In 
wafer semiconductor manufacture, a method of 
etching an 
arsenic doped polysilicon layer down to a patterned boro-phospho-
silicate-glass (BPSG) layer provided with a plurality of openings with an uniform etch rate is disclosed. The method relies on a combination of both 
system and process improvements. The 
system improvement consists to hold the 
wafer in the reactor during the etch process with an electrostatic chuck device to have a perfect 
plasma environment around and above the 
wafer. On the other hand, the 
process improvement consists in the use of a non 
dopant sensitive and not selective 
chemistry. A NF3 / CHF3 / N2 gas mixture with a 11 / 8.6 / 80.4 ratio in percent is adequate in that respect. The etch 
time duration is very accurately controlled by an optical etch endpoint detection 
system adapted to detect the intensity 
signal transition of a CO line at the BPSG layer 
exposure. The process is continued by a slight overetching. When the above method is applied to the doped polysilicon strap formation in 
DRAM chips, excessive or insufficient 
etching of the polysilicon layer is avoided, so that the doped polysilicon strap thickness is thus much more uniform, opening to opening, within a wafer.