CMP for hard-disk drives spotlighted at NCCAVS CMPUG

September 15, 2011 – About 30 well-polished professionals (pun intended) attended the September meeting of the NCCAVS CMP Users Group at SEMI headquarters in San Jose. The agenda comprised several topics for a combination of technical, technical marketing, and marketing presentations, with the overall theme of CMP for hard disk drive industry. Presentations will be posted in the coming weeks at CMP User Group proceedings. Note that the HDD industry uses CMP in two distinct ways: flattening and surface texturing of the disk storage platter, and planarization steps in the thin-film head process. All of the speakers addressed the thin-film head CMP process, unless otherwise noted.

Mark Geenen of TrendFocus kicked off the meeting with his HDD market outlook. He sees no growth in notebook PCs (flat in 2011, <5% in 2012) and a decline in desktop PCs, as tablet PCs and smart phones decrease the demand for their less-portable predecessors. A consequence is that the usable life of the notebooks tends to increase as their use demand drops, which slows the replacement market. Solid-state drives are still at a substantial cost disadvantage and are prevalent only in the Mac Airbooks. The hard-drive market is growing due to non-PC applications, up 4% to a 2011 TAM of $679M, with another 8% expected in 2012 to $730M. Cloud storage alone is a huge new HDD market. Seagate, Western Digital, and Toshiba appear to be the last three HDD manufacturers standing; Seagate’s acquisition of Samsung’s HDD business appears to be on track; WD’s acquisition of Hitachi Global may be delayed by the EU, but closure is still expected 4Q11.

Dan Trojan of Axus Technology gave an overview of the company’s advanced carrier head technology after a walk down memory lane, peering as far back as wax-mounted wafers. (If you remember that, I’m willing to bet that you are using an enlarged font to read this.) The Axus heads can be retrofit onto all of the major tools used in HDD CMP, which by-and-large are the early workhorse models of semiconductor CMP.

Continuing the polisher head theme, Sarah Okada of Strasbaugh talked about the differences between IC and HDD polishing heads. To my chagrin, she pointed out that Strasbaugh has a wax-mounted polisher system that is still a good seller, and is the only one remaining on the market today. She also had a nice chart showing similarities and differences among IC, HDD, MEMS, TSV, and LED polishing.

Jack Cole of Morgan Technical Ceramics switched the subject to CVD diamond pad conditioners, the present-day incarnation of the Diamonex technology that I had the pleasure of working on in 1998/1999. While most conditioners work with exposed diamond grit surfaces, the Morgan product has a CVD diamond film with its own micro-texture over the diamond grit. It is the CVD film that does the conditioning work; life testing has shown that the bare diamond grit is never exposed over normal lifetime usage. As a result, newer models for 32nm and 22nm are being fabricated with diamond CVD films over ceramic pedestals.

Ramin Emami of Hitachi Global Storage Technologies spoke about CMP-related challenges in improving first-pass yield of GMR thin-film heads. R/W heads require between eight and 13 CMP steps in the latest generations. Root cause methods were used to track down a systemic deep scratch issue and eliminate the problem. During the course of the study, the more expensive consumable set was found to produce significantly fewer yield excursions, with particular significance attributed to the pad conditioner. I am guessing that the supplier will be alert enough to turn this into additional market share.

The final talk of the day was given by Kurt Rubin, also from Hitachi Global Storage Technologies, speaking on the emergence of patterned media in HDD systems, and use of CMP thereupon. The 650M HDD systems shipped in 2010 represent a minimum of 1.3B media surfaces, higher still because many HDD systems contain more than one platter. This represents the eventual market potential for patterned media. One master disk can be used to fabricate 10,000 production masters, which in turn can be used to produce 100M platters by nanoreplication. The indentations are typically 10nm deep and create magnetic islands. The recesses are filled with a dielectric material (SiO2 or SiN) atop a thin stop layer (SiN or C) and a thin Si adhesion layer, and planarized damascene-style by CMP to appear aerodynamically smooth to the R/W heads. Polishing recesses <2nm have been achieved, with an average recess of 1.3nm across all disk features. (Unfortunately, slides for the two Hitachi Global presentations will not be available for posting on the NCCAVS CMPUG website.)

Michael A. Fury, Ph.D, is senior technology analyst at Techcet Group, LLC, P.O. Box 29, Del Mar, CA 92014; e-mail [email protected].


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