Infineon Technologies Ag

Nan Ya Technology Corporation

Anita Klee

Peter Weidner

Barbara Schmidt

Pierre-Yves Guittet

Alexander Kasic

Zhen-Long Chen

An apparatus for monitoring a trench profile of a substrate includes a radiation-emitting unit for irradiating the substrate with infrared radiation. The intensity and/or polarization state of the infrared radiation reflected from the substrate is measured at a multitude of measuring frequencies. An analyzing unit determines the respective reflectance and relative phase change and/or relative amplitude change in relation to the respective measuring frequency. In addition, a reflectance spectrum, a relative phase change spectrum and/or a relative amplitude change spectrum may be obtained. By performing a Fourier transformation of the respective spectrum, a secondary Fourier spectrum is obtained. The secondary Fourier spectrum plots a virtual amplitude against corresponding values of a frequency periodicity that correspond to a substrate depth. Peaks of the virtual amplitude may indicate reflective planes within the substrate at respective depths. Thus, rough sections in the trench profile may be identified without modeling.

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Langebrueck, Germany

Anita Klee