Advanced Direct-Polishing Process Development of Non-Porous Ultralow-kDielectric Fluorocarbon with Plasma Treatment on Cu Interconnects

Abstract

A direct-polishing process was applied to the ultralow-k dielectric without a dielectric protective layer to reduce the effective dielectric constant in damascene interconnects. The direct-polishing process on organic non-porous ultralow-k dielectric, fluorocarbon (k = 2.2), was demonstrated and an optimum direct-polishing process condition was investigated. Mechanically enhanced chemical reaction on the fluorocarbon degraded the electrical properties by changing the structure of the fluorocarbon. Higher down-pressure, one of the most important factors in mechanical effects, resulted in both higher leakage current and a variance of the structure of th fluorocarbon. A surface nitrogen plasma treatment of fluorocarbon before polishing to form an effective protective layer was applied to avoid the degradation of electrical characteristics during the direct-polish, and this result revealed that the surface nitrogen plasma treatment of fluorocarbon is a practical technique for a direct-polishing process in advanced Cu interconnects.

Integration Process Development for Improved Compatibility with Organic Non-Porous Ultralow-k Dielectric Fluorocarbon on Advanced Cu Interconnects

“…It was reported that no change in the structure of fluorocarbon was found after chemical dipping only, such as dipping in slurry in CMP, in our previous study. [31][32][33] Therefore, this finding reveals that the change in the structure of fluorocarbon during DHF cleaning is a possible mechanism occurring after dry etching and this change in structure probably results in the increase in leakage current during post-etching DHF cleaning. To eliminate the effects of post-etching cleaning on the electrical properties, two kinds of post-etching plasma treatment were investigated.…”

“…On the other hand, NPT of the fluorocarbon film was also proved to protect the film from damage induced by CMP. [31][32][33] Therefore, NPT is critical and practical for the successful integration of the fluorocarbon film into Cu interconnects without dielectric degradation.…”

Determination of the characteristics of the metallic bonding interface and the bonding strength of a Cu interlayer by using atomic force microscopy

“…The quality of the wafer produced by using the bonding process can vary depending on which material is used to form the interlayer. Cu has recently attracted much attention as an excellent interlayer material as a result of its ideal electrical properties, good thermal conductivity, and long electromigration lifetimes [13][14][15]. However, Cu can also be rapidly oxidized at room temperature.…”

Film deposition and UV curing process impact on ultralow-kdielectric for high performance Cu interconnects

“…However, integration of porous low-k materials into Cu interconnects is a significant challenge due to poor mechanical strength as increasing the film porosity to reduce initial k-value for interlayer dielectric (ILD) film, the processinduced damage on ILD, and reliability issues. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] To use a dielectric material, which itself is resistant to physical and chemical damage, is very important. As the continued technology scaling, the development of the low-k materials is very difficult due to the achievable k-value is shifted to later technology generation by description of International Technology Roadmap for Semiconductors (ITRS).…”