How Are Heating Plates Certified to Meet SEMI Standards for Semiconductor Manufacturing Equipment?

The manufacture of semiconductors requires great cleanliness and purity of materials. The heating plates used in wafer processing equipment have to meet very strict SEMI criteria which go much beyond basic electrical safety to include outgassing, particle production and materials compatibility.

What Are SEMI Standards
SEMI (Semiconductor Equipment and Materials International) is an international trade association that creates standards to ensure the quality, safety and environmental compatibility of semiconductor production equipment. These criteria are essential for the cleanliness and performance needed in semiconductor manufacture. SEMI standards span a broad spectrum of topics including equipment safety (S2), environmental compatibility (S8) and material-specific requirements. When it comes to heating plates SEMI compliance means that they meet the high purity standards required for semiconductor production.

SEMI Standards Key for Heater Plates
SEMI S2 - Safety of equipment
SEMI S2 establishes general safety rules for semiconductor equipment to ensure that the heating plates are safe to use in a manufacturing environment. . SEMI S2 compliance is validated by a third-party assessment done by a certified SEMI S2 evaluator. The standard covers electrical safety, mechanical integrity and the general operation of the equipment.

SEMI S3 - Safety Guidelines for Heated Chemical Baths 
SEMI S3 pertains to equipment safety in heated chemical baths. This standard guarantees that heating plates, employed in chemical processing systems, do not pose safety risks or operational inefficiencies. It also includes materials and structure to avoid contamination by the hot chemical solution.

SEMI F57 - Specification for Polymer Materials in Ultrapure Water and Liquid Chemical Systems
SEMI F57 defines the standards for polymer materials, including coatings on heating plates, in contact with ultra pure water and liquid chemicals. This standard assures that the materials used in semiconductor production equipment are compatible with ultra-pure fluids and do not impact process purity.

Certification Standards for Heating Plates
Heating plates in semiconductor equipment are required to be rigorously tested to SEMI standards. These tests are related to the material qualities, contaminant resistance and chemical compatibility:

Outgassing (ASTM E 595)
Outgassing is the emission of volatile chemicals from the materials of the heating plate on heating. In semiconductor manufacturing, contamination in the cleanroom environment can lead to faults in semiconductor devices even from tiny levels of outgassing. Heating plates made of materials such as PTFE and PFA coatings must be tested for outgassing according to ASTM E595 requirements to guarantee they do not release hazardous compounds during operation.

Particle fall-off
Heating plates should be constructed to minimise the creation of particles that may contaminate the wafer or chemical operations. Any material that may come in contact with process fluids must be examined to ensure that it does not shed particles to levels that will interfere with the delicate manufacturing processes in semiconductor fabs.

Resistance to Process Chemicals 
Heating plates in semiconductor fabrication are often subjected to hostile substances such as acids, solvents and ultrapure water. These materials need to be corrosion resistant and resistant to degradation under the unique circumstances of the semiconductor production process. PTFE and PFA coatings are widely used on heating plates due to their superior chemical resistance, ensuring that the integrity of the heating surface is maintained without introducing any contaminants.

SEMI Standards for Heated Platens and Chucks Important SEMI Standards SEMI S2 - Equipment Safety (General Safety Requirements)

SEMI S3 - Safety Guidelines for Chemical Bath Heater

SEMI F57 - Specification for Polymer Materials in Ultra Pure Water and Liquid Chemical Systems

ASTM E595 Outgassing Test Method

SEMI F47 – Recommended Practices for Semiconductor Manufacturing Equipment

Conclusion 
SEMI is a standard that heating plates used in semiconductor equipment must meet the purity and safety standards of semiconductor industry. Heating plates are certified free of metal contamination, minimise particle shedding and meet outgassing regulations to protect the semiconductor production process. Niche sectors are developing their own specific standards to fulfil their particular technical needs. Compliance to such standards ensures the equipment meets the stringent, high-performance requirements of the semiconductor industry.