A lateral rc-igbt device structure to eliminate negative resistance effect

Abstract

The present application provides a kind of transverse RC-IGBT device structure of eliminating negative resistance effect.The transverse RC-IGBT device compared with in traditional transverse IGBT device, there is oxide isolation region at the center of the drift region of device, and there is a low-doped silicon region inside the oxide isolation region.Due to the isolation effect of the above oxide, the traditional IGBT region is below the oxide, so the bipolar current of forward conduction mode can be normally turned on, and there is no negative resistance effect.The freewheeling diode region is above the oxide, so the bipolar current of reverse conduction mode can be normally turned on.By adjusting the proportion of the area above and below the oxide, the performance distribution of IGBT and freewheeling diode can be adjusted.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically, to a lateral RC-IGBT device structure that eliminates the negative resistance effect. Background Technology

[0002] A lateral insulated-gate bipolar transistor (LIGBT) is a power device compatible with CMOS technology, characterized by its ability to control the switching on and off of large currents via voltage. Due to increasing demands for chip size and power density, the reverse-conducting lateral insulated-gate bipolar transistor (RC-LIGBT) was developed. RC-LIGBT devices have both forward and reverse current conduction capabilities, thus eliminating the need for an additional parallel freewheeling diode in practical applications.

[0003] During the initial forward conduction phase, traditional RC-LIGBTs exhibit a negative resistance effect due to the delay in the appearance of hole current, which threatens the stability of multiple RC-LIGBTs used in parallel. Therefore, a method to eliminate the negative resistance effect is needed.

[0004] In forward blocking mode, traditional RC-LIGBTs mainly rely on the depletion of the drift region to bear the electric field, resulting in a low withstand voltage level. Etching and filling oxide trenches within the drift region is a method to improve the withstand voltage. This method uses oxide to bear the electric field and smooths out the electric field line distribution, making it an effective approach. Summary of the Invention

[0005] The main objective of this invention is to propose a lateral RC-IGBT device structure that eliminates the negative resistance effect, thereby solving the problem of negative resistance in conventional RC-IGBTs and improving device reliability. Compared with conventional lateral IGBT devices, this lateral RC-IGBT device has an oxide isolation region at the center of the drift region, and within this oxide isolation region is a lightly doped silicon region. Due to the isolation effect of the oxide, the conventional IGBT region is below the oxide, thus allowing normal conduction of bipolar current in forward conduction mode without the negative resistance effect. The freewheeling diode region is above the oxide, thus allowing normal conduction of bipolar current in reverse conduction mode. By adjusting the ratio of the areas occupied above and below the oxide, the performance distribution of the IGBT and the freewheeling diode can be adjusted.

[0006] Preferably, the RC-LIGBT device has a cell width of 17 μm and an active region depth of 25 μm.

[0007] Preferably, the oxide trench depth of the RC-LIGBT device is 20 μm.

[0008] Preferably, the thickness of the sidewalls and bottom of the oxide trench in the RC-LIGBT device is 2 μm.

[0009] Preferably, the doping concentration of the ion-implanted N-type cathode region and P-type anode region is 1×10⁻⁶. 18 cm -3 .

[0010] The beneficial effects of this invention are as follows: because the oxide trenches isolate the IGBT region and the freewheeling diode region of the device, the proposed RC-LIGBT does not have a negative resistance effect during the initial forward conduction stage. Furthermore, the presence of the oxide trenches is beneficial to improving the device's withstand voltage level. Attached Figure Description

[0011] Figure 1 A schematic diagram of a traditional RC-LIGBT structure is shown;

[0012] Figure 2 A schematic diagram of the RC-LIGBT structure designed based on the present invention is shown;

[0013] Figure 3 The selected SOI substrate;

[0014] Figure 4 The product obtained in step ③;

[0015] Figure 5 This is the product obtained in step ④. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings.

[0017] Traditional RC-LIGBT structure, such as Figure 1 As shown, the RC-LIGBT semi-cell structure proposed in this invention is as follows: Figure 2 As shown, compared to traditional RC-LIGBTs, the RC-IGBT proposed in this invention differs in that it uses oxide to isolate the IGBT region and the freewheeling diode region. For example... Figures 3-5 As shown, the specific manufacturing steps for its back structure are as follows:

[0018] ①. An SOI substrate was selected, with a cell width of 17 μm and a silicon film thickness of 25 μm above the SOI; the N-drift region 1 concentration was 5.0 × 10⁻⁶. 14 cm -3 The gate oxide layer thickness is 0.05 μm;

[0019] ②. Etching and oxidation form trenches, which are respectively formed into gate oxide trenches and drift region trenches.

[0020] ③. Fill the gate oxide trench with polycrystalline silicon as an electrode, and use chemical vapor deposition to generate a silicon thin film in the drift region trench to form N-drift region 2.

[0021] ④. An active region with a Gaussian distribution on the emitter side and a P-type collector region and an N-type buffer layer on the collector side are formed by ion implantation.

[0022] ⑤. Fabrication of electrodes.

[0023] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. It should be noted that the above descriptions are merely specific embodiments of this invention and do not limit the invention. Any modifications and optimizations made within the spirit and principles of this invention should be covered by the claims of this invention.

Claims

1. A lateral RC-IGBT device structure for eliminating negative resistance effect, characterized in that, An oxide isolation region is set between the N-buffer layer and the P-body region at the top of the drift region of a traditional lateral IGBT device. The isolation region is in the shape of a trench. The N-drift region is below the oxide (1) and the N-drift region is above the oxide (2). Both regions are low-doped regions. Below the N-drift region (1) is the SOI layer, and below the SOI layer is the P-substrate; a P-type anode region is formed by ion implantation on the emitter side of the N-drift region (2), and an N-type cathode region is formed by ion implantation on the collector side of the N-drift region (2).

2. The lateral RC-IGBT device structure for eliminating negative resistance effect according to claim 1, characterized in that: The cell width of the lateral RC-IGBT device is 10~50μm, and the active region depth is 5~40μm.

3. The lateral RC-IGBT device structure for eliminating negative resistance effect according to claim 1, characterized in that: The oxide trench depth of the lateral RC-IGBT device is 10~20μm.

4. The lateral RC-IGBT device structure for eliminating negative resistance effect according to claim 1, characterized in that: The thickness of the sidewalls and bottom of the oxide trench of the lateral RC-IGBT device is 1~5μm.

5. The lateral RC-IGBT device structure for eliminating negative resistance effect according to claim 1, characterized in that: The doping concentration of the ion-implanted N-type cathode region and P-type anode region is 1×10⁻⁶. 18 cm -3 above.

6. The lateral RC-IGBT device structure for eliminating negative resistance effect according to claim 1, characterized in that: The material of the N-drift region (2) is silicon.

7. The lateral RC-IGBT device structure for eliminating negative resistance effect according to claim 1, characterized in that: The oxide is mainly composed of SiO2.

8. The lateral RC-IGBT device structure for eliminating negative resistance effect according to claim 1, characterized in that: The SOI layer is mainly composed of SiO2.

9. The lateral RC-IGBT device structure for eliminating negative resistance effect according to claim 1, characterized in that: The RC-IGBT device has a cell width of 17μm and an active region depth of 25μm.

10. The lateral RC-IGBT device structure for eliminating negative resistance effect according to claim 1, characterized in that: The oxide trench depth of the RC-IGBT device is 20 μm.

Images