Method of manufacturing semiconductor device

A method of manufacturing a semiconductor device, the method comprising:

• forming a mask layer on a pattern target layer;
• exposing and developing the mask layer by using a multi-tone reticle including a white region and first to third gray regions to form a first mask pattern region having a first thickness that exposes the pattern target layer and second to fourth preliminary mask pattern regions respectively having second to fourth sub-thicknesses that are sequentially less than the first thickness, without exposing the pattern target layer;
• etching the pattern target layer located below the first mask pattern region while etching the mask layer and the pattern target layer located below the second to fourth preliminary mask pattern regions to form first to fourth patterns respectively having first depth to fourth depth that are sequentially smaller;
• and
• removing the mask layer.

A method of manufacturing a semiconductor device, the method comprising:

• forming high-density mask patterns and low-density mask patterns separate from each other on a semiconductor substrate, wherein the semiconductor substrate is a pattern target layer, the high-density mask patterns are apart from each other, and the low-density mask patterns are apart from each other;
• forming a mask layer on the high-density mask patterns and the low-density mask patterns;
• exposing and developing the mask layer by using a multi-tone reticle including a white region and a gray region to form a first mask exposure pattern region exposing the semiconductor substrate and the low-density mask patterns and a second mask pattern region not exposing the semiconductor substrate or the high-density mask patterns;
• etching the semiconductor substrate located below the first mask exposure pattern region to form first preliminary patterns and further etching the second mask pattern region to form a second mask exposure pattern region exposing the high-density mask patterns and the semiconductor substrate;
• and
• further etching the semiconductor substrate located below the first mask exposure pattern region and the first preliminary patterns to form first patterns having a first depth and etching the semiconductor substrate located below the high-density mask patterns of the second mask exposure pattern region to form second patterns having a second depth that is less than the first depth,
• wherein the first patterns are first trench patterns, the second patterns are second trench patterns, low-density active patterns are formed between the first trench patterns, and high-density active patterns are formed between the second trench patterns.