Voltage control type thyristor and preparation method of voltage control type thyristor

Abstract

The invention relates to the technical field of semiconductors, and discloses a voltage control type thyristor and a preparation method of the voltage control type thyristor, the voltage control type thyristor comprises a P-type emitter region, an N-type drift region, a first P well region, a second P well region and an N + type emitter region which are sequentially arranged from an anode to a cathode, the second P well region is located at the end part of the first P well region, and the doping concentration of the second P well region is greater than that of the first P well region. The threshold voltage and the conduction characteristic of the thyristor are decoupled by introducing the second P well region, that is, the threshold voltage of the device is mainly regulated and controlled by the doping concentration of the second P well region, and the conduction characteristic depends on the doping concentration of the first P well region.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a voltage-controlled thyristor and a method for preparing the voltage-controlled thyristor. Background Art

[0002] MOS-controlled thyristor (MCT) is a voltage-controlled power device, which is widely used in pulse discharge systems as a high-voltage and high-current switch. MCT devices control the conduction and shutdown of thyristors through the MOS gate, and have the advantages of high input impedance, low driving power and high power handling capability. MCT devices play a key role in modern power electronics, industrial control, new energy, transportation and other fields. Figure 1 The figure shows the structure of a traditional MCT device. The front structure of the traditional MCT device adopts a triple diffusion process. Since the emitter injection efficiency of the NPN transistor on the cathode side of the device strongly depends on the ratio of the doping concentration of the N+ region / P well region (ie, P-well region), for example, for the NPN transistor, the ratio Therefore, in general, in order to ensure the low on-state voltage drop and strong current-carrying capacity of the device, the doping concentration of the P-well region of the traditional MCT device is generally low, resulting in a low threshold voltage of the MCT device (generally around 2V). When used in the field of power electronics, the MCT device is prone to false triggering, which is not conducive to the promotion and application of MCT devices. Summary of the invention

[0003] The object of the present invention is to provide a voltage-controlled thyristor and a method for preparing a voltage-controlled thyristor, which decouples the threshold voltage and conduction characteristics of the thyristor by introducing a second P-well region, that is, the threshold voltage of the device is mainly regulated by the doping concentration of the second P-well region, and the conduction characteristics depend on the doping concentration of the first P-well region.

[0004] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a voltage-controlled thyristor, which includes: a P-type emitter region, an N-type drift region, a first P-well region and a second P-well region, and an N+ type emitter region arranged in sequence from an anode to a cathode, wherein the second P-well region is located at an end of the first P-well region, and the doping concentration of the second P-well region is greater than the doping concentration of the first P-well region.

[0005] Preferably, the doping concentration of the first P-well region is lower than a preset doping concentration.

[0006] Preferably, the peak doping concentration of the first P-well region is 1E17-3E17cm -3 The peak doping concentration of the second P-well region is 2E17-5E17cm-3 .

[0007] Preferably, the junction depth of the first P-well region is 3-8 μm, and the junction depth of the second P-well region is 0.2-2 μm.

[0008] Preferably, the doping elements of the first P-well region and the second P-well region are boron and aluminum. Preferably, the voltage-controlled thyristor further comprises: an anode; a cathode; a gate and a gate oxide layer; and an N-type buffer region located between the P-type emitter region and the N-type drift region.

[0009] Preferably, the voltage-controlled thyristor is a MOS-controlled thyristor, a base resistance-controlled thyristor, or an emitter-switched thyristor.

[0010] Preferably, in the case where the voltage-controlled thyristor is a MOS-controlled thyristor, the MOS-controlled thyristor further includes: an N-type emitter region, located on both sides of the N+-type emitter region; and a P-type cathode region, located at the upper part of the boundary area between the N-type emitter region and the N+-type emitter region and in contact with both the gate and cathode of the MOS-controlled thyristor.

[0011] Through the above technical solution, the present invention creatively sets the P-well region in the voltage-controlled thyristor as a first P-well region and a second P-well region, wherein the second P-well region is located at the end of the first P-well region, and the doping concentration of the second P-well region is greater than the doping concentration of the first P-well region. Thus, the introduction of the second P-well region decouples the threshold voltage and conduction characteristics of the thyristor, that is, the threshold voltage of the device is mainly regulated by the doping concentration of the second P-well region, and the conduction characteristics depend on the doping concentration of the first P-well region.

[0012] A second aspect of the present invention provides a method for preparing a voltage-controlled thyristor, the method comprising: using a triple diffusion process to form a front structure of the voltage-controlled thyristor, wherein the front structure comprises a P-type emitter region, an N-type drift region, a first P-well region, and an N+-type emitter region arranged in sequence from an anode to a cathode; using a high-energy ion implantation process to form a second P-well region, wherein the second P-well region is located at an end of the first P-well region, and the doping concentration of the second P-well region is greater than the doping concentration of the first P-well region.

[0013] Preferably, the voltage-controlled thyristor is a MOS-controlled thyristor, a base resistance-controlled thyristor, or an emitter-switched thyristor.

[0014] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings: Figure 1 It is a schematic diagram of the structure of a traditional MCT device; Figure 2 is a schematic diagram of the structure of an MCT provided by an embodiment of the present invention; Figure 3 is a schematic diagram of the structure of a BRT provided by an embodiment of the present invention; and Figure 4 It is a schematic diagram of the structure of an EST provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0016] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0017] An embodiment of the present invention provides a voltage-controlled thyristor, wherein the voltage-controlled thyristor (for example, a MOS-controlled thyristor, a base resistance-controlled thyristor, or an emitter switch thyristor) includes: a P-type emitter region, an N-type drift region, a first P-well region and a second P-well region, and an N+-type emitter region arranged in sequence from an anode to a cathode, wherein the second P-well region is located at an end of the first P-well region, and the doping concentration of the second P-well region is greater than the doping concentration of the first P-well region.

[0018] This embodiment can reasonably regulate the threshold voltage and conduction characteristics of the device, thereby resolving the contradictory relationship between the threshold voltage and conduction characteristics of the voltage-controlled thyristor. The conduction voltage drop and the current carrying capacity in this embodiment mainly depend on the doping concentration of the first P-well region (i.e., P-well 1) below the N+ emitter region, that is, the lower the doping concentration of the P-well 1 region, the lower the conduction voltage drop of the device and the stronger the current carrying capacity; while the threshold voltage mainly depends on the doping concentration of the second P-well region (i.e., the channel region / P-well 2), and the higher the doping concentration of the P-well 2 region, the higher the threshold voltage of the device.

[0019] The voltage-controlled thyristor may be a MOS-controlled thyristor (ie, MCT), a base resistor-controlled thyristor, or an emitter-switched thyristor.

[0020] The structure of the voltage-controlled thyristor is explained and illustrated by three types of embodiments below.

[0021] Embodiment 1 Figure 2FIG. 1 is a schematic diagram of the structure of a MOS controlled thyristor (MCT) provided in one embodiment of the present invention. Figure 2 As shown, the MOS controlled thyristor (i.e., MCT) includes: a P-type emitter region 10, an N-type drift region 20, a first P-well region 30 and a second P-well region 40, and an N+ type emitter region 50 arranged in sequence from the anode to the cathode, wherein the second P-well region 40 is located at the end of the first P-well region 30, and the doping concentration of the second P-well region 40 is greater than the doping concentration of the first P-well region 30.

[0022] The P-well region (i.e., P-well region) of the MCT device is composed of a first P-well region 30 (i.e., Figure 2 The MCT device is composed of two parts: a first P-well region 10 (i.e., P-well 1 region) and a second P-well region 40 (i.e., P-well 2 region, which is in contact with the gate oxide layer under the gate 60). The introduction of the P-well 2 region decouples the threshold voltage and conduction characteristics of the MCT device, that is, the threshold voltage of the device is mainly regulated by the doping concentration of the P-well 2 region, and because the cathode electrons mainly flow downward through the N+ type emitter region 50 (i.e., N+ region) when the MCT is turned on, the conduction characteristics depend on the doping concentration of the P-well 1 region.

[0023] On the basis of the above embodiment, the doping concentration of the first P-well region 30 is lower than the preset doping concentration.

[0024] Since the cathode electrons mainly flow downward through the N+ type emission region 50 (i.e., the N+ region) when the MCT is turned on, when the doping concentration of the P-well 1 region is lower than the doping concentration of the P-well region in the conventional structure MCT device (the doping concentration range is 3E17-6E17cm -3 That is, if the doping concentration of the P-well region in the conventional MCT device is 3E17cm -3 , the preset doping concentration is 3E17cm -3 ), the doping concentration of P-well 1 region can be 1E17cm -3 or 2E17cm -3 , the conduction characteristics of MCT devices are better than those of traditional structures, and a higher threshold voltage (e.g., 5~7V) can be obtained.

[0025] Based on the above embodiments, the peak doping concentration of the first P-well region 30 is 1E17-3E17cm -3 The peak doping concentration of the second P-well region 40 is 2E17-5E17cm -3 In this embodiment, the total doping concentration of the channel region is higher than the corresponding concentration in the conventional MCT device, so that a high threshold voltage can be obtained.

[0026] Based on the above embodiments, the junction depth of the first P-well region 30 is 3-8 μm, and the junction depth of the second P-well region 40 is 0.2-2 μm. In this embodiment, the setting of the junction depth can make the first P-well region 30 mainly located under the N+ emitter region, and make the second P-well region 40 mainly located in the channel region.

[0027] On the basis of the above embodiments, the doping elements of the first P-well region 30 and the second P-well region 40 are boron and aluminum.

[0028] Based on the above embodiments, the MOS controlled thyristor further includes: an anode 70 ; a cathode 80 ; a gate 60 and a gate oxide layer 90 ; and an N-type buffer region 100 located between the P-type emitter region 10 and the N-type drift region 20 .

[0029] On the basis of the above-mentioned embodiments, the MOS-controlled thyristor further includes: an N-type emitter region 110, located on both sides of the N+-type emitter region 50; and a P-type cathode region 120, located at the upper part of the boundary area between the N-type emitter region 110 and the N+-type emitter region 50 and in contact with both the gate 60 and the cathode 80 of the MOS-controlled thyristor.

[0030] Embodiment 2 Figure 3 1 is a schematic diagram of the structure of a base resistor controlled thyristor (BRT) provided in one embodiment of the present invention. Figure 3 As shown, the base resistance controlled thyristor (i.e., BRT) includes: a P-type emitter region 10, an N-type drift region 20, a first P-well region 30 and a second P-well region 40, and an N+ type emitter region 50 arranged in sequence from the anode to the cathode, wherein the second P-well region 40 is located at the end of the first P-well region 30, and the doping concentration of the second P-well region 40 is greater than the doping concentration of the first P-well region 30.

[0031] The P-well region (i.e., P-well region) of the BRT device is composed of a first P-well region 30 (i.e., Figure 2 The BRT device is composed of two parts: a first P-well region 1 (i.e., P-well 1 region) and a second P-well region 40 (i.e., P-well 2 region, which is in contact with the gate oxide layer under the gate 60). The introduction of the P-well 2 region decouples the threshold voltage and conduction characteristics of the BRT device, that is, the threshold voltage of the device is mainly regulated by the doping concentration of the P-well 2 region, and because the cathode electrons mainly flow downward through the N+ type emitter region 50 (i.e., N+ region) when the BRT is turned on, the conduction characteristics depend on the doping concentration of the P-well 1 region.

[0032] On the basis of the above embodiment, the doping concentration of the first P-well region 30 is lower than the preset doping concentration.

[0033] Since the cathode electrons mainly flow downward through the N+ type emission region 50 (i.e., the N+ region) when the BRT is turned on, when the doping concentration of the P-well 1 region is lower than the doping concentration of the P-well region in the conventional structure BRT device (the doping concentration range is 3E17-6E17cm -3 That is, if the doping concentration of the P-well region in the conventional MCT device is 3E17cm -3 , the preset doping concentration is 3E17cm -3 ), the doping concentration of P-well 1 region can be 1E17cm -3 or 2E17cm -3 , the conduction characteristics of the BRT device are better than those of the traditional structure, and a higher threshold voltage (for example, 5~7V) can be obtained.

[0034] Based on the above embodiments, the peak doping concentration of the first P-well region 30 is 1E17-3E17cm -3 The peak doping concentration of the second P-well region 40 is 2E17-5E17cm -3 In this embodiment, the total doping concentration of the channel region is higher than the corresponding concentration in the conventional MCT device, so that a high threshold voltage can be obtained.

[0035] Based on the above embodiments, the junction depth of the first P-well region 30 is 3-8 μm, and the junction depth of the second P-well region 40 is 0.2-2 μm. In this embodiment, the setting of the junction depth can make the first P-well region 30 mainly located under the N+ emitter region, and make the second P-well region 40 mainly located in the channel region.

[0036] On the basis of the above embodiments, the doping elements of the first P-well region 30 and the second P-well region 40 are boron and aluminum.

[0037] Based on the above embodiments, the MOS controlled thyristor further includes: an anode 70 ; a cathode 80 ; a gate 60 and a gate oxide layer 90 ; and an N-type buffer region 100 located between the P-type emitter region 10 and the N-type drift region 20 .

[0038] Embodiment 3 Figure 4 FIG. 1 is a schematic diagram of the structure of an emitter switched thyristor (EST) provided in one embodiment of the present invention. Figure 4As shown, the emitter switch thyristor (i.e., EST) includes: a P-type emitter region 10, an N-type drift region 20, a first P-well region 30 and a second P-well region 40, and an N+ type emitter region 50 arranged in sequence from the anode to the cathode, wherein the second P-well region 40 is located at the end of the first P-well region 30, and the doping concentration of the second P-well region 40 is greater than the doping concentration of the first P-well region 30.

[0039] The P-well region (i.e., P-well region) of the EST device is composed of a first P-well region 30 (i.e., Figure 2 The EST device is composed of two parts: a first P-well region 1 (i.e., P-well 1 region) and a second P-well region 40 (i.e., P-well 2 region, which is in contact with the gate oxide layer under the gate 60). The introduction of the P-well 2 region decouples the threshold voltage and conduction characteristics of the EST device, that is, the threshold voltage of the device is mainly regulated by the doping concentration of the P-well 2 region, and because the cathode electrons mainly flow downward through the N+ type emitter region 50 (i.e., N+ region) when the EST is turned on, the conduction characteristics depend on the doping concentration of the P-well 1 region.

[0040] On the basis of the above embodiment, the doping concentration of the first P-well region 30 is lower than the preset doping concentration.

[0041] Since the cathode electrons mainly flow downward through the N+ type emitter region 50 (i.e., the N+ region) when the EST is turned on, when the doping concentration of the P-well 1 region is lower than the doping concentration of the P-well region in the conventional structure EST device (the doping concentration range is 3E17-6E17cm -3 That is, if the doping concentration of the P-well region in the conventional MCT device is 3E17cm -3 , the preset doping concentration is 3E17cm -3 ), the doping concentration of P-well 1 region can be 1E17cm -3 or 2E17cm -3 , the conduction characteristics of EST devices are better than those of traditional structures, and a higher threshold voltage (e.g., 5~7V) can be obtained.

[0042] Based on the above embodiments, the peak doping concentration of the first P-well region 30 is 1E17-3E17cm -3 The peak doping concentration of the second P-well region 40 is 2E17-5E17cm -3 In this embodiment, the total doping concentration of the channel region is higher than the corresponding concentration in the conventional MCT device, so that a high threshold voltage can be obtained.

[0043] Based on the above embodiments, the junction depth of the first P-well region 30 is 3-8 μm, and the junction depth of the second P-well region 40 is 0.2-2 μm. In this embodiment, the setting of the junction depth can make the first P-well region 30 mainly located under the N+ emitter region, and make the second P-well region 40 mainly located in the channel region.

[0044] On the basis of the above embodiments, the doping elements of the first P-well region 30 and the second P-well region 40 are boron and aluminum.

[0045] Based on the above embodiments, the emitter switch thyristor further includes: an anode 70 ; a cathode 80 ; a gate 60 and a gate oxide layer 90 ; and an N-type buffer region 100 located between the P-type emitter region 10 and the N-type drift region 20 .

[0046] In summary, the present invention creatively sets the P-well region in the voltage-controlled thyristor as a first P-well region and a second P-well region, wherein the second P-well region is located at the end of the first P-well region, and the doping concentration of the second P-well region is greater than the doping concentration of the first P-well region. Thus, the introduction of the second P-well region decouples the threshold voltage and conduction characteristics of the thyristor, that is, the threshold voltage of the device is mainly regulated by the doping concentration of the second P-well region, and the conduction characteristics depend on the doping concentration of the first P-well region.

[0047] Embodiment 4 An embodiment of the present invention provides a method for preparing a voltage-controlled thyristor, the method comprising: using a triple diffusion process to form a front structure of the voltage-controlled thyristor, wherein the front structure comprises a P-type emitter region, an N-type drift region, a first P-well region, and an N+-type emitter region arranged in sequence from an anode to a cathode; using a high-energy ion implantation process to form a second P-well region, wherein the second P-well region is located at an end of the first P-well region, and the doping concentration of the second P-well region is greater than the doping concentration of the first P-well region.

[0048] In this embodiment, a triple diffusion process can be used to form the front structure of a voltage-controlled thyristor (e.g., an MCT device), and the P-well 2 region can be implemented using a high-energy ion implantation process alone. The triple diffusion process is a traditional MCT process, and the process flow of the present invention can be compatible with the traditional MCT process. Alternatively, in another embodiment, the triple diffusion structure of a traditional voltage-controlled thyristor (e.g., an MCT device) is no longer used, but the gate oxide layer and the polysilicon gate are formed after the front structure of the voltage-controlled thyristor (e.g., an MCT device) is finalized.

[0049] Based on the above fourth embodiment, the doping concentration of the first P-well region is lower than a preset doping concentration.

[0050] Based on the above embodiments, the peak doping concentration of the first P-well region is 1E17-3E17cm -3 The peak doping concentration of the second P-well region is 2E17-5E17cm -3 .

[0051] Based on the above embodiments, the junction depth of the first P-well region is 3-8 μm, and the junction depth of the second P-well region is 0.2-2 μm.

[0052] Based on the above embodiments, the doping elements of the first P-well region and the second P-well region are boron and aluminum. Based on the above embodiments, the voltage-controlled thyristor further includes: an anode; a cathode; a gate and a gate oxide layer; and an N-type buffer region located between the P-type emitter region and the N-type drift region.

[0053] On the basis of the above embodiments, the voltage-controlled thyristor is a MOS-controlled thyristor, a base resistor-controlled thyristor, or an emitter-switched thyristor.

[0054] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0055] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0056] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A voltage-controlled thyristor, characterized in that: The voltage controlled thyristor comprises: The P-type emitter region, the N-type drift region, the first P-well region and the second P-well region, and the N+-type emitter region are arranged in sequence from the anode to the cathode. The second P-well region is located at an end of the first P-well region, and the doping concentration of the second P-well region is greater than the doping concentration of the first P-well region.

2. The voltage-controlled thyristor according to claim 1, characterized in that: The doping concentration of the first P-well region is lower than a preset doping concentration.

3. The voltage-controlled thyristor according to claim 1, characterized in that: The peak doping concentration of the first P-well region is 1E17-3E17cm -3 The peak doping concentration of the second P-well region is 2E17-5E17cm -3 .

4. The voltage-controlled thyristor according to claim 1, characterized in that: The junction depth of the first P-well region is 3-8 μm, and the junction depth of the second P-well region is 0.2-2 μm.

5. The voltage-controlled thyristor according to claim 1, characterized in that: The doping elements of the first P-well region and the second P-well region are boron and aluminum.

6. The voltage-controlled thyristor according to claim 1, characterized in that: The voltage-controlled thyristor further includes: an anode; a cathode; a gate and a gate oxide layer; and an N-type buffer region located between the P-type emitter region and the N-type drift region.

7. The voltage-controlled thyristor according to claim 1, characterized in that: The voltage-controlled thyristor is a MOS-controlled thyristor, a base resistor-controlled thyristor, or an emitter-switched thyristor.

8. The voltage-controlled thyristor according to claim 7, characterized in that: In the case where the voltage-controlled thyristor is a MOS-controlled thyristor, the MOS-controlled thyristor further includes: an N-type emitter region located on both sides of the N+-type emitter region; and a P-type cathode region located at the upper part of the boundary area between the N-type emitter region and the N+-type emitter region and in contact with both the gate and cathode of the MOS-controlled thyristor.

9. A method for preparing a voltage-controlled thyristor, characterized in that: The preparation method comprises: A front structure of a voltage-controlled thyristor is formed using a triple diffusion process, wherein the front structure includes a P-type emitter region, an N-type drift region, a first P-well region, and an N+-type emitter region arranged in sequence from an anode to a cathode; A second P-well region is formed by a high energy ion implantation process. The second P-well region is located at an end of the first P-well region, and the doping concentration of the second P-well region is greater than the doping concentration of the first P-well region.

10. The preparation method according to claim 9, characterized in that: The voltage-controlled thyristor is a MOS-controlled thyristor, a base resistor-controlled thyristor, or an emitter-switched thyristor.

Images