Post-CMP Cleaning via Gradient H2SO4-H2O2 Ratios
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Solution Overview
Problem
Conventional post-CMP cleaning methods are inadequate in removing nano-sized particles and residues from semiconductor wafers, leading to yield loss and defects due to the reattachment of particles to the substrate surface via Van der Waal forces and the difficulty in simultaneously optimizing the removal of slurry and organic polymer residues.
Innovation Solution
A post-CMP cleaning method involving sequential processes with varying ratios of sulfuric acid (H2SO4) to hydrogen peroxide (H2O2) solutions at different temperatures, where the volume ratios of H2SO4 to H2O2 vary gradiently and inversely with temperatures across multiple cleaning steps to effectively remove both slurry and polymer residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional post-CMP cleaning methods are used, then the cleaning process is simple and fast, but nano-sized particles and residues cannot be effectively removed and may reattach to the substrate surface
Solution Approach 1:
The cleaning process is divided into multiple sequential steps, each with specific H2SO4:H2O2 volume ratios and temperature conditions. The first step uses a higher H2SO4 ratio for slurry removal, while subsequent steps use higher H2O2 ratios for organic residue removal, with temperatures varying from room temperature to elevated temperatures to optimize particle detachment and prevent reattachment.
Solution Approach 2:
The patent systematically varies critical parameters including H2SO4:H2O2 volume ratios (from 3:1 to 1:3), temperatures (from room temperature to 80°C), and exposure times across different cleaning steps. These parameter changes optimize the chemical reactions for different types of residues and prevent particle reattachment through controlled thermal energy input.
2Manufacturing precision
If higher concentrations of cleaning solutions are used, then particle removal effectiveness increases, but the risk of substrate damage and yield loss increases
Solution Approach 1:
The cleaning process uses dynamic, varying concentrations rather than static high concentrations. The H2SO4:H2O2 ratios are adjusted across different steps, and temperatures are modulated to provide sufficient cleaning power when needed while allowing gentle treatment during other phases, thereby preventing substrate damage while maintaining effective particle removal.
Solution Approach 2:
The patent employs periodic cycles of different chemical compositions and temperatures. Each cleaning step alternates between aggressive particle removal phases and gentler residue elimination phases, creating a rhythmic cleaning pattern that prevents substrate damage accumulation while maintaining continuous particle removal effectiveness.
3Manufacturing precision
If multiple cleaning steps with varying solutions are used, then both slurry and polymer residues are effectively removed, but the cleaning process time and complexity increase
Solution Approach 1:
The patent combines multiple cleaning functions into a unified sequential process where each step builds on the previous one. The H2SO4-based steps and H2O2-based steps are merged in a specific sequence to simultaneously address slurry removal, organic residue elimination, and particle reattachment prevention, achieving comprehensive cleaning without requiring separate independent processes.
Solution Approach 2:
The cleaning process maintains continuous useful action through sequential steps without idle transitions. Each cleaning step immediately follows the previous one with optimized timing, ensuring that the substrate surface is continuously treated with appropriate chemical environments. This continuous action maximizes cleaning efficiency while minimizing total process time compared to interrupted or batch-wise approaches.
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 defect levels by up to two orders of magnitude, ensuring complete removal of particles and preventing reattachment, thereby enhancing the cleanliness and yield of semiconductor wafers.
Implementation Method 1
a post CMP cleaning method involving sequential processes with varying ratios of sulfuric acid (H2SO4) to hydrogen peroxide (H2O2) solutions
Implementation Method 2
both slurries and polymer residue may be most effectively removed
Implementation Method 3
processes sequentially on the substrate using solutions of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) at different temperatures
Implementation Method 4
nano-sized particles may be more difficult to be removed because they may reattach to the substrate surface due to Van der Waal forces
Data Source
AI summary
A method for post chemical mechanical polishing clean is provided in the present invention, which include the steps of providing a substrate, performing a chemical mechanical polishing process, and performing a plurality of cleaning processes sequentially substrate using solutions of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) with different ratios and at different temperatures.