CN103361732A - Preparation process of N-type heavily-doped phosphorus master alloy silicon rod - Google Patents

Abstract

The invention discloses a preparation process of an N-type heavily-doped phosphorus master alloy silicon rod. The preparation process comprises the following steps of: selecting a single crystal furnace, a 20 graphite thermal field and a 20 quartz crucible, and heating to melt 70kg of polycrystalline silicon; placing 520g of N high-purity red phosphorus into a quartz doper; installing an adapting doper at a seed crystal bayonet, ascending the adapting doper into an auxiliary chamber of the single crystal furnace to guide air, then, opening a flap valve, descending the quartz doper to a tested 390-mm position, enabling the air to be sublimated and automatically guided into a silicon melt, and pulling crystals under the conditions that the rotating speed of a crystal rod is 12r/min, the rotating speed of the crucible is 8r/min, the pulling speed of the head of the crystal rod is 1.1mm/min, and the pressure of the furnace is 2000-2500Pa; and cutting the pulled crystal rod into cakes with the thickness of 2cm, grading according to the electrical resistivity, then, treating by using a water quenching technology, pickling, then, preparing fragments with the size of 5-20mm by using a silicon briquette mutual-collision method, packaging according to different grades, and labeling for self use or sell. The safety in preparing the N-type heavily-doped phosphorus master alloy silicon rod is ensured, and the electrical resistivity of the crystal rod is uniform and ranges from 0.001 to 0.005ohm.cm.

Description

The heavily doped phosphorus mother alloy of a kind of N-type silicon rod preparation technology

Technical field

The present invention relates to the heavily doped phosphorus mother alloy of a kind of N-type silicon rod preparation technology.

Background technology

High-purity crystalline silicon is important solar energy photovoltaic material.Mix micro-group III A element (as boron) in silicon single crystal, form the p-type silicon semiconductor; Mix the VA family element (as phosphorus) of trace, form the N-shaped semi-conductor.This bi-material all can be made solar cell, changes solar radiant energy into electric energy.

Semiconductor element silicon belongs to four main group elements in the periodic table of elements, and the outermost electron number of its atom has 4, and this is a kind of more stable element.If mix III family boron, because boron atom outermost layer only has three electronics, it,, than the outer few electronics of Siliciumatom, after the doped with boron atom, produces hole in Siliciumatom in the Siliciumatom lattice, and this silicon be doped is P-type semiconductor.If adulterate group Ⅴ element in silicon single-crystal, as phosphorus or arsenic, phosphorus and arsenic atom outermost electron number have five, and it can increase the conductivity of silicon than the many electronics of the out-shell electron number of Siliciumatom as conductor, and the silicon of this doping is N-type semiconductor.

The purity how many electric property of semiconductor material and dopings reach doped source has direct relation.Generally, in manufacturing these materials and doping process, all need to carry out under super-clean environment, otherwise unwanted detrimental impurity also becomes doped source, polluted semiconductor material, had a strong impact on the quality of materials and devices.

From theory, no matter be that boron doped P type silicon chip or the N-type silicon chip of phosphorus doping can be used for preparing solar cell.But now most crystal silicon solar energy battery manufacturer all adopts the P type silicon chip of boron-doping to produce solar cell in the world.Because solar cell open circuit voltage and packing factor prepared by the N-type silicon chip are lower, and life-time service or while depositing, N-type silicon chip solar cell properties can be degenerated to some extent; And form the N+ emitter junction on the p-type silicon chip, than form the P+ emitter junction on the N-type silicon chip, on suitability for industrialized production, more easily realize.

The P type silicon solar cell efficiency of conversion of main flow suitability for industrialized production can be stabilized in more than 18% at present, will be in the situation that do not increase cost and raise the efficiency again very difficult, so people turn to the minority carrier lifetime N-type silicon more much higher than P type silicon to eye, and have obtained remarkable progress.

It is high that the first, P type silicon solar cell has efficiency of conversion, and the advantages such as technology maturation are occupied the overwhelming majority of world's solar cell yield.But in manufacturing processed, diffusion system knot technique need to temperature approximately 1000 ℃ carry out, complex process, yield rate is low.And N-type silicon solar cell production technique can carried out below 200 ℃.Meet low cost, high yield, high efficiency requirement.

The second, the minority carrier lifetime of the N-type silicon chip of same resistivity is higher than P type silicon chip.(annotate: minority carrier lifetime has reflected solar cell surface and the matrix Compound Degree to photo-generated carrier, has reflected the degree of utilizing of photo-generated carrier, and minority carrier lifetime is higher, and the short-circuit current of solar cell, open circuit voltage also can improve.Be the important parameter of solar cell design, production, but it can be subject to the impact of high-temperature process.）

The 3rd, the N-type silicon chip will be higher than P type silicon chip to the tolerance of metallic pollution.

Summary of the invention

Its purpose of the present invention just is to provide the heavily doped phosphorus mother alloy of a kind of N-type silicon rod preparation technology, and the security while having guaranteed to make the heavily doped phosphorus mother alloy of N-type silicon rod, make crystal bar uniform resistivity and scope at the 0.001-0.005 ohmcm.

The technical scheme that realizes above-mentioned purpose and take, processing step comprises,

1), select a single crystal growing furnace, adopt 20 " graphite field and 20 " quartz crucible, 70 kilograms of policrystalline silicons of charge amount, heat fused;

2), the high-purity red phosphorus of 520 grams " N " is packed in quartzy doping device;

3), to adapt to the doping device and be contained in the seed crystal bayonet socket, rise up into air guide in auxiliary chamber of single crystal furnace, open again flap valve the quartz device that adulterates is dropped to the 390mm position of having tested, its distillation is imported in silicon melt automatically, and 12 rev/mins of crystal bar rotating speeds, 8 rev/mins of crucible rotations, crystal bar head pulling rate 1.1mm/ divides, and carries out crystal pulling under the condition of furnace pressure 2000-2500Pa;

4), the crystal bar drawn, can be cut into the round pie of 2 cm thicks, by the resistivity stepping, difference is 0.0005 ohmcm, then adopts the shrend technical finesse, after pickling, adopts silico briquette to touch mutually method, make the fragment that is of a size of the 5-20 millimeter, then the stepping packing, posting label can use by oneself or sell.

Compared with prior art the present invention has the following advantages.

The invention provides the heavily doped phosphorus mother alloy of a kind of N-type silicon rod preparation technology, the security while having guaranteed to make the heavily doped phosphorus mother alloy of N-type silicon rod, make crystal bar uniform resistivity and scope at the 0.001-0.005 ohmcm.

The accompanying drawing explanation

Below in conjunction with accompanying drawing, the invention will be further described .

Fig. 1 is the axial distribution of resistivity in crystal bar (resistivity and boule length concern schematic diagram).

Embodiment

Processing step comprises,

1) select a single crystal growing furnace, adopt 20 " graphite field and 20 " quartz crucible, 70 kilograms of policrystalline silicons of charge amount, heat fused;

2) the high-purity red phosphorus of 520 grams " N " is packed in quartzy doping device;

3) will adapt to the doping device and be contained in the seed crystal bayonet socket, rise up into air guide in auxiliary chamber of single crystal furnace, open again flap valve the quartz device that adulterates is dropped to the 390mm position of having tested, make its distillation automatically import in silicon melt, and 12 rev/mins of crystal bar rotating speeds, 8 rev/mins of crucible rotations, crystal bar head pulling rate 1.1mm/ divides, and carries out crystal pulling under the condition of furnace pressure 2000-2500Pa;

4) crystal bar drawn, can be cut into the round pie of 2 cm thicks, by the resistivity stepping, difference is 0.0005 ohmcm, then adopts the shrend technical finesse, after pickling, adopts silico briquette to touch mutually method, make the fragment that is of a size of the 5-20 millimeter, then the stepping packing, posting label can use by oneself or sell.

The present invention, described doping agent is called again mother alloy, is to utilize single crystal growing furnace to participate in silicon melt obtained by red phosphorus in certain ratio of sending out.The sublimation point of the described red phosphorus of this technique under normal pressure is 416 С, and meeting high temperature can sharply distil, and may set off an explosion.So red phosphorus must have a special container; And temperature must strictly measure and be controlled at its sublimation temperature, but can not be too high.Low-temperature distillation characteristic due to red phosphorus, can not answer with solid-state form gas form to mix in the silicon materials of high temperature, must design a kind of special phosphorus mechanism of mixing, by gaseous state red phosphorus, controlledly gently import in silicon melt, so both can prevent that red phosphorus from gasifying suddenly, pressure increases sharply and produces danger, can effectively control phosphorus again and mix speed, reaches pre-provisioning request.The invention of this technique is to utilize single crystal growing furnace, sets specific processing condition (quartz container is contained carrier gas state red phosphorus) and draws crystal with parameter.Owing to taking the special process measure, the security while having guaranteed to make the heavily doped phosphorus mother alloy of N-type silicon rod, make crystal bar uniform resistivity and scope at the 0.001-0.005 ohmcm.

1. the axial-temperature gradient of 85 type thermal field of single crystal furnace test:

Annotate: the red phosphorus in quartz container approximately just starts distillation in 390 mm places at distance stove flap valve flange, draws thus the size of quartz container, designs drawing, entrusts quartzy equipment factory to process.

2. the resistivity distribution figure (as shown in Figure 1) of the N++ crystal bar prepared.The resistivity of the heavily doped mother alloy rod of N++ all, in the scope of 0.001-0.005 ohmcm, meets design requirements, shows the technology of preparing success.

3. the crystal bar that drawn, can be cut into the round pie of 2 cm thicks, and by the resistivity stepping, difference is 0.0005 ohmcm.Then adopt the shrend technical finesse, after pickling, adopt silico briquette to touch mutually method, make the fragment that is of a size of the 5-20 millimeter.Stepping packing again, post after label the doping agent (being mother alloy) that just can be used as the N-type silicon chip and use.

Embodiment

1, select sky dragon 85 type single crystal growing furnaces, adopt 20 " graphite field and 20 " quartz crucible, 70 kilograms of policrystalline silicons of charge amount, heat fused;

2, (designing and process special according to early stage the dynamic thermal field of single crystal growing furnace being carried out to the longitudinal temperature gradient test data) quartz of the high-purity red phosphorus of 520 grams " N " being packed into adulterates in device;

3, will adapt to the doping device and be contained in the seed crystal bayonet socket, rise up into air guide in concubine, open again flap valve the quartz device that adulterates is dropped to the 390mm position of having tested, make its distillation automatically import in silicon melt, and at the crystal bar rotating speed--12 rev/mins, crucible rotation--8 rev/mins, crystal bar head pulling rate--1.1mm/ divides, furnace pressure--carries out crystal pulling under the condition of 2000-2500Pa;

4, the crystal bar drawn, can be cut into the round pie of 2 cm thicks, and by the resistivity stepping, difference is 0.0005 ohmcm.Then adopt the shrend technical finesse, after pickling, adopt silico briquette to touch mutually method, make the fragment that is of a size of the 5-20 millimeter.Stepping is packed again, and posting label can use by oneself or sell;

5, the workman need be with safe respirator to be wiped furnace operating, needs in case of necessity to use oxygen breathing apparatus.Because red phosphorus itself is nontoxic, but become phosphorous oxides after the oxidation by air of red phosphorus dust, just there is toxicity.So pull in the wiping stove operation after crystal bar, must dress gas mask and Labor protection clothing, wipe clearly furnace wall with wet rag, suck the dust on graphite piece with suction cleaner.Wiping the stove dirt need focus on.Material end to end and pot bottom material after crystal pulling are also wanted collective custody, in order to avoid affect monocrystalline and the production of casting polycrystalline from now on.

Claims (1)

1. the heavily doped phosphorus mother alloy of a N-type silicon rod preparation technology, is characterized in that, processing step comprises,

1) select a single crystal growing furnace, adopt 20 " graphite field and 20 " quartz crucible, 70 kilograms of policrystalline silicons of charge amount, heat fused;

2) the high-purity red phosphorus of 520 grams " N " is packed in quartzy doping device;

3) will adapt to the doping device and be contained in the seed crystal bayonet socket, rise up into air guide in auxiliary chamber of single crystal furnace, open again flap valve the quartz device that adulterates is dropped to the 390mm position of having tested, make its distillation automatically import in silicon melt, and 12 rev/mins of crystal bar rotating speeds, 8 rev/mins of crucible rotations, crystal bar head pulling rate 1.1mm/ divides, and carries out crystal pulling under the condition of furnace pressure 2000-2500Pa;

4) crystal bar drawn, can be cut into the round pie of 2 cm thicks, by the resistivity stepping, difference is 0.0005 ohmcm, then adopts the shrend technical finesse, after pickling, adopts silico briquette to touch mutually method, make the fragment that is of a size of the 5-20 millimeter, then the stepping packing, posting label can use by oneself or sell.

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