Especially for advanced masks the reticle inspection operation is a very significant cost factor, since it is a time
consuming process and inspection tools are becoming disproportionately expensive. Analyzing and categorizing
historical equipment utilization times of the reticle inspection tools however showed a significant amount of time which
can be classified as non productive. In order to reduce the inspection costs the equipment utilization needed to be
improved. The main contributors to non productive time were analyzed and several use cases identified, where
automation utilizing a SECS<sup>1</sup> equipment interface was expected to help to reduce these non productive times.
The paper demonstrates how real time access to equipment utilization data can be applied to better control
manufacturing resources. Scenarios are presented where remote monitoring and control of the inspection equipment can
be used to avoid setup errors or save inspection time by faster response to problem situations. Additionally a solution to
the second important need, the maximization of tool utilization in cases where not all of the intended functions are
available, is explained. Both the models and the software implementation are briefly explained. For automation of the so
called inspection strategy a new approach which allows separation of the business rules from the automation
infrastructure was chosen.
Initial results of inspection equipment performance data tracked through the SECS interface are shown. Furthermore a
system integration overview is presented and examples of how the inspection strategy rules are implemented and
managed are given.
In order to fulfil the upcoming requirements for photomasks there is a need for improving the process stability
(reproducibility) of the unit processes in photomask fabrication. In order to understand and minimize the etch
contribution to the CD stability impedance sensors integrated into the capacitively coupled radio frequency (RF) circuit
(bias circuit) have shown a big potential.
The last step towards a full characterization of the RF properties is the integration of impedance sensors in the
inductively coupled RF circuit (source). This kind of sensor measures voltage, current and phase angle for the
fundamental (13.56 MHz) and higher harmonics (up to the 5th harmonic).
In this paper we are describing the integration of the Z-Scan sensors into the source RF matchbox and its impact on the
RF and CD characteristics of the mask etcher. The central point is the correlation of impedance data to CD data. We will
also compare the responses for bias and source impedance measurements.