Bit Line Conductive Structure Ashing Without Oxidation
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Solution Overview
Problem
Dry etching in semiconductor manufacturing leads to electric migration failure in bit lines due to oxidation during conventional ashing processes, which affects the integrity and resistance of the bit lines.
Innovation Solution
Employ an oxygen-free gas, such as a hydrogen-containing and nitrogen-containing gas or a combination thereof, for the ashing process to remove residues without oxidizing the conductive structures, ensuring alignment and direct contact between conductive structures, and use a nitride spacer layer to protect and enhance electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching is used to form bit lines with high aspect ratio, then the bit line structure can be achieved, but electric migration failure and oxidation occur leading to increased interface resistance
Solution Approach 1:
The patent applies inert atmosphere by replacing oxygen-containing plasma with nitrogen-containing plasma in the etching process. This creates an oxygen-free environment that prevents oxidation of the bit line structures during manufacturing, thereby eliminating the root cause of electric migration failure while maintaining the ability to form high aspect ratio bit lines with precise dimensional control
2Ease of manufacture
If conventional ashing process with oxygen plasma is used to remove residues, then residues are removed, but oxidation of conductive structures occurs increasing interface resistance
Solution Approach 1:
The patent replaces oxygen plasma with nitrogen plasma for the ashing process. Nitrogen plasma effectively removes organic residues from the bit line structures while creating an oxygen-free environment that prevents oxidation of the conductive materials. This maintains manufacturing ease for residue removal while preserving the electrical properties and reducing interface resistance
Solution Approach 2:
The patent changes the chemical composition parameter of the plasma from oxygen-based to nitrogen-based. This parameter change fundamentally alters the chemistry of the ashing process, allowing effective residue removal through nitrogen-containing radical reactions while eliminating the harmful oxidation that would increase interface resistance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution maintains the integrity of conductive structures, reduces interface resistance, and enhances the overall resistance of the semiconductor device by preventing oxidation, thereby improving the manufacturing process.
Implementation Method 1
performing an ashing process to remove the residue, in which a gas for generating a plasma used in the ashing process is an oxygen-free gas
Implementation Method 2
a reactivity of a material of the second conductive structure to oxygen is larger than a reactivity of tungsten to oxygen
Data Source
AI summary
A semiconductor device includes a substrate and a bit line structure disposed on the substrate. The bit line structure includes a first conductive structure and a second conductive structure, in which a material of the first conductive structure includes polysilicon. The second conductive structure is disposed in direct contact on the first conductive structure, in which a reactivity of a material of the second conductive structure to oxygen is larger than a reactivity of tungsten to oxygen.