I believe that there is a critical need for improved carrier profiling as we progress from 10 nm to 7 nm lithography and beyond. Scanning Spreading Resistance Microscopy (SSRM) is presently the method of choice at these nodes. However, the carriers cannot reach equilibrium with a semiconductor over lengths less than the mean-free path for the carriers (10-15 nm). Thus, measurements made over shorter lengths would only reflect the resistivity outside of that region. Roadmaps for the semiconductor industry have asked for carrier and dopant profiling with a resolution finer than 10% of the node dimension. Atom Probe Tomography can provide nanometer resolution dopant profiling--to verify the fabrication. However, carrier profiling, which is required to validate the operation of a device, currently has no method that can satisfy the Roadmaps at and below the 10-nm node. SSRM line scans for composites of layers having different doping densities show the convolution with an impulse function having a width of approximately 50 nm.
Thus, at the 7-nm node, the use of SSRM is equivalent to attempting to manufacture an automobile using a piece of string having a length 7 times that of the car for all measurements.
I am funded by the National Science Foundation to make a prototype for a new method of carrier profiling during 2017, and I would be happy to discuss this method with anyone who would contact me using the SemiWiki.com button for email contact. I would also appreciate your comments and suggestions, either by email or by reply, regarding what I believe to be a crisis.
Thus, at the 7-nm node, the use of SSRM is equivalent to attempting to manufacture an automobile using a piece of string having a length 7 times that of the car for all measurements.
I am funded by the National Science Foundation to make a prototype for a new method of carrier profiling during 2017, and I would be happy to discuss this method with anyone who would contact me using the SemiWiki.com button for email contact. I would also appreciate your comments and suggestions, either by email or by reply, regarding what I believe to be a crisis.