Abstract: A hole forming method with a laser beam and a hole forming laser apparatus improves the efficiency of hole formation without deterioration in the quality of the formed hole. In a hole forming method for forming holes in a plurality of articles by irradiation with a condensed laser beam, the laser beam is switched in succession to plural working optical axes, thereby forming holes in succession in the articles positioned respectively on the working optical axes.

Abstract: A substrate having a small-diameter hole is taken from the air and placed in a boiling vapor and/or boiling liquid in a first treatment tank of a vessel having a boiling heater, whereupon the pressure of the air in the small-diameter hole exceeds atmospheric pressure by an amount equivalent to the partial pressure of the air in the hole. Accordingly, the air cannot remain in the hole but is instead expelled to the outside. As a result, the interior of the microhole is replaced entirely by the boiling vapor and/or boiling liquid. Next, without being brought into contact with the external air, the substrate is contacted with a non-boiling liquid inside a second treatment tank, thereby preventing external gas from flowing back into the small-diameter. The non-boiling liquid and the boiling vapor and/or boiling liquid are soluble in each other. As a result, the two are unified and introduced to the small-diameter hole in the form of a liquid.