JPS6233456A - Schottky barrier diode - Google Patents

Abstract

PURPOSE:To reduce the forward voltage of a Schottky barrier diode, by providing with one conductive type of a separating region with a higher impurity concentration reaching from the epitaxial layer surface to the semiconductor substrate surface around the epitaxial layer, and the one conductive type of a buried layer formed at a section in the separating region on the semiconductor substrate. CONSTITUTION:An N<+> type buried region 3 is formed at least on a section in the separating region 6 by diffusing selectively antimony on a semiconductor substrate 2. Accordingly, since the current path flowing into the semiconductor substrate 2 from the barrier metal electrode 7 can be shortened, the resistance at this section can be reduced. On the other hand, an N<+> type separating region 6 is formed so as to reach from the epitaxial layer 4 surface to the N<+> type semiconductor substrate 2 surface around the N-type epitaxial layer 4. Since the N<+> type separating region with a higher concentration than the N-type epitaxial layer 4 may be formed and thus a portion of current may be flowed into the N<+> type separating region 6, increase of the boundary area between the semiconductor substrate 2 and the epitaxial layer 4 of the Schottky barrier diode and thus decrease of the resistance can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to improving the forward voltage (V?) characteristics of a Schottky barrier diode.

(B) Conventional technology A conventional Schottky barrier diode 121) has an N''
ffi silicon semiconductor substrate and an N-type epitaxial layer laminated on the N''W silicon semiconductor substrate@
, a silicon oxide film (c) laminated on the N-type epitaxial layer 04) using a thermal oxidation method or the like, and a contact hole formed in the silicon oxide film (c) by photolithography. Here, the contact hole is formed approximately in the middle of the silicon semiconductor substrate@, and the barrier metal electrode (3) is laminated through the contact hole. It is composed of A (1 wire, etc.) formed by a wire bonding method approximately at the center of the barrier metal electrode (3) which is formed by stacking.

(c) Problems to be solved by the invention It is generally known that Schottky barrier diodes have short switching times and are suitable for high-speed switching operations, and the height of the forward barrier of Schottky barrier diodes is Since it is inversely proportional to the switching speed,
Schottky barrier diodes with lower forward barrier heights are desirable. Therefore, a Schottky barrier diode with a small forward voltage V is desirable, and the problem of the present invention is to reduce the forward voltage V of this Schottky barrier diode.

B) Means for Solving Problems The present invention provides a semiconductor substrate (2) of one conductivity type with high impurity concentration, an epitaxial layer (4) of one conductivity type formed on the semiconductor substrate (2), and the epitaxial layer (4) of one conductivity type formed on the semiconductor substrate (2). A Schottky barrier diode (1) comprising a barrier metal electrode (4) in contact with the layer (4) and an insulating film (5) formed in a region where the barrier metal electrode (7) does not contact the epitaxial layer (4). ), an isolation region (6) of one conductivity type with a high impurity concentration reaching from the surface of the epitaxial layer (4) to the surface of the semiconductor substrate (2) is provided at the periphery of the epitaxial layer (4); 2) Upper separation area (6
) and a buried region (3) of one conductivity type formed in at least a part of the region (3).

(E) Function Generally speaking, the forward voltage of a Schittky barrier diode is
, is the series resistance R1 of the Schottky barrier diode.

In the conventional structure, the concentration and thickness of the epitaxial layer (material) of one conductivity type were approximately determined, but the epitaxial layer (4) was formed on the periphery of the epitaxial layer (4).
By forming an isolation region (6) of one conductivity type reaching from the surface to the surface of the semiconductor substrate (2), a portion of current flows into the isolation region (6) of one conductivity type with high impurity concentration, so that Schottky The forward voltage V of the barrier diode can be reduced.

On the other hand, by providing the buried region (3), the current path flowing into the semiconductor substrate (2) can be shortened, so that the head direction voltage V can be reduced as described above.

(F) Embodiment An embodiment of the present invention will be described below with reference to FIG.

As shown in Figure 1, an N+ type silicon semiconductor substrate (2)
and an N+ type buried layer (3) formed by selectively further diffusing antimony on the semiconductor substrate (2), where the N+ type buried layer (3) is formed on the semiconductor substrate (2).
), an N-type epitaxial layer (4) stacked on the N+ type silicon semiconductor substrate (2) and formed in at least a part of the isolation region (B) on the N-type epitaxial layer ( 4) A silicon oxide film (5) is laminated on the silicon oxide film (5) using a thermal oxidation method or the like, and the epitaxial layer is formed using a diffusion method into a diffusion hole formed at the periphery of the silicon oxide film (5) by a photolithography method or the like. an N+ type isolation region (6) formed to reach the surface of the semiconductor substrate (2) from the surface of layer f4J;
The barrier metal 1 electrode (7) in contact with the epitaxial layer (4) is formed by selectively removing the silicon oxide film (5) and providing a contact hole with Mo, Ni, AI. The barrier metal electrode (7) is formed by a sputtering method or the like in this order, and is composed of an insulating film (5) formed in a region not in contact with the epitaxial layer (4) or the isolation region (6).

The feature of the present invention is that the embedded area (3)
and in the separation area (6). The N+ type buried region (3) selectively diffuses antimony onto the semiconductor substrate (2) and is formed in at least a part of the isolation region (6). Here, the separation region (6) may be formed in a mesh shape or the like. Therefore, the path of the current flowing from the barrier metal electrode (7) to the semiconductor substrate (2) can be shortened, so that the resistance in this portion can be reduced.

On the other hand, the N type isolation region (6) is formed at the periphery of the N type epitaxial layer (4) so as to reach from the surface of the epitaxial layer (4) to the surface of the N+ type semiconductor substrate (2). Here, diffusion using ion implantation or the like may be considered as a forming method. Therefore, by forming an N+ type isolation region (6) with a higher concentration than the N epitaxial layer (4), a part of the current is transferred to the N''W isolation region (
6), the epitaxial layer (4) of the Schottky barrier diode (1) and the semiconductor substrate (2)
) has increased the boundary area, which means that the resistance has decreased.

Moreover, FIGS. 2 and 3 show embodiments of the present invention, and each figure is an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a Schottky barrier diode using a "type" type/P+ type guard ring.

(g) Effects of the Invention As is clear from the above description, the present invention provides a method for selectively diffusing antimony onto the semiconductor substrate (2) and forming a separation region (
6) an N+ type buried region (3) formed in at least a part of the N+ type semiconductor substrate (21) and an N+ type buried region (3) formed at the periphery of the N type epitaxial layer (4) from the surface of the epitaxial layer (4) to the surface of the N+ type semiconductor substrate (21); N+ type isolation region (6
), it is possible to reduce the resistance of the Schottky barrier diode and reduce the forward voltage (2).

[Brief explanation of drawings]

1 to 3 are cross-sectional views of a Schottky barrier diode according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view of a conventional Schottky barrier diode. The explanation of the main figure numbers is (1) is Schottky barrier diode, (2) is semiconductor substrate, (3) is buried layer, (4) is epitaxial layer, (5) is silicon oxide film, (6) is Separation area, (
7) is a barrier metal electrode. Applicant Sanyo Electric Co., Ltd. and 1 other representative Patent attorney Shizuka Sano Mistake 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) A highly impurity-concentrated semiconductor substrate of one conductivity type, an epitaxial layer of one conductivity type formed on the semiconductor substrate, a barrier metal electrode in contact with the epitaxial layer, and the barrier metal electrode not in contact with the epitaxial layer. In the Schottky barrier diode, the Schottky barrier diode includes an isolation region with a high impurity concentration extending from the surface of the epitaxial layer to the surface of the semiconductor substrate at the periphery of the epitaxial layer, and an isolation region on the semiconductor substrate. A Schottky barrier diode comprising a buried region of one conductivity type formed in at least a part of the region.