JPH0575098A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device excellent in the forward direction, reverse direction, and switching characteristics having an increased ratio of the forward current effective area whereby to determine the ratio of the effective channel width corresponding to the cell size. CONSTITUTION:The surface of one conductive type semiconductor 1 is arranged in a configuration having irregularities 5 and 6. A first inverted conductive semiconductor region 2a is formed on the upper part of the extrusion 6, and a second inverted conductive semiconductor region 2b is formed at the bottom of the extrusion or at the bottom including a part of the sides. Then, a metallic layer to form a Schottky or ohmic contact is arranged at least on one side of the extrusion which is located between the first and second regions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a semiconductor device of the present invention.

[0002]

2. Description of the Related Art As is well known, the characteristics of semiconductor devices are improved,
In particular, in order to improve the forward characteristic, the reverse characteristic, and the switching characteristic, development has been advanced and various structures have been proposed.

FIG. 1 shows a sectional structure view of a conventional semiconductor device. FIG. 1 shows that the present inventors have filed Japanese Patent Application No. 3-11534.
1 is a structure invented by "Schottky barrier semiconductor device", 1 is a one-conductivity type semiconductor region, for example, N-type silicon semiconductor, 1'is a low-resistance one-conductivity type semiconductor region, for example, N + -type silicon semiconductor, 2 Is a semiconductor region of opposite conductivity type,
For example, P + type silicon semiconductor, 3 is one electrode metal, 4 is an ohmic electrode metal, 5 is a concave portion by a trench groove, 6 is a convex portion, A is an anode, and C is a cathode.

In the above-mentioned Japanese Patent Application No. 3-115341, a well-known metal that forms a Schottky barrier contact is selected as one electrode metal 3 to improve the forward direction characteristics, and at the same time, in the reverse bias (2) ass, one conductivity type semiconductor. Region 1 and one electrode metal 3
By sandwiching the space charge layer extending from the Schottky barrier contact surface e formed by the two sides with the space charge layer from the PN junction formed by the opposite conductivity type semiconductor region 2, the space charge layers in three directions are generated at a certain reverse voltage or more. In combination, the electric field strength E applied to the contact surface e is suppressed to a low value to improve the reverse leakage current. It should be noted that such an effect is not limited to the case where the contact surface e forms a Schottky barrier contact, and is the same when the contact surface e is an ohmic contact.

However, assuming that the closest distance W between adjacent opposite conductivity type semiconductor regions 2 that determines the effective channel width within the cell size CW, the forward current effective region ratio α = W in the current semiconductor manufacturing technology. /CW<0.2-0.4 is unavoidable. Therefore, the cell size CW becomes extremely large in order to secure the closest distance W that determines the required forward current. That is, the semiconductor chip has a large shape even if it is excellent in characteristics, resulting in an expensive semiconductor device.

[0006]

SUMMARY OF THE INVENTION The present invention solves the problems of the conventional device described above, and provides a semiconductor device having a small reverse leakage current and a small forward voltage drop, a high speed and a low loss with a structure having a large forward current effective area ratio α. The purpose is to get.

[0007]

EXAMPLE An example of the present invention is shown in the sectional structure view of FIG.
The same reference numerals as in FIG. 1 represent the same parts. Reference numeral 2a denotes a first reverse-conductivity type semiconductor region formed on the upper portion of the convex portion 6, 2b denotes a second reverse-conductivity type semiconductor region formed below the bottom portion and the side portion of the convex portion 6, A Schottky or ohmic contact surface e ′ is formed by the one electrode metal 3 on the side of the convex portion 6 sandwiched by the region 2a and the second region 2b.

Specifically, a trench groove is formed in an N-type silicon semiconductor substrate by a known method, a recess 5 and a protrusion 6 are provided, and a first reverse conductivity type semiconductor region 2a and a second reverse ( 3) Boron atoms are formed as P + regions at the position of the conductive type semiconductor region 2b by the ion implantation method or the vapor phase diffusion method. Then, the one-electrode metal 3 was formed by the vapor deposition method.

The second opposite conductivity type semiconductor region 2b is preferably formed so as to extend to a part of the bottom and side portions of the convex portion 6, but it is necessary to form it at least at a corner portion of the bottom portion.

Regarding the shape of each part, the closest distance WL between the first region 2a and the second region 2b, the closest distance L between each 2b of the adjacent second regions, and zero extending from the contact surface e '. If the depth Wbi of the space charge layer at the time of bias, the space charge layer WB at the time of dielectric breakdown, and the angle θ formed by the tangent line at the position f of Wbi in the second region 2b with the contact surface e ', WL and L are 2 Wb
smaller than i or at least within 2 WB, θ
Is preferably formed so that 60 ° ≦ θ ≦ 180 °. Thus, between the anode A and the cathode C, one conductivity having a first region 2a and two metal-semiconductor contact surfaces e'sandwiched by the respective second regions 2b. A semiconductor device having the type semiconductor 1 as a base is formed. That is, it is possible to form a semiconductor device having a contact surface e'on each of the right and left sides of the convex portion 6 in FIG.

When the contact surface e of FIG. 1 and the contact surface e'of FIG. 2 have the same area, the forward current effective area ratio α in the structure of the present invention of FIG. 2 can be doubled as compared with the conventional structure of FIG.

In forming a trench groove having an uneven surface of one conductivity type semiconductor, the forward current effective area ratio α can be doubled by a plurality of strip-shaped array trench grooves. It is possible to increase the effective area ratio α to 4 times or more by devising the three-dimensional size of the cell by forming a plurality of island-shaped array trenches as shown in the plan structure diagram.

As described above, the structure of the present invention (4) does not impair the reverse leakage current suppressing effect described in FIG. it can. For the same forward current, the current density at the contact surface e'can be reduced, and if e'is a Schottky contact, the forward voltage drop can be reduced. Further, when the current density is made equal to that of the conventional structure shown in FIG. 1, the chip size can be reduced, so that an inexpensive semiconductor device can be obtained.

When the contact surface e'has an ohmic contact, the electrical characteristics corresponding to the electron potential height in one conductivity type semiconductor region are formed based on the formation of the first region 2a and the second region 2b. The rectification characteristics in the forward and reverse directions similar to those when the contact surface e ′ was Schottky contact were observed.

The shape of the trench groove, that is, the recess 5 in the sectional structure of FIG. 2 is not limited to the trapezoid or the rectangle, and the shape of the second region 2b, the distance between the respective portions, and the dimensional relationship are also limited to those of the embodiment. Not a thing. Other modifications, conversions, changes such as additions are also included in the right of the present application within the scope of the present invention.

[0016]

As described above, a semiconductor device having excellent forward characteristics, reverse characteristics, and switching characteristics can be obtained with a structure having an increased forward current effective area ratio, and Schottky or ohmic contact can be obtained. The current density of the surface can be reduced or the chip size can be reduced to achieve economy, and the present invention can be applied to semiconductor devices used in various industrial equipment such as power applications, and the effect is extremely large.

[Brief description of drawings]

FIG. 1 is a cross-sectional structural diagram of a conventional semiconductor device.

FIG. 2 is a sectional structural view showing an embodiment of the present invention.

FIG. 3 is a plan structure diagram showing (5) an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1 conductivity type semiconductor area 1'Low resistance 1 conductivity type semiconductor area 2 Reverse conductivity type semiconductor area 2a 1st reverse conductivity type semiconductor area 2b 2nd reverse conductivity type semiconductor area 3 1 electrode metal 4 Ohmic electrode metal 5 concave part 6 convex part A anode C cathode e, e'contact surface f contact CW cell size W closest distance of two adjacent phases WL closest distance between 2a and 2b Wbi space charge layer at zero bias Depth WB Space charge layer width at dielectric breakdown L phase Closest distance between adjacent 2b θ angle

Claims (1)

[Claims] 1. A semiconductor device in which a trench groove is formed to make a surface of one conductivity type semiconductor uneven, and a first reverse conductivity type semiconductor region is included in an upper portion of the protrusion, and a part of a bottom portion or a side portion of the protrusion is included. A second opposite conductivity type semiconductor region is formed on the bottom, and a metal layer for forming a Schottky or ohmic contact is provided on at least one side of a protrusion sandwiched by the first and second opposite conductivity type semiconductor regions. A semiconductor device characterized by the above.