An electronic element having a sufficient dielectric strength remarkably superior to any of the conventional ones. In this element, a conductive wire pattern is formed on the surface of a substrate which is insulative at least in its surface, and an insulating layer is so formed as to cover the substrate and the wire pattern either partially or entirely. The insulating layer is composed of a silicon nitride film where the oxygen content is less than 10 atomic percent at least in the vicinity of a step portion of the wire pattern. There is also provided a method of producing such electronic element, wherein the insulating layer is formed by plasma enhanced CVD under the conditions that the following relationship among a film forming temperature T (.degree. C.), an ion flux I (A) and a film forming speed v (nm/min): T.gtoreq.-651 (I/v)+390, 150.ltoreq.T.ltoreq.350 (where the ion flux denotes the current (A) per 60.times.60 cm.sup.2). According to this method, an insulating film of a high withstand voltage with a great dielectric strength can be obtained stably at a high yield rate.