Semiconductor chip and forming method thereof
In the manufacturing process of semiconductor chips, first use a cutting knife to form the first cutting groove, and then use laser to cut the back metal layer to form the semiconductor chip, the problem of chip edge missing corners or hidden cracks when the back metal layer is thick is solved, and the chip quality and production yield are improved.
Patent Information
- Application Number
- CN202510119007.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-23
- Publication Date
- 2025-04-15
AI Technical Summary
During the semiconductor chip manufacturing process, when the back metal layer is thicker, missing corners or hidden cracks are prone to appear on the edge of the chip after cutting, affecting the chip quality and production yield.
A first cutting groove is formed by cutting the wafer along the cutting path using a cutting knife, and then a back metal layer is cut along the first cutting groove using laser to form a second cutting groove to separate the wafer from the back metal layer and form a semiconductor chip.
This method avoids the problem of blade passivation when the cutting knife cuts the metal layer on the back, improves the cutting quality, prevents edge collapse and cracks on the edges of the chip, improves the appearance and performance of the chip, and improves the yield of the production.
Smart Images
Figure CN119833476A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a semiconductor chip and a method for forming the same. Background Art
[0002] In the chip manufacturing process, after the wafer completes the front process, it is necessary to attach a front protective film to the front of the wafer to avoid scratches on the front of the wafer when the back of the wafer is thinned. Then, the back of the wafer is thinned to reduce the thickness of the wafer to a preset thickness. After that, the front protective film on the front of the wafer is removed, and the back of the wafer is chemically corroded to remove the rough lines on the back caused by grinding, thereby effectively reducing the contact resistance on the back of the wafer. Then, a back metal layer is formed on the back of the wafer. The thickness of the back metal layer formed on the back of the wafer varies depending on the purpose of the chip. After the back metal layer is formed, the wafer needs to be cut to form a single independent semiconductor chip, so as to facilitate subsequent packaging and other processing of the chip. However, when the thickness of the back metal layer is thick, after the wafer is cut with a blade, problems such as missing corners or hidden cracks will occur at the edge of the formed single chip, affecting the quality of the semiconductor chip, thereby reducing the yield of semiconductor production.
[0003] Therefore, how to avoid corner chipping or cracking on the edges of semiconductor chips formed after cutting, improve the quality of semiconductor chips, and thus increase the yield of semiconductor production is a technical problem that needs to be solved urgently. Summary of the invention
[0004] The present invention provides a semiconductor chip and a method for forming the same, which are used to avoid corner chipping or hidden cracks on the edge of the semiconductor chip formed after cutting, improve the quality of the semiconductor chip, and thus increase the yield of semiconductor production.
[0005] According to some embodiments, the present invention provides a method for forming a semiconductor chip, comprising the following steps:
[0006] A wafer is provided, the wafer comprising a front side and a back side which are relatively distributed along a first direction, a back side metal layer is formed on the back side of the wafer, and the front side of the wafer has a plurality of front side device structures which are arranged at intervals and a dicing path between two adjacent front side device structures;
[0007] Using a cutting knife to cut the wafer along the cutting path to form a first cutting groove extending into the interior of the wafer;
[0008] The back metal layer is cut along the first cutting groove by using a laser to form a second cutting groove connected to the first cutting groove and penetrating the back metal layer along the first direction. The first cutting groove and the second cutting groove separate the wafer into multiple substrates and separate the back metal layer into multiple back conductive layers to form a semiconductor chip including the substrate, the front device structure located above the substrate, and the back conductive layer located below the substrate.
[0009] In some embodiments, the specific steps of forming a back metal layer on the back side of the wafer include:
[0010] A physical vapor deposition process is used to deposit any one of metal titanium, metal aluminum, metal nickel and metal silver, or a combination of two or more of them, onto the back side of the wafer to form the back side metal layer.
[0011] In some embodiments, a thickness of the back metal layer along the first direction is greater than or equal to 8 μm.
[0012] In some embodiments, before cutting the wafer along the cutting path using a cutting knife, the following steps are also included:
[0013] A protection film is formed to cover the surface of the back metal layer facing away from the wafer.
[0014] In some embodiments, a width of the first cutting groove is greater than or equal to 15 μm.
[0015] In some embodiments, the specific steps of using a cutting knife to cut the wafer along the cutting path to form a first cutting groove extending into the interior of the wafer include:
[0016] Using a cutting knife to cut the wafer along the cutting path to form a first cutting groove extending into the interior of the wafer, wherein the thickness of the wafer remaining at the bottom of the first cutting groove along the first direction is greater than or equal to 3 μm; and / or
[0017] The wafer is cut along the cutting path using a cutting knife to form a first cutting groove that penetrates the wafer along the first direction and exposes the surface of the back metal layer.
[0018] In some embodiments, the specific steps of using a laser to cut the back metal layer along the first cutting groove to form a second cutting groove connected to the first cutting groove and penetrating the back metal layer along the first direction include:
[0019] The back metal layer is cut along the first cutting groove by using laser to form the second cutting groove having a width smaller than the first cutting groove.
[0020] In some embodiments, the specific steps of cutting the back metal layer along the first cutting groove using a laser include:
[0021] The back metal layer is cut along the first cutting groove by using a laser with a spot beam width of 3 μm to 7 μm.
[0022] According to some other embodiments, the present invention further provides a semiconductor chip formed by the method for forming a semiconductor chip as described above; the semiconductor chip comprises:
[0023] A substrate, the substrate comprising a first main surface and a second main surface that are oppositely distributed along a first direction;
[0024] A front device structure, located on the first main surface of the substrate along the first direction;
[0025] A back conductive layer is located on the second main surface of the substrate along the first direction.
[0026] In some embodiments, a thickness of the back conductive layer along the first direction is greater than or equal to 8 μm.
[0027] The semiconductor chip and the method for forming the same provided by the present invention, in the process of cutting the wafer to form the semiconductor chip, firstly use a cutting knife to cut at least a part of the wafer along the cutting path, and then use a laser to cut the back metal layer on the back side of the wafer, which not only avoids the problem of blade passivation caused by the cutting knife being easily wrapped by metal materials during the process of cutting the back metal layer, improves the cutting quality, avoids the problems of edge collapse and hidden cracks on the edge of the semiconductor chip formed after cutting, but also avoids the problems of blackening of the side of the semiconductor chip and thermal effect caused by laser cutting alone, improves the appearance and performance of the semiconductor chip, and improves the yield rate of semiconductor production. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 is a flow chart of a method for forming a semiconductor chip in a specific embodiment of the present invention;
[0029] Figure 2 is a schematic diagram of the structure of a wafer in a specific embodiment of the present invention;
[0030] Figure 3 is a schematic diagram of the structure after a cutting knife cuts at least a portion of a wafer in a specific embodiment of the present invention;
[0031] Figure 4 It is a schematic diagram of the structure after laser cutting of the back metal layer in a specific embodiment of the present invention. DETAILED DESCRIPTION
[0032] The specific implementation manner of the semiconductor chip and the method for forming the same provided by the present invention will be described in detail below with reference to the accompanying drawings.
[0033] This specific embodiment provides a method for forming a semiconductor chip. Figure 1 FIG. 1 is a flow chart of a method for forming a semiconductor chip in a specific embodiment of the present invention. Figure 1 As shown, the method for forming the semiconductor chip comprises the following steps:
[0034] Step S11, providing a wafer, the wafer comprising a front side and a back side relatively distributed along a first direction, forming a back side metal layer on the back side of the wafer, the front side of the wafer having a plurality of front side device structures arranged at intervals and a dicing path between two adjacent front side device structures;
[0035] Step S12, using a cutting knife to cut the wafer along the cutting path to form a first cutting groove extending into the interior of the wafer;
[0036] Step S13, using laser to cut the back metal layer along the first cutting groove to form a second cutting groove connected to the first cutting groove and penetrating the back metal layer along the first direction, the first cutting groove and the second cutting groove separate the wafer into multiple substrates and separate the back metal layer into multiple back conductive layers to form a semiconductor chip including the substrate, the front device structure located above the substrate, and the back conductive layer located below the substrate.
[0037] Figure 2 Schematic diagram of the structure of a wafer in a specific embodiment of the present invention. Figure 2 As shown, the specific steps of forming the back metal layer 21 on the back side of the wafer 20 include:
[0038] Any one of metal titanium, metal aluminum, metal nickel and metal silver, or a combination of two or more of them, is deposited on the back side of the wafer 20 by a physical vapor deposition process to form the back side metal layer 21 .
[0039] Specifically, the wafer 20 may be, but is not limited to, a silicon wafer. This specific embodiment takes the wafer 20 as a silicon wafer as an example for explanation. The wafer 20 includes the front side and the back side relatively distributed along the first direction D1, and the front side of the wafer 20 is covered with a device layer 22. The wafer 20 includes a plurality of device regions 201 arranged at intervals at least along the second direction D2 and the cutting road 202 located between two adjacent device regions 201. The device layer 22 includes a plurality of front device structures distributed one by one in the plurality of device regions 201 and a dielectric layer continuously covering the plurality of front device structures. Among them, the second direction D2 intersects the first direction D1 perpendicularly. The plurality described in this specific embodiment refers to more than two. Any one or a combination of two or more of metal titanium, metal aluminum, metal nickel and metal silver is deposited on the back side of the wafer 20 by a physical vapor deposition process in a physical deposition machine to form the back side metal layer 21.
[0040] In some embodiments, a thickness of the back metal layer 21 along the first direction D1 is greater than or equal to 8 μm.
[0041] Specifically, the thickness of the back metal layer 21 along the first direction D1 is adjusted by adjusting the deposition time, the dosage of the reaction gas and other parameters of the physical vapor deposition process to meet the process requirements of semiconductor chips with different functions.
[0042] In order to protect the back side of the back metal layer 21 (i.e., the surface of the back metal layer 21 away from the wafer 20 along the first direction D1), thereby facilitating the implementation of subsequent processes, in some embodiments, before the wafer 20 is cut along the cutting path 202 by using a cutting knife, the following steps are further included:
[0043] A protection film 23 is formed to cover the surface of the back metal layer 21 facing away from the wafer 20 .
[0044] Figure 3 Schematic diagram of the structure after the cutting knife cuts at least part of the wafer in a specific embodiment of the present invention. Figure 3 As shown, the width of the first cutting groove 31 is greater than or equal to 15 μm.
[0045] Specifically, the cutting knife cuts downward from the device layer 22 along the first direction D1 to form the first cutting groove 31 that penetrates the device layer 22 along the first direction D1 and extends at least to the inside of the wafer 20. The first cutting groove 31 separates the device layer 22 into a plurality of mutually independent front device structures. By setting the blade width of the cutting knife to be greater than or equal to 15 μm, the width of the first cutting groove 31 is greater than or equal to 15 μm. On the one hand, the width of the first cutting groove 31 (for example, the width along the second direction D2) is prevented from being too narrow, ensuring that the width of the first cutting groove 31 is wide enough so that the subsequent laser can smoothly and fully cut the back metal layer; on the other hand, in combination with the width of the cutting path 202, by setting the width of the first cutting groove 31 to be greater than or equal to 15 μm, the adjacent front device structures 30 can be fully separated.
[0046] In some embodiments, the specific steps of using a cutting knife to cut the wafer 20 along the cutting road 202 to form the first cutting groove 31 extending into the interior of the wafer 20 include:
[0047] Using a cutting knife to cut the wafer 20 along the cutting path 202 to form a first cutting groove 31 extending into the interior of the wafer 20, and the thickness of the wafer 20 remaining at the bottom of the first cutting groove 31 along the first direction D1 is greater than or equal to 3 μm; and / or
[0048] The wafer 20 is cut along the cutting path 202 by a cutting blade to form a first cutting groove 31 penetrating the wafer 20 along the first direction D1 and exposing the surface of the back metal layer 21 .
[0049] In one example, since the cutting accuracy of the wafer 20 using the cutting knife is less than 3μm, by controlling the cutting depth of the cutting knife, the thickness of the wafer 20 remaining at the bottom of the first cutting groove 31 along the first direction D1 is greater than or equal to 3μm, thereby further preventing the cutting knife from contacting the metal material in the back metal layer 21, thereby further preventing the metal material in the back metal layer 21 from wrapping the cutting knife.
[0050] In another example, the cutting accuracy of the cutting knife when cutting the wafer 20 can be improved by adjusting the cutting parameters of the cutting knife when cutting the wafer 20 or replacing a high-precision cutting knife, so that the cutting process of the cutting knife stops at the top surface of the back metal layer 21 (that is, the surface of the back metal layer 21 facing the wafer 20), and the first cutting groove 31 formed passes through the wafer 20 along the first direction D1, thereby shortening the subsequent laser cutting time, further reducing the thermal effect during the laser cutting process, and further reducing the problem of blackening of the side of the semiconductor chip formed after cutting.
[0051] Figure 4 Schematic diagram of the structure after laser cutting of the back metal layer in a specific embodiment of the present invention. Figure 4 As shown, the specific steps of using laser to cut the back metal layer 21 along the first cutting groove 31 to form a second cutting groove 40 that is connected to the first cutting groove 31 and penetrates the back metal layer 21 along the first direction D1 include:
[0052] The back metal layer 21 is cut along the first cutting groove 31 by using laser to form the second cutting groove 40 having a smaller width than the first cutting groove 21 .
[0053] In some embodiments, the specific steps of cutting the back metal layer 21 along the first cutting groove 31 using a laser include:
[0054] The back metal layer 21 is cut along the first cutting groove 31 by using a laser with a spot beam width of 3 μm to 7 μm.
[0055] Specifically, by using a laser with a spot beam width of 3 μm to 7 μm to cut the back metal layer 21 along the first cutting groove 31, the width of the formed second cutting groove 40 (for example, the width along the second direction D2) is smaller than the width of the first cutting groove 31 (for example, the width along the second direction D2), which can not only improve the cutting accuracy of the back metal layer 21, but also avoid damage to the front device structure and the wafer 20 during the laser cutting process. A plurality of the first cutting grooves 31 separate the device layer 22 into a plurality of the front device structures, a plurality of the first cutting grooves 31 (or a plurality of the first cutting grooves 31 and the second cutting grooves 40) separate the wafer 20 into a plurality of the substrates 41, and a plurality of the second cutting grooves 40 separate the back metal layer 21 into a plurality of the back conductive layers 42. The substrate 41, the front device structure 30 located on the substrate 41, and the back conductive layer 42 together constitute a semiconductor chip. After the laser cutting process is completed, the protective film 23 can be removed.
[0056] This specific embodiment also provides a semiconductor chip, which is formed by the semiconductor chip forming method as described above. Figure 1-Figure 4 The schematic diagram of the structure of the semiconductor chip can be found in Figure 4 .
[0057] like Figure 1-Figure 4 As shown, the semiconductor chip comprises:
[0058] A substrate 41, wherein the substrate 41 includes a first main surface and a second main surface that are oppositely distributed along a first direction D1;
[0059] A front device structure 30, located on the first main surface of the substrate 41 along the first direction D1;
[0060] The back conductive layer 42 is located on the second main surface of the substrate 41 along the first direction D1.
[0061] In some embodiments, a thickness of the back conductive layer 42 along the first direction D1 is greater than or equal to 8 μm.
[0062] The semiconductor chip and its formation method provided in this specific embodiment, in the process of cutting the wafer to form the semiconductor chip, first use a cutting knife to cut at least a part of the wafer along the cutting path, and then use a laser to cut the back metal layer on the back side of the wafer. This not only avoids the problem of blade passivation caused by the cutting knife being easily wrapped by metal materials during the process of cutting the back metal layer, improves the cutting quality, avoids the problems of edge collapse and hidden cracks at the edge of the semiconductor chip formed after cutting, but also avoids the problems of blackening of the side of the semiconductor chip and thermal effect caused by laser cutting alone, improves the appearance of the semiconductor chip and the performance of the semiconductor chip, and improves the yield of semiconductor production.
[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for forming a semiconductor chip, characterized in that: The steps include: A wafer is provided, the wafer comprising a front side and a back side which are relatively distributed along a first direction, a back side metal layer is formed on the back side of the wafer, and the front side of the wafer has a plurality of front side device structures which are arranged at intervals and a dicing path between two adjacent front side device structures; Using a cutting knife to cut the wafer along the cutting path to form a first cutting groove extending into the interior of the wafer; The back metal layer is cut along the first cutting groove by using a laser to form a second cutting groove connected to the first cutting groove and penetrating the back metal layer along the first direction. The first cutting groove and the second cutting groove separate the wafer into multiple substrates and separate the back metal layer into multiple back conductive layers to form a semiconductor chip including the substrate, the front device structure located above the substrate, and the back conductive layer located below the substrate.
2. The method for forming a semiconductor chip according to claim 1, wherein: The specific steps of forming a back metal layer on the back side of the wafer include: A physical vapor deposition process is used to deposit any one of metal titanium, metal aluminum, metal nickel and metal silver, or a combination of two or more of them, onto the back side of the wafer to form the back side metal layer.
3. The method for forming a semiconductor chip according to claim 1, wherein: The thickness of the back metal layer along the first direction is greater than or equal to 8 μm.
4. The method for forming a semiconductor chip according to claim 1, wherein: Before using a cutting knife to cut the wafer along the cutting path, the following steps are also included: A protection film is formed to cover the surface of the back metal layer facing away from the wafer.
5. The method for forming a semiconductor chip according to claim 1, wherein: The width of the first cutting groove is greater than or equal to 15 μm.
6. The method for forming a semiconductor chip according to claim 1, wherein: The specific steps of using a cutting knife to cut the wafer along the cutting path to form a first cutting groove extending into the interior of the wafer include: Using a cutting knife to cut the wafer along the cutting path to form a first cutting groove extending into the interior of the wafer, wherein the thickness of the wafer remaining at the bottom of the first cutting groove along the first direction is greater than or equal to 3 μm; and / or The wafer is cut along the cutting path using a cutting knife to form a first cutting groove that penetrates the wafer along the first direction and exposes the surface of the back metal layer.
7. The method for forming a semiconductor chip according to claim 1, wherein: The specific steps of using a laser to cut the back metal layer along the first cutting groove to form a second cutting groove that is connected to the first cutting groove and penetrates the back metal layer along the first direction include: The back metal layer is cut along the first cutting groove by using laser to form the second cutting groove having a width smaller than the first cutting groove.
8. The method for forming a semiconductor chip according to claim 1, wherein: The specific steps of cutting the back metal layer along the first cutting groove by using laser include: The back metal layer is cut along the first cutting groove by using a laser with a spot beam width of 3 μm to 7 μm.
9. A semiconductor chip, characterized in that: The semiconductor chip is formed by the method for forming a semiconductor chip according to claim 1; the semiconductor chip comprises: A substrate, the substrate comprising a first main surface and a second main surface that are oppositely distributed along a first direction; A front device structure, located on the first main surface of the substrate along the first direction; A back conductive layer is located on the second main surface of the substrate along the first direction.
10. The semiconductor chip according to claim 9, characterized in that The thickness of the back conductive layer along the first direction is greater than or equal to 8 μm.