CMP Slurry for Barrier Removal Polishing
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) processes face challenges in efficiently removing barriers from ultra-low k dielectric films while maintaining controlled copper removal rates and minimizing surface roughness, especially with the introduction of low-k and ultra-low k dielectric materials in ultra-large-scale-integrated circuits (ULSIs).
Innovation Solution
An aqueous slurry comprising specific concentrations of oxidizing agents, abrasive particles, polyvinyl pyrrolidone, phosphorus-containing compounds, and inhibitors is used for chemical mechanical polishing, with a pH range of 8 to 12, to enhance copper removal rates and maintain low k and ultra-low k dielectric film integrity, reducing static etch and surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP processes are used to remove barriers from ultra-low k dielectric films, then barrier removal is achieved, but copper removal rate is insufficient and surface roughness increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific oxidizing agents (potassium permanganate, ammonium persulfate, hydrogen peroxide) at controlled concentrations (0.01-25 wt%, 0.05-15 wt%, 0.1-10 wt% respectively), along with phosphorus-containing compounds (0.001-5 wt%) and copper inhibitors (0.01-10 wt%). These parameter changes enable enhanced barrier removal rates while maintaining controlled copper removal and reduced surface roughness through optimized chemical interactions during the polishing process
Solution Approach 2:
The invention creates a composite slurry system that combines multiple functional components: oxidizing agents for barrier layer removal, phosphorus-containing compounds for copper removal rate enhancement, azole inhibitors for static etch prevention, polyvinyl pyrrolidone for low k dielectric specificity, and abrasive particles. This composite formulation allows simultaneous achievement of high barrier removal rate, controlled copper removal, and minimized surface roughness through synergistic interactions among the components
2Manufacturing precision
If polyvinyl pyrrolidone amount is adjusted to control tantalum nitride and CDO removal rates, then barrier to dielectric removal ratio is optimized, but copper removal rate becomes inadequate
Solution Approach 1:
The patent merges multiple functional additives into a single slurry formulation: phosphorus-containing compounds (0.001-5 wt%) are combined with polyvinyl pyrrolidone (0.001-3 wt%) and copper inhibitors (0.01-10 wt%). This combination allows the slurry to simultaneously achieve optimized barrier-to-dielectric removal ratio through PVP control while enhancing copper removal rate through the synergistic action of phosphorus compounds and oxidizing agents, eliminating the trade-off present in previous formulations
3Productivity
If aggressive cleaning is performed after CMP, then copper removal is enhanced, but low k and ultra-low k dielectric film integrity is compromised
Solution Approach 1:
The patent applies preliminary action by incorporating copper inhibitors (azole compounds at 0.01-10 wt%) and phosphorus-containing compounds (0.001-5 wt%) into the CMP slurry formulation before the polishing process. These additives pre-establish protective mechanisms that prevent excessive copper removal and protect dielectric film integrity during and after polishing, eliminating the need for aggressive post-CMP cleaning that would compromise film integrity
Solution Approach 2:
The phosphorus-containing compounds (0.001-5 wt%) and azole inhibitors (0.01-10 wt%) act as intermediary substances that mediate between the oxidizing agents and the copper/dielectric materials. These intermediaries control the chemical reactions to achieve enhanced copper removal while protecting low k and ultra-low k dielectric films from damage, allowing effective cleaning without compromising film integrity
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 slurry effectively increases copper removal rates while maintaining stable low k and ultra-low k dielectric film removal rates, improving surface roughness and facilitating cleaning without adverse impacts on the wafer's surface, thus addressing the complexities of CMP processes in ULSIs.
Implementation Method 1
0.01 to 25 weight percent oxidizing agent
Implementation Method 2
0.1 to 50 weight percent abrasive particles
Implementation Method 3
0.01 to 10 weight percent inhibitor for decreasing static etch of the copper interconnects
Data Source
AI summary
The aqueous slurry is useful for chemical mechanical polishing semiconductor substrates having copper interconnects. The aqueous slurry includes by weight percent, 0.01 to 25 oxidizing agent, 0.1 to 50 abrasive particles, 0.001 to 3 polyvinyl pyrrolidone, 0.01 to 10 inhibitor for decreasing static etch of the copper interconnects, 0.001 to 5 phosphorus-containing compound for increasing removal rate of the copper interconnects, 0.001 to 10 complexing agent formed during polishing and balance water; and the aqueous slurry has a pH of at least 8.