A method for preparing a gently sloping wafer

Abstract

The present invention provides a method for fabricating a gently sloped wafer, comprising: S100, placing the gently sloped wafer in a groove of a first carrier plate with the back side of the gently sloped wafer facing upward. After performing ion implantation and high-temperature tempering processes on the back side of the gently sloped wafer, a metal layer is fabricated on the back side of the gently sloped wafer; S200, fabricating a first polyimide layer on the back side of the gently sloped wafer to make the back side of the gently sloped wafer reach a preset flatness; S300, flipping the first carrier plate and transferring the gently sloped wafer to a second carrier plate with the front side of the gently sloped wafer facing upward; S400, fabricating metal devices on the front side of the gently sloped wafer and a second polyimide layer on the front side of the gently sloped wafer, wherein the hollowed-out area of the second polyimide corresponds to the position of the cutting channel; S500, performing cutting on the gently sloped wafer with reference to the position of the cutting channel. According to the method for fabricating a gently sloped wafer provided by the present invention, the stability and the yield rate of processing the gently sloped wafer are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular, to a method for preparing a gently sloped wafer. Background Art

[0002] In the process of semiconductor element production, in some processes of wafer production, it is necessary to grind the wafer to reduce the thickness of the wafer to meet the requirements of subsequent processes. Common processes such as the Taiko thinning process will form a gently sloped edge on one side of the ground wafer, and the wafer is in a state where the center is thinner and the gently sloped edge is thicker.

[0003] When performing subsequent processes on the gently sloped wafer obtained by the above thinning process, when it is impossible to process the opposite side of the thinned grinding surface, because the side with the gently sloped edge needs to be turned downward, at this time, due to the existence of the gently sloped edge of the wafer, the position of the center of the wafer will be in a suspended state. Coupled with the fact that the wafer has undergone a thinning process to greatly reduce its thickness, the probability of rupture of the suspended part in the center of the wafer increases greatly, thereby resulting in a decrease in the yield of the wafer.

[0004] In addition, when processing a wafer prepared by a process such as the Taiko thinning process, when cutting the gently sloped edge of the wafer, problems such as wafer rupture caused by stress concentration due to uneven thickness at the edge and in the center of the wafer and rupture caused by collision between the cut gently sloped edge and the wafer in the center will also occur. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to improve the strength of the gently sloped wafer when processing the side without the gently sloped edge of the gently sloped wafer, improve the flatness and stability during processing of the gently sloped wafer, and effectively solve the problem of inconvenient cutting of the gently sloped edge of the wafer, and provide a method for preparing a gently sloped wafer.

[0006] According to the method for preparing a gently sloped wafer provided by the present invention, it includes:

[0007] S100, placing the gently sloped wafer in the groove of the first carrier plate, with the back of the gently sloped wafer facing upward. After completing the ion implantation and high-temperature tempering processes on the back of the wafer, a metal layer is prepared on the back of the gently sloped wafer;

[0008] S200, preparing a first polyimide layer on the back of the gently sloped wafer to make the back of the gently sloped wafer reach a preset flatness;

[0009] S300, flipping the first carrier plate, transferring the gently sloped wafer to the second carrier plate, with the front of the gently sloped wafer facing upward;

[0010] S400. Prepare the metal devices on the front side of the wafer and the second polyimide layer on the front side of the gently sloped wafer, where the hollowed-out area of the second polyimide corresponds to the position of the dicing lane.

[0011] S500. Dice the gently sloped wafer with reference to the position of the dicing lane.

[0012] According to the method for preparing a gently sloped wafer provided by the present invention, by pre-preparing the first polyimide layer on the back side of the gently sloped wafer, the flatness of the back side after flipping the gently sloped wafer is improved, and the problem of the center of the gently sloped wafer being suspended after flipping is also avoided. The probability of wafer breakage or cracking caused by the low strength of the center of the gently sloped wafer is reduced, and the flatness of the back side of the gently sloped wafer meets the process requirements, improving the stability of the wafer during processing of the gently sloped wafer.

[0013] According to some embodiments of the present invention, in S100, the implanted ions include: boron ions, phosphorus ions, and hydrogen ions, and the preset temperature range for activating the ions is 600 - 1000 °C.

[0014] In some embodiments of the present invention, in S400, the process for preparing the metal devices on the front side of the gently sloped wafer includes:

[0015] S410. Prepare metal blocks with a preset arrangement on the front side of the gently sloped wafer;

[0016] S420. Prepare the second polyimide layer on the front side of the gently sloped wafer;

[0017] S430. Electro-less plate Ni, Pd, and Au on the metal blocks without polarization.

[0018] According to some embodiments of the present invention, S500 includes:

[0019] S510. Use the selectivity ratio and adopt the plasma cutting process to cut the gently sloped wafer;

[0020] S520. Use the laser cutting process to cut off the metal layer on the back side of the gently sloped wafer;

[0021] S530. Cut off the first polyimide layer on the back side of the gently sloped wafer.

[0022] According to some embodiments of the present invention, the method further includes:

[0023] S600. Attach the front side of the diced gently sloped wafer to the first dicing mold frame;

[0024] S700. Remove the first polyimide layer on the back side of the gently sloped wafer.

[0025] According to some embodiments of the present invention, the method further includes:

[0026] S800, attaching the back surface of the sloped wafer from which the first polyimide layer has been removed to a second cutting die frame;

[0027] S900, removing the first cutting die frame.

[0028] According to some embodiments of the present invention, in S900, after irradiating the first cutting die frame with UV light for a preset duration, the first cutting die frame is removed.

[0029] According to some embodiments of the present invention, both the first carrier plate and the second carrier plate are glass carrier plates.

[0030] According to some embodiments of the present invention, the thickness range of the sloped wafer is: 50 - 200 um.

[0031] According to some embodiments of the present invention, the size range of the sloped wafer is from 6 inches to 12 inches. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flowchart of a method for preparing a sloped wafer according to an embodiment of the present invention;

[0033] Figure 2 is a schematic structural diagram of a sloped wafer obtained by step S100 of the method for preparing a sloped wafer according to an embodiment of the present invention;

[0034] Figure 3 is a schematic structural diagram of a sloped wafer obtained by step S200 of the method for preparing a sloped wafer according to an embodiment of the present invention;

[0035] Figure 4 is a schematic structural diagram of a sloped wafer obtained by step S300 of the method for preparing a sloped wafer according to an embodiment of the present invention;

[0036] Figure 5 is a schematic structural diagram of a sloped wafer obtained by step S400 of the method for preparing a sloped wafer according to an embodiment of the present invention;

[0037] Figure 6 is a schematic structural diagram of a sloped wafer obtained by step S400 of the method for preparing a sloped wafer according to an embodiment of the present invention;

[0038] Figure 7 is a schematic structural diagram of a sloped wafer obtained by step S400 of the method for preparing a sloped wafer according to an embodiment of the present invention;

[0039] Figure 8Schematic diagram of the stepped wafer obtained by step S500 of the stepped wafer preparation method according to an embodiment of the present invention;

[0040] Figure 9 Schematic diagram of the stepped wafer obtained by step S500 of the stepped wafer preparation method according to an embodiment of the present invention;

[0041] Figure 10 Schematic diagram of the stepped wafer before step S600 of the stepped wafer preparation method according to an embodiment of the present invention;

[0042] Figure 11 Schematic diagram of the second carrier removed after step S600 of the stepped wafer preparation method according to an embodiment of the present invention;

[0043] Figure 12 Schematic diagram of the stepped wafer obtained after step S600 of the stepped wafer preparation method according to an embodiment of the present invention;

[0044] Figure 13 Schematic diagram of the stepped wafer obtained by step S700 of the stepped wafer preparation method according to an embodiment of the present invention;

[0045] Figure 14 Schematic diagram of the stepped wafer obtained by step S800 of the stepped wafer preparation method according to an embodiment of the present invention;

[0046] Figure 15 Schematic diagram of the structure after etching or plasma ashing the second polyimide layer after step S600 of the stepped wafer preparation method according to an embodiment of the present invention.

[0047] Reference numerals:

[0048] Stepped wafer 1, metal layer 11, first polyimide layer 12, metal device 13, metal block 131, second polyimide layer 14,

[0049] First carrier 2,

[0050] Second carrier 3,

[0051] First cutting die frame 4,

[0052] Second cutting die frame 5. Detailed implementation manners

[0053] To further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose, the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0054] The present invention provides a stepped wafer preparation method, the method comprising:

[0055] S100, Place the gently sloped wafer 1 in the groove of the first carrier 2 with the back side of the gently sloped wafer 1 facing up. After completing the ion implantation and high-temperature tempering processes on the back side of the wafer, a metal layer 11 is prepared on the back side of the gently sloped wafer 1.

[0056] S200, Prepare a first polyimide layer 12 on the back side of the gently sloped wafer 1 to make the back side of the gently sloped wafer 1 reach a preset flatness.

[0057] S300, Flip the first carrier 2 and transfer the gently sloped wafer 1 to the second carrier 3 with the front side of the gently sloped wafer 1 facing up.

[0058] S400, Complete the preparation of the metal devices 13 on the front side of the gently sloped wafer 1 and the second polyimide layer 14 on the front side of the gently sloped wafer 1. The hollowed-out area of the second polyimide layer corresponds to the position of the scribe lane.

[0059] S500, Cut the gently sloped wafer 1 with reference to the position of the scribe lane.

[0060] According to the method for preparing a gently sloped wafer provided by the present invention, by pre-preparing the first polyimide layer 12 on the back side of the gently sloped wafer 1, the flatness of the back side after flipping the gently sloped wafer 1 is improved, and the problem of the center of the gently sloped wafer 1 being suspended after flipping is avoided. The probability of wafer breakage or cracking caused by the low strength of the center of the gently sloped wafer 1 is reduced, and the back side of the gently sloped wafer 1 meets the flatness requirements of the process, improving the stability of the wafer during processing of the gently sloped wafer 1. Thus, the technical problem in the prior art that the back side of the gently sloped wafer 1 cannot be processed is solved.

[0061] According to some embodiments of the present invention, in S100, the implanted ions include: boron ions, phosphorus ions, and hydrogen ions, and the preset temperature range for activating the ions is 600 - 1000 °C.

[0062] In some embodiments of the present invention, in S400, the process for preparing the metal devices 13 on the front side of the gently sloped wafer 1 includes:

[0063] S410, Prepare metal blocks 131 arranged in a preset pattern on the front side of the gently sloped wafer 1. Among them, the metal blocks 131 can be aluminum blocks (Al Pad), and the metal blocks 131 can be prepared by processes such as photolithography, electrochemical deposition, and growth processes.

[0064] S420, Prepare the second polyimide layer 14 on the front side of the gently sloped wafer 1.

[0065] S430, Electrolessly plate Ni, Pd, Au on the metal blocks 131 without electrode polarization.

[0066] According to some embodiments of the present invention, the S500 includes:

[0067] S510, using a selection ratio, adopting a plasma cutting process to cut the gently sloped wafer 1. Wherein, the hollowed-out area on the surface of the second polyimide layer 14 corresponds to the position of the cutting channel, so there is no need to prefabricate a cutting pattern on the surface of the second polyimide layer 14, and by using the selection ratio between the polyimide and the wafer, the wafer can be directly cut while the gently sloped wafer 1 still has the first polyimide layer 12.

[0068] S520, using a laser cutting process to cut off the metal layer 11 on the back of the wafer.

[0069] S530, cutting off the first polyimide layer on the back of the wafer.

[0070] Specifically, as Figures 8 - 9 shown, through steps S510 to S530, the gently sloped wafer 1 is cut into grains that are not connected to each other.

[0071] According to some embodiments of the present invention, the method further includes:

[0072] S600, attaching the front side of the cut gently sloped wafer 1 to the first cutting die frame 4.

[0073] S700, removing the first polyimide layer 12 on the back of the gently sloped wafer 1.

[0074] Wherein, as Figures 8 - 12 shown, since the gently sloped wafer 1 is fixed to the second carrier plate 3 through the second polyimide layer 14, through steps S510 to S530, without additional processing, the gently sloped edge of the gently sloped wafer 1 can be cut off and left on the second carrier plate 3 together with the cut-off second polyimide layer 14, without the need for a series of treatments on the gently sloped edge like the existing drum process wafers, improving the technical solution for cutting the gently sloped edge of the gently sloped wafer 1.

[0075] In addition, as Figure 15As shown, after step S600, through processes such as UV light irradiation, etching, or plasma ashing, part or all of the relatively thick second polyimide layer 12 at the edge of the sloped wafer 1 can be removed, which can reduce the adhesion force of the relatively thick second polyimide layer 12 at the edge of the sloped wafer 1 to the first cutting die frame 4, facilitating the removal of the second carrier plate 3 after step S600. And because the second polyimide layer 12 at the edge of the sloped wafer 1 is relatively thick, it will also be blocked by the relatively thick second polyimide layer 12 at the edge during the processes of etching or plasma ashing, thereby protecting the second polyimide layer 12 at the center from etching or plasma ashing.

[0076] According to some embodiments of the present invention, the method further includes:

[0077] S800, attaching the back surface of the sloped wafer 1 from which the first polyimide layer 12 has been removed to the second cutting die frame 5.

[0078] S900, removing the first cutting die frame 4.

[0079] According to some embodiments of the present invention, in S900, after irradiating the first cutting die frame 4 with UV light for a preset duration, the first cutting die frame 4 is removed.

[0080] According to some embodiments of the present invention, both the first carrier plate 2 and the second carrier plate 3 are glass carrier plates.

[0081] According to some embodiments of the present invention, the thickness range of the sloped wafer 1 is: 50 - 200 um.

[0082] According to some embodiments of the present invention, the size range of the sloped wafer 1 is from 6 inches to 12 inches.

[0083] In the present invention, the description of the method flow in the specification and the steps in the flowchart in the accompanying drawings of the present invention do not necessarily have to be strictly executed according to the step numbers. The method steps can change the execution order. Moreover, certain steps can be omitted, multiple steps can be combined into one step for execution, and / or one step can be decomposed into multiple steps for execution.

[0084] Through the description of the specific implementation manners, it should be possible to have a more in - depth and specific understanding of the technical means and effects adopted by the present invention to achieve the predetermined purpose. However, the attached drawings are only for reference and illustration, and are not used to limit the present invention.

Claims

1. A method for preparing a gently sloping wafer, characterized in that, Including: S100: Place the gently sloped wafer in the groove of the first carrier plate with the back side of the gently sloped wafer facing up. After completing the ion implantation and high-temperature tempering process on the back side of the wafer, prepare a metal layer on the back side of the gently sloped wafer. S200: Prepare a first polyimide layer on the back side of the gently sloped wafer to make the back side of the gently sloped wafer reach a preset flatness. S300: Flip the first carrier plate and transfer the gently sloped wafer to the second carrier plate with the front side of the gently sloped wafer facing up. S400: Complete the preparation of the metal devices and the second polyimide layer on the front side of the gently sloped wafer. The gently sloped wafer is fixed to the second carrier plate through the second polyimide layer, and the hollowed-out area of the second polyimide layer corresponds to the position of the cutting channel. S500: Cut the gently sloped wafer with reference to the position of the cutting channel. S600: Attach the front side of the cut gently sloped wafer to the first cutting die frame. S700: Remove the first polyimide layer on the back side of the gently sloped wafer.

2. The method for preparing a gently sloping wafer according to claim 1, wherein In S100, the implanted ions include boron ions, phosphorus ions, and hydrogen ions, and the preset temperature range for activating the ions is 600°C to 1000°C.

3. The method for preparing a gently sloping wafer according to claim 1, wherein In S400, the preparation process of the metal devices and the second polyimide layer on the front side of the gently sloped wafer includes: S410: Prepare metal blocks with a preset arrangement on the front side of the gently sloped wafer. S420: Prepare a second polyimide layer on the front side of the gently sloped wafer. S430: Electro-less plate Ni, Pd, and Au on the metal blocks without polarization.

4. The method for preparing a gently sloped wafer according to claim 1, wherein S500 includes: S510: Use the selectivity ratio and adopt the plasma cutting process to cut the gently sloped wafer; S520: Use the laser cutting process to cut off the metal layer on the back side of the gently sloped wafer. S530: Cut off the first polyimide layer on the back side of the gently sloped wafer.

5. The method for preparing a gently sloped wafer according to claim 1, wherein The method further includes: S800: Attach the back side of the gently sloped wafer from which the first polyimide layer has been removed to the second cutting die frame. S900: Remove the first cutting die frame.

6. The method for preparing a gently-sloped wafer according to claim 5, wherein, In S900, after irradiating the first cutting die frame with UV light for a preset duration, remove the first cutting die frame.

7. The method for preparing a gently sloped wafer according to claim 1, wherein Both the first carrier plate and the second carrier plate are glass carrier plates.

8. The method for preparing a gently-sloped wafer according to claim 1, wherein, The thickness range of the gently sloped wafer is 50um to 200um.

9. The method for preparing a gently sloped wafer according to any one of claims 1-8, characterized in that, The size range of the gently sloped wafer is from 6 inches to 12 inches.

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