A 1200v freewheeling diode matched with an igbt module and a preparation method thereof

Abstract

The application discloses a 1200V freewheeling diode matched with an IGBT module and a preparation method thereof, and the preparation method comprises the following steps: step 1, adopting ring plate lithography etching on the front surface of an N-type substrate, implanting boron by high-energy ion injection, and annealing at a preset temperature I to form a high-doped P+ ring region; step 2, adopting active region plate lithography etching on the front surface of the main junction region of the N-type substrate, implanting boron by high-energy ion injection, and annealing and activating at a preset temperature II to form a lightly-doped P- region; and step 3, adopting N-buffer plate lithography etching on the lightly-doped P- region, implanting phosphorus by high-energy ion injection, and annealing and activating to set an N-buffer region on the lower surface of the lightly-doped P- region. The diode obtained by adopting the preparation method has a fast and soft reverse recovery characteristic and a good temperature coefficient.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and in particular to a 1200V freewheeling diode for use with an IGBT module and its fabrication method. Background Technology

[0002] The main difference between traditional 1200V fast recovery diodes used in IGBT modules for freewheeling and ordinary freewheeling diodes lies in the reverse recovery time, which is primarily related to the non-equilibrium carrier lifetime. Gold doping or electron irradiation are commonly used to reduce minority carrier lifetime, resulting in a shorter reverse recovery time. However, with the development of power electronics technology, traditional 1200V fast recovery diodes used in IGBT modules for freewheeling are far from meeting the requirements of new device applications. Existing fast recovery diodes not only require shorter reverse recovery times but also softer reverse recovery characteristics and a better temperature coefficient. This is especially important in high-power switching circuits, where the load is often inductive, generating a large induced voltage during switching. To protect the main switching device from damage, a freewheeling diode needs to be connected in parallel, allowing the high voltage generated to be dissipated as current in the circuit. Therefore, the freewheeling diode must have fast and soft reverse recovery characteristics and a good temperature coefficient. Therefore, how to make the freewheeling diode meet these technical requirements is a direction that those skilled in the art are dedicated to improving. Summary of the Invention

[0003] The purpose of this invention is to provide a method for fabricating a freewheeling diode for an S1200V IGBT module.

[0004] To achieve this objective, the present invention adopts the following technical solution:

[0005] A method for fabricating a 1200V freewheeling diode for use with an IGBT module, the method comprising the following steps:

[0006] Step 1) On the front side of the N-type substrate, a ring-shaped photolithography etching is used to form a highly doped P+ ring region by high-energy ion implantation of boron and annealing at a preset temperature I.

[0007] Step 2) On the front main junction region of the N-type substrate, active region photolithography is used to form a lightly doped P-region by high-energy ion implantation of boron and annealing activation at a preset temperature II.

[0008] Step 3) In the lightly doped P-region, N-buffer plate photolithography is used for etching, and phosphorus is implanted by high-energy ion and activated by annealing to form an N-buffer region on the lower surface of the lightly doped P-region.

[0009] In one specific implementation, the high-energy ion implantation of boron in step 1) uses a dose of 1E13~5E13, an energy of 50-60keV, and an average implantation depth of 12-15μm.

[0010] As a specific implementation method, the preset temperature I used in step 1) is 1250℃, and the annealing time is controlled between 400-500min.

[0011] In one specific implementation, in step 2), the high-energy ion implantation of boron uses a dose of 5E11~1E12, an energy of 50-60 keV, and an average implantation depth of 2-4 μm.

[0012] As a specific implementation method, the preset temperature II used in step 2) is 1100℃, and the annealing time is controlled between 60-90 minutes.

[0013] As a specific implementation method, the high-energy ion implantation of phosphorus used in step 3) uses a dose of 3E15~5E15, an energy of 80-120 keVv, and an average implantation depth of 8-10 μm.

[0014] In one specific implementation, the annealing temperature in step 3) is 1100℃, and the annealing time is controlled between 60-90 minutes.

[0015] Another objective of this invention is to provide a 1200V freewheeling diode for use with an IGBT module, which is prepared using the above-described method.

[0016] Compared with traditional 1200V fast recovery diodes used for freewheeling in IGBT modules, the freewheeling diode of this invention has the following advantages:

[0017] (1) An SSD electrostatic shielding diode is formed in the main junction region through a highly doped P+ ring region and a lightly doped P- region, thereby improving the problem of insufficient reverse recovery characteristics of traditional products;

[0018] (2) An N-buffer layer is set under the lightly doped P-region in the main junction region to achieve local minority carrier lifetime control, thereby effectively improving the temperature coefficient of traditional products. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the freewheeling diode of the 1200V IGBT module described in this invention. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] This invention provides a 1200V freewheeling diode for use with an IGBT module. It has a ring region and a main junction region on the upper surface of an N-type substrate. The ring region is a highly doped P+ ring region, and the main junction region is a lightly doped P- region. An N-buffer region is set on the lower surface of the lightly doped P- region.

[0022] Its specific preparation method includes the following steps:

[0023] Step 1) On the front side of the N-type substrate, ring-shaped photolithography is used for etching. Boron is implanted by high-energy ions and annealed at 1250℃ for 400-500 min to form a highly doped P+ ring region. Here, the dose of high-energy ion implantation of boron is 1E13~5E13, the energy is 50-60keV, and the average implantation depth is 12-15μm.

[0024] Step 2) On the front main junction region of the N-type substrate, active region photolithography is used for etching, boron is implanted by high-energy ions, and annealing is performed at 1100℃ for 60-90 minutes to form a lightly doped P- region. Here, the dose of high-energy ion implantation of boron is 5E11~1E12, the energy is 50-60keV, and the average implantation depth is 2-4μm.

[0025] Step 3) In the lightly doped P- region, N-buffer plate photolithography is used for etching, phosphorus is implanted by high-energy ions, and annealing is performed at 1100℃ for 60-90 min to activate it. An N-buffer region is set on the lower surface of the lightly doped P- region. Here, the dose of high-energy ion implantation of phosphorus is 3E15~5E15, the energy is 80-120 keVv, and the average implantation depth is 8-10 μm.

[0026] The freewheeling diode of this invention features a reduced stored charge due to the lower injection efficiency of the lightly doped P-region, thus forming a static shielding diode (SSD) structure. This structure improves the diode's reverse recovery characteristics. In the lightly doped P-region, an N-buffer is formed through photolithography etching, high-energy ion implantation of phosphorus, and annealing activation, thereby achieving local minority carrier lifetime control and improving the product's temperature coefficient. Compared to traditional 1200V fast recovery diodes used in IGBT modules for freewheeling, this invention features an SSD static shielding diode in the main junction region, improving reverse recovery characteristics; and an N-buffer in the lightly doped P-region, achieving local minority carrier lifetime control and thus improving the product's temperature coefficient.

[0027] The above description is only a preferred embodiment of the present invention. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present invention. The content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for fabricating a 1200V freewheeling diode paired with an IGBT module, characterized in that, The preparation method includes the following steps: Step 1) On the front side of the N-type substrate, a ring-shaped photolithography etching is used to form a highly doped P+ ring region by high-energy ion implantation of boron and annealing at a preset temperature I. Step 2) On the front main junction region of the N-type substrate, active region photolithography is used for etching, and boron is implanted by high-energy ions and activated by annealing at a preset temperature II to form a lightly doped P-region. Step 3) In the lightly doped P-region, N-buffer plate photolithography is used for etching, and phosphorus is implanted by high-energy ion and activated by annealing to form an N-buffer region on the lower surface of the lightly doped P-region.

2. The method for fabricating a 1200V freewheeling diode paired with an IGBT module according to claim 1, characterized in that, In step 1), the high-energy ion implantation of boron uses a dose of 1E13~5E13, an energy of 50-60keV, and an average implantation depth of 12-15μm.

3. The method for fabricating a 1200V freewheeling diode paired with an IGBT module according to claim 1, characterized in that, The preset temperature I used in step 1) is 1250℃, and the annealing time is controlled between 400-500 min.

4. The method for fabricating a 1200V freewheeling diode paired with an IGBT module according to claim 1, characterized in that, In step 2), the high-energy ion implantation of boron uses a dose of 5E11~1E12, an energy of 50-60 keV, and an average implantation depth of 2-4 μm.

5. The method for fabricating a 1200V freewheeling diode paired with an IGBT module according to claim 1, characterized in that, The preset temperature II used in step 2) is 1100℃, and the annealing time is controlled between 60-90 minutes.

6. The method for fabricating a 1200V freewheeling diode paired with an IGBT module according to claim 1, characterized in that, The high-energy ion implantation of phosphorus used in step 3) has a dose of 3E15~5E15, an energy of 80-120keV, and an average implantation depth of 8-10μm.

7. The method for fabricating a 1200V freewheeling diode paired with an IGBT module according to claim 1, characterized in that, In step 3), the annealing temperature is 1100℃ and the annealing time is controlled between 60-90 minutes.

8. A 1200V freewheeling diode for use with an IGBT module, characterized in that, The freewheeling diode was prepared using the method described in any one of claims 1 to 7.

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