Structured Wafer With Through Passages for Device Release
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Solution Overview
Problem
Current semiconductor device processing methods using handle wafers are inefficient due to long etching times, device adhesion issues, and high costs associated with consuming handle wafers, particularly silicon wafers, which are often destroyed during the process and do not yield high-quality crystalline silicon when metal or ceramic wafers are used.
Innovation Solution
A structured wafer with through passages, such as vertical holes and surface channels, is used as a reusable handle wafer, allowing for efficient release of devices via etching through these passages, reducing adhesion, and enabling multiple batches of devices to be processed without destroying the wafer, thus lowering fabrication costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional handle wafers are used for device processing, then devices can be processed and released, but the etching process takes a long time (30 minutes to hours) and devices may adhere to each other or re-adhere to the handle wafer
Solution Approach 1:
The handle wafer is segmented by creating an array of through-holes through its thickness, dividing the solid wafer into a porous structure. This segmentation allows etchant to access the release layer from multiple locations simultaneously, reducing etching time from 30 minutes to hours down to seconds or minutes, while also preventing device adhesion by eliminating large continuous contact areas
Solution Approach 2:
The handle wafer is transformed into a porous material by forming through-holes through its thickness. This porous structure enables rapid etchant penetration and release layer removal while reducing the surface area available for device adhesion, thereby solving both the time loss and reliability issues simultaneously
2Productivity
If silicon handle wafers are used and consumed by the process, then devices can be processed, but the handle wafers need to be destroyed after release and replacing them increases cost
Solution Approach 1:
Instead of discarding the silicon handle wafer after use, the through-holes are formed in it to create a reusable porous structure. The wafer can be cleaned and used for multiple batches of device processing, transforming a single-use consumable into a durable tool that reduces material waste and processing costs
Solution Approach 2:
The silicon handle wafer with through-holes becomes a universal tool that can process multiple batches of devices with different sizes, shapes, and functionalities. The porous structure provides universal access for etchant to any release layer configuration, making the same handle wafer applicable to various device types without requiring destruction or replacement
3Loss of substance
If metal and/or ceramic handle wafers are used, then handle wafer replacement cost is reduced, but high quality crystalline silicon is not yielded
Solution Approach 1:
The handle wafer parameters are changed by forming through-holes through its thickness, transforming it from a conventional solid structure to a porous structure. This parameter change allows the silicon handle wafer to achieve reusability (reducing material loss) while maintaining its inherent ability to produce high-quality crystalline silicon, resolving the contradiction between cost reduction and quality maintenance
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
The structured wafer significantly reduces etching time, minimizes device adhesion, and allows for the reuse of the wafer, thereby improving processing efficiency and reducing material costs while maintaining high-quality device production.
Implementation Method 1
The release layer is then removed using etchant that accesses the release layer via the through passages to thereby separate the devices from the structured wafer
Data Source
AI summary
A structured wafer that includes through passages is used for device processing. Each of the through passages extends from or along one surface of the structured wafer and forms a pattern on a top surface area of the structured wafer. The top surface of the structured wafer is bonded to a device layer via a release layer. Devices are processed on the device layer, and are released from the structured wafer using etchant. The through passages within the structured wafer allow the etchant to access the release layer to thereby remove the release layer.