Pulse Plating Flow Control for Uniform Film Thickness
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Solution Overview
Problem
Existing plating apparatuses face challenges in achieving uniform thickness of plating films, particularly in locations with varying opening diameters and densities, due to uneven distribution of accelerator molecules during pulse plating processes.
Innovation Solution
An apparatus with a controlled flow path system that regulates the supply of plating liquid in response to reverse current pulses, reducing or stopping the flow during specific time periods to adjust the re-adsorption of accelerator molecules, thereby enhancing film thickness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the plating liquid is continuously supplied during reverse current pulse, then the metal ion supply to substrate is maintained, but the accelerator molecules diffuse away from the plating film surface causing non-uniform plating film thickness
Solution Approach 1:
The patent applies periodic action by stopping the plating liquid supply during the reverse current pulse period and resuming it during the forward current period. This periodic on/off flow control allows accelerator molecules to remain concentrated at the plating film surface during reverse pulses (improving uniformity) while still supplying metal ions during forward pulses (maintaining plating rate).
Solution Approach 2:
The patent implements preliminary action by pre-stopping the plating liquid supply before the reverse current pulse begins. This ensures that accelerator molecules are already retained at the plating film surface before the reverse pulse causes desorption, preventing their diffusion away and ensuring uniform re-adsorption during the subsequent forward pulse.
2Manufacturing precision
If the plating liquid supply is stopped during reverse current pulse, then the accelerator molecules are retained for uniform re-adsorption, but the metal ion supply to substrate is interrupted
Solution Approach 1:
The patent uses periodic action by synchronizing the plating liquid flow stop with the reverse current pulse and resuming flow with the forward current. This timing ensures that metal ion supply is interrupted only during reverse pulses (when no plating occurs anyway) while maintaining full supply during forward pulses (when plating actually happens), thus preserving overall productivity.
Solution Approach 2:
The patent implements feedback by using the reverse current pulse signal itself to control the flow valve. The reverse current pulse serves as both the plating process step and the control signal for flow regulation, creating a self-coordinated system where the plating regime directly controls the liquid supply timing.
3Manufacturing precision
If the flow path system is simplified without reverse flow control, then the device complexity is reduced, but the uniformity of plating film thickness cannot be improved
Solution Approach 1:
The patent introduces an intermediary component - an automated flow control valve - that mediates between the plating power supply (controlling reverse/forward currents) and the plating liquid reservoir. This valve translates electrical pulse signals into corresponding liquid flow actions, enabling precise flow timing without complex mechanical flow path design.
Solution Approach 2:
The patent replaces a potentially complex mechanical flow control system with an automated valve controlled by electrical signals from the plating power supply. This substitution uses electrical control (already present for current regulation) to manage liquid flow, simplifying the overall system by unifying control mechanisms.
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 system effectively compensates for variations in film thickness by controlling the flow of plating liquid, resulting in uniform plating film heights across different substrate locations.
Implementation Method 1
applies a voltage between the substrate and the anode to make a flow of electric current and thereby form an electroplating film on the exposed surface of the substrate
Implementation Method 2
cause molecules of an accelerator to be once desorbed from the surface of a plating film
Implementation Method 3
a difference in density of the re-adsorbed molecules of the accelerator by location is attributed to a difference in the degree of diffusion of the desorbed molecules of the accelerator
Data Source
AI summary
An object is to improve the uniformity of a plating film thickness in a variety of different types of apparatuses for plating that perform pulse plating. There is provided an apparatus for plating, comprising: a first plating tank configured to plate a substrate by application of a forward direction current and a reverse current pulse between the substrate and an anode; a first flow path connected with a reservoir tank and configured to discharge a plating liquid from the reservoir tank; a second flow path connected with the first flow path and with the first plating tank and configured to supply the plating liquid to the first plating tank; a third flow path connected with the first flow path and configured to cause the plating liquid discharged from the reservoir tank to go around the first plating tank and to be returned to the reservoir tank or to be discharged to a discharge port; a first valve configured to regulate a flow of the plating liquid between the second flow path and the third flow path; and a control module configured to control the first valve according to a timing of the reverse current pulse during plating of the substrate, such as to regulate the flow of the plating liquid between the second flow path and the third flow path and to decrease a supply of the plating liquid to the second flow path to be less than a supply of the plating liquid in an interval of the forward direction current or to stop the supply of the plating liquid to the second flow path.