The Problem With Spin-On Carbon Materials

In an integrated circuit manufacturing process, spin-on-carbon (SOC) materials constitute an important layer for the multilayer process to achieve smaller feature size. The SOC layer responds to the photolithography, pattern transformation, substrate planarization, and a variety of other critical processes.

A key challenge in selecting a suitable material is that some processes require a high temperature, reaching as high as 300°C to 500°C, and most polymers decompose at these high temperatures. There are a few platforms that can survive, but these materials present challenges of their own. These types of materials that have high-temperature-stable polymers usually have poor solubility in commonly used organic solvents. Polymer types that are good for thermal stability often do not have good for gap fill or planarization. The SOC layer also must avoid both intermixing with the top layer and maintain line-wiggling resistance during pattern transfer etch.

The table below introduces two of Brewer Science’s high-temperature SOCs.

SOC Platform 1 can be used as a high-temperature SOC with a chemical vapor deposition (CVD) layer on top. The crosslinked film is very stable and can survive in high temperature processes up to and over 500°C. It also can be used as a standard SOC with a spin-on silicon hardmask on top. This SOC Platform 1 is designed to be used in a multilayer process and show excellent lithography performance.

SOC Platform 2 is a platform designed for better planarization. By controlling surface tension, viscosity, and crosslink reaction, the material has chance to flow during coat and bake steps to achieve planarization. This material can be modified to change the flow behavior in order to planarize different topography on substrates, such as bright field or dark field, and over small features or large features.

Both materials excel at standard temperature and high-temperature applications. They have a high carbon content for etch resistance, low film shrinkage, and good gap fill properties.