CMP Composition for SiC and SiN Removal Selectivity
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) technologies face challenges in achieving high removal rates while maintaining selectivity for semiconductor substrates, particularly for materials like silicon carbide (SiC), silicon nitride (SiN), and their doped variants, due to their hardness and chemical inertness, which complicates the removal of specific layers without damaging others.
Innovation Solution
A CMP composition comprising an abrasive, a chemical additive selected from piperazine derivatives, substituted morpholine derivatives, amino sulfonic acid derivatives, and their salts, along with a liquid carrier, pH buffering agent, surfactant, and biocide, with a pH range of 2.0 to 8.0, is used to enhance removal rates and selectivity by interacting with the substrate surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP compositions are used for polishing hard materials like SiC and SiN, then the polishing process can be performed, but the removal rate is insufficient due to the hardness and chemical inertness of these materials
Solution Approach 1:
The patent changes the chemical parameters of the CMP composition by introducing specific additives (chelating agents, oxidizing agents, acids) that can chemically interact with SiC and SiN. These parameter changes enable the composition to overcome the chemical inertness of these hard materials and achieve acceptable removal rates.
Solution Approach 2:
The patent uses a composite CMP composition containing multiple functional components: abrasives for mechanical removal, chelating agents for chemical complexation, oxidizing agents for surface oxidation, and acids for etching. This composite approach combines mechanical and chemical actions to effectively polish hard, chemically inert materials.
2Productivity
If aggressive polishing methods are used to increase removal rate, then productivity improves, but selectivity between different layers deteriorates
Solution Approach 1:
The patent introduces chemical additives as intermediaries that selectively interact with specific materials. The chelating agents, oxidizing agents, and acids act as mediators that preferentially react with certain layers (e.g., SiC or SiN) while having minimal effect on others (e.g., SiO2), thereby maintaining selectivity while achieving high removal rates.
Solution Approach 2:
The patent adjusts chemical parameters (pH, oxidation potential, chelating strength) to achieve selective removal. By carefully controlling these parameters, the composition can be tuned to remove specific layers at high rates while preserving underlying or overlying layers, thus resolving the contradiction between productivity and precision.
3Productivity
If strong chemical agents are used to enhance removal rate, then productivity improves, but damage to the substrate surface increases
Solution Approach 1:
The patent uses controlled amounts of chemical agents that are sufficient to achieve the desired removal rate but not excessive to cause damage. The composition achieves effective polishing through the synergistic action of multiple milder agents rather than one strong agent, preventing surface damage while maintaining productivity.
Solution Approach 2:
The patent optimizes the concentration and strength parameters of chemical agents to achieve the minimum effective level needed for high removal rates. By carefully controlling pH, oxidizing agent concentration, and chelating agent strength, the composition achieves effective polishing without causing excessive surface damage.
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 composition effectively enhances removal rates and provides tunable selectivity for SiC, SiN, and SiCxNy films, maintaining desirable removal rates and selectivity ratios, thereby improving the polishing process efficiency for semiconductor substrates.
Implementation Method 1
concurrent chemical and mechanical abrasion of the surface of the substrate
Implementation Method 2
a polishing composition comprising a liquid carrier, an abrasive, and an oxidizing agent
Data Source
AI summary
Chemical-mechanical polishing (CMP) compositions containing chemical additives and methods of using the CMP compositions are disclosed. The CMP composition comprises abrasive; chemical additive; liquid carrier; optionally an oxidizing agent; a pH buffering agent and salt; a surfactant and a biocide. The CMP compositions and the methods provide enhanced removing rate for “SiC”, SiN” and “SiCxNy” films; and tunable removal selectivity for “SiC” in reference to SiO2, “SiN” in reference to SiO2, “SiC” in reference to “SiN”, or “SiCxNy” in reference to SiO2; wherein x ranges from 0.1 wt % to 55 wt %, y ranges from 0.1 wt % to 32 wt %.