WaferMasters | Products | PROCESSES

DESIGN PHILOSOPHY

PROCESSES

WaferMasters has developed robust platforms to provide a near Isothermal environment for rapid thermal processing of wafers. This provides truly differentiated results compared to lamp based RTP for two reasons:

1. Consistent, uniform, predictable and reliable on-wafer processing at advanced technology nodes because the process module is essentially invariant throughout the manufacturing run.

2. Since radiation is a small component in the Isothermal Process Module design, processing is largely without the harmful effects of the Pattern Effect. This is demonstrated in some of the graphics below:

THERMAL PROCESSING

Wafer Level

At the Wafer Level, the benefits of Isothermal Processing can be seen in this comparison of detailed sheet resistance measurements following WSi anneal carried out on wafers processed in 3 different systems; a WaferMasters SRTF, a honeycomb Lamp RTP system and a linear Lamp RTP system. All wafers have been characterized in detail, with 625 point measurements. In the 2D and 3D representations below, the excellent within wafer uniformity is confirmed in the SRTF. The advantage of the Isothermal Process Module is designed in, and, with the advantage of rock solid reproduceability, wafers are produced with essentially identical results over months of continuous processing, with no interruptions or maintenance, and uptimes of > 99%.

Device Level

The schematics of the STI structures on the left illustrate the way Isothermal Processing and lamp RTP differ at the device level. The Isothermal Process Module of the SRTF/SAO conveys heat to the structures evenly (there is no physics mechanism for differential treatment of the circuit geometries). However, for photon based processing, structures act as gratings and diffraction effects, as well as other localized thermal transfer mechanisms, have measureable impact, causing non-uniformities. Within the trench, for example, due to the periodic trench structures, radiation bends and we can get localized sidewall heating and selective film buildup that are a cause of leakage. At the feature sizes of advanced technology nodes, strong coupling exists between the circuit periodicities and the many spectral lines of halogen lamp radiation, exacerbating this phenomenon to meaningful levels. In the hot wall, Isothermal Process Module of the SRTF/SAO, there is no similar mechanism. The graphic at the right shows how edge to center thickness can vary, depending on the choice of thermal process system.

Data from: H. Itokawa, H. Akutsu, A. Nomachi, H. Oono, T. Iinuma and K. Suguro, Ext. Abst. 2006 Int. Conf. on Solid State Device and Materials (Yokohama, 2006) 342.

PROCESSING REQUIREMENTS

WaferMasters has systems covering nearly every thermal processing requirement. This chart of process temperature and time shows the product offerings which are available for 200mm and 300mm wafer applications.