Package Substrate Metal Pad Layer for Reduced Via Size and Bump Pitch
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Solution Overview
Problem
Existing integrated circuit (IC) packages face challenges in minimizing inductance in the power distribution network (PDN) due to limitations in reducing the bump pitch of the package substrate, which restricts the density of connections between the deep trench capacitor and the die.
Innovation Solution
The introduction of an additional metal pad layer in the insulating layer of the package substrate's metallization layer reduces the via size by decreasing the aspect ratio, allowing for smaller metal interconnects and a reduced bump pitch, thereby enhancing the power distribution network's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the bump pitch of the package substrate is reduced to increase connection density between the deep trench capacitor and the die, then the decoupling capacitance and PDN performance are improved, but the via size and aspect ratio constraints prevent further pitch reduction
Solution Approach 1:
The patent introduces an additional metal pad layer within the existing metallization structure, effectively adding a dimensional element to the vertical stack. This allows vias to connect to the new pad layer at a reduced depth, decreasing the via aspect ratio and enabling smaller via sizes that support reduced bump pitch and higher connection density
Solution Approach 2:
The patent modifies the metallization layer parameters by inserting an additional metal pad layer, which changes the vertical distance parameter for via formation. This parameter change reduces the via aspect ratio, allowing for smaller via dimensions and enabling reduced bump pitch to achieve higher connection density
2Quantity of substance
If the via size is reduced to enable reduced bump pitch, then the connection density is improved, but the via aspect ratio increases making fabrication more difficult
Solution Approach 1:
By adding an intermediate metal pad layer within the metallization stack, the patent creates an additional connection plane that reduces the vertical distance vias must traverse. This dimensional modification decreases the via aspect ratio, making fabrication easier while enabling reduced bump pitch for higher connection density
3Quantity of substance
If the metal interconnect size is reduced to achieve reduced bump pitch, then the connection density is improved, but the alignment precision required for via-to-interconnect connections increases
Solution Approach 1:
The additional metal pad layer acts as an intermediary element between the vias and the metal interconnects. This intermediate pad provides a larger target area for via alignment, reducing the precision requirements for via-to-interconnect alignment while enabling smaller metal interconnect sizes and reduced bump pitch for higher connection density
Data Source
AI summary
Package substrate with metallization layer(s) that includes an additional metal pad layer to facilitate reduced via size for reduced bump pitch, and related integrated circuit (IC) packages and fabrication methods. An additional metal pad(s) is provided in an insulating layer of a metallization layer(s) of the package substrate in which a via(s) is formed to reduce vertical connectivity distance between metal interconnects in adjacent metallization layers electrically coupled together by the via. This can reduce the aspect ratio and size of the via thereby allowing metal interconnects that are electrically coupled to the via to also be reduced in size (e.g., width) while still supporting an aligned, low resistance connection between the via(s) and the metal interconnects. Being able to reduce the size (e.g., width) of the metal interconnects can reduce bump pitch of the package substrate, which can facilitate a higher density of die/bump connections to the package substrate.