Gate Protection Caps for Self-Aligned Contacts in Semiconductor Devices
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Solution Overview
Problem
The increasing integration density in semiconductor manufacturing, driven by reduced feature sizes, leads to yield decreases in integrated circuits due to issues like misaligned contacts and improper electrical connections in transistor structures.
Innovation Solution
A gate-last process is employed, involving the formation of gate spacers, dielectric layers, and gate protection caps to prevent misalignment and electrical shorts, using techniques like chemical mechanical polishing, etching, and conformal deposition to create a structure that allows for self-alignment of contacts and reduces the likelihood of bridges between gate electrodes and substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the minimum feature size is reduced to increase integration density, then more components can be integrated into a given area and latency decreases, but misalignment and electrical connection problems increase causing yield to decrease
Solution Approach 1:
The gate protection cap is formed over the gate electrode before contact formation, establishing a protective structure in advance that defines the contact opening boundaries and prevents misalignment during subsequent processing steps
Solution Approach 2:
The gate protection cap acts as an intermediary structure between the gate electrode and the contact opening, providing a reference boundary that ensures proper alignment and prevents direct exposure of the gate electrode to etching processes
2Productivity
If the minimum feature size is reduced to increase integration density, then more components can be integrated into a given area, but electrical shorts and bridges between gate electrodes and substrates increase
Solution Approach 1:
The gate protection cap is formed in advance to prevent potential electrical shorts and bridges between the gate electrode and substrate by providing a protective barrier that stops etching processes from creating unwanted conductive paths
Solution Approach 2:
The gate protection cap serves as an intermediary protective layer that prevents direct interaction between the gate electrode and the substrate, eliminating the risk of electrical shorts while allowing the gate electrode to maintain its electrical connection to the gate contact
3Ease of manufacture
If conventional gate structures are used without protection caps, then the manufacturing process is simpler, but contacts cannot be properly self-aligned and bridges may form
Solution Approach 1:
The gate protection cap acts as an intermediary reference structure that enables self-alignment of contacts by providing a clearly defined boundary that guides the formation of contact openings, eliminating the need for complex alignment procedures
Solution Approach 2:
The gate protection cap enables self-alignment of contacts by providing its own structure as the alignment reference, allowing the contact opening to be automatically positioned correctly relative to the gate electrode without requiring external alignment marks or complex positioning systems
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 enhances the processing window in small pitch technologies, ensuring higher yield and reliability by preventing electrical failures and improving contact alignment, thus maintaining circuit performance.
Implementation Method 1
using techniques like chemical mechanical polishing, etching, and conformal deposition
Implementation Method 2
using techniques like chemical mechanical polishing, etching, and conformal deposition
Implementation Method 3
using techniques like chemical mechanical polishing, etching, and conformal deposition to create a structure
Data Source
AI summary
A structure includes a substrate, a gate structure over the substrate, a dielectric layer over the substrate, and a cap over a gate electrode of the gate structure. Top surfaces of the dielectric layer and gate electrode are co-planar. The gate structure extends a gate lateral distance between first and second gate structure sidewalls. The cap extends between first and second cap sidewalls. A first cap portion extends from a midline of the gate structure laterally towards the first gate structure sidewall and to the first cap sidewall a first cap lateral distance, and a second cap portion extends from the midline laterally towards the second gate structure sidewall and to the second cap sidewall a second cap lateral distance. The first cap lateral distance and the second cap lateral distance are at least half of the gate lateral distance.