Devices having a semiconductor material that is semimetal in bulk and methods of forming the same
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Solution Overview
Problem
Current semiconductor devices, particularly transistors, face limitations in operation speed due to the characteristics of traditional semiconductor materials, which can be improved by incorporating semimetal materials like bismuth in bulk form to enhance performance.
Innovation Solution
The method involves forming bismuth-containing channel structures within transistors by depositing bismuth material in channel openings of the semiconductor substrate, where the bismuth transitions from a semimetal to a semiconductor, and subsequent annealing to crystallize the material, creating vertical channel transistors with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional semiconductor materials are used in transistors, then manufacturing process is well-established and reliable, but operation speed and carrier mobility are limited
Solution Approach 1:
The patent changes the material parameter from traditional semiconductor (silicon) to semimetal (bismuth), fundamentally altering the electrical properties and carrier mobility of the channel material. This parameter change enables faster operation speed while maintaining compatibility with existing manufacturing processes through controlled deposition and annealing techniques.
Solution Approach 2:
The patent creates a composite structure by combining bismuth (semimetal) with semiconductor materials, forming a hybrid material system that exhibits both the high carrier mobility of semimetals and the controllable semiconductor properties needed for transistor operation. This composite approach resolves the contradiction between speed improvement and manufacturing ease.
2Reliability
If bismuth material is deposited in channel openings, then carrier mobility and current speed are enhanced, but material phase transition control becomes critical
Solution Approach 1:
The patent deliberately utilizes the phase transition of bismuth from semimetal to semiconductor state through controlled annealing processes. By precisely controlling the annealing temperature and atmosphere, the patent achieves reliable phase transition that enhances device performance while maintaining manufacturing precision. The phase transition is harnessed as a key mechanism to transform the material properties in situ.
Solution Approach 2:
The patent performs preliminary deposition of bismuth material in the amorphous or polycrystalline state before controlled annealing to induce crystallization and phase transition. This preliminary action sets up the material in a state that is ready for controlled transformation, ensuring both reliability of the final semiconductor phase and precision in the phase transition process.
3Productivity
If semimetal materials are used to improve operation speed, then transistor performance increases, but dopant diffusion issues may arise
Solution Approach 1:
The patent extracts or removes the dopant diffusion problem by using intrinsic carrier generation mechanisms in bismuth rather than relying on dopant diffusion. The high carrier mobility in bismuth is achieved through its semimetallic band structure and intrinsic properties, eliminating the need for dopant introduction and the associated diffusion issues that plague traditional semiconductor materials.
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 carrier mobility and current speed of transistors, allowing for faster operation and integration into advanced semiconductor devices without adverse dopant diffusion, thus improving overall device performance.
Implementation Method 1
the bismuth transitions from a semimetal to a semiconductor
Implementation Method 2
subsequent annealing to crystallize the material
Implementation Method 3
depositing bismuth material in channel openings
Data Source
AI summary
Devices, and methods of forming such devices, having a material that is semimetal when in bulk but is a semiconductor in the devices are described. An example structure includes a substrate, a first source/drain contact region, a channel structure, a gate dielectric, a gate electrode, and a second source/drain contact region. The substrate has an upper surface. The channel structure is connected to and over the first source/drain contact region, and the channel structure is over the upper surface of the substrate. The channel structure has a sidewall that extends above the first source/drain contact region. The channel structure comprises a bismuth-containing semiconductor material. The gate dielectric is along the sidewall of the channel structure. The gate electrode is along the gate dielectric. The second source/drain contact region is connected to and over the channel structure.