Application to production of process and the trench capacitor which it backs up etches polysilicon

摘要

(57) Abstract This invention, regards our discoveries that flat the etching front is formed substantially by using the etching gas of combination of specification for use of polysilicon etching. Speaking generally, process of this invention, although form of the etching front is controlled while etching back the polysilicon, is useful. Typically, as for process, using the plasma which it occurs from the plasma source gas which includes the combination of specification of the reactivity kind which etches polysilicon selectively, it includes the fact that it etches polysilicon isotropically. The plasma source gas, approximately 80 volume % the empty approximately 95 volume % to fluorine content gas and, approximately 5 volume % includes with the addition gas which is selected from the group which consists of the empty approximately 20 volume % to bromine content gas, the chlorine content gas, the iodic content gas, or those combinations. The method this invention which is used in order to accomplish the pit etchback of the polysilicon filling up trench inside the base substance being desirable a) includes the step which prepares the trench which was formed inside semiconductor structure, as for this structure includes one which at least is repeated on one which is repeated on the surface of the base substance and the base substance gate dielectric layer, and gate dielectric layer etching barrier layer at least, in order b) to be piled up on the side wall and the bottom of etching barrier layer, and the trench, in order to be piled up on step and c) conformal dielectric film which form the conformal dielectric film, fills up the trench at layer of polysiliconStep and d) using the plasma which it occurs from the plasma source gas which includes the reactivity kind which etches polysilicon selectively, the polysilicon inside the trench step which is etched isotropically furthermore it includes to specified depth, this plasma source gas, approximately 80 volume % the empty approximately 95 volume % to fluorine content gas and, approximately 5 volume % with the empty approximately 20 volume % to bromine content gas, the chlorine content gas, the iodic content gas, or includes with the addition gas which is selected from the group which consists of those combinations. Also the method of forming the trench capacitor inside the monocrystal silicon base substance is disclosed, this trench capacitor includes the dielectric color and the buried strap.