TW201508102A - Construction of crystal growth furnace for lateral mobile heating - Google Patents

Abstract

The present invention relates to a construction of crystal growth furnace for lateral mobile heating comprising a crystal growth furnace body, a quartz crucible inside the crystal growth furnace body, and a top heater and a lateral heater set in the peripheral of the quartz crucible. The top heater corresponds to the top of the quartz crucible, and the lateral heater corresponds to the lateral margin of the quartz crucible. A power element is configured to the lateral heater, so as to move the lateral heater vertically on the peripheral of the quartz crucible and to control the temperature gradient of the quartz crucible, further to retard the silicon molten crystal growth on the wall of the quartz crucible.

Description

Lateral moving heated crystal growth furnace construction

The present invention relates to a crystallized furnace configuration for laterally moving heating, and more particularly to a lateral heater of a crystal growth furnace that is vertically movable along a side edge of the quartz crucible for controlling a temperature gradient change of the quartz crucible.

Referring to the fifth figure, the crystal growth furnace (A) structure of the conventional solar twin crystal ingot generally comprises: an insulating cage (B); a quartz crucible (C), placed in the insulating cage (B), There is a heat sink (D) at the bottom of the quartz crucible (C); a heater (E) is placed in the insulating cage (B), usually including a top heater (E1) near the top of the quartz crucible (C) And the side heater (E2) is adjacent to the side edge of the quartz crucible (C).

The crystal growth process of the solar crystal ingot is divided into five stages: heating, melting, growing, annealing and cooling. The heating process uses the aforementioned heater (E) to raise the temperature inside the crystal growth furnace to about 1300 ゚C, so that the solid material reaches the pre-melting state; during the melting process, the solid material will be slowly melted from the top to the melting point. Soup (F); during the growth process, the insulating cage (B) is lifted to create a gap at the bottom of the insulating cage (B), so that the quartz crucible (C) transmits heat conduction through the heat dissipating mat (D), and through the The heat convection effect of the gap makes the bottom heat dissipation speed of the melting furnace (F) faster, so that the upper and lower layers of the quartz crucible (C) have a temperature gradient change from high temperature to low temperature, so the crucible soup (F) is bottomed The upward solidification grows into a twinned ingot; the purpose of the annealing process is to eliminate the internal stress of the twinned ingot, so that the twinned ingot is not cracked during processing; the cooling process cools the twinned ingot to reach room temperature.

Actually, the DSS (Directional Solidification System) crystal growth furnace developed by GT-SOLAR was tested. Please refer to the sixth and seventh figures, respectively, for the first hour and the fifth hour of the crystal growth process, in the quartz crucible. The solid-liquid phase distribution diagram shows a solid twine ingot (G) at the bottom and a liquid strontium melt (F) at the top. The above phenomenon indicates that when the bottom of the smelting soup (F) is gradually cooled, the heat energy is transmitted outward through the gap at the bottom of the insulating cage, so that the two side wall surfaces of the quartz crucible are cooled faster, and the lattice begins to grow inward from the wall surface. At this time, the solid-liquid interface is concave, and this type of twinned ingot (G) will cause the internal impurities of the smelting soup (F) to be easily discharged to the outside, and will be deposited in the cerium crystal, and the twin crystal ingot (G) The internal stress is also large, and it is easy to cause damage to the twinned ingot (G) in the subsequent cutting process.

Thus, in order to obtain a better quality solar crystal ingot, the present invention proposes a laterally heated heating crystal growth furnace structure, which utilizes a lateral heater that can move vertically on the side edge of the quartz crucible to control the temperature gradient change of the quartz crucible. To solve the problem that the twin crystal ingot grows from the inner wall surface of the quartz crucible.

The invention includes:

a crystal growth furnace body; a quartz crucible disposed in the crystal growth furnace body; a top heater disposed in the crystal growth furnace body and corresponding to the top of the quartz crucible; a side heater Inserted in the crystal growth furnace body and corresponding to the side edge of the quartz crucible; a power element is connected to the lateral heater for controlling the lateral heater to move vertically on the side edge of the quartz crucible.

Further, the power component includes an actuating lever and a cylinder connected to the actuating lever, and the lateral heater is disposed on the actuating lever.

The effect of the invention is:

The movable lateral heater is used to control the temperature gradient of the quartz crucible. When the twin ingot starts to grow, the lateral heater is close to the bottom of the quartz crucible, so the radial temperature difference at the initial stage of the growth of the twin ingot is maximized. The grain grows vertically, and the lateral heater moves to make the radial temperature gradient of the quartz crucible smaller, the vertical temperature gradient becomes larger, and the quartz crucible wall surface maintains a higher temperature, so the grain side length at the quartz crucible wall surface The situation will also decrease, the overall temperature will become more uniform during growth, and the grain growth direction will be vertically upward from the bottom of the quartz crucible, so that the solid-liquid interface is flat, which can obtain a better twin crystal structure and reduce the defect density of the crystal. The overall quality of the solar crystal ingot is improved, and the photoelectric conversion efficiency of the subsequently processed polycrystalline silicon wafer is also high.

In combination with the above technical features, the main effects of the laterally heated heating crystal growth furnace construction of the present invention will be apparent from the following examples.

Referring to the first figure, a preferred embodiment of the present invention includes:

a crystal growth furnace body (1); a quartz crucible (2), placed in the crystal growth furnace body (1); a top heater (3), placed in the crystal growth furnace body (1), And corresponding to the top of the quartz crucible (2); a side heater (4), placed in the crystal growth furnace body (1), and corresponding to the side edge of the quartz crucible (2); a power component (5) comprising an actuating lever (51) connected to the lateral heater (4), and a pressure cylinder (52) connected to the actuating lever (51), whereby the lateral heater (4) can be controlled The side edge of the quartz crucible (2) moves vertically.

Referring to the second figure, the crystal growth test of the present embodiment is performed based on the DSS crystal growth furnace system. When the material is melted, the operating rod (51) is controlled by the pressure cylinder (52) to drive the lateral direction. The heater (4) moves toward the bottom of the quartz crucible (2), so that the height of the crucible can be controlled by controlling the lateral heater (4) to move the height so that the crucible can be melted from top to bottom. When the crystal grows, the cylinder (52) controls the actuating rod (51) to move the lateral heater (4) to follow the growing solid-liquid interface and gradually move toward the top of the quartz crucible (2). In the long crystal mode, when the tantalum melt (6) begins to solidify into a twin ingot (7), the lateral heater (4) is close to the bottom of the quartz crucible (2), thus in a twinned ingot (7) The radial temperature difference at the beginning of growth is the largest, so that the crystal grains can grow vertically, and the quartz crucible (2) wall surface maintains a high temperature at any time, so that the smelting soup (6) can be slowed down from the quartz crucible (2) The phenomenon that the wall begins to crystallize and grow. It is further explained that the power component (5) is a preset motion mode according to the temperature gradient in the quartz crucible (2) required by the user, and the user can perform simulation or other experiments according to the user. The method is decided and will not be described here.

Referring to the third and fourth figures, respectively, the first and second hours of the crystal growth process, the solid solution distribution of the quartz crucible (2), and the condensation of the crucible soup (6) is found in the figure. When the ingot (7) is cast, the lateral solidification phenomenon of the inner wall surface of the quartz crucible (2) is significantly slowed down compared to the conventional DSS crystal growth furnace mentioned in the prior art, and the present invention The growing twin crystal ingot (7) has a relatively uniform temperature, which can obtain a better twin crystal structure, reduce the defect density of the crystal, and improve the overall quality of the twinned ingot (7).

In view of the foregoing description of the embodiments, the operation and the use of the present invention and the effects of the present invention are fully understood, but the above described embodiments are merely preferred embodiments of the present invention, and the invention may not be limited thereto. Included within the scope of the present invention are the scope of the present invention.

(1) ‧‧‧Crystal furnace body

(2) ‧‧‧Quartz

(3)‧‧‧ top heater

(4)‧‧‧ Lateral heaters

(5) ‧‧‧Power components

(51)‧‧‧Action rod

(52) ‧‧‧Cylinder

(6) ‧‧‧矽 molten soup

(7)‧‧‧矽crystalline ingots

(A) ‧‧‧Crystal furnace

(B) ‧‧ ‧Insulation cage

(C) ‧‧‧Quartz

(D)‧‧‧ Thermal pad

(E) ‧ ‧ heater

(E1)‧‧‧ top heater

(E2)‧‧‧ Lateral heater

(F)‧‧‧矽 molten soup

(G)‧‧‧矽crystalline ingots

[First figure] is a schematic view showing the structure of the crystal growth furnace of the present invention.

[Second picture] is a schematic diagram of adjusting the temperature gradient of the quartz crucible by using a lateral heater to vertically move on the side edge of the quartz crucible when used in the crystal growth furnace of the present invention.

[Third image] is the first hour of the crystal growth process of the crystal growth furnace of the present invention based on the DSS crystal growth furnace, and the solid-liquid phase distribution diagram of the quartz crucible.

[Fourth figure] is the fifth hour of the crystal growth process of the crystal growth furnace of the present invention based on the DSS crystal growth furnace, and the solid-liquid phase distribution diagram of the quartz crucible.

[Fifth diagram] is a schematic structural view of a conventional crystal growth furnace.

[Sixth image] is the first hour of the crystal growth process of the conventional DSS crystal growth furnace, and the solid-liquid phase distribution diagram of the quartz crucible.

[Seventh image] is the distribution of solid-liquid phase in the quartz crucible for the fifth hour of the conventional DSS crystal growth furnace.

(1) ‧‧‧Crystal furnace body

(2) ‧‧‧Quartz

(3)‧‧‧ top heater

(4)‧‧‧ Lateral heaters

(5) ‧‧‧Power components

(51)‧‧‧Action rod

(52) ‧‧‧Cylinder

Claims (3)

A laterally heated heating crystal growth furnace structure for inserting a quartz crucible for crystal growth, comprising: a crystal growth furnace body for inserting the quartz crucible; and a top heater placed in the crystal growth a furnace body corresponding to the top of the quartz crucible; a side heater disposed in the crystal growth furnace body and corresponding to a side edge of the quartz crucible; a power component connected to the lateral heater It is used to control the lateral heater to move vertically on the side edge of the quartz crucible. The laterally heated heated crystal growth furnace structure of claim 1, wherein the power element includes an actuating rod and a cylinder connected to the actuating rod, and the lateral heater is disposed on the actuating rod. A laterally heated heating crystal growth furnace structure comprising: a crystal growth furnace body; a quartz crucible disposed in the crystal growth furnace body; a top heater disposed in the crystal growth furnace body, and Corresponding to the top of the quartz crucible; a lateral heater is placed in the crystal growth furnace body and corresponds to the side edge of the quartz crucible; a power component is connected to the lateral heater for controlling the side The heater is moved vertically at the side edge of the quartz crucible.