Featured Research

from universities, journals, and other organizations

New Surface Chemistry May Extend Life Of Technology For Making Transistors

Date:
September 30, 2004
Source:
University Of Illinois At Urbana-Champaign
Summary:
Researchers at the University of Illinois at Urbana-Champaign have developed a technique that uses surface chemistry to make tinier and more effective p-n junctions in silicon-based semiconductors. The method could permit the semiconductor industry to significantly extend the life of current ion-implantation technology for making transistors, thereby avoiding the implementation of difficult and costly alternatives.

CHAMPAIGN, Ill. -- Researchers at the University of Illinois at Urbana-Champaign have developed a technique that uses surface chemistry to make tinier and more effective p-n junctions in silicon-based semiconductors. The method could permit the semiconductor industry to significantly extend the life of current ion-implantation technology for making transistors, thereby avoiding the implementation of difficult and costly alternatives.

Related Articles


To make faster silicon-based transistors, scientists much shrink the active region in p-n junctions while increasing the concentration of electrically active dopant. Currently about 25 nanometers thick, these active regions must decrease to about 10 nanometers, or roughly 40 atoms deep, for next-generation devices.

The conventional process, ion implantation, shoots dopant atoms into a silicon wafer in much the same way that a shotgun sends pellets into a target. To be useful, dopant atoms must lie close to the surface and replace silicon atoms in the crystal structure. In the atomic-scale chaos that accompanies implantation, however, many dopant atoms and silicon atoms end up as interstitials -- lodged awkwardly between atoms in the crystal.

Ion implantation also creates defects that damage the crystal in a way that degrades its electrical properties. Heating the wafer -- a process called annealing -- heals some of the defects and allows more dopant atoms to move into useful crystalline sites. But annealing also has the nasty effect of further diffusing the dopant and deepening the p-n junction.

"We developed a way of using surface chemistry to obtain shallower active regions and enhanced dopant activation simultaneously," said Edmund Seebauer, a professor of chemical and biomolecular engineering at Illinois. "By modifying the ability of the silicon surface to absorb atoms from the substrate, our technique can control and correct the defects induced during implantation."

Inside the active region, atoms sitting on lattice sites have bonds to four neighbors, which saturates the bonding capacity of the silicon atoms. Atoms sitting on the surface have fewer neighbors, leading to unused, or "dangling" bonds. Atoms of a gas such as hydrogen, oxygen or nitrogen can saturate the dangling bonds.

"These dangling bonds can also react with interstitial atoms, and remove them from the crystal," Seebauer said. "The process selectively pulls silicon interstitials to the surface, while leaving active dopant atoms in place. The preferential removal of silicon interstitials is exactly what is needed to both suppress dopant diffusion and increase dopant activation."

Seebauer and his colleagues -- chemical and biomolecular engineering professor Richard Braatz and graduate research assistants Kapil Dev and Charlotte Kwok -- use ammonia and other nitrogen-containing gases to saturate some of the dangling bonds and control the ability of the surface to remove interstitials.

"The amount of surface nitrogen compound formed, and therefore the number of dangling bonds that become saturated, can be varied by changing the type of gas and the degree of exposure," Seebauer said. "As an added benefit, nitrogen compounds are also quite compatible with conventional chip manufacturing processes."

Through computer simulations and experimental verification, the researchers have shown that "defect engineering" by means of surface chemistry can extend the life of current ion-implantation technology and create smaller, faster electronic devices. Seebauer will present the team's latest findings at the 51st International Symposium of the AVS Science and Technology Society, to be held Nov. 14-19 in Anaheim, Calif.

Funding was provided by International SEMATECH and the National Science Foundation. The researchers have applied for a patent.


Story Source:

The above story is based on materials provided by University Of Illinois At Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University Of Illinois At Urbana-Champaign. "New Surface Chemistry May Extend Life Of Technology For Making Transistors." ScienceDaily. ScienceDaily, 30 September 2004. <www.sciencedaily.com/releases/2004/09/040930122341.htm>.
University Of Illinois At Urbana-Champaign. (2004, September 30). New Surface Chemistry May Extend Life Of Technology For Making Transistors. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2004/09/040930122341.htm
University Of Illinois At Urbana-Champaign. "New Surface Chemistry May Extend Life Of Technology For Making Transistors." ScienceDaily. www.sciencedaily.com/releases/2004/09/040930122341.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Who Will Failed Nuclear Talks Hurt Most?

Who Will Failed Nuclear Talks Hurt Most?

Reuters - Business Video Online (Nov. 25, 2014) With no immediate prospect of sanctions relief for Iran, and no solid progress in negotiations with the West over the country's nuclear programme, Ciara Lee asks why talks have still not produced results and what a resolution would mean for both parties. Video provided by Reuters
Powered by NewsLook.com
Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Reuters - Innovations Video Online (Nov. 25, 2014) A virtual flying enthusiast converts parts of a written-off Airbus aircraft into a working flight simulator in his northern Slovenian home. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
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

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