Low-cost diamond spliced wafer-level radiator and preparation method thereof

Abstract

The invention belongs to the technical field of semiconductor materials, and particularly relates to a low-cost diamond spliced wafer-level radiator and a preparation method thereof, and the preparation method comprises the following steps: carrying out surface pretreatment on a diamond sheet; photoresist is spin-coated on the silicon wafer; transferring the diamond sheets subjected to surface pretreatment to a silicon wafer of which the surface is spin-coated with photoresist according to an array at a certain interval; sequentially growing a transition layer and an electroplating seed layer on the silicon wafer of which the surface comprises the diamond sheets arranged in an array manner through PVD (Physical Vapor Deposition); copper is electroplated on the surface of the electroplating seed layer, and gaps between the diamond sheets arranged in an array mode are completely filled; carrying out grinding and polishing treatment on the surface of the wafer subjected to the electro-coppering filling treatment; and dissolving the photoresist on the lower surface of the diamond through an organic solvent. According to the method, the small diamond pieces are spliced into the wafer in an electroplating splicing mode, and the cost is far lower than that of manufacturing wafer-level diamonds of the same size.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor materials, and in particular relates to a low-cost diamond splicing wafer-level heat sink and a preparation method thereof. Background Art

[0002] As the integration of microelectronic devices becomes higher and higher, the thermal management problems caused by high density are becoming more and more prominent. Therefore, how to solve the thermal management problem while ensuring the high density of integrated circuits has become a major problem. Diamond is considered to be an excellent heat dissipation material due to its ultra-high thermal conductivity (2000W / (m·K)), but the cost of using diamond for integrated circuit heat sinks is high, and the growth of diamond wafers is difficult and expensive. Therefore, there is currently a method of preparing diamond / copper composite materials as heat dissipation substrates. However, the high temperature and high pressure conditions required to prepare diamond / copper composite materials by traditional sintering are relatively harsh, so diamond particles can be spliced ​​together by electroplating at room temperature and pressure to form diamond / copper composite materials.

[0003] Since it is desired to prepare a diamond / copper composite material with high thermal conductivity, it is necessary to ensure that diamond and copper have a good contact interface in the process technology of electroplating the diamond / copper composite material to avoid gaps. For this reason, the industry generally uses metal layers or additives to improve the contact interface while ensuring that the contact interface has good thermal conductivity. For example, patent CN202211166517.9 "A copper-based diamond heat sink and its preparation method" is to surface copper-plated diamond powder and then dispersed into the electroplating solution for electroplating to obtain a diamond / copper composite material with a thermal conductivity of 400-700W / (m·K). Improving the contact interface by adding a metal layer or additives may cause interface reaction problems, resulting in changes in material properties. Additives may affect the thermal conductivity and electrical properties of the material. There are also surface flatness issues. The addition of a metal layer or additive may cause an uneven coating surface, reducing the appearance and mechanical properties of the composite material. There are also strength issues. Adding a metal layer or additive will affect the strength of the composite material, which can easily damage hard materials such as diamond. The added layer will make the strain at the interface more severe, which may cause cracking in the composite material. In addition, the addition of a metal layer or additive is more complicated to operate, and factors such as the type of additive, the amount of additive added, and the compatibility between the additive and the substrate need to be considered. The selection and processing of the added layer material requires stricter control.

[0004] Therefore, it is very necessary to develop a new low-cost diamond splicing wafer-level heat sink and its preparation method. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a low-cost diamond splicing wafer-level heat sink and a preparation method thereof. By growing a metal layer on a diamond sheet as a contact interface transition layer, a good diamond / copper bonding force is provided while ensuring a high thermal conductivity, thereby ultimately realizing the preparation of a wafer-level diamond / copper composite material heat dissipation substrate.

[0006] In order to achieve the above objectives, one of the technical solutions of the present invention is: a method for preparing a low-cost diamond spliced ​​wafer-level heat sink, comprising the following steps:

[0007] (1) Surface pretreatment of diamond sheet;

[0008] (2) Spin coating photoresist on silicon wafer;

[0009] (3) transferring the surface-pretreated diamond sheets to a silicon wafer with a photoresist spin-coated thereon in an array with a certain spacing;

[0010] (4) sequentially growing a transition layer and an electroplating seed layer on a silicon wafer having an array of diamond flakes on its surface by PVD;

[0011] (5) electroplating copper on the surface of the electroplating seed layer obtained in step (4) to completely fill the gaps between the diamond sheets arranged in an array;

[0012] (6) grinding and polishing the surface of the wafer after the copper electroplating treatment;

[0013] (7) Dissolve the photoresist on the lower surface of the diamond sheet using an organic solvent.

[0014] The transition layer, as a transition interface structure between the diamond sheet and the electroplating seed layer, not only improves the bonding force between the diamond sheet and the electroplating seed layer, but also improves the contact thermal conductivity between the diamond sheet and the electroplating seed layer.

[0015] In a preferred embodiment of the present invention, the spacing in step (3) is 1 μm-5 mm.

[0016] In a preferred embodiment of the present invention, the material of the transition layer in step (4) includes but is not limited to Ti, Cr, Zr, B, TiC, and TiN.

[0017] In a preferred embodiment of the present invention, the material of the electroplating seed layer in step (4) is Cu.

[0018] In a preferred embodiment of the present invention, the thickness of the transition layer in step (4) is 5 nm-5000 nm.

[0019] In a preferred embodiment of the present invention, the thickness of the electroplating seed layer in step (4) is 5 nm-5000 nm.

[0020] In a preferred embodiment of the present invention, the components of the electroplating solution in step (5) include 150-250 g / L of copper sulfate pentahydrate, 30-50 g / L of sulfuric acid, 30-50 mg / L of hydrochloric acid, 1-2 mg / L of accelerator SPS (sodium polydisulfide propane sulfonate), 200-400 mg / L of inhibitor PEG (polyethylene glycol), and 5-15 mg / L of leveler red tetrazolium.

[0021] In a preferred embodiment of the present invention, the thickness of the electroplated copper layer in step (5) is 1 μm-6 mm.

[0022] In a preferred embodiment of the present invention, the polishing process in step (6) is to polish the diamond surface to be flat and retain the surface copper layer or to polish the diamond surface until the diamond is exposed and remove the surface copper layer.

[0023] In order to achieve the above objectives, the second technical solution of the present invention is: a diamond spliced ​​wafer-level heat sink made by the above-mentioned preparation method of the low-cost diamond spliced ​​wafer-level heat sink.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention splices diamond chips into wafers by electroplating, and the cost is much lower than the cost of making wafer-level diamonds of the same size;

[0026] 2. The thermal conductivity of the diamond spliced ​​wafer-level heat sink prepared by the preparation method of the present invention is better than that of the wafer-level heat sink prepared by using diamond particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The process flow chart for preparing low-cost diamond spliced ​​wafer-level heat sink in Example 1-3;

[0028] Figure 2 Process flow chart for preparing low-cost diamond spliced ​​wafer-level heat sink in Example 4

[0029] Figure 3 This is a schematic diagram of the array arrangement of diamond sheets on a silicon wafer with photoresist spin-coated on the surface in Example 1;

[0030] Figure 4 This is a schematic diagram of the array arrangement of diamond sheets on a silicon wafer with photoresist spin-coated on the surface in Example 2;

[0031] Figure 5Schematic diagram of the array arrangement of diamond sheets on a silicon wafer with photoresist spin-coated on the surface in Example 3.

[0032] Figure 6 This is a schematic diagram of the array arrangement of diamond sheets on a silicon wafer with photoresist spin-coated on the surface in Example 4;

[0033] Figure 7 This is a physical picture of the diamond-stitched wafer-level heat sink in Example 4. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is described in more detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0035] A method for preparing a low-cost diamond spliced ​​wafer-level heat sink comprises the following steps:

[0036] (1) Surface pretreatment of diamond sheet;

[0037] (2) Spin coating photoresist on silicon wafer;

[0038] (3) transferring the surface-pretreated diamond sheets to a silicon wafer with a photoresist spin-coated thereon in an array with a certain spacing;

[0039] (4) sequentially growing a transition layer and an electroplating seed layer on a silicon wafer having an array of diamond flakes on its surface by PVD;

[0040] (5) electroplating copper on the surface of the electroplating seed layer obtained in step (4) to completely fill the gaps between the diamond sheets arranged in an array;

[0041] (6) grinding and polishing the surface of the wafer after the copper electroplating treatment;

[0042] (7) Dissolve the photoresist on the lower surface of the diamond sheet using an organic solvent.

[0043] In a preferred embodiment of the present invention, the spacing in step (3) is 1 μm-5 mm.

[0044] In a preferred embodiment of the present invention, the material of the transition layer in step (4) includes but is not limited to Ti, Cr, Zr, B, TiC, and TiN.

[0045] In a preferred embodiment of the present invention, the material of the electroplating seed layer in step (4) is Cu.

[0046] In a preferred embodiment of the present invention, the thickness of the transition layer in step (4) is 5 nm-5000 nm.

[0047] In a preferred embodiment of the present invention, the thickness of the electroplating seed layer in step (4) is 5 nm-5000 nm.

[0048] In a preferred embodiment of the present invention, the components of the electroplating solution in step (5) include 150-250 g / L of copper sulfate pentahydrate, 30-50 g / L of sulfuric acid, 30-50 mg / L of hydrochloric acid, 1-2 mg / L of accelerator SPS (sodium polydisulfide propane sulfonate), 200-400 mg / L of inhibitor PEG (polyethylene glycol), and 5-15 mg / L of leveler red tetrazolium.

[0049] In a preferred embodiment of the present invention, the thickness of the electroplated copper layer in step (5) is 1 μm-6 mm.

[0050] In a preferred embodiment of the present invention, the polishing process in step (6) is to polish the diamond surface to be flat and retain the surface copper layer or to polish the diamond surface until the diamond is exposed and remove the surface copper layer.

[0051] In order to achieve the above objectives, the second technical solution of the present invention is: a diamond spliced ​​wafer-level heat sink made by the above-mentioned preparation method of the low-cost diamond spliced ​​wafer-level heat sink.

[0052] Example 1

[0053] A low-cost diamond spliced ​​wafer-level heat sink is prepared by the following preparation method:

[0054] (1) Pre-treat a diamond sheet (10 mm*10 mm*0.5 mm) by washing it in aqua regia (concentrated nitric acid:concentrated hydrochloric acid=1:3);

[0055] (2) Take a 4-inch silicon wafer and spin-coat photoresist (AZ1500);

[0056] (3) The diamond sheets pretreated in step (1) are transferred to the silicon wafers spin-coated with photoresist in step (2) in an array with a spacing of 100 μm. The array is arranged as follows: Figure 1 ;

[0057] (4) using PVD to sequentially grow a transition layer Ti layer (thickness 200 nm) and an electroplating seed layer Cu layer (thickness 800 nm) on the above 4-inch wafer;

[0058] (5) Placing the sample on an electroplating machine and electroplating copper on the surface of the electroplating seed layer, the thickness of the electroplated copper layer is 500 μm, and the gaps between the diamond sheets arranged in an array are completely filled, so that the diamonds are spliced ​​together; the electroplating solution used includes the following components: 200 g / L copper sulfate pentahydrate, 40 g / L sulfuric acid, 40 mg / L hydrochloric acid, 1.5 mg / L accelerator SPS (sodium polydisulfide propane sulfonate), 300 mg / L inhibitor PEG (polyethylene glycol), and 10 mg / L leveling agent (red tetrazolium);

[0059] (6) Use CMP to grind the copper on the wafer surface after electroplating to make it smooth (retain the surface copper layer);

[0060] (7) Use NMP, acetone, and ethanol to dissolve the photoresist and remove the sample.

[0061] Example 2

[0062] A low-cost diamond spliced ​​wafer-level heat sink is prepared by the following preparation method:

[0063] (1) Pre-treat a diamond sheet (10 mm*10 mm*0.5 mm / 5 mm*5 mm*0.5 mm) by washing in aqua regia (concentrated nitric acid:concentrated hydrochloric acid=1:3);

[0064] (2) Take a 4-inch silicon wafer and spin-coat photoresist (AZ1500);

[0065] (3) Transfer the diamond sheets onto the photoresist in an array (spacing 200 μm) and arrange the array as follows: Figure 2 As shown;

[0066] (4) Using PVD to grow a transition layer Ti layer (200 nm) on a 4-inch wafer and electroplating a seed layer Cu layer (800 nm);

[0067] (5) Placing the sample on an electroplating machine and electroplating copper on the surface of the electroplating seed layer, the thickness of the electroplated copper layer is 500 μm, and the gaps between the diamond sheets arranged in an array are completely filled, so that the diamonds are spliced ​​together; the electroplating solution used includes the following components: 200 g / L copper sulfate pentahydrate, 40 g / L sulfuric acid, 40 mg / L hydrochloric acid, 1.5 mg / L accelerator SPS (sodium polydisulfide propane sulfonate), 300 mg / L inhibitor PEG (polyethylene glycol), and 10 mg / L leveling agent (red tetrazolium);

[0068] (6) Use CMP to grind the copper on the wafer surface after electroplating to make it smooth (retain the surface copper layer);

[0069] (7) Use NMP, acetone, and ethanol to dissolve the photoresist and remove the sample.

[0070] Example 3

[0071] A low-cost diamond spliced ​​wafer-level heat sink is prepared by the following preparation method:

[0072] (1) Pre-treat a diamond sheet (10 mm*10 mm*0.5 mm) by washing it in aqua regia (concentrated nitric acid:concentrated hydrochloric acid=1:3);

[0073] (2) Spin-coat photoresist (AZ1500) on a 12-inch silicon wafer;

[0074] (3) Transfer the diamond sheets onto the photoresist in an array (spacing 200 μm) and arrange the array as follows: Figure 3 As shown;

[0075] (4) Using PVD to grow a transition layer Ti layer (200 nm) on a 12-inch wafer and electroplating a seed layer Cu layer (800 nm);

[0076] (5) Placing the sample on an electroplating machine and electroplating copper on the surface of the electroplating seed layer, the thickness of the electroplated copper layer is 500 μm, and the gaps between the diamond sheets arranged in an array are completely filled, so that the diamonds are spliced ​​together; the electroplating solution used includes the following components: 200 g / L copper sulfate pentahydrate, 40 g / L sulfuric acid, 40 mg / L hydrochloric acid, 1.5 mg / L accelerator SPS (sodium polydisulfide propane sulfonate), 300 mg / L inhibitor PEG (polyethylene glycol), and 10 mg / L leveling agent (red tetrazolium);

[0077] (6) Use CMP to grind the copper on the wafer surface after electroplating to make it smooth (retain the surface copper layer);

[0078] (7) Use NMP, acetone, and ethanol to dissolve the photoresist and remove the sample.

[0079] Example 4

[0080] A low-cost diamond spliced ​​wafer-level heat sink is prepared by the following preparation method:

[0081] (1) Pre-treat a diamond sheet (10 mm*10 mm*0.5 mm) by washing it in aqua regia (concentrated nitric acid:concentrated hydrochloric acid=1:3);

[0082] (2) Take a 30mm*30mm silicon wafer and spin-coat it with photoresist (AZ1500);

[0083] (3) Transfer the diamond sheets onto the photoresist in an array (spacing 300 μm) and arrange the array as follows: Figure 4 As shown;

[0084] (4) Using PVD to grow a transition layer Ti layer (200 nm) on a 30 mm*30 mm silicon wafer and electroplating a seed layer Cu layer (800 nm);

[0085] (5) Placing the sample on an electroplating machine and electroplating copper on the surface of the electroplating seed layer, the thickness of the electroplated copper layer is 600 μm, and the gaps between the diamond sheets arranged in an array are completely filled, so that the diamonds are spliced ​​together; the electroplating solution used includes the following components: 200 g / L copper sulfate pentahydrate, 40 g / L sulfuric acid, 40 mg / L hydrochloric acid, 1.5 mg / L accelerator SPS (sodium polydisulfide propane sulfonate), 300 mg / L inhibitor PEG (polyethylene glycol), and 10 mg / L leveling agent (red tetrazolium);

[0086] (6) Use CMP to polish the copper on the wafer surface after electroplating until the diamond is exposed (without retaining the surface copper layer);

[0087] (7) Use NMP, acetone, and ethanol to dissolve the photoresist and remove the sample.

[0088] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a low-cost diamond spliced ​​wafer-level heat sink, characterized in that: The following steps are involved: (1) Surface pretreatment of diamond sheet; (2) Spin coating photoresist on silicon wafer; (3) transferring the surface-pretreated diamond sheets to a silicon wafer with a photoresist spin-coated thereon in an array with a certain spacing; (4) sequentially growing a transition layer and an electroplating seed layer on a silicon wafer having an array of diamond flakes on its surface by PVD; (5) electroplating copper on the surface of the electroplating seed layer obtained in step (4) to completely fill the gaps between the diamond sheets arranged in an array; (6) grinding and polishing the surface of the wafer after the copper electroplating treatment; (7) Dissolve the photoresist on the lower surface of the diamond sheet using an organic solvent.

2. The method for preparing a low-cost diamond spliced ​​wafer-level heat sink according to claim 1, characterized in that: The spacing in step (3) is 1 μm-5 mm.

3. The method for preparing a low-cost diamond spliced ​​wafer-level heat sink according to claim 1, characterized in that: The material of the transition layer in step (4) includes but is not limited to Ti, Cr, Zr, B, TiC, and TiN.

4. The low-cost diamond-bonded wafer-level heat sink according to claim 1, characterized in that: The material of the electroplating seed layer in step (4) is Cu.

5. The method for preparing a low-cost diamond spliced ​​wafer-level heat sink according to claim 1, characterized in that: The thickness of the transition layer in step (4) is 5nm-5000nm.

6. The method for preparing a low-cost diamond spliced ​​wafer-level heat sink according to claim 1, characterized in that: The thickness of the electroplating seed layer in step (4) is 5nm-5000nm.

7. The method for preparing a low-cost diamond spliced ​​wafer-level heat sink according to claim 1, characterized in that: The components of the electroplating solution in step (5) include 150-250 g / L of copper sulfate pentahydrate, 30-50 g / L of sulfuric acid, 30-50 mg / L of hydrochloric acid, 1-2 mg / L of accelerator sodium polydisulfide dipropane sulfonate, 200-400 mg / L of inhibitor polyethylene glycol, and 5-15 mg / L of leveling agent red tetrazolium.

8. The method for preparing a low-cost diamond spliced ​​wafer-level heat sink according to claim 1, characterized in that: The thickness of the electroplated copper layer in step (5) is 1 μm-6 mm.

9. The method for preparing a low-cost diamond spliced ​​wafer-level heat sink according to claim 1, characterized in that: The polishing process in step (6) is to polish the diamond surface to be flat and retain the surface copper layer or to polish the diamond surface until the diamond is exposed and remove the surface copper layer.

10. A diamond-jointed wafer-level heat sink made by the method for making a low-cost diamond-jointed wafer-level heat sink as claimed in any one of claims 1 to 9.

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