the present invention will now be described more fully hereinafter with reference to the accompanying drawings , in which preferred embodiments of the invention are shown . this invention may , however , be embodied in many different forms and should not be construed as limited to the embodiments set forth herein ; rather , these embodiments are provided so that this disclosure will be thorough and complete , and will fully convey the scope of the invention to those skilled in the art . in the drawings , the thicknesses of layers and regions are exaggerated for clarity . like numbers refer to like elements throughout . it will also be understood that when a layer is referred to as being &# 34 ; on &# 34 ; another layer or substrate , it can be directly on the other layer or substrate , or intervening layers may also be present . the formation of integrated circuit devices including hemispherical grained ( hsg ) silicon layers according to the present invention will now be discussed with reference to fig6 - 8 . in particular , a memory cell transistor can be formed on a substrate 40 , and an insulating layer 42 can be formed on the memory cell transistor and on the substrate 40 . a contact hole can be formed in the insulating layer 42 by forming a photoresist mask on the insulating layer 42 and selectively etching portions of the insulating layer 42 exposed through the photoresist mask . moreover , the contact hole 44 can expose a source / drain region of the memory cell transistor , and an anisotropic etch can be used to form the contact hole 44 . a conductive layer is then formed on the surface of the insulating layer 42 , and this conductive layer is coupled to the semiconductor substrate 40 through the contact hole 44 . the conductive layer is then patterned using photolithographic and etch steps to provide a first sub - layer 46 of the lower capacitor electrode coupled to the semiconductor substrate 40 through the contact hole 44 as shown in fig6 . moreover , the conductive layer , and thus the first sub - layer 46 , can be formed from doped polysilicon or doped amorphous silicon . the surface area of the lower capacitor electrode can be increased as shown in fig7 . a second sub - layer 48 having a roughened surface , such as a hemispherical grained ( hsg ) silicon layer , is provided to increase the surface area of the lower capacitor electrode . in particular , hemispherical grained ( hsg ) silicon seeds can be formed on the surface of the first sub - layer 46 using either silane ( sih 4 ) or disilane ( si 2 h 6 ). the hsg seeds are then grown by thermally treating the lower capacitor electrode to form the hsg silicon layer on the first sub - layer 46 . the surface area of the lower capacitor electrode can thus be increased . the second sub - layer 48 can be formed by a selective hsg silicon formation technique , or the second sub - layer 48 can be formed by a blanket hsg silicon formation technique wherein the hsg silicon layer is formed on the first sub - layer 46 as well as the insulating layer 42 and then removed from the insulating layer 42 . at this point , the second sub - layer 48 can be undoped . the second sub - layer 48 , however , is preferably doped with the same dopant used to dope the first sub - layer 46 . for example , it is preferable to dope the second sub - layer 48 with phosphorous if the first sub - layer 46 is doped with phosphorous . in particular , the second sub - layer 48 can be doped by flowing a dopant gas over the second sub - layer at a predetermined flow rate while annealing the second sub - layer 48 for a predetermined time and at a predetermined temperature . for example , the annealing step can be performed at a temperature in the range of 560 ° c . to 630 ° c . while flowing the dopant gas for a period of time in the range of one to ten minutes . the dopant gas may be a gas including ph 3 or ash 3 . in addition , it may be desirable to provide a carrier gas such as nitrogen ( n 2 ), helium ( he ), or argon ( ar ) with the dopant gas . other gases may also be used . the annealing time should be determined so as not to significantly influence the production yield of the integrated circuit device . in particular , the annealing step is preferably performed for at least one minute and more preferably for a period of time between one and ten minutes . moreover , the dopant gas can flow at a rate of at least 1 sccm and preferably at a rate in the range of 1 sccm to 250 sccm . the doped second sub - layer 50 , such as a doped hsg silicon layer , is illustrated in fig8 . as discussed above , the doped hsg silicon layer is preferably doped with the same dopant used to dope the first electrode sublayer 46 . the dopant concentration of the hsg silicon layer can be controlled by controlling the flow rate of the dopant gas and the annealing time during which the dopant gas flows . furthermore , a dielectric layer 51 can be formed on the second sub - layer 50 , and a conductive layer 53 can be formed on the dielectric layer 51 as shown in fig8 . as shown in fig9 hsg silicon layers doped by out - diffusion according to the present invention can be used to provide capacitors having a reduced difference between the maximum ( cmax ) and minimum ( cmin ) capacitances . in fig9 the reference symbols , ▪, ▴, ▾, and ♦ indicate the capacitances respectively measured at the top , center , bottom , left , and right portions of the capacitor formed according to the present invention . as shown , the capacitance is highest at the center of the capacitor , while the capacitance is lowest at the bottom of the capacitor . as further shown , progressively lower capacitances are obtained by measuring at the center , right , bottom , left , and then top of the capacitor . a minimum capacitance cmin of between 0 . 9 pf and 1 . 0 pf can be obtained at any portion of the capacitor with an applied voltage of between - 1 . 5 v and + 1 . 5 v . a maximum capacitance cmax of only slightly more than 1 . 0 pf can be obtained with an applied voltage of between 0 . 0 v and - 0 . 5 v . a cmin / cmax ratio of at least 0 . 9 can thus be obtained thereby providing stable capacitor operation . in fig9 the reference symbol &# 34 ;+-&# 34 ; indicates a capacitance variation of a capacitor without an hsg silicon layer on the storage node . here , the capacitance is a little higher than 0 . 6 pf which is significantly lower than that of a capacitor having a hsg silicon film on the lower capacitor electrode . as discussed above , a hemispherical grained ( hsg ) silicon layer can be formed and then doped by flowing a dopant gas across the hsg silicon layer while annealing the silicon layer . the dopant concentrations of the upper and lower electrodes can thus be increased thereby increasing the cmin value and allowing a cmin / cmax ratio of 0 . 9 or greater to be obtained . stable capacitor operations can thus be provided thereby increasing the operational reliability of an integrated circuit device including the capacitor thus formed . the performance of dynamic random access memory devices including capacitors formed according to the present invention can thus be improved . in the drawings and specification , there have been disclosed typical preferred embodiments of the invention and , although specific terms are employed , they are used in a generic and descriptive sense only and not for purposes of limitation , the scope of the invention being set forth in the following claims .