Tapered Bit Line Structure for Landing Pad Connectivity
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Solution Overview
Problem
As the semiconductor industry advances to smaller technology nodes, precise control of lithography becomes challenging, leading to issues such as disconnected landing pads due to sharp corners of bit line structures during etching operations, affecting device performance and yield.
Innovation Solution
A semiconductor structure with a bit line configuration featuring a cylindrical portion and a tapered step portion, surrounded by a polysilicon layer and spacers, is manufactured using a series of etching operations to prevent sharp corners and ensure a larger process window for landing pad formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional lithography and etching processes are used to fabricate bit line structures at advanced technology nodes, then device density and integration are improved, but manufacturing precision deteriorates due to disconnected landing pads caused by sharp corners
Solution Approach 1:
The bit line structure is designed with a tapered configuration where the width gradually decreases from the base to the top, replacing sharp corners with curved transitions. This curvature prevents the formation of disconnected landing pads during etching operations while maintaining high device density at advanced technology nodes.
Solution Approach 2:
The patent modifies the geometric parameters of the bit line structure by implementing a tapered profile with controlled width variation. This parameter change from a uniform rectangular cross-section to a tapered shape improves manufacturing precision by ensuring continuous landing pad formation throughout the etching process.
2Ease of manufacture
If sharp-cornered bit line structures are used in conventional designs, then ease of manufacture is improved through standard lithography processes, but reliability deteriorates due to electrical disconnection and damage from subsequent processing
Solution Approach 1:
The tapered bit line structure replaces sharp corners with gradual transitions, preventing electrical disconnection and damage during subsequent processing steps while remaining compatible with standard lithography and etching processes, thus maintaining ease of manufacture.
Solution Approach 2:
The tapered configuration acts as a preventive measure before subsequent processing steps, cushioning against potential electrical disconnection and structural damage by eliminating stress concentration points that would exist at sharp corners.
3Productivity
If standard etching operations are performed on bit line structures with sharp corners, then productivity is improved through conventional process flows, but manufacturing precision deteriorates due to process window limitations
Solution Approach 1:
By changing the geometric parameters to create a tapered bit line structure, the patent expands the process window for etching operations, allowing standard high-productivity processes to achieve better manufacturing precision and maintain structural integrity throughout fabrication.
Data Source
AI summary
The present disclosure provides a semiconductor structure having a bit line with a tapered configuration. The semiconductor structure includes: a substrate; a bit line structure, disposed over the substrate, wherein the bit line structure includes a cylindrical portion and a step portion above the cylindrical portion; a polysilicon layer, disposed over the substrate and around the bit line structure; and a landing pad, disposed over the polysilicon layer and the step portion.