JPH07169952A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve withstand voltage by extending a depletion layer to the circumferential part along the region, having different conduction type, which is provided on the surface region located directly under the temperature detecting element of a semiconductor substrate. CONSTITUTION:Directly under the temperature detecting element, to be provided in the vicinity of the circumferential part of the semiconductor substrate same as the main semiconductor element, a region having the different conductive type is provided. The above-mentioned temperature detection element is a diode. A p-region 13 is formed on the surface layer of the n base layer 1 directly under the n<+> region 11 and the p<+> region 12 of a temperature detection diode. The p-region 13 is formed in the same process as the p-base region 2 of an IGBT. Consequently, as the depletion layer is expanded to an n layer by the application of inverse potential between the p-base region 2 and the n<-> base layer 1, the curvature of the edge face of the depletion layer becomes small, and the lowering of withstand voltage of the main IGBT can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which a temperature detecting function for protecting a main semiconductor element such as a power switching device is added to the main semiconductor element.

[0002]

2. Description of the Related Art In order to prevent a main semiconductor element from being destroyed by a temperature rise due to a steady loss and a switching loss due to a main current, a diode is provided on a semiconductor substrate of the element. It is known to detect a temperature rise from the increase and take measures such as cutting off the main current. FIG. 2 shows such a semiconductor device. An insulated gate bipolar transistor as a main semiconductor element has a p base region 2 on a surface layer on one side of an n ⁻ base layer 1 and a surface layer of the p base region 2. has n ⁺ source region 3, p base region 2 n ⁺ source region 3 and the n ^- gate oxide film 4 over the region between the exposed surface of the base layer 1
The gate electrode 5 is provided via the. Source terminal S
The source electrode 6 connected to is commonly contacted with the n ⁺ source region 3 and the p base region 2. the n ^- on the other side of the base layer 1 p ⁺ drain layer 8 is present through the n ⁺ buffer layer 7, contact the p ⁺ drain layer 8 drain electrode 9 connected to the drain terminal D to the . The temperature detecting diode is formed on the exposed surface of the n ⁻ base layer 1 by the insulating film 10
N ⁺ region 11 and p of the polycrystalline silicon layer provided via
⁺ Consists regions 12., n ⁺ one the impurity concentration of the region 11 and p ⁺ region 12 1 × 10 ⁴ cm - ² are below. The electrodes 23 and 24 to which the terminals 21 and 22 are respectively connected are in contact with the n ⁺ region 11 and the p ⁺ region 12.

In a normal switching operation, when a voltage higher than a threshold value is applied to the gate electrode 5, electrons are injected from the n ⁺ source region 3 into the n ⁻ base layer 1 and the n ⁺ buffer layer 7. Since a positive voltage is applied to the drain electrode 9, holes are injected from the p ⁺ drain layer 8 and the built-in p ⁺ drain layer 8, n ⁺ buffer layer 7 and n ⁻ base layer 1 , P base region 2, and the IGBT is turned on.

When the IGBT is operated at a constant frequency, heat is generated in the semiconductor substrate due to switching loss and steady loss, and the temperature of the entire n ⁻ base layer 1 rises. This temperature rise can be detected by shifting the forward direction IV characteristic curve of the temperature detecting diode shown in FIG. 3 from the line 31 at a low temperature to the line 32 at a low saturation voltage. Alternatively, the point when the leakage current is low at a constant voltage of the reverse direction IV characteristic of the temperature detection diode shown in FIG.
It can be detected by increasing from 41 and moving to point 42. Further, if the temperature detection diode has the avalanche characteristic, in the reverse IV characteristic shown in FIG. 5, the avalanche voltage rises from the line 51 when the temperature is low and moves to the line 52. The main semiconductor element can be protected by detecting such a change and operating a control circuit connected to the terminals 21 and 22, such as cutting off the main current.

[0005]

The temperature detecting diode cannot be accurately detected if it is placed not on the same semiconductor substrate as the semiconductor element but on the circuit board or the like separately from the element. However, if the temperature detection diode is incorporated in the same semiconductor substrate, a parasitic thyristor is formed, and this parasitic thyristor may malfunction, resulting in latch-up breakdown. Therefore, as shown in FIG. 2, the temperature detection diode needs to be electrically insulated by the insulating film 10 on the n ⁻ base layer 1.

However, the temperature detection diode made of polycrystalline silicon as shown in FIG. 2 is arranged close to the periphery of the substrate in order to effectively utilize the semiconductor substrate area. It is not possible to form a peripheral breakdown voltage structure that expands a depletion layer such as a ring. Therefore, the curvature of the end face of the depletion layer on the surface of the n ⁻ base layer 1 becomes tight, and the breakdown voltage is lowered.

An object of the present invention is to solve this problem and to install a temperature detecting element such as a temperature detecting diode on a semiconductor substrate so as not to affect characteristics such as withstand voltage of a main semiconductor element. To provide.

[0008]

In order to achieve the above object, the present invention provides a temperature detecting device comprising a plurality of regions of a semiconductor layer formed on a surface of a semiconductor substrate of a main semiconductor element via an insulating film. In a semiconductor device having an element, it is assumed that a region having a different conductivity type is provided in a surface layer of a semiconductor substrate immediately below an element for temperature detection. Alternatively, it is assumed that an electrode of the main semiconductor element provided on the same surface of the semiconductor substrate is connected to any region of the temperature detecting element. It is effective that the temperature detecting element is a diode in which the p-type region and the n-type region are adjacent to each other in a plane parallel to the semiconductor substrate surface.

[0009]

If a region of different conductivity type is formed in the surface layer of the semiconductor substrate immediately below the temperature detecting element provided near the peripheral portion of the semiconductor substrate, the depletion layer in the surface layer of the substrate moves toward the peripheral portion along the region. Since it stretches and acts like a guard ring, the breakdown voltage is improved. Alternatively, if any region of the temperature detecting element and the main electrode are connected to have the same potential as the main electrode, the depletion layer on the substrate surface is extended toward the peripheral portion due to the potential of the region and the field plate is affected. Since it has the same function as, the breakdown voltage is improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, which is shown in FIG.
The same parts as those in FIG. Different from Fig. 2, n ⁺ region 11 and p ⁺ region of the temperature detection diode
A p region 13 is formed in the surface layer of the n ⁻ base layer 1 immediately below 12. This p region 13 can be formed in the same step as the p base region 2 of the IGBT. As a result, p base region 2 and n ⁻
By applying a reverse voltage between the base layers 1, n ⁻
Since the depletion layer spreading in the layer extends along the p region 12, the curvature of the end surface of the depletion layer becomes small, and the breakdown voltage of the main IGBT is prevented from lowering.

In another embodiment shown in FIG. 6, since the n ⁺ region 11 of the temperature detecting diode is connected to the source electrode 6 by the conductive wire 14, the depletion layer extends toward the peripheral side of the substrate and the end face of the depletion layer is formed. The curvature is reduced to prevent the breakdown voltage of the main IGBT from being lowered.

[0012]

According to the present invention, different conductivity type regions are provided immediately below the temperature detecting element provided in the vicinity of the peripheral portion of the same semiconductor substrate as the main semiconductor element, or one area of the temperature detecting element is mainly formed. By connecting to the electrodes of the semiconductor element, the depletion layer extending from the main semiconductor element can be extended toward the periphery of the substrate. As a result, the curvature of the end face of the depletion layer was reduced, and a semiconductor device with a temperature detecting function was obtained in which the breakdown voltage did not decrease due to the temperature detecting element formation.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional IGBT with a temperature detecting function.

FIG. 3 is a forward current / voltage characteristic diagram of the temperature detection diode at room temperature and at high temperature.

FIG. 4 is a reverse current / voltage characteristic diagram of the temperature detection diode at room temperature and at high temperature.

FIG. 5: Avalanche characteristic diagram of temperature detection diode at room temperature and high temperature

FIG. 6 is a sectional view of a semiconductor device according to another embodiment of the present invention.

[Explanation of symbols]

1 n ^- base layer 2 p base region 3 n ⁺ source region 4 gate oxide film 5 gate electrode 6 source electrode 7 n ⁺ buffer layer 8 p ⁺ drain layer 9 drain electrode 10 insulating film 11 n ⁺ region 12 p ⁺ region 13 p Area 14 conductor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 27/08 331 B 9170-4M 35/00 S

Claims (3)

[Claims] 1. A main semiconductor element having a detection element composed of a plurality of regions of a semiconductor layer formed on the surface of a semiconductor substrate via an insulating film, wherein the surface of the semiconductor substrate immediately below the temperature detection element. A semiconductor device, wherein layers are provided with regions having different conductivity types. 2. A semiconductor device having a plurality of regions of a semiconductor layer formed on a surface of a semiconductor substrate of a main semiconductor device via an insulating film, wherein the semiconductor is provided in one of the regions of the temperature detecting device. A semiconductor device, wherein electrodes of a main semiconductor element provided on the same surface of a substrate are connected. 3. The semiconductor device according to claim 1, wherein the temperature detecting element is a diode in which a p-type region and an n-type region are adjacent to each other in a plane parallel to the substrate surface.