Direct Handle Wafer Bonding for Precise Thin Silicon Processing
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Solution Overview
Problem
Existing bonding techniques for stacked dies and wafers face challenges in achieving precise thinning of device wafers to silicon thicknesses of 1 to 10 um and processing at temperatures above 250 C, as adhesive bonding methods lack uniformity and support for chemical mechanical polishing (CMP), and are compressible.
Innovation Solution
Direct bonding of a handle wafer to a device wafer using non-adhesive techniques, allowing for precise thinning and high-temperature processing, with the handle wafer providing mechanical support and being selectively removable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If adhesive bonding is used to attach handle wafer to device wafer, then ease of handling is improved, but manufacturing precision deteriorates due to lack of uniformity for precise thinning and CMP processing
Solution Approach 1:
The patent removes the adhesive layer from the bonding interface, extracting the source of non-uniformity. By using direct non-adhesive bonding between the handle wafer and device wafer, the interface achieves atomic-level flatness and uniformity, enabling precise thinning and CMP processing that were previously impossible with adhesive bonding.
Solution Approach 2:
The patent introduces a non-adhesive bonding interface as an intermediary between the handle wafer and device wafer. This intermediary provides mechanical support and uniformity without the compressible, non-uniform adhesive layer, allowing for precise manufacturing while maintaining ease of handling during processing.
2Ease of operation
If adhesive bonding is used to attach handle wafer, then ease of handling is improved, but reliability deteriorates due to compressibility and inability to support high-temperature processing
Solution Approach 1:
The patent extracts the adhesive layer that causes reliability issues. By implementing direct non-adhesive bonding, the system eliminates the compressible interface that cannot support high-temperature processing, thereby improving reliability for temperatures above 250°C while maintaining handling capabilities through the mechanical support of the handle wafer.
Solution Approach 2:
The patent changes the bonding parameter from adhesive-based to non-adhesive direct bonding. This parameter change transforms the interface properties from compressible and temperature-sensitive to rigid and thermally stable, enabling reliable high-temperature processing while the handle wafer continues to provide mechanical support for handling.
3Ease of operation
If adhesive layer is used for bonding, then ease of handling is improved, but manufacturing precision deteriorates because adhesive layer is too compressible to support adequate planarization by CMP
Solution Approach 1:
The patent removes the adhesive layer that prevents adequate planarization. By using direct non-adhesive bonding, the bonding interface becomes sufficiently rigid to support the mechanical forces applied during CMP processing, enabling achievevement of the required surface flatness and manufacturing precision while the handle wafer provides handling support.
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 precise thinning and high-temperature processing of device wafers, ensuring uniformity and reliability of bonding surfaces, facilitating efficient stacking and bonding of microelectronic components.
Implementation Method 1
bonding a handle to the prepared first bonding surface. The handle may be directly bonded, using non-adhesive bonding techniques
Implementation Method 2
the handle wafer providing mechanical support and being selectively removable
Data Source
AI summary
Devices and techniques include process steps for preparing various microelectronic components for bonding, such as for direct bonding without adhesive. The processes include providing a first bonding surface on a first surface of the microelectronic components, bonding a handle to the prepared first bonding surface, and processing a second surface of the microelectronic components while the microelectronic components are gripped at the handle. In some embodiments, the processes include removing the handle from the first bonding surface, and directly bonding the microelectronic components at the first bonding surface to other microelectronic components.