Bonded IC Substrate Structure for Overlay Stability in Thinning
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Solution Overview
Problem
As semiconductor substrates become thinner and pattern sizes decrease, the IC device faces challenges with bending distortion and overlay errors, which affect the critical dimension uniformity and reliability of the device.
Innovation Solution
The IC device incorporates a structure with a first semiconductor substrate and a second semiconductor substrate, where the Young's modulus of different crystal orientations between the two substrates is utilized to minimize bending distortion and overlay errors. This is achieved through a specific bonding process and polishing techniques to form BEOL structures on both sides of the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the semiconductor substrate thickness is reduced to achieve higher integration, then the device density increases, but bending distortion and overlay errors occur
Solution Approach 1:
The patent employs a composite structure consisting of a first semiconductor substrate and a second semiconductor substrate with different crystal orientations bonded together. This composite substrate structure compensates for bending distortion by utilizing the different mechanical properties (Young's modulus) of the two substrates, thereby maintaining overlay consistency even when the overall substrate thickness is reduced for higher integration.
Solution Approach 2:
The patent changes the crystal orientation parameter of the semiconductor substrates, specifically using <100> for the first substrate and <110> or <100> for the second substrate. This parameter change results in different Young's modulus values, which enables the composite structure to resist bending distortion and maintain manufacturing precision during thinning processes.
2Productivity
If the substrate is thinned to improve device integration, then more components can be integrated, but critical dimension uniformity deteriorates due to bending distortion
Solution Approach 1:
The composite substrate structure with different crystal orientations provides mechanical stability that prevents bending distortion during thinning, thereby maintaining critical dimension uniformity while enabling higher integration density through substrate reduction.
Solution Approach 2:
The second semiconductor substrate acts as a counterweight to the first substrate, compensating for the bending forces that occur during thinning. The different Young's modulus values create a balanced structure that resists distortion, ensuring critical dimension uniformity is maintained throughout the manufacturing process.
3Area of moving object
If pattern sizes are reduced to increase integration, then device density improves, but overlay errors increase due to substrate bending
Solution Approach 1:
The composite substrate structure maintains flatness and reduces bending distortion even when pattern sizes are reduced, thereby preserving overlay consistency for small-scale high-density patterns that would otherwise be affected by substrate deformation.
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 enhances the overlay consistency and reduces process failures, leading to improved critical dimension uniformity and increased reliability of the IC device, even as the semiconductor substrate thickness decreases and pattern sizes shrink.
Implementation Method 1
a Young's modulus of a first crystal orientation extending parallel to the frontside surface of the first semiconductor substrate is different from a Young's modulus of a second crystal orientation that overlaps the first crystal orientation in the vertical direction and extends parallel to the first crystal orientation in the second semiconductor substrate
Data Source
AI summary
An integrated circuit device includes a first semiconductor substrate having a frontside surface and a backside surface, a front-end-of-line (FEOL) structure on the frontside surface of the first semiconductor substrate, the FEOL structure including a plurality of fin-type active regions, a back-end-of-line (BEOL) structure on the FEOL structure, a second BEOL structure on the backside surface of the first semiconductor substrate, and a second semiconductor substrate spaced apart from the first semiconductor substrate in the vertical direction with the FEOL structure and the first BEOL structure therebetween, wherein a Young's modulus of a first crystal orientation extending parallel to the frontside surface of the first semiconductor substrate is different from a Young's modulus of a second crystal orientation that overlaps the first crystal orientation in the vertical direction and extends parallel to the first crystal orientation in the second semiconductor substrate.