Papers by Keyword: Silicon Substrates

Abstract: Chromium-free preferential etching techniques in combination with light optical microscopy were compared with the non-destructive Laser Scattering Tomography (LST) for the evaluation of crystal defect densities in Czochralski substrates grown under different conditions. Dichromate containing etching solutions (original Secco etch and dilute Secco etch) were included into the study as reference. The chromium-free etching solutions with high etch rates comprised mixtures of nitric, hydrofluoric and acetic acid with water (JEITA 1, MEMC). Those with low etch rates consisted of mixtures of nitric and acetic or propanoic acid with hydrogen peroxide which form peracetic or perpropanoic acid (Organic Peracid Etches). OPE solutions provide improved discrimination of different types of defects and work also on highly doped substrates. As a general result, it turned out that the defect densities determined by the preferential etching solutions applied were significantly higher than those evaluated by LST. Relatively close to the LST defect densities are those determined by original Secco etch for larger etch pits.

Abstract: Laser micromachining has been widely used for micro-component fabrication of various materials, such as silicon substrates where silicon wafer is ablated accurately and precisely through marking, scribing, drilling or dicing. Thermal damages can occur on the substrates when improper process parameters and methods are used. This paper presents a review on the micromachining of silicon substrates using conventional and novel lasers as well as water-assisted laser micromachining technologies. The basic concepts and approaches of the technologies are discussed along with the challenges to damage-free laser micromachining at commercially acceptable cutting rates.

Abstract: While batch wafer cleaning processes have been conventionally used in the semiconductor manufacturing for many years, the use of single wafer cleaning processes in the manufacturing has recently become increasingly widespread. Single wafer cleaning processes have the advantages of reducing particle and metal contamination, however, electric charge or electrostatic discharge phenomena occurring in these processes causes serious problems such as device destruction through insulation failure and circuit disconnection [1,2]. Well-known examples are the breakdown of the ultra-thin gate oxide and the dissolution of Cu wiring due to charging-up damage in de-ionized water rinsing, which occur during the single wafer wet cleaning process in semiconductor manufacturing. We investigated the problem of wafer defects caused by electrostatic discharge and characterized them using transmission electron microscope (TEM) and energy dispersive X-ray (EDX) analyses.

Abstract: Vertical GaN nano-columns arrays were grown on Au-coated silicon (111) substrate by Au+Ga alloy seeding method and pulsed flow of Gallium and ammonia using metalorganic chemical vapor deposition (MOCVD). A gold thin film was deposited on Si using an ion coating system. The Au coated Si substrate was annealed at 800 oC under hydrogen ambient for 5 min. The pre-deposition of gallium and nitrogen was performed for 60 sec to form Au+Ga and nitrogen solid solution, which acts as the initial nucleation islands. Then Gallium and ammonia were let in pulse method. Scanning electron microscopy (SEM) image reveals a vertical growth and cylindrical in shape GaN nano-column. From the sharp PL peak intensity it is clearly seen that the dislocation density is reduced considerably and the optical quality of the nano-column is improved.