Patent Application
20220270866
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-027688 filed on Feb. 24, 2021, the entire contents of which are incorporated herein by reference.
The present disclosure relates to an apparatus for performing a sputtering process and a method thereof.
In a semiconductor device manufacturing process, a magnetron sputtering apparatus is used for forming a metal film or the like. This apparatus is configured such that a target made of a material to be deposited is disposed inside a vacuum processing container and a magnetic field and an electric field are generated inside the processing container to generate plasma so as to sputter the target with plasma ions.
For example, Patent Document 1 discloses a low-pressure remote sputtering apparatus in which a plurality of sets of holder bases that rotate via an auxiliary drive shaft are provided around a main drive shaft that rotates a base support stage, and a plurality of substrates are arranged around the auxiliary drive shaft. In this apparatus, when processing the plurality substrates held on the holder bases, film formation is performed by causing sputtered particles to be emitted from the target while combining rotation around the auxiliary drive shaft with rotation around the main drive shaft.
According to one embodiment of the present disclosure, there is provided an apparatus for performing a sputtering process on a substrate, including: a processing container configured to accommodate a plurality of substrates; a plurality of stages provided inside the processing container to respectively place the plurality of substrates thereon and disposed to be arranged along a circle surrounding a preset center position; and a target disposed at a position above the plurality of stages to cause target particles to be emitted by plasma formed inside the processing container such that the target particles adhere to the plurality of substrates respectively placed on the plurality of stages, wherein the plurality of stages are arranged such that an emission region in which the target particles are emitted from the target and overlapping regions in which the plurality of substrates respectively placed on the plurality of stages overlap are arranged at positions that are rotationally symmetrical around the preset center position when viewed in a plan view from above the target.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.
Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components have not been described in detail so as not to unnecessarily obscure aspects of the various embodiments.
A carrier C, which is a transfer container accommodating a substrate to be processed, is placed in the carry-in/out port 11. The carrier C accommodates a plurality of wafers W, which are circular substrates having a diameter of, for example, 300 mm. The carry-in/out module 12 is a facility for performing carry-in/out of the wafer W between the carrier C and the vacuum transfer module 13. The carry-in/out module 12 includes an atmospheric transfer chamber 121 provided with a transfer mechanism 123 for performing delivery and transfer of the wafer W in a normal pressure atmosphere, and a load-lock chamber 122 configured to switch the atmosphere in which the wafer W is placed between a normal pressure atmosphere and a vacuum atmosphere. The transfer mechanism 123 is configured to be movable in the left-right direction along a rail 124, and to be capable of being raised/lowered/rotated/expanded/contracted.
The vacuum transfer module 13 includes a vacuum transfer chamber 14 in which a vacuum atmosphere is formed, and a substrate transfer mechanism 15 is arranged inside the vacuum transfer chamber 14. The vacuum transfer chamber 14 of this example is configured to have a rectangular shape having long sides extending in the front-rear direction when viewed in a plan view. Among the four sidewalls of the vacuum transfer chamber 14, a plurality of (e.g., two) sputtering apparatuses 2 are connected to each of the long sides facing each other. The load-lock chamber 122 is connected to the short side on the front side. Reference numeral G in the figure indicates gate valves interposed between the carry-in/out module 12 and the vacuum transfer module 13 and between the vacuum transfer module 13 and the sputtering apparatuses 2, respectively. The gate valves G open and close the carry-in/out ports for the wafer W provided in respective modules connected to each other.
The substrate transfer mechanism 15 of this example is configured as an articulated arm for transferring the wafer W between the carry-in/out module 12 and each sputtering apparatus 2, and includes an end effector 16 configured to hold the wafer W. As will be described later, the sputtering apparatus 2 in this example collectively performs a sputtering process on the plurality of (e.g., four) wafers W in a vacuum atmosphere. Therefore, in order to collectively deliver the wafers W to the sputtering apparatus 2, the end effector 16 of the substrate transfer mechanism 15 is configured to be capable of holding, for example, four wafers W at the same time.
The end effector 16 includes a substrate holder 161 and a connecting portion 162. The substrate holder 161 includes two elongated spatula-shaped members extending horizontally in parallel with each other. The connecting portion 162 extends in the horizontal direction to be orthogonal to the extending direction of the substrate holder 161 and connects two base ends of the substrate holder 161 to each other. The central portion of the connecting portion 162 in the length direction is connected to the tip end of the articulated arm constituting the substrate transfer mechanism 15. The substrate transfer mechanism 15 is configured to be capable of swiveling and expanding/contracting.
Next, a configuration of the sputtering apparatus 2 for forming a film on the wafer W through a sputtering process will be described with reference to
The four sputtering apparatuses 2 connected to the vacuum transfer module 13 are configured in the same manner as each other, and the plurality of sputtering apparatuses 2 are capable of processing the wafers W in parallel with each other.
The sputtering apparatus 2 includes a processing container 20 having a rectangular shape in a plan view. The processing container 20 is configured as a vacuum container capable of evacuating an internal atmosphere. A carry-in/out port 21 connected to the vacuum transfer chamber 14 via a gate valve G is formed on the sidewall on the front side of the processing container 20. The carry-in/out port 21 is opened/closed by the gate valve G.
Inside the processing container 20, four stages 31 are arranged to correspond to the positions at which transfer of the wafers W is performed by the end effector 16. Each stage 31 is formed of a disk-shaped member. In this example, the wafer W is placed on each stage 31 such that the center of the disk-shaped stage 31 and the center of the wafer W are aligned with each other.
In addition, these plurality of stages 31 are in a state of being arranged at specific positions in relation to the planar shape and arrangement of the target 41 to be described later, but a specific setting example of the arrangement will be described later.
Each stage 31 is supported by a support column 32 at the center position of the disk from the bottom side. The lower side of the support column 32 penetrates the bottom surface of the processing container 20 and protrudes downward. A lower end portion of the support column 32 is provided with a drive mechanism 33 configured to rotate the stage 31 around a vertical axis passing through the center of the wafer W placed on the stage 31. From this point of view, the drive mechanism 33 corresponds to a rotation mechanism of this example. In a case in which a film having a desired film thickness distribution can be formed without rotating the wafer W, it is not an essential requirement to rotate the stage 31 using the drive mechanism 33.
Reference numeral 321 indicated in
The drive mechanism 33 also has a function of raising and lowering the stage 31 between a processing position at which the sputtering process for the wafer W is performed and a delivery position at which the wafer W is delivered to/from the end effector 16. A height position at which the stages 31 are arranged in
In the processing container 20, a shield plate 24 that divides the internal space of the processing container into upper and lower portions is disposed. Circular openings 241 are formed in the shield plate 24, and the stages 31 raised to the processing position are in the state of being arranged inside the openings 241, respectively.
Delivery pins (not illustrated) are provided on the bottom surface of the processing container 20. When the stages 31 are lowered to the delivery position, the delivery pins protrude from the top surfaces of the stages 31 through through-holes (not illustrated) provided in the stages 31. As a result, the delivery of the wafers W can be performed between the delivery pins and the end effector 16.
A heater 311 is embedded in each stage 31, and generates heat by electric power supplied from a power feeder (not illustrated) to heat the wafer W placed on the stage 31. As a temperature of heating the wafer W by the stage 31, a temperature in the range of 50 to 450 degrees C. may be exemplified.
A circular opening 201 is formed in the center of the top surface of the processing container 20. The target 41 is provided inside the opening 201. A conductive target electrode 42 made of, for example, copper (Cu) or aluminum (Al) is bonded to the top surface of the target 41. For example, the target electrode 42 is arranged on the top surface of the processing container 20 via an annular insulating member 43. As a result, the above-mentioned opening 201 provided in the top surface of the processing container 20 is closed by the target electrode 42.
A DC power supply 44 is connected to the target 41. Plasma can be formed in the processing container 20 by DC power supplied from the DC power supply 44. Instead of the DC power, AC power may be applied to generate plasma.
The target 41 emits target particles, which adhere to the wafers W, by the plasma formed inside the processing container 20, thereby performing film formation. For example, the target 41 is composed of titanium (Ti), silicon (Si), zirconium (Zr), hafnium (HD, tungsten (W), a cobalt-iron-boron alloy, a cobalt-iron alloy, iron (Fe), tantalum (Ta), ruthenium (Ru), magnesium (Mg), iridium manganese (IrMn), platinum manganese (PtMn), or the like. In addition, as the target 41, an insulator such as SiO2 may be used in addition to the metal.
A magnet 5 made of a permanent magnet for adjusting the state of plasma formed inside the processing container 20 is arranged on the rear side of the target 41 when viewed from the side of the stages 31. Specifically, the magnet 5 is held by a magnet moving mechanism 50 and is arranged at a height position spaced apart from the top surface of the target electrode 42 bonded to the target 41 by about several millimeters.
As schematically illustrated in
For example, the magnet moving mechanism 50 includes an elongated rod-shaped magnet holder 51. The magnet 5 is held on the bottom side of the magnet holder 51. Ball screws 531, each of which penetrates the magnet holder 51, are provided at opposite ends of the magnet holder 51. Opposite ends of each ball screw 531 are supported by support columns 52 arranged on the top surface of the processing container 20. Each ball screw 531 can be rotationally driven by a drive motor 53 provided at the end portion thereof. The magnet 5 can be horizontally moved by rotating both ball screws 531 in a state in which rotation direction and rotation speed are in synchronization with each other.
With the above-described configuration, as indicated by the arrows in
For the sake of convenience in illustration, the illustration of the magnet moving mechanism 50, the target electrode 42, the processing container 20, and the like is omitted in
Returning to the description of
In the sputtering apparatus 2 having the configuration described above, the target 41 and the stages 31 have a special arrangement relationship in which a film having a uniform film thickness is formed in the plane of each wafer W. In addition, according to this arrangement relationship, it is possible to perform film formation with a uniform film thickness distribution even in inter-planes of the plurality of wafers W to be sputtered in the processing container 20.
Hereinafter, the arrangement relationship between the target 41 and the stages 31 in the sputtering apparatus 2 of this example will be described with reference to
Furthermore, as described above, the wafer W is placed on each stage 31 such that the center of the disk-shaped stage 31 and the center of the wafer W are aligned with each other. Therefore, ignoring a difference in diameter between each stage 31 and the wafer W, it can be said that
At this time, in the sputtering apparatus 2 of this example illustrated in
In the following description, regions in which an emission region, which is a region in which the target particles are emitted, and wafers W respectively placed on the plurality of stages 31 overlap when viewed from above the target 41 in a plan view will be referred to as “overlapping regions OR.” In this example, the entire surface of the target 41 corresponds to the emission region. In
In the sputtering apparatus 2 of this example, the overlapping regions OR are arranged at positions that are rotationally symmetrical around the above-mentioned center position O. In the example illustrated in
Here, for ease of understanding the characteristics of the arrangement of the target 41 and the stages 31 in
As described above, there is a problem of providing a plurality of stages 31 in a common processing container 20 and forming a film having a uniform thickness in the plane of the wafer W placed on each stage 31. In this case, as illustrated in
However, under a condition that the footprint of the apparatus is limited, the plurality of stages 31 are required to be arranged at positions close to each other as illustrated in
For example, in the example of the arrangement illustrated in
In order to avoid the formation of such a film thickness distribution, it is necessary to arrange the stages 31 sufficiently apart from each other, which may lead to an increase in the footprint of the sputtering apparatus 2 or the substrate processing system 1.
Therefore, as described above, in the sputtering apparatus 2 of this example, an arrangement, in which the plurality of overlapping regions OR in which the stages 31 and the target 41 appear to overlap each other are rotationally symmetrical around the center position O (in this example, symmetrical 4 times) when viewed in a plan view, is adopted. Unlike the comparative embodiment described with reference to
As described above, the substrate processing system 1 and the sputtering apparatus 2 having the configurations described above with reference to
Next, the operations of the above-described substrate processing system 1 and sputtering apparatus 2 will be described.
When the carrier C accommodating the wafers W to be processed is placed on the carry-in/out port 11, the transfer mechanism 123 receives the wafers W and transfers the same into the load-lock chamber 122 via the atmospheric transfer chamber 121. Subsequently, after switching the interior of the load lock chamber 122 from a normal pressure atmosphere to a vacuum atmosphere, the substrate transfer mechanism 15 of the vacuum transfer module 13 receives the wafers W and transfers the same to a predetermined sputtering apparatus 2 via the vacuum transfer chamber 14. As described above, the substrate transfer mechanism 15 enters the processing container 20 in the state of holding a total of four wafers W on the end effector 16. Then, after these wafers W are delivered from the end effector 16 to delivery pins (not illustrated), the end effector 16 is retracted from the processing container 20 and the gate valve G closes the carry-in/out port 21. Thereafter, each stage 31 that has been retracted to the delivery position is raised, and the wafers W are delivered from the delivery pins to these four stages 31 at the same time.
Subsequently, while raising each stage 31 to the processing position, the supply of the plasma-generating gas from the supply port 25, the adjustment of the internal pressure of the processing container 20, and the heating of the wafers W by the heaters 311 are performed. In addition, the rotation of the stages 31 by the drive mechanisms 33 is initiated.
Thereafter, the DC power is applied from the DC power supply 44 to the target electrode 42. As a result, an electric field is generated around the target electrode 42, and electrons accelerated by this electric field collide with the Ar gas to ionize the Ar gas, whereby new electrons are generated.
Meanwhile, when the movement of the magnet 5 by the magnet moving mechanism 50 is initiated, a magnetic field is formed on the surface of the target 41 according to the arrangement position of the magnet 5, and electrons ionized from the Ar gas are accelerated by the electric field and the magnetic field near the target 41. Due to this acceleration, a phenomenon in which electrons with energy further collide with the Ar gas to cause ionization successively occurs to form plasma. The Ar ions in the plasma sputter the target 41, whereby target particles are emitted.
In this way, the target particles are radially emitted from the surface of the target 41 located under the magnet 5 toward the wafers W on the stages 31. As a result, the target particles reach and adhere to the wafers W. Then, by reciprocating the magnet 5 as described with reference to
As described above, in the sputtering apparatus 2 of this example, the overlapping regions OR between the stages 31 and the target 41 are arranged to be rotationally symmetrical around the center position O of the circle R formed by arranging the center positions of the plurality of stages 31. According to this configuration, even when the plurality of stages 31 are arranged in a compact region, target particles are supplied from one target 41 to the wafer W placed on each stage 31. As a result, unlike the sputtering apparatus 2a according to the comparative embodiment described with reference to
Since respective stages 31 are arranged to be rotationally symmetrical with respect to the disk-shaped target 41, a difference in film thickness distribution due to a difference in the arrangement positions of the stages 31 may be less likely to occur. This makes it possible to perform film formation in which the film thickness distribution is uniform even in the inter-planes of the wafers W.
When a predetermined period of time elapses and the film formation by the sputtering process is completed, the supply of the Ar gas and the DC power, the heating of the wafers W, and the rotation of the stages 31 are stopped, and the internal pressure of the processing container 20 is adjusted. Then, the four wafers W after the film formation are simultaneously carried out from the processing container 20 via a procedure opposite to that at the time of carry-in.
In addition, the wafers W taken out from the processing container 20 are returned to the carrier C on the carry-in/out port 11 in the order of the vacuum transfer module 13, the load-lock chamber 122, and the atmospheric transfer chamber 121 via the route opposite to that at the time of carry-in.
According to the sputtering apparatus 2 according to the present embodiment, it is possible to perform an in-plane and inter-plane uniform sputtering process on the plurality of wafers W arranged in the common processing container 20.
Next, with reference to
The number of stages 31 provided inside the processing container 20 is not limited to the example described with reference to
In general, when the stages 31 are arranged such that the overlapping regions OR are symmetrical M times, it is not an essential requirement to arrange a total of M stages 31 at all positions satisfying this condition.
In addition, the shapes of targets 41b and 41c are not limited to a circle. For example,
Next,
Using the magnet moving mechanism 50a illustrated in
In the example illustrated in
Here, in the example described with reference to
By contrast, in the example described with reference to
As a method of forming the circular emission region D, a case in which the magnets 5a illustrated in
The emission region D formed as a partial region of the target 41 is not limited to the case of a circular shape or an annular shape. For example, the emission region D having another shape such as a square or an equilateral triangle may be formed in correspondence with the examples described with reference to
According to the present disclosure, a sputtering process can be uniformly performed on a plurality of substrates arranged in a common processing container.
It should be understood that the embodiments disclosed herein are exemplary in all respects and are not restrictive. The above-described embodiments may be omitted, replaced, or modified in various forms without departing from the scope and spirit of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-027688 | Feb 2021 | JP | national |
