CMP Slurry with N-Oxide Inhibitor for SiGe FinFET Planarization
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) processes for silicon-germanium (SiGe) finFETs face challenges in achieving high germanium to oxide removal selectivity while minimizing metal recess formation, leading to poor device performance due to recesses in the germanium channel regions.
Innovation Solution
A CMP slurry composition is developed, comprising an oxidant with one or more oxygen molecules and a nitrogen-oxide etching inhibitor, which reduces the rate of metal and dielectric material removal, providing a high selectivity for germanium to oxide removal with a low rate of metal recess formation, thereby enhancing the planarity and performance of SiGe finFETs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurry is used to remove germanium, then germanium removal rate is achieved, but metal recess formation increases and selectivity to oxide is poor
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific additives including chelating agents (e.g., EDTA, DTPA), complexing agents (e.g., ammonia, amine compounds), and surfactants (e.g., nonionic surfactants). These parameter changes alter the chemical reactivity of the slurry to achieve high germanium removal rates while suppressing metal recess formation and improving oxide selectivity.
Solution Approach 2:
The patent employs a composite slurry formulation combining multiple functional components: abrasive particles (e.g., colloidal silica, alumina), oxidants (e.g., hydrogen peroxide), chelating agents, complexing agents, and surfactants. This composite material approach creates synergistic effects that simultaneously achieve high germanium removal, minimal metal recess, and improved oxide selectivity that cannot be achieved with single-component slurries.
2Shape
If CMP process removes metal layer, then planarization is achieved, but selectivity between metal and oxide removal is poor
Solution Approach 1:
The patent adjusts chemical parameters of the slurry including pH control (using buffers like ammonium hydroxide), oxidant concentration (hydrogen peroxide at controlled levels), and additive ratios. These parameter modifications enable the slurry to selectively interact with germanium while preserving oxide layers, achieving both planarization and high selectivity.
Solution Approach 2:
The patent introduces intermediary substances such as chelating agents (EDTA, DTPA) and complexing agents (ammonia, amine compounds) that mediate between the abrasive/oxidant system and the germanium metal. These intermediaries form complexes with germanium ions, enhancing selective germanium removal while protecting oxide surfaces from excessive etching.
3Productivity
If oxidant concentration is increased to improve germanium removal, then removal rate increases, but metal recess formation worsens
Solution Approach 1:
The patent uses chelating agents and complexing agents as intermediaries that modulate the action of oxidants on germanium. These intermediaries control the oxidation process by forming stable complexes with germanium ions, preventing excessive oxidation that leads to metal recess while maintaining high removal rates through enhanced chemical reactivity.
Solution Approach 2:
The patent optimizes oxidant concentration parameters by combining moderate oxidant levels with enhanced chelating/complexing agent concentrations. This parameter combination achieves high germanium removal through improved chemical complexation rather than relying solely on high oxidant concentration, thereby avoiding metal recess formation.
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 CMP slurry achieves a high germanium to oxide removal selectivity, reducing metal recess formation and improving the structural integrity and performance of SiGe finFETs by selectively removing excess germanium without significantly affecting the oxide layer, thus ensuring better device performance.
Implementation Method 1
The CMP slurry composition comprises an oxidant and an etching inhibitor
Implementation Method 2
The etching inhibitor comprises a nitrogen-oxide compound having a chemical formula of R1R2R3N+—O−
Implementation Method 3
A workpiece is then brought into contact with the pad, causing the rotating platen to planarize the workpiece
Data Source
AI summary
The present disclosure relates to a chemical mechanical polishing (CMP) slurry composition that provides for a high metal to dielectric material selectivity along with a low rate of metal recess formation. In some embodiments, the disclosed slurry composition has an oxidant and an etching inhibitor. The oxidant has a compound with one or more oxygen molecules. The etching inhibitor has a nitrogen-oxide compound. The etching inhibitor reduces the rate of metal and dielectric material (e.g., oxide) removal, but does so in a manner that reduces the rate of dielectric material removal by a larger amount, so as to provide the slurry composition with a high metal (e.g., germanium) to dielectric material removal selectivity and with a low rate of metal recess formation.