Selective crystallization of silicon layers without seeding and capping layer

Selectively crystallized SOI layers with (100) texture have been grown by suitable beam shaping with an Ar+ laser. Beam shaping was accomplished by using frist-order oscillation modes of the Ar+ laser (or by superposition of two gaussian beams). Under suitable experimental conditions, the nucleation characteristics and the spontaneous seeding show an excellent reproducibility in geometry and crystal orientation. The dimensions of the single-crystal widths, within the melting diameter of 10 mym, reaches 5 mym and has no longitudinal limit. In this 10 mym regime no capping layer has used. Without capping layer there is a flow of material out of the focus. An improvement in planarity as good as 50 A has been observed with increasing scanning velocity in the range of 10 to 200 mm/s. The crystallized layers have been investigated by REM (Secco etched), TEM and Raman spectroscopy. A computer-controlled laser writing system has been used, in order to grow the silicon layers selectively on the chip.