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Study On Laser Assisted Microprocessing For Fabrication Of Monolithic OEICs

Posted on:2005-06-19Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y F WuFull Text:PDF
GTID:1118360152498264Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Monolithically optoelectronic integrated circuits (OEICs) integrate optoelecronic components and electronic components onto one chip. It has the advantages of high speed, high reliability, cost-effective, and small size. In applications such as phased array radars and fiber-optic communication systems, monolithic OEICs will be the key components. However, The fabrication of monolithic OEICs is confronted with the incompatibility problem between optoelectronic and electronic components. Though enormous efforts have been made to overcome this difficulty, the problem has not been solved perfectly. Laser assisted microprocessing of semiconductors have the advantages of "low temperture processing" and "direct writing". It is promising to use this technology in the fabrication of OEICs to solve the incompatibility problem.The purpose of this work is to develop the laser microprocessing technologies for the fabrication of monolithic OEICs. The main conclusions and contributions include:1) As the fundamentals of the fabrication of monolithically integrated optical receiver, a planar InGaAs/InP PIN photodiode has been fabricated using laser assisted microprocessing. The responsivity of the fabricated Planar InGaAs/InP PIN photodiodes arrived 0.21A/W. Laser induced diffusion and laser assisted alloying were introduced, and the experimental results were presented.2) A computer-controlled temperature measurement system for the small region in laser assisted microprocessing has been developed. The system can realize the real time temperature measurement of the small laser-exposed region nonintrusively. The system reached a temperature resolution of 0.2 ℃. The measurement region diameter of 18 μm was also obtained.The system can be used to measure the tmerature distributions and the temperature changing versus time in the small region.3) Some precise alignment technologies in the laser assisted microprocessing are proposed, a) Algorithm had been designed to cooperate the move of themotorized stage and the acquisition of temperature data. It follows that the measurement of temperature distribution and the accurate location of the highest temperature region were realized, b) The requirement of focusing is stringent in the temperature measurement of the laser-processed region. A focusing method was proposed to solve this problem. The method utilized the calculated focal lengths at different wave bands, and the measured temperature distributions of the same object at different objective distances, c) A method has been proposed to realize the precise alignment between the small invisible laser spot and the diffusion window, d) The alignment between the diffusion window and the etching area in the second ion mass spectrometry analysing has also been realized.4) The temperature rise in a semiconductor substrate induced by a 10.6 μ m focused CW CO2 laser beam has been investigated experimentally. The thermal runaway phenomenon was observed. Then its mechanism was analyzed. A numerical method has been proposed to calculate the stable temperature rise when the optical absorptivity of the substrate increases with the substrate temperature. Then methods including preheating the substrate and feedback controlling the temperature of the exposed region have been proposed to avoid the thermal runaway phenomenon.5) Two methods have been proposed to uniform the temperature distribution in the small processed region, a) It was first proposed to uniform the temperature distribution through modulating of the intensity incident on the surface using a mask. The key of this method is calculating the laser intensity distribution that can induce uniform temperature rise in the diffusion region. The numerical method to solve this problem was described. The results show that when the mean temperature rise in the processed region is about 500 K, the maximum temperature difference of 3.9 K can be achieved, and the temperature distribution approaches "top-hat", b) Another method changes the laser intensity distribution at the focal plane using binary optical elements (BOE). The ideal intensity distribution was calculated firstly. And a genetic algorithm was proposed to design the BOE. The results suggest that this method can also uniform the...
Keywords/Search Tags:monolithically optoelectronic integrated circuits, laser assisted microprocessing, temperature measurement of small region, thermal runaway, uniformation of temperature distribution of small region, alignment technology
PDF Full Text Request
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