February 12, 2010
Carnegie Mellon's Nanofabrication Facility and Data Storage Systems Center recently joined forces to acquire an STS ASPECT Cluster Reactive Ion Etching (RIE) system. Purchased primarily for its inductively coupled plasma (ICP) source, the etcher will build on the facility's current methanol RIE system and enhance existing complementary metal oxide semiconductor (CMOS) microelectromechanical systems (MEMS) device processing.
The new system features an input loadlock, output loadlock, wafer transfer chamber and two independent RIE process chambers — one configured for deep reactive ion etching (DRIE) and another configured for advanced oxide etching (AOE). The system is set up to work with 150 mm diameter substrates.
Researchers at Carnegie Mellon will use the DRIE process chamber to explore methanol-based plasma etching of magnetic materials. This chamber utilizes an ICP source, which the current methanol RIE system lacks, that will allow etching at higher plasma power densities and low independently controlled platen or substrate bias voltages. The ICP also increases the etch rate while minimizing any substrate bombardment during the etch.
"We've experienced great success with our current methanol etching facilities in the Nanofabrication Facility, but the new etcher's inductively coupled plasma source gives us a unique capability to develop a commercially viable process that will help us move the data storage industry forward," said DSSC Director and ABB Professor of Electrical and Computer Engineering Jimmy Zhu. "The ICP is much faster, and we look forward to using this technology to benefit our research efforts and that of our industrial sponsors."
"We are very excited about using this for nanomasking pattern transfer into magnetic thin films," said Physics Professor Sara Majetich, who also contributed funds toward the purchase of the new system.
The system's second chamber, the AOE process chamber, will allow users to etch thick silicon dioxide layers as well as trenches in glass substrates. This chamber also features an ICP source with independent substrate bias control, and will provide for high rate directional etching. The RIE currently used for oxide etching does not have ICP and requires lengthy etch times. The AOE process chamber will dramatically reduce etch times and provide more control of sidewall profiles. These additional capabilities will enhance the existing CMOS-based MEMS device processing by providing deeper and narrower etching of oxide layers while reducing the amount of aluminum layer erosion — all at much faster etch times.
While the STS ASPECT Cluster Reactive Ion Etching (RIE) system is not yet operational, Nanofabrication Facility technicians are reconfiguring the cleanroom and preparing for the system's installation.