DRAM Active Pattern Formation Using Multi-Stage Masking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The contact hole-type trimming process used in DRAM device manufacturing results in non-uniform spacing between active patterns, affecting the uniformity and quality of the active pattern array.
Innovation Solution
A method involving the formation of first and second patterns on a substrate, with specific mask configurations and etching processes to create active patterns in both the cell and peripheral circuit regions, ensuring uniform spacing and rectangular shapes with protrusions, using multiple mask layers and spacer layers to achieve precise pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a contact hole-type trimming process is used to cut preliminary active patterns, then the active patterns can be formed, but the space between the active patterns becomes non-uniform
Solution Approach 1:
The patterning process is divided into multiple stages: first forming preliminary active patterns, then using multiple mask layers (first mask, second mask, third mask) to progressively refine and separate the patterns. This segmentation allows precise control over spacing by treating different regions (cell region vs. peripheral circuit region) independently with region-specific masks.
Solution Approach 2:
The patent introduces multiple mask layers stacked in the vertical dimension to control horizontal spacing. By using first masks, second masks, and third masks at different vertical levels, the process achieves precise two-dimensional pattern control that cannot be obtained with single-layer masking, resolving the spacing uniformity issue.
2Manufacturing precision
If multiple mask layers and spacer layers are used to achieve precise pattern formation, then uniform spacing and rectangular shapes with protrusions are obtained, but the manufacturing process complexity increases
Solution Approach 1:
Spacer layers are formed in advance before the final active pattern definition. The spacers are deposited and patterned beforehand to serve as pre-positioned structures that guide subsequent mask formation and etching processes, ensuring precise spacing is achieved before the actual pattern cutting occurs.
Solution Approach 2:
The patent introduces intermediate spacer layers and intermediate mask patterns that mediate between the preliminary active patterns and the final active patterns. These intermediaries facilitate the transformation process, allowing complex shape modifications (including protrusion formation) to be achieved through manageable sequential steps rather than a single complex operation.
Data Source
AI summary
In a method of forming active patterns, first patterns are formed in a first direction on a cell region of a substrate, and a second pattern is formed on a peripheral circuit region of the substrate. The first pattern extends in a third direction crossing the first direction. First masks are formed in the first direction on the first patterns, and a second mask is formed on the second pattern. The first mask extends in a fourth direction crossing the third direction. Third masks are formed between the first masks extending in the fourth direction. The first and second patterns are etched using the first to third masks to form third and fourth patterns. Upper portions of the substrate are etched using the third and fourth patterns to form first and second active patterns in the cell and peripheral circuit regions.