KR20120039817A - Single crystal grower - Google Patents

Abstract

PURPOSE: An apparatus for growing single crystal is provided to reduce stress applied to a peripheral subsidiary material by dividing an oxide deposition prevention layer. CONSTITUTION: An apparatus for growing single crystal includes a crucible(120), a heat shield, and a support stand(125). The heat shield is arranged in an upper part of the crucible. The support stand is included in the upper one end of the heat shield. A surface of the support stand which is contiguous to the crucible includes a second oxide deposition prevention layer(143) The second oxide deposition prevention layer is divided into a plurality of areas. The plurality of areas is combined with a bonding groove in the second oxide deposition prevention layer.

Description

Single Crystal Grower

The embodiment relates to a single crystal growth apparatus.

In order to manufacture a semiconductor, a wafer must be manufactured, and in order to manufacture a wafer, single crystal silicon must be grown in the form of an ingot, and for this, the Czochralski (CZ) method can be applied.

In the prior art, the dopant is added to the silicon melt to control the resistance as follows. For example, when a low volatility dopant such as boron is used, when a polysilicon is placed in a quartz crucible, the dopant is added together to be melted, followed by a single crystal process.

On the other hand, in the case of using a high volatility such as Sb, As, Pb as a dopant, proceed in the same manner as in the case of Boron, or doping directly to the surface of the melt in the solid state after the polysilicon melted, or After the silicon was melted, it proceeded to a method of doping by gasifying a certain depth of the melt surface in the sublimed state.

When selecting a dopant suitable for the resistance level, especially when doping in a boron-like manner to control the resistance with a highly volatile dopant, a lot of volatilization is generated by the heat applied during melting. In addition, the volatilized dopant will contaminate the interior of the device, especially if the volatilization is high and more dopants have to be added. Therefore, if a high volatility dopant is chosen, it is preferred to apply it after the polysilicon is completely melted.

However, no matter which method is chosen, there is no way to completely prevent contamination in the equipment, so contamination of the single crystal growth apparatus is inevitable.

The embodiment aims to provide a single crystal growth apparatus in which contaminants generated during single crystal growth fall into by-products such as oxides on the surface of the melt and do not lower the yield.

In addition, the embodiment is to provide a single crystal growth apparatus that can facilitate the cleaning of the heat shield when the heat shield is contaminated.

Single crystal growth apparatus according to the embodiment is a crucible; A heat shield disposed above the crucible; And a support provided at one end of the upper heat shield, wherein the surface of the support adjacent to the crucible may include a second oxide deposition preventing layer.

According to the single crystal growth apparatus according to the embodiment, it is possible to eliminate the phenomenon that the contamination source is reduced to the yield in the single crystal growth step.

In addition, according to the embodiment, it is possible to simply remove the contaminant by etching, thereby saving time and cost by omitting a process of applying additional heat.

In addition, according to the embodiment it is possible to increase the frequency of use by protecting the heat shield from the pollution source, the support can be used semi-permanently as long as it is not damaged.

In addition, according to the embodiment it is possible to reduce the weight through the division of the oxide deposition prevention layer is applicable to large diameters, it is possible to reduce the stress applied to the peripheral subsidiary materials.

In addition, according to the embodiment, even if the single crystal is large-sized through the division of the oxide deposition prevention layer, it is not necessary to greatly enlarge the etching bath size during the etching for cleaning.

In addition, according to the embodiment, even if the oxide deposition prevention layer is divided, the divided portion is not dismantled during the process by applying a method of bonding into grooves, and the problem of bonding the grooves by using a material having a low thermal expansion coefficient as the material of the oxide deposition prevention layer Does not occur.

1 is an illustration of a single crystal growth apparatus according to the embodiment.
Figure 2 is an illustration of a low melting point oxide in the single crystal growth apparatus according to the prior art.
Figure 3 is an illustration of the contaminants generated in the single crystal ingot during the single crystal growth apparatus process according to the prior art.
Figure 4 is an exemplary table of the generation probability of contaminants in the single crystal ingot during the single crystal growth apparatus process according to the prior art.
Figure 5 is an enlarged view of a portion of the upper heat shield in the single crystal growth apparatus according to the embodiment.
6 is an enlarged view of the support of the single crystal growth apparatus according to the embodiment.
7 is an enlarged exemplified view of the second oxide barrier layer in the single crystal growth apparatus according to the embodiment.

In the description of the embodiments, each wafer, apparatus, chuck, member, sub-region, or surface is referred to as being "on" or "under" Quot ;, " on "and" under "include both being formed" directly "or" indirectly " In addition, the criteria for "up" or "down" of each component are described with reference to the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation and does not mean the size actually applied.

(Example)

1 is an illustration of a single crystal growth apparatus 100 according to an embodiment.

The silicon single crystal growth apparatus 100 according to the embodiment may include a chamber 110, a crucible 120, a heater 130, a pulling means 150, and the like.

For example, the single crystal growth apparatus 100 according to the embodiment is provided in the chamber 110, the inside of the chamber 110, the crucible 120 containing the silicon melt, and the inside of the chamber 110. It is provided in, and may include a pulling means 150 coupled to the heater 130 and the seed crystal 152 to heat the crucible 120.

The chamber 110 provides a space in which predetermined processes are performed to grow a single crystal ingot for a silicon wafer used as an electronic component material such as a semiconductor.

The radiant heat insulator 140 may be installed on the inner wall of the chamber 110 to prevent heat of the heater 130 from being discharged to the side wall of the chamber 110.

The embodiment may adjust various factors such as pressure conditions inside the rotation of the quartz crucible 120 to control the oxygen concentration during silicon single crystal growth. For example, in order to control the oxygen concentration, an argon gas or the like may be injected into the chamber 110 of the silicon single crystal growth apparatus and discharged downward.

The crucible 120 is provided inside the chamber 110 to contain the silicon melt SM and may be made of quartz. A crucible support 125 made of graphite may be provided outside the crucible 120 to support the crucible 120. The crucible support 125 is fixedly installed on the rotation shaft 127, which is rotated by a driving means (not shown) so that the solid-liquid interface has the same height while rotating and elevating the crucible 120. It can be maintained.

The heater 130 may be provided inside the chamber 110 to heat the crucible 120. For example, the heater 130 may have a cylindrical shape surrounding the crucible support 125. The heater 130 melts a high-purity polycrystalline silicon mass loaded in the crucible 120 into a silicon melt SM.

The single crystal ingot growth apparatus according to the embodiment may include a support 142 on the radiant heat insulating part 140 so that the heat of the heater 130 is not discharged to the upper part of the chamber 110.

The support 142 is formed to surround the single crystal ingot between the single crystal ingot and the crucible 120 to block the heat emitted from the silicon melt (SM), and also is released from the silicon melt for cooling the grown silicon ingot A heat shield 160 may be mounted to block heat transferred to the silicon ingot.

Example is a manufacturing method for silicon single crystal ingot growth Czochralsk (CZ) method of growing a crystal while immersing the seed crystal (152), which is a single crystal in a silicon melt (SM), and slowly pulling it up. Can be adopted.

According to this method, first, after a necking process of growing thin and long crystals from the seed crystals 152, a shouldering process of growing the crystals in the radial direction to a target diameter is performed. After the body growing process to grow into a crystal having a certain diameter, after the body growing by a certain length, the diameter of the crystal is gradually reduced, and the tailing process to separate from the molten silicon and eventually single crystal (single crystal) The growth is over.

2 is an exemplary photograph of a low melting point oxide in a single crystal growth apparatus according to the prior art.

According to the prior art, the heat shield plate upper (H) and the support 142 region is particularly exposed to contamination compared to other graphite subsidiary materials because the temperature of the heat shield plate is rapidly lowered in the single crystal growth apparatus, thereby increasing the time. As the number of pollutants is increased, the more the frequency of use, the thicker the deposition thickness, and SiC will be deposited in the corresponding area.Since the difference in thermal expansion rate between SiC and the base graphite, In the process of cleaning, the oxidation and thickness reduction of graphite eventually reduce the number of times of use.

This phenomenon is not only related to the addition of high volatility dopants, and even if the volatility is low, this phenomenon occurs due to high diameter and high charge, especially when the process time is long. Only difference can be said.

In the conventional prior art, in order to remove such pollutants, the heat shield plate is reheated after completion of single crystal growth to remove even portions not removed during cleaning. This removes the contaminants but reduces the number of uses regardless of single crystal growth.

As the deposition time of the oxide film increases, the thickness of the deposited film becomes thicker as the process time increases. As a result, the difference in thermal expansion rate between the oxide and the graphite rapidly increases. In fact, when the single crystal is polycrystallized during the process, dopants are added as needed in the melt to maintain the same resistivity after melting again. At low melting points, almost 30 to 50% of these inputs are volatilized. It is to be deposited at the top of the relatively low temperature.

The lower the resistivity, the more low melting dopants are introduced into the melt, and as the input increases, the amount of volatilized and deposited increases.

Figure 3 is an illustration of the contamination (P) photo generated in the single crystal ingot during the single crystal growth apparatus process according to the prior art.

In summary, the use of a low melting dopant inevitably results in volatilization, and as more low melting dopants are added to reduce the resistivity, and as the process time increases, these oxides become relatively hot. It is deposited on the lower part of the heat shield plate and thickens, and the mass of these oxides falls into the melt during the process and floats and adheres to the inner wall of the quartz crucible following the rotation of the quartz crucible. Generates.

3 is a practical example, and the size of the oxide was clearly visible even with the naked eye at about 2 cm in length and width.

4 is a table illustrating the probability of contaminants occurring in the single crystal ingot during the single crystal growth apparatus according to the related art.

In view of the process time, as shown in FIG. 4, if the amount of volatilization per hour is fixed at about 5 g / h, this phenomenon starts to increase rapidly after about 45 hours (hr), and when the total amount of the dopant is about 225 g or more. The frequency of occurrence becomes high.

5 is an enlarged exemplary view of an upper heat shield in the single crystal growth apparatus according to the embodiment.

In the heat shield 160 according to the embodiment of the heat shield disposed above the crucible 120 of the single crystal growth apparatus, a lower heat shield body and an upper heat shield body extending upward from the lower heat shield body are formed. (H) and the first oxide deposition preventing layer 164 provided on one side of the upper heat shield body (H).

The lower heat shield body may be located inside the crucible 120, and the upper heat shield body H may be located outside the crucible 120, but is not limited thereto.

The first oxide deposition preventing layer 164 may be provided on the bottom surface of the upper heat shield body H, but is not limited thereto.

In addition, the first oxide deposition prevention layer 164 may be in the form of a cover (cover) surrounding the upper heat shield body (H), but is not limited thereto.

In the embodiment, in order to minimize the change in the weight or thickness of the heat shield, the first oxide deposition preventing layer 164 is made of molybdenum in the form of a cover (Cover) in the portion where the deposition of the oxide film occurs, not the whole of the heat shield. To minimize the weight.

The first oxide deposition preventing layer 164 may be formed of molybdenum, but is not limited thereto. In an embodiment, when the first oxide deposition preventing layer 164 is formed of molybdenum, the oxide deposition is less than that of graphite, and the thermal expansion rate is lower than that of graphite, and thus the peeling phenomenon due to the difference in thermal expansion with the deposited oxide is reduced. This has less advantages.

6 is an enlarged view of the support of the single crystal growth apparatus according to the embodiment.

The single crystal growth apparatus according to the embodiment may include a heat shield support 142, and the heat shield 160 may be mounted on the support 142.

In the single crystal growth apparatus according to the embodiment, the surface of the support adjacent to the crucible may include a second oxide deposition preventing layer 143. The second oxide deposition preventing layer 143 may be formed of molybdenum, but is not limited thereto.

The second oxide deposition preventing layer 143 may have a cylindrical shape, but is not limited thereto. For example, the second oxide deposition preventing layer 143 may be interposed between the support and the heat shield 160, but is not limited thereto.

According to the embodiment, not only the heat shield but also the surface of the support, which is particularly vulnerable to pollutants, may be supplemented with molybdenum, thereby improving the number of times of use of the subsidiary materials and improving the yield.

7 is an enlarged exemplary view of a second oxide barrier layer in the single crystal growth apparatus according to the embodiment.

The cross-sectional view of the second oxide deposition preventing layer 143 in the single crystal growth apparatus according to the embodiment is not limited to the groove bonding example of the second oxide deposition preventing layer 143 designed in the embodiment.

In an embodiment, the second oxide deposition preventing layer 143 of the heat shield may be separated into a plurality of regions. In addition, the plurality of regions may be coupled to the second oxide deposition preventing layer 143 by the coupling groove 145. For example, it may be firmly coupled by a groove coupling or the like, but is not limited thereto.

In an embodiment, the second oxide deposition preventing layer 143 of the heat shield may be etched with hydrofluoric acid during cleaning, and when the second oxide deposition preventing layer 143 is not separated into a plurality of regions, etching is performed toward larger diameters. Since the bath must be infinitely large accordingly, it was divided and designed to improve this part.

Accordingly, the embodiment is designed to divide the second oxide deposition preventing layer 143 of the heat shield, so that there is no inconvenience in using the existing etching bath as it is. On the other hand, even if the division can be made by fitting the grooves so as to bond well, in this case, the second oxide deposition preventing layer 143 can be firmly bonded due to the characteristics of molybdenum having a low thermal expansion coefficient.

According to the single crystal growth apparatus according to the embodiment, it is possible to eliminate the phenomenon that the contamination source is reduced to the yield in the single crystal growth step.

In addition, according to the embodiment, it is possible to simply remove the contaminant by etching, thereby saving time and cost by omitting a process of applying additional heat.

In addition, according to the embodiment it is possible to increase the frequency of use by protecting the heat shield from the pollution source, the support can be used semi-permanently as long as it is not damaged.

In addition, according to the embodiment it is possible to reduce the weight through the division of the oxide deposition prevention layer is applicable to large diameters, it is possible to reduce the stress applied to the peripheral subsidiary materials.

In addition, according to the embodiment, even if the single crystal is large-sized through the division of the oxide deposition prevention layer, it is not necessary to greatly enlarge the etching bath size during the etching for cleaning.

In addition, according to the embodiment, even if the oxide deposition prevention layer is divided, the divided portion is not dismantled during the process by applying a method of bonding into grooves, and the problem of bonding the grooves by using a material having a low thermal expansion coefficient as the material of the oxide deposition prevention layer Does not occur.

The features, structures, effects and the like described in the embodiments are included in at least one embodiment and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Accordingly, the contents of such combinations and modifications should be construed as being included in the scope of the embodiments.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. It can be seen that the modification and application of branches are possible. For example, each component specifically shown in the embodiment can be modified. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

Claims (9)

Crucible;
A heat shield disposed above the crucible; And
And a support provided at one end of the upper heat shield.
And a surface of the support adjacent to the crucible includes a second oxide deposition preventing layer. The method according to claim 1,
The second oxide deposition prevention layer,
Single crystal growth apparatus formed of molybdenum. The method according to claim 1,
The second oxide deposition prevention layer,
Single crystal growth apparatus that can be separated into a plurality of regions. The method of claim 3,
The second oxide deposition prevention layer,
Single crystal growth apparatus that can be coupled to the plurality of regions by the coupling groove. The method according to claim 1,
The heat shield,
Lower heat shield body;
An upper heat shield body extending upward from the lower heat shield body; And
And a first oxide deposition prevention layer provided on one side of the upper heat shield body. The method of claim 5,
The lower heat shield body is a heat shield located inside the crucible. The method of claim 5,
The upper heat shield body is a heat shield located outside the crucible. The method of claim 5,
The first oxide deposition prevention layer,
A heat shield provided on the bottom of the upper heat shield body. The method according to claim 1,
The first oxide deposition prevention layer,
Heat shield formed of molybdenum.

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