An electronic image shows six transistors installed in a space measuring 300 nanometres by 130 nanometres on a microchip developed by State-backed National Nano Device Laboratories
Nano injection lithography eliminates the masks of other lithography techniques. Eliminating the masks and the photoresist cuts the patterning process from five steps to one, greatly simplifying production. The researchers say that EUV masks are projected to cost around US $3 million a set and the EUV lithography machines about $60 million apiece. So the nano injection lithography could also be significantly cheaper. Hu says the technique also allows for finer lines and closer spacing than typical electron-beam lithography.
Yang Fu-liang, the lab’s chief and his team are working on 16-nanometer technology, referring to the space between transistors on a chip.
said the 16-nm SRAM device offers a nine-fold increase in capacity over 45-nm SRAM technology and a 60-percent reduction in microchip size, while at the same time lowering power consumption by about half. With a capacity 10 times that of current 45-nm SRAM devices, the new technology will lead to even smaller and lighter portable electronics products after mass production begins by allowing for major reductions in motherboard size. In the future, the technology could lead to computers as light as 500 grams in weight.
A new type of lithography, which uses an electron beam to spark a chemical reaction, could provide a cheaper way to build the incredibly tiny transistors that the chipmaking industry will require in a few years. Researchers from Taiwan and the University of California, Berkeley, say they’ve made static random access memory (SRAM) that anticipates 16-nanometer chip features with a new process called nano injection lithography.
They say their technique may provide an alternative to lithography that relies on extreme ultraviolet light (EUV), which still is beset by problems and could be extremely expensive.
The device the team made was a six-transistor SRAM in a 0.039µm2 cell. The previous record holder was based on 22-nm features in a 0.1 µm2 cell.
SRAM occupies an ever-increasing percentage of a chip, taking up as much as 80 percent of cell area in some designs, Hu notes. “The size of the SRAM cell becomes critical to the cost of the chip, so SRAM is always the most taxing circuit for testing process capability,” he says. Shrinking the SRAM, in other words, is key to shrinking the chip’s circuitry as a whole.
Standard lithography uses a set of masks to create a pattern of structures in a photoresist that’s exposed to ultraviolet light. The Taiwan team’s process eliminates both the masks and the photoresist, relying instead on a metallorganic gas, an organic molecule studded with atoms of platinum. An electron beam with a diameter of 4.6 nm is fired at the gas, causing a chemical reaction that deposits the platinum on the silicon chip in the desired pattern, while the rest of the gas flows away. With this hard mask deposited on the silicon, the researchers then use chemicals to etch away exposed silicon and thereby create the desired circuits. The platinum mask is then chemically removed.
The researchers say their technique is mainly an alternative for EUV and e-beam lithography for low-volume fabrication.
“It seems this new nano-injection-lithography technique may indeed be of interest for exploring 16-nm node device dimensions,” says Anabela Veloso, who specializes in CMOS devices and technology at IMEC, an independent research center for nano-electronics in Belgium. “However, as an electron-beam based technique, and without further information on potential throughput and [alignment of different patterns], the feasibility of its application for volume production seems very unlikely.”
Skepticism aside, the researchers will explore other ways to improve the technique, such as using other gases. They used a gas that was readily available and worked, but may not be the best for their purposes.
When the 16-nm chip is coming is not certain, although Hu says some optimists expect it by 2013.