TW201713804A - Crystal growth apparatus - Google Patents

Abstract

A crystal growth apparatus including a chamber, a pulling rod, a crucible, a heater, a heat insulating cover and a cooler is provided. The pulling rod is disposed in the chamber for pulling a seed crystal. The crucible is disposed in the chamber for containing a raw material melt. The heater is disposed in the chamber and located outside the crucible for heating the raw material melt. The heat insulating cover is disposed in the chamber and located above the crucible. The heat insulating cover has an inner wall and an outer wall. An inner space is between the inner wall and the outer wall. The cooler is disposed in the inner space between the inner wall and the outer wall.

Description

Crystal growth device

This invention relates to a crystal growth apparatus and, more particularly, to a crystal growth apparatus having a cooling element.

In recent years, the semiconductor industry has flourished, and silicon wafers are the most basic necessities of the semiconductor industry. The way in which the wafer is grown includes the Floating Zone Method, the Laser Heated Pedestal Growth, and the Czochralski Method (CZ method). Among them, the Chai's long crystal method has become a major growth mode for large-size wafers because of its better economic benefits.

In the growth of single crystal of the CZ method, in a chamber maintained in an inert gas atmosphere under reduced pressure, a seed crystal is immersed in a crucible material accumulated in a crucible. In the soup, the impregnated seed crystals are slowly pulled to grow a single crystal crucible under the seed crystal. In addition, in the CZ method, a cylindrical or inverted hot-cut curtain is placed around the single crystal crucible grown on the solution to insulate the radiant heat to control the temperature gradient of the grown single crystal crucible. However, when the ingot being gradually pulled out passes through 900 ° C to 1200 ° C during the cooling process, a stacking fault may occur. These overlaps caused by oxidation are simply referred to as OISF (Oxidation Induced Stacking Faults). Therefore, how to speed up the cooling of the ingot, that is, to increase the temperature gradient to reduce the generation of the oxidation stack, has become a subject worthy of study.

The invention provides a crystal growth device which can solve the problem that the temperature gradient is small and the oxidation stack is easily generated in the prior art.

The crystal growth apparatus of the present invention comprises a cavity, a suspension wire, a weir, a heating element, a thermal curtain and a cooling element. The hanging wire is placed in the cavity, and a seed crystal is pulled by the above. The crucible is disposed in the cavity for accommodating a molten soup. The heating element is disposed in the cavity and located at the periphery of the crucible for heating the melt. The thermal curtain is placed in the cavity and above the crucible. The hot curtain has an inner wall and an outer wall. There is an internal space between the inner wall and the outer wall. The cooling element is disposed in an inner space between the inner wall and the outer wall.

In an embodiment of the invention, the side of the hot curtain adjacent to the melt is the bottom and the cooling elements are distributed from the bottom of the hot curtain to the top.

In an embodiment of the invention, the cooling element is a metal tube containing a coolant.

In an embodiment of the invention, the material of the thermal curtain is graphite.

In an embodiment of the invention, the inner and outer walls are removably assembled.

In an embodiment of the invention, the crystal growth device further includes a heat insulating element disposed in the cavity. The heating element is located between the thermal insulation element and the crucible.

In an embodiment of the invention, the crystal growth device further includes a heat insulating material disposed in an inner space between the inner wall and the outer wall.

In an embodiment of the invention, wherein the insulating material is carbon fiber.

Based on the above, in the crystal growth apparatus of the present invention, a cooling element is provided in the thermal curtain, which can increase the temperature gradient of the ingot during the growth of the crystal, thereby improving the quality of the ingot and improving the output efficiency.

The above described features and advantages of the invention will be apparent from the following description.

1 is a schematic cross-sectional view of a crystal growth apparatus in accordance with an embodiment of the present invention. Referring to FIG. 1 , the crystal growth apparatus 100 of the present embodiment includes a cavity 110 , a suspension line 120 , a crucible 130 , a heating element 140 , a thermal curtain 150 , and a cooling element 160 . The cavity 110 is generally in the shape of a barrel and is adapted to pass a blunt gas to the cavity 110. The pressure within the cavity 110 is, for example, 60 torr. The blunt gas is, for example, argon gas, and does not easily react with the crystal growth material to ensure the quality of the crystal rod. The crucible 130 is disposed in the cavity 110 for accommodating a molten soup 50. In the present embodiment, a semiconductor material such as polysilicon and a dopant such as boron or phosphorus may be melted in the crucible 130 at a high temperature of 1420 ° C or higher to form the melt 50. The suspension wire 120 is disposed in the cavity 110, and a seed crystal 60 is pulled by the above. The heating element 140 is disposed in the cavity 110 and located at the periphery of the crucible 130 for heating the melt 50. The thermal curtain 150 is disposed in the cavity 110 and above the crucible 130. The thermal curtain 150 can isolate radiant heat during the pulling process, thereby controlling and increasing the temperature profile of the twine 70.

When the polysilicon material and the dopant are melted to form the melt 50, the suspension wire 120 is slowly placed underground into the melt 50. Next, the suspension wire 120 slowly pulls up the seed crystal 60 while rotating, so that a cylinder-like twin rod 70 is formed under the seed crystal 60. In addition, the crystal growth apparatus 100 may further include a rotating shaft 190 that can support the crucible 130 and drive the crucible 130 to rotate. For example, when the suspension wire 120 is rotated in the counterclockwise direction and the seed crystal 60 is slowly pulled up, the crucible 130 is rotated in the clockwise direction by the rotation of the rotary shaft 190. In addition, as the twin rod 70 becomes longer and longer, the liquid level of the melt 50 will become lower and lower. At this time, the distance between the crucible 130 and the thermal curtain 150 can be adjusted to bring the two closer together, thereby maintaining the distance between the bottom of the thermal curtain 150 and the liquid surface of the melt 50, and maintaining the twin rod 70 at a preferred temperature. gradient.

The thermal curtain 150 of the present embodiment has an inner wall 152 and an outer wall 154. An inner space 156 is defined between the inner wall 152 and the outer wall 154. The inner wall 152 refers to a wall constituting the inner surface of the heat curtain 150 facing the suspension wire 120, and the outer wall 154 refers to a wall constituting the outer surface of the heat curtain 150 facing away from the suspension wire 120. The cooling element 160 is disposed in an interior space 156 between the inner wall 152 and the outer wall 154. Therefore, the cooling element 160 is substantially sealed between the inner wall 152 and the outer wall 154 and is isolated from the outside. Thereby, contamination of the melt 50 by the cooling element 160 can be avoided. Due to the cooling effect of the cooling element 160, the temperature of the crystallized rod 70 after leaving the melt 50 drops rapidly, that is, the temperature gradient on the twin rod 70 increases. Therefore, the time during which the twin rod 70 passes through the temperature range of 900 ° C to 1200 ° C is also shortened, thereby reducing the chance of OISF generation, thereby improving the quality of the twin rod 70. Moreover, after the temperature gradient is increased, the speed at which the twin rod 70 is formed can also be increased, which helps to shorten the process time and reduce the process cost.

In one embodiment of the invention, the side of the thermal curtain 150 adjacent the melt 50 is the bottom 150A, and the cooling element 160 is distributed from the bottom 150A of the thermal curtain 150 to the top 150B. In other words, the cooling element 160 is filled in the interior space 156 of the thermal curtain 150 from top to bottom. As such, the cooling element 160 can provide a better cooling effect to increase the temperature gradient and speed up the growth rate. The better the cooling capacity of the cooling element 160, the more pronounced the temperature gradient can be increased. The cooling member 160 of the present embodiment may be a metal tube equipped with a cooling liquid, for example, a copper tube equipped with cooling water, argon gas or helium gas, but the present invention is not limited thereto. Since the inner wall 152 isolates the cooling element 160 from the melt 50 from the outer wall 154, the choice of material for the cooling element 160 does not require consideration of whether the melt 50 will be contaminated.

In order to further enhance the cooling effect, the crystal growth apparatus 100 of the present embodiment may further include a heat insulating material 170 disposed in the inner space 156 between the inner wall 152 and the outer wall 154. The heat insulating material is, for example, carbon fiber, but the present invention is not limited thereto.

The material of the thermal curtain 150 of this embodiment is graphite or other suitable material. The material of the inner wall 152 and the outer wall 154 may be the same or different. The inner wall 152 and the outer wall 154 are, for example, detachably assembled. Therefore, when the cooling element 160 is placed, the inner wall 152 and the outer wall 154 can be first detached and then assembled. The interior space 156, for example, is isolated from the other spaces within the cavity 110 and is not in communication with each other, ensuring a cooling effect and avoiding contamination of the melt 50.

The crystal growth apparatus 100 of the present embodiment may further include a heat retention element 180 disposed in the cavity 110. The heating element 140 is positioned between the thermal insulation element 180 and the crucible 130 to maintain the temperature of the melt 50 and the heating effect caused by the heating element 140.

Applicant performed a simulation analysis of the crystal growth apparatus 100 having the cooling element 160 of the above embodiment and the crystal growth apparatus having no cooling element provided in the prior art. The process conditions of the simulated crystal growth apparatus 100 are: melt feed amount 60 kg, twin rod rotation speed 16 rpm, twin rod pull speed 60 mm/hr, helium rotation speed - 14 rpm, chamber internal pressure 60 torr, cooling element The flow rate of the argon gas passed was 40 slpm (Standard liters per minute), and the process conditions of the simulated conventional crystal growth apparatus were the same as those of the crystal growth apparatus 100 except that there was no cooling element. After the simulation under the above conditions, the average temperature gradient of the twin rod of the crystal growth apparatus 100 from the surface of the melt was 5.137 oK/mm, and the crystal growth rod of the conventional crystal growth apparatus was calculated from the surface of the molten soup. The average temperature gradient is 4.137 oK/mm. It can be seen that the temperature gradient achieved by the crystal growth device 100 having the cooling element 160 of the above embodiment is improved by 24% compared to the temperature gradient achieved by the conventional crystal growth apparatus, which is sufficient to prove that the crystal growth apparatus of the present invention is indeed Helps increase the temperature gradient of the ingot.

In summary, in the crystal growth apparatus of the present invention, the cooling element produces a cooling effect on the ingot to increase the temperature gradient of the ingot and reduce the probability of occurrence of the oxidation stack, which not only improves the quality of the ingot, but also improves the quality of the ingot. Improve output efficiency. In addition, since the cooling element is disposed in the inner space of the heat curtain, it is possible to prevent the cooling element from contaminating the molten material.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

50‧‧‧ molten soup
60‧‧‧ seed crystal
70‧‧‧矽晶棒
100‧‧‧ crystal growth device
110‧‧‧ cavity
120‧‧‧ hanging wire
130‧‧‧坩埚
140‧‧‧heating elements
150‧‧‧hot curtain
150A‧‧‧ bottom
150B‧‧‧ top
152‧‧‧ inner wall
154‧‧‧ outer wall
156‧‧‧Internal space
160‧‧‧Cooling element
170‧‧‧Insulation
180‧‧‧Insulation components
190‧‧‧Rotary axis

1 is a schematic cross-sectional view of a crystal growth apparatus in accordance with an embodiment of the present invention.

50‧‧‧ molten soup

60‧‧‧ seed crystal

70‧‧‧矽晶棒

100‧‧‧ crystal growth device

110‧‧‧ cavity

120‧‧‧ hanging wire

130‧‧‧坩埚

140‧‧‧heating elements

150‧‧‧hot curtain

150A‧‧‧ bottom

150B‧‧‧ top

152‧‧‧ inner wall

154‧‧‧ outer wall

156‧‧‧Internal space

160‧‧‧Cooling element

170‧‧‧Insulation

180‧‧‧Insulation components

190‧‧‧Rotary axis

Claims (8)

A crystal growth apparatus comprising: a cavity; a suspension wire disposed in the cavity, the seed crystal is pulled by the above; a crucible disposed in the cavity for accommodating a molten soup; a heating element, Disposed in the cavity and located at the periphery of the crucible for heating the molten material; a thermal curtain disposed in the cavity and above the crucible, wherein the thermal curtain has an inner wall and an outer wall, the inner An inner space is formed between the wall and the outer wall; and a cooling element disposed in the inner space between the inner wall and the outer wall. The crystal growth apparatus of claim 1, wherein the side of the hot curtain adjacent to the melt is a bottom portion, and the cooling element is distributed from the bottom of the heat curtain to the top. The crystal growth apparatus of claim 1, wherein the cooling element is a metal tube filled with a coolant. The crystal growth apparatus of claim 1, wherein the thermal curtain is made of graphite. The crystal growth apparatus of claim 1, wherein the inner wall and the outer wall are detachably assembled. The crystal growth device of claim 1, further comprising a heat insulating member disposed in the cavity, wherein the heating element is located between the heat insulating member and the crucible. The crystal growth device of claim 1, further comprising a heat insulating material disposed in the inner space between the inner wall and the outer wall. The crystal growth apparatus of claim 7, wherein the thermal insulation material is carbon fiber.