| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a crystal oscillator having a mesa structure with an inclined edge on at least one of top and back surfaces thereof with good mass-productivity.SOLUTION: An etching-resistant mask 21 including the following photoresist pattern 17a is formed by using a grayscale exposure process on a planned area of a piezoelectric wafer 11, where a mesa structure is to be formed; and in the photoresist pattern 17a, thickness of a portion Y corresponding to an edge of the mesa structure decreases toward an end of the portion Y. The wafer after the formation of the etching-resistant mask 21 is treated with a wet etching solution to form an initial mesa portion 23 on the wafer. The wafer after the formation of the initial mesa portion 23 is treated in a dry etching atmosphere.SELECTED DRAWING: Figure 3 |
