3D Pattern Effects in RTA Radiative vs Conductive Heating

Abstract

The effect of 3D patterns on the heating of silicon substrates was investigated theoretically and experimentally. As energy sources RTA systems based on radiant heating (i.e. lamp-based) and on conduction heating (wafer placed in very close proximity to hot surfaces) were applied. The 3D patterns were trenches with dimensions 150-450nm wide, and 400nm deep. In case of lamp-based systems with heat-up rates of 75°C/s within-die temperature variations of 10-20°C were observed. In case of conduction-based systems with heat-up rates up to 900°C/s the impact of the 3D structures was negligible. Both types of systems were modeled, and a reasonable correlation with the experimental data was found.

(Invited) Pattern and Emissivity Insensitive Dopant Activation and Silicide Contact Formation Annealing in a Hot Wall Rapid Thermal Annealing System

“…Hot wall RTA systems are insensitive to the optical properties of materials and density of patterns since they are not relying heavily on radiation heating. [9,19,20] Metal films are highly reflective and difficult to heat using photon radiation. When metal reacts with Si at the metal/Si interface, the metal film loses reflectance significantly and increases light absorbance significantly.…”

“…[6,7] RTA-induced variations strongly depend on circuit layout patterns and optical properties of exposed materials on the surface of the Si wafers. [5,8,9] This phenomenon is often referred to as the "pattern effect" and "emissivity effect", known from the early days of RTA introduction in the semiconductor industry. [5][6][7][8][9][10] In efforts to reduce the "pattern effect" and "emissivity effect", various approaches have been proposed and implemented in device manufacturing.…”

“…[5,8,9] This phenomenon is often referred to as the "pattern effect" and "emissivity effect", known from the early days of RTA introduction in the semiconductor industry. [5][6][7][8][9][10] In efforts to reduce the "pattern effect" and "emissivity effect", various approaches have been proposed and implemented in device manufacturing. Shielding device patterns from the radiant heat source is a common approach for "pattern effect" reduction, but has showed limited success.…”

A Short History of Pattern Effects in Thermal Processing

“…It has been proposed that one path to elimination of pattern effects is to ensure that the dominant heating mechanism is thermal conduction. The approach is based on placing the wafer between a pair of massive hot blocks, and making sure that it is only ~150 µm from those surfaces [75]. These very small gaps enable the conductive heat fluxes to dominate the heating process, greatly reducing the role of radiative heat exchange in comparison to the conductive heat flow.…”