A method and tooling for micro-hole machining and slag cleaning of aluminum nitride substrates

Abstract

The present invention discloses a method and tooling for micro-hole processing and slag cleaning of aluminum nitride substrates, which relates to the technical field of semiconductor substrate processing. In the first aspect, there is a method for micro-hole processing and slag cleaning of aluminum nitride substrates. In the second aspect, there is a tooling for cleaning the slag of micro-holes on aluminum nitride substrates, which includes a cleaning tank. Inside the cleaning tank, there are two clamping bowls symmetrically arranged on the front and rear sides of the substrate. The clamping bowls are used to clamp the substrate and form a cavity communicating with the cleaning tank with the substrate. Each clamping bowl is connected with a pushing device for pushing the clamping bowl to clamp the substrate by the two clamping bowls; inside each clamping bowl, there is an elastic bowl. The clamping bowl is provided with a push rod connected to the elastic bowl through it. The push rod penetrates through the cleaning tank and is connected to a driving device outside the cleaning tank. The present invention can effectively clean the micro-holes on the aluminum nitride substrate and improve the yield rate of subsequent metalized holes.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor substrate processing, and particularly relates to a method and tooling for micro-hole processing and slag cleaning of aluminum nitride substrates. Background Art

[0002] Aluminum nitride substrates are widely used in high-power electronic devices due to their high thermal conductivity, low dielectric loss and other characteristics.

[0003] The existing technology for processing aluminum nitride substrates is as follows:

[0004] S1. Select an aluminum nitride substrate with a thickness of 0.2 mm;

[0005] S2. Adopt a cleaning process to remove substances such as organic matter on the surface;

[0006] S3. Use a laser to drill micro-holes with a diameter of 0.1 mm in the aluminum nitride substrate;

[0007] S4. Clean the micro-holes for the second time;

[0008] S5. Metalize the holes process.

[0009] When processing the aluminum nitride substrate by this processing method, since the diameter of the micro-holes drilled by the laser in step S3 is small, the vaporized aluminum nitride cannot be effectively discharged in step S4, so that the vaporized aluminum nitride is easily solidified on the hole wall, and thus protruding slag is formed on the hole wall. The micro-holes cannot be cleaned by physical friction cleaning. Generally, solution soaking and ultrasonic cleaning are used, resulting in incomplete cleaning and affecting the yield of subsequent metalized hole formation. Summary of the Invention

[0010] The purpose of the present invention is to provide a method and tooling for micro-hole processing and slag cleaning of aluminum nitride substrates, which can effectively clean the micro-holes on the aluminum nitride substrates and improve the yield of subsequent metalized hole formation.

[0011] To solve the above technical problems, the present invention adopts the following solutions:

[0012] In a first aspect, a method for micro-hole processing and slag cleaning of an aluminum nitride substrate includes the following steps:

[0013] Step S1. Select an aluminum nitride substrate with a thickness of 0.3 mm;

[0014] Step S2. Use a laser to process micro-holes with a diameter of 0.1 mm on the substrate;

[0015] Step S3. Place the substrate in a slag cleaning tooling, soak it with a 1:1 potassium hydroxide-hydrogen peroxide mixed solution or a 2:1 sulfuric acid-hydrogen peroxide mixed solution, and simultaneously apply ultrasonic cleaning;

[0016] Step S4: Precision polish the substrate until the substrate thickness is 0.2 mm and restore the surface roughness to that before immersion cleaning;

[0017] Step S5: Perform final cleaning with an organic solvent. Its function is that by using a substrate with a thickness greater than 0.2 mm for laser processing, and then immersing and cleaning the substrate with an acidic solution or an alkaline solution, the slag in the micropores can be effectively removed. And because using an acidic solution or an alkaline solution will increase the surface roughness of the substrate, by precision polishing, while reducing the surface roughness of the substrate, the excess thickness of the substrate is removed so that the substrate can reach the predetermined thickness (0.2 mm), thus an aluminum nitride substrate with a predetermined thickness, a predetermined roughness and completely cleaned micropores can be obtained. Further, further cleaning the substrate with an acidic solution and an alkaline solution can slightly increase the roughness of the micropores, which is beneficial to the subsequent electroplating process.

[0018] Further, it further includes the following steps:

[0019] Step S3a: In the slag cleaning tooling in Step S3, the elastic bowls on both sides of the micropore are cyclically extruded successively to make the solution flow back and forth in the micropore to accelerate the removal of slag.

[0020] In Step S3a, the extrusion frequency of the elastic bowl is 5 times / minute - 20 times / minute, and the generated pressure difference is 0.1 MPa - 0.5 MPa.

[0021] In Step S3, the temperature of the mixed solution is 40°C - 60°C, and the soaking time is 10 - 30 minutes.

[0022] In Step S3, the power of the ultrasonic cleaning is 100 W - 300 W, and the frequency is 20 kHz - 40 kHz.

[0023] In Step S4, a chemical mechanical polishing process is adopted, and the surface roughness Rc ≤ 0.05 μm is controlled.

[0024] In the second aspect, a tooling for cleaning the slag in the micropores of an aluminum nitride substrate includes a cleaning tank for the above-mentioned method for processing and cleaning the slag in the micropores of an aluminum nitride substrate,

[0025] Two clamping bowls for symmetrically arranging on the front and back sides of the substrate are arranged in the cleaning tank. The clamping bowls are used to clamp the substrate and form a cavity communicating with the cleaning tank with the substrate. Each clamping bowl is connected with a pushing device for pushing the clamping bowl to clamp the substrate by the two clamping bowls;

[0026] An elastic bowl is arranged in each clamping bowl, and the elastic bowl can be deformed under the action of an external force;

[0027] The clamping bowl is provided with a push-pull rod passing through it and connected to the elastic bowl. The moving direction of the push-pull rod is perpendicular to the symmetry plane between the two clamping bowls. The push-pull rod passes through the cleaning tank and is connected to the driving device outside the cleaning tank;

[0028] A cleaning solution is injected into the cleaning tank. When the elastic bowl is squeezed, the cleaning solution in the cleaning tank forms a reciprocating flow in the micropores on the substrate. Both the clamping bowl and the elastic bowl are in the shape of a hollow hemisphere. An ultrasonic cleaning device is provided in the cleaning tank. The setting of the ultrasonic cleaning device in the cleaning tank adopts the prior art and will not be elaborated here. Its function is that through the setting of the clamping bowl and the pushing device, the substrate can be clamped; through the setting of the elastic bowl, the push-pull rod and the driving device, the elastic bowl can be squeezed against the substrate by driving the push-pull rod by the driving device to realize the reciprocating flow of the cleaning solution in the micropores on the substrate, thereby enhancing the impact force on the slag in the micropores.

[0029] Furthermore, an anti-slip texture layer is provided on the contact surface of the clamping bowl for contacting the substrate. Its function is that through the setting of the anti-slip texture layer, the clamping effect of the clamping bowl on the substrate can be enhanced.

[0030] Furthermore, the clamping bowl is made of an acid and alkali resistant rigid material, and the acid and alkali resistant rigid material is polytetrafluoroethylene, polyvinyl chloride, polyvinylidene fluoride, ceramic material, fiberglass or glass. The elastic bowl is made of an acid and alkali resistant elastic material, and the acid and alkali resistant elastic material is perfluoroether rubber, ethylene propylene diene monomer rubber, chloroprene rubber or polytetrafluoroethylene composite material. Its function is that through the design of using acid and alkali resistant materials for the clamping bowl and the elastic bowl, the clamping bowl and the elastic bowl can be prevented from being corroded and damaged by the cleaning solution.

[0031] Furthermore, a pressure relief hole is provided on the elastic bowl. Its function is that through the setting of the pressure relief hole, when the elastic bowl is squeezed, the pressure between the elastic bowl and the substrate can be reduced, and the substrate can be prevented from being damaged due to excessive pressure between the elastic bowl and the substrate.

[0032] Furthermore, a communication port for communicating with the cleaning tank is provided at the bottom of the clamping bowl. Its function is that through the setting of the communication port, the cleaning solution in the cleaning tank can enter the clamping bowl; through the design of the position of the communication port on the clamping bowl, the liquid fluctuation of the disturbance of the elastic bowl in the clamping bowl can be minimized from being transmitted to the liquid surface of the cleaning solution.

[0033] Furthermore, both the pushing device and the driving device adopt hydraulic cylinders. The fixing of the pushing device and the driving device adopts the prior art and will not be elaborated here. The dynamic seal between the driving device and the side wall of the cleaning tank adopts the prior art and will not be elaborated here. A connecting rod is connected between the pushing device and the top surface of the outer wall of the clamping bowl, and the connecting rod passes through the top surface of the cleaning tank.

[0034] The beneficial effects of the present invention are:

[0035] 1. By using a substrate with a thickness greater than 0.2 mm for laser processing and then soaking and cleaning the substrate with an acidic solution or an alkaline solution, the slag in the micro-holes can be effectively removed. And because using an acidic solution or an alkaline solution will increase the surface roughness of the substrate, by fine polishing to reduce the surface roughness of the substrate and removing the excess thickness of the substrate, the substrate can reach the predetermined thickness (0.2 mm), so that an aluminum nitride substrate with a predetermined thickness, a predetermined roughness and completely cleaned micro-holes can be obtained. Further, further cleaning the substrate with an acidic solution and an alkaline solution can slightly increase the roughness of the micro-holes, which is beneficial to the subsequent electroplating process;

[0036] 2. Through the setting of the clamping bowl and the pushing device, the substrate can be clamped; through the setting of the elastic bowl, the push rod and the driving device, the driving device can drive the push rod to squeeze the elastic bowl on the substrate to realize the reciprocating flow of the cleaning solution in the micro-holes of the substrate, thereby enhancing the impact force on the slag in the micro-holes. Description of the Drawings

[0037] Figure 1 It is the process flow chart of the substrate processing in Embodiment 1;

[0038] Figure 2 It is the top view sectional structure schematic diagram of the slag cleaning tooling in Embodiment 1;

[0039] Figure 3 It is the front view sectional structure schematic diagram of the slag cleaning tooling in Embodiment 1.

[0040] Reference Signs: 1. Substrate; 2. Micro-hole; 3. Cleaning tank; 4. Clamping bowl; 5. Elastic bowl; 6. Push rod; 7. Driving device; 8. Pushing device; 9. Communication port; 10. Connecting rod; 11. Pressure relief hole. Detailed Embodiments

[0041] The following will further elaborate on the present invention in conjunction with the embodiments and the drawings, but the implementation manners of the present invention are not limited thereto.

[0042] Embodiment 1

[0043] In a first aspect, a method for processing micro-holes and cleaning slag on an aluminum nitride substrate is as Figure 1 shown, including the following steps:

[0044] Step S1. Select an aluminum nitride substrate 1 with a thickness of 0.3 mm;

[0045] Step S2. Use a laser to process micro-holes 2 with a diameter of 0.1 mm on the substrate 1;

[0046] Step S3: Place the substrate 1 in the slag cleaning tooling, soak it with a 1:1 potassium hydroxide - hydrogen peroxide mixed solution or a 2:1 sulfuric acid - hydrogen peroxide mixed solution, and simultaneously apply ultrasonic cleaning;

[0047] Step S4: Precision polish the substrate 1 until the thickness of the substrate 1 is 0.2 mm and restore the surface roughness to that before the immersion cleaning;

[0048] Step S5: Conduct a final cleaning with an organic solvent. Its function is that by using a substrate 1 with a thickness greater than 0.2 mm for laser processing, and then soaking and cleaning the substrate 1 with an acidic solution or an alkaline solution, the slag in the micropores 2 can be effectively removed. And because using an acidic solution or an alkaline solution will increase the surface roughness of the substrate 1, by precision polishing, while reducing the surface roughness of the substrate 1, the excess thickness of the substrate 1 is removed so that the substrate 1 can reach the predetermined thickness (0.2 mm), thereby enabling an aluminum nitride substrate 1 with a predetermined thickness and a predetermined roughness and completely cleaned micropores 2 to be obtained. Further, further cleaning the substrate 1 with an acidic solution and an alkaline solution can slightly increase the roughness of the micropores 2, which is beneficial to the subsequent electroplating process.

[0049] It also includes the following steps:

[0050] Step S3a: In the slag cleaning tooling of Step S3, by successively and circularly squeezing the elastic bowls 5 on both sides of the micropores 2, the solution is made to flow back and forth in the micropores 2 to accelerate the removal of slag.

[0051] In Step S3a, the squeezing frequency of the elastic bowl 5 is 5 times per minute - 20 times per minute, and the generated pressure difference is 0.1 MPa - 0.5 MPa.

[0052] In Step S3, the temperature of the mixed solution is 40°C - 60°C, and the soaking time is 10 minutes - 30 minutes.

[0053] In Step S3, the power of the ultrasonic cleaning is 100 W - 300 W, and the frequency is 20 kHz - 40 kHz.

[0054] In Step S4, a chemical mechanical polishing process is adopted, and the surface roughness Rc ≤ 0.05 μm is controlled.

[0055] Second aspect, a slag cleaning tooling for micropores of an aluminum nitride substrate, as Figure 2 shown, including a cleaning tank 3, which is used for the above-mentioned method for micropore processing and slag cleaning of an aluminum nitride substrate,

[0056] Two clamping bowls 4 for symmetrically arranging on the front and rear sides of the substrate 1 are provided in the cleaning tank 3. The clamping bowls 4 are used for clamping the substrate 1 and forming a cavity communicating with the cleaning tank 3 with the substrate 1, as Figure 3As shown in the figure, each clamping bowl 4 is connected with a pushing device 8 for pushing the clamping bowl 4 to clamp the substrate 1 by the two clamping bowls 4;

[0057] Inside each clamping bowl 4, there is an elastic bowl 5 which can be deformed by external force extrusion;

[0058] The clamping bowl 4 is provided with a push-pull rod 6 penetrating through and connected with the elastic bowl 5. The moving direction of the push-pull rod 6 is perpendicular to the symmetry plane between the two clamping bowls 4. The push-pull rod 6 penetrates through the cleaning tank 3 and is connected with the driving device 7 outside the cleaning tank 3;

[0059] The cleaning solution is injected into the cleaning tank 3. When the elastic bowl 5 is extruded, the solution forms a reciprocating flow in the micropores 2 on the substrate 1. Both the clamping bowl 4 and the elastic bowl 5 are in the shape of a hollow hemisphere. An ultrasonic cleaning device is provided in the cleaning tank 3. The setting of the ultrasonic cleaning device in the cleaning tank 3 adopts the prior art and will not be elaborated here. Its function is that through the setting of the clamping bowl 4 and the pushing device 8, the substrate 1 can be clamped; through the setting of the elastic bowl 5, the push-pull rod 6 and the driving device 7, the driving device 7 can drive the push-pull rod 6 to squeeze the elastic bowl 5 against the substrate 1 to realize the reciprocating flow of the cleaning solution in the micropores 2 on the substrate 1, thereby enhancing the impact force on the slag in the micropores 2.

[0060] Specifically, as Figure 2 shown in the figure, an anti-slip texture layer is provided on the contact surface of the clamping bowl 4 for contacting the substrate 1. Its function is that through the setting of the anti-slip texture layer, the clamping effect of the clamping bowl 4 on the substrate 1 can be enhanced.

[0061] Specifically, as Figure 2 shown in the figure, the clamping bowl 4 is prepared from an acid and alkali resistant rigid material, and the acid and alkali resistant rigid material is glass. The elastic bowl 5 is prepared from an acid and alkali resistant elastic material, and the acid and alkali resistant elastic material is a polytetrafluoroethylene composite material. Its function is that through the design of using acid and alkali resistant materials for the clamping bowl 4 and the elastic bowl 5, the clamping bowl 4 and the elastic bowl 5 can be prevented from being corroded and damaged by the cleaning solution.

[0062] Specifically, as Figure 2 shown in the figure, the elastic bowl 5 is provided with a pressure relief hole 11. The pressure relief hole 11 penetrates through both the inner and outer sides of the elastic bowl 5. Its function is that through the setting of the pressure relief hole 11, when the elastic bowl 5 is extruded, the pressure between the elastic bowl 5 and the substrate 1 can be reduced, and the substrate 1 can be prevented from being damaged due to excessive pressure between the elastic bowl 5 and the substrate 1.

[0063] Specifically, as Figure 2As shown, a communication port 9 for communicating with the cleaning tank 3 is provided at the bottom of the clamping bowl 4. Its function is that through the setting of the communication port 9, the cleaning solution in the cleaning tank 3 can enter the clamping bowl 4; through the design of the position of the communication port 9 on the clamping bowl 4, the liquid fluctuation of the disturbance of the elastic bowl 5 in the clamping bowl 4 can be minimized from being transmitted to the liquid level of the cleaning solution.

[0064] Specifically, as Figure 2 shown, both the pushing device 8 and the driving device 7 adopt hydraulic cylinders. The fixing of the pushing device 8 and the driving device 7 adopts the prior art and will not be elaborated. The dynamic seal between the driving device 7 and the side wall of the cleaning tank 3 adopts the prior art and will not be elaborated. A connecting rod 10 is connected between the outer wall top surface of the pushing device 8 and the clamping bowl 4, and the connecting rod 10 passes through the top surface of the cleaning tank 3.

[0065] The working principle of this embodiment is described as follows: In step S3, first place the substrate 1 vertically in the cleaning tank 3, and then drive the pushing device 8 to drive the connecting rod 10 to drive the two clamping bowls 4 to clamp and fix the substrate 1. Then inject an acidic solution or an alkaline solution into the cleaning tank 3 to make the cleaning solution (acidic solution or alkaline solution) submerge the micropores 2. Then drive the section devices located on both sides of the substrate 1 first, so that the elastic bowls 5 on both sides of the substrate 1 are successively pressed against the substrate 1 and cyclically squeezed, so as to achieve the effect of making the cleaning solution flow reciprocally in the micropores 2 to accelerate the removal of slag.

[0066] The above is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. Based on the technical essence of the present invention, any simple modification, equivalent replacement, and improvement made to the above embodiments within the spirit and principle of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for micro-hole processing and slag cleaning of an aluminum nitride substrate, characterized in that: It includes the following steps: Step S1: Select an aluminum nitride substrate (1) with a thickness greater than 0.2 mm; Step S2: Use a laser to process micro-holes (2) with a diameter of 0.1 mm on the substrate (1); Step S3: Place the substrate (1) in a slag cleaning tooling, soak it with a potassium hydroxide-hydrogen peroxide mixed solution with a ratio of 1:1 or a sulfuric acid-hydrogen peroxide mixed solution with a ratio of 2:1, and simultaneously apply ultrasonic cleaning; Step S4: Perform fine polishing on the substrate (1) until the thickness of the substrate (1) is 0.2 mm and restore the surface roughness; Step S5: Perform a final cleaning with an organic solvent, It also includes the following steps: Step S3a: In the slag cleaning tooling of Step S3, successively and circularly squeeze the elastic bowls (5) on both sides of the micro-holes (2) to make the solution flow reciprocally in the micro-holes (2) to accelerate slag removal.

2. A method for micro-hole processing and slag cleaning of an aluminum nitride substrate according to claim 1, characterized in that: In Step S3a, the extrusion frequency of the elastic bowl (5) is 5 times / minute - 20 times / minute, and the generated pressure difference is 0.1 MPa - 0.5 MPa.

3. A method for micro-hole machining and slag cleaning of an aluminum nitride substrate according to claim 1, characterized in that: In Step S3, the temperature of the mixed solution is 40°C - 60°C, and the soaking time is 10 minutes - 30 minutes.

4. A method for micro-hole processing and slag cleaning of an aluminum nitride substrate according to claim 1, characterized in that: In Step S3, the power of the ultrasonic cleaning is 100 W - 300 W, and the frequency is 20 kHz - 40 kHz.

5. A method for micro-hole processing and slag cleaning of an aluminum nitride substrate according to claim 1, characterized in that: In Step S4, a chemical mechanical polishing process is adopted to control the surface roughness Rc ≤ 0.05 μm.

6. A microporous slag cleaning tooling for an aluminum nitride substrate, comprising a cleaning tank (3), characterized in that: For a method for processing micro-holes and cleaning slag of an aluminum nitride substrate described in any one of claims 1 - 5, Two clamping bowls (4) for symmetrically arranging on the front and rear sides of the substrate (1) are provided in the cleaning tank (3). The clamping bowls (4) are used to clamp the substrate (1) and form a cavity communicating with the cleaning tank (3) with the substrate (1). Each clamping bowl (4) is connected with a pushing device (8) for pushing the clamping bowl (4) to clamp the substrate (1) by the two clamping bowls (4); An elastic bowl (5) is provided in each clamping bowl (4), and the elastic bowl (5) can be deformed by an external force; A push-pull rod (6) connected to the elastic bowl (5) is provided through the clamping bowl (4). The moving direction of the push-pull rod (6) is perpendicular to the symmetry plane between the two clamping bowls (4). The push-pull rod (6) is provided through the cleaning tank (3) and the push-pull rod (6) is connected to the driving device (7) outside the cleaning tank (3); Cleaning solution is injected into the cleaning tank (3). When the elastic bowl (5) is squeezed, the cleaning solution in the cleaning tank (3) forms a reciprocating flow in the micro-holes (2) on the substrate (1).

7. The microporous slag cleaning tooling for an aluminum nitride substrate according to claim 6, wherein: An anti-slip texture layer is provided on the contact surface of the clamping bowl (4) for contacting the substrate (1).

8. The microporous slag cleaning tooling for an aluminum nitride substrate according to claim 6, characterized in that: The clamping bowl (4) is made of an acid and alkali resistant rigid material, and the acid and alkali resistant rigid material is polytetrafluoroethylene, polyvinyl chloride, polyvinylidene fluoride, ceramic material, fiberglass or glass. The elastic bowl (5) is made of an acid and alkali resistant elastic material, and the acid and alkali resistant elastic material is perfluoroether rubber, ethylene propylene diene monomer rubber, chloroprene rubber or polytetrafluoroethylene composite material.

9. The microporous slag cleaning tooling for an aluminum nitride substrate according to claim 6, characterized in that: A pressure relief hole (11) is provided on the elastic bowl (5).

Images