CN102110742A

CN102110742A - Method for passivating crystal silicon P-type surface

Info

Publication number: CN102110742A
Application number: CN201010564187XA
Authority: CN
Inventors: 董经兵; 宋文涛; 陶龙忠; 邢国强
Original assignee: Altusvia Energy Taicang Co Ltd
Current assignee: Altusvia Energy Taicang Co Ltd
Priority date: 2010-11-30
Filing date: 2010-11-30
Publication date: 2011-06-29

Abstract

The invention discloses a method for passivating a crystal silicon P-type surface. The method comprises the following steps of: removing the borosilicate glass from the surface of an N-type crystal silicon wafer subjected to boron diffusion and cleaning the surface; generating a thin SiO2 layer on the cleaned silicon wafer surface; depositing a SiNx layer on the surface of the generated SiO2 thin layer by a plasma enhanced chemical vapor deposition (PECVD) method. The method provided by the invention is suitable for industrialization production and has characteristics of simple heat treatment process, good anti-reflection effect and good passivation quality.

Description

The passivating method on a kind of crystalline silicon P type surface

Technical field

The present invention relates to the passivating method on crystalline silicon P type surface, particularly N type battery P ⁺The passivating method on emitter junction surface.

Background technology

The passivating technique on crystalline silicon P type surface is meant and is passing through at crystalline silicon P type surface or P ⁺Emitter junction superficial growth or metallization medium layer, thus effectively reduce crystalline silicon P type surface or P ⁺The recombination-rate surface of emitter junction.

At present crystal silicon solar energy battery mainly is to be the conventional solar cell of substrate with P type crystalline silicon, and the passivation that relates to mainly is N ⁺The passivation on emitter junction surface; And present PECVD SiNx can effectively reduce N ⁺The recombination-rate surface of emitter junction can provide good sunken light effect simultaneously, is being used widely.

Compare with P type crystal silicon cell, advantage such as N type crystal silicon cell has the efficient height, and photo attenuation is low, thereby will obtain better development from now on.But because the SiNx of PECVD deposition carries a large amount of positive charge (~ 10 ¹²), thereby will be at crystalline silicon P ⁺The emitter junction surface forms inversion layer, thereby causes the generation of leakage current; Thereby seek a kind of suitable P ⁺The passivating method on surface is a key factor that realizes the development of N type battery industry.

Summary of the invention

Goal of the invention: the objective of the invention is to overcome the deficiencies in the prior art, a kind of suitable suitability for industrialized production, low-cost, the passivating method on crystalline silicon P type surface efficiently are provided.

Technical scheme: to achieve these goals, the invention provides the passivating method on a kind of crystalline silicon P type surface, the concrete steps of this method are as follows:

(1) the N type crystal silicon chip (as shown in Figure 1) that boron diffusion is finished is removed the Pyrex on surface, and is cleaned;

(2) the silicon chip surface growth one deck SiO that finishes in cleaning ₂Thin layer;

(3) at the SiO that has grown and finished ₂The thin layer surface adopts plasma chemical gas phase PECVD mode to deposit layer of sin x.

SiO in the described step (2) ₂Thin layer is grown in dense HNO3 or dense H2SO4 or KMnO4 solution, and dense HNO3 or dense H2SO4 or KMnO4 solution concentration are 6% ~ 98%.

SiO in the described step (2) ₂The growing environment temperature of thin layer is: 15 ~ 140 ℃, the reaction time is 5 ~ 60 minutes, and the thickness of SiO2 thin layer is greater than 1nm.

The refractive index of the SiNx thin layer that generates in the described step (3) is 1.9 ~ 2.2, and the SiNx thickness of thin layer is 60 ~ 100nm.

Beneficial effect: the passivating method on a kind of crystalline silicon P type of the present invention surface compared with prior art has following advantage:

1, adopt the method for the invention can prevent P ⁺The generation of emitter junction surface inversion layer again can be to P ⁺The emitter junction surface provides good passivation effect, and the method for the invention also possesses the required low cost of industrialization production and the advantage of high yield simultaneously;

2, adopt the method for the invention can effectively reduce crystalline silicon P ⁺The recombination rate on emitter junction surface improves the short wave response of N type solar cell, and then improves the conversion efficiency of N type crystal silicon solar energy battery;

3, the method for the invention is fit to few, the good anti-reflective effect of industrialization production, heat treatment process, good passivation quality.

Description of drawings

The N type silicon chip that Fig. 1 finishes for B diffusion.

Fig. 2 forms SiO among the embodiment ₂The minority carrier life time comparison diagram of SiNx individual layer in/SiNx layer and the prior art.

Embodiment

Below in conjunction with specific embodiment, further illustrate the present invention, should understand these embodiment only is used to the present invention is described and is not used in and limit the scope of the invention, after having read the present invention, those skilled in the art all fall within the application's claims to the modification of the various equivalent form of values of the present invention and limit.

Embodiment 1

The passivating method on a kind of crystalline silicon P type surface, the concrete steps of this method are as follows:

(1) adopt the N type crystal silicon chip of 1 Ω cm to carry out two-sided boron diffusion, the sheet resistance of diffusion is 50 ohms/square, and the N type crystal silicon chip of then boron diffusion being finished is removed the Pyrex on surface, and cleaned;

(2) to put into temperature be that 110 ℃, concentration are that 69% red fuming nitric acid (RFNA) carries out oxidation to the silicon chip of finishing in cleaning, after 30 minutes at the SiO of silicon chip surface growth one deck 3nm ₂Thin layer;

(3) at the SiO that has grown and finished ₂The thin layer surface adopts plasma chemical gas phase PECVD mode to deposit layer of sin x film; The SiNx film thickness is 75nm, and refractive index is 2.1.

Adopt behind the silicon chip sintering after the present embodiment passivation with adopt the conventional method sintering after the individual layer SiNx that generates compare, minority carrier life time contrasts as shown in Figure 1.

Embodiment 2

(1) adopt the N type crystal silicon chip of 1 Ω cm to carry out two-sided boron diffusion, the sheet resistance of diffusion is 50, and the N type crystal silicon chip of then boron diffusion being finished is removed the Pyrex on surface, and cleaned;

(2) to put into temperature be that 120 ℃, concentration are that 90% the concentrated sulfuric acid carries out oxidation to the silicon chip of finishing in cleaning, after 45 minutes at the SiO of silicon chip surface growth one deck 1.1nm ₂Thin layer;

(3) at the SiO that has grown and finished ₂The thin layer surface adopts plasma chemical gas phase PECVD mode to deposit layer of sin x film; The SiNx film thickness is 60nm, and refractive index is 1.9.

Embodiment 3

(2) to put into temperature be that 70 ℃, concentration are that 16% potassium permanganate carries out oxidation to the silicon chip of finishing in cleaning, after 10 minutes at the SiO of silicon chip surface growth one deck 2nm ₂Thin layer;

(3) at the SiO that has grown and finished ₂The thin layer surface adopts plasma chemical gas phase PECVD mode to deposit layer of sin x film; The SiNx film thickness is 100nm, and refractive index is 2.2.

Claims

1. the passivating method on a crystalline silicon P type surface, it is characterized in that: the concrete steps of this method are as follows:

(1) the N type crystal silicon chip that boron diffusion is finished is removed the Pyrex on surface, and is cleaned;

2. the passivating method on a kind of crystalline silicon P type according to claim 1 surface is characterized in that: SiO in the described step (2) ₂Thin layer is grown in dense HNO3 or dense H2SO4 or KMnO4 solution, and the concentration range of dense HNO3 or dense H2SO4 or KMnO4 solution is 6% ~ 98%.

3. the passivating method on a kind of crystalline silicon P type according to claim 2 surface is characterized in that: SiO in the described step (2) ₂The growing environment temperature of thin layer is: 15 ~ 140 ℃, the reaction time is 5 ~ 60 minutes, and the thickness of SiO2 thin layer is greater than 1nm.

4. the passivating method on a kind of crystalline silicon P type according to claim 1 surface is characterized in that: the refractive index of the SiNx thin layer that generates in the described step (3) is 1.9 ~ 2.2, and the SiNx thickness of thin layer is 60 ~ 100nm.