JP2012114327A - Substrate processing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide substrate processing equipment capable of preventing an end portion of a heating element from reducing its lifetime due to a pest phenomenon.SOLUTION: Substrate processing equipment comprises: a processing chamber for processing a wafer 105; a heating device for heating the wafer 105 in the processing chamber. The heating device includes: a heat insulating body 107 covering the processing chamber; a heating element 108 provided in an inner periphery surface of the heat insulating body 107 and composed of molybdenum disilicide; a cover 84 surrounding an end portion of the heating element 108 pulled out of the heat insulating body 107; and an inert gas supply device 87 for supplying an inert gas into the cover 84. The heat insulating body 107 has an inert gas supply line 122 for supplying the inert gas connected thereto. Supplying the inert gas into the cover can prevent the end portion of the heating element from reducing its lifetime due to a pest phenomenon in a low temperature region.

Description

The present invention relates to a substrate processing apparatus.
For example, semiconductor wafers (hereinafter referred to as ICs) on which semiconductor integrated circuit devices (hereinafter referred to as ICs) are fabricated are used for annealing, oxidation, diffusion, CVD, reflow for carrier activation and planarization after ion implantation, etc. And what is effective.

As a conventional hydrogen annealing apparatus used in a hydrogen annealing process, which is one process in an IC manufacturing method, a space between a processing chamber for processing a wafer and a heating apparatus for heating the processing chamber is in an inert gas atmosphere. A hydrogen annealing apparatus that anneals the wafer by introducing and exhausting hydrogen gas into the processing chamber, wherein the space between the processing chamber and the heating apparatus is replaced with an atmosphere containing oxygen, and the atmosphere of the heating apparatus is There is a hydrogen annealing apparatus that forms an oxide film on the surface of a heating element. For example, see Patent Document 1.
According to this hydrogen annealing apparatus, an oxide film can be formed on the surface of the heating element, so that the deterioration of the oxidation protection film can be prevented and the life of the heating element can be extended.

JP 2006-261362 A

  However, in the conventional hydrogen annealing apparatus, since the end of the heating element is drawn out of the heat insulator, it is not possible to prevent a decrease in life due to a pest (pulverization) phenomenon in a low temperature region.

  An object of the present invention is to provide a substrate processing apparatus capable of preventing a reduction in lifetime due to low-temperature oxidation at an end portion of a heating element.

Representative inventions disclosed in the present application are as follows.
(1) a processing chamber for processing a substrate;
A heating device for heating the substrate in the processing chamber;
A substrate processing apparatus comprising:
The heating device includes a heat insulator that covers the processing chamber;
A heating element provided on the inner peripheral surface of the heat insulator;
A cover surrounding an end of the heating element drawn out of the heat insulator;
An inert gas supply device for supplying an inert gas into the cover;
A substrate processing apparatus.
(2) The substrate processing apparatus according to (1), wherein the inert gas is supplied into the cover when the temperature inside the heat insulating body becomes equal to or higher than a preset temperature.

  According to this substrate processing apparatus, by supplying an inert gas into the cover, it is possible to prevent a decrease in life due to a low temperature region pest (powdering) phenomenon at the end of the heating element.

It is a schematic perspective view which shows the substrate processing apparatus which is one Embodiment of this invention. It is side surface sectional drawing which shows a reaction furnace. It is side surface sectional drawing which shows the principal part.

  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 to heat-treat a wafer as a substrate. In addition, a FOUP (Front Opening Unified Pod), which is a sealed cassette, is used for transporting the wafer. Since the FOUP (hereinafter referred to as a pod) stores the wafer in a sealable storage chamber, contamination of the wafer during transfer can be prevented.

As shown in FIG. 1, the substrate processing apparatus according to this embodiment includes a housing 1. A pod stage 2 that exchanges pods with an external transfer device (not shown) is provided on the front surface of the housing 1, and the pod stage 2 communicates with the inside of the housing 1 through a shutter 3.
A pod opener 5 is provided in front of the housing 1 so as to face the pod stage 2, a pod stocker 6 is provided above the pod opener 5, and between the pod stocker 6, the pod opener 5, and the pod stage 2. A pod loader 7 is provided.
A boat elevator 8 is provided on one inner rear side of the housing 1, and a seal cap 10 is provided on a lifting arm 9 that extends horizontally from the boat elevator 8. The seal cap 10 closes the furnace port of the processing furnace 11 that forms the processing chamber. A holder (hereinafter referred to as a boat) 106 for holding the wafer 105 in multiple stages in a horizontal posture is placed on the seal cap 10. When the boat 106 is lowered, the furnace port is closed by the furnace port shutter 16.

On the other side of the housing 1, a boat exchange device 12 is provided facing the boat elevator 8, and a wafer transfer device 13 is provided between the boat exchange device 12, the boat elevator 8, and the pod opener 5.
The pod stage 2 exchanges the pod 4 between the external transfer device and the pod loader 7. The pod loader 7 can traverse, move up and down, and move back and forth. The pod 4 of the pod stage 2 is transferred to the pod opener 5 and the pod stocker 6, and the pod 4 is transferred between the pod opener 5 and the pod stocker 6. Or The pod opener 5 opens and closes the lid of the pod 4.
The wafer transfer device 13 can move up and down, move forward and backward, and rotate. The wafer transfer device 13 transfers the wafer 105 between the pod 4 on the pod opener 5 and the boat 106 held by the boat changer 12.
The boat changer 12 has two boat support arms 14 and 15. The boat support arms 14 and 15 are independently rotatable and can be moved up and down, and the boat 106 is moved between the wafer transfer position A, the boat transfer position B, and the wafer cooling position C.
The seal cap 10 receives the boat 106 holding the unprocessed wafer 105 at the boat transfer position B from the boat changer 12 and carries it into the processing furnace 11 by the boat elevator 8.

In the processing furnace 11, the unprocessed wafer 105 is heated, and a required processing gas is introduced to process the wafer. The boat 106 is rotated by a rotating device (not shown) provided in the seal cap 10 in order to improve processing uniformity in the processing furnace 11 during wafer processing.
When the processing is completed, the boat elevator 8 pulls the boat 106 from the processing furnace 11 to the boat transfer position B, and transfers the boat 106 to the boat changer 12.
The boat 106 holding the processed wafer 105 is moved to the wafer cooling position C and cooled until it reaches a predetermined temperature. Meanwhile, the boat 106 holding the unprocessed wafer 105 is moved from the wafer transfer position A to the boat transfer position B, transferred to the seal cap 10, and carried into the processing furnace 11 by the boat elevator 8.
When the processed wafer 105 is cooled to a predetermined temperature at the wafer cooling position C, the boat exchange device 12 moves the boat 106 holding the processed wafer 105 to the wafer transfer position A.
The wafer transfer device 13 pays out the processed wafer 105 from the boat 106 at the wafer transfer position A to the pod 4 on the pod opener 5. When the processed wafer 105 is loaded into the pod 4, the pod 4 is transferred to the pod stage 2 by the pod loader 7 and further carried out by the external transfer device.
The pod 4 loaded with the unprocessed wafer 105 is transferred to the pod opener 5 by the pod loader 7. The wafer transfer device 13 transfers the unprocessed wafer 105 from the pod 4 to the empty boat 106 at the wafer transfer position A.
Then, the processing of the wafer 105 is repeatedly executed.

  Hereinafter, the processing furnace 11 according to the present embodiment will be described.

As shown in FIGS. 2 and 3, a reaction tube 104 is concentrically provided inside the cylindrical heating device 102, and a cylindrical shape is provided between the reaction tube 104 and the heating device 102. A furnace space 124 is formed. The in-furnace space 124 communicates with the exhaust conduit 113.
A processing gas introduction pipe 119 and an exhaust line 121 are communicated with the reaction pipe 104. The processing gas introduction pipe 119 is provided with a flow rate controller 125, and the exhaust line 121 is provided with a pressure controller 126 so that the processing gas is introduced at a predetermined flow rate and the reaction tube 104 is maintained at a predetermined pressure. As much as possible, exhaust gas is discharged. A cooling gas supply line 117 communicates with the cooling gas introduction duct 116, and an air valve 129 is provided in the cooling gas supply line 117.
An inert gas supply line 122 communicates with the furnace space 124, and a flow rate control valve 127 and an air valve 128 are provided in the inert gas supply line 122. An oxygen gas mixing line 130 is joined to the inert gas supply line 122, and a flow control valve 131 and an air valve 132 are provided in the oxygen gas supply line 130. From the oxygen gas mixing line 130, oxygen gas or air is joined to the inert gas supply line 122.

The heating device 102 includes a heat generating part 109, a heater case 111, and a ceiling part 112. The heat generating portion 109 includes a cylindrical heat insulating body 107 and a heat generating body 108 disposed on the inner peripheral surface of the heat insulating body 107.
The heat insulator 107 is formed of an alumina ceramic formed of aluminum oxide (Al2 O3) and silica (SiO2).
The heating element 108 can be rapidly heated and has a cross-sectional shape such as an elliptical shape or a flat plate shape so as to increase the heat generating surface area.
The heating element 108 is made of molybdenum disilicide (MoSi2) as a resistance heating element. A heating element made of molybdenum disilicide has a higher melting point than a metal (for example, Fe-Cr-Al metal) heating element, and an oxide film (protective film) is formed in a temperature region exceeding 1000 ° C. High oxidation resistance. Therefore, a heating element made of molybdenum disilicide is often used for heat treatment in a high temperature region (1000 to 1800 ° C.).
However, a heating element made of molybdenum disilicide has a problem that in the low-temperature region (400 to 600 ° C.), a pest (powdering) phenomenon occurs due to low-temperature oxidation, the heating element becomes thin, and eventually the wire breaks. There is a point.

As shown in FIG. 3, the heating element 108 has the end portion 81 bent at a right angle, and the end portion 81 passes through the cylindrical wall of the heat insulating body 107 and is drawn out to the outside. It is in a suspended state on the inner periphery. One end of an electric wire 82 is connected to the end 81 of the heating element 108, and one end of a heater terminal 83 formed of stainless steel is connected to the other end of the electric wire 82. A power cable (not shown) is connected to the other end portion of the heater terminal 83, and the heating element 108 generates heat by energizing the end portion 81 via the power cable, the heater terminal 83 and the electric wire 82. It is supposed to be.
The electric wire 82 is formed of a flexible aluminum net assembly wire. Aluminum has heat resistance, corrosion resistance, and good electrical conductivity, but its melting temperature is about 600 ° C.
Since the heating element 108 made of molybdenum disilicide is extremely brittle, it may be damaged by a force due to thermal expansion and contraction. However, the flexibility of the electric wire 82 can absorb the force due to the thermal expansion / contraction of the heating element 108, so that the heating element 108 made of molybdenum disilicide can be prevented from being damaged.

As shown in FIG. 3, a cover 84 is formed on the outer peripheral surface of the heat insulating body 107 so as to surround the end portion 81 of the heating element 108, the electric wire 82, and the heater terminal 83. A nozzle 85 for supplying gas into the cover 84 is connected to the lower end of the cover 84, and a gas supply line 86 is connected to the nozzle 85. The gas supply line 86 is connected to an inert gas supply device 87 and an air supply device 88, and the inert gas supply device 87 and the air supply device 88 are controlled by the main control unit 137.
As shown in FIG. 3, a thermocouple 89 for detecting the temperature in the furnace space 124 is inserted in the cylindrical wall of the heat insulating body 107, and the thermocouple 89 sends a detection result to the main control unit 137. It is supposed to send.
An exhaust port 90 for exhausting the inside of the cover 84 is formed at the upper end portion of the cover 84.

The main controller 137 controls the processing state of the wafer 105 processed in the reaction tube 104. The main control unit 137 includes a temperature control unit 138 for controlling the temperature in the furnace, a gas flow rate control unit 139 for controlling the flow rate of the processing gas and the cooling gas, a pressure control unit 140 for controlling the pressure in the reaction tube 104, A drive control unit 141 that controls a mechanism unit such as a boat elevator is provided.
The heat generating part 109 is divided into required zones in the axial direction of the heating device 102, and a heater temperature detector 135 is provided for each zone. An in-furnace temperature detector 136 is erected along the inner surface of the reaction tube 104, and the detected temperature in the furnace detected by the in-furnace temperature detector 136 and the detected heater temperature detected by the heater temperature detector 135 are the temperature control unit. It is input to 138. Zone control for performing soaking is performed based on the detected temperature of each zone and the detected temperature in the furnace.

At least one oxygen concentration detector 143 is provided at a required portion of the furnace space 124. The oxygen concentration detected by the oxygen concentration detector 143 is input to the gas flow rate control unit 139.
Opening and closing of the air valves 129, 128, 132 is controlled by the gas flow rate control unit 139. The gas flow rate control unit 139 controls the amount of gas introduced by the flow rate controller 125, and the pressure control unit 140 controls the exhaust pressure via the pressure controller 126 to control the pressure in the reaction tube 104. Further, by controlling the opening and closing of the air valves 128 and 132, the flow rate control valve 127, and the flow rate control valve 131, whether the gas supplied to the furnace space 124 is an inert gas or a gas containing oxygen In addition to performing control, control is also performed to maintain the oxygen concentration at a predetermined value based on the detection result from the oxygen concentration detector 143.

  Next, the operation of the processing furnace according to this embodiment will be described.

The boat 106 on which a predetermined number of wafers 105 are transferred is carried into the processing chamber 17 by the boat elevator 8. When the boat 106 is carried into the processing chamber 17, the processing chamber 17 is hermetically sealed with a seal cap.
The reaction furnace 11 is heated by the heating device 102, the processing chamber 17 is decompressed by the exhaust line 121, and the processing gas is introduced into the processing chamber 17 by the processing gas introduction pipe 119. Thereby, heat treatment is performed on the wafer 105 in the processing chamber 17.

At this time, an inert gas (nitrogen gas in the present embodiment) is supplied from the inert gas supply device 87 through the gas supply line 86 and the nozzle 85 into the cover 84 on the outer peripheral surface of the heat insulator 107, and The air is exhausted from the exhaust port 90. The end 81 of the heating element 108, the electric wire 82, and the heater terminal 83 are cooled by the inert gas blown into the cover 84. Therefore, melting of the aluminum netting wire (melting temperature is 600 ° C.) forming the electric wire 82 can be prevented. Further, since the inside of the cover 84 is replaced with an inert gas, oxidation of the end portion 81 of the heating element 108, the electric wire 82, and the heater terminal 83 can be prevented.
Note that when the thermocouple 89 does not reach a preset temperature or higher, the inert gas supply device 87 does not supply the inert gas into the cover 84. The set temperature is, for example, 350 ° C. in consideration of a safety margin with respect to 400 ° C. which is the temperature range where the plague phenomenon occurs.

When the heat treatment is completed, the supply of the processing gas is stopped, and the inside of the processing chamber 17 is replaced with an inert gas. Further, while supplying a cooling gas (for example, cooling air) from the cooling gas supply line 117, the exhaust gas is exhausted from the exhaust conduit 113, and the heating device 102 and the reaction tube 104 are lowered to a so-called standby temperature (described later) and maintained. The
Thereafter, the boat 106 is lowered by the boat elevator 8, and the processed wafer 105 is carried out of the processing chamber 17. The bottom furnace port of the reaction tube 104 is closed by the furnace port shutter 16, and the wafer 105 is delivered by the wafer transfer device 13.
Thereafter, the above-described operation is repeated.

Here, the standby temperature is a standby temperature between heat treatment steps. For example, even when the heat treatment temperature is 1000 ° C., when a processed wafer is carried out of the processing chamber, the wafer is not suitable for heat resistance such as a boat elevator, a boat exchange device, or a wafer transfer device in the housing. In addition, it is necessary to lower the temperature of the boat to a temperature that can protect the boat elevator, the boat exchange device, the wafer transfer device, and the like in the housing.
If the temperature difference between the standby temperature and the heat treatment temperature is large, time and energy are wasted in raising and lowering the temperature, so the standby temperature can ensure the heat resistance of the boat elevator, boat changer, wafer transfer machine, etc. in the housing. Within the range, it is desirable to be as high as possible.

In the present embodiment, it is possible to secure the heat resistance of the boat elevator, the boat exchange device, the wafer transfer machine, etc. in the casing so that the heating element 108 is not exposed to the low temperature oxidation temperature region of molybdenum disilicide. The upper limit temperature is set to 700 ° C. or higher.
In the present embodiment, the heating element 108 made of molybdenum disilicide is not exposed to a temperature region lower than 700 ° C., and therefore is not oxidized at a low temperature. That is, in the present embodiment, it is possible to prevent the occurrence of a plague (powdering) phenomenon due to low-temperature oxidation in the heating element 108 made of molybdenum disilicide, so that the heating element 108 is finally broken due to thinning and thinning. Can be prevented in advance.

Also in this standby temperature step, the inert gas is supplied into the cover 84 from the inert gas supply device 87 via the gas supply line 86 and the nozzle 85 and exhausted from the exhaust port 90. Thereby, it is possible to prevent melting of the aluminum mesh wire (melting temperature is 600 ° C.) forming the electric wire 82 and to prevent oxidation of the end portion 81 of the heating element 108, the electric wire 82 and the heater terminal 83. Can do.
That is, when the temperature in the heat insulating body 107 is 700 ° C., the plague phenomenon does not occur on the surface of the heating element 108 in the heat insulating body 107. However, since the end portion 81 of the heating element 108 is drawn out of the heat insulating body 107, the temperature is lowered by radiation than the heating element 108 located in the heat insulating body 107. Is likely to cause plague. Therefore, supplying an inert gas into the cover 84 prevents the plague phenomenon from occurring at the end 81 of the heating element 108.

When the heater temperature detector 135 detects a temperature lower than 700 ° C. (that is, a temperature lower than the pest phenomenon occurrence temperature), an inert gas is supplied from the inert gas supply line 122 to the furnace space 124. As a result, the heating element 108 can be prevented from coming into contact with oxygen. Therefore, even if the heating element 108 made of molybdenum disilicide is exposed to a temperature region below 700 ° C., It is possible to prevent a pest (powdering) phenomenon due to low-temperature oxidation in the heating element 108 made of molybdenum, and it is possible to prevent the occurrence of a failure that the heating element 108 is finally disconnected due to thinning.
On the other hand, since it is not always necessary to supply the inert gas to the furnace space 124, the consumption of the inert gas can be reduced.

  By the way, an oxide film can be formed on the surface of the heating element 108 made of molybdenum disilicide by high-temperature heat treatment. However, a high temperature region during heat treatment (for example, 1000 to 1800 ° C.) and a low temperature region during standby temperature (for example, 700 ° C.) are repeated to form the surface of the heating element 108 made of molybdenum disilicide. Cracks occur in the oxide film. As a result, the life of the heating element 108 is reduced.

Therefore, in the present embodiment, an oxide film is formed on a crack portion generated in the heating element 108 made of molybdenum disilicide.
After the lower end furnace port of the reaction tube 104 is closed by the furnace port shutter 16, the air valve 132 is opened, oxygen gas is mixed with the inert gas supplied from the inert gas supply line 122, and supplied to the furnace space 124. The oxygen concentration in the furnace space 124 is adjusted by controlling the flow rate of the oxygen gas and the inert gas by controlling the flow rate control valve 127 and the flow rate control valve 131 based on the detection result of the oxygen concentration detector 143. The oxygen concentration in the furnace space 124 is adjusted to be at least 20%. The oxygen concentration may be a high concentration of 30%, 40%, or 40%.
In parallel with the adjustment of the oxygen concentration, power is supplied to the heating element 108 and the heating element 108 is heated. The temperature elevation temperature is set to a high temperature of 1000 ° C. to 1600 ° C. By heating the heating element 108 in an oxygen atmosphere, an oxide film is formed on the surface of the heating element 108. The oxide film generates heat in an inert gas atmosphere and repairs the deterioration of the oxide film on the surface.
As a result, an oxide film can be formed in the crack portion generated in the heating element 108 made of molybdenum disilicide, so that the lifetime of the heating element 108 made of molybdenum disilicide can be extended.

Incidentally, the generation of the oxide film is limited by the heating temperature and time, and the film is formed in a shorter time as the heating temperature is higher, and the film is formed earlier as the oxygen concentration is higher.
For example, when the heating element 108 is molybdenum disilicide, it is heated at 1200 ° C. for 3 hours, heated at 1400 ° C. for 2 hours, and heated at 1600 ° C. for 1 hour. A molybdenum (MoO3) coating is formed.
When the heating element is Kanthal Al, when heated at 1000 ° C. for 10 hours and heated at 1200 ° C. for 5 hours, an aluminum trioxide (Al 2 O 3) film is formed on the surface of the heating element 108.

  According to this embodiment, the following effects can be obtained.

(1) Since the inert gas is supplied into the cover on the outer peripheral surface of the heat insulator, it is possible to prevent the occurrence of the plague phenomenon at the end of the heat generator that falls below the temperature of the heat generator inside the heat insulator. It is possible to prevent the end portion and thus the life of the entire heating element from being reduced.

(2) By supplying the inert gas into the cover on the outer peripheral surface of the heat insulator, it is possible to prevent melting of the aluminum mesh wire forming the electric wire and to prevent oxidation of the electric wire and the heater terminal. it can.

(3) Since the inert gas consumption can be reduced by setting so that the inert gas is not supplied into the cover when the inside of the cover does not reach a set temperature (for example, 350 ° C.), Cost can be reduced.

(4) By forming the electric wire with a flexible aluminum mesh wire, it is possible to absorb the force due to the thermal expansion and contraction of the heating element, so that the brittle molybdenum disilicide heating element is damaged. Can be prevented.

(5) By setting the standby temperature to 700 ° C. or higher, it is possible to prevent a pest (pulverization) phenomenon due to low-temperature oxidation in a heating element made of molybdenum disilicide, and to bring inert gas into the furnace space. Since it is not necessary to supply constantly, the consumption of inert gas can be reduced.

(6) By forming an oxide film in the crack portion generated in the heat generating element made of molybdenum disilicide, the life of the heat generating element made of molybdenum disilicide can be extended.

(7) By extending the life of the heating element made of molybdenum disilicide, it is possible to reduce the failure of the heating apparatus, and thus the throughput of the substrate processing apparatus can be increased.

  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 step of forming the oxide film on the heating element is not limited to the sequential repetition between the heat treatment step and the heat treatment step, but may be performed depending on the generation state of the oxide film crack and the deterioration state of the oxide film. One oxide film forming step may be incorporated into one heat treatment step.

11 ... reactor, 17 ... processing chamber,
81 ... End of heating element, 82 ... Electric wire, 83 ... Heater terminal, 84 ... Cover, 85 ... Nozzle, 86 ... Gas supply line, 87 ... Inert gas supply device, 88 ... Air supply device, 89 ... Thermocouple, 90 ... exhaust port,
DESCRIPTION OF SYMBOLS 102 ... Heating device, 104 ... Reaction tube, 105 ... Wafer, 106 ... Boat, 107 ... Heat insulator, 108 ... Metal heating element, 109 ... Heat generating part, 110 ... Cylindrical space, 111 ... Heater case, 112 ... Ceiling part, 113 DESCRIPTION OF SYMBOLS ... Exhaust conduit, 114 ... Gas blowing hole, 116 ... Cooling gas introduction duct, 117 ... Cooling gas introduction line, 119 ... Process gas introduction pipe, 121 ... Exhaust line, 122 ... Inert gas supply line, 124 ... Space in furnace , 125 ... flow rate controller, 126 ... pressure controller, 127 ... flow rate control valve, 128 ... air valve, 129 ... air valve, 130 ... oxygen gas mixing line, 131 ... flow rate control valve, 132 ... air valve, 135 ... heater temperature detector DESCRIPTION OF SYMBOLS 136 ... Furnace temperature detector, 137 ... Main control part, 138 ... Temperature control part, 139 ... Gas flow rate control part, 140 ... Pressure control part, 14 ... drive control unit, 143 ... oxygen concentration detector.

Claims (2)

A processing chamber for processing the substrate;
A heating device for heating the substrate in the processing chamber;
A substrate processing apparatus comprising:
The heating device includes a heat insulator that covers the processing chamber;
A heating element provided on the inner peripheral surface of the heat insulator;
A cover surrounding an end of the heating element drawn out of the heat insulator;
An inert gas supply device for supplying an inert gas into the cover;
A substrate processing apparatus.   The substrate processing apparatus according to claim 1, wherein the inert gas is supplied into the cover when the temperature inside the heat insulating body becomes equal to or higher than a preset temperature.

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