| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a lithium tantalate (LT) substrate and its manufacturing method in which a comb-line pattern formed on a front surface of the substrate is prevented from being destroyed, further, the substrate is prevented from being cracked by a spark caused by charging-up of electric charges on the front surface of the substrate, and light transmitted through the substrate is prevented from being reflected on a rear surface of the substrate and returning to the front surface to degrade a resolution of the formed comb-line pattern in a photo-lithograph step. <P>SOLUTION: In a step of using an LT crystal to manufacture the LT substrate, the LT crystal is thermally treated longer than four hours in a holding temperature of 1200 to 1650°C under a low oxygen concentration atmosphere in any one of a cooling step after crystal growth, a thermal treatment step for thermal distortion removal and a polling treatment step. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
