CN103048360A - Method for measuring concentration of germanium or/and tin impurity in crystalline silicon - Google Patents

Abstract

The invention discloses a method for measuring concentration of germanium or/and tin impurity in crystalline silicon, which comprises the following steps of: doping boron or phosphorus into a germanium or/and tin mother alloy; and determining the concentration of germanium or/and tin by measuring the resistivity of a silicon chip. According to the invention, the phosphorus or boron is doped into the germanium tin mother alloy, the relationship between the resistivity of mother alloy and the concentration of germanium tin impurity is established, and the concentration of the germanium tin impurity can be determined by measuring the resistivity of the mother alloy; and the method is simple and convenient to operate, solves the difficulty in detecting the concentration of current germanium tin mother alloy, reduces the production cost and improves the production efficiency.

Description

Germanium in the crystalline silicon is or/and the measuring method of tin impurity concentration

Technical field

The present invention relates to germanium in a kind of crystalline silicon or/and the measuring method of tin impurity concentration.

Background technology

Studies show that both at home and abroad, in the sun power industry, the crystalline silicon growth time is mixed germanium, tin can obviously improve the properties of material, thus mix germanium in the monocrystalline silicon, tin impurity has very wide application prospect in the sun power industry.In large-scale production process, the means by the preparation foundry alloy realize accurate control to doped chemical, and therefore, the development of germanium tin foundry alloy has its necessity.Because germanium, tin impurity are electrically not aobvious in crystalline silicon, this just causes germanium tin foundry alloy impurity concentration can't use conventional means to measure, the present SIMS(of employing secondary ion mass spectrum), the methods such as ICP-MS, GDMS are measured germanium tin foundry alloy impurity concentrations, these methods all need the preparation standard sample, and need to measure in high-purity environment, cost is high.

Summary of the invention

The object of the present invention is to provide germanium in a kind of crystalline silicon or/and the measuring method of tin impurity concentration, solved the problem of present germanium tin foundry alloy impurity concentration detection difficult.

The object of the present invention is achieved like this, and germanium in the crystalline silicon is or/and the measuring method of tin impurity concentration is that boron or phosphorus are mixed germanium or/and in the tin foundry alloy, by measuring silicon chip resistivity, determine germanium or/and the concentration of tin specifically may further comprise the steps:

Step 1. is mixed boron or phosphorus, germanium simultaneously or/and tin adopts conventional pulling of crystals autofrettage in the solar-grade polysilicon raw material, form silicon melt, under argon shield atmosphere, makes the foundry alloy silicon rod;

Step 2. cuts into the foundry alloy silicon chip with gained foundry alloy silicon rod in the step 1, and recycling solar energy level silicon material cleaning is cleaned germanic foundry alloy silicon chip surface;

Step 3. is utilized the electricalresistivityρ of four probe method measuring process 2 gained foundry alloy silicon chips, according to single crystal silicon resistivity and concentration of dopant reduction formula, and the doping content of boron or phosphorus in the calculating foundry alloy silicon chip.

Step 4. utilizes in the crystal fractional condensation computing formula (1) to draw sampling foundry alloy silicon chip residing volume fraction g on the foundry alloy crystal bar,

C _s＝C ₀Ke(1-g) ^(Ke-1) (1)

In the formula:

C _s---the doping content cm of boron or phosphorus in the foundry alloy silicon rod ^-3

C ₀---the concentration c m of boron or phosphorus in the silicon melt of boron or phosphorus ^-3

The segregation coefficient of Ke---boron or phosphorus;

The volume fraction of g---boron or phosphorus;

Step 5. is calculated step 4 the segregation coefficient K of gained g value, germanium or tin _E1With germanium or the tin concentration C in the silicon melt ₀₁, substitution formula (1) can be calculated the concentration C of germanium in the foundry alloy silicon chip or tin impurity _S1

Characteristics of the present invention also are:

The purity of boron or phosphorus is 6N-7N; The purity of germanium or tin is 5N-7N.

Boron or phosphorus doping density are not more than 5 * 10 ¹⁵Atom/cm3.

Boron-doping foundry alloy sampling silicon wafer thickness is 1 ~ 3mm; Mixing phosphorus foundry alloy sampling silicon wafer thickness is 1 ~ 2mm.

, need first with the annealing in process of head through 550 ~ 650 ℃ during with interior sampling at foundry alloy silicon rod head volume mark 15%.

The present invention has following beneficial effect, the present invention mixes germanium or/and in the tin foundry alloy with phosphorus or boron, by measuring foundry alloy resistivity, determine the concentration of phosphorus or boron, and then calculate germanium or/and the volume fraction of tin, calculate germanium or/and the concentration of tin by volume fraction, method is simple, easy to operate, the testing result of its testing result and prior art approaches, and deviation is very little, can satisfy Production requirement, solve present germanium or/and the technical matters of tin foundry alloy concentration detection method complexity has reduced cost, improved production efficiency.

Embodiment

Germanium in the crystalline silicon provided by the invention is or/and the measuring method of tin impurity concentration is that boron or phosphorus are mixed germanium or/and in the tin foundry alloy, by measuring silicon chip resistivity, determine germanium or/and the concentration of tin.

Its principle is: different impurities segregation coefficient in monocrystalline silicon there are differences, and is theoretical according to fractional condensation, determines that the key factor that impurity distributes in monocrystalline silicon is volume fraction, and between the different impurities and do not make significant difference.Can realize on this basis when impurity is mixed altogether, calculating the concentration of another kind of impurity by a kind of concentration of impurity.

The present invention reaches the purpose of determining the germanium tin concentration by measuring crystal resistivity.At first, because germanium tin is electrically not aobvious in silicon crystal, and boron phosphorus can be determined its concentration by resistivity measurement; Simultaneously, impurity meets the fractional condensation rule in silicon crystal, and this is just for realizing that deriving the germanium tin concentration by measurement boron phosphorus provides theoretical foundation.

In actual tests, determine the foundry alloy sheet in the residing volume fraction of whole foundry alloy crystal bar by the resistivity of measuring the foundry alloy sheet, derive by volume fraction, doping content and the impurity segregation coefficient in crystalline silicon again and calculate corresponding relation between resistivity and the germanium tin impurity concentration.

Find in actual tests, if the phenomenon of segregation coefficient drift can appear in heavily doped boron phosphorus in germanium tin foundry alloy, therefore, for the deviation of the testing result that reduces the germanium tin concentration, the present invention determines that the boron phosphorus concentration should be not more than 5 * 10 in germanium tin foundry alloy ¹⁵

For guaranteeing the homogeneity of foundry alloy sheet concentration, boron-doping foundry alloy sheet thickness range should be 1 ~ 3mm; Mix phosphorus foundry alloy sheet thickness range 1 ~ 2mm.This moment, foundry alloy sheet two sides concentration difference was less than 1%; Can be considered Uniform Doped.

Germanium tin foundry alloy crystal bar head volume mark 15% is with interior crystal bar, should through 550 ~ 650 ℃ annealing in process with after eliminating oxygen alms giver effect, carry out resistivity again and detect.

Below in conjunction with embodiment the present invention is described in further detail.

Germanium in embodiment 1. crystalline silicons or/and the measuring method of tin impurity concentration comprise the steps:

1. the purity of mixing simultaneously 0.005 gram in 150000 gram solar-grade polysilicon raw materials is that the boron powder of 6N-7N, the purity of 2000 grams are 5N-7N germanium, by pulling of crystals autofrettage (CZ method), form silicon melt, under argon shield atmosphere, make the germanic foundry alloy silicon rod of P type;

2. utilize inner circle cutting or multi-wire saw mode that the germanic foundry alloy silicon rod in the step 1 is cut into thickness and be the germanic foundry alloy silicon chip of 3mm, recycling solar energy level silicon material cleaning is cleaned germanic foundry alloy silicon chip surface;

3. utilize the electricalresistivityρ of the germanic foundry alloy silicon chip of four probe method measuring process 2 gained, mix formula in phosphorus single crystal silicon resistivity and the concentration of dopant conversion rules according to the GB/T13389-1992 boron-doping, calculate the boron concentration N (ρ) of germanic foundry alloy silicon chip, formula is as follows:

$N\left(\mathrm{\ρ}\right)=\frac{1.33\×{10}^{16}}{\mathrm{\ρ}}+\frac{1.082\×{10}^{17}}{\mathrm{\ρ}[1+{\left(54.56\mathrm{\ρ}\right)}^{1.105}}---\left(2\right)$

In the formula: ρ---resistivity Ω cm;

N (ρ)---boron impurity concentration c m ^-3

4. utilize in the crystal fractional condensation computing formula (1) to draw sampling foundry alloy silicon chip residing volume fraction g on the foundry alloy crystal bar,

C _s＝C ₀Ke(1-g) ^(Ke-1) (1)

Wherein, the boron element correlation parameter is as follows:

C _s=N(ρ)；

C _o=(28.086×0.005)/(10.811×150000)；

Ke=0.8；

5. with gained g value in the step 4 and germanium impurity parameters C ₀₁=(28.086 * 2000)/(72.61 * 150000); Ke ₁=0.35 substitution formula (1) calculates the concentration C of germanium in germanic foundry alloy silicon chip _S1

Table 1 has been listed the corresponding relation of foundry alloy resistivity and germanium concentration, thereby can extrapolate by the resistivity of foundry alloy the concentration of germanium; Table 1 has also been listed result's contrast of adopting measuring method of the present invention and existing SIMS measuring method that a plurality of germanic foundry alloy silicon chips are measured.

The measurement result contrast of table 1 measuring method of the present invention and SIMS measuring method

From upper watch test result contrast as can be known, detection method of the present invention and SIMS detection method measured result approach, and the deviation maximum is no more than 15%, can satisfy production requirement.

Germanium in embodiment 2. crystalline silicons or/and the measuring method of tin impurity concentration comprise the steps:

1. the purity of mixing simultaneously 0.005 gram in 150000 gram solar-grade polysilicon raw materials is that the phosphorus of 6N-7N, the purity of 2000 grams are the tin of 6N-7N, by pulling of crystals autofrettage (CZ method), form silicon melt, under argon shield atmosphere, make the stanniferous foundry alloy silicon rod of N-type;

2. utilize the modes such as inner circle cutting, multi-wire saw to be cut to thickness the stanniferous foundry alloy silicon in the step 1 and be the stanniferous foundry alloy silicon chip of 1mm, recycling solar energy level silicon material cleaning is cleaned stanniferous foundry alloy silicon chip surface;

3. utilize the electricalresistivityρ of the stanniferous foundry alloy silicon chip of four probe method measuring process two gained, mix the formula of phosphorus single crystal silicon resistivity and concentration of dopant conversion rules according to the GB/T13389-1992 boron-doping, calculate the phosphorus concentration N (ρ) of stanniferous foundry alloy silicon chip, formula is as follows:

$N\left(\mathrm{\ρ}\right)=\frac{6.242\×{10}^{18}}{\mathrm{\ρ}}\×{10}^Z---\left(3\right)$

In the formula: ρ---resistivity Ω cm;

N (ρ)---phosphorus impurities concentration c m ^-3

$Z=\frac{A_0+A_{1}x+A_2{x}^2+A_3{x}^3}{1+B_{1}x+B_2{x}^2+B_3{x}^3}---\left(4\right)$

In the formula: x=log ₁₀ρ; A ₀=-3.1083; A ₁=-3.2626; A ₂=-1.2196; A ₃=-0.13923; B ₁=1.0265; B ₂=0.38755; B ₃=0.041833;

4. in crystal fractional condensation computing formula (1), with following parameter substitution, draw the residing volume fraction g of the stanniferous foundry alloy silicon chip of sampling, determine the stanniferous foundry alloy silicon chip of sampling residing position on crystal with this;

C _s＝C ₀Ke(1-g) ^(Ke-1) (1)

P elements correlation parameter wherein:

C _s=N(ρ)；

C ₀=(28.086×0.005)/(30.97×150000)；

Ke=0.35；

5. with step 4 gained g value and tin impurity parameters C ₀₁=(28.086 * 2000)/(118.71 * 150000) and Ke ₁=0.03 substitution formula (1) can be calculated the concentration C of tin impurity in stanniferous foundry alloy silicon chip _S1Table 2 is the corresponding relation of foundry alloy resistivity and tin concentration, thereby extrapolates the concentration of tin by the resistivity of foundry alloy.

Table 2 foundry alloy resistivity and corresponding tin concentration

Resistivity Ω cm	Adopt the present invention to calculate the concentration c m of tin -3
		4.62	8.54E+18
4.49	9.39E+18
		4.32	1.04E+19

4.13	1.17E+19
		3.95	1.34E+19
3.79	1.56E+19
		3.62	1.88E+19
3.43	2.42E+19

When while doped germanium, tin, both are independent of each other because of germanium, tin, so, calculate respectively by embodiment 1 and embodiment 2 described methods and to get final product to get germanium impurity concentration and tin impurity concentration.

Claims (5)

1. In the crystalline silicon germanium or/and the measuring method of tin impurity concentration it is characterized in that, boron or phosphorus are mixed germanium or/and in the tin foundry alloy, by measuring silicon chip resistivity, determine germanium or/and the concentration of tin specifically may further comprise the steps:

   Step 1. is mixed boron or phosphorus, germanium simultaneously or/and tin adopts conventional pulling of crystals autofrettage in the solar-grade polysilicon raw material, form silicon melt, under argon shield atmosphere, makes the foundry alloy silicon rod;

   Step 2. cuts into the foundry alloy silicon chip with gained foundry alloy silicon rod in the step 1, cleans again;

   Step 3. is utilized the electricalresistivityρ of four probe method measuring process 2 gained foundry alloy silicon chips, according to single crystal silicon resistivity and concentration of dopant reduction formula, and the doping content of boron or phosphorus in the calculating foundry alloy silicon chip.

   Step 4. utilizes in the crystal fractional condensation computing formula (1) to draw sampling foundry alloy silicon chip residing volume fraction g on the foundry alloy crystal bar,

   C _s＝C ₀Ke(1-g) ^(Ke-1) (1)

   In the formula:

   C _s---the doping content cm of boron or phosphorus in the foundry alloy silicon rod ^-3

   C ₀---the concentration c m of boron or phosphorus in the silicon melt ^-3

   The segregation coefficient of Ke---boron or phosphorus;

   The volume fraction of g---boron or phosphorus;

   Step 5. is calculated step 4 the segregation coefficient K of gained g value, germanium or tin _E1With germanium or the tin concentration C in the silicon melt ₀₁, substitution formula (1) can be calculated the concentration C of germanium in the foundry alloy silicon chip or tin impurity _S1
2. In the crystalline silicon according to claim 1 germanium or/and the measuring method of tin foundry alloy impurity concentration it is characterized in that, the purity of described boron or phosphorus is 6N-7N; The purity of described germanium or tin is 5N-7N.
3. In the crystalline silicon according to claim 1 germanium or/and the measuring method of tin impurity concentration it is characterized in that, described boron or phosphorus doping density are not more than 5 * 10 ¹⁵Atom/cm ³
4. In the crystalline silicon according to claim 1 germanium or/and the measuring method of tin impurity concentration it is characterized in that, boron-doping foundry alloy sampling silicon wafer thickness is 1 ~ 3mm; Mixing phosphorus foundry alloy sampling silicon wafer thickness is 1 ~ 2mm.
5. In the crystalline silicon according to claim 1 germanium or/and the measuring method of tin impurity concentration it is characterized in that,, need first with the annealing in process of head through 550 ~ 650 ℃ during with interior sampling at foundry alloy silicon rod head volume mark 15%.