Currently, it's not doable. For e-beam lithography, manufacturers are using them in large quantities for mask making. For directly making circuits, it's just not economically viable. In an IC where you have 20 to 30 masking levels, of which about 10 levels are critical and 2 to 3 are supercritical, e-beam will write those supercritical ones. No, it is not.
X ray is in reality just a proximity printing system.
You have a separation between the wafer and the mask. That separation can be reduced to zero if one is not worried about defects and mask damage. Actually it's not zero, because you have the photoresist layer in there. The problem is that people can't make a mask that is economical enough, that is controlled in defect and linewidth variation, and in overlay placements. The e-beam machine is not there.