TWI755444B - Membrane structure and method for producing the same - Google Patents

Abstract

An object of the present invention is to provide a film structure having a conductive film formed on a silicon substrate and a piezoelectric film formed on the conductive film, and a film structure capable of increasing the piezoelectric constant of the piezoelectric film. The method for producing a film structure, which is the solution of the present invention, is characterized by the step (b) of forming a film containing zirconium on a substrate (11) serving as a silicon substrate, and, after the step (b), forming a film containing zirconium on the substrate (11). (c) step of forming an epitaxially grown zirconia-containing alignment film (12b) on ). In addition, the method for producing the film structure includes the step (d) of forming an epitaxially grown platinum-containing conductive film (13) on the alignment film (12b), and forming epitaxial growth on the conductive film (13). (e) step of growing piezoelectric film (15).

Description

Membrane structure and method for producing the same

[0001] The present invention relates to a membrane structure and a method for producing the same.

As a film structure having a substrate, a conductive film formed on the substrate, and a piezoelectric film formed on the conductive film, there are known a conductive film including a substrate, a platinum-containing film formed on the substrate, and A film structure of a piezoelectric film containing lead zirconate titanate (PZT), that is, Pb(Zr _1-x Ti _x )O ₃ (0<x<1) formed on a conductive film. Piezoelectric elements are formed by processing such film structures. As the substrate having this film structure, a silicon substrate can be used. In Japanese Patent Laid-Open No. 2015-154015 (Patent Document 1), it is disclosed that in a ferroelectric ceramic, a ZrO ₂ film having a (200) orientation is formed on the ZrO ₂ film, and a (200) Aligned platinum film and piezoelectric film technology formed on platinum film. [Prior Art Document] [Patent Document] [0004] [Patent Document 1] Japanese Patent Laid-Open No. 2015-154015

[Problems to be Solved by the Invention] [0005] When a zirconium oxide (ZrO ₂ ) film is directly formed on a silicon substrate, the crystallinity of the formed ZrO ₂ film is lowered, and the ZrO ₂ film cannot be grown well by epitaxial growth. occasion. In such a case, the conductive film cannot be epitaxially grown well on the ZrO ₂ film, and the piezoelectric film cannot be well epitaxially grown on the conductive film. When the piezoelectric film containing lead titanate zirconate is applied with an electric field along a direction parallel to the polarizing direction, or a direction having a certain angle with the polarizing direction, for example, the piezoelectric constant is large. Therefore, when the piezoelectric film is not epitaxially grown well, since the polarization directions of the entire piezoelectric film are not uniform, the piezoelectric constant of the piezoelectric film cannot be increased, and the characteristics of the piezoelectric element are degraded. The present invention is an invention accomplished in order to solve the above-mentioned problems in the past, and an object of the present invention is to provide a film structure having a conductive film formed on a silicon substrate and a piezoelectric film formed on the conductive film It is a film structure that can increase the piezoelectric constant of the piezoelectric film. [Means for Solving the Problems] [0007] Among the creations disclosed in this specification, the outlines of representative ones are briefly described below. [0008] A method for producing a film structure according to an aspect of the present invention is characterized by comprising the step (a) of preparing a silicon substrate, the step (b) of forming a first film containing zirconium on the silicon substrate, and the step (b) of forming a first film containing zirconium on the silicon substrate. After step b), step (c) of forming a second film containing zirconium oxide epitaxially grown on the silicon substrate. In addition, a method for producing a film structure includes the step (d) of forming an epitaxially grown platinum-containing first conductive film on the second film, and forming an epitaxially grown piezoelectric film on the first conductive film (e) step. [0009] In addition, as another aspect, the silicon substrate may have a main surface composed of a (100) plane. In the step (c), a second film that is epitaxially grown on the main surface, has a cubic crystal structure, and contains (100) oriented zirconia can also be formed; in the step (d), a crystal with a cubic crystal is formed. The structure includes a (100) oriented platinum-containing first conductive film. [0010] In addition, as another aspect, in the step (b), the first film may be formed by the vapor deposition method, and in the step (c), the second film may be formed by the vapor deposition method. [0011] In addition, as another aspect, in the step (b), the first film having a thickness of 5 to 10 nm may be formed at a temperature of 650 to 700°C. [0012] In addition, as another aspect, in the step (c), the second film may be formed at a temperature of 500 to 600°C. [0013] In addition, as another aspect, in the step (c), a second film having a thickness of 8 to 12 nm may be formed. [0014] In addition, as another aspect, in the step (e), a piezoelectric film having a tetragonal crystal structure and including (001)-aligned lead zirconate titanate may be formed. [0015] In addition, as another aspect, in the step (e), a piezoelectric film having a rhombohedral crystal structure and including (100) oriented lead zirconate titanate may be formed. [0016] In addition, as another aspect, the method for producing the film structure may include the step (f) of forming the second conductive film on the piezoelectric film. [0017] A film structure as an aspect of the present invention is characterized by comprising a silicon substrate, a first film containing zirconium formed on the silicon substrate, and a first film containing zirconium oxide epitaxially grown on the first film. 2 films, a first conductive film containing platinum epitaxially grown on the second film, and a piezoelectric film epitaxially grown on the first conductive film. In addition, as another aspect, the silicon substrate may have a main surface composed of a (100) plane, the second film may have a cubic crystal structure and include (100) oriented zirconia, and the first The conductive film system has a cubic crystal structure and contains (100) oriented platinum. [0019] In addition, as another aspect, it is preferable that the first film has a thickness of 5 to 10 nm, and the second film has a thickness of 8 to 12 nm. [0020] In addition, as another aspect, it is preferable that the piezoelectric film has a tetragonal crystal structure and contains lead zirconate titanate of (001) orientation. [0021] In addition, as another aspect, it is preferable that the piezoelectric film has a crystal structure of a rhombohedral crystal and contains lead zirconate titanate of (100) orientation. [0022] In addition, as another aspect, the film structure may have a second conductive film formed on the piezoelectric film. [Effects of the Invention] [0023] By applying one aspect of the present invention, in a film structure having a conductive film formed on a silicon substrate and a piezoelectric film formed on the conductive film, piezoelectric The piezoelectric constant of the film increases.

[0052] 如表1所示，矽的晶格常數係0.543nm，ZrO₂ 的晶格常數係0.514nm，ZrO₂ 的晶格常數對矽的晶格常數之不整合小、為5.3%，故而ZrO₂ 的晶格常數對矽的晶格常數之整合性佳。因此，如圖3所示，可以使含ZrO₂ 的配向膜12、在含矽單晶的基板11之(100)面構成的主面上磊晶成長。從而，可以使含ZrO₂ 的配向膜12，在含矽單晶的基板11之(100)面上，以立方晶的結晶構造成(100)配向，可以提高配向膜12的結晶性。 　　[0053] 此外，如表1所示，ZrO₂ 的晶格常數係0.514nm，鉑的晶格常數係0.392nm，但鉑於平面內45°旋轉時，對角線的長度係0.554nm，該對角線的長度對ZrO₂ 的晶格常數之不整合小到7.8%，故而鉑的晶格常數對ZrO₂ 的晶格常數之整合性佳。因此，如圖3所示，可以使含鉑的導電膜13，在含ZrO₂ 的配向膜12之(100)面上，以立方晶的結晶構造成(100)配向，可以提高導電膜13的結晶性。 　　[0054] 此外，如表1所示，鉑的晶格常數係0.392 nm，SRO的晶格常數係0.390～0.393nm，SRO的晶格常數對鉑的晶格常數之不整合小到0.51%以下，故而SRO的晶格常數對鉑的晶格常數之整合性佳。因此，可以使含SRO的導電膜14，在含鉑的導電膜13之(100)面上，以立方晶的結晶構造成(100)配向，可以提高導電膜14的結晶性。 　　[0055] 此外，如表1所示，SRO的晶格常數係0.390～0.393nm，PZT的晶格常數係0.401nm，PZT的晶格常數對SRO的晶格常數之不整合小到2.0～2.8%，故而PZT的晶格常數對SRO的晶格常數之整合性佳。因此，可以使含PZT的壓電膜15，在含SRO的導電膜14之(100)面上、以正方晶的結晶構造成(001)配向，或者，以菱面體晶的結晶構造成(100)配向，可以提高壓電膜15的結晶性。 　　[0056] 另一方面，如圖4所示，於含ZrO₂ 的配向膜12、在含矽單晶的基板11之(100)面構成的主面上並未磊晶成長之狀態下，例如含ZrO₂ 的配向膜12，係在含矽單晶的基板11之(100)面上、以例如立方晶的結晶構造成(111)配向。因此，無法提高配向膜12的結晶性。 　　[0057] 此外，如圖4所示，於含ZrO₂ 的配向膜12、在含矽單晶的基板11之(100)面構成的主面上並未磊晶成長之狀態下，雖在圖4省略圖示，但含鉑的導電膜13、係例如立方晶的結晶構造且(111)配向。因此，無法提高導電膜13的結晶性。於是，在含鉑的導電膜13為例如立方晶的結晶構造且(111)配向之狀態下，無法使含SRO的導電膜14、立方晶的結晶構造且(100)配向，而無法使含PZT的壓電膜15正方晶的結晶構造且(001)配向、或者菱面體晶的結晶構造且(100)配向。 　　[0058] 最好是配向膜12具有厚度13～22nm。在配向膜12的厚度未滿13nm之場合，由於配向膜12的厚度太薄，而使在基板11上配向膜12容易磊晶成長之效果變小。從而，在配向膜12的厚度未滿13nm之場合，配向膜12的一部分，不是(100)配向、而是(111)配向。 　　[0059] 此外，在配向膜12的厚度超過22nm之場合，由於配向膜12的厚度太厚，也會使在基板11上配向膜12容易磊晶成長之效果變小。從而，在配向膜12的厚度超過22nm之場合，配向膜12的一部分，不是(100)配向、而是(111)配向。 　　[0060] 圖5係實施形態之膜構造體之配向膜具有二層構造的場合之、膜構造體之剖面圖。 　　[0061] 配向膜12，也可以包含膜12a、與配向膜12b。膜12a，包含被形成在基板11上之鋯，但被包含在膜12a之鋯並未被氧化，而是金屬鋯。亦即，膜12a，係含鋯之金屬膜。另一方面，配向膜12b，係包含在膜12a上磊晶成長的氧化鋯。從而，圖1及圖2所示之配向膜12，係相當於圖5所示之配向膜12b。 　　[0062] 配向膜12b介著膜12a而在基板11上被形成之場合，相比於配向膜12b並不介著膜12a而在基板11上被形成之場合，較容易使磊晶成長。因此，可以使含ZrO₂ 的配向膜12b，在含矽單晶的基板11之(100)面構成的作為主面的上面11a上，更安定化並磊晶成長。從而，可以使含ZrO₂ 的配向膜12，在含矽單晶的基板11之(100)面上，更安定化並(100)配向，可以更為提高配向膜12的結晶性。 　　[0063] 但是，在形成含ZrO₂ 的配向膜12b時，會有藉由包含在膜12a的鋯被氧化，致使膜12a消滅而成為配向膜12b之情形。在這樣的場合，如圖1所示，在基板11上直接形成配向膜12b，作成在基板11上形成僅包含被直接形成的配向膜12b之配向膜12。 　　[0064] 最好是，膜12a具有厚度5～10nm。在膜12a的厚度未滿5nm之場合，由於膜12a的厚度太薄，而使在基板11上配向膜12b容易磊晶成長之效果變小。從而，在膜12a的厚度未滿5nm之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0065] 此外，在膜12a的厚度超過10nm之場合，由於膜12a的厚度太厚，也會使在基板11上配向膜12b容易磊晶成長之效果變小。從而，在膜12a的厚度超過10nm之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0066] 最好是，配向膜12b具有厚度8～12nm。在配向膜12b的厚度未滿8nm之場合，由於配向膜12b的厚度太薄，而使在基板11上配向膜12b容易磊晶成長之效果變小。從而，在配向膜12b的厚度未滿8nm之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0067] 此外，在配向膜12b的厚度超過12nm之場合，由於配向膜12b的厚度太厚，也會使在基板11上配向膜12b容易磊晶成長之效果變小。從而，在配向膜12b的厚度超過12nm之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0068] 又，本實施形態之膜構造體10，不具有導電膜14及壓電膜15，而僅具有基板11、配向膜12、與導電膜13亦可。即使在這樣的場合，也可以藉由在膜構造體10上，形成壓電膜15、與作為上部電極的導電膜16，而容易地形成具有利用導電膜13與導電膜16從上下挾著的壓電膜15之壓電元件。 　　[0069] ＜膜構造體之製造方法＞ 　　其次，說明本實施形態之膜構造體之製造方法。圖6～圖11係實施形態之膜構造體的製造步驟中之剖面圖。 　　[0070] 首先，如圖6所示，準備作為矽基板的基板11(步驟S1)。 　　[0071] 最好是，基板11，具有立方晶的結晶構造，且具有由(100)面構成的作為主面之上面11a。此外，在基板11之上面11d上，亦可形成作為自然氧化膜之SiO₂ 膜等氧化膜。 　　[0072] 又，作為基板11，可以使用矽基板以外的各種基板，可以使用例如矽以外之各種半導體單晶所構成的基板等。 　　[0073] 如圖6所示，將矽單晶所構成的基板11之(100)面構成的上面11a內相互正交的2個方向、設為X軸方向及Y軸方向，垂直於上面11a的方向設為Z軸方向。 　　[0074] 其次，如圖7所示，形成膜12a(步驟S2)。於此步驟S2，在基板11上，形成含鋯之膜12a。 　　[0075] 於步驟S2，以採用電子束蒸鍍法形成配向膜12的場合為例示進行說明，但也可以採用例如濺鍍法等各種方法來形成。 　　[0076] 於步驟S2，首先，在將基板11設置在電子束蒸鍍裝置的真空室內，將真空室內的壓力、調整到例如2.1×10^-5 Pa等一定的真空氛圍下之狀態，將基板11加熱到例如600～750℃。 　　[0077] 於步驟S2，其次，藉由使用鋯(Zr)單晶的蒸鍍材料之電子束蒸鍍法使鋯蒸發。此時，蒸發的鋯，成膜成鋯(Zr)膜。於是，在基板11上，形成具有例如厚度20nm以下的含鋯之膜12a。又，包含在膜12a之鋯，並未被氧化，而是金屬鋯。亦即，膜12a，係含鋯之金屬膜。 　　[0078] 最好是，於步驟S2，形成具有厚度5～10nm之膜12a。在膜12a的厚度未滿5nm之場合，膜12a的厚度太薄，會使在基板11上配向膜12b(參照後述之圖8)容易磊晶成長之效果變小。從而，在膜12a的厚度未滿5nm之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0079] 此外，在膜12a的厚度超過10nm之場合，由於膜12a的厚度太厚，也會使在基板11上配向膜12b容易磊晶成長之效果變小。從而，在膜12a的厚度超過10nm之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0080] 最好是，於步驟S2，以溫度650～700℃形成膜12a。在基板11的溫度未滿650℃之場合，基板11的溫度太低，會使在基板11上配向膜12b容易磊晶成長之效果變小。從而，在基板11的溫度未滿650℃之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0081] 此外，在基板11的溫度超過700℃之場合，基板11的溫度過高，會使在基板11上配向膜12b容易磊晶成長之效果變小。從而，在基板11的溫度超過700℃之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0082] 其次，如圖8所示，形成配向膜12b(步驟S3)。於此步驟S3，係形成在膜12a上磊晶成長的含氧化鋯之配向膜12b。 　　[0083] 於步驟S3，與步驟S2同樣地，以採用電子束蒸鍍法形成配向膜12之場合為例示進行說明，但也可以採用例如濺鍍法等各種方法來形成。 　　[0084] 於步驟S3，首先，在將基板11設置在電子束蒸鍍裝置的真空室內，以例如10sccm的流量將氧氣(O₂ )流到真空室內，將真空室內的壓力調整到例如7.0×10^-3 Pa之狀態，將基板11加熱到例如500～600℃。 　　[0085] 於步驟S3，其次，藉由使用鋯(Zr)單晶的蒸鍍材料之電子束蒸鍍法使鋯蒸發。此時，藉由蒸發的鋯在膜12a上與氧反應，成膜成氧化鋯(ZrO₂ )膜。接著，形成作為單層膜之由ZrO₂ 膜所構成之配向膜12b。接著，形成在含鋯的膜12a上磊晶成長之、含氧化鋯之配向膜12b。 　　[0086] 配向膜12b，在由矽單晶構成的基板11之(100)面構成的作為主面之上面11a上，藉著膜12a，進行磊晶成長。配向膜12，具有立方晶之結晶構造，且包含(100)配向之氧化鋯(ZrO₂ )。亦即，在由矽單晶所構成的基板11的(100)面構成的上面11a上，介著膜12a，形成(100)配向的含氧化鋯(ZrO₂ )的配向膜12。 　　[0087] 如使用前述之圖6所說明的，將由矽單晶所構成的基板11之(100)面構成的上面11a內相互正交的2個方向、設為X軸方向及Y軸方向，將垂直於上面11a的方向設為Z軸方向。此時，某個膜進行磊晶成長，是指該膜在X軸方向、Y軸方向及Z軸方向之任一方向均進行配向。 　　[0088] 最好是，於步驟S3，形成具有厚度8～12nm之配向膜12b。在配向膜12b的厚度未滿8nm之場合，由於配向膜12b的厚度太薄，而使在基板11上配向膜12b容易磊晶成長之效果變小。從而，在配向膜12b的厚度未滿8nm之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0089] 此外，在配向膜12b的厚度超過12nm之場合，由於配向膜12b的厚度太厚，也會使在基板11上配向膜12b容易磊晶成長之效果變小。從而，在配向膜12b的厚度超過12nm之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0090] 如前述，最好是，於步驟S3，以溫度500～600℃形成配向膜12b。在基板11的溫度未滿500℃之場合，因基板11的溫度太低，例如在膜12a上鋯原子及氧原子變得不易被再配置等，致使在基板11上配向膜12b容易磊晶成長之效果變小。從而，在基板11的溫度未滿500℃之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0091] 此外，在基板11的溫度超過600℃之場合，基板11的溫度過高，會使在基板11上配向膜12b容易磊晶成長之效果變小。從而，在基板11的溫度超過600℃之場合，配向膜12b的一部分，不是(100)配向、而是(111)配向。 　　[0092] 在形成含ZrO₂ 的配向膜12b時，會有藉由包含在膜12a的鋯被氧化，致使膜12a消滅而成為配向膜12b之情形。在這樣的場合，如圖9所示，在基板11上直接形成配向膜12b，作成在基板11上形成僅包含被直接形成的配向膜12b之配向膜12。於是，最好是，利用具有厚度5～10 nm之膜12a、與具有厚度8～12nm之本來的配向膜12b，形成包含具有合計厚度13～22nm的新的配向膜12b之配向膜12。於以下的說明，如圖9所示，在步驟S3，以在基板11上直接形成配向膜12b之場合為例示加以說明。 　　[0093] 其次，如圖10所示，形成導電膜13(步驟S4)。於此步驟S4，形成在配向膜12b上磊晶成長之、作為下部電極的一部分之導電膜13。導電膜13係由金屬所構成。作為由金屬所構成的導電膜13，可以使用例如含鉑(Pt)的導電膜。 　　[0094] 作為導電膜13，形成含鉑的導電膜之場合，在配向膜12上，以550℃以下之溫度、最好是溫度400℃，利用濺鍍法，將磊晶成長之導電膜13、形成作為下部電極的一部分。含鉑的導電膜13，係在配向膜12b上磊晶成長。此外，包含於導電膜13的鉑，係具有立方晶之結晶構造，且(100)配向。 　　[0095] 又，作為由金屬所構成的導電膜13，也可以取代含鉑(Pt)的導電膜，而改用例如含銥(Ir)的導電膜。 　　[0096] 其次，如圖11所示，形成導電膜14(步驟S5)。於此步驟S5，形成在導電膜13上磊晶成長之、作為下部電極的一部分之導電膜14。導電膜14係由金屬氧化物所構成。作為由金屬氧化物所構成的導電膜14，可以使用例如含釕酸鍶(SrRuO₃ :SRO)的導電膜。 　　[0097] 作為導電膜14，形成含SRO的導電膜之場合，於導電膜13上，以600℃程度之溫度，利用濺鍍法，將磊晶成長之導電膜14，形成作為下部電極的一部分。含SRO的導電膜14，係在導電膜13上磊晶成長。此外，包含於導電膜14的SRO，係具有立方晶之結晶構造，且(100)配向。 　　[0098] 又，作為由金屬氧化物所構成的導電膜14，也可以取代含SRO的導電膜，而改用例如含鈦酸釕酸鍶(Sr(Ti_y Ru_1-y )O₃ (0≦y≦0.4))之導電膜。 　　[0099] 其次，如圖1所示，形成壓電膜15(步驟S6)。於此步驟S6，利用例如溶膠-凝膠(Sol-Gel)法等塗佈法或濺鍍法，在導電膜14上，形成磊晶成長之含鋯鈦酸鉛(Pb(Zr_1-x Ti_x )O₃ (0＜x＜1):PZT)之壓電膜15。 　　[0100] 此外，利用溶膠-凝膠法形成壓電膜15之場合，於步驟S6，首先，複數回反覆進行在導電膜14上，藉由塗佈含有鉛、鋯及鈦的溶液，形成含PZT的前驅體的膜之步驟。藉此，形成包含相互層積的複數膜之膜。 　　[0101] 接著，利用溶膠-凝膠法形成壓電膜15之場合，於步驟S6，其次，藉由將膜熱處理使前驅體氧化並結晶化，而形成含PZT之壓電膜15。 　　[0102] 最好是，壓電膜15具有正方晶之結晶構造，且(001)配向。藉由滿足在Pb(Zr_1-x Ti_x )O₃ (0＜x＜1)之x為0.48＜x＜1，包含在壓電膜15的PZT具有正方晶的結晶構造，容易使磊晶成長、容易(001)配向。於是，具有正方晶的結晶構造之PZT為(001)配向的場合，平行於[001]方向的分極方向、與平行於壓電膜15的厚度方向的電場方向成為相互平行，因而使壓電特性提升。亦即，在具有正方晶的結晶構造的PZT，被施加沿著[001]方向的電場之場合，可得到大的壓電常數d33及d31。因此，可以使壓電膜15的壓電常數更為增大。 　　[0103] 或者，最好是，壓電膜15具有菱面體晶之結晶構造，且(100)配向。藉由滿足在Pb(Zr_1-x Ti_x )O₃ (0＜x＜1)之x為0.20＜x≦0.48，包含在壓電膜15的PZT具有菱面體晶的結晶構造，容易使磊晶成長、容易(100)配向。於是，具有菱面體晶的結晶構造之PZT為(100)配向的場合，該PZT，具有所謂的Engineered Domain Configuration，平行於與[111]方向等價的各方向的分極方向、與平行於壓電膜15的厚度方向的電場方向之角度，因任一分極域(domain)均相互相等而使壓電特性提升。亦即，在具有菱面體晶的結晶構造的PZT，被施加沿著[100]方向的電場之場合，可得到大的壓電常數d33及d31。因此，可以使壓電膜15的壓電特性更為增大。 　　[0104] 如此作法，形成圖1所示的膜構造體10。又，在形成配向膜12b時，膜12a不消滅而殘留之場合，形成圖5所示之膜構造體10。 　　[0105] 在作為矽基板的基板11上直接形成含氧化鋯(ZrO₂ )的配向膜12b之場合，有被形成的ZrO₂ 膜的結晶性降低，無法使配向膜12b良好地磊晶成長之場合。這樣的場合，無法在配向膜12b上使導電膜13良好地磊晶成長、無法在導電膜13上使壓電膜15良好地磊晶成長。在壓電膜15，在施加例如沿著平行於分極方向的方向，或者與分極方向具有一定角度的方向的電場的場合，壓電常數d33及d31很大。因此，在壓電膜15並未良好地磊晶成長之場合，由於壓電膜15全體其分極方向沒有統一，而無法使壓電膜15的壓電常數d33及d31增加，使壓電元件的特性降低。 　　[0106] 另一方面，於本實施形態，在基板11上形成含鋯(Zr)的膜12a之後，在基板11上使含ZrO₂ 的配向膜12b磊晶成長。被包含在膜12a的鋯，未被氧化，是金屬鋯。在這樣的場合，相較於在基板11上直接形成含ZrO₂ 的配向膜12b之場合，前者可以使配向膜12良好地磊晶成長。因此，可以在配向膜12b上使導電膜13良好地磊晶成長、在導電膜13上使壓電膜15良好地磊晶成長。從而，壓電膜15全體其分極方向可以統一，可以使壓電膜15的壓電常數d33及d31增加，能提升壓電元件的特性。 　　[0107] 又，形成壓電膜15之後，作為步驟S7，亦可在壓電膜15上，形成作為上部電極之導電膜16(參照圖2)。藉此，可以在壓電膜15上對厚度方向施加電場。 　　[0108] ＜實施形態之變形例＞ 　　在實施形態，如圖1所示，在導電膜13上介著導電膜14形成壓電膜15。但是，亦可在導電膜13上，不介著導電膜14而直接形成壓電膜15。將這樣的例，作為實施形態之變形例來說明。 　　[0109] 圖12係實施形態的變形例之膜構造體之剖面圖。 　　[0110] 如圖12所示，本變形例之膜構造體10，係具有基板11、配向膜12、導電膜13、與壓電膜15。配向膜12，被形成於基板11上。導電膜13，被形成於配向膜12上。壓電膜15，被形成於導電膜13上。 　　[0111] 亦即，本變形例之膜構造體10，除了在導電膜13上、不介著導電膜14(參照圖1)而直接形成壓電膜15這一點之外，與實施形態的膜構造體10是相同的。 　　[0112] 在含鉑的導電膜13上，不介著含SRO的導電膜14(參照圖1)而形成含PZT的壓電膜15之場合，相較於在含鉑的導電膜13上、介著含SRO的導電膜14(參照圖1)而形成含PZT的壓電膜15之場合，壓電膜15的結晶性較為降低。但是，在含鉑的導電膜13上，不介著含SRO的導電膜14(參照圖1)而形成含PZT的壓電膜15之場合，在配向膜12上導電膜13也容易配向或磊晶成長。因此，在導電膜13上被形成的壓電膜15也有某種程度容易配向或磊晶成長，可以某種程度提升壓電膜15的結晶性。 　　[0113] 又，本變形例的膜構造體10，與實施形態的膜構造體10同樣地，也可以具有導電膜16(參照圖2)。 [實施例] 　　[0114] 以下，根據實施例更詳細說明本實施形態。又，本發明並不受到以下的實施例的限定。 　　[0115] (實施例1~60) 　　在以下，將在實施形態用圖1說明的膜構造體10，形成為實施例1～60之膜構造體。此外，實施例1～60的膜構造體，是分別變更膜12a(參照圖7)的厚度、形成膜12a時的基板溫度、及形成配向膜12b(參照圖8)時的基板溫度而形成的膜構造體。 　　[0116] 首先，如圖6所示，作為基板11，具有由(100)面構成的作為主面之上面11a，準備由6吋矽基板構成的晶圓。 　　[0117] 其次，如圖7所示，在基板11上，作為膜12a，而利用電子束蒸鍍法形成鋯(Zr)膜。將此時的條件顯示於以下。 　　裝置：電子束蒸鍍裝置 　　壓力：2.10×10^-5 Pa 　　蒸鍍源：Zr 　　加速電壓／放射電流：7.5kV/1.50mA 　　厚度：20nm以下 　　成膜速度：0.005nm/s 　　氧流量：0sccm 　　基板溫度：600～750℃ 　　[0118] 其次，如圖8所示，作為配向膜12，利用電子束蒸鍍法、形成氧化鋯(ZrO₂ )膜。將此時的條件顯示於以下。 　　裝置：電子束蒸鍍裝置 　　壓力：7.00×10^-3 Pa 　　蒸鍍源：Zr+O₂ 加速電壓／放射電流：7.5kV/1.80mA 　　厚度：10nm 　　成膜速度：0.005nm/s 　　氧流量：10sccm 　　基板溫度：500～600℃ 　　[0119] 於此，將實施例1～60之各實施例之鋯膜的厚度、形成鋯膜時的基板溫度、及形成ZrO₂ 膜時的基板溫度，顯示在表2~表4。表2所示之實施例1～20，係形成ZrO₂ 膜時的基板溫度為500℃之場合。表3所示之實施例21～40，係形成ZrO₂ 膜時的基板溫度為550℃之場合。接著，表4所示之實施例41～60，係形成ZrO₂ 膜時的基板溫度為600℃之場合。又，如前述，實施例1～60之各實施例之ZrO₂ 膜的厚度係10nm。此外，於表2~表4，利用單圈與雙圈、顯示ZrO₂ 膜的結晶性之評價結果。雙圈之場合，顯示其結晶性比單圈之場合還高。 　　[0120]

[0121]

[0122]

[0123] 針對實施例1～60，測定被形成到ZrO₂ 膜為止的膜構造體根據X光繞射(X-ray Diffraction:XRD)法之θ-2θ頻譜。圖13及圖14，係顯示被形成到ZrO₂ 膜為止的膜構造體根據XRD法之θ-2θ頻譜之例之圖。圖13及圖14之各個圖的橫軸係顯示角度2θ，圖13及圖14之各個圖的縱軸係顯示X線的強度。 　　[0124] 又，圖13係例示鋯膜的厚度為7nm、形成鋯膜時的基板溫度為700℃、形成ZrO₂ 膜時的基板溫度為550℃之場合。此外，圖14係例示鋯膜的厚度為7nm、形成鋯膜時的基板溫度為750℃、形成ZrO₂ 膜時的基板溫度為550℃之場合。此外，在圖13及圖14，T-ZrO₂ 係意指正方晶的ZrO₂ ，M-ZrO₂ 係意指單斜晶的ZrO₂ 。又，如前述，設定正方晶的ZrO₂ 被包含在立方晶的ZrO₂ 。 　　[0125] 於圖13所示之例，在θ-2θ頻譜，觀察到相當於具有正方晶的結晶構造的ZrO₂ 的(200)的峰值。因此可知，配向膜12b，具有正方晶的結晶構造，且包含(100)配向之ZrO₂ 。 　　[0126] 此外，於圖13所示之例，在θ-2θ頻譜，未觀察到相當於具有正方晶的結晶構造的ZrO₂ 的(200)之峰值以外的峰值。因此可知，配向膜12b，具有正方晶的結晶構造，且於(100)面以外的面配向之ZrO₂ ，或者具有單斜晶的結晶構造的ZrO₂ 、至少並未含有檢出界限以上的含有比。 　　[0127] 另一方面，於圖14所示之例，也在θ-2θ頻譜，觀察到相當於具有正方晶的結晶構造的ZrO₂ 的(200)的峰值。因此可知，配向膜12b，具有正方晶的結晶構造，且包含(100)配向之ZrO₂ 。 　　[0128] 但是，於圖14所示之例，在θ-2θ頻譜，作為相當於具有正方晶的結晶構造的ZrO₂ 的(200)之峰值以外的峰值，觀察到相當於具有正方晶的結晶構造之ZrO₂ 的(111)之峰值、及相當於具有單斜晶的結晶構造之ZrO₂ 的(111)之峰值。因此可知，配向膜12b，若比起具有正方晶的結晶構造、且(100)配向的ZrO₂ ，雖含有比是較少，但某種程度包含具有正方晶的結晶構造、且(111)配向的ZrO₂ ，及具有單斜晶的結晶構造、且(111)配向的ZrO₂ 。 　　[0129] 如前述，實施例1～60的膜構造體，係分別變更鋯膜的厚度、形成鋯膜時的基板溫度、及形成ZrO₂ 膜時的基板溫度而形成的膜構造體。針對這樣的實施例1～60的膜構造體將在測定的θ-2θ頻譜觀察到之峰值、依鋯膜的厚度、形成鋯膜時的基板溫度、及形成ZrO₂ 膜時的基板溫度加以分類並整理。圖15~圖17，係顯示將於實施例1～60的θ-2θ頻譜觀察到之峰值、依鋯膜的厚度、及形成鋯膜時的基板溫度加以分類並整理之表。圖15~圖17，分別顯示形成ZrO₂ 膜時的基板溫度、為500℃、550℃及600℃任一之場合。此外，圖15~圖17各圖的各列，係對應於相互不同的Zr膜的厚度；圖15~圖17各圖的各行，係對應於形成相互不同的Zr膜時的基板溫度。 　　[0130] 首先，如圖15所示，在形成ZrO₂ 膜時的基板溫度為500℃之場合下，鋯膜的厚度為20nm以下、且形成鋯膜時的基板溫度為600～750℃之場合，觀察到(100)配向的ZrO₂ 的峰值(在圖15記載為ZrO₂ (200))。另一方面，在圖15省略圖示，但在形成ZrO₂ 膜時的基板溫度為500℃之場合下，鋯膜的厚度為超過20nm之場合、形成鋯膜時的基板溫度為未滿600℃之場合、或形成鋯膜時的基板溫度為超過750℃之場合，並未觀察到(100)配向的ZrO₂ 的峰值。 　　[0131] 此外，如圖16所示，在形成ZrO₂ 膜時的基板溫度為550℃之場合下，鋯膜的厚度為20nm以下、且形成鋯膜時的基板溫度為600～750℃之場合，觀察到(100)配向的ZrO₂ 的峰值(在圖16記載為ZrO₂ (200))。另一方面，在圖16省略圖示，但在形成ZrO₂ 膜時的基板溫度為550℃之場合下，鋯膜的厚度為超過20nm之場合、形成鋯膜時的基板溫度為未滿600℃之場合、或形成鋯膜時的基板溫度為超過750℃之場合，並未觀察到(100)配向的ZrO₂ 的峰值。 　　[0132] 此外，如圖17所示，在形成ZrO₂ 膜時的基板溫度為600℃之場合下，鋯膜的厚度為20nm以下、且形成鋯膜時的基板溫度為600～750℃之場合，觀察到(100)配向的ZrO₂ 的峰值(在圖17記載為ZrO₂ (200))。另一方面，在圖17省略圖示，但在形成ZrO₂ 膜時的基板溫度為600℃之場合下，鋯膜的厚度為超過20nm之場合、形成鋯膜時的基板溫度為未滿600℃之場合、或形成鋯膜時的基板溫度為超過750℃之場合，並未觀察到(100)配向的ZrO₂ 的峰值。 　　[0133] 此外，於圖15～圖17省略圖示，但作為圖15～圖17所示的實施例1~60以外之實施例，其他條件設定完全相同，形成具有厚度5nm或20nm的ZrO₂ 膜之場合，也得到與形成具有厚度10nm的ZrO₂ 膜之場合完全同樣的結果。 　　[0134] 由以上的結果可知，至少在以溫度600～750℃形成具有厚度20nm以下的、含鋯的膜12a，且以溫度500～600℃形成具有厚度5～20nm的含氧化鋯的配向膜12b之場合，觀察到(100)配向的ZrO₂ 峰值。此類之場合，配向膜12b，具有正方晶之結晶構造，且包含更多(100)配向之氧化鋯。 　　[0135] 此外，如在圖15附上影線所示，在形成ZrO₂ 膜時的基板溫度為500℃之場合下，鋯膜的厚度為5～10nm、且形成鋯膜時的基板溫度為650～700℃之場合，並未觀察到(100)配向的ZrO₂ 的峰值以外的峰值。另一方面，在形成ZrO₂ 膜時的基板溫度為500℃之場合下，鋯膜的厚度為未滿5nm之場合、鋯膜的厚度為超過10nm之場合、形成鋯膜時的基板溫度為未滿650℃之場合、或形成鋯膜時的基板溫度為超過700℃之場合，觀察到ZrO₂ (100)以外的峰值。觀察到的峰值，係例如(111)配向的ZrO₂ 的峰值(在圖15記載為ZrO₂ (111))、(111)配向的Zr₃ O的峰值(在圖15記載為Zr₃ O(111))、(101)配向的Zr₃ O的峰值(在圖15記載為Zr₃ O(101))。 　　[0136] 又，針對形成ZrO₂ 膜時的基板溫度為500℃之場合之上述結果，在表2的「ZrO₂ 膜的結晶性」欄位，顯示如以下。亦即，鋯膜的厚度為5～10nm、且形成鋯膜時的基板溫度為650～700℃之場合(實施例7～9、12～14)，結晶性的評價結果是以比單圈更優良的雙圈表示。另一方面，這以外的場合(實施例1～6、10、11、15～20)，結晶性的評價結果是以單圈表示。 　　[0137] 此外，如在圖16附上影線所示，在形成ZrO₂ 膜時的基板溫度為550℃之場合，鋯膜的厚度為5～10 nm、且形成鋯膜時的基板溫度為650～700℃之場合，並未觀察到(100)配向的ZrO₂ 的峰值以外的峰值。另一方面，在形成ZrO₂ 膜時的基板溫度為550℃之場合下，鋯膜的厚度為未滿5nm之場合、鋯膜的厚度為超過10nm之場合、形成鋯膜時的基板溫度為未滿650℃之場合、或形成鋯膜時的基板溫度為超過700℃之場合，觀察到ZrO₂ (100)以外的峰值。觀察到的峰值，係例如(111)配向的ZrO₂ 的峰值(在圖16記載為ZrO₂ (111))、(111)配向的Zr₃ O的峰值(在圖16記載為Zr₃ O(111))、(101)配向的Zr₃ O的峰值(在圖16記載為Zr₃ O(101))。 　　[0138] 又，針對形成ZrO₂ 膜時的基板溫度為550℃之場合之上述結果，在表3的「ZrO₂ 膜的結晶性」欄位，顯示如以下。亦即，鋯膜的厚度為5～10nm、且形成鋯膜時的基板溫度為650～700℃之場合(實施例27～29、32～34)，結晶性的評價結果是以比單圈更優良的雙圈表示。另一方面，這以外的場合(實施例21～26、30、31、35～40)，結晶性的評價結果是以單圈表示。 　　[0139] 此外，如在圖17附上影線所示，在形成ZrO₂ 膜時的基板溫度為600℃之場合，鋯膜的厚度為5～10 nm、且形成鋯膜時的基板溫度為650～700℃之場合，並未觀察到(100)配向的ZrO₂ 的峰值以外的峰值。另一方面，在形成ZrO₂ 膜時的基板溫度為600℃之場合下，鋯膜的厚度為未滿5nm之場合、鋯膜的厚度為超過10nm之場合、形成鋯膜時的基板溫度為未滿650℃之場合、或形成鋯膜時的基板溫度為超過700℃之場合，觀察到ZrO₂ (100)以外的峰值。觀察到的峰值，係例如(111)配向的ZrO₂ 的峰值(在圖17記載為ZrO₂ (111))、(111)配向的Zr₃ O的峰值(在圖17記載為Zr₃ O(111))、(101)配向的Zr₃ O的峰值(在圖17記載為Zr₃ O(101))。 　　[0140] 又，針對形成ZrO₂ 膜時的基板溫度為600℃之場合之上述結果，在表4的「ZrO₂ 膜的結晶性」欄位，顯示如以下。亦即，鋯膜的厚度為5～10nm、且形成鋯膜時的基板溫度為650～700℃之場合(實施例47～49、52～54)，結晶性的評價結果是以比單圈更優良的雙圈表示。另一方面，這以外的場合(實施例41～46、50、51、55～60)，結晶性的評價結果是以單圈表示。 　　[0141] 又，在圖15~圖17，被記載為「ZrO₂ (200)弱」之峰值強度係意味未滿5.0×10³ cps，未滿這以外的被記載為「ZrO₂ (200)」之峰值強度的1/2。 　　[0142] 此外，於圖15～圖17省略圖示，但作為實施例1~60以外之實施例，形成具有厚度8nm或12nm的ZrO₂ 膜之場合，也得到與形成具有厚度10nm的ZrO₂ 膜之場合完全同樣的結果。 　　[0143] 由以上的結果可知，最好是以溫度650～700℃形成具有厚度5～10nm的、含鋯的膜12a，且以溫度500～600℃形成具有厚度8～12nm的含氧化鋯的配向膜12b。此類的條件之場合，配向膜12b，可以具有正方晶之結晶構造，且包含更多(100)配向之氧化鋯。 　　[0144] 鋯(Zr)，比矽(Si)還容易氧化、容易離子化。因此，藉由以溫度650～700℃形成具有厚度5～10nm的、含鋯的膜12a，且以溫度500～600℃形成具有厚度8～12nm的含氧化鋯的配向膜12b，能將在矽基板即基板11的上面11a存在的自然氧化膜(SiO₂ )更完全地去除。因此，可以使含氧化鋯(Zr)的配向膜12b，在基板11的上面11a上直接磊晶成長。 　　[0145] 又，於實施例1～60，在形成含ZrO₂ 的配向膜12b時，由於包含在膜12a的鋯被氧化，致使膜12a消滅而成為配向膜12b。因此，在基板11上直接形成配向膜12b，在基板11上形成僅包含被直接形成的配向膜12b之配向膜12。 　　[0146] 其次，如圖10所示，於配向膜12上，作為導電膜13，利用濺鍍法形成了鉑(Pt)膜。將此時的條件顯示如下。 　　裝置：DC濺鍍裝置 　　壓力：3.20×10^-2 Pa 　　蒸鍍源：Pt 　　電力：100W 　　厚度：100nm 　　成膜速度：0.14nm/s 　　Ar流量：16sccm 　　基板溫度：400℃ 　　[0147] 在ZrO₂ 膜的θ-2θ頻譜，在ZrO₂ (200)的峰值以外，觀察到ZrO₂ (111)、Zr₃ O(111)及Zr₃ O(101)的峰值之場合，在鉑膜的θ-2θ頻譜，在鉑(200)的峰值以外，觀察到鉑(111)的峰值。另一方面，在ZrO₂ 膜的θ-2θ頻譜，在ZrO₂ (200)的峰值以外，未觀察到ZrO₂ (111)、Zr₃ O(111)及Zr₃ O(101)的峰值之場合，在鉑膜的θ-2θ頻譜，在鉑(200)的峰值以外，未觀察到鉑(111)的峰值，可以提升導電膜13的結晶性。 　　[0148] 其次，如圖11所示，於導電膜13上，作為膜14，利用濺鍍法形成SRO膜。將此時的條件顯示如下。 　　裝置：RF磁控管濺鍍裝置 　　功率：300W 　　氣體：Ar 　　壓力：1.8Pa 　　基板溫度：600℃ 　　成膜速度：0.11nm/s 　　厚度：20nm 　　[0149] 針對實施例1～60，測定被形成至SRO膜為止的膜構造體之根據XRD法之θ-2θ頻譜。圖18係顯示被形成至SRO膜為止的膜構造體之根據XRD法之θ-2θ頻譜之例之圖。圖18之圖的橫軸係顯示角度2θ，圖18之圖的縱軸係顯示X線的強度。 　　[0150] 又，圖18係例示鋯膜的厚度為7nm、形成鋯膜時的基板溫度為700℃、形成ZrO₂ 膜時的基板溫度為550℃之場合。 　　[0151] 於圖18所示之例，在θ-2θ頻譜，觀察到相當於具有立方晶的結晶構造的Pt的(200)的峰值。因此可知，導電膜13，具有立方晶的結晶構造，且包含(100)配向的Pt。 　　[0152] 此外，於圖18所示之例，在θ-2θ頻譜，觀察到相當於具有立方晶的結晶構造的SRO的(100)的峰值。因此可知，導電膜13，具有立方晶的結晶構造，且包含(100)配向的SRO。 　　[0153] 其次，如圖1所示，在導電膜14上，作為壓電膜15，利用塗佈法形成層積Pb(Zr_{0 . 52} Ti_{0 . 48} )O₃ 膜(PZT膜)之層積膜。將此時的條件顯示如下。 　　[0154] 使鉛、鋯及鈦之有機金屬化合物以成為Pb:Zr:Ti=100+δ:52:48之組成比的方式混合，對乙醇與2-正丁氧醇之混合溶媒，以使作為Pb(Zr_{0 . 52} Ti_{0 . 48} )O₃ 之濃度成為0.35mol/l的方式調整使溶解之原料溶液。此處的δ，係於之後的熱處理程序補充Pb氧化物揮發之剩餘Pb量，於本實施例為δ=20。接著，於原料溶液，進而溶解20g的重量之K值為27～33的聚咯烷酮。 　　[0155] 其次，藉由把調製的原料溶液之中的3ml的原料溶液、滴下至6吋晶圓構成的基板11上，以3000rpm旋轉10秒鐘，把原料溶液塗佈於基板11上，而形成包含前驅體的膜。接著，藉由在溫度200℃的熱板上，將基板11載置30秒鐘，進而在溫度450℃的熱板上，將基板11載置30秒鐘，而使溶媒蒸發並使膜乾燥。之後，藉由在0.2MPa的氧(O₂ )氛圍中，以600～700℃熱處理60秒鐘將前驅體氧化並使結晶化，形成具有100nm膜厚之壓電膜。藉由反覆進行例如5回從該原料溶液的塗佈至結晶化為止的步驟，形成具有例如500nm膜厚的PZT膜。 　　[0156] 針對實施例1～60，測定被形成至PZT膜為止的膜構造體之根據XRD法之θ-2θ頻譜。圖19係顯示被形成至PZT膜為止的膜構造體之根據XRD法之θ-2θ頻譜之例之圖。圖19之圖的橫軸係顯示角度2θ，圖19之圖的縱軸係顯示X線的強度。 　　[0157] 又，圖19係例示鋯膜的厚度為7nm、形成鋯膜時的基板溫度為700℃、形成ZrO₂ 膜時的基板溫度為550℃之場合。 　　[0158] 此外，於圖19所示之例，在θ-2θ頻譜，觀察到相當於具有正方晶的結晶構造的PZT的(001)及(002)的峰值。因此可知，壓電膜15，具有正方晶的結晶構造，且包含(001)配向的PZT。 　　[0159] 此外，在將PZT膜利用塗佈法形成之場合，作為基板溫度，以比從前廣的溫度範圍之600～700℃形成之場合，可知與圖19所示之例同樣地，壓電膜15具有正方晶的結晶構造、且包含(001)配向的PZT。 　　[0160] 又，有別於實施例1～60，作為壓電膜15，即使取代塗佈法、而利用濺鍍法來形成PZT膜，也可得到完全同樣的結果。作為壓電膜15，將利用濺鍍法形成PZT膜時的條件、顯示於以下。 　　裝置：RF磁控管濺鍍裝置 　　功率：2500W 　　氣體：Ar/O₂ 壓力：0.14Pa 　　基板溫度：425～525℃ 　　成膜速度：0.63nm/s 　　[0161] 在將PZT膜、取代塗佈法而利用濺鍍法形成之場合，作為基板溫度，也以比從前廣的溫度範圍之425～525℃形成之場合，可知與圖19所示之例同樣地，壓電膜15具有正方晶的結晶構造、且包含(001)配向的PZT。 　　[0162] 以上根據其實施形態具體說明由本案發明人所完成的發明，但本發明並不以前述實施形態為限，在不逸脫於其要旨的範圍當然可以進行種種的變更。 　　[0163] 在本發明的思想的範圍，只要是熟悉該項技藝者(業者)，就可能會想到各種變更例及修正例，針對這些變更例及修正例也應該理解為屬於本發明的範圍。 　　[0164] 例如，對於前述各實施形態，熟悉該項技藝者進行適當的、構成要素的追加、削減或者設計變更者，或者進行了步驟的追加、省略或者條件變更者，只要具備本發明之要旨，都包含於本發明的範圍。[0025] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. [0026] Also, the disclosure is only an example after all, and those who are familiar with the art will obviously think of appropriate changes under the gist of the invention, which of course are all included in the scope of the present invention. In addition, the drawings can make the description more clear, and when the width, thickness, shape, etc. of each part are schematically shown compared with the embodiment, it is only an example after all, and is not intended to limit the present invention. explain. [0027] In addition, in this specification and each drawing, the same reference numerals are given to the same elements as those described above, and detailed descriptions are appropriately omitted. [0028] Furthermore, in the drawings used in the embodiments, there are occasions where hatching (network lines) given for distinguishing structures is omitted in accordance with the drawings. (Embodiment) <Membrane structure> First, a membrane structure in an embodiment of an embodiment of the present invention will be described. Fig. 1 is a cross-sectional view of a membrane structure according to an embodiment. 2 is a cross-sectional view of the membrane structure in the case where the membrane structure of the embodiment has a conductive film as the upper electrode. [0030] As shown in FIG. 1 , the film structure 10 of this embodiment includes a substrate 11, an alignment film 12, a conductive film 13, a conductive film 14, and a piezoelectric film 15. The alignment film 12 is formed on the substrate 11 . The conductive film 13 is formed on the alignment film 12 . The conductive film 14 is formed on the conductive film 13 . The piezoelectric film 15 is formed on the conductive film 14 . [0031] Further, as shown in FIG. 2, the film structure 10 of the present embodiment may have a conductive film 16. The conductive film 16 is formed on the piezoelectric film 15 . At this time, the conductive films 13 and 14 serve as the conductive film of the lower electrode, and the conductive film 16 serves as the conductive film of the upper electrode. Thereby, an electric field can be applied to the piezoelectric film 15 in the thickness direction. [0032] The substrate 11 is, for example, a silicon substrate made of silicon (Si) single crystal. Moreover, the board|substrate 11 has the upper surface 11a which is a main surface. [0033] The alignment film 12 includes, for example, zirconium oxide (ZrO ₂ ) epitaxially grown on the upper surface 11a of the substrate 11. The conductive film 13 is made of metal, for example, platinum (Pt) epitaxially grown on the alignment film 12 . The conductive film 14 is epitaxially grown on the conductive film 13 . The piezoelectric film 15 is epitaxially grown on the conductive film 14 . Here, when two directions orthogonal to each other in the upper surface 11a serving as the main surface of the substrate 11 are referred to as the X-axis direction and the Y-axis direction, and the direction perpendicular to the upper surface 11a is referred to as the Z-axis direction, a certain film Epitaxial growth means that the film is oriented in any one of the X-axis direction, the Y-axis direction, and the Z-axis direction. The alignment film 12 is not epitaxially grown on the substrate 11, and when the conductive film 13 is not epitaxially grown on the alignment film 12, the conductive film 14 cannot be epitaxially grown on the conductive film 13, and the conductive film 14 cannot be epitaxially grown. The piezoelectric film 15 is epitaxially grown thereon. The piezoelectric constants d33 and d31 are large when an electric field is applied to the piezoelectric film 15 in a direction parallel to the polarizing direction, or a direction having a certain angle with the polarizing direction, for example. Therefore, when the piezoelectric film 15 is not epitaxially grown, since the polarization directions of the entire piezoelectric film 15 are not uniform, the piezoelectric constants d33 and d31 of the piezoelectric film 15 cannot be increased, and the characteristics of the piezoelectric element are degraded . On the other hand, in this embodiment, since the alignment film 12 is epitaxially grown on the substrate 11, the conductive film 13 is epitaxially grown on the alignment film 12, and the conductive film 14 can be epitaxially grown on the conductive film 13. , the piezoelectric film 15 can be epitaxially grown on the conductive film 14 . Therefore, the polarization directions of the entire piezoelectric film 15 can be unified, the piezoelectric constants d33 and d31 of the piezoelectric film 15 can be increased, and the characteristics of the piezoelectric element can be improved. [0037] Preferably, the conductive film 14 includes a metal oxide, including strontium ruthenate (SrRuO ₃ , also referred to as SRO hereinafter) epitaxially grown on the alignment film 12. Further, the piezoelectric film 15 includes lead zirconate titanate (Pb(Zr _1-x Ti _x )O ₃ (0<x<1), which is epitaxially grown on the conductive film 13 via the conductive film 14 , below Also referred to as PZT). [0038] Since the piezoelectric film 15 contains PZT, the piezoelectric constant of the piezoelectric film 15 can be increased compared to the case where the piezoelectric film 15 does not contain PZT. [0039] In addition, the SRO contained in the conductive film 14 has the crystal structure of the PZT contained in the piezoelectric film 15, which is the same as the perovskite structure. Therefore, the PZT contained in the piezoelectric film 15 can be easily aligned in a certain direction. In addition, since the PZT contained in the piezoelectric film 15 has a tetragonal crystal structure or a rhombohedral crystal structure, the PZT contained in the piezoelectric film 15 is easily oriented in a certain direction, and the polarization directions are easily unified. In a certain direction, improve the piezoelectric properties. [0040] Also, as shown in FIG. 12 described later, the film structure 10 may not have the conductive film 14, and the piezoelectric film 15 may be directly formed on the conductive film 13. In this case, the piezoelectric film 15 is less likely to be aligned than the case where the piezoelectric film 15 is formed on the conductive film 14 containing SRO, but can be aligned in a certain direction even on the conductive film 13 containing platinum. [0041] Preferably, the silicon single crystal contained in the substrate 11 has the upper surface 11a as the main surface composed of the (100) plane in the crystal structure of the cubic crystal. The zirconium oxide (ZrO ₂ ) contained in the alignment film 12 has a cubic crystal structure and is (100) aligned. Platinum (Pt) contained in the conductive film 13 has a cubic crystal structure and has a (100) orientation. [0042] Thereby, when the SRO included in the conductive film 14 has a quasi-cubic crystal structure, the conductive film 14 can be aligned (100) on the substrate 11. In addition, when the PZT contained in the piezoelectric film 15 has a tetragonal crystal structure, the piezoelectric film 15 can be (001) aligned on the substrate 11; in the case where the PZT contained in the piezoelectric film 15 has a rhombohedron In the case of the crystal structure of the crystal, the piezoelectric film 15 can be aligned (100) on the substrate 11. [0043] Here, the alignment film 12 is (100) alignment, which means that the (100) plane of the alignment film 12 having a cubic crystal structure is along the substrate 11 composed of silicon single crystal, and the (100) plane is The upper surface 11a constituted by the surface is the main surface. In addition, the alignment film 12 is (100) aligned, preferably the (100) plane of the alignment film 12 is the upper surface 11a composed of the (100) plane parallel to the substrate 11 composed of silicon single crystal. In addition, the upper surface 11a formed by the (100) plane of the alignment film 12 being parallel to the (100) plane of the substrate 11 refers not only to the case where the (100) plane of the alignment film 12 is completely parallel to the upper surface 11a of the substrate 11, but also includes When the angle between the surface completely parallel to the upper surface 11a of the substrate 11 and the (100) surface of the alignment film 12 is 20° or less. In addition, zirconia as a bulk material has a monoclinic crystal structure at room temperature, and when the temperature is raised from room temperature, it is phase-transferred at about 1170 ° C and has a tetragonal crystal structure, and then When the temperature is raised, the phase transitions at about 2370° C. and becomes a crystal structure having a cubic crystal. However, since stress is applied to the zirconia contained in the alignment film 12 from the upper and lower films or the substrate, the behavior of the phase transition of the zirconia contained in the alignment film 12 and the behavior of the phase transition of the zirconia as the bulk material not different. In addition, since the thickness of the alignment film 12 is as thin as several 10 nm or less, it is difficult to accurately distinguish the crystal structure of the zirconia contained in the alignment film 12 as a tetragonal crystal structure or a cubic crystal structure. . [0045] Therefore, in the following, the case where the zirconia contained in the alignment film 12 has a tetragonal crystal structure is regarded as a case where the zirconia has a cubic crystal structure. That is, in the present specification, when the zirconium oxide contained in the alignment film 12 has a cubic crystal structure, it includes the case where it actually has a cubic crystal structure and the actual non-cubic crystal structure. In the case of tetragonal crystal structure. In addition, in the same manner, in the following, there are cases where the SRO included in the conductive film 14 has an orthorhombic crystal structure, and the SRO is considered to have a quasi-cubic crystal structure. This is the case where the SRO has a cubic crystal structure. That is, in the present specification, when the SRO included in the conductive film 14 has a cubic crystal structure, it includes the case where the crystal structure actually has a cubic crystal, and the actual non-cubic crystal structure has a crystal structure. Orthorhombic, that is, the case of quasi-cubic crystal structure. [0047] Preferably, the piezoelectric film 15 has a tetragonal crystal structure and a (001) orientation. In Pb(Zr _1-x Ti _x )O ₃ (0<x<1), x is 0. By satisfying 48<x<1, the PZT contained in the piezoelectric film 15 has a tetragonal crystal structure, and it is easy to epitaxially grow and to easily (001) align. Therefore, when the PZT having a tetragonal crystal structure is (001) oriented, the polarization direction parallel to the [001] direction and the electric field direction parallel to the thickness direction of the piezoelectric film 15 are parallel to each other, so that the piezoelectric characteristics are improved. promote. That is, when an electric field along the [001] direction is applied to PZT having a tetragonal crystal structure, large piezoelectric constants d33 and d31 can be obtained. Therefore, the piezoelectric constant of the piezoelectric film 15 can be further increased. [0048] Alternatively, preferably, the piezoelectric film 15 has a rhombohedral crystal structure and has a (100) orientation. Since x in Pb(Zr _1-x Ti _x )O ₃ (0<x<1) is 0.20<x≦0.48, the PZT contained in the piezoelectric film 15 has a rhombohedral crystal structure, and it is easy to Epitaxial growth and easy (100) alignment. Therefore, when the PZT having a rhombohedral crystal structure is (100) oriented, the PZT has a so-called Engineered Domain Configuration, which is parallel to the polarization direction of each direction equivalent to the [111] direction, and parallel to the pressure direction. The angle of the electric field direction in the thickness direction of the electric film 15 is equal to each other in any of the divided domains, thereby improving the piezoelectric properties. That is, when an electric field along the [100] direction is applied to PZT having a rhombohedral crystal structure, large piezoelectric constants d33 and d31 can be obtained. Therefore, the piezoelectric properties of the piezoelectric film 15 can be further increased. [0049] FIG. 3 is a diagram illustrating a state of epitaxial growth of an alignment film included in the film structure of the embodiment. On the other hand, FIG. 4 is a diagram illustrating a state in which the alignment film included in the film structure has not undergone epitaxial growth. 3 schematically shows the layers of the substrate 11 , the alignment film 12 , the conductive films 13 and 14 , and the piezoelectric film 15 ; and FIG. 4 schematically shows the substrate 11 and the alignment film 12 . The lattice constant of silicon included in the substrate 11, the lattice constant of ZrO ₂ included in the alignment film 12, the lattice constant of Pt included in the conductive film 13, the lattice constant of SRO included in the film 14, Table 1 shows the lattice constants of PZT contained in the piezoelectric film 15 . [0051]

As shown in Table 1, the lattice constant of silicon is 0.543 nm, the lattice constant of ZrO ₂ is 0.514 nm, and the unintegration of the lattice constant of ZrO ₂ to the lattice constant of silicon is as small as 5.3%, so The lattice constant of ZrO ₂ is well integrated with the lattice constant of silicon. Therefore, as shown in FIG. 3 , the alignment film 12 containing ZrO ₂ can be epitaxially grown on the main surface constituted by the (100) plane of the substrate 11 containing silicon single crystal. Therefore, the alignment film 12 containing ZrO ₂ can be oriented to (100) with a cubic crystal structure on the (100) plane of the substrate 11 containing silicon single crystal, and the crystallinity of the alignment film 12 can be improved. In addition, as shown in Table 1, the lattice constant of ZrO ₂ is 0.514 nm, and the lattice constant of platinum is 0.392 nm, but when platinum is rotated 45° in the plane, the length of the diagonal line is 0.554 nm, and the The unintegration of the length of the diagonal line to the lattice constant of ZrO ₂ is as small as 7.8%, so the integration of the lattice constant of platinum to the lattice constant of ZrO ₂ is good. Therefore, as shown in FIG. 3 , the conductive film 13 containing platinum can have a (100) orientation with a cubic crystal structure on the (100) plane of the alignment film 12 containing ZrO ₂ , so that the conductivity of the conductive film 13 can be improved. crystallinity. In addition, as shown in Table 1, the lattice constant of platinum is 0.392 nm, the lattice constant of SRO is 0.390 to 0.393 nm, and the unconformity between the lattice constant of SRO and the lattice constant of platinum is less than 0.51% , so the lattice constant of SRO has good integration with that of platinum. Therefore, the SRO-containing conductive film 14 can have a (100) orientation with a cubic crystal structure on the (100) plane of the platinum-containing conductive film 13, and the crystallinity of the conductive film 14 can be improved. In addition, as shown in Table 1, the lattice constant of SRO is 0.390 to 0.393 nm, the lattice constant of PZT is 0.401 nm, and the unconformity between the lattice constant of PZT and the lattice constant of SRO is as small as 2.0 to 2.8 %, so the lattice constant of PZT has good integration with that of SRO. Therefore, the piezoelectric film 15 containing PZT can have a (001) orientation with a tetragonal crystal structure on the (100) plane of the conductive film 14 containing SRO, or a (001) orientation with a rhombohedral crystal structure. 100) alignment, the crystallinity of the piezoelectric film 15 can be improved. [0056] On the other hand, as shown in FIG. 4, in the state where the ZrO ₂ -containing alignment film 12 and the main surface constituted by the (100) plane of the silicon-containing single crystal substrate 11 are not epitaxially grown, for example The ZrO ₂ -containing alignment film 12 has a (111) alignment on the (100) plane of the silicon single crystal-containing substrate 11, for example, with a cubic crystal structure. Therefore, the crystallinity of the alignment film 12 cannot be improved. In addition, as shown in FIG. 4, in the state where the ZrO ₂ -containing alignment film 12 and the main surface constituted by the (100) plane of the silicon-containing single crystal substrate 11 are not epitaxially grown, although in FIG. 4. Although illustration is omitted, the platinum-containing conductive film 13 has, for example, a cubic crystal structure and a (111) orientation. Therefore, the crystallinity of the conductive film 13 cannot be improved. Therefore, when the platinum-containing conductive film 13 has, for example, a cubic crystal structure and a (111) orientation, the SRO-containing conductive film 14 cannot have a cubic crystal structure and a (100) orientation, and the PZT-containing conductive film 14 cannot be oriented. The piezoelectric film 15 has a tetragonal crystal structure and a (001) orientation, or a rhombohedral crystal structure and a (100) orientation. [0058] Preferably, the alignment film 12 has a thickness of 13 to 22 nm. When the thickness of the alignment film 12 is less than 13 nm, since the thickness of the alignment film 12 is too thin, the effect of easy epitaxial growth of the alignment film 12 on the substrate 11 is reduced. Therefore, when the thickness of the alignment film 12 is less than 13 nm, a part of the alignment film 12 is not (100) aligned but (111) aligned. [0059] In addition, when the thickness of the alignment film 12 exceeds 22 nm, because the thickness of the alignment film 12 is too thick, the effect of easy epitaxial growth of the alignment film 12 on the substrate 11 is reduced. Therefore, when the thickness of the alignment film 12 exceeds 22 nm, a part of the alignment film 12 is not (100) aligned but (111) aligned. 5 is a cross-sectional view of the film structure in the case where the alignment film of the film structure of the embodiment has a two-layer structure. [0061] The alignment film 12 may also include a film 12a and an alignment film 12b. The film 12a contains zirconium formed on the substrate 11, but the zirconium contained in the film 12a is not oxidized, but is metal zirconium. That is, the film 12a is a metal film containing zirconium. On the other hand, the alignment film 12b includes zirconia epitaxially grown on the film 12a. Therefore, the alignment film 12 shown in FIGS. 1 and 2 is equivalent to the alignment film 12b shown in FIG. 5 . [0062] When the alignment film 12b is formed on the substrate 11 via the film 12a, epitaxial growth is easier than when the alignment film 12b is formed on the substrate 11 without interposing the film 12a. Therefore, the alignment film 12b containing ZrO ₂ can be more stabilized and epitaxially grown on the upper surface 11a which is the main surface constituted by the (100) plane of the substrate 11 containing silicon single crystal. Therefore, the alignment film 12 containing ZrO ₂ can be more stabilized and (100) aligned on the (100) surface of the substrate 11 containing silicon single crystal, and the crystallinity of the alignment film 12 can be further improved. [0063] However, when the alignment film 12b containing ZrO ₂ is formed, the zirconium contained in the film 12a may be oxidized, so that the film 12a may be destroyed and the alignment film 12b may be formed. In such a case, as shown in FIG. 1 , the alignment film 12 b is directly formed on the substrate 11 , and the alignment film 12 including only the directly formed alignment film 12 b is formed on the substrate 11 . [0064] Preferably, the film 12a has a thickness of 5 to 10 nm. When the thickness of the film 12a is less than 5 nm, since the thickness of the film 12a is too thin, the effect of facilitating the epitaxial growth of the alignment film 12b on the substrate 11 is reduced. Therefore, when the thickness of the film 12a is less than 5 nm, a part of the alignment film 12b is not (100) aligned but (111) aligned. [0065] In addition, when the thickness of the film 12a exceeds 10 nm, since the thickness of the film 12a is too thick, the effect of easy epitaxial growth of the alignment film 12b on the substrate 11 is reduced. Therefore, when the thickness of the film 12a exceeds 10 nm, a part of the alignment film 12b is not (100) aligned but (111) aligned. [0066] Preferably, the alignment film 12b has a thickness of 8 to 12 nm. When the thickness of the alignment film 12b is less than 8 nm, since the thickness of the alignment film 12b is too thin, the effect of facilitating the epitaxial growth of the alignment film 12b on the substrate 11 is reduced. Therefore, when the thickness of the alignment film 12b is less than 8 nm, a part of the alignment film 12b is not (100) aligned but (111) aligned. [0067] In addition, when the thickness of the alignment film 12b exceeds 12 nm, since the thickness of the alignment film 12b is too thick, the effect of easy epitaxial growth of the alignment film 12b on the substrate 11 is reduced. Therefore, when the thickness of the alignment film 12b exceeds 12 nm, a part of the alignment film 12b is not (100) aligned but (111) aligned. [0068] In addition, the film structure 10 of the present embodiment may not include the conductive film 14 and the piezoelectric film 15, but may include only the substrate 11, the alignment film 12, and the conductive film 13. Even in such a case, by forming the piezoelectric film 15 and the conductive film 16 as the upper electrode on the film structure 10, it is possible to easily form a structure having the conductive film 13 and the conductive film 16 sandwiched from above and below. Piezoelectric element of the piezoelectric film 15 . [0069] <Manufacturing Method of Membrane Structure> Next, the manufacturing method of the membrane structure of the present embodiment will be described. 6 to 11 are cross-sectional views in the production steps of the membrane structure of the embodiment. [0070] First, as shown in FIG. 6, a substrate 11 as a silicon substrate is prepared (step S1). [0071] Preferably, the substrate 11 has a cubic crystal structure, and has an upper surface 11a as a main surface consisting of a (100) plane. In addition, on the upper surface 11d of the substrate 11, an oxide film such as a _SiO2 film as a natural oxide film may be formed. [0072] Further, as the substrate 11, various substrates other than silicon substrates can be used, for example, substrates formed of various semiconductor single crystals other than silicon can be used. As shown in FIG. 6, two mutually orthogonal directions in the upper surface 11a formed by the (100) plane of the substrate 11 composed of the silicon single crystal are set as the X-axis direction and the Y-axis direction, which are perpendicular to the upper surface 11a. is set to the Z-axis direction. [0074] Next, as shown in FIG. 7, the film 12a is formed (step S2). In this step S2, on the substrate 11, a film 12a containing zirconium is formed. [0075] In step S2, the case where the alignment film 12 is formed by the electron beam vapor deposition method is described as an example, but it may be formed by various methods such as sputtering. In step S2, first, the substrate 11 is set in the vacuum chamber of the electron beam evaporation apparatus, and the pressure in the vacuum chamber is adjusted to a state under a certain vacuum atmosphere such as 2.1×10 ⁻⁵ Pa, and the substrate 11 is placed in a vacuum chamber. 11 Heat to, for example, 600-750°C. [0077] In step S2, secondly, zirconium is evaporated by an electron beam evaporation method using an evaporation material of zirconium (Zr) single crystal. At this time, the evaporated zirconium is formed into a zirconium (Zr) film. Then, on the substrate 11, a zirconium-containing film 12a having a thickness of, for example, 20 nm or less is formed. In addition, the zirconium contained in the film 12a is not oxidized, but is metal zirconium. That is, the film 12a is a metal film containing zirconium. [0078] Preferably, in step S2, a film 12a having a thickness of 5 to 10 nm is formed. When the thickness of the film 12a is less than 5 nm, the thickness of the film 12a is too thin, and the effect of facilitating the epitaxial growth of the alignment film 12b (see FIG. 8 to be described later) on the substrate 11 is reduced. Therefore, when the thickness of the film 12a is less than 5 nm, a part of the alignment film 12b is not (100) aligned but (111) aligned. [0079] In addition, when the thickness of the film 12a exceeds 10 nm, since the thickness of the film 12a is too thick, the effect of the easy epitaxial growth of the alignment film 12b on the substrate 11 is reduced. Therefore, when the thickness of the film 12a exceeds 10 nm, a part of the alignment film 12b is not (100) aligned but (111) aligned. [0080] Preferably, in step S2, the film 12a is formed at a temperature of 650 to 700°C. When the temperature of the substrate 11 is lower than 650° C., the temperature of the substrate 11 is too low, and the effect of facilitating the epitaxial growth of the alignment film 12 b on the substrate 11 is reduced. Therefore, when the temperature of the substrate 11 is lower than 650° C., a part of the alignment film 12 b is not (100) aligned but (111) aligned. [0081] In addition, when the temperature of the substrate 11 exceeds 700° C., the temperature of the substrate 11 is too high, and the effect of facilitating the epitaxial growth of the alignment film 12b on the substrate 11 is reduced. Therefore, when the temperature of the substrate 11 exceeds 700° C., a part of the alignment film 12 b is not (100) aligned but (111) aligned. [0082] Next, as shown in FIG. 8, the alignment film 12b is formed (step S3). In this step S3, an alignment film 12b containing zirconia grown epitaxially on the film 12a is formed. [0083] In step S3, similarly to step S2, the case where the alignment film 12 is formed by the electron beam evaporation method is exemplified, but various methods such as sputtering may be used. In step S3, first, after the substrate 11 is set in the vacuum chamber of the electron beam evaporation apparatus, oxygen gas (O ₂ ) is flowed into the vacuum chamber at a flow rate of, for example, 10 sccm, and the pressure in the vacuum chamber is adjusted to, for example, 7.0× In the state of 10 ^-3 Pa, the substrate 11 is heated to, for example, 500 to 600°C. [0085] In step S3, secondly, zirconium is evaporated by an electron beam evaporation method using an evaporation material of zirconium (Zr) single crystal. At this time, the evaporated zirconium reacts with oxygen on the film 12a to form a zirconium oxide (ZrO ₂ ) film. Next, an alignment film 12b composed of a ZrO ₂ film is formed as a single-layer film. Next, an alignment film 12b containing zirconium oxide, which is epitaxially grown on the film 12a containing zirconium, is formed. [0086] The alignment film 12b is epitaxially grown through the film 12a on the upper surface 11a which is the main surface constituted by the (100) plane of the substrate 11 made of silicon single crystal. The alignment film 12 has a cubic crystal structure and includes (100) oriented zirconia (ZrO ₂ ). That is, on the upper surface 11a composed of the (100) plane of the substrate 11 composed of silicon single crystal, the alignment film 12 containing zirconium oxide (ZrO ₂ ) having the (100) alignment is formed via the film 12a. [0087] As described using the aforementioned FIG. 6 , two directions orthogonal to each other in the upper surface 11a formed by the (100) plane of the substrate 11 formed of a silicon single crystal are referred to as the X-axis direction and the Y-axis direction, Let the direction perpendicular to the upper surface 11a be the Z-axis direction. At this time, epitaxial growth of a certain film means that the film is aligned in any one of the X-axis direction, the Y-axis direction, and the Z-axis direction. [0088] Preferably, in step S3, an alignment film 12b having a thickness of 8-12 nm is formed. When the thickness of the alignment film 12b is less than 8 nm, since the thickness of the alignment film 12b is too thin, the effect of facilitating the epitaxial growth of the alignment film 12b on the substrate 11 is reduced. Therefore, when the thickness of the alignment film 12b is less than 8 nm, a part of the alignment film 12b is not (100) aligned but (111) aligned. [0089] In addition, when the thickness of the alignment film 12b exceeds 12 nm, since the thickness of the alignment film 12b is too thick, the effect of easy epitaxial growth of the alignment film 12b on the substrate 11 is reduced. Therefore, when the thickness of the alignment film 12b exceeds 12 nm, a part of the alignment film 12b is not (100) aligned but (111) aligned. [0090] As described above, preferably, in step S3, the alignment film 12b is formed at a temperature of 500-600°C. When the temperature of the substrate 11 is lower than 500° C., the temperature of the substrate 11 is too low, for example, the zirconium atoms and oxygen atoms on the film 12a are not easily relocated, so that the alignment film 12b on the substrate 11 is prone to epitaxial growth. effect is reduced. Therefore, when the temperature of the substrate 11 is lower than 500° C., a part of the alignment film 12 b is not (100) aligned but (111) aligned. [0091] In addition, when the temperature of the substrate 11 exceeds 600° C., the temperature of the substrate 11 is too high, and the effect of facilitating the epitaxial growth of the alignment film 12b on the substrate 11 is reduced. Therefore, when the temperature of the substrate 11 exceeds 600° C., a part of the alignment film 12 b is not (100) aligned but (111) aligned. [0092] When the alignment film 12b containing ZrO ₂ is formed, the zirconium contained in the film 12a is oxidized, so that the film 12a is destroyed and the alignment film 12b is formed. In such a case, as shown in FIG. 9 , the alignment film 12 b is directly formed on the substrate 11 , and the alignment film 12 including only the directly formed alignment film 12 b is formed on the substrate 11 . Therefore, it is preferable to form an alignment film 12 including a new alignment film 12b having a total thickness of 13 to 22 nm using the film 12a having a thickness of 5 to 10 nm and the original alignment film 12b having a thickness of 8 to 12 nm. In the following description, as shown in FIG. 9 , in step S3 , the case where the alignment film 12 b is directly formed on the substrate 11 will be described as an example. [0093] Next, as shown in FIG. 10, the conductive film 13 is formed (step S4). In this step S4, the conductive film 13 as a part of the lower electrode, which is epitaxially grown on the alignment film 12b, is formed. The conductive film 13 is made of metal. As the conductive film 13 made of metal, for example, a conductive film containing platinum (Pt) can be used. As the conductive film 13, when a conductive film containing platinum is formed, the conductive film 13 is epitaxially grown on the alignment film 12 at a temperature of 550° C. or lower, preferably 400° C. by sputtering. , formed as part of the lower electrode. The conductive film 13 containing platinum is epitaxially grown on the alignment film 12b. In addition, platinum contained in the conductive film 13 has a cubic crystal structure and has a (100) orientation. [0095] Further, as the conductive film 13 made of metal, instead of the conductive film containing platinum (Pt), for example, a conductive film containing iridium (Ir) may be used instead. [0096] Next, as shown in FIG. 11, the conductive film 14 is formed (step S5). In this step S5, the conductive film 14 which is epitaxially grown on the conductive film 13 as a part of the lower electrode is formed. The conductive film 14 is made of metal oxide. As the conductive film 14 made of a metal oxide, for example, a conductive film containing strontium ruthenate (SrRuO ₃ :SRO) can be used. When forming the conductive film containing SRO as the conductive film 14, the conductive film 14 epitaxially grown on the conductive film 13 at a temperature of about 600° C. is formed as a part of the lower electrode by sputtering. . The conductive film 14 containing SRO is epitaxially grown on the conductive film 13 . In addition, the SRO included in the conductive film 14 has a cubic crystal structure and a (100) orientation. In addition, as the conductive film 14 composed of metal oxide, it is also possible to replace the conductive film containing SRO, and for example, strontium titanate ruthenate (Sr(Ti _y Ru _1-y )O ₃ (O ) can be used instead. ≦y≦0.4)) conductive film. [0099] Next, as shown in FIG. 1, the piezoelectric film 15 is formed (step S6). In this step S6, an epitaxially grown lead zirconate titanate (Pb(Zr _1-x Ti) is formed on the conductive film 14 by a coating method such as a sol-gel method or a sputtering method. The piezoelectric film 15 of _x )O ₃ (0<x<1):PZT). In addition, in the case where the piezoelectric film 15 is formed by the sol-gel method, in step S6, first, the conductive film 14 is repeatedly applied a plurality of times, and a solution containing lead, zirconium and titanium is applied to form a solution containing lead, zirconium and titanium. The step of filming the precursor of PZT. Thereby, a film including a plurality of films stacked on each other is formed. [0101] Next, when the piezoelectric film 15 is formed by the sol-gel method, in step S6, the precursor is oxidized and crystallized by heat treatment of the film, thereby forming the piezoelectric film 15 containing PZT. [0102] Preferably, the piezoelectric film 15 has a tetragonal crystal structure and a (001) orientation. Since x in Pb(Zr _1-x Ti _x )O ₃ (0<x<1) is 0.48<x<1, the PZT included in the piezoelectric film 15 has a tetragonal crystal structure, and it is easy to make epitaxial Growth, easy (001) alignment. Therefore, when the PZT having a tetragonal crystal structure is (001) oriented, the polarization direction parallel to the [001] direction and the electric field direction parallel to the thickness direction of the piezoelectric film 15 are parallel to each other, so that the piezoelectric characteristics are improved. promote. That is, when an electric field along the [001] direction is applied to PZT having a tetragonal crystal structure, large piezoelectric constants d33 and d31 can be obtained. Therefore, the piezoelectric constant of the piezoelectric film 15 can be further increased. [0103] Alternatively, preferably, the piezoelectric film 15 has a rhombohedral crystal structure and has a (100) orientation. Since x in Pb(Zr _1-x Ti _x )O ₃ (0<x<1) is 0.20<x≦0.48, the PZT included in the piezoelectric film 15 has a rhombohedral crystal structure, and it is easy to make Epitaxial growth, easy (100) alignment. Therefore, when the PZT having a rhombohedral crystal structure is (100) oriented, the PZT has a so-called Engineered Domain Configuration, which is parallel to the polarization direction of each direction equivalent to the [111] direction, and parallel to the pressure direction. The angle of the electric field direction in the thickness direction of the electric film 15 is equal to each other in any of the divided domains, thereby improving the piezoelectric properties. That is, when an electric field along the [100] direction is applied to PZT having a rhombohedral crystal structure, large piezoelectric constants d33 and d31 can be obtained. Therefore, the piezoelectric properties of the piezoelectric film 15 can be further increased. [0104] In this way, the membrane structure 10 shown in FIG. 1 is formed. When the alignment film 12b is formed, the film structure 10 shown in FIG. 5 is formed when the film 12a remains without being destroyed. [0105] When the alignment film 12b containing zirconium oxide (ZrO ₂ ) is directly formed on the substrate 11, which is a silicon substrate, the crystallinity of the formed ZrO ₂ film is lowered, and the alignment film 12b cannot be epitaxially grown well. occasion. In such a case, the conductive film 13 cannot be epitaxially grown on the alignment film 12 b , and the piezoelectric film 15 cannot be epitaxially grown on the conductive film 13 . The piezoelectric constants d33 and d31 are large when an electric field is applied to the piezoelectric film 15 in a direction parallel to the polarizing direction, or a direction having a certain angle with the polarizing direction, for example. Therefore, when the piezoelectric film 15 is not epitaxially grown well, since the polarization directions of the entire piezoelectric film 15 are not uniform, the piezoelectric constants d33 and d31 of the piezoelectric film 15 cannot be increased. characteristics are reduced. [0106] On the other hand, in this embodiment, after the zirconium (Zr)-containing film 12a is formed on the substrate 11, the ZrO ₂ -containing alignment film 12b is epitaxially grown on the substrate 11. The zirconium contained in the film 12a is metal zirconium without being oxidized. In such a case, compared with the case where the alignment film 12b containing ZrO ₂ is directly formed on the substrate 11 , the former can make the alignment film 12 epitaxially grow well. Therefore, the conductive film 13 can be favorably epitaxially grown on the alignment film 12 b , and the piezoelectric film 15 can be favorably grown on the conductive film 13 by epitaxial growth. Therefore, the polarization directions of the entire piezoelectric film 15 can be unified, the piezoelectric constants d33 and d31 of the piezoelectric film 15 can be increased, and the characteristics of the piezoelectric element can be improved. [0107] Further, after the piezoelectric film 15 is formed, as step S7, a conductive film 16 (refer to FIG. 2 ) as an upper electrode may be formed on the piezoelectric film 15. Thereby, an electric field can be applied to the piezoelectric film 15 in the thickness direction. [0108] <Modification of the embodiment> In the embodiment, as shown in FIG. 1 , the piezoelectric film 15 is formed on the conductive film 13 with the conductive film 14 interposed therebetween. However, the piezoelectric film 15 may be directly formed on the conductive film 13 without interposing the conductive film 14 therebetween. Such an example will be described as a modification of the embodiment. 12 is a cross-sectional view of a membrane structure according to a modification of the embodiment. [0110] As shown in FIG. 12 , the film structure 10 of this modification example includes a substrate 11, an alignment film 12, a conductive film 13, and a piezoelectric film 15. The alignment film 12 is formed on the substrate 11 . The conductive film 13 is formed on the alignment film 12 . The piezoelectric film 15 is formed on the conductive film 13 . That is, the film structure 10 of this modification is different from the film of the embodiment except that the piezoelectric film 15 is directly formed on the conductive film 13 without interposing the conductive film 14 (see FIG. 1 ). The structures 10 are the same. On the platinum-containing conductive film 13, when the PZT-containing piezoelectric film 15 is formed without interposing the SRO-containing conductive film 14 (refer to FIG. 1), compared with the platinum-containing conductive film 13, When the piezoelectric film 15 containing PZT is formed through the conductive film 14 containing SRO (see FIG. 1 ), the crystallinity of the piezoelectric film 15 is relatively lowered. However, when the PZT-containing piezoelectric film 15 is formed on the platinum-containing conductive film 13 without interposing the SRO-containing conductive film 14 (see FIG. 1 ), the conductive film 13 on the alignment film 12 can be easily aligned or epilated crystal growth. Therefore, the piezoelectric film 15 formed on the conductive film 13 can also be easily aligned or epitaxially grown to some extent, and the crystallinity of the piezoelectric film 15 can be improved to some extent. [0113] In addition, the membrane structure 10 of the present modification may include the conductive film 16 (see FIG. 2 ), similarly to the membrane structure 10 of the embodiment. [Examples] [0114] Hereinafter, the present embodiment will be described in more detail based on examples. In addition, this invention is not limited by the following Examples. (Examples 1 to 60) Hereinafter, the membrane structure 10 described in the embodiment with reference to FIG. 1 is formed as the membrane structure of Examples 1 to 60. The film structures of Examples 1 to 60 were formed by changing the thickness of the film 12a (see FIG. 7 ), the substrate temperature when the film 12a was formed, and the substrate temperature when the alignment film 12b (see FIG. 8 ) was formed, respectively. Membrane constructs. [0116] First, as shown in FIG. 6, as the substrate 11, the upper surface 11a as the main surface constituted by the (100) plane is prepared, and a wafer constituted by a 6-inch silicon substrate is prepared. [0117] Next, as shown in FIG. 7 , on the substrate 11, a zirconium (Zr) film was formed as a film 12a by an electron beam vapor deposition method. The conditions at this time are shown below. Apparatus: Electron beam deposition apparatus Pressure: 2.10×10 ^-5 Pa Evaporation source: Zr Accelerating voltage/radiation current: 7.5kV/1.50mA Thickness: 20nm or less Film-forming speed: 0.005nm/s Oxygen flow rate: 0sccm Substrate temperature: 600 to 750° C. [0118] Next, as shown in FIG. 8 , as the alignment film 12 , a zirconium oxide (ZrO ₂ ) film was formed by an electron beam vapor deposition method. The conditions at this time are shown below. Apparatus: Electron beam deposition apparatus Pressure: 7.00×10 ^-3 Pa Evaporation source: Zr+O ₂ Accelerating voltage/radiation current: 7.5kV/1.80mA Thickness: 10nm Film-forming speed: 0.005nm/s Oxygen flow rate: 10sccm Substrate Temperature: 500 _～ 600℃ ~Table 4. In Examples 1 to 20 shown in Table 2, the substrate temperature at the time of forming the ZrO ₂ film was 500°C. In Examples 21 to 40 shown in Table 3, the substrate temperature at the time of forming the ZrO ₂ film was 550°C. Next, in Examples 41 to 60 shown in Table 4, the substrate temperature at the time of forming the ZrO ₂ film was 600°C. In addition, as described above, the thickness of the ZrO ₂ film in each of Examples 1 to 60 was 10 nm. In addition, in Tables 2 to 4, the evaluation results of the crystallinity of the ZrO ₂ film are shown by single-turn and double-turn. In the case of double turns, the crystallinity is higher than that of single turns. [0120]

[0121]

[0122]

[0123] For Examples 1 to 60, the θ-2θ spectrum of the film structure formed up to the ZrO ₂ film was measured by X-ray Diffraction (XRD) method. 13 and 14 are diagrams showing an example of the θ-2θ spectrum of the film structure formed up to the ZrO ₂ film according to the XRD method. The horizontal axis of each of the graphs of FIGS. 13 and 14 shows the angle 2θ, and the vertical axis of each of the graphs of FIGS. 13 and 14 shows the intensity of X-rays. 13 illustrates a case where the thickness of the zirconium film is 7 nm, the substrate temperature when the zirconium film is formed is 700°C, and the substrate temperature when the ZrO ₂ film is formed is 550°C. 14 illustrates a case where the thickness of the zirconium film is 7 nm, the substrate temperature when the zirconium film is formed is 750°C, and the substrate temperature when the ZrO ₂ film is formed is 550°C. In addition, in FIGS. 13 and 14 , T-ZrO ₂ means tetragonal ZrO ₂ , and M-ZrO ₂ means monoclinic ZrO ₂ . Also, as described above, it is assumed that tetragonal ZrO ₂ is contained in cubic ZrO ₂ . [0125] In the example shown in FIG. 13 , in the θ-2θ spectrum, a peak corresponding to (200) of ZrO ₂ having a tetragonal crystal structure was observed. Therefore, it can be seen that the alignment film 12b has a tetragonal crystal structure and includes ZrO ₂ of (100) alignment. [0126] In addition, in the example shown in FIG. 13 , in the θ-2θ spectrum, no peaks other than the (200) peak corresponding to ZrO ₂ having a tetragonal crystal structure were observed. Therefore, it can be seen that the alignment film 12b has a tetragonal crystal structure and ZrO ₂ oriented in planes other than the (100) plane, or ZrO ₂ having a monoclinic crystal structure, at least not containing more than the detection limit. Compare. [0127] On the other hand, in the example shown in FIG. 14, also in the θ-2θ spectrum, a peak corresponding to (200) of ZrO ₂ having a tetragonal crystal structure was observed. Therefore, it can be seen that the alignment film 12b has a tetragonal crystal structure and includes ZrO ₂ of (100) alignment. However, in the example shown in FIG. 14, in the θ-2θ spectrum, as a peak other than the peak value of ( ₂₀₀ ) corresponding to ZrO having a tetragonal crystal structure, a crystal corresponding to a tetragonal crystal was observed. The peak of (111) of ZrO ₂ having a structure corresponds to the peak of (111) of ZrO ₂ having a monoclinic crystal structure. Therefore, it can be seen that the alignment film 12b contains a tetragonal crystal structure and a (111) orientation to some extent, although the content ratio is smaller than that of ZrO ₂ having a tetragonal crystal structure and a (100) orientation. ZrO ₂ , and ZrO ₂ having a monoclinic crystal structure and a (111) orientation. [0129] As described above, the film structures of Examples 1 to 60 were film structures formed by changing the thickness of the zirconium film, the substrate temperature when the zirconium film was formed, and the substrate temperature when the ZrO ₂ film was formed, respectively. The film structures of Examples 1 to 60 were classified according to the peak observed in the measured θ-2θ spectrum, the thickness of the zirconium film, the substrate temperature when the zirconium film was formed, and the substrate temperature when the ZrO ₂ film was formed and organize. 15 to 17 are tables showing the peaks observed in the θ-2θ spectrum of Examples 1 to 60, classified and sorted by the thickness of the zirconium film and the substrate temperature when the zirconium film was formed. FIGS. 15 to 17 show the cases where the substrate temperature at the time of forming the ZrO ₂ film is any of 500°C, 550°C, and 600°C, respectively. 15 to 17 correspond to the thicknesses of Zr films that are different from each other, and each row of each of FIGS. 15 to 17 corresponds to the substrate temperatures when forming different Zr films. First, as shown in FIG. ₁₅ , when the substrate temperature when forming the ZrO film is 500° C., the thickness of the zirconium film is 20 nm or less, and the substrate temperature when forming the zirconium film is 600 to 750° C. , a peak of (100) oriented ZrO ₂ was observed (represented as ZrO ₂ (200) in FIG. 15 ). On the other hand, although not shown in FIG. 15 , when the substrate temperature when forming the ZrO ₂ film is 500° C., and when the thickness of the zirconium film exceeds 20 nm, the substrate temperature when forming the zirconium film is less than 600° C. In this case, or when the substrate temperature at the time of forming the zirconium film was higher than 750° C., the peak of ZrO ₂ in the (100) orientation was not observed. In addition, as shown in FIG. ₁₆ , when the substrate temperature when forming the ZrO film is 550°C, the thickness of the zirconium film is 20 nm or less, and the substrate temperature when forming the zirconium film is 600-750°C. , a peak of (100) oriented ZrO ₂ (represented as ZrO ₂ (200) in FIG. 16 ) was observed. On the other hand, although the illustration is omitted in FIG. 16, when the substrate temperature when the ZrO ₂ film is formed is 550°C, and when the thickness of the zirconium film exceeds 20 nm, the substrate temperature when the zirconium film is formed is less than 600°C In this case, or when the substrate temperature at the time of forming the zirconium film was higher than 750° C., the peak of ZrO ₂ in the (100) orientation was not observed. In addition, as shown in FIG. 17 , in the case where the substrate temperature when forming the ZrO film is 600° C., the thickness of the zirconium film is ₂₀ nm or less, and the substrate temperature when forming the zirconium film is 600-750° C. , the peak of (100) oriented ZrO ₂ (represented as ZrO ₂ (200) in FIG. 17 ) was observed. On the other hand, although illustration is omitted in FIG. 17 , when the substrate temperature at the time of forming the ZrO ₂ film is 600° C., and when the thickness of the zirconium film exceeds 20 nm, the substrate temperature at the time of forming the zirconium film is less than 600° C. In this case, or when the substrate temperature at the time of forming the zirconium film was higher than 750° C., the peak of ZrO ₂ in the (100) orientation was not observed. 15 to 17 are omitted, but as examples other than Examples 1 to 60 shown in FIGS. 15 to 17, other conditions are set exactly the same, and ZrO having a thickness of ₅ nm or 20 nm is formed. In the case of the film, completely the same results as in the case of forming a ZrO ₂ film having a thickness of 10 nm were obtained. From the above results, at least the zirconium-containing film 12a having a thickness of 20 nm or less is formed at a temperature of 600 to 750° C., and a zirconium oxide-containing alignment film having a thickness of 5 to 20 nm is formed at a temperature of 500 to 600° C. In the case of 12b, a (100)-aligned ZrO ₂ peak was observed. In such a case, the alignment film 12b has a tetragonal crystal structure and contains more (100) oriented zirconia. In addition, as shown by hatching in FIG. 15 , when the substrate temperature when forming the ZrO film is 500° C., the thickness of the zirconium film is ₅ to 10 nm, and the substrate temperature when forming the zirconium film is At 650 to 700°C, no peaks other than the peaks of (100) oriented ZrO ₂ were observed. On the other hand, when the substrate temperature when forming the ZrO ₂ film is 500°C, when the thickness of the zirconium film is less than 5 nm, when the thickness of the zirconium film is more than 10 nm, the substrate temperature when forming the zirconium film is not Peaks other than ZrO ₂ (100) were observed when the temperature exceeded 650°C, or when the substrate temperature at the time of forming the zirconium film exceeded 700°C. The observed peaks are, for example, the peak of (111)-aligned ZrO ₂ (represented as ZrO ₂ (111) in FIG. 15 ) and the peak of (111)-aligned Zr ₃ O (represented as Zr ₃ O (111) in FIG. 15 . )) and (101)-aligned peaks of Zr ₃ O (represented as Zr ₃ O(101) in FIG. 15 ). [0136] In addition, the above results in the case where the substrate temperature at the time of forming the ZrO ₂ film is 500° C. are shown in the column of “crystallinity of the ZrO ₂ film” in Table 2 as follows. That is, when the thickness of the zirconium film is 5 to 10 nm, and the substrate temperature at the time of forming the zirconium film is 650 to 700° C. (Examples 7 to 9 and 12 to 14), the evaluation results of crystallinity are higher than that of a single coil. Excellent double circle representation. On the other hand, in the other cases (Examples 1 to 6, 10, 11, and 15 to 20), the evaluation results of crystallinity are shown as single circles. In addition, as shown by hatching in FIG. ₁₆ , when the substrate temperature when the ZrO film is formed is 550° C., the thickness of the zirconium film is 5 to 10 nm, and the substrate temperature when the zirconium film is formed is At 650 to 700°C, no peaks other than the peaks of (100) oriented ZrO ₂ were observed. On the other hand, when the substrate temperature when forming the ZrO ₂ film is 550°C, when the thickness of the zirconium film is less than 5 nm, when the thickness of the zirconium film is more than 10 nm, the substrate temperature when forming the zirconium film is not Peaks other than ZrO ₂ (100) were observed when the temperature exceeded 650°C, or when the substrate temperature at the time of forming the zirconium film exceeded 700°C. The observed peaks are, for example, the peak of (111)-aligned ZrO ₂ (represented as ZrO ₂ (111) in FIG. 16 ) and the peak of (111)-aligned Zr ₃ O (represented as Zr ₃ O (111) in FIG. 16 . )) and (101) oriented peaks of Zr ₃ O (represented as Zr ₃ O(101) in FIG. 16 ). [0138] In addition, the above-mentioned results in the case where the substrate temperature at the time of forming the ZrO ₂ film was 550° C. are shown in the column of “crystallinity of the ZrO ₂ film” in Table 3 as follows. That is, when the thickness of the zirconium film is 5 to 10 nm, and the substrate temperature at the time of forming the zirconium film is 650 to 700° C. (Examples 27 to 29, 32 to 34), the crystallinity is evaluated as being higher than that of a single coil. Excellent double circle representation. On the other hand, in other cases (Examples 21 to 26, 30, 31, and 35 to 40), the evaluation results of crystallinity are shown as single circles. In addition, as shown by hatching in FIG. ₁₇ , when the substrate temperature when the ZrO film is formed is 600° C., the thickness of the zirconium film is 5 to 10 nm, and the substrate temperature when the zirconium film is formed is At 650 to 700°C, no peaks other than the peaks of (100) oriented ZrO ₂ were observed. On the other hand, when the substrate temperature when forming the ZrO ₂ film is 600°C, when the thickness of the zirconium film is less than 5 nm, when the thickness of the zirconium film is more than 10 nm, the substrate temperature when forming the zirconium film is less than 5 nm. Peaks other than ZrO ₂ (100) were observed when the temperature exceeded 650°C, or when the substrate temperature at the time of forming the zirconium film exceeded 700°C. The observed peaks are, for example, the peak of (111)-aligned ZrO ₂ (represented as ZrO ₂ (111) in FIG. 17 ) and the peak of (111)-aligned Zr ₃ O (represented as Zr ₃ O (111) in FIG. 17 . )) and (101) oriented peaks of Zr ₃ O (represented as Zr ₃ O(101) in FIG. 17 ). [0140] In addition, the above results in the case where the substrate temperature at the time of forming the ZrO ₂ film is 600° C. are shown in the column of “crystallinity of the ZrO ₂ film” in Table 4 as follows. That is, when the thickness of the zirconium film is 5 to 10 nm, and the substrate temperature at the time of forming the zirconium film is 650 to 700° C. (Examples 47 to 49, 52 to 54), the evaluation results of crystallinity are higher than that of a single coil. Excellent double circle representation. On the other hand, in other cases (Examples 41 to 46, 50, 51, and 55 to 60), the evaluation results of crystallinity are shown as single circles. 15 to 17 , the peak intensity described as “ZrO ₂ (200) is weak” means less than 5.0×10 ³ cps, and those other than this are described as “ZrO ₂ (200)” ” is 1/2 of the peak intensity. 15 to 17 are omitted, but as examples other than Examples 1 to 60, when a ZrO ₂ film having a thickness of 8 nm or 12 nm is formed, it is also possible to obtain and form a ZrO ₂ film having a thickness of 10 nm. The same results were obtained in the case of membranes. From the above results, it is better to form the zirconium-containing film 12a having a thickness of 5 to 10 nm at a temperature of 650 to 700°C, and to form a zirconium oxide-containing film 12a having a thickness of 8 to 12 nm at a temperature of 500 to 600°C. Alignment film 12b. In the case of such conditions, the alignment film 12b may have a tetragonal crystal structure, and may contain more (100) oriented zirconia. [0144] Zirconium (Zr) is more easily oxidized and ionized than silicon (Si). Therefore, by forming the zirconium-containing film 12a with a thickness of 5 to 10 nm at a temperature of 650 to 700°C, and by forming the zirconium-containing alignment film 12b with a thickness of 8 to 12 nm at a temperature of 500 to 600°C, the silicon dioxide The natural oxide film (SiO ₂ ) existing on the upper surface 11 a of the substrate 11 , which is the substrate, is removed more completely. Therefore, the alignment film 12b containing zirconium oxide (Zr) can be directly epitaxially grown on the upper surface 11a of the substrate 11 . [0145] Furthermore, in Examples 1 to 60, when the alignment film 12b containing ZrO ₂ was formed, the zirconium contained in the film 12a was oxidized, and the film 12a was destroyed to become the alignment film 12b. Therefore, the alignment film 12 b is directly formed on the substrate 11 , and the alignment film 12 including only the directly formed alignment film 12 b is formed on the substrate 11 . [0146] Next, as shown in FIG. 10, on the alignment film 12, as the conductive film 13, a platinum (Pt) film was formed by a sputtering method. The conditions at this time are shown as follows. Apparatus: DC sputtering apparatus Pressure: 3.20×10 ^-2 Pa Evaporation source: Pt Electric power: 100W Thickness: 100nm Film-forming speed: 0.14nm/s Ar flow rate: _16sccm Substrate temperature: 400°C In the θ-2θ spectrum, in addition to the peak of ZrO ₂ (200), when the peaks of ZrO ₂ (111), Zr ₃ O (111) and Zr ₃ O (101) are observed, in the θ-2θ spectrum of the platinum film, In addition to the peak of platinum (200), a peak of platinum (111) was observed. On the other hand, in the θ-2θ spectrum of the ZrO ₂ film, in addition to the peak of ZrO ₂ (200), the peaks of ZrO ₂ (111), Zr ₃ O (111) and Zr ₃ O (101) were not observed , in the θ-2θ spectrum of the platinum film, in addition to the peak of platinum (200), no peak of platinum (111) is observed, and the crystallinity of the conductive film 13 can be improved. [0148] Next, as shown in FIG. 11, on the conductive film 13, as the film 14, an SRO film is formed by a sputtering method. The conditions at this time are shown as follows. Apparatus: RF Magnetron Sputtering Apparatus Power: 300W Gas: Ar Pressure: 1.8Pa Substrate Temperature: 600°C Film Formation Rate: 0.11nm/s Thickness: 20nm The θ-2θ spectrum of the film structure up to the film according to the XRD method. FIG. 18 is a diagram showing an example of the θ-2θ spectrum by the XRD method of the film structure formed up to the SRO film. The horizontal axis of the graph of FIG. 18 shows the angle 2θ, and the vertical axis of the graph of FIG. 18 shows the intensity of the X-ray. 18 illustrates a case where the thickness of the zirconium film is 7 nm, the substrate temperature when the zirconium film is formed is 700°C, and the substrate temperature when the ZrO ₂ film is formed is 550°C. [0151] In the example shown in FIG. 18 , in the θ-2θ spectrum, a peak corresponding to (200) of Pt having a cubic crystal structure was observed. Therefore, it can be seen that the conductive film 13 has a cubic crystal structure and contains Pt with a (100) orientation. [0152] In addition, in the example shown in FIG. 18 , in the θ-2θ spectrum, a peak corresponding to (100) of SRO having a cubic crystal structure was observed. Therefore, it can be seen that the conductive film 13 has a cubic crystal structure and includes SRO of (100) orientation. Next, as shown in FIG. 1, on the conductive film 14, as the piezoelectric film ₁₅ , a layer _{in which} a Pb (Zr _0.52 Ti _{0.48 )} O film (PZT film ₎ is laminated is formed by a coating method Membrane. The conditions at this time are shown as follows. The organometallic compounds of lead, zirconium and titanium are mixed in a manner to become the composition ratio of Pb:Zr:Ti=100+δ:52:48, to the mixed solvent of ethanol and 2-n-butoxy alcohol, so that The raw material solution to be dissolved was adjusted so that the concentration of Pb(Zr _{0 . 52} Ti _{0 . 48} )O ₃ was 0.35 mol/l. The δ here refers to the residual Pb amount that is supplemented by the volatilization of the Pb oxide in the subsequent heat treatment process, and is δ=20 in this embodiment. Next, 20 g of polyrolidone having a K value of 27 to 33 was dissolved in the raw material solution. Next, by dropping 3 ml of the raw material solution in the prepared raw material solution onto the substrate 11 composed of a 6-inch wafer, and rotating at 3000 rpm for 10 seconds, the raw material solution was applied on the substrate 11, and A film containing the precursor is formed. Next, by placing the substrate 11 on a hot plate at a temperature of 200° C. for 30 seconds, and further placing the substrate 11 on a hot plate at a temperature of 450° C. for 30 seconds, the solvent is evaporated and the film is dried. Then, the precursor is oxidized and crystallized by heat treatment at 600 to 700° C. for 60 seconds in an oxygen (O ₂ ) atmosphere of 0.2 MPa to form a piezoelectric film having a thickness of 100 nm. A PZT film having a film thickness of, for example, 500 nm is formed by repeating, for example, the steps from the application of the raw material solution to crystallization five times. [0156] For Examples 1 to 60, the θ-2θ spectrum by the XRD method of the film structure formed up to the PZT film was measured. FIG. 19 is a diagram showing an example of the θ-2θ spectrum by the XRD method of the film structure formed up to the PZT film. The horizontal axis of the graph of FIG. 19 shows the angle 2θ, and the vertical axis of the graph of FIG. 19 shows the intensity of the X-ray. 19 illustrates a case where the thickness of the zirconium film is 7 nm, the substrate temperature when the zirconium film is formed is 700°C, and the substrate temperature when the ZrO ₂ film is formed is 550°C. [0158] In addition, in the example shown in FIG. 19, in the θ-2θ spectrum, peaks corresponding to (001) and (002) of PZT having a tetragonal crystal structure were observed. Therefore, it can be seen that the piezoelectric film 15 has a tetragonal crystal structure and includes PZT with a (001) orientation. In addition, when the PZT film is formed by a coating method, as the substrate temperature, when the substrate temperature is formed at 600 to 700° C., which is a wider temperature range than before, it can be seen that, as in the example shown in FIG. 19, the piezoelectric The film 15 has a tetragonal crystal structure and includes (001) oriented PZT. [0160] In addition, different from Examples 1 to 60, as the piezoelectric film 15, even if the PZT film is formed by the sputtering method instead of the coating method, completely the same results can be obtained. As the piezoelectric film 15, the conditions when the PZT film is formed by the sputtering method are shown below. Device: RF magnetron sputtering device Power: 2500W Gas: Ar/O ₂ Pressure: 0.14Pa Substrate temperature: 425-525°C Film-forming speed: 0.63nm/s In the case of forming by sputtering, and also in the case of forming the substrate temperature at 425 to 525° C., which is a wider temperature range than before, it can be seen that the piezoelectric film 15 has a tetragonal crystal structure as in the example shown in FIG. 19 . , and includes (001) oriented PZT. [0162] The invention accomplished by the present inventor has been specifically described above based on its embodiments, but the present invention is not limited to the aforementioned embodiments, and various changes can be made without departing from the gist of the invention. Within the scope of the idea of the present invention, as long as those skilled in the art (professionals) can think of various modifications and amendments, these modifications and amendments should also be understood as belonging to the scope of the present invention. For example, for each of the above-mentioned embodiments, those skilled in the art make appropriate additions, reductions or design changes of constituent elements, or add, omit or condition changes of steps, as long as the gist of the present invention is possessed. , are included in the scope of the present invention.

[0165] 10‧‧‧Film structure 11‧‧‧Substrate 11a‧‧‧Top surface 12, 12b‧‧‧Orientation film 12a‧‧‧Film 13, 14, 16‧‧‧Conductive film 15‧‧‧piezoelectric film

1 is a cross-sectional view of the membrane structure of the embodiment. 2 is a cross-sectional view of the membrane structure in the case where the membrane structure according to the embodiment has a conductive film as the upper electrode. 3 is a diagram illustrating a state of epitaxial growth of an alignment film included in the film structure of the embodiment. FIG. 4 is a diagram illustrating a state in which the alignment film included in the film structure has not undergone epitaxial growth. 5 is a cross-sectional view of the film structure in the case where the alignment film of the film structure according to the embodiment has a two-layer structure. FIG. 6 is a cross-sectional view in the manufacturing process of the membrane structure of the embodiment. FIG. 7 is a cross-sectional view in the manufacturing process of the membrane structure of the embodiment. FIG. 8 is a cross-sectional view in the manufacturing process of the membrane structure of the embodiment. FIG. 9 is a cross-sectional view in the manufacturing process of the membrane structure of the embodiment. FIG. 10 is a cross-sectional view in the manufacturing process of the membrane structure of the embodiment. Fig. 11 is a cross-sectional view in the manufacturing process of the membrane structure of the embodiment. 12 is a cross-sectional view of a membrane structure according to a modification of the embodiment. FIG. 13 is a diagram showing an example of the θ-2θ spectrum by the XRD method of the film structure formed up to the ZrO ₂ film. FIG. 14 is a diagram showing an example of the θ-2θ spectrum by the XRD method of the film structure formed up to the ZrO ₂ film. FIG. 15 is a table in which peaks observed in the θ-2θ spectrum of Examples 1 to 20 are classified and sorted according to the thickness of the zirconium film and the substrate temperature when the zirconium film is formed. FIG. 16 is a table in which peaks observed in the θ-2θ spectrum of Examples 21 to 40 are classified and sorted according to the thickness of the zirconium film and the substrate temperature when the zirconium film is formed. FIG. 17 is a table in which peaks observed in the θ-2θ spectrum of Examples 41 to 60 are classified and sorted according to the thickness of the zirconium film and the substrate temperature when the zirconium film is formed. FIG. 18 is a diagram showing an example of the θ-2θ spectrum by the XRD method of the film structure formed up to the SRO film. FIG. 19 is a diagram showing an example of the θ-2θ spectrum by the XRD method of the film structure formed up to the PZT film.

10‧‧‧Membrane structure

11‧‧‧Substrate

11a‧‧‧Above

12. 12b‧‧‧Alignment film

13, 14‧‧‧Conductive film

15‧‧‧piezoelectric film

Claims (14)

A method for producing a film structure, which is characterized by comprising: (a) a step of preparing a silicon substrate, (b) a step of forming a first film containing zirconium on the silicon substrate, and (c) after the step (b) , the step of forming an epitaxially grown zirconia-containing second film on the silicon substrate, (d) the step of forming an epitaxially grown platinum-containing first conductive film on the second film, (e) in the aforementioned The step of forming an epitaxially grown piezoelectric film on the first conductive film; in the step (b), the first film having a thickness of 5 to 10 nm is formed at a temperature of 650 to 700°C. The method for producing a film structure according to claim 1, wherein the silicon substrate has a main surface composed of a (100) plane; and in the step (c), epitaxial growth is formed on the main surface. 2. The above-mentioned second film having a cubic crystal structure and containing (100) oriented zirconia; in the above-mentioned (d) step, the above-mentioned second film having a cubic crystal structure and containing (100) oriented platinum is formed 1 Conductive film. The manufacturing method of the membrane structure described in item 1 or 2 of the scope of the patent application method, wherein in the step (b), the first film is formed by vapor deposition; in the step (c), the second film is formed by vapor deposition. The method for producing a film structure according to claim 3, wherein in the step (c), the second film is formed at a temperature of 500 to 600°C. The method for producing a film structure according to claim 4, wherein in the step (c), the second film having a thickness of 8 to 12 nm is formed. The method for producing a film structure according to claim 1 or 2, wherein in the step (e), the piezoelectric film having a tetragonal crystal structure and including (001)-oriented lead zirconate titanate is formed . The method for producing a film structure according to claim 1 or 2, wherein in the step (e), a crystalline structure having a rhombohedral crystal is formed and the pressing of lead zirconate titanate having a (100) orientation is formed. Electric film. The method for producing a film structure according to claim 1 or 2 of the scope of the application, which includes (f) the step of forming a second conductive film on the piezoelectric film. A film structure comprising a silicon substrate, a first film containing zirconium formed on the silicon substrate, a second film containing zirconium oxide epitaxially grown on the first film, A first conductive film containing platinum epitaxially grown on the film, and a piezoelectric film epitaxially grown on the first conductive film; the first film has a thickness of 5-10 nm. The film structure according to claim 9, wherein the silicon substrate has a main surface consisting of a (100) plane, and the second film has a cubic crystal structure and includes a (100) orientation. Zirconia; the first conductive film described above has a cubic crystal structure and contains (100) oriented platinum. The film structure according to claim 9 or 10, wherein the second film system has a thickness of 8 to 12 nm. The film structure according to claim 9 or 10, wherein the piezoelectric film has a tetragonal crystal structure and contains lead zirconate titanate (PZT) in (001) orientation. The film structure according to claim 9 or 10, wherein the piezoelectric film has a rhombohedral crystal structure and includes (100)-oriented lead zirconate titanate. The film structure according to claim 9 or 10, further comprising a second conductive film formed on the piezoelectric film.

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