Cantilever Structure Void Formation via Germanium Sacrificial Layer
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Solution Overview
Problem
The presence of silicon residues beneath the oxide cantilever beam in integrated optical waveguide sensors hinders the suspension of the cantilever beam and prevents the effective filling of organic polymer, leading to transmission loss of light or optical signals, which existing isotropic dry etching methods cannot adequately address.
Innovation Solution
A method involving the formation of a recess in a semiconductor substrate, deposition of a sacrificial layer, and subsequent etching to create a cantilever structure with a void, using a sacrificial layer of germanium and a corrosion solution to remove the germanium, ensuring the cantilever structure is suspended without residues, allowing for proper filling with an organic polymer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If isotropic dry etching is used to form an oxide cantilever beam, then the cantilever beam can be formed with the desired width, but silicon residues remain below the cantilever beam preventing suspension
Solution Approach 1:
A sacrificial layer (silicon nitride or germanium) is introduced as an intermediary substance between the substrate and the cantilever beam. This sacrificial layer enables complete removal of silicon residues through selective etching, allowing cantilever suspension while maintaining precise width control during the etching process.
Solution Approach 2:
The sacrificial layer is deposited beforehand on the substrate before forming the cantilever beam. This preliminary action creates a protective barrier that prevents silicon residue contamination and enables subsequent complete removal of residues through selective etching processes.
2Reliability
If organic polymer is filled below and above the cantilever beam to prevent transmission loss, then light transmission is maintained, but the poor morphology of the cantilever beam hinders the filling process
Solution Approach 1:
The sacrificial layer acts as a mediator that creates a clean, residue-free interface between the substrate and cantilever beam. This clean morphology eliminates obstacles to polymer filling, allowing complete and uniform filling below and above the cantilever beam to prevent light transmission loss.
Solution Approach 2:
By removing silicon residues through selective etching of the sacrificial layer before polymer filling, the surface morphology is optimized in advance. This preliminary cleanup ensures that subsequent polymer filling can proceed smoothly and completely, maintaining both ease of manufacture and light transmission reliability.
3Object-generated harmful factors
If isotropic dry etching time is increased to remove silicon residues, then more residues are removed, but the cantilever beam suspension is still prevented in severe cases
Solution Approach 1:
The sacrificial layer serves as a selective etching target that enables complete removal of silicon residues without affecting the cantilever beam structure. By targeting the sacrificial layer specifically, the process achieves thorough residue removal while preserving cantilever integrity and enabling successful suspension.
Solution Approach 2:
The invention changes the etching selectivity parameter by introducing a sacrificial layer with different etching characteristics than the cantilever beam material. This parameter change allows differentiated etching rates, enabling complete residue removal while maintaining precise cantilever dimensions and suspension capability.
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 ensures the cantilever structure is suspended without silicon residues, facilitating the filling of organic polymer and preventing light or optical signal transmission loss, thereby enhancing the reliability and performance of integrated optical waveguide sensors.
Implementation Method 1
performing an etching process to remove a portion of the cantilever structure layer
Implementation Method 2
forming a sacrificial layer in the recess
Data Source
AI summary
A method of manufacturing a cantilever structure includes providing a semiconductor substrate, forming a recess in the semiconductor substrate, forming a sacrificial layer in the recess, forming a cantilever structure layer on the semiconductor substrate and the sacrificial layer, performing an etching process to remove a portion of the cantilever structure layer until a surface of the sacrificial layer is exposed to form a cantilever structure and an opening, and removing a portion of the sacrificial layer to form a void below the cantilever structure so that the cantilever structure is suspended in the void. The cantilever structure thus formed has good morphological properties to ensure that the cantilever structure is free of residues at the bottom and has excellent suspension even if the width of the cantilever structure is relatively large.