Semiconductor Concentration Gradient Fabrication
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Solution Overview
Problem
Conventional microelectronics fabrication methods are limited to producing planar devices with vertical composition gradients, which restrict the creation of dissymmetrical structures and etching techniques, making it difficult to achieve non-flat profiles and complex geometries.
Innovation Solution
A method is developed to form a continuous semiconductive region within a substrate with a non-uniform composition perpendicular to the substrate thickness, using a silicon or germanium alloy with varying layer compositions, and employing etching techniques sensitive to concentration gradients to create sloping profiles and compensate for etching difficulties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional deposition techniques are used to create composition gradients, then vertical gradients parallel to substrate thickness are achieved, but dissymmetrical structures and non-planar geometries cannot be formed
Solution Approach 1:
The patent transitions from conventional vertical composition gradients (parallel to substrate thickness) to horizontal composition gradients (perpendicular to substrate thickness). This dimensional change enables the formation of dissymmetrical structures and non-planar geometries while maintaining compatibility with standard deposition techniques, resolving the contradiction between geometric complexity and ease of manufacture
Solution Approach 2:
The invention creates dissymmetrical structures by forming continuous regions with horizontal composition gradients that extend laterally across the substrate. This asymmetry in composition distribution enables non-planar geometries and dissymmetrical device regions that cannot be achieved with conventional vertical gradients, while still using standard fabrication processes
2Shape
If standard etching techniques are used on planar substrates, then uniform etching is achieved, but sloping profiles and complex geometries cannot be created
Solution Approach 1:
The patent creates local variations in composition within continuous regions, where the concentration of alloying elements (such as germanium in silicon) varies horizontally across the substrate. These local compositional differences result in spatially varying etching rates, enabling the formation of sloping profiles and complex geometries while maintaining precise control through the controlled composition gradient
Solution Approach 2:
The invention changes the composition parameter of the semiconductor material horizontally across the substrate, creating regions with different alloy concentrations. This parameter change directly affects the etching rate, allowing standard etching techniques to produce non-uniform sloping profiles and complex geometries with precise control over the final shape
3Adaptability or versatility
If vertical composition gradients are used, then conventional fabrication methods are maintained, but dissymmetrical device regions and non-planar structures are restricted
Solution Approach 1:
The patent resolves the contradiction by changing the orientation of composition gradients from vertical to horizontal. This dimensional change allows conventional fabrication methods to be maintained while enabling dissymmetrical device regions and non-planar structures, thereby increasing device geometry flexibility without introducing excessive structural complexity
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 enables the fabrication of semiconductive devices with non-planar geometries and controlled etching profiles, allowing for the production of devices with unique geometries and overcoming etching challenges in high aspect ratios, such as sensors and MOS transistors with dissymmetrical regions.
Implementation Method 1
depositing a plurality of conformal layers in the trench, each layer formed of an alloy material, and each alloy material layer having a gradually differing material concentration
Implementation Method 2
performing heat drive-in to stimulate lateral diffusion of the second material from the alloy material filling the trench and into the first material in the layer
Data Source
AI summary
A semiconductive device is fabricated by forming, within a semiconductive substrate, at least one continuous region formed of a material having a non-uniform composition in a direction substantially perpendicular to the thickness of the substrate.