Applied Employs Backside Heating in Vulcan RTP Tool
By David Lammers
Applied Materials launched its Vantage Vulcan rapid thermal processing (RTP) system Wednesday (June 29), employing wafer backside heating to sharply improve the temperature uniformity across the individual die.
New transistor types require careful temperature control. (Source: Applied Materials)
Sundar Ramamurthy, general manager of Applied’s Front End Products within the Silicon Systems Group, said die sizes have grown larger in recent years, making it more challenging to control the annealing temperature across the dense and less-dense areas of the die. Also, new transistor designs, at ever-smaller smaller device dimensions, require multiple RTP steps that are more carefully controlled. That led Applied to develop a backside heating design, which he said is a first for the industry.
A honeycomb array of lamps provides heat from the back side of the wafer. (Source: Applied Materials)
The honeycomb-like array of lamps is configured into 18 zones, controlling a much-wider range of temperatures — from 75°C to 1,300°C — than Applied’s earlier RTP systems. “Contact materials are coming in that require lower temperatures, and this ability to operate at less than 250 degrees C is huge for our customers,” Ramamurthy said, particularly as they seek to reduce contact resistance.
The temperature variability was reduced from 9°C to 3°C by using backside heating, he added. The system can control within-die temperature to less than 3°C — even while the wafer temperature is aggressively ramping at more than 200°C per second.
Compared with direct radiant heating, the backside heating approach reduces the hot spots across the patterned wafer, reducing the transistor performance variations which result in more low-end chips on the wafer, he said.
The Vantage Vulcan includes closed-loop control which can dynamically control wafer temperature as the tool ramps from almost room temperature to 1,300°C. The capability enables any device wafer, including wafers with challenging reflective surfaces, to be processed without recipe modification – a benefit for the high-mix, fast-changing environment of foundries.
Applied has been working with early customers and the company is received repeat orders from customers beginning to ramp their 28nm technology to volumes, he said. He estimated the RTP served available market at $500 million.
Tags: Applied Materials, RTP