The present disclosure relates to an antenna and a plasma processing apparatus.
Japanese Laid-Open Patent Application Publication No. 2018-41685 discloses an antenna including a plurality of antenna members extending along a predetermined track-like shape and having longitudinal coupling positions opposite to each other in a short-side direction so as to form a predetermined track-like shape having a longitudinal direction and a short-side direction. The antenna includes a deformable and electrically conductive coupling member connecting the ends of the adjacent plurality of antenna members, and at least two vertical moving mechanisms individually coupled to at least two of the plurality of antenna members and capable of raising and lowering at least two of the plurality of antenna members so as to change the bending angle of the coupling member as a fulcrum.
The present disclosure provides an antenna that is shaped in accordance with an oxidizing amount or a nitriding amount in a substrate process.
According to one embodiment of the present disclosure, there is provided an antenna for inductively-coupled plasma. The antenna is configured to be disposed on a predetermined process chamber. The antenna is configured to adjust an oxidizing amount or a nitriding amount of a substrate process in the process chamber by changing a shape thereof. The antenna includes an antenna member disposed on the process chamber. The antenna member has a position where an oxidizing amount or a nitriding amount becomes a predetermined value at each measurement point of the antenna member. The antenna member has a shape formed based on the position of the antenna member obtained at each measurement point.
Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
As illustrated in
The vacuum chamber 1 is a process chamber to accommodate wafers W therein and to perform a plasma process on a film or the like deposited on surfaces of the wafers W. The vacuum chamber 1 includes a top plate (ceiling) 11 that faces recesses 24 formed in a surface of the susceptor 2, and a chamber body 12. A ring-shaped seal member 13 is provided at the periphery of the upper surface of the chamber body 12. The top plate 11 is configured to be attachable to and detachable from the chamber body 12. The diameter (inside diameter) of the vacuum chamber 1 in plan view is, for example, about 1100 mm, but is not limited to this.
A separation gas supply pipe 51 is connected to the center of the upper side of the vacuum chamber 1 (or the center of the top plate 11). The separation gas supply pipe 51 supplies a separation gas to a central area C in the vacuum chamber 1 to prevent different process gases from mixing with each other in the central area C.
A central part of the susceptor 2 is fixed to an approximately-cylindrical core portion 21. A rotational shaft 22 is connected to a lower surface of the core portion 21 and extends in the vertical direction. The susceptor 2 is configured to be rotatable by a drive unit 23 about the vertical axis of the rotational shaft 22, in a clockwise fashion in the example of
The rotational shaft 22 and the drive unit 23 are housed in a case body 20. An upper-side flange of the case body 20 is hermetically attached to the lower surface of a bottom part 14 of the vacuum chamber 1. A purge gas supply pipe 72 is connected to the case body 20. The purge gas supply pipe 72 supplies a purge gas (separation gas) such as nitrogen gas or argon gas to an area below the susceptor 2.
A part of the bottom part 14 of the vacuum chamber 1 surrounding the core portion 21 forms a ring-shaped protrusion 12a that protrudes so as to approach the susceptor 2 from below.
Circular recesses 24 (or substrate receiving areas), where the wafers W having a diameter of, for example, 300 mm are placed, are formed in the upper surface of the susceptor 2. A plurality of (e.g., five) recesses 24 are provided along the rotational direction of the susceptor 2. Each of the recesses 24 has an inner diameter that is slightly (e.g., from 1 mm to 4 mm) greater than the diameter of the wafer W. The depth of the recess 24 is substantially the same as or greater than the thickness of the wafer W. Accordingly, when the wafer W is placed in the recess 24, the height of the upper surface of the wafer W becomes substantially the same as or lower than the height of the upper surface of the susceptor 2 where the wafers W are not placed. When the depth of the recess 24 is excessively greater than the thickness of the wafer W, it may adversely affect film deposition. Therefore, the depth of the recess 24 is preferably less than or equal to about three times the thickness of the wafer W. Through holes (not illustrated in the drawings) are formed in the bottom of the recess 24 to allow a plurality of (e.g., three) lifting pins (which are described later) to pass through. The lifting pins raise and lower the wafer W.
As illustrated in
Also, the plasma processing gas nozzles 33 to 35 may be substituted with a single plasma processing gas nozzle. In this case, for example, a plasma processing gas nozzle extending from the outer peripheral wall of the vacuum chamber 1 toward the central region C may be disposed, similar to the second process gas nozzle 32.
The first process gas nozzle 31 forms a “first process gas supply part”. Also, the second process gas nozzle 32 forms a “second process gas supply part”. Each of the plasma processing gas nozzles 33, 34 and 35 forms a “plasma processing gas supply part”. Each of the separation gas nozzles 41 and 42 forms a “separation gas supply part”.
Each of the gas nozzles 31 through 35, 41, and 42 is connected to gas supply sources (not illustrated in the drawings) via a flow control valve.
Gas discharge holes 36 for discharging a gas are formed in the lower side (which faces the susceptor 2) of each of the nozzles 31 through 35, 41, and 42. The gas discharge holes 36 are formed, for example, at regular intervals along the radial direction of the susceptor 2. The distance between the lower end of each of the nozzles 31 through 35, 41, and 42 and the upper surface of the susceptor 2 is, for example, from about 1 mm to about 5 mm.
An area below the first process gas nozzle 31 is a first process area P1 where a first process gas is adsorbed on the wafer W. An area below the second process gas nozzle 32 is a second process area P2 where a second process gas that can produce a reaction product by reacting with the first process gas is supplied to the wafer W. An area below the plasma processing gas nozzles 33 through 35 is a third process area P3 where a modification process is performed on a film on the wafer W. The separation gas nozzles 41 and 42 are provided to form separation areas D for separating the first process area P1 from the second process area P2, and separating the third process area P3 from the first process area P1, respectively. Here, the separation area D is not provided between the second process area P2 and the third process area P3. This is because the second process gas supplied in the second process area P2 and the mixed gas supplied in the third process area P3 partially contain a common component therein in many cases, and therefore the second process area P2 and the third process area P3 do not particularly have to be separated from each other by using the separation gas.
Although described in detail later, the first process gas nozzle 31 supplies a source gas that forms a principal component of a film to be deposited as a first process gas. For example, when the film to be deposited is a silicon oxide film (SiO2), the first process gas nozzle 31 supplies a silicon-containing gas such as an organic aminosilane gas. The second process gas nozzle 32 supplies an oxidation gas such as oxygen gas and ozone gas as a second process gas. The plasma processing gas nozzles 33 through 35 supply a mixed gas containing the same gas as the second process gas and a noble gas to perform a modification process on the deposited film. For example, when the film to be deposited is the silicon oxide film (SiO2), the plasma processing gas nozzles 33 through 35 supply a mixed gas of the oxidation gas such as oxygen gas and ozone gas being the same as the second process gas and a noble gas such as argon and helium. Because the plasma processing gas nozzles 33 to 35 are configured to supply gases to different regions on the susceptor 2, the flow ratio of the noble gas may be made to vary from region to region, and thus the modification process may be performed uniformly.
Approximately pie slice-like convex portions 4 are provided on the lower surface of the top plate 11 of the vacuum chamber 1 at locations corresponding to the separation areas D. The convex portions 4 are attached to the back surface of the top plate 11. In the vacuum chamber 1, flat and low ceiling surfaces 44 (first ceiling surfaces) are formed by the lower surfaces of the convex portions 4, and ceiling surfaces 45 (second ceiling surfaces) are formed by the lower surface of the top plate 11. The ceiling surfaces 45 are located on both sides of the ceiling surfaces 44 in the circumferential direction, and are located higher than the ceiling surfaces 44.
As illustrated in
A nozzle cover 230 is provided above the first process gas nozzle 31. The nozzle cover 230 causes the first process gas to flow along the wafer W, and causes the separation gas to flow near the top plate 11 instead of near the wafer W. As illustrated in
As illustrated in
The plasma generating device 80 is configured by winding an antenna 83 made of a metal wire or the like, for example, three times around a vertical axis in a coil form. In plan view, the plasma generating device 80 is disposed to surround a strip-shaped area extending in the radial direction of the susceptor 2 and to extend across the diameter of the wafer W on the susceptor 2.
The antenna 83 is connected through a matching box 84 to a high frequency power source 85 that has, for example, a frequency of 13.56 MHz and output power of 5000 W. The antenna 83 is hermetically separated from the inner area of the vacuum chamber 1. As illustrated in
The antenna 83 has a foldable configuration at the top and the bottom, and has a lifting mechanism enabling the antenna 83 to be folded automatically at the top and the bottom. However, in
As illustrated in
As illustrated in
As illustrated in
The housing 90 is arranged so as to extend across the diameter of the wafer W in the radial direction of the susceptor 2 when the wafer W is located under the housing 90. A seal member 11c such as an O-ring is provided between the ring-shaped member 82 and the top plate 11.
The internal atmosphere of the vacuum chamber 1 is hermetically sealed by the ring-shaped member 82 and the housing 90. As illustrated in
As illustrated in
As illustrated in
Moreover, as illustrated in
When a single plasma processing gas nozzle is used, for example, the mixture of the above-described Ar gas, He gas, and O2 gas is supplied to the single plasma processing gas nozzle.
The base nozzle 33 is a gas nozzle for supplying a plasma processing gas to the whole surface of the wafer W. As illustrated in
On the other hand, the outer nozzle 34 is a nozzle for supplying a plasma processing gas selectively to an outer area of the wafer W.
The axis-side nozzle 35 is a nozzle to mainly supply the plasma processing gas to the central area near the axial side of the susceptor 2 on the wafer W.
Here, when a plasma processing gas nozzle is formed as a single gas nozzle, only the base gas nozzle may be disposed.
Next, a detailed description is given below of a Faraday shield 95 of the plasma generating device 80. As illustrated in
Viewing the Faraday shield 95 from the rotational center of the susceptor 2, the right and left upper ends of the Faraday shield 95 extend horizontally rightward and leftward, respectively, to form supports 96. A frame 99 is provided between the Faraday shield 95 and the housing 90 to support the supports 96 from below. The frame 99 is supported by a part of the housing 90 near the central area C and a part of the flange part 90a near the outer edge of the susceptor 2.
When an electric field reaches the wafer W, for example, electric wiring and the like formed inside the wafer W may become electrically damaged. To prevent this problem, as illustrated in
As illustrated in
As illustrated in
Next, an example of an antenna device 81 for holding an antenna according to an embodiment of the present disclosure and a plasma generating device 80 will be described.
The antenna device 81 includes an antenna 83, a connection electrode 86, a lifting mechanism 87, a linear encoder 88, and a fulcrum jig 89.
Also, the plasma generating device 80 further includes the antenna device 81, a matching box 84, and a radio frequency power source 85.
The antenna 83 includes an antenna member 830, a coupling member 831 and a spacer 832. The antenna 83 is generally configured in a coil shape, or a track-like shape, and is planar in an elongate annular shape having a longitudinal direction and a short-side direction (or a width direction). The planar shape may be an ellipse having an angle or a shape close to a rectangular frame having an angle. Such a track-like shape of antenna 83 is formed by coupling the antenna members 830. The antenna member 830 is part of the antenna 83 and the antenna 83 is formed by connecting ends of a plurality of small antenna members 830 extending along the track-like shape. The antenna member 830 includes a straight portion 8301 having a straight shape and curved portion 8302 having a curved shape for bending and connecting the straight portions 8301.
Then, by combining and connecting the straight portions 8301 and the curved portions 8302, the antenna members 830 are connected to both ends 830a and 830b and the central portions 830c and 830d to form a track-like shape as a whole. In
As illustrated in
The antenna member 830 forms a multi-stage track-like shape as a whole, and in
The coupling member 831 is a member for connecting adjacent antenna members 830 to each other and is made with a material that is conductive and can be deformed. The coupling member 831 may be made with, for example, a flexible substrate or the like, and may be made with a copper material. The copper material is a highly conductive and soft material, and is suitable for coupling the antenna members 830 to each other.
Because the coupling members 831 are made with a flexible material, it is possible to bend the antenna members 830 with the coupling members 831 as a fulcrum. This allows the antenna members 830 to be maintained in a bent state at the point of the coupling members 831, while allowing the configuration of the antenna 83 to be varied. The distance between the antenna 83 and the wafer W is likely to affect the intensity of the plasma process. When the antenna 83 is brought close to the wafer W, the intensity of the plasma process is likely to increase, and when the antenna 83 is moved away from the wafer W, the intensity of the plasma process is likely to decrease.
Further, the method of determining the shape of the antenna 83 and the details of the shape will be described below.
When the wafer W is loaded on the recess 24 of the susceptor 2 and the susceptor 2 is rotated to perform the plasma process, the wafer W is positioned along the circumferential direction of the susceptor 2, and the moving speed of the center side of the susceptor 2 is low and the moving speed of the outer side is high. Thus, the intensity (or processing amount) of the plasma process at the center of the wafer W, which is irradiated with plasma for a long time, is likely to be higher than the intensity of the plasma process at the outer periphery. To correct this, for example, if the antenna member 830a disposed on the central side is folded upwardly and the antenna member 830b disposed on the peripheral side is folded downwardly, the central plasma processing intensity is reduced; the peripheral plasma processing intensity is increased, and the overall plasma processing amount is uniform in the radial direction of the susceptor 2.
In
In any case, facing coupling members 831 are preferably disposed at the same position in the longitudinal direction, that is, equal in length in the longitudinal direction of the facing antenna members 830. As noted above, the antenna 83 is preferably configured to change its height in the longitudinal direction, while using the bending points facing each other in the short-side direction and coinciding with each other in the longitudinal direction. In this embodiment, the coupling members 831 coupling the antenna member 830a to the antenna member 830c and the coupling members 831 coupling the antenna member 830a to the antenna member 830d are configured to face each other in the short-side direction and be in the same position in the longitudinal direction. Similarly, the coupling member 831, which couples the antenna member 830b to the antenna member 830c, and the coupling member 831, which couples the antenna member 830b to the antenna member 830d, are also configured to face each other in the short-side direction and be in the same position in the longitudinal direction. Such an arrangement allows the shape of the antenna 83 to be varied to adjust the intensity of the plasma process in the longitudinal direction.
However, when the bending portion is shifted in an oblique direction and a deformation into a parallelogram shape, for example, is desired, it is possible to set the longitudinal positions of the coupling member 831 to different positions on the 830c side and the 830d side in the oblique direction instead of facing each other in the short-side direction.
A spacer 832 is a member for separating multi-stage antenna members 830 disposed at an upper stage and a lower stage from each other so that even if antenna 83 is deformed, the antenna members 830 do not contact the upper and lower stages and do not cause a short circuit.
The lifting mechanism 87 is a vertical motion mechanism for moving the antenna member 830 up and down. The lifting mechanism 87 includes an antenna retainer 870, a drive unit 871, and a frame 872. The antenna retainer 870 is the retaining portion of the antenna 83 and the drive unit 871 is a driving part for moving the antenna 83 up and down through the antenna retainer 870. The antenna retainer 870 may have various configurations as long as the antenna retainer 870 can hold the antenna member 830 of the antenna 83, but may be constructed to hold the antenna member 830 around the perimeter of the antenna member 830, for example, as illustrated in
The drive unit 871 may also use various drivers as long as the antenna members 830 can be moved up and down, for example, an air cylinder for air drive may be used. In
A frame 872 is a support for holding the drive unit 871, and holds the drive unit 871 at an appropriate position. The antenna retainer 870 is retained by the drive unit 871.
The lifting mechanism 87 is disposed for at least two or more of the antenna members 830a to 830d individually. In this embodiment, deformation of the antenna 83 is performed automatically using the lifting mechanism 87, rather than being adjusted by the operator. Thus, to deform the antenna 83 into various shapes, preferably, each of the antenna members 830a to 830d individually includes the lifting mechanism 87, each of which operates independently. Thus, the lifting mechanism 87 is preferably disposed for each of the antenna members 830a to 830d, and the lifting mechanism 87 is disposed for at least two of the antenna members 830a to 830d even when the lifting mechanism 87 is not disposed for each of the antenna members 830a to 830d.
In
The bending of the antenna 83 is performed by changing the angle formed between the antenna members 830a to 830d on both sides of the coupling member 831, with the coupling member 831 serving as the fulcrum.
A linear encoder 88 is a device that detects the position of the linear axis and outputs position information. This allows accurate measurement of the distance of the antenna member 830a from the top face of the Faraday shield 95. The linear encoder 88 may be disposed at any position where precise position information is desired, and a plurality of the linear encoders may be disposed. The linear encoder 88 may be any type including an optical, a magnetic, or an electromagnetic inductive type, as long as the position and height of the antenna 83 can be measured. Additionally, as long as the position and height of the antenna 83 can be measured, a height measuring unit other than the linear encoder 88 may be used.
The fulcrum jig 89 is a member for pivotally securing the lowermost antenna member 830. This facilitates tilting the antenna 83. Generally, the fulcrum jig 89 is provided to support the antenna member 830b of the lowermost stage at the end of the outer peripheral side. This is because, as noted above, the antenna 83 is often deformed to raise the center side. However, it is not mandatory to provide the fulcrum jig 89, but rather it is preferable to provide the lifting mechanism 87 that moves the antenna member 830b up and down.
The connection electrode 86 includes an antenna connecting part 860 and an adjustment busbar 861. The connection electrode 86 is a connection wire that serves as a framing to supply the antenna 83 with high frequency power output from the radio frequency power source 85. The antenna connecting part 860 is an interconnection directly connected to the antenna 83, and the adjustment busbar 861 is a part of the antenna connecting part 860 having a resilient structure to absorb the deformation when the antenna connecting part 860 is moved up and down by the vertical movement of the antenna 83. Because the antenna connecting part 860 is an electrode, the antenna connecting part 860 is made with an electrically conductive material such as metal.
Thus, antenna device 81 and plasma generating device 80 may be used that can automatically transform the shape of the antenna 83 into any shape.
Next, an antenna 83 according to embodiments of the present invention will be described. As noted above, the antenna 83 in accordance with this embodiment can be deformed in three dimensions.
The amount of plasma processing was considered to be proportional to the distance from the top plate 11 of the vacuum chamber 1 (precisely the bottom face of the housing 90).
However, in fact, the study of the inventors has found that the amount of plasma processing changes as shown in
The horizontal axis of
As shown in
In
As can be seen from the graph for each measurement point, the distance from the bottom face and the decrease in the oxidizing amount are proportional at a point A on the central axis side. A point B (50 mm) and a point B (100 mm) show similar properties. However, at a point E (200 mm), a linear line deforms and is shaped like a quadratic curve. In this case, the oxidizing amount is not proportional to the distance from the bottom face of the housing 90 of the antenna 83, and has an inflection point. The oxidizing amount is likely to increase as the point of inflection approaches the bottom face (the right side of the graph), but when the point of inflection is exceeded, the oxidizing amount decreases as the distance from the bottom face approaches (the left side of the graph).
At a point F (250 mm) and point G (300 mm), the slope is reversed from the points A to C, and the shorter the distance from the bottom face, the smaller the oxidizing amount.
As described above, in order to improve the uniformity of the oxidizing amount across the surface of the wafer W, the change in the oxidizing amount corresponding to the distance from these centers is understood, and the shape of the antenna 83 needs to be set so as to generate a constant oxidizing amount depending on the distance from the center of the susceptor 2.
For example, when the oxidizing amount is set to be the same at each measurement point, a shape that improves the uniformity of the oxidizing amount across the surface of the wafer W of the antenna 83 can be understood. In other words, if the oxidizing amount is constant at each measurement point A to G, the oxidizing amount at each measurement point A to G is uniform, and a plasma process with high uniformity across the surface of the wafer W can be performed.
The right-hand side of
Therefore, the ideal curve T is approximated and the final shape R is shown by a line that can be machined. When the antenna 83 is configured to be the final shape R, because the shape of the antenna 83 is very close to the ideal curve T, the uniformity of plasma processing across the surface of the wafer W is dramatically improved.
Thus, in the antenna 83 according to the present embodiment, by defining the shape of antenna 83 such that the oxidizing amount is a predetermined value, an antenna 83 with extremely high uniformity of plasma processing across a surface of a wafer W can be configured.
As described above, the shape of the antenna 83 can be configured to be the final shape R by performing the shape adjustment of the antenna 83 in multiple stages. Oxidation power was measured at each optimization stage.
The antennas J1 to J3 have flat shapes corresponding to the shape in
The antenna K has a bending shape corresponding to
The antenna L1 has a bending shape corresponding to that of
The antenna L2 is similar to the antenna L1 but has a sloped shape extending outward from the center. The shape of antenna L2 corresponds to the final shape R in
The oxidizing power was measured by depositing a silicon oxide film and measuring the thickness of the film. The higher the oxidation power, the thicker the film.
As the deposition conditions, as shown in
In contrast, in antennas K, L1, and L2, the thickness on the central axis side and the outer periphery side are almost the same, while indicating that the uniformity in film thickness is greatly improved.
In contrast, as shown in
As described above, when the antenna shape is optimized based on the oxidation power, very preferable uniformity of the film thickness across the surface of the wafer W can be obtained even in the actual film deposition.
Incidentally, in this embodiment, the index of the oxidation power is measured by the thickness of the silicon oxide film. However, the same result can be considered to be obtained even when the comparison is made with respect to the wet etch rate or the like, as long as the amount of plasma processing is the same.
In addition, the same result can be obtained not only for the silicon oxide film but naturally also for other oxide films, for example, a metal oxide film, if the uniformity of the oxidation power of the plasma across the surface of the wafer W is improved.
Furthermore, even when a nitride film is deposited, the same concept is applied. In this case, the shape of the antenna may be optimized so as to make the nitriding power uniform, and the ideal shape T of the antenna may be calculated by calculating the point where the thickness of the film is 1 or a predetermined value with respect to the thickness of the nitride film. Furthermore, if the shape is approximated to a shape that can be actually machined, the final shape R can be determined.
In addition, as for substrate processes other than film deposition, such as etching, if the shape of the antenna can be determined based on the etching power of the antenna, the antenna and the plasma processing apparatus according to the present embodiment can be applied.
Thus, the antenna and the plasma processing apparatus according to this embodiment can be applied to various substrate processes and to the plasma generating antenna used for the substrate processes, and uniformity across a surface of a wafer can be improved in any substrate process.
As described above, according to an antenna and a plasma processing apparatus according to the embodiments, uniformity of plasma processing across a surface of a substrate can be improved.
All examples recited herein are intended for pedagogical purposes to aid the reader in understanding the disclosure 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 disclosure. Although the embodiments of the present disclosure 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 disclosure.
Number | Date | Country | Kind |
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2021-004432 | Jan 2021 | JP | national |
The present application is a continuation application of U.S. patent application Ser. No. 17/570,470 filed on Jan. 7, 2022, which is based on and claims priority to Japanese Priority Application No. 2021-004432 filed on Jan. 14, 2021, the entire contents of which are hereby incorporated herein by reference.
Number | Date | Country | |
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Parent | 17570470 | Jan 2022 | US |
Child | 18668645 | US |