Polymer Cleaning From Porous Low-$k$ Dielectrics in $\hbox{He/H}_{2}$ Plasmas

Porous dielectrics such as SiCOH are used as the insulator in interconnect wiring in microelectronics devices to lower the dielectric constant and therefore decrease the resistive-capacitive delay. After etching a trench in low-k; di electrics in fluorocarbon plasmas, a CF_x polymer remains on the sidewalls, which must be removed in a manner that does not damage the low-k material. This can be accomplished using He/H₂ plasmas, which produce hot H atoms (i.e., energy >; 1 eV). We present images of the distributions of hot H atoms and H⁺ ions from an inductively coupled plasma and their resulting cleaning of a trench etched in SiCOH.

Porous dielectrics having a low dielectric constant (low-) are being used to lower interconnect-wiring capacitance to limit the resistive–capacitive time delay in integrated circuits. [1] SiCOH, i.e., silicon dioxide with groups lining the pores, is one commonly used material, having porosities as large as 50% with pore diameters of up to a few nanometers. Such dielectrics are typically etched in fluorocarbon plasmas in which there is deposition of a polymer. The polymer is then removed by a subsequent plasma clean to enable the deposition of diffusion barriers of metals such as Ti and Ta [1]. During the removal process, the photoresist (PR) is also typically removed. plasmas are generally used for such removal; however, these plasmas are often damaging to SiCOH. plasmas are being investigated for polymer and PR removal to reduce the potential damage to SiOCH [2].