| AVS 58th Annual International Symposium and Exhibition | |
| Plasma Science and Technology Division | Tuesday Sessions |
| Session PS1-TuA |
| Session: | Advanced BEOL / Interconnect Etching II |
| Presenter: | Vincent Omarjee, American Air Liquide – Delaware Research and Technology Center |
| Authors: | A.J. Gildea, College of Nanoscale Science and Engineering, the University at Albany-SUNY J.C. Long, College of Nanoscale Science and Engineering, the University at Albany-SUNY E. Eisenbraun, College of Nanoscale Science and Engineering, the University at Albany-SUNY V. Omarjee, American Air Liquide – Delaware Research and Technology Center F. Doniat, American Air Liquide – Delaware Research and Technology Center N. Stafford, American Air Liquide – Delaware Research and Technology Center C. Dussarrat, American Air Liquide – Delaware Research and Technology Center |
| Correspondent: | Click to Email |
Semiconductor manufacturing is facing major integration challenges. The introduction of ultra low-k materials (k=2.5 and below) in BEOL processing combined with the always shrinking dimensions increased the number of film parameters such as LER or species diffusion that need to be perfectly mastered. In particular, the use of porous dielectrics to reduce permittivity is done at the expense of film chemical and mechanical robustness. With films having porosity ranging from 15 to 30%, patterning collapse, impurity diffusion and other defects are becoming serious issues. A negative impact on interconnect reliability and performance is observed unless tight process controls and/or new approaches are employed. To overcome the defects created during the low-k patterning, one approach that is considered here is the use of new etch gases. Among the possible choices, CF3I has seen increased momentum over the past years. When the first studies >10 years ago demonstrated some interesting features of CF3I such as a GWP<1, the benefits were still too marginal to consider a fundamental change for dielectric etching in the semiconductor industry. Recently, with the increasing challenges to be overcome when etching the low-k, alternatives such as CF3I are receiving increased attention.
In this talk we will present a comparison of the etching performance such as etch rate and selectivity of CF3I alone or in combination with standard fluorocarbons such as CF4 and C4F8.
Etching rate measurements performed on blanket porous low-k films (k=2.4) showed comparable values between CF3I and the standard gases; therefore demonstrating no loss of throughput. Possible iodine incorporation during the process was carefully monitored and found to be negligible. Iodine, if detected, is usually at the detection limit of the tools (<0.4 at.%) and concentrated at the film surface therefore could be easily removed during the subsequent ashing and cleaning steps.
Patterned structure etch testing was performed and optimized using a DOE approach. CF3I was found to be suitable to obtain nicely etched features. In many cases, better etched structures and higher selectivity were obtained using CF3I compared to the standard gases.