SEMATECH News

Improved Metrology Critical to Advanced Technology Development; Industry Coordination Vital

Austin, TX (1 June, 2004) – As the semiconductor industry drives toward new horizons in post-CMOS and nanoelectronics, it’s essential to keep metrology updated, coordinated, and close to the driver’s seat, an International SEMATECH technologist says.

Dr. Alain C. Diebold, a SEMATECH fellow and recognized industry authority, adds that while metrology has long been the industry’s dependable workhorse on the manufacturing line, current R&D systems are reaching their metrical limits and must be replaced soon by more advanced approaches.

In addition, materials characterization methods such as transmission electron microscopy must advance to meet the needs of nanoelectronics development, he said, adding that metrology must stay well ahead of, rather than lag, technology advancement.

“The next few years are critical for the development of metrology tools,” Diebold noted in a recent interview. “Metrology and characterization are as essential to R&D as they are to manufacturing. Whether you are shrinking semiconductor devices to nano dimensions, or focusing on biotech or MEMS, or arranging molecules directly, you need microscopy tools that currently don’t exist, or that are still in developmental phases.”

An example, said Diebold, is high-resolution transmission electron microscopy (HR TEM), a long-reliable characterization method which nevertheless is greatly challenged by the need for measuring interfaces and other properties at atomic dimensions. A relatively new scanning TEM (STEM) method known as “annular dark field” has greatly improved microscopy’s ability to analyze small areas, he said. But even with this advance, the aberration present in TEM lenses makes it impossible to accurately perceive nanoscopic objects.

“We need to move toward aberration-corrected TEM images that compensate for problems caused by the lens itself,” Diebold said. “Eventually, we need to advance it with three-dimensional (3-D) TEM imaging. We need a smaller beam diameter to allow more localized analysis and a better picture of the atomic structure.”

Another area of concern for metrologists is the introduction of new advanced semiconductor materials, such as strained silicon and/or germanium, in place of traditional silicon found in transistor channels. “Measurement methods must be developed for these innovations,” said Diebold. “This is critical for the industry; measuring stress and determining film thickness for gate dielectrics on top of these materials are critical needs.”

New structures such as “fin-shaped” field-effect transistors (FINFETs) and 3D interconnect may require redesigning equipment so that film properties can be measured on sidewalls. Doping control in FINFETs is also a challenge, the metrologist said.

To address these and other metrology issues, Diebold is calling for more and better organized industry coordination to develop microscopy for nanotech and other advanced technologies. This is especially important given recent federal funding support to national labs for advanced metrology, he contends.

“The U.S. government has done its part by increasing the necessary funding for nanotechnology, including advanced metrology,” Diebold said. “Now it’s time for the industry to come together and prove that the money will be well spent.’

A logical venue for such industry coordination is the newly established Advanced Materials Research Center (AMRC) in Austin, an R&D effort which is being jointly administered by SEMATECH and the University of Texas System, Diebold continued.

“We are already working with Chemical Engineering Professor Brian Korgel in the AMRC to develop TEM for microscopy of nano-structures,” Diebold explained. “Using his nano-materials, we can test both existing TEMs and the new aberration-corrected TEMs at the dimensions found in the nanoelectronics that will be manufactured 10 years from now.”

“The nano-wires and dots also provide a means of testing critical dimension metrology at the end of the roadmap. We will also be working with several other professors in the AMRC to develop metrology.” He provided the following examples of work by UT professors:

  • Physics Professor Michael Downer’s work on nonlinear optical spectroscopy to improve optical metrology of future ultra-thin films and interfaces;
  • Physics Professor Ken Shih’s work to measure FINFET doping;
  • Chemistry Professor Alan Campion’s development of stress measurement that is essential for future transistor development and fabrication;
  • Chemical Engineering Professor Miguel Yacaman’s work on TEM characterization of nanoelectronics;
  • Physics Professor Alex De Lozanne’s work on scanning tunneling microscopy measurements for future transistor and interconnect technology.

“At these sizes, the electrical properties of materials are different from the bulk properties, and fundamental understanding is a must if we are going to measure and control the critical dimensions and properties of nanoelectronics and other emerging technology devices in both R&D and manufacturing,” Diebold said.

“The development and continuous improvement of metrology tools is essential to future technology infrastructure,” he concluded. “But what we do now, or fail to do, will affect our progress for years to come.