JPS62145875A - Protecting diode for compound semiconductor device - Google Patents

Abstract

PURPOSE:To accurately control the dielecetric strength of a compound semiconductor device by diffusing a second diffused region thinner in concentration and deeper than a first diffused region, and expanding the depletion layer to a second diffused region when a bias is applied across electrodes of the surface of the first region to break down by punch-through. CONSTITUTION:When a second diffused region 4 is diffused thinner in concentration and deeper than a first diffused region 3 and a bias is applied across electrodes each formed on the surface of the region 3, a depletion layer expands to the second region 4 to break down by punch-through. The depletion layer 5 is longitudinally uniformly expanded from one region 3 to the other region 3 by deeply diffusing the second region 4 more than the first region 3. Thus, since the expanding way of the layer 5 becomes longitudinally uniform, the dielectric strength can be accurately controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a protection diode formed together with a compound semiconductor device in order to improve the surge resistance of the compound semiconductor device.

(b) Conventional technology Compound semiconductor devices, such as gallium-arsenide field effect transistors (hereinafter referred to as GaAsMESFETs), are being put into practical use as microwave band amplification elements with excellent characteristics such as low noise and high gain. is recommended.

However, since the gate of a GaAs MESFET is a Schottky junction, the Schottky junction is easily destroyed when surge energy is applied between the gate and source or between the gate and drain. Therefore, recently, GaAs has been used to
Countermeasures have been taken, such as monolithically integrating AsMESFETs and protection diodes. (For example, IEICE Technical Report 5
SD82-132. Pages 75 to 79 are detailed. ).

By the way, the above-mentioned protection diode is shown in FIG. 3, which includes an N-type diffusion region (33) formed in a GaAs substrate (32) by ion implantation, etc., and one of the N-type diffusion regions (33). A P” type diffusion region (34) formed to connect with the GaAsMESF
It was monolithically integrated, connected between the gate and source of the ET.

(c) Problems to be solved by the invention In the protection diode (31) with a guard-like configuration,
Since the area of the part of the P''N junction formed by the bottom surface of the P'' diffusion region (34) and the N type diffusion region (33) is large, the parasitic capacitance increases and the noise figure (NF ) was causing significant deterioration.

(d) Means for Solving the Problems The present invention has been made in view of the above-mentioned problems, and includes a protection diode (1) for a compound semiconductor device formed on a compound semiconductor substrate (2). A plurality of first diffusion regions (3) of one conductivity type formed in 2) and a second diffusion region (4) of an opposite conductivity type that can be bonded between the first diffusion regions (3) (3). The second diffusion region (4) is diffused to a lower concentration and deeper than the first diffusion region (3), and an electrode provided on the surface of the first diffusion region (3), respectively. The solution is that when the voltage is applied between the two, a depletion layer spreads in the second diffusion region (4), and breakdown occurs due to bunch-through.

(*) Effect of the second diffusion region (4) on the first diffusion region (3)
When the impurity is diffused deeper, the impurity concentration between the first diffusion regions (3) (3) becomes almost uniform, resulting in a depletion layer (5) as shown in FIG.
) (dotted line).

(f) Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the protection diode (1) according to the present invention, and as shown in FIG.
It shows a cross-sectional view of the protection diode (21) connected to the gate 1 (GI) of the ESFET.

As shown in FIG. 1, at least a compound semiconductor substrate (2)
For example, there are two first diffusion regions (3) of one conductivity type (P type) with high impurity concentration formed in a semi-insulating GaAs substrate.

Here, the GaAs substrate (2) is coated with about 5000 silicon oxide film (6) by using, for example, CVD method, and the silicon oxide film (6) corresponding to the P-type first diffusion region (3) is coated.
) is opened and zinc ions (Z, ”) are added at a dose of 1 x 1
Ion implantation was performed under the conditions of 0 "cm-" and acceleration voltage of 100 KeV (7), and two P-type first diffusion regions (3) (3)
The - conductivity type first diffusion region (3) (3
) A second diffusion region (4) of the opposite conductivity type that joins with a part of (
There is an N-type diffusion region).

Therefore, the two P-type first diffusion regions (3) (3) and the N-type second diffusion region (4) form two diodes ( The feature of the present invention is that the second diffusion region (4) is formed of a PNP type and is configured as a gate protection diode (1).
) is diffused to a lower concentration and deeper than the first diffusion region (3), and a bias is applied between the electrodes provided on the two surfaces of the first diffusion region (3). 2
The reason is that the depletion layer spreads and bunches through the diffusion region (4).

That is, here, the silicon oxide film (6) is again coated on the GaAs substrate (2) in the same way, and the silicon oxide film (6) in the region corresponding to the N-type second diffusion region (4) is removed. , ions are implanted into the opening under conditions of a dose of lXl0''cI['' and an acceleration voltage of 360 KeV. Also, the first
The impurity concentration between the diffusion regions (3) (3) becomes almost uniform, and the impurity concentration spreads uniformly vertically like the depletion layer (5) (dotted line) shown in FIG.

(G) Effects of the Invention As is clear from the above description, the present invention is capable of forming a depletion layer (5) by diffusing the second diffusion region (4) deeper than the first diffusion region (3). One first diffusion region (3
) and spreads uniformly vertically to the other first diffusion region (3).

Therefore, since the depletion layer (5) spreads vertically uniformly, the withstand voltage can be controlled with high accuracy.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a protection diode that is an embodiment of the present invention, Fig. 2 is a connection diagram when a protection diode is provided in a dual-gate MESFET, and Fig. 3 is a cross-sectional view of a conventional protection diode. . (1) is a protection diode of a compound semiconductor device, (2) is a GaAs substrate, (3) is a first diffusion region, and (4) is a second diffusion region.
The diffusion region (5) is a depletion layer. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (1) In a protection diode for a compound semiconductor device formed on a compound semiconductor substrate, a plurality of first diffusion regions of one conductivity type formed on the semiconductor substrate and a junction between the first diffusion regions are provided. a second diffusion region of opposite conductivity type,
When the second diffusion region is diffused to a lower concentration and deeper than the first diffusion region, and a bias is applied between the electrodes provided on the surface of the first diffusion region, the second diffusion region
A protection diode for a compound semiconductor device characterized by breakdown due to expansion of a depletion layer in the diffusion region and punch-through.