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EP-4742877-A1 - DIELECTRIC ELEMENT AND METHOD FOR MANUFACTURING SAME

EP4742877A1EP 4742877 A1EP4742877 A1EP 4742877A1EP-4742877-A1

Abstract

This dielectric element includes a substrate, an underlayer disposed on the substrate, and a nitride thin film disposed on the underlayer, the underlayer is composed of any one element selected from rare earth elements, and the nitride thin film contains scandium, and a Group 13 element and a Group 15 element in the periodic table.

Inventors

  • HIRATA KENJI
  • AKIYAMA MORITO
  • UEHARA MASATO
  • TABARU TATSUO
  • YAMADA HIROSHI
  • Anggraini Sri Ayu

Assignees

  • National Institute Of Advanced Industrial Science and Technology

Dates

Publication Date
20260513
Application Date
20240705

Claims (13)

  1. A dielectric element comprising: a substrate; an underlayer disposed on the substrate; and a nitride thin film disposed on the underlayer, wherein the underlayer is composed of any one element selected from rare earth elements, and the nitride thin film contains scandium, and a Group 13 element and a Group 15 element in the periodic table.
  2. The dielectric element according to Claim 1, wherein the nitride thin film contains more than 43 atom% of scandium relative to a total number of atoms of the Group 13 element and scandium.
  3. The dielectric element according to Claim 1, wherein the nitride thin film contains 0 atom% or more and 43 atom% or less of scandium relative to a total number of atoms of the Group 13 element and scandium.
  4. The dielectric element according to Claim 1, wherein the nitride thin film contains 13 atom% or more and 43 atom% or less of scandium relative to a total number of atoms of the Group 13 element and scandium.
  5. The dielectric element according to any one of Claims 1 to 4, wherein the underlayer has a thickness of 1180 nm or less.
  6. The dielectric element according to any one of Claim 1 to 4, wherein the underlayer is composed of any of the group consisting of yttrium, lutetium, scandium, gadolinium, and cerium.
  7. The dielectric element according to Claim 5, wherein the underlayer is composed of any of the group consisting of yttrium, lutetium, scandium, gadolinium, and cerium.
  8. The dielectric element according to any one of Claims 1 to 4, wherein the Group 13 element is aluminum, and the Group 15 element is nitrogen.
  9. The dielectric element according to Claim 5, wherein the Group 13 element is aluminum, and the Group 15 element is nitrogen.
  10. The dielectric element according to Claim 6, wherein the Group 13 element is aluminum, and the Group 15 element is nitrogen.
  11. The dielectric element according to Claim 7, wherein the Group 13 element is aluminum, and the Group 15 element is nitrogen.
  12. The dielectric element according to any one of Claim 1 to 4 that is used in any one or more selected from the group consisting of a transistor, an inverter, a ferroelectric memory, a vibration sensor, an ultrasonic sensor, a microphone, a filter, an AI semiconductor, a power semiconductor, a piezoelectric generator, and a MEMS device.
  13. A method for manufacturing a dielectric element, the method comprising: a step of forming an underlayer on a substrate; and a step of forming a nitride thin film on the underlayer, wherein any one element selected from rare earth elements is used as a raw material of the underlayer, and scandium, and a Group 13 element and a Group 15 element in the periodic table are used as raw materials of the nitride thin film.

Description

TECHNICAL FIELD The present invention relates to a dielectric element and a method for manufacturing the same. Priority is claimed on Japanese Patent Application No. 2023-111711, filed July 6, 2023, the content of which is incorporated herein by reference. BACKGROUND ART Nitride thin films exhibiting excellent piezoelectric performances are in use in a variety of devices, for example, FBAR high pass filers for mobile communication, piezoelectric sensors, energy harvesting devices, MEMS microphones, and fingerprint authentication sensors. In recent years, diverse and highly functional sensors have been in demand, and there has been a demand for further improvement in piezoelectric performances for nitride thin films due to the ongoing increase in frequency for communication. For example, Patent Document 1 discloses an AlN thin film to which Sc is added, that is, a ScAlN thin film for the purpose of enhancing piezoelectric performances. At the moment, ScAlN thin films are in practical use in elastic wave filters. Citation List Patent Document Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2019-145677 SUMMARY OF INVENTION Technical Problem For ScAlN thin films, it is known that there is a tendency that the piezoelectric constant (d33) that represents the magnitude of the piezoelectric performances is maximized at a Sc concentration of 43 atom% but the piezoelectric performances deteriorate at equal or higher Sc concentrations due to the deterioration of crystallinity, the formation of a secondary phase, or the like. Incidentally, according to theoretical calculation, there is a possibility that the piezoelectric constant may improve when a higher concentration of Sc is made to form a solid solution in AIN. That is, it can be said that curbing the deterioration of crystallinity or the formation of a secondary phase leads to a technique of improving the piezoelectric performances by incorporating Sc at a high concentration. It can be considered that when it becomes possible to stably produce ScAlN thin films containing Sc at a high concentration, the production of elastic wave filters enabling transmission bands to be arbitrarily set to high frequencies far higher than several GHz levels becomes possible. In addition, ScAlN thin films are confirmed to be ferroelectric, are highly spontaneously polarizable, and are thus expected to be applied to ferroelectric memories. However, when polarization is reversed, the applied voltages are high, and the power consumption thus becomes high at the time of applying ScAlN thin films to memories. The applied voltages can also be decreased by thinning the film thicknesses, but methods therefor are limited, and it is considered that other measures are also required. The applied voltages having a tendency of decreasing when Sc concentrations are increased have been found by experiments, and at the moment, there is a desire for the production of ScAlN thin films containing Sc at high concentrations. Therefore, the present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a dielectric element that maintains ferroelectricity and has excellent piezoelectric performances and a method for manufacturing the same. Solution to Problem The main points of the present invention are as described below. [1] A dielectric element according to one aspect of the present invention including a substrate, an underlayer disposed on the substrate, and a nitride thin film disposed on the underlayer, in which the underlayer is composed of any one element selected from rare earth elements, and the nitride thin film contains scandium, and a Group 13 element and a Group 15 element in the periodic table.[2] In the dielectric element according to [1], the nitride thin film may contain more than 43 atom% of scandium relative to a total number of atoms of the Group 13 element and scandium.[3] In the dielectric element according to [1], the nitride thin film may contain 0 atom% or more and 43 atom% or less of scandium relative to a total number of atoms of the Group 13 element and scandium.[4] In the dielectric element according to [1], the nitride thin film may contain 13 atom% or more and 43 atom% or less of scandium relative to a total number of atoms of the Group 13 element and scandium.[5] In the dielectric element according to at least any of the group consisting of [1] to [4], the underlayer may have a thickness of 1180 nm or less.[6] In the dielectric element according to at least any of the group consisting of [1] to [5], the underlayer may be composed of any of the group consisting of yttrium, lutetium, scandium, gadolinium, and cerium.[7] In the dielectric element according to at least any of the group consisting of [1] to [6], the Group 13 element may be aluminum, and the Group 15 element may be nitrogen.[8] The dielectric element according to at least any of the group consisting of [