Plating Solution Leveler Control Using RDE Potential Reference Data
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Solution Overview
Problem
Existing semiconductor fabrication processes face challenges in achieving uniform conductor deposition across substrates with varying features, particularly due to the introduction of levelers in electroplating baths, which complicates the detection and control of suppressor and leveler concentrations, leading to topography variations and voids in interconnects.
Innovation Solution
A method and apparatus using a rotating disk electrode (RDE) and a control potentiostat to determine and adjust suppressor and leveler concentrations in the plating solution by comparing measured RDE potentials to reference data, ensuring the suppressor concentration meets a threshold before determining the leveler concentration, and adjusting the plating solution accordingly to achieve uniform deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If levelers are introduced in electroplating baths to improve deposition uniformity, then topography variations are reduced, but detection and control of suppressor and leveler concentrations becomes complicated
Solution Approach 1:
The patent segments the concentration determination process into two distinct stages: first determining suppressor concentration using reference data obtained in the absence of leveler, then determining leveler concentration using reference data obtained at a known suppressor concentration. This segmentation allows each component to be measured independently, resolving the complexity of detecting both concentrations simultaneously in the presence of levelers.
Solution Approach 2:
The patent applies preliminary action by first determining the suppressor concentration before determining the leveler concentration. The suppressor concentration is established as a known parameter first, which then serves as the basis for accurately determining the leveler concentration. This sequential approach simplifies the overall measurement process by breaking it into manageable steps.
2Manufacturing precision
If suppressor concentration is not properly controlled, then bottom-up fill is achieved, but topography variations and voids occur in interconnects
Solution Approach 1:
The patent implements feedback control by continuously monitoring suppressor and leveler concentrations through RDE potential measurements and adjusting the plating solution composition accordingly. The system uses measured RDE potentials to determine concentrations, compares them to target values, and makes real-time adjustments to maintain optimal suppressor and leveler levels, ensuring consistent interconnect fill quality without manual intervention.
Solution Approach 2:
The patent utilizes parameter changes by monitoring RDE potential as an indicator of suppressor and leveler concentrations. By tracking changes in RDE potential over time and comparing them to reference data, the system dynamically adjusts chemical parameters in the plating bath to maintain optimal deposition conditions, preventing topography variations and void formation.
3Measurement precision
If RDE potential is measured at multiple time points to determine both suppressor and leveler concentrations, then accurate composition control is achieved, but measurement time increases
Solution Approach 1:
The patent segments the measurement process into two efficient stages: first measuring RDE potential to determine suppressor concentration using reference data from suppressor-only solutions, then measuring RDE potential again to determine leveler concentration using reference data that accounts for the known suppressor level. This segmentation achieves accurate determination of both concentrations while minimizing total measurement time compared to exhaustive multi-parameter analysis.
Solution Approach 2:
The patent applies preliminary action by obtaining suppressor concentration first, which then serves as a known parameter for the subsequent leveler concentration determination. This sequential approach reduces the overall measurement time by eliminating the need for simultaneous multi-variable analysis, as each measurement builds on the previous result.
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 precise control of the plating solution composition, minimizing topography variations and ensuring void-free interconnects, thereby improving the uniformity and quality of conductor deposition on substrates with diverse features.
Implementation Method 1
determining a suppressor concentration of a suppressor in the plating solution in the analysis cell and a leveler concentration in the analysis cell by: comparing a measured rotating disk electrode (RDE) potential at a predetermined tune to reference data of RDE potential versus suppressor concentration or leveler concentration
Implementation Method 2
plating a semiconductor substrate using the plating solution in the bath reservoir after adjusting the plating solution in the bath reservoir
Data Source
AI summary
An apparatus and method of adjusting a plating solution are described. Suppressor is added to the plating solution until a comparison to reference data of an RDE potential taken at a first time during a constant current experiment indicates a threshold suppressor concentration is present. The amount of suppressor added to reach the threshold suppressor concentration is used to determine suppressor concentration of the solution. Another amount of suppressor is added to a new plating solution so that the new plating solution has a specific suppressor concentration. The RDE potential or slope of RDE potential change of the new plating concentration with the specific suppressor concentration taken at a second time during another constant current experiment is compared with the reference data to determine the leveler concentration. The suppressor and leveler concentrations of the original plating solution are adjusted before a semiconductor substrate is plated.