Role of rapid photothermal processing in environmentally conscious semiconductor manufacturing

Compliance with the increasingly stringent environmental laws will force the phasing out of conventional methods for the manufacture of all semiconductor devices. Development of processes with the highest possible material and energy efficiencies is the heart of the present ecological preservation efforts. Besides other benefits, rapid isothermal processing (RIP) also uses less energy than furnace processing. Further increase of material and energy efficiencies is possible by using rapid photothermal processing. Central to this method is the use of quantum photoeffects in conventional RIP systems. This approach can be consolidated with advanced chemical vapor deposition methods that further lower the wastages leading to systems that can give significant improvements over those presently used. Key experimental results and possible future directions are presented.

Problems with The Concept of Thermal Budget: Experimental Demonstrations

ABSTRACTUp to now, kinetic effects in rapid thermal processing (RTP) have been assessed using the concept of thermal budget, with the idea that thermal budget minimization should minimize dopant diffusion and interface degradation. This work highlights shortcomings with that principle. Experiments comparing directly the rate of Si chemical vapor deposition with that of dopant diffusion show how thermal budget minimization can actually worsen diffusion problems rather than mitigate them. We present a straightforward framework for improving the results through comparison of activation energies of the desired and undesired phenomena. This framework explains the experimental results and provides strong kinetic arguments for continued development of rapid isothermal processing and small batch fast ramp methods.

Defect Reduction and Improved Device Performance using Rapid Isothermal Diffusion in Silicon

ABSTRACTQuantum photoeffects associated with photons of wavelength less than 0.8 micron lead to higher bulk and surface diffusion coefficients. We have exploited this fundamental property in designing rapid isothermal processing (RIP) systems for shallow junction formation in silicon. A detailed comparative study of diffusion, metallization and CVD with and without high energy photons has been carried out. The results show that microscopic defects, cycle time and processing temperature is lower than what can be achieved byconventional methods is realized by using photons in the ultra violet (UV) and vacuum ultra violet (VUV) spectrum.

How Rapid Isothermal Processing Can be a Dominant Semiconductor Processing Technology in the 21st Century

The growth and advancement of the electronic and photonic industry in the 21 st century hinges on revolutionary new processing techniques that will overcome some of the most fundamental limitations of conventional methods. Rapid isothermal processing (RIP) based on incoherent radiation as the source of optical and thermal energy can play a major role in designing processing systems that offer the tight process control, low thermal budgets, low microscopic defects, high throughput and high yields required for almost every semiconductor device. Conventional RIP can be further optimized by fully exploiting the contribution of quantum photoeffects. The improved performance and reliability offered by RIP will make it the mainstream technology for the green manufacture of microelectronics, optoelectronics, solar cells, flat panel displays and microelectromechanical systems. Key issues related to the cost of ownership, design of RIP system based on the full utilization of photo–thermal effects and model based control systems are described. New experimental results for a number of processing steps are provided. These results demonstrate the importance of advanced RIP systems in providing better performance and lower defects for future devices.

Low Thermal Budget Processing Of Organic Dielectrics

Low dielectric constant organic materials are ideal for use as interconnect dielectrics forintegrated circuits. As compared to silicon dioxide, organic dielectrics with K <3.84 reducepower dissipation, crosstilk and RC delays in interconnects. Curing is essential afterdeposition of these materials to initiate polymerization reactions and form films of desirableelectrical properties. For high performance and reliability, low thermal budget processing isa necessity. Rapid isothermal processing (RIP) based on the use of dual spectral sources isa potential technique to lower the thermal budget. In this paper, we demonstrate the role ofphotoeffects in the curing of polyimide films (K∼2.6) using a rapid isothermal processor witha dual spectral source (Tungsten Halogen and vacuum ultra violet (VUV) lamps) as a sourceof optical and thermal energy. Lamp configurations that allowed a greater availability of ultraviolet and vacuum ultra violet photons on the film to initiate physical and chemical processesallowed a lower curing temperature to achieve the same level of immidization. Furthermore, these samples also gave the lowest leakage current and film stress. Therefore, the rapidheating and cooling features of rapid isothermal processing in conjunction with lowerprocessing temperature through the use of high energy photons to enhance surface reactionsgive superior film properties