The present application is based on Japanese Patent Applications No. 2008-227029 and No. 2009-181806, filed with the Japanese Patent Office on Sep. 4, 2008, and Aug. 4, 2009, respectively, the entire contents of which are hereby incorporated herein by reference.
1. Field of the Invention
The present invention relates to a film deposition apparatus for depositing a film on a substrate by carrying out plural cycles of supplying in turn at least two source gases to the substrate in order to form plural layers of a reaction product, a substrate process apparatus including the film deposition apparatus, and a turntable to be used in the film deposition apparatus.
2. Description of the Related Art
As a film deposition technique in a semiconductor fabrication process, there has been known a process, in which a first reaction gas is adsorbed on a surface of a semiconductor wafer (referred to as a wafer hereinafter) and the like under vacuum and then a second reaction gas is adsorbed on the surface of the wafer in order to form one or more atomic or molecular layers through reaction of the first and the second reaction gases on the surface of the wafer, and such an alternating adsorption of the gases is repeated plural times, thereby depositing a film on the wafer. This technique is called Atomic Layer Deposition (ALD) or Molecular Layer Deposition (MLD) and advantageous in that the film thickness can be controlled at higher accuracy by the number of times of alternately supplying the reaction gases, and in that the deposited film can have excellent uniformity over the wafer. Therefore, this deposition method is thought to be promising as a film deposition technique that can address further miniaturization of semiconductor devices.
Such a film deposition method may be preferably used, for example, for depositing a dielectric material to be used as a gate insulator. When silicon dioxide (SiO2) is deposited as the gate insulator, a bis (tertiary-butylamino) silane (BTBAS) gas or the like is used as a first reaction gas (source gas) and ozone gas or the like is used as a second gas (oxidation gas).
In order to carry out such a deposition method, use of a single-wafer deposition apparatus having a vacuum chamber and a shower head at a top center portion of the vacuum chamber and a deposition method using such an apparatus has been under consideration. In the deposition apparatus, the reaction gases are introduced into the chamber from the top center portion, and unreacted gases and by-products are evacuated from a bottom portion of the chamber. When such a deposition chamber is used, it takes a long time for a purge gas to purge the reaction gases, resulting in an extremely long process time because the number of cycles may reach several hundred. Therefore, a deposition method and apparatus that enable high throughput is desired.
Under these circumstances, film deposition apparatuses having a vacuum chamber and a turntable that holds plural wafers along a rotation direction have been proposed in order to carry out ALD or MLD, in documents listed below.
Patent Document 1 listed below discloses a deposition apparatus whose process chamber has a shape of a flattened cylinder. The process chamber is divided into two half circle areas. Each area has an evacuation port provided to surround the area at the top portion of the corresponding area. In addition, the process chamber has a gas inlet port that introduces separation gas between the two areas along a diameter of the process chamber. With these configurations, while different reaction gases are supplied into the corresponding areas and evacuated from above by the corresponding evacuation ports, a turntable is rotated so that the wafers placed on the turntable can alternately pass through the two areas.
Patent Document 2 discloses a process chamber in which four wafers are placed on a wafer support member (rotation table) at equal angular intervals along a rotation direction of the wafer support member, first and second gas ejection nozzles are located along the rotation direction and oppose the wafer support member, and purge nozzles are located between the first and the second gas ejection nozzles. In this process chamber, the wafer support member is horizontally rotated in order to deposit a film on the wafers.
Patent Document 3 discloses a process chamber that is divided into plural process areas along the circumferential direction by plural partitions. Below the partitions, a circular rotatable susceptor on which plural wafers are placed is provided leaving a slight gap in relation to the partitions.
Moreover, Patent Document 4 discloses a technique in which a circular gas supplying plate is divided into eight sector areas, four gas inlet ports for AsH3 gas, H2 gas, trimethyl gallium (TMG) gas, and H2 gas, respectively, are arranged at angular intervals of 90 degrees, evacuation ports are located between the adjacent gas inlet ports, and a susceptor that holds plural wafers and opposes the gas supplying plate is rotated.
Patent Document 5 discloses a process chamber in which an area above a turntable is partitioned in a crisscross manner by four vertical walls; four wafers are arranged below the corresponding partitioned areas; and an injector unit having a source gas injector, a cross-shaped reaction gas injector, and a purge gas injector that are arranged in turn along a rotation direction. In this process chamber, the injector unit horizontally rotates around a center axis thereof above the four wafers while ejecting a source gas, a purge gas, a reaction gas, and another purge gas, and these gases are evacuated from a peripheral area of the turntable.
Furthermore, Patent Document 6 (Patent Documents 7, 8) discloses a film deposition apparatus preferably used for an Atomic Layer CVD method that causes plural gases to be alternately adsorbed on a target (a wafer). In the apparatus, a susceptor that holds the wafer is rotated, while source gases and purge gases are supplied to the susceptor from above. Paragraphs 0023, 0024, and 0025 of the document describe partition walls that extend in a radial direction from a center of a chamber, and gas ejection holes that are formed in a bottom of the partition walls in order to supply the source gases or the purge gas to the susceptor, so that an inert gas as the purge gas ejected from the gas ejection holes produces a gas curtain. Regarding evacuation of the gases, paragraph 0058 of the document describes that the source gases are evacuated through an evacuation channel 30a, and the purge gases are evacuated through an evacuation channel 30b.
Patent Document 1: United States Patent Publication No. 7,153,542 (FIGS. 6A, 6B)
Patent Document 2: Japanese Patent Application Laid-Open Publication No. 2001-254181 (FIGS. 1, 2)
Patent Document 3: Japanese Patent Publication No. 3,144,664 (FIGS. 1, 2, claim 1)
Patent Document 4: Japanese Patent Application Laid-Open Publication No. H4-287912
Patent Document 5: United States Patent Publication No. 6,634,314
Patent Document 6: Japanese Patent Application Laid-Open Publication No. 2007-247066 (paragraphs 0023 through 0025, 0058, FIGS. 12 and 18)
Patent Document 7: United States Patent Publication No. 2007/218701
Patent Document 8: United States Patent Publication No. 2007/218702
However, in the apparatus described in Patent Document 1, because the evacuation port is provided at the upper portion of the process chamber and between the separation gas inlet port and the area where reaction gas is supplied, and the reaction gas is evacuated along with the separation gas upward from the evacuation port, particles in the process chamber may be blown up by the upward flow of the gases and fall on the wafers, leading to contamination of the wafers.
In addition, in the process chamber described in Patent Document 2, the gas curtain cannot completely prevent mixture of the reaction gases but may allow one of the reaction gases to flow through the gas curtain to be mixed with the other reaction gas partly because the gases flow along the rotation direction due to the rotation of the wafer support member. Moreover, the first (second) reaction gas discharged from the first (second) gas outlet nozzle may flow through the center portion of the wafer support member to meet the second (first) gas, because centrifugal force is not strongly applied to the gases in a vicinity of the center of the rotating wafer support member. Once the reaction gases are mixed in the chamber, an MLD (or ALD) mode film deposition cannot be carried out as expected.
In the apparatus described in Patent Document 3, the process gas introduced into one of the process areas may spread into the adjacent process area through the gap below the partition, and be mixed with another process gas introduced into the adjacent process area. Moreover, the process gases may be mixed in the evacuation chamber, so that the wafer is exposed to the two process gases at the same time. Therefore, ALD (or MLD) mode deposition cannot be carried out in a proper manner by this process chamber.
Patent Document 4 does not provide any realistic measures to prevent two source gases (AsH3, TMG) from being mixed. Because of the lack of such measures, the two source gases may be mixed around the center of the susceptor and through the H2 gas supplying plates. Moreover, because the evacuation ports are located between the adjacent two gas supplying plates to evacuate the gases upward, particles are blown up from the susceptor surface, which leads to wafer contamination.
In the process chamber described in Patent Document 5, after one of the injector pipes passes over one of the quarters, this quarter cannot be purged by the purge gas in a short period of time. In addition, the reaction gas in one of the partitioned areas can easily flow into an adjacent one of the partitioned areas and the reaction gases react with each other over the wafers.
The present invention has been made in view of the above, and provides a film deposition apparatus, a substrate process apparatus and a turntable to be used in the film deposition apparatus which are capable of reducing contamination due to metal powders or the like caused from the turntable and its vicinity and cracks/breakage, when at least two source gases are supplied in turn to a substrate to form plural layers of a reaction product and thus deposit a film on the substrate.
A first aspect of the present invention provides a film deposition apparatus for depositing a film on a substrate by carrying out a cycle of alternately supplying at least two kinds of reaction gases that react with each other to the substrate to produce a layer of a reaction product in a chamber. The film deposition apparatus includes a turntable rotatably provided in the chamber; a substrate receiving portion that is provided in the turntable and the substrate is placed in; a first reaction gas supplying portion configured to supply a first reaction gas to a surface having the substrate receiving portion; a second reaction gas supplying portion configured to supply a second reaction gas to the surface having the substrate receiving portion, the second reaction gas supplying portion being separated from the first reaction gas supplying portion along a rotation direction of the turntable; a separation area located along the rotation direction between a first process area in which the first reaction gas is supplied and a second process area in which the second reaction gas is supplied, wherein the separation area includes a separation gas supplying portion that supplies a first separation gas, and a ceiling surface that creates in relation to the turntable a thin space in which the first separation gas may flow from the separation area to the process area side in relation to the rotation direction; a center area that is located substantially in a center portion of the chamber in order to separate the first process area and the second process area, and has an ejection hole that ejects a second separation gas along the surface having the substrate receiving area; an evacuation opening provided in the chamber in order to evacuate the chamber; an upper holding member that may be pressed on an upper center portion of the turntable and is made of one of quartz and a ceramic material; and a lower holding member that may be pressed on a lower center portion of the turntable in order to rotatably hold the turntable in cooperation with the upper holding member.
A second aspect of the present invention provides a film deposition apparatus for depositing a film on a substrate by carrying out a cycle of alternately supplying at least two kinds of reaction gases that react with each other to the substrate to produce a layer of a reaction product in a chamber. The film deposition apparatus includes a turntable rotatably provided in the chamber; a substrate receiving portion that is provided in the turntable and the substrate is placed in; a first reaction gas supplying portion configured to supply a first reaction gas to a surface having the substrate receiving portion; a second reaction gas supplying portion configured to supply a second reaction gas to the surface having the substrate receiving portion, the second reaction gas supplying portion being separated from the first reaction gas supplying portion along a rotation direction of the turntable; separation area located along the rotation direction between a first process area in which the first reaction gas is supplied and a second process area in which the second reaction gas is supplied, wherein the separation area includes a separation gas supplying portion that supplies a first separation gas, and a ceiling surface that creates in relation to the turntable a thin space in which the first separation gas may flow from the separation area to the process area side in relation to the rotation direction; a center area that is located substantially in a center portion of the chamber in order to separate the first process area and the second process area, and has an ejection hole that ejects a second separation gas along the surface having the substrate receiving area; an evacuation opening provided in the chamber in order to evacuate the chamber; an upper holding member that may be pressed on an upper center portion of the turntable; and a lower holding member that may be pressed on a lower center portion of the turntable in order to rotatably hold the turntable in cooperation with the upper holding member, wherein an area where the upper holding member and the turntable contact each other is made of a ceramic material, and an area where the lower holding member and the turntable contact each other is made of a ceramic material.
A third aspect of the present invention provides a turntable rotatably provided in a film deposition apparatus and held in such a manner that an upper holding member is pressed on an upper center portion of the turntable and a lower holding member is pressed on a lower center portion of the turntable. The turntable includes a ceramic film formed on areas of the turntable, the areas contacting the upper holding member and the lower holding member, respectively.
According to an embodiment of the present invention, when at least two source gases are supplied in turn to a substrate to form plural layers of a reaction product, and thus deposit a film on the substrate, contamination due to metal powders or the like caused from a turntable and its vicinity can be reduced, and breakage/cracks of the turntable can be avoided. Therefore, film deposition can be carried out in a clean environment for a long time, thereby reducing defective devices and enhancing an apparatus utilization efficiency.
Referring to the accompanying drawings, a film deposition apparatus according to an embodiment of the present invention will be explained. As shown in
The turntable 2 is fixed onto a cylindrically shaped core portion 21. The core portion 21 is fixed on a top end of a rotational shaft 22 that extends in a vertical direction. The rotational shaft 22 penetrates a bottom portion 14 of the chamber body 12 and is fixed at the lower end to a driving mechanism 23 that can rotate the rotational shaft 22 clockwise, in this embodiment. The rotational shaft 22 and the driving mechanism 23 are housed in a case body 20 having a cylinder with a bottom. The case body 20 is hermetically fixed to a bottom surface of the bottom portion 14 via a flanged portion, which isolates an inner environment of the case body 20 from an outer environment.
As shown in
The concave portions 24 are wafer receiving areas provided to position the wafers W and prevent the wafers W from being thrown out by centrifugal force caused by rotation of the turntable 2. However, the wafer W receiving areas are not limited to the concave portions 24, but may be configured by plural guide members that are located along a circumferential direction of the turntable 2 on the turntable 2. For example, the wafer receiving areas may be configured by electrostatic chucks. In this case, an area where the wafer W is held by the electrostatic chucks is the wafer receiving area.
Referring to
Although not shown, the reaction gas nozzle 31 is connected to a gas supplying source of bis (tertiary-butylamino) silane (BTBAS), which is a first source gas, and the reaction gas nozzle 32 is connected to a gas supplying source of O3 (ozone) gas, which is a second source gas. In addition, the separation gas nozzles 41, 42 are connected to gas supplying sources of N2 (nitrogen) gas (not shown).
The reaction gas nozzles 31, 32 have plural ejection holes 33 to eject the corresponding source gases downward. The plural ejection holes 33 are arranged in longitudinal directions of the reaction gas nozzles 31, 32 at predetermined intervals. The reaction gas nozzles 31, 32 are a first reaction gas supplying portion and a second reaction gas supplying portion, respectively, in this embodiment. In addition, an area below the reaction gas nozzle 31 is a first process area P1 in which the BTBAS gas is adsorbed on the wafer W, and an area below the reaction gas nozzle 32 is a second process area P2 in which the O3 gas is adsorbed on the wafer W.
The separation gas nozzles 41, 42 are provided to create corresponding separation areas D that separate the first process area P1 and the second process area P2. In each of the separation areas D, there is provided a convex portion 4 on the ceiling plate 11, as shown in
With the above configuration, there are flat low ceiling surfaces 44 (first ceiling surfaces) on both sides of the separation gas nozzle 41 (42), and high ceiling surfaces 45 (second ceiling surfaces) outside of the corresponding low ceiling surfaces 44, as shown in
Taking an example of the separation gas nozzle 41, this nozzle 41 may impede the O3 gas and the BTBAS gas from entering between the convex portion 4 and the turntable 2 from the upstream side and the downstream side of the rotation direction, respectively. “The gases being impeded from entering” means that the N2 gas as the separation gas ejected from the separation gas nozzle 41 diffuses between the first ceiling surfaces 44 and the upper surface of the turntable 2 and flows out to a space below the second ceiling surfaces 45, which are adjacent to the corresponding first ceiling surfaces 44 in the illustrated example, so that the gases cannot enter the separation space from the space below the second ceiling surfaces 45. “The gases cannot enter the separation space” means not only that the gases are completely prevented from entering the separation space, but that the gases cannot proceed farther toward the separation gas nozzle 41 and thus be mixed with each other even if a fraction of the reaction gases enter the separation space. Namely, as long as such an effect is provided, the separation area D separates the first process area P1 and the second process area P2. Incidentally, the BTBAS gas or the O3 gas adsorbed on the wafer W can pass through below the convex portion 4. Therefore, the gases in “the gases being impeded from entering” mean the gases in a gaseous phase.
Referring to
The separation area D is configured by forming the groove portion 43 in a sector-shaped plate to be the convex portion 4, and locating the separation gas nozzle 41 (42) in the groove portion 43 in the above embodiment. However, two sector-shaped plates may be attached on the lower surface of the ceiling plate 11 by screws so that the two sector-shaped plates are located on both sides of the separation gas nozzle 41 (32).
The separation gas nozzles 41, 42 have plural ejection holes 40 open downward. The plural ejection holes 40 have an inner diameter of about 0.5 mm and are arranged at predetermined intervals of about 10 mm in longitudinal directions of the separation gas nozzles 41, 42. In the reaction gas nozzles 31, 32, the ejection holes 33 open downward have diameters of about 0.5 mm and are arranged at intervals of about 10 mm along longitudinal directions of the reaction gas nozzles 31, 32.
When the wafer W having a diameter of about 300 mm is supposed to be processed in the vacuum chamber 1, the convex portion 4 has a circumferential length of, for example, about 146 mm along an inner arc that is at a distance of 140 mm from the rotation center of the turntable 2, and a circumferential length of, for example, about 502 mm along an outer arc corresponding to the outermost portion of the concave portions 24 of the turntable 2 in this embodiment. In addition, a circumferential length from one side wall of the convex portion 4 through the nearest side wall of the groove portion 43 along the outer arc is about 246 mm.
In addition, the height h (
As described above, the vacuum chamber 1 is provided with the first ceiling surfaces 44 and the second ceiling surfaces 45 higher than the first ceiling surfaces 44, which are alternately arranged in the circumferential direction.
The inner circumferential wall of the chamber body 12 is close to the outer circumferential surface of the bent portion 46 and stands upright in the separation area D, as shown in
Referring to
Referring to
With the purge gas supplying pipes 72, 73, the space extending from the case body 20 through the heater unit housing space is purged with N2 gas as shown by arrows in
Referring to
In addition, a transfer opening 15 is formed in a side wall of the chamber body 12 as shown in
The film deposition apparatus according to this embodiment is provided with a controller 100 in order to control operations (including operations in the other embodiments explained later) of the deposition apparatus. The control portion 100 includes a process controller 100a formed of, for example, a computer, a user interface portion 100b, and a memory device 100c. The memory device 100c stores a program for operating the apparatus. The program includes a group of steps for executing an operation of the apparatus described later, and may be installed to the memory device 100c from a storing medium 100d such as a hard disk, a compact disk, a magneto-optical disk, a memory card, a flexible disk, and the like.
In this embodiment, the turntable 2 is held by the core portion 21, as stated above. Structures of the core portion 21 and the turntable 2, specifically, how the core portion 21 and the turntable 2 are fixed, are explained with reference to
In the film deposition apparatus according to this embodiment, the core portion 21 that holds the turntable 2 has an upper hub 121 as an upper holding member and a lower hub 122 as a lower holding member. The turntable 2 has a circular opening at the center thereof, and this opening is utilized when the turntable 2 is held by the upper hub 121 and the lower hub 122. Specifically, the upper hub 121 and the lower hub 122 are pressed on the turntable 2 from above and below, respectively, so that the turntable 2 is sandwiched and firmly held by the upper hub 121 and the lower hub 122. The upper hub 121 is made of, for example, quartz, and has a hole 127 in or around the center portion of the upper hub 121. The hole 127 allows a bolt (screw) 123 to pass therethrough. The bolt 123 fastens the upper hub 121 with the lower hub 122 in order to hold the turntable 2. In addition, the lower hub 122 is made of, for example, stainless steel, inconel alloy, or the like, and coupled with the rotational shaft 22.
The lower hub 122 is provided with a threaded hole 128 into which the bolt 123 is screwed. As shown in
However, such a contamination due to the metal powders or the like and breakage of the turntable 2 are avoided because of the ceramic film 122a formed in the contact area between the lower hub 122 and the turntable 2 in this embodiment. In addition, because the upper hub 121 and the turntable 2 are made of quartz in this embodiment, substantially no problems of contamination and breakage will occur in an area where the upper hub 121 contacts the turntable 2.
Moreover, an upper surface (contacting surface) of the ceramic film 122a formed on the lower hub 122 has a mirror surface in a contact area of the ceramic film 122a to the turntable 2. Similarly, a contact area of the upper hub 121 to the turntable 2 has a mirror surface.
In addition, the turntable 2 may be made of not only quartz but also carbon or the like. A SiC film 2a is formed on the turntable 2 made of carbon or the like, as shown in
Because the upper hub 121 is made of quartz and the turntable 2 is made of quartz, or carbon or the like and coated with the SiC film 2a as stated above, ceramic materials contact each other. Therefore, substantially no metal powders are caused due to friction. Especially, when the both contact surfaces have mirror surfaces, a contamination problem is assuredly reduced.
In addition, the ceramic film 122a made of, Al2O3, Y2O3, or a mixture of Al2O3 and Y2O3 is formed on the lower hub 122. The turntable 2 is made of quartz, or carbon or the like and coated with the SiC film 2a. Therefore, substantially no metal powders are caused due to friction. Especially, when the both contact surfaces have mirror surfaces, a contamination problem is assuredly reduced.
As stated above, the turntable 2 is held by the upper hub 121 and the lower hub 122 without causing the contamination problem due to the metal powders. Incidentally, the mirror surface may be made by machining such as grinding and polishing.
Incidentally, the lower hub 122 may be made of a ceramic material rather than stainless steel, inconel alloy, or the like. Examples of the ceramic materials, which is preferable to make the lower hub 122 from a viewpoint of toughness, include silicon nitride (SiN), zirconia oxide, or the like. When the lower hub 122 is formed of a ceramic material, there is no need to form the ceramic film 122a on the contact area of the lower hub 122 to the turntable 2.
In addition, the turntable 2 may be made of a ceramic material. In this case, the above advantages are demonstrated without the SiC film 2a formed on the turntable 2. In this embodiment, the upper hub 121 is made of quartz, which has relatively greater resistances against heat and chemical agents, because the upper hub 121 may be heated up to about 300° C. through 400° C. and exposed to corrosive gases in the vacuum chamber 1. Because the upper hub 121 and the turntable 2 are made of quartz in this embodiment, the contact of the upper hub 121 to the turntable 2 is made between the ceramic materials. In addition, when the ceramic film 122a is formed on the lower hub 122, the contact of the lower hub 122 to the turntable 2 is made between the ceramic materials. Moreover, when the lower hub 122 is made of a ceramic material, the contact of the lower hub 122 to the turntable 2 is made between the ceramic materials.
Referring to
In addition, a center ring 125 is provided in the opening formed in the center portion of the turntable 2 so that a center axis of the turntable 2 is in alignment with a rotation axis of the rotational shaft 22, in this embodiment. Because a coil spring 126 is provided between the turntable 2 and the center ring 125 and serves as a buffer for thermal expansion of the turntable 2, the turntable 2 is not damaged, broken, or cracked even when the turntable 2 may be deformed by the heat. Incidentally, because when the turntable 2 is rotated the center ring 125 is also rotated, the rotation axis of the turntable 2 is in alignment with the rotation axis of the center ring 125.
As described above, the turntable 2 is firmly held by the upper hub 121 and the lower hub 122 in such a manner that the upper hub 121 and the lower hub 122 are fastened with each other by the bolt 123, with the turntable 2 between the upper hub 121 and the lower hub 122, in this embodiment. However, as shown in
Next, a process carried out in the film deposition apparatus according to this embodiment is explained. First, the gate valve (not shown) is opened. Then, the wafer W is transferred into the vacuum chamber 1 through the transfer opening 15 by the transfer arm 10 (
Such wafer transferring is carried out by intermittently rotating the turntable 2, and five wafers are placed in the corresponding concave portions 24. Next, the gate valve is closed; the vacuum chamber 1 is evacuated to a predetermined pressure; and the wafers W are heated by the heater unit 7 via the turntable 2 while rotating the turntable 2. Specifically, the turntable 2 is heated in advance at a temperature of, for example, 300° C., and the wafers W are heated upon being placed on the turntable 2 (the concave portions 24). After the temperature of the wafers W is confirmed to be the predetermined temperature by a temperature sensor (not shown), the BTBAS gas is supplied from the first reaction gas nozzle 31, the O3 gas is supplied from the second reaction gas nozzle 32, and the N2 gas is supplied from the and the separation gas nozzles 41, 42.
Because the wafers W move alternately through the first process area P1 where the first reaction gas nozzle 31 is arranged and the second process area P2 where the second reaction gas nozzle 32 is arranged by the rotation of the turntable 2, the BTBAS gas is adsorbed on the surfaces of the wafers W and then the O3 gas is adsorbed on the surfaces of the wafers W, thereby oxidizing the BTBAS molecules to form a mono-layer or plural layers of silicon oxide. In such a manner, molecular layers of silicon oxide are accumulatively deposited, and thus the silicon oxide film having a predetermined thickness is formed on the wafers W after predetermined rotations of the turntable 2.
At this time, the N2 gas serving as the separation gas is supplied from the separation gas supplying pipe 51 (
Next, the flow patterns of the gases supplied into the vacuum chamber 1 from the gas nozzles 31, 32, 41, 42 are described in reference to
Another part of the O3 gas ejected from the second reaction gas nozzle 32 hits and flows along the top surface of the turntable 2 (and the surface of the wafers W) in the same direction as the rotation direction of the turntable 2. This part of the O3 gas mainly flows toward the evacuation area 6 due to the N2 gas flowing from the center portion C and suction force through the evacuation port 62. On the other hand, a small portion of this part of the O3 gas flows toward the separation area D located downstream of the rotation direction of the turntable 2 in relation to the second reaction gas nozzle 32 and may enter the gap between the ceiling surface 44 and the turntable 2. However, because the height h of the thin space is designed so that the O3 gas is impeded from flowing into the gap at film deposition conditions intended, the small portion of the O3 gas cannot flow into the gap. Even when a small fraction of the O3 gas flows into the gap, the fraction of the O3 gas cannot flow farther into the separation area D, because the fraction of the O3 gas can be pushed backward by the N2 gas ejected from the separation gas nozzle 41. Therefore, substantially all the part of the O3 gas flowing along the top surface of the turntable 2 in the rotation direction flows into the evacuation area 6 and is evacuated by the evacuation port 62, as shown in
Similarly, the BTBAS gas ejected from the first reaction gas nozzle 31 to flow along the top surface of the turntable 2 (and the surface of the wafers W) in the rotation direction of the turntable 2 and the opposite direction cannot flow into the gaps below the convex portions 4 located upstream and downstream of the rotation direction, respectively. Alternatively, even when a fraction of the BTBAS gas enters the gaps, the fraction of the BTBAS gas is pushed backward to the process areas P1, P2. Then, the BTBAS gas flows into the evacuation area 6 between the circumference of the turntable 2 and the inner circumferential wall of the vacuum chamber 1, and is evacuated through the evacuation port 61 along with the N2 gas ejected from the center area C.
As stated above, the separation areas D may prevent the BTBAS gas and the O3 gas from flowing thereinto, or may greatly reduce the amount of the BTBAS gas and the O3 gas flowing thereinto, or may push the BTBAS gas and the O3 gas backward. On the other hand, the BTBAS molecules and the O3 molecules adsorbed on the wafer W are allowed to go through the separation area D (below the lower ceiling surface 44), contributing to the film deposition.
Additionally, the BTBAS gas in the first process area P1 (the O3 gas in the second process area P2) is impeded from flowing into the center area C, because the separation gas is ejected toward the outer circumferential edge of the turntable 2 from the center area C, as shown in
Moreover, the BTBAS gas in the first process area P1 (the O3 gas in the second process area P2) is impeded from flowing into the second process area P2 (the first process area P1) through the space between the turntable 2 and the inner circumferential wall of the chamber body 12. This is because the bent portion 46 is formed downward from the convex portion 4 so that the gaps between the bent portion 46 and the turntable 2 and between the bent portion 46 and the inner circumferential wall of the chamber body 12 are as small as the height h of the ceiling surface 44 of the protrusion portion 5, thereby substantially avoiding gaseous communication between the two process areas P1, P2, as stated above. Therefore, the two separation areas D separate the first process area P1 and the second process area P2, and the BTBAS gas and the O3 gas are evacuated from the evacuation ports 61, 62, respectively. As a result, the reaction gases (BTBAS, O3) are not mixed in an atmosphere in the vacuum chamber 1. Moreover, because the space below the turntable 2 is purged with the N2 gas, the BTBAS gas, for example, flowing into the evacuation area 6 cannot flow through the space below the turntable 2 into the second process area P2 where the O3 gas is supplied.
After the film deposition is completed in the above manner, the wafers W are transferred out from the vacuum chamber 1 in accordance with procedures opposite to the procedures for transferring the wafers W into the vacuum chamber 1.
An example of process parameters preferable in the film deposition apparatus according to this embodiment is listed in the following. A rotational speed of the turntable 2 is 1 through 500 rpm (in the case of the wafer W having a diameter of 300 mm); a pressure in the vacuum chamber 1 is about 1.067 kPa (8 Torr); a temperature of the wafers W is about 350° C.; a flow rate of the DCS gas is 100 sccm; a flow rate of the NH3 gas is about 10000 sccm; a flow rate of the N2 gas from the separation gas nozzles 41, 42 is about 20000 sccm; and a flow rate of the N2 gas from the separation gas supplying pipe 51 at the center of the vacuum chamber 1 is about 5000 sccm. In addition, the number of cycles of alternately supplying the reaction gases to the wafers W, namely, the number of times when the wafers W alternately pass through the process area P1 and the process area P2 is about 600, though changed depending on the film thickness required.
According to the film deposition apparatus of this embodiment, because the film deposition apparatus has the separation areas D including the low ceiling surface 44 between the first process area P1, to which the BTBAS gas is supplied from the first reaction gas nozzle 31, and the second process area P2, to which the O3 gas is supplied from the second reaction gas nozzle 32, the BTBAS gas (the O3 gas) is prevented from flowing into the second process area P2 (the first process area P1) and being mixed with the O3 gas (the BTBAS gas). Therefore, an MLD (or ALD) mode deposition of silicon dioxide is assuredly performed by rotating the turntable 2 on which the wafers W are placed in order to allow the wafers W to pass through the first process area P1, the separation area D, the second process area P2, and the separation area D. In addition, the separation areas D further include the separation gas nozzles 41, 42 from which the N2 gases are ejected in order to further assuredly prevent the BTBAS gas (the O3 gas) from flowing into the second process area P2 (the first process area P1) and being mixed with the O3 gas (the BTBAS gas). Moreover, because the vacuum chamber 1 of the film deposition apparatus according to this embodiment has the center area C having the ejection holes from which the N2 gas is ejected, the BTBAS gas (the O3 gas) is prevented from flowing into the second process area P2 (the first process area P1) through the center area C and being mixed with the O3 gas (the BTBAS gas). Furthermore, because the BTBAS gas and the O3 gas are not mixed, almost no deposits of silicon dioxide are made on the turntable 2, thereby reducing particle problems.
Incidentally, although the turntable 2 has the five concave portions 24 and five wafers W placed in the corresponding concave portions 24 can be processed in one run in this embodiment, only one wafer W may be placed in one of the five concave portions 24, or the turntable 2 may have only one concave portion 24.
The reaction gases that may be used in the film deposition apparatus according to an embodiment of the present invention are dichlorosilane (DCS), hexachlorodisilane (HCD), Trimethyl Aluminum (TMA), tris(dimethyl amino) silane (3DMAS), tetrakis-ethyl-methyl-amino-hafnium (TEMHf), bis(tetra methyl heptandionate) strontium (Sr(THD)2) (methyl-pentadionate)(bis-tetra-methyl-heptandionate) titanium (Ti(MPD)(THD)), tetrakis-ethyl-methyl-amino-zirconium (TEMAZr), monoamino-silane, or the like.
Because a larger centrifugal force is applied to the gases in the vacuum chamber 1 at a position closer to the outer circumference of the turntable 2, the BTBAS gas, for example, flows toward the separation area D at a higher speed in the position closer to the outer circumference of the turntable 2. Therefore, the BTBAS gas is more likely to enter the gap between the ceiling surface 44 and the turntable 2 in the position closer to the circumference of the turntable 2. Because of this situation, when the convex portion 4 has a greater width (a longer arc) toward the circumference, the BTBAS gas cannot flow farther into the gap and mix with the O3 gas. In view of this, it is preferable for the convex portion 4 to have a sector-shaped top view, as explained in the above embodiment.
The size of the convex portion 4 (or the ceiling surface 44) is exemplified again below. Referring to
The separation gas nozzle 41 (42) is located in the groove portion 43 formed in the convex portion 4 and the lower ceiling surfaces 44 are located at both sides of the separation gas nozzle 41 (42) in the above embodiment. However, as shown in
The ceiling surface 44 of the separation area D is not necessarily flat in other embodiments. For example, the ceiling surface 44 may be concavely curved as shown in subsection (a) of
In addition, the convex portion 4 may be hollow and the separation gas may be introduced into the hollow convex portion 4. In this case, the plural gas ejection holes 33 may be arranged as shown in subsections (a) through (c) of
Referring to subsection (a) of
While the convex portion 4 has the sector-shaped top view shape in this embodiment, the convex portion 4 may have a rectangle top view shape as shown in subsection (d) of
The heater unit 7 for heating the wafers W is configured to have a lamp heating element instead of the resistance heating element. In addition, the heater unit 7 may be located above the turntable 2, or above and below the turntable 2.
Another arrangement of the first and the second process areas P1, P2 and the separation area D is exemplified in the following. Referring to
In addition, the separation area D may be configured by attaching two sector-shaped plates on the bottom surface of the ceiling plate 1 by screws so that the two sector-shaped plates are located on both sides of the separation gas nozzle 41 (42), as stated above.
In the above embodiment, the first process area P1 and the second process area P2 correspond to the areas having the ceiling surface 45 higher than the ceiling surface 44 of the separation area D. However, at least one of the first process area P1 and the second process area P2 may have another ceiling surface that opposes the turntable 2 at both sides of the reaction gas supplying nozzle 31 (32) and is lower than the ceiling surface 45 in order to prevent gas from flowing into a gap between the ceiling surface concerned and the turntable 2. This ceiling surface, which is lower than the ceiling surface 45, may be as low as the ceiling surface 44 of the separation area D.
Moreover, the ceiling surface, which is lower than the ceiling surface 45 and as low as the ceiling surface 44 of the separation area D, may be provided for both reaction gas nozzles 31, 32 and extended to reach the ceiling surfaces 44 in other embodiments, as shown in
Incidentally, the convex portion 400 may be configured by combining the hollow convex portions 4 shown in any of subsections (a) through (c) of
In the above embodiments, the rotational shaft 22 for the turntable 2 is located in the center of the vacuum chamber 1 and the space defined by the center portion of the turntable 2 and the ceiling plate 11 is purged with the separation gas. However, the film deposition apparatus according to another embodiment may be configured as shown in
Next, a driving mechanism for the turntable 2 is explained. A rotation sleeve 82 is provided so that the rotation sleeve 82 coaxially surrounds the pillar 81. The turntable 2, which is a ring shape, is attached on the outer circumferential surface of the rotation sleeve 82. In addition, a motor 83 is provided in the housing space 80 and a gear 84 is attached to a driving shaft extending from the motor 83. The gear 84 engages with a gear 85 formed or attached on an outer circumferential surface of the rotation sleeve 82, and drives the rotation sleeve 82 via the gear 85 when the motor 83 is energized, thereby rotating the turntable 2. Reference numerals “86”, “87”, and “88” in
In the embodiment illustrated in
Although the two kinds of reaction gases are used in the film deposition apparatus according to the above embodiment, three or more kinds of reaction gases may be used in another film deposition apparatus according to other embodiments of the present invention. In this case, a first reaction gas nozzle, a separation gas nozzle, a second reaction gas nozzle, a separation gas nozzle, and a third reaction gas nozzle may be located in this order at predetermined angular intervals, each nozzle extending along the radial direction of the turntable 2. Additionally, the separation areas D including the corresponding separation gas nozzles are configured in the same manner as explained above.
The film deposition apparatus according to embodiments of the present invention may be integrated into a wafer process apparatus, an example of which is schematically illustrated in
While the present invention has been described in reference to the foregoing embodiments, the present invention is not limited to the disclosed embodiments, but may be modified or altered within the scope of the accompanying claims.
Number | Date | Country | Kind |
---|---|---|---|
2008-227029 | Sep 2008 | JP | national |
2009-181806 | Aug 2009 | JP | national |