Method and device for semi-molten ingot casting of polycrystalline silicon

Abstract

The invention discloses a method and device for semi-molten ingot casting of polycrystalline silicon. Crushed aggregates of the polycrystalline silicon are evenly laid at the bottom of a quartz crucible and then sequentially vacuumized and heated, and a heated fragment layer is obtained; the temperature of an ingot furnace heater rises, the power ratio of a top heater and a side heater is adjusted to let the bottom have continuous refrigerating capacity, and it is guaranteed that seed crystal is not molten; after the temperature is reduced, the power ratio of the top heater and the side heater is adjusted, the temperature is kept unchanged to grow crystal; the temperature of the ingot furnace heater continues to be reduced, the power ratio coefficient of the top heater and the side heater is adjusted to control the crystal growth speed to grow crystal; after the crystal grows, annealing and cooling are performed sequentially, and the semi-molten ingot casting of polycrystalline silicon is obtained. According to the method and device for semi-molten ingot casting of the polycrystalline silicon, the heater structure does not need to be changed, the operation is simple, and the goal of effectively discharging impurities and improving product quality can be achieved through specific process parameters.

Description

Technical field

[0001] The invention belongs to the technical field of polysilicon preparation, and in particular relates to a polysilicon semi-melted ingot casting method and device.

Background technique

[0002] At present, in the photovoltaic industry technology industry, the solar polycrystalline ingot semi-melting process has been unanimously promoted by the market due to its advantages such as good crystal flowers, and the improvement of polycrystalline silicon ingot casting technology is one of the main ways to reduce battery costs. Impurities and oxygen contained in cast polysilicon will form hard spots and other impurities that will affect the conversion efficiency of solar cells. In the semi-melting process, because the side part is not completely melted, the impurities and oxygen in the raw materials are not effectively removed, resulting in the formation of hard spots during the ingot casting process, which has a great impact on the quality of the product. T...

Examples

Embodiment 1

[0047] 1) Evenly lay polysilicon fragments with a diameter of 3 mm and a thickness of 8 mm on the bottom of the quartz crucible so that the thickness of the fragment layer reaches 8 mm, and then vacuumize and heat in sequence to obtain a heated fragment layer;

[0048] 2) Raise the temperature of the heater of the ingot furnace to 1550°C, and then adjust the power ratio of the top heater and the side heater to 1:0.2, so that there is continuous cooling at the bottom to ensure that the seed crystal is not melted; when the seed crystal When the remaining thickness is 10mm, the cooling air flow rate at the bottom is 20ml / s, and after the temperature gradually drops to 1430°C, adjust the power ratio of the top heater and the side heater to 0.5:0.8 at the same time, and keep the temperature constant, and grow the crystal for 20 minutes;

[0049] 3) The cooling air flow rate at the bottom is 20ml / s, continue to reduce the temperature of the ingot furnace heater to 1400°C, the power r...

Embodiment 2

[0054] 1) Evenly lay polysilicon fragments with a diameter of 5 mm and a thickness of 10 mm on the bottom of the quartz crucible so that the thickness of the fragment layer reaches 20 mm, and then vacuumize and heat in sequence to obtain a heated fragment layer;

[0055] 2) Raise the temperature of the ingot furnace heater to 1552°C, and then adjust the power ratio of the top heater and the side heater to 1:0.2, so that there is continuous cooling at the bottom to ensure that the seed crystal is not melted; when the seed crystal When the remaining thickness is 10mm, the cooling air flow rate at the bottom is 40ml / s, and after the temperature gradually drops to 1435°C, adjust the power ratio of the top heater and side heater to 0.5:0.8 at the same time, keep the temperature constant, and grow crystals for 30 minutes;

[0056] 3) The cooling air flow rate at the bottom is 40ml / s, continue to reduce the temperature of the ingot furnace heater to 1404°C, the power ratio coefficient...

Embodiment 3

[0061] 1) Evenly lay polysilicon fragments with a diameter of 10 mm and a thickness of 30 mm on the bottom of the quartz crucible, so that the thickness of the fragment layer reaches 30 mm, and then vacuumize and heat in sequence to obtain a heated fragment layer;

[0062] 2) Raise the temperature of the heater of the ingot furnace to 1555°C, and then adjust the power ratio of the top heater and the side heater to 1:0.2, so that there is continuous cooling at the bottom to ensure that the seed crystal is not melted; when the seed crystal When the remaining thickness is 10mm, the cooling air flow rate at the bottom is 50ml / s, and after the temperature gradually drops to 1440°C, adjust the power ratio of the top heater and the side heater to 0.5:0.8 at the same time, and keep the temperature constant, and grow the crystal for 40 minutes;

[0063] 3) The cooling air flow rate at the bottom is 50ml / s, continue to reduce the temperature of the ingot furnace heater to 1410°C, the pow...

Technical field

[0001] The invention belongs to the technical field of polysilicon preparation, and in particular relates to a polysilicon semi-melted ingot casting method and device.

Background technique

[0002] At present, in the photovoltaic industry technology industry, the solar polycrystalline ingot semi-melting process has been unanimously promoted by the market due to its advantages such as good crystal flowers, and the improvement of polycrystalline silicon ingot casting technology is one of the main ways to reduce battery costs. Impurities and oxygen contained in cast polysilicon will form hard spots and other impurities that will affect the conversion efficiency of solar cells. In the semi-melting process, because the side part is not completely melted, the impurities and oxygen in the raw materials are not effectively removed, resulting in the formation of hard spots during the ingot casting process, which has a great impact on the quality of the product. T...

Examples

Embodiment 1

[0047] 1) Evenly lay polysilicon fragments with a diameter of 3 mm and a thickness of 8 mm on the bottom of the quartz crucible so that the thickness of the fragment layer reaches 8 mm, and then vacuumize and heat in sequence to obtain a heated fragment layer;

[0048] 2) Raise the temperature of the heater of the ingot furnace to 1550°C, and then adjust the power ratio of the top heater and the side heater to 1:0.2, so that there is continuous cooling at the bottom to ensure that the seed crystal is not melted; when the seed crystal When the remaining thickness is 10mm, the cooling air flow rate at the bottom is 20ml / s, and after the temperature gradually drops to 1430°C, adjust the power ratio of the top heater and the side heater to 0.5:0.8 at the same time, and keep the temperature constant, and grow the crystal for 20 minutes;

[0049] 3) The cooling air flow rate at the bottom is 20ml / s, continue to reduce the temperature of the ingot furnace heater to 1400°C, the power r...

Embodiment 2

[0054] 1) Evenly lay polysilicon fragments with a diameter of 5 mm and a thickness of 10 mm on the bottom of the quartz crucible so that the thickness of the fragment layer reaches 20 mm, and then vacuumize and heat in sequence to obtain a heated fragment layer;

[0055] 2) Raise the temperature of the ingot furnace heater to 1552°C, and then adjust the power ratio of the top heater and the side heater to 1:0.2, so that there is continuous cooling at the bottom to ensure that the seed crystal is not melted; when the seed crystal When the remaining thickness is 10mm, the cooling air flow rate at the bottom is 40ml / s, and after the temperature gradually drops to 1435°C, adjust the power ratio of the top heater and side heater to 0.5:0.8 at the same time, keep the temperature constant, and grow crystals for 30 minutes;

[0056] 3) The cooling air flow rate at the bottom is 40ml / s, continue to reduce the temperature of the ingot furnace heater to 1404°C, the power ratio coefficient...

Embodiment 3

[0061] 1) Evenly lay polysilicon fragments with a diameter of 10 mm and a thickness of 30 mm on the bottom of the quartz crucible, so that the thickness of the fragment layer reaches 30 mm, and then vacuumize and heat in sequence to obtain a heated fragment layer;

[0062] 2) Raise the temperature of the heater of the ingot furnace to 1555°C, and then adjust the power ratio of the top heater and the side heater to 1:0.2, so that there is continuous cooling at the bottom to ensure that the seed crystal is not melted; when the seed crystal When the remaining thickness is 10mm, the cooling air flow rate at the bottom is 50ml / s, and after the temperature gradually drops to 1440°C, adjust the power ratio of the top heater and the side heater to 0.5:0.8 at the same time, and keep the temperature constant, and grow the crystal for 40 minutes;

[0063] 3) The cooling air flow rate at the bottom is 50ml / s, continue to reduce the temperature of the ingot furnace heater to 1410°C, the pow...

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