JP2006080256A - Substrate processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve throughput by shortening a heat treating time duration. <P>SOLUTION: In a low-temperature annealing device 10 having a process tube 31 made of a silicon carbide in which the processing chamber 32 of a wafer 1 is formed and a heater unit 60 for heating the wafer 1 of the processing chamber 32 to a relatively low temperature of 150°C to 600°C, the heating element 63 of the heater unit 60 is brought into contact with the external surface of a processing tube 31 through an insulating layer 64 made of alumina. In the case of annealing, the processing chamber 32 is made into a hydrogen gas atmosphere. Since the process tube can be heated by heat conduction, a heat transfer speed between the heater unit and the process tube can be improved. The hydrogen gas atmosphere where thermal conductivity is large is provided. Thereby, the heat of the process tube heated by the heater unit can be transferred by the heat conduction. Since the temperature rising of the wafer 1 can be performed in a short time, the throughput of the low-temperature annealing device can be improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a substrate processing apparatus that accommodates a substrate in a processing chamber and performs processing under heating. The present invention relates to an effective heat treatment apparatus (furnace) used for thermal treatment such as annealing, reflow, oxidation, diffusion, and film formation by thermal CVD reaction.

In an IC manufacturing method, a batch type vertical hot wall type annealing apparatus, which is an example of a heat treatment apparatus, is widely used for annealing a wafer.
A batch type vertical hot wall type annealing apparatus (hereinafter referred to as an annealing apparatus) includes a process tube that forms a processing chamber and is installed vertically, an exhaust pipe that exhausts the processing chamber, and a gas supply pipe that supplies gas to the processing chamber Are connected to each other, a heater unit that is laid outside the process tube and heats the processing chamber, and a boat that holds a plurality of wafers aligned in the vertical direction and carries them into the processing chamber. When a boat holding a plurality of wafers is loaded into the processing chamber from the bottom furnace port (boat loading), annealing gas is supplied from the gas supply pipe to the processing chamber, and the processing chamber is heated by the heater unit. The wafer is annealed (see, for example, Patent Document 1).
JP 2004-14543 A

A process tube of a conventional annealing apparatus is generally formed of quartz glass (SiO ₂ ).

In the annealing apparatus in which the process tube is formed of quartz glass, if the heat treatment temperature is lowered, there is a problem that the heat treatment time becomes longer and the throughput is lowered for the following reasons.
1) Generally, when the heat treatment temperature is low, the heating temperature of the heater unit also becomes low, so that heat transfer due to radiation is significantly reduced.
2) Because quartz glass is opaque to infrared rays, the radiant heat rays from the heater unit do not directly irradiate (not reach) the wafer in the process tube.
3) Because quartz glass has a low thermal conductivity, heat transfer from the heater unit to the wafer is extremely small, and it takes a long time to stabilize the wafer temperature.

  An object of the present invention is to provide a substrate processing apparatus that can shorten the heat treatment time and improve the throughput.

Representative inventions disclosed in the present application are as follows.
(1) a process tube in which a processing chamber for processing a substrate is formed, and a heater unit for heating the substrate in the processing chamber;
The heating element of the heater unit is electrically insulatively in contact with the outer surface of the process tube, or the distance between the heating unit of the heater unit and the process tube is greater than that of the substrate and the process tube. A substrate processing apparatus that is close to each other so as to be smaller than a distance from a process tube.
(2) The substrate processing apparatus according to (1), wherein the process tube is made of carbon (C), silicon (Si), silicon-impregnated silicon carbide (SiC), or silicon carbide.
In the case where contamination is not a problem, it may be formed of a metal or a metal coated with SiO ₂ or the like.
(3) The substrate according to (1), wherein the processing chamber has an atmosphere containing at least 20% of hydrogen (H ₂ ), helium (He), or neon (Ne) when processing the substrate. Processing equipment.
(4) a process tube in which a processing chamber for processing a substrate is formed, and a heater unit for heating the substrate in the processing chamber;
An annealing apparatus, wherein the inner surface of the process tube is provided with irregularities that disturb airflow.
(5) A process tube in which a processing chamber for processing a substrate is formed, a heater unit for heating the substrate in the processing chamber, a holding tool for holding the substrate in the processing chamber, and a rotational drive for rotating the holding tool. Equipment,
The substrate processing apparatus, wherein the holder is provided with fins that disturb the airflow in the processing chamber.
(6) carrying the substrate into the process chamber of the process tube;
The heating element of the heater unit is in contact with the outer surface of the process tube via an insulator, or the distance between the heating unit of the heater unit and the heater unit and the process tube is greater than the substrate and the process tube. Processing the substrate in the processing chamber while heating the process tube in a state of being close to each other so as to be smaller than the distance between
Unloading the substrate after processing from the processing chamber;
A method for manufacturing a semiconductor device, comprising:

  According to the means (1), since the heat transfer rate can be improved by heating the process tube by heat conduction, the temperature of the substrate can be raised and stabilized in a short time. The throughput of the processing apparatus can be improved.

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

In the present embodiment, the substrate processing apparatus according to the present invention is configured as an annealing apparatus (batch type vertical hot wall type annealing apparatus) that performs an annealing step in an IC manufacturing method, and particularly, a low temperature (150 ° C.). It is configured to exhibit an excellent effect in annealing at 600 ° C. or lower).
Incidentally, normal annealing is performed at 800 ° C. or more and 1200 ° C. or less.
As shown in FIGS. 1 and 2, the annealing apparatus 10 includes a housing 11 formed in a substantially rectangular parallelepiped box shape. A cassette stage 12 is installed inside the front wall of the housing 11, and a cassette 2 for storing and transferring the wafer 1 is supplied to the cassette stage 12 by an in-process transfer device (not shown). ing.
A cassette elevator 13 as an elevating means is provided on the rear side of the cassette stage 12 inside the housing 11, and a cassette transfer device 14 as a conveying means is attached to the cassette elevator 13. A cassette shelf 15 for storing the cassette 2 is provided on the rear side of the cassette elevator 13, and a spare cassette shelf 16 is provided above the cassette stage 12.
A clean unit 17 is provided above the spare cassette shelf 16, and the clean unit 17 is configured to distribute clean air inside the housing 11. A transfer elevator 18 is installed vertically on the rear side of the cassette shelf 15 inside the housing 11, and a wafer transfer device 19 for transferring the wafer 1 is installed in the transfer elevator 18.

A boat elevator 20 constructed by a motor-driven feed screw shaft device or the like is installed on the rear side of the transfer elevator 18 inside the housing 11, and the elevator 21 of the boat elevator 20 serves as a wafer holder. The boat 23 is supported via an arm 22 and a seal cap.
The boat 23 includes a pair of upper and lower end plates 24 and 25, and a plurality of holding members 26 disposed vertically between the both end plates 24 and 25, and is formed of silicon carbide. Each holding member 26 is provided with a plurality of holding grooves 27 which are arranged at equal intervals in the longitudinal direction so as to open in the same plane. The wafer 1 is held in the boat 23 by being aligned in a state where the centers are aligned with each other horizontally by inserting the outer peripheral portion between the plurality of holding grooves 27.
A first heat insulation cap 28 and a second heat insulation cap 29 are formed below the boat 23. The first heat insulating cap 28 arranged on the upper side is made of silicon carbide, and the second heat insulating cap 29 arranged on the lower side is made of quartz glass.

A process tube 31 is installed vertically on the top of the housing 11 so that the center line is vertical. The process tube 31 is transparent to heat rays such as infrared rays and far-infrared rays, and is made of silicon carbide, which is a material having a higher thermal conductivity than quartz glass, and has a cylindrical shape with a closed upper end and an opened lower end. Is formed.
Incidentally, the thermal conductivity of quartz glass (SiO ₂ ) is 1,66 W / mK, and the thermal conductivity of Si-impregnated silicon carbide (SiC) is 175 W / mK.
The cylindrical hollow portion of the process tube 31 forms a processing chamber 32 into which a plurality of wafers held by the boat 23 are loaded. The inner diameter of the process tube 31 forming the processing chamber 32 is the maximum outer diameter of the wafer to be handled. It is set to be larger than (for example, 300 mm).
At the lower end of the outer periphery of the process tube 31, a circular ring-shaped flange portion 33 protrudes horizontally.

A support ring 35 is horizontally suspended below the process tube 31 of the housing 11 via a lifting tool 34, and the support ring 35 supports the manifold 40 from below. On the support ring 35, a pressing ring 36 that holds the manifold 40 is mounted.
The manifold 40 is made of quartz glass, stainless steel, or the like, and is formed into a short, substantially cylindrical shape with both upper and lower ends opened. A furnace port 41 is formed by the lower end opening of the manifold 40.
At the lower end of the outer periphery of the manifold 40, a circular ring-shaped lower flange portion 42 is provided to project horizontally. The support ring 35 supports the manifold 40 and the process tube 31 by engaging with the peripheral edge of the lower end surface of the lower flange portion 42 from below.

A circular ring-shaped upper flange portion 43 is horizontally provided at the upper end of the outer periphery of the manifold 40. The lower end surface of the flange portion 33 of the process tube 31 is in contact with the upper end surface of the upper flange portion 43 of the manifold 40, and the process tube 31 is supported vertically on the manifold 40. The contact surface between the flange portion 33 of the process tube 31 and the upper flange portion 43 of the manifold 40 can absorb a difference in thermal expansion between the process tube 31 and the manifold 40 while ensuring a sufficient hermetic seal. So as to be flat and smooth.
Incidentally, the thermal expansion coefficient of quartz glass is 0, ^{6 to 0} , 9 × 10 ⁻⁶ / ° C., and the thermal expansion coefficient of silicon carbide is 3, 8 × 10 ⁻⁶ / ° C.
When a vacuum is required or when gas such as hydrogen is difficult to leak, an annular groove must be formed in the manifold 40 and completely sealed with a seal ring such as fluorine rubber.

A large-diameter exhaust pipe 44 having the other end connected to an exhaust device (not shown) is connected to the side wall of the manifold 40 so as to communicate with the processing chamber 32, and the exhaust pipe 44 exhausts the processing chamber 32. It is like that.
A gas introduction port 45 (see FIG. 3) having a horizontal portion and a vertical portion is opened inside the side wall of the manifold 40. A gas introduction pipe 46 is connected to a horizontal portion opened to the outer periphery of the side wall of the manifold 40 at the gas introduction port 45, and the other end of the gas introduction pipe 46 supplies a gas such as an annealing gas (see FIG. (Not shown). A nozzle 47 formed of silicon carbide is inserted and fixed in a vertical portion opened to the upper end surface of the manifold 40, and the nozzle 47 extends to the upper end portion of the processing chamber 32 along the inner peripheral surface of the processing chamber 32. It is laid. A spout opened at the upper end of the nozzle 47 is disposed at the upper end of the boat 23.

As shown in FIGS. 1 and 2, a shutter 50 that opens and closes the furnace port 41 is installed in the vicinity of the manifold 40 inside the housing 11, and the shutter 50 is carried out from the processing chamber 32 by the boat 23. The furnace port 41 is configured to be closed when being operated.
When the boat 23 is carried into the processing chamber 32, the furnace port 41 is configured to be closed by a seal cap 51. The seal cap 51 is made of a metal material such as stainless steel and is formed in a disk shape having a diameter larger than that of the furnace port 41.
A cover 52 made of quartz glass is attached to the upper surface of the seal cap 51, and a seal ring storage groove (not shown) is concentrically placed at the peripheral edge portion of the upper surface of the cover 52, so that the seal A seal ring (not shown) for sealing the furnace port 41 is stored in the ring storage groove.

A heater unit 60 for heating the wafer is disposed outside the process tube 31 so as to be concentrically arranged. The heater unit 60 is vertically supported by the housing 11. The heater unit 60 has a case 61 formed in a cylindrical shape by stainless steel or the like, a heat insulating tank 62 formed in a cylindrical shape by a heat insulating material and installed in the case 61, and a heat insulating tank 62 formed by a resistance heating element or the like. And a heating element 63 laid on the inner peripheral surface.
In the case of low temperature, the heat insulating material is not so necessary and may be thin. For cryogenic temperatures, it is considered best not to provide insulation.
The heating element 63 of the heater unit 60 is formed on the outer peripheral surface of the process tube 31 by an insulator such as alumina (Al ₂ O ₃ ) which is transparent to heat rays such as infrared rays and far infrared rays and has a high thermal conductivity. The heat generation of the heat generating element 63 is directly transferred to the process tube 31 via the insulating layer 64 not by radiation but by heat conduction. The heat transfer speed to is set large. That is, the heating element 63 is in electrical contact with the outer surface of the process tube 31.
Incidentally, the thermal conductivity of alumina is 19 W / mK for 96% alumina and 25 W / mK for 99% 5% alumina. The thermal expansion coefficient of alumina is ⁶ , 7-7, 0 × 10 ⁻⁶ / ° C. for 96% alumina, and 7, 1 × 10 ⁻⁶ / ° C. for 99% 5% alumina.

  Next, the operation of the annealing apparatus according to the above configuration will be described based on the hydrogen annealing step for the wafer.

The cassette 2 loaded with the wafer 1 to be subjected to the hydrogen annealing process is loaded into the cassette stage 12 by the in-process transfer device in an upward posture so that the wafer 1 is in a horizontal posture by the cassette stage 12. It is rotated 90 degrees.
Next, the cassette 2 is transported from the cassette stage 12 to the cassette shelf 15 or the spare cassette shelf 16 by cooperation of the raising / lowering operation of the cassette elevator 13, the transverse operation, the advance / retreat operation of the cassette transfer device 14, and the rotation operation.
The cassette shelf 15 is provided with a transfer shelf in which the cassette 2 to be transferred by the wafer transfer device 19 is stored. The cassette 2 to which the wafer 1 is transferred is the cassette elevator 13 and the cassette transfer device. 14 is transferred to the transfer shelf.

  When the cassette 2 is transferred to the transfer shelf, the wafer 1 is transferred from the transfer shelf to the boat 23 by the cooperation of the advance / retreat operation, the rotation operation of the wafer transfer device 19 and the raising / lowering operation of the transfer elevator 18. The The plurality of wafers 1 are loaded (wafer charging) by the wafer transfer device 19 in a state where the center lines are aligned parallel to each other on the boat 23.

When a predetermined number of wafers 1 are loaded, the boat 23 moves up to the processing chamber 32 preheated to a so-called standby temperature (100 to 200 ° C., for example, about 150 ° C.) as the seal cap 51 is raised by the boat elevator 20. It is carried in from the furnace port 41 of the manifold 40 (boat loading) and is left in the processing chamber 32 while being supported by the seal cap 51 as shown in FIG.
In this state, the seal cap 51 is in a state of hermetically sealing the furnace port 41. That is, when the seal ring at the peripheral edge of the cover 52 attached to the seal cap 51 is brought into close contact with the lower end surface of the manifold 40, the furnace port 41 is hermetically sealed.

Next, the inside of the process tube 31 is exhausted by the exhaust pipe 44 to a predetermined degree of vacuum (several tens to several tens of thousands Pa).
Further, the processing chamber 32 is uniformly heated by the heater unit 60 to a predetermined temperature (150 ° C. or higher and 600 ° C. or lower) lower than the normal processing temperature for annealing. At this time, heat generated from the heating element 63 of the heater unit 60 is directly transferred to the process tube 31 via the insulating layer 64 not by radiation but by heat conduction, so that the heat transfer speed from the heating element 63 to the process tube 31 is increased. Therefore, the temperature of the process tube 31 rises to a predetermined processing temperature in a short time.
When the temperature and pressure inside the process tube 31 are stabilized, hydrogen gas as an annealing gas is introduced into the processing chamber 32 by the gas introduction pipe 46, the gas introduction port 45, and the nozzle 47.
The processing conditions are as follows, for example.
The processing temperature is 400 ° C., the flow rate of hydrogen gas is several tens of cc / min to tens of thousands cc / min, the processing pressure is atmospheric pressure or reduced pressure, and the processing time is about 120 minutes.

When the processing time set in advance elapses, the residual gas in the processing chamber 32 is exhausted by the exhaust force of the exhaust pipe 44. Further, the temperature of the processing chamber 32 is lowered to a so-called standby temperature (for example, about 150 ° C.).
Next, the seal cap 51 is lowered to open the furnace port 41, and the group of wafers is unloaded from the furnace port 41 to the standby chamber directly below the process tube 31 while being held by the boat 23 (boat unloading). Is done.
When the boat 23 is carried out, the shutter 50 hermetically seals the furnace port 41.

The processed wafer 1 is transferred from the boat 23 to the cassette 2 of the transfer shelf by the reverse procedure of the operation described above.
The cassette 2 is transferred from the transfer shelf to the cassette stage 12 by the cassette transfer device 14 and is carried out of the casing 11 by the in-process transfer device.

By the way, since the thermal conductivity (182 × 10 ⁻³ W / mK) of the hydrogen gas used in the above annealing process is relatively large, the heat of the process tube 31 heated by the heater unit 60 is transferred to the wafer 1. It is transmitted very effectively not only by radiation but also by heat conduction of hydrogen gas. Accordingly, the temperature of the wafer 1 rises to a predetermined processing temperature in a short time.

  According to the embodiment described above, the following effects can be obtained.

1) By bringing the heating element of the heater unit into contact with the outer surface of the process tube via an insulator, the process tube can be heated by heat conduction to improve the heat transfer rate. The processing temperature can be increased in a short time, and as a result, the throughput of the annealing apparatus can be improved.

2) By using a gas with high thermal conductivity as the annealing gas, the heat of the process tube heated by the heater unit can be transferred to the wafer 1 not only by radiation but also by heat conduction of the gas. Therefore, the temperature of the wafer 1 can be raised to a predetermined processing temperature in a short time, and as a result, the throughput of the annealing apparatus can be improved.

  FIG. 4 is a side sectional view showing a main part of an annealing apparatus according to the second embodiment of the present invention.

The present embodiment is different from the above-described embodiment in that unevenness 37 that disturbs the flow of annealing gas is provided on the inner peripheral surface of the process tube 31 and the insulating layer is omitted.
In addition, it is desirable to set the width and depth of the unevenness 37 to several mm or more so that the airflow can be effectively disturbed. The unevenness 37 can be formed by a groove cutting method, a plate-like object fitting method, or the like.
Further, as shown in FIG. 4, the unevenness 37 may be provided on the entire inner peripheral surface of the process tube 31 or may be provided on a part of the inner peripheral surface of the process tube 31.

  According to the present embodiment, the unevenness 37 that disturbs the air flow of the annealing gas is provided on the inner peripheral surface of the process tube 31, so that the heat transfer rate from the process tube 31 to the wafer 1 by the annealing gas is further increased. Therefore, the temperature raising time of the wafer 1 can be shortened.

  FIG. 5 is a side sectional view showing the main part of the annealing apparatus according to the third embodiment of the present invention.

The present embodiment is different from the above-described embodiment in that fins 23a for disturbing the air flow of the annealing gas are provided on the outer peripheral surface of the boat 23, and the boat 23 is rotated by the rotation driving device 23b. The insulating layer is omitted.
In addition, as for the width | variety and length (depth) of the fin 23a, it is desirable to set to several mm or more so that an airflow can be disturbed effectively. The fins 23a can be provided by a groove cutting method, a plate-like object fitting method, or the like.

  According to the present embodiment, when the boat 23 is rotated by the rotation drive device 23b, the fins 23a provided on the outer peripheral surface of the boat 23 disturb the air flow of the annealing gas. Since the heat transfer rate to is further increased, the temperature raising time of the wafer 1 can be shortened.

  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 heater unit heating element is not limited to be placed in contact with the outer surface of the process tube via an insulator, and the heater unit heating element is connected to the heater unit and the process tube without contacting the heating element and the process tube. They may be placed in close proximity so that the distance between them is smaller than the distance between the wafer and the process tube. In other words, when the space is used as an insulating layer (so-called air gap) that electrically insulates the heating element and the process tube, the heating element and the process are within the range that can ensure insulation between the heating element and the process tube. It is desirable to set the proximity distance between the heating element and the process tube so that the heat transfer rate between the tube and the tube is maximized. Considering them, the distance between the heating element and the process tube is preferably 10 mm or less, preferably 2 mm or less.

The process tube is not limited to being formed of silicon carbide, but may be formed of carbon (C), silicon (Si), or silicon-impregnated silicon carbide (SiC), which is an example of a material having a higher thermal conductivity than quartz glass. .
Incidentally, the thermal conductivity of carbon is 900 to 2000 W / mK, and the thermal conductivity of silicon is 150 W / mK.
A process tube made of silicon-impregnated silicon carbide can be manufactured by immersing a ceramic product obtained by baking silicon carbide powder into silicon melted at a high temperature.

In order to improve the heat transfer rate, the treatment chamber is not limited to a 100% hydrogen gas atmosphere, and the treatment chamber contains at least 20% or more of hydrogen gas (H ₂ ), helium (He), or neon (Ne). It may be an atmosphere. Hydrogen gas, helium, and neon have better heat conductivity than nitrogen. When diluting a gas, use hydrogen gas, helium, and neon instead of nitrogen, and increase the heat transfer rate by setting the concentration to 20% or higher. Can be improved.
Incidentally, the thermal conductivity of helium is 150 × 10 ⁻³ W / mK, and the thermal conductivity of neon is 493 × 10 ⁻⁴ W / mK.

  An object to be annealed may be a wafer with an SOG film, a wafer with a PIQ film, a wafer with an aluminum (Al) film, a wafer with a copper (Cu) film, or the like.

As the annealing gas, nitrogen, hydrogen, argon, oxygen, water vapor (H ₂ O) or the like can be used. It is desirable to select an appropriate type of annealing gas according to the purpose of annealing.

  It is desirable that the annealing process conditions be set optimally according to the purpose of annealing, the type of annealing gas, and the like.

The present invention is not limited to an annealing apparatus, and can be applied to any substrate processing apparatus that is also used for oxidation processing, diffusion processing, film formation processing by thermal CVD reaction, and the like.
The present invention can be applied to a substrate processing apparatus provided with a double reaction tube, and can be applied not only to a batch type substrate processing apparatus but also to a single wafer type substrate processing apparatus.

  In the above embodiment, the case where the wafer is processed has been described. However, the processing target may be a photomask, a printed wiring board, a liquid crystal panel, a compact disk, a magnetic disk, or the like.

1 is a partially omitted perspective view showing an annealing apparatus according to an embodiment of the present invention. It is side surface sectional drawing. It is sectional drawing which shows the principal part. It is side surface sectional drawing which shows the principal part of the annealing apparatus which is 2nd embodiment of this invention. It is side surface sectional drawing which shows the principal part of the annealing apparatus which is 3rd embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wafer (substrate to be processed), 2 ... Cassette, 10 ... Annealing apparatus (substrate processing apparatus), 11 ... Housing, 12 ... Cassette stage, 13 ... Cassette elevator, 14 ... Cassette transfer device, 15 ... Cassette shelf, 16 ... Reserve cassette shelf, 17 ... Clean unit, 18 ... Transfer elevator, 19 ... Wafer transfer device, 20 ... Boat elevator, 21 ... Lifting platform, 22 ... Arm, 23 ... Boat, 23a ... Fin, 23b ... Rotation drive Apparatus, 24, 25 ... End plate, 26 ... Holding member, 27 ... Holding groove, 28 ... First heat insulating cap, 29 ... Second heat insulating cap, 31 ... Process tube, 32 ... Processing chamber, 33 ... Flange part, 34 ... Suspension tool, 35 ... support ring, 36 ... pressing ring, 37 ... concave, 40 ... manifold, 41 ... furnace port, 42 ... lower flange, 43 ... upper flange, 4 ... exhaust pipe, 45 ... gas introduction port, 46 ... gas introduction pipe, 47 ... nozzle, 50 ... shutter, 51 ... seal cap, 52 ... cover, 60 ... heater unit, 61 ... case, 62 ... heat insulation tank, 63 ... Heating element, 64 ... insulating layer.

Claims (1)

A process tube in which a processing chamber for processing a substrate is formed, and a heater unit for heating the substrate in the processing chamber,
The heating element of the heater unit is electrically insulatively in contact with the outer surface of the process tube, or the distance between the heating unit of the heater unit and the process tube is greater than that of the substrate and the process tube. A substrate processing apparatus that is close to each other so as to be smaller than a distance from a process tube.

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