the wet etching step in a still further alternative embodiment a dry etching process may be used to form roughened surface 17 a on bpsg layer 17 referring now to fig9 following the formation of roughened surface 17 a a layer of polysilicon 24 is deposited on top of bpsg layer 17 in one embodiment polysilicon layer 24 is formed of amorphous silicon or smooth polysilicon and is deposited on top of bpsg 17 layer using a cvd step although other procedures may also be used polysilicon layer 24 is preferably 250 1000 angstroms in thickness and still more preferably 400 600 angstroms in thickness in a still further preferred embodiment polysilicon layer 24 will be about 500 angstroms in thickness when polysilicon layer 24 is formed of amorphous silicon or smooth polysilicon the inner surface 24 a of polysilicon layer 24 will naturally follow the roughened contour of surface 17 a thereby giving inner surface 24 a a roughened texture outer surface 24 b of polysilicon layer 24 will also conform to surface 17 a thereby giving outer surface 24 b a roughened texture in an alternative embodiment polysilicon having intrinsic surface roughness may be used to form layer 24 in this alternative embodiment after deposition of polysilicon layer 24 polysilicon layer 24 is preferably seeded with a disilane and then annealed in order to form roughened inner surface 24 a referring now to fig1 after polysilicon layer 24 having roughened surfaces 24 a 24 b is disposed on top of bpsg layer 17 the structure shown in fig9 is subjected to a cmp process wherein portions of.