Self-Aligned Contact Fabrication with Spacer Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The fabrication of self-aligned contact openings in memory devices is complicated due to differences in spacer thickness requirements between memory and periphery regions, leading to damage of spacers in the memory region during the removal of second set spacers, which affects electrical insulation and contact opening size.
Innovation Solution
A method where a first material layer covers the memory region to protect it during processes in the periphery region, allowing for the formation of intact spacers and subsequent contact openings between gates, ensuring superior electrical insulation and device characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the second set of spacers is formed on the first set of spacers in the periphery region to form source and drain regions, then the source and drain regions can be formed, but the material of the second set of spacers cannot be completely removed from the high aspect ratio openings between gates in the memory region, and the first set of spacers may be damaged during removal
Solution Approach 1:
The invention divides the fabrication process into separate treatment for memory region and periphery region. A first material layer is selectively formed only in the memory region to cover the first set of spacers, while the periphery region undergoes the second spacer formation process. This segmentation allows independent optimization of each region's process parameters.
Solution Approach 2:
The first material layer acts as an intermediary protective layer between the first set of spacers and the harmful removal processes. This intermediate layer prevents direct contact between the removal chemistry and the spacers, eliminating damage while still allowing subsequent contact opening formation.
2Reliability
If the first set of spacers are damaged during the removal of second set spacers material, then the electrical insulation of the gates deteriorates and the contact opening size is affected, but complete removal of second set spacers material from high aspect ratio openings is difficult
Solution Approach 1:
The first material layer is formed in advance before any removal processes occur. This preliminary protective action ensures that the spacers are shielded from damage during subsequent removal operations, maintaining their integrity for electrical insulation and contact opening definition.
Solution Approach 2:
The first material layer is selectively applied only where needed - in the memory region between gates - rather than uniformly across the entire wafer. This local application provides targeted protection to critical structures while allowing process access in other regions.
Data Source
AI summary
A method of fabricating a memory is provided. A substrate comprising a memory region and a periphery region is provided. A plurality of gates is formed on the substrate and a first spacer is formed on a sidewall of each gate, where a plurality of openings is formed between the gates in the memory region. A first material layer formed on the substrate in the memory region covers the gates in the memory region and fills the openings. A process is performed to the periphery region. The first material layer is partially removed to form a first pattern in each opening respectively. A second material layer formed on the substrate covers the memory region and the periphery region to expose the first patterns. The first patterns are removed to form a plurality of contact openings in the second material layer. The contact plugs are formed in the contact openings.