JP2006295020A - Apparatus and method for forming oxide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for forming an oxide film wherein a high-quality oxide film can be formed and management is facilitated. <P>SOLUTION: A vaporizer 21 provided externally to a pressure-resistant container 13 generates water vapor, which is in turn supplied into warmed and pressurized the pressure-resistant container 13. Therefore, the atmosphere around a silicon wafer A is constant throughout all the steps of an oxide film formation process, and an oxide film formed over the silicon wafer A is of high quality. Since water is used, the management of a quantity consumed and safe management are facilitated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an oxide film forming apparatus and an oxide film forming method for forming an oxide film on the surface of a semiconductor substrate or the like.

  In the semiconductor substrate manufacturing process, for example, an oxide film is formed on the surface of a substrate material such as silicon by an oxide film forming apparatus. In the oxide film forming apparatus, the silicon wafer is accommodated in a pressure vessel, and the inside of the pressure vessel is set to a high pressure and high temperature such as 0.65 MPa and 950 ° C. in the case of a wet oxidation method. The silicon wafer reacts with water vapor in the pressure vessel in such a state. Thereby, an oxide film is formed on the surface of the silicon wafer.

FIG. 2 is a schematic diagram showing the configuration of an example of a conventional oxide film forming apparatus.
As shown in FIG. 2, the oxide film forming apparatus 200 includes a pressure vessel 203, and the pressure vessel 203 is covered with an outer shell portion 201 and a floor portion 202. A reaction chamber 201 a is formed inside the pressure vessel 203.
In this oxide film forming apparatus 200, the silicon wafer A is set in a plurality of evaporating dishes 205 a and 205 b containing pure water and accommodated in the pressure vessel 203. In addition, heater groups 204a, 204b, and 204c provided on the outer periphery of the pressure vessel 203 heat the reaction chamber 201a to a predetermined temperature, and a compressor (not shown) pressurizes the reaction chamber 201a to a predetermined pressure. As a result, pure water evaporates into water vapor, and this water vapor reacts with the silicon wafer A to form an oxide film on the surface of the silicon wafer A.

However, in the oxide film forming apparatus 200, pure water is vaporized from the initial stage when the reaction chamber 201a starts to be heated and pressurized, and an oxide film is formed on the silicon wafer A. Therefore, all steps for forming the oxide film are performed. Therefore, the atmosphere around the silicon wafer A is not constant. Further, since the evaporating dishes 205a and 205b are also heated at the same time, these materials may be ionized and dissolved in pure water. Therefore, it is difficult to form a high quality oxide film on the silicon wafer A.
Further, when exchanging the silicon wafer A, the pure water in the evaporating dishes 205a and 205b must be exchanged. However, as long as the temperature in the vicinity of the evaporating dishes 205a and 205b is not sufficiently lowered, this exchanging operation is not performed. Have difficulty. Therefore, the operating rate of the apparatus is reduced.

An example of an oxide film forming apparatus that solves the above-mentioned problems is disclosed in Patent Document 1.
FIG. 3 is a schematic view showing the configuration of such an oxide film forming apparatus 300.
As shown in FIG. 3, the oxide film forming apparatus 300 includes a pressure vessel 303, and this pressure vessel 303 is covered with an outer shell portion 301 and a side lid portion 302. A reaction chamber 301 a is formed inside the pressure vessel 303.
The oxide film forming apparatus 300 includes a gas control unit 306. The gas control unit 306 receives supply of hydrogen gas and oxygen gas from the hydrogen gas acquisition port 306b and the oxygen gas acquisition port 306c, respectively, and adjusts these gases at appropriate ratios, respectively, from the gas discharge port 306a. 301a.

In this oxide film forming apparatus 300, the silicon wafer A is set on a sample dish 305 provided in the reaction chamber 301a. Next, heater groups 304a and 304b provided outside the pressure vessel 303 heat the reaction chamber 301a to a predetermined temperature, and a compressor (not shown) pressurizes the reaction chamber 301a to a predetermined pressure.
Thereafter, hydrogen gas and oxygen gas are sent from the gas control unit 306 to the reaction chamber 301a, and the hydrogen gas and oxygen gas react in the reaction chamber 301a to generate water vapor. Thereby, the water vapor and the silicon wafer A react to form an oxide film on the surface of the silicon wafer A.

In this case, the amount of hydrogen gas and oxygen gas sent into the reaction chamber 301a is calculated based on a theoretical formula. However, it is difficult to manage the gas at the exact ratio as in theory. Moreover, since flammable gas is used, management in terms of safety becomes complicated. In addition, it is necessary to install an alarm or the like, and there is a problem that the apparatus becomes large.
JP-A-6-204210

  An object of the present invention is to provide an oxide film forming apparatus and an oxide film forming method capable of forming a high quality oxide film and easy to manage.

The present invention solves the above problems by the following means.
The invention of claim 1 is provided outside the pressure vessel, a pressure vessel that accommodates the object to be processed, a heating unit that heats the inside of the pressure vessel, a pressure unit that pressurizes the inside of the pressure vessel, and the pressure vessel. An oxide film forming apparatus comprising: a water vapor supply unit that vaporizes water to generate water vapor and supplies the water vapor into the pressure-resistant vessel; and a water supply unit that supplies water to the water vapor supply unit.
The invention of claim 2 accommodates an object to be processed in a pressure vessel, warms and pressurizes the inside of the pressure vessel, vaporizes water outside the pressure vessel, generates water vapor, It is an oxide film forming method in which an oxide film is formed on the surface of the object to be processed by supplying it into a pressure vessel and reacting the water vapor and the object to be processed.

As described above, the present invention has the following effects.
According to the first and second aspects of the present invention, since the water vapor is generated outside the pressure vessel and supplied into the heated and pressurized pressure vessel, the atmosphere around the object to be processed is oxidized. Constant throughout the film formation process. Therefore, the oxide film formed on the object to be processed is of high quality.
In addition, since the amount of water used is easily managed, the structure of the apparatus is simple. Furthermore, since it uses water without using flammable gas, it is easy to manage safety and is environmentally friendly. Further, compared with the case where gas is used, an alarm device or the like is unnecessary, so that the apparatus does not increase in size. Moreover, since the handling of water is easier than the handling of gas cylinders and the like, work is saved.

  The present invention provides an oxide film forming apparatus and an oxide film forming method that can form a high-quality oxide film and that are easy to manage by generating water vapor outside the pressure vessel and heating and heating the water vapor. This was realized by supplying the pressure vessel in a pressurized state.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a schematic diagram showing the configuration of an oxide film forming apparatus 100 according to an embodiment of the present invention.

The oxide film forming apparatus 100 includes an oxide film forming unit 10.
The oxide film forming unit 10 includes an outer shell 11, a floor 12, a pressure resistant container 13 including a reaction chamber 11 a, a quartz table 14, a plurality of heaters (heating units) 15 a and 15 b, and a compressor (pressurizing unit) 16. Etc.
The outer shell portion 11 is composed of a substantially cylindrical trunk portion whose axial direction is a substantially vertical direction, and a dome-shaped roof portion provided in the upper opening thereof. The floor portion 12 has a substantially circular plate shape, and is attached to the outer shell portion 11 so as to close the lower opening of the outer shell portion 11. The floor 12 has a substantially circular hole 12a at the center.

  The pressure vessel 13 is provided inside the outer shell portion 11 and the floor portion 12. The pressure vessel 13 is composed of a substantially cylindrical body portion that is substantially coaxial with the outer shell portion 11 and a dome-shaped roof portion provided in an upper opening thereof. The pressure vessel 13 has a pressure resistance performance of 1.5 MPa, for example. A reaction chamber 11 a is formed inside the pressure vessel 13.

The heaters 15 a and 15 b (hereinafter referred to as “heater group 15”) are disposed between the outer shell portion 11 and the pressure vessel 13 and surround the outer periphery of the body portion of the pressure vessel 13. These heater groups 15 can heat the temperature in the pressure vessel 13 to a high temperature of about 1000 ° C., for example. In the oxide film forming apparatus 100 of the present embodiment, the processing temperature range when forming the oxide film on the silicon wafer A is set to 700 to 950 ° C., for example.
The compressor 16 is provided outside the outer shell portion 11. The compressor 16 can pressurize the inside of the pressure vessel 13 through a pipe 16a. In addition, the compressor 16 of a present Example has the performance which can pressurize the inside of the pressure-resistant container 13 to 0.7 Mpa, for example.

  The quartz table 14 is provided inside the pressure vessel 13. The quartz table 14 includes a plurality of disk-shaped tables arranged in a hierarchy in the vertical direction, and is placed on a disk-shaped lifting table 17. The radial dimension of the lifting table 17 corresponds to the radial dimension of the hole 12 a of the floor 12. In the state where the quartz table 14 shown in FIG. 1 is set in the pressure resistant vessel 13, the hole 12a of the floor 12 is closed by the lifting table 17, and the reaction chamber 11a is sealed. The quartz table 14 of this embodiment corresponds to, for example, 6-inch and 8-inch silicon wafers A (objects to be processed), and the maximum number of processed sheets is, for example, 75 and 50, respectively. .

In addition, the oxide film forming apparatus 100 includes an elevating device 18 below the oxide film forming unit 10. The elevating device 18 is connected to the lower end surface of the elevating table 17, and when the quartz table 14 is set in the reaction chamber 11 a, the elevating table 17 on which the quartz table 14 is placed is placed from below the oxide film forming unit 10. It is designed to move.
The oxide film forming apparatus 100 has a silicon wafer transfer robot (not shown) outside the oxide film forming unit 10, and the silicon wafer transfer robot performs the work of setting the silicon wafer A on the quartz table 14. It has become.

Furthermore, the oxide film forming apparatus 100 includes a water vapor generating unit 20 outside the oxide film forming unit 10.
The steam generation unit 20 includes a vaporizer 21, a tank 22, a pure water supply unit 26, a pure water metering unit 31, a pressurization gas supply unit 23, a pressurization gas measurement unit 30, a carrier gas supply unit 24, and a heater 25. 27 etc.

The vaporizer 21 has a heater (not shown), and can vaporize water to generate water vapor. The vaporizer 21 and the reaction chamber 11a are connected by a water vapor supply pipe 21a, and the water vapor generated in the vaporizer 21 is supplied to the reaction chamber 11a through the water vapor supply pipe 21a. The water vapor supply pipe 21a connects the vaporizer 21 and the reaction chamber 11a within the shortest distance in the apparatus.
The tank 22 is provided in the vicinity of the vaporizer 21 and always stores pure water. This tank 22 has a pressure resistance equivalent to that of the pressure vessel 13. The tank 22 and the vaporizer 21 are connected by a pipe, and pure water is supplied from the tank 22 to the vaporizer 21 through this pipe.

  The pure water supply unit 26 is provided in the vicinity of the tank 22 and serves as a water source for supplying pure water to the tank 22. The pure water metering unit 31 is provided between the pure water supply unit 26 and the tank 22. The pure water measuring unit 31 has a weight sensor 22b. The weight sensor 22b includes, for example, a load cell, and can measure the weight of pure water in the tank 22. The pure water metering unit 31 has a CPU 28, and the weight sensor 22b emits a pure water amount measured to the CPU 28 as a signal. The pure water metering unit 31 has a valve 26 a in the middle of a pipe connecting the pure water supply unit 26 and the tank 22. The CPU 28 issues a signal to the valve 26a based on a signal from the weight sensor 22b, and operates the opening degree of the valve 26a.

The boosting gas supply unit 23 is provided in the vicinity of the tank 22. The boosting gas supply unit 23 supplies an inert gas such as nitrogen gas to the tank 22, for example. The discharge pressure of the inert gas is set higher than the pressure in the pressure resistant vessel 13 when the oxide film is generated.
The boosting gas measuring unit 30 is provided between the boosting gas supply unit 23 and the tank 22. The pressurization gas measurement unit 30 includes a pressure sensor 22a. The pressure sensor 22a can measure the pressure in the tank 22. The pressure-increasing gas measuring section 30 has a CPU 29, and the pressure sensor 22a emits the tank internal pressure measured with respect to the CPU 29 as a signal. Further, the pressurization gas measuring unit 30 has a valve 23 a in the middle of a pipe connecting the pressurization gas supply unit 23 and the tank 22. The CPU 29 issues a signal to the valve 23a based on a signal from the pressure sensor 22a, and operates the opening degree of the valve 23a.

The carrier gas supply unit 24 is provided in the vicinity of the vaporizer 21, and is connected to the vaporizer 21 via a pipe. The carrier gas supply unit 24 supplies, for example, an inert gas such as nitrogen gas to the vaporizer 21. The discharge pressure of this inert gas is also set higher than the pressure in the pressure vessel 13 when the oxide film is generated.
The heater 27 is provided for the water vapor supply pipe 21a. The heater 25 is provided for the carrier gas supply unit 24. These heaters 27 and 25 heat the water vapor generated by the vaporizer 21 and the carrier gas at a temperature equal to or higher than the boiling point of water vapor that is higher than the normal boiling point (100 ° C.) by being pressurized. It is like that.

Next, the operation of the oxide film forming apparatus 100 according to the present embodiment will be described including an oxide film forming method.
When the oxide film forming apparatus 100 forms an oxide film on the silicon wafer A, the silicon wafer A is placed at a predetermined position on the quartz table 14 by the silicon wafer transfer robot outside the oxide film forming unit. Thereafter, the quartz table 14 is set in the reaction chamber 11 a by the lifting device 18. At this time, the hole 12a of the floor 12 is closed by the lifting table 17, and the reaction chamber 11a is sealed. Next, the heater group 15 heats the temperature of the reaction chamber 11a to, for example, 950 ° C., and the compressor 16 pressurizes the pressure of the reaction chamber 11a to, for example, 0.65 MPa.

Next, the water vapor generation unit 20 generates an appropriate amount of water vapor according to the type and number of silicon wafers A to be processed.
When water vapor is generated, pure water is supplied from the pure water supply unit 26 into the tank 22, and at the same time, a pressure-increasing gas is supplied from the pressure-increasing gas supply unit 23 to the tank 22.

  Here, when determining the amount of pure water, the weight sensor 22 b measures the weight of pure water in the tank 22. Note that pure water is always stored in the tank 22, and the weight sensor 22 b measures the amount of change of the pure water and sends a signal to the CPU 28. Based on this signal, the CPU 28 transmits a signal to the valve 26a and operates the opening of the valve 26a to adjust the flow rate of pure water. Thereby, an appropriate amount of pure water supplied to the tank 22 is automatically determined.

Further, when determining the amount of the boosting gas, the pressure sensor 22 a measures the pressure in the tank 22 and sends a signal to the CPU 29. Based on this signal, the CPU 29 transmits a signal to the valve 23a and operates the opening of the valve 23a to adjust the discharge amount of the boosting gas. As a result, the appropriate pressure of the boosting gas supplied to the tank 22 is automatically controlled.
The pure water whose amount and pressure are controlled is sent from the tank 22 to the vaporizer by the pressure-increasing gas and is vaporized by the vaporizer 21. Thereby, an appropriate amount of water vapor is generated.

  The water vapor is sent into the reaction chamber 11a by the pressurizing gas and the carrier gas. At this time, since the discharge pressure of the pressurizing gas and the carrier gas is higher than the pressure in the reaction chamber 11a, the pressure in the water vapor supply pipe 21a is higher than the pressure in the reaction chamber 11a. Therefore, the water vapor does not flow back to the vaporizer 21. Further, since the heater 25 heats the carrier gas supply unit 24 and the heater 27 heats the water vapor supply pipe 21a to a temperature equal to or higher than the boiling point of water vapor, the water vapor does not condense.

  The silicon wafer A in the reaction chamber 11a reacts with water vapor sent into the reaction chamber 11a for a predetermined reaction time. As a result, an oxide film is formed on the surface of the silicon wafer A. After the formation of the oxide film is completed, the quartz table 14 (silicon wafer A) is taken out from the reaction chamber 11a by the lifting device 18. Thus, the oxide film formation process is completed. For example, when the 1 μm oxide film is formed on the silicon wafer A, the processing time is 6 hours.

As described above, according to the oxide film forming apparatus 100 and the oxide film forming method of this embodiment, the water vapor is generated outside the pressure vessel 13 and supplied to the reaction chamber 11a in a heated and pressurized state. Therefore, the atmosphere around the silicon wafer A is constant throughout the entire oxide film formation process. Therefore, the oxide film formed on the silicon wafer A is of high quality.
Further, since the oxide film forming apparatus 100 uses pure water without using a combustible gas, it is easy to manage safety. Furthermore, since pure water can be easily measured, the structure of the apparatus is also simple. Moreover, since pure water is widely used in semiconductor factories, it is easy to obtain and environmentally friendly. Further, compared with the case where flammable gas is prepared, an alarm device or the like is not required, so that the apparatus is not enlarged. Furthermore, since pure water is easier to handle than gas cylinders and the like, work is saved.

  In this embodiment, the object to be processed is the silicon wafer A, but the object to be processed is not limited to this. Therefore, for example, the object to be processed may be a compound semiconductor such as silicon carbide. In addition, the object to be processed may be a liquid crystal substrate or a substrate for organic EL.

In the oxide film forming apparatus 100 of the present embodiment, the pressure vessel 13 is a so-called “vertical” pressure vessel whose axial direction is the vertical direction, but the configuration of the pressure vessel is not limited thereto. It may be a so-called “lateral” pressure vessel in which the axial direction is a horizontal direction.
Further, the pressurization gas and the carrier gas in this example were both nitrogen gas, but the pressurization gas and the carrier gas are not limited to these, and are flame retardant and easy to manage, and the formation of an oxide film Other types of gases may be used as long as they are not affected.

It is a schematic block diagram which shows the oxide film forming apparatus which concerns on the Example of this invention. It is a schematic block diagram which shows an example of the conventional oxide film formation apparatus. It is a schematic block diagram which shows the other example of the conventional oxide film forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Oxide film formation apparatus 13 Pressure | voltage resistant container 15a, 15b Heater 16 Compressor 21 Vaporizer 22 Tank 23 Gas supply part 25 for pressurization 25 Carrier gas supply part 26 Pure water supply part A Silicon wafer

Claims (2)

A pressure-resistant container that accommodates an object to be processed;
A heating unit for heating the inside of the pressure vessel,
A pressurizing unit for pressurizing the inside of the pressure vessel;
A water vapor supply unit that is provided outside the pressure vessel, vaporizes water to generate water vapor, and supplies the water vapor into the pressure vessel;
A water supply unit for supplying water to the water vapor supply unit;
An oxide film forming apparatus comprising: House the object to be processed in a pressure vessel,
Heating and pressurizing the inside of the pressure vessel,
Vaporizing water outside the pressure vessel to produce water vapor;
Supplying the water vapor into the pressure vessel,
An oxide film forming method for reacting the water vapor and the object to be processed to form an oxide film on a surface of the object to be processed.

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