Two-Stage Electroplating for Via Hole Filling
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Solution Overview
Problem
The existing methods for forming conductive structures with via plugs in three-dimensional semiconductor packaging are inefficient, leading to long processing times and high production costs due to the need for multiple plating steps and excessive metal deposition outside via holes, which results in defects and increased costs.
Innovation Solution
A method involving two-stage electroplating with optimized plating conditions, including the use of additives and mechanical stirring, to selectively fill via holes with copper while minimizing deposition on the substrate surface, and a plating apparatus with a bubble supply system to promote uniform plating solution flow and reduce surface deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electroplating is used to fill via holes, then via holes can be filled with copper, but excessive metal deposition occurs on the substrate surface leading to defects and increased costs
Solution Approach 1:
The patent applies local quality by using a resist pattern that selectively covers specific areas of the substrate, allowing copper deposition only in the via hole regions while preventing deposition on the surrounding substrate surface. This localized approach ensures precise filling without excessive metal deposition elsewhere.
Solution Approach 2:
The patent employs preliminary action by forming a resist pattern before electroplating. This resist pattern pre-defines the deposition areas, ensuring that copper is deposited only where needed (in via holes) and not on the substrate surface, thereby preventing excessive metal deposition before it occurs.
2Manufacturing precision
If multiple plating steps are used to form conductive structures, then via holes and electrode pads can be formed, but processing time increases leading to reduced productivity
Solution Approach 1:
The patent merges the formation of via plugs and electrode pads into a single electroplating step. By using a resist pattern that defines both via hole openings and electrode pad positions, the process simultaneously forms both conductive structures in one plating operation, eliminating the need for separate plating steps and reducing processing time.
Solution Approach 2:
The resist pattern serves multiple functions: it defines via hole openings for copper filling, defines electrode pad positions for copper deposition, and prevents deposition in unwanted areas. This multi-functionality allows a single electroplating step to achieve what previously required multiple steps, thereby increasing productivity.
3Ease of manufacture
If electroplating is performed without resist pattern, then process is simpler, but metal deposits on entire substrate surface causing defects
Solution Approach 1:
The resist pattern creates local quality differences across the substrate surface, allowing electroplating to proceed with high deposition control. Areas covered by resist prevent deposition, while exposed via hole regions allow selective copper filling, and exposed pad regions allow electrode pad formation, thus preventing unwanted surface deposition while maintaining process feasibility.
4Ease of manufacture
If plating solution is not stirred, then process is simpler, but uniformity of plated film decreases leading to defects
Solution Approach 1:
The patent uses hydraulic principles by circulating the plating solution through the electroplating bath. This circulation ensures uniform distribution of copper ions throughout the solution, maintaining consistent deposition rates across all via holes and electrode pads, thereby achieving high plated film uniformity while keeping the process relatively simple.
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 significantly reduces processing time, increases productivity, and achieves high in-plane uniformity of the plated film, allowing for defect-free filling of via holes with minimal extra metal film on the surface, thus lowering production costs and enhancing the efficiency of three-dimensional packaging.
Implementation Method 1
a plating solution stirring section, disposed between the anode and the substrate held by the substrate holder and immersed in the plating solution, for stirring the plating solution in the plating tank
Implementation Method 2
a bubble supply section for supplying bubbles to the plating solution facing a surface to be plated of the substrate held by the substrate holder and immersed in the plating solution
Implementation Method 3
carrying out first electroplating under first plating conditions, using the conductive film as a feeding layer, thereby filling a first plated film into the via holes
Data Source
AI summary
A method can form a conductive structure, which is useful for three-dimensional packaging with via plugs, in a shorter time by shortening the conventional long plating time that is an impediment to the practical use of electroplating. The method includes forming a conductive film on an entire surface, including interior surfaces of via holes, of a substrate having the via holes formed in the surface; forming a resist pattern at a predetermined position on the conductive film; carrying out first electroplating under first plating conditions, using the conductive film as a feeding layer, thereby filling a first plated film into the via holes; and carrying out second electroplating under second plating conditions, using the conductive film and the first plated film as a feeding layer, thereby allowing a second plated film to grow on the conductive film and the first plated film, both exposed in the resist openings of the resist pattern.