Sacrificial Layer Spacer Formation for Semiconductor Substrates
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Solution Overview
Problem
The challenge in semiconductor device manufacturing lies in forming contact plugs between closely spaced features without damaging the substrate or conductive patterns, leading to electrical shorts, high contact resistance, and poor device performance due to the difficulty in forming precise spacers during the etching process.
Innovation Solution
A method involving the use of a sacrificial layer, such as luminescent materials like gallium nitride, which is anisotropically wet etched to form a pattern that serves as a mask for etching the spacer formation layer, allowing for the creation of spacers on the sidewalls without damaging the substrate, using etching solutions like potassium hydroxide or phosphoric acid, and removing the sacrificial layer after spacer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the spacer is formed by an etching process to be thin to ensure sufficient contact area, then the contact area between contact plug and substrate is improved, but the substrate and conductive pattern are damaged
Solution Approach 1:
A sacrificial layer is introduced as an intermediary material between the etching process and the substrate. This sacrificial layer absorbs the etching damage that would otherwise directly affect the substrate and conductive pattern. The sacrificial layer is selectively removed after spacer formation, having served its protective function during the critical etching step.
Solution Approach 2:
The sacrificial layer is deposited beforehand on the substrate and conductive pattern before the spacer etching process. This pre-positioned layer acts as a cushion or buffer that prevents direct contact between the etching chemicals and the sensitive underlying structures, thereby preventing damage before it can occur.
2Manufacturing precision
If the spacer is formed thin to ensure sufficient contact area, then the contact resistance is reduced, but the breakdown voltage worsens
Solution Approach 1:
The sacrificial layer serves as a mediator that enables the formation of thin spacers without directly exposing the substrate to damaging etching processes. This allows precise control of spacer thickness for low contact resistance while the sacrificial layer protects the substrate integrity needed for maintaining breakdown voltage characteristics.
3Area of stationary object
If the spacer is formed thin to ensure sufficient contact area, then the contact plug to substrate contact is improved, but the source/drain regions are damaged causing junction leakage current
Solution Approach 1:
The sacrificial layer is deposited beforehand to cushion and protect the source/drain regions during the spacer formation etching process. This prevents etching damage that would create leakage paths, while still allowing the spacer to be formed thin enough to ensure adequate contact area for low resistance contact.
4Ease of manufacture
If conventional etching process is used to form spacer, then the manufacturing process is simple, but the manufacturing precision of spacer dimensions is poor
Solution Approach 1:
The patent replaces the direct mechanical/chemical etching of the spacer layer with a two-step process: first etching the sacrificial layer to define the precise spacer dimensions, then forming the spacer material conformally. This substitution of the etching target (from spacer material to sacrificial layer) enables much higher dimensional precision while maintaining process simplicity.
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
This approach enables the formation of spacers with precise dimensions, reducing contact resistance and preventing substrate damage, resulting in semiconductor devices with improved electrical characteristics and integration.
Implementation Method 1
the sacrificial layer is anisotropically wet etched to form a sacrificial layer pattern
Implementation Method 2
The etching solution employed by the wet etching process may comprise at least one of a potassium hydroxide solution, a sodium hydroxide solution, a hydrochloric acid solution, a phosphoric acid solution, and a sulfuric acid solution
Data Source
AI summary
A sacrificial layer and wet etch are used to form a sidewall spacer so as to prevent damage to the structure on which the spacer is formed and to the underlying substrate as well. Once the structure is formed on the substrate a spacer formation layer is formed to cover the structure, and a sacrificial layer is formed on the spacer formation layer. The sacrificial layer is wet etched to form a sacrificial layer pattern on that portion of the spacer formation layer extending along a sidewall of the structure. The spacer is formed on the sidewall of the structure by wet etching the spacer formation layer using the sacrificial layer pattern as a mask.