JPS62108578A - Semiconductor device - Google Patents

Abstract

PURPOSE:To reduce leakage currents by forming a groove to an insulating film on the surface of a semiconductor substrate among a plurality of diodes and exposing the surface of the semiconductor substrate. CONSTITUTION:The surface section of a semiconductor substrate 11 is oxidized and coated with an silicon dioxide film 14, and a P-type impurity such as boron is introduced to the surface section of the substrate 11 from windows bored to the silicon dioxide film 14 to shape impurity regions 15, 16. The N-type semiconductor substrate 11 and the P-type impurity regions 15, 6 each constitute diodes, and anode electrodes 17, 18 are brought into contact with the impurity regions 15, 16. On the other hand, a back metal as a common cathode electrode 19 is laminated on a high impurity concentration layer 12. An approximately V-shaped groove 20 reaching up to the high impurity layer 12 is shaped to the silicon dioxide film 14 between the impurity regions 15 and 16, and a low impurity concentration layer 13. Accordingly, a path for leakage currents flowing on the interface between the insulating film and the semiconductor substrate is interrupted by the groove, thus reducing leakage currents between the impurity regions.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a semiconductor device, and particularly to a semiconductor device that prevents leakage current between a plurality of diodes formed on a single semiconductor substrate.

<Prior art> FIG. 3 is a sectional view showing a conventional semiconductor device, and 1 is a sectional view showing a conventional semiconductor device.
An n-type semiconductor substrate consisting of a high impurity concentration layer 2 and a low impurity concentration layer 3 is shown. The surface of the semiconductor substrate 1 is oxidized and covered with a silicon dioxide film 4, and a p-type impurity such as boron is introduced into the surface of the substrate 1 through a window formed in the silicon dioxide film 4. Impurity region 5
, 6 are formed. The n-type semiconductor substrate 1 and the p-type impurity regions 5 and 6 each constitute a diode, and the anode electrode 7.8 is in contact with the impurity regions 5 and 6. On the other hand, a back metal serving as a common cathode electrode 9 is laminated on the high impurity concentration layer 2 .

A semiconductor device having such a structure allows current to flow between the anode electrode 7.8 and the common cathode electrode 9, respectively, and functions as a so-called twin diode.

<Problems to be Solved by the Invention> In the conventional semiconductor device described above, the state of the interface between the silicon dioxide film 4 and the semiconductor substrate 1 deteriorates due to slight contamination during the manufacturing process, and contaminants propagate through the interface. A leakage current was flowing between impurity region 5 and impurity region 6.

In addition, since the impurity regions 5 and 6 are formed within the low impurity concentration layer 3, a parasitic bipolar transistor is formed by the impurity region 5, the low impurity concentration layer 3, and the impurity region 6. When the applied voltage was higher than the anode electrode 8 as well as the cathode electrode 9, the parasitic bipolar transistor was biased in the forward direction, and a leakage current was flowing between the anode electrodes 7 and 8.

Although the current flowing through such an interface and the current due to the parasitic bipolar transistor is about 1 to 100 μA,
Electronic circuits that require high precision are required to further reduce such a small amount of leakage current, and reducing leakage current has been a problem with semiconductor devices in which a plurality of diodes are integrated on a single substrate.

Therefore, it is an object of the present invention to provide a semiconductor device comprising a plurality of diodes with further reduced leakage current.

<Means for Solving the Problems> The present invention involves growing an insulating film on the surface of a single semiconductor substrate in which a first conductivity type high impurity concentration layer and a first conductivity type low impurity concentration layer are superimposed. In a semiconductor device in which a plurality of impurity regions of a second conductivity type are formed in a surface portion of a semiconductor substrate under an insulating film, and a plurality of diodes are respectively formed by the semiconductor substrate and the plurality of impurity regions, The gist of this invention is to eliminate the influence of the interface between the semiconductor substrate and the insulating film by forming a groove in the insulating film on the surface of the semiconductor substrate and exposing the surface of the semiconductor substrate.

<Example> FIGS. 1 and 2 are diagrams showing a first example of the present invention. In FIG. An n-type semiconductor substrate consisting of a layer 12 and a low impurity concentration layer 13 is shown. The surface of the semiconductor substrate 11 is oxidized and covered with a silicon dioxide film 14, and a p-type impurity such as boron is introduced into the surface of the substrate 11 through a window formed in the silicon dioxide film 14. Impurity region 15°16
is formed. The n-type semiconductor substrate 11 and the p-type impurity region 15.16 each constitute a diode, and the impurity region 15.16 is connected to an anode electrode 17.1.
8 are in contact. On the other hand, a back metal serving as a common cathode electrode 19 is laminated on the high impurity concentration layer 12 .

A substantially V-shaped groove 20 reaching up to the high impurity layer 12 is formed in the silicon dioxide film 14 and the low impurity concentration layer 13 between the impurity regions 15 and 16 described above. , a physical method by Cutter et al.

It may be formed by either a chemical method such as etching or an optical method using a laser or the like.

In a semiconductor device having such a V-shaped groove 20,
Since the interface between silicon dioxide film 14 and semiconductor substrate 11 is cut between impurity regions 5 and 6, leakage current flowing through this interface can be prevented, and since no parasitic transistor is formed, leakage current due to parasitic transistors can also be prevented. can. In fact, the twin diode device with the figure 7 groove 20 was able to reduce the leakage current to a few tens of nA.

<Effects> As explained above, according to the present invention, the leakage current path flowing through the interface between the absolute film and the semiconductor substrate is blocked by the groove formed in the insulating film, so that the leakage current between the impurity regions can be reduced. The effect is that it can be reduced.

Furthermore, in one embodiment, grooves are formed in the low impurity concentration layer, so that not only leakage current flowing through the interface but also leakage current due to parasitic transistors can be prevented, and leakage current between impurity regions can be extremely minimized. It has the advantage of being able to

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a plan view of the semiconductor device shown in FIG. 1, and FIG. 3 is a sectional view of a conventional example. 11... Semiconductor substrate. 12...High impurity concentration layer. 13...Low impurity concentration layer, 14...Insulating film, 15.16...Impurity region 2o...Groove. Patent Applicant: ROHM Co., Ltd. Agent, Patent Attorney Kiyoshi Kuwai - Figure 1, Figure 2, Figure 3

Claims (2)

[Claims] (1) An insulating film is grown on the surface of a single semiconductor substrate in which a first conductivity type high impurity concentration layer and a first conductivity type low impurity concentration layer are superimposed, and a plurality of insulating films are grown on the surface of the semiconductor substrate under the insulating film. In the semiconductor device in which a second conductivity type impurity region is formed, and a plurality of diodes are respectively formed in the semiconductor substrate and the plurality of impurity regions, a groove is formed in an insulating film on a surface of the semiconductor substrate between the plurality of diodes. A semiconductor device characterized in that a surface of the semiconductor substrate is exposed. (2) The semiconductor device according to claim 1, wherein a groove continuous with a groove formed in the insulating film is formed in the low impurity concentration layer to expose the high impurity concentration layer.