JP2013227613A - Gas introducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas introducing device capable of introducing a prescribed source gas surely and as promptly as possible with the number of moles thereof fixed, regardless of vapor pressure of the source gas.SOLUTION: A gas introducing device includes: a single first buffer chamber 33b connected to an upstream side gas introducing pipe 32b extended from a gas supply source 31b; a plurality of second buffer chambers 33c connected to the first buffer chamber in series and having the same prescribed volume smaller than that of the first buffer chamber; and a downstream side gas introducing pipe 34b for introducing a source gas from a chamber selected from the first buffer chamber and the respective second buffer chambers to a treatment chamber. The volume of the second buffer chamber on the most upstream side including a connecting pipe 35a connecting the first buffer chamber and the second buffer chamber positioned on the most upstream side, and the volume of the second buffer chamber on the downstream side including a connecting pipe 35b connecting the second buffer chamber positioned on the upstream side and the second buffer chamber positioned on the downstream side, that are continued to each other, are made equal.

Description

  The present invention relates to a gas introduction device for introducing a predetermined source gas into a processing chamber with a constant number of moles thereof.

  In recent years, a self-assembled monomolecular film (hereinafter referred to as “SAM”) in which raw material molecules are assembled and autonomously assembled on the surface of a substrate to be processed such as a silicon wafer has attracted attention. The SAM has, for example, a functional group chemically adsorbed on the substrate to be processed and a terminal functional group opposite to the functional group on a core atom such as silicon or titanium, and by appropriately selecting the terminal functional group. It is possible to control the physical or chemical properties of the surface, and it is widely used in the manufacturing process of electronic devices such as transistors, MEMS and image display devices.

  Conventionally, a method and an apparatus for forming a SAM having a high film density and high orientation by a vapor phase method are known, for example, from Patent Document 1. In this apparatus, a processing chamber (deposition chamber) capable of forming a film, an atmospheric temperature control means for controlling the temperature in the processing chamber, a humidity control means for controlling the humidity in the processing chamber, and a stage disposed in the processing chamber Substrate temperature adjusting means for controlling the temperature of the substrate to be processed set on the substrate. Connected to the ceiling of the processing chamber are a gas introduction pipe of a gas introduction device that supplies the source gas into the processing chamber and an exhaust pipe of a gas exhaust device that exhausts the gas in the processing chamber. Then, the gas introducing apparatus introduces a source gas for SAM formation (including a mixed gas with a carrier gas) into the processing chamber into the processing chamber in which the humidity and temperature are appropriately controlled to form a film. In this case, the humidity is adjusted by mixing the main gas such as nitrogen with a water vapor gas and introducing it into the processing chamber.

  Here, when introducing the raw material gas into the processing chamber, it is desirable to improve the utilization efficiency of the raw material gas for forming the SAM by introducing only a predetermined amount of the raw material gas essential for film formation. In such a case, a buffer chamber having a predetermined volume is provided in a source gas introduction pipe that leads from the gas supply source containing the raw material in a solid phase or a liquid phase to the processing chamber, and upstream and downstream of the buffer chamber. An open / close valve is provided in each of the introduction pipe portions. Then, the raw material of the gas supply source is gasified, the upstream on-off valve is opened, a predetermined amount of source gas is temporarily stored in the buffer chamber, and the downstream on-off valve is opened when performing film formation. Only the source gas in the buffer chamber is introduced into the processing chamber.

  However, in the method of introducing the source gas as described above, when the vapor pressure of the source gas is high, the source gas is introduced into the buffer chamber by adjusting the pressure of the source gas introduced into the buffer chamber to a predetermined pressure lower than the vapor pressure each time. There is a problem that it is difficult to introduce. When the pressure of the source gas is different, the number of moles of the source gas introduced into the processing chamber is not constant, and there is a problem that the SAM film quality (density and orientation) is not constant for each substrate to be processed. In this case, a part for controlling the gas flow rate such as an orifice is provided in the introduction pipe that leads to the buffer chamber, and the on-off valve is controlled while the pressure in the buffer chamber is monitored with a pressure gauge to introduce the source gas into the buffer chamber. In this case, there is a problem that the introduction of the source gas into the buffer chamber is troublesome and the introduction of the source gas takes time.

International Publication No. 2006/112408

  In view of the above, the present invention provides a gas introduction device capable of reliably and promptly introducing a predetermined source gas with a constant number of moles irrespective of the vapor pressure of the source gas. Is the issue.

  In order to solve the above problems, a gas introduction apparatus of the present invention for introducing a predetermined source gas into a processing chamber with a constant number of moles is a single gas source connected to an upstream gas introduction pipe from a gas supply source. A first buffer chamber, a plurality of second buffer chambers connected in series to the first buffer chamber and having the same predetermined volume smaller than the first buffer chamber, and a selection among the first buffer chamber and each second buffer chamber And a downstream gas introduction pipe for introducing the raw material gas into the processing chamber from the generated gas, and the uppermost stream side including the connection pipe connecting the first buffer chamber to the second buffer chamber located on the uppermost stream side. The volume of the second buffer chamber including the connection pipe connecting the volume of the second buffer chamber and the second buffer chamber located upstream to the second buffer chamber located downstream is continuous. Is characterized by equality To.

  According to the present invention, the source gas gasified by the gas supply source is first introduced into the first buffer chamber while maintaining its vapor pressure. Next, the source gas once stored in the first buffer chamber is transferred to the second buffer chamber. At this time, the volume of the second buffer chamber on the uppermost stream side including the connection pipe connecting the first buffer chamber to the second buffer chamber located on the uppermost stream side is continuous with the first upstream buffer located on the upstream side. Since the volume of the second buffer chamber on the downstream side including the connecting pipe connecting the second buffer chamber to the second buffer chamber located on the downstream side is made equal, the source gas is transferred from the first buffer chamber to each second buffer chamber. Are equally divided so that the pressures in the first buffer chamber and the second buffer chambers are equal to each other, and the number of moles of the source gas is also equal. That is, the pressure in the first buffer chamber and each second buffer chamber is a pressure obtained by dividing the vapor pressure of the source gas by the sum of the first buffer chamber and each second buffer chamber. In this case, the number and volume of the second buffer chambers are appropriately set according to the pressure of the source gas when introduced into the processing chamber. Then, the source gas is sequentially supplied from the selected one of the first buffer chamber and each of the second buffer chambers to, for example, the film forming chamber that is evacuated to perform film formation.

  As described above, in the present invention, since the raw material gas is introduced into the first buffer chamber while maintaining its vapor pressure, only the partial pressure is divided into the second buffer chamber, so that only the on-off valve can be used as quickly as possible without complicated control. It can be realized that the raw material gas can be introduced into the processing chamber with a constant number of moles only by opening and closing. Note that the “equivalent” in the present invention does not mean only when the source gases are evenly divided as long as the source gas is equally divided into the first buffer chamber and each second buffer chamber. .

  In the present invention, a branch pipe is connected to the downstream gas introduction pipe leading from the first buffer chamber to the processing chamber via an on-off valve, and a third buffer chamber having a variable volume can be connected to the branch pipe. For example, the pressure of the source gas introduced into the first and second buffer chambers may be appropriately changed according to the volume of the third buffer chamber. In this case, for example, an evacuation device may be connected to the third buffer chamber, and after the source gas is divided, the inside thereof may be appropriately evacuated. An introduction pipe may be connected to introduce the source gas in the third buffer chamber into the processing chamber.

The schematic diagram of the film-forming apparatus provided with the gas introduction apparatus of embodiment of this invention.

  Hereinafter, with reference to the drawings, an embodiment in which a gas introduction apparatus of the present invention is applied to a film forming apparatus that forms a self-assembled monolayer (SAM) on a silicon substrate W as a substrate to be processed will be described. explain.

Referring to FIG. 1, reference numeral 1 denotes a vacuum chamber that defines a processing chamber 1a in which film formation is performed. In the following, with reference to FIG. 1, the side in which the stage 2 is provided in the vacuum chamber 1 will be the bottom, and terms indicating the direction such as top, right, and left will be used. However, the arrangement is not limited to this. Absent. The vacuum chamber 1 is provided with a vacuum pump P for evacuating the inside, and a stage 2 on which the silicon substrate W is positioned and held is provided at the center of the lower surface. The stage 2 incorporates a heater and a cooling unit (not shown) so that the silicon substrate W set on the stage 2 can be controlled to a predetermined temperature. The vacuum chamber 1 is also provided with a heater (not shown) so that the atmospheric temperature in the processing chamber 1a can be controlled during film formation. The first and second gas introduction devices 3 ₁ and 3 ₂ are provided on the upper wall portion of the vacuum chamber 1 so as to face the stage ₂ .

The first gas introduction device 3 ₁ is intended to introduce the raw material gas for SAM formation, the second gas introducing device 3 _2, the steam gas in order to adjust the processing chamber 1a to the predetermined humidity at the time of film formation It is to be introduced. The source gas for SAM formation is appropriately selected depending on what is going to be formed on the silicon substrate W in order to control the physical or chemical properties of the surface. Since it can be used, it is omitted here. Here, when a compound having a core atom of silicon is used as the source gas, the vapor pressure is not so high. Therefore, the first gas introduction device 3 _1, raw materials are stored in liquid phase, a gas supply source 31a having a heater (not shown) for gasifying the raw material, the upstream side gas from the gas supply source 31a A single buffer chamber 33a to which the introduction pipe 32a is connected, and a downstream side gas introduction pipe 34a for introducing the raw material gas from the buffer chamber 33a into the processing chamber 1a, and the upstream side gas introduction pipe 32a and the downstream side gas introduction. On-off valves V1 and V2 are respectively provided in the pipes 34a. In this case, the volume of the buffer chamber 33a is appropriately set according to the amount of source gas essential for film formation.

On the other hand, water vapor gas, high vapor pressure as compared to the raw material gas, the first gas introduction device 3 _1, such as configuration, the pressure of the steam gas arranged in a predetermined pressure lower than the vapor pressure, moles of the raw material gas It is difficult to introduce the raw material gas into the buffer chamber with a constant number. Therefore, in this embodiment, it was decided to constitute a second gas introduction device 3 ₂ as follows. That is, the second gas introducing device 3 _2, raw materials (H 2 _O) stored in the liquid phase, the raw material gas supply source 31b having a heater (not shown) for gasification, the gas supply source 31b A single first buffer chamber 33b to which the upstream gas introduction pipe 32b is connected, and a downstream gas introduction pipe 34b for introducing the raw material gas from the first buffer chamber 33b into the processing chamber 1a. A plurality of second buffer chambers 33c having the same predetermined volume smaller than the first buffer chamber 33b are connected in series to the first buffer chamber 33b via connection pipes 35a to 35d branched from the downstream gas introduction pipe 34b. It is connected to the. In this case, the number of second buffer chambers 33c is appropriately selected in consideration of the vapor pressure of the source gas, the pressure of the source gas when introduced into the processing chamber 1a, and the like. Further, the pipe diameter and length of the connecting pipe 35a between the first buffer chamber 33b and the second buffer chamber 33c located on the most upstream side, and the connecting pipes 35b to 35b connecting the second buffer chambers 33c to each other. The pipe diameter and length of 35d are the same. Each of the second buffer chambers 33c is connected to another downstream gas introduction pipe 34c for introducing the raw material gas once stored therein into the processing chamber 1a. Further, the upstream side gas introduction pipe 32b, the connection pipes 35a to 35d, and the downstream side gas introduction pipes 34b and 34c are respectively provided with on-off valves V3, V4 and V5 having the same configuration. In the downstream gas introduction pipe 34b, the length from the first buffer chamber 33b to the on-off valve V4 is preferably equal to the length of the connection pipe 35a.

  Further, a branch pipe 36 is connected to the downstream side gas introduction pipe 34b leading from the first buffer chamber 33b to the processing chamber 1a via an on-off valve V6, and the third buffer chamber 33d having a variable volume is connected to the branch pipe 36. Is connected. In this case, the third buffer chamber 33d has a smaller volume than the first buffer chamber 33b, and a piston PS is provided therein, and a direct acting motor PM for driving the piston PS is additionally provided, and the third buffer chamber 33d is provided. The relative position of the piston PS in the chamber 33d is appropriately controlled so that the internal volume can be varied. The form of the third buffer chamber 33d is not limited to this, and for example, a bellows may be used.

  As described above, according to the above-described embodiment, only the on-off valve V3 is opened and the source gas gasified by the gas supply source 31b is first introduced into the first buffer chamber 33b with the vapor pressure thereof. Next, after closing the on-off valve V3, all the on-off valves V5 are opened, and the raw material gas once stored in the first buffer chamber 33b is transferred to the second buffer chamber 33c. At this time, the pipe diameter and the length of the connecting pipe 35a are aligned, and the second upstream-side second pipe including the connecting pipe 35a connecting the first buffer chamber 33b to the second buffer chamber 33c located on the uppermost-stream side is included. The second downstream side including the volume of the buffer chamber 33c and the connecting pipes 35b to 35d connecting the second buffer chamber 33c located upstream and the second buffer chamber 33c located downstream are continuous with each other. Since the volumes of the buffer chambers 33c are made equal, the source gas is equally divided from the first buffer chambers 33b to the second buffer chambers 33c, and the pressures in the first buffer chambers 33b and the second buffer chambers 33c are changed. They are equivalent to each other, and the number of moles of the source gas is also equivalent. That is, the pressure in the first buffer chamber 33b and each second buffer chamber 33c is a pressure obtained by dividing the vapor pressure of the source gas by the number of the first buffer chamber 33b and each second buffer chamber 33c added. Then, by sequentially opening and closing the on-off valve V4 with the on-off valve V5 closed, the processing chamber 1a evacuated from the selected one of the first buffer chamber 33b and each of the second buffer chambers 33c. The raw material gas is sequentially supplied to. Finally, when all of the source gases in the first buffer chamber 33b and the second buffer chambers 33c are introduced into the processing chamber 1a, the above operation is repeated, and the first buffer chamber 33b and the second buffer chambers 33c are again supplied. Source gas is supplied.

  As described above, in the present invention, since the raw material gas is introduced into the first buffer chamber 33b while maintaining its vapor pressure, the pressure is only divided into the second buffer chamber 33c. It can be realized that the raw material gas can be introduced into the processing chamber 1a with a constant number of moles by only opening and closing V3 to V5. Further, the pressure of the source gas introduced into the first and second buffer chambers 33b and 33c may be appropriately changed according to the volume of the third buffer chamber 33d. In this case, a vacuum pump (not shown) may be connected to the third buffer chamber 33d, and after the source gas is divided, the inside may be appropriately evacuated.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said thing. In the above embodiment, the case where the water vapor gas is introduced into the processing chamber with a constant number of moles has been described as an example, but the vapor pressure of the raw material gas is high, and the pressure is made constant in the buffer chamber as quickly as possible. The present invention can be applied when it cannot be introduced into the buffer chamber. Moreover, in the said embodiment, although the volume in the 2nd buffer chamber 33c and the pipe diameter and length of the connecting pipes 35a-35d were arrange | positioned and demonstrated as an example, this invention is limited to the above. Is not to be done. For example, by increasing the volume in the second buffer chamber 33c and the pipe diameter of the connecting pipe 35a toward the downstream side, and shortening the length of the connecting pipes 35a to 35d toward the downstream side, You may make it aim at size reduction of a gas introduction apparatus. Furthermore, in the above-described embodiment, the case where the SAM is formed by the vapor phase method has been described as an example. However, in another film forming apparatus or an etching apparatus, the gas is introduced at a constant pressure and thus the number of moles is constant. The present invention can be widely applied when necessary.

DESCRIPTION OF SYMBOLS 1 ... Vacuum chamber, 1a ... Processing chamber, 3 ₂ ... Gas introduction apparatus, 33b ... 1st buffer chamber, 33c ... 2nd buffer chamber, 33d ... 3rd buffer chamber, 31b ... Gas supply source, 32b ... Upstream side gas introduction Pipe, 34b ... downstream gas introduction pipe, 35a-35d ... connection pipe, 36 ... branch pipe, V1-V5 ... open / close valve, W ... silicon substrate (substrate to be processed).

Claims (2)

A gas introduction device for introducing a predetermined source gas into a processing chamber with a constant number of moles thereof,
A single first buffer chamber connected to the upstream gas introduction pipe from the gas supply source, and a plurality of second buffer chambers connected in series to the first buffer chamber and having the same predetermined volume smaller than the first buffer chamber A buffer chamber, and a downstream gas introduction pipe for introducing a source gas into the processing chamber from a selected one of the first buffer chamber and each second buffer chamber,
The volume of the second buffer chamber on the most upstream side including the connecting pipe connecting the first buffer chamber to the second buffer chamber located on the most upstream side, and the second buffer chamber located on the upstream side that are continuous with each other. A gas introducing device characterized in that the volume of the second buffer chamber on the downstream side including the connecting pipe connecting the first buffer chamber to the second buffer chamber located on the downstream side is made equal. A branch pipe is connected to a downstream side gas introduction pipe leading from the first buffer chamber to the processing chamber via an on-off valve, and a third buffer chamber having a variable volume is connected to the branch pipe. Item 2. The gas introduction device according to Item 1.

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