Patent Application
20150211118
The present invention relates to a vapor deposition apparatus for use in, for example, vertical shower head MOCVD (metal organic chemical vapor deposition)
MOCVD technology and apparatus (vapor deposition apparatus) has been conventionally used in the manufacture of light-emitting diodes and semiconductor laser devices. MOCVD grows crystals of compound semiconductor material by supplying, to a reaction chamber, an organic metal gas (e.g., trimethylgallium (TMG) or trimethylaluminum (TMA)) and a hydride gas (e.g., ammonia (NH3), phosphine (PH3), or arsine (AsH3)) as source gases which contribute to film formation.
In MOCVD, source gases (an organic metal gas and a hydride gas) are supplied together with an inert gas, such as hydrogen or nitrogen, to a reaction chamber. The gaseous mixture is then heated so that it reacts on a predetermined target substrate to grow crystals of compound semiconductor material on the target substrate. A requirement in the manufacture of crystals of compound semiconductor material by MOCVD is to ensure a maximum yield and productivity while improving the quality of the grown compound semiconductor crystals, all in a cost effective manner.
The shower head 210 includes: the gas inlets 214 through which a source gas is introduced; a gas distribution space 213 for uniformly and broadly diffusing the source gas introduced through the gas inlets 214; and a shower plate 211, having, at predetermined intervals therein, gas channels 215 for supplying the source gas diffused in the gas distribution space 213 to the reaction chamber 221. The shower head 210 also includes a cooling medium channel 218 around the gas channels 215. A cooling medium flows in the cooling medium channel 218 so as to regulate the temperature of the gas channels 215.
A rotation axis 232 is provided in a lower central part of the reaction chamber 221 and supported by an actuator (not shown) so as to be freely rotatable. On the tip of the rotation axis 232 is there attached a disc-shaped substrate support 230 on which a target substrate 231 is placed opposite a face of the shower plate 211 from which the source gas is supplied. A heater 233 for heating the substrate support 230 is attached below the substrate support 230. A gas discharge section 225, including gas outlets 226 for externally discharging the gas in the reaction chamber 221, is provided in a lower part of the reactor 220.
To grow crystals of compound semiconductor material on the target substrate 231 by using the vapor deposition apparatus 200 thus configured, the target substrate 231 is placed on the substrate support 230, followed by the rotation of the substrate support 230 driven by the rotation of the rotation axis 232. Next, the target substrate 231 is heated to a predetermined temperature by the heater 233 via the substrate support 230. Under these conditions, the source gas is supplied from the gas channels 215 penetrating through the shower plate 211 to the reaction chamber 221 inside the reactor 220. The source gas thus supplied is heated by the heat of target substrate 231 and undergoes chemical reactions to grow semiconductor crystalline films on the target substrate 231.
To supply two or more source gases to grow crystals of compound semiconductor material on the target substrate 231, the source gases are introduced through different gas inlets 214 and mixed in the gas distribution space 213 of the shower head 210. The mixed gas is supplied from the gas channels 215 penetrating through the shower plate 211 to the reaction chamber 221 inside the reactor 220.
The vapor deposition apparatus of this type is required to create a uniform gas flow rate, gas mix ratio, etc. across all the gas channels so that the film can be formed with a uniform thickness, composition ratio, etc. across the entire surface of the target substrate.
To respond to this requirement, for example, Patent Literature 1 discloses a vacuum manufacturing device in which a gas supplied from a plurality of gas supply systems each provided with an independent mass flow controller (flow rate adjusting section) is passed through gas spaces, one being provided for each gas supply system, before being fed into the vacuum chamber. The vacuum manufacturing device is capable of adjusting the gas flow rate for the individual gas supply systems. The device is therefore capable of forming a film with a uniform thickness across the entire surface of the target substrate.
As another example, Patent Literature 2 discloses a semiconductor manufacturing device including a shower head provided with a plurality of gas ejection holes to supply a gas to the surface of a target substrate, the shower head being divided radially from its center into a plurality of blocks so that the gas flow rate can be controlled independently in each block. The semiconductor manufacturing device is capable of adjusting the distribution of gas concentration block by block. The device is therefore capable of forming a film with a uniform thickness across the entire surface of the target substrate.
Patent Literature 2 also discloses a semiconductor manufacturing device including a shower head provided with a plurality of gas ejection holes to supply a gas to the surface of a target substrate, the device having a face, opposite the gas ejection holes, which has holes at corresponding parts of the face so that stoppers for the gas ejection holes can be inserted in the holes. The semiconductor manufacturing device is capable of adjusting the distribution of gas concentration by selectively opening gas ejection holes to enable gas supply to the surface of the target substrate and inserting stoppers to stop the gas supply. The device is therefore capable of forming a film with a uniform thickness across the entire surface of the target substrate.
Patent Literature 2 further discloses a semiconductor manufacturing device including a shower head provided with an umbrella-shaped gas ejection face which is separated from the surface of a target substrate by a distance which gradually decreases farther away from the center of the face toward the periphery. The semiconductor manufacturing device restrains increases of gas passage area which could occur with increasing distance from the center toward the periphery. The device is therefore capable of forming a film with a uniform thickness across the entire surface of the target substrate.
The vapor deposition apparatus 200, illustrated in
For these reasons, in the vacuum manufacturing device of Patent Literature 1 and the semiconductor manufacturing device of Patent Literature 2, the region where a film is to be formed is divided into a plurality of subregions in each of which a film can be formed with a uniform thickness, and each subregion is provided with an independent gas supply system, so that the flow rate can be adjusted individually for each gas supply system.
Meanwhile, for example, a large-capacity vapor deposition apparatus which forms a film on multiple 6-inch substrates in a single batch is required to form a film covering an area as large as about φ=600 mm with a uniform thickness. If the large-capacity vapor deposition apparatus is configured so that a region thereof where a film is to be formed is divided into a plurality of subregions, the subregions are too numerous to implement a simple design because the same number of mass flow controllers (flow rate adjusting sections) and piping system members as the subregions are needed.
As mentioned above, Patent Literature 2 discloses a semiconductor manufacturing device capable of selectively opening each gas ejection hole to enable gas supply and inserting a stopper to stop the gas supply. A large-capacity vapor deposition apparatus would, however, need more than a few thousand gas ejection holes. It is therefore complex and laborious to determine, for each one of the gas ejection holes, whether it should be opened or closed by inserting a stopper, so that a film can be formed with a uniform thickness across the entire surface of the target substrate.
Patent Literature 2, as mentioned above, also discloses a semiconductor manufacturing device including a shower head provided with an umbrella-shaped gas ejection face which is separated from the surface of the target substrate by a distance which gradually decreases from the center of the face toward the periphery. Advanced fabrication technology is necessary, however, to enable symmetric fabrication while maintaining a desired inclination angle. Especially, for a large-capacity vapor deposition apparatus, the shower head has a large gas ejection face to be fabricated. It is thus extremely difficult to fabricate the gas ejection face of the shower head in an umbrella-like shape so that a film can be formed with a uniform thickness across the entire surface of the target substrate.
The present invention, conceived in view of these problems, has an object of providing a vapor deposition apparatus which is simple and convenient to design and assemble and allows for quality improvement in terms of the thickness, composition ratio, etc. of a film formed on a target substrate by supplying gas more uniformly in amount on the surface of a target substrate in a reaction chamber.
To attain the object, the vapor deposition apparatus in accordance with the present invention includes: a reactor for housing a target substrate on which a thin film is to be formed by vapor deposition; a shower head having: a gas inlet for introducing a gas; a gas distribution space for diffusing the gas; and a shower plate having a plurality of gas channels for supplying the gas from the gas distribution space into the reactor; and a gas outlet for externally discharging the gas from the reactor, the gas distribution space of the shower head having the shower plate as a bottom face thereof, the gas distribution space having a first space and a second space, the first space being farther from the gas outlet of the reactor than is the second space, the first space being formed so as to be taller than the second space.
According to the invention, in the gas distribution space of the shower head, the first space, which is located relatively far from the gas outlet, is formed so as to be taller than the second space, which is located relatively close to the gas outlet. In other words, the present invention makes it possible to supply gas uniformly in amounton the surface of the target substrate in the reaction chamber by the structural shape of the gas distribution space. This in turn improves quality of the film formed on the target substrate in terms of its thickness, composition ratio, etc. Hence, the invention can provide a vapor deposition apparatus at low design and assembly cost.
The vapor deposition apparatus in accordance with the present invention, as described in the foregoing, is such that the gas distribution space of the shower head has the shower plate as a bottom face thereof and is provided with a first space and a second space, the first space being farther from the gas outlet of the reactor than is the second space, and also that the first space is formed so as to be taller than the second space.
The invention advantageously provides a vapor deposition apparatus which is simple and convenient to design and assemble and allows for quality improvement in terms of the thickness, composition ratio, etc. of a film formed on a target substrate by supplying gas uniformly in amount on the surface of a target substrate in a reaction chamber.
(A) and (B) of
(A) and (B) of
(A), (B), and (C) of
(A) and (B) of
(A) and (B) of
The following will describe an embodiment of the present invention in reference to
A vapor deposition apparatus 1A in accordance with the present embodiment is described in reference to
The vapor deposition apparatus 1A, as illustrated in
The shower head 10 includes: the gas inlets 14 through which a source gas is introduced; a gas distribution space 13 for uniformly and broadly diffusing the source gas introduced through the gas inlets 14; and a shower plate 11 for supplying the source gas diffused in the gas distribution space 13 to the reaction chamber 21. The shower head 10 also includes a cooling medium channel 18 around gas channels 15 formed in the shower plate 11. A cooling medium flows in the cooling medium channel 18 so as to regulate the temperature of the gas channels 15.
A rotation axis 32 is provided in a lower central part of the reaction chamber 21 and supported by an actuator (not shown) so as to be freely rotatable. On the tip of the rotation axis 32 is there attached a disc-shaped substrate support 30 on which a target substrate 31 is placed opposite a face of the shower plate 11 from which the source gas is supplied. A heater 33 for heating the substrate support 30 is attached below the substrate support 30. A gas discharge section 25, including gas outlets 26 for externally discharging the gas in the reaction chamber 21, is provided in a lower part of the reactor 20.
The gas distribution space 13 of the vapor deposition apparatus 1A is, as illustrated in
In other words, in the present embodiment, the gas distribution space 13 includes the first space 131 located relatively far from the gas outlets 26 of the reactor 20 and the second space 132 located relatively close to the gas outlets 26 of the reactor 20. Additionally, the first space 131 is formed so as to be taller than the second space 132.
Next, the configuration of the shower plate 11 is described in reference to
The vapor deposition apparatus 1A, as illustrated in
The gas supply rates from the gas channels 15 penetrating through the shower plate 11 vary slightly from one gas channel 15 to another under these conditions, due to the effect of the discharge gas flow to the gas outlets 26. Specifically, the gas supply rates from those gas channels 15 which are close to the gas outlets 26 and near the periphery are a maximum, and the gas supply rates from those gas channels 15 which are far from the gas outlets 26 and near the center are a minimum.
The vertical dimensions of the device members, such as the heater 33, which are provided inside the reaction chamber 21 may be roughly equal to those in the case of a compact vapor deposition apparatus. In other words, when these device member are disposed in the reaction chamber 21, the vertical distance from the source gas supply face of the shower plate 11 to the gas outlets 26 does not need to be larger than the corresponding distance in the case of a compact vapor deposition apparatus.
As mentioned earlier, undesirably, in the large-capacity vapor deposition apparatus 1A in which the film forming region and the gas supply region are large, the difference in distance to the gas outlets 26 is large between the gas channels 15 located closest to the periphery of the shower plate 11 and the gas channels 15 located at the center of the shower plate 11, and so is the difference in gas supply rate. These are issues which should be addressed.
Accordingly, in the vapor deposition apparatus 1A in accordance with the present embodiment, the gas distribution space 13 is formed in a hat-like shape, thereby restraining the gas supply ratesfrom the gas channels 15 located right under the second space 132 where the gas supply rates are likely to be affected by the discharge gas flow to the gas outlets 26. As a result, the vapor deposition apparatus 1A makes it possible to supply uniform gas amounts from the gas channels 15 in the gas supply region.
The following will describe another embodiment of the present invention in reference to
A vapor deposition apparatus 1B in accordance with the present embodiment is described in reference to
The vapor deposition apparatus 1B in accordance with the present embodiment, as illustrated in
In other words, the shower head 10 of the vapor deposition apparatus 1B, as illustrated in
The third space 133 is formed in a columnar shape which has a large enough diameter to dispose the gas inlets 14 located closest to the periphery within the diameter so that the source gases introduced through the gas inlets 14 are collectively mixed.
Next, the configuration of diffusion plate 50 is described in detail in accordance with
The diffusion plate 50 has, as illustrated in
Accordingly, in the present embodiment, the diffusion holes 51 are formed only in a central part (gas flow region) of the diffusion plate 50 as illustrated in
According to the configuration, the diffusion plate 50 has no diffusion holes 51 along its periphery. The gas flow to the gas channels 15 along the periphery of the shower plate 11 is therefore restricted. Meanwhile, the gas passing through the gas flow region in the central part of the diffusion plate 50 is likely to flow to the gas channels 15 near the center of the shower plate 11. As a result, the gas can be fed to the gas channels 15 of the shower plate 11 at uniform gas supply rates, respectively.
To restrict passage of gas along the periphery of the diffusion plate 50, for example, the diffusion holes 51 may be distributed more toward the central part of the diffusion plate 50 from the periphery of the diffusion plate 50, or the diffusion holes 51 may become larger in diameter toward the central part from the periphery.
As described above, in the vapor deposition apparatus 1B in accordance with the present embodiment, the gas distribution space 13 is formed in a hat-like shape, and the third space 133 and the diffusion plate 50 are provided, so that the gas distribution space 13 can be divided into three spaces (stages) and an upstream gas passage region is narrowed down to the central part. The configuration therefore restrains the gas supply ratesfrom those gas channels 15, of the shower plate 11, which are located right under the second space 132 (these gas supply rates are likely to be affected by the discharge gas flow to the gas outlets 26) and thereby makes it possible to supply the gas uniformly in amount from the gas channels 15 in the gas supply region of the shower plate 11.
The following will describe gas flow rate distribution simulation for the vapor deposition apparatus 1B in accordance with the present embodiment in comparison with gas flow rate distribution simulation for a conventional vapor deposition apparatus 200 in reference to (A) and (B) of
As illustrated in (A) and (B) of
In the ⅛π-model of the vapor deposition apparatus 1B in accordance with the present embodiment, gas channels 15 (φ=1 mm) are also formed at 5-mm intervals in a gas supply region (φ=570 mm) of a shower plate 11.
The gas distribution space 13 of a hat-like shape, provided in the shower head 10, shares the same central axis with the first space 131 and the second space 132. The first space 131 has a columnar shape and measures 25 mm in height and 420 mm in diameter (φ). The second space 132, located below the first space 131, has a columnar shape and measures 3 mm in height and 570 mm in diameter (φ).
Above the hat-shaped gas distribution space 13 is there provided a diffusion plate 50 which separates the third space 133 from the second space 132. The diffusion plate 50 has a columnar shape and measures 5 mm in height and 570 mm in diameter (φ).
A gas flow region of the diffusion plate 50, which has the same diameter of 420 mm as the first space 131, has, at 5-mm intervals, diffusion holes 51 (φ=2 mm) through which the source gases introduced to the third space 133 can flow to the first space 131.
In contrast, as illustrated in (A) of
In the conventional vapor deposition apparatus 200, the gas channels 215 (φ=1 mm) are formed at 5-mm intervals in a gas supply region (φ=570 mm) of a shower plate 211 as illustrated in (B) of
Simulated gas flow rate distributions obtained using the models are represented in
Also in
Referring to
In contrast, in the ⅛π-model of the conventional vapor deposition apparatus 200, the gas flow rate increases linearly farther away from the center of the shower head 210 where the rate is relatively unlikely to be affected by the discharge gas flow toward the gas outlets 226 to the periphery where the rate is relatively likely to be affected by the discharge gas flow to the gas outlets 226. As a result, the gas flow rate from the gas channels 215 located 125 mm to 275 mm away from the center of the shower head 210 exhibits a rate of change (=((Maximum−Minimum)/Mean Value)×100) of about Δ5.7%.
As witnessed above, in the vapor deposition apparatus 1B in accordance with the present embodiment, the gas flow rates from those gas channels 15 close to the gas outlets 26 of the shower plate 11 and the gas flow rates from those gas channels 15 far from the gas outlets 26 of the shower plate 11 are made practically equal to each other by forming the gas distribution space 13 having a hat-like shape in which the source gas introduced through the gas inlets 14 is uniformly and broadly diffused. In other words, the gas is supplied uniformly in amount on the surface of the target substrate 31 in the reaction chamber 21 by means of the structural shape of the gas distribution space 13. This in turn improves quality of the film formed on the target substrate 31 in terms of its thickness, composition ratio, etc. Hence, the embodiment can provide a vapor deposition apparatus 1B at low design and assembly cost.
The aforementioned embodiment should be regarded as illustrative, not restrictive. Specifically, in the description above, the diffusion plate 50 is provided in an upper part of the hat-shaped gas distribution space 13 in the vapor deposition apparatus 1B so that the gas passage region is narrowed down farther upstream. Therefore, the shape of the gas distribution space 13 is not limited to this provided that the gas passage region is narrowed down farther upstream. The gas distribution space 13 may take a different shape. For example, the gas distribution space 13 of the vapor deposition apparatus 1B in accordance with the present embodiment may take a shape determined according to the positions of the gas outlets 26, the diameter(s) of the gas channels 15, the intervals between the gas channels 15, etc.
In this viewpoint, (A), (B), and (C) of
The gas distribution space 13 illustrated in (A) of
The gas distribution space 13 illustrated in (B) of
The gas distribution space 13 illustrated in (C) of
The variations described in reference to (A) to (C) of
The following will describe a further embodiment of the present invention in reference to
A vapor deposition apparatus in accordance with the present embodiment is described in reference to
The shower head 10A in accordance with the present embodiment differs from the shower head 10 in the vapor deposition apparatus 1A or the vapor deposition apparatus 1B in that an adjustment mechanism is provided which is capable of adjusting the height of a ceiling face from a floor face of a second space 132.
In other words, as illustrated in
The distribution space forming mechanism 12 includes a second space forming mechanism 122 and a first space forming mechanism 121. The second space forming mechanism 122 constitutes the second space 132 or a part of the second space 132, whereas the first space forming mechanism 121, by being coupled to the second space forming mechanism 122 as an upper layer member for the second space forming mechanism 122. constitutes a first space 131. The first space forming mechanism 121 is configured so that a diffusion plate 50 can be attached to it.
A concrete example of the distribution space forming mechanism 12 in the shower head 10A is described in reference to
The shower head 10A, as illustrated in
The shower plate 11a is a columnar member. On the top of the shower plate 11a is there formed a concave face including a circular region, with a diameter of R2, which is lower in height than the periphery by H3. The shower plate 11a has a plurality of gas channels 15 extending from the concave face to the bottom face.
The distribution space forming mechanism 12a is constituted by either a first space forming member 121a or the first space forming member 121a and at least one second space forming member 122a (as a second space-height adjusting member). The first space forming member 121a is of a cylindrical shape and has formed therein a hole with a diameter of R1 and a height of H1.
The second space forming member 122a is of a ring shape and has formed therein a hole with a diameter of R2 and a height of H2.
The first space forming member 121a is configured so that the diffusion plate 50, provided with a plurality of diffusion holes 51, can be attachable onto it within the R1 (diameter) region.
These members are configured so that they can be coupled together by aligning the central axes of their cylindrical or columnar shapes.
When the distribution space forming mechanism 12 includes only the first space forming member 121a, as illustrated in (A) of
In contrast, when the distribution space forming mechanism 12 is constituted by the first space forming member 121a and one second space forming member 122a, as illustrated in (B) of
In this manner, in the present embodiment, the height of the second space 132 is adjustable by means of the number of second space forming members 122a used.
Next, another concrete example of the distribution space forming mechanism 12 in the shower head 10A is described in reference to
The shower head 10A, as illustrated in
The shower plate 11b includes a columnar member. The shower plate 11b is holed, in a central part (φ=R4) thereof, by a plurality of gas channels 15 extending from the top face to the bottom face thereof.
The distribution space forming mechanism 12b, provided as an upper layer member for the shower plate 11b, includes: a cylindrical first space forming member 121b which has formed therein a hole with a diameter of R1 and a height of H1; and a second space forming member 122b (as a second space-height adjusting member) which has a hole with a diameter of R4 and which also has a bellows structure capable of adjusting its height in the range of H5 (minimum) to H4 (maximum).
The first space forming member 121b is configured so that a diffusion plate 50, provided with a plurality of diffusion holes 51, can be attached to it within the R1 (diameter) region.
These members are configured so that they can be coupled together by aligning the central axes of their cylindrical or columnar shapes.
(A) and (B) of
As illustrated in (A) of
In contrast, for example, as illustrated in (B) of
As a result, in the shower head 10A in accordance with the present embodiment, the height of the second space 132 can be adjusted by suitably adjusting the height of the second space forming member 122b during the assembly of the vapor deposition apparatus.
In this manner, in the vapor deposition apparatus in accordance with the present embodiment, the height(s) of the first space 131, the second space 132, or both is/are configured to be adjustable. This configuration enables suitable adjustment of the height of the first space 131 or the second space 132, for example, according to the species or mix ratio of the gases introduced, and hence more elaborate optimization of the gas supply ratesfrom gas channels 15.
The following will describe yet another embodiment of the present invention in reference to
A vapor deposition apparatus in accordance with the present embodiment is described in reference to
The shower head 10B in accordance with the present embodiment differs from the shower head 10A described in embodiment 3 in that an adjustment mechanism is provided which is capable of adjusting the height of a first space 131.
The shower head 10B, as illustrated in
The distribution space forming mechanism 12c includes a second space forming mechanism 122 and a first space forming member 121c. The second space forming mechanism 122 constitutes a second space 132 or a part of the second space 132, whereas the first space forming member 121c constitutes the first space 131.
The first space forming member 121c, provided with a hole of a predetermined diameter, has a bellows structure capable of adjusting its height in the range of H7 (minimum) to H6 (maximum). The first space forming member 121c is configured so that a diffusion plate 50, provided with a plurality of diffusion holes 51, can be attached to it.
These members are configured so that they can be coupled together by aligning the central axes of their cylindrical or columnar shapes.
As a result, in the shower head 10B in accordance with the present embodiment, the height of the first space 131 can be adjusted by suitably adjusting the height of the first space forming member 121c during the assembly of the vapor deposition apparatus.
In this manner, in the vapor deposition apparatus in accordance with the present embodiment, the height(s) of the first space 131, the second space 132, or both is/are configured to be adjustable. This configuration enables suitable adjustment of the height of the first space 131 or the second space 132, for example, according to the species or mix ratio of the gases introduced, and hence more elaborate optimization of the gas supply ratesfrom gas channels 15.
The embodiments disclosed here are illuminative, and by no means restrictive, in every respect. The scope of the present invention is set forth only by patent claims, not by the description above, and encompasses all variations within the meaning and scope of the equivalents of the patent claims.
As described in the foregoing, in the vapor deposition apparatus in accordance with the present invention, the shower head includes a diffusion plate which divides a gas distribution space into two spaces, one of which is an upstream space and the other one of which is a downstream space. Furthermore, the diffusion plate has a plurality of diffusion holes for allowing the gas to pass from the upstream space to the downstream space through the holes.
In addition, in the vapor deposition apparatus in accordance with the present invention, the shower head includes a second space-height adjusting mechanism for adjusting the height of the second space.
In addition, in the vapor deposition apparatus in accordance with the present invention, the shower head includes a first space-height adjusting mechanism for adjusting the height of the first space.
The present invention is applicable to vapor deposition apparatus, such as a vertical-type MOCVD apparatus which supplies a gas to the surface of a target substrate through a plurality of gas channels of a shower plate in a shower head.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-142129 | Jun 2010 | JP | national |
| 2011-013969 | Jan 2011 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/064084 | 6/20/2011 | WO | 00 | 8/8/2012 |
