Applied, Novellus are quietly working on spin-on low-k for copper, just in case
By J. Robert Lineback
Semiconductor Business News
(04/06/00, 08:49:08 AM EDT)
MUNICH -- You'd think IBM Corp.'s announcement on Monday to use a spin-on low-k dielectric material in 0.13-micron copper ICs would be a major setback for Applied Materials, Novellus, and Trikon Technologies. The three tool suppliers are promoting chemical vapor deposition (CVD) technologies for the same next-generation interconnect process application.
But while IBM carries a lot of weight in interconnect processing trends after becoming the first producer of copper chips in volume, it is uncertain if other IC manufacturers will follow Big Blue's lead in low-k dielectrics, said managers for Applied, Novellus, and Trikon during meeting here at the Semicon Europa trade show this week. IBM plans to use Dow Chemical Co.'s SiLK spin-on resin for low-k dielectric insulators in an integrated dual-damascene copper process starting next year.
A couple days after IBM's announcement, Applied, Novellus and Trikon managers maintained that CVD films still have advantages over spin-on low-k dielectrics in mechanical strength, lower production costs, and process integration with dual-damascene copper processes. But, Applied Materials Inc. and Novellus Systems Inc. are also hedging their competing CVD bets in interlayer dielectric (ILD) processes by exploring options that would put them into the spin-on low-k dielectric arena.
Last August, Novellus Systems Inc. quietly acquired the spin-on dielectric activities of Fairchild Technologies in Fremont, Calif., to pursue future alternatives to CVD low-k processes with organic thin films with dielectric constants in the 2.5 to 2.0 range.
"We are hedging our bet in 2.2 [dielectric insulators], which will be needed for the 0.10-micron technology node," explained Wilbert van den Hoek, executive vice president of integration and advanced deposition for San Jose-based Novellus during an interview at the Munich trade show on Wednesday. "However, we do not believe this capability will be needed in 0.18- to 0.13-micron [process nodes], and I would say CVD silicon-oxide carbide films are still favored by 80% of the people in the industry."
Meanwhile, Applied Materials in Santa Clara, Calif., is widely rumored to be working on a new track system for spin-on low-k dielectric applications. During the Munich trade show, officials would not discuss details about possible alternative to CVD-based low-k dielectrics, but Applied chairman and CEO James C. Morgan said his company would participate in whatever approach the industry takes in next-generation interconnect processes.
"If we believe that it [spin-on low-k dielectrics] is going to be a mainstream capability or a significant part of the market, we will provide that capability," Morgan promised. However, Applied is still working with a range of customers, which are considering its Black Diamond CVD-based low-k dielectric technology, said David N.K. Wang, senior vice president in the Office of the President at Applied.
"We have worked very closely with IBM on Black Diamond," noted Wang, suggesting that many options are still on the table for low-k dielectrics in future copper processing steps. For that reason, companies usually have "two or three approaches going on simultaneously," added Morgan.
Officials with Trikon Technologies Ltd. of Newport, Wales, insisted that CVD low-k dielectrics were still well ahead of spin-on films for ILD applications, and company managers said that the industry's movement to copper interconnects from aluminum metal was not proceeding as quickly as many might think. During Semicon Europa, Trikon rolled out a new cluster tool for its CVD tools and "tunable" low-k films with a dielectric constants down to 2.5.
Conventional silicon-dioxide insulators in aluminum interconnects have a dielectric constant of about 4.1. The lower the dielectric constant of new insulators will greatly improve chip speed by reducing capacitance in interconnects and protection against crosstalk between metal lines in high-performance logic. For several years now, chip makers have been wrestling with the many tradeoffs between a range of spin-on and CVD thin-film candidates. Most industry experts believe the industry will most likely narrow the opinions for low-k materials and processes in 2000.
Trikon and its technology partner, LSI Logic Corp., are running counter to a growing belief in the chip industry that copper processing will become necessary by the 0.13-micron technology nodes in high-performance ICs. Last month, LSI Logic of Milpitas, Calif., announced a 0.13-micron technology using Trikon's low-k Flowfill CVD technology with standard aluminum wiring.
"The extendibility of subtractive-aluminum etch processes has a lot more life than people think," insisted Andy Noakes, CVD products marketing manager during a press briefing at Semicon Europa on Wednesday. "I don't think copper processing is really coming on as fast as some people think."
And Trikon also believes that spin-on low-k dielectrics are behind CVD technology for a variety of reasons. One problem for most spin-on films is the need for extra steps to use hard masks since the material is softer than the CVD dielectrics, Noakes said. The hardness of the dielectric materials is a critical factor in its ability to hold up under the stresses in copper fabrication--in particular during chemical mechanical planarization (CMP), which polishes interconnect layers flat during the dual-damascene processes.
Trikon now collecting data for its Flowfill CVD technology to determine its specifications for low-k in copper processing. The U.K.-based company believes there is still plenty of time to work out the integration of its new Planar fxP low-k process with copper, and it's planning joint-development partnerships...." |
