JPWO2020156213A5 - - Google Patents

Description

The present invention relates to the field of semiconductor manufacturing, and more particularly to semiconductor crystal growth equipment.

The CZ pulling method is an important method for producing silicon single crystals for semiconductor wafers and solar energy. A seed crystal is immersed in the melt, and a single crystal ingot is finally obtained through a series of steps (neck, shurda, bodi, tail, and cooling).

In the crystal pulling process, a reflector device such as an inflow tube (or a reflector ) is often provided around the silicon crystal ingot. This shields the crystal surface from heat radiation from the quartz crucible and the silicon melt in the crucible during crystal growth, increases the temperature gradient in the axial direction of the crystal ingot, and makes the temperature distribution in the radial direction as uniform as possible. This is to control the growth rate of the crystal ingot within an appropriate range and to suppress the internal defects of the crystal. In addition, by guiding the inert gas introduced from the upper part of the crystal growth furnace and allowing it to pass through the silicon melt surface at a higher flow velocity, the effect of controlling the oxygen content and impurity content in the silicon crystal ingot can be obtained. in order to obtain

In the process of designing a semiconductor crystal growth apparatus, it is necessary to consider the distance between the reflector apparatus and the silicon melt surface and the crystal ingot in order to control the temperature gradient in the axial direction and the temperature distribution in the radial direction of the crystal ingot. Specifically, in the process of designing the reflector device, the minimum distance between the reflector device and the liquid surface (hereinafter referred to as liquid level distance Drm) and the minimum distance between the reflector device and the crystal ingot (hereinafter referred to as crystal ingot distance Drc ), two important parameters are often considered. Here, Drm controls the stable growth of the silicon crystal between the crystal pulling liquid surface and Drc controls the temperature gradient in the axial direction of the silicon crystal ingot. In order to stably grow a silicon crystal between a silicon crystal ingot and a silicon melt surface, the crucible rising speed is often controlled so that Drm is stabilized within an appropriate range. For example, in Japanese Patent Application No. 2000-160405, a reflector device is provided around single crystal silicon to control the distance from the lower surface of the reflector device to the surface of the silicon melt and the pulling speed when pulling out the single crystal silicon. Thus, a semiconductor crystal growth method and apparatus for suppressing defects occurring inside single crystal silicon are disclosed. However, once the shape of the reflector device is fixed, the shape and position of the flow guide tube are fixed, and when the shape of the silicon crystal ingot is constant, the device itself can be controlled to further reduce Drc. Therefore, it is difficult to adjust the temperature gradient in the axial direction of the silicon crystal ingot.

Therefore, in order to solve the problems of the conventional technology, a new semiconductor crystal growth apparatus is proposed.

The Summary of the Invention section introduces a series of concepts in a simplified form that are explained in further detail in the Specific Embodiments section. The Summary of Invention column of the present invention is not intended to limit the main features or essential technical features of the claimed technical solution, much less the claimed technical solution. Nor does it attempt to determine the scope of protection of

The present invention provides a semiconductor crystal growth apparatus, the apparatus comprising:
a furnace body;
a crucible that is provided inside the furnace body and holds a silicon melt;
Provided on the upper part of the furnace body, comprising a device for pulling up a silicon crystal ingot from the silicon melt and a reflector device,
The reflector device is provided with an inflow tube, the inflow tube having a cylindrical shape, and being provided around the silicon crystal ingot to rectify the argon gas introduced from the upper part of the furnace body, and The reflector device is for adjusting the heat distribution between the silicon melt surface and the silicon crystal ingot. It further comprises an adjustment device for adjusting the minimum distance between.

Illustratively, the adjusting device comprises an annular device surrounding the inner side of the inflow tube.

Illustratively, the annular device is constructed by joining at least two arcuate members.

Illustratively, the adjustment device is detachably connected to the inflow tube .

Illustratively, the inflow tube includes an inner tube, an outer tube, and a heat insulating material, and the bottom of the outer tube extends downward from the bottom of the inner tube and closes with the bottom of the inner tube, thereby A cavity is formed between the inner cylinder and the outer cylinder, and the heat insulating material is provided in the cavity.

Illustratively, the adjustment device includes an insertion portion and a projection portion, and the insertion portion includes a portion of the bottom portion of the outer cylinder that extends below the bottom portion of the inner cylinder and the inner cylinder. It is inserted between the bottom of the cylinder.

Illustratively, the adjustment device is an inverted L-shaped cross-section or a T-shaped rotated 90° counterclockwise.

Exemplarily, the protruding portion has an inverted triangle shape or a shape protruding toward the silicon crystal.

Illustratively, the protrusion extends downward beyond the bottom of the inflow tube .

Illustratively, the shape of the protrusion extending downwardly beyond the bottom of the inflow tube comprises an inwardly concave curved surface or an outwardly convex curved surface.

Illustratively, the material of the conditioning device comprises a material with low thermal conductivity.

Illustratively, the material of the conditioning device comprises monocrystalline silicon, graphite, quartz, refractory metals, or combinations of said materials.

Illustratively, the protrusion has a layer with a low thermal radiation coefficient on the side facing the silicon crystal ingot to further modify the radiant heat transfer between the conditioning device and the silicon crystal ingot surface.

According to the semiconductor crystal growth apparatus according to the present invention, in the design of the reflector device, by providing the adjustment device inside the lower end of the inflow tube , the reflector device and the crystal ingot can be aligned without changing the shape and position of the inflow tube . The minimum distance can be reduced and the axial temperature gradient of the silicon crystal ingot can be increased to improve the crystal growth rate. At the same time, the difference in temperature gradient in the axial direction between the central portion and the edge portion of the crystal ingot can be reduced, enabling defect control inside the crystal. In addition, the adjustment device is controlled by the gas flow rate of argon gas flowing into the silicon melt surface through the inflow pipe and the minimum distance Drc between the reflector device and the crystal ingot. , the oxygen content of the melt can be controlled by changing the flow rate of the gas that develops radially from the silicon melt surface, and the quality of the pulled crystal can be further improved.

The following accompanying drawings of the present invention are used herein as part of the present invention for the understanding of the present invention. For the purpose of explaining the principles of the invention, embodiments of the invention and descriptions thereof are illustrated in the accompanying drawings.

In the attached drawing:
FIG. 1 is a schematic configuration diagram of a semiconductor crystal growth apparatus according to one embodiment of the present invention. FIG. 2 is a schematic configuration diagram of an adjustment device attached to an inflow tube according to one embodiment of the present invention. FIG. 3A is a schematic configuration diagram of an adjustment device according to one embodiment of the present invention. FIG. 3B is a schematic configuration diagram of an adjustment device according to one embodiment of the present invention. FIG. 3C is a schematic configuration diagram of an adjustment device according to one embodiment of the present invention.

In the following description, numerous specifics are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the invention can be practiced without one or more of these details. In other instances, some technical features well known in the art are not described to avoid confusion with the present invention.

For a thorough understanding of the present invention, the following detailed description will be made with reference to the semiconductor crystal growth apparatus described herein as an example. Naturally, the invention is not limited in its implementation to specific details familiar to those skilled in the semiconductor art. Although preferred embodiments of the present invention are described in detail below, the present invention can have other embodiments in addition to these detailed descriptions.

It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present invention. . In this specification, singular forms are also intended to include plural forms unless the context clearly dictates otherwise. Further, when the terms “comprise” and/or “include” are used herein, these terms refer to the existence of said features, wholes, steps, operations, parts, assemblies and/or combinations thereof. , does not exclude the presence or addition of one or more other features, elements, steps, operations, parts, assemblies or combinations thereof.

Exemplary embodiments according to the invention will now be described in more detail with reference to the accompanying drawings. These example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is to be understood that these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the ideas of these exemplary embodiments to those skilled in the art. In the attached drawings, the thickness of layers and regions are exaggerated for clarity, and like components are indicated using the same attached labels and their descriptions are omitted.

In order to solve the technical problems of the prior art, the present invention provides a semiconductor crystal growth apparatus, the apparatus comprising:
a furnace body;
a crucible that is provided inside the furnace body and holds a silicon melt;
Provided on the upper part of the furnace body, comprising a device for pulling up a silicon crystal ingot from the silicon melt and a reflector device,
The reflector device is provided with an inflow tube, the inflow tube having a cylindrical shape, and being provided around the silicon crystal ingot to rectify the argon gas introduced from the upper part of the furnace body, and The reflector is provided inside the lower end portion of the inflow cylinder , and the reflector is provided between the reflector device and the silicon crystal ingot. It further comprises an adjusting device for adjusting the minimum distance.

An exemplary description of the semiconductor crystal growth apparatus proposed by the present invention is given below with reference to FIGS. 1 and 2. FIG. FIG. 1 is a schematic configuration diagram of a semiconductor crystal growth apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of an adjusting device attached to an inflow cylinder according to an embodiment of the present invention. 3A to 3C are schematic configuration diagrams of the adjustment device , respectively.

The pulling method (Cz) is an important method for producing silicon single crystals for semiconductor wafers and solar energy. In this method, a seed crystal is immersed in a molten liquid, and a single crystal ingot is finally obtained through a series of steps (neck, shurda, bodi, tail, and cooling).

A semiconductor crystal growth apparatus according to one embodiment of the present invention will be described with reference to FIG. A semiconductor crystal growth apparatus includes a furnace body 1 provided with a crucible 11 , a heater 12 for heating the crucible 11 is provided outside the crucible 11 , and a silicon melt 13 is accommodated in the crucible 11 .

A pulling device 14 is provided in the upper part of the furnace body 1, and the silicon crystal ingot 10 is pulled up from the surface of the silicon melt by the pulling device 14, and a reflector device is provided around the silicon crystal ingot 10. there is Illustratively, as shown in FIG. 1, the reflector device comprises a conical inlet tube 16 . The reflector device blocks heat radiation generated against the crystal surface by the quartz crucible and the silicon melt in the crucible during the crystal growth process, thereby increasing the cooling rate of the crystal ingot and the temperature gradient in the axial direction, increasing the growth rate. At the same time, while affecting the heat distribution on the surface of the crystal ingot, it is devised so as not to cause an excessive difference in the temperature gradient in the axial direction between the center and the edge of the crystal ingot. control the inner distribution. In addition, the inflow tube guides the inert gas introduced from the upper part of the crystal growth furnace to pass through the surface of the silicon melt at a higher flow rate, thereby controlling the amount of oxygen and the content of impurities in the crystal. You get the effect. Referring to FIG. 1, the minimum distance between the bottom surface of the inflow pipe 16 and the liquid surface of the silicon melt 13 is used as the minimum distance between the reflector device and the silicon melt, which is called the liquid surface distance, Drm, the minimum distance between the position of the inflow tube 16 closest to the silicon crystal ingot 10 and the silicon crystal ingot is used as the minimum distance between the reflector device and the silicon crystal ingot, and is referred to as the crystal ingot distance. , Drc.

In order to stably grow a silicon crystal ingot, a driving device 15 for rotating and vertically moving the crucible 11 is provided at the bottom of the furnace body 1 . The driving device 15 drives the crucible 11 to keep rotating during the crystal pulling process in order to reduce the thermal asymmetry of the silicon melt and grow the silicon crystal column isotropically . In addition, the driving device 15 controls the liquid surface distance Drm to an appropriate range to stabilize heat radiation from the silicon melt surface to the crystal ingot, thereby satisfying the condition of stable growth of the silicon crystal ingot. Next, drive the crucible up and down . Illustratively, the drive unit 15 drives the crucible up and down to control the liquid level distance Drm between 20 mm and 80 mm.

However, when the reflector device is fixed, the shape and position of the inflow cylinder are fixed, and when the shape of the silicon crystal ingot is constant, the device itself is controlled to further reduce Drc. Therefore, it is difficult to increase the temperature gradient in the axial direction of the silicon crystal ingot.

For this reason, referring to FIG. 2, in the semiconductor crystal growth apparatus of the present invention, an adjustment device 17 is provided at the lower end of the inflow tube 16. Together, they regulate the heat distribution between the silicon melt surface and the crystal ingot. Specifically, by providing an adjustment device inside the lower end of the inflow tube , the reflector device and silicon can be adjusted without adjusting the size and position of the inflow tube , compared to the case where no adjustment device is provided. By changing the minimum distance Drc between the crystal ingot from the initial minimum distance between the inflow tube and the silicon crystal ingot to the minimum distance between the conditioning device and the silicon crystal ingot, the reflector device and the silicon The minimum distance Drc to the crystal ingot can be reduced. The reflector device readjusts the radiant energy between the silicon crystal ingot and the reflector device, and between the reflector device and the silicon melt surface, thereby adjusting the intensity and distribution of the heat flux on the crystal surface, and The axial temperature gradient between the center and the edge of the crystal ingot is increased, effectively improving the crystal growth rate, and the axial temperature gradient between the center and the edge of the silicon crystal ingot. , the crystal is stably grown on the silicon melt surface. In addition, the adjustment device further reduces the cross-sectional area of the flow path through which the argon gas flows to the silicon melt surface through the inflow cylinder , thereby increasing the flow rate of the argon gas radially expanding from the silicon melt surface. and adjust the oxygen content of the growing crystal to further improve the quality of the crystal being pulled.

Furthermore, when setting the adjusting device , the minimum distance Drc between the reflector device and the silicon crystal ingot should be reduced to reduce the transmission of radiant heat from the silicon melt to the crystal ingot, and the axial direction of the crystal ingot should be reduced. By increasing the temperature gradient, the crystal growth rate can be improved, and at the same time, the power consumption of the heater for crystal growth can be reduced. If an adjustment device is provided between the inflow tube and the crystal ingot, the transfer of radiant heat from the inflow tube to the crystal ingot can be reduced, thereby reducing the axial temperature gradient between the center and edge of the crystal ingot. can be reduced to widen the crystal growth process window (appropriate permissible range of pulling speed) and improve the product yield.

The inflow tube is provided in a cylindrical shape around the silicon crystal ingot, and exemplarily, the adjusting device 17 is provided as an annular device surrounding the inside of the inflow tube .

Exemplarily, the adjustment device and the inflow tube are detachably connected.

Further illustratively, the annular device comprises at least two spliced arcuate members. Since the crystal pulling process is in a high temperature environment, in order to prevent the adjustment device from expanding in a high temperature environment and becoming unstable in the installation with the inflow cylinder , the annular adjustment device is made into a multi-stage arc. , by providing a gap between the multi-stage arcs, it is possible to effectively avoid the problem that the adjustment device is expanded and the mounting of the inflow pipe becomes unstable, and at the same time, the annular adjustment device is made into a multi-stage arc. This further simplifies the work of attaching the adjustment device to the inflow tube .

With continued reference to FIG. 2, in accordance with one embodiment of the present invention, inlet tube 16 includes an inner tube 161, an outer tube 162, and insulation 163 disposed between inner tube 161 and outer tube 162. , the bottom of the outer cylinder 162 extends below the bottom of the inner cylinder 161 and is connected with the bottom of the inner cylinder 161 to form a cavity between the inner cylinder 161 and the outer cylinder 162 to accommodate the heat insulating material 163 do. By configuring the inflow tube to include an inner tube, an outer tube, and a heat insulating material, installation of the inflow tube can be facilitated. Illustratively, the material of the inner and outer cylinders is graphite, and the heat insulating material includes porous materials such as carbon fiber, asbestos, rock wool, silicate, airgel mat, and vacuum board.

Continuing to refer to FIG. 2, in a configuration in which the inflow tube 16 is set to include an inner tube 161, an outer tube 162, and a heat insulating material 163 set between the inner tube 161 and the outer tube 162, , the adjusting device 17 includes a projecting portion 171 and an inserting portion 172. The inserting portion 172 is formed by a portion of the bottom portion of the outer cylinder 162 extending downward from the bottom portion of the inner cylinder 161 and a bottom portion of the inner cylinder 161. is inserted between Since the adjustment device is attached to the inflow tube by inserting it, the adjustment device can be installed without modifying the inflow tube , and the manufacturing and installation costs of the adjustment device and the inflow tube can be further simplified. . In addition, the insertion part is inserted between the bottom of the outer cylinder and the bottom of the inner cylinder, which effectively reduces the heat transfer from the outer cylinder to the inner cylinder, lowers the temperature of the inner cylinder, and disperses the crystal from the inner cylinder. It can further reduce the transfer of radiant heat to the ingot, effectively reduce the difference in axial temperature gradient between the center and the edge of the silicon crystal ingot, and improve the quality of the pulled crystal.

Illustratively, the conditioning device is constructed of a low thermal conductivity material. Further, exemplary said low thermal conductivity materials include materials having a thermal conductivity of less than 5-10 W/(m*K). By way of example, the material of the adjustment device may be SiC, quartz, monocrystalline silicon, carbon fiber, quartz, refractory metals, or a combination of said materials.

In this embodiment, the adjustment device is detachably attached to the inflow tube , which on the one hand realizes the attachment and separate manufacture of both, simplifies the manufacturing process and reduces the manufacturing cost. On the other hand, it makes it possible to replace the regulating device separately and to process and use the regulating device as a consumable, so that the regulating device forms a series of products and processes This is to shorten the development cycle and reduce development costs. It should be understood by those skilled in the art that the present invention can also be applied when the adjustment device is integrally manufactured with the inner cylinder of the inflow cylinder .

Illustratively, the cross-section of the adjusting device has an inverted L shape or a T shape rotated 90° counterclockwise. With continued reference to FIG. 2 , the adjustment device 17 has a T-shaped cross-section rotated 90° counterclockwise, with an insert 172 extending below the bottom surface of the inner cylinder 161 . and the bottom surface of the inner cylinder 161, and the projection 171 has an inverted triangular shape, thereby reducing the minimum distance between the crystal ingot and the reflector device.

It should be noted that the inverted triangular shape of the protruding portion is an example, and any shape may be used as long as it protrudes toward the side surface of the silicon crystal ingot. It should be understood that any shape that reduces the minimum distance of is applicable to the present invention.

3A-3C, it is shown that the protrusion 171 is shaped to protrude toward the crystal ingot. As shown in FIGS. 3A-3C, protrusion 171 extends downward beyond the bottom of the inflow tube , as indicated by arrow P. As shown in FIG. As shown in FIG. 2, the protrusions extend downward beyond the bottom surface of the inlet tube to reduce the minimum distance Drm between the reflector device and the silicon melt surface to By changing the minimum distance between the bottom surface of the inflow tube and the silicon melt surface to the minimum distance between the lower end of the protrusion of the adjusting device and the silicon melt surface, the distance between the reflector device and the silicon melt surface is By reducing the minimum distance Drm between the silicon crystals and thereby adjusting the gas flow rate of the argon gas flowing in the inflow cylinder toward the silicon melt surface and expanding in the radial direction from the silicon melt surface, the outer periphery of the silicon crystal By controlling the oxygen concentration in the silicon melt in the vicinity, the oxygen content in the crystal can be adjusted, and the quality of the pulled crystal can be further improved.

Exemplarily, the shape of the downward extension beyond the bottom of the inflow tube of the protrusion 171 includes an inwardly concave curved surface (shown in FIG. 3B) or an outwardly convex curved surface (shown in FIG. 3C). . By making the shape of the downwardly extending portion of the protrusion beyond the bottom of the inflow cylinder an inwardly concave curved surface or an outwardly convex curved surface, the relative shape of the adjustment device and the silicon melt surface allows the Further adjust the transfer of radiant heat between the surface of the crystal ingot, the silicon melt surface and the adjustment device , and adjust the fluctuation of the heat flux emitted from the crystal to the outside along the axial direction of the crystal surface. By reducing the difference in temperature gradient in the axial direction between the central portion and the edge portion, the effect of making the interface between the crystal and the melt more flat can be obtained.

Illustratively, the protrusion comprises a layer of low thermal radiation coefficient (high reflection coefficient) on the side facing the silicon crystal ingot, which reduces the transfer of radiant heat between the inflow tube and the surface of the silicon crystal ingot. further decreasing. The heat radiation coefficient e ranges from 0 to 1 (reflection coefficient p=1-e). Illustratively, the thermal radiation coefficient of said low radiation coefficient material is e<0.5. In one example, the protrusion is made of polished stainless steel, and the polished stainless steel surface has a heat radiation coefficient e=0.2-0.3.

Exemplarily, the material of the adjustment device is graphite, and the surface of the graphite is surface-treated to form a SiC coating and/or a pyrolytic carbon coating with a coating thickness of 10 μm to 100 μm. Here, the pyrolytic carbon coating has a high surface density and a high heat reflectance at high temperatures, and the surface treatment includes a chemical vapor deposition method or the like.

Exemplarily, the shape and surface of the protrusion of the adjusting device are coated to form a layer of high reflectance (low thermal emissivity) on the surface, and the surface of the silicon crystal ingot, the liquid level and the adjusting device By changing the radiant heat transfer between the By reducing the difference, the shape of the interface between the crystal and the melt is flattened, and the difference in the radial direction of the crystal is reduced.

The semiconductor crystal growth apparatus according to the present invention has been exemplified above, but the limitations on the shape, mounting method, material, etc. of the adjustment device in the semiconductor crystal growth apparatus of the present embodiment are merely examples, and the crystal ingot and the reflector device are not limited. It should be understood that any regulating device that allows a small minimum distance between is applicable to the present invention.

INDUSTRIAL APPLICABILITY As described above, the semiconductor crystal growth apparatus according to the present invention is provided with the adjusting device inside the lower end portion of the inflow tube , so that the reflector device and the crystal ingot can be minimized without changing the shape and position of the inflow tube . By shortening the distance and increasing the axial temperature gradient of the silicon crystal ingot, the crystal growth rate can be adjusted. Stable crystal growth becomes easier. At the same time, the adjustment device reduces the passage size of the argon gas flowing from the inlet tube to the silicon melt surface by the minimum distance between the reflector device and the crystal ingot, and the silicon melt surface from the inlet tube to the silicon melt surface. By changing the flow rate of the argon gas that spreads radially from the melt surface, the oxygen concentration inside the silicon melt near the outer periphery of the silicon crystal is controlled, the oxygen content in the crystal is adjusted, and the quality of the crystal that is pulled is controlled. It can be improved further.

While the present invention has been described by the above-described embodiments, the above-described embodiments are used for purposes of illustration and description only and are not intended to limit the scope of the invention to the described embodiments. should be understood. Moreover, the present invention is not limited to the above-described embodiments, and many more variations and modifications are possible in accordance with the teachings of the present invention, all of which fall within the scope of protection claimed by the present invention. It will be understood by those skilled in the art. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (13)

A semiconductor crystal growth apparatus,
a furnace body;
a crucible that is provided inside the furnace body and holds a silicon melt;
a device provided on the upper part of the furnace body for pulling up a silicon crystal ingot from the silicon melt;
a reflector device;
with
The reflector device is provided with an inflow cylinder, the inflow cylinder having a cylindrical shape, and being provided around the silicon crystal ingot to rectify the argon gas introduced from the upper part of the furnace body, and The reflector device is for adjusting the heat distribution between the silicon melt surface and the reflector device. further comprising an adjustment device for adjusting the distance,
The adjustment device comprises an insertion portion and a protrusion, and the insertion portion is inserted into the inflow tube.
Semiconductor crystal growth equipment. 2. The semiconductor crystal growth apparatus according to claim 1, wherein said adjusting device comprises an annular device surrounding said inflow tube. 3. The semiconductor crystal growth apparatus according to claim 2, wherein said annular device is constructed by joining at least two arcuate members. 2. The semiconductor crystal growth apparatus according to claim 1, wherein said adjusting device is detachably connected to said inflow cylinder . The inflow cylinder includes an inner cylinder, an outer cylinder, and a heat insulating material, and the bottom of the outer cylinder extends downward from the bottom of the inner cylinder, and closes with the bottom of the inner cylinder to form the inner cylinder and the heat insulator. 2. The semiconductor crystal growth apparatus according to claim 1, wherein a cavity is formed between said outer cylinder and said heat insulating material is provided in said cavity. 6. The semiconductor according to claim 5, wherein said insertion portion is inserted between said bottom portion of said inner cylinder and a portion of said bottom portion of said outer cylinder that extends below said bottom portion of said inner cylinder. Crystal growth equipment. 7. The semiconductor crystal growth apparatus according to claim 6, wherein said adjusting device has an inverted L-shaped cross section or a T-shaped cross section rotated counterclockwise by 90 degrees. 7. The semiconductor crystal growth apparatus according to claim 6, wherein said projecting portion has an inverted triangle shape or a shape projecting toward said silicon crystal. 9. The semiconductor crystal growth apparatus according to claim 8, wherein said projecting portion extends downward beyond the bottom of said inflow tube . 9. The semiconductor crystal growth apparatus according to claim 8, wherein the shape of said protrusion extending downward beyond the bottom of said inflow tube comprises an inward concave curved surface or an outward convex curved surface. 2. The semiconductor crystal growth apparatus of claim 1, wherein the material of said conditioning device comprises a low thermal conductivity material. 12. The semiconductor crystal growth apparatus of claim 11 , wherein the conditioning device material comprises monocrystalline silicon, graphite, quartz, refractory metals, or a combination of said materials. 10. The method of claim 9, wherein the protrusion has a layer with a low thermal radiation coefficient on the side facing the silicon crystal ingot to further modify radiant heat transfer between the conditioning device and the silicon crystal ingot surface. The semiconductor crystal growth apparatus described.