JPS59163874A - Semiconductor device - Google Patents

Abstract

PURPOSE:To realize a Schottky barrier diode (SBD) device, speed thereof is increased and the degree of integration thereof is improved, by forming a columnar body on a semiconductor substrate and shaping the SBD on the upper surface of the columnar body while forming a capacitor using an SBD metal and the substrate as electrodes to the peripheral side surface of the columnar body. CONSTITUTION:A silicon oxide film 12 and a first silicon nitride film 13 are formed on a silicon substrate 11, and a columnar body 14 is formed through an etching method. A silicon surface is coated with a silicon oxide film 15, and the film 15 is coated with a second silicon nitride film 16. The film 16 is left only to the side surface of the columnar body through anisotropic etching, and a thick silicon oxide film 17 is formed to a section not masked with the nitride film through thermal oxidation. The films 13, 16 are removed, a third silicon nitride film 18 is applied, the film 12 is removed, and a Schottky barrier forming metal 19 is applied. An SBD is shaped to the upper surface of the columnar body and a capacitor using the films 15, 18 as dielectrics to the side surface.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and particularly to a semiconductor device including a Schottky barrier diode.

Recently, in order to suppress saturation and increase the speed of bipolar transistors, Schottky barrier diodes (Schottky barrier diodes), which inject fewer minority carriers in the forward bias state than normal PN junctions and, as a result, recover quickly when reverse biased, have been developed. There are increasing opportunities for SBDs (hereinafter referred to as SBDs) to be incorporated into integrated circuits.

FIG. 1 is a cross-sectional view of an example of a conventional Schottky barrier diode.

An insulating film 2 is formed on a silicon substrate 1, selectively removed to form an opening, and then a Schottky barrier forming metal film 3 is deposited to form 8BD (Schottky barrier diode).

The SBD formed in this way has a forward current rise voltage that is smaller than that of a normal PN junction, and when an 8BD is used as a load section of a memory cell, it is possible to lower the clamp voltage on the off side of the memory cell. It is known to be useful for speeding up memory. Furthermore, when an SBD is used in the load section of a memory cell, the SBD capacitor acts as a speed-up capacitor when the word line potential rises, and α In order to prevent soft errors caused by wires, SBD
A certain amount of capacity is required. However, 5BI) itself has a smaller capacity than a normal PN junction.
, (: was small (8B' Some kind of treatment was necessary to increase the D capacity.

In a semiconductor device having a conventional structure, in order to increase the capacity of the SBD, impurity ions are sometimes implanted in advance into a portion where the SBD is to be formed. In this case, the capacitance increases as the implantation amount increases, but at the same time, if the rising voltage of the forward current of the SHD is lowered and the surface concentration is implanted to about 1.times.10.sup.18 atoms/C.sup.-, it becomes ohmic. The rising voltage of the SBD must be controlled within a certain range for circuit operation, and the amount of ions implanted to increase the capacity is also limited to a certain level. Furthermore, even with ion implantation, a sufficient capacity cannot be obtained, so it is necessary to increase the area of the SBD itself. Because of these factors, it is difficult to increase the integration density of semiconductor devices incorporating SBDs.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide a semiconductor device that includes a Schottky barrier diode with a large capacity and a small area, and which can be expected to achieve high speed and high integration density.

The semiconductor device of the present invention includes a semiconductor columnar body formed on one main surface of the semiconductor substrate by selective etching removal of the semiconductor substrate, and a Schottky barrier forming metal film coated on the upper surface of the semiconductor columnar body. a Schottky barrier diode formed on the semiconductor columnar body, at least one dielectric layer provided on the side surface of the semiconductor columnar body as a capacitor dielectric, and a metal film provided on the surface of the dielectric layer and connected to the Schottky barrier forming metal film. A capacitor having one electrode as the semiconductor columnar body and the other electrode as the semiconductor columnar body.

According to the present invention, an SBD is formed on the top surface of a columnar body formed by selectively etching a semiconductor substrate, a capacitor is formed on the side of this columnar body, and 813D and the capacitor are connected in parallel. Since the capacity of the SBD is secured by using the conventional structure, there is no need to permanently attach a capacitor, making it possible to realize an SBD with a capacitor in a small area.
By incorporating BD into an integrated circuit, a semiconductor device with high speed and high integration density can be obtained.

Next, embodiments of the present invention will be described using the drawings.

FIGS. 2(a) to 2(f) are sectional views illustrating a manufacturing method according to an embodiment of the present invention in the order of steps.

First, as shown in FIG. 2(a), a thin silicon oxide film 12 is formed on an N-type or P-type silicon substrate 11, and a first silicon nitride film 13 is formed thereon. The first silicon nitride film 13 is etched using a photoresist. Silicon oxide film 12. The silicon substrate 11 is sequentially etched to form columnar bodies 14.

Next, as shown in FIG. 2(b), the silicon surface exposed by thermal oxidation is covered with a silicon oxide film 15, and a second silicon nitride film 16 is deposited on the entire surface. Then, anisotropic etching is performed using a method such as reactive ion etching so that the second silicon nitride film remains only on the side surfaces.

Next, as shown in FIG. 2(C), thermal oxidation is performed using the first and second 5-silicon nitride films as oxidation-resistant masks.
Thick silicon oxide film 17 in areas not covered by the mask
form.

Next, as shown in FIG. 2(d), the first and second silicon nitride films 1.3 and 16 are removed.

Next, as shown in FIG. 2(e), after depositing the third silicon nitride film 18 on the entire surface, anisotropic etching is performed to leave the silicon nitride film 18 only on the side surfaces and remove the other parts. .

Next, as shown in FIG. 2(f), the silicon oxide film 12 on the upper surface of the columnar body 14 is removed, and a Schottky barrier forming metal 191, for example, aluminum, is deposited on the entire surface and selectively removed. As a result, a Schottky barrier diode is formed on the upper surface of the columnar body 14, and the Schottky barrier forming metal 19 is used as one electrode, the silicon substrate 11 is used as the other electrode, and the silicon oxide film 15 and the third silicon nitride film 18 are formed on the side surface of the columnar body. A capacitor is formed using this as a dielectric. The capacitor is connected in parallel with a Schottky barrier diode. With such a structure, the characteristics of the SBD are determined by the area of the top surface of the columnar body 14 and the type of Schottky barrier forming metal, and the capacitance of the SBD can be added by a capacitor formed on the side surface of the columnar body. Since the size of the capacitance can be controlled by the height of the columnar body, a large area is not required to add capacitance. Therefore, an SBD with a capacitance suitable for integrated circuits with high integration density can be obtained.

In the above embodiment, the Schottky barrier forming metal 19 was used as one pole of the capacitor, but this was done to simplify the manufacturing process, and a metal other than the Schottky barrier forming metal was used. Of course, it may be formed by separately depositing it.

As described in detail above, according to the present invention, a Schottky barrier with a capacitance can be formed in a small area without implanting impurity ions or increasing the device area in order to add capacitance to a Schottky barrier diode as in the conventional method. The effect is great because a diode can be formed and a semiconductor device with high integration density and high speed operation can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an example of a conventional Schottky barrier diode, and FIGS. 2(a) to 2(f) are sectional views shown in order of steps for explaining a manufacturing method of an embodiment of the present invention. 1... Silicon substrate, 2... Insulating film,
3... Schottky barrier forming metal film, 11...
... silicon substrate, 12 ... silicon oxide film, 13 ... first silicon nitride film, 14 ...
...Columnar body, 15...Silicon oxide film, 16
...Second silicon nitride film, 17...
Silicon oxide film, 18... Third silicon nitride film, 19... Schottky barrier forming metal.

Claims (1)

[Claims] A semiconductor columnar body formed on one main surface of the semiconductor substrate by selective etching removal of the semiconductor substrate, and a Schottky barrier diode formed by depositing a Schottky barrier forming metal film on the upper surface of the semiconductor columnar body. and at least one dielectric layer provided on the side surface of the semiconductor columnar body is used as a capacitor dielectric, and a metal film provided on the surface of the dielectric layer and connected to the Schottky barrier forming metal film is used as one electrode. A semiconductor device comprising: a capacitor having the semiconductor columnar body as the other electrode.