A new fabrication process of silicon template for nanoimprint lithography is developed. A very fine and high aspect Si lines are fabricated by the combination of plasma process for Si deep etching and anisotropic wet etching by potassium hydroxide solution (KOH treatment). Improved switching process, which consists of sequentially alternating etching and deposition steps, is used as the Si deep etching. The side wall profile of the Si lines can be controlled by the deposition step time. Line pattern with vertical side wall is fabricated. The line width and height are 0.2 mu m and 2.9 mu m, respectively. By the KOH treatment the side wall corrugation can be reduced and the line width also decreases. Very fine line of 45 nm width at the line top with the pattern height of 3.0 mu m can be fabricated by use of the line width shrink by the KOH treatment. (C) 2009 Elsevier B.V. All rights reserved.