Semiconductor device having IGBT and diode

Abstract

A semiconductor device includes: a semiconductor substrate having first and second semiconductor layers; an IGBT having a collector region, a base region in the first semiconductor layer, an emitter region in the base region, and a channel region in the base region between the emitter region and the first semiconductor layer; a diode having an anode region in the first semiconductor layer and a cathode electrode on the first semiconductor layer; and a resistive region. The collector region and the second semiconductor layer are disposed on the first semiconductor layer. The resistive region for increasing a resistance of the second semiconductor layer is disposed in a current path between the channel region and the cathode electrode through the first semiconductor layer and the second semiconductor layer with bypassing the collector region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

FIG. 1 is a cross sectional view showing a semiconductor device according to a first embodiment;

FIGS. 2A to 2C are cross sectional views showing a method for manufacturing the semiconductor device shown in FIG. 1;

FIGS. 3A to 3C are cross sectional views showing another method for manufacturing the semiconductor device shown in FIG. 1;

FIG. 4 is a schematic view showing the semiconductor device and its equivalent circuit;

FIG. 5 is a cross sectional view showing a semiconductor device according to a modification of the first embodiment;

FIG. 6 is a cross sectional view showing a semiconductor device according to a second embodiment;

FIG. 7 is a cross sectional view showing a semiconductor device according to a modification of the second embodiment;

FIG. 8 is a cross sectional view showing a semiconductor device according to a third embodiment;

FIG. 9 is a cross sectional view showing a semiconductor device according to a modification of the third embodiment;

FIG. 10 is a cross sectional view showing a semiconductor device according to a fourth embodiment;

FIG. 11 is a cross sectional view showing a semiconductor device according to a modification of the fourth embodiment;

FIG. 12 is a cross sectional view showing a semiconductor device according to a fifth embodiment;

FIG. 13 is a cross sectional view showing a semiconductor device according to a modification of the fifth embodiment;

FIG. 14 is a cross sectional view showing a semiconductor device according to a comparison of the first embodiment;

FIG. 15 is a graph showing a I-V characteristics of the device shown in FIG. 14.

Claims

1. A semiconductor device comprising: a semiconductor substrate having an IGBT region and a diode region;an IGBT disposed in the IGBT region of the substrate;a diode disposed in the diode region of the substrate; anda resistive region, whereinthe semiconductor substrate has a first side and a second side opposite to the first side,the semiconductor substrate includes a first semiconductor layer having a first conductive type and a second semiconductor layer having the first conductive type,the second semiconductor layer has an impurity concentration higher than an impurity concentration of the first semiconductor layer,the second semiconductor layer is disposed on the first semiconductor layer on the second side in the IGBT region,the IGBT includes a collector region having a second conductive type, a collector electrode, a base region having the second conductive type, an emitter region having the first conductive type, an emitter electrode, a channel region, and a gate electrode,the collector region is disposed on the second semiconductor layer on the second side in the IGBT region,the collector electrode is electrically coupled with the collector region,the base region is disposed in a surface portion of the first semiconductor layer on the first side in the IGBT region,the emitter region is disposed in a surface portion of the base region,the emitter electrode is electrically coupled with the emitter region,the channel region is disposed in a part of the base region between the emitter region and the first semiconductor layer,the gate electrode contacts the channel region through a gate insulation film,the diode includes an anode region having the second conductive type, an anode electrode, and a cathode electrode,the anode region is disposed in a surface portion of the first semiconductor layer on the first side in the diode region,the anode electrode is electrically coupled with the anode region and the emitter electrode,the cathode electrode is disposed on the first semiconductor layer on the second side in the diode region,the cathode electrode is electrically coupled with the collector electrode, andthe resistive region for increasing a resistance of the second semiconductor layer is disposed in a part of the second semiconductor layer, which is arranged in a current path between the channel region in the IGBT region and the cathode electrode in the diode region through the first semiconductor layer and the second semiconductor layer with bypassing the collector region.

2. The device according to claim 1, wherein the diode further includes a high concentration semiconductor region having the first conductive type,the high concentration semiconductor region has an impurity concentration higher than the impurity concentration of the first semiconductor layer,the high concentration semiconductor region is disposed in the diode region between the first semiconductor layer and the cathode electrode, andthe high concentration semiconductor region is electrically coupled with the second semiconductor layer and the cathode electrode.

3. The device according to claim 2, wherein the high concentration semiconductor region provides a cathode region,the high concentration semiconductor region includes first and second high concentration semiconductor regions,the first high concentration semiconductor region has the first conductive type, and the second high concentration semiconductor region has the first conductive type,the first high concentration semiconductor region has an impurity concentration higher than the impurity concentration of the first semiconductor layer,the second high concentration semiconductor region has an impurity concentration higher than the impurity concentration of the first high concentration semiconductor region, andthe first high concentration semiconductor region is disposed on the first semiconductor layer, and the second high concentration semiconductor region is disposed on the first high concentration semiconductor region.

4. The device according to claim 1, wherein the resistive region increases the resistance of the second semiconductor layer to be larger than a resistance of the first semiconductor layer.

5. The device according to claim 1, wherein the resistive region is disposed at a boundary portion of the second semiconductor layer between the IGBT region and the diode region.

6. The device according to claim 1, wherein the resistive region is an insulator in a trench,the insulator in the trench is disposed on the second side of the collector region, andthe insulator in the trench penetrates the collector region, and reaches the second semiconductor layer.

7. The device according to claim 6, wherein the insulator in the trench penetrates the second semiconductor layer, and reaches the first semiconductor layer.

8. The device according to claim 1, wherein the resistive region is a second conductive type semiconductor region in the second semiconductor layer.

9. The device according to claim 1, wherein the resistive region is a low crystallinity region in the second semiconductor layer, andthe low crystallinity region has a crystallinity degree, which is lower than a crystallinity degree of the second semiconductor layer.

10. The device according to claim 1, wherein the resistive region is made of oxide or nitride of the second semiconductor layer.

11. The device according to claim 1, wherein the resistive region is a low impurity concentration region having the first conductive type in the second semiconductor layer, andthe low impurity concentration region has an impurity concentration, which is lower than the impurity concentration of the second semiconductor layer.

12. The device according to claim 1, wherein the resistive region is provided by a part of the first semiconductor layer, which protrudes toward the second semiconductor layer, so that a thickness of a part of the second semiconductor layer becomes smaller than a thickness of another part of the second semiconductor layer.