CMP Slurry RRO Compounds Stabilize Removal Rate at Elevated Temperatures
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes experience significant removal rate variations due to temperature fluctuations on the wafer and pad surfaces, leading to defects such as 'dish' and 'erosion' during copper polishing, as reaction rates and pH levels are sensitive to temperature changes.
Innovation Solution
The use of reaction rate optimizing (RRO) compounds in CMP compositions, including buffering agents like potassium sulfates and polymeric solvents, along with corrosion inhibitors and oxidizers, to stabilize removal rates within a 10% variation over a 40-65°C temperature range, optimizing oxidation, complexation, and particle dissolution reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP compositions are used, then high removal rate can be achieved, but removal rate variation increases due to temperature sensitivity
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the CMP slurry, specifically incorporating buffering agents (potassium sulfates) and polymeric solvents that stabilize pH and reaction rates across temperature variations. This allows the system to maintain consistent removal rates despite temperature fluctuations during the polishing process.
Solution Approach 2:
The patent uses buffering agents and polymeric solvents as intermediary substances that mediate between temperature variations and chemical reaction rates. These intermediaries absorb temperature-induced pH changes and prevent them from affecting the overall removal rate uniformity, thereby resolving the contradiction between high removal rate and removal rate uniformity.
2Speed
If temperature increases during CMP, then chemical reaction rates increase, but removal rate uniformity deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the slurry by adding buffering agents that maintain stable pH levels across temperature changes. This stabilization prevents temperature-induced acceleration of chemical reactions from causing non-uniform removal rates, thereby maintaining both reaction efficiency and uniformity.
Solution Approach 2:
The patent employs buffering agents and polymeric solvents as preemptive cushioning mechanisms that are built into the slurry formulation before the CMP process begins. These additives cushion against temperature-induced pH variations and reaction rate fluctuations, ensuring uniform removal rates even when temperatures rise during polishing.
3Power
If pH levels are sensitive to temperature changes, then chemical reactions are enhanced, but process stability decreases
Solution Approach 1:
The patent modifies the pH stability parameters of the slurry by incorporating buffering agents (potassium sulfates) and polymeric solvents. These additives change the pH-resistance parameter of the system, allowing chemical reactions to remain active while pH levels stay stable despite temperature fluctuations, thereby enhancing both reaction power and process reliability.
Solution Approach 2:
The buffering agents and polymeric solvents act as intermediaries that decouple pH levels from temperature changes. These intermediaries absorb the temperature-induced pH variations, allowing chemical reactions to proceed at enhanced rates while the overall process remains stable and predictable.
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 RRO compounds ensure robust and stable polishing processes with minimal removal rate variation, reducing defects and maintaining uniformity across the wafer surface by stabilizing chemical reactions and pH levels, even with temperature changes.
Implementation Method 1
The use of reaction rate optimizing (RRO) compounds in CMP compositions, including buffering agents like potassium sulfates and polymeric solvents, along with corrosion inhibitors and oxidizers, to stabilize removal rates within a 10% variation over a 40-65°C temperature range
Implementation Method 2
optimizing oxidation, complexation, and particle dissolution reactions
Implementation Method 3
CMP processes, which are friction and wear processes, generate heat
Data Source
AI summary
CMP compositions providing stable and robust polishing performance at elevated pad or wafer surface temperatures are disclosed, as well as methods for use thereof. The compositions of the disclosure include reaction rate optimizing (RRO) compounds that optimize various chemical reactions occurring in the slurry chemistry at elevated polishing temperatures on the wafer surface, such that removal rate variation within an individual wafer is <10%.