Backside Recessed Bond Pad Structure for Substrate Bowing Control
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Solution Overview
Problem
The semiconductor industry faces challenges in manufacturing smaller and more complex integrated circuits due to substrate bowing and warpage caused by bond pad structures, which complicates the patterning of small features and affects the focus depth and resolution of photolithography tools.
Innovation Solution
A method involving the formation of a recess in the substrate to expose a conductive bond pad, followed by the deposition of conformal layers that induce minimal strain, and subsequent chemical mechanical planarization to reduce substrate bowing, using a combination of oxide and nitride layers to manage stress and achieve a planarized surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conformal layers are deposited over the bond pad to manage stress, then substrate bowing is reduced, but the manufacturing process complexity increases
Solution Approach 1:
The stress management approach is segmented into multiple discrete conformal layers (oxide layer, nitride layer, and additional oxide layers) deposited at different stages. Each layer serves a specific stress compensation function, allowing precise control of substrate bowing while maintaining process modularity and manageability.
Solution Approach 2:
Stress compensation layers are deposited preliminarily during the fabrication process before final bonding operations. The oxide and nitride layers are formed in advance to preemptively counteract substrate bowing, ensuring planarity is maintained throughout subsequent processing steps.
2Strength
If the bond pad structure is optimized for bonding, then bonding strength is improved, but substrate warpage increases
Solution Approach 1:
Conformal oxide and nitride layers are deposited over the bond pad structure to provide counterbalancing stress that offsets the bowing and warping forces generated by the bonding process. These layers act as a counterweight to the destabilizing stresses, maintaining substrate planarity while allowing strong bonding to occur.
Solution Approach 2:
The bond pad structure incorporates a composite multilayer system consisting of metal bond pad, oxide layers, and nitride layers. Each material contributes different mechanical and stress properties, creating a composite structure that achieves both strong bonding capability and substrate stability through balanced stress distribution.
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 substrate bowing and warpage, making it easier to pattern small features and improve the focus depth and resolution of photolithography tools, thereby enhancing the manufacturing process for complex integrated circuits.
Implementation Method 1
subsequent chemical mechanical planarization to reduce substrate bowing
Implementation Method 2
deposition of conformal layers that induce minimal strain
Data Source
AI summary
A method of fabricating a semiconductor device includes receiving a device substrate; forming an interconnect structure on a front side of the device substrate; and etching a recess into a backside of the device substrate until a portion of the interconnect structure is exposed. The recess has a recess depth and an edge of the recess is defined by a sidewall of the device substrate. A conductive bond pad is formed in the recess, and a first plurality of layers cover the conductive bond pad, extend along the sidewall of the device substrate, and cover the backside of the device substrate. The first plurality of layers collectively have a first total thickness that is less than the recess depth. A first chemical mechanical planarization is performed to remove portions of the first plurality of layers so remaining portions of the first plurality of layers cover the conductive bond pad.