Copper Electroplating with Alternative Halides
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electroplating copper into small and large high aspect ratio features faces issues such as seams, voids, surface roughness, and slow process throughputs, particularly with thin seed layers and non-conformal seed coverage, which are exacerbated by conditions close to the suppressor's cloud point, and existing suppressor formulations are not robust enough to address these issues across a wide range of feature sizes.
Innovation Solution
Incorporating alternative halide ions like bromide and iodide ions into the copper electroplating solution, along with chloride ions, enhances adsorption and polarization, allowing for faster and void-free filling of features by establishing a stronger suppression gradient, especially in large features like Through Silicon Vias, thereby overcoming seed layer defects and improving nucleation density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If suppressor concentration is increased to improve suppression gradient, then suppression gradient is improved, but clouding occurs and suppressor distribution becomes unstable
Solution Approach 1:
The patent introduces alternative halide ions (bromide, iodide) as intermediary substances that mediate between the suppressor and the copper deposition process. These halide ions enhance suppressor adsorption and strengthen the suppression gradient without requiring increased suppressor concentration, thereby avoiding clouding and maintaining solution stability.
Solution Approach 2:
The patent changes the chemical composition parameters of the electroplating solution by adding alternative halide ions at specific concentrations (0.25-20 ppm). This parameter change modifies the adsorption characteristics and polarization behavior, enabling strong suppression gradients while maintaining suppressor distribution stability and avoiding clouding.
2Productivity
If electroplating rate is increased to improve productivity, then productivity is improved, but voids and seams occur due to insufficient suppression
Solution Approach 1:
Alternative halide ions serve as intermediaries that enhance suppressor adsorption strength and polarization, enabling the system to maintain strong suppression control even at higher electroplating rates. This resolves the contradiction by allowing high productivity while preventing voids and seams through improved suppressor effectiveness.
Solution Approach 2:
The patent creates a composite electroplating solution system combining chloride ions, alternative halide ions (bromide, iodide), and suppressor additives. This composite formulation synergistically enhances both suppression capability and electroplating rate, achieving high productivity with void-free filling and uniform copper deposition.
3Manufacturing precision
If suppressor adsorption is strengthened to prevent voids, then void-free filling is achieved, but electroplating rate decreases
Solution Approach 1:
The patent modifies the solution chemistry parameters by introducing alternative halide ions that change the adsorption kinetics and polarization characteristics. This enables strong suppressor adsorption for void-free filling while maintaining high electroplating rates, reversing the traditional trade-off between suppression strength and deposition speed.
Solution Approach 2:
The composite electroplating solution containing chloride ions, alternative halide ions, and suppressors works synergistically to achieve both strong suppression (void-free filling) and high electroplating rates. The alternative halide ions enhance suppressor effectiveness without sacrificing deposition speed, resolving the contradiction between precision and productivity.
4Productivity
If electroplating is performed at high current density to improve throughput, then throughput is improved, but polarization decreases and suppression becomes insufficient
Solution Approach 1:
The patent changes the electrochemical parameters of the solution by adding alternative halide ions, which increase polarization even at high current densities. This enables high throughput operation while maintaining effective suppression, as the halide ions enhance the polarization response that drives suppressor adsorption and control.
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 use of alternative halide ions in the electroplating solution significantly increases electroplating rates, reduces sidewall voids, and improves fill uniformity, enabling efficient copper deposition into features with marginal seed coverage and high aspect ratios, while maintaining high polarization and preventing issues like 'clouding' associated with stronger suppressor concentrations.
Implementation Method 1
Adding alternative halide ions, such as bromide ions and iodide ions, to a copper electroplating solution together with chloride ions accelerates and strengthens adsorption of a wide range of suppressors onto the processing surface
Implementation Method 2
electroplating copper onto the surface by passing an electrical current to fill the recessed features with copper
Implementation Method 3
electroplating copper onto the surface by passing an electrical current to fill the recessed features with copper
Implementation Method 4
suppressor molecules more easily diffuse the bottom of the features and a suppression gradient may be harder to establish than in smaller features
Data Source
AI summary
Methods, electroplating solution, and apparatuses for electroplating copper into a surface of a partially fabricated semiconductor substrate are provided. Electroplating solutions include copper ions, suppressor additives, chloride ions, and alternative halide ions, which include bromide ions and/or iodide ions. The concentration of the alternative halide ions in the solution may be between about 0.25 ppm and 20 ppm. Addition of the alternative halide ions at certain concentrations improves suppression properties of the solution over a range of feature sizes without a need to change suppressors.