JP2008034462A - Substrate processing equipment - Google Patents

Abstract

An object of the present invention is to provide a substrate processing apparatus for suppressing an etching gas component from being mixed into a processing chamber from a gas supply section after substrate processing when a semiconductor epitaxial film is selectively grown.
A substrate processing apparatus for selectively growing an epitaxial film of a semiconductor containing silicon, a processing chamber 9 for containing the substrate, a substrate holder 8 for holding the substrate, and a source gas containing silicon. A gas supply means 19 for supplying an etching gas containing chlorine and hydrogen gas, an exhaust means 28 for exhausting the atmosphere in the processing chamber, and a controller 18 for controlling the gas supply means and the exhaust means. Supplying and exhausting the source gas and the etching gas into the processing chamber, forming an epitaxial film containing silicon on the substrate surface where the silicon is exposed, and supplying the etching gas after the film formation The gas supply unit is purged by flowing the hydrogen gas through the units 12 and 26.
[Selection] Figure 2

Description

  The present invention relates to a substrate processing apparatus for performing a film forming process or an etching process on a silicon wafer, and more particularly to a substrate processing apparatus for selectively growing a semiconductor epitaxial film containing silicon on a portion of the substrate surface where silicon is exposed. is there.

  As one of the substrate processing apparatuses, there is a batch type substrate processing apparatus that processes a predetermined number of substrates at a time.

  An example of a batch type substrate processing apparatus is a vertical reduced pressure CVD apparatus, and FIG. 8 shows a processing furnace 1 of the vertical reduced pressure CVD apparatus.

  The processing furnace 1 mainly includes a reaction tube 2, a heating device 3 disposed concentrically with the reaction tube 2, an inlet flange 4 that supports the reaction tube 2, and a lower end opening of the inlet flange 4. It is comprised by the seal cap 5 etc. which obstruct | occlude (furnace opening part). Further, the reaction tube 2 has a concentric double tube structure of an outer tube 6 and an inner tube 7, and a processing chamber 9 is formed by the reaction tube 2 and the inlet flange 4.

  A boat 8 is placed on the seal cap 5, and wafers 10 are held on the boat 8 in multiple stages in a horizontal posture. Note that a heat insulating plate 11 for suppressing heat radiation from the furnace port portion is loaded in the lower portion of the boat 8.

  A gas which is a raw material for the CVD reaction is introduced from a gas introduction nozzle 12 provided in the inlet flange 4, and the raw material gas rises from the lower part of the processing chamber 9 to the inside of the inner tube 7 to the upper part. Is turned down at the upper part of the pipe, flows down between the outer tube 6 and the inner tube 7, and is exhausted from the exhaust pipe 13.

  Here, an O-ring 14 for vacuum sealing is used between the inlet flange 4 and the outer tube 6 and between the inlet flange 4 and the seal cap 5. Therefore, the O-ring component may be degassed or leak from the seal portion during decompression, and the reaction atmosphere may be contaminated. Depending on the apparatus, a boat rotation mechanism may be attached. The rotation mechanism generates particles, or the contaminants evaporate from the seal portion of the rotation support portion. As shown, these contamination sources are concentrated in the lower part of the reactor.

  Since the contamination source is located upstream of the gas flow in the reaction atmosphere, the source gas introduced from the lower part contains the contaminant, and the contaminant is carried to the source gas and adheres to the wafer 10. Furthermore, the attached contaminants contribute to film formation defects in the CVD reaction.

  In particular, in a process requiring a high clean atmosphere such as epitaxial growth of Si and SiGe (C), haze is generated due to contaminants adhering to the wafer 10, and a good epitaxial film cannot be obtained. there were.

  In the process of selectively growing a semiconductor epitaxial film containing silicon on the exposed portion of silicon on the substrate surface, a source gas such as SiH4, Si2 H2 Cl2 or GeH4, a doping gas such as PH3 or B2 H6, Alternatively, an etching gas such as HCl or Cl2 is introduced into the processing chamber 9 together with a carrier gas such as H2 or Ar or He, and the film formation on the exposed silicon part and the etching of the part other than silicon are performed in parallel. Alternatively, the epitaxial film is selectively formed by alternately proceeding.

  After the film forming process, an inert gas is introduced into the processing chamber 9 and purged with gas to return to atmospheric pressure.

  However, when the etching gas is supplied, even if the etching gas is stopped, the Cl component adsorbed on the raw material gas supply section such as the gas introduction nozzle 12 does not readily desorb and remains in the nozzle. The remaining Cl component oozes out gradually, and there is a problem that the Cl component is adsorbed on the surface of the wafer 10 after the completion of the process. The Cl component adsorbed on the surface has a problem that it is erroneously counted as a particle when measuring particles after the end of the process, or the Cl component is brought into the next process to contaminate the atmosphere.

  In the present invention, in view of such circumstances, when a semiconductor epitaxial film containing silicon is selectively grown on a portion of the substrate surface where silicon is exposed, an etching gas component is supplied from the gas supply unit to the processing chamber after the substrate processing. It is a thing which suppresses mixing in.

  The present invention relates to a substrate processing apparatus for selectively growing a semiconductor epitaxial film containing silicon on a substrate surface where silicon is exposed, the processing chamber storing the substrate, and holding the substrate in the processing chamber. A substrate holder for heating, a heating means for heating the atmosphere in the substrate and the processing chamber, a gas supply means for supplying a source gas containing silicon, an etching gas containing chlorine, and a hydrogen gas into the processing chamber, and the processing An exhaust unit that exhausts the atmosphere in the room; and a control unit that controls at least the operation of the heating unit, the gas supply unit, and the exhaust unit, and the control unit controls the heating unit to heat the substrate. And controlling the gas supply means and the exhaust means to supply and exhaust the source gas and the etching gas into the processing chamber to expose the silicon. A substrate processing apparatus that forms an epitaxial film containing silicon on a substrate surface, and after the film formation, purges the gas supply unit by flowing the hydrogen gas through a gas supply unit that supplies at least the etching gas of the gas supply unit. It is concerned.

  According to the present invention, there is provided a substrate processing apparatus for selectively growing a semiconductor epitaxial film containing silicon on a substrate surface where silicon is exposed, the processing chamber storing the substrate, and the substrate in the processing chamber. A substrate holder for holding the substrate, a heating means for heating the atmosphere in the substrate and the processing chamber, a gas supply means for supplying a source gas containing silicon, an etching gas containing chlorine, and a hydrogen gas into the processing chamber; An exhaust unit that exhausts the atmosphere in the processing chamber; and a control unit that controls operations of at least the heating unit, the gas supply unit, and the exhaust unit, and the control unit controls the heating unit to control the substrate. And the gas supply means and the exhaust means are controlled to supply and exhaust the source gas and the etching gas into the processing chamber, so that the silicon is exposed. An epitaxial film containing silicon is formed on the surface of the substrate, and after the film formation, at least the gas supply unit that supplies the etching gas of the gas supply unit flows the hydrogen gas to purge the gas supply unit. The etching gas component remaining in the gas supply unit is combined with hydrogen and removed, and it is possible to prevent the etching gas component from being mixed into the processing chamber after processing and to improve the substrate processing quality. .

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

  First, an outline of substrate processing in which the present invention is implemented will be described.

  In a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), a technique called an elevated source / drain (or a raised source / drain) is attracting attention in order to suppress a short channel effect accompanying a reduction in gate length. This is a technique in which Si or SiGe is epitaxially grown only in the source / drain region where Si is exposed, and nothing is grown in other regions where SiO2, SiN, etc. are exposed. ing.

  FIG. 1 shows a schematic structure of a MOSFET in which an elevated source / drain is formed.

  A Si-containing gas such as SiH4, Si2 H6, or SiH2 Cl2 is used as a source gas for selective growth of Si or SiGe. In the case of SiGe, a Ge-containing gas such as GeH4 or GeCl4 is further added. When a source gas is introduced in the CVD reaction, growth starts immediately on Si, whereas a growth delay called a latent period occurs on SiO2 or SiN. During this incubation period, selective growth is to grow Si or SiGe only on Si.

  When it is desired to increase the thickness of the selective growth, an etching gas such as HCl or Cl2 is often added for the purpose of extending the incubation period on SiO2 or SiN. Etching gas is added to remove Si or SiGe nuclei generated on SiO2 or SiN. There are a case where an etching gas is added simultaneously with the source gas and the film formation and etching are simultaneously performed, and a case where the source gas and the etching gas are alternately flowed and the film formation and etching are alternately performed.

  In the present invention, after the etching gas is added, the inside of the nozzle is purged with H2 before being purged with N2. The Cl component adsorbed in the nozzle is difficult to remove with N2, but when this is purged with H2, Cl + H → HCl, and the Cl component is easily removed.

  Next, an outline of a substrate processing apparatus in which the present invention is implemented will be described with reference to FIGS.

  In FIGS. 2 and 3, the same components as those shown in FIG. 8 are denoted by the same reference numerals.

  The inlet flange 4 is connected to the upper side of the airtight preliminary chamber 16 through a furnace port gate valve 17 in an airtight manner, and the reaction tube 2 is erected on the inlet flange 4.

  The reaction tube 2 has a single-tube structure made of quartz and has a structure in which, for example, the inner tube 7 shown in FIG. 8 is omitted. A heating device 3 is disposed on the outer periphery of the reaction tube 2, and the heating state of the heating device 3 is controlled by the control unit 18.

  The gas supply means 19 includes a raw material gas supply source 21 for supplying a raw material gas containing silicon, an etching gas supply source 22 for supplying an etching gas containing chlorine, a hydrogen gas supply source 23 for supplying hydrogen gas, a nitrogen gas and the like. A gas supply source 25 including an inert gas supply source 24 for supplying an active gas, a gas supply line 26 for guiding the gas from the gas supply source 25 to the processing chamber 9, and the gas supply line 26 connected to the processing chamber; 9 includes a gas introduction nozzle 12 or the like which is a gas supply section for supplying gas, and the gas introduction nozzle 12 passes through the inlet flange 4 and is connected to the gas supply line 26, and is connected to the reaction tube 2. It rises along and opens at the upper part of the processing chamber 9.

  An exhaust pipe 13 communicates with the inlet flange 4, and an exhaust device such as a vacuum pump 27 is provided in the exhaust pipe 13 to constitute an exhaust means 28 that exhausts the atmosphere of the processing chamber 9.

  A boat elevator 31 as a means for loading / unloading the substrate holder is provided inside the preliminary chamber 16. The boat elevator 31 supports the boat 8, which is a substrate holder, so that it can be raised and lowered. It is designed to be attached to and removed from the chamber 9.

  A cassette storage portion 32 is disposed opposite to the preliminary chamber 16 via a gate valve 34, and a substrate transfer container (wafer cassette 33) is stored in the cassette storage portion 32.

  A substrate transfer device 35 is provided between the preliminary chamber 16 and the cassette storage portion 32, and the substrate transfer device 35 transfers the wafer 10 between the cassette storage portion 32 and the boat 8 in the lowered state. I do.

  Next, the flow of substrate processing will be described with reference to FIG.

  The wafer 10 is loaded by an external transfer device (not shown) while being stored in the wafer cassette 33 and is stored in the cassette storage unit 32 (wafer loading). With the furnace port gate valve 17 closed, the gate valve 34 is opened, and the substrate transfer machine 35 transfers the wafers 10 of the wafer cassette 33 to the lowered boat 8.

  When a predetermined number of wafers 10 are transferred to the boat 8, the gate valve 34 is closed. The furnace gate gate valve 17 is opened, and the boat 8 is loaded into the processing chamber 9 by the boat elevator 31 (boat loading).

  The furnace cap is hermetically closed by the seal cap 5, and the processing chamber 9 is reduced to the processing pressure and maintained by the exhaust means 28. Exhaust by the exhaust means 28 is controlled by the control unit 18 (decompression).

  The processing chamber 9 and the wafer 10 are heated by the heating device 3. The temperature of the processing chamber 9 and the wafer 10 by the heating device 3 and the stable maintenance at a predetermined temperature are controlled by the control unit 18 (temperature increase and temperature stabilization).

  An etching gas containing a source gas and Cl is simultaneously or alternately introduced from the gas supply source 25 into the processing chamber 9 through the gas supply line 26 and the gas introduction nozzle 12.

  Source gas and etching gas are introduced into the processing chamber 9 from the upper end of the gas introduction nozzle 12. The gas activated by heating comes into contact with the wafer 10 while descending the processing chamber 9. The source gas is deposited on the exposed portion of the substrate surface, and a thin film grows. On the other portions of the substrate, the etching of the source gas suppresses the adhesion of the source gas, and the silicon is exposed. A semiconductor epitaxial film is selectively grown. During film formation, the boat rotating device 36 rotates the wafer 10 through the boat 8 to improve the uniformity within the wafer 10 surface (film formation).

  When the film formation is completed, hydrogen gas is supplied from the gas supply source 25 to the processing chamber 9 through the gas supply line 26 and the gas introduction nozzle 12 for a predetermined time. When the gas supply line 26 is separated into a source gas supply line and an etching gas supply line, hydrogen gas is supplied to the processing chamber 9 through the etching gas supply line and the gas introduction nozzle 12. The In addition, hydrogen gas is supplied to at least the gas supply section, that is, the gas introduction nozzle 12 in the etching gas supply path.

  By supplying hydrogen gas, the gas supply line 26 and the inside of the gas introduction nozzle 12 are purged with hydrogen gas.

  When the etching gas is introduced, Cl components adhere to the wall surfaces of the gas introduction nozzle 12 and the gas supply line 26. However, by purging with hydrogen gas, Cl + H → HCl, and the adhered Cl components are removed. Removed (H2 purge).

  When purging with hydrogen gas is completed, an inert gas such as nitrogen gas is introduced into the processing chamber 9 from the gas introduction nozzle 12, and the inside of the processing chamber 9 is purged with the inert gas. Returned to At least the Cl component of the gas supply unit is removed by the gas purge of the gas supply unit with hydrogen gas, and the Cl component is not mixed in the supplied inert gas (N2 purge, atmospheric pressure).

  The furnace gate gate valve 17 is opened, and the boat elevator 31 lowers the boat 8 to the preliminary chamber 16, and the wafer 10 is cooled to a required temperature in the preliminary chamber 16 (boat unloading, wafer cooling). .

  The gate valve 34 is opened, and the processed wafer 10 is discharged from the boat 8 by the substrate transfer device 35 by the substrate transfer device 35 and transferred to the wafer cassette 33. The processed wafer 10 is unloaded from the substrate processing apparatus while being stored in the wafer cassette 33 (wafer unloading).

  In the processing of the wafer 10 described above, the source gas flows from the upper portion to the lower portion of the processing chamber 9 and is discharged from the exhaust pipe 13 communicated with the lower portion. Accordingly, the atmospheric gas in the lower part of the processing chamber 9 is exhausted from the exhaust pipe 13 without rising.

  Although there are contamination sources such as the O-ring 14 and the boat rotating device 36 in the lower portion of the processing chamber 9, even if the atmosphere in the lower portion of the processing chamber 9 is contaminated by these contamination sources, the contaminated atmosphere is still in the processing chamber 9. The air is exhausted from the exhaust pipe 13 without rising, that is, without contaminating the wafer 10.

  Needless to say, the gas purging of the gas supply line 26 with hydrogen gas can be similarly performed in the conventional substrate processing apparatus shown in FIG.

  Next, in FIG. 5 to FIG. 7, an example in the case where the substrate processing is performed by the substrate processing apparatus according to the present invention is shown.

  FIG. 5 shows a particle adhesion state of the wafer 10 of the present invention when Si is selectively grown by simultaneously supplying SiH2 Cl2 as a source gas and HCl simultaneously as an etching gas and simultaneously performing film formation and etching.

  Further, FIG. 6 and FIG. 7 show the particle adhesion state of the wafer 10 when processing is performed by a conventional substrate processing apparatus in which only N2 purge is performed after film formation.

  A particle map immediately after film formation in this case is shown in FIG. Many particles are counted in the vicinity of the gas introduction nozzle 12.

  FIG. 7 shows a particle map of the wafer 10 measured again after 4 days. Particles in the vicinity of the gas introduction nozzle 12 are reduced.

  Since the particles are decreasing with time, the measured particles are not actual particles, and the Cl component adsorbed on the wafer surface is erroneously counted as particles, and the number decreases because they desorb with time. It seems to have been.

It is the schematic of the structure of MOSFET in which the elevated source / drain was formed. 1 is a schematic cross-sectional view of a substrate processing apparatus according to an embodiment of the present invention. It is a schematic sectional drawing of the processing furnace which concerns on embodiment of this invention. It is a flowchart which shows the flow of the board | substrate process in embodiment of this invention. It is the particle map of the board | substrate processed by the substrate processing apparatus which concerns on embodiment of this invention. It is the particle map of the board | substrate just after processing with the conventional substrate processing apparatus. It is a particle map of the substrate 4 days after processed by the conventional substrate processing apparatus. It is a schematic sectional drawing of the processing furnace which concerns on the conventional substrate processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Processing furnace 2 Reaction tube 3 Heating device 4 Inlet flange 8 Boat 9 Processing chamber 10 Wafer 12 Gas introduction nozzle 13 Exhaust pipe 18 Control part 21 Source gas supply source 22 Etching gas supply source 23 Hydrogen gas supply source 24 Inert gas supply source 25 Gas supply source 26 Gas supply line

Claims (1)

  A substrate processing apparatus for selectively growing an epitaxial film of a semiconductor containing silicon on a substrate surface where silicon is exposed, a processing chamber for storing the substrate, and a substrate holder for holding the substrate in the processing chamber Heating means for heating the substrate and the atmosphere in the processing chamber, gas supply means for supplying a source gas containing silicon, an etching gas containing chlorine, and hydrogen gas into the processing chamber, and an atmosphere in the processing chamber An exhaust unit for exhausting, and a control unit for controlling operations of at least the heating unit, the gas supply unit, and the exhaust unit, and the control unit controls the heating unit to heat the substrate, and The substrate surface on which the silicon is exposed by controlling the supply means and the exhaust means to supply and exhaust the source gas and the etching gas into the processing chamber. Epitaxial film containing silicon is formed, and after the film formation, the hydrogen supply gas is supplied to at least the gas supply part supplied with the etching gas of the gas supply means to purge the inside of the gas supply part. apparatus.

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