- Category:
Nano-ceria CMP Slurry Achieving Both High-Speed Polishing and Low Scratch in Front-End Processes with Advancing Miniaturization
From Part 1 to Part 9, we focused on advanced semiconductor packaging and introduced packaging materials designed to solve the challenges in the semiconductor back-end processes.
However, Resonac's product offerings are not limited to back-end materials; we also provide materials with high market share and technological capabilities in the semiconductor front-end processes.
In this column, we will explain the CMP slurry that supports device miniaturization.
In advanced semiconductor devices that support the expansion of AI, the importance of the CMP (Chemical Mechanical Polishing) process is increasing. As circuit line widths become finer, the depth of focus in the lithography process becomes shallower. Therefore, maintaining lithography accuracy requires the planarization of the wafer surface at the nanometer scale. Furthermore, in 3D stacking of chips, using HBM and 3D stacked logic, highly advanced planarization technology is required to ensure connection reliability and minimize structural distortion.
What is the CMP Process?
The CMP process removes surface irregularities from the wafer to achieve a high degree of planarity and is performed using equipment like that shown in Figure 1. A carrier holding a wafer is pressed under constant pressure against a polishing pad mounted on a rotating platen. As CMP slurry is introduced into the interface, the combined effects of the slurry’s chemical action (softening) and the mechanical friction of the abrasive particles facilitate planarization of the wafer surface.
Figure 1. CMP Equipment
Components of CMP Slurry and Types of Abrasives
The slurry is composed of abrasives, a dispersion medium (pure water), and additives. Abrasives such as ceria, silica, alumina, and others are selected based on the hardness and chemical properties of the target film to be polished, as shown in Table 1.
Table 1. Types and Applications of Abrasives
| Type of Abrasive | Main Polishing Target | Features |
|---|---|---|
| Ceria / Nano-ceria | Silicon oxide (Gate formation, STI, etc.) | High chemical activity, excellent in selective polishing for specific films. |
| Colloidal silica | Interlayer dielectric films, metal films | Uniform and spherical particles. Excellent in flatness and low-scratch properties, suitable for finish polishing. |
| Fumed silica | Interlayer dielectric films, tungsten, etc. | Fumed silica Interlayer dielectric films, tungsten, etc. Produced by vapor-phase methods, having an agglomerated structure. Excellent polishing rate, but with a high risk of scratches. |
| Alumina | Hard metal films, hard disks, etc. | Extremely high hardness and excellent polishing rate, but with a very high risk of scratches. |
Features of Nano-ceria Slurry
Resonac provides CMP slurries that are compatible with the most advanced device structures and diverse film qualities. In particular, our nano-ceria slurry has the following technical features.
Polishing Selectivity Applying Chemical Interaction
Ceria particles have a chemical interaction with silicon dioxide, enabling selective polishing. By combining this property with our proprietary slurry design technology, we can control the polishing selectivity according to the target film. For example, in the gate formation process, high-precision fine transistor structures can be formed by selectively polishing insulating films, such as oxide and nitride films, while minimizing the polishing of stopper materials, such as polysilicon.
Achieving Both High-Speed Polishing and Scratch Reduction
Conventional ceria slurries had the issue that increasing the slurry particle size to achieve a higher polishing rate increased the likelihood of polishing scratches on the wafer surface. As shown in Figure 2, our nano-ceria slurry controls the particles to be fine and uniform, reducing physical damage to the wafer, and suppressing the occurrence of scratches. Furthermore, by increasing the chemical activity on the particle surface while making them finer, the polishing rate is also maintained, contributing to improved device yields and shortened process times.
Figure 2. Comparison between Ceria Slurry and Nano-ceria Slurry
Published: July 28th, 2026
