CMP-MIC: 3Ms no-slurry pads, Lams polisher

05/01/1998

CMP-MIC: 3M`s no-slurry pads, Lam`s polisher

The CMP-MIC conference held in Santa Clara, CA, saw the introduction of 3M Laboratories` new slurry-free oxide planarization technique, and the long-awaited linear CMP polisher from Lam Research`s OnTrak subsidiary.

3M Laboratories` no-slurry pads. 3M`s planarization technique, which has been in development for several years, offers higher throughput and a simpler approach than conventional CMP slurry methods, according to 3M Laboratories` researchers at the conference. Abrasive particles are embedded in the pad - rather than the pad being soaked with a slurry - and the abrasive pad is injected with DI water or a potassium solution for polishing. 3M`s pad consists of a three-layer sandwich, incorporating a soft underlayer about 90 mils thick for polishing uniformity, and a hard layer about 20 mils thick for promoting planarization. The top layer, according to the researchers, is a microreplicated pyramidal structure composed of cerium particles embedded in a resist matrix.

The method, according to 3M, eliminates conventional CMP slurry handling, pad conditioning, and pad-to-pad performance inconsistency challenges, while offering higher throughput, high removal rate, and polishing fluid simplicity. The technique is said to have polishing times about half as long as conventional CMP methods.

The process, however, does have its own limitations. Unlike current methods, it requires a buffing step, and work is ongoing to improve defectivity and evaluate pad life time.

Lam`s CMP polisher. Lam Research Corp. has unveiled the long-awaited Teres CMP system, which uses the linear polishing technology it acquired with its purchase of OnTrak Systems last year, and plans to ship the first system this quarter.

The linear polishing tool is a dry in/dry out system said to offer a 3-to-1 planarization efficiency over conventional tools, and eliminates pattern density effects, dishing, and erosion problems of conventional methods.

The system uses two stations for linear polish, one for proprietary rotary buff and an integrated cleaner incorporating OnTrak cleaning technology. It also extends to 180-nm or smaller geometries, and scales to accommodate 300-mm wafers. - C.L.