Semiconductor manufacturers and their suppliers – both process tool vendors and providers of sub-fab systems – are looking to an open industrial networking methodology, EtherCAT, developed by Beckhoff Automation (Verl, Germany; m.beckhoff.com) to address the increasingly stringent control requirements of emerging high-precision processes.

During SEMICON West, early adopters are promoting EtherCAT as a next-generation real-time Ethernet control solution, with a variety of attributes: it is fast (good for controlling ever-more precise process recipes), open, and extendable to many more nodes than existing networking protocols. Those attributes make EtherCAT attractive to tool makers such as Applied Materials, Lam Research, and Tokyo Electron Ltd., as well as sub-systems suppliers such as Edwards (Crawley, England).

Fab managers increasingly are looking ahead to the availability of predictive maintenance and other data-based productivity approaches, all of which require fast, extendable networks.

EtherCAT is fast enough for near real-time control. Andrew Chambers, a product manager at Edwards, gave the example of a process recipe that requires a change in gas flow, resulting in a deviation in chamber pressure. To maintain good process control the pressure controller must respond to the change in flow as quickly as possible in order not to lose time as the process chamber conditions stabilize. The EtherCAT control architecture can enable the change in flow, and pre-emptively adjust the pressure control, in real time, using a central controller over the EtherCAT network, rather than relying on the devices responding individually to changes in circumstances.

Increasingly, shrinking device geometries and the trend towards “atomic-scale engineering” are putting pressure on the process tools to control all process parameters with high precision in real time. EtherCAT supporters argue that with very short cycle times and response rates, real-time process control becomes realizable, overcoming the problems that arise from serial control and looped-in control, which can introduce delays in the system.

Edwards’ Gerald Shelley said as tool vendors seek to improve processes, they may need to reduce individual process steps to less than one second. That in turn requires a fast network to enable parameter changes at a correspondingly high rate.

Beckhoff Automation developed EtherCAT based on a specific functional principle, they describe it as “processing on the fly,” which supports very short cycle times. EtherCAT’s rapid response times have therefore proved attractive to semiconductor process tool developers, Shelley said.

Flexibility, another key virtue, allows EtherCAT to support more than 65,000 nodes on a network. “It’s extendable. It can be reconfigured. And there is an emerging option where the network itself can provide power to the devices attached to the network, which reduces the cabling requirements to the system,” Chambers said. Pre-existing, conventional fieldbus networks can be added to the EtherCAT network as additional nodes. “If you’ve got a pre-existing system that you want to integrate into something new that has an EtherCAT network, then you can do that,” he also noted.

As an open protocol network, any party can use EtherCAT, which is described in international standards.

“It has the benefit that it doesn’t need any particularly special infrastructure components to make it run. There’s not a special master device. The devices themselves can incorporate the EtherCAT protocol. You can simply plug a device into the network and have it run. That makes it relatively easy to use,” Shelley added.

Toolmakers, such Applied Materials, Lam Research and Tokyo Electron Ltd., currently use a wide variety of tool control systems on their diverse product ranges. EtherCAT is seen as a route towards a common, adaptable control architecture that could support a diversity of process tools on a common platform.

Beckhoff Automation, with about 3,000 employees worldwide, has worked with its business partners to set up the EtherCAT Technology Group to further develop EtherCAT. The technology group currently has 3,810 members, up from just 300 in 2006.

“There will be open standards so that they’re available to all interested parties, but in particular the profiles of the devices which can be added to any EtherCAT network, the profiles which control how devices respond and communicate with a network, are being generated and developed by the supplier working groups, of which Edwards is a member. We, along with a wide range of other sub-system suppliers are developing devices to meet the requirements for installation in EtherCAT networks, to be able to provide the functions and features that are needed by the semiconductor industry,” Shelley said.

In the future, process tool manufacturers will be able to select from a range of devices with similar functionality which will fit on the same network, so it reduces the dependency of toolmakers on specific individual suppliers. This enables process tool makers to develop advanced bespoke control algorithms and address emerging process challenges.

“From a total process control perspective, our view is that as high volume manufacturing moves towards smaller and smaller nodes, introduction of those processes is going to depend on a complete sub-fab process solution per process tool. These solutions will be based on some kind of integrated best-known method that describes how you set up the sub-fab equipment to deliver what the process vendor needs,” Chambers added.

Predictive maintenance, Intelligent devices

Next-generation sub-fab systems will require the ability to analyze data gathered within the system, or within the submodules within the system. The system will be comprised of intelligent devices, all generating data. “The question that we all have to address is how do you turn huge amounts of data into useful information. We believe that the manufacturer of the sub-fab equipment is well placed to turn raw data into useful information, which then can be relayed to the process tool,” Chambers said.

Relaying that information to the process tool is where the EtherCAT network plays an important role. “The sub-fab equipment could be hooked up to the process tool control network as a node on the EtherCAT network, despite the fact that what’s going on within the integrated sub-fab system doesn’t depend on EtherCAT for its functionality,” he said.

The process tool and the sub-fab equipment are able to exchange operational data or information in real time over an EtherCAT network. “That means if things are happening in the process tool that would benefit from a change in what’s happening in the sub-fab, then that data can be shared, and the sub-fab equipment can adapt itself to whatever the process tool is doing at that specific time, with the result that new and more efficient modes of operation are possible across the tool” he added.

“The equipment in the sub-fab will be generating vast amounts of data. Our intent is that the sub-fab equipment itself processes the data to turn it into information, and the kinds of information that we’re talking about is working up predictive maintenance algorithms so you can effectively predict when, for example, a dry pump or abatement system is going to need service attention, with sufficient advance notice that it can be scheduled into the process tools job schedule,” he said.

“The key point is neither a process toolmaker nor a sub-fab equipment supplier is able to do this in isolation. The whole thing becomes an iterative partnership between the tool operator, the OEM, and the sub-fab equipment maker. Going forward, we can see the emergence of process-specific predictive algorithms as a necessary requirement to enable fully cost-effective device manufacturing,” Chambers said.