Manufacturing method of a low-voltage and low-leakage diode

Abstract

The present invention discloses a manufacturing method of a low-voltage and low-leakage diode. The low-voltage and low-leakage diode includes a silicon wafer, which is of P-type material, with the front and back sides distinguished. After processing the front side, polysilicon is deposited on the surface, and isolation grooves are etched. Photoresist glass powder is filled inside the isolation grooves to further reduce leakage current. The manufacturing method of the low-voltage and low-leakage diode includes: silicon wafer cleaning, polysilicon deposition, active region implantation, redistribution, isolation groove lithography, isolation groove etching, photoresist glass powder melting, secondary lithography, front-side metallization of the silicon wafer, metal back-etching, back-side cleaning of the silicon wafer, back-side metallization of the silicon wafer, dicing, and chip storage. The beneficial effects of the present invention are as follows: The manufacturing method of the low-voltage and low-leakage diode has the advantages of low voltage, small leakage current, strong stability, and high reliability, and can be widely applied to various environments and quality level requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of the design and manufacture of electronic components, and more specifically, to a manufacturing method of a small-capacitance guiding rectifier diode. Background Art

[0002] Semiconductors refer to materials whose electrical conductivity at room temperature is between that of conductors and insulators. Semiconductors have a wide range of applications in various electronic instruments in life.

[0003] Currently, in the field of electronic component chips, the vast majority of low-voltage diodes generally exhibit a relatively large leakage current.

[0004] The production of ordinary low-voltage diode chips aims to reduce the leakage current by increasing the passivation layer. However, this method has an insignificant effect on reducing the leakage current. Therefore, a new process method is needed to further reduce the leakage current of low-voltage diodes. For this purpose, we propose a manufacturing method of a low-voltage and low-leakage current diode. Summary of the Invention

[0005] The present invention is precisely a manufacturing method of a low-voltage and low-leakage current diode designed to solve the above technical problems, and solves the problem that it is difficult to reduce the large leakage current of low-voltage diode chips.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0007] A manufacturing method of a low-voltage and low-leakage current diode, the low-voltage and low-leakage current diode includes a silicon wafer, the silicon wafer is a P-type material, the front and back are distinguished, after the front is processed, polysilicon is deposited on the surface, and isolation grooves are etched at the same time, and photoresist glass powder is filled inside the isolation grooves to further reduce leakage; the manufacturing method of the low-voltage and low-leakage current diode includes: silicon wafer cleaning, polysilicon deposition, active region implantation, redistribution, isolation groove lithography, isolation groove etching, photoresist glass powder melting, secondary lithography, front-side metallization of the silicon wafer, metal etching, back-side cleaning of the silicon wafer, back-side metallization of the silicon wafer, dicing, and chip storage; the specific implementation steps are as follows:

[0008] Step 1: The silicon wafer cleaning: The silicon wafer is cleaned by chemical reaction and melt washing to obtain a silicon wafer with a highly clean surface;

[0009] Step 2: The polysilicon deposition: POLY process is used to deposit polysilicon on the front side of the silicon wafer processed in Step 1;

[0010] Step 3: The active region implantation: Ion implantation is performed on the front region of the silicon wafer processed in Step 2, so that the single crystal material obtains the specified doping ions in the defined region to form an active region;

[0011] Step Four: The Redistribution: For the silicon wafer processed in Step Three, in a high-temperature dry oxygen atmosphere, the doped ions implanted in the active region diffuse into the interior of the silicon wafer, ultimately forming an active region with a junction depth of 2 - 3 microns.

[0012] Step Five: The Isolation Trench Lithography: Use the spin coating method to apply a layer of photoresist on the front side of the silicon wafer. Employ the isolation trench photomask to perform local exposure and masking etching on the front side of the silicon wafer, and etch an isolation ring window on the photoresist film.

[0013] Step Six: The Isolation Trench Etching: After Step Five, etch the front side of the silicon wafer to form an isolation trench with a depth of 20 microns.

[0014] Step Seven: The Photoresist Glass Powder Melting: After completing Steps One to Six, perform photoresist glass powder melting. After melting, the isolation trench is filled with glass powder.

[0015] Step Eight: The Second Lithography: After Step Seven, perform the second lithography. Use the spin coating method to apply a layer of photoresist on the front side of the silicon wafer. Select the second lithography mask and perform local exposure and masking etching to etch an electrode window on the photoresist.

[0016] Step Nine: The Front-Side Metallization of the Silicon Wafer: After Step Eight, use the evaporation process to form a metal film on the front side of the silicon wafer.

[0017] Step Ten: The Metal Lift-Off: After Step Nine, use the spin coating method to apply a layer of photoresist on the front side of the silicon wafer. Employ the metal lift-off photomask to perform local exposure and masking etching on the front side of the silicon wafer, and etch an electrode on the photoresist film.

[0018] Step Eleven: The Back-Side Cleaning of the Silicon Wafer: After Step Ten, perform chemical cleaning on the back side of the silicon wafer to obtain a silicon wafer with a highly clean back side.

[0019] Step Twelve: The Back-Side Metallization of the Silicon Wafer: After Step Eleven, use the evaporation process to form a metal film on the back side of the silicon wafer.

[0020] Step Thirteen: The Dicing: After Step Twelve, use a diamond grinding wheel to cut the silicon wafer to obtain finished chips.

[0021] For the manufacturing method of the low-voltage and low-leakage diode, the chemical reaction and washing method are as follows: First, wash with a mixture of sulfuric acid and hydrogen peroxide for 10 minutes, then wash with DI water for 10 minutes. Then, soak in 1:20 hydrofluoric acid for 20 seconds, wash with DI water for 10 minutes. Finally, wash with a mixture of ammonia water and hydrogen peroxide for 10 minutes, wash with DI water for 10 minutes, and spin dry for 10 minutes.

[0022] The manufacturing method of the low-voltage and low-leakage diode, the POLY process is as follows: The gas used is silane. The gas is introduced for 20 minutes at 650 °C, then the temperature is raised to 780 °C and deposition is carried out for 1 hour, and the formed polysilicon thickness is 3300 Å.

[0023] The manufacturing method of the low-voltage and low-leakage diode, the ion implantation is as follows: PH3 is used as the implantation source, the implantation energy is 120 Kev, and the implantation dose is 2E16.

[0024] The manufacturing method of the low-voltage and low-leakage diode, the diffusion distribution in step 4 means that in a dry oxygen atmosphere at a temperature of 1150 °C, the oxygen flow rate is 8 L / min, and the time is 30 minutes, so that the implanted doping ions in the active region (7) diffuse into the silicon wafer.

[0025] The manufacturing method of the low-voltage and low-leakage diode, the spin coating method means that: the photoresist is selected as BN308-450, the rotation speed is 2000 revolutions per minute, and the time is 20 seconds for the photoresist coating operation.

[0026] The manufacturing method of the low-voltage and low-leakage diode, the etching means that the ICP plasma etching method is used for the isolation groove etching.

[0027] The manufacturing method of the low-voltage and low-leakage diode, the melting is carried out at a pre-burning temperature of 570 °C, an oxygen flow rate of 8 L / min, and a pre-burning time of 15 minutes; then at a melting temperature of 740 °C, an oxygen flow rate of 8 L / min, and a continuous melting time of 15 minutes.

[0028] The manufacturing method of the low-voltage and low-leakage diode, the evaporation process is as follows: In a vacuum environment, an electron beam is used to bombard the Ti / Ni / Ag material, generating Ti / Ni / Ag metal vapor that splashes onto the silicon wafer surface, and the thicknesses of the Ti / Ni / Ag metal films are 4000 Å / 800 Å / 15000 Å respectively.

[0029] The manufacturing method of the low-voltage and low-leakage diode, the chemical cleaning means that: first, soak in 1:20 hydrofluoric acid for 10 seconds, clean with DI water for 10 minutes, then clean with acetone for 10 minutes, clean with DI water for 10 minutes, then clean with ethanol for 10 minutes, and finally clean with isopropanol for 10 minutes.

[0030] Preferably, for the chip storage, the produced chips are placed in an appropriate environment for long-term storage.

[0031] The beneficial effects of the present invention are: The chips manufactured by the manufacturing method of the low-voltage and low-leakage diode have the advantages of low voltage, low leakage current, and high reliability, and can be widely applied to various environments and quality level requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic longitudinal sectional structure diagram of the low-voltage and low-leakage diode of the present invention;

[0033] Figure 2 It is a schematic structure diagram of the photomask of the low-voltage and low-leakage diode of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention will be further described below in conjunction with the drawings and embodiments.

[0035] As shown in Figure 1 and 2 A manufacturing method of a low-voltage and low-leakage diode according to the present invention, the low-voltage and low-leakage diode includes a silicon wafer, the silicon wafer is a P-type material, the front and back are distinguished, the surface of the front is deposited with polysilicon after processing, and at the same time isolation grooves are etched, and photoresist glass powder is filled inside the isolation grooves to further reduce leakage; the manufacturing method of the low-voltage and low-leakage diode includes: silicon wafer cleaning, polysilicon deposition, active region implantation, redistribution, isolation groove lithography, isolation groove etching, photoresist glass powder melting, secondary lithography, front surface metallization of the silicon wafer, metal back-etching, back surface cleaning of the silicon wafer, back surface metallization of the silicon wafer, dicing and chip storage; the specific implementation steps are:

[0036] Step 1: The silicon wafer cleaning: The silicon wafer is cleaned by chemical reaction and melt washing to obtain a silicon wafer with a highly clean surface;

[0037] Step 2: The polysilicon deposition: POLY process is used to deposit polysilicon on the front surface of the silicon wafer processed in Step 1;

[0038] Step 3: The active region implantation: Ion implantation is performed on the front surface region of the silicon wafer processed in Step 2, so that the single crystal material obtains specified doped ions in a limited region to form an active region;

[0039] Step 4: The redistribution: After the silicon wafer processed in Step 3, in a high-temperature dry oxygen atmosphere, the doped ions implanted in the active region diffuse into the silicon wafer, and finally an active region with a junction depth of 2-3 microns is formed;

[0040] Step 5: The isolation groove lithography: A layer of photoresist is coated on the front surface of the silicon wafer by spin coating method, and the method of local exposure and masking corrosion is adopted on the front surface of the silicon wafer using the isolation groove photomask to etch isolation ring windows on the photoresist film;

[0041] Step 6: The isolation groove etching: After Step 5, the front surface of the silicon wafer is etched to form isolation grooves with a depth of 20 microns;

[0042] Step 7: Melting the photoresist glass powder: After completing Steps 1 to 6, the photoresist glass powder is melted. After melting, the isolation groove is filled with glass powder;

[0043] Step 8: The second lithography: After Step 7, the second lithography is carried out. A layer of photoresist is coated on the front side of the silicon wafer by spin coating. A second lithography mask is selected, and the methods of local exposure and masking etching are adopted to etch electrode windows on the photoresist;

[0044] Step 9: Metallization on the front side of the silicon wafer: After Step 8, a metal film is formed on the front side of the silicon wafer by evaporation process;

[0045] Step 10: Metal etching back: After Step 9, a layer of photoresist is coated on the front side of the silicon wafer by spin coating. Using a metal etching back lithography mask, the methods of local exposure and masking etching are adopted on the front side of the silicon wafer to etch electrodes on the photoresist film;

[0046] Step 11: Cleaning the back side of the silicon wafer: After Step 10, the back side of the silicon wafer is chemically cleaned to obtain a silicon wafer with a highly clean back side;

[0047] Step 12: Metallization on the back side of the silicon wafer: After Step 11, a metal film is formed on the back side of the silicon wafer by evaporation process;

[0048] Step 13: Dicing: After Step 12, the silicon wafer is cut by a diamond grinding wheel to obtain finished chips.

[0049] For the manufacturing method of the low-voltage and low-leakage diode, the chemical reaction and melting and washing method are as follows: First, wash with a mixed solution of sulfuric acid and hydrogen peroxide for 10 minutes, wash with DI water for 10 minutes, then soak in 1:20 hydrofluoric acid for 20 seconds, wash with DI water for 10 minutes, finally wash with a mixed solution of ammonia water and hydrogen peroxide for 10 minutes, wash with DI water for 10 minutes, and spin dry for 10 minutes.

[0050] For the manufacturing method of the low-voltage and low-leakage diode, the POLY process is as follows: The gas used is silane. The gas is introduced for 20 minutes at 650 °C, then the temperature is raised to 780 °C, and deposition is carried out for 1 hour. The thickness of the formed polysilicon is 3300 Å.

[0051] For the manufacturing method of the low-voltage and low-leakage diode, the ion implantation is as follows: PH3 is used as the implantation source, the implantation energy is 120 Kev, and the implantation dose is 2E16.

[0052] For the manufacturing method of the low-voltage and low-leakage diode, the diffusion distribution in Step 4 means that in a dry oxygen atmosphere at a temperature of 1150 °C, the oxygen flow rate is 8 L / min, and the time is 30 minutes, so that the implanted doping ions in the active region (7) diffuse into the interior of the silicon wafer.

[0053] The manufacturing method of the low-voltage and low-leakage diode, the spin coating method refers to: the photoresist is selected as BN308-450, the rotation speed is 2000 revolutions per minute, and the time is 20 seconds for the photoresist coating operation.

[0054] The manufacturing method of the low-voltage and low-leakage diode, the etching refers to using the ICP plasma etching method for the isolation trench etching.

[0055] The manufacturing method of the low-voltage and low-leakage diode, the melting is carried out at a pre-burning temperature of 570 °C, an oxygen flow rate of 8 L / min, and a pre-burning time of 15 minutes; then at a melting temperature of 740 °C, an oxygen flow rate of 8 L / min, and a continuous melting time of 15 minutes.

[0056] The manufacturing method of the low-voltage and low-leakage diode, the evaporation process is: in a vacuum environment, use an electron beam to bombard the Ti / Ni / Ag material to generate Ti / Ni / Ag metal vapor that splashes on the surface of the silicon wafer, and the thicknesses of the Ti / Ni / Ag metal films are 4000 Å / 800 Å / 15000 Å respectively.

[0057] The manufacturing method of the low-voltage and low-leakage diode, the chemical cleaning refers to: first soak in hydrofluoric acid with a ratio of 1:20 for 10 seconds, clean with DI water for 10 minutes, then clean with acetone for 10 minutes, clean with DI water for 10 minutes, then clean with ethanol for 10 minutes, and finally clean with isopropanol for 10 minutes.

[0058] Please refer to Figures 1 to 2 , the present invention provides a technical solution: a manufacturing method of a low-voltage and low-leakage diode, characterized in that: the manufacturing method further reduces leakage through single crystal materials, deposited polysilicon and photoresist glass powder isolation, and the manufacturing method includes the following steps, silicon wafer cleaning, deposited polysilicon, active area implantation, redistribution, isolation trench lithography, isolation trench etching, photoresist glass powder melting, secondary lithography, front and back metallization, metal etching back, dicing and chip storage.

[0059] Its manufacturing process is mainly divided into twelve steps, and the specific operations are as follows:

[0060] The first step: silicon wafer cleaning

[0061] Obtain a workpiece surface with high cleanliness by using chemical reaction and melting and washing methods.

[0062] The second step: deposited polysilicon

[0063] Adopt the POLY (non-oxygen-doped) process, and the time is 20 minutes.

[0064] The third step: active area implantation

[0065] Adopt an ion implantation process with a different ion source type from the single-crystal material, so that the single-crystal material obtains specified doping particles within a defined area. The total implantation energy is 120 Kev and the implantation dose is 2E16.

[0066] Step 4: Redistribution

[0067] In a high-temperature dry oxygen or wet oxygen atmosphere at 1150 °C for a duration of 30 min, so that the high-energy ions diffuse to the depth required by the process (the junction depth of the active region).

[0068] Step 5: Isolation trench lithography

[0069] Select a photomask, and use the methods of local exposure and masking etching to etch an isolation ring window on a specific thin film.

[0070] Step 6: Isolation trench etching

[0071] Use the ICP plasma etching method to etch the single-crystal material to form a shallow trench. After the trench is formed, clean the dust and other substances generated by etching in the trench.

[0072] Step 7: Photoresist glass powder melting

[0073] In an oxygen atmosphere at 570 °C for 15 minutes, and then in an oxygen atmosphere at 740 °C for 15 minutes.

[0074] Step 8: Second lithography

[0075] Select a photomask, and use the methods of local exposure and masking etching to etch an electrode window on a specific thin film.

[0076] Step 9: Front and back metallization

[0077] Bombard the Ti / Ni / Ag material with an electron beam in a vacuum environment to generate metal vapor that splashes onto the surface of the silicon wafer to form a metal film.

[0078] Step 10: Metal etching

[0079] Select a photomask, and use the methods of local exposure and masking etching to etch an electrode on a specific thin film.

[0080] Step 11: Dicing

[0081] Use a diamond grinding wheel to cut the chip wafer to obtain finished chips.

[0082] Step 12: Chip storage

[0083] Place the produced chips in a suitable environment for long-term storage.

[0084] In summary: The design and manufacturing technology can make the leakage current of diodes with a voltage within 5V reach the nA level, and the characteristic curve of the chip shows excellent performance.

[0085] The present invention is not limited to the above-mentioned best implementation mode. Any other products identical or similar to the present invention obtained by anyone under the inspiration of the present invention fall within the protection scope of the present invention.

Claims

1. A manufacturing method of a low-voltage and low-leakage diode, characterized in that: The low-voltage and low-leakage diode includes a silicon wafer (1), which is made of P-type material, with a front side (2) and a back side (3). After processing, polysilicon (4) is deposited on the surface of the front side (2), and isolation grooves (5) are etched. Inside the isolation grooves (5), photoresist glass powder (6) is filled to further reduce leakage. The manufacturing method of the low-voltage and low-leakage diode includes: silicon wafer cleaning, polysilicon deposition, active region implantation, redistribution, isolation groove lithography, isolation groove etching, photoresist glass powder melting, secondary lithography, front-side metallization of the silicon wafer, metal etching back, back-side cleaning of the silicon wafer, back-side metallization of the silicon wafer, dicing, and chip storage. The specific implementation steps are as follows: Step 1: The silicon wafer cleaning: The silicon wafer (1) is cleaned by using chemical reaction and melt washing methods to obtain a silicon wafer with a highly clean surface. Step 2: The polysilicon deposition: POLY process is used to deposit polysilicon on the front side (2) of the silicon wafer processed in Step 1. Step 3: The active region implantation: Ion implantation is performed on the front side (2) region of the silicon wafer processed in Step 2, so that the single-crystal material obtains specified doped ions in the defined region to form an active region (7). Step 4: The redistribution: After the silicon wafer processed in Step 3 is placed in a high-temperature dry oxygen atmosphere, the doped ions implanted in the active region (7) diffuse into the silicon wafer interior, and finally an active region (7) with a junction depth of 2 - 3 microns is formed. Step 5: The isolation groove lithography: A layer of photoresist is coated on the front side (2) of the silicon wafer by spin coating method. Using an isolation groove photomask, the method of local exposure and masking corrosion is adopted on the front side (2) of the silicon wafer to etch isolation ring windows on the photoresist film. Step 6: The isolation groove etching: After Step 5, the front side (2) of the silicon wafer is etched to form isolation grooves (5) with a depth of 20 microns. Step 7: The photoresist glass powder melting: After Steps 1 to 6 are completed, the photoresist glass powder is melted. After melting, the isolation grooves are filled with glass powder. Step 8: The secondary lithography: After Step 7, secondary lithography is performed. A layer of photoresist is coated on the front side (2) of the silicon wafer by spin coating method. Selecting a secondary lithography mask, the method of local exposure and masking corrosion is adopted to etch electrode windows on the photoresist. Step 9: The front-side metallization of the silicon wafer: After Step 8, an evaporation process is used to form a metal film on the front side (2) of the silicon wafer. Step 10: The metal etching back: After Step 9, a layer of photoresist is coated on the front side (2) of the silicon wafer by spin coating method. Using a metal etching back photomask, the method of local exposure and masking corrosion is adopted on the front side (2) of the silicon wafer to etch electrodes on the photoresist film. Step 11: The back-side cleaning of the silicon wafer: After Step 10, the back side (3) of the silicon wafer is chemically cleaned to obtain a silicon wafer with a highly clean back side. Step 12: The back-side metallization of the silicon wafer: After Step 11, an evaporation process is used to form a metal film on the back side (3) of the silicon wafer. Step 13: The dicing: After Step 12, the silicon wafer is cut with a diamond grinding wheel to obtain finished chips.

2. The manufacturing method of a low-voltage and low-leakage diode according to claim 1, wherein: The method of the chemical reaction and melt washing is as follows: First, wash with a mixed solution of sulfuric acid and hydrogen peroxide for 10 minutes, wash with DI water for 10 minutes, then soak in 1:20 hydrofluoric acid for 20 seconds, wash with DI water for 10 minutes, finally wash with a mixed solution of ammonia water and hydrogen peroxide for 10 minutes, wash with DI water for 10 minutes, and spin dry for 10 minutes.

3. The manufacturing method of a low-voltage and low-leakage diode according to claim 1, characterized in that: The POLY process is as follows: The gas used is silane. Ventilate for 20 minutes at 650 °C, then heat up to 780 °C and deposit for 1 hour. The thickness of the formed polysilicon is 3300 Å.

4. The manufacturing method of a low-voltage and low-leakage diode according to claim 1, wherein: The ion implantation is as follows: PH3 is used as the implantation source, the implantation energy is 120 Kev, and the implantation dose is 2E16.

5. The manufacturing method of a low-voltage and low-leakage diode according to claim 1, characterized in that: The diffusion distribution in step 4 refers to that in a dry oxygen atmosphere at a temperature of 1150 °C, with an oxygen flow rate of 8 L / min and a time of 30 minutes, so that the implanted doping ions in the active region (7) diffuse into the silicon wafer.

6. The manufacturing method of a low-voltage and low-leakage diode according to claim 1, wherein: The spin coating method refers to: The photoresist selected is BN308-450, the rotation speed is 2000 revolutions per minute, and the time is 20 seconds for the photoresist coating operation.

7. The manufacturing method of a low-voltage and low-leakage diode according to claim 1, wherein: The etching refers to using ICP plasma etching method for isolation trench etching.

8. The manufacturing method of a low-voltage and low-leakage diode according to claim 1, wherein: The melting is carried out at a pre-burning temperature of 570 °C, an oxygen flow rate of 8 L / min, and a pre-burning time of 15 minutes; then at a melting temperature of 740 °C, an oxygen flow rate of 8 L / min, and a continuous melting time of 15 minutes.

9. The manufacturing method of a low-voltage and low-leakage diode according to claim 1, wherein: The evaporation process is as follows: Under a vacuum environment, use an electron beam to bombard the Ti / Ni / Ag material to generate Ti / Ni / Ag metal vapor that splashes onto the surface of the silicon wafer. The thicknesses of the Ti / Ni / Ag metal films are 4000 Å / 800 Å / 15000 Å respectively.

10. The manufacturing method of a low-voltage and low-leakage diode according to claim 1, wherein: The chemical cleaning refers to: First, soak in 1:20 hydrofluoric acid for 10 seconds, wash with DI water for 10 minutes, then wash with acetone for 10 minutes, wash with DI water for 10 minutes, then wash with ethanol for 10 minutes, and finally wash with isopropanol for 10 minutes.

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