Electrochemical Void Formation in Semiconductor Devices
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Solution Overview
Problem
Conventional device processing techniques for integrated circuits and MEMS devices often require additional and costly procedures to form voids and patterned structures, which are not compatible with standard integrated circuit processing and add unnecessary steps.
Innovation Solution
The formation of voids is achieved using conventional processing techniques by creating a patterned trench configuration that includes both metal regions and voids, where the conductive material is electrochemically removed through electrochemical corrosion induced by electromagnetic radiation and an electrolyte, eliminating the need for additional lithographic steps and processing modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional integrated circuit processing techniques are used to form voids and patterned structures, then manufacturing precision and device functionality are improved, but device complexity and processing steps increase
Solution Approach 1:
The patent combines void formation with metal interconnect formation into a single integrated process. Trenches are etched to define both metal regions and void regions simultaneously, and conductive material is deposited to fill only the metal regions while leaving void regions empty. This merging eliminates separate void formation steps and lithographic processes that would otherwise be required.
Solution Approach 2:
The patent performs preliminary patterning of trenches that define both future metal regions and void regions before metal deposition. By pre-configuring the trench pattern to include both types of regions, the process eliminates the need for subsequent lithographic steps to define void boundaries, thereby simplifying the overall processing sequence.
2Manufacturing precision
If additional lithographic steps are used to pattern voids, then void formation precision is improved, but productivity and manufacturing cost worsen
Solution Approach 1:
The patent merges void patterning with metal interconnect patterning into a single lithographic step. The same photolithographic process that defines metal trench patterns also defines void region patterns, eliminating additional lithographic steps and associated productivity losses.
Solution Approach 2:
The patent makes the trench etching process multi-functional by designing it to simultaneously define both metal interconnect regions and void regions. This universal approach allows a single process step to accomplish what would traditionally require separate dedicated processes for each feature type.
3Manufacturing precision
If crystallographically selective etching is used to form channels in MEMS devices, then void formation precision is improved, but ease of manufacture and cost worsen
Solution Approach 1:
The patent changes the etching parameter from crystallographically selective (which requires specific crystal orientations) to chemically selective etching that uses material composition differences. This allows channels to be formed in amorphous or polycrystalline materials without requiring specific crystal orientations, making the process compatible with standard MEMS and integrated circuit fabrication.
Solution Approach 2:
The patent replaces crystallographically selective etching (which relies on mechanical/crystallographic properties) with chemically selective etching that relies on electrochemical potential differences. This substitution enables void formation using conventional wet or vapor HF etching processes that are already standard in semiconductor manufacturing.
4Ease of manufacture
If conventional processing techniques are used without modifications, then ease of manufacture is improved, but ability to form voids and patterned structures worsens
Solution Approach 1:
The patent performs preliminary design of trench patterns that inherently define both metal and void regions. By pre-configuring the trench geometry and positioning charge separation structures appropriately, the process enables void formation using standard electrochemical etching without requiring process modifications.
Solution Approach 2:
The patent enables the electrochemical etching process to self-differentiate between metal regions and void regions through the presence of charge separation structures. These structures generate local electric fields that drive selective etching in metal regions while protecting void regions, allowing the process to automatically perform the differentiation that would otherwise require additional patterning steps.
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 allows for the cost-effective fabrication of devices with voids, such as integrated circuits and MEMS structures, without adding processing steps, enabling improved high-frequency characteristics and efficient separation of mechanical entities from substrates.
Implementation Method 1
The illumination of the charge separation structure introduces a separation of electrons and holes
Implementation Method 2
the conductive material occupying trenches 23 are removed by a electrochemical wet process
Data Source
AI summary
Devices having voids are producible by employing an electrochemical corrosion process. For example, an electrically conductive region is formed to have a surrounding chemically distinct region. Such formation is possible through conventional semiconductor processing techniques such as a copper damascene process. The surrounded conducting material is configured to be in electrical communication with a charge separation structure. The electrically conducting region is contacted with a fluid electrolyte and electromagnetic radiation is made to illuminate the charge separation region to induce separation of electrons and holes. The resulting separated charges are used to drive an electrochemical corrosion process at the conductive material/electrolyte interface resulting in the removal of at least a portion of the electrically conducting material. The induced corrosion leaves a void that is useful, for example, as a highly effective dielectric in integrated circuits, functions to allow component separation such as gear separation in microelectromechanical devices or produces long cavities useful for material separation analogous to the distillation columns used in liquid chromatography.