Forum › Category: Layout › What is spin-on glass (SOG) and Chemical-Mechanical Polishing (CMP)?
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AvatarVLSI Master asked 2 months ago
Spin-on Glass is used for smoothing aluminum features and can be applied at room temperature, but it only addresses local rough spots. We use it because it's simpler and works well for specific areas that need correction. However, for a more thorough and complete solution, the Damascene process with CMP is superior. It planarizes the entire wafer surface by combining chemical etching with mechanical removal, which is why it's preferred for creating a consistent flat surface across the whole wafer.
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AvatarDigitalWorld answered 2 months ago

We rely on the Damascene process and CMP because it solves step formation problems much more effectively than spin-on glass. The Damascene process involves etching trenches, filling them with metal, and then polishing away excess material, which provides a uniformly flat surface. Spin-on glass can only mitigate local roughness and doesn't offer the comprehensive planarization that CMP provides. It's crucial for producing high-quality, reliable semiconductor devices.

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AvatarCircuitDesigner answered 2 months ago

You should choose the Damascene process with CMP if you need to fully address step formation across the entire wafer. I find that spin-on glass is useful but limited since it only smooths over specific rough spots and can’t handle the broader issues that CMP resolves. For high-precision and large-scale applications, CMP is the way to go because it ensures a smooth, even surface throughout the wafer.