Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32082—Radio frequency generated discharge
  • H01J37/321—Radio frequency generated discharge the radio frequency energy being inductively coupled to the plasma
  • H01J37/3211—Antennas, e.g. particular shapes of coils
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32082—Radio frequency generated discharge
  • H01J37/321—Radio frequency generated discharge the radio frequency energy being inductively coupled to the plasma
  • H01J37/32119—Windows
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32082—Radio frequency generated discharge
  • H01J37/32174—Circuits specially adapted for controlling the RF discharge
  • H01J37/32183—Matching circuits
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/3244—Gas supply means

Definitions

• the present disclosure relates generally to substrate processing systems and more particularly to a Fibonacci coil for a plasma processing chamber.
• Substrate processing systems are typically used to perform treatments on substrates such as semiconductor wafers. Examples of treatments include deposition, etching, cleaning, and other processes. Etching usually includes wet chemical etching or dry etching. Dry etching may be performed using plasma generated by inductively- coupled plasma (ICP). The inductively-coupled plasma may be generated by coils arranged outside of a processing chamber adjacent to a dielectric window. Process gas mixtures flowing inside the processing chamber are ignited to create plasma.
• ICP inductively- coupled plasma
• a system for processing semiconductor substrates comprises a processing chamber configured to process a semiconductor substrate using an inductively coupled plasma.
• the processing chamber comprises a dielectric window.
• the system further comprises a coil arranged on the dielectric window.
• the coil has a circular center portion and a plurality of legs extending spirally outward from the circular center portion parallel to the dielectric window. Each of the legs is a Fibonacci spiral.
• the system further comprises a generator configured to supply RF power to the circular center portion of the coil to generate the inductively coupled plasma in the processing chamber in response to a process gas being supplied to the processing chamber.
• the plurality of legs extend spirally outward from the circular center portion of the coil in a clockwise direction, or the plurality of legs extend spirally outward from the circular center portion of the coil in a counterclockwise direction.
• each of the plurality of legs has a predetermined length and makes a predetermined number of turns around the circular center portion of the coil, and the predetermined number of turns is within a predetermined range.
• each of the plurality of legs is grounded directly, each of the plurality of legs is grounded via a fixed capacitor, or each of the plurality of legs is grounded via a variable capacitor.
• system further comprises a matching circuit configured to match impedances of the generator and the coil.
• the coil is arranged along a first plane parallel to a top surface of the dielectric window.
• the top surface of the dielectric window is parallel to a second plane along which the semiconductor substrate is arranged on a substrate support located in the processing chamber beneath the dielectric window.
• the dielectric window is circular and has a diameter greater than the coil.
• the processing chamber further comprises an injector arranged at a center of the dielectric window to inject the process gas into the processing chamber where the circular center portion of the coil is mounted around the injector.
• the processing chamber further comprises a plurality of inlets to laterally supply the process gas into the processing chamber.
• the plurality of legs is grounded directly, via a fixed capacitor, via a variable capacitor, or using a combination thereof.
• the system further comprises an injector arranged at a center of the dielectric window to inject the process gas into the processing chamber where the circular center portion of the coil is mounted around the gas injector.
• the system further comprises a plurality of inlets to laterally supply the process gas into the processing chamber.
• the system further comprises a matching circuit configured to match impedances of the generator and the coil using a plurality of variable capacitors.
• the system further comprises a controller configured to control the inductively coupled plasma and a rate of a process performed on the semiconductor substrate using the inductively coupled plasma by controlling one or more of the process gas supplied via the injector and the plurality of inlets, the variable capacitor connected to one of the plurality of legs, and the plurality of variable capacitors of the matching circuit.
• a coil for generating inductively coupled plasma in a processing chamber for processing a semiconductor substrate comprises a circular center portion that is parallel to a plane.
• the circular center portion is configured to receive RF power to generate the inductively coupled plasma in the processing chamber for processing the semiconductor substrate.
• the coil further comprises a plurality of legs extending spirally outward from the circular center portion parallel to the plane. Each of the legs is a Fibonacci spiral.
• the plurality of legs extend spirally outward from the circular center portion of the coil in a clockwise direction, or the plurality of legs extend spirally outward from the circular center portion of the coil in a counterclockwise direction.
• each of the plurality of legs has a predetermined length and makes a predetermined number of turns around the circular center portion of the coil, and the predetermined number of turns is within a predetermined range.
• each of the plurality of legs is grounded directly, each of the plurality of legs is grounded via a fixed capacitor, or each of the plurality of legs is grounded via a variable capacitor.
• a system for processing semiconductor substrates comprises the coil.
• the plurality of legs of the coil is grounded directly, via a fixed capacitor, via a variable capacitor, or using a combination thereof.
• the system further comprises the processing chamber configured to process the semiconductor substrate arranged on a substrate support in the processing chamber using the inductively coupled plasma.
• the processing chamber comprises a dielectric window located above the semiconductor substrate.
• the coil is arranged on the dielectric window.
• the dielectric window and the semiconductor substrate are arranged parallel to the plane of the coil.
• the system further comprises a generator configured to supply the RF power to the circular center portion of the coil to generate the inductively coupled plasma in the processing chamber in response to a process gas being supplied to the processing chamber.
• the system further comprises an injector arranged at a center of the dielectric window to inject the process gas into the processing chamber.
• the circular center portion of the coil is mounted around the injector.
• the system further comprises a plurality of inlets to laterally supply the process gas into the processing chamber.
• the system further comprises a matching circuit configured to match impedances of the generator and the coil using a plurality of variable capacitors.
• the system further comprises a controller configured to control the inductively coupled plasma and a rate of a process performed on the semiconductor substrate using the inductively coupled plasma by controlling one or more of the process gas supplied via the injector and the plurality of inlets, the variable capacitor connected to one of the plurality of legs, and the plurality of variable capacitors of the matching circuit.
• FIG. 1 shows an example of a substrate processing system comprising a processing chamber that uses inductively coupled plasma to etch substrates such as semiconductor wafers;
• FIG. 2A shows an example of a Fibonacci spiral
• FIG. 2B shows an example of a method for generating a Fibonacci spiral
• FIG. 3 shows another example of a method for generating a Fibonacci spiral
• FIG. 4 shows an example of a coil design based on Fibonacci spirals
• FIGS. 5A-5D show additional examples of coil designs based on Fibonacci spirals;
• FIG. 6A shows an example of a Fibonacci coil mounted on a dielectric window of the processing chamber;
• FIGS. 6B-6D show examples of different ways in which a Fibonacci coil can be mounted on the dielectric window of the processing chamber
• FIGS. 7A-7C show examples of different ways in which legs of a Fibonacci coil can be terminated when the Fibonacci coil is mounted on the dielectric window of the processing chamber;
• FIG. 8A shows an example of a system for supplying power to a Fibonacci coil
• FIG. 8B shows an example of a matching circuit used in the system of FIG. 8A.
• FIG. 9 shows a schematic representation of the assembly shown in FIG. 6A.
• Substrate processing systems are typically used to etch thin film on substrates such as semiconductor wafers.
• the substrate processing systems include a processing chamber with a pedestal such as an electrostatic chuck (ESC) to support and hold a substrate during treatment.
• the processing chamber may include a dielectric window.
• Inductively-coupled plasma may be generated by supplying RF power to the coil using an RF generator. Process gas mixtures flowing inside the processing chamber are ignited to create plasma.
• the substrate processing system may be used to etch conductive or dielectric film.
• the coil is generally arranged in a plane that is located above and parallel to an outer surface of the dielectric window.
• the RF power is delivered to the coil by conductive lines that connect to the coil (e.g., to terminals located at the center of the coil as explained below).
• the conductive lines and the terminals are connected generally perpendicular to the plane including the coil.
• the coil When excited by RF power, the coil produces a strong magnetic field that travels through the dielectric window and ignites the process gas mixture.
• the coils designed using the Fibonacci sequence provide improved power distribution, plasma distribution, and uniformity relative to other coil designs. Etch rates can be improved by altering the number of turns, the number of legs, and the length of a Fibonacci coil as explained below in detail.
• FIG. 1 An example of a processing chamber that uses inductively coupled plasma to etch substrates such as semiconductor wafers is described with reference to FIG. 1.
• a Fibonacci spiral is described with reference to FIGS. 2A and 2B, and examples of Fibonacci spirals are described with reference to FIGS. 3 and 4.
• Examples of Fibonacci coil designs are described with reference to FIGS. 5A-5D.
• An example of a Fibonacci coil mounted on a dielectric window of a processing chamber is described with reference to FIGS. 6A-6D.
• FIGS. 7A-7C Various examples of configurations for terminating legs of a Fibonacci coil are described with reference to FIGS. 7A-7C.
• FIGS. 8A and 8B An example of a system for supplying power to a Fibonacci coil using a matching circuit is described with reference to FIGS. 8A and 8B.
• the principles of operation of the Fibonacci coil and the resultant improvements in etch rates provided by the Fibonacci coil are described with reference to FIG. 9.
• FIG. 1 shows an example of a substrate processing system 100 according to the present disclosure.
• the substrate processing system 100 includes a coil driving circuit 110.
• the coil driving circuit 110 includes an RF source 112, a pulsing circuit 114, and a tuning circuit (i.e. , matching circuit) 113.
• the pulsing circuit 114 controls a transformer coupled plasma (TCP) envelope of an RF signal generated by the RF source 112 and varies a duty cycle of TCP envelope between 1 % and 99% during operation.
• TCP transformer coupled plasma
• the pulsing circuit 114 and the RF source 112 can be combined or separate.
• the tuning circuit 113 may be directly connected to an inductive coil 116. While some substrate processing systems use a plurality of coils (e.g., inner and outer coils), the substrate processing system 100 uses a single coil having one of the various Fibonacci sequence based designs described below.
• the tuning circuit 113 tunes an output of the RF source 112 to a desired frequency and/or a desired phase, and matches an impedance of the coil 116.
• a dielectric window 124 is arranged along a top side of a processing chamber 128.
• the processing chamber 128 further comprises a substrate support (or pedestal) 132 to support a substrate 134.
• the substrate support 132 may include an electrostatic chuck (ESC), or a mechanical chuck or other type of chuck.
• Process gas is supplied to the processing chamber 128 and plasma 140 is generated inside of the processing chamber 128.
• the plasma 140 etches an exposed surface of the substrate 134.
• An RF source 150, a pulsing circuit 151 , and a bias matching circuit 152 may be used to bias the substrate support 132 during operation to control ion energy.
• a gas delivery system 156 may be used to supply a process gas mixture to the processing chamber 128.
• the gas delivery system 156 may include process and inert gas sources 157, a gas metering system 158 such as valves and mass flow controllers, and a manifold 159.
• a gas injector 163 may be arranged at a center of the dielectric window 124 and is used to inject gas mixtures from the gas delivery system 156 into the processing chamber 128. Additionally or alternatively, the gas mixtures may be injected from the side of the processing chamber 128 (e.g., see FIG. 6A).
• a heater/cooler 164 may be used to heat/cool the substrate support 132 to a predetermined temperature.
• An exhaust system 165 includes a valve 166 and pump 167 to control pressure in the processing chamber and/or to remove reactants from the processing chamber 128 by purging or evacuation.
• a controller 154 may be used to control the etching process.
• the controller 154 monitors system parameters and controls delivery of the gas mixture; striking, maintaining, and extinguishing the plasma; removal of reactants; supply of cooling gas; and so on. Additionally, as described below, the controller 154 may control various aspects of the coil driving circuit 110, the RF source 150, and the bias matching circuit 152, and so on.
• the controller 154 may control various aspects of the coil driving circuit 110, the RF source 150, and the bias matching circuit 152, and so on.
• 2A and 2B show a Fibonacci spiral (also called a logarithmic spiral).
• FIG. 2B shows that the logarithmic spiral can be constructed from equally spaced rays by starting at a point along one ray, and drawing a perpendicular to a neighboring ray. As the number of rays approaches infinity, the sequence of segments approaches a smooth logarithmic spiral.
• a rate of change of radius of the logarithmic spiral is:
• the spiral approaches a circle.
• a length of the spiral from P to the origin is finite. If the point P is at distance r from the origin measured along a radius vector, the distance from P to the pole along the spiral is the length of the arc. Radii from the origin meet the spiral at distances that are in geometric progression.
• the Fibonacci sequence based coil designs described below include a plurality of legs that extend from a circular center of a coil (e.g., see FIG. 4). Each leg of a coil in the coil designs shown in the following figures and described below is a Fibonacci spiral or follows a path of a Fibonacci spiral from a circular center of the coil. Accordingly, each coil design described below is called a Fibonacci coil. Any of the Fibonacci coils described below can be used as the coil 116 in FIG. 1.
• FIG. 4 shows an example of a Fibonacci coil 400 according to the present disclosure.
• the Fibonacci coil 400 has four legs 402-1 , 402-2, 402-3, and 402-4 (collectively legs 402).
• Each leg 402 is a Fibonacci spiral as described with reference to FIGS. 2A-3.
• Each leg 402 extends as a Fibonacci spiral from a center 404 of the Fibonacci coil 400 as shown.
• the center 404 of the Fibonacci coil 400 is a circle. While 4 legs are shown for example only, the Fibonacci coil 400 can have fewer or more than 4 legs (e.g., see FIGS. 5A-5D).
• the direction in which the legs 402 extend from the center 404 is shown as anti-clockwise.
• the legs 402 can extend from the center 404 in clockwise direction (e.g., see FIGS. 5A-5D).
• the number of turns of a leg 402 from the center 404 to the end (i.e. , point of termination) of the leg 402 can vary.
• the number of turns of each leg 402 may be any number greater than 0 (e.g., a quarter turn, half a turn, three quarters of a turn, 1 turn; 1.25, 1.5, 1.75, 2 turns; and so on; the variation being not necessarily in quarter turn increments).
• FIGS. 5A-5D show additional examples of Fibonacci coils according to the present disclosure.
• each leg of the coils shown is a Fibonacci spiral extending from a circular center of the coil.
• FIG. 5A shows an example of a Fibonacci coil 500 with 4 legs. Each leg of the Fibonacci coil 500 makes three quarters of one turn. Accordingly, the Fibonacci coil 500 is a 4 leg, 3 ⁇ 4 turn Fibonacci coil.
• FIG. 5B shows an example of a Fibonacci coil 502 with 4 legs. Each leg of the Fibonacci coil 502 makes one turn. Accordingly, the Fibonacci coil 502 is a 4 leg, 1 turn Fibonacci coil.
• FIG. 5A shows an example of a Fibonacci coil 500 with 4 legs. Each leg of the Fibonacci coil 500 makes three quarters of one turn. Accordingly, the Fibonacci coil 500 is a 4 leg, 3 ⁇ 4 turn Fibonacci coil.
• FIG. 5B shows an
• FIG. 5C shows an example of a Fibonacci coil 504 with 8 legs. Each leg of the Fibonacci coil 504 makes one turn. Accordingly, the Fibonacci coil 504 is an 8 leg, 1 turn Fibonacci coil. Additional configurations including different number of legs and turns and having counter-clockwise direction are contemplated.
• FIG. 5D shows an example of two Fibonacci coils 506 and 508, each having a plurality of legs extending from a circular center. Again, each leg of the coils shown is a Fibonacci spiral extending from a circular center.
• the Fibonacci coils 506 and 508 are drawn on top of each other not because they are stacked on top of each other when mounted above the dielectric window 124 but to illustrate and contrast the opposite directions in which their legs extend from the circular center.
• the legs of the Fibonacci coil 506 extend from the circular center of the Fibonacci coil 506 as Fibonacci spirals in counter-clockwise direction while the legs of the Fibonacci coil 508 extend from the circular center of the Fibonacci coil 508 as Fibonacci spirals in clockwise direction.
• FIG. 6A shows an example of a Fibonacci coil mounted on top of the dielectric window 124 of the processing chamber 128.
• the Fibonacci coil shown is the 4 leg, 1 turn Fibonacci coil 502 shown in FIG. 5B.
• a top plate 600 e.g., made of a metal such as aluminum
• the dielectric window 124 e.g., made of a dielectric material such as ceramic.
• the center of the Fibonacci coil 502 is mounted on top of the dielectric window 124 (i.e. , outside the processing chamber 128) around the gas injector 163. That is, the circular center of the Fibonacci coil 502 surrounds the gas injector 163.
• the top surface of the dielectric window 124 may include 4 mounting posts 601 -1 , 601 -2, 601 -3, and 601 -4 (collectively mounting posts 601 ).
• the Fibonacci coil 502 may include 4 mounting holes on its circular center portion that mate with the mounting posts 601 on the dielectric window 124.
• the mounting posts 601 on the dielectric window 124 and the corresponding mounting holes on the circular center of the Fibonacci coil 502 may be arranged in any manner.
• the mounting posts 601 on the dielectric window 124 and the corresponding mounting holes on the circular center of the Fibonacci coil 502 may lie on four vertices of a square whose diagonal is equal to a radius of the circular center of the Fibonacci coil 502.
• the mounting posts 601 on the dielectric window 124 and the corresponding mounting holes on the circular center of the Fibonacci coil 502 may lie on four vertices of a rectangle or any other quadrilateral. Additional mounting arrangements for mounting Fibonacci coils on the dielectric window 124 are shown in FIGS. 6B-6D and are described below.
• the four legs of the Fibonacci coil 502 are connected to the top plate 600 using electrically conductive straps 602-1 , 602-2, 602-3, and 602-4 (collectively conductive straps 602).
• the conductive straps 602 may be made of a metal such as copper.
• Various alternative configurations for terminating the legs are shown and described below with reference to FIGS. 7A-7C.
• RF power is supplied to the center of the Fibonacci coil 502 through a matching circuit via electrical contacts shown at 604-1 and 604-2 (collectively electrical contacts 604).
• a system comprising an RF generator and a matching circuit is shown and described below with reference to FIGS. 8A and 8B.
• Gas mixtures can be supplied from the gas delivery system 156 to the processing chamber 128 from the top via the gas injector 163 via a gas line 606 and/or from the side of the processing chamber 128 via gas lines 608.
• the gas lines 606 and 608 are connected to the gas delivery system 156 shown in FIG. 1.
• the gas line 606 connects the gas injector 163 to the gas delivery system 156.
• the plasma generation in the processing chamber 128 can be controlled to yield desired etch rates.
• FIGS. 6B-6D show many other examples of mounting arrangements that can be used to mount the Fibonacci coils of the present disclosure on top of the dielectric window 124.
• the gas injector 163 is not shown at the center of the dielectric window 124.
• the top surface of the dielectric window 124 may include the four mounting posts 601 shown in FIG. 6A, and the Fibonacci coil 502 may include four mounting holes on its circular center that mate with the mounting posts 601 on the dielectric window 124.
• the four mounting posts 601 on the dielectric window 124 and the corresponding mounting holes on the circular center of the Fibonacci coil 502 may lie on four vertices of a square whose diagonal is equal to a radius of the circular center of the Fibonacci coil 502.
• the mounting posts 601 on the dielectric window 124 and the corresponding mounting holes on the circular center of the Fibonacci coil 502 may lie on four vertices of a rectangle or any other quadrilateral.
• the top surface of the dielectric window 124 may include three mounting posts, and the Fibonacci coil 502 may include three mounting holes on its circular center that mate with the three mounting posts on the dielectric window 124.
• the three mounting posts on the dielectric window 124 and the corresponding mounting holes on the circular center of the Fibonacci coil 502 may lie on three vertices of a triangle.
• the triangle may be an equilateral triangle or any other triangle.
• the top surface of the dielectric window 124 may include eight mounting posts, and the Fibonacci coil 502 may include eight mounting holes on its circular center that mate with the eight mounting posts on the dielectric window 124.
• the eight mounting posts on the dielectric window 124 and the corresponding mounting holes on the circular center of the Fibonacci coil 502 may lie on eight vertices of an octagon.
• the number of turns of a Fibonacci coil can be changed by turning the coil clockwise or anticlockwise.
• the Fibonacci coil may be turned clockwise or anticlockwise by one or more mounting posts. That is, while the legs are terminated, the center of the Fibonacci coil can be rotated clockwise or anticlockwise from its existing position to increase or decrease the number of turns. For example, if the legs of the Fibonacci coil extend in a clockwise direction, rotating the center of the Fibonacci coil clockwise will decrease the number of turns, and rotating the center of the Fibonacci coil counterclockwise will increase the number of turns. Conversely, if the legs of the Fibonacci coil extend in a counterclockwise direction, rotating the center of the Fibonacci coil clockwise will increase the number of turns, and rotating the center of the Fibonacci coil counterclockwise will decrease the number of turns.
• the number of mounting posts on the dielectric window 124 and the number of holes on the circular center of the Fibonacci coil determine the resolution at which the number of turns of the Fibonacci coil can be changed. For example, if there are N mounting posts on the dielectric window 124 and N holes on the circular center of the Fibonacci coil, the smallest angle by which the Fibonacci coil can be turned is 360/N. Further, the Fibonacci coil can be turned by any angle that is an integer multiple of 360/N.
• the correspondence between the number of mounting posts on the dielectric window 124 and the number of holes on the circular center of the Fibonacci coil need not be a one-to-one correspondence.
• the number of mounting posts on the dielectric window 124 may be 2 while the number of holes on the circular center of the Fibonacci coil may be four, or vice versa.
• the number of mounting posts on the dielectric window 124 may be 4 while the number of holes on the circular center of the Fibonacci coil may be 8, or vice versa.
• FIGS. 7A-7C show various ways in which the legs of a Fibonacci coil can be terminated.
• the coil shown is the Fibonacci coil 400 of FIG. 4.
• the following teachings can be extended to any Fibonacci coil according to the present disclosure.
• FIG. 7A shows that all legs of the Fibonacci coil 400 can be directly connected to ground.
• FIG. 7B shows that all legs of the Fibonacci coil 400 can be connected to ground via a fixed capacitor.
• FIG. 7C shows that all legs of the Fibonacci coil 400 can be connected to ground via a variable capacitor.
• a controller e.g., see element 806 described below with reference to FIGS. 8A and 8B
• legs of a Fibonacci coil can be directly connected to ground while the remaining (one or more) legs of the Fibonacci coil 400 can be connected to ground via a fixed capacitor.
• some (one or more) of the legs of the Fibonacci coil 400 can be connected to ground via a variable capacitor while the remaining (one or more) legs of the Fibonacci coil 400 can be connected to ground via a fixed capacitor.
• some (one or more) of the legs of the Fibonacci coil 400 can be directly connected to ground while the remaining (one or more) legs of the Fibonacci coil 400 can be connected to ground via a variable capacitor. In additional examples, some (one or more) of the legs of the Fibonacci coil 400 can be directly connected to ground, some other (one or more) legs of the Fibonacci coil 400 can be connected to ground via a fix capacitor, and still other (one or more) legs of the Fibonacci coil 400 can be connected to ground via a variable capacitor, and so on.
• FIGS. 8A and 8B show a system 800 for supplying RF power to a Fibonacci coil according to the present disclosure.
• the Fibonacci coil can be any coil shown and described in the present disclosure.
• the system 800 comprises a RF generator 802, a matching circuit 804, a controller 806, and a Fibonacci coil 808.
• the RF generator 802 generates RF power and is similar to the elements 112 and 114 shown in FIG. 1.
• the matching circuit 804 matches the impedance of the Fibonacci coil 808 to the RF generator 802.
• the matching circuit 804 is similar to the element 113 shown in FIG. 1.
• the matching circuit 804 delivers RF power to the center of the Fibonacci coil 808 (e.g., to element 404 shown in FIG. 4 or to elements 604 shown in FIG. 6A).
• the controller 806 is similar to the controller 154 shown in FIG. 1 and controls the matching circuit 804 (e.g., the variable capacitors C1 and C3 of the matching circuit 804 shown in FIG. 8B) to match the impedances of the Fibonacci coil 808 and the RF generator 802.
• the variable capacitors C1 and C3 can have values in a predetermined range. The predetermined range can be calibrated for a particular Fibonacci coil design.
• the controller 806 can adjust the values of the variable capacitors C1 and C3 within the predetermined range to match the impedance of the Fibonacci coil regardless of the number of turns used.
• the controller 806 can adjust the values of the variable capacitors C1 and C3 automatically or can allow an operator to manually input into the system 800 the values for the variable capacitors C1 and C3 after changing the number of turns on a Fibonacci coil or after replacing one Fibonacci coil with another.
• the number of turns of a Fibonacci coil can be changed within a predetermined range (e.g., between X and Y turns) without changing the matching circuit 804.
• a predetermined range e.g., between X and Y turns
• the change in the inductance due to changes in the geometry and/or the number of turns of a Fibonacci coil are tuned out (i.e. , compensated) by the matching circuit 804 so long as the changes are within a range that can be handled by the variable capacitors C1 and C3.
• a different matching circuit may be used if a Fibonacci coil having a different design is used.
• another variable capacitor or capacitors may be added in series or in parallel to the variable capacitors C1 and C3 using suitable switching arrangement.
• the controller 806 can control the different matching circuit or the added capacitor or capacitors to match the impedance of the coil having the different design in the manner described above.
• the controller 806 can also control one or more variable capacitors connected to one or more legs of a Fibonacci coil (see FIG. 7C).
• the controller 806 can additionally control the gas supply to the processing chamber through the center of the processing chamber (e.g., via the injector nozzle 163 shown in FIGS. 1 and 6A) and/or through the side of the processing chamber (e.g., via elements 608 shown in FIG. 6A). Accordingly, by controlling a combination of coil design, matching (both the coil and one or more of its legs), and/or gas supply (both amount/rate and/or location of supply), the etch rates for different etch processes can be improved.
• FIG. 9 shows a schematic representation of a Fibonacci coil 900 mounted on the dielectric window 124 of the processing chamber 128 (e.g., see FIG. 6A).
• the Fibonacci coil 900 can be any Fibonacci coil described above and below in the present disclosure.
• h denotes a height of the Fibonacci coil 900
• d denotes a diameter of the Fibonacci coil 900
• n denotes the number of turns of the Fibonacci coil 900
• s denotes a skin depth of the plasma below the dielectric window 124.
• the Fibonacci coil 900 is smaller in diameter than the dielectric window 124.
• plasma density along the plane of the wafer in the plasma chamber depends on the source of plasma. Specifically, the plasma density in the processing chamber depends on the energy balance in the processing chamber. Additionally, plasma density distribution in the processing chamber depends on the particle balance in the processing chamber. Each is explained below in turn. [0084] More specifically, the plasma density depends on the amount of power deposited into the plasma by the coil and on the energy losses from the plasma. The amount of power deposited into the plasma depends on the impedance matching and the efficiency of the coil, which in turn is influenced by the geometry, the number of turns, and other design parameters of the coil such as the number of turns, the number of legs, the terminations of the legs, and so on. The Fibonacci coil designs of the present disclosure increase the efficiency with which power is deposited into the plasma, which in turn increases the plasma density in the processing chamber.
• the plasma density distribution which depends on the particle balance in the processing chamber, depends on the plasma source and sink (i.e. , loss) distribution within the processing chamber and the distance of the wafer from the plasma source.
• the plasma density distribution strongly influences uniformity.
• the plasma source i.e., the coil
• the plasma source i.e., the coil
• electron density peaks near the dielectric window while electron temperature is more uniform across the processing chamber.
• power deposition occurs only within a skin depth of the plasma below the dielectric window. Accordingly, if the coil is moved farther away from the dielectric window, the coupling between the coil, which acts as a primary coil, and the plasma, which acts as a secondary coil, decreases. As a result, more current needs to be supplied to the coil to maintain the same current in the plasma. Flowever, higher current in the coil leads to higher losses.
• the losses can be avoided and the current supplied to the coil can be reduced (i.e., the efficiency of the coil can be increased) by mounting the coil close to the dielectric window and by selecting coil design (e.g., number of turns, number of legs, terminations of legs, and so on) suitable for the etch process.
• coil design e.g., number of turns, number of legs, terminations of legs, and so on
• the coil area can be increased by increasing the number of legs, the number of turns, and/or the length of the Fibonacci coil while keeping the coil diameter smaller than the dielectric window.
• the efficiency of the coil can be maximized by using a Fibonacci coil having the largest diameter (less than the diameter of the dielectric window) and having the smallest number of turns, and by mounting the coil closest to the dielectric window.
• the power available for ionization (i.e., plasma generation) is equal to the power output by the RF generator minus the efficiency losses denoted by nP gen minus enthalpy losses.
• Radiation losses are included in the enthalpy losses and cannot be reduced for a given gas composition. Enthalpy losses can be reduced if the plasma is generated away from the walls and/or the dielectric window of the processing chamber further than the skin depth of the plasma below the dielectric window.
• Fibonacci coils of the present disclosure have a lower inductance than the other coil designs and can therefore produce higher currents at lower voltages than the other coil designs.
• Fibonacci coils of the present disclosure reduce the losses and improve the coil efficiency and the etch rate.
• the Fibonacci coil designs of the present disclosure provide improved power distribution than other coil designs, which translates into higher etch rates and In other examples, uniformity relative to other coil designs.
• the Fibonacci coils can also be removed, replaced, and their design can be altered more easily than the typically used inner and outer coils. This is because the Fibonacci coils use fewer electrical connections and mounting hardware compared to the inner and outer coils, which include at least eight electrical connections and use more mounting hardware than the Fibonacci coils. Further, the number of turns of the Fibonacci coils can be changed within a predetermined range instead of replacing the coil.
• the inner and outer coils are not as easily configurable as the Fibonacci coils.
• the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean“at least one of A, at least one of B, and at least one of C.”
• a controller is part of a system, which may be part of the above-described examples.
• Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and/or specific processing components (a wafer pedestal, a gas flow system, etc.).
• These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate.
• the electronics may be referred to as the“controller,” which may control various components or subparts of the system or systems.
• the controller may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and/or load locks connected to or interfaced with a specific system.
• temperature settings e.g., heating and/or cooling
• RF radio frequency
• the controller may be defined as electronics having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like.
• the integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software).
• Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system.
• the operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.
• the controller in some implementations, may be a part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof.
• the controller may be in the“cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing.
• the computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process.
• a remote computer e.g.
• a server can provide process recipes to a system over a network, which may include a local network or the Internet.
• the remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then communicated to the system from the remote computer.
• the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control.
• the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein.
• An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.
• example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and/or manufacturing of sem iconductor wafers.
• PVD physical vapor deposition
• CVD chemical vapor deposition
• ALD atomic layer deposition
• ALE atomic layer etch
• the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.

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• 2020
  • 2020-01-02 WO PCT/US2020/012076 patent/WO2020146189A1/en active Application Filing
  • 2020-01-02 CN CN202080008359.7A patent/CN113272935B/zh active Active
  • 2020-01-02 KR KR1020217024940A patent/KR20210102989A/ko unknown

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