A method for splitting silicon carbide wafer
By depositing the second ILD layer and polyimide on the silicon carbide wafer, forming metal contact points and cutting channels, combining invisible laser cutting and film expansion lobe technology, the large cutting loss and production efficiency in the silicon carbide wafer lobe method are solved. The problem of low efficiency and low loss silicon carbide wafer separation is achieved.
Patent Information
- Application Number
- CN202211118659.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-13
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2042-09-13
AI Technical Summary
The existing silicon carbide wafer lobe methods have problems of large cutting losses and low production efficiency, making it difficult to quickly complete subsequent processing.
The second ILD layer and polyimide are deposited using the LCPVD process to form metal contact points and cutting channels. Through invisible laser cutting and film expansion lobe technology, low-loss lobes and efficient separation of silicon carbide wafers are achieved.
The lobe efficiency of the silicon carbide wafer is improved, cutting losses are reduced, and there is no need to process each grain separately, which improves production efficiency.
Smart Images
Figure CN115458399B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of silicon carbide wafer processing, and in particular to a method for splitting a silicon carbide wafer. Background Art
[0002] Silicon carbide wafer, also known as silicon carbide single crystal sheet, is a sheet-like single crystal material obtained by cutting, grinding and polishing silicon carbide crystals along a specific crystal direction.
[0003] In silicon carbide wafer processing, during the manufacturing process of semiconductor devices, after the wafer growth is completed, the wafer needs to be divided into several grains for the subsequent chip packaging process.
[0004] In the prior art, silicon carbide wafers are usually split directly by laser cutting, which not only produces large cutting losses, but also requires each silicon carbide grain cut subsequently to undergo a separate process, resulting in low production efficiency and inconvenience in quickly completing the processing of silicon carbide wafers. Summary of the invention
[0005] The object of the present invention is to provide a method for splitting a silicon carbide wafer to solve the problems raised in the above background technology.
[0006] The purpose of the present invention can be achieved through the following technical solutions:
[0007] A method for splitting a silicon carbide wafer comprises the following steps:
[0008] S1. Take a silicon carbide wafer that has completed the first half of the process, attach the back of the silicon carbide wafer to a glass carrier with air holes, use a vacuum device to evacuate air from the bottom of the glass carrier, vacuum-adsorb the silicon carbide wafer onto the glass carrier, and then use the LCPVD process to deposit a second ILD layer on the silicon carbide wafer. Finally, stop evacuating the air from the vacuum device and remove the vacuum device.
[0009] S2, for the silicon carbide wafer obtained in step S1, coating a photoresist on the surface of the second ILD layer, and then etching, etching a contact hole on the front side of the silicon carbide wafer, then cleaning the photoresist and etching residue, and then depositing metal aluminum in the contact hole;
[0010] S3, for the silicon carbide wafer obtained in step S2, using the LPCVD process to deposit polyimide on the front side of the silicon carbide wafer, and then etching contact points on the front side of the silicon carbide wafer above the metal aluminum, and finally using a coating process to plate nickel-palladium-gold on the metal aluminum to form metal contact points;
[0011] S4, for the silicon carbide wafer obtained in step S3, coating photoresist again, exposing and developing, and etching polyimide to form a cutting path, using a laser to invisible cut the silicon carbide wafer along the cutting path, and using laser cutting to cut off the metal layer on the back of the silicon carbide wafer along the cutting path, and then using laser cutting to cut off the polyimide at the edge of the silicon carbide wafer, and finally using a vacuum device to evacuate air under the glass carrier, and vacuum adsorb the silicon carbide wafer on the glass carrier;
[0012] S5. For the silicon carbide wafer obtained in step S4, first flip the silicon carbide wafer and the glass carrier, attach the silicon carbide wafer to the cutting mold frame, and then cut off the edge of the silicon carbide wafer and the second ILD layer located at the edge of the silicon carbide wafer by laser cutting, and then use film expansion to split the silicon carbide wafer along the cutting path to separate it into multiple silicon carbide grains, thereby completing the splitting of the silicon carbide wafer.
[0013] Preferably, in step S1, the front half support of the silicon carbide wafer includes a front process and a back process, the front process of the silicon carbide wafer includes transistor manufacturing, front ion implantation, high temperature annealing and first ILD layer manufacturing, and the back support of the silicon carbide wafer includes grinding and thinning, metal layer deposition, back ion implantation and high temperature annealing.
[0014] Preferably, in step S1, depositing a second ILD layer on the silicon carbide wafer by using the LCPVD process will cover the front and edge of the silicon carbide wafer and the surface of the glass carrier to fix the silicon carbide wafer on the glass carrier.
[0015] Preferably, in step S2, the process of depositing metal aluminum in the contact hole is: after completing the cleaning of the photoresist and etching residues, the metal aluminum is deposited on the front side of the silicon carbide wafer by chemical vapor deposition, and the deposited metal aluminum is deposited inside the contact hole and on the surface of the second ILD layer, and then the metal aluminum on the surface of the second ILD layer is etched away by coating photoresist and exposing and developing, and then the photoresist is removed.
[0016] Preferably, in step S3, the process of etching a contact point on the front side of the silicon carbide wafer above the contact hole is: coating photoresist on the front side of the silicon carbide wafer, then etching out the contact point through exposure and development, and removing the photoresist after etching the contact point.
[0017] Preferably, in step S4, when the polyimide at the edge of the silicon carbide wafer is cut off by laser, the polyimide at the edge of the silicon carbide wafer can also be removed by solvent etching.
[0018] Preferably, in step S5, after the front side of the silicon carbide wafer is attached to the cutting mold frame, the vacuum device is stopped and the vacuum device and the glass carrier are removed. When the silicon carbide wafer is attached to the cutting mold frame, the metal contact point on the front side of the silicon carbide wafer is the contact surface between the silicon carbide wafer and the supporting film frame.
[0019] Beneficial effects of the present invention:
[0020] The second ILD layer deposited on the first ILD layer can, in the subsequent process, on the one hand, provide fixation for the silicon carbide wafer, and on the other hand, provide protection for the first ILD layer to avoid damage to the first ILD layer in the subsequent process, which is convenient for the production of contact holes. The deposited polyimide can then facilitate the production of metal connection points, thereby facilitating the rapid completion of the production of silicon carbide wafers.
[0021] After the production of the metal connection points on the front side of the silicon carbide wafer is completed, the polyimide, the first ILD layer and the second IDL layer are separated by the cutting path etched in step S4, and the silicon carbide wafer is cut by laser shadow invisible cutting, so that the silicon carbide wafers are easy to separate, and finally the laser is focused along the cutting path to cut the metal on the back side of the silicon carbide wafer to separate the metal, and finally in step S6, the tension of the cutting mold frame in the film expansion splitting is used to make the wafer split along the cutting path, and the silicon carbide wafer is separated into a plurality of silicon carbide wafers on which the contact holes and the metal connection points have been completed. There is no need to process each silicon carbide wafer one by one after the splitting is completed, which effectively improves the production efficiency, and the invisible laser cutting is performed when the silicon carbide wafer is cut, which can reduce the loss generated during the splitting. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art description are briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative work.
[0023] Figure 1 is a schematic flow chart of step S1 of the present invention;
[0024] Figure 2 is a schematic flow chart of step S2 of the present invention;
[0025] Figure 3 It is a schematic diagram of the process of step S3 of the present invention;
[0026] Figure 4 is a schematic flow chart of step S4 of the present invention;
[0027] Figure 5is a schematic flow chart of step S5 of the present invention;
[0028] Figure 6 It is a schematic diagram of the process of depositing metal aluminum in step S2 of the present invention.
[0029] The reference numerals in the figures are as follows:
[0030] 1. Silicon carbide wafer, 2. First ILD layer, 3. Metal layer, 4. Glass carrier, 5. Air holes, 6. Exhaust equipment, 7. Second ILD layer, 8. Photoresist, 9. Contact holes, 10. Metal aluminum, 11. Polyimide, 12. Metal contact points, 13. Cutting lanes, 14. Cutting mold frame, 15. Silicon carbide grains. DETAILED DESCRIPTION
[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0032] A method for splitting a silicon carbide wafer comprises the following steps:
[0033] S1. Take a silicon carbide wafer that has completed the first half of the process, attach the back of the silicon carbide wafer to a glass carrier with air holes, use a vacuum device to evacuate air from the bottom of the glass carrier, vacuum-adsorb the silicon carbide wafer onto the glass carrier, and then use the LCPVD process to deposit a second ILD layer on the silicon carbide wafer. Finally, stop evacuating the air from the vacuum device and remove the vacuum device.
[0034] S2, for the silicon carbide wafer obtained in step S1, coating a photoresist on the surface of the second ILD layer, and then etching, etching a contact hole on the front side of the silicon carbide wafer, then cleaning the photoresist and etching residue, and then depositing metal aluminum in the contact hole;
[0035] S3, for the silicon carbide wafer obtained in step S2, using the LPCVD process to deposit polyimide on the front side of the silicon carbide wafer, and then etching contact points on the front side of the silicon carbide wafer above the metal aluminum, and finally using a coating process to plate nickel-palladium-gold on the metal aluminum to form metal contact points;
[0036] S4, for the silicon carbide wafer obtained in step S3, coating photoresist again, exposing and developing, and etching polyimide to form a cutting path, using a laser to invisible cut the silicon carbide wafer along the cutting path, and using laser cutting to cut off the metal layer on the back of the silicon carbide wafer along the cutting path, and then using laser cutting to cut off the polyimide at the edge of the silicon carbide wafer, and finally using a vacuum device to evacuate air under the glass carrier, and vacuum adsorb the silicon carbide wafer on the glass carrier;
[0037] S5. For the silicon carbide wafer obtained in step S4, first flip the silicon carbide wafer and the glass carrier, attach the silicon carbide wafer to the cutting mold frame, and then cut off the edge of the silicon carbide wafer and the second ILD layer located at the edge of the silicon carbide wafer by laser cutting, and then use film expansion to split the silicon carbide wafer along the cutting path to separate it into multiple silicon carbide grains, thereby completing the splitting of the silicon carbide wafer.
[0038] In step S1, the front half support of the silicon carbide wafer includes front process and back process. The front process of the silicon carbide wafer includes transistor production, front ion implantation, high temperature annealing and first ILD layer production. The back support of the silicon carbide wafer includes grinding and thinning, metal layer deposition, back ion implantation and high temperature annealing.
[0039] In step S1, a second ILD layer is deposited on the silicon carbide wafer by using the LCPVD process to cover the front side and edge of the silicon carbide wafer and the surface of the glass carrier, so as to fix the silicon carbide wafer on the glass carrier.
[0040] By covering the front side and edge of the silicon carbide wafer and the surface of the glass carrier, the glass carrier and the silicon carbide wafer can be fixed.
[0041] In step S2, the process of depositing metal aluminum in the contact hole is as follows: after cleaning the photoresist and etching residues, metal aluminum is deposited on the front side of the silicon carbide wafer by chemical vapor deposition. The deposited metal aluminum will be deposited inside the contact hole and on the surface of the second ILD layer. Then, the metal aluminum on the surface of the second ILD layer is etched away by coating photoresist and exposing and developing, and then the photoresist is removed.
[0042] like Figure 6 The deposited metal aluminum is deposited on the entire front side of the silicon carbide wafer instead of directly depositing it inside the contact hole. The photoresist is located above the contact hole and is blocked by the photoresist during etching. The metal aluminum above the contact hole will not be etched, so that after removing the photoresist, part of the metal aluminum protrudes outside the contact hole, which is convenient for the subsequent production of metal connection points.
[0043] In step S3, the process of etching a contact point on the front side of the silicon carbide wafer above the contact hole is as follows: coating photoresist on the front side of the silicon carbide wafer, etching out the contact point through exposure and development, and removing the photoresist after etching the contact point.
[0044] No photoresist is coated on the metal aluminum so that the polyimide 11 on the metal aluminum can be directly etched away, which facilitates the formation of metal connection points by the coating process on the metal aluminum. The metal connection points protrude from the outside of the polyimide 11, and there is polyimide between the metal connection points to avoid contact between the metal connection points.
[0045] In the step S4, when the polyimide at the edge of the silicon carbide wafer is cut off by laser, the polyimide at the edge of the silicon carbide wafer can also be removed by solvent etching.
[0046] In the step S5, after the front side of the silicon carbide wafer is attached to the cutting mold frame, the vacuum device is stopped and the vacuum device and the glass carrier are removed. When the silicon carbide wafer is attached to the cutting mold frame, the metal contact point on the front side of the silicon carbide wafer is the contact surface between the silicon carbide wafer and the supporting film frame.
[0047] like Figure 4 and Figure 5 Since in step S4, the metal layer is located on the back side of the silicon carbide wafer, the silicon carbide wafer can be adsorbed onto the glass carrier by vacuuming the silicon carbide wafer through the vacuum equipment. In step S5, when the vacuum equipment is stopped, the glass carrier can be directly removed from the silicon carbide wafer.
[0048] Compared with the related art, the method for splitting a silicon carbide wafer provided by the present invention has the following beneficial effects:
[0049] The second ILD layer deposited on the first ILD layer can, in the subsequent process, on the one hand, provide fixation for the silicon carbide wafer, and on the other hand, provide protection for the first ILD layer to avoid damage to the first ILD layer in the subsequent process, which is convenient for the production of contact holes. The deposited polyimide can then facilitate the production of metal connection points, thereby facilitating the rapid completion of the production of silicon carbide wafers.
[0050] After the production of the metal connection points on the front side of the silicon carbide wafer is completed, the polyimide, the first ILD layer and the second IDL layer are separated by the cutting path etched in step S4, and the silicon carbide wafer is cut by laser shadow invisible cutting, so that the silicon carbide wafers are easy to separate, and finally the laser is focused along the cutting path to cut the metal on the back side of the silicon carbide wafer to separate the metal, and finally in step S6, the tension of the cutting mold frame in the film expansion splitting is used to make the wafer split along the cutting path, and the silicon carbide wafer is separated into a plurality of silicon carbide wafers on which the contact holes and the metal connection points have been completed. There is no need to process each silicon carbide wafer one by one after the splitting is completed, which effectively improves the production efficiency, and the invisible laser cutting is performed when the silicon carbide wafer is cut, which can reduce the loss generated during the splitting.
[0051] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.
Claims
1. A method for splitting a silicon carbide wafer, characterized in that: The following steps are involved: S1. Take a silicon carbide wafer that has completed the first half of the process, attach the back of the silicon carbide wafer to a glass carrier with air holes, use a vacuum device to evacuate air from the bottom of the glass carrier, vacuum-adsorb the silicon carbide wafer onto the glass carrier, and then use the LCPVD process to deposit a second ILD layer on the silicon carbide wafer. Finally, stop evacuating the air from the vacuum device and remove the vacuum device. S2, for the silicon carbide wafer obtained in step S1, coating a photoresist on the surface of the second ILD layer, and then etching, etching a contact hole on the front side of the silicon carbide wafer, then cleaning the photoresist and etching residue, and then depositing metal aluminum in the contact hole; S3, for the silicon carbide wafer obtained in step S2, using the LPCVD process to deposit polyimide on the front side of the silicon carbide wafer, and then etching contact points on the front side of the silicon carbide wafer above the metal aluminum, and finally using a coating process to plate nickel-palladium-gold on the metal aluminum to form metal contact points; The process of etching the contact point at the position above the contact hole on the front side of the silicon carbide wafer is as follows: coating the front side of the silicon carbide wafer with a photoresist, then etching out the contact point through exposure and development, and removing the photoresist after etching out the contact point; S4, for the silicon carbide wafer obtained in step S3, coating photoresist again, exposing and developing, and etching polyimide to form a cutting path, using a laser to invisible cut the silicon carbide wafer along the cutting path, and using laser cutting to cut off the metal layer on the back of the silicon carbide wafer along the cutting path, and then using laser cutting to cut off the polyimide at the edge of the silicon carbide wafer, and finally using a vacuum device to evacuate air under the glass carrier, and vacuum adsorb the silicon carbide wafer on the glass carrier; S5. For the silicon carbide wafer obtained in step S4, first flip the silicon carbide wafer and the glass carrier, attach the silicon carbide wafer to the cutting mold frame, and then cut off the edge of the silicon carbide wafer and the second ILD layer located at the edge of the silicon carbide wafer by laser cutting, and then use film expansion to split the silicon carbide wafer along the cutting path to separate it into multiple silicon carbide grains, thereby completing the splitting of the silicon carbide wafer.
2. A method for splitting a silicon carbide wafer according to claim 1, characterized in that: In step S1, the front half support of the silicon carbide wafer includes front process and back process. The front process of the silicon carbide wafer includes transistor production, front ion implantation, high temperature annealing and first ILD layer production. The back support of the silicon carbide wafer includes grinding and thinning, metal layer deposition, back ion implantation and high temperature annealing.
3. The method for splitting a silicon carbide wafer according to claim 1, characterized in that: In step S1, a second ILD layer is deposited on the silicon carbide wafer by using the LCPVD process to cover the front side and edge of the silicon carbide wafer and the surface of the glass carrier, so as to fix the silicon carbide wafer on the glass carrier.
4. The method for splitting a silicon carbide wafer according to claim 1, characterized in that: In step S2, the process of depositing metal aluminum in the contact hole is as follows: after cleaning the photoresist and etching residues, metal aluminum is deposited on the front side of the silicon carbide wafer by chemical vapor deposition. The deposited metal aluminum will be deposited inside the contact hole and on the surface of the second ILD layer. Then, the metal aluminum on the surface of the second ILD layer is etched away by coating photoresist and exposing and developing, and then the photoresist is removed.
5. The method for splitting a silicon carbide wafer according to claim 1, characterized in that: In the step S4, when the polyimide at the edge of the silicon carbide wafer is cut off by laser, the polyimide at the edge of the silicon carbide wafer is removed by solvent etching.
6. The method for splitting a silicon carbide wafer according to claim 1, characterized in that: In step S5, after the front side of the silicon carbide wafer is attached to the cutting mold frame, the vacuum device is stopped and the vacuum device and the glass carrier are removed. When the silicon carbide wafer is attached to the cutting mold frame, the metal contact point on the front side of the silicon carbide wafer is the contact surface between the silicon carbide wafer and the supporting film frame.