Bit Line Contact Trench Layout for Electrical Isolation
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Solution Overview
Problem
Bit line contacts in semiconductor devices with half-profile trenches experience electrical leakage due to lack of isolation spacers, leading to shorts between bit lines and capacitor contacts.
Innovation Solution
A method involving the formation of a substrate with active areas and mask structures, followed by the application of a protective layer with a zigzag edge to define regions for etching, resulting in trenches with integral profiles that allow for the formation of isolation spacers on both sides of bit line contacts, preventing electrical shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a half-profile trench is used at the edge of a cell region, then the trench can be formed to accommodate bit line contacts, but electrical leakage occurs between the bit line and cell contact due to lack of isolation spacers
Solution Approach 1:
The patent applies asymmetry by forming different trench profiles at different locations: full-profile trenches in the central region and half-profile trenches at the edge regions. This asymmetric approach allows the edge trenches to accommodate bit line contacts while the full-profile central trenches provide proper isolation spacers to prevent electrical leakage, thus resolving the contradiction between ease of manufacture and electrical isolation reliability
Solution Approach 2:
The patent implements local quality by providing different trench structures in different regions of the substrate. The central region receives full-profile trenches with complete isolation spacers for electrical isolation, while edge regions receive half-profile trenches optimized for bit line contact formation. This localized differentiation allows each region to have the structure best suited for its specific function, resolving the contradiction between manufacturing ease and electrical isolation
2Reliability
If full-profile trenches are formed in all regions, then electrical isolation is improved with isolation spacers, but the device complexity and manufacturing process become more complex
Solution Approach 1:
The patent resolves this contradiction by applying local quality - providing full-profile trenches with isolation spacers only where needed (central regions requiring electrical isolation) while using half-profile trenches at edge regions where bit line contacts are formed. This selective approach maintains electrical isolation reliability where required while simplifying the overall device structure and manufacturing process
3Ease of manufacture
If half-profile trenches are used at edge regions, then the trench can be formed to accommodate bit line contacts, but manufacturing precision is compromised due to varying trench profiles
Solution Approach 1:
The patent addresses this contradiction by deliberately designing an asymmetric trench structure where half-profile trenches at edge regions and full-profile trenches in central regions are intentionally different. This controlled asymmetry, guided by the zigzag protective layer pattern, ensures that each trench type is manufactured with precision according to its specific requirements, resolving the contradiction between ease of manufacture and manufacturing precision
Data Source
AI summary
A semiconductor device and method for manufacturing the same are provided. The method includes providing a substrate including a plurality of active areas separated from each other. In some embodiments, the method also includes forming first mask structures on the substrate. In some embodiments, the method further includes forming a first protective layer covering the first mask structures and the substrate. In some embodiments, the first protective layer defines an area exposing a portion of the first mask structures and the substrate, and the area defined by the first protective layer has a zigzag edge in a top view. In addition, the method includes performing a first etching process to remove a portion of the substrate exposed from the first mask structures and the first protective layer to form trenches.