CN102810465B - Growing SiO on SiC material2Method for passivating a layer - Google Patents

Abstract

The invention discloses a method for growing SiO on SiC material₂A method for growing passivation layer on semiconductor materialThe field of layer technology. The method comprises growing SiO on SiC material by PECVD₂Passivation layer and p-SiO₂The passivation layer is dense. The method can realize SiO under the condition of lower temperature₂Growth of passivation layers on SiC materials, SiO₂The refractive index of the passivation layer after annealing is reduced from 1.465 to 1.455, SiO₂The compactness degree of the passivation layer is high, and the requirement of SiC material on SiO can be met₂Requirements for passivation layers. Furthermore, the invention provides the growth of SiO on SiC materials₂The method of passivation layer can be used for SiO with a thickness above 100nm₂And growing a passivation layer.

Description

A method of growing SiO2 passivation layer on SiC material

technical field

The invention relates to the technical field of growing a passivation layer on a semiconductor material, in particular to a method for growing a _SiO2 passivation layer on a SiC material.

Background technique

As a new generation of wide bandgap semiconductor material, silicon carbide (SiC) has attracted more and more attention. It has the characteristics of large bandgap width, high critical breakdown field strength, high electron mobility, and high thermal conductivity. Widespread concern. At present, SiC-based JBS devices have been widely used in the field of power electronics.

Ion implantation in SiC-based JBS devices is a key process that affects device performance. The passivation layer grown on SiC materials can reduce implant damage and prevent chip surface from being contaminated.

Currently, methods for growing passivation layers on SiC materials include thermal oxidation and plasma enhanced chemical vapor deposition (PECVD).

The disadvantages of the thermal oxidation method are:

First, thermal oxidation consumes the SiC layer on the surface.

Second, the generated passivation layer contains residual C that cannot be precipitated and remains in the passivation layer. The passivation layer obtained after thermal oxidation has many defects and surface states, which require high temperature annealing to eliminate.

Third, the removal of the passivation layer after the ion implantation process tends to roughen the surface of the SiC layer.

Fourth, if there is a doping process before the thermal oxidation, the long-term thermal oxidation of the SiC layer at 1200 °C will cause the re-diffusion of the previous doping process, and the doping concentration will change. Therefore, thermal oxidation can only be used before the doping process.

Fifth, the thermal oxidation process has strict requirements on oxidation temperature and oxidation time. If a 60nm passivation layer is to be obtained, the temperature is usually above 1200°C, and the oxidation time is as long as 8 to 10 hours. The temperature required is high and the growth time is long. It is difficult to grow a passivation layer with a thickness of more than 100nm by thermal oxidation.

Although the method of growing the passivation layer on the SiC material by PECVD has the characteristics of low growth temperature and fast deposition speed, the defect of this method is that the quality of the passivation layer is poor and relatively loose.

Contents of the invention

In order to solve the above problems, the present invention proposes a method of growing an _SiO2 passivation layer on the SiC material by PECVD first, and then densely growing the _SiO2 passivation layer _on the SiC material.

In order to achieve the above object, the SiO provided by the invention grows on the SiC material _The method for the passivation layer includes:

using PECVD to grow a _SiO2 passivation layer on the SiC material; and,

The _SiO2 passivation layer is dense.

As preferably, said adopting PECVD to grow _SiO2 passivation layer on SiC material comprises:

cleaning SiC material;

Dry and clean the SiC material;

A SiO ₂ passivation layer is grown on the dried SiC material by PECVD.

As a further preference, when cleaning the SiC material, first remove the natural oxide layer on the SiC material with an etching solution, and then perform conventional cleaning.

As a further preference, the proportion of the etching solution is NH ₄ F:HF=6:1, and the etching time is 30 sec.

As a further preference, the drying of the SiC material is achieved by drying the SiC material in an oven for 10 minutes under the condition of 120° C. in N ₂ atmosphere.

As a further preference, the PECVD process conditions are as follows: temperature: 280°C, power: 70w, gas flow: SiH ₄ : 400sccm, N ₂ O: 800sccm, N ₂ : 750sccm, pressure: 900mTorr.

Preferably, the densification of the SiO ₂ passivation layer is to anneal the SiC material grown with the SiO ₂ passivation layer by uniformly increasing and decreasing the temperature.

As a further preference, annealing the SiC material grown with _SiO2 passivation layer by means of uniform heating and uniform cooling includes:

Step 1: Raise the temperature from room temperature to 800°C for 40 minutes.

Step 2: After the temperature reaches 800°C, maintain it for 10 minutes.

Step 3: Raise the temperature from 800°C to 1000°C, the heating rate is 10°C/min, and the elapsed time is 20min.

Step 4: After the temperature reaches 1000°C, keep it for 30 minutes.

Step 5: Cool down from 1000°C to 800°C with a cooling rate of 10°C/min and an elapsed time of 20 minutes.

Step 6: Naturally cool down from 800°C to below 400°C.

As a further preference, the annealing atmosphere is N ₂ , and the flow rate of N ₂ is 1 L/min.

On SiC material provided by the present invention grows SiO _The beneficial effect of the method for passivation layer is:

The method for growing the _SiO2 passivation layer on the SiC material provided by the present invention can realize the growth of the _SiO2 passivation layer on the SiC material under lower temperature conditions, and the refractive index of the _SiO2 passivation layer is from 1.465 to 1.465 after annealing. Reduced to 1.455, the SiO ₂ passivation layer has a high density, which can meet the requirements of SiC materials for the SiO ₂ passivation layer. Moreover, the method for growing a SiO ₂ passivation layer on a SiC material provided by the present invention can be used for growing a SiO ₂ passivation layer with a thickness above 100 nm.

Detailed ways

In order to understand the present invention in depth, the present invention will be described in detail below in conjunction with specific examples.

An embodiment of the present invention provides a method for growing a _SiO2 passivation layer on a SiC material, including:

Step 10, using PECVD to grow _SiO2 passivation layer on the SiC material; this step may include:

Step 101, cleaning the SiC material: corroding the SiC material with an etching solution with a ratio of NH ₄ F:HF=6:1, the etching time is 30 sec, removing the natural oxide layer on the SiC material, and then cleaning the obtained SiC material with deionized water. SiC material.

Step 102: drying the cleaned SiC material: put the cleaned SiC material into an oven at 120° C., and dry it for 10 minutes under N ₂ atmosphere.

Step 103: Using PECVD to grow a SiO ₂ passivation layer on the dried SiC material: temperature: 280°C, power: 70w, gas flow: SiH ₄ : 400 sccm, N ₂ O: 800 sccm, N ₂ : 750 sccm, pressure : Under the process condition of 900mTorr, use PECVD to grow a SiO ₂ passivation layer with a thickness of 100nm on the baked SiC material.

Step 20, densifying the _SiO2 passivation layer; this step may include:

The SiC material with _SiO2 passivation layer is annealed by uniform heating and cooling method:

Put the SiC material with the SiO ₂ passivation layer into the annealing furnace, pass N ₂ into the annealing furnace at a flow rate of 1L/min, and anneal in the N ₂ atmosphere by adopting the method of uniform speed rise and uniform speed drop, Right now:

Step: 201: raising the temperature from room temperature to 800° C. for 40 minutes.

Step 202: After the temperature reaches 800° C., maintain it for 10 minutes.

Step 203: Raise the temperature from 800° C. to 1000° C. with a heating rate of 10° C./min and an elapsed time of 20 minutes.

Step 204: After the temperature reaches 1000° C., maintain it for 30 minutes.

Step 205: Cool down from 1000°C to 800°C at a cooling rate of 10°C/min for 20 minutes.

Step 206: Naturally lower the temperature from 800°C to below 400°C.

Step 207: Take out the SiC material on which the SiO ₂ passivation layer has been grown.

The above method of growing _SiO2 passivation layer on SiC material can realize the growth of _SiO2 passivation layer on SiC material under lower temperature conditions, and the refractive index of _SiO2 passivation layer decreases from 1.465 after annealing As small as 1.455, the SiO ₂ passivation layer has a high density, which can meet the requirements of SiC materials for the SiO ₂ passivation layer. Moreover, the method for growing a SiO ₂ passivation layer on a SiC material provided by the present invention can be used for growing a SiO ₂ passivation layer with a thickness above 100 nm.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. one kind grows SiO in SiC material ₂the method of passivation layer, comprising:

PECVD is adopted to grow SiO in SiC material ₂passivation layer; With,

To described SiO ₂passivation layer is fine and close;

To described SiO ₂passivation layer densification has SiO to described growth ₂the SiC material of passivation layer is annealed;

It is characterized in that,

SiO is had to described growth ₂the SiC material of passivation layer is carried out annealing and is comprised:

Step 1: be warming up to 800 DEG C from normal temperature, elapsed-time standards 40min;

Step 2: after temperature reaches 800 DEG C, maintains 10min;

Step 3: be warming up to 1000 DEG C from 800 DEG C, programming rate 10 DEG C/min, elapsed-time standards 20min;

Step 4: after temperature reaches 1000 DEG C, maintains 30min;

Step 5: be cooled to 800 DEG C from 1000 DEG C, cooling rate 10 DEG C/min, elapsed-time standards 20min;

Step 6: below 800 DEG C of Temperature fall to 400 DEG C.

2. method according to claim 1, is characterized in that: described employing PECVD grows SiO in SiC material ₂passivation layer comprises:

Cleaning SiC material;

SiC material after dry cleaning;

PECVD is adopted to carry out dried SiC material grows SiO ₂passivation layer.

3. method according to claim 2, is characterized in that:

When described SiC material is cleaned, first remove the natural oxidizing layer in described SiC material with corrosive liquid, then carry out routine cleaning.

4. method according to claim 2, is characterized in that:

At N to described SiC material drying ₂atmosphere, under 120 DEG C of conditions, oven dry 10min realizes in an oven.

5. method according to claim 2, is characterized in that:

Described pecvd process condition is as follows: temperature: 280 DEG C, power: 70w, and gas flow is SiH ₄: 400sccm, N ₂o:800sccm, N ₂: 750sccm, pressure: 900mTorr.

6. method according to claim 1, is characterized in that:

The atmosphere of described annealing is N ₂, described N ₂flow be 1L/min.