By Dr Mike Cooke

Novellus Systems claims the industry's first standalone ultraviolet thermal processing (UVTP) system targeted at the post-deposition processing of advanced dielectric films. The SOLA system is designed for high-volume manufacturing at 300mm.

SOLA can process transistor-level high-stress nitrides (HSN) and interconnect-level dense or porous low-k dielectrics. Using a combination of UV light and heat, SOLA makes post-deposition treatment of these films possible at lower temperatures, a necessity when integrating new materials such as nickel silicide.

Wafers with a previously deposited plasma-enhanced chemical vapor deposition (PECVD) film are introduced into SOLA, where they are exposed to a uniform UV lamp source to modify the film's properties. At the same time, the wafer is heated to a uniform temperature, typically 450°C or less.

With HSN films, SOLA's UV radiation promotes bond rearrangement and volume contraction to generate the higher stress levels required to enhance device performance. With porous low-k films, UV radiation facilitates removal of porogen, and mechanically strengthens the dielectric film for further processing.

SOLA's proprietary lamp assembly includes dual linear lamps and custom optical reflectors optimally arranged to provide uniform UV light exposure on a 300mm wafer. This arrangement minimizes infrared (IR) light that causes undesirable wafer heating and non-homogeneous treatment results. SOLA's patented multi-station sequential treatment (MSST) architecture results in both high throughput and treatment non-uniformity is reduced to less than 2%.

SOLA also offers independent control of UV light intensity, temperature and process time at each treatment station. Tim Archer, senior vice president and general manager of Novellus' PECVD and Electrofill business units, comments: "While current applications are focused on porous low-k and HSN films, we foresee that there may well be other films that can benefit from the process flexibility afforded by SOLA."

The platform also incorporates proprietary purge hardware that minimizes clean requirements during wafer processing. More than 100 porogen-containing wafers may be processed in SOLA before a chamber clean is required, a purge efficacy as much as 20 times higher than the industry average, claims Novellus.

Novellus has already shipped SOLA to customers in Europe, North America and Asia.