Improving Semiconductor Yield Rates, Process and Equipment Reliability

by | Oct 13, 2021 | Event, Fluid Control & Pneumatics

Teck Hian Lee

Semiconductor Specialist, Fluid Control and Pneumatic

Oct 26-28 Emerson Exchange Asia-PacificWhen we purchase a mobile tablet, a cell phone or an electrical appliance, how long do we want that product to last? Consumers today have great expectations for electrical products to last for as long as they should. Having worked in a 200-mm and 300-mm wafer fabrication plant in the operations team and as a technical trainer in a semiconductor manufacturing company before, all these come too familiar to me.

Semiconductor industry challenges and concerns

Wafer fabrication plants need to make integrated circuit chips within specifications and achieve zero failure rate throughout the product’s intended lifespan. Furthermore, manufacturers are constantly looking for ways to improve yield rate, to achieve higher profitability for the company.

The manufacturing process of semiconductor chips is very complex. It takes anywhere from 20 days to more than 2 months to transform a bare wafer into a wafer filled with complex dies. This involves several repeated steps executed layer by layer onto the bare wafer. Any wafer scrapped during the production causes considerable revenue and production time loss to the company. Contamination, defects and scratches are major challenges faced by wafer fabrication plants.

In which areas can we look?

Reliability, responsive and precise flow control, fast response, efficient pneumatic control, high precision and repeatable electro-mechanical actuation, and source material quality are critical for improving yield rates. Reliability refers to equipment reliability and process reliability.

A semiconductor manufacturing equipment is made up of complex and interlink subsystems working together to perform very complex tasks in a very short time. Equipment reliability is the measure of how long the equipment can operate without failure. Be it by wafer count, RF hours, deposition thickness or etch thickness.

As it takes up valuable production time to troubleshoot and identify possible root causes of an alarm, it is essential to alleviate impending equipment failure by ensuring every single component of the equipment performs smoothly. Additionally, wafer fabrication plants need to address and prevent issues such as airborne molecular contamination, equipment be able to perform reliable efficient on-demand switching of valves and actuators and gas panels able to execute precise and contamination-free gas delivery.

Prevent airborne molecular contamination

Airborne molecular contaminants, oxygen and moisture in the cleanroom environment affects the performance and reliability of the integrated circuits. Sensitive surfaces on the silicon wafers need to be kept in a nitrogen-only environment. Nitrogen purging stations are used to inject nitrogen gas to purge away oxygen, moisture, and other contaminants from reacting with the silicon wafer surfaces. We require high flow solenoid valves for the purging stations to be reliable and responsive, and energized on demand.

Perform reliable, efficient on-demand switching of valves and actuators

In a semiconductor process that produces heat, temperature control is critical. This ensures wafer-to-wafer, lot-to-lot temperature variations are kept to a minimum. Rapid cooling is also deployed in the backend to ensure the dies are not damaged during the packaging process.

Regulating the temperature of the chamber wall and the pedestal requires the use of a chiller unit or heat exchanger. Excellent flow regulation inside the chiller unit ensures that every wafer is kept in the same processing temperature environment. It is essential to have reliable and responsive solenoid valves that are designed to operate in harsh, high temperature environment with a small footprint.

Execute precise and contamination-free gas delivery

Semiconductor wafer fabrication plants require large amount of bulk gases and specialty gases in the making of IC chips on a silicon wafer. These gases are required to be of the highest purity level to fabricate the complex and sensitive materials in the chip.

To deliver these gases to the semiconductor equipment, the gases travel far distances through the distribution lines. We need to ensure the gases are delivered at the same pressure and same flow to the same equipment group to minimise lot-to-lot or batch variation. Precise pressure control regulators ensure that the gases are regulated to the highest precision level, thereby delivering contamination-free gases accurately and reliably.

I encourage you to register and join me at Emerson Exchange Asia Pacific, coming up October 26 to 28, where I’ll talk more about some fluid control and pneumatics solutions specific for the semiconductor industry.

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The opinions expressed here are the personal opinions of the authors. Content published here is not read or approved by Emerson before it is posted and does not necessarily represent the views and opinions of Emerson.