Formation of very low-resistance aluminum layer on AlN ceramics by TEA CO/sub 2/ laser irradiation for direct laser writing of electric circuit

To make a low electrical resistance Al line, i.e. to make a thick Al layer, we selected a transversely excited atmospheric (TEA) CO/sub 2/ laser with a long penetration depth. AlN shows a moderate absorption coefficient in the mid infrared range over 10 /spl mu/m and it is possible to modify the surface of the AlN ceramics by irradiation with a TEA CO/sub 2/ laser. The technique is applicable to the drawing of an electrical circuit. The aluminum thickness dependence on irradiation shot number is also presented.