“Calling it “wet” means “dry” may sound like a riddle, but for plasma process equipment, the answer is “wet cleaning,” an important form of preventative maintenance.

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preventive maintenance

Calling it “wet” means “dry” may sound like a riddle, but for plasma process equipment, the answer is “wet cleaning,” an important form of preventative maintenance.

The term “wet cleaning” comes from the industry’s early days of preventive maintenance, where reaction chambers were disassembled and quartz components were immersed in acid water before being allowed to dry and reassemble. For equipment that requires high-precision maintenance, the only commonly used substance that refers to “wet” is a lint-free cloth moistened with deionized water, but the traditional term “wet cleaning” is still used today. Therefore, the maintenance method is called “wet method”, but it is actually “dry method”.

The goal of preventive maintenance is to keep equipment up and running and to minimize any unplanned downtime, which typically disrupts production significantly, resulting in higher costs and lost production. Like a car, regular engine oil changes are the key to maximizing the life and performance of your car. During the process of etching thousands of wafers, the polymer of the removed material accumulates on the surface of the plasma chamber.

We need to deal with such aggregates because they can be a source of contamination and because they have the potential to alter the induction or conductance within the chamber, thereby affecting the plasma process. Aggregate handling relies heavily on well-established plasma cleaning cycles, but there are times when regular preventive maintenance of the chamber is also required.

The number of steps and precision requirements for this preventive maintenance have increased significantly. In 2000, the entire maintenance process consisted of only about 35 steps, but today there are more than 150 steps, and the requirements for precision are much higher. Such complicated maintenance processes and high precision requirements often lead to maintenance failure rates as high as 30%, which not only means lost production, but also the loss of spare parts and test wafers, and the resulting cost increase.

Wet cleaning optimization

To solve the above problems, Lam has launched a service called “Wet Cleaning Optimization” (WCO), which is used to eliminate human variance and improve the success rate of preventive maintenance. Today, WCO has been used in a large number of etch and deposition chambers around the world, helping multiple customers solve problems such as increasing production and greatly reducing waste.

As a total solution, WCO covers specialized equipment, localized multimedia step-by-step instructions, data analysis and expert support (diagnosing maintenance issues and driving continuous improvement).

Professional equipment

Using the right equipment can dramatically increase productivity and efficiency and keep people safe. WCO service packages ensure that customers have standard and custom equipment when and where they need it.

Multimedia step-by-step instructions

One of the challenges that preventive maintenance teams often face is the replacement of maintenance personnel (18-month turnover rates can be as high as 100%), in which case step-by-step procedure instructions and easy-to-reference operating documents are very important.

data analysis

This is a key component of the WCO, which transforms wet-cleaned data into usable information. One of the keys to driving continuous improvement is to use high-quality analysis to identify the areas where improvement is most needed, and to measure and quantify how these improvements can be made.

Expert support

Professional engineers drive accountability, investigate issues, and drive systemic improvements.

Application scenarios

We will help you better understand the role of WCO through the introduction of the following application scenarios.

Chipmaker A is experiencing unpredictable performance issues with wet cleaning of its plasma etch equipment that has impacted equipment availability. The fab manager understands that the cause of the problem is high employee turnover, but he cannot improve the current situation through internal training or other actions. After the introduction of Lam’s WCO, localized step-by-step operation videos can help new employees quickly understand the situation and quickly achieve stable high-performance wet cleaning. Time-consuming wet cleaning and unplanned equipment downtime have been reduced, resulting in improved equipment uptime and yield.

Chipmaker B is using a new type of chamber for yield ramping and wants to achieve high productivity as quickly as possible. By bringing in the best of what WCO has to offer, B’s staff quickly got the hang of it, the variance in maintenance time was reduced, and the new chamber quickly achieved continuous and stable uptime.

Summarize

WCO is an approach that helps customers successfully complete preventive maintenance on their own. The holistic approach incorporates Lam’s proprietary software, data analytics and certified cleaning procedures with video guidance. Additionally, WCO is part of Lam’s Equipment Intelligence®, a comprehensive productivity solution based on Lam’s equipment experience and data.