Film structure and method for producing the same
A film structure comprises a substrate and a buffer film formed on the substrate. The substrate is a 36° to 48° rotated Y-cut Si substrate, or the substrate is a SOI substrate comprising a base substance made of the 36° to 48° rotated Y-cut Si substrate, an insulating layer on the base substance, and a SOI layer made of a Si film on the insulating layer, and a Miller index of a crystal plane of an upper surface of the SOI layer is equal to the Miller index of a crystal plane of an upper surface of the base substance. The buffer film comprises ZrO 2 epitaxially grown on the substrate.
1 . A film structure comprising:
a substrate; and
a buffer film formed on the substrate;
wherein;
the substrate is a 36° to 48° rotated Y-cut Si substrate, or
the substrate is a SOI substrate comprising a base substance made of a 36° to 48° rotated Y-cut Si substrate, an insulating layer on the base substance, and a SOI layer made of a Si film on the insulating layer,
a Miller index of a crystal plane of an upper surface of the SOI layer is equal to the Miller index of a crystal plane of an upper surface of the base substance, and
the buffer film comprises ZrO 2 epitaxially grown on the substrate.
2 . The film structure according to claim 1 , further comprising a metal film epitaxially grown on the buffer film.
3 . The film structure according to claim 2 , wherein the metal film comprises Pt.
4 . The film structure according to claim 2 , further comprising a SRO film epitaxially grown on the metal film.
5 . The film structure according to claim 4 , further comprising a piezoelectric film epitaxially grown on the SRO film.
6 . The film structure according to claim 5 , wherein
the piezoelectric film is a PZT film comprising PZT, and
two diffraction peaks respectively representing PZT ( 213 ) planes of the PZT film are observed in an in-plane X-ray diffraction pattern of the film structure.
7 . The film structure according to claim 6 , wherein, in an X-ray reciprocal lattice space mapping of the film structure, three reciprocal lattice points respectively representing a PZT ( 110 ) plane of the PZT film, a Si ( 220 ) plane of the substrate, and a PZT ( 112 ) plane of the PZT film are aligned in a Qz direction.
8 . The film structure according to claim 4 , wherein two diffraction peaks respectively representing SRO ( 110 ) planes of the SRO film are observed in an in-plane X-ray diffraction pattern of the film structure.
9 . The film structure according to claim 2 , further comprising a piezoelectric film epitaxially grown on the metal film.
10 . The film structure according to claim 9 , wherein the piezoelectric film comprises PZT, AlN, LiTaO 3 , or LiNbO 3 .
11 . The film structure according to claim 1 , further comprising a piezoelectric film epitaxially grown on the buffer film.
12 . A method for producing a film structure comprising:
(a) a step for preparing a substrate; and
(b) a step for forming a buffer film on the substrate; wherein
the step (a) comprises preparing (1) a 36° to 48° rotated Y-cut substrate is prepared, or (2) a SOI substrate comprising a base substance made of a 36° to 48° rotated Y-cut Si substrate, an insulating layer on the base substance, and a SOI layer made of a Si film on the insulating layer,
a Miller index of a crystal plane of an upper surface of the SOI layer is equal to the Miller index of a crystal plane of an upper surface of the base substance, and
the step (b) comprises forming the buffer film comprising ZrO 2 epitaxially grown on the substrate.
13 . The method for producing the film structure according to claim 12 , wherein the method further comprises:
(c) a step for forming a metal film epitaxially grown on the buffer film,
wherein the metal film comprises Pt.
14 . The method for producing the film structure according to claim 13 , wherein the method further comprises:
(d) a step for forming a SRO film epitaxially grown on the metal film,
wherein two diffraction peaks respectively representing SRO ( 110 ) planes of the SRO film are observed in an in-plane X-ray diffraction pattern of the film structure.
15 . The method for producing the film structure according to claim 13 , wherein the method further comprises;
(e) a step for forming a piezoelectric film epitaxially grown on the metal film,
wherein the piezoelectric film comprises PZT, AlN, LiTaO 3 , or LiNbO 3 .