RF Test Gage R&R Improvement
Advanced cell phone architectures require high performance multi-throw RF switches. Reliably measuring the very low RF power levels of the third harmonic signal of these switches is a significant challenge. This paper discusses the use of Gage studies to identify and measure the sources of variation in RF probe measurements. Tester Gage study results are presented. Evaluations of factors including test instrument repeatability, probe card wear, probe tip planarity, probe pressure, and probe placement within the bond pad are presented. The data indicated the repeatability of the test instrumentation was very good. However, the reproducibility needed improvement. The most significant factor in achieving reproducible RF measurements is sufficient probe contact. A method to provide probe operators feedback of sufficient probe contact was developed and implemented. As a result, the Gage study passed. Further, the percentage of die requiring re-test was reduced significantly. INTRODUCTION State of the art multi-throw RF switches need to meet third harmonic performance specifications in the range of -30 to -40 dBm power at RF frequencies in the range of 824 to 915 MHz. -30 and -40 dBm correspond to 1uW and 100nW of power respectively. To provide known good switch die for Skyworks Front End Modules (FEM), the Skyworks pHEMT wafer fab performs RF probe testing on all switch die. Reliably making these low power measurements at high frequencies in a probe test environment requires advanced test instruments and rigid production discipline. The Skyworks Quality System requires Gage studies be performed on all measurement equipment. Further, Skyworks customers can and do request measurement system Gage study results.
Yield Improvement Methodology in a pHEMT GaAs Fabrication Facility
Shrinking feature sizes, increasing circuit complexity, and stringent RF performance requirements make achieving high yield a considerable challenge. This paper presents a method to improve yield in a pHEMT GaAs wafer fabrication facility. A practical team approach and applied technical methods to support an effective yield improvement effort are discussed. Several case studies are presented to illustrate the efforts and success of the Skyworks-Woburn GaAs Fab Yield Improvement Team.
Experimental study of thermal modeling for stratospheric platform airships
R&D work on the Japanese stratospheric platform airship is discussed from the viewpoint of the thermal modeling. The work includes two experiments on the thermal characteristics of the 25m-long airship and the 35m-long PV-equipped airship model. The validity of the current thermal model was confirmed by comparing the calculated results with the measured data. The other important work is the Ground-to-Stratosphere (GTS) flight test. A 47mlong airship-shaped balloon was flown to the stratosphere. The flight simulation program into which the thermal model was integrated, was developed and applied successfully to predict the ascent behavior and the flight trajectory.