The effect of polymer hardness, pore size, and porosity on the performance of thermoplastic polyurethane-based chemical
- PDF / 829,442 Bytes
- 14 Pages / 584.957 x 782.986 pts Page_size
- 86 Downloads / 175 Views
Solid-state microcellular foaming (SSMF) process was used to produce porous chemical mechanical polishing (CMP) pads in a variety of pore size and porosity range, using a variety of thermoplastic polyurethane (TPU) resin hardness. By controlling the pore size, porosity, and pad hardness, one is able to manufacture CMP pads that offer tunable pad properties. A brief introduction to the SSMF manufacturing process and thereby, unique microstructures created is first addressed followed by inner layer dielectric (ILD) CMP results, describing the effects of top TPU foam sheet properties, such as hardness, pore size, and porosity on ILD removal rate (RR) and wafer defects. Softer TPU-based porous pads showed significantly lower wafer scratch counts, while only a moderate increase in the ILD RR was seen with increasing resin hardness for similar pore size and porosity pads. Pore size has insignificant influence on wafer defect count but has significant influence on the ILD RR profile. CMP pads made from small pore size foams cause a nonflat RR profile.
I. INTRODUCTION A. Chemical mechanical polishing process
In multilevel metallization or interconnection scheme used for the manufacturing of integrated circuits (IC), the metal interconnections are not confined to one plane; they span several planes and are isolated by insulating layers and connected by the wiring in the third dimensions through holes in the dielectric planes.1–3 Chemical mechanical polishing (CMP) is a process that creates smooth and planarized surface. CMP is the process of choice to planarize the constituent materials of IC interconnect scheme.2–6 For this reason, the CMP process is also known as chemical mechanical planarization. An excellent review on CMP process technology has been published by Zantye et al.5 Over a decade, CMP has been the fastest growing process technology in IC manufacturing. In 2012, worldwide sale of CMP consumables were well over $2.5 billion and still growing at a healthy pace. CMP steps accounts for up to one-third of all chip-manufacturing steps. One of the plausible mechanisms of CMP is the three body contact where the high points of the wafer and pad asperities come in contact with each other in the presence of abrasive slurry (see Fig. 1).1–5 Figure 1 shows schematic of a typical CMP tool that consists of the following essential parts: platen that holds the polishing pad, pad conditioner, a wafer carrier, and a slurry arm dispenser. Address all correspondence to these author. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2013.173 2380
J. Mater. Res., Vol. 28, No. 17, Sep 14, 2013
http://journals.cambridge.org
Downloaded: 27 Jan 2015
During CMP, the wafer to be planarized is held at pressure by a retaining ring pressed face down against a rotating polishing pad soaked with chemically and physically active slurry.2–5 Typically slurry contains small abrasive particles (,100 nm) such as alumina, ceria, or silica at concentrations ranging from 0.10% by weight to 25% by weight. Slurry
Data Loading...
