CN101191252A

CN101191252A - Method for removing natural oxidizing layer before silicon chip low-temperature epitaxy growth

Info

Publication number: CN101191252A
Application number: CNA2006101184968A
Authority: CN
Inventors: 王剑敏
Original assignee: Shanghai Hua Hong NEC Electronics Co Ltd
Current assignee: Shanghai Huahong Grace Semiconductor Manufacturing Corp
Priority date: 2006-11-20
Filing date: 2006-11-20
Publication date: 2008-06-04

Abstract

The invention discloses a method for removing natural oxidizing layer before low temperature epitaxial growth of silicon slice; the method of the invention can be carried out in relatively short time and under relatively low temperature, thereby the invention has the advantages of simplifying process, lowering cost and avoiding the damage on the surface of the silicon. The invention includes following procedures: (1) the reaction cavity of the silicon slice is charged with the gases (ClF3 and H2); (2) after the oxidizing reaction of the charged gas and the natural oxidizing layer, the SiOF or Si2OF6 generated by the natural oxidizing layer is volatilized. The parameters of the gases(ClF3 and H2) are that the flow rates of the ClF3 and the H2 are less than 1slm and 5 to 100slm respectively, the time is 30 to 120s, the temperature is lower than 700 DEG C, the pressure is less than 700Torr; (3) the reaction cavity of the silicon slice is charged with the mixed gas(H2) again to expel the remained gas(ClF3).

Description

Before silicon chip low-temperature epitaxy growth, remove the method for natural oxidizing layer

Technical field

The present invention relates to a kind of method of before silicon chip low-temperature epitaxy growth, removing natural oxidizing layer.

Background technology

Single crystal epitaxial materials such as present low temperature (less than 700 ℃) epitaxy method grown silicon or germanium silicon, holder's consequence in semiconducter device is made, but the complicated and difficult control of technology, especially before deposit low temperature silicon or germanium and silicon epitaxial, need the natural oxidizing layer and the metal impurities on surface are fully removed, to guarantee low-temperature epitaxy direct growth on monocrystalline substrate, not so the crystalline quality of low-temperature epitaxy will variation, is grown to serve as noncrystal or polycrystal, thereby influences the performance of device.Existing removal method is generally:

The first step, gas drivings such as use argon gas are for your plasma bombardment silicon chip surface, to remove surface oxide layer.

Second step increased germane air-flow his-and-hers watches top blast and sweeps, because the germanium oxide volatilization is very fast, it is very fast to remove surface oxide layer.

The 3rd step, use HF-LAST (using hydrofluoric acid treatment at last) to clean, at high temperature continue hot pre-treatment of long period then, and the hydrogenation air-blowing is swept.

In the 4th step, use low flow silicon line with the formation silicon monoxide, thereby make desorption accelerate.

But there is following problem in above-mentioned technology:

1, the argon gas ion bombardment can form damage or pollution at silicon face.

2, the germane gas flow purging germanium film of can growing on the surface, thus device performance influenced.

3, the pyritous hydrogen treat can increase the diffusion again of dopant in the substrate, makes device electrical performance change.

Except that above-mentioned distinct disadvantage, the whole process flow complexity, the operating time is long, and cost is higher.

Summary of the invention

Technical problem to be solved by this invention provides a kind of method of removing natural oxidizing layer before silicon chip low-temperature epitaxy growth, it can carry out under short period and lesser temps, and then simplified technology, and reduced cost, also avoided damage in addition to silicon chip surface.

In order to solve above technical problem, the invention provides a kind of method of before silicon chip low-temperature epitaxy growth, removing natural oxidizing layer, it comprises the steps: the first step, feeds gas ClF in the reaction chamber of silicon chip ₃And H ₂In second step, after feeding gas and natural oxidizing layer oxidizing reaction, wherein natural oxidizing layer generates SiOF or Si ₂OF ₆Volatilization.

At the described ClF of the first step ₃And H ₂Gas standard is as follows: flow: H ₂Be 5slm-100slm, ClF ₃Less than 1slm; Time: 30s-120s; Temperature is less than 700 ℃; Pressure is less than 700Torr.

It also comprised for the 3rd step, fed H once more ₂Mixed gas is with residual ClF ₃Gas is driven away.

Because the present invention adopts ClF ₃(chlorine trifluoride) and H ₂The surface purges just can finish the removal natural oxidizing layer, compare with the rapid treatment process of multistep in the prior art, simplified technology, compare with argon gas ion bombardment in the prior art, avoided the damage to silicon face, continued hot pre-treatment of long period down with high temperature of the prior art, the present invention can finish under short period (60s-120s) and lesser temps, so just shorten the process time, and then reduced cost.

Description of drawings

Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.

Fig. 1 is the method flow synoptic diagram that the present invention removes natural oxidizing layer;

Fig. 2 is the operating process synoptic diagram of Fig. 1 correspondence.

Embodiment

As shown in Figure 1, it is the method flow synoptic diagram that the present invention removes natural oxidizing layer, describes in conjunction with Fig. 2, and Fig. 2 is the operating process synoptic diagram of Fig. 1 correspondence.It comprises the steps:

Step 101 is at first carried out silicon chip RCA and is cleaned, and puts it in the reaction cavity then; This moment, silicon chip comprised the very thin natural oxidizing layer of substrate 1 and one deck 2, and the thickness of natural oxidizing layer 2 is less than 10 dusts, and the natural oxidizing layer 2 of this moment is not stoichiometric zone of oxidation SiO2, but suboxide SiO.Wherein RCA is the english abbreviation of the Radio Corporation of America, and RCA cleans the purging method that is meant with the said firm's name.

Step 102 feeds ClF in RTCVD (chemical vapor deposition is rapidly heated) reaction cavity ₃And H ₂Natural oxidizing layer 2 to silicon chip purges, wherein ClF ₃And H ₂Gas standard is as follows: H ₂Flow control between 5slm-100slm, ClF ₃Flow control within less than 1slm, the time is controlled between the 30s-120s, temperature is less than 700 ℃, pressure is less than 700Torr.Such as H ₂Flow be 50slm, ClF ₃Flow be 0.3slm, the pressure 650Torr of cavity, purge time are 120s.

Step 103, in the RTCVD reaction cavity, ClF ₃(SiO just) carries out chemical reaction with natural oxidizing layer 2, generates SiOF and HCl volatilization, and it would, of course, also be possible to generates Si2OF6.

Step 104 purges H to silicon chip surface once more in the RTCVD reaction cavity ₂Mixed gas 60s is with residual ClF ₃Gas is removed clean, wherein H ₂Flow is 70slm, time 120s, cavity pressure 650Torr this moment, 670 ℃ of temperature.

Step 105 after natural oxidizing layer is eliminated, just can have been carried out the growth of low-temperature epitaxy, as shown in Figure 2, has generated low-temperature epitaxy layer 3 at last.

Because entire treatment temperature of the present invention can remain on below 700, has so just reduced the influence of high temperature to silicon chip, and can shorten the time of waiting for cooling, and simple to operate than prior art, work simplification.

Claims

1. a method of removing natural oxidizing layer before silicon chip low-temperature epitaxy growth is characterized in that it comprises the steps:

The first step feeds gas CIF in the reaction chamber of silicon chip ₃And H ₂

In second step, after feeding gas and natural oxidizing layer oxidizing reaction, wherein natural oxidizing layer generates SiOF or Si ₂OF ₆Volatilization.

2. the method for removing natural oxidizing layer before silicon chip low-temperature epitaxy growth as claimed in claim 1 is characterized in that it also comprised for the 3rd step, feeds H once more ₂Mixed gas is with residual CIF ₃Gas is driven away.

3. the method for removing natural oxidizing layer before silicon chip low-temperature epitaxy growth as claimed in claim 1 or 2 is characterized in that, comprises also that before carrying out the first step silicon chip is carried out RCA to be cleaned.

4. the method for removing natural oxidizing layer before silicon chip low-temperature epitaxy growth as claimed in claim 1 is characterized in that, described low-temperature epitaxy growth is silicon single crystal or the monocrystalline germanium silicon in growth below 700 ℃.

5. the method for removing natural oxidizing layer before silicon chip low-temperature epitaxy growth as claimed in claim 1 is characterized in that, at the described CIF of the first step ₃And H ₂Gas standard is as follows: flow: H ₂Be 5slm-100slm, CIF ₃Less than 1slm; Time: 30s-120s; Temperature is less than 700 ℃; Pressure is less than 700Torr.