Method and apparatus for low pressure sputtering
First Claim
1. A method of sputtering comprising the steps of:
- supporting a substrate in a vacuum sputtering chamber facing a target of a sputter coating material mounted on a sputtering cathode assembly in the chamber;
establishing a vacuum pressure of gas within the chamber;
coupling RF energy from a supplemental plasma electrode into gas in the chamber;
controlling the combined pressure in the chamber and the power to the supplemental plasma electrode at a level to ignite a plasma in the gas in the chamber;
following ignition of the plasma;
energizing the target with a target power supply so as to initiate the sputtering of coating material from the target with ions from the plasma;
thenwhile the target is energized, reducing the combined pressure and power to the supplemental plasma electrode to a level below that required for ignition of the plasma but above a level required to sustain the plasma so as to sputter the coating material from the target;
then, continuing to energize the target to a degree sufficient to sputter material from the target at a pressure of less than 1 mTorr to thereby coat the substrate with the sputtered material.
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Accused Products
Abstract
Sputtering processes are carried out at low pressure, of less than one milli-Torr, particularly in the range of 0.05 to 0.5 mTorr, to reduce scattering of the sputtered particles due to collisions with atoms of the process gas, particularly for coating contacts at the bottoms of sub-micron sized holes of high aspect ratios. The sputtering is made possible by provision for a supplemental RF plasma generating source by which RF energy is reactively coupled into the gas within the chamber in close proximity to the surface of a sputtering target, preferably adjacent the periphery thereof. The pressure in the chamber as well as the power to an RF electrode by which the supplemental plasma is energized and the DC power by which the main target is energized are dynamically controlled so that the plasma is sustained at low pressure. First, the pressure in the chamber is raised to above 1 mTorr while the RF power on the supplemental electrode is applied to ignite the plasma, then this RF power is reduced and DC power on the target is increased to an operating level, whereupon the pressure in the chamber is reduced to below 1 mTorr for the low pressure sputtering of the wafer.
98 Citations
12 Claims
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1. A method of sputtering comprising the steps of:
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supporting a substrate in a vacuum sputtering chamber facing a target of a sputter coating material mounted on a sputtering cathode assembly in the chamber; establishing a vacuum pressure of gas within the chamber; coupling RF energy from a supplemental plasma electrode into gas in the chamber; controlling the combined pressure in the chamber and the power to the supplemental plasma electrode at a level to ignite a plasma in the gas in the chamber; following ignition of the plasma; energizing the target with a target power supply so as to initiate the sputtering of coating material from the target with ions from the plasma;
thenwhile the target is energized, reducing the combined pressure and power to the supplemental plasma electrode to a level below that required for ignition of the plasma but above a level required to sustain the plasma so as to sputter the coating material from the target; then, continuing to energize the target to a degree sufficient to sputter material from the target at a pressure of less than 1 mTorr to thereby coat the substrate with the sputtered material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification