JP5227003B2 - Semiconductor device manufacturing method, substrate processing method, and substrate processing apparatus - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device (semiconductor device) and a substrate processing apparatus.
Specifically, in a process of forming a thin film on a semiconductor wafer (hereinafter referred to as a wafer) on which an integrated circuit including a semiconductor element in a method for manufacturing a semiconductor integrated circuit device (hereinafter referred to as an IC) is formed, The present invention relates to a method for forming a high-quality interface therebetween and a substrate processing apparatus for realizing the method.

In an IC manufacturing method, a thin film is formed on a wafer by a low pressure CVD method (chemical vapor deposition method).
In recent years, the following method has been used to solve problems such as an increase in a natural oxide film when a wafer is introduced into a reaction furnace and deterioration of a semiconductor due to adhesion of impurities.
A preliminary chamber is set in front of the reaction furnace, oxygen and moisture are sufficiently removed in the preliminary chamber, and the preliminary chamber is replaced with nitrogen gas, and then the wafer is introduced into the reaction furnace.
In order to carry out this reduced pressure CVD method, a vertical reduced pressure CVD apparatus with a preliminary chamber (hereinafter referred to as a CVD apparatus with a preliminary chamber) having a preliminary chamber configured in a hermetically sealed structure capable of evacuation at the front stage of the reactor. used.
In the CVD apparatus with a preparatory chamber, a wafer before processing is carried into the preparatory chamber from the wafer transfer port and set on a boat which is a wafer processing jig. Thereafter, the preliminary chamber is closed in an airtight manner, and oxygen, moisture, and the like are removed by repeating evacuation and nitrogen purge. Thereafter, the wafer is loaded into the reaction furnace from the preliminary chamber by a boat (boat loading).

However, in this CVD apparatus with a preparatory chamber, there is a concern that the wafer surface is contaminated by contaminants such as organic substances during evacuation. This is because a drive shaft portion, a boat rotation mechanism portion, and a wiring portion for carrying wafers and boats into the reaction furnace are installed in the spare chamber.
Therefore, a hydrogen (H ₂ ) annealing method is used as a method for removing a natural oxide film or impurities on a wafer using a reaction gas in a reaction furnace in which the wafer is carried. For example, see Patent Document 1.
JP-A-5-29309.

However, this hydrogen annealing method generally requires a high-temperature treatment at 900 to 1000 ° C., and thus there may be problems of thermal damage to the IC and an increase in the thermal budget.
Here, in order to form a high-quality interface between the wafer and the thin film with a low oxygen / carbon density, the wafer surface from the introduction of the wafer into the CVD chamber with a preliminary chamber until just before the film formation in the reactor is obtained. It is important to minimize contamination.
Specifically, it is necessary to take measures for cleaning the wafer surface as follows.
In the preliminary chamber, contamination of the wafer surface by organic substances from the drive shaft portion, the boat rotation mechanism portion, and the wiring portion is suppressed at the time of nitrogen replacement before carrying the wafer into the reaction furnace and when carrying out the reaction furnace.
In the reaction furnace, contamination from a relatively low temperature furnace opening and the wafer itself is suppressed.
The furnace atmosphere is highly purified and the contaminants adsorbed on the surface are reduced and desorbed until just before the thin film is formed on the wafer.
When cleaning the wafer surface as described above using a CVD apparatus with a preliminary chamber in a batch process, for example, a mass production process of processing 100 to 150 sheets, a furnace port that is relatively low in temperature. There is a possibility that contamination of the wafer surface may occur non-uniformly in the direction between the wafer surfaces in the reaction furnace, that is, in the wafer arrangement direction due to degassing from the wafer and the wafer.

  An object of the present invention is to provide a semiconductor device manufacturing method and substrate capable of uniformly forming a low-oxygen / carbon density and high-quality interface between a wafer and a thin film across the wafer surface in a mass production process in batch processing. It is to provide a processing apparatus.

According to one aspect of the present invention, a step of carrying a plurality of substrates into a reaction vessel composed of a process tube and a manifold that supports the process tube and arranging the substrates in the reaction vessel;
Performing a pretreatment on the plurality of substrates by flowing a pretreatment gas from the manifold side toward the process tube in the reaction vessel;
Applying the main processing to the plurality of substrates subjected to the preprocessing by flowing a main processing gas from the manifold side to the process tube side in the reaction vessel;
Unloading the plurality of substrates after the main treatment from the reaction vessel, and
In the step of performing the pretreatment, a method for manufacturing a semiconductor device is provided in which pretreatment gas is supplied from at least one location in the region corresponding to the manifold and at least one location in the upper portion in the region corresponding to the substrate arrangement region. Is done.
According to another aspect of the present invention, a step of bringing a plurality of substrates into the reaction container and arranging them in the reaction container;
Flowing a pretreatment gas into the reaction vessel to pretreat the plurality of substrates;
Subjecting the plurality of substrates that have been subjected to the pretreatment by flowing a main treatment gas into the reaction vessel;
Unloading the plurality of substrates after the main treatment from the reaction vessel, and
In the step of performing the pretreatment, a semiconductor device that supplies a pretreatment gas from at least one location in a region that is lower in temperature than the substrate arrangement region and at least one location on the downstream end in a region corresponding to the substrate arrangement region A manufacturing method is provided.
According to still another aspect of the present invention, a step of bringing a plurality of substrates into the reaction container and arranging them in the reaction container;
Flowing a pretreatment gas into the reaction vessel to pretreat the plurality of substrates;
Subjecting the plurality of substrates that have been subjected to the pretreatment by flowing a main treatment gas into the reaction vessel;
Unloading the plurality of substrates after the main treatment from the reaction vessel, and
In the step of performing the pretreatment, the semiconductor device manufacturing method supplies the pretreatment gas from at least one place in a region below the substrate arrangement region and at least one place in an upper portion in a region corresponding to the substrate arrangement region. Is provided.
According to yet another aspect of the present invention, the step of loading the substrate into the reaction vessel;
Pre-treating the substrate in the reaction vessel;
Applying the main treatment to the pretreated substrate in the reaction vessel;
Unloading the substrate after the main treatment from the reaction vessel,
In the step of performing the pretreatment, the pretreatment gas is supplied from a plurality of locations in the processing chamber, and the supply flow rate, concentration, or type of the pretreatment gas is set in at least one of the plurality of locations and other locations. A method for manufacturing a semiconductor device is provided.
According to yet another aspect of the present invention, the step of loading the substrate into the reaction vessel;
Pre-treating the substrate in the reaction vessel;
Applying the main treatment to the pretreated substrate in the reaction vessel;
Unloading the substrate after the main treatment from the reaction vessel,
In the step of performing the pretreatment, a plurality of types of pretreatment gases are supplied from a plurality of locations in the processing chamber, and at least one of the plurality of locations and the other types of the pretreatment gases of the plurality of types are treated. Provided is a method for manufacturing a semiconductor device in which a supply flow rate ratio or a concentration ratio is varied.
According to yet another aspect of the invention, a process tube for processing a substrate;
A manifold that supports the process tube;
A support for arranging and supporting a plurality of substrates in the process tube;
A first nozzle that supplies gas from at least one location in a region corresponding to the manifold;
A second nozzle for supplying gas from at least one upper portion in a region corresponding to the substrate arrangement region in the process tube;
An exhaust path provided on the opposite side of the process tube to the side on which the first nozzle is provided and exhausts the inside of the process tube;
A pretreatment gas is supplied from the first nozzle and the second nozzle, flows toward the exhaust path, pretreats the plurality of substrates, and supplies the main treatment gas from at least the first nozzle. And a controller that controls the flow to flow toward the exhaust path and perform the main process on the plurality of substrates that have been subjected to the pre-process,
A substrate processing apparatus is provided.

  According to the present invention, in a mass production process in batch processing, a natural oxide film or impurities on a substrate are efficiently and uniformly removed across the substrate surface, and a high-quality interface with low oxygen and carbon density is formed between the substrate surfaces. Can be formed uniformly.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In the present embodiment, the method for manufacturing a semiconductor device according to the present invention is performed using the CVD apparatus with a prechamber (hereinafter referred to as a CVD apparatus) shown in FIGS. 1 and 2 as the substrate processing apparatus. .
In this embodiment, before forming a thin film, a gas containing hydrogen atoms, a gas containing silicon atoms, or a gas containing chlorine atoms is used as a pretreatment gas (interface cleaning gas), alone or in combination, or a carrier. Together with the gas, it is introduced into the reactor from two or more multi-system gas lines.

First, the CVD apparatus will be described.
As shown in FIG. 1, the CVD apparatus 10 includes a casing 11, and a preliminary chamber 12 is formed in the casing 11. The preliminary chamber 12 is constructed as a sealed chamber having an airtight performance capable of maintaining a pressure lower than atmospheric pressure, and constitutes a preliminary chamber installed in the front stage of the reactor.
A wafer loading / unloading port 13 is opened on the front wall of the housing 11, and the wafer loading / unloading port 13 is opened and closed by a gate valve 14.
A boat loading / unloading port 15 through which the boat 34 enters and exits is opened at the ceiling wall position of the housing 11, and the boat loading / unloading port 15 is opened and closed by a shutter 16.

One end of an exhaust line 17 for exhausting the atmosphere in the preliminary chamber 12 is connected to the housing 11, and the other end of the exhaust line 17 is connected to a mechanical booster pump 19 and a dry pump 20 as a vacuum pump via a valve 18. It is connected.
One end of a nitrogen gas supply line 21 for supplying nitrogen gas as a purge gas into the spare chamber 12 is connected to the casing 11, and the other end of the nitrogen gas supply line 21 is connected to a nitrogen gas supply source via a mass flow controller 22. 23.

A boat elevator 24 for raising and lowering the boat 34 is installed in the preliminary chamber 12 of the housing 11. The boat elevator 24 raises and lowers the boat 34 to carry the boat 34 into or out of the processing chamber 46 described later.
The boat elevator 24 includes a guide rail 25 and a feed screw shaft 26 laid vertically, and a motor 27 that rotates the feed screw shaft 26 forward and backward. An elevating body 28 is fitted to the guide rail 25 so as to be movable up and down in the vertical direction, and the elevating body 28 is screwed to the feed screw shaft 26 so as to advance and retract in the vertical direction.
An arm 29 protrudes horizontally from the elevating body 28, and the upper surface of the tip of the arm 29 serves as a furnace port lid that can airtightly close the boat loading / unloading port 15 provided on the ceiling wall of the housing 11. A seal cap 30 is installed horizontally. The seal cap 30 is brought into contact with the lower surface of the ceiling wall of the housing 11 from the lower side in the vertical direction. The seal cap 30 is formed in a disk shape using a metal such as stainless steel. An O-ring 31 is laid on the upper surface of the seal cap 30 as a seal member that contacts the lower surface of the ceiling wall of the housing 11.

A rotation mechanism 32 that rotates the boat is installed below the seal cap 30, and a rotation shaft 33 of the rotation mechanism 32 passes through the seal cap 30 and is connected to the boat 34. The rotating mechanism 32 rotates the wafer 1 by rotating the boat 34.
The boat 34 as a substrate holder is formed using a heat-resistant material such as quartz or silicon carbide, and the wafers 1 as a plurality of substrates are aligned in a horizontal posture and aligned with each other in the center. And hold it in multiple stages.
In the lower part of the boat 34, a plurality of heat insulating plates 35 are arranged in multiple stages in a horizontal posture. The heat insulating plate 35 is formed in a disk shape using a heat resistant material such as quartz or silicon carbide. The heat insulating plate 35 makes it difficult for the heat from the heater 42 to be transmitted to the preliminary chamber 12 side in a state where the boat 34 is accommodated in the processing chamber 46.
A drive control unit 36 is electrically connected to the rotation mechanism 32 and the motor 27 of the boat elevator 24 by an electrical wiring 37. The drive control unit 36 controls these at a desired timing so that the rotation mechanism 32 and the motor 27 of the boat elevator 24 perform desired operations.

A reaction furnace 40 is installed on the housing 11 corresponding to the boat loading / unloading port 15.
The reaction furnace 40 has a heater 42 as a heating mechanism. The heater 42 is formed in a cylindrical shape, and is vertically installed by being supported by a heater base 41 as a holding plate.
The heater 42 is divided into five zones: a U zone (upper zone) 42a, a CU zone (center upper zone) 42b, a C zone (center zone) 42c, a CL zone (center lower zone) 42d, and an L zone (lower zone) 42e. .

Inside the heater 42, a process tube 43 as a reaction tube is disposed concentrically with the heater 42. The process tube 43 is composed of an outer tube 44 as an external reaction tube and an inner tube 45 as an internal reaction tube provided on the inner side.
The outer tube 44 is formed by using a heat resistant material such as quartz (SiO ₂ ) or silicon carbide (SiC). The outer tube 44 is formed in a cylindrical shape having an inner diameter larger than the outer diameter of the inner tube 45 and closed at the upper end and opened at the lower end, and is provided concentrically with the inner tube 45.
The inner tube 45 is made of a heat-resistant material such as quartz or silicon carbide, and is formed in a cylindrical shape whose upper and lower ends are open. A cylindrical hollow portion of the inner tube 45 forms a processing chamber 46, and the processing chamber 46 accommodates a plurality of wafers 1 in a state where they are aligned in a plurality of stages in a vertical posture in a horizontal posture by the boat 34.
A cylindrical space 47 is formed by a gap between the outer tube 44 and the inner tube 45.

A manifold 49 is disposed below the outer tube 44 concentrically with the outer tube 44 via an O-ring 48 as a seal member. The manifold 49 is made of, for example, stainless steel, and is formed in a cylindrical shape having an open upper end and a lower end.
The manifold 49 engages with and supports the outer tube 44 and the inner tube 45. Since the manifold 49 is supported by the heater base 41 and the ceiling wall of the casing 11, the process tube 43 is installed vertically.
A reaction vessel is formed by the process tube 43 and the manifold 49.

  A temperature sensor 50 as a temperature detector is installed in the process tube 43. A temperature control unit 51 is electrically connected to the heater 42 and the temperature sensor 50 by an electric wiring 52. The temperature control unit 51 adjusts the power supply to the heater 42 based on the temperature information detected by the temperature sensor 50, thereby controlling the temperature in the processing chamber 46 at a desired timing so that the temperature in the processing chamber 46 becomes a desired temperature distribution.

The manifold 49 is provided with an exhaust pipe 53 for exhausting the atmosphere in the processing chamber 46. The exhaust pipe 53 is disposed at the lower end portion of the cylindrical space 47 formed by the gap between the outer tube 44 and the inner tube 45, and communicates with the cylindrical space 47.
A mechanical booster pump (MBP) 19 and a dry pump (DP) 20 are connected to a downstream side of the exhaust pipe 53 opposite to the connection side with the manifold 49 via a pressure sensor 54 and a pressure adjusting device 55 as a pressure detector. Etc. are connected. The pressure sensor 54, the pressure adjusting device 55, the mechanical booster pump 19, and the dry pump 20 evacuate so that the pressure in the processing chamber 46 becomes a predetermined pressure (degree of vacuum).
A pressure control unit 56 is electrically connected to the pressure sensor 54 and the pressure adjusting device 55 by an electric wiring 57. Based on the pressure detected by the pressure sensor 54, the pressure control unit 56 controls the pressure adjusting device 55 at a desired timing so that the pressure in the processing chamber 46 becomes a desired pressure.

A plurality of nozzles as gas introduction portions are connected to the manifold 49 so as to communicate with the inside of the processing chamber 46.
The plurality of nozzles is composed of four long nozzles having elbow tube shapes (L-type) having different lengths and one short nozzle having a straight tube shape (I-type).
The first long nozzle N1, the second long nozzle N2, the third long nozzle N3 and the fourth long nozzle N4 are provided between the boat 34 and the inner tube 45, and face the heater 42 which is a wafer group arrangement region. Stand up to the area to do.
The gas outlets of the first long nozzle N1, the second long nozzle N2, the third long nozzle N3, and the fourth long nozzle N4 are respectively located at different heights in the region corresponding to the wafer group arrangement region. Opening is performed upward in the wafer group arrangement direction (vertical direction).
The gas nozzle of the short nozzle N5, which is the fifth nozzle, is an area facing the manifold 49, which is an area upstream of the wafer group arrangement area, that is, an area below the wafer group arrangement area and a wafer group. It is located in a region where the temperature is lower than that of the array region, and opens in a direction perpendicular to the wafer group array direction (horizontal direction).
In FIG. 2, for the sake of convenience, only the first long nozzle N1, which is the first nozzle, is shown, and the other nozzles are not shown.

Gas supply lines L1 to L5 are connected to the nozzles N1 to N5, respectively. A gas supply / flow rate controller M including a plurality of valves and a plurality of gas flow controllers (mass flow controllers) on the upstream side of the gas supply lines L1 to L5 opposite to the connection side with the nozzles N1 to N5. A gas supply unit G including a plurality of gas supply sources is connected via the.
A gas supply / flow rate controller 58 is electrically connected to the gas supply / flow rate controller M via an electrical wiring 59. The gas supply / flow rate controller 58 controls the gas supply / flow rate controller M at a desired timing so that the gas flow rates of the respective gases flowing through the gas supply lines L1 to L5 become a desired amount.
FIG. 10A and FIG. 10B show specific examples of the gas supply system.
FIG. 10A shows an example (hereinafter referred to as a first supply system example) used when a first pretreatment sequence described later is performed.
In the first supply system example, the first gas supply source G1 supplies hydrogen (H ₂ ) gas to the gas supply lines L1 to L5. The second gas supply source G2 supplies monosilane (SiH ₄ ) gas to the gas supply line L5. The third gas supply source G3 supplies nitrogen (N ₂ ) gas to the gas supply lines L1 to L5.
The gas supply lines L1 to L5 that supply hydrogen gas from the first gas supply source G1 are provided with upstream valves U1 to U5, mass flow controllers C1 to C5, and downstream valves D1 to D5, respectively, in order from the upstream side. ing.
An upstream valve U6, a mass flow controller C6, and a downstream valve D6 are provided in order from the upstream side to the connection line that supplies the monosilane gas from the second gas supply source G2 to the gas supply line L5.
An upstream valve U7, a mass flow controller C7, and a downstream valve D7 are provided in order from the upstream side to the connection line that supplies nitrogen gas from the third gas supply source G3 to the gas supply lines L1 to L5. The gas supply unit G includes a first gas supply source G1, a second gas supply source G2, and a third gas supply source G3. The gas supply / flow rate controller M includes upstream valves U1 to U7, a mass flow controller C1. -C7 and the downstream side valves D1-D7 are included.
That is, in the first supply system example, when hydrogen gas is used as the pretreatment gas, the flow rate and concentration of the hydrogen gas are controlled by controlling each valve and each mass flow controller of the gas supply / flow rate controller M. It can be changed for each of the supply lines L1 to L5, that is, for each of the nozzles N1 to N5.
FIG. 10B shows an example (hereinafter referred to as a second supply system example) used when a second pretreatment sequence described later is performed.
In the second supply system example, the first gas supply source G1 supplies hydrogen gas to the gas supply lines L1 to L5. The second gas supply source G2 supplies monosilane gas to the gas supply lines L1 to L5. The fourth gas supply source G4 supplies chlorine (Cl ₂ ) gas to the gas supply lines L1 to N5. The third gas supply source G3 supplies nitrogen gas to the gas supply lines L1 to L5.
The gas supply lines L1 to L5 that supply hydrogen gas from the first gas supply source G1 are provided with upstream valves U1 to U5, mass flow controllers C1 to C5, and downstream valves D1 to D5, respectively, in order from the upstream side. ing.
The upstream valves U11 to U15, the mass flow controllers C11 to C15, and the downstream valves D11 to D15 are provided in order from the upstream side to the connection lines that supply the monosilane gas from the second gas supply source G2 to the gas supply lines L1 to L5. Each is provided.
The upstream valves U16 to U20, the mass flow controllers C16 to C20, and the downstream valves D16 to D20 are connected in order from the upstream side to the connection lines that supply chlorine gas from the fourth gas supply source G4 to the gas supply lines L1 to L5. Are provided.
The upstream valves U21 to U25, the mass flow controllers C21 to C25, and the downstream valves D21 to D25 are connected in order from the upstream side to the connection lines that supply nitrogen gas from the third gas supply source G3 to the gas supply lines L1 to L5. Are provided. The gas supply unit G includes a first gas supply source G1, a second gas supply source G2, a third gas supply source G3, and a fourth gas supply source G4. The gas supply / flow rate controller M is an upstream valve. U1-U5, U11-U25, mass flow controllers C1-C5, C11-C25, downstream valves D1-D5, D11-D25 are included.
That is, in the second supply system example, by controlling each valve and each mass flow controller of the gas supply / flow rate controller M, the flow rate and concentration of hydrogen gas, monosilane gas, and chlorine gas are set for each of the gas supply lines L1 to L5. Each of the nozzles N1 to N5 can be changed.

The drive control unit 36, the temperature control unit 51, the pressure control unit 56, and the gas flow rate control unit 58 also constitute an operation unit and an input / output unit, which are electrically connected to the main control unit 60 that controls the entire CVD apparatus 10. It is connected to the.
These drive control unit 36, temperature control unit 51, pressure control unit 56, gas flow rate control unit 58 and main control unit 60 constitute a controller 61.

Next, as a process of manufacturing a semiconductor device according to an embodiment of the present invention, a polycrystalline silicon film or a single crystal silicon film (hereinafter referred to as silicon) is formed on the wafer using the CVD apparatus 10 according to the above configuration. A method for forming a film) will be described with reference to FIGS.
3 and 4 are sequence flowcharts showing a method of forming a silicon film on a wafer. The temperature change in the furnace, each step name, nitrogen (N ₂ ) gas, hydrogen (H ₂ ) gas, silane (SiH ₄ ). Each timing of supply of gas, chlorine (Cl ₂ ) gas, etc., and the pressure change in the furnace are shown.
3 and 4, the horizontal axis represents the passage of time, and the vertical axis represents the furnace temperature, each step, the supply state of each gas, and the furnace pressure.
FIG. 3 shows a silicon film forming method according to the first embodiment, and FIG. 4 shows a silicon film forming method according to the second embodiment.
In the following description, the operation of each part constituting the CVD apparatus 10 is controlled by the controller 61.

After removing the natural oxide film on the surface of the silicon wafer with dilute hydrofluoric acid and simultaneously terminating the surface with hydrogen, the boat 34 in the spare chamber 12 is loaded with one batch of wafers 1, for example, 100 to 150 wafers 1. (Wafer charge step).
Next, purging with an inert gas in the preliminary chamber 12, for example, nitrogen purge is performed (pre-purge step), and evacuation and nitrogen purge are repeatedly performed in the preliminary chamber 12 (cycle purge step). Thereby, oxygen and moisture in the atmosphere in the preliminary chamber 12 are sufficiently removed.
Thereafter, the boat elevator 24 raises the wafer group loaded boat 34 and loads it into the processing chamber 46 via the boat loading / unloading port 15 (boat loading step).
When the loading of the boat 34 supporting the plurality of wafers 1 into the processing chamber 46 is completed, the seal cap 30 comes into contact with the lower surface of the ceiling wall of the housing 11 constituting the boat loading / unloading port 15 via the O-ring 31. The inside of the processing chamber 46 is sealed by closing the boat loading / unloading port 15.
At this time, in order to prevent wafer surface oxidation during the boat loading step, the wafer carry-in temperature, for example, 100 to 400 ° C., in which the temperature in the reaction furnace 40 (processing chamber 46) (hereinafter referred to as the furnace) is lower than the wafer processing temperature. The temperature control unit 51 controls the heater 42 so that the temperature becomes a certain level.
3 and 4, the wafer carry-in temperature is adjusted to 200 ° C.
Note that the furnace pressure is atmospheric pressure (ATM) from the wafer charge step to the boat loading step.

Next, the inside of the furnace is evacuated by the mechanical booster pump 19 and the dry pump 20 while maintaining the inside temperature at the wafer carry-in temperature (evacuation step).
At this time, the pressure control unit 56 controls the pressure adjusting device 55 so that the furnace pressure is adjusted to a pressure lower than the atmospheric pressure and lower than the wafer processing pressure, for example, about 1 to 10,000 Pa.
In the case of FIG. 3 and FIG. 4, the furnace pressure is adjusted to 1 Pa.
At this time, the drive control unit 36 rotates the boat 34 at a predetermined rotation speed by the rotation mechanism 32.

  The steps so far are the initial steps common to the sequence of the silicon film forming method according to the first embodiment and the second embodiment shown in FIGS.

Next, a hydrogen gas use contamination removal sequence (hereinafter referred to as a first pretreatment sequence) in the first embodiment shown in FIG. 3 will be described.
After the furnace pressure is adjusted to a predetermined pressure (45 Pa in this case), the inside of the furnace is purged with hydrogen gas while hydrogen gas is being supplied into the furnace, and the inside of the furnace is purged with hydrogen gas (hydrogen purging step). ).
Thereafter, with the supply and exhaust of hydrogen gas to the furnace maintained, the furnace temperature is raised from the wafer carry-in temperature to a first pretreatment temperature, for example, about 750 to 850 ° C. (temperature raising step). .
Supply of hydrogen gas into the furnace is started before the temperature raising step, that is, from the hydrogen purge step.
Supplying and exhausting hydrogen gas into the furnace is a temperature lowering step for lowering the furnace temperature from the first pretreatment temperature (750 to 850 ° C.) to a film forming temperature (620 ° C.) described later, and the furnace temperature to the film forming temperature. This is continuously performed until the temperature stabilization step for stabilization is completed.
Hydrogen gas is supplied into the furnace from all the nozzles N1 to N5 shown in FIG. That is, the gas nozzle is supplied from the short nozzle N5 located in the region corresponding to the manifold 49 and the gas nozzle from the long nozzles N1 to N4 located in the region corresponding to the wafer group arrangement region. The hydrogen gas supplied into the furnace rises in the furnace, flows down the cylindrical space 47 and is exhausted from the exhaust pipe 53.

By supplying and exhausting the hydrogen gas for a predetermined time, the removal process of the natural oxide film and the contaminant on the wafer is continued for a predetermined time. The reaction mechanism in the removal process of the natural oxide film and contaminants, that is, the removal mechanism of oxygen (O), carbon (C), and the natural oxide film (SiO ₂ ) by hydrogen will be discussed below.
It is considered that the following reaction proceeds by supplying hydrogen gas into the furnace.
In addition, what attached | subjected * in the following formula has shown that it is an active species.
1) H ₂ → 2H ^*
2) 2H ^* + O → H ₂ O ↑
3) 2H ₂ + C → CH ₄ ↑
4) SiO ₂ + 2H ^* → SiO ↑ + H ₂ O ↑
In the temperature range of 750 to 850 ° C., it is considered that H ₂ is separated into a form such as chemically active H ^* (Reaction Formula 1)).
They are considered to be removed by reacting with oxygen, carbon and natural oxide film remaining in the furnace atmosphere, evaporating in the form of H ₂ O, CH ₄ and SiO, and exhausting them outside the furnace. (Scheme 2), 3), 4)).

Next, a decontamination sequence (hereinafter referred to as a second pretreatment sequence) using hydrogen gas, silane gas and chlorine gas in the second embodiment shown in FIG. 4 will be described.
After the furnace pressure is adjusted to a predetermined pressure (45 Pa in this case), the inside of the furnace is purged with hydrogen gas while hydrogen gas is being supplied into the furnace, and the inside of the furnace is purged with hydrogen gas (hydrogen purging step). ).
Thereafter, with the supply and exhaust of hydrogen gas to the furnace maintained, the furnace temperature is raised from the wafer carry-in temperature to a second pretreatment temperature, for example, about 620 ° C. (temperature raising step). .
In the second embodiment, the second pretreatment temperature is set to the same film forming temperature, which will be described later.
From this temperature raising step, supply of silane gas and chlorine gas into the furnace is started.
That is, at this time, while the hydrogen gas, the silane gas, and the chlorine gas are supplied into the furnace, the inside of the furnace is exhausted (hydrogen + silane + chlorine purge step).
The pressure in the furnace at this time is adjusted to 50 Pa, for example.
Note that the silane gas and the chlorine gas continue to be supplied for a predetermined time after the temperature raising step is completed.
When the supply of silane gas and chlorine gas is stopped while the supply of hydrogen gas is maintained, the hydrogen purge step is performed again. That is, the supply and exhaust of hydrogen gas is continuously performed from the hydrogen purge step before the temperature raising step to the completion of the hydrogen purge step after the temperature raising step.
By performing the hydrogen purge step after the supply of silane gas and chlorine gas is stopped, chlorine remaining on the wafer surface can be removed.
Hydrogen gas, silane gas, and chlorine gas are supplied into the furnace from all the nozzles N1 to N5 shown in FIG. That is, hydrogen gas is supplied from the short nozzle N5 in which the gas outlet is located in the region corresponding to the manifold 49 and the long nozzles N1 to N4 in which the gas outlet is located in the region corresponding to the wafer group arrangement region in the hydrogen purge step. In the hydrogen + silane + chlorine purge step, a mixed gas of hydrogen gas, silane gas, and chlorine gas is supplied. Hydrogen gas, silane gas, and chlorine gas supplied into the furnace rise in the furnace, flow down the cylindrical space 47, and are exhausted from the exhaust pipe 53.

By supplying and exhausting the hydrogen gas, the silane gas, and the chlorine gas for a predetermined time, the natural oxide film and the contaminant removal process for the wafer is continued for a predetermined time. The reaction mechanism in the removal process of the natural oxide film and contaminants is discussed below.
First, the mechanism for removing moisture (H ₂ O) and oxygen (O) by silane will be described.
It is considered that the next reaction proceeds by supplying silane gas into the furnace.
5) SiH ₄ → SiH ₂ + H ₂
6) SiH ₄ → SiH ₃ + H ^*
7) SiH ₂ + H ₂ O ↑ → SiO ↑ + 2H ₂
8) 2SiH ₂ + O ₂ → 2SiO ↑ + 2H ₂
9) 2H ^* + O → H ₂ O ↑
10) SiH ₄ + SiO ₂ → 2SiO ↑ + 2H ₂
In a relatively low temperature region within the range of 200 to 620 ° C., silane (SiH ₄ ) is not completely decomposed but is considered to be separated into forms such as SiH ₂ and H ₂ or SiH ₃ and H. (Scheme 5), 6)).
It is considered that they react with moisture and oxygen remaining in the furnace atmosphere, are vaporized in the form of SiO and H ₂ O, respectively, and are removed by being exhausted outside the furnace (Reaction Formula 7). , 8), 9)).
However, since the temperature is relatively low, the SiO ₂ formed on the wafer surface has not yet been removed as in the reaction formula 10).
Next, a mechanism for removing oxygen (O) and carbon (C) by chlorine will be described.
It is considered that the following reaction proceeds when chlorine gas is supplied into the furnace.
11) 2Cl ₂ + Si → SiCl ₄ ↑
If no direct reaction between O and C by Cl _2, can be considered, when Si is etched by Cl _2, it is considered (Scheme 11)).
At that time, it is considered that O or C adsorbed on Si is lifted up and removed together with Si.

  The first pretreatment sequence and the second pretreatment sequence are each effective for removing the natural oxide film and the contaminants from the wafer, but it is also possible to combine both. By combining the two, a higher natural oxide film or impurity removal effect can be obtained.

After completion of the first pretreatment sequence or the second pretreatment sequence, a film forming step is performed.
From here on, the steps are common to the sequence of the silicon film forming method shown in FIGS.
When the heater 42 is controlled by the temperature control unit 51 and the furnace temperature is stabilized at the film formation temperature (620 ° C.) (temperature stabilization step), the supply of hydrogen gas to the furnace is stopped and silane gas is introduced into the furnace. Supplied. At this time, the furnace pressure is adjusted to 20 Pa, for example. Silane gas is supplied from the short nozzle N5 into the furnace. Silane gas may be supplied into the furnace from all nozzles N1 to N5. The silane gas supplied into the furnace rises in the furnace, flows down the cylindrical space 47 and is exhausted from the exhaust pipe 53.
Since the supplied silane gas is decomposed in a reduced-pressure atmosphere heated by the heater 42, a silicon film is formed on the wafer surface by a thermal CVD reaction (film formation step).
If the wafer surface is cleaned by the first pretreatment sequence or the second pretreatment sequence, a polycrystalline silicon film is formed when the film formation base is polycrystalline silicon (poly-Si). In the case of single crystal silicon, a single crystal silicon film is formed.
Thus, according to this embodiment, it is possible to form a single crystal silicon film at a low temperature of 620 ° C.
By stopping the supply of silane gas, the film forming step for the wafer is completed.

After the film forming step on the wafer is completed, the pressure in the furnace is adjusted to a predetermined pressure, for example, about 1 to 10,000 Pa. Here, the furnace pressure is adjusted to 15 Pa.
Simultaneously with the silane gas supply stop, the inside of the furnace is purged with nitrogen gas, whereby the inside of the furnace is replaced with nitrogen gas.
Thereafter, while the supply of nitrogen gas into the furnace is maintained, the pressure in the furnace is raised to return to atmospheric pressure (atmospheric pressure return step).
After the return to atmospheric pressure step, the boat 34 holding the processed wafer, that is, the wafer on which the single crystal silicon film or the polycrystalline silicon film is formed, is lowered by the boat elevator 24 and carried out of the processing chamber 46 (boat unloading). Step).
The boat 34 stands by in the preliminary chamber 12 until all the wafers 1 held in the boat 34 are cooled (wafer cooling step).
When all the wafers 1 held in the waited boat 34 are cooled to a predetermined temperature, the wafers 1 are taken out from the boat 34 by a wafer transfer device (not shown) and collected in a wafer carrier (not shown). (Wafer discharge step).
For the next sequence, in parallel with the wafer cooling step, the furnace temperature is lowered from the film formation temperature to a predetermined wafer carry-in temperature, for example, a temperature of about 300 to 600 ° C. (here, 200 ° C.). (In-furnace cooling step).

As a result of intensive studies on the above silicon film forming method, the present inventors have found the following phenomenon.
Like the CVD apparatus 10 in the present embodiment, a reaction vessel is formed by the process tube 43 and the manifold 49 provided below the process tube 43 so that the gas flows from the manifold 49 side toward the upper portion of the process tube 43. In the case of such a substrate processing apparatus, in the portion of the manifold 49 that is lower than the wafer group arrangement region and lower in temperature than the wafer group arrangement region and in the upper part of the wafer group arrangement region (near the downstream end of the wafer group arrangement region) The degree of contamination with oxygen, carbon, etc. is greater than other parts.

The present inventor considered the reason why this phenomenon occurs as follows.
In the film forming step, the gas introduced from the short nozzle N5 in the vicinity of the manifold 49 having a relatively low temperature below the wafer group arrangement region moves up in the processing chamber 46 and performs the film forming process on the wafer 1. Thereafter, the gas is exhausted from the exhaust pipe 53 through a cylindrical space 47 formed between the outer tube 44 and the inner tube 45.
If the inside of the furnace is divided into three areas, that is, the upper part of the wafer group arrangement area, the part other than the upper part of the wafer group arrangement area, and the vicinity of the manifold 49, the interface impurity density such as oxygen and carbon with respect to the wafer is It becomes relatively large in the upper part and in the vicinity of the manifold 49.
The reason why the interfacial impurity density becomes relatively large in the vicinity of the manifold 49 is considered to be contamination due to desorption of moisture and organic substances adhering to the manifold 49.
Moisture and organic substances that cause interface impurities are more likely to be adsorbed on the surface as the ambient temperature is lower. Therefore, more moisture and organic substances are adsorbed near the manifold 49 having a relatively low temperature in the furnace than in other areas. It can be considered that they are desorbed at the time of temperature rise in the film forming sequence and adsorbed to the wafer 1 in the vicinity of the manifold 49.
The reason why the interfacial impurity density is relatively high in the upper part of the wafer group arrangement region is considered to be contamination due to desorption of moisture and organic substances adhering to the wafer 1 and the boat 34.
The desorbed moisture and organic matter flow from the bottom to the top in the wafer group arrangement area due to the structure of the reaction furnace 40. Therefore, assuming that the wafer 1 is uniformly arranged in the wafer group arrangement area, the wafer group arrangement area It is considered that the upper part of the wafer group arrangement region on the downstream side is affected by desorbed moisture / organic matter from more parts than the wafers 1 and the surface of the boat 34.
In addition, due to the structure of the reaction furnace 40, it is considered that the influence of the back diffusion of impurities from the exhaust side is more strongly received in the upper part of the wafer group arrangement region located in the vicinity of the cylindrical space 47.

The inventor thus has a greater degree of contamination than other parts,
(1) An area below the wafer group arrangement area (upstream side of the wafer group arrangement area), that is, an area corresponding to a manifold having a lower temperature than the wafer group arrangement area, and
(2) An area corresponding to the upper part of the wafer group arrangement area (downstream end of the wafer group arrangement area),
It was found that this phenomenon can be improved by positively supplying the pretreatment gas.

  Next, an experiment conducted to investigate the difference of the natural oxide film / contaminant removal effect on the wafer (hereinafter referred to as the contamination removal effect) depending on the number of supply gas systems will be described.

FIG. 5 shows the evaluation apparatus used in the experiment.
In addition, about the component same as FIG. 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
In the first evaluation apparatus shown in FIG. 5A, hydrogen gas is introduced into the furnace using only one system of the short nozzle N5, and after the first pretreatment sequence for the wafer 1 is performed, the short nozzle N5 Silane gas was introduced into the furnace to perform the film forming step.
Interfacial oxygen / carbon density, which is an index of the decontamination effect, was measured on monitor wafers installed in the center region (89th sheet) and upper region (167th sheet) of the boat 34.
In the second evaluation apparatus shown in FIG. 5B, hydrogen gas is introduced into the furnace by two systems of the short nozzle N5 and one long nozzle N1, and the first pretreatment sequence for the wafer 1 is performed. Then, a silane gas was introduced into the furnace from the short nozzle N5 to perform a film forming step. That is, in the first pretreatment sequence, not only the hydrogen is supplied from the vicinity of the manifold 49 by the short nozzle N5, but also the boat upper region (167th sheet) which is relatively highly affected by degassing from the boat 34 and the wafer 1. In order to improve the interface characteristics, hydrogen gas was additionally introduced from the lower side (150th sheet) by the long nozzle N1. As in the experiment using the first evaluation apparatus, monitor wafers were installed in the central area (89th sheet) and the upper area (167th sheet) of the boat 34 to measure the interfacial oxygen / carbon density.

FIG. 6 is a graph showing experimental results.
In FIG. 6, the horizontal axis indicates the difference in the number of evaluation apparatuses, that is, the supply gas systems, and the vertical axis indicates the interfacial oxygen / carbon density (atoms / cm ² ).
In this experiment, the hydrogen gas purge temperature of the first pretreatment sequence was 800 ° C., the hydrogen gas purge time was 30 minutes, and the supply flow rate of hydrogen gas supplied from each nozzle was 5 slm.
In the film forming step, the supply flow rate of silane gas was set to 0.5 slm, and a polycrystalline silicon film having a thickness of about 200 nm was formed on the polycrystalline silicon film having a thickness of about 100 nm as the base film.
The interface characteristics were measured by SIMS (Secondary Ionization Mass Spectrometer).

According to FIG. 6, it can be seen that in the first evaluation apparatus having one hydrogen gas system, the influence of contamination due to degassing from the boat and wafer is relatively high in the boat upper region.
When the interface characteristics of the monitor wafers installed in the boat center area (89th sheet) are compared, there is almost no difference between the first evaluation apparatus and the second evaluation apparatus.
From this, it can be seen that there is almost no error between the evaluation batches and the increase in the hydrogen gas flow rate when the number of hydrogen gas systems is changed from one to two, the influence of the pressure increase during the hydrogen gas purge.
On the other hand, when the interface characteristics of the monitor wafer installed in the upper region (the 167th sheet) are compared between the first evaluation device and the second evaluation device, the number of hydrogen gas systems is increased from one system to two systems. With respect to (167th sheet), by additionally supplying hydrogen gas slightly upstream (upstream side) of the upper region (167th sheet), the oxygen density can be reduced by about 61% and the carbon density can be reduced by about 44%. It can be seen that the contamination density is greatly reduced.
For this reason, additional pretreatment gases such as hydrogen gas are supplied in multiple systems to uniformly remove contaminants on the wafer surface that are non-uniformly introduced in the direction between the wafer surfaces, and to produce a high-quality interface for mass production processing. It can be formed uniformly in the wafer group arrangement region (100 to 150).

In the case of FIG. 5B, the gas type, supply flow rate, and concentration of the pretreatment gas as the interface cleaning gas supplied to the long nozzle N1 and the short nozzle N5 are the same.
That is, the gas type of the pretreatment gas supplied to the long nozzle N1 and the short nozzle N5 is hydrogen gas. Further, the flow rate of hydrogen gas supplied to the long nozzle N1 and the short nozzle N5 is 5 slm. Further, the concentration of hydrogen gas supplied to the long nozzle N1 and the short nozzle N5 is 100%.

  However, for example, when the degree of contamination in the processing chamber is uneven in the inter-surface direction, the gas type, supply flow rate, and concentration of the pretreatment gas as the interface cleaning gas supplied to each nozzle are as follows. It may be varied according to the amount of contamination.

(1) For example, when the degree of contamination in the upper portion of the processing chamber is larger than that in other portions, the supply flow rate or concentration of the pretreatment gas supplied from the long nozzle N1 to the upper portion of the processing chamber is supplied to the other portions. It may be made larger than the supply flow rate or concentration of the pretreatment gas.
Further, the gas type of the pretreatment gas supplied from the long nozzle N1 to the upper part of the processing chamber may be different from the gas type of the pretreatment gas supplied to other portions.
For example, in the case of the apparatus shown in FIG. 5B, the supply flow rate of hydrogen gas supplied from the long nozzle N1 to the upper portion of the processing chamber and the supply flow rate of hydrogen gas supplied from the short nozzle N5 to the lower portion of the processing chamber are 7 slm and 5 slm, respectively. Alternatively, the concentration of hydrogen gas supplied from the long nozzle N1 to the upper portion of the processing chamber and the concentration of hydrogen gas supplied from the short nozzle N5 to the lower portion of the processing chamber are set to 100% and 80%, respectively. May be.
Further, the pretreatment gas supplied from the long nozzle N1 to the upper portion of the processing chamber may be a mixed gas of hydrogen gas, silane gas and chlorine gas, and the pretreatment gas supplied to the lower portion of the processing chamber from the short nozzle N5 may be hydrogen gas. Good.

(2) For example, when the degree of contamination in the upper and lower portions of the processing chamber is larger than that in other portions, the supply flow rate or concentration of the pretreatment gas supplied to the upper and lower portions in the processing chamber is set to other portions. It may be made larger than the supply flow rate or concentration of the pretreatment gas to be supplied.
Further, the gas type of the pretreatment gas supplied to the upper part and the lower part of the processing chamber may be different from the gas type of the pretreatment gas supplied to other parts.
For example, in the above-described CVD apparatus 10 of FIGS. 1 and 2, the supply flow rate of hydrogen gas supplied from the longest long nozzle N1 to the upper part of the processing chamber, and the hydrogen supplied from the second long nozzle N2 to the upper center of the processing chamber. Gas supply flow rate, hydrogen gas supply flow rate supplied from the third long (second shortest) long nozzle N3 to the lower center of the processing chamber, and hydrogen gas supply flow rate supplied from the shortest long nozzle N4 to the bottom of the processing chamber The supply flow rate of hydrogen gas supplied from the short nozzle N5 to the lower portion of the processing chamber may be 8 slm, 6 slm, 5 slm, 6 slm, and 7 slm, respectively.
The concentration of hydrogen gas supplied from the longest long nozzle N1 to the upper part of the processing chamber, the concentration of hydrogen gas supplied from the second longest nozzle N2 to the upper center of the processing chamber, and the third longest (second shortest). The concentration of hydrogen gas supplied from the long nozzle N3 to the lower center of the processing chamber, the concentration of hydrogen gas supplied from the shortest long nozzle N4 to the bottom of the processing chamber, and the concentration of hydrogen gas supplied from the short nozzle N5 to the lower portion of the processing chamber, They may be 100%, 80%, 80%, 90%, and 100%, respectively.
The pretreatment gas supplied from the longest long nozzle N1 to the upper part of the processing chamber is a mixed gas of hydrogen gas, silane gas and chlorine gas, and is supplied from the second longest nozzle N2 to the upper center of the processing chamber. The pretreatment gas supplied from the third long (second shortest) long nozzle N3 to the lower center of the processing chamber and the pretreatment gas supplied from the shortest long nozzle N4 to the bottom of the processing chamber are hydrogen gas, and the short nozzle N5 Alternatively, the pretreatment gas supplied to the lower part of the treatment chamber may be a mixed gas of hydrogen gas, silane gas, and chlorine gas.

That is, in the step of performing the pretreatment, the pretreatment gas is supplied from a plurality of locations in the processing chamber, and the supply flow rate, concentration, or type of the pretreatment gas is set at at least one of the plurality of locations and other locations. You may make it differ.
In this way, by changing the supply flow rate, concentration, or type of the pretreatment gas at each position in accordance with the degree of contamination at each position in the processing chamber, the natural oxide film or impurities on the wafer are changed between the wafer surfaces. Since it can be removed efficiently and uniformly in the direction, a high-quality interface with low oxygen and carbon density can be uniformly formed in a mass production process of batch processing of 100 to 150 sheets.

(3) Also, for example, when the degree of contamination in the upper and lower portions of the processing chamber is greater than that of other portions, the pretreatment gas supplied from the upper and lower portions of the processing chamber is mixed with a plurality of types of pretreatment gases. When the pretreatment gas supplied from other parts of the processing chamber is the same mixed gas as the mixed gas, the supply flow rates of the plurality of types of pretreatment gases supplied from the upper and lower portions of the processing chamber The ratio or the concentration ratio may be different from the supply flow rate ratio or concentration ratio of a plurality of types of pretreatment gases supplied from other portions.
For example, in the above-described CVD apparatus 10, when a mixed gas of hydrogen gas, silane gas, and chlorine gas is supplied from each nozzle as a pretreatment gas, the hydrogen gas, silane gas, and chlorine supplied from the long nozzle N 1 to the upper portion of the processing chamber. Supply flow ratio with gas, supply flow ratio between hydrogen gas, silane gas and chlorine gas supplied from the long nozzles N2, N3, N4 to the upper center, lower center and bottom of the processing chamber, and supply from the short nozzle N5 to the lower processing chamber The supply flow ratios of hydrogen gas, silane gas, and chlorine gas may be 5: 3: 2, 8: 1: 1, and 6: 3: 1, respectively.

That is, in the step of performing the pretreatment, a plurality of types of pretreatment gases are supplied from a plurality of locations in the processing chamber, and the supply flow rates of the plurality of types of pretreatment gases at at least one of the plurality of locations and other locations. The ratio or the concentration ratio may be varied.
In this way, by changing the supply flow rate ratio or concentration ratio of multiple types of pretreatment gases at each position in accordance with the degree of contamination at each position in the processing chamber, the natural oxide film or impurities on the wafer are removed from the wafer. Since it can be removed efficiently and uniformly across the plane, a high-quality interface with low oxygen and carbon density can be uniformly formed by a mass production process of 100 to 150 sheets.

The plurality of locations in the processing chamber for supplying the pretreatment gas are preferably at least one location in the region upstream of the wafer group arrangement region and at least one location in the region corresponding to the wafer group arrangement region.
More preferably, the pretreatment gas is supplied from at least one location in the region corresponding to the manifold and at least one location in the upper portion in the region corresponding to the wafer group arrangement region.
That is, it is more preferable that the pretreatment gas is supplied from at least one location in the region where the temperature is lower than that of the wafer group arrangement region and from at least one location at the downstream end in the region corresponding to the wafer group arrangement region.
It is more preferable to supply from at least one place in the area below the wafer group arrangement area and at least one place in the upper part of the area corresponding to the wafer group arrangement area.
The pretreatment gas nozzle that supplies the pretreatment gas and the main processing gas nozzle that supplies the film forming gas as the main processing gas are preferably the same nozzle.

  Next, in the case where the degree of contamination in the lower part of the processing chamber is large and the flow rate ratio between chlorine gas and hydrogen gas supplied as pretreatment gas from the short nozzle N5 to the lower part of the processing chamber is changed ( An experiment conducted to investigate the difference in the interfacial oxygen density will be described.

The experiment was performed using the first evaluation apparatus shown in FIG.
That is, using the first evaluation apparatus shown in FIG. 5A, a mixed gas of chlorine gas and hydrogen gas is introduced into the furnace as a pretreatment gas and the wafer is pretreated, and then the wafer is subjected to D−. A polySi film was formed to a thickness of 100 nm.
During the pretreatment, the flow rate ratio between chlorine gas and hydrogen gas was changed in two ways: chlorine / hydrogen = 0.02 and chlorine / hydrogen = 0.1.
The interface contaminant (interface oxygen density) was measured by installing a monitor wafer in the lower area (11th sheet) of the boat.

FIG. 7 shows the difference in interfacial oxygen density depending on the flow rate ratio between chlorine gas and hydrogen gas.
In FIG. 7, the horizontal axis indicates the flow rate ratio (chlorine / hydrogen) between chlorine gas and hydrogen gas, and the vertical axis indicates the interfacial oxygen density (atoms / cm ² ).
Interface characteristics were measured by SIMS.

According to FIG. 7, the following can be understood.
In the pretreatment, when the flow rate ratio between chlorine gas and hydrogen gas is set to chlorine / hydrogen = 0.1, the interfacial oxygen density is lower than when chlorine / hydrogen = 0.02.
That is, when the ratio of chlorine gas to hydrogen gas (chlorine / hydrogen) is increased, a low-oxygen and high-quality interface is obtained. This is presumably because the etching of the wafer was promoted and the contamination removal effect was enhanced by the increase in the proportion of chlorine gas.

As discussed in the description of the second pretreatment sequence, when chlorine gas is used, the interface impurities are removed by etching the silicon wafer using the reaction of Cl ₂ and Si as shown in reaction formula 11). can do.
In this case, in order to make the film thickness distribution in the direction between the wafer surfaces after the pretreatment uniform, it is necessary to make the silicon etching amount uniform in the direction between the wafer surfaces.

  For example, in the above-described CVD apparatus 10, when the degree of silicon etching in the upper portion of the processing chamber is larger than that in other portions, the supply flow rate or concentration of the pretreatment gas supplied from the long nozzle N 1 to the upper portion of the processing chamber is changed. The supply flow rate or concentration of the pretreatment gas supplied to this portion is made smaller, or the gas type of the pretreatment gas supplied from the long nozzle N1 to the upper part of the treatment chamber is made different from the gas type supplied to other portions. May be.

  Next, in the case where the degree of contamination in the lower part of the processing chamber is large, the flow rate ratio between chlorine gas and hydrogen gas supplied from the short nozzle N5 to the lower part of the processing chamber and the flow rate ratio between silane gas and chlorine gas are An experiment conducted to investigate the difference in the amount of silicon etching when changed is described.

The experiment was performed using the first evaluation apparatus shown in FIG.
That is, using the first evaluation apparatus shown in FIG. 5A, a mixed gas of hydrogen gas, silane gas, and chlorine gas was introduced into the furnace as the pretreatment gas, and the wafer was pretreated.
In the pretreatment, the flow rate ratio between chlorine gas and hydrogen gas is set to two types, chlorine / hydrogen = 0.02, chlorine / hydrogen = 0.1, and the flow rate ratio between silane gas and chlorine gas is changed to silane / hydrogen gas. It was changed in two ways: chlorine = 0, silane / chlorine = 2.5.
The silicon etching amount was measured by installing monitor wafers in the upper area (167th sheet), the central area (89th sheet), and the lower area (11th sheet) of the boat.

FIG. 8 shows the difference in the monitor wafer position depending on the flow rate ratio between chlorine gas and hydrogen gas and the flow rate ratio between silane gas and chlorine gas.
In FIG. 8, the horizontal axis indicates the monitor wafer position, and the vertical axis indicates the silicon etching amount (Å).

According to FIG. 8, the following can be understood.
During pre-treatment, the amount of silicon etching in the inter-wafer plane direction is greater when the flow ratio of chlorine gas to hydrogen gas is chlorine / hydrogen = 0.02 than when chlorine / hydrogen = 0.1. Distribution is uniform.
That is, when the ratio of the chlorine gas to the hydrogen gas is reduced, the silicon etching amount distribution in the direction between the wafer surfaces can be made uniform.
In addition, when pre-processing, the flow rate ratio of silane gas and chlorine gas is set to silane / chlorine = 0, and the silicon etching amount distribution in the wafer surface direction is more than when silane / chlorine = 2.5. Becomes uniform, and the silicon etching amount can be increased as a whole.
That is, when the ratio of the silane gas to the chlorine gas is reduced, the silicon etching amount can be increased in the entire region while maintaining a good silicon etching amount distribution in the direction between the wafer surfaces.

From these facts, when the ratio of chlorine gas to hydrogen gas is decreased in order to make the silicon etching amount distribution in the direction between the wafer surfaces uniform, the silicon etching amount decreases in all regions, and the interface impurities There is a concern that the removal effect will be reduced.
In such a case, by reducing the ratio of silane gas to chlorine gas, the silicon etching amount can be increased in the entire region, so that the contamination removal effect can be enhanced in the entire region while maintaining a good silicon etching amount. it can.

  When the degree of silicon etching at the upper and lower portions in the processing chamber is larger than that in other portions, the supply flow rate or concentration of the pretreatment gas supplied to the upper and lower portions in the processing chamber is supplied to the other portions. Before adjusting the supply flow rate or concentration of the pretreatment gas to an appropriate supply flow rate or concentration, etc., or before supplying the gas species of the pretreatment gas supplied to the upper and lower parts of the processing chamber to other parts The degree of silicon etching in the direction between the wafer surfaces may be made uniform, for example, by making it different from the gas type of the processing gas.

For example, in the above-described CVD apparatus 10, the following settings may be made.
(1) Supply flow rate of chlorine gas supplied from the long nozzle N1 to the upper part of the processing chamber, supply flow rate of chlorine gas supplied from the long nozzle N2 to the upper center of the processing chamber, and supply of chlorine gas supplied from the long nozzle N3 to the lower center of the processing chamber The supply flow rate, the supply flow rate of chlorine gas supplied from the long nozzle N4 to the bottom of the processing chamber, and the supply flow rate of chlorine gas supplied from the short nozzle N5 to the bottom of the processing chamber are 50 sccm, 40 sccm, 30 sccm, 40 sccm, and 60 sccm, respectively.
(2) The concentration of chlorine gas supplied from the long nozzle N1 to the upper part of the processing chamber, the concentration of chlorine gas supplied from the long nozzle N2 to the upper center of the processing chamber, the concentration of chlorine gas supplied from the long nozzle N3 to the lower center of the processing chamber, The concentration of chlorine gas supplied from the long nozzle N4 to the bottom of the processing chamber and the concentration of chlorine gas supplied from the short nozzle N5 to the bottom of the processing chamber are 20%, 10%, 5%, 10%, and 30%, respectively.
(3) The pretreatment gas supplied from the long nozzle N1 to the upper part of the processing chamber is a mixed gas of hydrogen gas and chlorine gas, and the preprocessing gas supplied from the long nozzle N2 to the upper center of the processing chamber, the long nozzle N3 to the center of the processing chamber The pretreatment gas supplied to the lower portion, the pretreatment gas supplied to the bottom of the treatment chamber from the long nozzle N4 is a mixed gas of hydrogen gas, silane gas and chlorine gas, and the pretreatment gas supplied to the lower portion of the treatment chamber from the short nozzle N5 is hydrogen. A mixed gas of gas and chlorine gas is used.
As described above, the degree of silicon etching in the direction between the wafer surfaces can be made uniform by changing the supply flow rate, concentration, or type of the pretreatment gas for each nozzle in accordance with the degree of silicon etching. The film thickness distribution in the direction between the wafer surfaces after the pretreatment can be made uniform.

  Needless to say, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

For example, the long nozzle is not limited to the use of a nozzle in which the gas outlet is opened so that the gas is ejected upward at the nozzle tip as in the above-described embodiment, but a plurality of gas outlets as shown in FIG. May use a nozzle that is open so as to eject gas in the horizontal direction on the nozzle tube wall.
In this case, the gas ejection holes H1 to H4 provided in the long nozzles N1 to N4 are preferably provided at locations that do not overlap in the vertical direction as shown in FIG. In FIG. 9, five gas outlets are provided at regular intervals at the tip of each long nozzle, and the gas ejection holes H1 to H4 of the long nozzles N1 to N4 are also provided at regular intervals. The example which provided the gas jet nozzle at equal intervals is shown. By arranging the gas ejection holes H1 to H4 of the long nozzles N1 to N4 in this way, the pretreatment gas can be supplied uniformly throughout the furnace.
The size (diameter), the number of holes, and the pitch of the gas ejection holes H1 to H4 may be different depending on the location.

  In the above embodiment, the case where a polycrystalline silicon film or a single crystal silicon film is formed on a wafer has been described. However, the present invention is not limited to this, and an amorphous film, a doped single crystal film, or a polycrystalline film is not limited thereto. The present invention can also be applied when forming a film, an amorphous film, a nitride film, an oxide film, or a metal film.

Although the CVD apparatus has been described in the above embodiment, the present invention is not limited to this and can be applied to all substrate processing apparatuses.
In particular, the present invention can be applied to a case where a high quality interface needs to be formed between the substrate and the thin film, and an excellent effect can be obtained.

In the following, preferred embodiments are described.
(1) carrying a plurality of substrates into a reaction vessel composed of a process tube and a manifold supporting the process tube and arranging the substrates in the reaction vessel;
Performing a pretreatment on the plurality of substrates by flowing a pretreatment gas from the manifold side toward the process tube in the reaction vessel;
Applying the main processing to the plurality of substrates subjected to the preprocessing by flowing a main processing gas from the manifold side to the process tube side in the reaction vessel;
Unloading the plurality of substrates after the main treatment from the reaction vessel, and
In the step of performing the pretreatment, a method of manufacturing a semiconductor device, wherein the pretreatment gas is supplied from at least one place in a region corresponding to the manifold and at least one place in an upper portion in a region corresponding to the substrate arrangement region.
(2) carrying a plurality of substrates into the reaction vessel and arranging them in the reaction vessel;
Flowing a pretreatment gas into the reaction vessel to pretreat the plurality of substrates;
Subjecting the plurality of substrates that have been subjected to the pretreatment by flowing a main treatment gas into the reaction vessel;
Unloading the plurality of substrates after the main treatment from the reaction vessel, and
In the step of performing the pretreatment, a semiconductor device that supplies a pretreatment gas from at least one location in a region that is lower in temperature than the substrate arrangement region and at least one location on the downstream end in a region corresponding to the substrate arrangement region Manufacturing method.
(3) carrying a plurality of substrates into the reaction vessel and arranging them in the reaction vessel;
Flowing a pretreatment gas into the reaction vessel to pretreat the plurality of substrates;
Subjecting the plurality of substrates that have been subjected to the pretreatment by flowing a main treatment gas into the reaction vessel;
Unloading the plurality of substrates after the main treatment from the reaction vessel, and
In the step of performing the pretreatment, the semiconductor device manufacturing method supplies the pretreatment gas from at least one place in a region below the substrate arrangement region and at least one place in an upper portion in a region corresponding to the substrate arrangement region. .
(4) carrying the substrate into the reaction vessel;
Pre-treating the substrate in the reaction vessel;
Applying the main treatment to the pretreated substrate in the reaction vessel;
Unloading the substrate after the main treatment from the reaction vessel,
In the step of performing the pretreatment, the pretreatment gas is supplied from a plurality of locations in the processing chamber, and the supply flow rate, concentration, or type of the pretreatment gas is set in at least one of the plurality of locations and other locations. A manufacturing method of a semiconductor device to be different.
(5) carrying the substrate into the reaction vessel;
Pre-treating the substrate in the reaction vessel;
Applying the main treatment to the pretreated substrate in the reaction vessel;
Unloading the substrate after the main treatment from the reaction vessel,
In the step of performing the pretreatment, a plurality of types of pretreatment gases are supplied from a plurality of locations in the processing chamber, and at least one of the plurality of locations and the other types of the pretreatment gases of the plurality of types are treated. A method of manufacturing a semiconductor device in which a supply flow rate ratio or a concentration ratio is varied.
(6) a process tube for processing the substrate;
A manifold that supports the process tube;
A support for arranging and supporting a plurality of substrates in the process tube;
A first nozzle that supplies gas from at least one location in a region corresponding to the manifold;
A second nozzle for supplying gas from at least one upper portion in a region corresponding to the substrate arrangement region in the process tube;
An exhaust path provided on the opposite side of the process tube to the side on which the first nozzle is provided and exhausts the inside of the process tube;
A pretreatment gas is supplied from the first nozzle and the second nozzle, flows toward the exhaust path, pretreats the plurality of substrates, and supplies the main treatment gas from at least the first nozzle. And a controller that controls the flow to flow toward the exhaust path and perform the main process on the plurality of substrates that have been subjected to the pre-process,
A substrate processing apparatus.
(7) When supplying the pretreatment gas from the first nozzle and the second nozzle, the controller varies the supply flow rate, concentration, or type of the pretreatment gas between the first nozzle and the second nozzle. (6) The substrate processing apparatus controlled as described above.
(8) a process tube for processing a substrate;
A manifold that supports the process tube;
A support for arranging and supporting a plurality of substrates in the process tube;
A first nozzle that supplies gas from at least one location in a region corresponding to the manifold;
A second nozzle for supplying gas from a plurality of locations including at least the upper part in a region corresponding to the substrate arrangement region in the process tube;
An exhaust path provided on the opposite side of the process tube to the side on which the first nozzle is provided and exhausts the inside of the process tube;
A pretreatment gas is supplied from the first nozzle and the second nozzle, flows toward the exhaust path, pretreats the plurality of substrates, and supplies the main treatment gas from at least the first nozzle. And a controller that controls the flow to flow toward the exhaust path and perform the main process on the plurality of substrates that have been subjected to the pre-process,
A substrate processing apparatus.
(9) When the controller supplies the pretreatment gas from the first nozzle and the second nozzle, at least one of the gas supply locations of the first nozzle and the second nozzle and other locations, The substrate processing apparatus according to (8), wherein the supply flow rate, concentration, or type of the pretreatment gas is controlled to be different.

1 is a schematic side sectional view showing a CVD apparatus according to a first embodiment of the present invention. It is side surface sectional drawing which shows the principal part. It is a sequence flowchart which shows the silicon film formation process of the manufacturing method of the semiconductor device which concerns on 1st embodiment of this invention. It is a sequence flowchart which shows the silicon film formation process of the manufacturing method of the semiconductor device which concerns on 2nd embodiment of this invention. It is a schematic diagram for evaluating a decontamination effect, (a) shows the case by a 1st evaluation apparatus, (b) has shown the case by a 2nd evaluation apparatus. It is a graph which shows the difference by the number of supply gas systems of a decontamination effect. It is a graph which shows the difference in the interface oxygen density at the time of changing the flow rate ratio of chlorine gas and hydrogen gas. It is a graph which shows the difference in the amount of silicon etching by the flow rate ratio of chlorine gas and hydrogen gas, and the flow rate ratio of silane gas and chlorine gas. It is typical side surface sectional drawing which shows the CVD apparatus which is 2nd embodiment of this invention. It is a piping diagram which shows the example of a 1st supply system. It is a piping figure showing the example of the 2nd supply system.

Explanation of symbols

1 ... wafer (substrate),
DESCRIPTION OF SYMBOLS 10 ... CVD apparatus (CVD apparatus with a spare chamber, substrate processing apparatus), 11 ... Case, 12 ... Spare chamber, 13 ... Wafer loading / unloading port, 14 ... Gate valve, 15 ... Boat loading / unloading port, 16 ... Shutter,
17 ... exhaust line, 18 ... valve, 19 ... mechanical booster pump, 20 ... dry pump,
21 ... Nitrogen gas supply line, 22 ... Mass flow controller, 23 ... Nitrogen gas supply source,
DESCRIPTION OF SYMBOLS 24 ... Boat elevator, 25 ... Guide rail, 26 ... Feed screw shaft, 27 ... Motor, 28 ... Lifting body, 29 ... Arm, 30 ... Seal cap, 31 ... O-ring, 32 ... Rotation mechanism, 33 ... Rotation shaft, 34 ... boats, 35 ... insulation plates,
36 ... Drive control unit, 37 ... Electric wiring,
40 ... reactor, 41 ... heater base, 42 ... heater,
43 ... Process tube, 44 ... Outer tube, 45 ... Inner tube, 46 ... Processing chamber, 47 ... Cylindrical space, 48 ... O-ring, 49 ... Manifold,
50 ... Temperature sensor, 51 ... Temperature controller, 52 ... Electrical wiring,
53 ... Exhaust pipe, 54 ... Pressure sensor, 55 ... Pressure adjusting device, 56 ... Pressure control unit, 57 ... Electric wiring, 58 ... Gas flow rate control unit, 59 ... Electric wiring,
60 ... main control unit, 61 ... controller,
N1 ... 1st long nozzle, N2 ... 2nd long nozzle, N3 ... 3rd long nozzle, N4 ... 4th long nozzle, N5 ... Short nozzle,
L1-L5 ... gas supply line, M1-M5 ... gas flow rate controller, G1-G5 ... gas supply source, H1-H4 ... gas ejection holes.

Claims (6)

Bringing a plurality of substrates into the reaction vessel and arranging them in the reaction vessel;
Performing a pretreatment by supplying a pretreatment gas into the reaction vessel to remove natural oxide films or contaminants on the plurality of substrates;
Performing a main process of supplying a main processing gas into the reaction vessel to form a thin film on the plurality of substrates subjected to the pretreatment;
Unloading the plurality of substrates after the main processing from the reaction vessel, and in the step of performing the preprocessing, a hydrogen-containing gas, a silicon-containing gas, and a chlorine-containing gas are used as the pretreatment gas. At least one of these or a mixed gas thereof is supplied from a plurality of locations including the substrate arrangement region in the reaction vessel, and at this time, the pretreatment gas is a region at a relatively low temperature upstream from the substrate arrangement region. And at least one of the locations to which the pretreatment gas is supplied and other locations so as to be actively supplied from locations corresponding to the downstream end portions of the substrate arrangement region, respectively. A method of manufacturing a semiconductor device, wherein at least one of gas supply flow rate, concentration, and type is different. Bringing a plurality of substrates into the reaction vessel and arranging them in the reaction vessel;
Performing a pretreatment by supplying a pretreatment gas into the reaction vessel to remove natural oxide films or contaminants on the plurality of substrates;
Performing a main process of supplying a main processing gas into the reaction vessel to form a thin film on the plurality of substrates subjected to the pretreatment;
Unloading the plurality of substrates after the main treatment from the reaction vessel, and in the step of performing the pretreatment, mixing a hydrogen-containing gas, a silicon-containing gas, and a chlorine-containing gas as a pretreatment gas Gas is supplied from a plurality of locations including the substrate arrangement region in the reaction vessel, and at that time, the pretreatment gas is supplied at a relatively low temperature upstream from the substrate arrangement region and a downstream end of the substrate arrangement region. The supply flow rate ratio and the concentration ratio of the mixed gas are at least one of the locations where the pretreatment gas is supplied and the other locations so as to be actively supplied from locations corresponding to the regions to be the parts . A method of manufacturing a semiconductor device in which at least one of them is different. Bringing a plurality of substrates into the reaction vessel and arranging them in the reaction vessel ;
Performing a pretreatment by supplying a pretreatment gas into the reaction vessel to remove natural oxide films or contaminants on the plurality of substrates;
Performing a main process of supplying a main processing gas into the reaction vessel to form a thin film on the plurality of substrates subjected to the pretreatment;
Anda step of unloading the plurality of substrates after the present process from the reaction vessel, in the step of performing the pretreatment, the hydrogen-containing gas as the pretreatment gas, the silicon-containing gas and the chlorine-containing gas out at least one or a mixture of these gases, is supplied from a plurality of locations including a substrate arrangement region of the reaction vessel, in which the pretreatment gas, a relatively low temperature on the upstream side of the substrate arrangement region area And at least one of the locations to which the pretreatment gas is supplied and other locations so as to be actively supplied from locations corresponding to the downstream end portions of the substrate arrangement region, respectively. A substrate processing method in which at least one of gas supply flow rate, concentration and type is different. Bringing a plurality of substrates into the reaction vessel and arranging them in the reaction vessel ;
Performing a pretreatment by supplying a pretreatment gas into the reaction vessel to remove natural oxide films or contaminants on the plurality of substrates;
Performing a main process of supplying a main processing gas into the reaction vessel to form a thin film on the plurality of substrates subjected to the pretreatment;
Unloading the plurality of substrates after the main treatment from the reaction vessel, and in the step of performing the pretreatment, mixing a hydrogen-containing gas, a silicon-containing gas, and a chlorine-containing gas as a pretreatment gas the gas is supplied from a plurality of locations including a substrate arrangement region of the reaction vessel, in which the pretreatment gas, the downstream end of the relatively low temperature and a region and the substrate sequence region upstream of the substrate arrangement region The supply flow rate ratio and the concentration ratio of the mixed gas are at least one of the locations where the pretreatment gas is supplied and the other locations so as to be actively supplied from locations corresponding to the regions to be the parts . A substrate processing method in which at least one of them is different. A reaction vessel containing a substrate;
A support for arranging and supporting a plurality of substrates in the reaction vessel;
A gas supply system for supplying gas from a plurality of locations including a substrate arrangement region in the reaction vessel;
A pretreatment gas for supplying a pretreatment gas into the reaction vessel containing and arranging a plurality of substrates to remove a natural oxide film or contaminants on the plurality of substrates; and a main treatment gas in the reaction vessel. And a main process for forming a thin film on the plurality of substrates that have been subjected to the pretreatment, and in the pretreatment, the pretreatment gas includes a hydrogen-containing gas, a silicon-containing gas, and a chlorine-containing gas. At least one of these or a mixed gas thereof is supplied from a plurality of locations including the substrate arrangement region in the reaction vessel, and at this time, the pretreatment gas becomes a relatively low temperature upstream of the substrate arrangement region. At least one of the locations to which the pretreatment gas is supplied and other locations so as to be actively supplied from the locations corresponding to the regions and the downstream end portions of the substrate arrangement region, respectively. processing Scan supply flow rate, and a controller for controlling so as to vary the at least either of the concentration and type,
A substrate processing apparatus . A reaction vessel containing a substrate;
A support for arranging and supporting a plurality of substrates in the reaction vessel;
A gas supply system for supplying gas from a plurality of locations including a substrate arrangement region in the reaction vessel;
A pretreatment gas for supplying a pretreatment gas into the reaction vessel containing and arranging a plurality of substrates to remove a natural oxide film or contaminants on the plurality of substrates; and a main treatment gas in the reaction vessel. And performing a main process of forming a thin film on the plurality of substrates that have been subjected to the pretreatment, and in the pretreatment, the pretreatment gas includes a hydrogen-containing gas, a silicon-containing gas, and a chlorine-containing material. A gas mixture gas is supplied from a plurality of locations including the substrate arrangement region in the reaction vessel, and the pretreatment gas is supplied at a relatively low temperature upstream from the substrate arrangement region and the substrate arrangement region. The mixed gas supply flow rate ratio and at least one of the locations to which the pretreatment gas is supplied and the other locations so as to be actively supplied from locations corresponding to the downstream end portions, respectively, Concentration ratio A controller for controlling so as to vary at least one,
A substrate processing apparatus .

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