Silicon Nitride CMP Slurry for High SiN/TEOS Selectivity
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Solution Overview
Problem
Current CMP processes face challenges in achieving high SiN removal rates while maintaining low TEOS removal rates, leading to low SiN:TEOS removal rate selectivity and surface scratches during semiconductor polishing.
Innovation Solution
A polishing composition comprising anion-modified silica with sulfonic acid groups, a substituted 5- or 6-membered heterocyclic SiN removal rate enhancer, and a pH adjusting agent, formulated to operate within a specific pH range of 4 to 6, providing electrical conductivity from greater than zero to 0.25 mS/cm and achieving a SiN:TEOS removal rate ratio of at least 40.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polishing compositions are used to rapidly remove silicon nitride, then SiN removal rate is improved, but TEOS removal rate increases uncontrollably
Solution Approach 1:
The patent applies parameter changes by carefully controlling the pH of the polishing composition within a specific range (approximately 2.0 to 4.0) and adjusting electrical conductivity (greater than zero to 0.25 mS/cm). These parameter adjustments create optimal conditions for selective SiN removal while suppressing TEOS removal, achieving both high productivity and manufacturing precision simultaneously
Solution Approach 2:
The patent uses composite materials by combining anion-modified silica abrasive particles with specific heterocyclic compounds (such as triazoles or imidazoles) that act as SiN removal rate enhancers. This composite formulation creates a synergistic effect where the abrasive provides mechanical removal and the heterocyclic compounds provide chemical enhancement specifically for SiN, achieving high removal rates with improved selectivity
2Productivity
If polishing speed is increased to improve throughput, then productivity is improved, but surface scratches occur
Solution Approach 1:
The patent applies parameter changes by controlling the pH within a specific range (2.0 to 4.0) and electrical conductivity (greater than zero to 0.25 mS/cm), which optimizes the chemical-mechanical interaction to achieve high removal rates while minimizing surface damage and scratches
Solution Approach 2:
The patent partially replaces purely mechanical polishing with a chemical-mechanical process by incorporating heterocyclic compounds that chemically enhance SiN removal. This substitution allows for higher effective polishing speeds without the surface damage typically associated with increased mechanical polishing intensity
3Productivity
If heat is applied to remove silicon nitride layer, then removal rate is improved, but process complexity and energy consumption increase
Solution Approach 1:
The patent replaces thermal processing with a chemical-mechanical polishing approach using pH-controlled slurries and heterocyclic compounds. This substitution eliminates the need for additional heating equipment and process controls, reducing device complexity while achieving high SiN removal rates through chemical enhancement combined with mechanical abrasion
Solution Approach 2:
The patent changes the approach from thermal energy input to chemical energy input by adjusting pH and electrical conductivity parameters of the polishing slurry. This parameter change enables high removal rates through chemical reactions rather than thermal processes, simplifying the overall process
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 composition enhances SiN removal rates while suppressing TEOS removal rates, thereby improving the selectivity and reducing surface scratches, thereby enhancing semiconductor polishing efficiency and throughput.
Implementation Method 1
Chemical mechanical polishing (CMP) is a process in which material is removed from a surface of a substrate
Implementation Method 2
CMP involves applying a slurry to the surface of the substrate or a polishing pad that polishes the substrate. This process achieves both the removal of unwanted material and planarization of the surface
Implementation Method 3
a SiN removal rate enhancer, wherein the SiN removal rate enhancer is a substituted 5- or 6-membered heterocycle, wherein the heterocyclic ring comprises at least two nitrogen atoms and the heterocycle is substituted with at least one group selected from —NH2 and —SH
Implementation Method 4
a pH adjusting agent, and water, combined in specified amounts to provide a specific electrical conductivity and high SiN:TEOS removal rate selectivity
Implementation Method 5
the polishing composition has a pH from about 4 to about 6... providing electrical conductivity from greater than zero to 0.25 mS/cm and achieving a SiN:TEOS removal rate ratio of at least 40
Data Source
AI summary
The present disclosure relates to relates to silicon nitride (SiN) chemical-mechanical polishing (CMP) compositions with SiN removal rate enhancers. The SiN CMP compositions increase the SiN polishing rate while suppressing the tetratethylorthosilicate (TEOS) polishing rate, thus providing a high SiN/TEOS selectivity ratio and reducing any defects on the surfaces of polished substrates.