| 摘要 |
PURPOSE:To perform a fresh printing, and to reduce a laser output to suppress a foreign matter by forming in advance an impurity layer on a region which contains a print forming position on a semiconductor substrate, and selectively annealing the layer by irradiating it with a laser light to form a discolored printing pattern. CONSTITUTION:Boron is added to the whole surface of a semiconductor substrate 1 or selectively thereto with a photoresist as a mask to form an impurity layer 2. Then, the region of the layer 2 is irradiated with a 1.0W pulse laser to open a hole having 0.3mm of diameter and 1.5-2.5mum of depth on the substrate 1. Heat is simultaneously generated at the substrate 1 by the radiation of the laser thereby to anneal the layer 2. An annealed region 4 of the width of approx. 0.4mm is formed on the periphery of the opened hole 3. When the laser is moved in plane to form the hole 3 of a predetermined pattern, the pattern region discolored in a black color is formed along the hole 3 to be formed as a symbol or a character.
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