CN101295749B

CN101295749B - Powder metallurgy metallic silicon solar battery underlay producing technique

Info

Publication number: CN101295749B
Application number: CN2008100314982A
Authority: CN
Inventors: 周继承; 赵保星; 李幼真; 陈勇民; 李莉; 荣林艳
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2008-06-16
Filing date: 2008-06-16
Publication date: 2011-07-27
Anticipated expiration: 2028-06-16
Also published as: CN101295749A

Abstract

The invention discloses a preparation technique for powder metallurgy silicon metal solar cell substrate, which makes silicon metal raw materials of 3N and lower into a specific shaped silicon metal spindle by milling, shaping and sintering, and then cuts the silicon metal spindle into thin film solar cell substrate of 300 to 500 micron thick. The substrates prepared by the technique can be used as substrates directly growing big-grain high-quality polycrystalline silicon and amorphous silicon thin films after special extension blocking layer treatment. By matching the thermal expansion coefficient of the substrate with that of the thin film, cracking and scaling of the thin film during high temperature or cooling process are avoided. The invention has the advantages of low cost raw materials, simple technique and is applicable to large scale industrial production. The successful development of the invention lays a solid foundation for the industrialization of thin film solar cells.

Description

A kind of powder metallurgy metallic silicon solar battery underlay producing technique

Technical field

The invention belongs to the solar cell substrate field of material preparation, relate to a kind of powder metallurgy metallic silicon solar battery underlay producing technique.

Background technology

The crystalline silicon raw material continue the higher price of maintenance, make the monocrystaline silicon solar cell cost to reduce significantly.Thin film solar cell is considered to solar cell of new generation, and development of new polycrystal film solar cell becomes first-selected monocrystaline silicon solar cell substitute products.Multi-crystal silicon film solar battery requires light absorbing zone that big as far as possible crystal grain and suitable grain orientation are arranged, reducing minority carrier in cell body and surface compound, thereby improve open circuit voltage, short circuit current and the efficient of multi-crystal silicon film solar battery.

At present, the substrate selected for use of multi-crystal silicon film solar battery mainly contains: the glass of the pottery of high temperature series, granular silicon belt and low temperature series etc.

Selecting ceramic substrate in the high-temperature technology for use is in order to inherit existing ripe crystal silicon solar energy battery high-temperature technology, to reduce cost of developing once more.But ceramic substrate exists a series of problems that are difficult to solve, and comprising: ceramic surface treatment process, ceramic substrate impurity is diffusion problem, silicon thin film thermal expansion cracking problem, crystal grain problem of low quality in film.Need to develop targetedly process of surface treatment, impurity barrier layer technology, heat transition layer process and crystallization processes again in order addressing these problems, to make the multi-crystal silicon film solar battery complex process of ceramic substrate, cost reduce limited like this.

What granular silicon belt used is high-quality silica flour, and the space that reduces cost is limited.China has grasped the technology that is prepared metallic silicon (≤99.9%) by the silicon ore deposit, but the high-purity polycrystalline of electron level, the long-term dependence on import of monocrystalline silicon, the import price of high-purity silicon powder be the metallic silicon export price 2000 surplus times.The large-scale production crystal silicon solar batteries will consume a large amount of 6N level crystal silicon raw material, and this is very unfavorable to China's development solar cell industry on long terms.

Select glass substrate in the low temperature process for use, substrate can not bear the high-temperature technology more than 600 ℃.The film quality of this process system deposit is poor, the general metal inducement technology of assisting that adopts, and need develop special later stage battery structure preparation technology, these technologies all can not with fine butt joint of existing crystal silicon solar energy battery technology, cause research and development and industrial production cost all reduce limited.

At above analysis to various types of substrates, film-substrate determines film crystal grain quality and later stage technology as can be seen.

Summary of the invention

The invention provides a kind of powder metallurgy metallic silicon solar battery underlay producing technique, with solve existing thin-film solar cells substrate processing complexity, cost height, heatproof is low and substrate impurity to defectives such as film diffusions.

The present invention solves the problems of the technologies described above the technical scheme that is adopted to be:

A kind of powder metallurgy metallic silicon solar battery underlay producing technique, it is characterized in that: with purity is 99.0～99.9% metallic silicon raw material through powder process, moulding with 1050～1150 ℃ of sintering (preferred temperature is 1100 ℃), make the metallic silicon spindle, then the metallic silicon spindle is cut into thin slice, on thin slice, adopt chemical vapor process or physical vapor method to deposit an impurity barrier layer.

The temperature retention time of described sintering is 1～2 hour, preferred 2 hours.

Described sintering is at N ₂Or H ₂Carry out under the atmosphere protection under the atmosphere.

As improvement, described N ₂Or H ₂Flow velocity be 10～12L/min (preferred parameter is 10L/min).

Described impurity barrier layer preferably is prepared from by the physical vapour deposition (PVD) mode by the SiC target, and described SiC target is the high-purity alpha-SiC target, and its purity is more than 99.99%.

The thickness of described thin slice is 300～500 microns.

Described being shaped to silicon metal powder compression molding or isostatic compaction.

Metallic silicon optimal seeking of raw and processed materials 3N grade metallic silicon, promptly purity be 99.9% and below.

The wet ball grinding mode is adopted in described powder process, and drying makes 5～10 microns silica flour after sieving and handling.

Beneficial effect of the present invention has:

(1) effectively stop diffusion of impurities: the impurity of metallic silicon substrate stops that preparation can use for reference existing integrated circuits Cu fully and stop technology in interconnected, can effectively stop the diffusion of substrate impurity to film.

(2) the film quality height of Huo Deing: the metallic silicon substrate of handling through the barrier layer itself can serve as the thin film deposition inculating crystal layer is convenient to prepare big crystal grain high-quality polysilicon membrane; The thermal coefficient of expansion of substrate is identical with film, can not have cracking and peel off problem.

(3) cost is low: the raw material of this technology adopts domestic self-produced metallic silicon, and the cost of raw material is low, well below adopting existing 6N level crystal silicon raw material.

(4) be suitable for commercial Application: this underlay producing technique is simple, is convenient to large-scale industrial production.Battery later stage technology can be docked with existing crystal silicon solar energy battery production technology, and industrial prospect is good.

The present invention will provide a kind of backing material fabricating technology of cheap preparation solar cell, avoided the complicated aftertreatment technology of conventional ceramic substrate, both be beneficial to the big crystal grain high-quality polysilicon membrane of deposition, the film cracking problem of more fundamentally having avoided causing because of thermal expansion between polysilicon membrane and substrate, greatly reduce the cost of crystal silicon solar batteries substrate and battery chip, for the networking power generation applications and the photovoltaic industrialization of solar cell are taken a firm foundation.

Embodiment

The invention will be further described below in conjunction with specific embodiment.

Embodiment 1

Powder metallurgy metallic silicon solar battery underlay producing technique may further comprise the steps:

1. 3N (99.9%) is reached following metallic silicon raw material process wet ball grinding 5 hours, drying makes 5～10 microns silica flour after sieving and handling;

2. with silica flour compression molding or isostatic compaction;

3. at flow the H of 10L/min ₂Under the atmosphere protection, under 1100 ℃ of temperature, carry out sintering, be incubated 1 hour, cooling naturally, room temperature is taken out, and makes the metallic silicon spindle of diameter more than 300 millimeters;

4. the metallic silicon spindle is cut into the thin-film solar cells substrate (backing sheet) of 300～500 micron thickness;

5. PVD (physical vapour deposition (PVD)) process deposits one deck impurity barrier layer on the metallic silicon substrate, the preparation on impurity barrier layer also can be developed preparation voluntarily by the user.

About the preparation on impurity barrier layer, preferred following method:

Adopt magnetron sputtering method to prepare the SiC diffusion barrier film, may further comprise the steps:

(1) C target, SiC target (be the high-purity alpha-SiC target, purity is higher than 99.99%) are installed simultaneously in the multi-target magnetic control sputtering instrument.Wherein the C target is in the direct current sputtering position, and the SiC target is in the radio frequency sputtering position; The metallic silicon substrate is cleaned and dries with deionized water, ultrasonic wave, absolute ethyl alcohol, acetone; The control sputtering atmosphere promptly charges into H toward the multi-target magnetic control sputtering instrument ₂Air-flow, stable gas pressure is at 0.9～1.2Pa;

(2) adopt magnetron sputtering method in-situ preparing SiC film; Rotary substrate is to improve into film uniformity.

Claims

1. powder metallurgy metallic silicon solar battery underlay producing technique, it is characterized in that: with purity is 99.0～99.9% metallic silicon raw material through powder process, moulding with at 1050～1150 ℃ of sintering, make the metallic silicon spindle, then the metallic silicon spindle is cut into thickness and be 300～500 microns thin slice, on thin slice, adopt magnetron sputtering method to prepare the SiC diffusion barrier film; The wet ball grinding mode is adopted in described powder process, and drying makes 5～10 microns silica flour after sieving and handling; Described being shaped to silicon metal powder compression molding or isostatic compaction; Described sintering process is for being the N of 10～12L/min at flow velocity ₂Or H ₂Carry out sintering under the atmosphere and be incubated 1-2 hour.

2. a kind of powder metallurgy metallic silicon solar battery underlay producing technique as claimed in claim 1 is characterized in that, metallic silicon optimal seeking of raw and processed materials 3N grade metallic silicon, and promptly purity is 99.9%.