Michael E. Adel

Noncontact temperature monitoring of semiconductors by optical absorption edge sensing

Remote, noncontact temperature monitoring of semiconductors may be achieved by near infrared reflection spectroscopy of a wafer during processing. A technique is described which relies on the temperature dependence of the optical absorption edge characteristic of most semiconductors in conjunction with internal reflection at the interface between the wafer bulk and the vacuum/dielectric/device. Results are presented which demonstrate application of the technique to silicon wafers with a broad range of back surface properties such as single and double layer dielectrics. The measurements were carried out in situ during process in both a PVD metallization chamber and a plasma etch chamber, over the temperature range from 20 to 570 degree(s)C.

New compact-design interferometer-based spectral imaging system for biomedical applications

A common path interferometric element introduced in the optical path of an imaging device is a well documented method to perform multidimensional spectroscopy. Recent design modifications however have provided significant improvements including enhanced spectral resolution and optical throughput, reduced acquisition time, as well as reduced instrument weight and volume. The new design will be reviewed in addition to its impact on three applications: spectral karyotyping, spectral imaging of the human ocular fundus and remote sensing of water reservoirs.

Laser boresighting by second harmonic generation

Weapons delivery systems frequently use laser designators which require boresighting with the visual line of sight. For systems based on the Nd .YAG laser (A = 1 . O6jnrt) , this may be achieved by a boresight collimator with a second harmonic generating crystal in its focal plane which reradiates collimated, visible light (A 0 . 53/nfl) . The conception, design and testing of such a device will be described along with a comparison with alternative technologies which demonstrates its superiority in terms of conversion efficiency, damage threshold and design versatility.

Emissivity compensated radiance-contrast-tracking pyrometry for semiconductor processing

In this paper an analysis technique is presented which allows the achievable performance specifications for a single wavelength pyrometer to be calculated. The effects of pyrometer wavelength, wafer emissivity, background radiation and detector noise limitations are all taken into account in the modelling. It is demonstrated that in order to maintain a given precision the wavelength of the pyrometer must be progressively reduced in order to maintain radiance contrast as the wafer temperature rises. The analysis technique is also shown to be an effective design tool for determining the required electronic and optical performance specifications of the pyrometer in order to obtain a given temperature measurement precision.

True wafer temperature during metallization in physical vapor deposition cluster tools

Aluminum metallization is an important process for planarization and interconnect applications. Wafer temperature during deposition is one of the key parameter determining film properties such as reflectivity and resistivity. Results of experiments carried out in order to characterize the thermal behavior of product wafers during physical vapor deposition, primarily aluminum and wafer degas will be presented. The effects of back and front side depositions, backside gas pressure and plasma power level on deposition temperature are all investigated. The utility of real time in-situ temperature monitoring on every product wafer in all deposition chambers within a cluster tool and the advantages provided in terms of process monitoring are discussed.

Boresighting of laser range finder or designator systems with and without laser/FLIR synchronization

We have conducted experiments to prove feasibility of a boresighting method between a laser and a Forward Looking Infra- Red (FLIR) system, which has the advantage of working with or without synchronization between the laser pulses and the FLIR scanning. The method is based on the Thermal Target concept (TT); the laser energy is focused on a special substrate which is locally heated and produces a point image on the FLIR screen with respect to the FLIR line of sight which is boresighted. Resistance to laser damage by the required pulse energy densities was established by target lifetime measurements. The TT method can be also used for real time boresighting of the laser with the FLIR, which means that the boresighting is done while looking at the scenery.