JP2015167157A - Semiconductor production apparatus, deposition method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress adhesion of particles to a substrate, when performing plasma processing of substrates stacked like a shelf in a vertical reaction tube.SOLUTION: A pair of particle collection electrodes 71, 71 are arranged on the outside of a reaction tube 12, so as to face a region where plasma is generated. During a deposition cycle for repeating a dichlorosilane gas supply step and a plasma of ammonia gas supply step a large number of times, while replacing the atmosphere in the reaction tube 12, a plus DC voltage is applied to the particle collection electrode 71, in parallel with the atmosphere replacement step following to the plasma of ammonia gas supply step.

Description

  The present invention relates to a semiconductor manufacturing apparatus, a film forming method, and a memory in which the film forming method is recorded, which performs a film forming process on a substrate held in a shelf shape by a substrate holder in a vertical reaction tube. It relates to the medium.

For example, as a device for depositing a thin film such as a silicon nitride (Si-N) film, a wafer boat (substrate holder) in which substrates such as semiconductor wafers (hereinafter referred to as “wafers”) are stacked in a shelf shape is used as a vertical reaction. 2. Description of the Related Art There is known a film forming apparatus that carries a film forming process by carrying it in a tube airtightly from below. A gas injector is provided in the reaction tube for supplying a silicon-based source gas (for example, dichlorosilane (DCS) gas) and a nitrogen-based reaction gas (for example, ammonia (NH ₃ ) gas) to each wafer. Yes. A pair of parallel electrodes for converting ammonia gas into plasma is provided at a position near the gas injector of ammonia gas (specifically, a position close to the gas injector outside the reaction tube).

  When the above-described silicon nitride film is formed in such a film forming apparatus, a so-called ALD method, which is a method of alternately supplying source gas and reactive gas plasma to each wafer, is used. When switching between the source gas and the reactive gas plasma, the atmosphere in the reaction tube is replaced by evacuating the reaction tube or purging with an inert gas. Therefore, mixing of the dichlorosilane gas and the ammonia gas plasma with each other is suppressed in the atmosphere.

  By the way, if particles are generated in the reaction tube during the formation of the thin film, if the particles adhere to the wafer, the yield is reduced. An exhaust port for exhausting the inside of the reaction tube is provided on one side (for example, the lower side) in the length direction in the reaction tube, so that when particles are generated on the other side (upper side) in the reaction tube, It is difficult to remove the particles only by forming a gas flow in the reaction tube. Patent Document 1 describes a technique in which a mesh electrode plate is disposed inside an exhaust pipe and particles are collected by the mesh electrode plate in a single wafer etching apparatus or thin film forming apparatus. . However, Patent Document 1 does not discuss particles generated in a specific thin film forming apparatus or a film forming apparatus that forms a film on a large number of wafers.

JP-A-11-112437

  The present invention has been made in view of such circumstances, and its purpose is to adhere particles to a substrate when performing a film forming process on a substrate stacked in a shelf in a vertical reaction tube. It is to provide a technology capable of suppressing the problem.

The semiconductor manufacturing apparatus of the present invention
In a semiconductor manufacturing apparatus for carrying out film formation processing by carrying a substrate holder holding a plurality of substrates in a shelf shape into a reaction tube made of vertical quartz,
A processing gas supply unit for supplying a processing gas to the substrate;
A conductive member for plasma to which high-frequency power is supplied in order to turn the processing gas supplied from the processing gas supply unit into plasma;
An electrode that is provided so as to face the space in the reaction tube through a dielectric member, and to which a voltage is applied to draw particles in the reaction tube to the dielectric member side by Coulomb force;
And an exhaust port for evacuating the inside of the reaction tube.

The film forming method of the present invention includes:
In a film forming method for carrying out a film forming process by carrying a substrate holder holding a plurality of substrates in a shelf shape into a reaction tube made of vertical quartz,
Supplying a processing gas from the processing gas supply unit to the substrate;
Supplying high-frequency power to a plasma conductive member, and converting the processing gas supplied from the processing gas supply unit into plasma;
Applying a voltage to an electrode provided to face the space in the reaction tube through a dielectric member, and drawing particles in the previous reaction tube to the dielectric member side by Coulomb force;
Evacuating the reaction tube;
And heating the substrate.
The storage medium of the present invention is
A storage medium storing a computer program that runs on a computer,
The computer program is characterized in that steps are set so as to implement the film forming method described above.

  In the present invention, when a film is formed on a substrate stacked in a shelf in a reaction tube, an electrode is provided so as to face the space in the reaction tube via a dielectric member, and a coulomb is applied to the electrode. A voltage for pulling particles by force is applied. Therefore, when particles are floating in the reaction tube, the particles are charged with the generation of plasma, so that the particles can be drawn into the dielectric member based on the potential difference between the particles and the electrodes.

It is a longitudinal cross-sectional view which shows an example of the semiconductor manufacturing apparatus of this invention. It is a cross-sectional top view which shows the said semiconductor manufacturing apparatus. It is a schematic diagram which shows an example of the sequence performed by the film-forming process in the said semiconductor manufacturing apparatus. It is a schematic diagram which shows the behavior of the floating particle which generate | occur | produces in the said film-forming process. It is a schematic diagram which shows the behavior of the said floating particle. It is a cross-sectional top view which shows the other example of the said semiconductor manufacturing apparatus. It is a cross-sectional top view which shows the other example of the said semiconductor manufacturing apparatus. It is a cross-sectional top view which shows another example of the said semiconductor manufacturing apparatus. It is a cross-sectional top view which shows another example of the said semiconductor manufacturing apparatus. It is a cross-sectional top view which shows the other example of the said semiconductor manufacturing apparatus. It is a cross-sectional top view which shows the other example of the said semiconductor manufacturing apparatus. It is a longitudinal cross-sectional view which shows the other example of the said semiconductor manufacturing apparatus. It is a cross-sectional top view which shows the other example of the said semiconductor manufacturing apparatus. It is a longitudinal cross-sectional view which expands and shows a part of other example of the said semiconductor manufacturing apparatus. It is a longitudinal cross-sectional view which shows the other example of the said semiconductor manufacturing apparatus. It is a schematic diagram which shows an example of the behavior of the floating particle collected with the said semiconductor device.

  An example of an embodiment of a semiconductor manufacturing apparatus according to the present invention will be described with reference to FIGS. This semiconductor manufacturing apparatus is configured to form a thin film by an ALD method in which reaction products are alternately supplied to a wafer W and a reaction product is stacked by alternately supplying a source gas and a reaction gas that react with each other. This is a batch type semiconductor manufacturing apparatus that collectively performs film formation on the wafer W.

  As shown in FIGS. 1 and 2, the semiconductor manufacturing apparatus includes a wafer boat 11 on which a large number of, for example, 150 wafers W are stacked in a shelf shape, and the wafer boat 11 is stored in an airtight manner with respect to the wafers W. And a reaction tube 12 that collectively performs the film forming process. The wafer boat 11 and the reaction tube 12 are made of dielectric members, in this example, quartz. A substantially cylindrical heating furnace main body 14 having an opening on the lower surface side is provided outside the reaction tube 12, and a heater 13 as a heating mechanism is disposed on the inner wall surface of the heating furnace main body 14 in the circumferential direction. ing. The wafer boat 11 is configured to be movable up and down by a boat elevator (not shown) together with a lid 25 that hermetically opens and closes the lower open end of the reaction tube 12 (more specifically, a manifold 18 described later). In FIG. 1, 16 is a base plate, 26 is a heat insulator, 27 is a rotating shaft, and 28 is a drive unit such as a motor. In FIG. 1, the heating furnace main body 14, the heater 13, and the base plate 6 are partially cut out.

  As shown in FIG. 1 and FIG. 2, the reaction tube 12 has a double tube structure of an outer tube 12a and an inner tube 12b housed in the outer tube 12a, and is a generally cylindrical shape whose upper and lower surfaces are open. It is airtightly supported from below by a manifold 18 made of a shaped metal. As shown in FIG. 2, the portion on one end side (front side) of the inner tube 12b when viewed in a plane swells outward along the length direction of the inner tube 12b, and forms the plasma generation region 12c. Therefore, the outer peripheral portion of the plasma generation region 12c protrudes outward from the outer tube 12a. In other words, the plasma generation region 12c is formed by opening a part of the wall surface of the outer tube 12a and the inner tube 12b in a slit shape in the vertical direction, and an opening end of a substantially box-shaped quartz member opened on the wafer boat 11 side and It is configured by welding the outer wall surface to the openings on the side surfaces of the inner tube 12b and the outer tube 12a, respectively.

In the plasma generation region 12c, an ammonia gas nozzle 51a which is a processing gas supply unit (gas injector) extending along the length direction of the wafer boat 11 is accommodated. The lower end portion of the ammonia gas nozzle 51a hermetically penetrates the inner wall surface of the reaction tube 12 constituting the plasma generation region 12c and is connected to an ammonia gas supply source 55a. As shown in FIG. 1, the end of the ammonia gas nozzle 51a on the side of the supply source 55a branches at an intermediate position and is connected to a supply source 55c of a purge gas such as nitrogen (N ₂ ) gas.

  As shown in FIG. 2, on the outside of the plasma generation region 12c (outside of the reaction tube 12), the plasma generation region 12c is sandwiched from the left and right in order to turn the ammonia gas supplied from the ammonia gas nozzle 51a into plasma. For example, a pair of plasma generating electrodes 61 and 61 made of a conductive member such as Inconel (nickel (Ni) alloy) are provided. Each of the plasma generating electrodes 61 and 61 is formed so as to extend along the length direction of the wafer boat 11 and is disposed at a position close to the plasma generating region 12c. The plasma generating electrodes 61 and 61 are located on the radially inner side of the reaction tube 12 with respect to the ammonia gas nozzle 51a as viewed in a plan view. The plasma generating electrode 61 is connected to a high frequency power source 64 having a frequency and output power of 13.56 MHz and 1 kW, for example, via a switch unit 62 and a matching unit 63, respectively. That is, the high frequency power supply 64 is connected to one plasma generation electrode 61 of the pair of plasma generation electrodes 61, 61, and the other plasma generation electrode 61 is grounded. The plasma generating electrodes 61, 61 are plasma conductive members.

  In addition, on the back side of the plasma generating electrodes 61 and 61 when viewed from the wafer boat 11, conductive members (in this example, a metal such as the nickel alloy described above) are used to sandwich the plasma generating region 12c from both left and right sides. A pair of configured particle collecting electrodes 71 and 71 are arranged. Therefore, these particle collection electrodes 71 and 71 are located on the outer side in the radial direction of the reaction tube 12 with respect to the ammonia gas nozzle 51a when seen in a plan view. The particle collecting electrodes 71 and 71 are for collecting floating particles (particles) generated in the plasma generation region 12 c and are formed to extend along the length direction of the wafer boat 11. And is arranged so as to be close to the plasma generation region 12c. Accordingly, the particle collecting electrodes 71 and 71 are arranged so as to face a processing region to which ammonia gas is supplied via a dielectric member (quartz member constituting the reaction tube 12).

  A positive (positive) terminal of a DC power source 73 is connected to each of the particle collecting electrodes 71 and 71 via a switch unit 72. In this example, the DC power source 73 is configured so that a positive voltage of 0 V to 1000 V can be applied to each of the particle collecting electrodes 71 and 71.

  As shown in FIG. 2, a source gas nozzle for supplying source gas containing silicon, in this example, dichlorosilane (DCS) gas, on both the left and right sides when viewed from the plasma generation region 12c at a position close to the wafer boat 11. 51b and 51b are arranged. These source gas nozzles 51b and 51b extend along the length direction of the wafer boat 11 and merge with each other at the lower end position. The source gas nozzles 51b and 51b pass through the inner wall surface of the reaction tube 12 in an airtight manner to the source gas supply source 55b. It is connected. In FIG. 1, reference numeral 52 denotes a gas discharge port, which is formed for each mounting position of each wafer W.

Further, as shown in FIG. 1, a supply of a cleaning gas such as hydrogen fluoride (HF) gas or fluorine (F ₂ ) gas is provided on the inner wall surface of the reaction tube 12 in the vicinity of the through positions of the gas nozzles 51a and 51b. A cleaning gas nozzle 51c extending from the source 55d is inserted in an airtight manner. The tip of the cleaning gas nozzle 51 c is opened at a position below the wafer boat 11. In FIG. 1, 53 is a valve, and 54 is a flow rate adjusting unit. In FIG. 2, the cleaning gas nozzle 51c is not shown.

  As shown in FIGS. 1 and 2, a substantially circular exhaust port 17 is formed in a portion of the inner tube 12b facing the plasma generation region 12c. The exhaust port 17 extends in the vertical direction. For example, they are arranged at equal intervals in a plurality of places. Further, as shown in FIG. 2, an exhaust port 21 made of quartz is formed at the position where the outer tube 12a is spaced apart from the plasma generation region 12c to the side, as shown in FIG. Therefore, it can be said that the exhaust port 21 forms a part of the reaction tube 12. A flange portion 21a made of, for example, stainless steel is airtightly fixed to the exhaust port 21 with, for example, a bolt (not shown). A vacuum pump 24, which is a vacuum exhaust mechanism, is connected to an exhaust path 22 extending from the flange portion 21a via a pressure adjusting unit 23 such as a rose fly valve. In FIG. 1, for convenience of illustration, the exhaust port 21 and the flange portion 21a are drawn at positions facing the plasma generation region 12c.

  As shown in FIG. 1, the semiconductor manufacturing apparatus is provided with a control unit 100 including a computer for controlling the operation of the entire apparatus, and a film forming process described later is stored in the memory of the control unit 100. Stores a program for performing This program is installed in the control unit 100 from the storage unit 101 which is a storage medium such as a hard disk, a compact disk, a magneto-optical disk, a memory card, and a flexible disk.

  Next, the operation of the above embodiment will be described. Here, in the reaction tube 12, batch-type film formation processing for a plurality of wafers W has already been performed a plurality of times, and accordingly, the inner wall surface of the reaction tube 12 (specifically, the inner tube 12 b) and the surface of the wafer boat 11. In this case, a silicon nitride film as a reaction product is attached as an attachment. The inside of the reaction tube 12 is set at a lower temperature, for example, 300 ° C. than the film forming temperature (for example, 500 ° C.) at which the wafer W is formed. Therefore, the adhering matter is removed from the inner wall surface of the reaction tube 12 and the surface of the wafer boat 11 due to the difference in thermal expansion and contraction rate with the reaction tube 12 and the wafer boat 11 as the temperature rises and falls in the reaction tube 12. It is easy to release.

  Under such circumstances, the wafer boat 11 loaded with unprocessed wafers W is airtightly carried into the reaction tube 12 and the reaction tube 12 is evacuated as shown in FIG. t0). Further, the heater 13 is energized so that the inside of the reaction tube 12 reaches the film forming temperature. Next, the pressure adjusting unit 23 (opening degree of the butterfly valve) is set so that the inside of the reaction tube 12 has a processing pressure when performing the film forming process, and as shown in FIG. A dichlorosilane gas is supplied into the inside (t1). When this dichlorosilane gas comes into contact with the surface of each wafer W, components of the dichlorosilane gas are adsorbed on the surface of the wafer W to form an adsorption layer. This adsorption layer is formed not only on the surface of the wafer W but also on the inner wall surface of the reaction tube 12 and the surface of the wafer boat 11. FIG. 3 shows a time chart for each step of supplying each gas and plasma, replacing the atmosphere in the reaction tube 12 and collecting particles, and whether each step is performed in each chart. (On / Off) is shown, and changes in gas flow rate and displacement are omitted.

  Subsequently, after the supply of dichlorosilane gas is stopped, the atmosphere in the reaction tube 12 is replaced as shown in FIG. 3C (t2). Specifically, after the reaction tube 12 is evacuated, a purge gas is supplied into the reaction tube 12. Next, the supply of the purge gas is stopped, and the inside of the reaction tube 12 is set to the processing pressure. Then, high-frequency power is supplied to the plasma generating electrode 61, and as shown in FIG. 3B, ammonia gas is supplied from the ammonia gas nozzle 51a to the plasma generating region 12c (t3).

  When the ammonia gas reaches the region between the plasma generating electrodes 61 and 61 or reaches a position in the vicinity of the region, the ammonia gas is converted into plasma by high-frequency power supplied between the plasma generating electrodes 61 and 61, and is ionized. And active species such as radicals. When this active species contacts the aforementioned adsorption layer on the surface of the wafer W, the adsorption layer is nitrided to form a reaction layer made of silicon nitride. Accordingly, the adsorption layer formed on the inner wall surface of the reaction tube 12 and the surface of the wafer boat 11 is also nitrided to form a reaction layer.

  Here, when the active species generated from the ammonia gas come into contact with the inner wall surface of the reaction tube 12, the adhering matter adhering to the inner wall surface is detached from the inner wall surface to become suspended particles (particles) 1. Alternatively, the quartz member itself constituting the reaction tube 12 may be etched by ions, and may be detached from the reaction tube 12 as the suspended particles 1.

  Then, in the ammonia gas plasma (plasma generation region 12c), as shown in FIG. 4, positive ions and electrons are generated in addition to neutral particles such as electrically neutral radicals. These electrons are negatively charged and are lighter and smaller than positive ions (the collision cross section is small). Accordingly, in the electric field between the plasma generating electrodes 61 and 61, electrons move at a high speed, while positive ions do not move so much. That is, electrons have a longer mean free path than positive ions. Therefore, the floating particles 1 floating in the plasma generation region 12c collide with more electrons than the positive ions, so that the floating particles 1 are negatively charged.

  Thereafter, as shown in FIGS. 3B and 3C, the power supply to the plasma generating electrodes 61 and 61 and the supply of the ammonia gas are stopped, and the vacuum exhaust and the supply of the purge gas in the reaction tube 12 are stopped. In this order, the atmosphere in the reaction tube 12 is replaced. In parallel with the step of replacing the atmosphere in the reaction tube 12, dust collection (removal) of the suspended particles 1 floating in the reaction tube 12 is performed. Specifically, as shown in FIG. 3D, a positive DC voltage of 0 V to 1000 V is applied to the particle collecting electrodes 71, 71 (t4).

  As described above, since the suspended particles 1 are negatively charged, as shown in FIG. 5, the suspended particles 1 are attracted to a positive charge (positive electrostatic field) by a Coulomb force, and are supplied with a direct current power source. The plasma generation region 12c flows toward the particle collecting electrode 71 to which 73 is connected. Then, it collides with the inner wall surface of the reaction tube 12 (inner tube 12b) interposed between the particle collecting electrode 71 and the plasma generation region 12c and adheres to the inner wall surface. That is, when a positive DC voltage is applied to the particle collecting electrode 71, the reaction tube 12 is made of a dielectric member. Therefore, on the inner wall surface of the reaction tube 12 adjacent to the particle collecting electrode 71, The part on the collecting electrode 71 side is negatively charged due to dielectric polarization, while the part on the floating particle 1 side (inside the reaction tube 12) is positively charged. Therefore, the suspended particles 1 in the reaction tube 12 are attracted to the inner wall surface of the reaction tube 12 by electrostatic force and adhere (adsorb) to the inner wall surface. Since the suspended particles 1 are thus electrically adsorbed on the inner wall surface of the reaction tube 12, the suspended particles 1 remain in the reaction tube 12 even if power supply to the particle collecting electrode 71 is stopped in the subsequent process. Continue to adsorb to the inner wall. In FIG. 5, for convenience of illustration, the plasma generating electrode 61 is also drawn together with the particle collecting electrode 71.

  Thereafter, as shown in FIGS. 3C and 3D, power supply to the particle collecting electrode 71 is stopped and supply of the purge gas is stopped (t5). Thus, the dichlorosilane gas supply process, the atmosphere replacement process in the reaction tube 12, the ammonia gas plasma supply process, the atmosphere replacement process in the reaction tube 12, and the suspended particle 1 dust collection process described above. The film-forming cycle consisting of is repeated many times. By these film forming cycles, the above-described reaction layers are stacked in multiple layers to form a thin film made of silicon nitride.

  Thereafter, after the wafer boat 11 is taken out from the reaction tube 12 and before the film forming process for the subsequent unprocessed wafer W is started, or after batch processing for each wafer W is performed a plurality of times, the reaction tube 12 is cleaned. Specifically, an empty wafer boat 11 (with no wafers W loaded thereon) is carried into the reaction tube 12 in an airtight manner, and the reaction tube 12 is set to a temperature lower than the film formation temperature (eg, 350 ° C.). At the same time, a cleaning gas is supplied into the reaction tube 12. In the reaction tube 12, the floating product 1 attached to the inner wall surface of the reaction tube 12 by feeding power to the particle collecting electrode 71 is etched together with the reaction product formed on the inner wall surface of the reaction tube 12 by the film forming process. And exhausted toward the exhaust port 21.

  According to the above-described embodiment, when performing the film forming process on the wafer W using the plasma, the particle collecting electrode 71 is provided at a position facing the processing region via the reaction tube 12, and this particle capturing is performed. A positive DC voltage is applied to the collecting electrode 71. Therefore, the floating particles 1 can be collected on the inner wall surface of the reaction tube 12 by utilizing the fact that the floating particles 1 in the plasma are negatively charged. Therefore, since the adhesion of the suspended particles 1 to the wafer W can be suppressed, it is possible to suppress a decrease in yield.

  Here, since the exhaust port 21 is provided in the lower region of the reaction tube 12, the gas flow tends to stay in the upper region inside the reaction tube 12. For this reason, in the upper region, the wafer flows. Suspended particles 1 are likely to adhere to W. On the other hand, since the particle collecting electrode 71 is provided along the length direction of the reaction tube 12, the suspended particles 1 can be collected along the length direction of the reaction tube 12.

  And since the process of collecting the suspended particles 1 is performed in parallel with a part of the film forming cycle in the ALD method (replacement process of the atmosphere in the reaction tube 12), in order to collect the suspended particles 1 A decrease in throughput can be suppressed as compared to a case where a process different from the film formation cycle is newly provided. In addition, the step of collecting the floating particles 1 is separated from the step of supplying the dichlorosilane gas or ammonia gas, so that the film forming process is not adversely affected.

Furthermore, in the present invention, it has been found that a large amount of suspended particles 1 are generated immediately after plasma generation, and that the amount of generated suspended particles 1 increases as the high frequency power supplied to the plasma generating electrode 61 is increased. The suspended particles 1 are collected immediately after the occurrence of. Therefore, the suspended particles 1 can be collected before the suspended particles 1 are scattered. Therefore, it can be said that the present invention is a technique having extremely high affinity with the ALD method in which film formation is performed by alternately supplying plasmas of dichlorosilane gas and ammonia gas that react with each other.
In addition, the suspended particles 1 are collected on the inner wall surface of the reaction tube 12, and therefore the suspended particles 1 can be removed by a normal process of cleaning the inner wall surface. There is no need to provide a process.

  Next, another embodiment of the present invention will be described. FIG. 6 shows that the particle collecting electrode 71 is provided on the back side of the plasma generating electrodes 61 and 61 when viewed from the wafer boat 11, and the plasma generating electrodes 61 and 61 are interposed via the wafer boat 11. In this example, they are arranged at positions facing each other. That is, the particle collecting electrode 71 is provided outside the outer tube 12a at a position close to the exhaust port 17 in the inner tube 12b. Also in this example, the film forming process and the removal of the suspended particles 1 are performed by the same sequence as the above-described example.

  FIG. 7 shows an example in which the particle collecting electrode 71 is arranged at a position close to (opposed to) the exhaust port 17 of the inner tube 12b between the inner tube 12b and the outer tube 12a. The particle collecting electrode 71 is covered in the length direction by a protective tube 81 made of a dielectric member such as quartz in order to prevent deterioration (oxidation) due to the cleaning gas, and is passed through the inner wall surface of the outer tube 12a. And inserted into the reaction tube 12 in an airtight manner. Accordingly, also in this example, the particle collecting electrode 71 is disposed so as to face the processing region via the dielectric member (the protective tube 81 and the inner tube 12b), and the same operation and An effect is obtained.

  FIG. 8 shows an example in which the particle collecting electrode 71 covered with the protective tube 81 is disposed at a position close to the exhaust port 21 between the inner tube 12b and the outer tube 12a. Specifically, one of the pair of particle collecting electrodes 71, 71 is arranged on the left side of the exhaust port 21 when the particle boat 71 is viewed from the exhaust port 21. The other particle collecting electrode 71 is arranged on the right side of the exhaust port 21.

  Further, FIG. 9 shows an example in which a plurality of particle collecting electrodes 71 are arranged in the circumferential direction in a region between the inner tube 12b and the outer tube 12a. That is, a plurality of particle collecting electrodes 71 in this example, seven in this example, are arranged so as to be equally spaced from each other, and each of these seven particle collecting electrodes 71 is provided with a DC power source 73. They are connected via the switch unit 72. In this way, an electric field is formed from each particle collecting electrode 71 toward the outside of the particle collecting electrode 71. In FIG. 9, you may arrange | position the electrode 71 for particle collection on the outer side of the outer tube | pipe 12a.

  In each of the examples described above, the timing of applying a positive DC voltage to the particle collecting electrode 71 is set to a time zone that overlaps with the replacement step in the reaction tube 12 subsequent to the generation of the ammonia gas plasma. The particle collecting electrode 71 may be supplied with power during the film forming cycle. That is, even if a positive DC voltage is applied to the particle collecting electrode 71 after the wafer boat 11 loaded with unprocessed wafers W is loaded into the reaction tube 12 and the film forming process is completed. good. In this case, since the suspended particles 1 are quickly collected when the suspended particles 1 are generated, it is possible to further suppress the yield reduction. In collecting the suspended particles 1 even when the ammonia gas plasma is generated in this way, in the configuration of FIG. 2 described above, a region where a positive DC voltage is applied to the plasma is a wafer boat. Since it is located on the opposite side to 11, it can suppress that the said area | region has a bad influence on plasma.

  FIG. 10 shows an example in which the plasma generating electrode 61 is also used as the particle collecting electrode 71. That is, the matching unit 63, the high frequency power source 64, and the DC power source 73 are connected to one of the pair of plasma generating electrodes 61, 61. Between the one plasma generating electrode 61 and the matching unit 63 and the DC power source 73, the one plasma generating electrode 61 can be switched between the matching unit 63 side and the DC power source 73 side. A switch unit 82 is provided. The other of the pair of plasma generating electrodes 61, 61 is grounded.

  In this example, when the ammonia gas plasma is generated, the switch unit 82 is switched to the high frequency power source 64 (matching unit 63) side, while when the suspended particles 1 are collected, the switch unit 82 is switched to the DC power source 73 side. Can be switched. Therefore, the region where the suspended particles 1 that are negatively charged due to the generation of plasma and the region where the positive DC voltage is applied overlap each other, so that the suspended particles 1 can be collected well. Further, since it is not necessary to provide the particle collecting electrodes 71, 71, it is advantageous in terms of space.

  Further, FIG. 11 shows that one of the pair of plasma generating electrodes 61, 61 is connected to one plasma generating electrode 61 via a matching unit 63, and the other plasma generating electrode 61 is An example is shown in which the switch unit 72 is configured to be switchable between a DC power source 73 and ground. Therefore, in this example, when the ammonia gas is turned into plasma, the switch unit 62 is turned on and the switch unit 72 is switched to the ground side. On the other hand, when the suspended particles 1 are collected, the switch unit 62 is turned off and the switch unit 72 is switched to the DC power source 73 side. Even if it is such a structure, the effect similar to the above-mentioned example is acquired.

  Next, FIGS. 12 and 13 show an example in which the reaction tube 12 is configured as a single tube type. Specifically, the substantially cylindrical reaction tube 12 whose bottom surface is open is hermetically supported by a manifold 18 made of a dielectric member such as quartz. The gas nozzles 51a to 51c are housed in the reaction tube 12 through the manifold 18 in an airtight manner. The exhaust port 21 is also formed in the manifold 18 and is made of quartz in the same manner as the manifold 18. In FIGS. 12 and 13, members having the same configurations as those in FIGS. 1 and 2 described above are denoted by the same reference numerals and description thereof is omitted. Further, in FIG. 12, drawing of the heating furnace main body 14 and the like is omitted.

Further, in this example, the particle collecting electrodes 71 and 71 are arranged on the back side of the plasma generating electrodes 61 and 61 when viewed from the wafer boat 11 so as to correspond to the above-described FIGS. Yes. In FIG. 12, reference numeral 91 denotes a substantially disk-shaped top plate made of quartz provided between the ceiling surface of the reaction tube 12 and the wafer boat 11, and the outer surface of the top plate 91 is the inner wall of the reaction tube 12. Are welded over the circumferential direction. Thus, even when the reaction tube 12 is configured as a single tube type, the same effects as those of the above-described examples can be obtained.
Also when this single tube type reaction tube 12 is used, the particle collecting electrode 71 may be arranged as shown in FIGS. 6 and 8 to 11 described above.

FIG. 14 shows an example in which the particle collecting electrodes 71, 71 are arranged so as to sandwich the exhaust port 21. That is, as shown in FIGS. 12 and 13, the exhaust port 21 is made of the same material (quartz) as the reaction tube 12. Therefore, when viewed from the particle collecting electrodes 71 and 71 arranged so as to sandwich the exhaust port 21, the wafer W is placed on the wafer boat 11 side via the manifold 18 and the reaction tube 12 both made of quartz. The processing areas to be dealt with face each other. By providing the particle collection electrodes 71 and 71 in this way, the suspended particles 1 flowing toward the exhaust port 21 can be collected.
1 and FIG. 2 in which the reaction tube 12 is configured as a double tube, the particle collecting electrodes 71 and 71 may be disposed so as to sandwich the exhaust port 21.

  FIG. 15 shows an example in which, for example, a particle collecting electrode 71 configured in a substantially plate shape is disposed on a top plate 91. That is, as already described, the suspended particles 1 are more likely to stay in the upper region in the reaction tube 12 than in the lower region. Therefore, in this example, a particle collecting electrode 71 is arranged on the top plate 91 in order to collect the suspended particles 1 staying in the upper region. Accordingly, the suspended particles 1 are adsorbed on the lower surface of the top plate 91 made of quartz, and the same effects as those of the above-described examples can be obtained. In this way, when the particle collecting electrode 71 is disposed on the upper side of the wafer boat 11, it may be disposed at a position spaced upward from the reaction tube 12.

Further, instead of disposing the particle collecting electrode 71 on the top plate 91, that is, instead of providing it on the upper side of the wafer boat 11, the particle collecting electrode 71 is disposed on the lid 25, and the wafer is collected. The suspended particles 1 falling from the boat 11 side may be collected. In this case, a protective tube 81 made of quartz is provided so as to cover the particle collecting electrode 71. In addition, even when the reaction tube 12 is configured as a double tube as shown in FIGS. 1 and 2, the particle collecting electrode 71 may be disposed on the upper side or the lower side in the reaction tube 12.
The particle collecting electrode 71 may be formed in a mesh shape, for example, when stored in the protective tube 81.

  Further, when collecting the suspended particles 1, it is performed in parallel with at least a part of the film formation cycle in the ALD method, but the film formation cycle is temporarily stopped to collect the suspended particles 1. May be. Specifically, after the process of supplying the plasma of ammonia gas as described in detail above, the supply of ammonia gas and the power supply to the high-frequency power source 64 are stopped, and the exhaust gas and purge gas in the reaction tube 12 are stopped. Electric power is supplied to the particle collecting electrode 71 without supply. Thereafter, power supply to the particle collecting electrode 71 is stopped, and then the exhaust gas and purge gas in the reaction tube 12 are supplied, and the subsequent film formation cycle is performed.

  Furthermore, in each of the examples described above, the ALD method in which the source gas and the plasma of the reactive gas are alternately supplied to the wafer W has been described. However, the CVD (Chemical Vapor) that simultaneously supplies the source gas and the plasma to the wafer W is described. A thin film may be formed by a deposition method. In this case, a positive DC voltage is applied to the particle collecting electrode 71 during the film forming process.

  The plasma treatment described above may be a process of forming a silicon oxide (Si—O) film using a silicon-based source gas and oxygen gas plasma. Further, when the ammonia gas is turned into plasma, instead of the CCP (capacitive coupling) plasma that forms an electric field between the pair of plasma generating electrodes 61, 61, the plasma generating electrode 61 is wound in a coil shape, and the ICP (Inductive coupling) Plasma may be generated.

  The DC voltage applied to the particle collecting electrode 71 may be a negative DC voltage. In this case, the positively charged floating particles 1 are collected. That is, for example, a plasma at a position separated from the inner wall surface of the reaction tube 12 and not affected by the inner wall surface is referred to as “bulk plasma”. 1 is negatively charged. On the other hand, in the vicinity of the inner wall surface, a sheath region 120 is formed as shown in FIG. 16, and in this sheath region 120, as shown in the lower part of FIG. Yes. Therefore, the suspended particles 1 generated in the bulk plasma are quickly adsorbed on the inner wall surface of the reaction tube 12, so that they pass through the sheath region 120 and reach the inner wall surface, but are generated in the one sheath region 120. The suspended particles 1 are positively charged by colliding with positive ions staying in the sheath region 120. Therefore, the floating particles 1 charged positively and floating in the sheath region 120 are collected by a negative DC voltage applied to the particle collecting electrode 71.

  Further, an AC voltage (high frequency voltage) may be applied to the particle collecting electrode 71. That is, as described above, once the suspended particles 1 that are negatively or positively charged are once collected on the inner wall of the reaction tube 12, for example, It becomes difficult to detach from the inner wall. Accordingly, when a negative potential and a positive potential are alternately supplied to the particle collecting electrode 71, the negatively charged floating particles 1 and the positively charged floating particles 1 are alternately collected. In applying such AC voltage, the negative voltage value may be smaller than the positive voltage value, and in this case, more negatively charged suspended particles 1 are collected. As the film forming method of the present invention, the film may be formed at room temperature without heating the wafer W.

W Wafer 11 Wafer boat 12 Reaction tube 61 Plasma generating electrode 71 Particle collection electrode 21 Exhaust port

Claims (14)

In a semiconductor manufacturing apparatus for carrying out film formation processing by carrying a substrate holder holding a plurality of substrates in a shelf shape into a reaction tube made of vertical quartz,
A processing gas supply unit for supplying a processing gas to the substrate;
A conductive member for plasma to which high-frequency power is supplied in order to turn the processing gas supplied from the processing gas supply unit into plasma;
An electrode that is provided so as to face the space in the reaction tube through a dielectric member, and to which a voltage is applied to draw particles in the reaction tube to the dielectric member side by Coulomb force;
A semiconductor manufacturing apparatus comprising: an exhaust port for evacuating the inside of the reaction tube. The dielectric member is the reaction tube;
The semiconductor manufacturing apparatus according to claim 1, wherein the electrode is disposed outside the reaction tube. The dielectric member is a quartz member that covers the electrode,
The semiconductor manufacturing apparatus according to claim 1, wherein the electrode is provided inside the reaction tube. The reaction tube is composed of an inner tube and an outer tube, and is configured as a double tube structure in which processing gas is exhausted through a gap between the inner tube and the outer tube.
The semiconductor manufacturing apparatus according to claim 1, wherein the electrode is covered with a quartz member forming the dielectric member and provided in the gap.   The semiconductor manufacturing apparatus according to claim 1, wherein the electrode is provided along a length direction of the substrate holder. On the side peripheral wall of the reaction tube, a convex portion that bulges outward is provided along the vertical direction,
The plasma conductive member is disposed so as to face the convex portion outside the reaction tube,
The processing gas supply unit is located on the outer side in the radial direction of the reaction tube than the conductive member for plasma when seen in a plan view,
3. The semiconductor manufacturing apparatus according to claim 2, wherein the electrode is disposed so as to face the convex portion on a radial inner side of the reaction tube with respect to the processing gas supply unit when seen in a plan view.   The semiconductor manufacturing apparatus according to claim 1, wherein the electrode is disposed to face a top plate of the substrate holder. A source gas supply unit for supplying source gas to the substrate;
A gas supply unit for supplying a replacement gas for atmosphere replacement to the substrate;
A source gas and a plasma process gas are supplied to the substrate alternately several times through a replacement step of the atmosphere in the reaction tube with a replacement gas, and at least a voltage is applied to the electrode when performing the replacement step. 8. The semiconductor manufacturing apparatus according to claim 1, further comprising a control unit that outputs a control signal so as to execute the applying step. The plasma conductive member also serves as the electrode,
A switch for switching the power supply path is provided to supply a high-frequency voltage to the plasma conductive member when the processing gas is turned into plasma, and to apply a voltage to the electrode when the processing gas is not turned into plasma. The semiconductor manufacturing apparatus according to claim 1, wherein the apparatus is a semiconductor manufacturing apparatus. A supply unit for supplying a cleaning gas into the reaction tube;
The controller, following the step of applying the voltage, exhausts the reaction tube and supplies a cleaning gas to the reaction tube to output a control signal so as to discharge the particles from the reaction tube. The semiconductor manufacturing apparatus according to claim 8. In a film forming method for carrying out a film forming process by carrying a substrate holder holding a plurality of substrates in a shelf shape into a reaction tube made of vertical quartz,
Supplying a processing gas from the processing gas supply unit to the substrate;
Supplying high-frequency power to a plasma conductive member, and converting the processing gas supplied from the processing gas supply unit into plasma;
Applying a voltage to an electrode provided to face the space in the reaction tube through a dielectric member, and drawing particles in the previous reaction tube to the dielectric member side by Coulomb force;
Evacuating the reaction tube;
And a step of heating the substrate. Before the step of turning the processing gas into plasma, performing a step of supplying a source gas to the substrate,
The step of converting the processing gas into plasma and the step of supplying the raw material gas are alternately performed a plurality of times through a step of replacing the atmosphere in the reaction tube with a replacement gas,
The film forming method according to claim 11, wherein the drawing step is performed at least when the replacing step is performed.   The process according to claim 11 or 12, wherein after the drawing step, the inside of the reaction tube is evacuated and a cleaning gas is supplied into the reaction tube to discharge the particles from the inside of the reaction tube. Membrane processing method. A storage medium storing a computer program that runs on a computer,
14. A storage medium characterized in that the computer program includes steps so as to implement the film forming method according to claim 11.

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