Oxide single crystal composite substrate and method for manufacturing the same

JP2026101555APending Publication Date: 2026-06-22SHIN ETSU CHEMICAL CO LTD
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Patent Information

Authority / Receiving Office
JP · JP
Patent Type
Applications
Current Assignee / Owner
SHIN ETSU CHEMICAL CO LTD
Filing Date
2024-12-10
Publication Date
2026-06-22

AI Technical Summary

Technical Problem

Existing methods for manufacturing thin films of lithium tantalate (LT) and lithium niobate (LN) face challenges in achieving nanometer-level uniformity and maintaining polarization and crystallinity while preventing polysilicon layer resistance degradation due to hydrogen exposure.

Method used

A two-step heat treatment process is employed, first at 300°C or higher in a reducing atmosphere to restore polarization and crystallinity, followed by a second heat treatment in a non-reducing atmosphere to diffuse hydrogen and stabilize the polysilicon layer, with specific hydrogen concentration gradients to prevent excessive dangling bond exposure.

Benefits of technology

The method achieves both the recovery of polarization and crystallinity in piezoelectric oxide single-crystal thin films and maintains a good Q value by stabilizing the polysilicon layer, ensuring optimal performance of SAW devices.

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Abstract

The present invention provides an oxide single-crystal composite substrate that achieves both the recovery of polarization and other properties of piezoelectric oxide single-crystal thin films generated during manufacturing and the non-low resistance of the polysilicon layer, while also obtaining a good Q value. [Solution] A method for manufacturing an oxide single crystal composite substrate, wherein a piezoelectric oxide single crystal thin film is laminated on a polysilicon layer laminated on a silicon substrate, comprising the steps of: first, performing a heat treatment on the oxide single crystal composite substrate at a temperature of 300°C or higher in an atmosphere containing hydrogen with a hydrogen concentration of 1% or more; and second, performing a heat treatment at a temperature exceeding 400°C in a non-reducing atmosphere, wherein the hydrogen concentration near the interface between the silicon substrate and the polysilicon layer is 1.5 × 10⁻⁶. 18 atoms / cm 3 As a result, the hydrogen concentration in the polysilicon layer gradually decreases as it moves away from the interface to 1.0 × 10⁻⁶. 18 atoms / cm 3 Perform the following steps to achieve the following result.
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