WO2012144872A2

WO2012144872A2 - Apparatus and method for fabricating ingot

Info

Publication number: WO2012144872A2
Application number: PCT/KR2012/003117
Authority: WO
Inventors: Bum Sup Kim; Chang Hyun Son
Original assignee: Lg Innotek Co., Ltd.
Priority date: 2011-04-21
Filing date: 2012-04-23
Publication date: 2012-10-26
Also published as: WO2012144872A3

Abstract

Disclosed are an apparatus and a method for fabricating an ingot. The apparatus for fabricating an ingot includes a crucible receiving a raw material, a holder fixing a seed provided on the raw material, and an adhesive layer interposed between the holder and the seed while adhering to the seed. The adhesive layer includes a main adhesive layer adhering to the seed, and adhesion enhancing particles dispersed in the main adhesive layer. Meanwhile, the apparatus for fabricating an ingot includes a crucible receiving a raw material, and a seed holder fixing a seed on the raw material, in which a buffer layer is formed on the seed holder.

Description

APPARATUS AND METHOD FOR FABRICATING INGOT

The embodiment relates to an apparatus and a method for fabricating an ingot.

In general, materials are very important factors to determine the property and the performance of final products in the electric, electronic and mechanical industrial fields.

Among the materials, SiC represents the superior thermal stability and superior oxidation-resistance property. In addition, the SiC has the superior thermal conductivity of about 4.6W/Cm℃, so the SiC can be used for fabricating a large-size substrate having a diameter of about 2 inches or above. In particular, the single crystal growth technology for the SiC is very stable in the art, so the SiC has been extensively used in the industrial field as a material for a substrate.

The SiC single crystal is manufactured through a seeded growth sublimation scheme.

According to the seeded growth sublimation scheme, a raw material is received in a crucible, and a SiC single crystal serving as a seed, is provided on the raw material. Temperature gradient is formed between the raw material and the seed, so that the raw material is dispersed to the seed, and recrystallized to grow a single crystal.

In order to perform the process, a seed used to grow the single crystal is attached to an additional member such as a cover of a crucible. Since quality of the single crystal grown on the surface of the seed may be greatly affected by the attachment state of the seed, the attachment process of the seed is very important. In addition, if the surface of the seed used to grow the single crystal is fixed in the direction of gravity due to the arrangement structure of the seed, the seed may be dropped due to the weight and the attachment state of the seed.

Therefore, before the process of growing the single crystal is performed, the seed and the seed holder to which the seed is attached must be stably and firmly attached.

The embodiment provides an apparatus and a method for fabricating an ingot, capable of growing a single crystal having high quality.

According to the embodiment, there is provided an apparatus for fabricating an ingot, which includes a crucible receiving a raw material, a holder fixing a seed provided on the raw material, and an adhesive layer interposed between the holder and the seed while adhering to the seed. The adhesive layer includes a main adhesive layer adhering to the seed, and adhesion enhancing particles dispersed in the main adhesive layer.

According to the embodiment, there is provided a method for fabricating an ingot, which includes forming a preliminary adhesive layer, which is obtained by mixing a main adhesive layer and adhesion enhancing particles, between a holder and a seed, forming an adhesive layer attached to the seed by drying the preliminary adhesive layer, and growing a silicon carbide crystal on the seed by using a raw material including silicon (Si) and carbon (C).

Meanwhile, according to the embodiment, there is provided an apparatus for fabricating an ingot, which includes a crucible receiving a raw material, and a seed holder fixing a seed on the raw material. A buffer layer is formed on the seed holder.

As described above, the apparatus for fabricating the ingot according to the embodiment includes an adhesive layer coupled with the seed, and the adhesive layer includes the main adhesive layer and the adhesion enhancing particles. The main adhesive layer may include photoresist including the mixture of polymer resin and a photosensitive material. Therefore, the main adhesive layer may have liquidity.

Therefore, the adhesive layer can be easily handled, and the uniform layer can be formed.

In addition, the adhesion enhancing particles can enhance the main adhesive layer. In other words, the adhesion enhancing particles can increase the coupling strength with the main adhesive layer. Accordingly, the seed may be firmly attached to the holder. Therefore, in the process of growing an ingot on the seed, the ingot can be prevented from being delaminated from the holder.

In addition, the adhesion enhancing particles may be changed into SiC when the ingot is grown. Accordingly, pores can be prevented from being made in the rear surface of the seed. In addition, the adhesion enhancing particles are introduced into the defective portion existing in the seed, so that the defects of the seed can be prevented.

In addition, when the ingot is grown, the adhesion enhancing particles are changed into SiC so that the SiC membrane can be formed. In other words, the adhesive layer includes the SiC membrane, so that the adhesive layer may have a thermal expansion coefficient substantially approximating the thermal expansion coefficient of the seed. Therefore, defects caused by the difference in the thermal expansion coefficient between the seed holder and the seed can be minimized. In addition, during the process of growing the single crystal, the seed can be prevented from being delaminated due to the thermal expansion coefficient difference.

According to the method for fabricating the ingot of the embodiment, the ingot having improved quality can be provided.

Meanwhile, the apparatus for fabricating the ingot according to another embodiment includes the buffer layer formed on the seed holder.

The buffer layer may include a material having a thermal expansion coefficient the same as that of the seed to be grown. Therefore, the defects caused by the difference in the thermal expansion coefficient between the seed holder and the seed can be minimized. In addition, during the process of growing the single crystal, the seed can be prevented from being delaminated due to the thermal expansion coefficient difference.

The SiC_1-X layer is formed on the interfacial surface between the buffer layer and the seed during the high-temperature process of growing the single crystal, thereby preventing the lattice mismatch between the buffer layer and the seed. Accordingly, the attachment strength of the seed can be improved.

Therefore, the buffer layer can include at least one a grain boundary. The grain boundary can effectively distribute stress generated when the seed is grown. Therefore, the high-quality single crystal having less defects and a large area can be provided. In addition, when the large-area single crystal is grown, the stability and the recovery rate can be improved.

FIG. 1 is a sectional view showing an apparatus for fabricating an ingot according to a first embodiment;

FIG. 2 is a sectional view showing a seed, a holder, and an adhesive layer constituting the apparatus for fabricating the ingot according to the embodiment;

FIGS. 3 to 7 are sectional views showing a process of coupling a seed with a holder;

FIG. 8 is a view showing a process of forming the ingot;

FIG. 9 is a sectional view showing the apparatus for fabricating an ingot according to a second embodiment;

FIG. 10 is an enlarged view showing a part A of FIG 9;

FIG. 11 is a sectional view showing a seed holder and a buffer layer constituting the apparatus for fabricating the ingot according to the second embodiment; and

FIGS. 12 to 14 are sectional views showing processes of forming a seed holder constituting the apparatus for fabricating the ingot according to the second embodiment.

In the description of the embodiments, it will be understood that, when a layer (or film), a region, a pattern, or a structure is referred to as being "on" or "under" another substrate, another layer (or film), another region, another pad, or another pattern, it can be "directly" or "indirectly" on the other substrate, layer (or film), region, pad, or pattern, or one or more intervening layers may also be present. Such a position of the layer has been described with reference to the drawings.

The thickness and size of each layer shown in the drawings may be exaggerated, omitted or schematically drawn for the purpose of convenience or clarity. In addition, the size of elements does not utterly reflect an actual size.

Hereinafter, the embodiment will be described in detail with reference to accompanying drawings.

Hereinafter, an apparatus 10 for fabricating an ingot according to a first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a sectional view showing the apparatus 10 for fabricating the ingot according to the first embodiment, and FIG. 2 is a sectional view showing a seed, a holder, and an adhesive layer constituting the apparatus for fabricating the ingot according to the first embodiment.

Referring to FIGS. 1 and 2, the apparatus 10 for fabricating the ingot according to the first embodiment includes a crucible 100, an upper cover 140, a seed holder 170, an adhesive layer 160, a focusing tub 180, an adiabatic material 200, a quart tube 400, and a heating induction part 500.

The crucible 100 can receive a raw material 130. The raw material 130 may include silicon and carbon. In more detail, the raw material 130 may include silicon carbide (SiC) compound. The crucible 100 may receive SiC powders or polycarbosilane.

The crucible 100 may have a cylindrical shape to receive the raw material 130.

A melting point of a material constituting the crucible 100 is higher than a sublimation temperature of SiC. For example, the crucible 100 may include graphite.

In addition, the crucible 100 may include graphite coated with a material having a melting point higher than the sublimation temperature of SiC. In this case, preferably, the material coated on the graphite includes a material chemically representing an inactive property with respect silicon and hydrogen at a temperature in which SiC single crystal is grown. For example, the material may include metallic carbide or metallic nitride. In particular, the mixture including at least two selected from the group consisting of Ta, Hf, Nb, Zr, W and V and a carbide including carbon may be coated on graphite. In addition, the mixture including at least two selected from the group consisting of Ta, Hf, Nb, Zr, W and V, and a nitride including nitrogen may be coated on graphite.

The upper cover 140 may be placed on the crucible 100. The upper cover 140 may seal the crucible 100. The upper cover 140 may seal the crucible 100 so that chemical reaction occurs in the crucible 100.

The upper cover 140 may include graphite. However, the embodiment is not limited thereto. The upper cover 140 may include a material having a melting point equal to or higher than the sublimation temperature of SiC.

The seed holder 170 is placed on a lower end portion of the upper cover 140. The seed holder 170 may be fixed to a lower portion of the upper cover 140. The seed holder 170 may be detachably fixed to the upper cover 140. In addition, the seed holder 170 is provided on the raw material 130.

The seed holder 170 may fix a seed 190 thereto. In addition, the seed holder 170 supports the seed 190. The seed 190 is provided under the seed holder 170.

The seed 190 includes SiC. In more detail, the seed 190 includes a single crystal silicon carbide. The seed 190 has a circular plate shape.

The seed holder 170 may include high-concentration graphite. The seed holder 170 may include a bottom surface provided in opposition to the top surface of the seed 190. In this case, the seed holder 170 has a flat bottom surface.

The adhesive layer 160 may be formed on the seed holder 170. In detail, the adhesive layer 160 is interposed between the seed holder 170 and the seed 190. The adhesive layer 160 adheres to the seed holder 170. The adhesive layer 160 adheres to the bottom surface of the seed 190.

In addition, the adhesive layer 160 includes a main adhesive layer 160b and adhesion enhancing particles 160a.

The main adhesive layer 160b may include resin. In detail, the main adhesive layer 160b may include polymer resin. In more detail, the main adhesive layer 160b may include photoresist obtained by mixing polymer resin and a photosensitive material. Therefore, the main adhesive layer 160b may have liquidity. Therefore, a work of handling the adhesive layer 160 can be easily performed, and the uniform film may be formed.

The adhesion enhancing particles 160a may include carbon (C), silicon (Si), and silicon carbide (SiC).

The adhesion enhancing particles 160a may enhance the main adhesive layer 160b. In other words, the adhesion enhancing particles 160a may increase the bonding strength of the main adhesive layer 160b.

In addition, the adhesion enhancing particles 160a may be changed into SiC when the ingot is grown. Therefore, pores can be prevented from being made in the rear surface of the seed 190. Further, the adhesion enhancing particles 160a are introduced into defective portions existing in the seed 190, thereby minimizing the defects of the seed 190 that may be produced during the growing of the ingot.

In addition, when the ingot is grown, the adhesion enhancing particles 160a are changed into SiC to form a SiC membrane. In other words, since the adhesion layer 160 includes the SiC membrane, the adhesion layer 160 may have a thermal expansion coefficient similar to that of the seed 190. Therefore, the defects caused by the difference in the thermal expansion coefficient between the seed holder 170 and the seed 190 can be minimized. In addition, the seed 190 can be prevented from being delaminated during a single crystal growing process due to the thermal expansion coefficient difference.

Referring to FIG. 2, an adhesive layer constituting the apparatus for fabricating the ingot according to the embodiment includes the main adhesive layer 160b and the adhesion enhancing particles 160a, and the adhesion enhancing particles 160a may be contained in the main adhesive layer 160b. In detail, the adhesion enhancing particles 160a may be dispersed in the main adhesive layer 160b. The adhesion enhancing particles 160a may be uniformly dispersed in the main adhesive layer 160b.

In this case, 10 weight% to 30 weight% of adhesion enhancing particles 160a may be contained. Accordingly, the adhesive layer 160 may be uniformly coated. The contents of the adhesion enhancing particles 160a may be varied depending on the size or the strength of the particles contained in the main adhesive layer 160b.

Each of the adhesion enhancing particles 160a has a size of 10㎛ or less.

The adhesive layer 160 may have a thickness of 100㎛ to 500㎛. In detail, the adhesive layer 160 has the above thickness if the size of each adhesion enhancing particles 160a is 10㎛ or less. Therefore, the thickness of the adhesive layer 160 may be varied according to the sizes of the adhesion enhancing particle 160a.

Subsequently, the focusing tube 180 is provided in the crucible 100. The focusing tube 180 may be placed in a region in which a single crystal is grown. The focusing tube 180 narrows the flow passage of sublimated SiC gas, so that the dispersion of the sublimated SiC is concentrated on the seed 190. Therefore, the growing rate of the single crystal can be enhanced.

The adiabatic material 200 surrounds the crucible 100. The adiabatic material 200 maintains the temperature of the crucible 100 to the crystal growth temperature. The adiabatic material 200 may include a graphite felt because the crystal growth temperature of SiC is very high. In detail, the adiabatic material 200 may include graphite felt manufactured in a cylindrical shape having a predetermined thickness by compressing graphite fiber. In addition, the adiabatic material 200 includes a plurality of layers to surround the crucible 100.

The quart tube 400 is placed at an outer peripheral surface of the crucible 100. The quart tube 400 is fitted around the outer peripheral surface of the crucible 100. The quart tube 400 may block heat transferred into a single crystal growth device from the heating induction part 500. The quart tube 400 is a hollow tube, and cooling water may circulate through the inner space of the quart tube 400. Accordingly, the quart tube 400 may more precisely control the growth rate and the growth size of a single crystal.

The heating induction part 500 is placed at the outside of the crucible 100. The heat induction part 500 may include a high-frequency induction coil. The crucible 100 can be heated by allowing a high-frequency current to flow through the high-frequency induction coil. In other words, the raw material received in the crucible 100 can be heated to a desirable temperature.

A central region of the heating induction part 500, which is induction-heated, is formed lower than the central portion of the crucible 100. Therefore, a temperature gradient may be formed along the upper and lower portions of the crucible 100, that is, the upper and lower portions of the crucible 100 have temperatures different from each other. A hot zone (HZ), which is a central portion of the heating induction part 500, is located lower than the central portion of the crucible 100, so that the temperature of the lower portion of the crucible 100 may be higher than the temperature of the upper portion of the crucible 100 on the basis of the HZ. In addition, a temperature is increased outwardly from an inner central portion of the crucible 100. The SiC is sublimated due to the temperature gradient, and the sublimated SiC gas is transferred to the surface of the seed 190 having a lower temperature. Accordingly, the SiC gas is recrystallized, so that the SiC gas is grown as a single crystal.

Hereinafter, a method for fabricating the ingot according to the embodiment will be described with reference to FIGS. 3 to 8. For clarity, the structure or components the same as or similar to the above structure or the above components will not be further described in detail below.

FIGS. 3 to 7 are sectional views showing a process of coupling the seed with the holder. FIG. 8 is a view showing a process of forming the ingot.

Referring to FIG. 3, the seed holder 170 is prepared while being overturned. Therefore, the bottom surface of the seed holder 170 may be directed upward.

Referring to FIG. 4, a preliminary adhesive layer 161 is formed on the seed holder 170. The preliminary adhesive layer 161 may include the mixture of a main adhesive layer and enhanced adhesion particles. In this case, the main adhesive layer may include photoresist. In addition, the enhanced adhesion particles may include C, Si, and SiC. Since the main adhesive layer has liquidity, a work can be easily performed and a uniform layer may be formed.

Referring to FIG. 5, the preliminary adhesive layer 161 may be dried. In detail, the pressure applied to the preliminary adhesive layer 161 is reduced. The preliminary adhesive layer 161 may be exposed to light. In other words, since the preliminary adhesive layer 161 includes photoresist, the chemical characteristics of the preliminary adhesive layer 161 may be changed.

Referring to FIG. 6, the seed 190 is attached onto the preliminary adhesive layer 161, and uniform load may be applied thereto. In this case, a step of carbonizing the preliminary adhesive layer 161 may be additionally performed. The step of carbonizing the preliminary adhesive layer 161 may be performed at the temperature of 400? to 500?. Pores can be prevented from being made in the interfacial surface between the seed 190 and the seed holder 170 through the step of carbonizing the preliminary adhesive layer 161.

Referring to FIG. 7, the preliminary adhesive layer 161 may be changed into the adhesive layer 160.

Referring to FIG. 8, the seed holder 170 coupled with the seed 190 is provided on the upper cover 140.

Thereafter, the raw material 130 is heated in the crucible 100, and Si and C of the raw material 130 are sublimated. An ingot I including silicon carbide having a single crystal structure is grown on the seed 190 by the sublimated Si and C.

In this case, the enhanced adhesion particles in the adhesive layer 160 may be changed into SiC. The coupling strength between the seed 190 and the seed holder 170 may be improved through SiC. In addition, SiC is introduced into defective portions of the seed 190 to minimize defects.

Hereinafter, an apparatus for fabricating an ingot according to a second embodiment will be described in detail with reference to FIGS. 9 to 14. For clarity, the structure or components the same as or similar to the above structure or the above components according to the first embodiment will not be further described in detail below.

FIG. 9 is a sectional view showing the apparatus for fabricating the ingot according to the second embodiment, FIG. 10 is an enlarged view showing a part A of FIG 9, and FIG. 11 is a sectional view showing a seed holder and a buffer layer constituting the apparatus for fabricating the ingot according to the second embodiment. FIGS. 12 to 14 are sectional views showing processes of manufacturing a seed holder constituting the apparatus for fabricating the ingot according to the second embodiment.

Referring to FIGS. 9 to 11, an apparatus 20 for fabricating the ingot according to the second embodiment includes the crucible 100, the upper cover 140, the seed holder 170, a buffer layer 162, the focusing tub 180, the adiabatic material 200, the quart tube 400, and the heating induction part 500.

The buffer layer 162 may be formed on the seed holder 170. In detail, the buffer layer 162 may be interposed between the seed holder 170 and the seed 190.

The buffer layer 162 may include a material having a thermal expansion coefficient the same as that of the seed 190 to be grown. In addition, the buffer layer 162 and the seed 190 may include the same material. For example, when SiC single crystal is grown, the buffer layer 162 may include SiC.

Therefore, defects caused by the difference in the thermal expansion coefficient between the seed holder 170 and the seed 190 can be minimized. In addition, the seed 190 can be prevented from being delaminated during a process of growing a single crystal due to the thermal expansion coefficient difference.

Referring to FIG. 10, the buffer layer 162 may include at least one grain boundary 162a. The grain boundary 162a may effectively distribute stress caused when the seed 190 is grown. Therefore, the buffer layer 162 may have a polycrystal structure including at least one grain boundary 162a.

Accordingly, a high-quality polycrystal representing less defects and a large area can be provided. In addition, when a single crystal having a large area is grown, stability and a recovery rate can be improved.

The buffer layer 162 may be formed through a process of growing a polycrystal.

Referring to FIGS. 12 and 14, after introducing the raw material 130 and the seed holder 170 into the crucible 100, the buffer layer 162 may be grown. In detail, after introducing SiC powder 130 and the seed holder 170 in the crucible 100, the buffer layer 162 may be grown at the temperature of about 2300 ℃ at the pressure of 15mbar for one hour to two hours.

Referring to FIG. 13, the buffer layer 162 may be grown from the surface of the seed holder 170 by sublimating SiC powders 130. In other words, SiC polycrystal may be grown on the surface of the seed holder 170. If the seed holder 170 includes graphite, SiC grains are grown in the seed holder 170, so that the seed holder 170 and the buffer layer 162 may represent higher coupling strength.

Referring to FIG. 14, a polishing process may be performed in order to ensure the uniform surface of the buffer layer 162.

After the polishing process has bee performed, the seed 190 may be attached to the buffer layer 162 by using an adhesive agent.

During the high-temperature process of growing a single crystal from the seed 190, a SiC_1-X layer is formed on the interfacial surface between the buffer layer 162 and the seed 190, so that the lattice mismatch between the buffer layer 162 and the seed 190 can be minimized. In addition, since the buffer layer 162 has very small grains, the buffer layer 162 can have a back-bone structure of the SiC_1-X layer.

Any reference in this specification to "one embodiment", "an embodiment", "example embodiment", etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure.　 More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims.　 In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

Claims

An apparatus for fabricating an ingot, the apparatus comprising:

a crucible receiving a raw material;

a holder fixing a seed provided on the raw material; and

an adhesive layer interposed between the holder and the seed while adhering to the seed,

wherein the adhesive layer comprises:

a main adhesive layer adhering to the seed; and

adhesion enhancing particles dispersed in the main adhesive layer.
The apparatus of claim 1, wherein the main adhesive layer includes resin.
The apparatus of claim 2, wherein the main adhesive layer includes photoresist.
The apparatus of claim 2, wherein the adhesion enhancing particles include at least one selected from the group consisting of carbon (C), silicon (Si), and silicon carbide (SiC).
The apparatus of claim 4, wherein the adhesion enhancing particles have contents in a range of 10weight% to 30weight% with respect to the adhesive layer.
The apparatus of claim 4, wherein each adhesion enhancing particle has a diameter of 10㎛.
The apparatus of claim 1, wherein the adhesive layer has a thickness of 100㎛ to 500㎛.
The apparatus of claim 1, wherein the holder includes graphite.
A method for fabricating an ingot, the method comprising:

forming a preliminary adhesive layer, which is obtained by mixing a main adhesive layer and adhesion enhancing particles, between a holder and a seed;

forming an adhesive layer attached to the seed by drying the preliminary adhesive layer; and

growing a silicon carbide crystal on the seed by using a raw material including silicon (Si) and carbon (C).
The method of claim 9, wherein the main adhesive layer includes resin.
The method of claim 9, wherein the adhesion enhancing particles include at least one selected from the group consisting of C, Si, and SiC.
The method of claim 9, wherein the forming of the adhesive layer comprises:

reducing a pressure applied to the preliminary adhesive layer; and

exposing the preliminary adhesive layer to a light.
The method of claim 9, wherein the forming of the adhesive layer further comprises carbonizing the preliminary adhesive layer.
The method of claim 13, wherein the carbonizing of the preliminary adhesive layer is performed at a temperature in a range of 400? to 500?.
An apparatus for fabricating an ingot, the apparatus comprising:

a crucible receiving a raw material; and

a seed holder fixing a seed on the raw material,

wherein a buffer layer is formed on the seed holder.
The apparatus of claim 15, wherein the buffer layer is interposed between the seed holder and the seed.
The apparatus of claim 16, wherein a thermal expansion coefficient of the buffer layer is equal to a thermal expansion coefficient of the seed.
The apparatus of claim 17, wherein a material of the buffer layer is a same as a material of the seed.
The apparatus of claim 16, wherein the buffer layer includes at least one grain boundary.
The apparatus of claim 19, wherein the buffer layer has a polycrystal structure.
The apparatus of claim 20, wherein the buffer layer includes silicon carbide.
The apparatus of claim 21, wherein the seed holder includes graphite.