equal to 0.85. In some embodiments, the ratio is greater than or equal to 0.7 and less than or equal to 0.8. In some embodiments, the ratio is greater than or equal to 0.6 and less than or equal to 0.7. In some embodiments, the ratio is greater than or equal to 0.5 and less than or equal to 0.6. In some embodiments, the ratio is greater than or equal to 0.4 and less than or equal to 0.5. In some embodiments, the ratio is greater than or equal to 0.3 and less than or equal to 0.4. In some embodiments, the ratio is greater than or equal to 0.2 and less than or equal to 0.3. In some embodiments, the ratio is greater than or equal to 0.1 and less than or equal to 0.2.

[0126] In some embodiments, the light source 32 may be other types of light sources (e.g., a non-coaxial light source), such as a ring light source, at least one line light source, a surface light source, a diffused dome light source, or other types of light sources.

[0127] In some embodiments, wafer 6 is made of at least one material selected from the group consisting of: glass, silicon carbide (SiC), gallium nitride (GaN), gallium nitride on silicon carbide substrate (GaN on SiC), gallium oxide (Ga2O3), silicon (Si), gallium nitride on silicon substrate (GaN on Si), gallium arsenide (GaAs), sapphire, indium phosphide (InP), gallium phosphide (GaP), aluminum nitride (AlN), zinc selenide (ZnSe), indium arsenide (InAs), silicon germanium (SiGe), diamond, and gallium antimonide (GaSb).

[0128] In some embodiments, the drive device 2 further includes a rotating platform (not shown), wherein the rotating platform of the drive device 2 is disposed on the three-axis moving platform of the drive device 2, and the carrier device 5 is disposed on the rotating platform of the drive device 2, wherein the wafer 6 carried by the carrier device 5 can be rotated along a Z-axis passing through a center of the rotating platform (or along a Z-axis passing through a center of the wafer 6) via the rotating platform.

[0129] In some embodiments, the support device 5 is disposed on a combination of the X-axis moving platform and the Y-axis moving platform of the drive device 2 (not shown in the figure), and the image capturing device 3 is disposed on the Z-axis moving platform (not shown in the figure).

[0130] In some embodiments, the drive device 2 further includes a rotating platform (not shown), wherein the rotating platform of the drive device 2 is disposed on a combination of the X-axis moving platform and the Y-axis moving platform of the drive device 2 (not shown), and the carrier device 5 is disposed on the rotating platform of the drive device 2, and the image capturing device 3 is disposed on the Z-axis moving platform (not shown), wherein the wafer 6 carried by the carrier device 5 can be rotated along the Z-axis passing through a center of the rotating platform (or along the Z-axis passing through a center of the wafer 6) via the rotating platform.

[0131] In some embodiments, the support device 5 is disposed on a combination of the X-axis moving platform and the Y-axis moving platform of the drive device 2 (not shown in the figure), and the laser device 4 is disposed on the Z-axis moving platform (not shown in the figure).

[0132] In some embodiments, the drive device 2 further includes a rotating platform (not shown), wherein the rotating platform of the drive device 2 is disposed on a combination of the X-axis moving platform and the Y-axis moving platform of the drive device 2 (not shown), and the carrier device 5 is disposed on the rotating platform of the drive device 2, and the laser device 4 is disposed on the Z-axis moving platform (not shown), wherein the wafer 6 carried by the carrier device 5 can be rotated along a Z-axis passing through a center of the rotating platform (or along a Z-axis passing through a center of the wafer 6) via the rotating platform.

[0133] In the method for partial wafer thinning of the present invention, step C is performed after step B and before step F. For example, (1) step C is performed after step B, step D is performed after step C, step E is performed after step D, and step F is performed after step E; or (2) step D is performed after step B, step C is performed after step D, step E is performed after step C, and step F is performed after step E; or (3) step D is performed after step B, step E is performed after step D, step C is performed after step E, and step F is performed after step C.

[0134] The present invention further provides a wafer with a locally thinned structure, comprising a wafer 6, wherein the wafer 6 includes a plurality of dies 61, each of the plurality of dies 61 including at least one element 7 and at least one back recess 75. The at least one element 7 is formed on an upper surface 60 of the wafer 6. The at least one back recess 75 is formed by laser processing, wherein the at least one back recess 75 has an opening 78 on a lower surface 63 of the wafer 6. In each of the plurality of dies 61, the area occupied by the opening 78 of the at least one back recess 75 is associated with the at least one element 7. The wafer 6 with the locally thinned structure of the present invention will not experience wafer warping.

[0135] In some implementations, in each of the plurality of grains 61, the area occupied by the opening 78 of at least one back groove 75 is determined according to at least one feature of interest, wherein the at least one feature of interest is associated with at least one element 7.

[0136] In some implementations, in each of the plurality of grains 61, at least one feature of interest is located within, or identical to, the area occupied by the opening 78 of the at least one back groove 75.

[0137] In some implementations, in each of the plurality of grains 61, a region occupied by a bottom surface 76 of at least one back groove 75 is associated with at least one element 7.

[0138] In some implementations, in each of the plurality of grains 61, the area occupied by the bottom surface 76 of at least one back groove 75 is determined according to at least one feature of interest, wherein the at least one feature of interest is associated with at least one element 7.

[0139] In some implementations, in each of the plurality of grains 61, at least one feature of interest is within, or identical to, the area occupied by the bottom surface 76 of at least one back groove 75.

[0140] In some implementations, in each of the plurality of grains 61, the area occupied by the bottom surface 76 of at least one back groove 75 is within the area occupied by the opening 78 of at least one back groove 75, or is identical to the area occupied by the opening 78 of at least one back groove 75.

[0141] In some embodiments, in each of the plurality of grains 61, the wafer 6 has a desired thickness in the area occupied by the bottom surface 76 of at least one backside recess 75. In some embodiments, the desired thickness is greater than 10 μm.

[0142] In some embodiments, in each of the plurality of grains 61, wafer 6 has a first desired thickness D1 in a region occupied by a bottom surface 761 of one of the at least one backside recess 75; and wafer 6 has a second desired thickness D2 in a region occupied by a bottom surface 762 of the other of the at least one backside recess 75, wherein the first desired thickness D1 is less than, equal to or greater than the second desired thickness D2. In some embodiments, the second desired thickness D2 is greater than 100 nm.

[0143] In some embodiments, in each of the plurality of grains 61, the bottom surface 76 of at least one backside recess 75 includes a first bottom surface 761 and a second bottom surface 762 of at least one backside recess 75. The wafer 6 has a first desired thickness D1 within a first region 621 occupied by the first bottom surface 761 of the at least one backside recess 75; and the wafer 6 has a second desired thickness D2 within a second region 622 occupied by the second bottom surface 762 of the at least one backside recess 75, wherein the first desired thickness D1 is less than, equal to, or greater than the second desired thickness D2. In some embodiments, the second desired thickness D2 is greater than 100 nm.

[0144] In some implementations, in each of the plurality of grains 61, the ratio of the area occupied by the bottom surface 76 of at least one back groove 75 to the area occupied by the opening 78 of at least one back groove 75 is greater than or equal to 0.5 and less than or equal to 1.

[0145] In some implementations, each of the plurality of grains 61 includes a plurality of sub-grains 691-699, and each of the plurality of sub-grains 691-699 includes at least one element 7 formed on the upper surface 60 of the wafer 6.

[0146] In some implementations, the ratio of the area occupied by the opening 78 of at least one back groove 75 of any of the plurality of grains 61 to the area occupied by any of the plurality of grains 61 is less than or equal to 0.98.

[0147] In some implementations, in each of the plurality of grains 61, one of at least one back groove is adjacent to another of at least one back groove; wherein a gap between an area occupied by an opening of the at least one back groove and an area occupied by an opening of the other of the at least one back groove is greater than or equal to 10 μm.

[0148] The above describes specific embodiments of the present invention and the technical means used. Many changes and modifications can be derived from the disclosure or teachings herein, which can still be regarded as equivalent changes to the concept of the present invention. The effects produced do not exceed the essential spirit covered by the specification and drawings, and should all be regarded as within the technical scope of the present invention.

[0149] In summary, based on the content disclosed above, the present invention can indeed achieve its intended purpose, providing a system and method for local wafer thinning, which has great industrial value.

Claims

1. A method for local wafer thinning, characterized in that, Includes the following steps: Step A: Provide a wafer, wherein the wafer includes a plurality of grains, each of the plurality of grains including at least one element formed on an upper surface of the wafer; Step B: Determine at least one feature of interest for each of the plurality of grains, wherein the at least one feature of interest for each of the plurality of grains is associated with at least one element of each of the plurality of grains; Step C: Determine at least one thinning start region for each of the plurality of grains based on the at least one feature of interest for each of the plurality of grains; Step D: At least one image of each of the plurality of grains is captured by an image capturing device; Step E: An image recognition element performs image recognition on the at least one image to identify the at least one feature of interest for each of the plurality of grains; as well as Step F: A laser device performs local laser thinning on a lower surface of the wafer in at least one thinning start region of each of the plurality of grains, so that the wafer is locally thinned in the at least one thinning start region of each of the plurality of grains.

2. The method for partial wafer thinning as described in claim 1, characterized in that, It also includes the following step: determining at least one region of interest for each of the plurality of grains based on the at least one feature of interest for each of the plurality of grains, wherein the at least one region of interest for each of the plurality of grains is either within or identical to the at least one thinning start region for each of the plurality of grains.

3. The method for local wafer thinning as described in claim 2, characterized in that, After step F, at least one back groove is formed for each of the plurality of grains, and the at least one region of interest for each of the plurality of grains defines a region occupied by a bottom surface of the at least one back groove for each of the plurality of grains.

4. The method for partial wafer thinning as described in claim 2, characterized in that, After step F, the wafer has a desired thickness in each of the plurality of grains in the at least one region of interest.

5. The method for partial wafer thinning as described in claim 2, characterized in that, After step F, the wafer has a first desired thickness within one of the at least one region of interest of each of the plurality of grains; and the wafer has a second desired thickness within the other of the at least one region of interest of each of the plurality of grains, wherein the first desired thickness is less than, equal to or greater than the second desired thickness.

6. The method for partial wafer thinning as described in claim 2, characterized in that, The at least one feature of interest for each of the plurality of grains is either within or identical to the at least one region of interest for each of the plurality of grains.

7. The method for partial wafer thinning as described in claim 2, characterized in that, In each of the plurality of grains, the at least one region of interest includes a first sub-region of interest and a second sub-region of interest; wherein in each of the plurality of grains, after step F, the wafer has a first desired thickness within the first sub-region of interest of the at least one region of interest; and the wafer has a second desired thickness within the second sub-region of interest of the at least one region of interest, wherein the first desired thickness is less than or equal to the second desired thickness, and wherein the first desired thickness is greater than 100 nm.

8. The method for partial wafer thinning as described in claim 1 or 2, characterized in that, Each of the plurality of grains includes a plurality of sub-grains, and each of the plurality of sub-grains includes at least one of the at least one element formed on the upper surface of the wafer.

9. The method for partial wafer thinning as described in claim 1 or 2, characterized in that, The at least one feature of interest for each of the plurality of grains is either within or identical to the at least one thinning start region of each of the plurality of grains.

10. The method for partial wafer thinning as described in claim 1 or 2, characterized in that, In each of the plurality of grains, one of the at least one thinning start region is adjacent to another of the at least one thinning start region; wherein in each of the plurality of grains, a gap between the at least one thinning start region and the other of the at least one thinning start region is greater than or equal to 10 μm.

11. The method for partial wafer thinning as described in claim 1 or 2, characterized in that, The wafer is made of at least one material selected from the group consisting of: glass, silicon carbide, gallium nitride, gallium nitride on silicon carbide substrate, gallium oxide, silicon, gallium nitride on silicon substrate, gallium arsenide, sapphire, indium phosphide, gallium phosphide, aluminum nitride, zinc selenide, indium arsenide, silicon germanium, diamond, and gallium antimonide.

12. A system for localized wafer thinning, characterized in that, include: A driving device; A carrier device is disposed on the driving device for carrying a wafer, wherein the wafer includes a plurality of grains, and each of the plurality of grains includes at least one element formed on an upper surface of the wafer. An image capturing apparatus includes an image capturing element, wherein the driving device causes at least one of a relative displacement and a relative rotation between the image capturing element and the wafer, the image capturing element being used to capture at least one image of each of the plurality of dies. A control integration device is connected to the driving device, the carrier device, and the image capturing device to control the driving device, the carrier device, and the image capturing device. The control integration device is used to determine at least one feature of interest for each of the plurality of chips and, based on the at least one feature of interest for each of the plurality of chips, to determine at least one thinning start region for each of the plurality of chips. The at least one feature of interest for each of the plurality of chips is associated with at least one element of each of the plurality of chips. The control integration device includes an image recognition element for performing image recognition on the at least one image of each of the plurality of chips captured by the image capturing element to identify the at least one feature of interest for each of the plurality of chips. as well as A laser device is connected to and controlled by the control integration device, wherein the driving device causes at least one of a relative displacement and a relative rotation between the laser device and the wafer, the laser device being used to perform local laser thinning on a lower surface of the wafer in at least one thinning start region of each of the plurality of grains, such that the wafer is locally thinned in the at least one thinning start region of each of the plurality of grains.

13. The system for partial wafer thinning as described in claim 12, characterized in that, The control integration device is further configured to determine at least one region of interest for each of the plurality of grains based on the at least one feature of interest for each of the plurality of grains, wherein the at least one region of interest for each of the plurality of grains is either within or identical to the at least one thinning start region for each of the plurality of grains.

14. The system for partial wafer thinning as described in claim 12 or 13, characterized in that, The wafer is opaque, and the upper surface of the wafer is located between the lower surface of the wafer and the image capturing element.

15. The system for partial wafer thinning as described in claim 12 or 13, characterized in that, The wafer is transparent, and the image capturing device further includes a light source, wherein the upper surface of the wafer is located between the lower surface of the wafer and the light source, wherein the upper surface of the wafer is located between the lower surface of the wafer and the image capturing element, or the lower surface of the wafer is located between the upper surface of the wafer and the image capturing element.

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