阅读说明：本技术 衬底处理装置、石英反应管、清洁方法以及程序
(Substrate processing apparatus, quartz reaction tube, cleaning method, and program
) 是由 冈嶋优作
佐佐木隆史
吉田秀成
西堂周平
石坂光范
三村英俊 于 2017-09-25 设计创作，主要内容包括：本发明公开了使用排气性经改善后的双重管反应管的衬底处理装置。反应管具有：排气端口,其与外管和内管之间的排气空间连通；第1排气口(4E),其设置于内管,将处理气体排出；多个第2排气口(4H、4J),其使排气空间与歧管的内侧的空间连通；以及多个第3排气口(4G),其在与隔热组件相对的部位的内管开口。第2排气口促进在距第1排气口远的排气空间中滞留的气体的排气。(The invention discloses a substrate processing apparatus using a dual tube reaction tube with improved exhaust performance. The reaction tube has: an exhaust port communicating with an exhaust space between the outer pipe and the inner pipe; a 1 st exhaust port (4E) provided in the inner tube and configured to exhaust the process gas; a plurality of 2 nd exhaust ports (4H, 4J) which communicate the exhaust space with the space inside the manifold; and a plurality of No. 3 exhaust ports (4G) which open to the inner pipe at a position opposite to the heat insulating module. The 2 nd exhaust port promotes the exhaust of the gas that stagnates in the exhaust space that is far from the 1 st exhaust port.)
1. A substrate processing apparatus includes:
a reaction tube having an outer tube and an inner tube, one ends of the outer tube and the inner tube being respectively closed;
a cylindrical manifold connected to an open end side of the reaction tube;
a sealing cap blocking an end of the manifold opposite to an end connected to the reaction tube;
a rotating mechanism which penetrates the sealing cover and transmits rotation; and
a gas supply pipe for supplying purge gas for purging the inner space of the manifold,
the reaction tube has: an exhaust port communicating with an exhaust space between the outer pipe and the inner pipe; a 1 st exhaust port provided in the inner tube and configured to exhaust the process gas; and a plurality of 2 nd exhaust ports that communicate the exhaust space with the space inside the manifold, at least one of the 2 nd exhaust ports promoting exhaust of gas that is retained in the exhaust space that is distant from the 1 st exhaust port.
2. The substrate processing apparatus of claim 1,
the substrate processing apparatus further includes:
a substrate holder that is rotated by the rotating mechanism;
a cylindrically shaped heat shield assembly that insulates between the substrate holder and the sealing lid; and
a plurality of No. 3 exhaust ports provided to open at the inner pipe at a portion opposite to the heat insulating module,
the 3 rd exhaust port inhibits purge gas from the gas supply tube from passing through a side of the thermal shield assembly to the substrate holder.
3. The substrate processing apparatus of claim 2, wherein,
the substrate processing apparatus further includes:
a nozzle which is provided between the outer pipe and the inner pipe and faces the 1 st exhaust port, and which supplies a process gas into the inner pipe; and
a nozzle chamber maintaining communication with the inside of the inner tube and surrounding a periphery of the nozzle.
4. The substrate processing apparatus of claim 3, wherein,
the conductance of the path of the purge gas entering the exhaust space from the 2 nd exhaust port and being exhausted is set to be larger than the conductance of the path of the purge gas entering the exhaust space from the 1 st exhaust port and being exhausted through the side face or nozzle chamber of the heat insulating assembly,
the size of the 2 nd exhaust port and the flow rate of the purge gas are set so that the concentration of the process gas intruding into the space inside the manifold becomes equal to or lower than a predetermined value.
5. A method for cleaning a substrate processing apparatus,
the substrate processing apparatus includes:
a reaction tube having an outer tube and an inner tube, one ends of the outer tube and the inner tube being respectively closed;
a cylindrical manifold connected to an open end side of the reaction tube;
a sealing cap blocking an end of the manifold opposite to an end connected to the reaction tube;
a rotating mechanism which penetrates the sealing cover and transmits rotation; and
a gas supply pipe for supplying purge gas for purging the inner space of the manifold,
the reaction tube has: an exhaust port communicating with an exhaust space between the outer pipe and the inner pipe; a 1 st exhaust port provided in the inner tube and configured to exhaust the process gas; and a plurality of 2 nd exhaust ports communicating the exhaust space with an inner space of the manifold,
the cleaning method comprises the following steps:
supplying a cleaning gas from a nozzle into the reaction tube; and
repeating a cycle comprising the following sub-steps of: a sub-step of raising the pressure in the processing chamber by supplying a purge gas into the reaction tube; and a sub-step of depressurizing the inside of the processing chamber by vacuum-exhausting the inside of the processing chamber.
6. A program for causing a computer for controlling a substrate processing apparatus to execute a process,
the substrate processing apparatus includes:
a reaction tube having an outer tube and an inner tube, one ends of the outer tube and the inner tube being respectively closed;
a cylindrical manifold connected to an open end side of the reaction tube;
a sealing cap blocking an end of the manifold opposite to an end connected to the reaction tube;
a rotating mechanism which penetrates the sealing cover and transmits rotation; and
a gas supply pipe for supplying purge gas for purging the inner space of the manifold,
the reaction tube has: an exhaust port communicating with an exhaust space between the outer pipe and the inner pipe; a 1 st exhaust port provided in the inner tube and configured to exhaust the process gas; and a plurality of 2 nd exhaust ports communicating the exhaust space with an inner space of the manifold,
the treatment comprises the following steps:
supplying a cleaning gas from a nozzle into the reaction tube; and
a step of purging while changing the pressure in the reaction tube by repeating a cycle including a sub-step of: a sub-step of raising the pressure in the processing chamber by alternately supplying a purge gas from the nozzle and the gas supply pipe; and a sub-step of depressurizing the inside of the processing chamber by vacuum-exhausting the inside of the processing chamber.
7. A quartz reaction tube comprising:
the outer pipe and the inner pipe are respectively closed at one end;
a flange connecting the other ends of the outer pipe and the inner pipe;
an exhaust port communicating with an exhaust space between the outer pipe and the inner pipe;
a 1 st exhaust port provided in the inner tube and configured to exhaust the process gas;
a supply slit for supplying a process gas into the inner tube at a position between the outer tube and the inner tube and opposite to the 1 st exhaust port;
a plurality of 2 nd exhaust ports provided at the flange to communicate the inside with the outside of the exhaust space; and
a plurality of No. 3 exhaust ports opened to the inner pipe at positions opposite to an insulation assembly provided in the inner pipe at positions close to the flanges,
at least one of the 2 nd exhaust ports is disposed at a position promoting exhaust of gas stagnating in an exhaust space distant from the 1 st exhaust port.
Technical Field
The invention relates to a substrate processing apparatus, a quartz reaction tube, a cleaning method and a program.
Background
For example, a vertical substrate processing apparatus is used for heat treatment of a substrate (wafer) in a manufacturing process of a semiconductor Device (Device). In a vertical substrate processing apparatus, a plurality of substrates are held by a substrate holder so as to be aligned in a vertical direction, and the substrate holder is carried into a processing chamber. Then, a process gas is introduced into the processing chamber in a state where the substrate is heated by a heater provided outside the processing chamber, and a thin film forming process or the like is performed on the substrate. Before the film adhering to the inside of the processing chamber is peeled off, dry cleaning or the like is performed to remove the film. Conventionally, a technique of performing cleaning in a vertical substrate processing apparatus using a double tube is known (for example, see patent documents 1 and 2). In addition, in order to improve exhaust, a technique of providing an opening in a part of a reaction tube or the like is known (for example, see patent documents 3 and 5).
Disclosure of Invention
Problems to be solved by the invention
In cleaning a process chamber, various kinds of gases and temperature conditions are applied according to the kind of a film in order to effectively remove the target film while suppressing damage to the process chamber and the like. For example, there is a method of repeating the following process: after the film is exposed to a 1 st gas for modification (oxidation) in order to easily remove the film, it is exposed to a 2 nd gas for removing the modified film. In addition, in the case where the by-products and the like accompanying the removal reaction are substances that corrode the processing chamber, purging by an inert gas may be used to rapidly discharge these substances.
However, when the quartz reaction tube has a double structure, gas tends to be trapped in the gap between the outer tube and the inner tube. In such a portion, the supply of the cleaning gas is small and the exhaust is slow. As a result, there is a problem that cleaning becomes incomplete or the time required for cleaning is prolonged. In addition, the double tube structure contributes to facilitating the flow of the source gas over the substrate and increasing the flow rate of the gas flowing over the substrate at the time of film formation over the substrate, and facilitates the flow of the inert gas purging the heat insulating space below the substrate processing position in the inner tube into the substrate processing space. As a result, the film thickness varies depending on the vertical position at which the substrate is disposed.
The invention aims to provide a technology for shortening cleaning time.
Means for solving the problems
In one aspect of the present invention, a substrate processing apparatus includes: a reaction tube having an outer tube and an inner tube, one ends of which are respectively closed; a cylindrical manifold connected to an open end side of the reaction tube; a sealing cap blocking an end of the manifold opposite to an end connected to the reaction tube; a rotating mechanism which penetrates the sealing cover and transmits rotation; and a gas supply pipe for supplying purge gas for purging the space inside the manifold. The reaction tube has: an exhaust port communicating with an exhaust space between the outer pipe and the inner pipe; a 1 st exhaust port provided in the inner tube and configured to exhaust the process gas; and a plurality of 2 nd exhaust ports that communicate the exhaust space with a space inside the manifold, at least one of the 2 nd exhaust ports promoting exhaust of gas that is retained in an exhaust space that is distant from the 1 st exhaust port.
Effects of the invention
According to the present invention, it is possible to improve gas stagnation in the gap of the double tube, shorten the cleaning time, and improve film uniformity between substrates.
Drawings
Fig. 1 is a schematic view of a substrate processing apparatus of an embodiment.
FIG. 2 is a longitudinal sectional view of an adiabatic assembly in a substrate processing apparatus according to an embodiment.
FIG. 3 is a perspective view of a cross section including a reaction tube in the substrate processing apparatus according to the embodiment.
FIG. 4 is a sectional view of a reaction tube in the substrate processing apparatus according to the embodiment.
FIG. 5 is a bottom view of a reaction tube in the substrate processing apparatus according to the embodiment.
Fig. 6 is a diagram illustrating a flow of a shaft purge gas in the substrate processing apparatus of the embodiment.
Fig. 7 is a configuration diagram of a controller in the substrate processing apparatus according to the embodiment.
Fig. 8 is a graph showing pressure and temperature in the cleaning process of the embodiment.
Fig. 9 is a bottom view of a reaction tube in a substrate processing apparatus according to a modification.
Detailed Description
Hereinafter, embodiments will be described with reference to the drawings.
As shown in fig. 1, a substrate processing apparatus 1 according to the present embodiment is a vertical heat treatment apparatus for performing a heat treatment process in semiconductor integrated circuit manufacturing, and includes a processing furnace 2. The processing furnace 2 has a heater 3 formed of a plurality of heater units for uniformly heating the processing furnace 8. The heater 3 is cylindrical and is supported by a heater base (not shown) serving as a holding plate, and is vertically attached to a mounting base plate of the substrate processing apparatus 1. The heater 3 also functions as an activation mechanism (excitation unit) for activating (exciting) the gas by heat as described later.
A reaction tube 4 constituting a reaction vessel (processing vessel) is disposed inside the heater 3. The reaction tube 4 is made of, for example, quartz (SiO)2) Or a heat-resistant material such as silicon carbide (SiC), and is formed into a cylindrical shape with its upper end closed and its lower end open. The reaction tube 4 has a double tube structure having an outer tube 4A and an inner tube 4B joined to each other at a flange portion 4C at a lower end. The upper ends of the outer tube 4A and the inner tube 4B are closed, and the lower end of the inner tube 4B is open. The flange portion 4C has an outer diameter larger than that of the outer tube 4A and protrudes outward. An exhaust port 4D communicating with the inside of the outer tube 4A is provided in a portion of the reaction tube 4 near the lower end. The reaction tube 4 including these components is integrally formed of a single material as a whole. The outer tube 4A is formed thick so as to be able to withstand a pressure difference when the inside is evacuated.
The manifold 5 is cylindrical or truncated cone-shaped, made of metal or quartz, and is provided to support the lower ends of the reaction tubes 4. The inner diameter of the manifold 5 is formed larger than the inner diameter of the reaction tube 4 (inner diameter of the flange portion 4C). This forms an annular space described later between the lower end (flange 4C) of the reaction tube 4 and the seal cap 19 described later. The space or the members around the space are collectively referred to as a furnace opening.
A main exhaust port 4E for communicating the inside with the outside is provided on the side surface of the inner tube 4B on the back side of the reaction tube from the exhaust port 4D, and a supply slit 4F is provided at a position opposite to the main exhaust port 4E. The main exhaust port 4E is a single longitudinal opening that opens to the region where the wafer 7 is disposed. The supply slit 4F is a slit extending in the circumferential direction, and a plurality of supply slits are arranged in the vertical direction so as to correspond to the wafers 7.
The inner tube 4B is further provided with a plurality of sub-exhaust ports 4G for communicating the process chamber 6 with the exhaust space S at positions further to the back side of the reaction tube 4 than the exhaust port 4D and further to the opening side than the main exhaust port 4E. Further, the flange 4C is formed with a plurality of bottom exhaust ports 4H and 4J and a nozzle introduction hole 4K for communicating the processing chamber 6 with the lower end of the exhaust space S. In other words, the lower end of the exhaust space S is closed by the flange 4C except for the bottom exhaust ports 4H, 4J, and the like. The sub-exhaust ports 4G and 4H mainly function to exhaust a shaft purge gas described later.
One or more nozzles 8 for supplying a process gas such as a source gas are provided in a space between the outer tube 4A and the inner tube 4B (hereinafter referred to as an exhaust space S) so as to correspond to the positions of the supply slits 4F. The nozzles 8 are connected to gas supply pipes 9 for supplying process gases (source gases) through the manifolds 5.
A flow mass controller (MFC)10 as a flow rate controller and a valve 11 as an on-off valve are provided in this order from the upstream side in the flow path of each gas supply pipe 9. A gas supply pipe 12 for supplying an inert gas is connected to the gas supply pipe 9 on the downstream side of the valve 11. The gas supply pipe 44b is provided with an MFC13 and a valve 14 in this order from the upstream side. The gas supply pipe 9, the MFC10, and the valve 11 mainly constitute a process gas supply unit as a process gas supply system.
The nozzle 8 is provided in the gas supply space 4 so as to stand from the lower portion of the reaction tube 4. One or more nozzle holes 8H for supplying gas are provided in the side surface and the upper end of the nozzle 8. The plurality of nozzle holes 8H correspond to the openings of the supply slit 4F and are opened toward the center of the reaction tube 4, so that gas can be injected toward the wafer 7 through the inner tube 4B.
An exhaust pipe 15 for exhausting the atmosphere in the processing chamber 6 is connected to the exhaust port 4D. A vacuum pump 18 as a vacuum exhaust device is connected to the exhaust pipe 15 via a Pressure sensor 16 as a Pressure detector (Pressure gauge) for detecting the Pressure in the processing chamber 6 and an APC (automatic Pressure Controller) valve as a Pressure regulator (Pressure adjusting unit). The APC valve 17 can perform vacuum evacuation and vacuum evacuation stop in the processing chamber 6 by opening and closing the valve while the vacuum pump 18 is activated. Further, the configuration is: in a state where the vacuum pump 18 is operated, the valve opening degree is adjusted based on the pressure information detected by the pressure sensor 16, and the pressure in the processing chamber 6 can be adjusted. The exhaust system is mainly constituted by an exhaust pipe 15, an APC valve 17, and a pressure sensor 16. It is also contemplated to include a vacuum pump 18 in the exhaust system.
A seal cap 19 as a furnace opening lid body capable of hermetically closing the lower end opening of the manifold 5 is provided below the manifold 5. The seal cover 19 is formed of a metal such as stainless steel or nickel base alloy and formed into a disk shape. An O-ring 19A as a sealing member is provided on the upper surface of the seal cap 19 so as to abut against the lower end of the manifold 5.
Further, a cover plate 20 for protecting the seal cover 19 is provided on the upper surface of the seal cover 19, at a portion inside the lower end inner periphery of the manifold 5. The cover plate 20 is formed of a heat and corrosion resistant material such as quartz, sapphire, or SiC, and is formed in a disk shape. The cover plate 20 does not require mechanical strength and can be formed with a thin wall thickness. The cover plate 20 is not limited to a member prepared separately from the cover portion 22, and may be a thin film or layer of nitride or the like formed by plating or modifying the inner surface of the cover portion 19. The cover plate 20 may also have a wall rising from the circumferential edge along the inner surface of the manifold 5.
The wafer boat 21 as a substrate holder supports a plurality of, for example, 25 to 200 wafers 7 in a horizontal posture with their centers aligned in a vertical direction in multiple stages. Here, the wafers 7 are arranged at regular intervals. The wafer boat 21 is made of a heat-resistant material such as quartz or SiC. There are the following cases: the reaction tube 4 is preferably formed to have a minimum inner diameter that enables safe carrying in and out of the wafer boat 21.
A heat insulating unit 22 described later is disposed below the wafer boat 21. The insulation assembly 22 has a structure that reduces heat conduction or heat transfer in the up-down direction, and generally has a hollow space inside. The interior can be purged with a shaft purge gas. In the reaction tube 4, an upper portion where the boat 21 is disposed is referred to as a substrate processing region a, and a lower portion where the heat shield assembly 22 is disposed is referred to as a heat shield region B.
A rotation mechanism 23 for rotating the boat 21 is provided on the side of the seal cover 19 opposite to the process chamber 6. A gas supply pipe 24 for shaft purge gas is connected to the rotating mechanism 23. The gas supply pipe 44c is provided with an MFC25 and a valve 26 in this order from the upstream side. One of the purposes of the purge gas is to protect the inside (e.g., bearings) of the rotation mechanism 23 from the corrosive gas used in the process chamber 6 and the like. Purge gas is exhausted from the rotary mechanism 23 along the shaft and directed into the insulation assembly 22.
The boat elevator 27 is vertically provided below the outside of the reaction tube 4, and operates as an elevating mechanism (conveyance mechanism) for elevating the seal cap 19. Thereby, the boat 21 and the wafers 7 supported by the seal cover 19 are carried into and out of the processing chamber 6. While the sealing lid 19 is lowered to the lowermost position, a shutter (not shown) for closing the lower end opening of the reaction tube 4 may be provided instead of the sealing lid 19.
A temperature detector 28 is provided on the outer wall of the outer tube 4A. The temperature detector 27 may be constituted by a plurality of thermocouples arranged in parallel in the vertical direction. The temperature inside the processing chamber 6 is set to a desired temperature distribution by adjusting the energization state of the heater 3 based on the temperature information detected by the temperature detector 27.
The controller 29 is a computer that controls the entire substrate processing apparatus 1, and is electrically connected to the MFCs 10 and 13, the valves 11 and 14, the pressure sensor 16, the APC valve 17, the vacuum pump 18, the heater 3, the lid heater 34, the lower lid heater 35, the temperature detector 28, the rotation mechanism 23, and the boat elevator 27, and the like, and receives signals from these components or controls these components.
Figure 2 shows a cross section of the insulation assembly 22 and the rotation mechanism 23. The rotation mechanism 23 has a casing (main body) 23A formed in a substantially cylindrical shape having an open upper end and a closed lower end, and the casing 23A is fixed to the lower surface of the seal cover 19 by bolts. Inside the outer casing 23A, an inner shaft 23B having a cylindrical shape and an outer shaft 23C having a cylindrical shape having a diameter larger than that of the inner shaft 23B are coaxially provided in this order from the inside. The outer shaft 23C is rotatably supported by a pair of upper and lower inner bearings 23D and 23E interposed between the inner shaft 23B and the outer shaft 23A, and a pair of upper and lower outer bearings 23F and 23G interposed between the outer shaft and the outer housing 23A. On the other hand, the inner shaft 23B is fixed to the outer housing 23A so as not to rotate.
Magnetic fluid seals 23H and 23I for isolating air at vacuum and atmospheric pressure are provided on the inner bearing 23D and the outer bearing 23F, i.e., on the processing chamber 6 side. A worm wheel or a pulley 23K driven by an electric motor (not shown) or the like is attached to the outer shaft 23C.
A sub-heater support 33 as a 1 st auxiliary heating mechanism for heating the wafer 7 from below in the processing chamber 6 is vertically inserted inside the inner shaft 23B. The sub-heater stay 33 is a quartz tube, and concentrically holds the lid heater 34 at the upper end thereof. The sub-heater stay 33 is supported at the upper end position of the inner shaft 23B by a support portion 23N formed of a heat-resistant resin. Further, the lower part between the sub-heater stay 33 and the inner shaft 23B is sealed by a vacuum joint 23P.
A cylindrical rotating shaft 36 having a flange at its lower end is fixed to the upper surface of the flange-shaped outer shaft 23C. The sub-heater support 33 penetrates the hollow of the rotary shaft 36. A disk-shaped rotary table 37 is fixed to the upper end of the rotary shaft 36 at a predetermined interval h1 from the cover plate 20, and the disk-shaped rotary table 37 has a through hole formed in the center thereof through which the sub-heater stay 33 passes.
An insulator holder 38 for holding an insulator 40 and a cylindrical portion 39 are concentrically mounted on the upper surface of the turntable 37 and fixed thereto by screws or the like. The heat insulating unit 22 includes a rotary table 37, a heat insulator holder 38, a cylindrical portion 39, and a heat insulator 40, and the rotary table 37 constitutes a bottom plate (support table). The turntable 37 is provided with a plurality of exhaust holes 37A having a diameter (width) h2 in a rotationally symmetrical manner near the edge.
The heat insulator holder 38 is formed in a cylindrical shape having a hollow hole in the center through which the sub-heater support 34 penetrates. The heat insulator holder 38 has a leg portion 38C at a lower end thereof, which has an outer diameter smaller than the outward flange shape of the rotary table 37. On the other hand, the upper end of the heat insulator holder 38 is opened so that the sub-heater stay 33 protrudes therefrom, and constitutes a purge gas supply port 38B.
A flow path having an annular cross section for supplying the shaft purge gas to the upper portion in the heat insulating block 22 is formed between the heat insulator holder 38 and the sub heater stay 33. The purge gas supplied from the supply hole 38B flows downward in the space between the insulator holder 38 and the inner wall of the cylindrical portion 39, and is exhausted from the exhaust hole 37A to the outside of the cylindrical portion 39. The shaft purge gas discharged from the gas discharge hole 37A flows in the radial direction through the gap between the turntable 37 and the cover plate 20 and is discharged to the furnace opening, where the furnace opening is purged.
A plurality of reflection plates 40A and heat insulating plates 40B are coaxially provided as the heat insulator 40 on the column of the heat insulator holder 38.
The cylindrical portion 39 has an outer diameter such that a gap h6 between the cylindrical portion and the inner tube 4B becomes a predetermined value. In order to suppress the passage of the process gas or the shaft purge gas, the gap h6 is preferably set to be narrow, for example, 7.5mm to 15 mm.
The upper end of the cylindrical portion 39 is closed by a flat plate, and the boat 21 is set therein.
Fig. 3 shows a perspective view of the reaction tube 4 cut horizontally. In the figure, the flange portion 4C is omitted. In the inner tube 4B, the number of supply slits 4F for supplying the process gas into the process chamber 6 is 3 in the longitudinal direction and the number is the same as that of the wafers 7, and the slits are arranged in a lattice shape. Partition plates 41 extending in the longitudinal direction are provided between the lateral rows of the supply slits 4F and at both ends thereof so as to partition the exhaust space S between the outer pipe 4A and the inner pipe 4B. The partitions separated from the main exhaust space S by the plurality of partition plates 41 form a nozzle chamber (nozzle buffer) 42. As a result, the exhaust space S is formed in a C-shape in cross section. The only opening connecting the nozzle chamber 42 directly with the inside of the inner tube 4B is the supply slit 4F.
The partition plate 41 is coupled to the inner tube 4B, but may be configured to have a slight gap without being coupled to the outer tube 4A in order to avoid stress caused by a temperature difference between the outer tube 4A and the inner tube 4B. The nozzle chamber 42 need not be completely isolated from the exhaust space S, and in particular may have openings or gaps at the upper and lower ends communicating with the exhaust space S. The nozzle chamber 42 is not limited to the outer peripheral side thereof being divided by the outer tube 4A, and a partition plate may be separately provided along the inner surface of the outer tube 4A.
The inner pipe 4B is provided with 3 sub-exhaust ports 4G at positions open to the side surface of the heat insulation module. One of the sub-exhaust ports 4G is provided in the same orientation as the exhaust port 4D, and at least a part of the opening is disposed at a height that overlaps the pipe of the exhaust port 4D. The remaining two sub-exhaust ports 4G are disposed near both side portions of the nozzle chamber 42. Alternatively, the 3 sub-exhaust ports 4G may be arranged at positions spaced 180 degrees apart on the circumference of the inner tube 4B.
As shown in fig. 4, the nozzles 8a to 8c are provided in the 3 nozzle chambers 42, respectively. Nozzle holes 8H that open toward the center of the reaction tube 6 are provided in the side surfaces of the nozzles 8a to 8 d. The gas ejected from the nozzle hole 8H is intended to flow from the supply slit 4F into the inner tube 4B, but a part of the gas does not directly flow in.
Since the nozzles 8a to 8c are provided in separate spaces by the partition plate 41, the process gases supplied from the nozzles 8a to 8c can be prevented from being mixed in the nozzle chamber 42. The gas accumulated in the nozzle chamber 42 can be discharged from the upper end and the lower end of the nozzle chamber 42 to the exhaust space. With this configuration, the process gas can be prevented from being mixed in the nozzle chamber 42 to form a thin film or by-products. In fig. 4 alone, a purge nozzle 8d that can be arbitrarily provided is provided in the exhaust space S adjacent to the nozzle chamber 42 in the axial direction (vertical direction) of the reaction tube. Hereinafter, a case where the purge nozzle 8d is not provided will be described.
Fig. 5 shows a bottom view of the reaction tube 4. The flange portion 4C is provided with bottom exhaust ports 4H and 4J and a nozzle introduction hole 4K as openings connecting the exhaust space S and the flange lower portion. The bottom exhaust port 4H is an elongated hole provided at a position closest to the exhaust port 4D, and the bottom exhaust port 4J is a small hole provided at 6 positions along the C-shaped exhaust space S. The nozzle introduction hole 4K is formed by inserting the nozzles 8a to 8c through its opening, and is normally closed by a nozzle introduction escutcheon 8S (fig. 1) made of quartz. If the opening of the bottom exhaust port 4J is too large as described later, the flow rate of the shaft purge gas passing therethrough decreases, and the raw material gas and the like intrude into the furnace mouth portion from the exhaust space S by diffusion. Therefore, a hole (narrowed) in which the diameter of the central portion is reduced may be formed.
Fig. 6 shows a shaft purge gas discharge path. The shaft purge gas discharged from the gas discharge hole 37A flows in the radial direction through the gap between the turntable 37 and the cover plate 20, and is discharged to the furnace opening. Here, the purge gas suppresses the inflow of the raw material gas into the furnace opening, dilutes the raw material gas that has intruded into the furnace opening by diffusion or the like, and carries the diluted raw material gas on the purge gas flow to be discharged, thereby playing a role of preventing the adhesion of by-products to the furnace opening or the degradation thereof. The shaft purge gas discharge path has roughly the following four modes.
A path P1 enters the exhaust space S from the bottom exhaust port 4H or 4J and reaches the exhaust port 4D.
The path P2 passes through the gap between the inner pipe 4B and the heat insulation assembly 22, enters the exhaust space S from the sub exhaust port 4G, and reaches the exhaust port 4D.
The path P3 passes through the gap between the inner tube 4B and the insulation assembly 22 into the processing region a, from the main exhaust port 4E into the exhaust space S and to the exhaust port 4D.
The path P4 enters the nozzle chamber 42 from the nozzle introduction hole 4K, crosses the processing region a, enters the exhaust space S from the main exhaust port 4E, and reaches the exhaust port 4D.
The paths P3 and P4 for the purge gas to flow into the process region a are not ideal for processing of the substrate because the concentration of the process gas is reduced and the substrate-to-substrate uniformity is impaired below the process region a. In particular, one of the characteristics of the reaction tube 4 of this example is that the pressure loss of the main exhaust port 4E is small, and therefore the purge gas is easily introduced into the paths P3 and P4. When neither the nozzle introduction hole cover 8S nor the bottom exhaust port 4J is provided, the purge gas flows only through the path P4. Therefore, in this example, increasing the opening of the sub-exhaust port 4G and decreasing the gap h6 make it easier for the purge gas to flow into the path P2 than the path P3. The nozzle introduction hole 4K is closed by the nozzle introduction hole cover 8S, for example, so that the substantial opening is sufficiently small and the flow into the path P4 is not likely to occur. The sub-exhaust port 4G can form a preferable pressure gradient in which the pressure on the process region a side and the furnace opening side is high and the pressure in the vicinity of the sub-exhaust port 4G is the lowest on the side surface of the cylindrical portion 39 when the process gas and the shaft purge gas flow. In this pressure gradient, both inflow of the shaft purge gas into the process field and inflow (diffusion) of the process gas into the furnace opening due to the path P3 can be suppressed. If the supply of the shaft purge gas is excessive, the pressure loss in the paths 1 and 2 increases, and the pressure gradient may be deteriorated.
On the other hand, the innermost portion of the C-shaped exhaust space S is in contact with the nozzle chamber 42 to form a small bag-like path, and therefore the process gas such as the cleaning gas is likely to be accumulated. At this time, if the exhaust space S and the furnace mouth portion are allowed to flow through each other through the bottom exhaust port 4J, the shaft purge gas flows into the exhaust space S through the path P3 to eliminate stagnation when the shaft purge gas is large (the pressure on the furnace mouth portion side is high), and the process gas flows into or diffuses into the exhaust space S and is discharged from the bottom exhaust port 4G when the shaft purge gas is small, so that the process gas contributes to exhaust of the stagnant gas in any case. In the case where the amount of the retained gas is small, the retained gas is sufficiently diluted even if it enters the furnace opening, and therefore there is no problem.
However, if the flow conductance of the path of P1 is increased by increasing the size of the bottom exhaust port 4J, the maximum flow rate of the shaft purge gas decreases in all the paths including P1, and the process gas easily penetrates into the furnace opening due to diffusion in the direction opposite to the flow direction.
As described above, it is preferable that the conductance of the paths P4 and P3 be smaller than that of any of the paths P1 and P2, and the upper limit of the conductance of the paths P1 and P2 is set so that the intrusion of the process gas into the furnace opening portion becomes equal to or less than the allowable amount.
As shown in fig. 7, the controller 29 is electrically connected to the MFCs 10, 13, and 25, the valves 11, 14, and 26, the pressure sensor 16, the APC valve 17, the vacuum pump 18, the heater 3, the lid heater 34, the temperature detector 28, the rotation mechanism 23, the boat elevator 27, and the like, to automatically control these components. The controller 29 is configured as a computer including a CPU (Central Processing Unit) 212, a RAM (Random Access Memory) 214, a storage device 216, and an I/O port 218. The RAM214, the storage device 216, and the I/O port 218 are configured to be able to exchange data with the CPU212 via an internal bus 220. The I/O port 218 is connected to each of the above components. The controller 29 is connected to an input/output device 222 such as a touch panel.
The storage device 216 is configured by, for example, a flash memory, an HDD (Hard Disk Drive), or the like. The storage device 216 stores, in a readable manner, a control program for controlling the operation of the substrate processing apparatus 1, and a program (a process, a cleaning process, or the like) for causing each component of the substrate processing apparatus 1 to perform a film formation process or the like in accordance with a processing condition. The RAM214 is configured as a memory area (work area) that temporarily holds programs, data, and the like read by the CPU 212.
The CPU212 reads and executes the control program from the storage device 216, and reads the process from the storage device 216 in response to input of an operation command from the input/output device 222, and controls the respective configurations in accordance with the process.
The controller 29 can be configured by installing the above-described program, which is continuously saved in an external storage device (for example, a semiconductor memory such as a USB memory or a memory card, an optical disk such as a CD or a DVD, or an HDD)224, in a computer. The storage device 216 and the external storage device 224 are configured as tangible media that can be read by a computer. Hereinafter, these are also referred to simply as recording media. Note that the program may be provided to the computer using a communication means such as the internet or a dedicated line without using the external storage device 224.
Next, a timing example of a process of forming a film on a substrate (hereinafter, also referred to as a film forming process) using the processing apparatus 4 as one of the steps of the manufacturing process of the semiconductor Device (Device) will be described.
Here, an example will be described in which two or more nozzles 8 are provided, and Hexachlorodisilane (HCDS) gas is supplied as the 1 st process gas (source gas) from the nozzle 8A, and ammonia (NH3) gas is supplied as the 2 nd process gas (reaction gas) from the nozzle 8B, respectively, to form a silicon nitride (SiN) film on the wafer 7. In the following description, the operations of the respective components of the substrate processing apparatus 1 are controlled by the controller 29.
In the film formation process in the present embodiment, the following steps are repeated a predetermined number of times (one or more times) to form the SiN film on the wafer 7: a step of supplying HCDS gas to the wafer 7 in the process chamber 6, a step of removing HCDS gas (residual gas) from the process chamber 6, a step of supplying NH3 gas to the wafer 7 in the process chamber 6, and a step of removing NH3 gas (residual gas) from the process chamber 6. In the present specification, the film formation sequence is expressed as follows for convenience:
(wafer Loading and boat Loading)
After a plurality of wafers 7 are loaded (wafer loading) in the boat 21, the boat 21 is loaded (boat loading) into the processing chamber 6 by the boat elevator 27. At this time, the seal cap 19 is in a state of hermetically closing (sealing) the lower end of the manifold 5 by the O-ring 19A. The valve 26 is opened from a standby state before wafer loading, and a small amount of purge gas can be supplied into the cylindrical portion 39.
(pressure adjustment)
The processing chamber 6, that is, the space in which the wafer 7 is present, is evacuated (depressurized) by the vacuum pump 18 so that a predetermined pressure (vacuum degree) is obtained. At this time, the pressure in the processing chamber 6 is measured by the pressure sensor 52, and the APC valve 17 is feedback-controlled based on the measured pressure information. The supply of the purge gas into the cylindrical portion 39 and the operation of the vacuum pump 18 are maintained at least until the end of the process for the wafer 7.
(temperature elevation)
After sufficiently exhausting oxygen gas and the like from the inside of the processing chamber 6, the temperature rise in the processing chamber 6 is started. Feedback control of the energization states of the heater 34, the lid heater 34, and the lower lid heater 35 is performed based on the temperature information detected by the temperature detector 28 so that the process chamber 6 has a predetermined temperature distribution suitable for film formation. The heating in the processing chamber 6 by the heater 34 and the like is continued at least until the processing (film formation) for the wafer 7 is completed. The energization period for energizing the lid heater 34 does not need to coincide with the heating period for heating the heater 34. It is preferable that the temperature of the lid heater 34 be the same as the film formation temperature and the temperature of the inner surface of the manifold 5 be 180 ℃ or higher (e.g., 260 ℃) immediately before the start of film formation.
Further, the rotation of the wafer boat 21 and the wafers 7 by the rotation mechanism 23 is started. The wafer boat 21 is rotated by the rotation mechanism 23 via the rotation shaft 66, the turntable 37, and the cylindrical portion 39, and thereby the wafers 7 are rotated without rotating the sub-heater 64. This reduces uneven heating. The rotation of the boat 21 and the wafers 7 by the rotation mechanism 23 is continued at least until the end of the process for the wafers 7.
(film formation)
If the temperature in the processing chamber 6 is stabilized to the preset processing temperature, the steps 1 to 4 are repeated. It should be noted that the valve 26 may be opened to increase the supply of purge gas before step 1 is started.
[ step 1: raw material gas supply step
In step 1, HCDS gas is supplied to the wafer 7 in the process chamber 6. The valve 11A is opened and the valve 14A is opened, so that the HCDS gas flows into the gas supply pipe 44A and the N2 gas flows into the gas supply pipe 44 b. The flow rates of the HCDS gas and the N2 gas are adjusted by MFCs 10 and 13, respectively, and the HCDS gas and the N2 gas are supplied into the processing chamber 6 through the nozzle 42 and exhausted from the exhaust pipe 15. By supplying HCDS gas to the wafer 7, a silicon (Si) -containing film having a thickness of, for example, from less than 1 atomic layer to several atomic layers is formed as the 1 st layer on the outermost surface of the wafer 7.
[ step 2: raw material gas exhaust step
After the layer 1 is formed, the valve 11A is closed, and the supply of the HCDS gas is stopped. At this time, the APC valve 17 is kept open, and the inside of the process chamber 6 is evacuated by the vacuum pump 18, so that the unreacted HCDS gas remaining in the process chamber 6 or the HCDS gas contributing to the formation of the 1 st layer is exhausted from the process chamber 6. Further, the N2 gas supplied while the valves 14A and 26 are kept open purges the gas supply pipe 9, the inside of the reaction tube 4, and the furnace opening.
[ step 3: reaction gas supply step
In step 3, NH3 gas is supplied to the wafer 7 in the processing chamber 6. The opening and closing control of the valves 11B and 14B is performed in the same procedure as the opening and closing control of the valves 11A and 14A in step 1. The flow rates of the NH3 gas and the N2 gas are adjusted by MFCs 10 and 13, respectively, and the gas is supplied into the process chamber 6 through the nozzle 42 and exhausted from the exhaust pipe 15. The NH3 gas supplied to the wafer 7 reacts with at least a portion of the 1 st layer, i.e., the Si-containing layer, formed on the wafer 7 in step 1. Thereby, the 1 st layer is nitrided and converted (modified) into a silicon nitride layer (SiN layer) which is a 2 nd layer containing Si and N.
[ step 4: reaction gas exhaust step
After the formation of the 2 nd layer, the valve 11 was closed, and the supply of NH3 gas was stopped. Then, in the same process step as step 1, the unreacted NH3 gas remaining in the process chamber 6, the NH3 gas contributing to the layer 2 formation, and the reaction by-products are exhausted from the process chamber 6.
By performing the above 4 steps in cycles a predetermined number of times (n times) at different times, i.e., without overlapping, an SiN film having a predetermined composition and a predetermined film thickness can be formed on the wafer 7.
The above-described time-series processing conditions are exemplified by
Process temperature (wafer temperature): at 250-700 deg.C,
Process pressure (pressure in process chamber): 1 to 4000Pa,
HCDS gas supply flow rate: 1 to 2000sccm,
NH3 gas supply flow rate: 100 to 10000sccm,
N2 gas supply flow rate (nozzle): 100 to 10000sccm,
N2 gas supply flow rate (rotation axis): 100 to 500 sccm.
By setting each process condition to a certain value within each range, the film formation process can be appropriately performed.
Thermally decomposable gases such as HCDS may form a film of by-products on the surface of metal more easily than quartz. The surface exposed to HCDS (and ammonia gas) is particularly likely to be coated with SiO, SiON, etc. at 260 ℃ or lower.
(purge and atmospheric pressure recovery)
After the film formation process is completed, the valves 14A and 14B are opened, and the N2 gas is supplied into the process chamber 6 from the gas supply pipes 12A and 12B and exhausted from the exhaust pipe 15. Thereby, the atmosphere in the processing chamber 6 is replaced with an inert gas (inert gas replacement), and the remaining raw materials and by-products are removed (purged) from the processing chamber 6. Then, the APC valve 17 is closed, and the N2 gas is filled until the pressure in the processing chamber 6 becomes normal pressure (atmospheric pressure recovery).
(boat unloading and wafer taking out)
The sealing lid 19 is lowered by the boat elevator 27, and the lower end of the manifold 5 is opened. The processed wafers 7 are carried out from the lower end of the manifold 5 to the outside of the reaction tube 36 while being supported by the boat 21 (boat unloading). The processed wafers 7 are taken out from the boat 21.
After the above-described film formation process, a thin film is formed by depositing a SiN film containing nitrogen on the surface of the heated member in the reaction tube 4, for example, the inner wall of the outer tube 4A, the surface of the nozzle 8a, the surface of the inner tube 4B, the surface of the boat 21, and the like. Therefore, when the amount of these deposits, that is, the accumulated film thickness reaches a predetermined amount (thickness) before the deposits are peeled off or dropped, the cleaning process is performed.
The cleaning process is performed by supplying F2 gas, for example, as a fluorine-based gas into the reaction tube 4. An example of the cleaning process in the present embodiment will be described below with reference to fig. 8. Here, the following are set: a gas supply pipe 9a of the nozzle 8a is connected to a F2 gas source. In the following description, the operations of the respective parts constituting the substrate processing apparatus are controlled by the controller 29.
(boat carrying-in step)
The shutter plate is moved to open the lower end opening 2B of the manifold 5 (shutter plate open). Then, the empty boat 21, that is, the boat 21 not loaded with the wafers 7 is lifted by the boat elevator 27 and carried into the reaction tube 4 (boat loading).
(pressure, temperature regulating step)
Vacuum evacuation is performed by a vacuum pump 246 so that the inside of the reaction tube 4 becomes a desired pressure. The vacuum pump 246 is maintained in a continuously operating state at least until the end of the cleaning process. Further, the inside of the reaction tube 4 is heated by the heater 3 to a desired temperature (2 nd temperature). The 2 nd temperature can be lower than the temperature of the wafer 7 (1 st temperature) in the film formation step, for example. This means that the heating is reduced as compared with the standby state. Further, the rotation of the boat 21 by the rotation mechanism 23 is started. The rotation of the boat 21 may be continued until the cleaning process is completed.
(gas cleaning step)
In this step, the opening and closing of these valves are controlled in the same manner as the opening and closing of the valves 10a, 13a, and 13b in step 1 of the film formation process. The flow rate of the F2 gas was adjusted by MFC10a, and the gas was supplied into reaction tube 4 through gas supply tube 9a and nozzle 8 a. By flowing the N2 gas out of the gas supply pipe 12a, the F2 gas can be diluted, and the concentration of the F2 gas supplied into the reaction tube 4 can be controlled. At this time, a small amount of N2 gas may flow out from the gas supply pipes 12b and 24 to purge the nozzle 8b, the shaft, and the furnace opening. Hydrogen Fluoride (HF) gas, hydrogen (H2) gas, Nitric Oxide (NO) gas, and the like may be added to the F2 gas.
During this step, the APC valve 17 is appropriately adjusted so that the pressure in the reaction tube 4 becomes, for example, a pressure in the range of 1330 to 101300Pa, preferably 13300 to 53320 Pa. The supply flow rate of the F2 gas controlled by MFC10a is, for example, in the range of 100 to 3000 sccm. The supply flow rate of the N2 gas controlled by MFC13a is, for example, a flow rate within a range of 100 to 10000 sccm. The time for supplying the F2 gas into the reaction tube 4 is, for example, 60 to 1800 seconds, preferably 120 to 1200 seconds. The temperature of the heater 3 is set so that the temperature in the reaction tube 4 is, for example, 200 to 450 ℃, preferably 200 to 400 ℃ (No. 2 temperature).
If the temperature in the reaction tube 4 is lower than 200 ℃, the etching reaction of the deposit may become difficult to progress. On the other hand, if the temperature in the reaction tube 4 exceeds 450 ℃, the etching reaction becomes severe, and the members in the reaction tube 4 may be damaged.
The supply of the F2 gas into the reaction tube 4 may be performed continuously or intermittently. When the supply of the F2 gas into the reaction tube 4 is intermittently performed, the F2 gas may be enclosed in the reaction tube 4. By intermittently supplying the F2 gas into the reaction tube 4, ammonium fluoride (NH) in the reaction tube 4 can be appropriately controlled4F) Silicon tetrafluoride (SiF)4) And the like, an environment in which the etching reaction easily proceeds can be formed. Further, by intermittently supplying the F2 gas, the pressure inside the reaction tube 4 can be changed, and the deposit can be provided with a pressure changeAn impact is given in accordance with the change in pressure. This can cause cracking, peeling, and the like of the deposit, thereby efficiently etching the deposit. Further, the amount of F2 gas used can be appropriately reduced, and the cost of the cleaning process can be reduced. Fig. 5 shows an example in which the supply of the F2 gas into the reaction tube 4 is intermittently performed to generate a pressure change in the reaction tube 4.
As the cleaning gas, fluorine-based gases such as chlorine fluoride (ClF3) gas, nitrogen fluoride (NF3) gas, HF gas, F2 gas + HF gas, ClF3 gas + HF gas, NF3 gas + HF gas, F2 gas + H2 gas, ClF3 gas + H2 gas, NF3 gas + H2 gas, F2 gas + NO gas, ClF3 gas + NO gas, NF3 gas + NO gas, and the like can be used in addition to the F2 gas. As the inert gas, for example, a rare gas such as argon can be used in addition to the N2 gas.
After the gas cleaning step is completed, the valve 10a is closed to stop the supply of the F2 gas into the reaction tube 4. Then, the inside of the reaction tube 4 is heated by the heater 3 so that the inside of the reaction tube 4 becomes a desired temperature (the 3 rd temperature). Here, an example in which the 3 rd temperature is higher than the 2 nd temperature, that is, an example in which the temperature in the reaction tube 4 is changed (increased) from the 2 nd temperature to the 3 rd temperature will be described. The heating at the 3 rd temperature is continued until the completion of the multi-stage purge step described later.
By making the 3 rd temperature higher than the 2 nd temperature, it is possible to promote a very small (number of) particle (foreign matter) source (for example, a solid generated by a reaction of a deposit with a cleaning gas)
Left and right) compounds (hereinafter, also referred to as residual compounds)) are released from the member surface in the
reaction tube 4. The reason for this is considered that the residual compounds such as NH4F are easily sublimated by heating the inside of the
reaction tube 4 in the above-described manner.
More preferably, the 3 rd temperature is higher than the temperature of the wafer 7 (1 st temperature) in the film formation step. By heating the inside of the reaction tube 4 to such a temperature, sublimation of the residual compound can be further promoted to further promote the desorption. However, if the temperature in the reaction tube 4 exceeds 630 ℃, the components in the reaction tube 4 may be damaged by heat.
The temperature of the heater 3 is set to: the temperature in the reaction tube 4 is set to a temperature satisfying the above conditions, and is, for example, 400 to 630 ℃, preferably 550 to 620 ℃ (No. 3 temperature).
(Multi-stage purge step)
A multi-stage purge step (pressure swing purge) is performed with the temperature in the reaction tube 4 set to the 3 rd temperature. The multi-stage purge step may be started simultaneously with the start of the temperature increase step. In this step, the following 1 st and 2 nd purge steps are performed in this order.
[ 1 st purge step ]
In this step, the inside of the reaction tube 4 is purged (1 st purge) while periodically changing the pressure inside the reaction tube 4 at a 1 st pressure width described later. Specifically, the step of increasing the pressure in the reaction tube 4 by the purge gas supplied into the reaction tube 4 (the 1 st pressure increasing step) and the step of reducing the pressure in the reaction tube 4 by strengthening the exhaust gas in the reaction tube 4 (the 1 st pressure reducing step) are set as one cycle, and this cycle is repeated a plurality of times (two or more times).
In the 1 st pressure increasing step, the valves 14a, 14b, and 26 are opened with the APC valve 17 slightly opened, and N2 gas is supplied into the reaction tube 4. The supply flow rate of the N2 gas controlled by MFC13a, 13b, and 25 is set to a flow rate in the range of 1000 to 50000sccm, for example. The maximum pressure in the reaction tube 4 is, for example, in the range of 53200 to 66500 Pa.
The first pressure increasing step 1 is performed in a state where the APC valve 17 is fully closed (full close), whereby the range of pressure change can be increased, but there is also a disadvantage that the residual compounds and the like easily flow back (diffuse) from the exhaust pipe 231 into the reaction tube 4.
In the next 1 st depressurization step, the APC valve 17 is fully opened (full open). The valves 14a, 14b, and 26 are kept open, but the supply flow rate of the N2 gas controlled by the MFCs 13a and 13b is reduced, and is set to a flow rate in the range of 50 to 500sccm, for example. The minimum pressure in the reaction tube 4 is, for example, in the range of 300 to 665 Pa.
In the 1 st depressurizing step, the pressure is reduced in a short time and the pressure variation width can be increased by closing the valves 14a, 14b, and 26 to stop the supply of the N2 gas into the reaction tube 4, but there is a possibility that residual compounds and the like may be generated from the exhaust pipe 231 into the reaction tube 4.
The pressure variation range in the 1 st purge step, i.e., the differential pressure between the maximum pressure in the pressure increasing step 1a and the minimum pressure in the pressure decreasing step 2a, is, for example, in the range of 52535 to 66101 Pa.
[ 2 nd purge step ]
After the 1 st purge step is completed, the 2 nd purge step is performed. In this step, the inside of the reaction tube 4 is purged (purge 2) while periodically changing the pressure inside the reaction tube 4 to a pressure range smaller than the pressure change range in the purge 1 step. Except for the pressure, the same as in purge step 1.
(temperature reduction and atmospheric pressure recovery step)
After the completion of the multi-stage purge step, the power of the heater 3 is adjusted to lower (lower) the temperature in the reaction tube 4. That is, the temperature in the reaction tube 4 is changed (decreased) from the 3 rd temperature to the 1 st temperature. Further, the N2 gas was flowed into the reaction tube 4 while keeping the valves 14a, 14b, and 26 open. Thereby, the reaction tube 4 was filled with N2 gas (gas replacement), and the pressure in the reaction tube 4 was returned to normal pressure (atmospheric pressure recovery).
(boat carrying-out step)
Then, the seal cap 19 is lowered by the boat elevator 27 to open the lower end of the manifold 5, and the empty boat 21 is carried out from the lower end of the manifold 5 to the outside of the reaction tube 4 (boat unloading). When the series of cleaning processes is completed, the film formation process is restarted.
In the cleaning process described above, the N2 gas is supplied at a constant ratio from the gas nozzles 8a and 8b and the gas supply pipe 24 in the multi-stage purge step, but the ratio may be changed periodically. For example, the following operations may be repeated: an operation of increasing the flow rate from the gas nozzles 8a and 8b and discharging the residual gas from the bottom exhaust port 4J to the furnace opening, and an operation of increasing the flow rate from the gas supply pipe 24 and flowing the shaft purge gas from the bottom exhaust port 4J into the exhaust space to push out the residual gas to the main exhaust port 4E.
In the present embodiment, one or more of the following effects can be obtained.
(a) By providing the sub-exhaust port 4G, the purge gas flowing into the inner tube 4B flows in a volume extremely into the exhaust space S between the outer tube and the inner tube, and the flow rate of the purge gas flowing into the substrate processing space a can be reduced.
(b) By providing the bottom exhaust ports 4H and 4J and the sub-exhaust port 4G, the exhaust efficiency of the exhaust space S and the clean gas is improved.
The reaction tube 4 is not limited to the outer tube 4A and the inner tube 4B being formed integrally, and may be formed of a separate member and placed on the manifold 5. In this case, the gaps through which the exhaust space and the furnace opening portion flow in the vicinity of the opening ends of the outer tube 4A and the inner tube 4B correspond to the bottom exhaust ports 4H and 4J. Alternatively, the outer tube 4A, the inner tube 4B, and the manifold 5 may all be integrally formed of quartz.
Next, a modification of the above embodiment will be described. Fig. 9 shows a bottom view of the reaction tube 400 of the substrate processing apparatus according to the modified embodiment. In this example, the inner tube 4G has a bulging portion 401 bulging outward. The bulging portion 401 provides a space for providing an increased number of nozzles, sensors, and the like inside thereof, and the bulging portion keeps the same shape continuously from the lower end to the upper end of the inner tube 4G because it locally narrows the exhaust space S.
Since the exhaust space S is locally narrowed by the bulging portion 401, stagnation is likely to occur when this state is maintained. In this example, at least one of the sub-exhaust port 4G and the bottom exhaust port 4J is provided in the inner pipe 4G located further to the rear side than the bulging portion 401 farthest from the main exhaust port 4E, and at least one bottom exhaust port 4J is provided in the exhaust space S sandwiched by the bulging portion 401. The narrow interval of the exhaust space S by the bulge portion 401 is preferably wider than the gap h 6.
In the above embodiment, an example in which the reaction tube is cleaned after the film is formed on the wafer is described. However, the present invention is not limited to the above embodiment, and is also useful for the case where by-products are generated, the surface of the reaction tube is corroded, or a pre-coating film for protecting the reaction tube is formed, even in the modification treatment such as oxidation and nitridation, the diffusion treatment, the etching treatment, and the like.
Industrial applicability
The present invention can be suitably applied to a film forming apparatus using a gaseous material, in addition to a manufacturing apparatus of a semiconductor device.
Description of the reference numerals
2 treatment furnace, 3 heater, 4 reaction tube, 4A outer tube,
4B inner tube, 4C flange, 4D exhaust port,
4E main exhaust port, 4F supply slit, 4G sub exhaust port,
4H, 4J bottom exhaust port, 4K nozzle leading-in hole 4K,
5 a manifold,
6 process chambers, 7 wafers,
8 nozzles, 9 gas supply pipes,
10 MFC、
12 gas supply pipe, 13 MFC, 15 exhaust pipe,
16 pressure sensor, 17 APC valve, 18 vacuum pump,
19a sealing cover, 20 cover plates, 21 wafer boats,
22 heat insulation assembly, 23 rotation mechanism, 24 gas supply pipe,
25 MFCs, 27 boat elevators, 28 temperature detectors,
29 controller, 33 sub-heater supports,
34 a heater, 36 a rotating shaft, 37a rotating table,
38 heat insulator holder, 39 cylindrical part, 40 heat insulator,
41 division plate, 42 nozzle chamber
