MEMS Resonance Wafer Separation Using Laser-Blocking Bonding Layers
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Solution Overview
Problem
In MEMS device manufacturing, existing laser processing methods risk damaging device parts on the opposite surface of the wafer due to unabsorbed laser light penetrating through the substrate during the cutting process.
Innovation Solution
A method involving the use of a second substrate bonded to the first substrate with a metal bonding portion that blocks laser light, where modified regions are formed inside both substrates along dividing lines to prevent laser penetration and facilitate clean separation without damaging electrode pads or other device parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser light is radiated from the rear surface side of the workpiece to form a modified region inside the substrate, then the substrate can be divided along the planned cutting line, but unabsorbed laser light penetrates through to the opposite surface and damages device parts formed on that surface
Solution Approach 1:
A light-absorbing layer is introduced as an intermediary component between the substrate and the device parts on the opposite surface. This layer selectively absorbs the laser light used for modifying the substrate, preventing the light from penetrating through to damage the device parts. The light-absorbing layer acts as a mediator that allows the laser processing to proceed while protecting the sensitive components.
Solution Approach 2:
The workpiece is segmented into distinct functional layers: the substrate, the light-absorbing layer, and the device parts. This segmentation allows each layer to perform its specific function - the substrate provides structural support, the light-absorbing layer protects against laser damage, and the device parts perform the intended functionality. The segmentation enables independent optimization of each layer's properties.
2Object-affected harmful factors
If a light-absorbing layer is added to block laser light, then device parts are protected from laser damage, but the device complexity and manufacturing process become more complex
Solution Approach 1:
The light-absorbing layer is merged with the substrate formation process rather than being added as a separate subsequent step. The layer is formed using the same semiconductor manufacturing techniques (such as CVD or sputtering) that are already employed for creating other substrate layers. This merging approach integrates the protective function into the existing manufacturing flow, minimizing additional process complexity.
Solution Approach 2:
The light-absorbing layer serves multiple functions: it blocks laser light to protect device parts, it can serve as an additional structural layer, and it may provide electrical isolation or other functional benefits. This multi-functionality justifies the added manufacturing step by providing multiple benefits from a single layer, thereby reducing the net increase in device complexity.
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 approach effectively suppresses damage to device parts by blocking unabsorbed laser light and ensures precise division of substrates into individual MEMS devices, reducing the risk of manufacturing defects and improving the yield of functional chips.
Implementation Method 1
the bonding portion blocks the laser light
Implementation Method 2
radiating laser light from a second main surface side of a second substrate so that a modified region is formed inside the second substrate
Data Source
AI summary
A MEMS device and a MEMS device manufacturing method are provided for suppressing damage to device parts. An exemplary method of manufacturing a resonance device includes radiating laser light from a bottom surface side of a second substrate to form modified regions inside the second substrate along dividing lines of a first substrate, which has device parts formed on a top surface thereof, and the second substrate, the top surface of which is bonded to the bottom surface of the first substrate via bonding portions. The method further includes dividing the first and second substrates along the dividing lines by applying stress to the modified regions. The bonding portions are formed along the dividing lines and block the laser light.