JP2014143421A - Substrate processing device, semiconductor manufacturing method and substrate processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an operation rate of a substrate processing device by reducing maintenance frequency of cumulative film removal.SOLUTION: A substrate processing device comprises: a processing chamber 34 for accommodating a substrate holder 13 which holds a substrate 2, therein and forming a film over the substrate; heating means 32 for heating the substrate and an atmosphere within the processing chamber; gas supply means 35a, 35b for supplying gas into the processing chamber; gas exhaust means 42 for exhausting the gas out of the processing chamber; transfer means for transferring the substrate to the substrate holder; and a control section 31 for controlling the heating means, the gas supply means, the gas exhaust means and the transfer means so as to perform in parallel a transfer step of transferring the substrate from the substrate holder carried out of the processing chamber, and a foreign substance removal step of removing foreign substances within the processing chamber by raising a temperature within the processing chamber to a first temperature exceeding a processing temperature at which the substrate is processed, then lowering the temperature to a second temperature lower than the processing temperature and repeating pressure rise and fall within the processing chamber.

Description

The present invention relates to a substrate processing apparatus for performing processes such as thin film generation, oxidation, impurity diffusion, annealing, and etching on a substrate such as a silicon wafer.

As one of semiconductor manufacturing processes, there is a film forming process for depositing a predetermined thin film on a substrate by using a CVD (Chemical Vapor Deposition) method using plasma or an ALD (Atomic Layer Deposition) method.

The CVD method is a method for depositing a thin film having an element contained in a raw material molecule as a constituent element on a substrate to be processed by utilizing a gas phase and reaction at the surface of a gaseous raw material.

A CVD method in which thin film deposition is controlled at the atomic layer level is called an ALD method, and is characterized by a lower substrate temperature than the conventional CVD method.

Plasma is used to promote a chemical reaction of a thin film deposited by a CVD method, remove impurities from the thin film, or assist a chemical reaction of an adsorbed film forming material by an ALD method.

For example, an amorphous silicon nitride film (hereinafter abbreviated as SiN) is formed by ALD using DCS (dichlorosilane) and NH3 (ammonia) plasma at a substrate temperature of 650 ° C. or lower.

The process of forming SiN on the substrate includes a DCS irradiation process and an NH3 plasma irradiation process. By a process of repeating these two steps (hereinafter referred to as a cycle process), SiN having a predetermined film thickness can be deposited on the substrate. The ALD method is characterized in that the film thickness is controlled by the number of cycles.

However, such an ALD method has a drawback in that a thin film is cumulatively deposited on a portion in contact with a gas other than the substrate.

For this reason, the following problems are likely to occur.

Micro-cracks are generated in the accumulated film deposited on a portion other than the substrate, which is a contamination due to a foreign substance that is separated and floated. Contamination due to foreign matter is more likely to occur as the deposition rate during SiN deposition increases or as the cumulative film thickness increases. This is because the higher the deposition rate, the greater the amount of impurities mixed in the accumulated film, which is annealed by the thermal energy of the continuous film formation process, and the impurities are released, and the thermal contraction and thermal expansion are repeated. It is considered that microcracks are likely to occur.

Further, since the yield is extremely deteriorated when the accumulated film is increased to a certain amount, maintenance (NF3 cleaning or WET cleaning process) for periodically removing the accumulated film must be performed. Since the substrate processing apparatus is stopped at the time of maintenance, as a result, it becomes a big barrier for improving the operation rate and productivity of the apparatus.

JP 2000-306904 A

International Publication No. 2005/029566 Pamphlet

In view of such circumstances, the present invention is intended to improve the operating rate of the substrate processing apparatus by reducing the maintenance frequency of cumulative film removal.

The present invention accommodates a substrate holder holding a substrate, forms a film on the substrate, a heating means for heating the atmosphere of the substrate and the processing chamber, and supplies a gas into the processing chamber. A gas supply means; a gas discharge means for discharging the processing chamber; a transfer means for transferring the substrate to the substrate holder; and the substrate being transferred from the substrate holder carried out of the processing chamber. A transfer step, and after the temperature in the processing chamber is raised to a first temperature that exceeds the processing temperature for processing the substrate, the temperature is lowered to a second temperature lower than the processing temperature, and the processing chamber The heating means, the gas supply means, the gas discharge means, and the transfer means are controlled so that the foreign matter removal step of removing the foreign matter in the processing chamber is repeated in parallel with the pressure increase and decrease of the pressure. And a control unit Those of the plate processor.

According to the present invention, the substrate holder holding the substrate is accommodated, a processing chamber for forming a film on the substrate, a heating means for heating the atmosphere of the substrate and the processing chamber, and a gas into the processing chamber. Gas supply means for supplying; gas discharge means for discharging the processing chamber; transfer means for transferring the substrate to the substrate holder; and the substrate from the substrate holder carried out of the processing chamber. The transfer step of transferring, and after raising the temperature in the processing chamber to a first temperature exceeding the processing temperature for processing the substrate, the temperature is lowered to a second temperature lower than the processing temperature, and The heating means, the gas supply means, the gas discharge means, and the transfer means are performed in parallel with the foreign matter removal step of removing the foreign matter in the processing chamber by repeatedly increasing and decreasing the pressure in the processing chamber. Control. The generation of foreign substances from reaction products deposited on the walls of the chamber can be suppressed, the maintenance period for cumulative film removal can be extended, the frequency of maintenance can be reduced, and the operating rate of the substrate processing apparatus can be improved. Demonstrate the effect.

1 is a schematic perspective view of a substrate processing apparatus in which the present invention is implemented. It is a schematic sectional drawing of the processing furnace used for this substrate processing apparatus. It is an AA arrow line view of FIG. It is a schematic diagram of the substrate processing sequence of the present invention. It is a diagram which shows the furnace temperature change at the time of performing the foreign material removal process of this invention. It is a diagram which shows the pressure fluctuation in a furnace at the time of performing the foreign material removal process of this invention. It is a table | surface which shows the conditions of the Example of the foreign material removal process of this invention. It is a diagram which shows the foreign material generation | occurrence | production tendency at the time of repeating a film-forming process.

The best mode for carrying out the present invention will be described below with reference to the drawings.

First, referring to FIG. 1, an example of a substrate processing apparatus in which the present invention is implemented will be described.

In the following description, a case where a vertical substrate processing apparatus that performs oxidation, diffusion processing, CVD processing, or the like is applied to the substrate as the substrate processing apparatus will be described.

In the substrate processing apparatus 1 according to the present invention, the transfer of the wafer 2 made of silicon or the like is performed in a state where the wafer 2 is loaded in a cassette 3 as a substrate container.

In the figure, reference numeral 4 denotes a housing, and a cassette loading / unloading port 5 is opened on the front surface of the housing 4 so as to communicate with the inside and outside of the housing 4. The cassette loading / unloading port 5 has a front shutter ( (Not shown).

A cassette stage (substrate container delivery table) 6 is installed adjacent to the cassette carry-in / out port 5. The cassette 3 is carried onto the cassette stage 6 by an in-process carrying device (not shown) and unloaded from the cassette stage 6.

The cassette stage 6 is placed by the in-process transfer device so that the wafer 2 in the cassette 3 is in a vertical posture and the wafer inlet / outlet of the cassette 3 faces upward. The cassette stage 6 rotates the cassette 3 clockwise 90 ° to the rear of the casing 4, the wafer 2 in the cassette 3 is in a horizontal posture, and the wafer inlet / outlet of the cassette 3 is the casing 4. It is configured to be operable so as to face backward.

A cassette shelf (substrate container mounting shelf) 7 is installed at a substantially central portion in the front-rear direction in the housing 4. The cassette shelf 7 stores a plurality of cassettes 3 in a plurality of rows and a plurality of rows. 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 the wafer transfer mechanism (substrate transfer mechanism) 8 is stored.

Further, a spare cassette shelf 10 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) 21 is installed between the cassette stage 6 and the cassette shelf 7. The cassette transport device 21 includes a cassette elevator (substrate container lifting mechanism) 22 that can be moved up and down while holding the cassette 3, and a cassette transport mechanism (substrate container transport mechanism) 23 as a horizontal transport mechanism. The cassette 3 is transported between the cassette stage 6, the cassette shelf 7, and the spare cassette shelf 10 by the cooperation of the cassette elevator 22 and the cassette transport mechanism 23.

The wafer transfer mechanism 8 is installed behind the cassette shelf 7, and the wafer transfer mechanism 8 is a wafer transfer device (substrate transfer) capable of rotating and linearly moving the wafer 2 in the horizontal direction. Apparatus) 11 and a wafer transfer apparatus elevator (substrate transfer apparatus lifting mechanism) 12 for moving the wafer transfer apparatus 11 up and down. The wafer transfer device elevator 12 and the wafer transfer device 11 cooperate to load and unload the wafers 2 with respect to the boat 13.

A load lock chamber (not shown), which is an airtight pressure vessel, is provided at the rear of the housing 4, and a vertical processing furnace 15 is provided above the load lock chamber. The lower end of the processing furnace 15 is opened, the opening forms a furnace port, and the furnace port is configured to be opened and closed by a furnace port shutter (furnace port opening / closing mechanism) 16.

Inside the load lock chamber, there is provided a boat elevator (substrate holder lifting mechanism) 17 as a lifting mechanism for lifting and lowering the boat 13 to and from the processing furnace 15, and a boat arm 18 is provided from the boat elevator 17. The boat arm 18 is provided with a seal cap 19 that hermetically closes the furnace port, and the boat 13 is placed vertically on the seal cap 19.

The boat 13 is made of a material that does not contaminate the wafers 2 such as quartz, and holds the wafers 2 in multiple stages in a horizontal posture.

A clean unit 24 composed of a supply fan and a dustproof filter is provided above the cassette shelf 7 so as to supply clean air, which is a cleaned atmosphere, and the clean air is placed inside the casing 4. It is configured to be distributed.

In addition, a clean unit 25 composed of a supply fan and a dustproof filter is installed so as to face the wafer transfer device elevator 12 and supply clean air toward the wafer transfer device elevator 12. The clean air blown out from the unit 25 flows through the wafer transfer device 11 and the boat 13, and then is sucked into an exhaust device (not shown) and exhausted to the outside of the housing 4.

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

The cassette loading / unloading port 5 is opened by a front shutter (not shown). Thereafter, the cassette 3 is loaded from the cassette loading / unloading port 5 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. The cassette stage 6 mounts the cassette 3 so that the wafer 2 in the cassette 3 is in a horizontal posture and the wafer inlet / outlet of the cassette 3 faces the rear of the housing 4.

The cassette carrying device 21 carries the cassette 3 to a designated shelf position of the cassette shelf 7 or the spare cassette shelf 10. After the cassette 3 is temporarily stored in the cassette shelf 7 or the spare cassette shelf 10, the cassette 3 is transferred from the cassette shelf 7 or the spare cassette shelf 10 to the transfer shelf 9 by the cassette carrying device 21. Alternatively, it is conveyed directly from the cassette stage 6 to the transfer shelf 9.

When the cassette 3 is transferred to the transfer shelf 9, the wafer 2 is loaded (charged) from the cassette 3 to the boat 13 in the lowered state by the wafer transfer device 11. When the wafer 2 is transferred to the boat 13, the wafer transfer device 11 returns to the cassette 3 and loads the next wafer 2 into the boat 13.

When a predetermined number of wafers 2 are loaded into the boat 13, the furnace port shutter 16 opens the furnace port. Subsequently, the boat 13 holding the group of wafers 2 is loaded into the processing furnace 15 when the seal cap 19 is lifted by the boat elevator 17.

After the charging, an arbitrary process is performed on the wafer 2 in the processing furnace 15.

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 15 will be described with reference to FIGS.

The substrate processing apparatus 1 includes a controller 31 as control means. The controller 31 controls the operation of each part of the substrate processing apparatus 1 and the processing furnace 15 and controls supply of process gas, and a heater 32. The heating control of the wafer 2, the processing chamber 33, and the reaction tube 34, and the gas exhaust control of the processing chamber 33 are performed.

The reaction tube 34 defining the processing chamber 33 is concentrically provided inside the heater 32 which is a heating device, and the reaction tube 34 processes the wafer 2 and performs a required process. The lower end opening of the reaction tube 34 is hermetically closed by the seal cap 19 that is a lid, and at least the reaction tube 34 and the seal cap 19 form the processing chamber 33. The heater 32, a temperature sensor (not shown) for detecting the temperature of the processing chamber 33, and the like constitute a heating means.

The boat 13 is erected on the seal cap 19 via a boat support 20, and the boat support 20 is a holding body that holds the boat 13. The boat 13 is loaded with a plurality of wafers 2 to be batch-processed in a horizontal posture in a multi-stage in the tube axis direction, loaded into the processing chamber 33 by the boat elevator 17, and the heater 32 loaded. Is heated to a predetermined temperature.

The processing chamber 33 is provided with two gas supply pipes 35a and 35b as supply paths for supplying a plurality of types, here two types of gases. Here, a buffer formed in the reaction tube 34, which will be described later, from the first gas supply pipe 35a through a first mass flow controller 36a which is a flow rate control device (flow rate control means) and a first valve 37a which is an on-off valve. A reaction gas is supplied to the processing chamber 33 through the chamber 38, and a second mass flow controller 36b, which is a flow rate control device (flow rate control means), a second valve 37b, which is an on-off valve, from the second gas supply pipe 35b. A reactive gas is supplied to the processing chamber 33 through a gas reservoir 39 and a third valve 37c, which is an on-off valve, and a gas supply unit 41 described later.

The reaction tube 34 is connected to a vacuum pump 43, which is an exhaust device, through a fourth valve 37d by a gas exhaust tube 42 for exhausting gas, and is evacuated. The fourth valve 37d is an open / close valve that can be opened / closed to stop evacuation / evacuation of the processing chamber 33, and further adjust the pressure by adjusting the valve opening. The gas exhaust pipe 42, the vacuum pump 43, the fourth valve 37d and the like constitute gas exhaust means.

In the arc-shaped space between the inner wall of the reaction tube 34 and the wafer 2, the buffer chamber which is a gas dispersion space along the loading direction of the wafer 2 on the inner wall above the lower part of the reaction tube 34. 38 is provided, and a first gas supply hole 44a, which is a supply hole for supplying gas, is provided at the end of the wall of the buffer chamber 38 adjacent to the wafer 2. The first gas supply hole 44 a opens toward the center of the reaction tube 34. The first gas supply holes 44a have the same opening area from the lower part to the upper part, and are provided at the same opening pitch.

At the end of the buffer chamber 38 opposite to the end where the first gas supply hole 44 a is provided, a nozzle 45 is arranged along the stacking direction of the wafer 2 from the lower part to the upper part of the reaction tube 34. It is installed. The nozzle 45 is provided with a second gas supply hole 44b which is a supply hole for supplying a plurality of gases. When the differential pressure between the buffer chamber 38 and the processing chamber 33 is small, the second gas supply hole 44b has the same opening area and the same opening pitch from the upstream side to the downstream side of the gas. Although it is good, when the differential pressure is large, the opening area should be increased from the upstream side to the downstream side, or the opening pitch should be reduced.

In the present embodiment, the opening area of the second gas supply hole 44b is gradually increased from the upstream side to the downstream side. With this configuration, the gas having the same flow rate is ejected from the second gas supply holes 44b to the buffer chamber 38 with the same flow rate.

In the buffer chamber 38, after the difference in the particle velocity of the gas ejected from the second gas supply holes 44b is alleviated, the gas is ejected from the first gas supply holes 44a to the processing chamber 33. Therefore, the gas ejected from each second gas supply hole 44b can have a uniform flow rate and flow velocity when ejected from each first gas supply hole 44a.

Further, in the buffer chamber 38, the first rod-shaped electrode 46, which is a first electrode having an elongated structure, and the second rod-shaped electrode 47, which is a second electrode, are electrode protections which are protective tubes that protect the electrode from the upper part to the lower part. Protected by a tube 48, either the first rod-shaped electrode 46 or the second rod-shaped electrode 47 is connected to a high-frequency power source 51 through a matching unit 49, and the other is connected to a ground that is a reference potential. Has been. As a result, plasma is generated in the plasma generation region 52 between the first rod-shaped electrode 46 and the second rod-shaped electrode 47.

The electrode protection tube 48 has a structure in which each of the first rod-shaped electrode 46 and the second rod-shaped electrode 47 can be inserted into the buffer chamber 38 while being isolated from the atmosphere of the buffer chamber 38. Here, if the inside of the electrode protection tube 48 has the same atmosphere as the outside air (atmosphere), the first rod-shaped electrode 46 and the second rod-shaped electrode 47 respectively inserted into the electrode protection tube 48 are connected to the heater 32. It is oxidized by heating. Therefore, the inside of the electrode protection tube 48 is filled or purged with an inert gas such as nitrogen to prevent the oxidation of the first rod-shaped electrode 46 or the second rod-shaped electrode 47 by suppressing the oxygen concentration sufficiently low. An inert gas purge mechanism is provided.

Further, the gas supply unit 41 is provided on the inner wall of the reaction tube 34 that is rotated about 120 ° from the position of the first gas supply hole 44a. The gas supply unit 41 is a supply unit that shares the gas supply species with the buffer chamber 38 when a plurality of types of gases are alternately supplied to the wafer 2 one by one in the film formation by the ALD method.

Similarly to the buffer chamber 38, the gas supply unit 41 has third gas supply holes 44c that supply gas at the same pitch at positions adjacent to the wafer 2, and the second gas supply pipe 35b at the bottom. Is connected.

When the differential pressure in the gas supply unit 41 and the processing chamber 33 is small, the opening area of the third gas supply hole 44c has the same opening area and the same opening pitch from the upstream side to the downstream side of the gas. However, when the differential pressure is large, it is preferable to increase the opening area or reduce the opening pitch from the upstream side toward the downstream side.

In the present embodiment, the opening area of the third gas supply hole 44c is gradually increased from the upstream side to the downstream side.

The boat 13 on which a plurality of wafers 2 are placed in multiple stages at the same interval is accommodated in the center of the reaction tube 34, and the boat 13 is loaded into and removed from the reaction tube 34 by the boat elevator 17. It has become like that. Further, in order to improve the uniformity of processing, a boat rotation mechanism 53 which is a rotation device (rotation means) for rotating the boat 13 is provided. By rotating the boat rotation mechanism 53, the boat support base is rotated. The boat 13 held at 20 is rotated.

The controller 31 includes the first and second mass flow controllers 36a and 36b, the first to fourth valves 37a, 37b, 37c, and 37d, the heater 32, the vacuum pump 43, the boat rotating mechanism 53, and the boat elevator. 17, connected to the high-frequency power source 51 and the matching unit 49, to adjust the flow rate of the first and second mass flow controllers 36a, 36b, to open / close the first to third valves 37a, 37b, 37c, Opening / closing and pressure adjusting operation of the 4-valve 37d, temperature adjustment of the heater 32, starting / stopping of the vacuum pump 43, rotation speed adjustment of the boat rotating mechanism 53, raising / lowering operation control of the boat elevator 17, and the high frequency power supply 51 Power supply control and impedance control by the matching unit 49 are performed.

Next, an example of film formation by the ALD method will be described using an example of forming a SiN film using DCS (dichlorosilane) and NH3 (ammonia) gas, which is one of the semiconductor device manufacturing steps.

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

For example, in the case of SiN (silicon nitride) film formation, high-quality film formation is possible at a low temperature of 300 ° C. to 600 ° C. using DCS and NH 3 in the ALD method. The gas supply alternately supplies a plurality of types of reactive gases one by one. And film thickness control is controlled by the cycle number of reactive gas supply. (For example, if the deposition rate is 1 mm / cycle, the process is performed 20 cycles when a film of 20 mm is formed.)

First, the wafer 2 to be formed is loaded into the boat 13 and carried into the processing chamber 33. After carrying in, the following three steps are sequentially executed.

(Step 1) In Step 1, NH3 gas that requires plasma excitation and DCS gas that does not require plasma excitation are allowed to flow in parallel. First, the first valve 37a provided in the first gas supply pipe 35a and the fourth valve 37d provided in the gas exhaust pipe 42 are both opened, and the first mass flow controller 36a is connected from the first gas supply pipe 35a. The NH 3 gas whose flow rate has been adjusted by the nozzle 45 is ejected from the second gas supply hole 44 b of the nozzle 45 to the buffer chamber 38, and the alignment from the high frequency power source 51 between the first rod-shaped electrode 46 and the second rod-shaped electrode 47 A high frequency power is applied through a vessel 49 to excite NH3 plasma, and the exhaust gas is exhausted from the gas exhaust pipe 42 while being supplied to the processing chamber 33 as active species. When flowing NH3 gas as an active species by plasma excitation, the fourth valve 37d is adjusted appropriately to maintain the pressure in the processing chamber 33 within a range of 10 to 100 Pa, for example, 40 Pa. The supply flow rate of NH3 controlled by the first mass flow controller 36a is in the range of 1 to 10 slm. Seconds. The temperature of the heater 32 at this time is set so that the wafer 2 is in the range of 300 ° C. to 600 ° C., for example, 600 ° C. Since NH3 has a high reaction temperature, it does not react at the above temperature. Therefore, NH3 is flowed as an active species by plasma excitation. Therefore, the temperature of the wafer 2 can be maintained in the set low temperature range.

When this NH3 is supplied as an active species by plasma excitation, the second valve 37b on the downstream side of the second gas supply pipe 35b is opened, the third valve 37c on the downstream side is closed, and the DCS is also Make it flow. Thus, DCS is stored in the gas reservoir 39 provided between the second valve 37b and the third valve 37c. At this time, the gas flowing in the processing chamber 33 is an active species obtained by exciting NH3 with plasma, and DCS does not exist. Accordingly, NH3 does not cause a gas phase reaction, and NH3 excited by plasma to become an active species undergoes surface reaction (chemical adsorption) with a surface portion such as a base film on the wafer 2.

(Step 2) In Step 2, the first valve 37a of the first gas supply pipe 35a is closed to stop the supply of NH3, but the supply to the gas reservoir 39 is continued. When a predetermined pressure and a predetermined amount of DCS are accumulated in the gas reservoir 39, the second valve 37b on the upstream side is also closed, and the DCS is confined in the gas reservoir 39. Further, the fourth valve 37d of the gas exhaust pipe 42 is kept open, and the processing chamber 33 is evacuated to 20 Pa or less by the vacuum pump 43, and residual NH3 is removed from the processing chamber 33. At this time, if an inert gas such as N2 is supplied to the processing chamber 33, the effect of eliminating residual NH3 is further enhanced. DCS is stored in the gas reservoir 39 so that the pressure is 20000 Pa or more. The apparatus is configured so that the conductance between the gas reservoir 39 and the processing chamber 33 is 1.5 × 10 ⁻³ m ³ / s or more. Considering the ratio between the volume of the reaction tube 34 and the volume of the gas reservoir 39 required for this, when the volume of the reaction tube 34 is 100 l (liter), it is 100 to 300 cc. The volume ratio of the gas reservoir 39 is preferably 1/1000 to 3/1000 times the reaction chamber volume.

(Step 3) In step 3, when the exhaust of the processing chamber 33 is finished, the fourth valve 37d of the gas exhaust pipe 42 is closed to stop the exhaust. The third valve 37c on the downstream side of the second gas supply pipe 35b is opened. As a result, the DCS stored in the gas reservoir 39 is supplied to the processing chamber 33 at once. At this time, since the fourth valve 37d of the gas exhaust pipe 42 is closed, the pressure in the processing chamber 33 is rapidly 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 ° C. 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 37c is closed, the fourth valve 37d is opened, and the processing chamber 33 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 processing chamber 33, the effect of removing the remaining gas after contributing to the deposition of DCS from the processing chamber 33 is enhanced. Also, the second valve 37b is opened to start supplying DCS to the gas reservoir 39.

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

In the ALD apparatus, the gas is chemisorbed on the surface portion of the wafer 2. The amount of gas adsorption is proportional to the gas pressure and the gas exposure time. Therefore, in order to adsorb the desired amount of gas in a short time, it is necessary to increase the gas pressure in a short time. In this regard, in the present embodiment, since the DCS accumulated in the gas reservoir 39 is instantaneously supplied after the fourth valve 37d is closed, the pressure of the DCS in the processing chamber 33 is reduced. It can be raised rapidly and a desired amount of gas can be adsorbed instantaneously.

Further, in the present embodiment, while DCS is stored in the gas reservoir 39, NH3 gas, which is a necessary step in the ALD method, is excited as a plasma by supplying it as an active species and exhausting the processing chamber 33. As a result, no special steps are required to store the DCS. Further, since the inside of the processing chamber 33 is evacuated to remove NH3 gas and then DCS is flowed, 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.

As described above, as a sequence for processing the substrate, the boat 13 is loaded from the cassette 3 of the transfer shelf 9 into the boat 13 by the wafer transfer device 11 and is loaded into the processing furnace 15 by the boat elevator 17. Loading, heating and heating of the wafer 2, ALD cycle processing, gas exhaust processing of the processing chamber 33, withdrawal of the boat 13 from the processing chamber 33, cooling processing of the processed wafer 2, and the wafer transfer device 11 The process of discharging the substrate from the boat 13 to the cassette 3 of the transfer shelf 9 and the loading of the unprocessed wafer 2 into the cassette 3 for further processing are sequentially repeated.

FIG. 4 schematically shows a sequence of substrate processing, and a substrate cooling process and a substrate transport process are interposed between the film forming process and the film forming process. In the present invention, the foreign matter removing process is executed by using the time during which the substrate cooling process and the substrate transport process are executed. Therefore, time does not increase in the entire substrate processing sequence.

The foreign matter removing process of the present invention will be described with reference to FIGS. 5 and 6 while comparing with a conventional substrate processing sequence.

The foreign matter removing process of the present invention is executed by a combination of temperature control including a rapid temperature raising process, a rapid temperature lowering process, and a recovery process, and further pressure control that gives a large pressure fluctuation in a short cycle to the pressure in the processing chamber 33. The

First, FIG. 5 shows temperature control. In the figure, a line A shown by a solid line shows a temperature change of the processing chamber 33 according to the present invention, and a line B shown by a broken line in the figure shows a temperature in a conventional process. It shows a change.

In the conventional temperature control, after the film formation process, the temperature gradually decreases to the STANDBY temperature, and the STANDBY temperature is maintained until the next film formation process is started.

In the present invention, after the film formation process, the temperature is rapidly increased by ΔT1 from the film formation temperature, and further, the temperature is rapidly decreased by ΔT2. ΔT2 is a large temperature difference exceeding 400 ° C., and the accumulated film is rapidly changed in temperature, thereby causing thermal damage and reducing the film stress. Further, the temperature is raised by ΔT3 and recovered to the STANDBY temperature.

It is conceivable that cracks are generated in the accumulated film by causing thermal damage to the accumulated film due to temperature rise and fall, and there are cases where foreign matter increases with the occurrence of cracks.

In order to remove the foreign matter, in parallel with the foreign matter removal step, the pressure in the processing chamber is subjected to a large pressure fluctuation in a short cycle, and the foreign matter is exhausted.

FIG. 6 shows the pressure fluctuation in the processing chamber when the pressure control (ATMVAC) in the processing chamber is executed in parallel with the temperature control during the foreign substance removing step. In the figure, a diagram A shown by a solid line shows a pressure fluctuation in the processing chamber according to the present invention, and a diagram B shown by a broken line in the figure shows a pressure fluctuation in the processing chamber in a conventional process.

Conventionally, after the film formation process, the pressure is returned to atmospheric pressure and the atmospheric pressure state is maintained. However, in the present invention, after the pressure is returned to atmospheric pressure, the pressure is further reduced to a pressure near the film formation process, and the negative pressure state is maintained. Gives a large pressure fluctuation in a short cycle. The pressure control executed in the rapid cooling step is ATMVAC1, the pressure fluctuation range at this time is ΔP1, and the pressure control executed in the recovery process is ATMVAC2, and the pressure fluctuation range at this time is ΔP2.

In the drawing, the pressure fluctuation range is gradually decreased (ΔP1> ΔP2), but the pressure fluctuation range may be constant or may be increased gradually. The mode of the pressure fluctuation is determined in accordance with the removal state of the foreign matter.

Moreover, since the peeled foreign matter is an insulating material mainly composed of Si, N, and O, it is likely to be charged and is presumed to be adsorbed on the accumulated film, the reaction tube wall surface, and the like. Therefore, in order to efficiently remove the adsorbed foreign matter, plasma is temporarily generated during the foreign matter removing step to perform static elimination. By performing the static elimination, the foreign matter removal efficiency is improved.

An example of foreign matter removal will be described with reference to FIGS.

In order to confirm the effect of the present invention, the foreign matter removing step was executed under the conditions shown in the table of FIG.

In this embodiment, the ATMVAC 1 controls the gas discharge means while introducing N2 into the reactor at a rate of 20 slm or more, and changes the pressure in the reactor between about 43,000 and 50 Pa (repetitive processing). ).

Similarly, ATMVAC2 is a process (repetitive process) in which N2 is introduced into the reactor at a rate of 20 slm or more while the exhaust means is controlled and the pressure in the reactor is varied between about 28000-50 Pa.

The pressure fluctuation speeds of ATMVAC1 and ATMVAC2 are both about 2666 Pa / s or more, and are executed in parallel with the rapid temperature increase process and the rapid temperature decrease process. As a result, the foreign substance removal and discharge process caused by the temperature change of the temperature increase / decrease temperature width ΔT is promoted by the change of the pressure fluctuation width ΔP.

FIG. 8 shows the tendency of foreign matter generation when the conventional foreign matter removing process is not repeated and only when the foreign matter removing sequence according to the present invention is added. The diagram B shows a conventional example.

As shown in the figure, in the past, the standard set value (SPEC Line) was exceeded every 4000 mm, and maintenance of cumulative film removal had to be performed, whereas in the present invention, the apparatus maintenance was improved every 6500 mm. We were able to. Therefore, the maintenance interval can be greatly extended. In addition, P / C number in a figure shows the number of the foreign materials on a board | substrate. The size of the foreign matter is, for example, 0.5 μm or more. Moreover, SPEC Line changes with apparatuses and methods which observe a foreign material. In FIG. 8, the line in which 20 foreign matters having a size of 0.5 μm or more are 20 is SPEC Line.

In addition, although the static elimination process by the said plasma processing is not included in the said Example, the generation | occurrence | production tendency of a foreign material can further be reduced by adding a static elimination process.

(Additional remarks) Moreover, this invention includes the following embodiments.

(Additional remark 1) The semiconductor manufacturing method characterized by interposing the foreign material removal process between the film-forming process and the film-forming process.

(Supplementary note 2) The semiconductor manufacturing method according to supplementary note 1, wherein the foreign matter removing step includes a temperature raising step, a temperature lowering step, and a recovery step.

(Supplementary note 3) The semiconductor according to supplementary note 1, wherein the foreign matter removing step includes a temperature raising step, a temperature lowering step, a recovery step, and a pressure fluctuation cycle step executed in parallel with the temperature raising step, the temperature lowering step, and the recovery step. Production method.

(Supplementary note 4) The semiconductor manufacturing method according to supplementary note 1, wherein neutralization is performed by temporarily generating plasma during the foreign substance removing step.

(Additional remark 5) The semiconductor manufacturing method of Additional remark 2 or Additional remark 3 whose temperature change of the said temperature rising process and the said temperature-fall process is 400 degreeC or more, and whose temperature change with the said temperature-fall process and the said recovery process is 250 degreeC or more.

(Additional remark 6) The semiconductor manufacturing method of Additional remark 3 whose pressure fluctuation range is 25000 Pa or more.

(Supplementary note 7) The semiconductor manufacturing method according to supplementary note 4, wherein the plasma is N2 plasma.

DESCRIPTION OF SYMBOLS 1 Substrate processing apparatus 2 Wafer 13 Boat 15 Processing furnace 31 Controller 32 Heater 33 Processing chamber 34 Reaction tube 35a
First gas supply pipe 35b Second gas supply pipe 37d Fourth valve 42 Gas exhaust pipe 43 Vacuum pump 46 First rod-shaped electrode 47 Second rod-shaped electrode 51 High-frequency power source 52 Plasma generation region

Claims (3)

A processing chamber for storing a substrate holder holding the substrate and forming a film on the substrate;
Heating means for heating the substrate and the atmosphere in the processing chamber;
Gas supply means for supplying gas into the processing chamber;
Gas discharge means for discharging the processing chamber;
Transfer means for transferring the substrate to the substrate holder;
A transfer step of transferring the substrate from the substrate holder carried out of the processing chamber, and the processing chamber is heated to a first temperature that exceeds a processing temperature for processing the substrate, and then the processing is performed. Reducing the temperature to a second temperature lower than the temperature, repeatedly increasing and decreasing the pressure in the processing chamber, and removing the foreign material in the processing chamber in parallel with the foreign matter removing step, so that the heating means, A substrate processing apparatus comprising: a gas supply unit; a control unit that controls the gas discharge unit and the transfer unit. A film forming step of forming a film on the substrate held by the substrate holder in the processing chamber;
A transfer step of transferring the substrate from the substrate holder carried out of the processing chamber;
After the temperature in the processing chamber is raised to a first temperature that exceeds the processing temperature for processing the substrate, the temperature is lowered to a second temperature lower than the processing temperature, and the pressure in the processing chamber is increased or decreased. And a foreign matter removing step for removing foreign matter in the processing chamber,
A method of manufacturing a semiconductor device, wherein the transfer step and the foreign matter removal step are performed in parallel. A transfer step of transferring the substrate from the substrate holder carried out of the processing chamber;
After the temperature in the processing chamber is raised to a first temperature that exceeds the processing temperature for processing the substrate, the temperature is lowered to a second temperature lower than the processing temperature, and the pressure in the processing chamber is increased or decreased. And a foreign matter removing step for removing foreign matter in the processing chamber,
The substrate processing method which performs the said transfer process and the said foreign material removal process in parallel.