JP5208294B2 - Semiconductor device manufacturing method, substrate processing method, and substrate processing apparatus - Google Patents

Description

  The present invention relates to a substrate processing method for forming a thin film by supplying a processing gas onto a substrate.

A semiconductor device such as a DRAM includes a silicon nitride film for covering a gate electrode and the like formed on a substrate. As a method for forming a silicon nitride film, for example, a first step of supplying dichlorosilane (SiH ₂ Cl _2, abbreviated as DCS) gas into a processing chamber containing a substrate, and a nitrogen gas is supplied into the processing chamber to supply a processing chamber. A second step of discharging DCS gas from the substrate, a third step of supplying ammonia (NH ₃ ) gas into the processing chamber to form a thin film on the substrate, and supplying nitrogen (N ₂ ) gas into the processing chamber. There is known an ALD (Atomic Layer Deposition) method in which the fourth step of discharging the second processing gas from the processing chamber is defined as one cycle and this cycle is repeated a predetermined number of times.

  A silicon oxide film such as a natural oxide film or a thermal oxide film may be formed on the substrate on which the silicon nitride film is formed. In order to remove the silicon oxide film, for example, an etching process using an HF-based solution is performed. In order to advance the miniaturization of a semiconductor device, it is necessary to form a thin silicon nitride film. At this time, in order to ensure the reliability of the semiconductor device, it is preferable that the etching amount of the silicon nitride film is small. That is, it is preferable that the etching rate of the silicon nitride film when etching the silicon oxide film is small.

  The etching rate of the silicon nitride film can be lowered by increasing the film formation temperature. However, when the deposition temperature is increased, the diffusion layer formed by diffusing impurities at a high concentration on the substrate is affected, and the reliability of the semiconductor device may be reduced. Therefore, the deposition temperature of the silicon nitride film is preferably low.

  An object of the present invention is to provide a substrate processing method capable of forming a silicon nitride film having a low etching rate with respect to an HF-based solution without increasing the film formation temperature.

According to one embodiment of the present invention,
A substrate processing method for forming a thin film on a substrate housed in a processing chamber,
A first step of supplying a first processing gas containing Cl element into the processing chamber;
A second step of supplying an inert gas into the processing chamber and discharging the first processing gas from the processing chamber;
A third step of supplying a second processing gas into the processing chamber to form a thin film on the substrate;
A fourth step of supplying an inert gas into the processing chamber and discharging a second processing gas from the processing chamber, and repeating this cycle a predetermined number of times as one cycle,
In the second step, there is provided a substrate processing method for continuously supplying an inert gas into the processing chamber even after the first processing gas is exhausted from the processing chamber.

  According to the substrate processing method of the present invention, it is possible to form a silicon nitride film having a low etching rate with respect to the HF-based solution without increasing the film formation temperature.

It is the schematic which illustrates the structure of the substrate processing apparatus concerning one Embodiment of this invention. It is a schematic block diagram of the processing furnace with which the substrate processing apparatus concerning one Embodiment of this invention is provided, (a) is the longitudinal cross-sectional schematic of a processing furnace, (b) is crossing of the processing furnace shown to Fig.1 (a). The surface schematic is shown, respectively. A graph showing an etching rate ratio of a silicon nitride film formed by a conventional ALD method at a film forming temperature of 525 ° C. and an etching rate ratio of a silicon nitride film formed by a conventional ALD method at a film forming temperature of 550 ° C. FIG. It is a graph which shows the etching rate ratio of the silicon nitride film formed at 525 degreeC, and the etching rate ratio of the silicon nitride film formed at 550 degreeC, respectively. It is the schematic which shows the process of etching a natural oxide film using HF system solution, (a) shows the case where the etching rate of a silicon nitride film is large, (a) shows the case where the etching rate of a silicon nitride film is small, Each is shown. It is a graph which shows the relationship between film-forming temperature and an etching rate ratio, and the relationship between film-forming temperature and Cl element concentration. It is a graph which shows the relationship between film-forming temperature and etching rate ratio, and the relationship between film-forming temperature and H element concentration, respectively. It is a schematic diagram which shows the implementation time of each process in the film-forming evaluation using ALD method, (a) is the case of the conventional substrate processing process, (b) extended the supply time of the 1st process gas. In the case of the substrate processing step, (c) shows the case of the substrate processing step in which the supply time of the second processing gas is extended, and (d) shows the case of the substrate processing step in which the supply time of the inert gas is extended. , Respectively. FIG. 8 is a graph showing an etching rate ratio and RI for each of the silicon nitride films formed by the substrate processing steps shown in FIGS. It is a table | surface figure which respectively shows the gas cost in each board | substrate processing process shown to Fig.7 (a)-(d). It is a graph which shows the relationship between the supply time of the nitrogen gas supplied at a 2nd process, and an etching rate ratio. FIG. 8 is a graph showing the Cl element concentration in the silicon nitride film formed by each substrate processing step shown in FIGS. FIG. 8 is a graph showing the concentration of H element in the silicon nitride film formed by each substrate processing step shown in FIGS. It is a graph which shows the measurement result of FTIR regarding the number of Si-N bonds about the silicon nitride film formed by each substrate processing process shown in Drawing 7 (a)-(d), respectively. (A) is the schematic which shows the substrate processing process which lengthened the supply time of the inert gas in a 2nd process, (b) is the substrate processing process which lengthened the supply time of the inert gas in a 4th process. FIG. The case where only the supply time of the inert gas in the second step is lengthened, the case where only the supply time of the inert gas in the fourth step is lengthened, and the inert gas in the second step and the fourth step It is a graph which shows the etching rate ratio of the silicon nitride film in the case where supply time is lengthened, respectively.

As described above, when the silicon oxide film is removed by etching, it is preferable that the etching amount of the silicon nitride film is small. Specifically, the etching rate ratio (WER = etching rate of silicon nitride film with respect to HF solution / etching rate of silicon oxide film with respect to HF solution) is preferably 0.2 or less. FIG. 4 is a schematic diagram showing a process of etching a natural oxide film formed on a silicon substrate using an HF-based solution. FIG. 4A shows a case where the etching rate of the silicon nitride film is high. Indicates a case where the etching rate of the silicon nitride film is low. As can be seen from FIG. 4, when the etching rate is high, even the silicon nitride film is etched when the silicon oxide film is etched, and the underlying gate electrode is exposed.

  Further, as described above, the etching rate of the silicon nitride film can be lowered by increasing the film formation temperature. FIG. 3 shows an etching rate ratio of a silicon nitride film formed by a conventional ALD method at a film formation temperature of 525 ° C., and an etching rate ratio of a silicon nitride film formed by a conventional ALD method at a film formation temperature of 550 ° C. FIG. According to FIG. 3, when the silicon nitride film is formed by the conventional ALD method at a film forming temperature of 525 ° C., the above-described etching rate ratio exceeds 0.4. On the other hand, it can be seen that the etching rate ratio can be reduced to about 0.2 by increasing the film forming temperature to about 550 ° C., for example. However, as described above, the film formation temperature of the silicon nitride film is preferably low, and the film formation temperature of 550 ° C. has become unacceptable from the viewpoint of ensuring reliability.

  Therefore, the inventors have conducted intensive research on a method for forming a silicon nitride film having a low etching rate with respect to the HF-based solution without increasing the film formation temperature. As a result, it has been found that the above-described problems can be solved by adjusting the supply amount or supply time of the inert gas in the second step.

In the conventional ALD method, the supply time of the nitrogen gas in the second step is a time necessary and sufficient for exhausting the DCS gas supplied in the first step from the processing chamber. If the supply time of the nitrogen gas in the second step is too short, DCS gas and ammonia gas are mixed in the processing chamber and the exhaust line, and reaction products such as NH ₄ Cl that cause particles are generated. Because it ends up. In particular, when DCS gas and ammonia gas are mixed in the downstream portion (atmospheric pressure portion) of the exhaust pump, a reaction product may be abnormally generated in the exhaust pump, leading to failure of the exhaust pump. On the other hand, if the supply time of the nitrogen gas in the second step is too long, the time required for one cycle becomes long, and the productivity of the substrate processing step is lowered.

  In contrast, the inventors reduced the Cl element concentration in the silicon nitride film by continuously supplying nitrogen gas into the processing chamber even after the DCS gas was discharged from the processing chamber in the second step, It has been found that the number of Si—N bonds can be increased and the etching rate for the HF-based solution can be reduced. Hereinafter, an embodiment of the present invention based on such knowledge will be described with reference to the drawings.

(1) Configuration of Substrate Processing Apparatus First, a configuration example of a substrate processing apparatus 101 according to an embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the substrate processing apparatus 101 according to the present embodiment includes a housing 111. In order to transport a wafer (substrate) 200 made of silicon or the like into and out of the casing 111, a cassette 110 as a wafer carrier (substrate storage container) that stores a plurality of wafers 200 is used. A cassette stage (substrate storage container delivery table) 114 is provided in front of the housing 111 (on the right side in the drawing). The cassette 110 is placed on the cassette stage 114 by an in-process transfer device (not shown), and is carried out of the casing 111 from the cassette stage 114.

The cassette 110 is placed on the cassette stage 114 so that the wafer 200 in the cassette 110 is in a vertical posture and the wafer loading / unloading port of the cassette 110 faces upward by the in-process transfer device. The cassette stage 114 rotates the cassette 110 90 degrees in the vertical direction toward the rear of the casing 111 to bring the wafer 200 in the cassette 110 into a horizontal posture, and the wafer loading / unloading port of the cassette 110 is placed behind the casing 111. It is configured to be able to face.

  A cassette shelf (substrate storage container mounting shelf) 105 is installed at a substantially central portion in the front-rear direction in the housing 111. The cassette shelf 105 is configured to store a plurality of cassettes 110 in a plurality of rows and a plurality of rows. The cassette shelf 105 is provided with a transfer shelf 123 in which a cassette 110 to be transferred by a wafer transfer mechanism 125 described later is stored. Further, a preliminary cassette shelf 107 is provided above the cassette stage 114, and is configured to store the cassette 110 in a preliminary manner.

  A cassette transfer device (substrate container transfer device) 118 is provided between the cassette stage 114 and the cassette shelf 105. The cassette transport device 118 includes a cassette elevator (substrate storage container lifting mechanism) 118a that can be moved up and down while holding the cassette 110, and a cassette transport mechanism (substrate storage container transport mechanism) as a transport mechanism that can move horizontally while holding the cassette 110. 118b. The cassette 110 is transported between the cassette stage 114, the cassette shelf 105, the spare cassette shelf 107, and the transfer shelf 123 by the cooperative operation of the cassette elevator 118a and the cassette transport mechanism 118b.

  A wafer transfer mechanism (substrate transfer mechanism) 125 is provided behind the cassette shelf 105. The wafer transfer mechanism 125 includes a wafer transfer device (substrate transfer device) 125a that can rotate or linearly move the wafer 200 in the horizontal direction, and a wafer transfer device elevator (substrate transfer device) that moves the wafer transfer device 125a up and down. Elevating mechanism) 125b. The wafer transfer device 125a includes a tweezer (substrate transfer jig) 125c that holds the wafer 200 in a horizontal posture. The wafer 200 is picked up from the cassette 110 on the transfer shelf 123 by the cooperative operation of the wafer transfer device 125a and the wafer transfer device elevator 125b, and loaded into the boat (substrate support member) 217 described later (charging). Or the wafer 200 is unloaded (discharged) from the boat 217 and stored in the cassette 110 on the transfer shelf 123.

  A processing furnace 202 is provided above the rear portion of the casing 111. An opening is provided at the lower end of the processing furnace 202, and the opening is configured to be opened and closed by a furnace port shutter (furnace port opening / closing mechanism) 147. The configuration of the processing furnace 202 will be described later.

  Below the processing furnace 202, a boat elevator (substrate support member elevating mechanism) 115 is provided as an elevating mechanism for moving the boat 217 up and down and carrying it in and out of the processing furnace 202. The elevator 128 of the boat elevator 115 is provided with an arm 128 as a connecting tool. On the arm 128, a seal cap 219 is provided in a horizontal posture as a lid that supports the boat 217 vertically and that hermetically closes the lower end of the processing furnace 202 when the boat 217 is raised by the boat elevator 115. ing.

  The boat 217 includes a plurality of holding members, and a plurality of (for example, about 50 to 150) wafers 200 are aligned in the vertical direction in a horizontal posture and in a state where the centers thereof are aligned in multiple stages. Configured to hold. The detailed configuration of the boat 217 will be described later.

  Above the cassette shelf 105, a clean unit 134a having a supply fan and a dustproof filter is provided. The clean unit 134a is configured to circulate clean air, which is a cleaned atmosphere, inside the casing 111.

  In addition, a clean unit (not shown) provided with a supply fan and a dustproof filter so as to supply clean air to the left end portion of the housing 111 opposite to the wafer transfer device elevator 125b and the boat elevator 115 side. Is installed. Clean air blown out from the clean unit (not shown) is configured to be sucked into an exhaust device (not shown) and exhausted to the outside of the casing 111 after circulating around the wafer transfer device 125a and the boat 217. ing.

(2) Operation of Substrate Processing Apparatus Next, the operation of the substrate processing apparatus 101 according to the present embodiment will be described.

  First, the cassette 110 is placed on the cassette stage 114 by an in-process transfer device (not shown) so that the wafer 200 is in a vertical posture and the wafer loading / unloading port of the cassette 110 faces upward. Thereafter, the cassette 110 is rotated 90 ° in the vertical direction toward the rear of the casing 111 by the cassette stage 114. As a result, the wafer 200 in the cassette 110 assumes a horizontal posture, and the wafer loading / unloading port of the cassette 110 faces rearward in the housing 111.

  The cassette 110 is automatically transported to the designated shelf position of the cassette shelf 105 or the spare cassette shelf 107 by the cassette transporting device 118, delivered, temporarily stored, and then stored in the cassette shelf 105 or the spare cassette shelf. The sample is transferred from 107 to the transfer shelf 123 or directly transferred to the transfer shelf 123.

  When the cassette 110 is transferred to the transfer shelf 123, the wafer 200 is picked up from the cassette 110 through the wafer loading / unloading port by the tweezer 125c of the wafer transfer device 125a, and the wafer transfer device 125a and the wafer transfer device elevator 125b are picked up. Are loaded (charged) into the boat 217 behind the transfer chamber 124. The wafer transfer mechanism 125 that has transferred the wafer 200 to the boat 217 returns to the cassette 110 and loads the next wafer 200 into the boat 217.

  When a predetermined number of wafers 200 are loaded into the boat 217, the lower end of the processing furnace 202 closed by the furnace port shutter 147 is opened by the furnace port shutter 147. Subsequently, when the seal cap 219 is raised by the boat elevator 115, the boat 217 holding the wafer 200 group is loaded into the processing furnace 202. After loading, arbitrary processing is performed on the wafer 200 in the processing furnace 202. Such processing will be described later. After the processing, the wafer 200 and the cassette 110 are discharged to the outside of the casing 111 by a procedure reverse to the above procedure.

(3) Configuration of Processing Furnace Next, the configuration of the processing furnace 202 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a schematic configuration diagram of a processing furnace 202 provided in a substrate processing apparatus according to an embodiment of the present invention, where (a) is a schematic longitudinal sectional view of the processing furnace, and (b) is FIG. 2 (a). The cross-sectional schematic of the process furnace 202 shown is shown, respectively.

(Processing room)
A processing furnace 202 according to an embodiment of the present invention includes a reaction tube 203 and a manifold 209. The reaction tube 203 is made of a heat-resistant non-metallic material such as quartz (SiO ₂ ) or silicon carbide (SiC), and has a cylindrical shape with its upper end closed and its lower end open. The manifold 209 is made of a metal material such as SUS, for example, and has a cylindrical shape with an upper end and a lower end opened. The reaction tube 203 is supported vertically by the manifold 209 from the lower end side. The reaction tube 203 and the manifold 209 are arranged concentrically. The lower end portion of the manifold 209 is configured to be hermetically sealed by the seal cap 219 when the above-described boat elevator 115 is raised. A sealing member 220 such as an O-ring that hermetically seals the inside of the processing chamber 201 is provided between the lower end portion of the manifold 209 and the seal cap 219.

  Inside the reaction tube 203 and the manifold 209, a processing chamber 201 for processing a wafer 200 as a substrate is formed. A boat 217 as a substrate holder is inserted into the processing chamber 201 from below. The inner diameters of the reaction tube 203 and the manifold 209 are configured to be larger than the maximum outer shape of the boat 217 loaded with the wafers 200.

  The boat 217 is configured to hold a plurality of wafers 200 in multiple stages with a predetermined gap (substrate pitch interval) in a substantially horizontal state. The boat 217 is mounted on a heat insulating cap 218 that blocks heat conduction from the boat 217. The heat insulating cap 218 is supported from below by the rotating shaft 267. The rotation shaft 267 is provided so as to penetrate the center portion of the seal cap 219 while maintaining airtightness in the processing chamber 201. A rotation mechanism (not shown) that rotates the rotation shaft 267 is provided below the seal cap 219. By rotating the rotating shaft 267 by the rotating mechanism, the boat 217 on which the plurality of wafers 200 are mounted can be rotated while maintaining the airtightness in the processing chamber 201.

(First gas supply line)
A first gas supply line 232 a that supplies a second processing gas is connected to the side surface of the manifold 209. The first gas supply line 232a is provided with a first processing gas supply source (not shown), a mass flow controller 241a, an open / close valve 243a, a gas reservoir 247a configured as a buffer tank, and an open / close valve 243a in order from the upstream side. Yes.

  A first gas supply unit 249 a is provided in the processing chamber 201 along the stacking direction of the wafers 200. The first gas supply unit 249 a is provided so as to surround a part of the space sandwiched between the inner wall of the processing chamber 201 and the periphery of the wafer 200 supported by the boat 217, and the wafer 200 from below in the processing chamber 201. It is extended toward the direction of laminating (vertical direction). In a space surrounded by the inner wall of the first gas supply unit 249a and the inner wall of the processing chamber 201, a buffer space that temporarily stores the processing gas supplied from the first gas supply line 232a and relaxes the difference in velocity of gas molecules. 250a is formed.

  The first gas supply unit 249a has a plurality of openings 248a. The plurality of openings 248 a are arranged on the side wall of the first gas supply unit 249 a facing the periphery of each wafer 200 so as to be along the stacking direction of the wafers 200. Each opening 248a opens toward the center of the processing chamber 201 (the center of the wafer 200). The first processing gas that is supplied into the buffer space 250a and in which the difference in velocity of gas molecules is relaxed is supplied (spouted) onto each wafer 200 accommodated in the processing chamber 201. . When the pressure in the buffer space 250a is different, for example, the diameter of the opening 248a on the upstream side of the gas flow (below the processing chamber 201) is set small, and the downstream side of the gas flow (above the processing chamber 201) is set. By setting the diameter of the opening 248a to be large, the supply amount of the processing gas to each wafer 200 can be made more uniform regardless of the mounting position (height) of the wafer 200.

(Second gas supply line)
A second gas supply line 232b for supplying a second processing gas is connected to the side surface of the manifold 209. The second gas supply line 232b is provided with a second processing gas supply source (not shown), a mass flow controller 241b, and an open / close valve 243b in order from the upstream side. The downstream end of the second gas supply line 232b is connected to the gas supply nozzle 233b. The gas supply nozzle 233 b penetrates the side surface of the manifold 209 and bends at a right angle in the processing chamber 201, and is disposed in the vertical direction along the inner wall of the manifold 209 and the reaction tube 203.

  A second gas supply unit 249 b is provided in the processing chamber 201 along the stacking direction of the wafers 200. The second gas supply unit 249b surrounds a part of the space sandwiched between the inner wall of the processing chamber 201 (the wall of the manifold 209 and the inner wall of the reaction tube 203) and the periphery of the wafer 200 supported by the boat 217. The gas supply nozzle 233b is provided so as to surround the outer periphery of the gas supply nozzle 233b, and extends from the lower side of the processing chamber 201 in the direction in which the wafers 200 are stacked (vertical direction). In a space surrounded by the inner wall of the second gas supply unit 249b and the inner wall of the processing chamber 201, a buffer space that temporarily stores the processing gas supplied from the second gas supply line 232b and relaxes the gas molecule velocity difference. 250b is formed.

  In the buffer space 250 b, a pair of electrodes 269 b and 270 b are extended in the direction (vertical direction) in which the wafers 200 are stacked so as to follow the inner walls of the manifold 209 and the reaction tube 203. An external power supply 273b is connected to the pair of electrodes 269b and 270b via an impedance matching device 272b. The pair of electrodes 269b and 270b are respectively covered with a cylindrical protective tube 275b made of a dielectric. The upper end portion of the protective tube 275b is closed, the lower end portion of the protective tube 275b is opened and communicates with the outside of the processing chamber 201, and an inert gas is purged inside the protective tube 275b. Although not shown, the held portion in the vicinity of the bent portion of the pair of electrodes 269b and 270b is sequentially covered with an insulating tube for preventing discharge and a shield tube for electrostatic shielding inside the protective tube 275b. By applying high frequency power from the external power supply 273b to the pair of electrodes 269b and 270b, plasma (ie, plasma discharge region) is generated (ignited) in the buffer space 250b. The plasma generated (ignited) by the pair of electrodes 269b and 270b is configured to excite the second processing gas supplied into the buffer space 250b.

  The second gas supply unit 249b has a plurality of openings 248b. The plurality of openings 248 b are arranged along the stacking direction of the wafers 200 on the side walls of the second gas supply unit 249 b facing the periphery of each wafer 200. Each opening 248b opens toward the center of the processing chamber 201 (the center of the wafer 200). The second processing gas supplied into the buffer space 250 b and excited by plasma is configured to be supplied (spouted) onto each wafer 200 stored in the processing chamber 201. When the pressure in the buffer space 250b is different, for example, the diameter of the opening 248b on the upstream side of the gas flow (below the processing chamber 201) is set small, and the downstream side of the gas flow (above the processing chamber 201) is set. By setting the diameter of the opening 248b to be large, it becomes possible to make the supply amount of the processing gas to each wafer 200 more uniform regardless of the mounting position (height) of the wafer 200.

(Inert gas supply line)
Inert gas supply lines 232c and 232d for supplying an inert gas into the processing chamber 201 are provided downstream of the opening / closing valve 244a of the first gas supply line 232a and downstream of the opening / closing valve 243b of the second gas supply line 232b. Are connected to each other. The inert gas supply line 232c is provided with an inert gas supply source, a mass flow controller 241c, and an open / close valve 243c (not shown) in order from the upstream side. The inert gas supply line 232d is provided with an inert gas supply source (not shown), a mass flow controller 241d, and an opening / closing valve 243d in order from the upstream side.

(Exhaust line)
An exhaust line 231 for exhausting the atmosphere in the processing chamber 201 is connected to the side wall of the manifold 209. A vacuum pump 246 is provided at the downstream end of the exhaust line 231. The exhaust line 231 has an APC (Auto Pressure) as a pressure regulator.
A controller) valve 243d is provided. By adjusting the opening degree of the APC valve 243e while operating the vacuum pump 246, the pressure in the processing chamber 201 can be adjusted.

(Resistance heater)
A resistance heater 207 as a heating means is provided so as to surround the outer periphery of the reaction tube 203. When the resistance heater 207 is energized, the inside of the processing chamber 201 is heated from the outside of the reaction tube 203. As described above, since the resistance heater 207 is configured as a hot wall structure, the temperature can be maintained uniformly throughout the processing chamber 201.

(controller)
A controller 280 is provided in the processing furnace 202. The controller 280 includes open / close valves 243a, 244a, 243b, mass flow controllers 241a, 241b, rotating means for rotating the rotating shaft 267, impedance matching unit 272b, external power supply 273b, vacuum pump 246, APC valve 243e, and resistance heater 207. These are connected to each other, and are configured to control each of these operations.

(4) Substrate Processing Step Next, a substrate processing step as one embodiment of the present invention will be described with reference to FIG. In the present embodiment, a silicon nitride film made of SiN or Si ₃ N ₄ is formed on the surface of the wafer 200 by using an ALD method which is one of CVD (Chemical Vapor Deposition) methods. This is performed as one step of the manufacturing process of the semiconductor device. In the following description, the operation of each part constituting the substrate processing apparatus is controlled by the controller 280.

(Substrate loading process)
The wafer 200 to be processed is loaded into the boat 217 by the procedure described above. Subsequently, the boat elevator 115 is raised, the boat 217 loaded with the wafers 200 is carried into the processing chamber 201, and the inside of the processing chamber 201 is hermetically sealed with a seal cap 219. At this time, the opening / closing valves 243a, 243b, 244a and the APC valve 243e are closed. After the wafer 200 is loaded, the wafer 200 is rotated by the rotation mechanism. Note that the inside of the processing chamber 201 is preferably heated in advance to, for example, 300 ° C.

(Decompression and temperature rise process)
The inside of the processing chamber 201 is exhausted by closing the open / close valves 243c and 243d and opening the APC valve 243e. During decompression, the gas reservoir 247a is also exhausted by opening the open / close valve 244a. Then, the pressure in the processing chamber 201 is controlled to be a predetermined pressure by adjusting the opening degree of the APC valve 243e. Further, by supplying electric power to the resistance heater 207, the temperature in the processing chamber 201 is raised to a predetermined temperature. At this time, the energization amount 1 to the resistance heater 207 is controlled so that the surface temperature of the wafer 200 becomes 525 ° C., for example.

When carrying out the substrate carrying-in process, the pressure reduction and the temperature raising process, the APC valve 243e and the opening / closing valves 243c and 243d are kept open, and nitrogen (N ₂ ) gas as an inert gas is always flowed into the processing chamber 201. It is preferable to keep it. As a result, the oxygen (O ₂ ) concentration in the processing chamber 201 can be lowered, and adhesion of particles (foreign matter) and metal contaminants to the wafer 200 can be suppressed.

(First step)
Subsequently, dichlorosilane (SiH ₂ Cl ₂ , abbreviated as DCS) gas as a first processing gas containing Cl element is supplied into the processing chamber 201.

  Specifically, by opening the opening / closing valve 243a with the opening / closing valve 244a closed, the flow rate is controlled by the mass flow controller 241a, and the gas reservoir 247a is filled with DCS gas. When the pressure in the gas reservoir 247a becomes 20000 Pa or more, for example, the charging of the DCS gas into the gas reservoir 247a is stopped by closing the open / close valve 243a. The filling of the DCS gas into the gas reservoir 247a is preferably completed before the end of the depressurization and temperature raising step or before the end of the fourth step described later.

  Then, by opening the opening / closing valve 244a with the opening / closing valves 243a, 243b and the APC valve 243e closed, the DCS gas in the gas reservoir 247a is removed using the pressure difference between the gas reservoir 247a and the processing chamber 201. It is introduced into the processing chamber 201 within a predetermined time (in a very short time). As a result, the pressure in the processing chamber 201 rises to about 931 Pa, for example, the surface of the wafer 200 is exposed to high-pressure DCS gas, and gas molecules of the DCS gas are chemically adsorbed on the wafer 200.

  When a predetermined time (for example, 6 seconds) elapses from the start of DCS gas supply into the processing chamber 201, the opening / closing valve 244a is closed to stop the supply of DCS gas into the processing chamber 201.

(Second step)
Subsequently, nitrogen (N ₂ ) gas as an inert gas is supplied into the processing chamber 201 and the DCS gas is exhausted from the processing chamber 201. Specifically, by opening the APC valve 243e and the opening / closing valves 243c and 243d, the nitrogen gas is supplied into the processing chamber 201, and the DCS gas remaining in the processing chamber 201, reaction products, and the like are exhausted from the exhaust line 231. Exhaust from. By supplying nitrogen gas into the processing chamber 201, the exhaust efficiency of DCS gas and reaction products from the processing chamber 201 can be increased.

  At this time, the concentration of Cl element in the silicon nitride film formed in this substrate processing step is controlled by adjusting the supply amount or supply time of the nitrogen gas in the second step. For example, after the discharge of DCS gas, reaction products, and the like from the inside of the processing chamber 201 is completed, the open / close valves 243c and 243d and the APC valve 243e are kept open, and nitrogen gas is continuously supplied into the processing chamber 201. Thereby, the Cl element concentration in the silicon nitride film can be reduced, the number of Si—N bonds can be increased, and the etching rate for the HF-based solution can be reduced.

  When a predetermined time (for example, 62 seconds) elapses from the start of supply of nitrogen gas into the processing chamber 201 and the amount of Cl element desorbed from the silicon nitride film is reduced to a predetermined value or less and converges, the open / close valve 243c, 243d is closed and the supply of nitrogen gas into the processing chamber 201 is stopped.

(Third step)
Subsequently, ammonia (NH ₃ ) gas as a second processing gas is supplied into the processing chamber 201 to generate a thin film on the wafer 200. In this embodiment, in order to lower the film forming temperature, ammonia gas is activated after being activated by plasma and then supplied.

Specifically, by closing the on-off valves 243c and 243d and opening the on-off valve 243b, while controlling the flow rate by the mass flow controller 241b, the buffer space 250b
Ammonia gas is supplied into the inside to relieve the difference in velocity of gas molecules. When the pressure in the buffer space 250b reaches a predetermined ignition pressure, high-frequency power is supplied from the external power source 273b to the pair of electrodes 269b and 270b via the impedance matching device 272b, and plasma is generated in the buffer space 250b. (Ignition). Then, the generated plasma excites (activates) the ammonia gas supplied into the buffer space 250b, and supplies active particles (radicals) into the processing chamber 201 through the opening 248b. When the active particles react with the gas molecules of the DCS gas that is chemically adsorbed on the wafer 200, a silicon nitride film composed of one atomic layer to several atomic layers of SiN or Si ₃ N ₄ is generated on the surface of the wafer 200. Is done.

  When a predetermined time (for example, 20 seconds) elapses from the start of supply of ammonia gas into the processing chamber 201, power supply to the pair of electrodes 269b and 270b is stopped, and the open / close valve 243b is closed to enter the processing chamber 201. Stop the supply of ammonia gas.

(Fourth process)
Subsequently, nitrogen gas as an inert gas is supplied into the processing chamber 201 and the ammonia gas is exhausted from the processing chamber 201. Specifically, by opening the opening / closing valves 243c and 243d with the APC valve 243e open, the ammonia gas and reaction products remaining in the processing chamber 201 are supplied while supplying the nitrogen gas into the processing chamber 201. Etc. are exhausted from the exhaust line 231. By supplying nitrogen gas into the processing chamber 201, the exhaust efficiency of DCS gas and reaction products from the processing chamber 201 can be increased.

  At this time, similarly to the second step, the concentration of Cl element in the silicon nitride film may be controlled by adjusting the supply amount or supply time of the nitrogen gas in the fourth step. For example, after the discharge of ammonia gas, reaction products, and the like from the inside of the processing chamber 201 is completed, the open / close valves 243c and 243d and the APC valve 243e are kept open and nitrogen gas is supplied to the processing chamber as in the second step. You may continue to supply in 201. Thereby, the Cl element concentration in the silicon nitride film can be further reduced, the number of Si—N bonds can be further increased, and the etching rate for the HF-based solution can be further reduced.

  When a predetermined time (for example, 61 seconds) elapses from the start of supply of nitrogen gas into the processing chamber 201 and the amount of Cl element desorbed from the silicon nitride film is reduced to a predetermined value or less and converges, the open / close valve 243c, 243d is closed and the supply of nitrogen gas into the processing chamber 201 is stopped.

(Repeated process)
This cycle is repeated a plurality of times with the first to fourth steps as one cycle. Thereby, a silicon nitride film having a desired film thickness can be formed on the wafer 200. For example, when the thickness of the silicon nitride film generated for each cycle is 1 mm, this cycle is repeated 20 times to form a silicon nitride film having a thickness of 20 mm.

(Substrate unloading process)
After a thin film having a desired film thickness is formed on each wafer 200, the rotation of the wafer 200 by the rotation mechanism is stopped. Then, the temperature in the processing chamber 201 is lowered to, for example, 300 ° C. and returned to the atmospheric pressure by a procedure reverse to the above-described substrate carry-in process and pressure reduction and temperature raising process, and the wafer 200 on which a thin film having a desired film thickness is processed. Unload from the chamber 201. Thus, the substrate processing process according to this embodiment is completed.

(5) Effects according to the present embodiment According to the present embodiment, one or more of the following effects (a) to (e) are achieved.

(A) According to the present embodiment, in the second step, after the DCS gas and reaction products are discharged from the processing chamber 201, the open / close valves 243c and 243d and the APC valve 243e are kept open, The gas is continuously supplied into the processing chamber 201. Thereby, the Cl element concentration in the silicon nitride film can be reduced, the number of Si—N bonds can be increased, and the etching rate for the HF-based solution can be reduced.

(B) According to the present embodiment, the etching rate of the silicon nitride film with respect to the HF-based solution can be lowered only by extending the gas supply time of the second step. That is, the etching rate can be reduced without increasing the film formation temperature. For example, it is possible to form a silicon nitride film having an etching rate ratio of 0.2 while keeping the film formation temperature at 525 ° C.

(C) According to the present embodiment, the etching rate of the silicon nitride film with respect to the HF-based solution can be lowered by extending only the gas supply time of the second step. As will be described later, the etching rate of the silicon nitride film is lowered by extending the supply time of the DCS gas in the first step or by extending the supply time of the ammonia gas in the third step. It is possible. However, the gas cost of nitrogen gas is low compared with DCS gas and ammonia gas. In this embodiment, since only the supply time of nitrogen gas is extended, a silicon nitride film having a low etching rate can be formed at a relatively low cost.

(D) According to the present embodiment, when a predetermined time elapses from the start of the supply of nitrogen gas into the processing chamber 201 and the amount of Cl element desorbed from the silicon nitride film is reduced to a predetermined value or less and converged. Then, the on-off valves 243c and 243d are closed, and the supply of nitrogen gas into the processing chamber 201 is stopped. As a result, it is possible to prevent the processing time per cycle from being unnecessarily extended and to prevent the productivity of the substrate processing process from being inadvertently reduced.

(E) According to the present embodiment, in the fourth step, similarly to the second step, after the ammonia gas, the reaction product, and the like are discharged from the processing chamber 201, the open / close valves 243c, 243d, APC The valve 243 e may be kept open and nitrogen gas may be continuously supplied into the processing chamber 201. In such a case, the Cl element concentration in the silicon nitride film can be further reduced, the number of Si—N bonds can be further increased, and the etching rate for the HF-based solution can be further reduced.

(6) Evaluation results Evaluation results supporting the above-described effects will be described below with reference to the drawings.

(Evaluation conditions)
First, the evaluation conditions will be described with reference to FIG. FIG. 7 is a schematic diagram showing the execution time of each process in the film formation evaluation using the ALD method, where (a) shows the case of the conventional substrate processing process, and (b) shows the supply time of the first processing gas. (C) shows a substrate processing step in which the supply time of the second processing gas is extended, and (d) shows a substrate processing in which the supply time of the inert gas is extended. Each of the process cases is shown.

  In FIG. 7 (a), the supply time of DCS gas in the first step is 6 seconds, the supply time of nitrogen gas in the second step is 8 seconds, the supply time of ammonia gas in the third step is 20 seconds, The supply time of nitrogen gas in the third step was 4 seconds. The supply amount of DCS gas in the first step is 60 cc, the supply flow rate of ammonia gas in the third step is 5 slm, the supply power (plasma generation power) from the external power supply 273b is 50 W, and the film formation temperature is 525 ° C. It was. Hereinafter, such film forming conditions are also referred to as “conventional recipes”.

  In FIG. 7 (b), the supply time of DCS gas in the first step is 63 seconds, the supply time of nitrogen gas in the second step is 8 seconds, the supply time of ammonia gas in the third step is 20 seconds, The supply time of nitrogen gas in the third step was 4 seconds. The supply amount of DCS gas in the first step was 660 cc. Other conditions are the same as those in FIG. Hereinafter, such film forming conditions are also referred to as “DCS long”.

In FIG. 7C, the DCS gas supply time in the first step is 6 seconds, the nitrogen gas supply time in the second step is 8 seconds, the ammonia gas supply time in the third step is 60 seconds, The supply time of nitrogen gas in the third step was 4 seconds. Note that the supply flow rate of ammonia gas in the third step was 5 slm. Other conditions are the same as those in FIG. Hereinafter, such film forming conditions are also referred to as “NH ₃ long”.

In FIG. 7D, the supply time of DCS gas in the first step is 6 seconds, the supply time of nitrogen gas in the second step is 62 seconds, the supply time of ammonia gas in the third step is 20 seconds, The supply time of nitrogen gas in the third step was 61 seconds. Other conditions are the same as those in FIG. Hereinafter, such film forming conditions are also referred to as “N ₂ long”.

(Evaluation results on film quality)
The evaluation results regarding each silicon nitride film formed under the conditions shown in FIGS. 7A to 7D will be described with reference to FIGS. 8 and 11 to 13.

FIG. 8 is a graph showing the etching rate ratio and the refractive index (RI) of the silicon nitride film formed by the respective substrate processing steps shown in FIGS. 7A to 7D. In the figure, the columnar graph indicates the etching rate ratio (left vertical axis), and the Δ mark indicates the refractive index (right vertical axis). “Top” is an evaluation result regarding the wafer 200 held near the upper part in the boat 217, “Ctr” is an evaluation result regarding the wafer 200 held near the middle in the boat 217, and “Btm” is the boat 217. The evaluation results relating to the wafer 200 held near the bottom of each are shown. According to FIG. 8, the etching rate ratio of the silicon nitride film formed by the conventional recipe (FIG. 7A) exceeds 0.4. On the other hand, it can be seen that the etching rate ratio of the silicon nitride film formed in N ₂ long (FIG. 7D) is less than 0.2. According to FIG. 8, DCS
The etching rate ratios of the silicon nitride films formed by long (FIG. 7B) and NH ₃ long (FIG. 7C) are both less than 0.3, and N ₂ long (FIG. 7D) Although not so much, it can be seen that the etching rate ratio of the silicon nitride film formed by the conventional recipe (FIG. 7A) is improved.

FIG. 11 is a graph showing the Cl element concentration in the silicon nitride film formed by each substrate processing step shown in FIGS. 7A to 7D. The horizontal axis in FIG. 11 indicates the depth (nm) from the surface of the silicon nitride film, and the vertical axis in FIG. 11 indicates the Cl element concentration (atoms / cm ³ ). According to FIG. 11, compared with the Cl element concentration (curve (a)) in the silicon nitride film formed by the conventional recipe (FIG. 7A), N ₂ long (FIG. 7D) It can be seen that the Cl element concentration (curve (d)) in the formed silicon nitride film is lower. According to FIG. 8, the Cl element concentration (curve (b) and curve (c) in the silicon nitride film formed by DCS long (FIG. 7B) and NH ₃ long (FIG. 7C) is shown. ) Is also lower than the Cl element concentration (curve (a)) in the silicon nitride film formed by the conventional recipe (FIG. 7A).

FIG. 12 is a graph showing the concentration of H element in each of the silicon nitride films formed by the substrate processing steps shown in FIGS. 7 (a) to 7 (d). The horizontal axis in FIG. 12 indicates the depth (nm) from the surface of the silicon nitride film, and the vertical axis in FIG. 12 indicates the H element concentration (atoms / cm ³ ). According to FIG. 12, compared with the H element concentration (curve (a)) in the silicon nitride film formed by the conventional recipe (FIG. 7 (a)), N ₂ long (FIG. 7 (d)). It can be seen that the H element concentration (curve (d)) in the formed silicon nitride film is slightly lower. Note that, according to FIG. 12, H element concentration (curve (b) and curve (c) in the silicon nitride film formed by DCS long (FIG. 7B) and NH ₃ long (FIG. 7C). )), It is understood that there is almost no difference compared with the H element concentration (curve (a)) in the silicon nitride film formed by the conventional recipe (FIG. 7A).

FIG. 13 shows FTIR (Fourier Transform Infrared Spectroscopy) measurement results relating to the number of Si—N bonds for the silicon nitride films formed by the respective substrate processing steps shown in FIGS. 7A to 7D. FIG. The horizontal axis of FIG. 13 indicates the depth (nm) from the surface of the silicon nitride film, the vertical axis of FIG. 13 indicates the amount of light absorption due to Si—N bonds in the silicon nitride film, and the horizontal axis indicates silicon nitride. The wavelength of the irradiation light to the film is shown. According to FIG. 13, the light absorption amount of the silicon nitride film formed by N ₂ long (FIG. 7D) is larger than the light absorption amount of the silicon nitride film formed by the conventional recipe (FIG. 7A). It can be seen that the number of Si—N bonds is increased in the silicon nitride film formed in N ₂ long (FIG. 7D).

  As described above, in the second step, after exhausting DCS gas, reaction products, and the like from the processing chamber 201, the nitrogen gas is continuously supplied into the processing chamber 201, whereby the concentration of Cl element in the silicon nitride film is increased. (FIG. 11), the number of Si—N bonds can be increased (FIG. 13), and the etching rate of the silicon nitride film with respect to the HF solution can be decreased (FIG. 8).

(Evaluation results regarding film formation costs)
Subsequently, the inventors conducted comparative verification on the gas cost (gas cost required for film formation) in each substrate processing step shown in FIGS. 7 (a) to 7 (d). FIG. 9 is a table showing gas costs in the respective substrate processing steps shown in FIGS. Each cost shown in FIG. 9 is expressed by using a ratio to the cost of the DCS gas in the conventional recipe (FIG. 7A) when a 300 シ リ コ ン silicon nitride film is formed.

According to FIG. 9, 375 cycles are required in the conventional recipe (FIG. 7 (a)) to form a 300 シ リ コ ン silicon nitride film. When the cost of DCS gas is 1.0, the cost of ammonia gas is 1.7, and the total gas cost is 2.7. In contrast, N ₂ long (FIG. 7D) requires 407 cycles, the cost of DCS gas is 1.1, the gas of ammonia is 1.7, and the total gas cost is 2.9. DCS long (FIG. 7B) requires 243 cycles, the cost of DCS gas is 7.3, the gas of ammonia is 1.1, and the total gas cost is 8.3. In addition, in NH ₃ long (FIG. 7C), 348 cycles are required, the cost of DCS gas becomes 0.9, the gas of ammonia becomes 4.3, and the total gas cost becomes 5.3.

That is, it can be seen that the film formation cost of N ₂ long (FIG. 7D) for extending the supply time of nitrogen gas hardly increases as compared with the film formation cost of the conventional recipe (FIG. 7A). Further, the film formation cost of N ₂ long (FIG. 7D) for extending the supply time of nitrogen gas is the same as the film formation cost of DCS long (FIG. 7B) or NH ₃ long (FIG. 7C). It can be seen that this is far less than the film formation cost.

(Upper limit of nitrogen gas supply time)
Subsequently, the inventors evaluated the relationship between the supply time of the nitrogen gas supplied in the second step and the etching rate ratio. FIG. 10 shows the evaluation results. As can be seen from FIG. 10, the etching rate of the silicon nitride film decreases as the supply time of the nitrogen gas is extended. It can also be seen that when the nitrogen gas supply time exceeds 65 seconds, the etching rate of the silicon nitride film hardly decreases. That is, it can be seen that when a predetermined time elapses from the start of the supply of nitrogen gas, the amount of Cl element desorbed from the silicon nitride film (the amount of decrease in the etching rate of the silicon nitride film) is reduced below the predetermined value and converges. . Accordingly, when the amount of Cl element desorption (the amount of decrease in the etching rate of the silicon nitride film) is reduced to a predetermined value or less, the supply of nitrogen gas in the second step may be stopped and the third step may be started (or It can be seen that the supply of nitrogen gas in the fourth step may be stopped and the first step may be started).

(Comparison between the second step and the fourth step)
Subsequently, the inventors extended the supply time of the nitrogen gas only in the second step, extended the supply time of the nitrogen gas only in the fourth step, and the second step and the fourth step. The etching rate ratio of the silicon nitride film in the case where the supply time of the nitrogen gas was extended in both the steps and the step was measured. FIG. 15 shows the measurement results. FIG. 14A is a schematic diagram showing a substrate processing process in which the inert gas supply time in the second process is extended, and FIG. 14B is a schematic diagram showing an increase in the inert gas supply time in the fourth process. It is the schematic which shows the performed substrate processing process. The film forming temperature was 525 ° C. and was the same.

  As shown in FIG. 15, when the supply time of nitrogen gas is extended only in the second step (left in the figure), the etching rate ratio becomes 0.2, and the supply time of nitrogen gas only in the fourth step. Is extended (in the middle of the figure), the etching rate ratio is 0.35, and the supply time of nitrogen gas is extended in both the second and fourth steps (right in the figure). The etching rate ratio was less than 0.2. In other words, it was found that extending the nitrogen gas supply time in the second step was more effective than lowering the nitrogen gas supply time in the fourth step in order to reduce the etching rate of the silicon nitride film. . It was also found that the etching rate can be further reduced by extending the supply time of nitrogen gas in both the second step and the fourth step.

<Preferred embodiment of the present invention>
Hereinafter, preferred embodiments of the present invention will be additionally described.

According to one aspect of the invention,
A substrate processing method for forming a thin film on a substrate housed in a processing chamber,
A first step of supplying a first processing gas containing Cl element into the processing chamber;
A second step of supplying an inert gas into the processing chamber and discharging the first processing gas from the processing chamber;
A third step of supplying a second processing gas into the processing chamber to form a thin film on the substrate;
A fourth step of supplying an inert gas into the processing chamber and discharging a second processing gas from the processing chamber, and repeating this cycle a predetermined number of times as one cycle,
In the second step, there is provided a substrate processing method for continuously supplying an inert gas into the processing chamber even after the first processing gas is exhausted from the processing chamber.

  Preferably, in the second step, after the first processing gas is exhausted from the processing chamber, an inert gas is continuously supplied into the processing chamber so as to desorb Cl element from the thin film.

  Preferably, in the second step, after the first processing gas is exhausted from the processing chamber, the inert gas is supplied until the desorption amount of Cl element from the thin film is reduced to a predetermined value or less. Continue to supply into the processing chamber.

  Preferably, in the fourth step, the inert gas is continuously supplied into the processing chamber even after the third processing gas is discharged from the processing chamber.

  Preferably, in the fourth step, after the second processing gas is exhausted from the processing chamber, an inert gas is continuously supplied into the processing chamber so as to desorb Cl element from the thin film.

  Preferably, in the fourth step, after the second processing gas is exhausted from the processing chamber, the inert gas is supplied until the amount of desorption of Cl element from the thin film is reduced to a predetermined value or less. Continue to supply into the processing chamber.

  Preferably, the total supply amount of the inert gas in the second step is larger than the total supply amount of the inert gas in the fourth step.

  Preferably, the supply time of the inert gas in the second step is longer than the supply time of the inert gas in the fourth step.

According to another aspect of the invention,
A substrate processing method for forming a thin film on a substrate housed in a processing chamber,
A first step of supplying a first processing gas containing Cl element into the processing chamber;
A second step of supplying an inert gas into the processing chamber and discharging the first processing gas from the processing chamber;
A third step of supplying a second processing gas into the processing chamber to form a thin film on the substrate;
A fourth step of supplying an inert gas into the processing chamber and discharging a second processing gas from the processing chamber, and repeating this cycle a predetermined number of times as one cycle,
There is provided a substrate processing method for controlling the Cl element concentration in the thin film by adjusting the supply amount or supply time of the inert gas in the second step.

According to another aspect of the invention,
A substrate processing method for forming a thin film on a substrate housed in a processing chamber,
A first step of supplying a first processing gas containing Cl element into the processing chamber;
A second step of supplying an inert gas into the processing chamber and discharging the first processing gas from the processing chamber;
A third step of supplying a second processing gas into the processing chamber to form a thin film on the substrate;
A fourth step of supplying an inert gas into the processing chamber and discharging a second processing gas from the processing chamber, and repeating this cycle a predetermined number of times as one cycle,
By adjusting the supply amount or supply time of the inert gas in the fourth step, a substrate processing method for controlling the Cl element concentration in the thin film is provided.

Preferably,
The first processing gas is dichlorosilane gas,
The second processing gas is ammonia gas activated by plasma,
The inert gas is nitrogen gas.

101 substrate processing apparatus 200 wafer (substrate)
201 processing chamber 202 processing furnace 231 exhaust line 232a first gas supply line 232b second gas supply line 232c inert gas supply line 232d inert gas supply line 280 controller

Claims (7)

Forming a silicon nitride film on the substrate;
In the step of forming the silicon nitride film,
A first step of supplying a first processing gas containing Cl element into a processing chamber containing the substrate;
A second step of supplying an inert gas alone into the processing chamber and discharging the first processing gas from the processing chamber;
A third step of supplying a second processing gas into the processing chamber to form a thin film on the substrate;
A fourth step of supplying an inert gas alone into the processing chamber and discharging the second processing gas from the processing chamber, and repeating this cycle a predetermined number of times as one cycle,
In the second step,
After the first processing gas is exhausted from the processing chamber, the inert gas is continuously supplied alone to the processing chamber, and the substrate is exposed to the atmosphere of the inert gas alone to remove the Cl element from the thin film. The method for manufacturing a semiconductor device is characterized in that the supply of the inert gas into the processing chamber is stopped when the amount of Cl element desorbed from the thin film is reduced to a predetermined value or less . In the fourth step,
After the second processing gas is discharged from the processing chamber, the inert gas is continuously supplied alone to the processing chamber, and the substrate is exposed to the atmosphere of the inert gas alone to remove the Cl element from the thin film. When the desorption amount of Cl element from the thin film is reduced below a predetermined value, the supply of the inert gas into the processing chamber is stopped.
The method of manufacturing a semiconductor device according to claim 1. The inert gas supply time in the second step is longer than the inert gas supply time in the fourth step.
The method for manufacturing a semiconductor device according to claim 1, wherein: Forming a silicon nitride film on the substrate;
In the step of forming the silicon nitride film,
A first step of supplying a first processing gas containing Cl element into a processing chamber containing the substrate;
A second step of supplying an inert gas alone into the processing chamber and discharging the first processing gas from the processing chamber;
A third step of supplying a second processing gas into the processing chamber to form a thin film on the substrate;
A fourth step of supplying an inert gas alone into the processing chamber and discharging the second processing gas from the processing chamber, and repeating this cycle a predetermined number of times as one cycle,
In the second step,
After the first processing gas is exhausted from the processing chamber, the inert gas is continuously supplied alone to the processing chamber, and the substrate is exposed to the atmosphere of the inert gas alone to remove the Cl element from the thin film. The substrate processing method is characterized in that the supply of the inert gas into the processing chamber is stopped when the release amount of the Cl element from the thin film is reduced to a predetermined value or less . In the fourth step,
After the second processing gas is discharged from the processing chamber, the inert gas is continuously supplied alone to the processing chamber, and the substrate is exposed to the atmosphere of the inert gas alone to remove the Cl element from the thin film. When the desorption amount of Cl element from the thin film is reduced below a predetermined value, the supply of the inert gas into the processing chamber is stopped.
The substrate processing method according to claim 4. The inert gas supply time in the second step is longer than the inert gas supply time in the fourth step.
The substrate processing method according to claim 4 or 5, wherein A processing chamber for accommodating the substrate;
A first processing gas supply line for supplying a first processing gas into the processing chamber;
A second processing gas supply line for supplying a second processing gas into the processing chamber;
An inert gas supply line for supplying an inert gas into the processing chamber;
An exhaust line for exhausting the processing chamber;
A controller for controlling at least the first processing gas supply line, the second processing gas supply line, the inert gas supply line, and the exhaust line;
The controller is
A first process for supplying a first process gas into the process chamber; a second process for supplying an inert gas alone into the process chamber and discharging the first process gas from the process chamber; A second process gas is supplied to the process chamber to form a thin film on the substrate, and an inert gas is supplied to the process chamber as a single unit to discharge the second process gas from the process chamber. When the silicon nitride film is formed on the substrate by repeating this cycle a predetermined number of times as a fourth process, the first process gas is exhausted from the process chamber in the second process. Thereafter, the inert gas is continuously supplied alone into the processing chamber, and the Cl element is desorbed from the thin film by exposing the substrate to the atmosphere of the inert gas alone, and the Cl element is desorbed from the thin film. The amount is reduced below the specified value When, the substrate processing apparatus according to claim <br/> stopping the supply of the inert gas into the processing chamber.

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