Generic Substrate Partition Removal for MEMS Cavity Fabrication

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Solution Overview

Problem

Existing MEMS device manufacturing methods require custom substrate development for each device topology, which is inefficient and costly, as sensitive information about cavity geometry and spacing is often proprietary to the substrate manufacturer.

Innovation Solution

A method using a generic substrate with predefined partitions and elementary cavities, allowing for the production of devices with membranes overhanging cavities by selectively removing temporary partitions, enabling standardization across various device topologies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If custom substrate development is performed for each device topology, then manufacturing precision and device performance are improved, but device complexity and development time increase

Engineering Contradiction:
Improvecavity geometry precisionVSAvoidsubstrate process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The substrate is segmented into reusable generic substrate layers and device-specific cavity patterns. The generic substrate contains standardized membranes and support structures that can be repeatedly used across different device topologies, while only the cavity definition step needs to be customized for each device type.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A universal generic substrate is created that can serve multiple device fabrication purposes. The substrate contains standardized components (membranes, support structures, partitions) that can be used across different device topologies, eliminating the need for custom substrate development for each device type.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If custom substrate development is performed for each device topology, then device performance is improved, but productivity and development speed decrease

Engineering Contradiction:
Improvedevice performanceVSAvoiddevice development speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The generic substrate is prepared in advance with all standardized components (membranes, support structures, partitions) already in place. This preliminary action eliminates the need for repeated substrate development cycles, allowing rapid fabrication of different device topologies by simply defining different cavity patterns on the pre-prepared substrate.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If extensive material removal and etching are performed, then precise cavity geometries are achieved, but manufacturing time and process complexity increase

Engineering Contradiction:
Improvecavity geometry precisionVSAvoidetching time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

Instead of removing large amounts of material to create cavities, the invention extracts only the necessary partition material locally. The generic substrate already contains pre-formed membranes and support structures, so only the minimal material needed for partitions and cavity definition is removed through localized etching processes.

Inventive Principle:
Principle #2Taking out (Extraction)

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 efficient and economical manufacturing of MEMS devices with precise cavity geometries without requiring custom substrate development, reducing material removal and etching time, and allowing for diverse device applications.

Implementation Method 1

the assembly comprises bonding by molecular adhesion between, on the one hand, the donor substrate, and on the other hand, the first face of the support substrate

Methodology Applied
Scientific EffectMolecular adhesion: Adhesive

Implementation Method 2

a step of separating the surface layer from the support substrate by mechanical force

Methodology Applied
Scientific EffectMechanical force: Mechanical Force

Implementation Method 3

the removal of the partitions located inside the contour of the group of elementary cavities comprises the local etching of the surface layer to form at least one opening passing through said surface layer, and the chemical etching of said partitions via said opening

Methodology Applied
Scientific EffectChemical etching: Chemical Bonding

Data Source

PatentEP3898503B1Method for manufacturing a device comprising a membrane extending over a cavity
Publication Date: 2025.10.08 SOITEC SA
  • EP3898503B1 patent drawingFigure 1a~1c
  • EP3898503B1 patent drawingFigure 1d~1f
  • EP3898503B1 patent drawingFigure 2a~2b

AI summary

The invention concerns a method for manufacturing a device comprising a membrane extending over a useful cavity, the method comprising: • Providing a generic structure comprising a surface layer extending in a main plane and arranged on a first face of a support substrate, the support substrate comprising elementary cavities opening under the surface layer and partitions delimiting each elementary cavity, the partitions having top surfaces that form all or part of the first face of the support substrate; • Defining a group of adjacent elementary cavities, such that a contour of the group of elementary cavities corresponds, in the main plane, to a contour of the useful cavity; Removing the partitions situated within the contour of the group of elementary cavities, in order to form the useful cavity, and to free the surface layer arranged above the useful cavity and forming the membrane.