Maskless Photochemical Etching for 3D Semiconductor Structures
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Solution Overview
Problem
Current semiconductor fabrication techniques face challenges in achieving three-dimensional structures with multiple heights using conventional photolithography and etching, particularly in creating complex grayscale topography, as traditional grayscale masks are expensive, static, and limited in gray levels, and require iterative purchases, while direct writing techniques like laser scanning have low throughput and require precise equipment.
Innovation Solution
A method and apparatus for maskless photochemical etching that involves applying an etch solution to a semiconductor substrate, generating a spatial pattern of electron-hole pairs by projecting illumination with specified intensity, wavelength, and duration, and controlling the etch rate through temporal and spectral characteristics of the light source and electrical potential, allowing for one-step etching of multi-level structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If grayscale masks are used for photolithography, then three-dimensional structures with multiple heights can be achieved, but the cost increases and the number of gray levels is limited
Solution Approach 1:
The patent removes the mask component entirely from the system, replacing it with direct digital light projection. This extracts the limiting factor (mask gray levels) and replaces it with digital control, achieving unlimited gray levels without physical mask constraints
Solution Approach 2:
The patent uses digital projection to create virtual masks that can be software-controlled. Instead of physical grayscale masks with fixed patterns, digital images are projected that can be modified and adjusted without replacing physical components, enabling flexible design changes
2Manufacturing precision
If grayscale masks are used for photolithography, then three-dimensional structures with multiple heights can be achieved, but iterative purchases are required while perfecting the process
Solution Approach 1:
The patent transitions from static physical masks to dynamic digital projections. The projection system can change patterns, resolutions, and gray levels on-demand through software control, eliminating the need for iterative mask purchases and allowing real-time process optimization
Solution Approach 2:
The patent enables continuous adjustment of critical parameters (gray levels, resolution, patterns) through digital control. This allows optimization of the etching process by modifying projection parameters rather than purchasing new masks, saving time and enabling flexible experimentation
3Manufacturing precision
If direct writing techniques like laser scanning are used, then complex structures can be created, but the throughput is low and precise equipment is required
Solution Approach 1:
The patent transitions from serial processing (laser scanning point-by-point) to parallel processing (projector displaying entire image simultaneously). This dimensional change from 1D scanning to 2D/3D simultaneous projection dramatically increases throughput while maintaining complex structure capability
Solution Approach 2:
The patent uses a projector that can display various image formats and resolutions, making the system versatile for different structure complexities. The same projection system handles both simple and complex patterns without requiring specialized equipment for each case, improving overall productivity
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
Enables the fabrication of complex three-dimensional structures with high aspect ratios and selective etching control, improving material selectivity and reducing costs by eliminating the need for grayscale masks, while enhancing throughput and flexibility in design modifications.
Implementation Method 1
generating a spatial pattern of electron-hole pairs by projecting illumination with specified intensity, wavelength, and duration
Implementation Method 2
maskless photochemical etching that involves applying an etch solution to a semiconductor substrate, generating a spatial pattern of electron-hole pairs
Data Source
AI summary
Methods and apparatus for subtractively fabricating three-dimensional structures relative to a surface of a substrate and for additively depositing metal and dopant atoms onto the surface and for diffusing them into the bulk. A chemical solution is applied to the surface of the semiconductor substrate, and a spatial pattern of electron-hole pairs is generated by projecting a spatial pattern of illumination characterized by a specified intensity, wavelength and duration at each pixel of a plurality of pixels on the surface. Charge carriers are driven away from the surface of the semiconductor on a timescale short compared to the carrier recombination lifetime. Such methods are applied to creating a spatially varying doping profile in the semiconductor substrate, a photonic integrated circuit and an integrated photonic microfluidic circuit.