JPS62136072A - Manufacture of schottky barrier diode - Google Patents

Abstract

PURPOSE:To eliminate the irregularity of the circumference of a Schottky junction and stabilize the characteristics by a method wherein, after a barrier metal layer is formed over the whole surface of a semiconductor substrate, the substrate is formed into bevel by selective etching and the bevel slope is covered with an insulating film. CONSTITUTION:A substrate composed of an N<+> type silicon substrate 1 and an N-type epitaxial layer 2 deposited on the substrate 1 is employed. A barrier metal layer 5 composed of three layers of Mo, Ni and A is formed over the whole surface and subjected to sintering treatment. Then the center part of the barrier metal layer 5 only is covered with a resist film and the substrate is formed into bevel by etching. After that, an insulating film 3 is applied to the bevel slope 6 by, for instance, varnish coating. With this constitution, the barrier metal layer is not formed on a stepped part so that secure bonding between the barrier metal layer and the semiconductor substrate surface can be always obtained and the instability of the characteristics of a Schottky barrier diode can be eliminated.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a method for manufacturing a Schottky barrier diode, particularly a large capacity Schottky barrier diode.

[Prior art and its problems]

An example of a structure that increases the withstand voltage of a large-capacity Schottky barrier diode is shown in Figure 2 +8! , (bl, (C1) are connected to each other. These have a structure that angles the substrate surface at the end of the depletion layer to avoid concentration of the electric field around the barrier when a reverse voltage is applied. In the case shown in Fig. 2+8!, the surface of the N epitaxial layer 2 deposited on the N silicon substrate 1 is covered with an insulating film 3, and a recess 4 is formed by etching from the opening. Afterwards, barrier metal N5 is deposited and manufactured.Second
The one shown in Figure 1) is manufactured by forming a recess 4 having an inclined surface and coating the barrier metal N5 on the bottom surface and the inclined surface of the recess. The one shown in FIG. 2 (C1) is manufactured by forming the base Fi1 and the epitaxial layer N2 in a mesa shape, covering the inclined surface 6 with the insulating film 3, and then depositing the barrier metal layer 5. However, in these cases, Since the barrier metal layer 5 is deposited on the stepped portion, it is difficult for the barrier metal to adhere to the semiconductor N2 in the peripheral area of the barrier metal layer indicated by the symbol A in the figure, and the Schottky junction becomes irregular, resulting in poor device characteristics. The disadvantage was that it became unstable.

[Purpose of the invention] The present invention enables reliable adhesion between the metal layer and the semiconductor substrate in the periphery of the Schottky barrier metal layer formed on the semiconductor substrate having an inclined surface, eliminates irregularities in the periphery of the Schottky junction, and improves the characteristics. The purpose is to provide a method for manufacturing a stable Schottky barrier diode. [Key points of the invention]

According to the present invention, after a barrier metal layer is entirely deposited on the surface of a semiconductor substrate, it is bevel-formed by selective etching, and the beveled inclined surface is covered with an insulating film, so that the peripheral portion of the barrier metal layer is covered with the metal layer. Since it is formed by etching after deposition, irregularities in the Schottky joint periphery do not occur, and the above objective is achieved.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, using a substrate in which an N epitaxial layer 2 is deposited on the same IN'' silicon substrate 1 as in the conventional case, and first a barrier metal layer 5 made of 3N of Mo, N+, and Au is deposited. As shown in Figure 1 (4), only the central part of the barrier metal It!! 5 is covered with a resist film, which is coated on the entire surface and subjected to sintering, and then etched, as shown in Figure 1 (bl). After bevel forming, the insulating film 3 is deposited on the bevel inclined surface 6 by, for example, coating with a face.Effects of the Invention The present invention is advantageous in that the inclined surface provided at the end of the depletion layer is formed on the semiconductor layer of the barrier metal layer. By forming it after adhering to the substrate surface,
Since the barrier metal layer does not adhere to the stepped portion, reliable adhesion between the barrier metal layer and the semiconductor substrate surface can be obtained at all times, and instability in the characteristics of the Schottky barrier diode can be prevented.

[Brief explanation of drawings]

FIG. 1 is a sectional view sequentially showing the steps of an embodiment of the present invention, and FIG. 2 is a sectional view showing three examples of conventional large-capacity Schottky barrier diodes. 1: N' silicon substrate, 2: N epitaxial layer, 3
: Insulating film, 5: Barrier metal layer, 6: Hevel slope. l-]・

Claims (1)

[Claims] 1) After depositing a barrier metal layer all over the surface of the semiconductor substrate,
A method for manufacturing a Schottky barrier diode, characterized by forming a bevel by selective etching and covering the beveled inclined surface with an insulating film.