Post-W CMP cleaning

We observe that the Fe metal contamination problem is related to the post-W CMP cleaning chemistry used. We have found that the effectiveness of the chemistry to remove Fe contamination is in the order of... 

The post-W CMP cleaning with ammonia in the past has caused wafer surface defect issues. Is it possible for you to determine alternative cleaning chemistries for the post-W CMP process Explain why you think they will provide a more efficient process. 

In most cases, the trace metal left on the wafer surface after W CMP can be removed by a conventional post-CMP cleaning. Under some circumstances, a more aggressive post-W CMP cleaning that etches the oxide surface is needed to completely remove any trace metal left on the patterned wafer surface. 

W.-T. Tseng, E. Rill, B. Backes, M. Chace, Y. Yao, P. DeHaven, A. Ticknor, V. DevarapaUi, M. Khojasteh, D. Steber, L. Economikos, C. Truong, C. Majors, Post Cu CMP cleaning of polyurethane pad debris, ECS J. SoUd State Technol. 3 (1) (2014) N3023-N3031. 

A typical W CMP process consists of several polishing materials W, W liner (Ti and/or TiN), and Oxide [45-47]. In some unique W CMP applications, the process may involve the removal or sloping of other materials such as for SiN and poly-Si. The focus of this section will be on the popular stacks (W, Ti, TiN, and oxide) and the common defects left on the oxide surface after CMP and post-CMP cleaning [48,49]. 

Chapters 1 and 2 introduce the CMP process and historical motivations. The present status of CMP is discussed in Chapter 2, which focuses on establishing the need of advanced metallization schemes and planarization. There are a large number of variables that control the process these are discussed in Chapter 3. Chapter 4 presents the science of CMP— mechanical and chemical concepts important in understanding the CMP fundamentals. The CMP of the Si02 films, the most commonly used insulator interlayer dielectric, is discussed in Chapter 5. Chapters 6 and 7 cover the CMP of the two most studied metals, W and Cu, respectively. Chapter 8 examines the applicability of CMP to new materials, e.g., Al, polymers, and Si3N4 photoresists. Finally, Chapter 9 covers post-CMP cleaning science and technology. 

D.W. Cooper, R.C. Linke, and M.T. Andreas, Comparing the effectiveness of Knobby and ridged post-CMP cleaning brushes, MICRO, July/August 1999. 

The slurry is the third important key player among the three listed above. Key slurry parameters that affect CMP are discussed in Chapter 3. Slurries provide both the chemical action through the solution chemistry and the mechanical action through the abrasives. High polishing rates, planarity, selectivity, uniformity, post-CMP ease of cleaning including environmental health and safety issues, shelf-life, and dispersion ability are the factors considered to optimize the slurry performance. For hard materials like W and Ta mechanical effects are more important. On the other hand for soft... 

Part li Pads and Related Issues, Part III Metal Polishing—W and Al, Part IV Copper Polishing and Related Issues, Part V CMP Modeling and Fluid Flow, and Part Vi Particle Adhesion and Post-Polish Cleaning. 

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