CN113073389B - {03-38} plane silicon carbide epitaxy and growth method thereof - Google Patents

Abstract

The invention discloses a {03‑38} plane silicon carbide epitaxy and a growth method thereof. By using bis(trimethylsilyl)methane as a Si source and a C source, the growth temperature is reduced to reduce the Z1/2 center; the growth The epitaxy structure of the {03-38} plane silicon carbide prepared by the method comprises from top to bottom: a positive axis {03-38} plane SiC substrate, a 4H-SiC buffer layer, and a 4H-SiC drift layer.

Description

A {03-38} plane silicon carbide epitaxy and its growth method

technical field

The invention belongs to the technical field of semiconductor materials, and in particular relates to a {03-38} surface silicon carbide epitaxy and a growth method thereof.

Background technique

The third-generation wide bandgap semiconductor materials represented by SiC materials have the characteristics of wide bandgap, high critical breakdown electric field, high thermal conductivity, high carrier saturation drift, etc., and are especially suitable for making high temperature, high pressure, high frequency, high power, anti- Irradiation and other semiconductor devices.

SiC has multiple crystal planes, and different crystal planes have different characteristics. On the {0001} crystal plane, along the c-axis <0001>, the crystal plane is called the Si crystal plane, while on the {000-1} crystal plane On the plane, which is directed along the c-axis <000-1>, this crystal plane is called the C crystal plane. In addition to the Si and C crystal planes, the {11-20} crystal plane perpendicular to the {0001} crystal plane is called the A crystal plane, and the other {1-100} crystal plane perpendicular to the {0001} crystal plane is called the M crystal plane noodle. There is also a typical non-basal plane {03-38} crystal plane, which is obtained by tilting 54.7 degrees from {0001} to {01-10}.

Based on 4H-SiC Si epitaxy, low background doping can be achieved through the principle of competition, and it is currently widely used. Silicon surface SiC materials are restricted by slow oxidation speed and high channel resistance when preparing MOSFET devices. Therefore, research on other crystal surfaces has begun to attract attention.

The interface state density of the {03-38} plane is 4 to 8 times lower than that of the Si plane. Therefore, the MOSFET device made of the epitaxial layer grown on the {03-38} plane has a low channel resistance, and the {03-38} The growth window of the tube surface is wide, and the C/Si can be in the range of 0.6-5. The surface is good, and the surface has the advantages of free SF and micropipes, but the Z1/2 center of this surface is significantly higher than that of the standard crystal plane, and the Z1/2 center It directly determines the lifetime of carriers, which will seriously restrict the application of {03-38} epitaxial layer in bipolar devices.

Contents of the invention

In order to solve the above technical problems, the present invention provides a {03-38} plane silicon carbide epitaxy and its growth method. By using bis(trimethylsilyl)methane as Si source and C source, the growth temperature is reduced to reduce Z1 /2 center, improve carrier life, because Si-C bond length (188pm) is longer than Si-H (147pm), Si-C bond energy (292 KJ/mol) than Si-H bond energy (313KJ/mol) Low, the growth temperature is 200-300°C lower than the current TCS system or SiH ₄ system, which can significantly reduce the Z1/2 center and increase the carrier lifetime.

The technical scheme that the present invention takes is:

A {03-38} plane silicon carbide epitaxial growth method, the growth method comprising the following steps:

(1) In-situ etching of the SiC substrate on the positive axis {03-38} plane;

(2) Introduce H ₂ , bis(trimethylsilyl)methane, N-type dopant and HCl, and grow a 4H-SiC buffer layer at a temperature of 1350-1550°C and a pressure of 50-500mbar;

(3) Introduce H ₂ , bis(trimethylsilyl)methane, N-type dopant and HCl, and grow 4H-SiC drift on the 4H-SiC buffer layer at a temperature of 1350-1550°C and a pressure of 50-500mbar layer.

Further, in step (2), the thickness of the 4H-SiC buffer layer is 0.1-0.2 μm;

In step (2), the doping concentration of the 4H-SiC buffer layer is 1×10 ¹⁷ to 9×10 ¹⁸ cm ⁻³ .

In the step (2) and step (3), the N-type dopant is N ₂ .

In step (2), the flow rates of H ₂ , bis(trimethylsilyl)methane, N-type dopant and HCl are respectively 200-1000 slm, 100-300 sccm and 50-100 sccm.

In step (3), the thickness of the 4H-SiC drift layer is 5-200 μm;

In step (3), the doping concentration of the 4H-SiC drift layer is 1×10 ¹⁵ to 9×10 ¹⁶ cm ⁻³ .

In step (3), the flow rates of H ₂ , bis(trimethylsilyl)methane, N-type dopant, and HCl are 200-1000 slm, 500-900 sccm, 10-30 sccm, and 15-35 sccm, respectively.

The present invention also provides {03-38} plane silicon carbide epitaxy grown according to the above-mentioned growth method. Buffer layer, 4H-SiC drift layer, the interface state density of the {03-38} plane is 4 to 8 times lower than that of the Si plane, therefore, the MOSFET device made of the epitaxial layer grown on the {03-38} plane has a low channel channel resistance.

In the {03-38} plane silicon carbide epitaxial growth method provided by the present invention, since the epitaxial structure is grown on the {03-38} plane SiC substrate, the interface state density of the {03-38} plane is 4-8 lower than that of the Si plane. times, the MOSFET channel resistance prepared by the grown epitaxial layer is low, but the Z1/2 center defect is high. The present invention uses bis(trimethylsilyl)methane as the Si source and the C source, and the growth temperature is higher than that of the current TCS system and The SiH ₄ system is 200-300°C lower, which can significantly reduce the Z1/2 center and increase the carrier lifetime.

Description of drawings

Fig. 1 is a relationship diagram between growth temperature and Z1/2 center density;

Fig. 2 is a Raman spectrum diagram of the epitaxial layer grown at a temperature of 1350°C.

detailed description

The present invention will be described in detail below in conjunction with examples.

Example

A {03-38} surface silicon carbide epitaxial growth method, comprising the following steps:

1) In-situ etching of the substrate: select the SiC substrate on the positive axis {03-38} surface, and perform standard cleaning; place the SiC substrate in the reaction chamber of the chemical vapor deposition equipment that has been pumped, and then react The chamber is evacuated. Inject H ₂ at a flow rate of 30-600 slm, etch for 5-10 min at a pressure of 50-500 mbar and a temperature of 1400-1550 °C;

2) Growth of the buffer layer: respectively feed carrier gas H ₂ , silicon source bis(trimethylsilyl)methane, and N-type dopant at flow rates of 200-1000slm, 100-300sccm, 20-60sccm and 50-100sccm N ₂ and HCl, grow a 0.1-0.2μm thick 4H-SiC buffer layer at a temperature of 1350-1550°C and a pressure of 50-500mbar, and the N doping concentration in the buffer layer is 1×10 ¹⁷ to 9×10 ¹⁸ cm ^{- 3} ;

3) Growth of the drift layer: Carrier gas H ₂ , bis(trimethylsilyl)methane, and N-type dopant N ₂ are introduced at flow rates of 200-1000slm, 500-900sccm, 10-30sccm and 15-35sccm respectively and HCl, grow a 5-200 μm thick 4H-SiC drift layer at a temperature of 1350-1550° C. and a pressure of 50-500 mbar, and the N doping concentration in the drift layer is 1×10 ¹⁵ to 9×10 ¹⁶ cm ^-3 .

Figure 2 is the Raman spectrum of silicon carbide epitaxy on the {03-38} surface at a growth temperature of 1350°C. It can be seen from the figure that there is no 3C-SiC heterocrystal.

The above detailed description of {03-38} plane silicon carbide epitaxy and its growth method with reference to the examples is illustrative rather than limiting, and several examples can be listed according to the limited scope, so without departing from this Changes and modifications under the general concept of the invention shall fall within the protection scope of the present invention.

Claims (6)

1. A {03-38} surface silicon carbide epitaxial growth method, characterized in that the growth method comprises the following steps: (1) In-situ etching of the SiC substrate on the positive axis {03-38} plane; (2) Feed H ₂ , bis(trimethylsilyl)methane, N-type dopant and HCl, and grow a 4H-SiC buffer layer at a temperature of 1350-1550°C and a pressure of 50-500mbar; (3) Introduce H ₂ , bis(trimethylsilyl)methane, N-type dopant and HCl, and grow 4H-SiC drift on the 4H-SiC buffer layer at a temperature of 1350-1550°C and a pressure of 50-500mbar layer; In step (2), the flow rates of H ₂ , bis(trimethylsilyl)methane, N-type dopant and HCl are respectively 200-1000 slm, 100-300 sccm, 20-60 sccm and 50-100 sccm; In step (3), the flow rates of H ₂ , bis(trimethylsilyl)methane, N-type dopant, and HCl are 200-1000 slm, 500-900 sccm, 10-30 sccm, and 15-35 sccm, respectively. 2. The method for epitaxial growth of silicon carbide on the {03-38} plane according to claim 1, characterized in that in step (2), the thickness of the 4H-SiC buffer layer is 0.1-0.2 μm. 3. The {03-38} plane silicon carbide epitaxial growth method according to claim 1, characterized in that in step (2), the doping concentration of the 4H-SiC buffer layer is 1×10 ¹⁷ to 9× 10 ¹⁸ cm ^-3 . 4 . The {03-38} plane silicon carbide epitaxial growth method according to claim 1 , characterized in that, in step (2) and step (3), the N-type dopant is N ₂ . 5. The method for epitaxial growth of silicon carbide on the {03-38} plane according to claim 1, characterized in that, in step (3), the thickness of the 4H-SiC drift layer is 5-200 μm. 6. The {03-38} plane silicon carbide epitaxial growth method according to claim 1, characterized in that in step (3), the doping concentration of the 4H-SiC drift layer is 1×10 ¹⁵ to 9× 10 ¹⁶ cm ^-3 .

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