Engineers Identify Materials for nMOS Metal Gate Electrodes

Mar 30, 2006

Sematech engineers have identified metal electrode materials that can be used to build reliable nMOS transistors with high‑k dielectric – a major milestone in the quest to fabricate working CMOS devices using metal gate and high-k dielectric stacks.

In recent years, the semiconductor industry has struggled with high gate leakage current and the limited scalability of SiO2 gate dielectrics. While high-k dielectrics were seen as an alternative, it has proven very difficult to find metal electrode materials to replace n- and p-type doped polysilicon gates.

In many cases, metal electrode materials showing workfunctions close to n+ or p+ type doped polysilicon gates reverted to unusable mid-gap workfunctions after going through CMOS device processing. That’s because the effective workfunction of metal electrodes is affected by several factors, including composition, underlying dielectric and heat cycles. Thus, the fabrication of metal-oxide semiconductor field-effect transistors (MOSFETs) with metal gates comparable to polysilicon gate MOSFETs has remained a huge challenge to industry researchers.

The accomplishment, involving nMOSFETs with metal electrodes showing an effective workfunction close to ~4.0eV, caps a three-year project involving nearly 40 engineers at Sematech and collaborating universities and suppliers. Technical details will be shared during the 2006 Symposium on VLSI Technology, scheduled June 13-15 in Honolulu, Hawaii.

“We systematically screened more than 250 material systems on various dielectrics,” said Byoung Hun Lee, manager of the Advanced Gate Stack Program in Sematech’s Front End Processes (FEP) Division. “From this work, we developed an understanding of how metal electrode materials and high-k dielectrics react, and how the effective workfunction of metal electrodes can be controlled to yield an effective workfunction close to that of doped polysilicon gates.”

Lee added, “Our approach will enable the industry to implement metal electrodes with minimum modifications to current CMOS process flow.”

Sematech’s progress on nMOSFET metal electrode technology comes on the heels of last year’s related breakthroughs in channel mobility and reliability of high-k metal gate transistors (www.sematech.org/corporate/new… eleases/20050425.htm). That FEP work involved a halfnium silicate (HfSiO) dielectric with an equivalent oxide thickness (EOT) of roughly 10 angstroms (Å) with a metal gate, achieving mobility of 90 percent of the universal mobility curve for SiO2.

“These potential solutions for metal gate nMOSFETs bring high-k technology to a more practical realm,” said FEP Director Rajarao Jammy. He said key data and process details will be provided to Sematech members, and some details of the material systems for nMOSFET will be presented at upcoming technical conferences to promote consensus and additional research from industry and academia.

Source: Sematech

Explore further: US official: Auto safety agency under review

add to favorites email to friend print save as pdf

Related Stories

Russia turns back clocks to permanent Winter Time

3 hours ago

Russia on Sunday is set to turn back its clocks to winter time permanently in a move backed by President Vladimir Putin, reversing a three-year experiment with non-stop summer time that proved highly unpopular.

UN climate talks shuffle to a close in Bonn

3 hours ago

Concern was high at a perceived lack of urgency as UN climate negotiations shuffled towards a close in Bonn on Saturday with just 14 months left to finalise a new, global pact.

Microsoft beefs up security protection in Windows 10

8 hours ago

What Microsoft users in business care deeply about—-a system architecture that supports efforts to get their work done efficiently; a work-centric menu to quickly access projects rather than weather readings ...

US official: Auto safety agency under review

21 hours ago

Transportation officials are reviewing the "safety culture" of the U.S. agency that oversees auto recalls, a senior Obama administration official said Friday. The National Highway Traffic Safety Administration has been criticized ...

Recommended for you

Microsoft beefs up security protection in Windows 10

17 hours ago

What Microsoft users in business care deeply about—-a system architecture that supports efforts to get their work done efficiently; a work-centric menu to quickly access projects rather than weather readings ...

US official: Auto safety agency under review

Oct 24, 2014

Transportation officials are reviewing the "safety culture" of the U.S. agency that oversees auto recalls, a senior Obama administration official said Friday. The National Highway Traffic Safety Administration has been criticized ...

Out-of-patience investors sell off Amazon

Oct 24, 2014

Amazon has long acted like an ideal customer on its own website: a freewheeling big spender with no worries about balancing a checkbook. Investors confident in founder and CEO Jeff Bezos' invest-and-expand ...

Ebola.com domain sold for big payout

Oct 24, 2014

The owners of the website Ebola.com have scored a big payday with the outbreak of the epidemic, selling the domain for more than $200,000 in cash and stock.

Hacker gets prison for cyberattack stealing $9.4M

Oct 24, 2014

An Estonian man who pleaded guilty to orchestrating a 2008 cyberattack on a credit card processing company that enabled hackers to steal $9.4 million has been sentenced to 11 years in prison by a federal judge in Atlanta.

Magic Leap moves beyond older lines of VR

Oct 24, 2014

Two messages from Magic Leap: Most of us know that a world with dragons and unicorns, elves and fairies is just a better world. The other message: Technology can be mindboggingly awesome. When the two ...

User comments : 0