JP2007088225A - Manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device manufacturing method including a film depositing process capable of carrying out a pretreatment at a low temperature, dispensing with H2 annealing that must be usually carried out at high temperatures for removing a natural oxide film before a selective epitaxial growth process is performed. <P>SOLUTION: A wafer is subjected to a pretreatment in an atmosphere of total pressure 100 Pa including a partial pressure 0.25 Pa of dichlorosilane and a partial pressure 0.03 Pa of Cl<SB>2</SB>while being kept at a temperature of 700°C so as to remove a natural oxide film before an epitaxial growth process is carried out. Then, the partial pressure ratio is changed between the gasses used in the pretreatment, specifically, a partial pressure 0.5 Pa of dichlorosilane and a partial pressure 0 to 0.05 Pa of Cl<SB>2</SB>are set up, and the wafer is subjected to a reduced-pressure CVD method in an atmosphere of 100 Pa including the above gases having each a specified partial pressure, whereby an Si film is deposited thereon. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device including a selective epitaxial growth step.

A natural oxide film removal process is performed before the selective epitaxial growth. Conventionally, it was necessary to perform H ₂ annealing at a high temperature of about 800 ° C. in order to remove the natural oxide film.

  In this case, the overheating causes deformation of the diffusion layer profile in the semiconductor wafer and changes in the film quality in the entire processing process, leading to performance degradation of the semiconductor device.

  Therefore, a main object of the present invention is to provide a method for manufacturing a semiconductor device including a film forming process capable of pretreatment at a low temperature.

According to the present invention,
A step of pre-treating the substrate;
Performing selective epitaxial film formation on the substrate,
A plurality of gases used in the pretreatment are used even during the selective epitaxial film formation, and at least a partial pressure ratio of the plurality of gases is made different between the pretreatment and the epitaxial film formation. A manufacturing method is provided.

  The plurality of gases are preferably Si source gas and halogen-based etching gas, and particularly preferably Si source gas and Cl-based etching gas.

  Silicon and silicon oxide are preferably formed on the surface of the substrate on which film formation is performed, or silicon is formed.

  Preferably, a natural oxide film present on the silicon surface is removed by pretreatment, and a silicon film is formed in the film formation.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a semiconductor device provided with the film-forming process which can be pre-processed at low temperature is provided.

  In a preferred embodiment of the present invention, a Si source gas and a halogen-based etching gas (preferably a Cl-based etching gas) are simultaneously supplied, a pretreatment for removing a natural oxide film is performed at a low temperature, and then a film forming process is continuously performed. To do. The Si source gas and the Cl-based etching gas are the same as the source gas for selective epitaxial film formation. At this time, [natural oxide film removal processing temperature] ≦ [selective epitaxial film formation processing temperature].

  A substrate on which silicon and silicon oxide (or siliconized chamber) are formed or a substrate on which silicon is formed is introduced into the treatment chamber and then heated to a predetermined temperature.

  After the substrate temperature is stabilized at the predetermined temperature, (1) the partial pressure ratio of the selective growth conditions in which the Si source gas and the Cl-based etching gas are not grown on the oxide film, and (2) on the Si substrate according to the partial pressure ratio. The processing is performed for a predetermined time at the total pressure under the condition that the growth rate is nearly zero.

  Here, the predetermined temperature is preferably a selective epitaxial film formation processing temperature in which the film is not grown on the silicon oxide film but is epitaxially formed on the silicon.

  The partial pressure ratio of the selective growth conditions that do not grow on the oxide film is preferably Si source gas: Cl-based etching gas = 20: 1 to 1: 2.

Further, the total pressure under the condition that the growth rate on the Si substrate is almost 0 according to the partial pressure ratio is preferably 1E-3 (1 × 10 ⁻³ ) Pa to 1E3 (1 × 10 ³ ) Pa. is there.

Monosilane, dichlorosilane, or disilane is preferably used as the Si source gas, and HCl or Cl ₂ is preferably used as the Cl-based etching gas.

  While repeating the competitive reaction between Si film formation and Si etching on the surface of the substrate, while the Si surface without a natural oxide film is epitaxially formed at a very slow rate, the silicon around the natural oxide film is etched and the natural oxide film On the surface of this, the desorption reaction of SiO occurs.

  Because of the selective growth conditions, Si nuclei deposited on SiO are quickly removed by a Cl-based etching gas. Therefore, Si is not deposited on the natural oxide film until the natural oxide film on the substrate surface is completely removed.

  After the natural oxide film is completely removed, the substrate is heated to the temperature for selective epitaxial film formation, and the selective oxide film formation is performed by changing at least the partial pressure or only the total pressure and the partial pressure ratio of the natural oxide film removal process conditions. Process. By the epitaxial film formation, the irregularities generated during the natural oxide film removal process are leveled and flattened.

  The removal temperature of the natural oxide film and the selective epitaxial growth temperature are preferably 700 ° C. or less, and the removal temperature of the natural oxide film and the selective epitaxial growth temperature are the same, or the removal temperature of the natural oxide film is higher than the selective epitaxial growth temperature. Low.

  Thus, the removal temperature of the natural oxide film is the same as or lower than the selective epitaxial growth temperature, so that the thermal budget is reduced, thereby contributing to higher performance of the semiconductor device.

  In addition, since the raw material gas that has been used for selective growth is used, there is no cost burden such as adding a line.

  Since the natural oxide film can be removed at the same temperature as the selective epitaxial film formation temperature, the throughput can be improved.

Table 1 shows specific examples in the case where dichlorosilane is used as the Si source gas and Cl ₂ is used as the Cl-based etching gas.

FIG. 1 is a schematic longitudinal sectional view of a MOSFET 10 in which an elevated source / drain to which the present invention is preferably applied is formed.
A gate electrode 20 is formed on the element formation silicon region 11 surrounded by the element isolation region 12 via a gate insulating film 17. Sidewalls 18 are formed on the side surfaces of the gate electrode 20, and a gate protection film 19 is formed on the upper surface of the gate electrode 20. A source 13 and a drain 14 are formed in the element formation silicon region 11 in a self-aligned manner with respect to the gate electrode 20. Elevated source 15 and elevated drain 16 are selectively formed only on source 13 and drain 14, respectively. The elevated source 15 and the elevated drain 16 are not grown in the region such as the element isolation region 12 where Si is epitaxially grown only on the source 13 and drain 14 where Si is exposed, and other SiO ₂ is exposed. It is formed by selective growth that does not grow.
The present invention is suitably used, for example, when forming such an elevated source / drain.

  Next, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 is a schematic perspective view for explaining a vertical selective epitaxial growth apparatus in a preferred embodiment of the present invention, and FIG. 3 is a schematic structure for explaining a vertical selective epitaxial growth apparatus in a preferred embodiment of the present invention. FIG. 4 is a longitudinal sectional view, and FIG. 4 is a schematic structural longitudinal sectional view for explaining a processing furnace of a vertical selective epitaxial growth apparatus in a preferred embodiment of the present invention.

  As shown in FIG. 2, a cassette stage 105 is provided on the front side inside the housing 101 as a holder transfer member that transfers a cassette 100 as a substrate storage container with an external transfer device (not shown). A cassette elevator 115 as an elevating means is provided on the rear side of the cassette stage 105, and a cassette transfer machine 114 as a conveying means is attached to the cassette elevator 115. On the rear side of the cassette elevator 115, a cassette shelf 109 as a means for placing the cassette 100 is provided, and the cassette shelf 109 is provided on the slide stage 122 so as to be able to traverse. Further, a buffer cassette shelf 110 as a means for placing the cassette 100 is provided above the cassette shelf. Further, a clean unit 118 is provided on the rear side of the buffer cassette shelf 110 so as to distribute clean air through the inside of the housing 101.

  A processing furnace 202 is provided above the rear portion of the housing 101. In the processing furnace 202, a processing chamber 201 for performing predetermined processing on the wafer 200 is formed. A load lock chamber 102 as an airtight chamber is connected to a lower side of the processing furnace 202 by a gate valve 244 as a gate valve, and a load as partition means is provided at a position facing the cassette shelf 109 on the front surface of the load lock chamber 102. A lock door 123 is provided. Inside the load lock chamber 102, a boat elevator as a lifting means for lifting and lowering a boat 217 as a substrate holding means for holding wafers 200 as substrates in a multi-stage in a horizontal posture between the processing chamber 201 and the load lock chamber 102. 121 is installed, and a seal cap 219 as a lid is attached to the boat elevator 121 to support the boat 217 vertically. Between the load lock chamber 102 and the cassette shelf 109, a transfer elevator (not shown) as an elevating means is provided, and a wafer transfer machine 112 as a transfer means is attached to the transfer elevator.

  The transport operation of the cassette transfer machine 114 and the like is controlled by the transport control means 124.

  Next, the configuration around the processing furnace of the vertical selective epitaxial growth apparatus which is the substrate processing apparatus of this embodiment will be described with reference to FIG.

  A lower substrate 145 is provided on the outer surface of the load lock chamber 102 as an airtight chamber, an upper substrate 147 is provided at the upper end of a guide shaft 146 erected on the lower substrate 145, and spans between the lower substrate 145 and the upper substrate 147. A ball screw 144 is rotatably provided. The ball screw 144 is rotated by a lift motor 148 provided on the upper substrate 147. An elevating table 149 is fitted to the guide shaft 146 so as to be movable up and down, and the elevating table 149 is screwed into a ball screw 144.

  A hollow elevating shaft 150 is vertically suspended from the elevating platform 149, and the support portions of the elevating platform 149 and the elevating shaft 150 are airtight. The elevating shaft 150 penetrates the top plate 151 of the load lock chamber 102 and reaches near the bottom surface of the load lock chamber 102. The penetrating portion of the top plate 151 has a sufficient margin so that it does not come into contact with the lifting movement of the lifting shaft 150, and the stretchability that covers the protruding portion of the lifting shaft 150 is between the load lock chamber 102 and the lifting platform 149. The bellows 119 has a sufficient amount of expansion and contraction to accommodate the lifting amount of the lifting platform 149, and the inner diameter of the bellows 119 is sufficiently larger than the outer shape of the lifting shaft 150. 119 is not expanded and contracted.

  A lifting substrate 152 is fixed horizontally to the lower end of the lifting shaft 150. A drive unit cover 153 is attached to the lower surface of the elevating board 152 to form a drive unit storage case 154. The joint between the elevating board 152 and the drive unit cover 153 is sealed with a sealing member such as an O-ring. Therefore, the inside of the drive unit storage case 154 is isolated from the atmosphere in the load lock chamber 102.

  A rotating mechanism 156 of the boat 217 is provided on the lower surface of the elevating board 152, and the periphery of the rotating mechanism 152 is cooled by the cooling means 157.

  A power supply cable 158 is led from the upper end of the lifting shaft 150 through the hollow portion of the lifting shaft 150 to the rotating mechanism 156 and connected thereto. Further, a cooling water path 159 is formed in the cooling means 157 and the seal cap 219, and a cooling water pipe 160 for supplying cooling water is connected to the cooling water path 159, and the cooling water pipe 160 is connected to the upper end of the lifting shaft 150. Through the hollow portion of the lifting shaft 150.

  A seal cap 219 is airtightly provided on the upper surface of the elevating substrate 152. The elevating motor 148 is driven and the ball screw 144 is rotated to raise the drive unit storage case 154 via the elevating platform 149 and the elevating shaft 150.

  In the vicinity of the top dead center of the lifting platform 149, the seal cap 219 closes the furnace port 161, which is the opening of the processing furnace 202, so that wafer processing is possible. When the wafer processing is completed, the lift motor 148 is driven, the boat 217 is lowered, and the wafer can be unloaded.

  Next, details of the processing furnace of the vertical selective epitaxial growth apparatus which is the substrate processing apparatus of this embodiment will be described with reference to FIG.

As shown in FIG. 4, the processing furnace 202 covers a reaction tube composed of an outer tube 205, a gas exhaust pipe 231, a gas supply pipe 232, a manifold 209, and a lower end portion (furnace port 161) of the manifold 209. A seal cap 219 that seals the processing chamber 201; a boat 217 that is provided on the seal cap 219 and has wafers 200 mounted in multiple stages in the vertical direction; a rotating mechanism 156 that rotates the boat 217; and a heater (not shown) A heater 207 or the like having a strand and a heat insulating member for heating the wafer 200 is provided.
The processing chamber 201 is constituted by the outer tube 205, the manifold 209, the seal cap 219, and the like.

  In the configuration of the processing furnace 202, processing gas is supplied from a first gas supply source 180, a second gas supply source 181 and a third gas supply source 182, and is an MFC (mass flow controller) as a gas flow rate control means. After the flow rates are controlled by H.183, MFC184 and MFC185, they are introduced from the upper part of the processing chamber 201 through a single gas supply pipe 232 through valves 177, 178 and 179, respectively. The gas supply pipe 232 extends through the manifold 209 and extends in the outer tube 205 to the upper part of the processing chamber 201. A valve 176 is provided in the gas supply pipe 232.

  A gas exhaust pipe 231 communicates with the manifold 209. The gas exhaust pipe 231 is provided with an exhaust valve 175 and a vacuum pump 246 as an exhaust system in this order toward the downstream side. The atmosphere in the processing chamber 201 is exhausted from the processing chamber 201 by a vacuum pump 246 connected to a gas exhaust pipe 231.

  The heater 207, the rotation mechanism 156, the MFCs 183, 184, 185, the valves 175, 176, 177, 178, 179, the lifting motor 148, the load lock door 123, the gate valve 244, the vacuum pump 246, and the like are controlled by the controller 162. , Raising and lowering between the processing chamber 201 and the row lock chamber 102 of the boat 217 loaded with the wafer 200, opening and closing of the gate valve 244 and the load lock door 123, temperature control in the processing furnace 202, processing gas into the processing chamber 201 The control device 162 controls the supply of nitrogen gas as an inert gas to the load lock chamber 102, the exhaust of the load lock chamber 102, and the like.

Next, as an example of the processing of the semiconductor wafer 200 in the vertical selective epitaxial growth apparatus which is the substrate processing apparatus of this embodiment, an epitaxial Si film is selectively formed using SiH ₂ Cl ₂ , Cl ₂ and H ₂ on the semiconductor silicon wafer. The case of forming a film will be described.

  A cassette 100 transported from an external transport device (not shown) is placed on a cassette stage 105, and the orientation of the cassette 100 is converted by 90 ° on the cassette stage 105. Further, the cassette elevator 115 is moved up and down, traversed and moved. The cassette 114 is transported to the cassette shelf 109 or the buffer cassette shelf 110 in cooperation with the advance / retreat operation of the loading machine 114.

  Wafers 200 are transferred from the cassette shelf 109 to the boat 217 by the wafer transfer device 112. In preparation for transferring the wafer 200 to the boat 217, the boat 217 is lowered by the boat elevator 121, the processing chamber 201 is closed by the gate valve 244, and a purge gas of nitrogen gas is introduced from the purge nozzle 234 into the load lock chamber 102. Is done. After the load lock chamber 102 is restored to atmospheric pressure, the load lock door 123 is opened.

  The horizontal slide mechanism 122 moves the cassette shelf 109 horizontally and positions the cassette 100 to be transferred so as to face the wafer transfer device 112. The wafer transfer device 112 transfers the wafers 200 from the cassette 100 to the boat 217 by cooperation of the raising / lowering operation and the rotating operation. The wafer 200 is transferred to several cassettes 100, and after the transfer of a predetermined number of wafers to the boat 217 is completed, the load lock door 123 is closed and the load lock chamber 102 is connected via the exhaust pipe 236. It is evacuated.

  After the evacuation is completed, nitrogen gas is introduced from the gas purge nozzle 234, and when the inside of the load lock chamber 102 is restored to atmospheric pressure by the nitrogen gas, the gate valve 244 is opened, and the boat elevator 121 is driven by driving the lift motor 148. The boat 217 is inserted into the processing chamber 201, and the processing chamber 201 is closed by closing the furnace port 161 that is the opening of the processing furnace 202 with the seal cap 219. When the boat 217 is inserted into the processing chamber 201, the temperature in the processing chamber 201 is kept at 200 ° C. The load lock chamber 102 is maintained at substantially atmospheric pressure with nitrogen gas until the processing of the wafers 200 is completed and the boat 217 descends again to the load lock chamber 102.

  Next, the exhaust valve 175 is opened, the atmosphere in the processing chamber 201 is exhausted, and the pressure in the processing chamber 201 is reduced. Then, the control device 162 controls the heater 207 to maintain the temperature in the processing chamber 201 and thus the temperature of the wafer 200 at 700 ° C. Thereafter, the rotation mechanism 156 is driven to rotate the boat 217 at a predetermined rotation speed.

SiH ₂ Cl ₂ , Cl _2, and H ₂ are sealed in the first gas supply source 180, the second gas supply source 181, and the third gas supply source 182, respectively, and the flow rates thereof are MFC 183 and MFC 184. And MFC 185, respectively. By opening valves 177, 178, 178 that open and close the gas supply pipe, opening the valve 176, and supplying the processing gas to the processing chamber 201 through the gas supply pipe 232, while exhausting through the gas exhaust pipe 236, 0.25Pa the partial pressure of dichlorosilane in the process chamber 201, while maintaining the partial pressure of Cl ₂ 0.03 Pa, a total pressure 100 Pa, the temperature of the wafer 200 to 700 ° C., by a low pressure CVD method, a natural oxide from the wafer 200 Remove the membrane.
Next, the partial pressure of dichlorosilane in the processing chamber 201 is 0.5 Pa, the partial pressure of Cl ₂ is 0 to 0.005 Pa, the total pressure is 100 Pa, and the temperature of the wafer 200 is maintained at 700 ° C. An epitaxial Si film is formed on the wafer 200.

After a predetermined film forming process is performed on the wafer 200 in the processing chamber 201, the inside of the processing chamber 201 is replaced with nitrogen gas as a purge gas. That is, after deposition, (1) a process chamber 201 under reduced pressure through a gas exhaust pipe 231, then nitrogen gas _{(N 2)} the purge flow in the process chamber 201 into the process chamber 201 from the gas supply pipe 232 Then, (2) the nitrogen gas is stopped and the inside of the processing chamber 201 is again depressurized through the gas exhaust pipe 231, and then the nitrogen gas is caused to flow into the processing chamber 201 through the gas supply pipe 232 to flow inside the processing chamber 201. Purge. The operations (1) and (2) are repeated four times. Thereafter, nitrogen gas is introduced into the processing chamber 201 from the gas supply pipe 232, and the inside of the processing chamber 201 is returned to almost atmospheric pressure with nitrogen gas. Note that the load lock chamber 102 is maintained at substantially atmospheric pressure by nitrogen gas as described above.

  In this state, by driving the lifting motor 148, the boat 217 on which the wafer 200 is mounted is lowered from the processing chamber 201 into the load lock chamber 102 by the boat elevator 121, and the gate valve 244 is closed.

  Thereafter, the inside of the load lock chamber 102 is evacuated to 10 Torr or less through the exhaust pipe 236, and then nitrogen gas is introduced into the processing chamber 201 from the purge nozzle 234, and the inside of the load lock chamber 102 is returned to atmospheric pressure with nitrogen gas. .

  Thereafter, the load lock door 123 is opened, and the processed wafer 200 is transferred from the boat 217 through the cassette shelf 109 to the cassette stage 105 by the reverse procedure of the above-described operation, and is carried out by an external transfer device (not shown).

1 is a schematic longitudinal sectional view of a semiconductor device to which the present invention is preferably applied. 1 is a schematic perspective view for explaining a vertical selective epitaxial growth apparatus in a preferred embodiment of the present invention. It is a schematic structure longitudinal cross-sectional view for demonstrating the vertical type selective epitaxial growth apparatus in preferable Example of this invention. It is a schematic structure longitudinal cross-sectional view for demonstrating the processing furnace of the vertical type selective epitaxial growth apparatus in preferable Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Cassette 101 ... Case 102 ... Load lock chamber 105 ... Cassette stage 109 ... Cassette shelf 110 ... Buffer cassette shelf 112 ... Wafer transfer machine 114 ... Cassette transfer machine 115 ... Cassette ereverta 116 ... Gate valve 118 ... Clean unit DESCRIPTION OF SYMBOLS 119 ... Bellows 121 ... Boat elevator 122 ... Slide stage 123 ... Load lock door 124 ... Conveyance control means 148 ... Lifting motor 149 ... Lifting stand 156 ... Rotating mechanism 161 ... Furnace 162 ... Control device 175 ... Exhaust valve 176, 177, 178 179 ... Valves 183, 184, 185 ... MFC
180 ... first gas supply source 181 ... second gas supply source 182 ... third gas supply source 196 ... exhaust valve 200 ... wafer 201 ... processing chamber 202 ... processing furnace 205 ... outer tube 207 ... heater 209 ... manifold 217 ... Boat 219 ... Seal cap 231 ... Gas exhaust pipe 232 ... Gas supply pipe 234 ... Purge nozzle 244 ... Gate valve 246 ... Exhaust system

Claims (1)

A step of pre-treating the substrate;
Performing selective epitaxial film formation on the substrate,
A plurality of gases used in the pretreatment are used even during the selective epitaxial film formation, and at least a partial pressure ratio of the plurality of gases is made different between the pretreatment and the epitaxial film formation. Production method.

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