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Practical selectivity window of selective epitaxial growth (SEG) using a H 2 /SiH 4 /Cl 2 cyclic chemical vapor deposition (CVD) system has been investigated with the batch-type vertical furnace equipment, replacing a conventional single-wafer H 2 /dichlorosilane/HCl CVD system. The process temperature was less than 700 • C, which is suitable for a low thermal budget process applicable to next-generation memories including vertical pn-diode switches. Selectivity loss is quantified by an in-line inspection tool to determine the practical number of selectivity losses. The H 2 /SiH 4 /Cl 2 cyclic CVD system provides an excellent capacity of 40 wafers per batch. Selectivity loss, which is one of the most crucial features in the SEG process for the diode application, is controlled with both the amount of SiH 4 and Cl 2 and the period of gas supply, and the practical number of selectivity loss is confirmed to be less than 100 in 200 mm wafers. Without high temperature annealing in hydrogen ambient, low temperature cyclic SEG in the batch reactor ensures the clean interface and improved crystalline quality of SEG-Si, as well as high throughput.

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In this study, the enhancement of the silicon etch rate with the heavy doping of phosphorus and arsenic was studied during cyclic selective epitaxial growth process using batch-type equipment. The reaction between molecular chlorine and heavily doped silicon was stimulated during the initial stage of cyclic SEG process at low temperature lower than 700° to induce voids at the interface. Heavy doping of n-type dopants into active regions also brought about the decrease in the growth rate of SEG process. It was possible to attain a stable process window by the elaborate control of total amount ratio of SiH4/Cl2. The window provided the robust interface between SEG silicon and active regions as well as the selectivity to an oxide layer. Vertical diodes which were realized within the window revealed eligible on- and off-current characteristics for cell switches applicable to next generation cross-point memories.