Featured Research

from universities, journals, and other organizations

New Five-Level Layering Process Pioneered By Sandia Promises More Reliable, Complex Micromachines

Date:
September 22, 1999
Source:
Sandia National Laboratories
Summary:
A new advanced five-level polysilicon surface micromachining process pioneered at the Department of Energy's Sandia National Laboratories promises that microelectromechanical systems (MEMS) of the future will be more reliable and capable of doing increasingly complex tasks.

ALBUQUERQUE, NM -- A new advanced five-level polysilicon surface micromachining process pioneered at the Department of Energy's Sandia National Laboratories promises that microelectromechanical systems (MEMS) of the future will be more reliable and capable of doing increasingly complex tasks.

Related Articles


"This five-level polysilicon surface micromachining technology has potential of becoming the industry standard, replacing the more commonly used two- or three-level polysilicon surface micromachining approaches," says Steve Rodgers, Sandia engineer who together with colleague Jeff Sniegowski has spent the past several years prototyping designs and developing the innovative process. "We have been working hard to baseline the technology as a reproducible manufacturing process, and we're getting there."

The new technology was developed at Sandia's Microelectronics Development Laboratory. MEMS devices made from the five-level process will eventually be manufactured in the new Microsystems and Engineering Sciences Application (MESA) facility being planned for construction at Sandia.

MEMS, complex machines with micron-size features, can be found in a variety of products, including optical devices, computer game joy sticks, car airbag sensors, inkjet printers, projection displays and more. They are so small that they are almost imperceptible to the human eye and have moving parts no bigger than a red blood cell.

Sandia will begin offering the five-level technology next spring to external customers for prototyping purposes. Information about all MEMS courses is available at Sandia's micromachine Web page located at http://www.mdl.sandia.gov/micromachine.

Almost all of today's surface micromachine components are designed for and fabricated in technologies that incorporate three or fewer levels of structural materials. The levels are typically deposited as thin films of polysilicon that are about one to two microns thick. These films are separated by air gaps that are initially defined by layers of sacrificial silicon dioxide (sacrificial because they will eventually be eliminated) of about the same thickness. Processes with thicker polysilicon film -- up to tens of microns -- exist, but are typically limited to only that layer.

"In general, the more layers of structural material that a designer has to work with, the more complicated the device that can be fabricated," says Sniegowski, who developed the fabrication technology for the five-level layering method. "Therefore, surface micromachined components have greater functionality than bulk micromachined parts."

He adds that's why the five-level polysilicon surface micromachine process that incorporates four layers of structural films plus an electrical interconnect layer is so attractive.

"This technology permits mechanical functionality that only a five or more layer process could offer," Sniegowski says." It provides a base for designing truly sophisticated multilevel microelectromechanical systems, while simultaneously offering much of the yield and robustness that is typically associated with single-level micromachining technology."

A two-level polysilicon process has only one layer of structural material, with the other level defining the ground plane. Such a technology is useful for fabricating simple sensors and actuators.

With three levels it is possible to create gears with hubs, while the four-level technology provides an additional layer of material that can be used to define linkage arms that move above the plane of the gears, enabling a continuous 360-degree rotation.

The five-level technology expands on this to permit complex interacting mechanisms to be fabricated on moving platforms.

But to do this, several challenges had to be overcome, which Sniegowski and Rodgers have met. For example, as additional layers are added, more texture appears on the surface. This occurs because the top layer acquires the characteristics of all the lower layers, including high and low spots. The result is the creation of protrusions, called "mechanical parasitics," that extend from the upper mechanical layer to lower areas. They can interfere with operation.

These parasitics, Sniegowski says, can significantly "constrain the design." If the design doesn't take them into account, they could easily "collide with the teeth and prevent rotation of the gear."

To eliminate this problem, a Sandia team led by process engineer Dale Hetherington modified and patented a process commonly used in manufacturing integrated circuits -- chemical mechanical polishing -- to planarize (flatten) the surface. High spots are eliminated after a very thick layer of sacrificial oxide covers all previous layers. Through chemical mechanical polishing, the high spots are eroded, producing a uniform flat surface.

Rodgers says the new five-layer process provides a foundation for fabricating components that offer high performance, reliability, and robustness. However, work continues to improve the process even further.

"We are now adding the final touches before offering it for widespread use," he says.


Story Source:

The above story is based on materials provided by Sandia National Laboratories. Note: Materials may be edited for content and length.


Cite This Page:

Sandia National Laboratories. "New Five-Level Layering Process Pioneered By Sandia Promises More Reliable, Complex Micromachines." ScienceDaily. ScienceDaily, 22 September 1999. <www.sciencedaily.com/releases/1999/09/990922050614.htm>.
Sandia National Laboratories. (1999, September 22). New Five-Level Layering Process Pioneered By Sandia Promises More Reliable, Complex Micromachines. ScienceDaily. Retrieved November 24, 2014 from www.sciencedaily.com/releases/1999/09/990922050614.htm
Sandia National Laboratories. "New Five-Level Layering Process Pioneered By Sandia Promises More Reliable, Complex Micromachines." ScienceDaily. www.sciencedaily.com/releases/1999/09/990922050614.htm (accessed November 24, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Monday, November 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Car Park Solution for Flexible Green Energy

Car Park Solution for Flexible Green Energy

Reuters - Innovations Video Online (Nov. 24, 2014) A British solar power start-up says that by covering millions of existing car park spaces around the UK with flexible solar panels, the country's power problems could be solved. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Microsoft Adds Robot Guards, Ushers In Sci-Fi Apocalypse

Microsoft Adds Robot Guards, Ushers In Sci-Fi Apocalypse

Newsy (Nov. 23, 2014) Microsoft has robotic security guards working at its Silicon Valley Campus. Video provided by Newsy
Powered by NewsLook.com
Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

AFP (Nov. 21, 2014) Toyota presented its hydrogen fuel-cell compact car called "Mirai" to US consumers at the Los Angeles auto show. The car should go on sale in 2015 for around $60.000. It combines stored hydrogen with oxygen to generate its own power. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
Google Announces Improvements To Balloon-Borne Wi-Fi Project

Google Announces Improvements To Balloon-Borne Wi-Fi Project

Newsy (Nov. 21, 2014) In a blog post, Google said its balloons have traveled 3 million kilometers since the start of Project Loon. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins