Segmented Pedestal for MEMS Device Bonding
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Solution Overview
Problem
In semiconductor manufacturing, particularly for micro-electromechanical systems (MEMS), existing bonding processes face challenges in efficiently and accurately aligning and bonding devices to semiconductor substrates without damaging surrounding structures during the etching process.
Innovation Solution
The process involves forming a substrate with scored pedestals and a dielectric matrix, where the etching process is abbreviated by reducing the critical dimension of the mask-providing layer, allowing for precise alignment and bonding of a second device using a metal bonding structure within a cavity, with the pedestals supporting the device and facilitating vertical alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a full etching process is used to remove the mask-providing layer from the pedestal area, then complete removal is achieved, but damage to other structures occurs and etching time increases
Solution Approach 1:
The mask-providing layer is segmented into isolated islands through etching openings in the hard mask layer. This segmentation allows the mask layer to be completely removed from the pedestal area using a shorter, less aggressive etching process, avoiding damage to surrounding structures while achieving complete mask removal.
Solution Approach 2:
The hard mask layer is patterned with openings before the etching of the mask-providing layer. This preliminary action creates a pattern that exposes only the pedestal areas, enabling selective and abbreviated etching that removes the mask layer completely from pedestals without requiring a full etching cycle that would damage other structures.
2Manufacturing precision
If a full etching process is used to remove the mask-providing layer, then complete removal is achieved, but etching time increases
Solution Approach 1:
The mask-providing layer is divided into isolated islands by etching openings in the hard mask. This segmentation reduces the total volume of material to be removed and allows use of a shorter etching process, achieving complete mask removal while significantly reducing etching time compared to a full etching cycle.
Solution Approach 2:
Instead of applying a full etching process that would remove all mask material throughout the entire wafer, the patent applies partial etching action only to the pedestal areas where mask removal is needed. The openings in the hard mask limit the etching to specific regions, achieving complete mask removal from pedestals with abbreviated etching time.
3Productivity
If the critical dimension of the mask-providing layer is reduced, then etching time is reduced and mask removal is facilitated, but alignment precision may be affected
Solution Approach 1:
The mask-providing layer is segmented into small isolated islands through the openings in the hard mask. This segmentation creates a pattern with reduced critical dimensions that etches away quickly and completely, improving etching efficiency while the hard mask openings maintain precise alignment through their carefully controlled geometry and positioning.
Solution Approach 2:
The hard mask layer acts as an intermediary structure that defines the pattern of openings. These openings control the critical dimension of the mask-providing layer exposure, enabling reduced etching time while maintaining alignment precision through the hard mask's structurally robust and precisely controllable geometry.
4Device complexity
If devices are bonded directly to the substrate without pedestals, then the bonding process is simpler, but vertical alignment between devices is less accurate
Solution Approach 1:
The pedestals serve as intermediary structures between the substrate and the device being bonded. These pedestals provide precisely controlled height and positioning features that enable accurate vertical alignment during bonding, while the overall bonding process remains relatively simple through direct contact bonding without complex alignment mechanisms.
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 reduces the etching time and minimizes damage to other structures, ensuring precise alignment and effective bonding of devices like lasers to waveguides, enhancing the functionality of MEMS devices such as LiDAR systems.
Implementation Method 1
bonded to the semiconductor substrate by metal within the first cavity
Data Source
AI summary
A system includes a semiconductor substrate having a first cavity. The semiconductor substrate forms a pedestal adjacent the first cavity. A device overlays the pedestal and is bonded to the semiconductor substrate by metal within the first cavity. A plurality of second cavities are formed in a surface of the pedestal beneath the device, wherein the second cavities are smaller than the first cavity. In some of these teachings, the second cavities are voids. In some of these teachings, the metal in the first cavity comprises a eutectic mixture. The structure relates to a method of manufacturing in which a layer providing a mask to etch the first cavity is segmented to enable easy removal of the mask-providing layer from the area over the pedestal.