<p>The precursor is dot patterns separated by a wall of thickness a<sub>0</sub> and b<sub>0</sub>. SLIM processing narrows both walls at the same rate to a thickness of a<sub>1</sub> and b<sub>1</sub>. At a critical thickness the etch rate reduces significantly resulting in little change towards a<sub>2</sub>, but b<sub>2</sub> continues to narrow. As b<sub>2</sub> approaches the critical thickness, the pattern converges to a square.</p
