Tilted Glass Windows for Microscanner Mirrors
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Solution Overview
Problem
Current methods for producing tilted glass windows for wafer level encapsulation of microsystems face challenges such as difficulty in structuring glass at the wafer level, maintaining optical quality, mechanical stability, and avoiding cracking during bonding, especially when integrating tilted windows into microscanner mirrors to reduce parasitic reflections and image distortions.
Innovation Solution
A production method involving a semiconductor substrate with a non-symmetrical lattice plane offset at an angle, using anisotropic etching to create etching structures with different angles, and applying a cover layer to form tilted windows that are non-parallel to the substrate, allowing for section-by-section material removal to create a window region exposed and tilted relative to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a window is integrated into the package of a microsystem chip, then optical communication with the environment is enabled, but parasitic reflections arise at the window surfaces which impair image quality
Solution Approach 1:
The patent applies asymmetry by tilting the window relative to the package surface. This asymmetric orientation causes parasitic reflections to be directed away from the optical path, eliminating the harmful effect while preserving optical communication capability. The tilted window creates non-symmetric reflection angles that redirect stray light away from the imaging region.
2Object-affected harmful factors
If the window is tilted relative to the microscanner mirror, then parasitic reflections are reduced and image distortions are avoided, but the complexity of integrating the window into the package increases
Solution Approach 1:
The patent merges the window integration process with the wafer-level packaging process itself. By incorporating the tilted window as part of the cap wafer structure and using the bonding process to simultaneously achieve both packaging and window integration, the overall complexity is reduced despite the tilted geometry. The window is formed and positioned during the same manufacturing steps as the package assembly.
3Manufacturing precision
If glass is structured at the wafer level to create tilted windows, then optical quality and mechanical stability can be maintained, but cracking may occur during the bonding process
Solution Approach 1:
The patent applies preliminary action by pre-forming the tilted window structures and releasing stress in controlled steps before final bonding. The glass is structured and tilted angles are established during wafer fabrication, and stress relief measures are implemented prior to the bonding process to prevent cracking during assembly.
4Use of energy by moving object
If vacuum encapsulation is used to minimize energy consumption and increase resolution, then the microscanner mirror performance is improved, but the difficulty of hermetically sealing the package increases
Solution Approach 1:
The patent applies universality by using the cap wafer to serve multiple functions simultaneously: it provides the tilted window for optical access, acts as the hermetic seal for vacuum encapsulation, and structures the package geometry. This multi-functional approach integrates vacuum sealing with window formation, reducing overall manufacturing difficulty despite the hermetic requirements.
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 method effectively produces high-quality, tilted glass windows that reduce parasitic reflections and image distortions, enhancing the optical communication and packaging of microscanner mirrors while maintaining mechanical stability and avoiding cracking during the bonding process.
Implementation Method 1
starting from the first main surface region, section-by-section anisotropic etching into the semiconductor substrate so as to achieve an etching structure which includes, in a plane extending perpendicularly to the first main surface region of the semiconductor substrate, two different etching angles relative to the first main surface region
Data Source
AI summary
A production methods includes providing a substrate including a lattice plane that extends in a non-symmetrical manner and such that it is offset at an angle α from at least a first or second main surface region of the substrate, the first and second main surface regions extending parallel to each other; anisotropic etching, starting from the first main surface region, into the substrate so as to obtain an etching structure which includes, in a plane extending perpendicularly to the first main surface region, two different etching angles relative to the first main surface region; arranging a cover layer on the first main surface region, so that the cover layer lies against the etching structure in at least some sections; and removing, section-by-section, the material of the substrate starting from the second main surface region in the area of the deformed cover layer, so that the cover layer is exposed in at least one window region.