Controlled Super-Lateral Growth of Si Films for Microstructural Manipulation and Optimization

Abstract

This paper reviews a particular form of pulsed‐laser‐based thin‐film crystallization method referred to as controlled super‐lateral growth (C‐SLG). By systematically manipulating and controlling the locations, shapes, and extent of melting induced by the incident laser pulses, the C‐SLG approach — notably in a version referred to as sequential lateral solidification (SLS) — can lead to realization of a variety of microstructurally designed crystalline Si films with low structural defect densities, including 1. large‐grained and grain‐boundary‐location controlled polycrystalline films, 2. directionally solidified microstructures, or 3. location‐controlled single‐crystal regions.

Mixed-phase solidification of thin Si films on SiO2

“…Such singular material characteristics qualify these films, among other applications: (1) as the best precursor material for generating location-and surface-orientation-controlled intragrain-defect-free (SOI-quality) single-crystal regions via the hybrid sequential lateral solidification (SLS) method [8] for high performance large-area electronics and 3-dimensional integrated circuits [9] and (2) as a good seed layer, with or without SLS [10,11], for subsequently epitaxially fabricating high-performance devices (e.g., Si film-based solar cells on low-cost and large-area substrates [12]). …”

N-shot SLS-processed polycrystalline silicon TFTs

“…By employing more 2-shot scans, the number of grain boundaries within the cells can be filtered out, as seen in the 2 4 -shot and 2 6 -shot processed films in Figure 1, and shown in the grain boundary maps of Figure 2. 4 , and 2 6 -shot processes. The directionality ratios for the mobility of devices that have their current flow in the final LG direction versus those with current flow perpendicular to the final LG direction are found to increase with increasing number of 2-shot scans.…”

“…4-6 The 2-shot implementation of this method is especially well suited for formation of polycrystalline Si films as it has a wide laser fluence processing window, 7 can have a high throughput, and can be carried out with no substrate heating or controlled atmosphere. 4,8,9 In this paper, results from an investigation to improve the uniformity of devices that have their majority carrier flow either parallel or perpendicular to the lateral growth direction are presented. With the 2-shot SLS process, a multitude of long narrowly-spaced grains are formed.…”

Microstructural Design of Advanced Architectures in Titanium/Platinum Thin Films by Laser Interference Metallurgy

“…This phenomenon is known as Super Lateral Growth. [16][17][18] Above a given laser fluence, laterally growing grains appear in this regime, originating from the unmelted areas (interference minima) and propagating to the completely molten regions (interference maxima). In Figure 1(a) and 1(b), a centre-line at the interference maxima can be observed, which results from the lateral growth of the grains from both sides of the molten pool at the interference maxima following the temperature gradient.…”