Direct Bonding Contact Layout for Higher Alignment Tolerance
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Solution Overview
Problem
Achieving accurate alignment and reliable metal bonding between semiconductor elements with small or compact contact pads is challenging, as traditional pick-and-place tools struggle to align features outside typical size ranges, leading to misalignment and increased parasitic capacitance with larger pads.
Innovation Solution
The use of elongate contact features with lengths significantly greater than their widths allows for improved alignment tolerances and reduced parasitic capacitance, enabling direct bonding of metal and non-metal regions without external pressure, using nitrogen-containing species for chemical bonding at room temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If small or compact contact pads are used, then parasitic capacitance is reduced and footprint is minimized, but alignment precision deteriorates making bonding difficult
Solution Approach 1:
The contact features are designed with elongated geometry in one dimension while maintaining compact size in perpendicular dimensions. This dimensional transformation allows the contact features to provide both small footprint (reducing parasitic capacitance) and extended alignment tolerance (improving bonding precision) simultaneously
Solution Approach 2:
The aspect ratio of contact features is changed from conventional compact shapes to elongated shapes with significantly greater length than width. This parameter change in geometry enables the contact features to tolerate larger misalignments while maintaining small overall footprint, resolving the contradiction between alignment precision and parasitic capacitance
2Ease of manufacture
If traditional pick-and-place tools are used for bonding, then existing bonding processes can be maintained, but alignment accuracy deteriorates for small contact pad features
Solution Approach 1:
The bonding process is segmented into two independent functions: mechanical bonding of non-metal regions and electrical bonding of metal contact features. This segmentation allows each function to be optimized independently, enabling use of traditional pick-and-place tools for mechanical bonding while the elongated contact features provide inherent alignment tolerance for electrical connection
Solution Approach 2:
The elongated contact features provide self-aligning capability through their geometry. The increased length in one dimension creates a larger overlap region that automatically compensates for misalignment, eliminating the need for high-precision alignment tools or complex alignment procedures
3Manufacturing precision
If larger contact pads are used, then alignment tolerance is improved, but parasitic capacitance increases and footprint enlarges
Solution Approach 1:
Instead of increasing contact pad size uniformly in all dimensions, the design transforms the geometry to be elongated in one dimension while maintaining compact dimensions in perpendicular directions. This dimensional transformation provides large alignment tolerance through increased length while keeping the footprint and parasitic capacitance low by maintaining small width and area
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 enables precise alignment and bonding of semiconductor elements with smaller feature sizes, reducing parasitic capacitance and maintaining a low footprint, while accommodating larger misalignments and eliminating the need for external pressure or heat.
Implementation Method 1
using nitrogen-containing species for chemical bonding at room temperature
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A bonded device structure including a first substrate having a first set of conductive contact structures, preferably connected to a device or circuit, and having a first non-metallic region adjacent to the contact structures on the first substrate, a second substrate having a second set of conductive contact structures, preferably connected to a device or circuit, and having a second non-metallic region adjacent to the contact structures on the second substrate, and a contact-bonded interface between the first and second set of contact structures formed by contact bonding of the first non-metallic region to the second non- metallic region. The contact structures include elongated contact features, such as individual lines or lines connected in a grid, that are non-parallel on the two substrates, making contact at intersections. Alignment tolerances are thus improved while minimizing dishing and parasitic capacitance.