Dual-Stage Electroless Plating for TSV Film Uniformity
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Solution Overview
Problem
In the context of three-dimensional mounting technologies, such as TSV (through-silicon-via) manufacturing, existing plating methods face challenges in uniformly forming barrier and seed films within recesses of varying depths and diameters due to non-uniform concentration distribution of plating liquids, leading to inconsistent film thickness across the inner surfaces of recesses.
Innovation Solution
The proposed solution involves an electroless plating method using two distinct plating liquids with different additive concentrations, where the first plating liquid forms a discontinuous film or particle shape on the substrate surface, and the second plating liquid, with a higher additive concentration, is supplied at specific speeds to promote uniform growth on the inner surfaces of recesses, ensuring consistent film thickness across the entire substrate and recess surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single plating liquid is supplied to form a plating layer on the substrate and inner surfaces of recesses, then the process is simple, but the concentration distribution of the plating liquid becomes non-uniform, leading to non-uniform film thickness
Solution Approach 1:
The plating process is segmented into two distinct stages: first forming a discontinuous film using a first plating liquid, then forming a continuous plating layer using a second plating liquid. This segmentation allows each stage to address specific requirements - the first stage provides initial coverage while the second stage ensures uniform thickness, thereby resolving the contradiction between film uniformity and process complexity.
Solution Approach 2:
Different plating liquids with different additive concentrations are used for different regions and stages of the plating process. The first plating liquid forms a discontinuous film suitable for initial coverage, while the second plating liquid with higher additive concentration forms a uniform continuous layer. This local differentiation of plating conditions enables uniform film thickness while maintaining process feasibility.
2Manufacturing precision
If the substrate is rotated at high speed to improve plating liquid distribution, then surface coverage is improved, but plating liquid cannot sufficiently reach the lower portions of deep recesses
Solution Approach 1:
The first plating process is performed as a preliminary action to form a discontinuous film on the substrate surface and inner surfaces of recesses. This initial film provides a foundation that facilitates subsequent plating liquid penetration and uniform deposition in the second stage, enabling better overall film uniformity while maintaining operational efficiency.
Solution Approach 2:
The plating process uses periodic action by alternating between two distinct plating stages with different liquids and conditions. The first plating liquid is supplied to form a discontinuous film, then the second plating liquid is supplied to form a uniform continuous layer. This periodic application of different plating conditions ensures both surface coverage and deep recess penetration.
3Reliability
If a barrier film and seed film are formed on inner surfaces of recesses with high aspect ratios, then diffusion suppression and adhesion improvement are achieved, but non-uniform film thickness occurs due to plating liquid concentration distribution
Solution Approach 1:
The formation of barrier film and seed film is segmented into two plating stages. The first stage forms a discontinuous film that provides initial coverage, while the second stage forms a uniform continuous layer that ensures consistent thickness. This segmentation allows both the barrier and seed film functions to be achieved with uniform thickness, improving reliability while maintaining precision.
Solution Approach 2:
The plating process changes parameters between stages by using different plating liquids with different additive concentrations. The first plating liquid creates a discontinuous film suitable for initial barrier formation, while the second plating liquid with higher additive concentration ensures uniform continuous coverage. This parameter change enables both high-quality film formation and uniform thickness on high aspect ratio recesses.
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 uniform formation of plating layers on both the substrate surface and inner recess surfaces, improving the thickness uniformity and consistency of barrier and seed films, thereby enhancing the reliability of three-dimensional mounting technologies.
Implementation Method 1
a first plating process of supplying a first plating liquid to the substrate and forming a first plating layer on a surface of the substrate
Implementation Method 2
a second plating process of supplying a second plating liquid to the substrate and forming a second plating layer on the first plating layer
Data Source
AI summary
A Plating method includes a first plating process S21 of supplying a first plating liquid to a substrate 2 having a recess 12 and forming a first plating layer 13; and a second plating process of supplying a second plating liquid to the substrate 2 and forming a second plating layer 14 on the first plating layer 13 after the first plating process S21. Here, a concentration of an additive contained in the first plating liquid is different from that in the second plating liquid. The first plating process S21 includes a process of forming the first plating layer of a discontinuous film or a particle shape on the substrate 2 by rotating the substrate 2 at a first speed and a process of rotating the substrate 2 at a second speed and at a third speed repeatedly.