PEEK Applications | Analysis of PEEK Material in CMP Retaining Rings and Key Technologies

The CMP (Chemical Mechanical Polishing) process is crucial in semiconductor manufacturing.

The CMP retaining ring, a critical consumable in this process, plays a role in fixing and supporting the wafer. As manufacturing complexity increases, the performance requirements for retaining ring materials have become more stringent.

Polyether Ether Ketone (PEEK), with its exceptional high-temperature resistance, chemical inertness, high mechanical strength, and ultra-low contamination, is becoming the ideal choice for high-end CMP retaining rings. This article analyzes the technical aspects of CMP retaining rings and focuses on the advanced application of PEEK in this field.

What is a CMP Retaining Ring?

CMP (Chemical Mechanical Polishing) is a key process combining chemical corrosion and mechanical polishing, used to remove excess/irregular dielectric layers from the wafer surface to achieve a highly precise planar surface.

CMP is widely applied in semiconductor manufacturing to remove various surface materials such as silicon dioxide, tungsten, and copper.

The CMP process uses consumables including:

• Slurry

• Polishing pads

• Pad conditioners

• CMP retaining rings

• Membranes, etc.

Functions of CMP Retaining Ring

CMP retaining rings are annular components mounted on the polishing head assembly with the following core functions:

• Wafer Fixation:
  Secure the wafer within the polishing head to prevent shifting or sliding under high-speed rotation and pressure.

• Edge Effect Improvement & Uniformity Enhancement:
  Optimize design to prevent over-polishing at the wafer edges, ensuring uniform surface polishing and improving yield.

• Wafer Edge Protection:
  Provide cushioning to protect wafer edges from chipping or cracking during polishing.

The precision and performance of the CMP retaining ring directly affect wafer polishing quality, yield, and process stability.

Challenges for CMP Retaining Rings

1. Harsh Mechanical Load

• High-pressure friction environment:
  Retaining rings endure higher downward pressure than wafers and withstand high-speed friction with polishing pads.

• Dynamic Wear:
  Continuous edge contact between the wafer and retaining ring challenges material integrity and wear resistance.

• Structural Stability Requirements:
  Balance between rigidity (anti-deformation) and toughness (impact resistance) to prevent cracking or dimensional drift.

2. Chemical Corrosion

Each wafer undergoes multiple CMP processes requiring different polishing slurries. The chemical environment varies, posing corrosion challenges to retaining ring materials.

Performance Requirements of CMP Retaining Rings

• Mechanical strength and wear resistance

• Chemical resistance to various slurries

• Dimensional stability

• Low contamination

• High precision manufacturing capability

Advantages of PEEK Material

As semiconductor processes advance, traditional materials struggle to meet the demands of high-end CMP. PEEK, with its comprehensive high-performance characteristics, is emerging as the core material for new-generation retaining rings.

Key advantages:

• Excellent high-temperature resistance

• Chemical inertness

• Superior mechanical strength

• Low particle generation and contamination

• Prolonged service life — several times that of traditional materials in certain CMP processes

Retaining Ring Structural Types & Market Trends

Two main structural types of CMP retaining rings:

1. Pasted Retaining Ring:
   High-performance plastic patches adhered to a metal base ring. Mature technology but risks metal exposure and adhesive contamination.

2. Overmolded Retaining Ring:
   High-performance plastic fully injection molded over a metal ring. No metal exposure, no bonding interface contamination — more suited for high-cleanliness processes and increasingly accepted by clients.

Both types can be manufactured using PEEK. With increasing cleanliness and consistency requirements, overmolded rings are gaining market traction.

PEEK Solutions for CMP Retaining Rings

High-performance CMP retaining rings depend on premium raw materials with strict requirements for polymer purity, stability, and processability.

ARKPEEK-1000 pure resin granules have proven market success in CMP retaining rings.

Main Advantages:

• High purity, minimizing black spots and impurities

• Excellent toughness and impact resistance

• Superior dimensional stability and flow for precision molding

• Outstanding electrical, chemical, and flame-retardant properties

• Customizable formulations for specific client needs

With R&D and production bases in Changchun, Shanghai, and Shenzhen, ARKPEEK Corporation provides competitive high-performance material solutions for China's semiconductor industry, helping clients reduce costs and enhance performance.

Conclusion

As semiconductor processes continue to advance, CMP retaining rings face higher material and structural demands. PEEK, as a leading high-performance engineering plastic, is accelerating its adoption as the preferred material for high-end CMP consumables.