Plasma Etch Rates of Porous Silica Low-k Films with Different Dielectric Constants

Abstract

The reactive ion etch rates of porous silica films with different dielectric constants (k-values) or film densities were measured by varying wafer bias and gas ratio for Ar/C5F8/O2 plasma. Both the etch rates of porous silica films and the optical emission intensities from the etching products (SiF) increased with wafer bias power. Etch rate increased with decreasing k-value of porous silica, whereas SiF emission intensity was maintained constant regardless of k-value, indicating that the amount of etching products escaping from the porous silica surface to the gas phase remained unchanged. From this result it is concluded that mass etch rate, defined as the weight of a porous silica film etched from a unit area per unit time, is constant for Ar/C5F8/O2 plasma.

Dielectric Barrier, Etch Stop, and Metal Capping Materials for State of the Art and beyond Metal Interconnects

“…The primary drawbacks to this approach are the difficulty of achieving perfect selectivity in the presence of inevitable surface defects, compatibility of the selective metal caps with next metal layer patterning and cleaning steps, and the added cost associated with the additional processing step. Etch selectivity.-While significant effort has been focused on understanding the influence of plasma etch chemistry, [349][350][351][352][353][354][355][356] low-k ILD porosity, 394 and ILD composition 395 on the low-k ILD plasma etch mechanisms and profiles, most ILD/ES etch selectivity studies have focused on a singular a-SiN:H or a-SiC:H ES material. Relatively little work has been reported investigating in detail how the properties and composition of the low-k ES can influence etch selectivity.…”

“…352 Low-k a-SiC:H and a-SiCN:H ES/DB materials have also been reported to exhibit high etch selectivities (2-10) relative to SiO 2 and low-k a-SiOC:H ILD materials. 38,353,354 The high etch selectivity has been similarly attributed to differences in the thickness of a deposited CF x layer that forms on the various surfaces during plasma etching. 104,[351][352][353][354] Additional studies by Posseme 355 and Standaert 106 have shown that the composition of the CF x layer is also an important consideration with lower etch rates being observed for CF x layers with reduced fluorine composition.…”

“…38,353,354 The high etch selectivity has been similarly attributed to differences in the thickness of a deposited CF x layer that forms on the various surfaces during plasma etching. 104,[351][352][353][354] Additional studies by Posseme 355 and Standaert 106 have shown that the composition of the CF x layer is also an important consideration with lower etch rates being observed for CF x layers with reduced fluorine composition. These same studies have also shown that the exact composition of the CF x layer is dependent on the plasma etch chemistry and plasma conditions.…”

Evaluation of Dielectric Constant through Direct Chemical Mechanical Planarization of Porous Low-k Film

“…10) Thus, improved plasma and/or ashing processes have been well researched and reported. [11][12][13][14][15][16][17] In addition, the uptake of water in nanoporous low-k materials significantly increases the k-values since water molecules have high k-values of $80. 3) The effects of water absorption on the electronic characteristics of LSI devices are reported.…”

Improvement of Adhesion at the Interface between Low-k Spin-on Dielectric and underlying SiCO Barrier by Plasma Treatments

“…In hp45nm generation, effective dielectric constant keff of 2.7-3.0 is necessary and k<2.4 is indispensable for realizing the appropriate performance [3]. Spin-on-dielectric (SOD) films are popularly examined as porous low-k material [4] as well as CVD films. In low-k materials, there are some issues such as peeling in Cu CMP process [5] and wire-bonding failure caused by the fragility of the material and low adhesion strength.…”