Seeking an Edge in Dielectric Etch
By Jeff Chappell -- Electronic News, 3/19/2002
e-insite.net
Applied Materials Inc. says it can do away with the middle etch stop layer in copper dual damascene/low k stacks and provide better critical dimension (CD) control with its new EnTek Centura chamber.
With the world’s largest foundry and the world’s largest IDM recently discussing their preparations to enter the 90nm node next year, the world’s largest tool OEM rolled out its latest offering for dielectric etch for 0.10-micron features.
Building upon its four-chamber eMax dielectric etch tool, Applied has separated deposition and cleaning steps in two different chambers on the EnTek cluster tool. The company also added an integrated rate monitor (IRM). The IRM can not only provide precise control of trench etch depth, but control that’s precise enough to do away with the middle etch stop layer, thus lowering the overall effective k value of the stack, said Amulya Athayde, manager of technical marketing for dielectric etch for Applied. "We’re taking our chamber technology and adding some new capabilities in terms of hardware," he added.
By separating out the deposition and photoresist strip steps, EnTek avoids any stripping-induced k value shifts and the possibility of fluorine memory effect. This can occur after the resist strip that follows deposition of polymer material. The polymer can attach itself to other areas of the chamber, and when it comes into contact with the fluorocarbon typically found in strip chemistry, it produces fluorine in the atmosphere of the chamber. This fluorine can remove the carbon in carbon doped oxides that make up current low k, chemical vapor deposition films. This in turn increases the k value of the film.
"You don’t have any fluorine memory effect because the chamber you are stripping doesn’t see any polymer," Athayde said of the EnTek tool. As a result, process chambers can be optimized for a single process.
This in turn provides better pattern transfer and better CD control, Applied argued. Its IRM also provides further CD control, Athayde said. The IRM’s sensors sit on top of the process chamber, analyzing the light from |
