Edwards CTI Kryogenics On Board 8F Enhanced Cryopump Explanation

Edwards CTI Kryogenics Enhanced On Board 8F Cryopump: A Vacuum Performance Revolution in Semiconductor Sputtering Processes

Introduction: The core role and regeneration bottleneck of low-temperature pumps in semiconductor sputtering

In modern semiconductor manufacturing, physical vapor deposition (PVD) sputtering technology is widely used to deposit metal thin films such as aluminum, titanium, and titanium nitride. This process requires the chamber to reach a high vacuum (usually at the level of 10-7Torr) in a very short period of time to ensure film uniformity and adhesion. Cryopump has become a standard vacuum acquisition device for sputtering equipment due to its high pumping speed and oil-free cleanliness characteristics for gases, especially water vapor, argon, and nitrogen.

However, the "regeneration" of the cryogenic pump - that is, regularly heating and releasing the captured gas and extracting it - is an unavoidable maintenance step. During the regeneration period, the process chamber cannot produce, directly affecting the tool availability of the equipment. After multiple process cycles, the vacuum recovery speed of traditional cryogenic pumps gradually decreases, resulting in an increase in regeneration frequency and a regeneration time of several hours, which seriously affects wafer output.

The Enhanced On Board 8F cryogenic pump launched by Edwards CTI Kryogenics is designed to solve this contradiction. It significantly improves vacuum recovery performance through internal optimization while maintaining the exact same external dimensions, interfaces, and pumping speed as the original On Board 8F and Cryo Torr 8F, reducing regeneration frequency by half and significantly increasing equipment availability. This article will delve into its technical details and engineering value.

The correlation between vacuum recovery performance and regeneration frequency

2.1 The Importance of Vacuum Recovery Steps

In the sputtering process, after each deposition cycle, the process gas (such as argon or nitrogen) needs to be turned off, and then the chamber is quickly evacuated to a specified high vacuum level (such as 1 × 10 − 7 Torr), which is called "vacuum recovery". The speed of recovery directly determines when the next batch of wafers can start processing. If the recovery is slow, the process cycle may be extended, and the membrane quality may be affected by residual gases.

2.2 Recovery performance degradation leads to frequent regeneration

As the operating time of the low-temperature pump increases, the adsorbed argon, nitrogen, and water vapor inside gradually accumulate, resulting in a decrease in the effective pumping speed of the pump, especially in high load areas. This directly results in a prolonged vacuum recovery time, and when the recovery time exceeds the allowed window of the process, regeneration must be performed. Traditional On Board 8F may require 4-6 regenerations per month in typical argon or nitrogen/argon mixed processes, with each shutdown lasting more than 2.5 hours, resulting in significant production capacity losses.

Core improvement of Enhanced On Board 8F: persistent recovery performance

3.1 Improvement mechanism and effect

By optimizing the adsorption structure and thermal management of the low-temperature plate, the enhanced 8F significantly prolongs the maintenance time of the "rapid recovery" state while maintaining the same pumping rate (hydrogen 2200 l/s, air 1500 l/s, water vapor 4000 l/s, argon 1200 l/s). The recovery performance curve provided in the data manual shows:

In the pure argon process, the vacuum recovery time of enhanced 8F can still be maintained at a very low level after long-term operation, and the number of regeneration triggers is significantly reduced.

In the nitrogen/argon mixed process (>50% N ₂), its recovery performance is also excellent, significantly extending the regeneration interval compared to traditional models.

Specific data shows that users can reduce the average monthly regeneration frequency by 40% to 65%. For example, if the original regeneration needs to be done 5 times a month, the enhanced regeneration can be reduced to 2-3 times, which means saving tens of hours of downtime per year.

3.2 Operation convenience brought by reduced regeneration frequency

Due to the reduced number of regenerations, engineers are more likely to synchronize regeneration operations with routine maintenance such as cavity baffle replacement or target material replacement, thereby further reducing overall downtime and achieving maintenance synergy.

3.3 No need for process revalidation

The manual emphasizes that the enhanced 8F has the same pumping speed for all gases as the standard On Board 8F and Cryo Torr 8F, so users do not need to re qualify the process after replacement, greatly reducing the risk and workload of replacement.

Performance parameters and regeneration time

4.1 Pumping speed and capacity

Parameter Value

Hydrogen pumping rate 2200 l/s

Air extraction speed 1500 l/s

Steam pumping speed 4000 l/s

Argon pumping speed 1200 l/s

Argon flux 700 SCCM (9 Torr-l/s)

Hydrogen capacity 12 standard liters (5 × 10 − 6 Torr)