In order to fully exploit the design knowledge during the operation of mask manufacturing equipment, as well as to
enable the efficient feedback of manufacturing information upstream into the design chain, close communication links
between the data processing domain and the machine are necessary.
With shrinking design rules and modeling technology required to drive simulations and corrections, the amount and
variety of measurements, for example, is steadily growing. This requires a flexible and automated setup of parameters
and location information and their communication with the machine.
The paper will describe a programming interface based on the Tcl/Tk language that contains a set of frequently
reoccurring functions for data extraction and search, site characterization, site filtering, and coordinate transfer. It
enables the free programming of the links, adapting to the flow and the machine needs. The interface lowers the effort
to connect to new tools with specific measurement capabilities, and it reduces the setup and measurement time. The
interface is capable of handling all common mask writer formats and their jobdecks, as well as OASIS and GDSII data.
The application of this interface is demonstrated for the Carl Zeiss AIMSTM system.
The photomask is a critical element in the lithographic image transfer process from the drawn layout to the final
structures on the wafer. The non-linearity of the imaging process and the related MEEF impose a tight control
requirement on the photomask critical dimensions.
Critical dimensions can be measured in aerial images with hardware emulation. This is a more recent complement to
the standard scanning electron microscope measurement of wafers and photomasks. Aerial image measurement
includes non-linear, 3-dimensional, and materials effects on imaging that cannot be observed directly by SEM
measurement of the mask. Aerial image measurement excludes the processing effects of printing and etching on the
wafer. This presents a unique contribution to the difficult process control and modeling tasks in mask making.
In the past, aerial image measurements have been used mainly to characterize the printability of mask repair sites.
Development of photomask CD characterization with the AIMSTM tool was motivated by the benefit of MEEF
sensitivity and the shorter feedback loop compared to wafer exposures.
This paper describes a new application that includes: an improved interface for the selection of meaningful locations
using the photomask and design layout data with the CalibreTM Metrology Interface, an automated recipe generation process, an automated measurement process, and automated analysis and result reporting on a Carl Zeiss AIMSTM system.