Patent Application
20170167019
This patent application is based upon and claims the benefit of priority of Japanese Patent Application No. 2015-240059, filed on Dec. 9, 2015, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a plasma processing apparatus and a film deposition method.
2. Description of the Related Art
ALD (Atomic Layer Deposition) and MLD (Molecular Layer Deposition) in which a plurality kinds of process gases (reaction gases) that react with each other is sequentially supplied to a surface of a wafer, thereby depositing a reaction product on the surface of the wafer, are known as one of methods for depositing a thin film such as a silicon oxide film (SiO2) on a substrate such as a semiconductor wafer. For example, there is a turntable type film deposition apparatus that is combined with a plasma source as one of the ALD film deposition apparatuses, as described in Japanese Laid-Open Patent Application Publication No. 2013-45903. More specifically, the turntable type film deposition apparatus with the plasma source includes a turntable on which five or six wafers are arranged along the circumferential direction, and an antenna to convert a gas to plasma arranged to face a path of the wafers moving by rotation of the turntable.
For example, high-quality and high-speed ALD film deposition can be implemented by using such an apparatus. For example, in the high-quality SiO2 film deposition, there is a method including steps of supplying a Si-containing gas such as 3DMAS (tris(dimethylamino)silane) or an organic aminosilane gas to a source gas supply area, supplying an oxidation gas such as O3 to a reaction gas supply area, supplying a mixed gas of argon, hydrogen and oxygen to a plasma processing area, respectively, and causing a wafer to pass through these areas at a high speed, thereby depositing a high-quality SiO2 film on the wafer. In such a method, a layer of the Si source adsorbed on the wafer in the source gas supply area is oxidized in the reaction gas supply area, and then modified in the plasma processing area where the plasma density and the modification effect are high. Furthermore, the Si adsorption continuously occurs again in the source gas supply area, which makes it relatively easy to acquire uniformity of film deposition across the wafer.
However, along with miniaturization of circuit patterns, for example, as aspect ratios of trenches in trench isolation structures and spaces in line and space patterns increase, it is sometimes difficult to fill up the trenches and the spaces with a film. For example, when a space having a width of about 30 nm is tried to be filled up with a silicon oxide film, because a reaction gas is unlikely to go into the bottom forming a narrow space, the film thickness around a top end of the space of the film deposited on the side wall of the line that also forms the space is likely to become thick, and the film thickness around the bottom is likely to become thin. Thus, the silicon oxide film filling the space may contain a void. When such a silicon oxide film is etched in the subsequent etching process, an opening in communication with the void may be formed in the top surface of the silicon oxide film. In such a case, an etching gas (or an etching solution) may invade from the opening into the silicon oxide film, which may cause contamination, or metal may enter the void during the subsequent metallization process, which may cause a defect.
Such a problem may occur not only in ALD but also in CVD (Chemical Vapor Deposition). For example, when a conductive contact hole (so-called plug) is formed by filling a contact hole formed in a semiconductor substrate with a film made of a conductive material, a void is sometimes formed in the plug. Therefore, to prevent this, Japanese Laid-Open Patent Application Publication No. 2013-135154 describes a film deposition method in which an organic aminosilane gas is caused to adsorb on a surface in a trench; an adsorption site is formed by adsorption of an OH group; and an upper portion of the trench is oxidized by oxidation plasma, thereby leaving many OH groups on and around the bottom and few OH groups at and around the opening portion. When a silicon oxide film is deposited in such a state, the silicon oxide film is deposited so as to becomes thick on and around the bottom and to become thin with the decreasing distance to the opening portion (upper end) with high bottom-up properties, thereby preventing the generation of the void.
However, the film deposition method as described in Japanese Laid-Open Patent Application Publication No. 2013-135154 in which the distribution of OH groups is controlled by plasma and thereby controlling an amount of adsorption of the organic aminosilane gas is often more difficult to acquire preferable uniformity across the substrate than the film deposition method of causing one layer of a source gas on a substrate, oxidizing the one layer of the source gas, and modifying the one oxidized layer. When a turntable type plasma processing apparatus or plasma processing apparatus is used, in the control of the distribution of OH groups by the plasma source, oxidation is likely to be insufficient at the periphery and many OH groups are likely to be present at the periphery because the peripheral portion rotates and moves faster than the central portion around the axis due to a difference in angular velocity. Thus, the amount of adsorption of the organic aminosilane at the periphery is likely to be more than that of the central portion, and the film thickness at the periphery is sometimes thicker than that of the central portion.
Moreover, in other types of substrate processes and plasma processes that do not control the OH groups, with respect to the turntable type plasma processing apparatus, a supply of plasma at the periphery is likely to be lower than the supply at the central portion due to the above-mentioned difference in angular velocity, and a disproportion of the plasma process between the central portion and the peripheral portion of the turntable is liable to be generated.
Furthermore, when the turntable type plasma processing apparatus is not used, a regional distribution of the plasma process is sometimes desired to be adjusted.
Embodiments of the present invention provide a plasma processing apparatus and a film deposition method solving one or more of the problems discussed above.
More specifically, embodiments of the present invention provide a plasma processing apparatus and a film deposition method that have high plasma controllability and can obtain preferable uniformity of film thickness, coverage performance and film quality across a surface of a substrate.
According to one embodiment of the present invention, there is provided a plasma processing apparatus includes a process chamber, and a susceptor provided in the process chamber and having a substrate receiving area formed in a top surface thereof. A first plasma generator is configured to perform a first plasma process on a first predetermined area in the substrate receiving area. A first radio frequency power source is connected to the first plasma generator and configured to supply first radio frequency power to the first plasma generator. A second plasma generator is configured to perform a second plasma process on a second predetermined area in the substrate receiving area and to be able to change the second predetermined area. A second radio frequency power source is connected to the second plasma generator and configured to supply second radio frequency power to the second plasma generator.
According to another embodiment of the present invention, there is provided a film deposition method. In the film deposition method, a source gas is supplied to a surface of a substrate. A reaction gas capable of producing a reaction product by reacting with the source gas is supplied to the surface of the substrate while converting the reaction gas to plasma, thereby depositing the reaction product on the surface of the substrate. A disproportion of a degree of reaction of the source gas on the surface of the substrate with the reaction gas is corrected by supplying the reaction gas while converting the reaction gas to plasma to an area where the degree of reaction of the source gas on the surface of the substrate with the reaction gas is smaller than the other area.
Additional objects and advantages of the embodiments are set forth in part in the description which follows, and in part will become obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed.
Embodiments of the present invention are described below with reference to accompanying drawings.
<Configuration of Plasma Processing Apparatus>
As illustrated in
The vacuum chamber 1 includes a ceiling plate (ceiling part) 11 provided in a position facing concave portions 24 of the turntable 2 described later, and a chamber body 12. Moreover, a seal member 13 having a ring-like shape is provided in a periphery in an upper surface of the chamber body 12. The ceiling plate 11 is configured to be detachable and attachable from and to the chamber body 12. A diameter dimension (inner diameter dimension) of the vacuum chamber 1 when seen in a plan view is not limited, but can be, for example, set at about 1100 mm.
A separation gas supply pipe 51 is connected to a central part in an upper surface of the ceiling plate 11 and is further in communication with a central part on the upper surface side of a space within the vacuum chamber 1 to supply a separation gas for preventing different process gases from mixing with each other in a central area C.
The turntable 2 is fixed to a core portion 21 having an approximately cylindrical shape at the central part, and is configured to be rotatable by a drive unit 23 in a clockwise fashion as illustrated in
The rotational shaft 22 and the drive unit 23 are accommodated in a casing body 20, and a flange portion on the upper surface side of the casing body 20 is hermetically attached to a lower surface of a bottom portion of the vacuum chamber 1. A purge gas supply pipe 72 for supplying nitrogen gas or the like as a purge gas (separation gas) is connected to an area below the turntable 2.
A peripheral side of the core portion 21 in a bottom part 14 of the vacuum chamber 1 forms a protruding part 12a by being formed into a ring-like shape so as to come to close to the lower surface of the turntable 2.
As shown in
Through holes not illustrated in the drawings are formed in a bottom surface of the concave portion 24 to allow, for example, three lifting pins described later to push up the wafer W from below and to lift the wafer W.
As illustrated in
In the example illustrated in
As illustrated in
Here, in the present embodiment, although an example of arranging a single nozzle in each process area is illustrated, a configuration of providing a plurality of nozzles in each process area is also possible. For example, the second process gas nozzle 32 may be constituted of a plurality of plasma processing gas nozzles, each of which is configured to supply argon (Ar) gas, ammonia (NH3) gas, hydrogen (H2) gas or the like, or maybe constituted of only a single plasma processing gas nozzle configured to supply a mixed gas of argon gas, ammonia gas and hydrogen gas.
The first process gas nozzle 31 forms a first process gas supply part. Moreover, the second process gas nozzle 32 forms a first plasma processing gas supply part, and the third process gas nozzle 33 forms a second plasma processing gas supply part. Furthermore, each of the separation gas nozzles 41 and 42 forms a separation gas supply part.
Each of the nozzles 31, 32, 33, 41 and 42 is connected to each gas supply source not illustrated in the drawings through a flow control valve.
The first process gas nozzle 31 may supply a variety of process gases depending on the intended purpose, and for example, may supply a source gas containing an element that constitutes a major component of a reaction product forming a film. For example, when a film such as SiO2, SiN is deposited, a Si-containing gas such as an organic aminosilane gas is supplied. When a TiN film is deposited, a Ti-containing gas such as TiCl4 is supplied.
A silicon-containing gas may be used as an example of the first process gas supplied from the first process gas nozzle 31 such as DCS [dichlorosilane], HCD [hexachlorodisilane], DIPAS [diisopropylamino-silane], 3DMAS [tris(dimethylamino)silane] gas, BTBAS [bis(tertiary-butyl-amino)silane] or the like. Also, a metal-containing gas maybe used as an example of the first process gas supplied from the first process gas nozzle 31 such as TiCl4 [titanium tetrachloride], Ti (MPD) (THD)2 [titanium methylpentanedionato bis(tetramethylheptanedionato)], TMA [trimethylaluminium], TEMAZ [Tetrakis(ethylmethylamino)zirconium], TEMHF [tetrakis (ethylmethylamino)hafnium], Sr(THD)2 [strontium bis(tetramethylheptanedionato)] or the like.
The plasma processing gases supplied from the second process gas nozzle 32 and the third process gas nozzle 33 can be properly selected depending on intended purpose of the plasma. For example, argon gas or helium (He) gas mainly used for plasma generation, an oxidation gas for oxidizing the first process gas adsorbed on the wafer W and modifying the obtained oxide film (e.g., O2 gas, O3 gas or the like), and a nitriding gas for nitrizing the first process gas adsorbed on the wafer W and modifying the obtained nitrized film (e.g., NH3 gas) are cited as examples. Here, the first and second plasma processing gases discharged from the second and third process gas nozzles 32 and 33 may be the same gas species, or may be different gas species from each other such as O2 gas and O3 gas as long as the second plasma processing gas supplied from the third process gas nozzle 33 is intended to modify the reaction product (film) as well as the first plasma processing gas supplied from the second process gas nozzle 32. Each of the plasma processing gases can be selected depending on a desired plasma process.
For example, argon (Ar) gas or the like is cited as an example of the separation gas supplied from the separation gas nozzles 41 and 42.
As discussed above, in the example illustrated in
Gas discharge holes 34 for discharging each of the above-mentioned gases are formed in each lower surface (the surface facing the turntable 2) of the gas nozzles 31, 32, 33, 41 and 42 along a radial direction of the turntable 2 at a plurality of locations, for example, at regular intervals. Each of the nozzles 31, 32, 33, 41 and 42 is arranged so that a distance between a lower end surface of each of the nozzles 31, 32, 33, 41 and 42 and an upper surface of the turntable 2 is set at, for example, about 1 to 5 mm.
An area under the first process gas nozzle 31 is a first process area P1 to allow the first process gas (i.e., source gas) to adsorb on the wafer W. An area under the second process gas nozzle 32 is a second process area P2 to supply a reaction gas that can react with the source gas adsorbed on the surface of the wafer W and produce a reaction product after being converted to plasma, thereby depositing the reaction product on the surface of the wafer W. An area under the third process gas nozzle 33 is a third process area P3 to supply a reaction gas, while converting the reaction gas to plasma, to an area where a degree of reaction of the source gas with the reaction gas on the surface of the wafer is low, in order to enhance the degree of reaction of the source gas with the reaction gas. In other words, in the third process area P3, a process for correcting a disproportion of the degree of reaction of the reaction product produced by passing through the second process area P2, is performed. To do this, while the first plasma generator 80 for the second process area P2 is configured to generate constant plasma, the second plasma generator 180 for the third process area P3 is configured to be able to change a plasma generation area. In other words, while a single antenna 83 is provided in the first plasma generator 80, a main antenna 83 connected to a radio frequency power source 189, and an auxiliary antenna 84 that is not connected to the radio frequency power source 189 and is electrically floating, are provided in the second plasma generator 180. Thus, the second plasma generator 180 is configured to be able to variously adjust currents flowing through the main antenna 83 and the auxiliary antenna 84, and to be able to generate the plasma in any or a desired area. The detailed configuration of the first and second plasma generators 80 and 180 is described later, and the overall configuration of the plasma processing apparatus is described at first.
As shown in
As illustrated in
As illustrated in
Next, the first plasma generator 80 and the second plasma generator 180 respectively provided above the second and third process gas nozzles 32 and 33 are described below in detail. Here, in the present embodiment, because each of the first plasma generator 80 and the second plasma generator 180 can perform an independent plasma treatment and has a different configuration from each other, each of the first plasma generator 80 and the second plasma generator 180 is independently described below. Hereinafter, the first plasma generator 80 and the second plasma generator 180 may be simply expressed as the “plasma generator 80” and “plasma generator 180” without attaching the language of the “first” and “second” thereto. In this regard, the other components related to the plasma generators 80 and 180 such as radio frequency power sources 85 and 189, and matching boxes 84 and 188 are expressed in a similar manner.
The first plasma generator 80 is configured to wind an antenna 83 constituted of a metal wire or the like, for example, triply around the vertical axis. Moreover, as illustrated in
The antenna 83 is, for example, connected to the radio frequency power source 85 having a frequency of 13.56 MHz and an output power of 5000 W by way of the matching box 84. Then, the antenna 83 is provided to be hermetically separated from an inner area of the vacuum chamber 1. Here, a connection electrode 86 is provided to electrically connect the antenna 83 with the matching box 84 and the radio frequency power source 85.
As illustrated in
As illustrated in
The housing 90 is arranged to cross the diameter of the wafer W in the radial direction of the turntable 2 when the wafer W is located under the housing 90. Here, as illustrated in
An internal atmosphere of the vacuum chamber 1 is sealed by the annular member 82 and the housing 90. More specifically, the annular member 82 and the housing 90 are set in the opening 11a, and then the housing 90 is pressed downward through the whole circumference by a pressing member 91 formed into a frame-like shape along the contact portion of the annular member 82 and the housing 90. Furthermore, the pressing member 91 is fixed to the ceiling plate 11 by volts and the like not illustrated in the drawings. Thus, the internal atmosphere of the vacuum chamber 1 is set to be sealed. Here, in
As illustrated in
As illustrated in
A grounded Faraday shield 95 that is formed so as to approximately fit along an inner shape of the housing 90 and is made of a conductive plate-like body, for example, a metal plate such as a copper plate and the like, is installed in the housing 90. The Faraday shield 95 includes a horizontal surface 95a horizontally formed so as to be along the bottom surface of the housing 90, and a vertical surface 95b extending upward from the outer edge of the horizontal surface 95a through the whole circumference, and may be configured to be approximately hexagon when seen in a plan view.
Upper end edges of the Faraday shield 95 on the right side and the left side extend rightward and leftward, respectively, when seen from the rotational center of the turntable 2 horizontally, and form supports 96. As illustrated in
When an electric field generated by the antenna 83 reaches the wafer W, a pattern (electrical wiring and the like) formed inside the wafer W may be electrically damaged. Because of this, as illustrated in
As illustrated in
As illustrated in
Next, a configuration for generating induction plasma from a plasma processing gas is described below in detail.
More specifically, when each of the upstream and downstream portions of the main antenna 183 in the rotational direction is referred to as a “straight section,” these straight sections 185 are formed along the radial direction of the turntable 2, in other words, along the lengthwise direction of the third process gas nozzle 33. Also, when each of the central and peripheral portions of the main antenna 183 is referred to as a “connecting portion 186,” each of the connecting portions 186 is formed along a tangential direction of the turntable 2. Then, the straight sections 185 and the connecting portions 186 are connected with each other in series at each end through approximately perpendicularly bending portions, and are connected to the radio frequency power source 189 through the matching box 188. In the present embodiment, the frequency and the output power of the radio frequency power source 189 are set at 13.56 MHz and 5000 W, respectively.
As illustrated in
The auxiliary antenna 184 is arranged downstream of and close to the main antenna 183 in the rotational direction of the turntable 2, and is electrically insulated from the main antenna 183. Accordingly, projection areas of the antennas 183 and 184 as seen in a plan view are arranged so as not to overlap each other. Moreover, the auxiliary antenna 184 is arrange to surround a rectangular area slightly smaller than the main antenna as seen in a plan view, and is provided to have approximately the same distance from the rotational center of the turntable and from the outer edge of the turntable 2.
In addition, with respect to the auxiliary antenna 184, the upstream and downstream straight sections 185 are arranged along the third process gas nozzle 33 in a line form. Each of the connecting portions 186 of the auxiliary antenna 184 on the rotational center side and the peripheral side of the turntable 2 is arranged along the tangential direction of the turntable 2. Hence, the straight sections 185 of the main antenna 183 and the straight sections 186 of the auxiliary antenna 184 are parallel with each other.
As illustrated in
More specifically, when the radio frequency power is supplied to the main antenna 183, a radio frequency electric field is generated around an axis in an extending direction of the main antenna 183 due to a radio frequency current flowing through the main antenna 183. Then, the auxiliary antenna 184 is not connected to the radio frequency power source 189, and is in a floating state in which the auxiliary antenna 184 is electrically insulated from the main antenna 183. Accordingly, an inducted electromotive force is generated in the auxiliary antenna 184, and an inducted current flows through the auxiliary antenna 184 due to the electromagnetic induction between the main antenna 183 and the auxiliary antenna 184 caused by the radio frequency electric field formed around the main antenna 183.
Here, a magnitude of the inducted current flowing through the auxiliary antenna 184 is investigated. A resonant frequency f (Hz) is expressed by the following formula.
f=1/(2π√{square root over ( )}(L×C))
Here, f expresses a frequency of the radio frequency power supplied to the main antenna 183 (auxiliary antenna 184); L expresses an inductance (H) of the auxiliary antenna 184; and C expresses a capacitance value (F) of the auxiliary antenna 184. The following formula is obtained by converting the above formula to a formula that expresses the capacitance value C.
C=1/(47π2×f2×L)
Then, when the frequency f and the inductance L are made, for example, 13.56 MHz and 2.62 μH, respectively, and assigned to the above formula, the capacitance value C that causes a series resonance in the auxiliary antenna 184 is about 52.6 pF. In other words, when the capacitance value C of the auxiliary antenna 184 is 52.5 pF, the series resonance occurs in the auxiliary antenna 184 due to the radio frequency electric field travelling to the auxiliary antenna 184 from the main antenna 183, and plasma is generated not only in an area under the main antenna 183 but also in an area under the auxiliary antenna 184. Therefore, in the present embodiment, the auxiliary antenna 184 is configured to generate resonance in the auxiliary antenna 184, and further to be able to adjust a state of the resonance.
More specifically, as illustrated in
A configuration example of such a capacitance variable mechanism 200 and a drive unit is described below. For example, a pair of opposite electrodes (not illustrated in the drawings) is provided in the capacitance variable mechanism 200, and the drive mechanism is connected to one of the pair of opposite electrodes. The drive mechanism changes a distance between the pair of opposite electrodes by moving one of the pair of opposite electrodes, thereby adjusting the capacitance value of the capacitance variable mechanism 200, which is, in other words, the capacitance value of the auxiliary antenna 184. Then, when the currents flow through the main antenna 183 and the auxiliary antenna 184 in the opposite direction to each other due to the impedance of the auxiliary antenna 184 as seen in a plan view, as illustrated in
The antennas 183 and 184 described above are arranged so as to be hermetically separated from the inner area of the vacuum chamber 1 similar to the antenna 83 in the first plasma generator 80. The ceiling plate 11 above the third process gas nozzle 32 has an approximately fan-shaped opening as seen in a plan view, and the opening is hermetically closed by a housing 190, for example, made of quartz. Because the configuration of the housing 90 and a method of fixing the housing 190 to the ceiling plate 11 are similar to those of the housing 90 described with the first plasma generator 80, the description is omitted.
Next, an auxiliary plasma process performed by the second plasma generator 180 on an area where the degree of reaction is low after the wafer W passes through the first plasma generator 80 is described below. The wafer W revolves due to the rotation of the turntable 2 and passes through the areas P1, P2 and P3 under the process gas nozzles 31, 32 and 33, respectively. Because of this, in the wafer W on the turntable 2, the speeds (angular rates) when passing through the areas 21, P2 and P3 differ from each other at the edge on the rotational center side and at the edge on the peripheral side of the turntable 2. More specifically, when the diameter dimension of the wafer W is 300 mm (12 inches), the speed at the edge on the rotational center side is one third as fast as that of the edge on the peripheral side.
More specifically, when a distance from the rotational center of the turntable 2 to the edge of the wafer W on the rotational center side is expressed by “s, ” the circumference DI of a circle on which the edge of the wafer W on the rotational center side passes equals to (2×π×s). In the meantime, under the same condition as the above, the circumference DO of a circle on which the edge of the wafer W passes equals to (2×π×(s+300)). On this occasion, the wafer W moves the circumferences DI and DO for the same period of time by the rotation of the turntable 2. Hence, when speeds of the edges of the wafer W on the rotational center side and the peripheral side are expressed by VI and VO, respectively, a ratio R (VI÷VO) of VI to VO of the speeds equals to (s÷(s+300)). Then, when the distance s is 150 mm, the ratio R equals to ⅓.
Accordingly, when plasma whose reactivity with a component of a source gas adsorbed on the wafer W is not very high, is used, a degree of reaction of the source gas with a reaction gas is liable to be lower on the peripheral side of the wafer W than on the central side if the reaction gas is merely converted to plasma in the vicinity of the second process gas nozzle 32.
Therefore, in order to correct such a disproportion of the degree of reaction, the plasma processing apparatus according to the first embodiment of the present invention is configured to be able to locally generate plasma in any area in the radial direction of the turntable 2, thereby correcting the disproportion of the degree of reaction and improving uniformity of a film thickness and film quality across the surface of the wafer W. As discussed above, with respect to the local plasma generation, the generation area of plasma can be controlled by changing a reactance by the capacitance variable mechanism 200 connected to the auxiliary antenna 200, thereby changing the impedance of the auxiliary antenna 184.
In addition to that, a shape of the projection portion 92 is adjusted in order to perform a uniform plasma process on the wafer W. More specifically, as illustrated in
As illustrated in
Each of the slits 197 is not in communication with other adjacent slits 197. In other words, the metal plate that forms the Faraday shield 196 surrounds each of the slits 197 and extends in the circumferential direction. The slits 197 are formed in a direction perpendicular to the lengthwise direction of the antennas 183 and 184, and are arranged at a plurality of locations at equal distances from each other along the lengthwise direction of the antennas 183 and 184 under the antennas 183 and 184. The slits 197 are not formed in a position right above the third process gas nozzle 33, thereby preventing the plasma processing gas in the process gas nozzle 33 from converting to plasma.
As illustrated in
Therefore, in the present embodiment, in order to equalize the amount of magnetic field component going toward the wafer W from the main antenna 183 through each the slits 197, the straight sections 185 of the antenna 183 are arranged across the position through which the wafer W passes, and the slits 197 are formed under the straight sections 185. Moreover, the slits 197 are not formed under the bending portions extending from the both ends of the straight sections 185, and the conductive plate that forms the Faraday shield 195 is arranged, thereby blocking not only the electric field component but also the magnetic field component. Thus, the generated amount of plasma is made uniform in the radial direction of the turntable 2.
Hence, the slit 197 at any position is seen, the opening width of the slit 197 is uniform along the lengthwise direction of the slit 197. Then, the opening widths of the slits 197 are adjusted to be made the same as the other slits 197 in the Faraday shield 197.
An insulating member 194, for example, made of quartz is provided between the Faraday shield 195 and the antennas 183 and 184 described above in order to insulate the Faraday shield 195 from the antennas 183 and 184. The insulating member 194 is formed into an approximately box-like shape with an opening on the upper side. In
As illustrated in
In the present specification, one of the exhaust openings 61 and 62 is referred to as a first opening 61 and the other of the exhaust openings 61 and 62 is referred to as a second opening 62. Here, the first exhaust opening 61 is formed between the separation gas nozzle 42 and the first plasma generator 80 located on the downstream side of the separation gas nozzle 42 in the rotational direction of the turntable 2. Furthermore, the second exhaust opening 62 is formed between the second plasma generator 180 and the separation area D on the downstream side of the second plasma generator 180 in the rotational direction of the turntable 2.
The first exhaust opening 61 is provided to evacuate the first process gas and the separation gas, and the second exhaust opening 62 is provided to evacuate the plasma processing gas and the separation gas. Each of the first exhaust opening 61 and the second exhaust opening 62 is, as illustrated in
As described above, because the housings 90 and 190 are arranged from the central area C side to the outer peripheral side, a gas flowing from the upstream side in the rotational direction of the turntable 2 to the plasma process area P2 and P3 may be blocked from going to the evacuation opening 62 by the housings 90. In response to this, a groove-like gas flow passage 101 (see
As shown in
As discussed above, because the housings 90 and 190 are formed at the location close to the central area C, the core portion 21 supporting the central portion of the turntable 2 is formed on the rotational center side so that a portion on the upper side of the turntable 2 is arranged apart from the housing 90. Due to this, the various gases are more likely to mix with each other at the central area C side than at the outer peripheral side. Hence, by forming the labyrinth structure 110 above the core portion 21, a flow path can be made longer to be able to prevent the gases from mixing with each other.
More specifically, the labyrinth structure 110 has a wall part vertically extending from the turntable 2 toward the ceiling plate 11 and a wall part vertically extending from the ceiling plate 11 toward the turntable 2 that are formed along the circumferential direction, respectively, and are arranged alternately in the radial direction of the turntable 2. In the labyrinth structure 110, for example, a first process gas discharged from the first process gas nozzle 31 and heading for the central area C needs to go through the labyrinth structure 110. Due to this, the first process gas decreases in speed with the decreasing the distance from the central area C and becomes unlikely to diffuse. As a result, the first process gas is pushed back by the separation gas supplied to the central area C before reaching the central area C. Moreover, other gases likely to head for the central area C are difficult to reach the central area C by the labyrinth structure 110 in a similar way. This prevents the process gases from mixing with each other in the central area C.
On the other hand, the separation gas supplied from the separation gas supply pipe 51 is likely to diffuse swiftly in the circumferential direction at first, but decreases in speed as going through the labyrinth structure 110. In this case, nitrogen gas is likely to intrude into a very narrow area such as a gap between the turntable 2 and the projection portion 92, but flows to a relatively large area such as an area where the transfer arm 10 moves in and out of the vacuum chamber 1 because the labyrinth structure 110 decreases the flowing speed thereof. Because of this, nitrogen gas is prevented from flowing into a space under the housings 90 and 190.
As illustrated in
As illustrated in
The wafer W is transferred between the concave portion 24 of the turntable 2 and the transfer arm 10 at a position where the concave portion 24 of the turntable 2 faces the transfer opening 15. Accordingly, lift pins and an elevating mechanism that are not illustrated in the drawings are provided at a position under the turntable 2 corresponding to the transferring position to lift the wafer W from the back surface by penetrating through the concave portion 24.
Moreover, as illustrated in
Next, working examples performed to check that plasma can be generated in any area by the second plasma generator 190, are described below.
As shown in
Then, the capacitance value of the capacitance variable mechanism 200 of the auxiliary antenna 184 was variously changed as the following working examples 1 through 4 in TABLE 1, and current values flowing through the antennas 183 and 184 were measured. Then, plasma was generated in the chamber under the conditions of each of the working examples 1 through 4, and emitting states of the plasma were photographed. In the working examples, a mixed gas of argon (Ar) and oxygen (O2) was used as the plasma processing gas.
Moreover, as put down in TABLE 1 with the capacitance value, the current values flowing through the main antenna 183 and the auxiliary antenna 184 also changed depending on the emitting states of plasma in
The plasma can be generated in a desired area of the concave portion 24 on which the wafer W is placed by utilizing the properties. More specifically, when a disproportion of a degree of reaction and a film thickness occur caused thereby in the first plasma generator 80, the second plasma generator 180 generates plasma at a location where the degree of reaction is low, thereby performing a modification process for correcting the disproportion of the degree of reaction. Thus, the uniformity of film thickness, film quality and coverage properties across the wafer W can be enhanced.
[Film Deposition Method]
Next, a film deposition method according to a first embodiment of the present invention is described below.
To begin with, in carrying wafers W into the vacuum chamber 1, the gate valve G is opened. Then, the wafers W are placed on the turntable 2 by the transfer arm 10 through the transfer opening 15 while rotating the turntable 2 intermittently.
Next, the gate valve G is closed and the wafers W are heated to a predetermined temperature by the heater unit 7. Subsequently, the first process gas is discharged from the first process gas nozzle 31 at a predetermined flow rate, and plasma processing gases are supplied from the second process gas nozzle 32 and the third process gas nozzle 33 at predetermined flow rates, respectively.
The inside of the vacuum chamber 1 is adjusted to a predetermined pressure by the pressure controller 65. The radio frequency power sources 85 and 189 supply radio frequency power of predetermined outputs to antennas 83 and 183, respectively.
The first process gas adsorbs on each surface of the wafers W in the first process area P1 by the rotation of the turntable 2. The wafers W on which the first process gas adsorbs pass through the separation area D by the rotation of the turntable 2. In the separation area D, the separation gas is supplied to each of the surfaces of the wafers W, and unnecessary physically absorbed materials with respect to the first process gas are removed.
The wafers W subsequently pass through the second process area P2 by the rotation of the turntable 2. In the second process area P2, a reaction gas supplied from the second process gas nozzle 32 is converted to plasma, and is supplied to each of the surfaces of the wafers W. The reaction gas reacts with the source gas (first process gas) adsorbed on each of the surfaces of the wafer W, and produces a reaction product, a molecular layer of which is deposited on each of the surfaces of the wafers W.
Next, the wafers W having passed through the second process area P2 pass through the third process area P3 by the rotation of the turntable 2. In the third process area P3, a reaction gas supplied from the third process gas nozzle 33 is converted to plasma in a desired area, thereby correcting a disproportion of a degree of reaction in the second process area P2. In general, because angular rates differ from each other on the central side and the peripheral side of the turntable 2, and because the supply of the reaction gas and the reaction with the source gas are likely to be insufficient, a current flowing through the main antenna 183 and an inducted current flowing through the auxiliary antenna 184 are adjusted so that the reaction gas on the peripheral side is converted to plasma. Thus, the plasma process insufficient in the second process area P2 can be complemented, and the disproportion can be corrected.
The wafers W processed by using the plasma pass through the separation area D by the rotation of the turntable 2. The separation area D is an area to separate the first process area P1 from the third process area P3 so that the unnecessary purge gas and the modifying gas do not intrude into the first process area P1.
In the present embodiment, by keeping the turntable 2 rotating, the adsorption of the first process gas on the wafers W, the reaction of the reaction gas with the first process gas adsorbed on the wafers W, and the plasma modification to the area where the reaction is insufficient are performed in this order many times. In other words, the film deposition process by ALD and the modification process of the deposited film are performed many times by rotating the turntable 2.
Here, in the plasma processing apparatus of the present embodiment, the separation areas D are arranged between the process areas P1 and P2 on both sides in the circumferential direction of the turntable 2. Because of this, in the separation areas D, each of the process gas and the plasma processing gases flows toward each of the exhaust openings 61 and 62 while being prevented from mixing with each other.
Next, in the film deposition method according to the first embodiment of the present invention, a process of filling a recessed pattern formed in a wafer W with a SiO2 film by using an organic aminosilane gas as a source gas is described below.
In this process, because intense plasma creates the O groups while moderate plasma creates the OH groups, the OH groups are likely to increase on the peripheral side of the turntable 2 where the plasma is likely to weaken, and the film thickness on the peripheral side is likely to become thicker than that on the central side. Hence, by generating the plasma in the peripheral area of the turntable 2 and the concave portion 24 in the third process area P3, the state illustrated in
In the modification process in
In contrast, in the film deposition of a SiN film and the like, when the plasma process is insufficient, nitriding becomes insufficient, which is likely to decrease film quality and unlikely to acquire the sufficient film thickness. Even in such a case, by performing the additional and complementary plasma process on the area where the plasma process is likely to become insufficient, for example, on the periphery of the turntable 2.
Thus, according to the plasma processing apparatus and the film deposition method of the first embodiment of the present invention, the plasma process with high uniformity can be performed on the wafer W by providing the second plasma generator 180 that can selectively perform the plasma process only on a desired area in addition to the first plasma generator 80 that can perform the whole surface of the wafer W.
As illustrated in
Accordingly, the plasma process can be independently performed on an area where the degree of plasma process is insufficient in the second process area P2, which makes it possible to improve the uniformity of plasma process across the surface of the wafer W.
Thus, the second plasma generator 280 may be configured to perform the plasma process only in a desired area by providing the plurality of independent small plasma generator 287. The local plasma generation unit differs from that of the first embodiment, but can have a similar effect to the first embodiment in the film deposition method.
In the first and second embodiments, the plasma processing apparatus and the film deposition method using the turntable 2 are described, but the embodiments of the present invention can be applied to a plasma processing apparatus and a film deposition method using an unrotatable susceptor as a substrate receiving area by providing the plasma generator 80 whose plasma conditions are fixed and the plasma generator 180 or 280 that can change the process area, and the amount of plasma process can be adjusted.
Moreover, even when a single wafer processing type turntable that receives only a single wafer W is used, the embodiments of the present invention can be applied because the uniformity across the surface of the wafer W can be improved by the local plasma process. In addition, even in the single wafer processing type, because the plasma process on the periphery of the turntable 2 is likely to be insufficient due to the difference of angular rate similarly to the embodiments of the present invention, the embodiments of the present invention can be preferably applied to the single wafer processing type plasma processing apparatus.
According to the embodiments of the present invention, there is provided a plasma processing apparatus and a film deposition method that can compensate a disproportion of a plasma process.
All examples recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority or inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-240059 | Dec 2015 | JP | national |
