Semiconductor Gate Cap Structure for Leakage-Safe Contact Etching
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Solution Overview
Problem
The scaling down of semiconductor integrated circuits leads to increased complexity and power dissipation, which can result in leakage currents due to the thinning of protective caps during the etching process for source/drain contact formation, reducing the yield of semiconductor devices.
Innovation Solution
A selective deposition process is employed to form a cap material over the thinned protective cap in the source/drain contact opening, increasing the distance between the gate structure and the source/drain contact, thereby preventing leakage currents and improving the yield of semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the protective cap is thinned during the etching process for source/drain contact formation, then the etching precision is improved, but the protective cap thickness becomes insufficient, leading to leakage currents
Solution Approach 1:
A capping material is deposited on the protective cap before the etching process to provide preliminary protection. This pre-deposited layer ensures that even after etching, the protective cap maintains sufficient thickness to prevent leakage currents while still allowing precise source/drain contact formation.
Solution Approach 2:
The capping material serves as a cushioning layer that compensates for the thickness loss during etching. By adding this protective layer beforehand, the system ensures that the protective cap retains adequate thickness throughout the etching process, preventing harmful leakage currents while maintaining manufacturing precision.
2Reliability
If the protective cap thickness is increased to prevent leakage currents, then the reliability is improved, but the etching precision for source/drain contact formation deteriorates
Solution Approach 1:
The protective structure is segmented into two distinct layers: the original protective cap and the additional capping material. This segmentation allows each layer to serve its specific function - the protective cap provides the primary barrier while the capping material offers additional protection without interfering with etching precision, as it can be selectively removed or designed with different etching characteristics.
Solution Approach 2:
The capping material is applied locally and selectively to specific regions of the protective cap, particularly in areas where leakage current prevention is most critical. This localized application maintains the overall protective function while preserving etching precision in contact formation regions, as the additional material can be strategically positioned to avoid interfering with the etching process.
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 selective deposition of cap material effectively prevents leakage currents, enhancing the yield and reliability of semiconductor devices by maintaining an adequate thickness of the protective cap during the source/drain contact formation process.
Implementation Method 1
A selective deposition process is employed to form a cap material over the thinned protective cap in the source/drain contact opening
Data Source
AI summary
The semiconductor structure includes a channel layer, a gate structure, a protective cap, gate spacers, a capping material, source/drain structures, and a source/drain contact. The gate structure is around the channel layer. The protective cap is over the gate structure. The gate spacers are on opposite sidewalls of the gate structure. From a cross-sectional view, the protective cap has a first sidewall covering by a first one of the gate spacers and a second sidewall opposite to the first sidewall of the protective cap and exposed from a second one of the gate spacers. The capping material is over the exposed second sidewall of the protective cap. The source/drain structures are on opposite sides of the channel layer. The source/drain contact is over one of the source/drain structures and upwardly extends over the capping material.