KR101073051B1 - METHOD FOR LOW-TEMPERATURE FAST FORMING OF Si THIN FILM AND APPARATUS FOR MANUFACTURING THE SAME - Google Patents

Abstract

The present invention relates to a silicon thin film deposition apparatus capable of depositing a silicon thin film on a substrate at high speed, and a silicon thin film deposition method using the same. In the deposition method of a silicon thin film, the substrate is cleaned to remove foreign substances on the surface of the substrate, the substrate is mounted inside the chamber, the substrate is cooled using a cooling fluid, and the chamber is heated to form a temperature gradient between the substrate and the chamber. And injecting the silicon source gas into the chamber and heating and pyrolyzing the silicon source gas to deposit a silicon thin film on the substrate.

Thin film, deposition, source gas, chamber, substrate, cooling, support, heating, control unit

Description

METHOD FOR LOW-TEMPERATURE FAST FORMING OF Si THIN FILM AND APPARATUS FOR MANUFACTURING THE SAME

The present invention relates to a method for depositing a silicon thin film, and more particularly, to a method and apparatus for low temperature high speed deposition of a silicon thin film capable of high speed deposition of a silicon thin film on a substrate.

Research into integrating semiconductor devices on substrates of various materials such as glass, plastic, as well as silicon wafers, is being conducted. In addition, in order for a semiconductor device to perform a complex information processing function, a technique of depositing a polycrystalline silicon material having a relatively high electron mobility in a thin film form is required.

The polycrystalline silicon thin film may be formed by first depositing an amorphous silicon thin film first and then irradiating a laser beam to instantly melt and recrystallize the amorphous silicon. However, this method is difficult to apply to substrates with very low heat resistance, such as plastics.

On the other hand, it is also possible to deposit polycrystalline silicon directly on the substrate, in which case the deposition rate is very slow. In addition, in order to deposit on a substrate having relatively low heat resistance, the deposition rate should be lower than that of a substrate having high heat resistance, and the deposition rate should be further lowered to obtain a high quality thin film. Therefore, the importance of a technique capable of high speed deposition in a low temperature range is becoming more important.

The present invention is to provide a method and apparatus for low temperature and high speed deposition of a silicon thin film capable of rapidly depositing a high quality thin film on a substrate of various materials.

According to an embodiment of the present invention, a low-temperature, high-speed deposition method of a silicon thin film may include: i) cleaning a substrate to remove foreign substances from the surface of the substrate, ii) mounting the substrate inside the chamber, and iii) using a cooling fluid. Iii) heating the chamber to form a temperature gradient between the substrate and the chamber, iii) injecting a silicon source gas into the chamber, and heating and pyrolysing the silicon source gas to deposit a silicon thin film on the substrate. .

The substrate cooling unit may be provided in contact with the substrate in the chamber, and the substrate may be cooled by supplying a cooling fluid to the substrate cooling unit from the outside of the chamber.

In the step of forming a temperature gradient and depositing a thin film, the cooling fluid may be continuously supplied to the substrate cooling unit.

The temperature gradient can be increased in proportion to the flow rate of the cooling fluid and the pressure of the silicon source gas. In the step of depositing the silicon thin film, the temperature difference between the substrate and the silicon source gas may be in the range of 100 ℃ to 200 ℃, the temperature of the substrate may be in the range of 0 ℃ to 600 ℃.

The substrate may be made of any one of silicon, glass, quartz, alumina and plastic. The silicon source gas may comprise a monosilane gas diluted with helium gas or hydrogen gas.

A low temperature high speed deposition apparatus of a silicon thin film according to an embodiment of the present invention, iii) a chamber for supplying a silicon source gas, ii) a chamber heating unit installed in the chamber to heat the chamber, iii) mounted inside the chamber, A substrate support for supporting a substrate on which a silicon thin film is to be deposited; (iii) a substrate support provided in contact with the substrate, the substrate cooling part for cooling the substrate by receiving a cooling fluid from the outside of the chamber, and iii) a chamber heating part and a substrate cooling part. It is connected to the unit and includes a control unit for controlling the temperature of the chamber and the substrate, respectively.

The substrate cooling unit includes: iii) a circulating pipe part contacting the substrate and receiving and circulating a cooling fluid; ii) a first pipe part connecting the circulation pipe part to the outside of the chamber to supply cooling fluid to the circulation pipe part, and iii) a first pipe part. The double pipe may be configured together with the surrounding first pipe part, and may include a second pipe part which connects the circulation pipe part and the outside of the chamber to discharge the cooling fluid used for cooling.

The substrate cooling unit may further include a protection tube unit surrounding the second tube unit and maintaining the inside in a vacuum.

The substrate support part may form an inner space for accommodating the circulation pipe part, and may include an upper surface having an opening smaller than the substrate.

When depositing a silicon thin film on a substrate using chemical vapor deposition (CVD), a large temperature gradient can be formed between the substrate and the chamber as the substrate is cooled. Therefore, a high quality silicon thin film can be deposited on a low temperature substrate at high speed, and a substrate having very low heat resistance such as plastic can be easily applied to form a silicon thin film on a substrate of various materials.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

1 is a perspective view illustrating a low temperature high speed deposition apparatus of a silicon thin film according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view illustrating a substrate, a substrate support unit, and a substrate cooling unit of the low temperature high speed deposition apparatus of FIG. 1.

1 and 2, the low-temperature, high-speed deposition apparatus 100 of the silicon thin film according to the first embodiment may include a chamber 10, a chamber heating part 12, a substrate support part 14, and a substrate cooling part 16. And a control unit 18.

The chamber 10 may be made of a quartz tube. The substrate 20 is positioned inside the chamber 10, and a silicon source gas for depositing a silicon thin film is supplied into the chamber 10. The silicon source gas may include a monosilane (SiH ₄ ) gas diluted in helium (He) gas or hydrogen (H ₂ ) gas.

The chamber heating unit 12 may be formed of a resistance heating wire surrounding the outer circumferential surface of the chamber 10. The chamber heating unit 12 serves to deposit a silicon thin film on the substrate 20 by heating and pyrolyzing the silicon source gas injected into the chamber 10. During the deposition of the silicon thin film, the silicon source gas maintains a constant temperature.

The substrate support 14 is installed inside the chamber 10. The substrate support 14 may be formed in a box shape having a predetermined internal space, and an opening 142 having a smaller size than the substrate 20 may be formed on the upper surface 141. The substrate 20 is positioned on the top surface 141 of the substrate support 14 on which the opening 142 is formed. Accordingly, the edge of the substrate 20 may be supported by the substrate support 14, while the center portion of the substrate 20 may remain floating.

The substrate 20 is used to remove the surface foreign matter by the cleaning process, it may be made of any one of silicon, glass, quartz, alumina and plastic. Silicon, glass, quartz, alumina, and plastic have different heat resistance characteristics. In the low temperature high speed deposition apparatus 100 of a silicon thin film according to the first embodiment, various kinds of substrates 10 having different heat resistance characteristics are easily applied. can do.

The substrate cooling unit 16 is installed inside the substrate support 14 to contact the bottom surface of the substrate 20, and receives the cooling fluid from the outside of the chamber 10 to cool the substrate 20. The substrate 20 is cooled by a cooling fluid to form a large temperature gradient between the chamber 10 and the chamber 10. Both the substrate support 14 and the substrate cooling unit 16 are located at a distance from the inner wall of the chamber 10.

The substrate cooling unit 16 is located in the substrate support 14 and is in contact with the substrate 20 to receive and circulate the cooling fluid, and the circulation pipe 161, the circulation pipe 161 and the outside of the chamber 10 Connecting the first pipe part 162 for supplying the cooling fluid to the circulation pipe part 161, and connecting the circulation pipe part 161 to the outside of the chamber 10 to discharge the cooling fluid used for cooling to the outside of the chamber 10. The second pipe portion 163 may be included.

In this case, the second pipe part 163 may be formed to surround the first pipe part 162 and take the form of a double pipe together with the first pipe part 162. In this case, the second pipe part 163 may function as a protective tube to isolate the first pipe part 162 from the chamber 10, thereby minimizing heat loss of the cooling fluid supplied to the first pipe part 162. The configuration of the cooling unit 16 can be simplified.

The first pipe part 162 and the second pipe part 163 are connected to the cooler 22. The cooler 22 cools the cooling fluid discharged from the second pipe part 163 and supplies it to the first pipe part 162. Air or water may be used as the cooling fluid. 1 illustrates a case in which the circulation pipe part 161 is formed in a circular annular shape, but the configuration of the substrate cooling part 16 is not limited to the illustrated example and may be variously modified.

The controller 18 is connected to the chamber heating unit 12 and the substrate cooling unit 16 to control the temperature of the silicon source gas and the substrate 20, respectively. That is, the controller 18 controls the operation of the chamber heating unit 12 to control the temperature of the chamber 10 and the temperature of the silicon source gas injected into the chamber 10. In addition, the controller 18 is connected to the cooler 22 to control the temperature of the cooling fluid supplied to the circulation pipe 161. Therefore, it is possible to easily adjust the temperature difference between the silicon source gas and the cooling fluid.

As the substrate 20 is cooled by the substrate cooling unit 16, a large temperature gradient ΔT is formed between the chamber 10 and the substrate 20. The temperature gradient is proportional to the flow rate of the cooling fluid and the pressure of the silicon source gas.

3 is a cross-sectional view illustrating a substrate cooling unit in a low temperature high speed deposition apparatus of a silicon thin film according to a second exemplary embodiment of the present invention.

Referring to FIG. 3, the substrate cooling unit 16 ′ in the silicon low temperature high speed deposition apparatus according to the second embodiment has a protective tube unit surrounding the second tube unit 163 based on the structure of the first embodiment described above. 164 further. The protective tube 164 is not connected to the inside of the circulation tube 161 and is not connected to the cooler 22 (see FIG. 2). The protective tube portion 164 may maintain the interior thereof in a vacuum.

As such, by installing the vacuum protective tube portion 164 between the second tube portion 163 and the chamber 10, heat exchange between the heated silicon source gas and the first tube portion 162 may be prevented. Therefore, it is possible to effectively suppress the temperature of the substrate 20 rising in conjunction with the temperature inside the chamber 10.

Next, the deposition method of the silicon thin film using the low temperature high speed vapor deposition apparatus of the above-mentioned silicon thin film is demonstrated.

4 is a process flowchart showing a low temperature high speed deposition method of a silicon thin film according to an embodiment of the present invention.

Referring to FIG. 4, in the low-temperature high-speed deposition method of a silicon thin film according to an embodiment of the present invention, the first step (S10) of cleaning the substrate 20 to remove foreign substances on the surface of the substrate 20 and washed A second step (S20) of mounting the substrate 20 on the substrate cooling unit 16 in the chamber 10, and a third step of cooling the substrate 20 by supplying a cooling fluid to the substrate cooling unit 16. (S30) and driving the chamber heating unit 12 to heat the chamber 10 to form a temperature gradient between the substrate 20 and the chamber 10 (S40) and the chamber 10 inside A fifth step (S50) of depositing a silicon thin film on the substrate 20 by injecting a silicon source gas into the furnace and heating and pyrolyzing the silicon source gas.

In the first step S10, the cleaning of the substrate 20 is to remove foreign substances, particularly metal foreign substances, present on the surface of the substrate 20, and the substrate 20 is washed with acetone solution, methanol solution, and isopropyl alcohol solution, respectively. After cleaning for 1 minute or more, and washed with distilled water for 2 minutes or more to remove foreign substances on the surface of the substrate.

If the substrate is mounted in the chamber without undergoing the cleaning of the first step S10, the silicon thin film may not be uniformly formed by the foreign matter remaining on the surface of the substrate, in particular, the metal foreign matter, and an irregular structure such as silicon wire may be formed. Can be. Therefore, in order to form a high quality silicon thin film, the first step S10 of cleaning the substrate 20 must be performed.

The cooling fluid is continuously supplied in the fourth step S40 and the fifth step S50 so that the substrate 20 maintains a constant temperature. In the third step S30 to the fifth step S50, the temperature of the substrate 20 may be controlled by controlling the temperature and the flow rate of the cooling fluid using the controller 18. As the temperature of the cooling fluid is lower and the flow rate is larger, the temperature of the substrate 20 may be lowered, and the temperature gradient between the substrate 20 and the chamber 10 may be increased.

In this case, since the first pipe part 162 is surrounded by the second pipe part 163 or the second pipe part 163 and the protective pipe part 164 and thermally separated from the inside of the chamber 10, the heat loss of the cooling fluid is minimized. can do.

In a fifth step S50, the silicon source gas may be a monosilane (SiH ₄ ) gas diluted in helium (He) gas or hydrogen (H ₂ ) gas.

The silicon source gas injected into the chamber 10 at the beginning of the fifth step S50 is cold. The higher the pressure of the silicon source gas is, the greater the heat transfer effect between the substrate 20 and the silicon source gas is. Can lower the temperature. Accordingly, the temperature gradient between the substrate 20 and the chamber 10 may be increased by increasing the pressure of the silicon source gas at the beginning of the fifth step S50. The silicon source gas injected into the chamber 10 is slowly heated and pyrolyzed by the chamber heating unit 12.

The silicon source gas heated and pyrolyzed in the chamber 10 may be formed at a low temperature portion (substrate (substrate)) by a thermodynamic and hydrodynamic driving force along a temperature gradient formed between the substrate 20 and the chamber 10. 20)) while being rapidly moved to form a dense structure on the substrate 20, which is a low temperature portion, is deposited at high speed. Therefore, a high quality silicon thin film can be formed on the substrate 20 at high speed.

In a fifth step S50, the temperature difference between the substrate 20 and the silicon source gas may be 100 ° C. to 200 ° C., and the temperature of the substrate 20 may be 0 ° C. to 600 ° C. FIG.

If the temperature difference between the substrate 20 and the silicon source gas is less than 100 ° C., the temperature gradient between the substrate 20 and the chamber 10 is not sufficient, making it difficult to obtain a high speed deposition effect. On the other hand, when the temperature difference between the substrate 20 and the silicon source gas exceeds 200 ° C., the chamber 10 may be overheated or the silicon thin film may be excessively deposited, thereby decreasing the density and physical properties of the silicon thin film. In addition, since the pressure of the cooling fluid and the pressure of the silicon source gas become excessive, overall system stability may be lowered. The temperature difference between the substrate 20 and the silicon source gas may be set to 160 ° C.

If the temperature of the substrate 20 is less than 0 ° C, it is difficult to deposit a high quality silicon thin film. On the other hand, when the temperature of the substrate 20 exceeds 600 ° C., it is difficult to form a sufficient temperature gradient between the substrate 20 and the chamber 10, and may be used as the substrate 20 by increasing the temperature of the substrate 20. The material may be limited.

As described above, according to the present exemplary embodiment, when the silicon thin film is deposited by chemical vapor deposition (CVD), a large temperature gradient is formed between the substrate 20 and the chamber 10 as the substrate 20 is cooled. do. Therefore, a high quality silicon thin film can be deposited on a low temperature substrate 20 at high speed, and a substrate 20 having a very low heat resistance such as plastic can be easily applied, so that a silicon thin film can be deposited on a substrate 20 made of various materials. Can be formed.

FIG. 5 is a graph illustrating a result of measuring actual temperatures of a substrate by driving the silicon thin film deposition apparatus illustrated in FIG. 1.

For experiments, the substrate was cooled by supplying air at room temperature as a cooling fluid at a pressure of 80 psi to the substrate cooling unit. As shown in FIG. 5, the higher the temperature of the chamber, the higher the temperature of the substrate, but the substrate and the chamber maintain a temperature difference of approximately 160 ° C. as it is. In this case, a larger flow rate of air or cooling water may be used as the cooling fluid, or a higher pressure of the silicon source gas may further lower the temperature of the substrate. The result shown in FIG. 5 is the result measured at the chamber pressure of 50 Torr.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the embodiments described below are only preferred embodiments of the present invention and the present invention is not limited to the following embodiments.

(Example)

The pressure inside the chamber was adjusted to 50 Torr, and the substrate support and the substrate were cooled by injecting air at room temperature as a cooling fluid to the substrate cooling unit at a pressure of 80 psi. A 300 nm SiO ₂ / Si substrate was used as the substrate. While cooling the substrate, the chamber was heated at 50 ° C. intervals from 550 ° C. to 700 ° C. to form a temperature gradient between the substrate and the chamber. Then, a silicon thin film was deposited on the substrate while injecting monosilane gas diluted in helium gas into the chamber at 50 ml per minute (50 sccm).

(Comparative Example)

A silicon thin film was deposited on the substrate in the same manner as in Example except that the temperature gradient was not formed between the substrate and the chamber by adjusting the temperature of the chamber.

6 is a scanning electron micrograph of a silicon thin film formed on a substrate according to Examples and Comparative Examples.

6 (a) shows the silicon thin film of the embodiment deposited under a temperature gradient of 650 ° C. (chamber) / 490 ° C. (substrate). (b) shows the silicon thin film of Comparative Example deposited at 490 ° C. for both chamber and substrate without temperature gradient. (c) shows the silicon thin film of the Example deposited at the temperature gradient conditions of 700 ° C (chamber) / 555 ° C (substrate). (d) shows the silicon thin film of the comparative example deposited on both the chamber and the substrate at 555 ° C. without temperature gradient. In both the Examples and the Comparative Examples, the deposition time was 15 minutes.

Referring to FIG. 6, in the embodiments (a and c) deposited under a temperature gradient, a silicon thin film having a thickness of several to several tens of micrometers (3.22 μm to 89.1 μm) was formed. On the other hand, in the case of Comparative Examples (b and d) deposited in the absence of a temperature gradient for the same time, a thin silicon film of several hundred nanometers thick (272nm to 636nm) was formed.

In one embodiment a temperature gradient between the substrate and the chamber, from the results of the above example, the deposition rate of the silicon thin film can be confirmed that at least 10, up ^twice.

7 is a graph showing deposition rates of silicon thin films formed on substrates according to Examples and Comparative Examples.

In FIG. 7, A1, A2, and A3 are examples of an embodiment in which a silicon thin film is deposited under a temperature gradient of 650 ° C. (chamber) / 490 ° C. (substrate), and shows the thickness of the silicon thin film according to growth time. B1 and B2 are the case of the comparative example in which the silicon thin film was deposited at 490 ° C. in both the chamber and the substrate without a temperature gradient, and represents the thickness of the silicon thin film measured at a growth time of 11 minutes. At this time, B1 is a case where monosilane gas diluted in helium gas is used, and B2 is a case where monosilane gas diluted in hydrogen gas is used. The use of helium gas shows a faster deposition rate than the use of hydrogen gas under the same conditions.

As in the result of FIG. 6, in the example in which the temperature gradient is formed between the substrate and the chamber, the deposition rate of the silicon thin film increased by 10 ² times or more than the comparative example.

In addition, it can be seen from the results of B1 and B2 that the deposition rate of the monosilane gas diluted in helium gas was increased by about 10 times compared to the case of using monosilane gas diluted in hydrogen gas. Therefore, it can be seen that the deposition rate of the silicon thin film can be controlled not only by adjusting the temperature gradient but also by the type of the dilution gas.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

1 is a perspective view schematically showing a low temperature high speed deposition apparatus of a silicon thin film according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a substrate, a substrate support unit, and a substrate cooling unit in the low temperature high speed vapor deposition apparatus of the silicon thin film illustrated in FIG. 1.

3 is a cross-sectional view illustrating a substrate cooling unit in a low temperature high speed deposition apparatus of a silicon thin film according to a second exemplary embodiment of the present invention.

4 is a process flowchart showing a low temperature high speed deposition method of a silicon thin film according to an embodiment of the present invention.

FIG. 5 is a graph illustrating a result of measuring actual temperature of a substrate by driving a low temperature high speed deposition apparatus of the silicon thin film illustrated in FIG. 1.

6 is a scanning electron micrograph of a silicon thin film formed on a substrate according to Examples and Comparative Examples.

7 is a graph showing deposition rates of silicon thin films formed on substrates according to Examples and Comparative Examples.

Claims (12)

Cleaning the substrate to remove debris from the surface of the substrate; A substrate cooling part including a circulation pipe part and a first pipe part and a second pipe part inside the chamber; Mount the substrate inside the chamber to be in contact with the circulation conduit; Supplying a cooling fluid to the circulation tube to cool the substrate; Heating the chamber to form a temperature gradient between the substrate and the chamber; Depositing a silicon thin film on the substrate by injecting a silicon source gas into the chamber and heating and pyrolyzing the silicon source gas; The first pipe part connects the circulation pipe part and the outside of the chamber to supply a cooling fluid to the circulation pipe part, and the second pipe part surrounds the first pipe part and forms a double pipe together with the first pipe part and the circulation pipe part Low temperature high speed deposition method of the silicon thin film is connected to the outside of the chamber to discharge the cooling fluid used for cooling. delete The method of claim 1, A low temperature and high speed deposition method of a silicon thin film continuously supplying the cooling fluid to the circulation pipe even in the step of forming the temperature gradient and depositing the thin film. The method of claim 3, Low temperature and high speed deposition method of increasing the temperature gradient in proportion to the flow rate of the cooling fluid and the pressure of the silicon source gas. The method of claim 1, In the depositing the silicon thin film, the temperature difference between the substrate and the silicon source gas is a low temperature high-speed deposition method of the silicon thin film in the range of 100 ℃ to 200 ℃. The method of claim 5, In the depositing the silicon thin film, the temperature of the substrate is a low-temperature high-speed deposition method of the silicon thin film in the range of 0 ℃ to 600 ℃. The method of claim 1, The substrate is a low temperature high-speed deposition method of a silicon thin film made of any one of silicon, glass, quartz, alumina and plastic. The method according to any one of claims 1 and 3 to 7, And the silicon source gas comprises monosilane gas diluted with helium gas or hydrogen gas. A chamber supplied with a silicon source gas; A chamber heating unit installed in the chamber to heat the chamber; A substrate support unit mounted inside the chamber and supporting a substrate on which a silicon thin film is to be deposited; A circulation pipe portion installed in the substrate support portion to contact the substrate and cooling the substrate by circulation of a cooling fluid, and a first pipe portion connecting the circulation pipe portion and the outside of the chamber to supply the cooling fluid to the circulation pipe portion. And a second pipe part surrounding the first pipe part to form a double pipe together with the first pipe part and connecting the circulation pipe part to the outside of the chamber to discharge the cooling fluid used for cooling; And Control unit connected to the chamber heating unit and the substrate cooling unit to control the temperature of the chamber and the substrate, respectively Low temperature high speed deposition device of a silicon thin film comprising a. delete 10. The method of claim 9, The substrate cooling unit further comprises a protective tube unit surrounding the second tube unit and maintaining the inside in a vacuum. The method according to claim 9 or 11, The substrate support part forms an inner space for accommodating the circulation pipe part, and the low temperature and high speed deposition apparatus of the silicon thin film including an upper surface formed with an opening of a smaller size than the substrate.

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