SiGe Transistor Active Regions with Varying Germanium Concentrations
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Solution Overview
Problem
Current semiconductor technologies face challenges in meeting diverse performance requirements for transistor elements in integrated circuits, as a single type of crystalline Si/Ge material struggles to satisfy the varying threshold voltage and performance characteristics needed for different circuit areas, such as RAM cells and time-critical signal paths.
Innovation Solution
The approach involves forming transistor elements with active regions of different germanium concentrations in Si/Ge materials, allowing for tailored performance characteristics in various device areas by selectively growing Si/Ge mixtures with distinct germanium concentrations, enabling the formation of transistors with optimized conductivity and threshold voltage adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single type of crystalline Si/Ge material is used for all transistor elements, then the manufacturing process is simplified, but the performance requirements for different circuit areas (such as RAM cells and time-critical signal paths) cannot be met
Solution Approach 1:
The patent applies local quality by forming active regions with different germanium concentrations in different spatial locations on the semiconductor substrate. Specifically, first active regions are formed with a first germanium concentration suitable for RAM cells, while second active regions are formed with a second germanium concentration suitable for time-critical signal paths. This allows each region to be optimized for its specific function while using a unified manufacturing process.
Solution Approach 2:
The patent changes the material parameter (germanium concentration) to achieve different performance characteristics. By varying the germanium concentration in the Si/Ge alloy across different active regions, the patent optimizes transistor performance for different circuit applications without changing the fundamental material system or process architecture.
2Reliability
If different germanium concentrations are used in different active regions, then performance requirements for various circuit areas are met, but the manufacturing process complexity increases
Solution Approach 1:
The patent merges multiple functionality into a single selective epitaxial growth process. By using mask layers with different etch selectivities, the process can form multiple active regions with different germanium concentrations in one integrated fabrication sequence, rather than requiring separate processes for each region type.
Solution Approach 2:
The patent uses mask layers as intermediary elements to control the selective formation of active regions. The first and second mask layers, with different etch selectivities relative to the sacrificial layer, act as intermediaries that enable the selective epitaxial growth of Si/Ge material in specific regions with controlled germanium concentrations.
3Productivity
If the channel length is reduced to improve switching speed and packing density, then transistor performance and integration density improve, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by creating spatially differentiated active regions with specific germanium concentrations at precisely defined locations. The selective epitaxial growth process, guided by mask layers, ensures that each active region receives the appropriate material composition locally, maintaining manufacturing precision even as device dimensions are scaled down.
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 method allows for improved performance and flexibility in transistor design, enabling the integration of high-density RAM cells and efficient signal paths within the same semiconductor chip by providing active regions with tailored germanium concentrations, enhancing overall circuit performance and scalability.
Implementation Method 1
a first semiconductor material layer is selectively grown on an exposed surface of a first region of the semiconductor layer... a second semiconductor material layer is selectively grown on an exposed surface of a second region of the semiconductor layer
Data Source
AI summary
A semiconductor device includes a first transistor element having a first channel region and a second transistor element having a second channel region, wherein the first channel region includes a first crystalline silicon/germanium (Si/Ge) material mixture having a first germanium concentration, and wherein the second channel region includes a second crystalline Si/Ge material mixture having a second germanium concentration that is higher than the first germanium concentration.