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US 2015/0144596 A1Published application
Method for controlling ion energy distribution
AssigneeAdvanced Energy Industries, Inc.
InventorsVictor Brouk, Randy Heckman, Daniel J. Hoffman
Life of this patent
Estimating the term…
Abstract
Methods for regulating ion energies in a plasma chamber are disclosed. An exemplary method includes placing a substrate in a plasma chamber, forming a plasma in the plasma chamber, controllably switching power to the substrate so as to apply a periodic voltage function to the substrate, and modulating, over multiple cycles of the periodic voltage function, the periodic voltage function responsive to a desired distribution of energies of ions at the surface of the substrate so as to effectuate the desired distribution of ion energies on a time-averaged basis.
Claims10
A method for plasma-based processing, comprising:
- placing a substrate in a substrate support of a plasma chamber;
- forming a plasma in the plasma chamber;
- generating a periodic voltage function at a surface the substrate, each cycle of the periodic voltage function at the surface of the substrate including a positive pulse peak followed by a constant negative voltage that results in a monoenergetic distribution of ion energy at the surface of the substrate;
- wherein generating the periodic voltage function at the surface the substrate includes:
- producing a DC voltage with a DC voltage source, a magnitude of the DC voltage defines a magnitude of the constant negative voltage at the surface of the substrate and establishes the energy level of the monoenergetic distribution of ion energy at the surface of the substrate;
- coupling the DC voltage to the substrate support to apply a positive voltage pulse peak to the substrate support that effectuates the positive pulse peak at the surface of the substrate;
- decoupling the DC voltage from the substrate support and coupling a ground potential to the substrate support after the DC voltage is decoupled from the substrate support, wherein the application of the ground potential effectuates a drop in a voltage of the substrate support to a first-lower-level;
- decoupling the ground potential from the substrate support while maintaining the DC voltage decoupled from the substrate support;
- and
- providing, while the ground potential and the DC voltage are decoupled from the substrate support, a compensation current to the substrate with a current source that is separate from the DC voltage source to ramp down the voltage of the substrate support from the first-negative-lower-level to a second-negative-lower-level, wherein the ramp down of the voltage at the substrate support effectuates the constant negative voltage at the surface of the substrate, and the constant negative voltage at the surface of the substrate effectuates the monoenergetic distribution of ion energy at the surface of the substrate.
7 more elements
A method for plasma-based processing, comprising:
- placing a substrate in a substrate support of a plasma chamber;
- forming a plasma in the plasma chamber;
- producing a positive DC voltage with a DC power supply;
- connecting, by closing a first switch, the positive DC voltage to the substrate support to effectuate a positive pulse peak at the surface of the substrate, wherein the positive DC voltage charges an inherent capacitance C1 of components, including the substrate support, associated with the plasma chamber;
- disconnecting, by opening the first switch, the positive DC voltage from the substrate support and connecting, by closing a second switch, a ground potential to the substrate support, wherein the application of the ground potential to the substrate support effectuates a negative voltage at a surface of the substrate that prompts ion current of positive ions in the plasma toward the surface of the substrate;
- disconnecting, by opening the second switch, the ground potential from the substrate support;
- maintaining both the first and second switches open for a period of time t,
- providing with a current source, while the first and second switches are open, a compensation current to the substrate support to create a ramp down of the voltage of the substrate support during the period of time t, wherein the ramp down of the voltage at the substrate support compensates for a tendency of the ion current to change the voltage at the surface of the substrate in order to maintain the negative voltage at the surface of the substrate at a constant negative voltage, wherein the constant negative voltage at the surface of the substrate effectuates a monoenergetic distribution of ion energy at the surface of the substrate.
5 more elements
A method for plasma-based processing, comprising:
- placing a substrate in a substrate support of a plasma chamber;
- forming a plasma in the plasma chamber;
- receiving an ion-energy setting for a desired ion energy at a surface of the substrate;
- producing a positive DC voltage that has a magnitude that is determined by the ion-energy setting;
- connecting, by closing a first switch, the positive DC voltage to the substrate support to effectuate a positive pulse peak at the surface of the substrate;
- disconnecting, by opening the first switch, the positive DC voltage from the substrate support and connecting, by closing a second switch, a ground potential to the substrate support, wherein the application of the ground potential to the substrate support effectuates a negative voltage at a surface of the substrate that prompts ion current of positive ions in the plasma toward the surface of the substrate;
- disconnecting, by opening the second switch, the ground potential from the substrate support;
- maintaining both the first and second switches open for a period of time t,
- providing with a current source, while the first and second switches are open, a compensation current to the substrate support to create a ramp down of the voltage of the substrate support during the period of time t, wherein the ramp down of the voltage at the substrate support compensates for a tendency of the ion current to change the voltage at the surface of the substrate in order to maintain the negative voltage at the surface of the substrate at a constant negative voltage, wherein the constant negative voltage at the surface of the substrate effectuates the desired ion energy at the surface of the substrate.
6 more elements
Dependencies are inferred from the claim text.