Review of computational lithography modeling: focusing on extending optical lithography and design-technology co-optimization

Abstract

Advances in computational lithography over the last 10 years have been instrumental to the continued scaling of semiconductor devices. Competitive scaling requires two types of complementary models: fast predictive empirical models that can be used for pattern correction and verification; rigorous physical models that can be used to identify key physical effects that must be considered to ensure pattern fidelity, but are too resource intensive to use for full chip applications. Today, all computational lithography efforts such as the optical proximity correction (OPC) and the optical rules check (ORC) depend on the ability to predictively model the lithography and metrology processes. We discuss some of the current modeling practices in optics, mask, resist and etching, leading to the " Holy Grail " of predictively modeling entire patterning process which we call " virtual fab " . Extreme ultraviolet (EUV) modeling is discussed due to its potential to extend optical lithography scaling for future nodes. Modeling of novel technologies such as Diblock Copolymer patterning is also discussed to demonstrate new opportunities for continued scaling. Complexity of the " virtual fab " approach is extremely high as there are multiple dimensions in this approach. The need to overcome this complexity, by reducing the number of dimensions of the problem, is evident. Lastly, the ability to leverage lithography modeling in design co-optimization is an important element of semiconductor device scaling.

Evolution of patterning materials towards the Moore’s Law 2.0 Era

“…A further refinement to OPC is source-machine optimization (SMO). 32) In SMO, the features on the mask deviate significantly from the intended design, while the light source illuminator is programmed with selective obscuration regions, making it uniquely paired with the new mask shapes. This way, it is possible to more faithfully print on the wafer the layout that the circuit designer created.…”

Advanced finite-element methods for design and analysis of nanooptical structures: applications

“…The field of numerical simulations in this engineering-and research-area is termed Computational lithography. 87 Numerically optimized resolution enhancement techniques (RET), optical proximity correction (OPC), and source mask optimization (SMO) help to push the resolution limits of nanofabrication further towards smaller structures. The technological framework of this field translates to challenging requirements on numerical accuracy and computation time.…”

Method for fast computation of angular light scattering spectra from 2D periodic arrays

“…Similar requirements for computations of solutions to Maxwell's equations as in the above described field of computational metrology are present, e.g., in the field of computational lithography. 4 A need therefore exists for a method to speed-up computation of such light distributions incident from a number of different directions on periodic samples. In this contribution we present results from an implementation of a Schur complement based method 5 allowing for such speed-ups.…”