form micro holes 3 the drie is an icp rie inductively coupled plasma reactive ion etching method the laser method employs a laser for drilling the micro drill method employs a micro drill micro diameter drill for drilling in the sandblast method micropowder is sprayed additionally the substrate is not limited to glass substrate 1 for example a ceramic a resin or a composite material thereof is also applicable as long as it has heat resistance higher than a melting temperature of a metal to be filled therein the thickness of the substrate is on the order of several ten micrometers u03bcm to several centimeters cm the diameter and depth of each micro hole are on the order of several nanometers nm to several millimeters mm there are no limitations in the number of micro holes to be formed on the substrate referring to fig2 b metal layers 7 are formed in the peripheries of openings of the plurality of micro holes 3 for example by sputtering and are patterned into a predetermined shape the shape of metal layers 7 is predetermined to assist in the formation of a bump shape described below an example of the metal layer underlayer is a layer of cr and then au sputtered with thicknesses of 30 nm and 500 nm respectively after coating photoresist thereon the resist is patterned by photolithography the au and then the cr are etched by use of the patterned resist as a mask referring to fig2 c and 5a a molten metal bath 67 and substrate 1 are disposed in a chamber 51 substrate 1.