Tribological Study of Brush Scrubbing in Post-Chemical Mechanical Planarization Cleaning in Non-porous Ultralow-k Dielectric∕Cu Interconnects

Abstract

Damage reduction during planarization is strongly required to avoid scratch generation and variation of electrical properties of low-k dielectrics that can lead to yield loss in an integrated circuit after implementation of an ultralow-k dielectric in Cu damascene interconnects. Three brush scrubbing conditions were found to realize high shear force for good particle removal. Having analyzed contact characteristics on an advanced non-porous ultralow-k dielectric fluorocarbon, brush scrubbing at a high rotation rate with a low down pressure is proposed to satisfy both sufficient particle removal efficiency and damage reduction during post chemical mechanical planarization cleaning. Tribological effects of down pressure and brush rotation rate on scratch and electrical properties of the ultralow-k fluorocarbon film are explored. To reduce the damage generated by the brush scrubbing process on the ultralow-k dielectric, it is important to make use of the effect of fluid flow by increasing the brush rotation rate at a low down pressure in advanced Cu interconnects in future.

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

“…Overburden Cu and TaN/Ta or TiN/Ti were polished by the chemical mechanical planarization (CMP) method. [18][19][20] Citric acid with additives, which has been reported as a suitable solution for cleaning without damage generation in the fluorocarbon film, was used. 21,22) A high brush rotation at a low applied down pressure of brush scrubbing cleaning condition, which has been reported to satisfy both good electrical properties and particle removal efficiency, was used for the post-CMP cleaning.…”

“…21,22) A high brush rotation at a low applied down pressure of brush scrubbing cleaning condition, which has been reported to satisfy both good electrical properties and particle removal efficiency, was used for the post-CMP cleaning. [23][24][25] Finally, a passivation SiCN film was formed, then a final annealing treatment was applied at 150 C.…”

Brush Deformation Effects on Poly Vinyl Acetal Brush Scrubbing

“…However, the main cleaning mechanism is still under discussion. [20][21][22][23][24][25][26][27][28][29] Proposed impurity removal mechanisms are divided mainly into techniques involving brush attachments, [20][21][22][23] fluid lubrication 24,25,[30][31][32][33] or mixed methods. [27][28][29]34 As a result, many researchers have investigated contact conditions (i.e., lubrication states 13,35 ).…”

Electrical Characteristics of Novel Non-porous Low-k Dielectric Fluorocarbon on Cu Interconnects for 22 nm Generation and Beyond

“…An overburden Cu and Ti/TiN were polished by the optimum CMP condition. [20][21][22] Citric acid with additives, which has been reported as the suitable cleaning solution without damage generation for the fluorocarbon film, was used as a cleaning solution. 23,24) A optimum brush scrubbing cleaning condition, which has been reported to satisfy both good electrical properties and particle removal efficiency, was used for the post CMP cleaning.…”