- Email: [email protected]
Next generation insulator
RESEARCH NEWS
LADI keeps Moore going Stephen Chou and co-workers at Princeton University have developed a new technique that allows patterns to be imprinted into silicon at record speeds [Nature (2002) 417, 835-837]. Laser-Assisted Direct Imprint – or LADI – could replace lithography and etching for
6
micro- and nano-fabrication of silicon, which are costly, timeconsuming, and resolution limited, say the researchers. The technique uses a quartz template to pattern silicon, or other materials such as polysilicon. The template is pressed against the silicon and a single excimer laser pulse
Scanning electron micrograph of a cross-section of a LADI-patterned silicon sample. (Courtesy of Stephen Chou, Princeton University, and Nature.)
Schematic of the LADI process for nano-patterning of silicon. (Courtesy of Stephen Chou, Princeton University, and Nature.)
melts the material in its vicinity. The melted silicon conforms to the shape of the mold and resolidifies (see schematic diagram). The quartz template is removed and can be reused. "You just imprint the pattern directly into the silicon," explains Chou. "You not only reduce the number of steps, you can do it in nanoseconds." The resulting silicon structures, as shown, reveal resolution better than 10 nm and can be applied to large areas. Questions still remain on whether the template could
How low can deposition go?
Next generation insulator
A new low temperature, nonvacuum technique for depositing crystalline oxide films could reduce costs in many electronic and optical applications [Science (2002) 297, 65]. Developed by researchers at Oregon State University (OSU) in collaboration with HewlettPackard and ReyTech Corp., the technique uses a simple water-based chemistry to deposit crystalline films of Zn2SiO4, ZrO2, and MnO2. It combines a precipitation and hydrothermal dehydration
Lanthanum aluminate (LAO) is being hailed as a potential replacement for silicon dioxide in the next generation of MOSFET (metal oxide semiconductor field effect transistor) devices. Motorola, Nanjing University, and the Chinese Institute of Physics (CAS) have just completed characterization of LAO and the related material lanthanum aluminum oxynitride (LAON) to determine their potential as a gate dielectric. With a dielectric constant of more than 20, LAO has one of the
September 2002
process with successive-ioniclayer-absorption-and-reaction (SILAR). "We found that you can take certain materials that contain water and let them dehydrate slowly and at low temperatures, and still observe crystallinity," says Douglas Keszler of OSU. "Processing is done in a bath, rather than requiring expensive technology, vacuums, and very high temperatures. There has never been a way before to both deposit and crystallize electronic or photonic films at such low temperatures."
cause and propagate defects – and if its features can be made small enough. Nevertheless, in an accompanying News and Views article [Nature (2002) 417, 802-803], R. Fabian Pease says that the new imprinting technology could keep Moore's law on track for another two decades. One implication of Moore's Law is that as the number of transistors crammed onto a chip increases, so does the cost of manufacture. But a technique like Chou's LADI could provide vital financial savings.
best thermal stabilities of current candidates. According to Motorola, it should also be possible to integrate with existing CMOS processes. "Traditional materials will last one or two more generations," explains Karen Guo, the director of Motorola China R&D Institute and DigitalDNA Laboratories China. "We are very excited about the potential of this material. While more research is required, LAO is the most promising material we have seen." Further details: www.motorola.com
LADI keeps Moore going Stephen Chou and co-workers at Princeton University have developed a new technique that allows patterns to be imprinted into silicon at record speeds [Nature (2002) 417, 835-837]. Laser-Assisted Direct Imprint – or LADI – could replace lithography and etching for
6
micro- and nano-fabrication of silicon, which are costly, timeconsuming, and resolution limited, say the researchers. The technique uses a quartz template to pattern silicon, or other materials such as polysilicon. The template is pressed against the silicon and a single excimer laser pulse
Scanning electron micrograph of a cross-section of a LADI-patterned silicon sample. (Courtesy of Stephen Chou, Princeton University, and Nature.)
Schematic of the LADI process for nano-patterning of silicon. (Courtesy of Stephen Chou, Princeton University, and Nature.)
melts the material in its vicinity. The melted silicon conforms to the shape of the mold and resolidifies (see schematic diagram). The quartz template is removed and can be reused. "You just imprint the pattern directly into the silicon," explains Chou. "You not only reduce the number of steps, you can do it in nanoseconds." The resulting silicon structures, as shown, reveal resolution better than 10 nm and can be applied to large areas. Questions still remain on whether the template could
How low can deposition go?
Next generation insulator
A new low temperature, nonvacuum technique for depositing crystalline oxide films could reduce costs in many electronic and optical applications [Science (2002) 297, 65]. Developed by researchers at Oregon State University (OSU) in collaboration with HewlettPackard and ReyTech Corp., the technique uses a simple water-based chemistry to deposit crystalline films of Zn2SiO4, ZrO2, and MnO2. It combines a precipitation and hydrothermal dehydration
Lanthanum aluminate (LAO) is being hailed as a potential replacement for silicon dioxide in the next generation of MOSFET (metal oxide semiconductor field effect transistor) devices. Motorola, Nanjing University, and the Chinese Institute of Physics (CAS) have just completed characterization of LAO and the related material lanthanum aluminum oxynitride (LAON) to determine their potential as a gate dielectric. With a dielectric constant of more than 20, LAO has one of the
September 2002
process with successive-ioniclayer-absorption-and-reaction (SILAR). "We found that you can take certain materials that contain water and let them dehydrate slowly and at low temperatures, and still observe crystallinity," says Douglas Keszler of OSU. "Processing is done in a bath, rather than requiring expensive technology, vacuums, and very high temperatures. There has never been a way before to both deposit and crystallize electronic or photonic films at such low temperatures."
cause and propagate defects – and if its features can be made small enough. Nevertheless, in an accompanying News and Views article [Nature (2002) 417, 802-803], R. Fabian Pease says that the new imprinting technology could keep Moore's law on track for another two decades. One implication of Moore's Law is that as the number of transistors crammed onto a chip increases, so does the cost of manufacture. But a technique like Chou's LADI could provide vital financial savings.
best thermal stabilities of current candidates. According to Motorola, it should also be possible to integrate with existing CMOS processes. "Traditional materials will last one or two more generations," explains Karen Guo, the director of Motorola China R&D Institute and DigitalDNA Laboratories China. "We are very excited about the potential of this material. While more research is required, LAO is the most promising material we have seen." Further details: www.motorola.com