Micromechanical Device Horizontal Access Channel
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing micromechanical devices face challenges in efficiently accessing and sealing cavities on silicon substrates, leading to stress incorporation and surface damage during laser drilling and sealing processes, which affects the robustness and sensitivity of the devices.
Innovation Solution
A micromechanical device design featuring a silicon substrate with an oxide layer and a micromechanical functional layer, where a horizontal access channel is created in the oxide layer extending perpendicularly to the main extension plane, allowing for a DRIE trench formation and laser sealing without passing through the cap, reducing stress and surface damage by using a lower thermal conductivity material system and precise laser pulse for sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If laser drilling or trenching is used to create access channels to cavities, then the cavity can be accessed and sealed, but tensile stress forms in the material due to thermal contraction during laser processing
Solution Approach 1:
The patent transitions from vertical access channels (perpendicular to the substrate surface) to horizontal access channels (parallel to the substrate surface). The access channel extends in the plane of the substrate from the cavity to an access area, avoiding the need to drill through the cap and reducing thermal stress on the functional layer.
2Ease of operation
If laser drilling is used to create access channels, then the cavity can be accessed, but the surface is damaged and chemical and electrical changes occur
Solution Approach 1:
The patent replaces the mechanical/laser drilling process with a chemical etching process using DRIE (Deep Reactive Ion Etching) to create the access channel. This substitution allows for precise channel formation without the thermal damage and surface changes associated with laser drilling.
3Manufacturing precision
If additional process steps are used to create access channels and seal cavities, then precise control is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines multiple functions into the horizontal access channel structure: it serves as the access path to the cavity, the sealing structure (when filled with sealing material), and the stress-relief feature. This integration reduces the number of separate process steps compared to vertical channel approaches that require separate sealing operations.
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 a more robust and less sensitive manufacturing process with reduced tensile stress, improved geometries for stress reduction, and a more cost-efficient component design by eliminating the need for additional process steps, while protecting the surface from chemical and electrical changes.
Implementation Method 1
a silicon substrate with an overlying oxide layer and with a micromechanical functional layer lying above same
Implementation Method 2
a portion of the functional layer in the access area is advantageously fused with a laser pulse and the access channel is thus sealed
Implementation Method 3
a portion of the functional layer in the access area is advantageously fused with a laser pulse
Implementation Method 4
After solidification, the material cools locally and in the process contracts relative to the colder surroundings. A tensile stress forms within the material
Implementation Method 5
the additional access channel is formed as a DRIE trench. In this way, a channel having a high aspect ratio and therefore minimal use of space may be advantageously created
Data Source
AI summary
A micromechanical device that includes a silicon substrate with an overlying oxide layer and with a micromechanical functional layer lying above same, which extend in parallel to a main extension plane, a cavity being formed at least in the micromechanical functional layer and in the oxide layer. An access channel is formed in the oxide layer and/or in the micromechanical functional layer which, starting from the cavity, extends in parallel to the main extension plane and in the process extends in a projection direction, as viewed perpendicularly to the main extension plane, all the way into an access area outside the cavity. A method for manufacturing a micromechanical device is also described.