JPS5879775A - Planar type diode - Google Patents

Abstract

PURPOSE:To improve electrostatic breakdown resistance by making a distance between the first semiconductor layer and the second semiconductor layer surrounding the first semiconductor layer larger than thickness just under the first semiconductor layer of a substrate. CONSTITUTION:Carriers reach an n<++> type Si layer 7 before a depletion layer (a) extending into the substrate 1 from a p type Si layer 2 reaches an n<++> type annular Si layer 3 from the layer 2 when reverse voltage is applied between an anode 6 and a cathode 8 because the distance la between the Si layers 2 and 3 is made larger than the thickness t between the layer 2 of the i type Si substrate 1 and the layer 7, and the generation of electrostatic breakdown between the layer 2 and the layer 3 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pinJ square diode constructed using a semiconductor substrate tube having a high resistivity tube and acting as an intrinsic semiconductor.

Taking advantage of this fact, it is widely used in blades, communication equipment, television receivers, etc.

FIG. 1 is a sectional view showing an example of a conventional Brehner diode having a p1n structure.

In the figure, +lid li! 00ON5000Ω-a
An n-type silicon (81) substrate (hereinafter referred to as "1-type S1 substrate") that has a resistivity of about m and acts as an intrinsic semiconductor, (!
l is a py#81 layer formed by introducing p-type impurities into a part of the first main surface of the 1-type 81 substrate + 11, 1B1Fi
I-type 81 substrate (11 first main surface part Kp-type 81 layer (2)
An annular n-type layer is formed by introducing n-type impurities at a high concentration to surround 81 p-type layers at a distance l as shown in the figure.
++ type B type layer 1 layer 4) is p type 81 layer (21, n++ type 8
silicon oxide (810z) formed over the surface of the p-type 81 layer (1 layer) and the 1-type S1 substrate (1); (6) is an anode formed to be in direct contact with the p-type Bi layer (!) through the contact hole (6), and (7) is an anode formed on the second main surface of the 1-type 81 substrate (1) with n-type impurities. n++ type s formed by introducing high concentration
The type layer 1 layer 8) is a single pole formed on the surface of the n++ type 8 type layer 1) so as to be in ohmic contact therewith.

By the way, when a reverse voltage is applied between the anode (6) and the cathode (8), the p-type 81 layer (2)
Due to the depletion layer (A) shown by the dashed line extending into the substrate (1), leakage current is likely to occur at the interface between the 1 type 81 substrate + 11 and the 8102 film (4).
When the leakage current reaches the end face of the 1-type 1-type substrate + 11, the leakage current becomes unstable, so in this conventional example, the n"v 81 layer (Bi is provided and the depletion layer is 0) is 1-type S1 substrate (1). The rounded V prevents the leakage current from reaching the end face and reduces the leakage current.
The illustrated distance l between the Ln++ type 81 layer (3) and the p type 81 layer (2) was set to be as small as possible.

When this distance l becomes smaller than the thickness t) between the p-type 81 layer (2) and the n-type 81 layer (7) of the 1-type 81 substrate (1), the depletion layer (a) becomes p-type Si# (!l to n Before reaching the 1st layer (7), the n++ 8th layer 1st layer + 31
and the depletion layer (a) of and reaches the n++ type s directly
Since the impurity concentration in the 1st layer + 11th surface area is high, the depletion layer (
A) immediately reaches the n++ type 8 layer 1 layer + 31, the Kp type 8
Electrostatic breakdown occurs between the first layer (2) and the n++ type 8 type layer (first layer), and this electrostatic breakdown 11 reduces the electrostatic breakdown resistance of this planar diode. However, there are cases where a high electrostatic breakdown resistance is more important than a low leakage current. For example, when this planar diode is used in a connection with an antenna of a communication device, it is usually a p-type s
The reverse voltage applied between tMe 121 and the n++ type B layer (1 layer) is not very large, but if a problem such as the antenna becoming open, the reverse voltage at this time will increase. The electrostatic damage caused by the reverse voltage at this time between the B1 layer (and (3)) not only destroys the planar diode itself, but also damages the planar diode itself. This may also cause discoloration of communication devices that use planar diodes, so it is necessary to increase the electrostatic breakdown resistance of these planar diodes.

This invention company, above-mentioned point Kill! A first semiconductor layer of a ninth conductivity type is formed on a part of one main surface of a semiconductor substrate of a first conductivity type that acts as an intrinsic semiconductor, and a high-temperature layer is formed surrounding it. By increasing the distance between the second semiconductor layer of the impurity conductivity type and the second semiconductor layer of the i-th conductivity type of the semiconductor substrate, the electrostatic breakdown resistance can be increased. The purpose of the present invention is to provide a planar diode with improved characteristics.

FIG. 2 is a cross-section diagram showing a pin-type play type diode according to an embodiment of the present invention.

In the figure, the same reference numerals as in the conventional example shown in FIG. 1 indicate the same parts, and the explanation thereof will be omitted.

The structure of this example is a p-type 81 layer (2) and an annular n++
The illustrated distance/a between the type 8 type s1 substrate (1 layer)
1) p-type 81 layer (2) and n”Bill ('71
The structure is the same as that of the conventional example shown in FIG. 1, except that the thickness between t) and t) is made larger than that shown in the figure.

In the planar diode of this example, 81 layers (2)
and (3) the distance between 11 and 1 type 81 board i11 nost
Since the thickness between layer (!) and (7) is much steeper than t,
When a reverse voltage is applied between the anode C. (from ri to cyclic n++
(1 layer of type 8 layer) Before reaching K, 1 layer of n++ type 8 layer K
It is possible to prevent electrostatic damage from occurring between the p-type 81 layer (3) and the n0-type 81 layer (3).Moreover, it is possible to prevent electrostatic discharge from occurring between the p-type 81 layer and the n0-type 81 layer (3). Whether or not electrostatic breakdown occurs between the p-type 81 layer (!1 and the n" type 8i layer (7) is determined by the impurity concentration of the p-type 81 layer (a, n"+ type 81 layer) due to the arrival of this n+ "f4 $ The i layer (71) has an impurity concentration gradient in which the impurity concentration decreases toward the 1 type 81 substrate (1) side due to the introduction of n-type impurities from the surface on the cathode (8) side, and this impurity concentration Due to the gradient, the depletion layer (a) reaches the n++ type B type layer (1 layer),
Since electrostatic damage is less likely to occur between the p-type 81 layer (2) and the n-type 81 layer (7), the electrostatic damage resistance can be improved.

In addition, in this example, the p shadow area is changed to the n shadow area,
It goes without saying that even if the n-shade region is changed to a p-shade region, the same effect as in this embodiment can be obtained. The first semiconductor layer is removed with a predetermined distance between the first semiconductor layer of the first conductivity type formed on a portion of the first main surface of the semiconductor substrate and the first semiconductor layer. a second conduction type semiconductor layer surrounded by a ring and having a high impurity concentration; and a conduction conduction type semiconductor layer W, 3 formed on the second main surface of the semiconductor substrate and having a high impurity concentration. Since the predetermined distance between the first and second semiconductor layers is made larger than the thickness between the first and third semiconductor layers of the semiconductor substrate, there is a distance between the first and jls semiconductor layers. When a reverse voltage is applied, the depletion layer extending from the first semiconductor layer into the intrinsic medium conductor substrate reaches the third semiconductor layer before reaching the second semiconductor layer, and It appears that it is possible to prevent electrostatic damage from occurring between the first and second semiconductor layers, and the electrostatic damage resistance can be improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of a conventional Brehner diode, and FIG. 2 is a cross-sectional view showing a Brehner diode according to an embodiment of the present invention. In the figure, (1) is the 1 type 81 substrate (the first conduction type semiconductor substrate), (21 is the p type 81 MI (the first conduction type semiconductor substrate)
+31 is the n-type 81 layer (the second semiconductor layer of the first great conduction type), (71 is the n-type 8i layer (the fifth semiconductor layer of the all conduction type). The same symbols in the middle indicate the same or equivalent parts 0

Claims (1)

[Claims] 111 A first conductor layer having high resistivity and functioning as an intrinsic semiconductor, the first conductor layer having a high resistivity and acting as an intrinsic semiconductor, the first
in which the predetermined distance between the first and second semiconductor layers is greater than the thickness between the first and $5 semiconductor layers of the intrinsic semiconductor substrate. Thing 1 - Features of planar diode 0