Experimental Investigations of Laser Micromachining of Metal Using Micro Thin Film Thermocouples

2007 ◽  
Author(s):  
Hongseok Choi ◽  
Xiaochun Li
Keyword(s):  
Thin Film ◽  
Surface Temperature ◽  
Laser Energy ◽  
Laser Micromachining ◽  
Temperature Measurements ◽  
Laser Spot ◽  
Experimental Investigations ◽  
Operation Temperature ◽  
Thin Film Thermocouples ◽  
Complex Phenomena

Laser-material interactions involved in laser micromachining are extremely complicated. In order to improve the fundamental understanding of the laser micromachining process, it is essential to investigate the complex phenomena and mechanisms of the physical processes within and close to the region of the interaction. Topographical characterizations of laser micromachining with various laser energy fluences were undertaken to correlate the resulting geometry changes with surface temperature measurements. Single pulses of laser beam with a nominal diameter of 47 μm were used. Possible changes of surface chemical composition induced by the laser micromachining process, in particular oxide formation, were also investigated around the laser spot. Moreover, C-type micro thin film thermocouples (TFTCs) with a junction size of 2 μm × 2 μm were fabricated to increase the maximum operation temperature and spatial resolution of temperature measurements. Surface temperature distribution around the laser spot was obtained in the range from 45 μm to 85 μm away from the center of laser spot. The result showed that there was a steep gradient of temperature in the radial direction and a superheated area around laser spot. It was also observed that the temperature profile matched the oxidation profile due to thermal effects.

Experimental Investigations of Laser Micromachining of Nickel Using Thin Film Micro Thermocouples

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Hongseok Choi ◽  
Xiaochun Li
Keyword(s):  
Thin Film ◽  
Surface Temperature ◽  
Laser Energy ◽  
Laser Micromachining ◽  
Laser Spot ◽  
Experimental Investigations ◽  
Operation Temperature ◽  
Fundamental Understanding ◽  
Thin Film Thermocouples ◽  
Complex Phenomena

Laser-material interactions during laser micromachining are extremely complicated. In order to improve the fundamental understanding of the laser micromachining process, it is essential to investigate the complex phenomena and mechanisms of the physical processes within and close to the region of the interaction. Moreover, C-type micro thin film thermocouples with a junction size of 2×2μm2 were fabricated to increase the maximum operation temperature and spatial resolution of sensors. Surface temperature distribution around the laser spot was obtained in the range from 45μmto85μm away from the center of laser spot. The result showed that there was a steep gradient of temperature in the radial direction and a superheated area around the laser spot. Topographical characterizations of laser micromachining with various laser energy fluences were undertaken to correlate the resulting geometry changes with surface temperature measurements. Possible changes of surface chemical composition induced by the laser micromachining process, in particular, oxide formation, were also investigated around the laser spot.

Transient Surface Temperature Measurement With Micro Sensors for Nanosecond Pulsed Laser Micromachining of Nickel

2006 ◽  
Author(s):  
Hongseok Choi ◽  
Xiaochun Li
Keyword(s):  
Laser Energy ◽  
Numerical Models ◽  
Pulsed Laser ◽  
Laser Micromachining ◽  
Measured Data ◽  
Time Resolved ◽  
Nanosecond Pulsed Laser ◽  
Thin Film Thermocouples ◽  
Transient Thermal ◽  
Thermal Phenomena

In order to investigate and understand the complicated transient thermal phenomena in laser micro processing, it is essential to accurately measure time-resolved temperatures of the workpiece. Micro thin film thermocouples with a micrometer spatial and nanosecond temporal resolution were fabricated on electroplated nickel workpieces to measure transient surface temperatures in nanosecond pulsed laser micromachining by ablation. Transient temperatures were successfully measured, and the effect of laser energy fluences on the peak temperatures was experimentally investigated. This study demonstrates that the micro TFTCs can be useful in measuring the transient temperatures on the workpiece during laser micromachining, and the measured data can be utilized to validate and improve existing analytical and numerical models.

RTP Calibration Wafer using thin-film Thermocouples

1998 ◽  
Vol 525 ◽  
Author(s):  
K. G. Kreider ◽  
D. P. Dewitt ◽  
B. K. Tsai ◽  
F. J. Lovas ◽  
D. W. Allen
Keyword(s):  
Thin Film ◽  
Integrated Circuits ◽  
Semiconductor Device ◽  
Temperature Measurements ◽  
Spectral Radiance ◽  
Measurement Technology ◽  
Test Bed ◽  
Wafer Temperature ◽  
Thin Film Thermocouples ◽  
Wafer Manufacturing

ABSTRACTRapid thermal processing (RTP) is a key technology for the cluster tool, single wafer manufacturing approach that is used to produce integrated circuits at lower cost with reduced line widths and thermal budgets. However, various problems associated with wafer temperature measurements and dynamic temperature uniformity have hindered the widespread use of RTP in semiconductor device manufacturing. The current technology for calibrating the radiometers employs a thermocouple instrumented wafer. We have accomplished improvements in the accuracy of these measurements through the use of thin-film thermocouples and the new Pt/Pd thermocouple system. These new calibration wafers can reduce the uncertainty in wafer temperature measurement technology by (1) reducing the perturbation due to heat transfer at the thermocouple junctions and (2) replacing conventional thermocouples with the superior Pt/Pd system. The thin-film thermocouples were calibrated using proof specimens fabricated with the Si 200 mm wafers and evaluated in the NIST RTP sensor test bed.The commercial type K thermocouples yielded temperature measurements within 4 °C of the thin-film Rh/Pt and Pt/Pd thermocouples on the 200 mm calibration wafer between 725°C and 875 °C. The Pt/Pd thin-film thermocouples proved less durable than the Rh/Pt thin films and the limitations of these systems are discussed. We also present a comparison of the radiometric measurements with the thermocouple measurements using a model estimating the wafer temperature from its spectral radiance temperature.

Accurate and Precise Surface Temperature Measurements Up to 1500°C Using Thin Film Thermocouple Sensors

2021 ◽  
Author(s):  
Siqing Liu ◽  
Franklin L. Duan ◽  
Zhonglin Ji ◽  
Ziyi Xie ◽  
Zhiliang Hong ◽  
...  
Keyword(s):  
Thin Film ◽  
Surface Temperature ◽  
Temperature Measurements ◽  
Thin Film Thermocouple
Sign in / Sign up

Export Citation Format

Share Document