High density plasma tool with adjustable uniformity and stochastic electron heating for reduced gas cracking
First Claim
1. A method of controlling plasma density including the steps ofapplying a VHF/UHF signal having a frequency equal to or greater than 40 MHz across generally radial antenna elements to produce a voltage having a standing wave component therein, and adjusting a voltage profile of said standing wave component along said generally radial antenna elements to produce a substantially uniform plasma density by capacitive coupling power to said plasma in accordance with said voltage profile.
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Accused Products
Abstract
VHF/UHF power having a frequency of about 40 MHz or higher is applied across generally radial elements of an antenna and the phase of a standing wave component of the voltage in the generally radial elements is adjusted to provide relatively uniform density of a high density plasma across an area of at least the size of a semiconductor wafer being processed. Capacitive coupling of power to the plasma enhances the hot tail distribution of electron energies which is associated with low levels of gas cracking and the production of radicals such as fluorine which are not material-selective in semiconductor processing operations such as oxide etching. Accordingly, material-selectivity of processes may be maintained while the high density plasma accelerates the process to significantly improve tool throughput.
59 Citations
20 Claims
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1. A method of controlling plasma density including the steps of
applying a VHF/UHF signal having a frequency equal to or greater than 40 MHz across generally radial antenna elements to produce a voltage having a standing wave component therein, and adjusting a voltage profile of said standing wave component along said generally radial antenna elements to produce a substantially uniform plasma density by capacitive coupling power to said plasma in accordance with said voltage profile.
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4. An antenna for coupling electrical power to a plasma including
a first plate having a plurality of generally radial elements, a second plate electrically connected to outer ends of said generally radial elements, a third plate forming a distributed capacitance with said second plate and electrically connected to inner ends of said generally radial elements, and a capacitive impedance from said second plate to ground.
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10. A plasma tool including
an antenna having a plurality of generally radial elements, means for applying VHF/UHF power of a frequency of about 40 MHZ or higher across said generally radial elements to establish a voltage thereon having a standing wave component, and means for adjusting phase of said standing wave component to control a voltage profile along said generally radial elements to produce a substantially uniform plasma density by capacitive coupling power to said plasma in accordance with said voltage profile.
Specification