KR20110090474A - Method for manufacturing single crystal - Google Patents

Abstract

PURPOSE: A method for manufacturing a single crystal is provided to control temperature side or a single crystal growth by controlling a coagulation interface according to the input of a dopant of high volatility low melting. CONSTITUTION: In a method for manufacturing a single crystal, a silicon solution(melt) is formed. A dopant having lower melting point than the silicon solution is inputted. The growth speed of the single solder is controlled to be maintained in performing a solder process of inputting the silicon solution.

Description

Method for Manufacturing Single Crystal

The example relates to a single crystal growth method.

In order to manufacture a silicon wafer, single crystal silicon must first be grown in an ingot form, and for this, a Czochralski (CZ) method or a floating zone (FZ) method may be applied.

In general, silicon wafers used as substrates for semiconductor devices have a P-type or N-type dopant added in the growth process of silicon single crystals in order to have an appropriate resistivity value.

In addition, the P-type or N-type dopant is divided into a high melting point dopant having a melting point higher than that of silicon and a low melting point dopant having a melting point lower than the melting point of silicon. The dopant is added to the silicon melt according to the type of dopant. This is different.

A typical P-type high melting point dopant is boron (B), and its melting point is about 2180 ° C., which is higher than the melting point of silicon 1414 ° C., so that polycrystalline silicon, which is a silicon single crystal growth preparation step, is loaded into a quartz crucible. It is possible to add dopants to the silicon melt by injecting and melting together with polycrystalline silicon in the bottom of the quartz crucible.

On the other hand, high-volatile low-melting dopants having a lower melting point than silicon include antimony (Sb), red (Red Phosphorus), germanium (Ge), arsenic (As), etc. These low-melting dopants are low Due to the melting point, in the melting stage of the first polycrystalline silicon during the single crystal growth process, the polycrystalline silicon is melted and vaporized before completely melting.

On the other hand, in order to grow a single crystal implanted with a high volatile low melting dopant, temperature control for each process is essential.

According to the prior art, single crystal growth has increased the monocrystalline gain (%) by controlling the coagulation interface. However, if the high volatile low melting point dopant is applied, not only the general coagulation interface control but also the coagulation surface height is changed due to the heat of vaporization by the high volatility low melting point dopant.

The embodiment provides a single crystal growth method capable of controlling the coagulation interface due to the injection of a high volatile low melting point dopant.

The single crystal growth method according to the embodiment comprises the steps of forming a silicon melt (melt) and injecting a dopant having a lower melting point than silicon into the silicon melt, wherein the dopant implanted silicon melt In the shoulder process, the acceleration of the growing single crystal to the shoulder growth rate can be controlled to be constant.

According to the embodiment, it is possible to provide a single crystal growth method capable of controlling the coagulation interface due to the injection of a high volatile low melting point dopant in terms of temperature or single crystal growth rate during single crystal growth.

1 is an illustration of a single crystal growth apparatus to which the single crystal manufacturing method according to the embodiment is applied.
Figure 2 is an illustration of the temperature gradient of the silicon melt surface in the single crystal manufacturing method according to the embodiment.
Figure 3 is an illustration of the difference in density of the silicon melt in the single crystal manufacturing method according to the embodiment.
Figure 4 is an illustration of the difference in heat of vaporization of the silicon melt in the single crystal manufacturing method according to the embodiment.
5 is an exemplary view of the temperature gradient during the shoulder process in the single crystal manufacturing method according to the embodiment.
Figure 6 is an illustration of the temperature gradient during the second shoulder process in the single crystal manufacturing method according to the embodiment.
7 is a view illustrating a difference in vaporization heat according to the distance to the heater during the shoulder process in the single crystal manufacturing method according to the embodiment.
8 is an exemplary view illustrating temperature control during the necking process in the single crystal manufacturing method according to the embodiment.
9 is an exemplary temperature control during the shoulder process in the single crystal manufacturing method according to the embodiment.
10 is an exemplary view of the temperature gradient during the body process in the single crystal manufacturing method according to the embodiment.
11 is an exemplary view illustrating temperature control during a body process in a single crystal manufacturing method according to an embodiment.
12 is an exemplary speed control in the single crystal manufacturing method according to the embodiment.

Hereinafter, a single crystal growth method according to an embodiment will be described in detail with reference to the accompanying drawings.

(Example)

1 is an illustration of a single crystal growth apparatus to which a single crystal manufacturing method according to an embodiment is applied.

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 embodiment is a manufacturing method for growing a silicon single crystal ingot 200, Czochralsk (Czochralsk: soaking a seed crystal (152), which is a single crystal in silicon melt (SM), and then slowly pulls up and grows the crystals. CZ) method 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 view of the temperature gradient of the surface of the silicon melt in the single crystal manufacturing method according to the embodiment.

The embodiment provides a single crystal growth method capable of controlling the coagulation interface due to the injection of a high volatile low melting point dopant.

The embodiment relates to a silicon single crystal growth method in which a high volatile low melting dopant is injected into a silicon melt.

The dopant may be subjected to a dopant implantation process by a predetermined dopant injector. In an embodiment, the dopant may be antimony (Sb), red (osp), germanium (Ge), arsenic (As), etc., but is not limited thereto. Do not.

Such a dopant may be classified into a low concentration (first concentration) dopant and a high concentration (second concentration) dopant.

For example, the low concentration of the first concentration may be a concentration such that the specific resistance of the silicon single crystal is less than 0.003Ωcm as the dopant of the first concentration is injected,

The high concentration of the second concentration may be a concentration such that the specific resistance of the silicon single crystal becomes 0.003Ωcm or more as the dopant of the second concentration is injected, but is not limited thereto.

3 is an exemplary view illustrating a difference in density of a silicon melt in a single crystal manufacturing method according to an embodiment, and FIG. 4 is a view illustrating a difference in heat of vaporization of a silicon melt in a single crystal manufacturing method according to an embodiment.

According to the embodiment, even at low concentrations, a considerable amount of dopant is introduced in view of the resistance level, especially in the case of the surface of the silicon melt (SM) where the shoulder is grown, compared to the P-type dopant in the radial direction, for example, boron. The difference is large, which results in a more pronounced temperature difference on the surface of the silicon melt (SM).

For example, near the heater, the density is significantly lower than the middle (50%) of the silicon melt (SM), and more intense at high concentrations where more dopant is added. This causes the volatilization speed to be closer to the heater 130.

Therefore, it is important to control the growth rate of the shoulder according to the change of the subcooling area which is secured in the radial direction.

5 is an exemplary view of the temperature gradient during the shoulder process in the single crystal manufacturing method according to the embodiment, Figure 6 is an illustration of the temperature gradient during the second shoulder process in the single crystal manufacturing method according to the embodiment.

7 is a view illustrating a difference in vaporization heat according to the distance to the heater during the shoulder process in the single crystal manufacturing method according to the embodiment.

In FIG. 5 to FIG. 7, the distance (%) with respect to the heater is set to 0 to 120% unlike FIG. 2, but this is for the distance (%) with respect to the heater as shown in FIG. 2 and the distance from one heater to the other heater ( %) Is set from 0 to 120%.

According to the embodiment, the shoulder 220 has a constant thickness and an area in which the thermal energy of the low melting dopant molecules volatilized under atmospheric conditions while the shoulder 220 grows horizontally from the seed crystal 152 in the center of the silicon melt (SM) (60%). The heat energy is released through.

As a result, the number of empty spaces of thermal energy decreases and the amount of thermal energy released into the atmosphere decreases, resulting in less heat energy exchanged with the silicon melt (SM) for a long period of time, which is relatively lower than the condition emitted from the atmosphere in terms of temperature. Done.

As a result, a sufficient subcooling area is secured at a level of the constant shoulder 220 diameter, thereby ensuring a horizontal growth rate.

By the way, in the case of a predetermined diameter that is close to the heater 130, the volatilization rate is rapidly increased to secure the subcooled region. Therefore, the horizontal growth rate of the shoulder should be significantly reduced compared to the low concentration. This reduction in speed may be possible as a control of temperature.

That is, the embodiment has a lower temperature than each single crystal growth step of the single crystal growth step in which the dopant is injected than the single crystal growth step in which the high volatility low melting dopant is not injected, thereby resulting in the injection of the high volatile low melting point dopant. The control of the coagulation interface can be controlled in terms of temperature during each process of single crystal growth.

In the embodiment, each single crystal when the dopant has a second concentration (high concentration) higher than the first concentration (low concentration) than the temperature decrease width of each single crystal growth step when the concentration of the dopant is the first concentration (low concentration). The temperature reduction during the growth phase may be higher.

8 is an exemplary view illustrating temperature control during the necking process in the single crystal manufacturing method according to the embodiment.

According to an embodiment, in a necking process for a silicon melt (SM) in which the dopant is injected, a silicon solution in which the dopant is injected is reduced at a temperature of about 5% to about 50% of a temperature for a necking process in which the dopant is not injected. The necking process can be performed.

In the embodiment, the necking (%) in the case of low concentration and high concentration may reduce the temperature within about 5% to about 50%, and at high concentration more temperature should be reduced. This is in line with the fact that at high concentrations the volatility is up to 50% stronger than at low concentrations. After a certain time, the temperature difference between low concentration and high concentration gradually decreases because the subcooling region is secured.

9 is an exemplary view illustrating temperature control during the shoulder process in the single crystal manufacturing method according to the embodiment.

In the embodiment, the shoulder process for the dopant-infused silicon melt, wherein the shoulder process for the dopant-infused silicon solution at a temperature of 10% to 50% of the temperature for the shoulder process without the dopant is injected You can proceed.

For example, in the case of shoulders, the percentage of decreasing temperature will be higher and higher based on diameter growth. This is because, in the case of high volatility, it is not easy to secure a subcooled region below a certain portion of the silicon melt surface and the silicon melt surface due to volatilization.

According to the embodiment, in the case of high concentration, at least 10% and at least 50% or less, the temperature of the high concentration is lowered compared to the low concentration to prevent polycrystallization.

10 is an exemplary view of the temperature gradient during the body 230 process in the single crystal manufacturing method according to the embodiment.

In FIG. 10, P is a pulling speed synergistic effect, Q is a heat of vaporization from the silicon melt, R is a heat of solidification from the single crystal 200, and S may mean a supercooling area according to temperature control. .

Temperature control for each process is essential for growing single crystals with high volatility and low melting dopants. The embodiment is directed to growing a highly volatile dopant melted with silicon into a single crystal.

In general, single crystal growth has increased the monocrystalline yield by controlling the coagulation interface and controlling it. However, in the case where the dopant of high volatility is applied, not only the general coagulation interface control but also the coagulation interface height due to the heat of vaporization depends on the coagulation interface control. Therefore, the embodiment intends to present such a control at an appropriate temperature level for each process in terms of temperature.

11 is an exemplary view illustrating temperature control during body processing in a single crystal manufacturing method according to an embodiment.

On the other hand, in the case of the body 230, if a constant subcooling area is secured, further temperature reduction may increase the pulling speed (Pulling Speed), making it difficult to secure the subcooling area, so that excessive temperature reduction may not proceed.

In case of further reducing the temperature in the body process of the embodiment, the additional temperature decrease is reduced to the low concentration (the first concentration) because a sufficient subcooling area is secured in the necking and shouldering processes in the case of the high concentration (second concentration). The reduction rate can be higher by reducing it by 60% or less.

According to the single crystal production method according to the embodiment, it is possible to prevent contamination of the silicon melt by the low melting point dopant by adjusting the doping process conditions of the low melting point dopant.

12 is an exemplary speed control in the shoulder process of the single crystal manufacturing method according to the embodiment.

In Fig. 12, the Y axis on the left represents the diameter growth rate of the shoulder, and the Y axis on the right represents the pulling rate. In FIG. 12, the X-axis may be set to 100% of the total shoulder process time. In FIG. 12, the total length of the shoulder process may be set to about 100 minutes. However, the shoulder process time is not limited thereto. It represents the proportional time of the corresponding% time of% time.

According to the embodiment it can be controlled so that the shoulder growth rate is rapidly reduced from about 40% of the total time of the shoulder growth process compared to the low concentration. Through this, it is possible to accumulate the time for securing the subcooling area, and thus, it is possible to control the pulling speed in a streamlined manner so as to fit the target diameter of the body during the over shoulder process.

In the embodiment, in the shoulder growth of a single crystal in which a high-volatile low-melting dopant is added and grown, the acceleration must be controlled to be constant in terms of acceleration so that the growth can be performed without polycrystallization. It can be implemented through temperature and / or pulling rate (P / S) control to be uniformly controlled in terms of growth rate.

For example, as a method of controlling the shoulder growth of the single crystal through the speed and acceleration control as shown in FIG. 12, the technical features of the above-described temperature control can be adopted.

For example, in the case of a predetermined diameter that is close to the heater 130, the volatilization speed increases rapidly, making it difficult to secure the subcooled region. Therefore, the horizontal growth rate of the shoulder should be significantly reduced compared to the low concentration. This reduction in speed may be possible as a control of temperature.

That is, in the embodiment, the temperature of the shoulder process in which the dopant is injected is lower than that in each single crystal growth step in which the high volatility low melting point dopant is not injected, thereby controlling the coagulation interface according to the injection of the high volatility low melting point dopant. It can be controlled in terms of temperature during growth shoulder process.

In the embodiment, each single crystal when the dopant has a second concentration (high concentration) higher than the first concentration (low concentration) than the temperature decrease width of each single crystal growth step when the concentration of the dopant is the first concentration (low concentration). The temperature reduction during the growth phase may be higher.

For example, Figure 9 is an exemplary view of temperature control during the shoulder process in the single crystal manufacturing method according to the embodiment.

In the embodiment, the shoulder process for the dopant-infused silicon melt, wherein the shoulder process for the dopant-infused silicon solution at a temperature of 10% to 50% of the temperature for the shoulder process without the dopant is injected You can proceed.

For example, in the case of shoulders, the percentage of decreasing temperature will be higher and higher based on diameter growth. This is because, in the case of high volatility, it is not easy to secure a subcooled region below a certain portion of the silicon melt surface and the silicon melt surface due to volatilization.

According to the embodiment, in the case of high concentration, at least 10% and at least 50% or less, the temperature of the high concentration is lowered compared to the low concentration to prevent polycrystallization.

According to the embodiment, it is possible to provide a single crystal growth method capable of controlling the coagulation interface due to the injection of a high volatile low melting point dopant in terms of temperature or single crystal growth rate during single crystal growth.

The present invention is not limited to the described embodiments and drawings, and various other embodiments are possible within the scope of the claims.

Claims (9)

A method of growing a single crystal comprising forming a silicon melt and injecting a dopant having a lower melting point than silicon into the silicon melt,
In the shoulder process for the silicon melt implanted with the dopant, the single crystal growth method is controlled so that the acceleration to the shoulder growth rate of the grown single crystal is constant. The method according to claim 1,
In controlling the acceleration to the shoulder growth rate is constant,
Single crystal growth method that controls the acceleration to shoulder growth rate by controlling the shoulder growth temperature or the pulling rate (P / S). The method of claim 2,
In controlling the acceleration to the shoulder growth rate is constant,
Wherein the process temperature of the single crystal shoulder processing step in which the dopant is injected is lower than the single crystal shoulder processing step in which the dopant is not injected. The method of claim 3,
The single crystal growth method having a higher temperature reduction range in each single crystal growth stage when the dopant concentration is higher than the first concentration than the temperature decrease width in each single crystal growth stage when the concentration of the dopant is the first concentration. The method of claim 4, wherein
Wherein the first concentration is such that the specific resistance of the silicon single crystal is less than 0.003 Ωcm as the dopant of the first concentration is injected. The method of claim 4, wherein
Wherein the second concentration is a concentration such that the specific resistance of the silicon single crystal becomes 0.003 Ωcm or more as the dopant of the second concentration is injected. The method according to any one of claims 4 to 6,
In the shoulder process for the silicon melt injected with the dopant,
And a shoulder process for the silicon solution in which the dopant is injected at a temperature of 10% to 50% of the temperature for the shoulder process in which the dopant is not injected. The method of claim 4, wherein
The single crystal growth method in which the speed reduction of the shoulder process when the dopant concentration of the second concentration is higher than the speed decrease in the shoulder process when the first concentration is higher. The method of claim 8,
In the case of the shoulder process having the dopant concentration of the second concentration, the growth rate of the shoulder decreases more than the case of the first concentration after 40% of the entire time of the shoulder growth process, compared to the shoulder process of the first concentration. Single crystal growth method controlled to.

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