JP2011100896A - Substrate processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma substrate processing apparatus which suppresses the deposition of a film on a hole and near the hole, the hole connecting a buffer chamber with a reaction chamber, prevents the formation of particles by the deposited film, and can process a substrate without degrading quality of the substrate. <P>SOLUTION: The plasma substrate processing apparatus includes a cylindrical reaction container 29, a reaction chamber 32 which is sectioned in the reaction container 29 and is able to accommodate a plurality of substrates 2, a buffer chamber 38 formed in the reaction container 29, and gas introducing units 34 and 35 which are disposed along the longitudinal direction of the reaction container 29 and are capable of introducing a process gas into the buffer chamber 38. The buffer chamber 38 has a plurality of gas supply holes 48 and 53 through which the process gas introduced by the gas introducing units 34 and 35 is supplied to the reaction chamber 32, a space 59 in which electrodes 54 and 55 for plasma generation are placed, and at least one drip hole which penetrates the wall of the buffer chamber 38 to be open to the reaction chamber 32 and is used when the reaction container 29 is cleansed with a chemical. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a substrate processing apparatus for manufacturing a semiconductor device by performing thin film formation, oxidation treatment, impurity diffusion, annealing treatment, etching and the like on a substrate such as a silicon wafer.

  In a chemical vapor deposition method for forming a thin film on a substrate, when forming a precursor that decomposes the raw material and contributes to film formation, the raw material gas can be sufficiently decomposed if the temperature of the reaction chamber is low. Can not.

  As a method of decomposing the source gas when the temperature of the reaction chamber is low and the decomposition efficiency is not sufficiently high, there is a method of decomposing the source gas using plasma. A buffer chamber, which is a region for generating plasma in a reaction vessel such as quartz, and a reaction chamber in which a substrate is stored are defined. The buffer chamber and the reaction chamber are separate chambers, and the buffer chamber A method of performing chemical vapor deposition using a reaction tube as a reaction vessel having a structure in which reaction chambers are connected is known as remote plasma.

  In the remote plasma, a rare gas such as helium, argon or krypton is generally used as the gas supplied to the reaction chamber. In addition, there are other gases that can be discharged, such as hydrogen and ammonia, and there is no restriction on the gas used.

  A conventional buffer chamber will be described with reference to FIGS. 7A to 7C show the buffer chamber portion of the reaction tube 75. FIG.

  In the figure, reference numeral 75 denotes a reaction tube, and a buffer chamber 71 is formed on the inner wall surface side of the reaction tube 75. The buffer chamber 71 for generating plasma by remote plasma is provided with a nozzle 72 for supplying a source gas to the buffer chamber 71 and two rod-shaped electrodes 73 and 74 for generating plasma in the buffer chamber 71. At the same time, two relatively large holes 76 and 77 are formed on the upper surface and the lower surface respectively for the purpose of effectively supplying and discharging a chemical solution used when removing unnecessary films attached to the reaction tube 75. ing. In general, the holes 76 and 77 have a rectangular shape in order to promote efficient discharge of the chemical solution supplied from the hole on the upper surface, and the discharge effect of the chemical solution by applying pressure to the buffer chamber 71. It consists of a hole 77 having a circular shape so as to be raised.

  The holes 76 and 77 are larger than the gas supply holes 78 necessary for promoting the decomposition of the source gas, and a large amount of rare gas that decomposes the source gas flows through the holes 76 and 77. In the reaction chamber (not shown) and the buffer chamber 71, a large amount of film adheres to the vicinity of the holes 76 and 77, and the quality of the substrate is deteriorated by particles generated by the film.

JP 2004-6801 A

  In view of such circumstances, the present invention suppresses the deposition of a film in the vicinity of the hole and the hole communicating the buffer chamber and the reaction chamber, prevents the generation of particles due to the deposited film, and reduces the quality of the substrate. The present invention provides a substrate processing apparatus capable of processing without any problem.

  The present invention includes a cylindrical reaction vessel, a reaction chamber defined inside the reaction vessel and capable of accommodating a plurality of substrates, a buffer chamber provided inside the reaction vessel, and a longitudinal direction of the reaction vessel And a gas introduction part capable of introducing a processing gas into the buffer chamber, wherein the buffer chamber has a plurality of gas supply holes for supplying a processing gas introduced from the gas introduction part to the reaction chamber; The present invention relates to a substrate processing apparatus having a space for accommodating an electrode for generating plasma and at least one hole penetrating a side wall and opening into the reaction chamber.

  According to the present invention, a cylindrical reaction vessel, a reaction chamber defined in the reaction vessel and capable of accommodating a plurality of substrates, a buffer chamber provided in the reaction vessel, and the reaction vessel A gas introduction part provided along the longitudinal direction and capable of introducing a processing gas into the buffer chamber, wherein the buffer chamber supplies a plurality of gas supplies for supplying the processing gas introduced from the gas introduction part to the reaction chamber Since it has a hole, a space for accommodating an electrode for generating plasma, and at least one hole that penetrates the side wall and opens into the reaction chamber, the distance between the space for accommodating the electrode and the hole can be separated, The plasma-excited processing gas loses energy before reaching the hole, thereby preventing the processing gas from being decomposed and depositing the film when passing through the hole, and generated due to the film. Depending on the particles It exhibits an excellent effect that it is possible to prevent deterioration in the quality of the plate.

1 is a schematic perspective view of a substrate processing apparatus in the present invention. It is a schematic longitudinal cross-sectional view of the processing furnace in this invention. It is a general | schematic plane sectional view of the processing furnace in this invention. It is the schematic of the buffer chamber in a 1st Example, (A) shows the plane sectional view of a buffer chamber, (B) has shown CC arrow directional view of (A). It is the schematic of the buffer chamber in a 2nd Example, (A) shows the plane sectional view of a buffer chamber, (B) has shown the DD arrow directional view of (A). It is the schematic of the buffer chamber in a 3rd Example, (A) shows the plane sectional view of a buffer chamber, (B) has shown the EE arrow line view of (A). It is the schematic of the conventional buffer chamber, (A) shows the plane sectional view of a buffer chamber, (B) shows the AA arrow line view of (A), (C) is B- of (A). B arrow view is shown.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a substrate processing apparatus 1 according to the present invention will be described with reference to FIG.

  As an example, the substrate processing apparatus 1 is configured as a semiconductor manufacturing apparatus that performs a processing step in a manufacturing method of a semiconductor device (IC). In the following description, a case where a vertical apparatus that performs oxidation, diffusion processing, CVD processing, or the like is applied to the substrate as the substrate processing apparatus will be described.

  The substrate processing apparatus 1 in which a cassette 3 as a wafer carrier containing a wafer (substrate) 2 made of silicon or the like is used includes a housing 4. Below the front wall 5 of the housing 4, a front maintenance port (not shown) is opened as an opening provided for maintenance, and a front maintenance door (not shown) that opens and closes the front maintenance port. Z) is built. In the front maintenance door, a cassette loading / unloading port (substrate container loading / unloading port) (not shown) is opened so as to communicate between the inside and outside of the housing 4, and the cassette loading / unloading port is not shown. It is configured to be opened and closed by a device loading / unloading opening / closing mechanism. A cassette stage (substrate container delivery table) 6 is installed inside the housing 4 at the cassette loading / unloading exit. The cassette 3 is loaded onto the cassette stage 6 by an in-process transfer device (not shown) and unloaded from the cassette stage 6.

  The cassette stage 6 is placed so that the wafer 2 in the cassette 3 is placed in a vertical posture by the in-process transfer device and the wafer inlet / outlet of the cassette 3 faces upward. The cassette stage 6 rotates the cassette 3 90 degrees clockwise and vertically toward the rear of the housing 4 so that the wafer 2 in the cassette 3 is in a horizontal posture, and the wafer inlet / outlet of the cassette 3 Operation is possible so as to face the rear of the housing 4.

  A cassette shelf (substrate container mounting shelf) 7 is installed in a substantially central portion of the casing 4 in the front-rear direction. The cassette shelf 7 stores a plurality of cassettes 3 in a plurality of rows and columns. It is configured to do. The cassette shelf 7 is provided with a transfer shelf 9 in which the cassette 3 to be transferred by a wafer transfer mechanism 8 described later is stored. Further, a spare cassette shelf 11 is provided above the cassette stage 6 so as to store the cassette 3 in a preliminary manner.

  A cassette transfer device (substrate container transfer device) 12 is installed between the cassette stage 6 and the cassette shelf 7. The cassette transport device 12 includes a cassette elevator (substrate container lifting mechanism) 13 that can be moved up and down while holding the cassette 3, and a cassette transport mechanism (substrate container transport mechanism) 14 as a transport mechanism. The cassette 3 is transported between the cassette stage 6, the cassette shelf 7, and the spare cassette shelf 11 by continuous operation of the cassette elevator 13 and the cassette transport mechanism 14.

  Behind the cassette shelf 7, the wafer transfer mechanism (substrate transfer mechanism) 8 is installed. The wafer transfer mechanism 8 is a wafer transfer device capable of rotating or linearly moving the wafer 2 in the horizontal direction. (Substrate transfer apparatus) 15 and a wafer transfer apparatus elevator (substrate transfer apparatus elevating mechanism) 16 for moving the wafer transfer apparatus 15 up and down. By continuous operation of the wafer transfer device 15 and the wafer transfer device elevator 16, the tweezer (substrate holding body) 17 of the wafer transfer device 15 is used as a mounting portion for the wafer 2, and the boat (substrate holding tool) 18 is attached. On the other hand, the wafer 2 is loaded (charged) and loaded (discharged).

  A processing furnace 19 is provided at the rear upper part of the housing 4. The lower end of the processing furnace 19 is configured to be opened and closed by a furnace port shutter (furnace port opening / closing mechanism) 21.

  Below the processing furnace 19, a boat elevator (substrate holder lifting mechanism) 22 is provided as a lifting mechanism for moving the boat 18 up and down to the processing furnace 19, and is connected to a lifting platform of the boat elevator 22. A seal cap 24 as a lid is horizontally installed on the arm 23 as a tool, and the seal cap 24 is configured to support the boat 18 vertically and to close the lower end of the processing furnace 19. Has been.

  The boat 18 has a plurality of holding members, and a plurality of (for example, about 50 to 150) wafers 2 are horizontally held in a state in which the wafers 2 are aligned in the center and vertically aligned. It is configured.

  Above the cassette shelf 7, a clean unit 25 composed of a supply fan and a dustproof filter is provided so as to supply clean air, which is a cleaned atmosphere, and clean air is placed inside the housing 4. It is configured to be distributed.

  Further, a clean unit 26 comprising a supply fan and a dustproof filter for supplying clean air to the left side end of the housing 4 opposite to the wafer transfer device elevator 16 and the boat elevator 22 side. The clean air blown out from the clean unit 26 flows through the wafer transfer device 15 and the boat 18, and then is sucked into an exhaust device (not shown) and exhausted outside the housing 4. It has become like that.

  Next, the operation of the substrate processing apparatus 1 will be described.

  The cassette 3 is loaded from a cassette loading / unloading port (not shown), and is placed on the cassette stage 6 so that the wafer 2 is in a vertical posture and the wafer loading / unloading port of the cassette 3 faces upward. Thereafter, the cassette 3 is placed behind the housing 4 so that the wafer 2 in the cassette 3 is placed in a horizontal posture by the cassette stage 6 and the wafer inlet / outlet of the cassette 3 faces the rear of the housing 4. It is rotated 90 ° clockwise.

  Next, the cassette 3 is automatically transported and delivered by the cassette transport device 12 to the designated shelf position of the cassette shelf 7 or the spare cassette shelf 11 and temporarily stored. From the cassette shelf 7 or the preliminary cassette shelf 11, the cassette is transferred to the transfer shelf 9 by the cassette transfer device 12 or directly transferred to the transfer shelf 9.

  When the cassette 3 is transferred to the transfer shelf 9, the wafers 2 are picked up from the cassette 3 by the tweezers 17 of the wafer transfer device 15 through the wafer loading / unloading port, and are placed behind the transfer shelf 9. The boat 18 is loaded. The wafer transfer device 15 that has transferred the wafer 2 to the boat 18 returns to the cassette 3 and loads the next wafer 2 into the boat 18.

  When a predetermined number of wafers 2 are loaded into the boat 18, the lower end portion of the processing furnace 19 closed by the furnace port shutter 21 is opened by the furnace port shutter 21. Subsequently, the boat 18 holding the group of wafers 2 is loaded into the processing furnace 19 as the seal cap 24 is raised by the boat elevator 22.

  After loading, arbitrary processing is performed on the wafer 2 in the processing furnace 19. After the processing, the wafer 2 and the cassette 3 are dispensed to the outside of the housing 4 in the reverse procedure to that described above.

  Next, the processing furnace 19 applied to the substrate processing apparatus 1 will be described with reference to FIGS. 2 to 4A and 4B.

  The substrate processing apparatus 1 has a controller 27 as a control unit, and the controller 27 controls operations of the respective parts constituting the substrate processing apparatus 1 and the processing furnace 19.

  A reaction tube 29 is provided as a reaction vessel for processing the wafer 2 as a substrate inside a heater 28 as a heating device (heating means), and a lower end opening of the reaction tube 29 is hermetically sealed by the seal cap 24 as a lid. A reaction chamber 32 is formed by at least the reaction tube 29 and the seal cap 24 and is hermetically closed through an O-ring 31 that is a member.

  The boat 18 is erected on the seal cap 24 via a boat support 33, and the boat support 33 is a holding body for holding the boat 18. A plurality of wafers 2 to be batch-processed are stacked in a multi-stage in the tube axis direction in the boat 18 on the boat 18. When the boat 18 is loaded into the reaction chamber 32, the wafers 2 are loaded by the heater 28. It is heated to a predetermined temperature.

  Two gas supply pipes 34 and 35 which are gas introduction portions are provided as supply paths for supplying a plurality of types of gases, here two types of gases, to the reaction chamber 32. From the first gas supply pipe 34, a first mass flow controller 36 which is a flow rate control device (flow rate control means) and a first valve 37 which is an on-off valve are formed in the reaction pipe 29 which will be described later. A processing gas is supplied to the reaction chamber 32 through the buffer chamber 38 formed. From the second gas supply pipe 35, a second mass flow controller 39, which is a flow rate control device (flow rate control means), a second valve 41, which is an on-off valve, a gas reservoir 42, and a second on-off valve. A processing gas is supplied to the reaction chamber 32 through a third valve 43 and a gas supply unit 44 described later.

  The reaction chamber 32 is connected to a vacuum pump 47 which is an exhaust device (exhaust means) through a fourth valve 46 by a gas exhaust pipe 45 for exhausting gas, and is evacuated. The fourth valve 46 is an on-off valve that can open and close the valve to evacuate and stop the evacuation of the reaction chamber 32, and further adjust the pressure by adjusting the valve opening.

  In the arc-shaped space between the inner wall of the reaction tube 29 and the wafer 2 constituting the reaction chamber 32, the inner wall above the lower part of the reaction tube 29 extends along the loading direction of the wafer 2. The buffer chamber 38 which is a gas dispersion space is provided, and a first gas supply hole 48 which is a supply hole for supplying gas is formed at the end of the wall adjacent to the wafer 2 of the buffer chamber 38. Has been. The first gas supply hole 48 opens toward the center of the reaction tube 29, and the first gas supply hole 48 has the same opening area from the lower part to the upper part, and the same. Drilled at an opening pitch.

  A rectangular hole 49 is formed in the bottom surface of the end of the buffer chamber 38 opposite to the end where the first gas supply hole 48 is provided. A circular hole 51 is formed in the side wall of the buffer chamber 38 in the vicinity of the square hole 49, which is a drain hole for applying a pressure to the buffer chamber 38 to efficiently discharge the chemical solution. The diameters of the square hole 49 and the circular hole 51 are larger than the diameter of the first gas supply hole 48, and the buffer chamber 38 and the reaction chamber are interposed via the square hole 49 and the circular hole 51. 32 communicates.

  Further, in the vicinity of the square hole 49 and the circular hole 51, a nozzle 52 is disposed from the lower part to the upper part of the reaction tube 29 along the loading direction of the wafer 2. The nozzle 52 has a plurality of second gas supply holes 53 which are supply holes for supplying gas to the buffer chamber 38. The opening area of the second gas supply hole 53 may be the same opening area and the same opening pitch from the upstream side to the downstream side of the gas when the differential pressure between the buffer chamber 38 and the reaction chamber 32 is small. However, when the differential pressure is large, it is desirable to increase the opening area from the upstream side to the downstream side or to reduce the opening pitch.

  In this embodiment, the opening area of the second gas supply hole 53 is gradually increased from the upstream side to the downstream side. With this configuration, gas having a flow rate of approximately the same amount is ejected from the second gas supply hole 53 into the buffer chamber 38, although the flow rate is substantially the same.

  Further, after the difference in the particle velocity of the gas ejected from the second gas supply holes 53 is alleviated in the buffer chamber 38, the first gas supply holes 48, the square holes 49, and the circular holes. 51 is ejected into the reaction chamber 32. Therefore, the gas ejected from each second gas supply hole 53 can be a gas having a uniform flow rate and flow velocity when ejected from each first gas supply hole 48.

  Further, in the buffer chamber 38, a first rod-shaped electrode 54 which is a first electrode having an elongated structure and a second rod-shaped electrode 55 which is a second electrode protect the electrode from the top to the bottom. Protected by an electrode protection tube 56 that is a tube, either the first rod-shaped electrode 54 or the second rod-shaped electrode 55 is connected to a high-frequency power source 58 via a matching unit 57, and the other is Connected to ground, which is the reference potential. As a result, plasma is generated in the plasma generation region 59 between the first rod-shaped electrode 54 and the second rod-shaped electrode 55.

  The periphery of the first rod-shaped electrode 54 and the second rod-shaped electrode 55 is covered with the electrode protection tube 56, respectively, and the atmosphere of the buffer chamber 38, the first rod-shaped electrode 54, and the second rod-shaped electrode 55 is in an isolated state, and the first rod-like electrode 54 and the second rod-like electrode 55 can be inserted into the buffer chamber 38 while being separated from the atmosphere of the buffer chamber 38. . At this time, if the inside of the electrode protection tube 56 has the same atmosphere as the outside air (atmosphere), the first rod-shaped electrode 54 and the second rod-shaped electrode 55 respectively inserted into the electrode protection tube 56 are the heater. It is oxidized by heating 28. Therefore, the inside of the electrode protection tube 56 is filled or purged with an inert gas such as nitrogen, and the oxygen concentration is kept sufficiently low to prevent oxidation of the first rod-shaped electrode 54 or the second rod-shaped electrode 55. An inert gas purge mechanism is provided.

  Further, the gas supply unit 44 is provided on an inner wall obtained by turning the inner periphery of the reaction tube 29 from the position of the first gas supply hole 48 by a required angle, for example, about 120 ° counterclockwise. The gas supply unit 44 shares the gas supply type with the buffer chamber 38 when alternately supplying a plurality of types of gases one by one to the wafer 2 in film formation by an ALD (Atomic Layer Deposition) method. Supply section.

  Similarly to the buffer chamber 38, the gas supply unit 44 has third gas supply holes 61 that supply gas at the same pitch at positions adjacent to the wafer 2, and the second gas is provided at the lower part. A supply pipe 35 is connected.

  The opening area of the third gas supply hole 61 is the same and the same opening area from the upstream side to the downstream side of the gas when the differential pressure in the gas supply unit 44 and the reaction chamber 32 is small. A pitch may be used, but when the differential pressure is large, it is desirable to increase the opening area from the upstream side to the downstream side or to decrease the opening pitch.

  In this embodiment, the opening area of the third gas supply hole 61 is gradually increased from the upstream side to the downstream side.

  In the central portion of the reaction tube 29, the boat 18 for mounting a plurality of wafers 2 in multiple stages at the same interval is provided. The boat 18 is connected to the reaction tube by a boat elevator 22 (see FIG. 1). You can enter and exit 29. In order to improve the uniformity of processing, a boat rotation mechanism 62 which is a rotation device (rotation means) for rotating the boat 18 is provided below the seal cap 24, and the boat rotation mechanism 62 is provided. , The boat 18 held on the boat support 33 is rotated.

  The controller 27 serving as a control means includes the first and second mass flow controllers 36 and 39, the first to fourth valves 37, 41, 43, and 46, the heater 28, the vacuum pump 47, and the boat rotation. It is connected to the mechanism 62, the boat elevator 22, the high-frequency power source 58, and the matching unit 57, and adjusts the flow rate of the first and second mass flow controllers 36, 39, and the first to third valves 37, 41. 43, opening and closing of the fourth valve 46 and pressure adjusting operation, adjusting the temperature of the heater 28, starting and stopping the vacuum pump 47, adjusting the rotational speed of the boat rotating mechanism 62, adjusting the boat elevator 22 Ascent / descent operation control, power supply control of the high-frequency power source 58, and impedance control by the matching unit 57 are performed.

  Next, an example of film formation by the ALD method will be described as an example of forming a SiN (silicon nitride) film using DCS (SiH2 Cl2, dichlorosilane) and NH3 (ammonia) gas, which is one of the semiconductor device manufacturing processes. To do.

  The ALD method, which is one of the CVD (Chemical Vapor Deposition) methods, uses two or more kinds of processing gases used for film formation one by one under certain film formation conditions (temperature, time, etc.). In this method, the film is alternately supplied onto the substrate, adsorbed in units of one atomic layer, and a film is formed using a surface reaction.

  For example, in the case of SiN film formation, high-quality film formation is possible at a low temperature of 300 to 600 ° C. using DCS and NH 3 in the ALD method. Further, the gas supply alternately supplies a plurality of types of reactive gases one by one. The film thickness is controlled by the number of reactive gas supply cycles. For example, assuming that the film formation rate is 1 cm / cycle, the process is performed 20 cycles when a film of 20 cm is generated.

  First, the wafer 2 to be deposited is loaded into the boat 18 and carried into the reaction chamber 32. After loading, the following three steps are executed in sequence.

(Step 1)
In step 1, NH3 gas necessary for plasma excitation and DCS gas that does not require plasma excitation are flowed in parallel. First, the first valve 37 provided in the first gas supply pipe 34 and the fourth valve 46 provided in the gas exhaust pipe 45 are both opened, and the first gas supply pipe 34 opens the first valve. The NH 3 gas whose flow rate is adjusted by the mass flow controller 36 is jetted from the second gas supply hole 53 of the nozzle 52 to the buffer chamber 38.

  NH3 jetted into the buffer chamber 38 is plasma-excited by applying high-frequency power from the high-frequency power source 58 via the matching unit 57 between the first rod-shaped electrode 54 and the second rod-shaped electrode 55. Then, the gas is exhausted from the gas exhaust pipe 45 while being supplied to the reaction chamber 32 as active species.

  At this time, NH3 is supplied to the reaction chamber 32 through the first gas supply hole 48, the rectangular hole 49, and the circular hole 51, but the active species loses energy as it moves, and the rectangular hole 49 and the circular hole 51 are formed at positions away from the plasma region 59 where NH3 is plasma-excited, so that the active species are separated from the plasma region 59 to the square hole 49 and the circular hole 51. When energy is lost and gas is supplied from the square hole 49 and the circular hole 51 to the reaction chamber 32, the energy is lost.

  When flowing NH3 as an active species by plasma excitation, the pressure in the reaction chamber 32 is maintained within a range of 10 to 100 Pa, for example, 50 Pa by adjusting the fourth valve 46 appropriately. The supply flow rate of NH3 controlled by the first mass flow controller 36 is in the range of 1 to 10 slm, for example, supplied at 5 slm. The time for exposing the wafer 2 to the active species obtained by plasma excitation of NH3 is 2 to 120 seconds. The temperature of the heater 28 at this time is set so that the wafer 2 is in the range of 300 to 600 ° C., for example, 550 ° C. Normally NH3 has a high reaction temperature and does not react at the temperature of the wafer 2 described above. Therefore, the plasma is excited so that it flows as an active species. By flowing as an active species, the temperature of the wafer 2 falls within a set low temperature range. Can be done as is.

  When supplying NH3 as an active species to the reaction chamber 32, the second valve 41 on the upstream side of the second gas supply pipe 35 is opened, and the third valve 43 on the downstream side is closed, Make DCS flow. As a result, DCS is stored in a gas reservoir 42 provided between the second and third valves 41 and 43. At this time, the gas flowing in the reaction chamber 32 is an active species obtained by plasma-exciting NH3, and DCS does not exist. Accordingly, NH3 does not cause a gas phase reaction, and NH3 which is excited by plasma and becomes active species reacts with the surface portion of the wafer 2 such as a base film (chemical adsorption).

(Step 2)
In Step 2, the first valve 37 of the first gas supply pipe 34 is closed and the supply of NH3 is stopped, but the supply to the gas reservoir 42 is continued. When a predetermined pressure and a predetermined amount of DCS have accumulated in the gas reservoir 42, the second valve 41 on the upstream side is also closed, and the DCS is confined in the gas reservoir 42. Further, the fourth valve 46 of the gas exhaust pipe 45 is kept open, the reaction chamber 32 is exhausted to 20 Pa or less by the vacuum pump 47, and residual NH3 is removed from the reaction chamber 32. At this time, by supplying an inert gas such as N2 to the reaction chamber 32, the effect of eliminating residual NH3 is further enhanced. DCS is stored in the gas reservoir 42 so that the pressure is 20000 Pa or more. The apparatus is configured so that the conductance between the gas reservoir 42 and the reaction chamber 32 is 1.5 × 10 ⁻³ m ³ / s or more. Considering the ratio between the volume of the reaction tube 29 and the volume of the gas reservoir 42 required for the reaction tube 29, when the volume of the reaction tube 29 is 100 l (liter), 100 to 300 cc is preferable, and the volume ratio of the gas reservoir 42 is preferably 1/1000 to 3/1000 times the volume of the reaction chamber 32.

(Step 3)
In step 3, when the exhaust of the reaction chamber 32 is finished, the fourth valve 46 of the gas exhaust pipe 45 is closed to stop the exhaust, and the third valve 43 on the downstream side of the second gas supply pipe 35 is stopped. open. As a result, the DCS stored in the gas reservoir 42 is supplied to the reaction chamber 32 at once. At this time, since the fourth valve 46 of the gas exhaust pipe 45 is closed, the pressure in the reaction chamber 32 rapidly increases and is increased to about 931 Pa (7 Torr). The time for supplying DCS was set to 2 to 4 seconds, and then the time for exposure to the increased pressure atmosphere was set to 2 to 4 seconds, for a total of 6 seconds. At this time, the temperature of the wafer 2 is maintained at a desired temperature within the range of 300 to 600 ° C., as in the case of supplying NH 3. By supplying DCS, NH 3 chemically adsorbed on the surface of the wafer 2 and DCS undergo a surface reaction (chemical adsorption), and a SiN film is formed on the wafer 2. After the film formation, the third valve 43 is closed, the fourth valve 46 is opened, and the reaction chamber 32 is evacuated to remove the gas after contributing to the film formation of the remaining DCS. At this time, if an inert gas such as N2 is supplied to the reaction chamber 32, the effect of removing the remaining gas after contributing to the film formation of DCS from the reaction chamber 32 is enhanced. In addition, the second valve 41 is opened to start supplying DCS to the gas reservoir 42.

  Steps 1 to 3 are defined as one cycle, and a SiN film having a predetermined thickness can be formed on the wafer 2 by repeating this cycle a plurality of times.

  In the ALD method, the gas is chemisorbed on the surface portion on the wafer 2. The amount of gas adsorption is proportional to the gas pressure and the gas exposure time. Therefore, in order to adsorb a desired amount of gas in a short time, it is necessary to increase the gas pressure in a short time. In this regard, in this embodiment, since the DCS accumulated in the gas reservoir 42 is instantaneously supplied after the fourth valve 46 is closed, the pressure of the DCS in the reaction chamber 32 is rapidly increased. The desired amount of gas can be instantaneously adsorbed.

  Further, in this embodiment, while DCS is stored in the gas reservoir 42, NH3 gas, which is a necessary step in the ALD method, is excited as plasma to supply it as an active species, and the reaction chamber 32 is exhausted. As a result, no special steps are required to accumulate DCS. Further, since the inside of the reaction chamber 32 is exhausted to remove NH3 gas and then DCS is flown, both do not react on the way to the wafer 2. The supplied DCS can be effectively reacted only with NH3 adsorbed on the wafer 2.

  Further, by forming the square hole 49 and the circular hole 51 at positions away from the plasma region 59, NH3 is decomposed when active species pass through the square hole 49 and the circular hole 51. No film is deposited around the square holes 49 and the circular holes 51 on the buffer chamber 38 side and the processing chamber 32 side, thereby preventing deterioration of the quality of the wafer 2 due to particles generated due to the films. Can do.

  In order to prevent film deposition, gas does not have to be decomposed when passing through the square hole 49 and the circular hole 51. Therefore, the plasma generation region 59, the square hole 49, and the circular hole 51 are not separated. As long as there is a distance that loses energy to decompose the gas.

  In this embodiment, the square hole 49 is drilled on the bottom surface near the nozzle 52 and the circular hole 51 is drilled on the side wall near the nozzle 52. The position may be reversed.

  Next, referring to FIGS. 5A and 5B, a second embodiment of the present invention will be described. 5A and 5B, the same components as those in FIGS. 4A and 4B are denoted by the same reference numerals, and the description thereof is omitted.

  In the second embodiment, the square hole 49 of the first embodiment is formed in the side wall of the buffer chamber 38 in the vicinity of the nozzle 52, that is, both the square hole 49 and the circular hole 51 are first in the buffer chamber 38. The gas supply hole 48 is formed on the side wall of the end opposite to the end provided with the gas supply hole 48.

  Both the square hole 49 and the circular hole 51 are formed in the side wall of the buffer chamber 38 in the vicinity of the nozzle 52, so that the square hole 49, the circular hole 51, the first bar electrode 54, and the second bar shape are formed. The distance from the plasma region 59 formed between the electrodes 55 is further increased compared to the first embodiment.

  Accordingly, in the process in which the energy of NH3 gas supplied to the buffer chamber 38 from the nozzle 52 and excited by plasma in the plasma region 59 reaches the square hole 49 and the circular hole 51. Further, since the film is lost, film deposition due to decomposition of NH3 gas does not occur in the square hole 49 and the circular hole 51, and deterioration of the quality of the wafer 2 due to particles generated by the film can be prevented.

  Next, with reference to FIGS. 6A and 6B, a third embodiment of the present invention will be described. 6A and 6B, the same components as those in FIGS. 4A and 4B are denoted by the same reference numerals, and the description thereof is omitted.

  In the third embodiment, a square hole 49 is formed in the side wall of the buffer chamber 38 near the nozzle 52.

  Accordingly, the distance between the square hole 49 and the plasma region 59 where the NH 3 gas supplied to the buffer chamber 38 is plasma-excited is increased, and the plasma-excited active species are passed through the square hole 49 through the reaction chamber 32 (FIG. 3), the energy of the active species is lost in the process from the plasma region 59 to the rectangular hole 49, and no film is deposited due to decomposition of NH3 gas in the rectangular hole 49. The quality deterioration of the wafer 2 due to particles generated due to the film can be prevented.

  In this embodiment, the square hole 49 is formed in the side wall of the buffer chamber 38 in the vicinity of the nozzle 52. However, the circular hole 51 may be formed in the side wall.

  In the first embodiment of the present invention, the case where the SiN film is generated has been described. However, the substrate processing apparatus 1 according to the present invention is not limited to the film type, and the film processing apparatus 1 is applicable to films other than the SiN film. However, it goes without saying that it is applicable.

DESCRIPTION OF SYMBOLS 1 Substrate processing apparatus 2 Wafer 34 1st gas supply pipe 35 2nd gas supply pipe 38 Buffer chamber 48 1st gas supply hole 49 Square hole 51 Circular hole 52 Nozzle 53 2nd gas supply hole 54 1st rod shape Electrode 55 Second rod-shaped electrode 59 Plasma generation region

Claims (1)

  A cylindrical reaction vessel, a reaction chamber defined inside the reaction vessel and capable of accommodating a plurality of substrates, a buffer chamber provided inside the reaction vessel, and provided along the longitudinal direction of the reaction vessel A gas introduction unit capable of introducing a processing gas into the buffer chamber, the buffer chamber having a plurality of gas supply holes for supplying the processing gas introduced from the gas introduction unit to the reaction chamber, and for generating plasma A substrate processing apparatus comprising: a space for accommodating the electrode; and at least one hole penetrating the side wall and opening into the reaction chamber.

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