STI CMP Slurry Selectivity via Ceria and Polyols
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Solution Overview
Problem
Existing Shallow Trench Isolation (STI) chemical mechanical polishing compositions fail to effectively reduce SiN film removal rates and oxide trench dishing, leading to non-uniform trench oxide loss and poor transistor isolation, and lack a method to predict patterned wafer performance from blanket wafer results.
Innovation Solution
The development of STI CMP polishing compositions using ceria-coated inorganic oxide particles and specific chemical additives, such as non-ionic organic surfactants and polyols, which suppress SiN film removal rates and reduce oxide trench dishing, while maintaining high selectivity for silicon dioxide over silicon nitride, and employing a down force offset selectivity method to predict patterned wafer performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional STI CMP polishing compositions are used, then silicon dioxide removal rate is maintained, but silicon nitride film removal rate is too high and oxide trench dishing is severe
Solution Approach 1:
The patent changes the chemical composition parameters of the polishing slurry by incorporating specific organic compounds with carboxylic acid functional groups and additional functional groups (amines or halides). This chemical parameter modification selectively suppresses silicon nitride removal while maintaining silicon dioxide removal, thereby reducing oxide trench dishing and improving trench uniformity without excessively increasing SiN removal rate
Solution Approach 2:
The polishing composition uses a composite approach by combining abrasive particles with specially designed organic molecules that have multiple functional groups. The carboxylic acid group provides chemical interaction with the materials being polished, while the amine or halide groups enhance selectivity. This composite chemical-mechanical system achieves differential removal rates that improve oxide trench uniformity while controlling SiN film loss
2Productivity
If polishing pressure is increased to improve planarization, then oxide removal rate increases, but silicon nitride removal rate increases even more, worsening selectivity
Solution Approach 1:
The patent modifies the chemical environment parameters by introducing organic compounds with specific functional groups that create a chemically selective polishing atmosphere. This allows the mechanical polishing action to differentiate between materials, maintaining high oxide removal rates even at increased pressures while selectively suppressing nitride removal, thereby preserving selectivity across a wider pressure range
3Productivity
If conventional polishing compositions are used, then high oxide removal rate is achieved, but trench oxide loss is non-uniform across the die
Solution Approach 1:
The patent applies local quality control by using organic compounds that create localized chemical environments during polishing. The multifunctional organic molecules interact differently with oxide in trench regions versus field regions, providing chemically assisted mechanical removal that maintains uniform oxide loss across the die while preserving high overall removal rates
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 achieve reduced SiN film removal rates, high oxide vs. nitride selectivity, and uniform oxide trench features, improving transistor isolation and enabling accurate prediction of patterned wafer performance from blanket wafer results.
Implementation Method 1
chemical mechanical polishing compositions
Implementation Method 2
abrasive particles
Implementation Method 3
exhibiting normal stress effects
Implementation Method 4
non-ionic organic surfactants
Data Source
AI summary
Shallow Trench Isolation (STI) chemical mechanical planarization (CMP) compositions, methods of using the composition and systems for using the composition are provided. The compositions comprise abrasive particles, and two different groups of chemical additives; a non-ionic organic surfactant molecule including polysorbate-type surfactants formed by the ethoxylation of the sorbitan and non-ionic organic molecules with multi hydroxyl functional groups in the same molecule. The compositions provide high silicon oxide removal rate (RR) and suppressed SiN removal rate (RR). A good pattern performance is provided by the compositions which offer desired silicon oxide RR at a reasonable DF and show high SiN RR suppression at an even higher DF from the blanket wafer data.