JPS58132968A - Semiconductor device - Google Patents

Abstract

PURPOSE:To suppress dependency of clip voltage on temperature by forming separately from base region a high concentration region within collector region. CONSTITUTION:An N<-> collector region 2 is totally spreading just below a P base region 4, and a withstand voltage of a clip voltage VA is determined by a distance between an N<+> region 3 internally existing in the N<-> collector region 2 just below the P base region 4 and the N<-> collector region 2 up to the P base region 4. Since a clip voltage VA is set within a semiconductor substrate, it is not effectuated by the surface, improving reliability. In addition, since a high concentration region to be formed in the collector region is isolated from the base region, dependency of clip voltage on temperature can be suppressed.

Description

[Detailed Description of the Invention] This invention improves the secondary breakdown resistance (E, /l, ) of power transistors related to semiconductor devices, especially electronic ignition devices (igniters) used in bicycles, motorcycles, etc. It is something.

In general, in order to increase this secondary breakdown needle t (E, /b) or to protect the transistor from surge voltage, a well-known method is to connect a clip diode between the collector and base. There is.

Figure 1 shows the equivalent circuit of a monolithically built-in Zener diode Darlington power transistor. In this figure, Q is a transistor for the front stage (drive), and Q2 is a transistor for the rear stage (output). D is a diode for the purpose of dissipating the energy caused by the transistor Q when reversely connected, and Rt and Rz are resistors connected for the purpose of stabilizing leakage current between the emitter and base. D is a Zener diode for a clip built-in for the purpose of increasing the number of secondary breaking needles 1k (E-7b). This Zener diode DA is designed to break down at a value lower than the collector-emitter sustaining breakdown voltage VC (llt18) of the transistor itself. Furthermore, the action of this Zener diode D will be explained.

In the crane transistor eveninger circuit, the power transistor is cut off by the applied voltage Vce, and then
When a hexagonal signal is input to the pace, it turns on and the collector current increases. When the pace current is then turned off, a high kickback voltage is applied to the transistor due to the energy stored in the primary side of the ignition coil. The operating point at this time, in the case of no Zener diode D, is likely to leave the transistor's Yet (fflυ dust) cage and go out of the safe operating area. When the Zener diode D is included, the kickback voltage is flipped by the breakdown voltage V of the Zener diode DA, so the operating point becomes relatively low and the secondary breakdown resistance ( E, /b) can be increased.

Zener diode D with the above 45 effects, ★
A conventional die structure for a monolithically integrated Darienton power transistor is shown in FIG.

In this figure, 1 is an N+ collector region, 2 is an N- collector region, 3 is an N region formed directly below the pace of the transistor Q to form the Zener diode O1, and 4 is a P pace of the transistor Q1. area, 5
is the N+ emitter region of the transistor Q, 6 is the N+ emitter region of the transistor Q, 7 is also a pace electrode, and 8 is an internal wiring connecting the N+ emitter region 5 of the transistor Qs and the pace electrode 7 of the transistor Q2. , 9 is an emitter electrode, and 1o is a collector electrode. Further, 11 is a passivation film that protects the surface of each junction.

Figure 3 is a cross-sectional profile diagram taken along line A-A' of the conventional structure shown in Figure 2, and shows examples of each area in the profile of the built-in part of the conventional Zener diode D. and the surface concentration Ns of P pace region 4 =
2 x 10"atoms/cm".

Depth x J = 20 pm, the N region 3 is formed by diffusion before the formation of the P pace region 4, and the P base region 4
The concentration directly below is lx 10"atoms/cm", N
- Concentration of collector region 2: 1.2 x 10I4 atoms
The distance until it becomes equivalent to "s/am" is 10 μm.

The distance from directly below the P pace region 4 to the N+ collector region 1 is 60 μm.

In such a profile, the breakdown voltage vA of the Zener diode OA is determined by the resistivity of the highest concentration portion of the N region 3 directly below the P space region 4.

However, the conventional configuration described above has the following drawbacks. The song @I in FIG. 4 shows the physical properties of vA (clip voltage) - T and (ambient temperature) of the transistor with built-in Zener diode ROM shown in FIG. 2 above. As shown in FIG. 4, the positive temperature dependence is extremely large. The permissible range of clipping voltage vA is determined by the relationship between the lower limit and the secondary output voltage of the ignition coil, and the upper limit based on the secondary breakdown resistance (E
s/b). This relationship also applies to the entire temperature range (-30°C to 13°C) loaded on the igniter.
0° C.), it is necessary to narrow down the range of the clip voltage V at room temperature very narrowly.

Further, in practical use, the Zener diode D is selected based on the correlation between low temperature characteristics, high temperature characteristics, and room temperature characteristics, which may cause problems in actual use due to variations.

This invention has been made in order to eliminate the above-mentioned drawback (temperature dependence of clipping voltage vA) of the transistor with a built-in Zener diode. This invention will be explained below.

FIG. 5 is a structural diagram showing one embodiment of the present invention. 6th
The figure is a profile diagram of a cross section taken along the line B-B' in FIG. 5, and the same reference numerals indicate the same regions.

In this embodiment, the basic difference from the conventional structure shown in FIG. N+ region 3' inherent in N- collector region 2 of
and the distance lK of N-collector region 2 to P pace region 4
The reason is that the withstand pressure is determined. Other details are the same as in Figure 2.

The effects of this invention include temperature changes in resistivity (or amount of doped impurities) of a semiconductor substrate, relationship between resistivity and breakdown voltage,
This can be explained by the relationship between the specific resistance and the width of the depletion layer depending on the applied voltage. I x 10” atoms/Cm” (ρ=5Ω
am ) is 3Ωcm at -30℃, +150”CK
Changes to OΩeffl. Therefore, the withstand voltage is 270v
It varies up to ~5oov.

The present invention aims to solve the conventional drawbacks by a method that limits the breakdown voltage value and the extension K of the depletion layer.

At this time, the withstand voltage value V is Here, xl: The theoretical width of the depletion layer at the time of pre-Kudawan ■B: Theoretical break-a-one value Wc: Practical width of high resistance layer This determines the withstand pressure.

In this case, if the resistance is temperature dependent and the value V changes, the temperature change in V is limited because the increase in resistance is proportional to the increase in Xml.

To give an example of numerical values, the distance Wc from the C-B junction to the N+ high concentration region Wc = 15 μm, the concentration of the N− reflector region 2 is the same as the collector concentration 1.2 × 10” atoms/
am” (ρ=60Ωcm), -30℃~+
Change in ρ at 150°C from 40ΩCm to 100Ωcm.

The change in XaN is lOO~150 μm. At this time, the maximum change in breakdown voltage value V is 300v to 380v, which is a significant improvement compared to conventional products. In addition, this structure has a clip voltage V
Since the timing is set inside the semiconductor substrate, it is not affected by the surface and has good reliability, which is shown by the curved line in FIG.

As described in detail above, the present invention has the advantage that the high concentration region formed in the collector region is formed apart from the base region, so that the temperature dependence of the clip voltage can be suppressed.

[Brief explanation of drawings]

Figure 1 is an equivalent circuit diagram of a 17-ton power transistor with a built-in clip diode, Figure 2 is a sectional view showing the structure of a conventional semiconductor device, Figure 3 is a cross-sectional view showing the structure of a conventional semiconductor device, and Figure 3 is A-A in Figure 2.
The profile V of the cross section along the line, FIG. 4 shows the temperature dependence of the clipping voltage vA, FIG. B-B'
FIG. 3 is a profile diagram of a cross section taken along the AIUC. In the figure, 1 is the N+ collector area, 2+! N- collector area, 3 is N area, 3゛ is N+ area 4 (home P base area,
5 is the N+ emitter region of the transistor Q, 6 is the N+ emitter region of the transistor Q, T is the base electrode, 8 is the internal wiring, 9 & emitter electrical connection, 10 is the collector electrode,
No. 11 1) (Tsivation membrane. In addition, the same reference numerals in the figure are the same and the parts corresponding to number i are shown. Agent Shin Kuzuno - (1 other person) - Hekoto) - 12 Procedure amendment Written by Mr. Commissioner of the Patent Office! , ! *(Display of 1 = Tokugansho 1!?-1
@18141, Title of the invention: Tei conductor device 3, Relationship with the person making the amendment fT- Patent applicant: Address: 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601): Jinhachi Katayama, Representative of Mitsubishi Electric Corporation Part 4, Agent Address: 2-2-3-5 Marunouchi, 111-ku, Chiyo, Tokyo, Detailed Description of the Invention in the Specification Subject to Amendment and Drawing 6, Contents of the Amendment (1) Page 2 of the Specification, Page 3 Correct the line ``bicycle'' to ``car.'' (2) Also on page 4, line 11, 'P base region of fQt,'
The statement "P pace region of Ql-Qt," is corrected. (3) Correct Figure 2 as shown in the attached sheet. that's all

Claims (1)

[Claims] a collector region having one conductivity type, a pace region formed in the collector region and having the opposite conductivity type, a first emitter region formed in the base region and having the same conductivity type as the collector region; 2 emitter regions, having the same conductivity type as the collector region in a collector region immediately below the base region around the first emitter region, and having the same conductivity type as the collector region, and the second emitter region and the pace region and forming a highly doped region formed at a distance from the pace region to be reached by a depletion layer extending from the collector-base junction at a voltage lower than a collector-emitter sustaining voltage of the transistor comprising the collector region; A semiconductor device characterized in that a high voltage applied to a collector region and an emitter region of a transistor is clipped by reach-through voltage of the high concentration region.