Researchers at the National Institute of Standards and Technology (NIST) have developed a method to measure the toughnessthe resistance to fractureof the thin insulating films that play a critical role in high-performance integrated circuits. The new technique could help improve the reliability and manufacturability of ICs and, better yet, its one that state-of-the-art microelectronics manufacturers can use with equipment they already own.
At issue is the mechanical strength of so-called low-k dielectric layerselectrically insulating films only a couple of micrometers thick that are interleaved between layers of conductors and components in microprocessor chips and other high-performance semiconductor devices. As IC features like transistors have gotten ever smaller and crammed more closely together, designers are preventing electrical interference or cross-talk by making the insulating films more and more porous with nanoscale voidsbut this has made them more fragile. Brittle fracture failure of low-k insulating films remains a problem for the industry, affecting both manufacturing yields and device reliability. To date, there has been no accurate method to measure the fracture resistance of such films, which makes it difficult to design improved dielectrics.
NIST researchers believe they have found an answer to the measurement problem in a new adaptation of a materials test technique called nanoindentation. Nanoindentation works by pressing a sharp, hard objecta diamond tipand observing how much pressure it takes to deform the material. For roughly 20 years, researchers have known how to measure elasticity and plasticitythe forces needed to bend a material either temporarily or permanentlyof materials at very small scales with nanoindenters. But toughness, the force needed to actually break the material, has been, well, tougher. Thin films were particularly problematic because they necessarily must be layered on top of another stronger mater
|Contact: Michael Baum|
National Institute of Standards and Technology (NIST)