JPH0484466A - Diode - Google Patents

Abstract

PURPOSE:To improve rising response and efficiency in forward characteristics under simple structure by forming another conducting type buried layer into a single conducting type low concentration substrate in lattice shape, coupling electrically a single conducting type high concentration layer formed on one side the substrate with this buried layer so as to produce an anode, and turning a single conducting type high concentration layer formed on the other side of the substrate so as to produce a cathode: CONSTITUTION:When a forward bias voltage is increased, the expansion between each buried layer 12 is further minimized while a slit 22 is increased so that more increased current flows between N<+> layers 17 and 19 of an anode and a cathode. As a result, a diode is promptly turned ON from the forward voltage 0 so that current may flow where the slit 22 in a depletion layer serves so that the concentration of the buried layer 12, and data such as dimensions and shapes may be properly set so as to reduce the generated voltage to 0. In an electrostatic induction type diode, which controls an expanding state of the depletion layer 21 formed between each buried layer in lattice shape by a reverse bias in this manner, it is possible to enhance rising responsibility with forward characteristics, thereby improving the efficiency of the diode dramatically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a diode, and more particularly to a static induction diode in which current is controlled by a depletion layer formed by reverse bias.

[Conventional technology]

A typical diode has a structure consisting of a PN junction, and its basic structure is shown and explained in FIG.

This diode is made by selectively diffusing P-type impurities to the negative side of an N-type substrate (1) to form a P layer (2).
An insulating film (3) is deposited on top, and a window is opened in the part corresponding to the P layer (2), and the window is covered with an anode electrode (
4), and a cathode electrode (5) is formed on the other surface of the substrate (1).

The above diode has voltage-current characteristics as shown in Fig. 8, and becomes reverse biased by applying a voltage with the anode electrode (4) on the negative side and the cathode electrode (5) on the positive side. The depletion layer that spreads from the P layer (2) into the substrate (1) puts the diode in a cut-off state. Conversely, place the anode electrode (4) on the positive side and the cathode electrode (5) on the positive side.
By applying a voltage to the negative terminal, a forward bias state is created, and current flows between the PN junction and the diode turns on.
state.

[Problem to be solved by the invention]

By the way, in the conventional diode made of the above-mentioned PN junction, as is clear from the voltage-current characteristics shown in Figure 8, when the voltage is gradually increased from the reverse bias state to the forward bias state, the voltage changes from the 00 point. There is a phenomenon in which the diode does not turn on and current does not flow up to a voltage V of 0.6 to 0.7V. As described above, there is a problem in that the rising response of the diode in the forward direction is poor, and the efficiency of the diode is significantly reduced.

The present invention was proposed in view of the above-mentioned problems, and its purpose is to find a diode that can improve the rise response and efficiency of forward characteristics with a simple structure.

[Means to solve the problem]

The technical means for achieving the above object of the present invention is to form a buried layer of another conductivity type in a lattice shape in a low concentration substrate of one conductivity type, and to form a buried layer of one conductivity type on one side of the substrate in this buried layer. The high concentration layer is electrically coupled to serve as an anode, and the high concentration layer of one conductivity type formed on the other side of the substrate is used as a cathode.

[Function] In the diode according to the present invention, by controlling the spread state of the depletion layer formed between each buried layer in a lattice shape by reverse bias, the depletion layer is interposed between the high concentration layer of one conductivity type between the anode and the cathode. Controls the current flowing through the circuit and improves the rise response in the forward characteristic.

〔Example〕

Embodiments of the diode according to the present invention will be described with reference to FIGS. 1 to 6.

The embodiment shown in FIG. 1 is a diode with a square structure.
(12) (12)- is a buried layer of P+ type, which is a different conductivity type, formed in a lattice shape in the N- type substrate (11); (13)
) (13) is the outermost part of the buried layer (12) (12)- and the mesa part (14) (14) of the N-type substrate (11).
) P+ layer (15) N+ layer formed adjacent to (15), (16) (16) is the P+ layer (1
5) (15) and N+ layer (13) Connection electrode formed on (13), (17) is - of N- type substrate (11)
A high concentration N''ffA of one conductivity type formed on the surface side is used as an anode, and an anode electrode (18) is formed on the surface.

This N+ layer (17) is the N”! (
13), is electrically coupled to the buried layer (12) (12) through the connection electrode (16) and the P+ layer (15). (19) is a high concentration N+ layer of one conductivity type formed on the other side of the N- type substrate (11), and this is used as a cathode to form a cathode electrode (20) on its surface.

In this diode, when a reverse bias voltage is applied with the anode electrode (18) on the negative side and the cathode electrode (20) on the positive side, a lattice-shaped buried layer (12) ( A depletion layer (21) is formed around 12)-. If the above reverse bias voltage is small, the depletion layer (
21) is large and each buried layer (12) (1
Since there is a depletion layer (21) between 2L−, this separates the anode and cathode N+ layers (17) and (19), and current flows between the anode electrode (step 8) and the cathode electrode (20). No current flows, and the diode enters a cut-off state as shown in the voltage-current characteristics of FIG. When the reverse bias voltage is gradually reduced, the spread of the depletion layer (21) becomes smaller, and as shown in FIG. 2(b), each buried layer (1
2) (12) - The gap (22) in the depletion layer (21)
occurs, that is, when the reverse bias voltage becomes O, the anode and cathode N+ layers (17) and (19) are connected through the gap (22) in the depletion layer (21),
A current flows between the anode electrode (18) and the cathode electrode (20). After that, when the forward bias voltage is increased, the spread between each buried layer (12) (121-) becomes smaller and the gap (22) becomes larger, and the current flowing between the anode and cathode N+ layer (17) (19) increases. As a result, as shown in the voltage-current characteristics in Fig. 3, current immediately flows through the diode ONL from the forward bias voltage of 0.Here, the gap (22) between the depletion layer (21)
the buried layer (12) so that the voltage generated is OV.
(12) The density, size, shape, etc. of . . . are appropriately set. In this way, each buried layer (
12) In the electrostatic induction diode that controls the expansion state of the depletion layer (21) formed between (12), the rising response in the forward characteristic is good. Incidentally, if the forward bias voltage mentioned in 7 above is further increased, the buried layer (12)
A current will flow between the PN junction between the N″′ type substrate (11) and the N″′ type substrate (11).

Also, the above diode is embedded! If too much current is passed through (12), minority carriers will accumulate and O
If there is a risk of poor cutting during FF, remove the mesa portion (14) (1) of the N-type substrate (11) as shown in Figure 4.
4) P+ layer (15) (15) separated from N+
Form layer (13) (13) and its P+ layer (15)
(15) and the N+ layer (13) (13) The connection electrode (16°) (16') for electrically coupling the N+ layer (13) (13) may have a structure in which it has a resistance component.

In addition, in this electrostatic induction diode, as shown in FIG. 5, the anode N+ layer (I7) and the buried layer (12)
(N+ layer (13'
) (13'') may be formed on the end face of the N-type substrate (11).

Furthermore, the above diode is not limited to the mesa structure, but can also have a planar structure as shown in FIG. 6. In this case, the anode N+ layer (17) and the buried layer (12)
(Buried layer (12) for electrically coupling with 12L-
(12: l- outermost P+ layer (15') (15'
) is preferably formed extending into the N+ layer (17) of the anode.

In each of the above-mentioned embodiments, an N-type substrate has been described, but the present invention is not limited thereto, and is of course applicable to a P-type substrate.

〔Effect of the invention〕

According to the present invention, by controlling the spread state of the depletion layer formed between each buried layer in a lattice shape using reverse bias,
By using a static induction diode that controls the current flowing between the one-conductivity type high concentration layer of the anode and cathode with a depletion layer intervening, the rising response in the forward direction characteristics is good and the efficiency of the diode is high. Its practical value is great.

[Brief explanation of drawings]

1 to 6 are for explaining the present invention in detail, and FIG. 1 is a cross-sectional view showing a diode with a mesa structure, and FIG.
Figures (a) and (b) are cross-sectional views showing the reverse bias state of the diode in Figure 1, Figure 3 is a waveform diagram showing the voltage-current characteristics of the diode in Figure 1, and Figure 4 is the waveform diagram shown in Figure 1. 5 is a sectional view showing another embodiment of FIG. 4,
FIG. 6 is a sectional view showing a Brehner type diode. Figure 7 is a sectional view showing a conventional example of a diode, and Figure 8 is!
FIG. 7 is a waveform diagram showing the voltage-current characteristics of the diode shown in FIG. (11) - Low concentration substrate of one conductivity type, (12) - Buried layer of other conductivity type, (17) - High concentration layer of one and one conductivity type (anode), (1
9) - High concentration layer of one conductivity type (cathode). Figure 1

Claims (1)

[Claims] (1) A buried layer of one conductivity type is formed in a grid pattern in a low concentration substrate of one conductivity type, and a high concentration layer of one conductivity type formed on one side of the substrate is electrically coupled to this buried layer to form an anode. In addition, a diode characterized in that a high concentration layer of one conductivity type formed on the other side of the substrate serves as a cathode.