Patent ID: 8337713

Claim:
A method for etching a layer over a substrate in a capacitively coupled process chamber, wherein said capacitively coupled process chamber includes a first electrode and a second electrode, wherein said first electrode is disposed opposite of said second electrode, said method comprising: placing said substrate on said second electrode; positioning said first electrode and said second electrode at a distance from one another such that a gap of between about 0.5 to 4.0 cm exists between said first electrode and said second electrode, wherein an aspect ratio between a diameter of said substrate and said gap is between 30:1 to less than 60:1; providing an etching gas into said capacitively coupled process chamber; providing a first radio frequency power source for providing a power signal at a first frequency having a frequency power between 150 kHz and 10 MHz; into said second electrode in said capacitively coupled process chamber; providing a second radio frequency power source for providing a power signal at a second frequency having a frequency power between 12 MHz and 200 MHz; into said second electrode in said capacitively coupled process chamber; providing a first modulation control connected to said first radio frequency power source, to provide a controlled modulation of said first radio frequency power source at a frequency of between 1 kHz to 100 kHz; and providing a second modulation control connected to said second radio frequency power source, to provide a controlled modulation of said second radio frequency power source at a frequency of between about 1 kHz to about 100 kHz.