CN2826698Y - Germanium-silicon Schottky diode - Google Patents

Abstract

The utility model relates to a germanium-silicon Schottky diode which comprises an ohmic contact electrode, a silicon substrate and a silicon nitride layer which is provided with a window, wherein the ohmic contact electrode, the silicon substrate and the silicon nitride layer are orderly superposed from bottom to top. A germanium-silicon layer and a nickel-silicon compound layer are arranged in the window of the silicon nitride layer, wherein the nickel-silicon compound layer is positioned on the germanium-silicon layer, and an aluminium electrode which is in contact with the nickel-silicon compound layer is covered on the window of the silicon nitride layer. Because the germanium-silicon layer of the germanium-silicon Schottky diode with the structure is only arranged on the point of the photoetching window of the silicon nitride, the reverse leakage current of the device can be effectively reduced, and the device can be manufactured without any isolation; the technology is simplified, and the integrated level is improved.

Description

A silicon germanium schottky diode

technical field

The utility model relates to a semiconductor device, in particular to a germanium-silicon schottky diode.

Background technique

Schottky diodes are widely used in high-frequency, high-speed, and detection due to their characteristics of majority carrier operation, fast response speed, and no minority carrier accumulation. Before the utility model was made, the traditional SiGe Schottky diodes had ohmic contact electrodes from bottom to top, silicon substrate layer, SiGe epitaxial layer, silicon nitride layer with window, and in the silicon nitride window A nickel-silicon compound layer is placed, and the silicon nitride window is covered with an aluminum electrode. The silicon germanium Schottky diode with this structure has a large contact area between the silicon germanium and the silicon nitride, and there are many interface defects, resulting in a large leakage current of the device. During the manufacturing process, a silicon germanium layer is grown on a silicon substrate first, and then a layer of silicon nitride is grown on the silicon germanium layer. Since silicon germanium materials will undergo strain relaxation at high temperatures, only low-temperature deposition of silicon nitride is used, which brings great limitations to subsequent device isolation and integration processes.

Contents of the invention

The purpose of the utility model is to provide a germanium-silicon schottky diode with a novel structure, so as to improve the quality of the germanium-silicon schottky diode prototype device.

The silicon germanium Schottky diode of the utility model comprises a silicon substrate, a silicon germanium layer, a silicon nitride layer with a window, a nickel silicon compound layer, an aluminum electrode and an ohmic contact electrode, an ohmic contact electrode, a silicon substrate and a window with The silicon nitride layer of the window is stacked successively from bottom to top, the silicon germanium layer and the nickel silicon compound layer are in the window of the silicon nitride layer, wherein the nickel silicon compound layer is on the silicon germanium layer, and the silicon nitride layer is in the window An overlying aluminum electrode in contact with the nickel silicon compound layer.

The manufacture method of the silicon germanium schottky diode of the present utility model comprises the following steps:

1) Put the cleaned silicon substrate into a low-pressure chemical vapor deposition device, and grow a silicon nitride layer at 700-800°C with SiH ₂ Cl ₂ and NH ₃ as gas sources. The thickness of silicon nitride is 0.5 ~0.6μm;

2) At 600°C, a layer of silicon dioxide is grown on the surface of silicon nitride with silane as the gas source, and the thickness of the silicon dioxide is 0.2-0.3 μm;

3) Photoetch a window on the surface of the silicon dioxide layer, and remove the exposed silicon nitride layer at the window with hot phosphoric acid at 180°C;

4) Putting it into an ultra-high vacuum chemical vapor deposition device to grow a germanium-silicon layer at a growth temperature of 550-650° C., so that the thickness of the germanium-silicon layer is smaller than that of silicon nitride;

5) removing the silicon dioxide layer with hydrofluoric acid with a concentration of 5%, and the silicon germanium layer deposited on the silicon dioxide layer is also removed simultaneously;

6) Put the sample into the evaporation equipment, and use the electron beam evaporation method to evaporate a layer of metallic nickel with a thickness of 10-30nm on the surface of the silicon nitride and silicon germanium layer;

7) Put it in a rapid heat treatment furnace, anneal at 400-700°C for 30-90 seconds, form a nickel-silicon compound layer on the germanium-silicon layer at the window, and clean it with 1:1 concentrated sulfuric acid and hydrogen peroxide after cooling;

8) Put the product obtained in step 7) into the evaporation equipment, and vapor-deposit aluminum electrodes and ohmic contact electrodes with a thickness of 200 nm on both sides of the product;

9) Etch the electrode back, remove the aluminum deposited on the silicon nitride, and then carry out aluminum alloying at 450° C. for at least 10 minutes.

The aforementioned silicon substrate may be a heavily doped N-type or P-type silicon substrate with a resistivity of 10 ^-3 Ω·cm.

Since the silicon germanium Schottky diode of the utility model is only limited in the photolithography window surrounded by the silicon nitride layer, the contact area between the silicon germanium and the dielectric layer is greatly reduced, the interface density is reduced, and the leakage of the device is reduced. current, improving the performance of the device, which is completely different from the traditional Schottky diode structure. Since the silicon germanium layer of the device only exists at the photolithographic window, the device manufacturing does not require any isolation technology, which simplifies the process and improves the integration level.

Description of drawings

Fig. 1 is a structural schematic diagram of a silicon germanium Schottky diode prototype device of the present invention.

Detailed ways

The utility model is further described below in conjunction with specific examples.

With reference to Fig. 1, the germanium-silicon Schottky diode of the present utility model comprises silicon substrate 1, germanium-silicon layer 2, silicon nitride layer 3 with window, nickel-silicon compound layer 4, aluminum electrode 5 and ohmic contact electrode 6, The ohmic contact electrode 6, the silicon substrate 1 and the silicon nitride layer 3 with a window are successively stacked from bottom to top, and the silicon germanium layer 2 and the nickel-silicon compound layer 4 are in the window of the silicon nitride layer 3, wherein the nickel-silicon The compound layer 4 is on the silicon germanium layer 2, covering the aluminum electrode in contact with the nickel silicon compound layer on the window of the silicon nitride layer.

The method for making the utility model germanium-silicon Schottky diode, the steps are as follows:

1) After cleaning the N-type (100) silicon substrate with a resistivity of 0.008Ω·cm, put it into a low-pressure chemical vapor deposition device, and grow a layer of nitrogen at 750°C with SiH ₂ Cl ₂ and NH ₃ as gas sources silicon nitride layer, the thickness of silicon nitride is 0.5 μm;

2) Then grow a silicon dioxide layer on the surface of the silicon nitride at 600° C. with silane as the gas source, and the thickness of the silicon dioxide is 0.2 μm;

3) Use the standard photolithography process to first photoetch a window on the surface of the silicon dioxide layer, the size of the window is determined by the size of the photolithography plate, and then use 180°C hot phosphoric acid to remove the exposed silicon nitride layer at the window;

4) Put the photoetched sample into an ultra-high vacuum chemical vapor deposition device to grow a germanium-silicon layer at a growth temperature of 550° C., so that the thickness of the germanium-silicon layer is smaller than that of silicon nitride;

5) removing the silicon dioxide layer with hydrofluoric acid with a concentration of 5%, and the silicon germanium layer deposited on the silicon dioxide layer is also removed simultaneously;

6) Put the sample into the evaporation equipment, and use the electron beam evaporation method to evaporate a layer of metallic nickel with a thickness of 20nm on the surface of the silicon nitride and silicon germanium layer;

7) Put it in a rapid heat treatment furnace, anneal at 500°C for 60 seconds, and form a nickel-silicon compound layer on the germanium-silicon layer at the window, and clean it with 1:1 concentrated sulfuric acid and hydrogen peroxide after cooling;

8) Put the product obtained in step 7) into an evaporation device, and vapor-deposit an aluminum electrode and an ohmic contact electrode with a thickness of 200 nm on both sides of the product according to a conventional method;

9) Etch the electrode back, remove the aluminum deposited on the silicon nitride, and then carry out aluminum alloying at 450° C. for 10 minutes to obtain the silicon germanium Schottky diode of the present invention.

Claims (1)

1. germanium, silicon Schotty diode, comprise silicon substrate (1), germanium silicon layer (2), have the silicon nitride layer (3) of window, nisiloy compound layer (4), aluminium electrode (5) and Ohm contact electrode (6), it is characterized in that Ohm contact electrode (6), silicon substrate (1) and the silicon nitride layer (3) that has a window are repeatedly put from bottom to top successively, germanium silicon layer (2) and nisiloy compound layer (4) are in the window of silicon nitride layer (3), wherein nisiloy compound layer (4) covers the aluminium electrode (5) that contacts with nisiloy compound layer (4) on the window of silicon nitride layer on germanium silicon layer (2).

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