Sloped Device Isolation Sidewalls for Semiconductor Memory Reliability
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Solution Overview
Problem
The fabrication of densely integrated semiconductor memory devices is challenging due to the need for new and expensive exposure techniques to achieve fine patterns, leading to increased process defects and reduced reliability.
Innovation Solution
The semiconductor memory device design includes a substrate with impurity regions, device isolation patterns, bit-line and storage node contacts, and dielectric patterns, where the device isolation pattern's sidewalls have specific slope configurations and the dielectric pattern has constant and variable widths, along with a method of fabricating these structures to reduce process defects and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If new and expensive exposure techniques are used to achieve fine patterns, then manufacturing precision is improved, but device complexity and fabrication cost increase
Solution Approach 1:
The patent changes the geometric parameters of the device isolation pattern sidewalls by introducing specific slope configurations (first slope for upper part, second slope for lower part). This parameter modification enables improved manufacturing precision in forming fine patterns while avoiding the need for complex expensive exposure techniques, thus resolving the contradiction between pattern fineness and fabrication process complexity
Solution Approach 2:
The patent applies local quality by creating different slope characteristics at different portions of the device isolation pattern sidewalls. The upper part has a first slope and the lower part has a second slope, allowing each region to serve its specific function in the fabrication process. This localized differentiation improves overall manufacturing precision without requiring complex global process changes
2Productivity
If line widths are reduced for higher integration, then productivity is improved, but manufacturing precision becomes more difficult to achieve
Solution Approach 1:
The patent modifies the geometric parameters of the device isolation pattern by introducing specific slope configurations. This parameter change creates a self-aligned effect that improves manufacturing precision when forming narrow line widths, enabling higher integration density without sacrificing precision. The sloped sidewalls provide better definition during etching processes, allowing tighter spacing between features
3Ease of manufacture
If conventional device isolation patterns are used, then ease of manufacture is maintained, but reliability decreases due to process defects
Solution Approach 1:
The patent changes the sidewall geometry parameters of the device isolation pattern by introducing specific slope configurations (first slope and second slope at different portions). This parameter modification improves device reliability by reducing process defects such as bridging and short circuits, while maintaining ease of manufacture through standard fabrication processes. The sloped structure provides better process margins without requiring complex manufacturing steps
Data Source
AI summary
A semiconductor memory device includes; a first impurity region and a second impurity region spaced apart in a substrate, a device isolation pattern between the first impurity region and the second impurity region, a bit-line contact on the first impurity region, a storage node contact on the second impurity region and a dielectric pattern between the bit-line contact and the storage node contact. An upper part of a sidewall of the device isolation pattern has a first slope and a lower part of the sidewall of the device isolation pattern has a second slope different from the first slope.