Method for growing 6-inch lithium tantalate crystal

Abstract

The invention relates to the technical field of piezoelectric crystals, in particular to a method for growing a 6-inch lithium tantalate crystal, which comprises the following steps of: a) filling a lithium tantalate raw material into a platinum-iridium alloy crucible, vacuumizing, and filling nitrogen to positive pressure; b) raising the temperature to 1600-1645 DEG C to melt the raw materials; c) descending the seed crystal, stopping descending when the seed crystal descends to the 0 position of the crucible opening, and clearing the weighing weight to zero; d) adjusting the seeding temperature and the descending or ascending rate of the seed crystal according to the weight change of the seed crystal, and enabling the crystal to grow automatically after the seeding is completed, and e) controlling the crystallization rate of the crystal by adjusting the lifting speed of the shouldering growth and the equal-diameter growth in real time, and pulling up the crystal after the crystal growth is completed, so that the crystal is separated from the molten liquid.

Description

technical field [0001] The invention relates to the field of piezoelectric crystals, in particular to a method for growing 6-inch lithium tantalate crystals. Background technique [0002] In recent years, due to the widespread use of high-frequency and multi-frequency communication in wireless communication represented by mobile phones, the demand for surface acoustic wave filters (SAW) has increased significantly, and the quality requirements are also higher. As a piezoelectric crystal, lithium tantalate crystals can be processed into wafers and are widely used in SAW devices. Since large-sized wafers help device manufacturers to save raw materials and reduce production costs, there is a demand for high-quality large-sized lithium tantalate crystals at this stage. Large, especially 6-inch lithium tantalate crystals. [0003] However, due to the large size of the 6-inch lithium tantalate crystal, during the crystal growth process, the temperature of the lithium tantalate ra...

AI Technical Summary

Problems solved by technology

The patent with the publication number CN104109904A discloses a seeding method for sapphire crystal growth by the Kyropoulos method. The patent discloses a method of controlling seeding by using the weight change of the seed crystal, which first records the weight of the seed crystal at 10 mm above the liquid surface , then record the weight of the seed crystal placed 30mm below the liquid surface for 10 seconds and then pull it back to 30mm above the liquid surface, and compare the weight changes of the two to confirm the test temperature. First, this patent uses the seed crystal to test the temperature below the liquid surface. It is easy to cause the seed crystal to melt too fast or crystallize too fast to cause the seed crystal to melt or the crystal is too large to be uncontrollable. At the same time, this method requires the seed crystal to rise and fall multiple times above and below the liquid surface for temperature testing, which is more complicated. high