JP2006190789A - Substrate processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable suppressing clogging of an exhaust pipe due to reaction by-products while saving resources and energy by eliminating a low temperature portion from an exhaust pipe of the secondary side of a vacuum pump, even if the piping length of the exhaust pipe is increased. <P>SOLUTION: A substrate processing apparatus has a processing chamber 201 for processing a wafer 200 as a substrate, gas supply ports 232A, 232B as a plurality of gas supply means for alternately supplying a reaction gas to the processing chamber 201, the vacuum pump 246 as an exhaust means for exhausting the gas in the processing chamber 201, a first exhaust pipe 231 provided between the primary side of the vacuum pump and the processing chamber 201, and a second exhaust pipe 234 provided on the secondary side of the vacuum pump 246. The second exhaust pipe 234 of the substrate processing apparatus is provided with a heated gas supply unit 221 as an inert gas supply means for supplying a high-temperature inert N<SB>2</SB>gas, so that the high-temperature inert N<SB>2</SB>gas may be supplied to the second exhaust pipe 234. The heated gas supply unit 221 is to supply a high-temperature inactive gas only when a recipe for supplying a reaction gas is executed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a substrate processing apparatus for processing a substrate by supplying a reaction gas to a processing chamber alternately while exhausting from an exhaust pipe, and more particularly to an apparatus for reducing deposition of reaction by-products in the exhaust pipe.

In a processing furnace constituting a substrate processing apparatus, for example, a semiconductor manufacturing apparatus, a CVD (Chemical Vapor Deposition) method is widely adopted as a method for forming a film on a substrate such as a semiconductor wafer. In this method, gas type A and gas type B are simultaneously supplied to the processing chamber, and film formation is performed on the substrate in the processing chamber. Residual gas in the treatment chamber is caused to flow to an exhaust gas treatment device such as a detoxification device through an exhaust pipe by a vacuum pump.
FIG. 7 shows a general exhaust gas system diagram of a CVD processing furnace constituting such a CVD apparatus.

  In FIG. 7, gas species A and B are introduced into a quartz reaction tube 2 hermetically sealed with a seal cap 5 to process the substrate. Gas species A and B are introduced into the heated reaction tube 2 through gas introduction ports 6 and 7 provided at the lower portion of the reaction tube 2. The gas species A and B introduced into the reaction tube 2 are supplied onto a plurality of substrates and formed on the substrates. After film formation on the substrate, the residual gas is removed from the exhaust port 8 provided at the bottom of the reaction tube 2 via the exhaust tube 21, trap 10, exhaust tube 22, vacuum pump 11, and exhaust tube 23. Sent to device 12 for processing.

  In such an exhaust gas system of a CVD processing furnace, reaction by-products generated by the reaction of gas species A and B are forcibly lowered by a trap 10, for example, a water-cooled trap, and are deposited on a solid phase. The method of removing is common. The exhaust pipe 21 connecting the exhaust port 8 and the water-cooled trap 10 is equipped with a pipe heater 9 capable of heating to a temperature at which reaction by-products do not precipitate on the solid phase. Therefore, no reaction by-products are attached to the exhaust pipes 22 and 23 on the downstream side of the water-cooled trap 10, and the exhaust pipes 22 and 23 are not clogged with the reaction products. The water-cooled trap 10 is regularly maintained.

  By the way, in recent years, a method called ALD (Atomic Layer Deposition) has begun to be adopted as a method for forming a film on a substrate. This is because, under certain film formation conditions (temperature, time, etc.), two (or more) introduced gases used for film formation are alternately supplied onto the substrate and adsorbed in units of one atomic layer, and surface reaction is performed. This is a method of forming a film by using only the film. FIG. 8 shows an exhaust gas system diagram of an ALD processing furnace constituting such an ALD apparatus.

  In this method, for example, the reactive gas species A is supplied from the gas introduction port 6 onto the plurality of substrates 4 inside the reaction tube 2 and adsorbed onto the substrates 4. Thereafter, the gas type A inside the reaction tube 2 is once exhausted. Subsequently, the gas species B is supplied from the gas introduction port 7 to react with the gas species A adsorbed on the substrate 4 to form a film on the substrate 4. After the film formation, the gas type B inside the reaction tube 2 is exhausted. By repeatedly supplying the gas, the atomic layers are formed on the substrate one by one.

  Since the gas used in the ALD process does not form a film alone, the water-cooled trap 10 provided in the exhaust gas system of the CVD processing furnace shown in FIG. 7 is not necessary in the exhaust gas system of the ALD processing furnace. However, it is necessary to provide a pipe heater 9 in the exhaust pipe 24 between the exhaust port 8 and the vacuum pump 11. The reason is that when the liquid organic raw material is vaporized and used as the gas raw material, when the organic raw material is cooled on the primary side (upstream side) of the vacuum pump 11, it is liquefied again, stays in the exhaust pipe, and is then supplied. There is a possibility that reaction by-products adhere to the exhaust pipe 24. Therefore, in order to prevent this, it is necessary to provide the pipe heater 9.

  By the way, in the exhaust gas system of FIG. 7 or FIG. 8, the exhaust pipe between the vacuum pump 11 and the abatement apparatus 12 may be very long depending on the equipment layout. This is because, when exhaust gas from a large number of semiconductor manufacturing apparatuses is commonly processed by a single abatement apparatus 12, there may be a semiconductor manufacturing apparatus installed at a relatively close distance to the abatement apparatus 12, This is because a semiconductor manufacturing apparatus installed at a long distance comes out.

  Even when the length of the exhaust pipe is long, there is no problem in the CVD furnace shown in FIG. 7 because no reaction by-products are attached to the exhaust pipes 22 and 23 by the water-cooled trap 10. However, there is a problem in the ALD processing furnace shown in FIG. This is because the gas type A and the gas type B may react in the secondary (downstream) exhaust pipe 23 of the vacuum pump 11. In the exhaust pipe 24 on the primary side of the vacuum pump 11, the gas is extracted by the vacuum pump 11 and the pressure becomes low, so there is almost no gas. Therefore, a plurality of gas species do not react. However, in the exhaust pipe 23 on the secondary side of the vacuum pump 11, the pressure is high, the extracted gas flows relatively slowly, and if the pipe length is long, it drifts into the exhaust pipe 23, so that it is extracted before and after. Among the plurality of gas species, the gas species extracted earlier catch up with the gas species extracted later, and both react.

  In order to prevent this, it is desirable to provide a heater over the entire length of the exhaust pipe. However, when the pipe becomes long, it is difficult to economically and expensively provide a heater over the entire length, The presence of the exhaust pipe 23 without a heater is inevitable. For this reason, reaction of a plurality of gas species occurs in the exhaust pipe 23 not provided with the heater, and the reaction by-products are cooled and solidified, and adhere to the exhaust pipe wall.

As described above, in the conventional substrate processing apparatus that exhausts while processing gas is alternately supplied to the processing chamber to process the substrate, the piping length of the secondary side exhaust pipe of the vacuum pump 11 becomes long, and the piping When the length becomes longer and a low temperature part occurs, a plurality of gas species react in the middle of the exhaust pipe, and further, in the low temperature part of the exhaust pipe, the reacted gas precipitates in the solid phase and deposits reaction byproducts, There was a risk of clogging the exhaust pipe. When the exhaust pipe is clogged, it is necessary to frequently perform maintenance such as stopping the substrate processing apparatus and cleaning the exhaust pipe.
It is also conceivable that a trap is provided between the vacuum pump 11 and the abatement apparatus 12, and the reacted gas is forcibly lowered in temperature by the trap and deposited and deposited on the solid phase. However, since the secondary side of the vacuum pump 11 is only operated by the discharging device on the factory side where the processing device is installed, the pressure becomes high and the gas stays on the upstream side of the trap. There is a risk of promoting the accumulation of by-products. In particular, the method of alternately supplying a plurality of reaction gases is different from the method of supplying a plurality of reaction gases at the same time, and does not react anytime and anywhere, so it is difficult to remove reaction products effectively depending on the trap. is there.

  An object of the present invention is to solve the above-mentioned problems of the prior art in an apparatus for processing a substrate by alternately supplying a plurality of reaction gases, and the length of the exhaust pipe on the secondary side of the exhaust means becomes longer. However, an object of the present invention is to provide a substrate processing apparatus capable of effectively suppressing clogging of an exhaust pipe due to reaction by-products, and saving resources and energy.

  The present invention includes a processing chamber for processing a substrate, a plurality of reactive gas supply means for alternately supplying a plurality of reactive gases to the processing chamber, a first exhaust pipe for exhausting the processing chamber, A substrate processing apparatus comprising: exhaust means for exhausting the processing chamber through the first exhaust pipe; and a second exhaust pipe for exhausting gas exhausted from the exhaust means. An inert gas supply means for supplying a high temperature inert gas to the two exhaust pipes is provided, and the high temperature inert gas is supplied from the inert gas supply means only when a recipe for supplying the reactive gas is executed. The substrate processing apparatus is characterized by being configured as described above.

When the high temperature inert gas is supplied from the inert gas supply means to the second exhaust pipe, the low temperature portion disappears from the second exhaust pipe. Therefore, even if a plurality of reaction gases react in the second exhaust pipe, the reaction gas does not deposit on the solid phase and adhere to the second exhaust pipe, and the second exhaust pipe caused by reaction by-products Clogging can be prevented.
Further, since the inert gas supply means supplies the high-temperature inert gas only when executing the recipe for supplying the reactive gas, the supply is performed at times other than when executing the recipe for supplying the reactive gas. Compared with what to do, the consumption of an inert gas and the energy for making an inert gas high temperature can be suppressed.

  Here, in the present invention, when the recipe for supplying the reaction gas is executed, the reaction by-product is likely to be deposited in the solid phase in at least the second exhaust pipe, and is inactive during that period. The heating time necessary for raising the temperature of the gas is added. It does not include time other than when the recipe is executed, for example, idle time when the substrate processing apparatus is powered on. The high temperature is a temperature at which a reaction byproduct generated by the reaction gas is vaporized.

  In the present invention, it is preferable to supply a high-temperature inert gas from a plurality of locations of the second exhaust pipe. When the high temperature inert gas is supplied from a plurality of locations of the second exhaust pipe, the reaction gas is effectively heated as compared with the case where the high temperature inert gas is supplied from a single location. Can be further prevented. In this case, since the supply amount of the inert gas is increased, the consumption amount of the inert gas and the energy suppressing effect for increasing the temperature of the inert gas are large.

  According to the present invention, in an apparatus for processing a substrate by alternately supplying a plurality of reaction gases, it is possible to effectively suppress clogging of the exhaust pipe due to reaction by-products even when the length of the exhaust pipe is increased. In addition, resource saving and energy saving can be achieved.

  The structure of the substrate processing apparatus of this invention is demonstrated using drawing. In the following description, a case where the substrate processing apparatus is applied to a vertical apparatus (hereinafter simply referred to as a processing apparatus) that performs ALD processing on a substrate will be described. FIG. 3 is an external perspective view of a processing apparatus applied to the present invention. This figure is drawn as a perspective view. FIG. 4 is a side view of the processing apparatus shown in FIG.

The processing apparatus according to the present invention inserts a pod (substrate storage container) 100 containing a wafer (substrate) 200 made of silicon or the like into the housing 101 from the outside, and vice versa. An I / O stage (holder holding member) 105 for dispensing is attached to the front surface of the housing 101, and a cassette shelf (mounting means) 109 for storing the inserted pod 100 is provided in the housing 101. It is laid. Further, an N ₂ purge chamber (airtight chamber) 102 serving as a loading / unloading space for a boat (substrate holding means) 217, which will be described later, is provided as a transfer area for the wafer 200. The N ₂ purge chamber 102 is hermetically sealed so that the inside of the N ₂ purge chamber 102 when processing the wafer 200 is filled with an inert gas such as N ₂ gas in order to prevent a natural oxide film on the wafer 200. It is a container.

As the pod 100 described above, the FOUP type is currently used in the mainstream, and the opening provided on one side surface of the pod 100 is closed with a lid (not shown) to isolate the wafer 200 from the atmosphere. The wafer 200 can be moved into and out of the pod 100 by removing the lid. A pod opener (opening / closing means) 108 is provided on the front side of the N ₂ purge chamber 102 so that the lid of the pod 100 is removed and the atmosphere in the pod communicates with the atmosphere of the N ₂ purge chamber 102. Yes. The pod 100 is transferred between the pod opener 108, the cassette shelf 109, and the I / O stage 105 by a cassette transfer machine 114. Air that has been cleaned by a clean unit (not shown) provided in the casing 101 is caused to flow in the transport space of the pod 100 by the cassette transfer device 114.

Inside the N ₂ purge chamber 102, a boat 217 for loading a plurality of wafers 200 in multiple stages, a substrate alignment device 106 for adjusting the position of the notch (or orientation flat) of the wafers 200 to an arbitrary position, and a pod opener 108 A wafer transfer machine (carrying means) 112 that carries the wafer 200 between the upper pod 100, the substrate alignment device 106, and the boat 217 is provided. Further, a processing furnace 202 for processing the wafer 200 is provided in the upper part of the N ₂ purge chamber 102, and the boat 217 is loaded into the processing furnace 202 by the boat elevator (lifting means) 115 or unloaded from the processing furnace 202. Can be loaded.

Next, the operation of the processing apparatus according to the embodiment will be described.
First, the pod 100 that has been transported from the outside of the housing 101 by an AGV (self-propelled transport vehicle) or an OHT (ceiling suspended transport device) is placed on the I / O stage 105. The pod 100 placed on the I / O stage 105 is directly transported onto the pod opener 108 by the cassette transfer device 114, or once stocked on the cassette shelf 109 and then transported onto the pod opener 108. The The pod 100 transferred to the pod opener 108 is removed from the pod 100 by the pod opener 108, and the internal atmosphere of the pod 100 is communicated with the atmosphere of the N ₂ purge chamber 102.

Next, the wafer 200 is taken out from the pod 100 in communication with the atmosphere of the N ₂ purge chamber 102 by the wafer transfer device 112. The taken-out wafer 200 is aligned so that a notch is determined at an arbitrary position by the substrate alignment apparatus 106, and after alignment, is charged into the boat 217 (wafer charge).

  When the charging of the wafer 200 to the boat 217 is completed, the furnace port shutter 116 of the processing chamber 201 is opened, and the boat 217 loaded with the wafer 200 is loaded by the boat elevator 115 (boat up).

  After loading, arbitrary processing is performed on the wafer 200 in the processing furnace 202 (process). After the processing, the wafer 200 and the pod 100 are housed in the casing 101 by boat down and wafer discharge in the reverse procedure described above. Paid out to the outside.

  First, a film forming process using the ALD method as an example of a process performed on a substrate such as a wafer performed in the embodiment of the present invention will be briefly described.

  In the ALD method, under one film formation condition (temperature, time, etc.), two kinds (or more) of raw material gases used for film formation are alternately supplied onto the substrate one by one, and one atomic layer unit. In this method, the film is adsorbed by using a surface reaction to form a film.

That is, for example, in the case of forming a SiN (silicon nitride) film, the chemical reaction to be used uses DCS (SiH ₂ Cl ₂ , dichlorosilane) as the gas species A and NH ₃ (ammonia) as the gas species B in the ALD method. High quality film formation is possible at a low temperature of 300 to 600 ° C. Further, the gas supply alternately supplies a plurality of types of reactive gases one by one. The film thickness control is controlled by the number of cycles of the reactive gas supply (for example, if the film forming speed is 1 kg / cycle, the process is performed 20 cycles when a 20 mm film is formed).

This will be specifically described with reference to FIGS.
FIG. 5 is a schematic configuration diagram of a vertical processing furnace constituting the processing apparatus according to the present embodiment, showing the processing furnace part in a vertical cross section, and FIG. 6 is a vertical substrate processing according to the present embodiment. It is a schematic structure figure of a furnace, and shows a processing furnace part in a cross section. A reaction tube 203 is provided as a reaction vessel for processing the wafer 200 as a substrate inside a heater 207 as a heating means, and the lower end opening of the reaction tube 203 is an O-ring as an airtight member by a seal cap 219 as a lid. The process furnace 202 is formed by at least the heater 207, the reaction tube 203, and the seal cap 219. A boat 217 as a substrate holding means is erected on the seal cap 219 via a quartz cap 218, and the quartz cap 218 serves as a holding body for holding the boat. Then, the boat 217 is inserted into the processing furnace 202. On the boat 217, a plurality of wafers 200 to be batch-processed are stacked in a multi-stage in the tube axis direction in a horizontal posture. The heater 207 heats the wafer 200 inserted into the processing furnace 202 to a predetermined temperature.

  The processing furnace 202 is provided with two gas supply pipes 232a and 232b as supply pipes for supplying a plurality of types, here two types of gases. Here, from the first gas supply pipe 232a, a buffer chamber 237 formed in the processing furnace 202, which will be described later, is further passed through a first mass flow controller 241a that is a flow control means and a first valve 243a that is an on-off valve. Through the second gas supply pipe 232b, a second mass flow controller 241b serving as a flow rate control unit, a second valve 243b serving as an on-off valve, a gas reservoir 247, and an on-off valve are supplied. The reaction gas is supplied to the processing furnace 202 through a third valve 243c, which is the gas supply unit 249 described later.

  The processing furnace 202 is provided with a gas exhaust pipe 231 that is an exhaust pipe for exhausting gas to the exhaust port 231a. The gas exhaust pipe 231 is connected to a vacuum pump 246 which is an exhaust means via a fourth valve 243d, and is evacuated. The fourth valve 243d is an open / close valve that can open and close the valve to stop evacuation / evacuation of the processing furnace 202, and further adjust the valve opening to adjust the pressure. Also, a second exhaust pipe 234 is provided on the secondary side of the vacuum pump 246, and the gas discharged from the vacuum pump 246 is exhausted directly into the atmosphere or, if necessary, through the abatement device 238 into the atmosphere. It is supposed to be.

  The arc-shaped space between the inner wall of the reaction tube 203 and the wafer 200 constituting the processing furnace 202 is a gas dispersion space along the loading direction of the wafer 200 on the inner wall above the lower part of the reaction tube 203. A buffer chamber 237 is provided, and a first gas supply hole 248 a that is a supply hole for supplying a gas is provided at the end of the wall adjacent to the wafer 200 in the buffer chamber 237. The first gas supply hole 248 a opens toward the center of the reaction tube 203. The first gas supply holes 248a have the same opening area from the lower part to the upper part, and are provided at the same opening pitch.

  At the end of the buffer chamber 237 opposite to the end where the first gas supply hole 248 a is provided, a nozzle 233 is also disposed along the stacking direction of the wafer 200 from the lower part to the upper part of the reaction tube 203. Has been. The nozzle 233 is provided with a second gas supply hole 248b which is a supply hole for supplying a plurality of gases. When the differential pressure between the buffer chamber 237 and the processing furnace 202 is small, the second gas supply hole 248b may have the same opening area and the same opening pitch from the upstream side to the downstream side. When the pressure is large, the opening area is increased from the upstream side toward the downstream side, or the opening pitch is reduced.

  In the present invention, by adjusting the opening area and opening pitch of the second gas supply holes 248b from the upstream side to the downstream side, first, there is a difference in the gas flow velocity from each of the second gas supply holes 248b, but the flow rate is A gas of approximately the same amount is ejected. Then, the gas ejected from each of the second gas supply holes 248b is ejected into the buffer chamber 237 and once introduced, and the flow velocity difference of the gas is made uniform.

  That is, in the buffer chamber 237, the gas ejected from each second gas supply hole 248b is ejected from the first gas supply hole 248a to the processing furnace 202 after the particle velocity of each gas is reduced in the buffer chamber 237. During this time, the gas ejected from each of the second gas supply holes 248b could be a gas having a uniform flow rate and flow velocity when ejected from each of the first gas supply holes 248a.

  Further, in the buffer chamber 237, the first rod-shaped electrode 269 that is a first electrode having an elongated structure and the second rod-shaped electrode 270 that is a second electrode are electrodes that are protective tubes that protect the electrode from the top to the bottom. One of the first rod-shaped electrode 269 and the second rod-shaped electrode 270 is connected to a high-frequency power source 273 via a matching device 272, and the other is grounded as a reference potential. It is connected to the. As a result, plasma is generated in the plasma generation region 224 between the first rod-shaped electrode 269 and the second rod-shaped electrode 270.

  The electrode protection tube 275 has a structure in which the first rod-shaped electrode 269 and the second rod-shaped electrode 270 can be inserted into the buffer chamber 237 while being isolated from the atmosphere of the buffer chamber 237. Here, if the inside of the electrode protection tube 275 has the same atmosphere as the outside air (atmosphere), the first rod-shaped electrode 269 and the second rod-shaped electrode 270 inserted into the electrode protection tube 275 are oxidized by the heating of the heater 207. Will be. Therefore, the inside of the electrode protection tube 275 is filled or purged with an inert gas such as nitrogen to keep the oxygen concentration sufficiently low to prevent oxidation of the first rod-shaped electrode 269 or the second rod-shaped electrode 270. A gas purge mechanism is provided.

  Further, a gas supply unit 249 is provided on the inner wall of the reaction tube 203 that is rotated about 120 ° from the position of the first gas supply hole 248a. The gas supply unit 249 is a supply unit that shares the gas supply species with the buffer chamber 237 when a plurality of types of gases are alternately supplied to the wafer 200 one by one in film formation by the ALD method.

  Similarly to the buffer chamber 237, the gas supply unit 249 also has third gas supply holes 248c which are supply holes for supplying gas at the same pitch at positions adjacent to the wafer, and a second gas supply pipe 232b is provided at the lower part. It is connected.

  When the differential pressure between the buffer chamber 237 and the processing furnace 202 is small, the third gas supply hole 248c may have the same opening area and the same opening pitch from the upstream side to the downstream side. If it is large, it is preferable to increase the opening area or reduce the opening pitch from the upstream side toward the downstream side.

  A boat 217 for loading a plurality of wafers 200 in multiple stages at the same interval is provided at the center of the reaction tube 203. This boat 217 can enter and exit the reaction tube 203 by a boat elevator mechanism (not shown). It has become. Further, in order to improve the uniformity of processing, a boat rotation mechanism 267 that is a rotation means for rotating the boat 217 is provided. By rotating the boat rotation mechanism 267, the boat 217 held by the quartz cap 218 is removed. It is designed to rotate.

The controller 121, which is a control means, includes first and second mass flow controllers 241a and 241b, first to fourth valves 243a, 243b, 243c, and 243d, a heater 207, a vacuum pump 246, a boat rotation mechanism 267, and are omitted in the drawing. Connected to the boat lifting mechanism, the high frequency power supply 273, and the matching unit 272, the flow rate adjustment of the first and second mass flow controllers 241a, 241b, the opening / closing operation of the first to third valves 243a, 243b, 243c, 4 valve 243d open / close and pressure adjustment operation, heater 207 temperature adjustment, vacuum pump 246 start / stop, boat rotation mechanism 267 rotation speed adjustment, boat elevating mechanism elevating operation control, high frequency power supply 273 power supply control, alignment Impedance control is performed by the device 272.

Next, an example of film formation by the ALD method will be described using an example of forming an SiN film using DCS and NH ₃ gas.

  First, the wafer 200 to be deposited is charged into the boat 217, and the boat 217 is up and loaded into the processing furnace 202. After carrying in, the following three steps are sequentially executed.

[Step 1]
In step 1, NH ₃ gas that requires plasma excitation and DCS gas that does not require plasma excitation are caused to flow in parallel. First, the first valve 243a provided in the first gas supply pipe 232a and the fourth valve 243d provided in the gas exhaust pipe 231 are both opened, and the first mass flow controller 241a is operated from the first gas supply pipe 232a. The NH ₃ gas whose flow rate has been adjusted is jetted from the second gas supply hole 248 b of the nozzle 233 to the buffer chamber 237, and the high frequency power supply 273 is passed through the matching unit 272 between the first rod-shaped electrode 269 and the second rod-shaped electrode 270. Then, high frequency power is applied to excite plasma of NH _3, and exhausted from the gas exhaust pipe 231 while being supplied to the processing furnace 202 as active species. When flowing NH ₃ gas as an active species by plasma excitation, the pressure in the processing furnace 202 is set to 10 to 100 Pa by appropriately adjusting the fourth valve 243d. The supply flow rate of NH ₃ controlled by the first mass flow controller 241a is 1000 to 10000 sccm. The time for exposing the wafer 200 to the active species obtained by plasma excitation of NH ₃ is 2 to 120 seconds. At this time, the temperature of the heater 207 is set to be 300 to 600 ° C. for the wafer. Since NH ₃ has a high reaction temperature, it does not react at the above-mentioned wafer temperature. Therefore, it is made to flow as an active species by plasma excitation. Therefore, the wafer temperature can be kept in a set low temperature range.

When NH ₃ is supplied as an active species by plasma excitation, the second valve 243b on the upstream side of the second gas supply pipe 232b is opened, the third valve 243c on the downstream side is closed, and the DCS Also let it flow. As a result, DCS is stored in a gas reservoir 247 provided between the second and third valves 243b and 243c. At this time, the gas flowing in the processing furnace 202 is an active species obtained by plasma exciting NH ₃ , and DCS does not exist.
Therefore, NH ₃ does not cause a gas phase reaction, NH ₃ became excited active species by the plasma reacts base film and the surface of the wafer 200.

[Step 2]
In Step 2, the first valve 243a of the first gas supply pipe 232a is closed to stop the supply of NH ₃ , but the supply to the gas reservoir 247 is continued. When a predetermined pressure and a predetermined amount of DCS accumulate in the gas reservoir 247, the second valve 243b on the upstream side is also closed, and the DCS is confined in the gas reservoir 247. Further, the fourth valve 243 d of the gas exhaust pipe 231 is kept open, and the processing furnace 202 is exhausted to 20 Pa or less by the vacuum pump 246, and residual NH ₃ is removed from the processing furnace 202. At this time, if an inert gas such as N ₂ is supplied to the processing furnace 202, the effect of eliminating residual NH ₃ is further enhanced. DCS is stored in the gas reservoir 247 so that the pressure is 20000 Pa or more. Further, the apparatus is configured such that the conductance between the gas reservoir 247 and the processing furnace 202 is 1.5 × 10 ⁻³ m ³ / s or more. Considering the ratio between the volume of the reaction tube 203 and the volume of the necessary gas reservoir 247 for this, in the case of the reaction tube 203 volume of 100 l (liter), it is preferably 100 to 300 cc. The reservoir 247 is preferably 1/1000 to 3/1000 times the volume of the processing chamber.

[Step 3]
In step 3, when exhaust of the processing furnace 202 is completed, the fourth valve 243d of the gas exhaust pipe 231 is closed to stop the exhaust. The third valve 243c on the downstream side of the second gas supply pipe 232b is opened. As a result, the DCS stored in the gas reservoir 247 is supplied to the processing furnace 202 at once. At this time, since the fourth valve 243d of the gas exhaust pipe 231 is closed, the pressure in the processing furnace 202 is rapidly increased to about 931 Pa (7 Torr). The time for supplying DCS was set to 2 to 4 seconds, and then the time for exposure to the increased pressure atmosphere was set to 2 to 4 seconds, for a total of 6 seconds. The wafer temperature at this time is 300 to 600 ° C. as in the case of supplying NH ₃ . By supplying DCS, NH ₃ and DCS on the base film react with each other to form a SiN film on the wafer 200. After the film formation, the third valve 243c is closed, the fourth valve 243d is opened, and the processing furnace 202 is evacuated to remove the gas after contributing to the film formation of the remaining DCS. At this time, if an inert gas such as N ₂ is supplied to the processing furnace 202, the effect of removing the remaining gas after contributing to the film formation of DCS from the processing furnace 202 is enhanced. Also, the second valve 243b is opened to start supplying DCS to the gas reservoir 247.

  Steps 1 to 3 are defined as one cycle, and this cycle is repeated a plurality of times to form a SiN film having a predetermined thickness on the wafer.

  In the ALD apparatus, the gas is adsorbed on the surface of the base film. The amount of gas adsorption is proportional to the gas pressure and the gas exposure time. Therefore, in order to adsorb a desired amount of gas in a short time, it is necessary to increase the gas pressure in a short time. In this respect, in the present embodiment, the DCS stored in the gas reservoir 247 is instantaneously supplied after the fourth valve 243d is closed, so the DCS pressure in the processing furnace 202 is rapidly increased. The desired amount of gas can be instantaneously adsorbed.

Further, in the present embodiment, while DCS is stored in the gas reservoir 247, NH ₃ gas, which is a necessary step in the ALD method, is excited as plasma to be supplied as active species and the processing furnace 202 is exhausted. As a result, no special steps are required to store the DCS.
Further, since the inside of the processing furnace 202 is exhausted to remove the NH ₃ gas, DCS is flowed, so that they do not react on the way to the wafer 200. The supplied DCS can be effectively reacted only with NH ₃ adsorbed on the wafer 200.

  After film formation on the wafer 200 is completed, the boat 217 is lowered and carried out of the processing furnace 202, and the wafer is discharged from the boat 217.

  By the way, as described above, in the ALD processing furnace for processing the wafer by supplying the reaction gas species A and B to the processing chamber alternately, as described above, the secondary side exhaust pipe of the vacuum pump 246 is used. In 234, a plurality of gas species react, and precipitate in the solid phase at the low temperature portion of the exhaust pipe 234, depositing reaction by-products, which may cause clogging of the exhaust piping. is there. For this reason, it has been necessary to frequently perform maintenance such as stopping the processing apparatus and cleaning the exhaust pipe. This tendency was conspicuous especially when the exhaust pipe 234 on the secondary side of the vacuum pump 246 is long.

  Therefore, in this embodiment, in order to avoid this, the exhaust pipe 234 provided on the secondary side of the vacuum pump 246 is provided with an inert gas supply means for supplying a high-temperature inert gas, A hot inert gas was supplied to prevent the formation of reaction by-products in the exhaust pipe 234. This will be described in detail below.

FIG. 1 shows a schematic diagram of an ALD processing furnace equipped with a gas exhaust system according to an embodiment.
The ALD processing furnace includes a reaction tube 203 that forms a processing chamber 201 for processing the wafer 200 therein, and a heater 207 that is provided on the outer periphery of the reaction tube 203 and heats the wafer 200. Also connected to the gas supply ports 232A and 232B as a plurality of reaction gas supply means for alternately supplying the reaction gas species A and B to the processing chamber 201, and the exhaust ports 231a and 231a for exhausting the processing chamber 201 The exhausted first exhaust pipe 231, the vacuum pump 246 as exhaust means for exhausting the processing chamber 201 through the first exhaust pipe 231, and the gas exhausted from the secondary side of the vacuum pump 246. The second exhaust pipe 234 and a detoxification device 238 for removing harmful components of the exhaust gas through the second exhaust pipe 234 are provided.

  A pipe heater 236 is attached to the first exhaust pipe 231 on the primary side of the vacuum pump 246. Specifically, a pressure control valve 243d is provided between the exhaust port 231a and the vacuum pump 246, and the pipe heater 236 heats the pipe from the exhaust port 231a to the pressure control valve 243d. It has become.

A heated gas supply unit 221 is provided as an inert gas supply means for supplying a high-temperature inert gas to the second exhaust pipe 234 on the secondary side of the vacuum pump 246, and the heated inert gas is exhausted to the second exhaust. It is supplied to the pipe 234 so that reaction by-products do not precipitate inside the second exhaust pipe 234. The heated gas supply unit 221 is connected to the second exhaust pipe 234 in the vicinity of the vacuum pump 246, and the heated inert gas, for example, N ₂ gas is supplied to the second exhaust pipe from one place in the vicinity of the vacuum pump 246. 234 is supplied. The N ₂ gas is supplied from one place near the vacuum pump 246 because it is the simplest and has the highest heating efficiency. Further, the heating gas supply unit 221 is configured such that when an AC power source (not shown) of the substrate processing apparatus is turned on, N ₂ gas heated to a high temperature flows from the heating gas supply unit 221 to the second exhaust pipe 234. It has become.

Here, as an example of ALD film formation conditions, when the source gas type is DCS, NH ₃ and the film formation temperature is 300 to 600 ° C., the heating gas supply unit 221 to the secondary side (downstream side) of the vacuum pump 246 is used. The temperature of the high-temperature N ₂ gas flowing through the second exhaust pipe 234 is, for example, about 150 to 160 ° C.

According to the above embodiment, the following effects can be obtained.
(1) The clogging of the second exhaust pipe due to reaction by-products can be effectively suppressed. In the wafer processing method by the ALD method, the inside of the first exhaust pipe 231 provided on the primary side of the vacuum pump 246 is Due to the discharging action of the vacuum pump 246, the pressure is relatively low and each reaction gas does not stay, so that no reaction is caused by mixing a plurality of reaction gases. However, in the second exhaust pipe 234 provided on the secondary side of the vacuum pump 246, only the exhaust action by the factory-side exhaust means in which the substrate processing apparatus is installed acts, so the pressure becomes relatively high, and a plurality of Although the reaction gas is alternately exhausted, the reaction of the reaction gases A and B occurs when the exhaust pipe length becomes longer. In addition, when the exhaust pipe length of the second exhaust pipe 234 becomes long and a low temperature portion exists, the reacted reaction gas is cooled, and reaction byproducts may adhere to the second exhaust pipe 234. Thus, when the piping of the second exhaust pipe 234 becomes long, reaction by-products generated by the reaction of a plurality of gases in the low temperature portion are deposited on the solid phase and deposited inside the piping. And the inside of the 2nd exhaust pipe 234 is obstruct | occluded at an accelerated speed by the reaction by-product deposited on a solid phase, the exhaust pressure error of the vacuum pump 246 will be caused, and the situation which must be maintained will generate | occur | produce.
However, as described above, according to the embodiment, the heated gas supply unit 221 is provided so that the heated inert gas is supplied to the second exhaust pipe 234 on the secondary side of the vacuum pump 246. Thus, no low temperature portion is generated in the second exhaust pipe 234. Therefore, even if the length of the exhaust pipe of the second exhaust pipe 234 is increased, a low temperature portion does not occur, so that there is no possibility that reaction by-products adhere to the second exhaust pipe 234 even in an ALD processing furnace. The clogging of the second exhaust pipe 234 due to reaction byproducts can be effectively suppressed.

(2) The exhaust capacity of the vacuum pump does not decrease.
If an inert gas is supplied to the first exhaust pipe 231 provided on the primary side of the vacuum pump 246, the exhaust capacity of the vacuum pump 246 is reduced, and the process chamber cannot be exhausted quickly, and prompt exhaust is required. In the ALD substrate processing, the throughput is remarkably lowered, which is not preferable. In addition, since the reaction gas used in the ALD process is not originally formed alone, the heated inert gas N ₂ is provided in the first exhaust pipe 231 on the primary side of the vacuum pump 246 where the reaction gas exists alone. There is no need to supply.
In this regard, in the embodiment, the inert gas is not supplied to the first exhaust pipe 231 on the primary side of the vacuum pump 246, and the second exhaust pipe 234 provided on the secondary side of the vacuum pump 246 is not supplied. Since the inert gas is supplied, the exhaust capability of the vacuum pump 246 does not decrease.

(3) Effective use of inert gas resources is planned.
If high-temperature inert gas N ₂ is supplied to the upstream side of the vacuum pump 246 to increase the temperature of the exhausted reaction gas, the pressure is low on the upstream side of the vacuum pump 246, so heat conduction is poor, Therefore, it is necessary to supply a large amount of N ₂ . If a large amount of inert gas N ₂ is supplied to the upstream side of the vacuum pump 246, the exhaust capability of the vacuum pump 246 is reduced as described above. In this respect as well, in the embodiment, the high-temperature inert gas N ₂ is supplied to the secondary side of the vacuum pump 246, which has a relatively high pressure and a high thermal conductivity to the exhaust gas. It is sufficient to supply the active gas N _2, and the inert gas resource can be effectively used.

By the way, when AC power is supplied to the substrate processing apparatus, the N ₂ gas heated to a high temperature flows from the heating gas supply unit 221 to the second exhaust pipe so that the N ₂ gas is constantly supplied. Although control is easy and existing software can be used as it is, more than necessary N ₂ gas is consumed in spite of the effective use of the resource (3) described above, and the N ₂ gas is heated to a high temperature. It is thought that the electric power for doing so will be consumed more than necessary. Therefore, such a problem can be solved if the high temperature inert gas N ₂ is supplied only when the recipe for supplying the reactive gas is executed.

FIG. 2 is a specific configuration diagram for realizing such a heated gas supply unit 221. The heated gas supply unit 221 includes a housing 300 provided with a thermal exhaust port 301. The housing 300, N ₂ gas outlet AC power terminal 302, N ₂ gas supply port 303 that N ₂ gas is supplied, N ₂ gas is connected to an AC power source as the power supply of the substrate processing apparatus is discharged 304, and drive coil circuit terminals 305a and 305b externally connected to the operation unit 120 in the substrate processing apparatus 103 are provided.

In the housing 300, an N ₂ gas line 310 connecting the N ₂ gas supply port 303 and the N ₂ gas discharge port 304 is provided. The N ₂ gas line 310 is provided with a manual valve HV, a regulator MP1 for adjusting the pressure, an air valve AV1, and a heat exchanger HT in order from the supply port 303 to the discharge port 304.

The air valve AV1 operates with air or N ₂ gas. Here, the operation is performed by supplying N ₂ gas to the air valve AV1 by opening / closing control of the electromagnetic valve EV. This N ₂ gas uses a part of the gas flowing through the N ₂ gas line 310. That is, a branch line 311 is connected between the manual valve HV of the N ₂ gas line 310 and the regulator MP1, and the branch line 311 is taken out via the regulator MP2.

The heat exchanger HT is adapted to heat the N ₂ gas heat received from the lamp LP of N ₂ for heating by heat exchange in N ₂ gas. The lamp LP is controlled so that the power corresponding to the output value from the temperature controller CTR based on the temperature sensor TC is supplied from the power regulator SSR and the N ₂ gas becomes the set temperature via the heat exchanger HT. The
The AC power terminal 302 is connected to the power regulator SSR via the relay contact AA. In addition, the AC power of the AC power source is converted to DC and connected to a DC power source 308 that outputs a DC voltage, for example, 24V, and the DC voltage output from the DC power source 308 is supplied to the solenoid valve EV via a relay contact AB. Connected.

A drive coil unit 306 internally connected to the drive coil circuit terminals 305a and 305b includes a relay winding AA for driving a relay contact AA for lamp on / off control and a relay contact AB for controlling a solenoid valve (for driving AV1). It consists of a parallel circuit with a relay winding AB to be driven. When a current flows through the relay winding AA, the relay contact AA is closed, a current flows through the power regulator SSR, the lamp LP is turned on, and the heat exchanger HT is activated. Thereby, the N ₂ gas flowing in the heat exchanger HT is heated to a predetermined temperature (about 150 to 160 ° C.). When a current flows through the relay winding AB simultaneously with the relay winding AA, the relay contact AB is closed, a DC voltage is applied to the electromagnetic valve EV, the electromagnetic valve EV is opened, and the N ₂ gas for operation passes through the branch line 311. Is supplied to the air valve AV1, and the air valve AV1 is opened. Thus N ₂ gas flows into N ₂ gas line 310, the high temperature of the N ₂ gas is discharged from the N ₂ gas exhaust port 304.

  The heating gas supply unit 221 described above is operated by an operation unit 120 provided in the substrate processing apparatus 103. The operation unit 120 includes a DC power supply (+ 24V) and a relay contact XX. This operation unit 120 is connected to the drive coil unit 306 in the heating gas supply unit 221 and constitutes an operation circuit in which DC power (+ 24V) is applied to the parallel circuit of the drive coils AA and AB via the relay contact XX. To do.

On the substrate processing apparatus 103 side, the substrate processing apparatus is operated by following various process recipes incorporated in advance by a main controller (not shown). For each process recipe, software for outputting an output signal for turning on / off the relay contact XX of the operation unit 120 is set. As a result, the high-temperature N ₂ gas is allowed to flow only in the recipe that causes the reactive gas that requires the heated gas supply unit 221 to flow.

Here, the recipe in which the reactive gas flows is, for example, a recipe that performs a series of operations from wafer charge → boat up → film formation → boat down → wafer discharge, and the period of the series of operations is during execution of the recipe. Become. During the execution of this recipe, high-temperature N ₂ gas is allowed to flow continuously. The reason is that it takes time (30 to 40 minutes) until the temperature of the N ₂ gas is stabilized at the target temperature (about 150 to 160 ° C.) after the lamp LP of the heating gas supply unit 221 is turned on. This is to ensure

As described above, the heating gas supply unit 221 according to the embodiment includes the operation unit 120, the drive coil unit 306, the relay contact AA for lamp on / off control, and the relay contact AB for electromagnetic valve (AV1 drive) control. Then, when AC power is supplied to the substrate processing apparatus 103 and the above-described soft output signal is output from the substrate processing apparatus 103, the N ₂ gas heating lamp LP is turned on, and N The air valve AV1 for _two gas supply is opened, and the high temperature N ₂ gas is allowed to flow only when a process recipe that requires high temperature N ₂ gas is executed. Therefore, AC power supply supply point immediately lamp LP is turned, air valve AV1 is opened as compared to (always hot N ₂ gas supply state) ones, energy saving of N ₂ gas, the power-saving lamp heating Can be achieved. Energy savings and power savings depend on the type of substrate processing equipment and the time from when AC power is supplied until recipe execution (idle time), for example, N ₂ consumption can be reduced by about 30-40% The power consumption can be reduced by about 30 to 40%. Therefore, the consumption amount of N _{2 and} the amount of electric power of the heating gas supply unit 221 can be greatly suppressed.

In the embodiment described above, the heated gas supply unit 221 is connected to the second exhaust pipe 234 in the vicinity of the vacuum pump 246, and heated inert gas, for example, N ₂ gas is supplied in the vicinity of the vacuum pump 246. From one place, the second exhaust pipe 234 is supplied. However, the present invention is not limited to this. High temperature inert gas may be supplied from a plurality of locations in the second exhaust pipe 234. According to this, even when the piping length of the second exhaust pipe 234 becomes long as in the case of supplying from one place, the inside of the second exhaust pipe 234 is effectively extended over the entire length of the second exhaust pipe 234. Can be heated. Therefore, the temperature inside the pipe does not decrease as the distance from the heated gas supply portion increases, and it is possible to effectively avoid the deposition of reaction by-products in the solid phase and precipitation inside the pipe. In particular, in such a case where a high-temperature inert gas is supplied from a plurality of locations, the N ₂ gas flow rate and the lamp power consumption increase, so that the N ₂ gas can be obtained by using the heating gas supply unit 221 described above. The advantage of reducing the consumption and power consumption is great.

  In the above-described embodiment, ALD has been described as a film forming method for alternately supplying a plurality of reactive gases. The present invention is not limited to this. For example, two or more kinds of reactive gases may be used for the formation. The present invention can also be applied to cyclic MOCVD (Metal Organic Chemical Vapor Deposition) in which four steps of membrane, exhaust, reforming, and exhaust are taken as one cycle and this is repeated a plurality of times.

It is the schematic of the processing furnace provided with the gas exhaust system which comprises the substrate processing apparatus by embodiment. It is a block diagram of the heating gas supply unit by embodiment. It is an external appearance perspective view of the processing apparatus applied to this invention. It is a side view of the processing apparatus shown in FIG. It is a schematic structure figure of a vertical type substrate processing furnace concerning an embodiment of the invention, and is a figure showing a processing furnace part with a vertical section. It is a schematic structure figure of a vertical type substrate processing furnace concerning an embodiment of the invention, and is a figure showing a processing furnace part in a cross section. It is a general exhaust gas system diagram using the CVD method. It is a general exhaust gas system diagram using the ALD method.

Explanation of symbols

200 wafer (substrate)
201 processing chambers 232A, 232B gas supply ports (reactive gas supply means)
221 Vacuum pump (exhaust means)
231 1st exhaust pipe 234 2nd exhaust pipe 221 Heating gas supply unit (inert gas supply means)

Claims (1)

A processing chamber for processing the substrate;
A plurality of reactive gas supply means for alternately supplying a plurality of reactive gases to the processing chamber;
A first exhaust pipe for exhausting the processing chamber;
An exhaust means for exhausting the processing chamber through the first exhaust pipe;
A second exhaust pipe for exhausting the gas exhausted from the exhaust means;
A substrate processing apparatus comprising:
Providing an inert gas supply means for supplying a high-temperature inert gas to the second exhaust pipe;
A substrate processing apparatus, wherein a high-temperature inert gas is supplied from the inert gas supply means only when a recipe for supplying the reactive gas is executed.

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