Light Blocking Layer for Laser Annealed Source/Drain Contacts
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Solution Overview
Problem
High contact resistance between source/drain contacts and source/drain structures in transistors limits device performance, especially in nanowire FETs, due to excessive laser energy used for dopant activation, which causes thermal damage to the semiconductor channel and metal gate during the annealing process.
Innovation Solution
A light blocking layer is introduced to absorb or reflect laser irradiation during the nanosecond laser annealing process, preventing thermal damage to the gate and channel regions, allowing for effective dopant activation in the source/drain contact regions without deactivating dopants caused by the gate formation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high laser energy is used for dopant activation in source/drain contact regions, then dopant activation effectiveness is improved, but thermal damage to gate and channel structures occurs
Solution Approach 1:
The patent applies local quality by creating spatially selective laser irradiation where the source/drain contact regions receive high energy laser treatment for dopant activation, while the gate and channel regions are protected from thermal damage through selective shielding or energy distribution, allowing different parts of the device to experience different thermal conditions appropriate to their function
Solution Approach 2:
The patent introduces an intermediary mechanism (such as a mask layer or selective absorption structure) that mediates the laser energy distribution, allowing the laser to activate dopants in contact regions while preventing excessive energy from reaching and damaging the gate and channel structures
2Reliability
If laser annealing is performed to activate dopants in source/drain contact regions, then contact resistance is reduced, but the metal gate integrity is compromised
Solution Approach 1:
The patent implements local quality by directing laser energy selectively to source/drain contact regions where dopant activation is needed, while the metal gate region is either shielded or receives significantly reduced energy, thus reducing contact resistance without compromising gate integrity
Solution Approach 2:
The patent applies preliminary action by performing laser annealing on source/drain contact regions before final gate formation or by using selective shielding during gate formation, ensuring that dopant activation occurs without exposing the metal gate to damaging thermal conditions
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 solution enhances device performance and reliability by reducing contact resistance and preventing thermal damage to the gate and channel structures, enabling efficient dopant activation and maintaining device integrity.
Implementation Method 1
A light blocking layer is introduced to absorb or reflect laser irradiation during the nanosecond laser annealing process
Implementation Method 2
A light blocking layer is introduced to absorb or reflect laser irradiation during the nanosecond laser annealing process
Implementation Method 3
performing a laser annealing process to activate dopants in the source/drain contact regions
Implementation Method 4
performing a laser annealing process to activate dopants in the source/drain contact regions
Data Source
AI summary
A method of forming a semiconductor device includes forming source/drain contact openings extending through at least one dielectric layer to expose source/drain contact regions of source/drain structures. The method further includes depositing a light blocking layer along sidewalls and bottom surfaces of the source/drain contact openings and a topmost surface of the at least one dielectric layer. The method further includes performing a laser annealing process to activate dopants in the source/drain contact region. The method further includes forming source/drain contact structures within source/drain contact openings.