Fast recovery diode device and forming method thereof

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to a fast recovery diode device and a forming method thereof. The forming method of the fast recovery diode device comprises the following steps that a monocrystalline silicon material grows, a silicon substrate is formed, the silicon substrate comprises a front face and a back face which are oppositely distributed, and the oxygen concentration in the silicon substrate is lower than 5 ppma; forming an epitaxial layer on the front surface of the silicon substrate by adopting an epitaxial process; and forming a front device structure on one side, deviating from the silicon substrate, of the epitaxial layer. The power consumption and the manufacturing cost of the fast recovery diode device are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a fast recovery diode device and a forming method thereof. Background Art

[0002] For a diode, its power consumption mainly depends on the diode current and forward voltage drop. Since the diode current is predetermined by the specific application of the diode, the main method to reduce the diode power consumption is to reduce the forward voltage of the diode. For diode devices prepared on 8-inch or 12-inch wafers, the main method to reduce the forward voltage drop is to perform a hydrogen implantation process from the back of the wafer.

[0003] Fast recovery diode (FRD) is a power semiconductor device with advantages such as good switching performance, short reverse recovery time, and soft recovery characteristics. Fast recovery diodes are used as high-frequency rectifier diodes, freewheeling diodes or damping diodes in electronic circuits such as switching power supplies, PWM (Pulse-Width Modulation) devices, and inverters. Fast recovery diode devices are usually prepared on 6-inch and 8-inch wafers. Due to the high price of the equipment for implementing the back hydrogen implantation process, the back hydrogen implantation process is generally not performed on 6-inch wafers for cost considerations.

[0004] Therefore, how to reduce the manufacturing cost of fast recovery diode devices while reducing the power consumption of fast recovery diode devices is a technical problem that needs to be solved urgently. Summary of the invention

[0005] The present invention provides a fast recovery diode device and a method for forming the same, which are used to reduce the power consumption of the fast recovery diode device and reduce the manufacturing cost of the fast recovery diode device.

[0006] According to some embodiments, the present invention provides a method for forming a fast recovery diode device, comprising the following steps:

[0007] Growing a single crystal silicon material to form a silicon substrate, wherein the silicon substrate comprises a front surface and a back surface that are relatively distributed, and an oxygen concentration in the silicon substrate is lower than 5 ppma;

[0008] forming an epitaxial layer on the front side of the silicon substrate by using an epitaxial process;

[0009] A front device structure is formed on a side of the epitaxial layer away from the silicon substrate.

[0010] In some embodiments, the specific steps of growing a single crystal silicon material to form a silicon substrate include:

[0011] The silicon substrate is formed by growing single crystal silicon material using a magnetron Czochralski method.

[0012] In some embodiments, the specific steps of growing a single crystal silicon material to form a silicon substrate include:

[0013] The silicon substrate is formed by growing a single crystal silicon material using a zone melting method.

[0014] In some embodiments, the single crystal silicon material is grown by the zone melting method, and the specific steps of forming the silicon substrate include:

[0015] A single crystal silicon material is grown in a reaction chamber by adopting a zone melting method, and a doping source gas is simultaneously transmitted to the reaction chamber to form the silicon substrate including doped ions.

[0016] In some embodiments, the silicon substrate has a size of 6 inches.

[0017] According to some other embodiments, the present invention also provides a fast recovery diode device, including:

[0018] A silicon substrate, comprising a front side and a back side that are relatively distributed, wherein the oxygen concentration in the silicon substrate is lower than 5 ppma;

[0019] An epitaxial layer, located on the front side of the silicon substrate;

[0020] The front device structure is located on the surface of the epitaxial layer facing away from the silicon substrate.

[0021] In some embodiments, the oxygen concentration in the silicon substrate is less than 0.2 ppma.

[0022] In some embodiments, the silicon substrate has a size of 6 inches.

[0023] In some embodiments, the silicon substrate is a melting zone silicon substrate.

[0024] In some embodiments, the silicon substrate is a magnetron CZ silicon substrate.

[0025] The fast recovery diode device and its formation method provided by the present invention control the oxygen concentration in the silicon substrate during the process of growing a single crystal silicon material to form a silicon substrate, so that the oxygen concentration in the silicon substrate is lower than 5ppma. After an epitaxial layer is formed on the front of the silicon substrate through an epitaxial process and a front device structure is formed on the surface of the epitaxial layer, the fast recovery diode device is obtained. The lower oxygen concentration in the silicon substrate reduces the forward voltage drop of the fast recovery diode, thereby reducing the power consumption of the fast recovery diode device. At the same time, since the fast recovery diode device achieves the effect of reducing power consumption by adjusting the oxygen content in the silicon substrate, there is no need to perform a back hydrogen injection process, so there is no need to use expensive back hydrogen injection equipment, and multiple processes are reduced, thereby reducing the manufacturing cost of the fast recovery diode device. In addition, the method of controlling the oxygen content in the silicon substrate is used to reduce power consumption, which can improve the consistency of the forward voltage drop in the mass-produced fast recovery diode devices, thereby helping to stabilize product performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of a method for forming a fast recovery diode device in a specific embodiment of the present invention;

[0027] Figure 2 is a schematic cross-sectional view of a silicon substrate formed in a specific embodiment of the present invention;

[0028] Figure 3 is a schematic cross-sectional view of an epitaxial layer formed on a silicon substrate in a specific embodiment of the present invention;

[0029] Figure 4 It is a cross-sectional schematic diagram of a specific embodiment of the present invention after a front device structure is formed on the epitaxial layer. DETAILED DESCRIPTION

[0030] The specific implementation manner of the fast recovery diode device and the method for forming the same provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0031] This specific embodiment provides a method for forming a fast recovery diode device. Figure 1 FIG. 1 is a flow chart of a method for forming a fast recovery diode device in a specific embodiment of the present invention. Figure 1 As shown, the method for forming the fast recovery diode device comprises the following steps:

[0032] Step S11, growing a single crystal silicon material to form a silicon substrate, wherein the silicon substrate comprises a front surface and a back surface that are relatively distributed, and an oxygen concentration in the silicon substrate is lower than 5 ppma;

[0033] Step S12, forming an epitaxial layer on the front side of the silicon substrate by using an epitaxial process;

[0034] Step S13, forming a front device structure on a side of the epitaxial layer away from the silicon substrate.

[0035] Figure 2 2 is a schematic cross-sectional view of a silicon substrate formed in a specific embodiment of the present invention. In some embodiments, the specific steps of growing a single crystal silicon material to form a silicon substrate 20 include:

[0036] The silicon substrate 20 is formed by growing single crystal silicon material using a magnetron Czochralski method.

[0037] Specifically, for a fast recovery diode device, its forward voltage drop depends on the metal barrier layer and the active area used in the fast recovery diode device. The influence of the active area mainly comes from the specific material used for the silicon substrate in the fast recovery diode device. Among them, the content of oxygen elements in the silicon substrate and the radial distribution of oxygen elements have a direct impact on the level of the forward voltage drop and the discrete performance. The oxygen concentration in the silicon substrate 20 grown by the magnetron Czochralski method (MCZ) is lower than 5ppma. Compared with the single crystal silicon material grown by the Czochralski method (CZ), the oxygen concentration is greatly reduced, and the radial distribution uniformity of the oxygen element is improved, so that the forward voltage drop of the fast recovery diode device is reduced, thereby reducing the power consumption of the fast recovery diode device.

[0038] In some other embodiments, the specific steps of growing a single crystal silicon material to form the silicon substrate 20 include:

[0039] The silicon substrate 20 is formed by growing a single crystal silicon material using a zone melting method.

[0040] Specifically, in the process of growing single crystal silicon material to form the silicon substrate 20 by using the zone melting method (FZ), the polysilicon raw material, the melting zone and the grown single crystal silicon material do not contact with other substances, thereby avoiding the contact between impurities and the grown silicon substrate 20, so that the grown silicon substrate 20 has a higher purity and a lower oxygen content. In one example, the oxygen concentration in the silicon substrate 20 formed by the zone melting method is lower than 0.2ppma. In this specific embodiment, the silicon substrate 20 is grown by using the zone melting method, so that a lower forward voltage drop can be obtained by a lower oxygen content under the epitaxial conditions (i.e., the process conditions for forming the epitaxial layer) required for the pre-design of the fast recovery diode device, thereby achieving the purpose of reducing the power consumption of the fast recovery diode device. Moreover, the use of the zone melting method to grow the silicon substrate 20 can improve the consistency of the forward voltage drop in the mass-produced fast recovery diode devices, for example, the consistency of the forward voltage drop of the mass-produced fast recovery diode devices is increased by 30% to 50%, thereby helping to further stabilize the product performance.

[0041] In some embodiments, the single crystal silicon material is grown by the zone melting method, and the specific steps of forming the silicon substrate 20 include:

[0042] A single crystal silicon material is grown in a reaction chamber by adopting a zone melting method, and a doping source gas is simultaneously transmitted to the reaction chamber to form the silicon substrate 20 including doped ions.

[0043] In some embodiments, the size of the silicon substrate 20 is 6 inches.

[0044] For example, the 6-inch silicon substrate 20 grown by the zone melting method can achieve the same forward voltage drop as a large-size (for example, 8-inch) silicon wafer after the back hydrogen implantation process without using the back hydrogen implantation process of the substrate, and greatly reduces the manufacturing cost of the substrate 20, so that the fast recovery diode device formed by the silicon substrate 20 can be used in automotive products.

[0045] Figure 3 is a schematic cross-sectional view of an epitaxial layer formed on a silicon substrate in a specific embodiment of the present invention, Figure 4 2 is a schematic cross-sectional view of a specific embodiment of the present invention after a front device structure is formed on an epitaxial layer. After the silicon substrate 20 is formed, the silicon substrate 20 includes a front side 201 and a back side 202 that are relatively distributed. The epitaxial layer 30 is formed on the front side 201 of the silicon substrate 20 by an epitaxial process, such as Figure 3 Afterwards, the front device structure 40 is formed on the side of the epitaxial layer 30 away from the silicon substrate 201 , and the front device structure 40 includes a plurality of doped regions and a front metal layer located above the plurality of doped regions.

[0046] This specific embodiment also provides a fast recovery diode device. The structural diagram of the fast recovery diode device can be seen in Figure 4 The fast recovery diode device can be used as follows Figure 1-Figure 4 The fast recovery diode is formed by the method shown in FIG. Figure 1-Figure 4 As shown, the fast recovery diode device comprises:

[0047] A silicon substrate 20, comprising a front side 201 and a back side 202 which are relatively distributed, wherein the oxygen concentration in the silicon substrate 20 is lower than 5 ppma;

[0048] The epitaxial layer 30 is located on the front side 201 of the silicon substrate 20;

[0049] The front device structure 40 is located on the surface of the epitaxial layer 30 facing away from the silicon substrate 20 .

[0050] Specifically, for a fast recovery diode device, its forward voltage drop depends on the metal barrier layer and the active area used in the fast recovery diode device. The influence of the active area mainly comes from the specific material used in the silicon substrate in the fast recovery diode device. Among them, the content of oxygen elements in the silicon substrate and the radial distribution of oxygen elements have a direct impact on the level of the forward voltage drop and the discrete performance. This specific embodiment controls the oxygen concentration in the silicon substrate 20 to be lower than 5ppma, so that the forward voltage drop of the fast recovery diode is reduced, thereby reducing the power consumption of the fast recovery diode. At the same time, since the fast recovery diode device achieves the effect of reducing power consumption by adjusting the oxygen content in the silicon substrate, there is no need to perform a back hydrogen injection process, so there is no need to use expensive back hydrogen injection equipment, thereby reducing the manufacturing cost of the fast recovery diode device. In addition, the method of controlling the oxygen content in the silicon substrate to reduce power consumption can improve the consistency of the forward voltage drop in the mass-produced fast recovery diode devices, thereby helping to stabilize product performance.

[0051] In some embodiments, the oxygen concentration in the silicon substrate 20 is less than 0.2 ppma.

[0052] In some embodiments, the size of the silicon substrate 20 is 6 inches.

[0053] In some embodiments, the silicon substrate 20 is a melting zone silicon substrate.

[0054] In some embodiments, the silicon substrate 20 is a magnetron CZ silicon substrate.

[0055] The fast recovery diode device and its formation method provided in this specific embodiment control the oxygen concentration in the silicon substrate during the process of growing a single crystal silicon material to form a silicon substrate, so that the oxygen concentration in the silicon substrate is lower than 5ppma, and after forming an epitaxial layer on the front of the silicon substrate through an epitaxial process and forming a front device structure on the surface of the epitaxial layer, the fast recovery diode device is obtained. The lower oxygen concentration in the silicon substrate reduces the forward voltage drop of the fast recovery diode, thereby reducing the power consumption of the fast recovery diode device. At the same time, since the fast recovery diode device achieves the effect of reducing power consumption by adjusting the oxygen content in the silicon substrate, there is no need to perform a back hydrogen injection process, so there is no need to use expensive back hydrogen injection equipment, and multiple processes are reduced, thereby reducing the manufacturing cost of the fast recovery diode device. In addition, the method of controlling the oxygen content in the silicon substrate to reduce power consumption can improve the consistency of the forward voltage drop in the mass-produced fast recovery diode devices, thereby helping to stabilize product performance.

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for forming a fast recovery diode device, characterized in that: The steps include: Growing a single crystal silicon material to form a silicon substrate, wherein the silicon substrate comprises a front surface and a back surface that are relatively distributed, and an oxygen concentration in the silicon substrate is lower than 5 ppma; forming an epitaxial layer on the front side of the silicon substrate by using an epitaxial process; A front device structure is formed on a side of the epitaxial layer away from the silicon substrate.

2. The method for forming a fast recovery diode device according to claim 1, characterized in that: The specific steps of growing single crystal silicon material and forming a silicon substrate include: The silicon substrate is formed by growing single crystal silicon material using a magnetron Czochralski method.

3. The method for forming a fast recovery diode device according to claim 1, characterized in that: The specific steps of growing single crystal silicon material and forming a silicon substrate include: The silicon substrate is formed by growing a single crystal silicon material using a zone melting method.

4. The method for forming a fast recovery diode device according to claim 3, characterized in that: The specific steps of growing a single crystal silicon material by a zone melting method and forming the silicon substrate include: A single crystal silicon material is grown in a reaction chamber by adopting a zone melting method, and a doping source gas is simultaneously transmitted to the reaction chamber to form the silicon substrate including doped ions.

5. The method for forming a fast recovery diode device according to claim 1, characterized in that: The size of the silicon substrate is 6 inches.

6. A fast recovery diode device, characterized in that: include: A silicon substrate, comprising a front side and a back side that are relatively distributed, wherein the oxygen concentration in the silicon substrate is lower than 5 ppma; An epitaxial layer, located on the front side of the silicon substrate; The front device structure is located on the surface of the epitaxial layer facing away from the silicon substrate.

7. The fast recovery diode device according to claim 6, characterized in that: The oxygen concentration in the silicon substrate is lower than 0.2 ppma.

8. The fast recovery diode device according to claim 6, characterized in that: The size of the silicon substrate is 6 inches.

9. The fast recovery diode device according to claim 6, characterized in that: The silicon substrate is a melting zone silicon substrate.

10. The fast recovery diode device according to claim 6, characterized in that: The silicon substrate is a magnetron CZ silicon substrate.

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