AVS 52nd International Symposium
    Manufacturing Science and Technology Tuesday Sessions
       Session MS-TuA

Paper MS-TuA5
Investigation of Low-k Dielectric Etching using Groovy ICP Plasma Source

Tuesday, November 1, 2005, 3:20 pm, Room 207

Session: Advanced Manufacturing Processes for Silicon Devices
Presenter: G.K. Vinogradov, FOI Corporation, Japan
Authors: A. Kelly, FOI Corporation, Japan
G.K. Vinogradov, FOI Corporation, Japan
Correspondent: Click to Email
Plasma etching of low-k dielectric materials, such as porous materials is presenting significant challenges to their introduction in copper dual damascene device production. Plasma damage is implicated in poor retention of low-k properties. We investigated plasma damage using a narrow gap inductive plasma source, Groovy ICP. Specially developed for 300mm low-k dielectric etching, it has three independently controllable highly efficient RF coils immersed in separate grooves machined in a planar roof. Each groove generates its own plasma toroid, both radial plasma density and chemical uniformity can be optimized. We investigated sidewall damage in dual damascene stack structures over a wide pressure range for porous low-k dielectrics. Only under conditions of low pressure, 5-10mTorr and low ion energy can sidewall damage be eliminated. With separate wafer bias control of ion energy, we can distinguish between ion and radical effects on sidewall damage of low k materials. Damage is by radical attack penetrating into the sidewall; therefore low-pressure ion dominant conditions are needed. Also low ion energy is needed as high ion energy conditions can sputter damage sidewalls. Groovy ICP is capable of achieving these conditions in a narrow gap, typical for low residence time oxide etchers. This shows its unique applicability for low-k dielectric etching including oxide layers.