Polymer-Derived Ceramic Core for Semiconductor Package Substrates
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Solution Overview
Problem
Thinner semiconductor package substrates are prone to warpage due to mismatched coefficients of thermal expansion (CTE) between the substrate and the semiconductor die, leading to bending and poor mounting of dies, which traditional methods like flip flattening and stiffener attachments cannot adequately address, especially in asymmetric stack-ups with large dielectric thickness imbalances.
Innovation Solution
A package substrate with a core layer made of polymer-derived ceramic, which has a low CTE comparable to silicon, providing increased stiffness and toughness, allowing for patterned features like through-holes, and reducing warpage by lowering the overall substrate CTE without increasing thickness, enabling thinner and more robust packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the package substrate thickness is reduced to achieve thinner package profiles, then the package profile is improved, but the substrate becomes more prone to warpage and bending
Solution Approach 1:
The patent changes the material parameters of the core layer by using polymer-derived ceramic instead of traditional ceramic or laminate materials. This material substitution provides a lower CTE (coefficient of thermal expansion) that better matches the semiconductor die, reducing thermal mismatch and warpage while enabling thinner substrate designs to maintain structural stability
Solution Approach 2:
The patent employs a composite structure with a core layer made of polymer-derived ceramic material that combines the benefits of low CTE (comparable to silicon) with high stiffness and toughness. This composite approach allows the thin substrate to achieve both the desired thin profile and sufficient warpage resistance through the unique properties of the polymer-derived ceramic material
2Reliability
If traditional core layer materials are used with lowered CTE, then the CTE is improved, but the relative CTE mismatch between the overall substrate and semiconductor die remains
Solution Approach 1:
The patent achieves superior CTE matching by using polymer-derived ceramic material with a CTE comparable to silicon (the semiconductor die material). This parameter change in material selection creates a gradient-free, uniform low-CTE structure throughout the substrate, eliminating the relative CTE mismatch problem that persists with traditional multi-layer laminate materials
3Stability of the object's composition
If flip flattening processes or stiffener attachments are used to control warpage, then warpage control is improved, but the device complexity and manufacturing process complexity increase
Solution Approach 1:
The patent extracts and eliminates the need for complex post-fabrication warpage control measures (such as flip flattening processes and stiffener attachments) by incorporating the warpage resistance directly into the core layer material properties. The polymer-derived ceramic material inherently provides the necessary stiffness and CTE matching, removing the need for additional corrective processes or components
Solution Approach 2:
The substrate structure serves itself by using polymer-derived ceramic material that inherently provides both the mechanical stiffness and the thermal expansion characteristics needed to resist warpage. This self-service approach eliminates the need for external stiffener attachments or complex manufacturing processes, as the material itself performs the warpage control function
4Strength
If stiffener layers or glass cloth fibers are added to increase substrate stiffness, then the stiffness is improved, but the thickness and device complexity increase
Solution Approach 1:
The patent changes the fundamental material parameter of the core layer from traditional ceramic or laminate to polymer-derived ceramic, which provides inherently higher stiffness and toughness. This material parameter change enables the substrate to achieve the required stiffness without adding thickness through additional stiffener layers or glass cloth fibers
Solution Approach 2:
The patent uses polymer-derived ceramic as a composite material that combines the advantages of ceramic (low CTE, high stiffness) with the processing benefits of polymers. This composite material provides superior mechanical properties including high stiffness and toughness in a thin form factor, eliminating the need for additional thickening measures like stiffener attachments or embedded glass cloth fibers
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
The polymer-derived ceramic core layer effectively resists warpage and bending, enabling the fabrication of thinner, more robust semiconductor packages with improved mounting and reduced risk of fracture, suitable for applications like asymmetric antenna arrays.
Implementation Method 1
exposing a first portion of the precursor layer to a light source while masking a second portion of the precursor layer from the light source. The light source activates the resin to cross-link the polymers in the first portion into a cured polymer layer
Implementation Method 2
pyrolyzing the polymer layer to form a core layer including a polymer-derived ceramic
Data Source
AI summary
Semiconductor packages including package substrates having polymer-derived ceramic cores are described. In an example, a package substrate includes a core layer including a polymer-derived ceramic. The polymer-derived ceramic may include filler particles to control shrinkage and reduce warpage of the core layer during fabrication and use of the package substrate. The core layer may include counterbores or blind holes to embed a contact pad or an electrical interconnect in the core layer. A semiconductor die may be mounted on the package substrate and may be electrically connected to the contact pad or the electrical interconnect.