CMP Polishing Composition for Selective Oxide Over Nitride Removal
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Solution Overview
Problem
Conventional CMP slurries struggle with high silicon nitride removal rates and low selectivity during shallow trench isolation (STI) processes, leading to increased defects and inefficiencies in semiconductor manufacturing.
Innovation Solution
Aqueous polishing compositions comprising an abrasive, a nitride removal rate reducing agent, an acid or base, and a metal corrosion inhibitor, with a pH range of 2 to 4.5, that selectively polish silicon oxide at high rates while minimizing silicon nitride removal, using silica abrasives to achieve low defectivity and high selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurries are used to achieve high material removal rate of silicon oxide, then productivity is improved, but silicon nitride removal rate increases leading to loss of stop-on layer
Solution Approach 1:
The invention changes the chemical parameters of the CMP slurry by introducing a nitride removal rate reducing agent that selectively inhibits silicon nitride removal while maintaining silicon oxide removal. The agent modifies the chemical interaction between the slurry and the materials being polished, achieving differential removal rates through chemical parameter adjustment rather than mechanical force alone.
Solution Approach 2:
The nitride removal rate reducing agent acts as an intermediary substance that mediates between the abrasive particles and the silicon nitride layer. This agent adsorbs onto the silicon nitride surface, forming a protective layer that prevents direct interaction between the abrasive and the stop-on layer, thereby reducing its removal rate while allowing silicon oxide to be removed at high rates.
2Productivity
If conventional CMP slurries are used to increase material removal rate, then productivity is improved, but selectivity between silicon oxide and silicon nitride decreases
Solution Approach 1:
The invention achieves high selectivity by changing the chemical composition parameters of the slurry, specifically adding the nitride removal rate reducing agent at controlled concentrations (0.1-10 wt%). This chemical parameter modification creates a selective environment where silicon oxide is removed rapidly while silicon nitride removal is suppressed, achieving selectivity ratios greater than 10:1.
Solution Approach 2:
The nitride removal rate reducing agent provides local quality enhancement by specifically targeting the silicon nitride-silicon oxide interface. The agent preferentially adsorbs onto silicon nitride surfaces, creating a localized protective effect only where needed, while leaving silicon oxide surfaces exposed to high-rate removal mechanisms.
3Productivity
If high material removal rates are achieved, then productivity is improved, but defects and surface roughness increase
Solution Approach 1:
The nitride removal rate reducing agent serves as a protective intermediary that prevents direct mechanical contact between abrasive particles and the silicon nitride stop-on layer. This mediation reduces mechanical damage, scratching, and surface roughness while still allowing efficient removal of silicon oxide through chemical-mechanical mechanisms.
Solution Approach 2:
The additive provides beforehand cushioning by forming a protective adsorbed layer on the silicon nitride surface before the polishing action occurs. This pre-formed protective layer cushions against mechanical impacts from abrasive particles, preventing surface damage and defect formation while maintaining the high removal rate for silicon oxide.
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 compositions provide high selectivity in material removal rates for silicon oxide over silicon nitride, reducing defects and surface roughness, and maintaining stability across various polish conditions, enhancing device yield and integration schemes.
Implementation Method 1
The nitride removal rate reducing agent includes a hydrophobic portion and a hydrophilic portion... selectively polish silicon oxide at high rates while minimizing silicon nitride removal
Implementation Method 2
aqueous polishing compositions comprising an abrasive... that selectively polish silicon oxide at high rates
Implementation Method 3
Chemical Mechanical Polishing/Planarization (CMP) is a powerful technology
Implementation Method 4
The polishing composition has a pH ranging from 2 to 4.5... including an acid or a base
Implementation Method 5
a metal corrosion inhibitor... that selectively polish silicon oxide at high rates while minimizing silicon nitride removal
Data Source
Figure 1(a)~1(d)
Figure 2
Figure 3
AI summary
This disclosure relates to a polishing composition that includes at least one abrasive; at least one nitride removal rate reducing agent, an acid or a base; and water. The at least one nitride removal rate reduce agent can include a hydrophobic portion containing a C4 to C40 hydrocarbon group; and a hydrophilic portion containing at least one group selected from the group consisting of a sulfinite group, a sulfate group, a sulfonate group, a carboxylate group, a phosphate group, and a phosphonate group; in which the hydrophobic portion and the hydrophilic portion are separated by zero to ten alkylene oxide groups. The polishing composition can have a pH of from about 2 to about 6.5.