Semiconductor equipment

Abstract

To provide a semiconductor device with an increased breakdown voltage of a high breakdown voltage region.SOLUTION: A semiconductor device comprises: a high-side drive circuit arranged in a high-side circuit area and for driving a switching element; a field plate in which one end is connected to the high-side drive circuit and the other end is connected to a low-side drive circuit; a transistor formed in a high breakdown voltage termination arranged with the field plate; a separation region for separating a drain of the transistor from the high-side circuit area; and a voltage reduction unit which further reduces a voltage of the field plate in addition to a voltage reduction by the field plate between the one end of the field plate and the separation region.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a semiconductor device.

Background Art

[0002] Conventionally, a gate driver IC that performs on / off control of a switching element using a power semiconductor device such as a MOSFET or an IGBT is known. In this gate driver IC, a field plate is used to obtain high breakdown voltage characteristics (for example, Patent Document 1). A conventional field plate is, for example, a resistive one made of polysilicon of one polarity.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional semiconductor device such as that of Patent Document 1, parasitic elements formed in the field plate region are not particularly considered, and there is room for improvement in the influence of parasitic elements, for example, there is a risk that parasitic elements may be energized in a separation region.

[0005] An object of the present invention is to provide a semiconductor device in which the influence of parasitic elements is improved.

Means for Solving the Problems

[0006] A semiconductor device according to one aspect of the present invention includes a high-side drive circuit arranged in a high-side circuit area for driving a switching element, a field plate with one end connected to the high-side drive circuit and the other end connected to a low-side circuit, a transistor formed in a high-voltage termination on which the field plate is arranged, an isolation region that separates the drain of the transistor from the high-side circuit area, and a voltage reduction section between the one end of the field plate and the isolation region that further reduces the voltage of the field plate in addition to the voltage reduction caused by the field plate. The voltage reduction section reduces the voltage applied to the gate of a parasitic MOS formed in the isolated region, with the field plate as the gate, the drain of the transistor as the source, and the high-side circuit area as the drain. The voltage reduction section is provided between one end of the field plate and the gate of the parasitic MOS, and not between the gate of the parasitic MOS and the other end of the field plate. It is characterized by the following:

[0007] In the semiconductor device according to one embodiment described above, the voltage reduction portion is characterized by being a diode formed between one end of the field plate and the isolation region.

[0008] In the semiconductor device according to one embodiment described above, the transistor is characterized by being a level-shift MOS.

[0009] In the semiconductor device according to one embodiment described above, the field plate is ring-shaped with a spiral shape extending from one end to the other, the high-side circuit area is located inside the ring-shaped field plate, and the low-side circuit area where the low-side circuit is located is located outside the ring-shaped field plate. [Effects of the Invention]

[0011] According to one aspect of the present invention, a semiconductor device can be provided that improves the influence of parasitic elements.

[0012] According to one aspect of the present invention, by having a voltage reduction section between one end of the field plate and the isolation region that reduces the voltage of the field plate, the voltage applied to the isolation region can be reduced, thereby reducing the impact on parasitic elements formed in the isolation region.

[0013] According to one aspect of the present invention, the voltage reduction section is a diode formed between one end of the field plate and the isolation region, which allows the voltage reduction section to be easily incorporated.

[0014] According to one aspect of the present invention, the transistor is a level-shifted MOS, and the invention is applicable when the semiconductor device is a gate driver IC using a level-shifted MOS.

[0015] According to one aspect of the present invention, the voltage reduction unit can prevent current from flowing through the isolated region, which is the space between the drain and source of the parasitic MOS, by reducing the voltage applied to the gate of the parasitic MOS formed in the isolated region. [Brief explanation of the drawing]

[0016] [Figure 1] This is a plan view of a semiconductor device according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view AA' in Figure 1. [Figure 3] This is a cross-sectional view of BB' in Figure 1. [Figure 4] This is a cross-sectional view of CC' in Figure 1. [Figure 5] Figure 1 is a circuit diagram of the semiconductor device 100. [Modes for carrying out the invention]

[0017] A semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings. Note that in the following drawings, the scale and number of components in each structure may differ from the actual structure in order to make the components easier to understand. Also, the polarity of the semiconductor in the following description is an example, and the opposite polarity may also be used.

[0018] FIG. 1 is a plan view of a semiconductor device according to an embodiment of the present invention. The semiconductor device 100 according to an embodiment of the present invention includes a gate driver IC that performs on / off control of a switching element using a power semiconductor device such as a MOSFET or an IGBT. The gate driver IC has a high-side drive circuit that drives a high-side switching element and a low-side drive circuit that drives a low-side switching element.

[0019] The high-side drive circuit of the gate driver IC is arranged in the high-side circuit area 120. The low-side drive circuit of the gate driver IC is arranged in the low-side circuit area 130. The field plate 110 is in an annular shape that winds around from the starting point 112 to the ending point 113 so as to surround the high-side circuit area 120. In FIG. 1, the number of turns of the field plate 110 being wound is a schematic for easy viewing and may be different from the actual number. The field plate 110 is a resistive field plate made of polysilicon. The field plate 110 increases the breakdown voltage of each element included in the semiconductor device 100.

[0020] The field plate 110 that winds in a spiral shape constitutes a high-voltage termination 111. The starting point 112 of the field plate 110 is connected to the high-side drive circuit arranged in the high-side circuit area 120. The ending point 113 of the field plate 110 is connected to the low-side circuit arranged in the low-side circuit area 130. The high-side circuit area 120 is arranged inside the annular field plate 110, and the low-side circuit area 130 is arranged outside the annular field plate 110.

[0021] The semiconductor device 100 has a level - shift MOS 115 that converts an input signal with a low voltage into a high voltage for controlling a high - side drive circuit. The level - shift MOS 115 is provided in the high - voltage - withstand termination 111. The semiconductor device 100 has a separation region 116 that separates the drain of the level - shift MOS 115 from the high - side circuit area 120. A parasitic MOS 117, which is an example of a parasitic element, is formed in this separation region 116.

[0022] Figure 2 is a cross - sectional view taken along the line A - A′ of Figure 1. The level - shift MOS 115 is separated from the high - side circuit area 120 by a separation region 116 made of P - type silicon. The level - shift MOS 115 has a field plate 110 on its upper surface, thereby increasing its voltage withstand.

[0023] Figure 3 is a cross - sectional view taken along the line B - B′ of Figure 1. In the separation region 116, a parasitic MOS 117 is formed with the field plate 110 as the gate, the drain of the level - shift MOS 115 as the source, and the high - side circuit area 120 as the drain. In this embodiment, since the field plate 110 has a diode 200, the voltage applied to the gate of the parasitic MOS 117 can be reduced, preventing the parasitic MOS 117 from being energized. The diode 200 functions as a voltage - reducing part that reduces the voltage of the field plate 110 between the starting point 112 of the field plate 110 and the separation region 116. The diode 200 further reduces the voltage of the field plate 110 in addition to the voltage reduction by the field plate 110.

[0024] On the other hand, if the field plate 110 is a simple resistive field plate without a diode 200, the following problems may occur. For example, if the impurity concentration in the isolation region 116 is too low, the parasitic MOS 117 will turn ON due to the voltage of the field plate 110, and the isolation breakdown voltage will decrease. Conversely, if the impurity concentration in the isolation region 116 is increased to make it more difficult for the parasitic MOS 117 to turn ON, the electric field in the isolation region 116 will become stronger, and the breakdown voltage of the level shift MOS 115 will decrease. According to this embodiment, by having a diode 200, the voltage applied to the gate of the parasitic MOS 117 can be reduced, and the breakdown voltage in the high breakdown voltage region can be increased.

[0025] Figure 4 is a cross-sectional view of CC' in Figure 1. In this embodiment, the field plate 110 is made of N-type polysilicon. The diode 200 can be formed by doping the field plate 110 with P-type impurities between the starting point 112 and the isolation region 116. The voltage reduction section that reduces the voltage of the field plate 110 between the starting point 112 and the isolation region 116 can be any other method used to reduce the voltage of the field plate 110. Also, if the field plate 110 is P-type, the diode 200 may be formed by doping the field plate 110 with N-type impurities.

[0026] Figure 5 is a circuit diagram of the semiconductor device 100 shown in Figure 1. The field plate 110 has a diode 200 between the power supply voltage of the high-side drive circuit and the gate of the parasitic MOS 117. The diode 200 functions as a Zener diode, reducing the voltage applied to the gate of the parasitic MOS 117.

[0027] As explained above, according to this embodiment, the voltage applied to the gate of the parasitic MOS117 can be reduced, thereby increasing the breakdown voltage in the high breakdown voltage region.

[0028] Furthermore, according to this embodiment, the voltage applied to the gate of the parasitic MOS 117 can be reduced by simply providing a diode 200 on the field plate 110.

[0029] Furthermore, according to this embodiment, the method of providing the diode 200 on the field plate 110 is a simple method of doping the field plate 110 with impurities of opposite polarity to the field plate 110, which can reduce the voltage applied to the gate of the parasitic MOS 117.

[0030] (Note 1) Located in the high-side circuit area, the high-side drive circuit drives the switching element, A field plate, one end of which is connected to the high-side drive circuit and the other end of which is connected to the low-side circuit, A transistor formed in a high-voltage termination on which the field plate is arranged, The drain of the transistor is separated from the high-side circuit area by an isolation region, Between one end of the field plate and the isolation region, there is a voltage reduction section that further reduces the voltage of the field plate in addition to the voltage reduction caused by the field plate, A semiconductor device characterized by the following features.

[0031] (Note 2) The voltage reduction section is a diode formed between one end of the field plate and the isolation region. The semiconductor device described in Appendix 1, characterized by the features described herein.

[0032] (Note 3) The aforementioned transistor is a level-shift MOS. A semiconductor device as described in Appendix 1 or 2, characterized by the features described herein.

[0033] (Note 4) The field plate has a ring shape that spirals around from one end to the other end. The high-side circuit area is located inside the ring-shaped field plate. The low-side circuit area where the low-side circuit is located is positioned outside the ring-shaped field plate. A semiconductor device characterized by any one of the appendices 1 to 3.

[0034] (Note 5) The voltage reduction unit reduces the voltage applied to the gate of a parasitic MOS formed in the isolated region, using the field plate as the gate, the drain of the transistor as the source, and the high-side circuit area as the drain. A semiconductor device as described in any one of the appendices 1 to 4, characterized by the features described herein.

[0035] The present invention is not limited to the embodiments described above, and various improvements and design modifications may be made without departing from the spirit of the invention. In addition, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the above description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0036] 100... Semiconductor device, 110... Field plate, 115... Level-shift MOS, 116... Isolation region, 117... Parasitic MOS, 200... Diode

Claims

1. Located in the high-side circuit area, the high-side drive circuit drives the switching element, A field plate, one end of which is connected to the high-side drive circuit and the other end of which is connected to the low-side circuit, A transistor formed in a high-voltage termination on which the field plate is arranged, The drain of the transistor is separated from the high-side circuit area by an isolation region, Between one end of the field plate and the isolation region, there is a voltage reduction section that further reduces the voltage of the field plate in addition to the voltage reduction caused by the field plate, The voltage reduction unit reduces the voltage applied to the gate of the parasitic MOS formed in the isolated region, using the field plate as the gate, the drain of the transistor as the source, and the high-side circuit area as the drain. The voltage reduction section is provided between one end of the field plate and the gate of the parasitic MOS, and not between the gate of the parasitic MOS and the other end of the field plate. A semiconductor device characterized by the following features.

2. The voltage reduction section is a diode formed between one end of the field plate and the isolation region. The semiconductor device according to feature 1.

3. The aforementioned transistor is a level-shift MOS. The semiconductor device according to claim 1 or 2.

4. The field plate has a ring shape that spirals around from one end to the other end. The high-side circuit area is located inside the ring-shaped field plate. The low-side circuit area where the low-side circuit is located is positioned outside the ring-shaped field plate. The semiconductor device according to claim 1 or 2.

Images