Selective Epitaxial Cap Element Profile for Short-Circuit Prevention
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Solution Overview
Problem
The semiconductor industry faces challenges in forming reliable semiconductor devices with increasingly smaller feature sizes due to the complexity and difficulty of fabrication processes as feature sizes continue to decrease.
Innovation Solution
The process involves forming a semiconductor device structure with a gate stack, source/drain structures, and cap elements, where the cap elements are grown using a selective epitaxial growth process with a specific gas mixture to control their profile and prevent short-circuits, and metal silicide features are formed to enhance electrical connections, while maintaining a precise distance and thickness to ensure reliability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency is improved and costs are lowered, but fabrication process complexity and difficulty increase
Solution Approach 1:
The fabrication process is divided into multiple sequential steps including forming mandrels, depositing first spacers, forming recesses, depositing second spacers, and forming cap elements. Each step builds upon the previous one, allowing complex structures to be created through manageable, modular processes that can be performed with existing fabrication equipment
Solution Approach 2:
Mandrels are formed in advance as templates before the actual source/drain structures are created. These mandrels guide the subsequent spacer formation and material deposition processes, ensuring precise positioning and dimensions are achieved without requiring direct manipulation of the final structures
2Productivity
If feature sizes continue to decrease, then functional density increases, but reliability of semiconductor devices decreases
Solution Approach 1:
The patent employs selective epitaxial growth with controlled gas mixtures (including HCl gas) to precisely control the growth rate and composition of cap elements. By adjusting process parameters such as temperature, pressure, and gas flow rates, the cap elements achieve optimal thickness and material composition that ensure reliability in scaled devices
Solution Approach 2:
The semiconductor structure incorporates multiple materials including silicon, silicon germanium, and metal silicides in different layers and regions. These composite materials provide tailored electrical, mechanical, and thermal properties that maintain device reliability despite reduced feature sizes
3Reliability
If cap elements are formed with larger contact landing area, then electrical connections are improved, but risk of short-circuits between adjacent structures increases
Solution Approach 1:
The cap elements exhibit different properties in different regions: they have sufficient thickness and material composition for reliable electrical contact in the contact landing area, while maintaining appropriate spacing and profile control in regions adjacent to other structures. The selective epitaxial growth ensures locally optimized characteristics that simultaneously achieve good electrical connection and prevent short-circuits
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 improves the performance and reliability of semiconductor devices by providing a larger contact landing area and preventing short-circuits, ensuring the semiconductor device structure's integrity and efficiency in smaller geometries.
Implementation Method 1
the cap elements are grown using a selective epitaxial growth process with a specific gas mixture to control their profile and prevent short-circuits
Data Source
AI summary
A semiconductor device structure is provided. The semiconductor device structure includes an epitaxial structure over a substrate and a cap element over the epitaxial structure. The cap element has a first thickness measured between a top surface of the cap element and a top surface of the epitaxial structure. The cap element has a second thickness measured between a side surface of the cap element and a side surface of the epitaxial structure. The first thickness and the second thickness are different from each other.