Friday, March 20, 2015

Issues and options for using selective ALD at 5nm

Here is a very good blog by Mark Lapedus on scaling down some additional nodes. Mark Lapedus is Executive Editor for manufacturing at Semiconductor Engineering.

One of the more interesting option for all us ALD freaks besides the NGLs, there is another emerging option—selective deposition. Below I have cut out that part and please do forward any good open avaialble information on this topic to me ( or simply post a comment here!

Still in the R&D stage, selective deposition could be used to selectively deposit materials, namely metals on metals and dielectrics on dielectrics, on a device. “There are a lot of people thinking about
this today,” said Girish Dixit, vice president of process applications for Lam Research . “There are many areas that selective deposition could be used in, including doing edges or removing something at the expense of something.

Selective deposition involves the use of special chemistries and existing atomic layer deposition (ALD) tools. It also makes use of molecular layer deposition (MLD), which is similar to ALD. “With MLD,you are typically making something that is primarily an organic,composed of carbon, nitrogen, oxygen and hydrogen. In classic ALD, you are making inorganic materials. There are also hybrids,” said James Engstrom, a professor in the School of Chemical and Biomolecular Engineering at Cornell University. There are some differences between traditional ALD and selective deposition using ALD. “The difference is you somehow trick the ALD process, so that it grows on material A, but does not grow on material B,” Engstrom said.

Selective deposition doesn’t replace lithography, but it does solve a problem—edge placement error. “When you want one thing to line up with another, the ability to control the placement of a feature is getting to be outside the range, because the features are small,” said Gregory Parsons, a professor in the College of Engineering at North Carolina State University.

In a theoretical flow, a lithography tool would first pattern a surface. “So, if there is a pattern available on the surface that you want to selectively deposit, then your material that you are forming would then align to the pattern that is underneath the substrate,” Parsons said. “Instead of a physical mask to align, you would want to use the chemistry of the surface to do the alignment. And if the process can recognize that selective chemical difference, then we can deposit materials exactly where we want.”

Still, the technology is unproven and there are challenges. But if the technology works, it could possibly change the landscape in IC manufacturing. “Once the ball is rolling, and you can do selective deposition on anything, then the applications will expand,” Lam’s Dixit added.

Full Story here:

Good papers on the topic:

The use of atomic layer deposition in advanced nanopatterning by Kessels et al

Atomic layer deposition (ALD) is a method that allows for the deposition of thin films with atomic level control of the thickness and an excellent conformality on 3-dimensional surfaces. In recent years, ALD has been implemented in many applications in microelectronics, for which often a patterned film instead of full area coverage is required. This article reviews several approaches for the patterning of ALD-grown films. In addition to conventional methods relying on etching, there has been much interest in nanopatterning by area-selective ALD. Area-selective approaches can eliminate compatibility issues associated with the use of etchants, lift-off chemicals, or resist films. Moreover, the use of ALD as an enabling technology in advanced nanopatterning methods such as spacer defined double patterning or block copolymer lithography is discussed, as well as the application of selective ALD in self-aligned fabrication schemes.

Graphical abstract: The use of atomic layer deposition in advanced nanopatterning