JP5060356B2 - Manufacturing method of BAW resonance device - Google Patents

Manufacturing method of BAW resonance device Download PDF

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JP5060356B2
JP5060356B2 JP2008076697A JP2008076697A JP5060356B2 JP 5060356 B2 JP5060356 B2 JP 5060356B2 JP 2008076697 A JP2008076697 A JP 2008076697A JP 2008076697 A JP2008076697 A JP 2008076697A JP 5060356 B2 JP5060356 B2 JP 5060356B2
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piezoelectric layer
substrate
layer forming
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surface side
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規裕 山内
朝明 松嶋
健雄 白井
孝明 吉原
嘉城 早崎
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Panasonic Corp
Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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本発明は、圧電層の厚み方向の縦振動モードを利用する共振子を有するＢＡＷ（Bulk Acoustic Wave）共振装置の製造方法に関するものである。   The present invention relates to a method of manufacturing a BAW (Bulk Acoustic Wave) resonance device having a resonator using a longitudinal vibration mode in the thickness direction of a piezoelectric layer.

従来から、２ＧＨｚ以上の高周波帯域で用いる共振装置としてＳＡＷ（Surface Acoustic Wave）共振装置よりもＢＡＷ共振装置が適していることが知られており、近年、ＢＡＷ共振装置をＵＷＢ（Ultra Wide Band）用フィルタに応用する場合に、ＵＷＢ用フィルタに適応できる帯域幅（例えば、３００ＭＨｚ）を確保するために、圧電層の圧電材料として、ＡｌＮに比べて電気機械結合係数（ｋeff）が大きな鉛系圧電材料（例えば、ＰＺＴなど）を採用することが提案されている（例えば、特許文献１参照）。なお、上記特許文献１には、ＢＡＷ共振装置として、ＦＢＡＲ（Film Bulk Acoustic Resonator）およびＳＭＲ（Solidly Mounted Resonator）が記載されている。 Conventionally, it is known that a BAW resonance device is more suitable than a SAW (Surface Acoustic Wave) resonance device as a resonance device used in a high frequency band of 2 GHz or more. In recent years, a BAW resonance device has been used for UWB (Ultra Wide Band). When applying to a filter, in order to secure a bandwidth (for example, 300 MHz) that can be applied to a UWB filter, a lead-based piezoelectric material having a large electromechanical coupling coefficient (k eff ) compared to AlN as a piezoelectric material of the piezoelectric layer. It has been proposed to employ a material (for example, PZT) (for example, see Patent Document 1). In Patent Document 1, FBAR (Film Bulk Acoustic Resonator) and SMR (Solidly Mounted Resonator) are described as BAW resonance devices.

また、ＦＢＡＲと称されるＢＡＷ共振装置としては、上記特許文献１に開示された構造に限らず、例えば、図４（ｆ）に示すように、単結晶ＭｇＯ基板もしくは単結晶ＳＴＯ基板からなる支持基板１’の一表面側に第１の導電性材料（例えば、Ｐｔ，Ｉｒなど）からなる下部電極３１’と鉛系圧電材料（例えば、ＰＺＴなど）からなる圧電層３２’と第２の導電性材料（例えば、Ｐｔ，Ｉｒ，Ａｌ，Ｍｏ，Ｗなど）からなる上部電極３３’とを有する共振子３’を備え、支持基板１’に下部電極３１’を露出させる空洞部１ａ’が貫設された構造のものが知られている。なお、図４（ｆ）に示した構成のＢＡＷ共振装置は、圧電層３２’における下部電極３１’側とは反対側に上部電極３３’と圧電層３２’との接触面積を規定する開孔部４ａ’を有するシリコン酸化膜からなる絶縁層４’が形成されている。   Further, the BAW resonance device called FBAR is not limited to the structure disclosed in the above-mentioned Patent Document 1, and for example, as shown in FIG. 4 (f), a support made of a single crystal MgO substrate or a single crystal STO substrate. On one surface side of the substrate 1 ′, a lower electrode 31 ′ made of a first conductive material (eg, Pt, Ir, etc.), a piezoelectric layer 32 ′ made of a lead-based piezoelectric material (eg, PZT, etc.), and a second conductive material. A cavity 3a having an upper electrode 33 'made of a conductive material (eg, Pt, Ir, Al, Mo, W, etc.) and exposing the lower electrode 31' to the support substrate 1 '. An installed structure is known. Note that the BAW resonator having the configuration shown in FIG. 4F has an opening that defines the contact area between the upper electrode 33 ′ and the piezoelectric layer 32 ′ on the opposite side of the piezoelectric layer 32 ′ from the lower electrode 31 ′ side. An insulating layer 4 ′ made of a silicon oxide film having a portion 4a ′ is formed.

以下、図４（ｆ）に示した構成のＢＡＷ共振装置の製造方法ついて説明する。   Hereinafter, a method of manufacturing the BAW resonator having the configuration shown in FIG.

まず、単結晶ＭｇＯ基板からなる支持基板１’の上記一表面側に上記第１の導電性材料からなる下部電極３１’をスパッタ法やＣＶＤ法などにより形成することによって、図４（ａ）に示す構造を得る。   First, the lower electrode 31 ′ made of the first conductive material is formed on the one surface side of the support substrate 1 ′ made of a single crystal MgO substrate by a sputtering method, a CVD method, or the like, so that FIG. Get the structure shown.

その後、支持基板１’の上記一表面側に鉛系圧電材料（例えば、ＰＺＴ）からなる圧電層３２’をスパッタ法やＣＶＤ法やゾルゲル法などにより形成することによって、図４（ｂ）に示す構造を得る。   Thereafter, a piezoelectric layer 32 ′ made of a lead-based piezoelectric material (for example, PZT) is formed on the one surface side of the support substrate 1 ′ by a sputtering method, a CVD method, a sol-gel method, or the like, as shown in FIG. Get the structure.

次に、フォトリソグラフィ技術およびエッチング技術を利用して圧電層３２’を所定形状にパターニングすることによって、図４（ｃ）に示す構造を得る。   Next, the structure shown in FIG. 4C is obtained by patterning the piezoelectric layer 32 'into a predetermined shape using a photolithography technique and an etching technique.

続いて、支持基板１’の上記一表面側に上述の開孔部４ａ’を有する絶縁層４’を形成することによって、図４（ｄ）に示す構造を得る。ここにおいて、絶縁層４’の形成にあたっては、例えば、支持基板１’の上記一表面側において絶縁層４’の形成予定領域以外の部位を覆うレジスト層を形成してから、スパッタ法やＣＶＤ法などにより支持基板１’の上記一表面側の全面に絶縁層４’を成膜し、その後、レジスト層および当該レジスト層上の絶縁層４’をリフトオフすればよい。   Subsequently, the structure shown in FIG. 4D is obtained by forming the insulating layer 4 ′ having the above-described opening 4 a ′ on the one surface side of the support substrate 1 ′. Here, in forming the insulating layer 4 ′, for example, a resist layer covering a portion other than the region where the insulating layer 4 ′ is to be formed is formed on the one surface side of the support substrate 1 ′, and then a sputtering method or a CVD method is used. For example, an insulating layer 4 ′ may be formed on the entire surface of the one surface side of the support substrate 1 ′, and then the resist layer and the insulating layer 4 ′ on the resist layer may be lifted off.

上述の開孔部４ａ’を有する絶縁層４’を形成した後、支持基板１’の上記一表面側に上部電極３３’を形成することによって、図４（ｅ）に示す構造を得る。上部電極３３’の形成にあたっては、スパッタ法やＥＢ蒸着法やＣＶＤ法などにより上部電極３３’を成膜してから、フォトリソグラフィ技術およびエッチング技術を利用して所定形状にパターニングすればよい。   After forming the insulating layer 4 ′ having the opening 4 a ′, the upper electrode 33 ′ is formed on the one surface side of the support substrate 1 ′, thereby obtaining the structure shown in FIG. In forming the upper electrode 33 ′, the upper electrode 33 ′ may be formed by sputtering, EB vapor deposition, CVD, or the like, and then patterned into a predetermined shape using a photolithography technique and an etching technique.

上述の上部電極３３’を形成した後、フォトリソグラフィ技術およびエッチング技術を利用して支持基板１’に厚み方向に貫通する空洞部１ａ’を形成することによって、図４（ｆ）に示す構造のＢＡＷ共振装置を得ることができる。なお、単結晶ＭｇＯ基板からなる支持基板１’に空洞部１ａ’を形成する際のエッチャントとしては、燐酸などを用いればよい。   After the upper electrode 33 ′ is formed, a cavity 1a ′ penetrating in the thickness direction is formed in the support substrate 1 ′ by using a photolithography technique and an etching technique, whereby the structure shown in FIG. A BAW resonance device can be obtained. Note that phosphoric acid or the like may be used as an etchant for forming the cavity 1a 'in the support substrate 1' made of a single crystal MgO substrate.

ところで、圧電層３２’の材料としてＰＺＴなどの鉛系圧電材料を利用したＢＡＷ共振装置を上述の製造方法で製造する場合には、支持基板１’として当該鉛系圧電材料との格子定数差が単結晶Ｓｉ基板に比べて小さく格子整合性の良い単結晶ＭｇＯ基板や単結晶ＳＴＯ基板を用いることにより、圧電層３２’の結晶性を向上でき機械的品質係数や電気機械結合係数などの向上を図れる。しかしながら、単結晶ＭｇＯ基板や単結晶ＳＴＯ基板は単結晶Ｓｉ基板に比べて非常に高価であり、上記特許文献１に開示されたＢＡＷ共振装置のように支持基板として単結晶Ｓｉ基板を用いる場合に比べて、コストが高くなってしまう。   By the way, when a BAW resonance device using a lead-based piezoelectric material such as PZT as a material of the piezoelectric layer 32 ′ is manufactured by the above-described manufacturing method, a lattice constant difference from the lead-based piezoelectric material as the support substrate 1 ′ is increased. By using a single crystal MgO substrate or a single crystal STO substrate that is smaller than a single crystal Si substrate and has good lattice matching, the crystallinity of the piezoelectric layer 32 'can be improved, and the mechanical quality factor, electromechanical coupling coefficient, etc. can be improved. I can plan. However, the single crystal MgO substrate and the single crystal STO substrate are very expensive as compared with the single crystal Si substrate. When the single crystal Si substrate is used as the support substrate like the BAW resonator disclosed in Patent Document 1 above. Compared with the cost.

これに対して、一対の電極間に圧電層を有するＭＥＭＳデバイスの製造方法として、単結晶ＭｇＯ基板からなる圧電層形成基板の一表面側に鉛系圧電材料（例えば、ＰＺＴなど）からなる圧電層を形成し、続いて、圧電層上に第１の接合用金属層を形成し、その後、圧電層形成基板の上記一表面側の第１の接合用金属層と単結晶Ｓｉ基板からなる支持基板の一表面側に形成した第２の接合用金属層とを接合し、更にその後、圧電層形成基板を透過するレーザ光を圧電層形成基板の他表面側から照射して圧電層形成基板を圧電層から剥離することで圧電層を支持基板の上記一表面側に転写するようにした製造方法が提案されており（例えば、特許文献２）、この製造方法によれば圧電層の結晶性を向上できるとともに、単結晶ＭｇＯ基板の再利用が可能となる。なお、上記特許文献２に記載の製造方法では、第１の接合用金属層と第２の接合用金属層とで上記一対の電極の一方の電極が構成されるので、圧電層を支持基板の上記一表面側に転写した後に、他方の電極を形成すればよい。
特開２００７−２９５０２５号公報 特開２００３−３０９３０３号公報 On the other hand, as a method of manufacturing a MEMS device having a piezoelectric layer between a pair of electrodes, a piezoelectric layer made of a lead-based piezoelectric material (for example, PZT) on one surface side of a piezoelectric layer forming substrate made of a single crystal MgO substrate. Subsequently, a first bonding metal layer is formed on the piezoelectric layer, and then the first bonding metal layer on the one surface side of the piezoelectric layer forming substrate and a single crystal Si substrate are used. The second bonding metal layer formed on one surface side of the piezoelectric layer forming substrate is bonded, and then the laser beam transmitted through the piezoelectric layer forming substrate is irradiated from the other surface side of the piezoelectric layer forming substrate to thereby piezoelectrically apply the piezoelectric layer forming substrate. A manufacturing method has been proposed in which the piezoelectric layer is transferred to the one surface side of the support substrate by peeling from the layer (for example, Patent Document 2). According to this manufacturing method, the crystallinity of the piezoelectric layer is improved. And re-use of single crystal MgO substrate It is possible. In the manufacturing method described in Patent Document 2, since the first bonding metal layer and the second bonding metal layer constitute one electrode of the pair of electrodes, the piezoelectric layer is formed on the support substrate. After the transfer to the one surface side, the other electrode may be formed.
JP 2007-295025 A JP 2003-309303 A

しかしながら、上記特許文献２に記載された製造方法では、圧電層形成基板に形成した圧電層を支持基板側へ転写するために、圧電層形成基板の第１の接合用金属層と支持基板の第２の接合用金属層とを接合する接合工程と、当該接合工程の後でレーザ光を照射して圧電層形成基板を剥離する剥離工程との２つの工程が必要となってしまう。   However, in the manufacturing method described in Patent Document 2, in order to transfer the piezoelectric layer formed on the piezoelectric layer forming substrate to the supporting substrate side, the first bonding metal layer of the piezoelectric layer forming substrate and the first of the supporting substrate are transferred. Two steps, a joining step for joining the two joining metal layers, and a peeling step for peeling the piezoelectric layer forming substrate by irradiating laser light after the joining step are required.

本発明は上記事由に鑑みて為されたものであり、その目的は、圧電層の結晶性を向上できるとともに圧電層形成基板の再利用が可能で且つ製造工程の簡略化を図れるＢＡＷ共振装置の製造方法を提供することにある。   The present invention has been made in view of the above-mentioned reasons, and the object of the present invention is to improve the crystallinity of the piezoelectric layer, to enable reuse of the piezoelectric layer forming substrate, and to simplify the manufacturing process. It is to provide a manufacturing method.

請求項１の発明は、支持基板と、支持基板の一表面側に形成された下部電極、下部電極における支持基板側とは反対側に形成され支持基板とは格子定数差のある圧電材料からなる圧電層、圧電層における下部電極側とは反対側に形成された上部電極を有する共振子とを備えたＢＡＷ共振装置の製造方法であって、圧電層を支持基板に比べて当該圧電層との格子整合性の良い圧電層形成用基板の一表面側に形成する圧電層形成工程と、圧電層形成基板の前記一表面と支持基板の前記一表面側に形成した下部電極との間に圧電層が位置するように支持基板の前記一表面側に圧電層形成基板を配置し、圧電層形成基板を透過するレーザ光を圧電層形成基板の他表面側から照射し圧電層と圧電層形成基板における圧電層側の界面で吸収させて圧電層を支持基板の前記一表面側に転写する転写工程とを備えることを特徴とする。   The invention of claim 1 is composed of a support substrate, a lower electrode formed on one surface side of the support substrate, and a piezoelectric material formed on the opposite side of the lower electrode from the support substrate side and having a lattice constant difference from the support substrate. A method of manufacturing a BAW resonance device comprising a piezoelectric layer and a resonator having an upper electrode formed on the side opposite to the lower electrode side of the piezoelectric layer, wherein the piezoelectric layer is compared with the piezoelectric layer relative to the support substrate. Piezoelectric layer formed between the one surface of the piezoelectric layer forming substrate and the lower electrode formed on the one surface side of the supporting substrate, and the piezoelectric layer forming step formed on the one surface side of the piezoelectric layer forming substrate with good lattice matching The piezoelectric layer forming substrate is disposed on the one surface side of the support substrate so that the substrate is positioned, and laser light that passes through the piezoelectric layer forming substrate is irradiated from the other surface side of the piezoelectric layer forming substrate. The piezoelectric layer is absorbed by the interface on the piezoelectric layer side. Characterized in that it comprises a transfer step of transferring to the one surface side of the lifting board.

この発明によれば、圧電層を支持基板に比べて当該圧電層との格子整合性の良い圧電層形成用基板の一表面側に形成する圧電層形成工程と、圧電層形成基板の前記一表面と支持基板の前記一表面側に形成した下部電極との間に圧電層が位置するように支持基板の前記一表面側に圧電層形成基板を配置し、圧電層形成基板を透過するレーザ光を圧電層形成基板の他表面側から照射し圧電層と圧電層形成基板における圧電層側の界面で吸収させて圧電層を支持基板の前記一表面側に転写する転写工程とを備えるので、圧電層の結晶性を向上できるとともに圧電層形成基板の再利用が可能であり、しかも、圧電層形成基板に形成した圧電層を支持基板側へ転写するための工程はレーザ光を照射して圧電層を転写する転写工程だけでよいから、従来のように接合工程と剥離工程との２つの工程を必要とする場合に比べて製造工程の簡略化を図れる。   According to the present invention, the piezoelectric layer forming step of forming the piezoelectric layer on one surface side of the piezoelectric layer forming substrate having better lattice matching with the piezoelectric layer than the supporting substrate, and the one surface of the piezoelectric layer forming substrate A piezoelectric layer forming substrate is disposed on the one surface side of the supporting substrate so that the piezoelectric layer is positioned between the lower electrode formed on the one surface side of the supporting substrate and laser light transmitted through the piezoelectric layer forming substrate. A transfer step of irradiating from the other surface side of the piezoelectric layer forming substrate and absorbing it at the interface between the piezoelectric layer and the piezoelectric layer side of the piezoelectric layer forming substrate and transferring the piezoelectric layer to the one surface side of the supporting substrate. The crystallinity of the piezoelectric layer can be improved and the piezoelectric layer forming substrate can be reused. In addition, the process for transferring the piezoelectric layer formed on the piezoelectric layer forming substrate to the support substrate side is performed by irradiating the piezoelectric layer with laser light. Since only the transfer process to transfer is necessary, Attained to simplify the manufacturing process as compared with the case that requires two steps of the sea urchin bonding step and separation step.

請求項２の発明は、請求項１の発明において、前記圧電材料が鉛系圧電材料であり、前記圧電層形成基板として、単結晶ＭｇＯ基板もしくは単結晶ＳＴＯ基板を用い、前記支持基板として単結晶Ｓｉ基板を用いることを特徴とする。   The invention of claim 2 is the invention of claim 1, wherein the piezoelectric material is a lead-based piezoelectric material, a single crystal MgO substrate or a single crystal STO substrate is used as the piezoelectric layer forming substrate, and a single crystal is used as the support substrate. A Si substrate is used.

この発明によれば、前記圧電層の結晶性を向上できるとともに前記支持基板の低コスト化を図れる。   According to this invention, the crystallinity of the piezoelectric layer can be improved and the cost of the support substrate can be reduced.

請求項３の発明は、請求項２の発明において、前記圧電層形成工程よりも前に前記圧電層形成基板の前記一表面上にＰＬＴもしくはＰＴＯもしくはＳＲＯからなるシード層を形成するシード層形成工程を備え、前記転写工程では、前記レーザ光を前記圧電層形成基板と前記シード層との界面で吸収させて前記圧電層と前記シード層との積層膜を転写することを特徴とする。   According to a third aspect of the present invention, in the second aspect of the invention, the seed layer forming step of forming a seed layer made of PLT, PTO, or SRO on the one surface of the piezoelectric layer forming substrate before the piezoelectric layer forming step. In the transfer step, the laser beam is absorbed at the interface between the piezoelectric layer forming substrate and the seed layer to transfer the laminated film of the piezoelectric layer and the seed layer.

この発明によれば、前記圧電層形成工程よりも前に前記圧電層形成基板の前記一表面上にＰＬＴもしくはＰＴＯもしくはＳＲＯからなるシード層を形成するシード層形成工程を備えていることにより、前記圧電層の結晶性をより一層向上でき、しかも、前記転写工程では、前記レーザ光を前記圧電層形成基板と前記シード層との界面で吸収させて前記圧電層と前記シード層との積層膜を転写するので、前記圧電層形成基板を再利用することができる。   According to this invention, by providing a seed layer forming step of forming a seed layer made of PLT, PTO or SRO on the one surface of the piezoelectric layer forming substrate before the piezoelectric layer forming step, The crystallinity of the piezoelectric layer can be further improved, and in the transfer step, the laser beam is absorbed at the interface between the piezoelectric layer forming substrate and the seed layer to form a laminated film of the piezoelectric layer and the seed layer. Since the transfer is performed, the piezoelectric layer forming substrate can be reused.

請求項１の発明では、圧電層の結晶性を向上できるとともに圧電層形成基板の再利用が可能で且つ製造工程の簡略化を図れるという効果がある。   According to the first aspect of the invention, the crystallinity of the piezoelectric layer can be improved, the piezoelectric layer forming substrate can be reused, and the manufacturing process can be simplified.

本実施形態におけるＢＡＷ共振装置は、図１（ｆ）に示すように、単結晶Ｓｉ基板からなる支持基板１と、支持基板１の一表面側に形成された下部電極３１、下部電極３１における支持基板１側とは反対側に形成され支持基板１とは格子定数差のある圧電材料（例えば、ＰＺＴなど）からなる圧電層３２、圧電層３２における下部電極３１側とは反対側に形成された上部電極３３を有する共振子３とを備えている。ここにおいて、下部電極３１は、第１の導電性材料（例えば、Ｉｎ，Ｐｔ，Ｉｒなど）により形成され、上部電極３３は、第２の導電性材料（例えば、Ｐｔ，Ｉｒ，Ａｌ，Ｍｏ，Ｗなど）により形成されている。   As shown in FIG. 1 (f), the BAW resonance device according to the present embodiment includes a support substrate 1 made of a single crystal Si substrate, a lower electrode 31 formed on one surface side of the support substrate 1, and support on the lower electrode 31. A piezoelectric layer 32 made of a piezoelectric material (for example, PZT) having a lattice constant difference from the support substrate 1 formed on the opposite side of the substrate 1 side, and formed on the opposite side of the piezoelectric layer 32 to the lower electrode 31 side. And a resonator 3 having an upper electrode 33. Here, the lower electrode 31 is made of a first conductive material (for example, In, Pt, Ir, etc.), and the upper electrode 33 is made of a second conductive material (for example, Pt, Ir, Al, Mo, etc.). W etc.).

また、本実施形態におけるＢＡＷ共振装置は、支持基板１の上記一表面上にシリコン酸化膜からなる絶縁膜２０が形成され、当該絶縁膜２０上に下部電極３１が形成されており、支持基板１には、絶縁膜２０において共振子３の共振領域に重なる部位を露出させる空洞部１ａが貫設されている。要するに、本実施形態におけるＢＡＷ共振装置は、支持基板１に空洞部１ａを設けることにより支持基板１側への弾性波エネルギの伝搬を抑制するようにしたＦＢＡＲを構成している。なお、支持基板１の空洞部１ａは、支持基板１の厚み方向において絶縁膜２０から離れる（つまり、下部電極３１から離れる）につれて徐々に開口面積が大きくなる形状に開孔されている。なお、支持基板１として、絶縁性基板を用いる場合には、絶縁膜２０は設ける必要はない。   In the BAW resonator according to the present embodiment, the insulating film 20 made of a silicon oxide film is formed on the one surface of the supporting substrate 1, and the lower electrode 31 is formed on the insulating film 20. In the insulating film 20, a cavity 1 a that exposes a portion overlapping the resonance region of the resonator 3 is provided. In short, the BAW resonance apparatus in the present embodiment constitutes an FBAR in which propagation of elastic wave energy to the support substrate 1 side is suppressed by providing the support substrate 1 with a cavity 1a. Note that the cavity 1a of the support substrate 1 is formed in a shape in which the opening area gradually increases as the distance from the insulating film 20 increases in the thickness direction of the support substrate 1 (that is, from the lower electrode 31). When an insulating substrate is used as the support substrate 1, the insulating film 20 does not need to be provided.

また、本実施形態におけるＢＡＷ共振装置は、圧電層３２における下部電極３１側とは反対側に上部電極３３と圧電層３２との接触面積を規定する開孔部４ａを有するシリコン酸化膜からなる絶縁層４が形成されている。なお、絶縁層４の材料としては、ＳｉＯ２を採用しているが、ＳｉＯ２に限らず、例えば、Ｓｉ３Ｎ４を採用してもよい。 Further, the BAW resonance device according to the present embodiment is an insulating film made of a silicon oxide film having an opening 4a that defines the contact area between the upper electrode 33 and the piezoelectric layer 32 on the opposite side of the piezoelectric layer 32 from the lower electrode 31 side. Layer 4 is formed. As the material of the insulating layer 4, is adopted to SiO 2, is not limited to SiO 2, for example, it may be adopted Si 3 N 4.

また、本実施形態におけるＢＡＷ共振装置は、圧電層３２の圧電材料として鉛系圧電材料の一種であるＰＺＴを採用しており、支持基板１として、上記一表面が（１００）面の単結晶Ｓｉ基板を用いているが、鉛系圧電材料は、ＰＺＴに限らず、例えば、ＰＺＴ−ＰＭＴや適宜の不純物を添加したＰＺＴなどを採用してもよい。   Further, the BAW resonance device in the present embodiment employs PZT, which is a kind of lead-based piezoelectric material, as the piezoelectric material of the piezoelectric layer 32, and the support substrate 1 is a single crystal Si whose one surface is a (100) plane. Although the substrate is used, the lead-based piezoelectric material is not limited to PZT, and for example, PZT-PMT or PZT to which appropriate impurities are added may be employed.

なお、本実施形態におけるＢＡＷ共振装置では、共振子３の共振周波数を５ＧＨｚに設定してあり、圧電層３２の厚みを６００ｎｍに設定してあるが、これらの数値は一例であって特に限定するものではない。例えば、共振周波数を３ＧＨｚ〜５ＧＨｚの範囲で設計する場合には、圧電層３２の厚みは２００ｎｍ〜６００ｎｍの範囲で適宜設定すればよい。   In the BAW resonator according to the present embodiment, the resonance frequency of the resonator 3 is set to 5 GHz, and the thickness of the piezoelectric layer 32 is set to 600 nm. However, these numerical values are only examples and are particularly limited. It is not a thing. For example, when designing the resonance frequency in the range of 3 GHz to 5 GHz, the thickness of the piezoelectric layer 32 may be appropriately set in the range of 200 nm to 600 nm.

以下、本実施形態のＢＡＷ共振装置の製造方法について図１を参照しながら説明する。   Hereinafter, a method for manufacturing the BAW resonator according to the present embodiment will be described with reference to FIG.

まず、圧電材料（例えば、ＰＺＴなど）からなる圧電層３２を単結晶Ｓｉ基板からなる支持基板１に比べて当該圧電層３２との格子定数差が小さく格子整合性の良い単結晶ＭｇＯ基板からなる圧電層形成用基板１０（図１（ａ）参照）の一表面側（図１（ａ）における下面側）に形成する圧電層形成工程を行い、その後、図１（ｂ）に示すように圧電層形成基板１０の上記一表面側の圧電層３２と支持基板１の上記一表面側の絶縁膜２０上に形成した所定膜厚（例えば、１００ｎｍ）のＩｎ膜からなる下部電極３１とを対向させてから、図１（ｃ）に示すように圧電層形成基板１０の上記一表面と支持基板１の上記一表面側に形成した下部電極３１との間に圧電層３２が位置するように支持基板１の上記一表面側に圧電層形成基板を配置し、圧電層形成基板１０を透過するレーザ光を圧電層形成基板１０の他表面側（図１（ｂ）における上面側）から照射し圧電層３２と圧電層形成基板１０における圧電層３２側の界面（ここでは、圧電層形成基板１０と圧電層３２との界面）で吸収させて圧電層３２を支持基板１の上記一表面側に転写し圧電層形成基板１０を支持基板１から離す転写工程を行うことによって、図１（ｃ）に示す構造を得る。なお、圧電層形成工程において用いる圧電層形成基板１０としては、上記一表面が（１００）面で厚さが３００μｍの単結晶ＭｇＯ基板を採用しているが、単結晶ＭｇＯ基板に限らず、上記一表面が（１００）面の単結晶ＳＴＯ基板などを採用してもよい。また、圧電層形成基板１０の厚さは特に限定するものではない。   First, the piezoelectric layer 32 made of a piezoelectric material (for example, PZT) is made of a single crystal MgO substrate having a small lattice constant difference from the piezoelectric layer 32 and having good lattice matching as compared with the support substrate 1 made of a single crystal Si substrate. A piezoelectric layer forming step is performed on one surface side (the lower surface side in FIG. 1A) of the piezoelectric layer forming substrate 10 (see FIG. 1A), and then, as shown in FIG. The piezoelectric layer 32 on the one surface side of the layer forming substrate 10 and the lower electrode 31 made of an In film having a predetermined thickness (for example, 100 nm) formed on the insulating film 20 on the one surface side of the support substrate 1 are opposed to each other. After that, as shown in FIG. 1C, the support substrate is arranged such that the piezoelectric layer 32 is positioned between the one surface of the piezoelectric layer forming substrate 10 and the lower electrode 31 formed on the one surface side of the support substrate 1. 1. A piezoelectric layer forming substrate is disposed on the one surface side of 1, Laser light that passes through the electrode layer forming substrate 10 is irradiated from the other surface side (the upper surface side in FIG. 1B) of the piezoelectric layer forming substrate 10, and the interface between the piezoelectric layer 32 and the piezoelectric layer 32 side of the piezoelectric layer forming substrate 10 ( Here, a transfer process is performed in which the piezoelectric layer 32 is absorbed at the interface between the piezoelectric layer forming substrate 10 and the piezoelectric layer 32 to transfer the piezoelectric layer 32 to the one surface side of the supporting substrate 1 and separate the piezoelectric layer forming substrate 10 from the supporting substrate 1. As a result, the structure shown in FIG. As the piezoelectric layer forming substrate 10 used in the piezoelectric layer forming step, a single crystal MgO substrate having a surface of (100) and a thickness of 300 μm is used. However, the piezoelectric layer forming substrate 10 is not limited to the single crystal MgO substrate. A single crystal STO substrate having one (100) surface may be employed. Further, the thickness of the piezoelectric layer forming substrate 10 is not particularly limited.

上述の圧電層形成工程では、圧電層３２をスパッタ法やＣＶＤ法やゾルゲル法などにより形成する。また、支持基板１の上記一表面側の下部電極３１は、スパッタ法やＣＶＤ法などにより形成すればよい。また、上述の転写工程では、レーザ光を照射する領域を制御して圧電層３２の一部を転写することで、別途に圧電層３２をパターニングする工程を不要としているが、圧電層３２の全部を転写するようにしてもよい。また、転写工程におけるレーザ光の光源としては、例えば、波長が２４８ｎｍのＫｒＦエキシマレーザを用いればよく、圧電層形成基板１０が単結晶ＭｇＯ基板であり、圧電層３２の圧電材料がＰＺＴである場合には、当該ＫｒＦエキシマレーザの出力密度は０．１ｍＪ／ｍｍ２〜１．８ｍＪ／ｍｍ２の範囲で設定することが望ましい。ここで、出力密度が０．１ｍＪ／ｍｍ２未満であると、圧電層３２を転写できないことがあり、１．８ｍＪ／ｍｍ２よりも大きいと圧電層形成基板１０が割れて圧電層形成基板１０の破片が支持基板１側の圧電層３２側に付着してしまうことがある。なお、転写工程において剥離した圧電層形成基板１０に残留している圧電層３２については、例えば、適宜のエッチャント（例えば、フッ酸など）により選択的にエッチング除去すればよい。 In the piezoelectric layer forming step described above, the piezoelectric layer 32 is formed by a sputtering method, a CVD method, a sol-gel method, or the like. Further, the lower electrode 31 on the one surface side of the support substrate 1 may be formed by sputtering, CVD, or the like. Further, in the above-described transfer process, a part of the piezoelectric layer 32 is transferred by controlling the region irradiated with the laser light, so that a separate patterning process for the piezoelectric layer 32 is not necessary. May be transferred. Further, as a laser light source in the transfer process, for example, a KrF excimer laser having a wavelength of 248 nm may be used, and the piezoelectric layer forming substrate 10 is a single crystal MgO substrate, and the piezoelectric material of the piezoelectric layer 32 is PZT. For this, the output density of the KrF excimer laser is preferably set in the range of 0.1 mJ / mm 2 to 1.8 mJ / mm 2 . Here, if the output density is less than 0.1 mJ / mm 2 , the piezoelectric layer 32 may not be transferred. If the output density is greater than 1.8 mJ / mm 2 , the piezoelectric layer forming substrate 10 is cracked and the piezoelectric layer forming substrate 10 is broken. May adhere to the piezoelectric layer 32 side on the support substrate 1 side. Note that the piezoelectric layer 32 remaining on the piezoelectric layer forming substrate 10 peeled off in the transfer process may be selectively etched away with an appropriate etchant (for example, hydrofluoric acid, for example).

上述の転写工程の後、支持基板１の上記一表面側に上述の開孔部４ａを有する絶縁層４を形成する絶縁層形成工程を行うことによって、図１（ｄ）に示す構造を得る。ここにおいて、絶縁層形成工程では、例えば、支持基板１の上記一表面側において絶縁層４の形成予定領域以外の部位を覆うレジスト層を形成してから、スパッタ法やＣＶＤ法などにより支持基板１の上記一表面側の全面に絶縁層４を成膜し、その後、レジスト層および当該レジスト層上の絶縁層４をリフトオフすればよい。   After the above-described transfer step, the structure shown in FIG. 1D is obtained by performing the insulating layer forming step of forming the insulating layer 4 having the above-described opening 4a on the one surface side of the support substrate 1. Here, in the insulating layer forming step, for example, after forming a resist layer covering a portion other than the region where the insulating layer 4 is to be formed on the one surface side of the supporting substrate 1, the supporting substrate 1 is formed by sputtering or CVD. The insulating layer 4 may be formed on the entire surface on the one surface side, and then the resist layer and the insulating layer 4 on the resist layer may be lifted off.

上述の絶縁層形成工程の後、支持基板１の上記一表面側に上部電極３３を形成する上部電極形成工程を行うことによって、図１（ｅ）に示す構造を得る。上部電極形成工程では、スパッタ法やＥＢ蒸着法やＣＶＤ法などにより上部電極３３を成膜してから、フォトリソグラフィ技術およびエッチング技術を利用して所定形状にパターニングすればよい。   After the above-described insulating layer forming step, the upper electrode forming step of forming the upper electrode 33 on the one surface side of the support substrate 1 is performed, thereby obtaining the structure shown in FIG. In the upper electrode formation step, the upper electrode 33 may be formed by sputtering, EB vapor deposition, CVD, or the like, and then patterned into a predetermined shape using a photolithography technique and an etching technique.

上述の上部電極形成工程の後、フォトリソグラフィ技術およびエッチング技術を利用して支持基板１に厚み方向に貫通する空洞部１ａを形成する空洞部形成工程を行うことによって、図１（ｆ）に示す構造のＢＡＷ共振装置を得ることができる。なお、空洞部形成工程において単結晶ＭｇＯ基板からなる支持基板１に空洞部１ａを形成する際のエッチャントとしては、燐酸などを用いればよい。   After the above-described upper electrode formation step, a cavity portion forming step is performed in which a cavity portion 1a penetrating in the thickness direction is formed in the support substrate 1 by using a photolithography technique and an etching technique, as shown in FIG. A BAW resonance device having a structure can be obtained. Note that phosphoric acid or the like may be used as an etchant when forming the cavity 1a in the support substrate 1 made of a single crystal MgO substrate in the cavity formation process.

なお、上述のＢＡＷ共振装置の製造にあたっては、上述の支持基板１および圧電層形成基板１０それぞれウェハ状のものを用いてウェハレベルで多数のＢＡＷ共振装置を形成した後、ダイシング工程で個々のＢＡＷ共振装置に分割すればよい。   In the manufacture of the above-described BAW resonance device, a large number of BAW resonance devices are formed at the wafer level using the support substrate 1 and the piezoelectric layer-forming substrate 10 described above, respectively. What is necessary is just to divide | segment into a resonance apparatus.

以上説明した本実施形態のＢＡＷ共振装置の製造方法によれば、圧電層３２を支持基板１に比べて当該圧電層３２との格子整合性の良い圧電層形成用基板１０の上記一表面側に形成する圧電層形成工程と、圧電層形成基板１０の上記一表面と支持基板１の上記一表面側に形成した下部電極３１との間に圧電層３２が位置するように支持基板１の上記一表面側に圧電層形成基板１０を配置し、圧電層形成基板１０を透過するレーザ光を圧電層形成基板１０の上記他表面側から照射し圧電層３２と圧電層形成基板１０における圧電層３２側の界面で吸収させて圧電層３２を支持基板１の上記一表面側に転写する転写工程とを備えるので、圧電層３２の結晶性を向上でき高品質の圧電層３２を得ることができるとともに圧電層形成基板１０の再利用が可能であり、しかも、圧電層形成基板１０に形成した圧電層３２を支持基板１側へ転写するための工程はレーザ光を照射して圧電層３２を転写する転写工程だけでよいから、従来のように接合工程と剥離工程との２つの工程を必要とする場合に比べて製造工程の簡略化を図れる。   According to the method for manufacturing the BAW resonance device of the present embodiment described above, the piezoelectric layer 32 is placed on the one surface side of the piezoelectric layer forming substrate 10 having better lattice matching with the piezoelectric layer 32 than the support substrate 1. The piezoelectric layer forming step to be formed, and the piezoelectric layer 32 is positioned between the one surface of the piezoelectric layer forming substrate 10 and the lower electrode 31 formed on the one surface side of the supporting substrate 1. The piezoelectric layer forming substrate 10 is disposed on the front surface side, and laser light transmitted through the piezoelectric layer forming substrate 10 is irradiated from the other surface side of the piezoelectric layer forming substrate 10 to the piezoelectric layer 32 and the piezoelectric layer 32 side of the piezoelectric layer forming substrate 10. And the transfer step of transferring the piezoelectric layer 32 to the one surface side of the support substrate 1 by absorbing the piezoelectric layer 32, so that the crystallinity of the piezoelectric layer 32 can be improved and a high-quality piezoelectric layer 32 can be obtained. Reuse of layered substrate 10 In addition, the process for transferring the piezoelectric layer 32 formed on the piezoelectric layer forming substrate 10 to the support substrate 1 side is only a transfer process for transferring the piezoelectric layer 32 by irradiating the laser beam. As described above, the manufacturing process can be simplified as compared with the case where two processes of the joining process and the peeling process are required.

また、本実施形態のＢＡＷ共振装置の製造方法では、圧電層３２の圧電材料が鉛系圧電材料であり、圧電層形成基板１０として、単結晶ＭｇＯ基板もしくは単結晶ＳＴＯ基板を用い、支持基板１として単結晶Ｓｉ基板を用いるので、圧電層３２の結晶性を向上できるとともに支持基板１の低コスト化を図れる。   Further, in the method of manufacturing the BAW resonator according to this embodiment, the piezoelectric material of the piezoelectric layer 32 is a lead-based piezoelectric material, and a single crystal MgO substrate or a single crystal STO substrate is used as the piezoelectric layer forming substrate 10. Therefore, the crystallinity of the piezoelectric layer 32 can be improved and the cost of the support substrate 1 can be reduced.

ところで、圧電層３２の圧電材料は、鉛系圧電材料に限らず、例えば、鉛フリーのＫＮＮ（ニオブ酸カリウムナトリウム）や、ＫＮ、ＮＮ、ＫＮＮに不純物（例えば、Ｌｉ，Ｎｂ，Ｔａ，Ｓｂ，Ｃｕなど）を添加したものでもよい。また、上述のＢＡＷ共振装置の製造方法において、圧電層形成工程よりも前に圧電層形成基板１０の上記一表面上に、圧電層３２の結晶配向を制御するためのＰＬＴもしくはＰＴＯもしくはＳＲＯからなるシード層を形成するシード層形成工程を設け、転写工程では、レーザ光を圧電層形成基板１０とシード層との界面で吸収させて圧電層３２とシード層との積層膜を転写するようにしてもよく、シード層形成工程を設けることにより、圧電層３２の結晶性をより一層向上でき、しかも、転写工程では、レーザ光を圧電層形成基板１０とシード層との界面で吸収させて圧電層３２とシード層との積層膜を転写するので、圧電層形成基板１０を再利用することができる。   By the way, the piezoelectric material of the piezoelectric layer 32 is not limited to the lead-based piezoelectric material. For example, lead-free KNN (potassium sodium niobate), KN, NN, and KNN have impurities (for example, Li, Nb, Ta, Sb, Cu or the like) may be added. Further, in the above-described method for manufacturing a BAW resonance device, PLT, PTO, or SRO for controlling the crystal orientation of the piezoelectric layer 32 is formed on the one surface of the piezoelectric layer forming substrate 10 before the piezoelectric layer forming step. A seed layer forming step for forming a seed layer is provided, and in the transfer step, laser light is absorbed at the interface between the piezoelectric layer forming substrate 10 and the seed layer to transfer the laminated film of the piezoelectric layer 32 and the seed layer. In addition, by providing the seed layer forming step, the crystallinity of the piezoelectric layer 32 can be further improved, and in the transfer step, the laser light is absorbed at the interface between the piezoelectric layer forming substrate 10 and the seed layer to thereby reduce the piezoelectric layer. Since the laminated film of 32 and the seed layer is transferred, the piezoelectric layer forming substrate 10 can be reused.

下記表１に圧電層３２、シード層、下部電極３１、基板（支持基板１、圧電層形成基板１０）それぞれの材料の格子定数などを示す。   Table 1 below shows the lattice constants and the like of the materials of the piezoelectric layer 32, the seed layer, the lower electrode 31, and the substrate (support substrate 1, piezoelectric layer forming substrate 10).

Figure 0005060356
Figure 0005060356

なお、表１における「ap」は基板の一表面に平行な方向（基板材料のａ軸方向に平行な方向）における格子間隔であり、成膜時の表面を（１００）面とすることが好ましい正方晶系および立方晶系では、「a」と同じである。また、「cp」は基板の一表面に直交する方向（基板材料のｃ軸方向に平行な方向）の格子間隔であり、成膜時の表面を（１００）面とすることが好ましい正方晶系および立方晶系では、「c」と同じである。また、斜方晶系のＳＲＯについては、成膜時の表面を（１０１）面とすることが好ましいが、ＳＲＯは、図２（ａ）に示す結晶構造を有しており、（１０１）面が図２（ｂ）に示すような二次元格子となるので、「ap」を隣り合うＳｒ元素の格子点間の間隔ではなく、隣り合うＲｕ元素とＯ元素との擬似格子点間の間隔として記載してあり、「cp」についても同様の間隔を記載してある。また、ＫＮＮ、ＫＮ、ＮＮそれぞれの「ap」，「cp」については、刊行物１〔Takehisa SAITO,et al，「Pulsed Laser Deposition of High-Quality (K,Na)NbO3Thin Films on SrTiO3 Substrate Using High-Density Ceramic Targets」，Japanese Journal of Applied Physics,Vol.43,No.9B,2004,pp.6627-6631〕において「Table II. Lattiice parameters of (K,Na)NbO3films with a psudo-tetoragonal unit cell」で「a」，「b」として報告されている値を記載してある。また、圧電層形成基板１０の材料は、圧電層３２の材料よりもヤング率が大きい材料を採用することが好ましい。 Note that “a p ” in Table 1 is a lattice interval in a direction parallel to one surface of the substrate (a direction parallel to the a-axis direction of the substrate material), and the surface at the time of film formation is the (100) plane. In the preferred tetragonal system and cubic system, it is the same as “a”. Further, “c p ” is a lattice spacing in a direction orthogonal to one surface of the substrate (a direction parallel to the c-axis direction of the substrate material), and the surface at the time of film formation is preferably a (100) plane. For systems and cubic systems, this is the same as “c”. Further, for orthorhombic SRO, the surface during film formation is preferably the (101) plane, but the SRO has the crystal structure shown in FIG. Becomes a two-dimensional lattice as shown in FIG. 2B, so that “a p ” is not the interval between the lattice points of the adjacent Sr element, but the interval between the pseudo lattice points of the adjacent Ru element and the O element. The same interval is also described for “c p ”. For “a p ” and “c p ” of KNN, KN, and NN, see publication 1 [Takehisa SAITO, et al, “Pulsed Laser Deposition of High-Quality (K, Na) NbO 3 Thin Films on SrTiO 3 Substrate Using High-Density Ceramic Targets ”, Japanese Journal of Applied Physics, Vol. 43, No. 9B, 2004, pp. 6627-6631],“ Table II. Lattiice parameters of (K, Na) NbO 3 films with a The values reported as “a” and “b” in the “psudo-tetoragonal unit cell” are described. Moreover, it is preferable to employ a material having a Young's modulus larger than that of the piezoelectric layer 32 as the material of the piezoelectric layer forming substrate 10.

（実施形態２）
本実施形態におけるＢＡＷ共振装置は、実施形態１にて図１（ｆ）を参照しながら説明した空洞部１ａを支持基板１に設ける代わりに、図３（ｅ）に示すように、単結晶Ｓｉ基板からなる支持基板１と共振子３の下部電極３１との間に、音響ミラー（音響多層膜）２が形成されている点が相違する。要するに、本実施形態におけるＢＡＷ共振装置は、ＳＭＲを構成している。なお、実施形態１と同様の構成要素には同一の符号を付して説明を適宜省略する。 (Embodiment 2)
In the BAW resonator according to this embodiment, instead of providing the support substrate 1 with the cavity 1a described with reference to FIG. 1 (f) in the first embodiment, as shown in FIG. The difference is that an acoustic mirror (acoustic multilayer film) 2 is formed between the support substrate 1 made of a substrate and the lower electrode 31 of the resonator 3. In short, the BAW resonance device in the present embodiment constitutes an SMR. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted suitably.

音響ミラー２は、相対的に音響インピーダンスの低い材料からなる低音響インピーダンス層２１と相対的に音響インピーダンスの高い材料からなる高音響インピーダンス層２２とが交互に積層されており、上述の下部電極３１は、最上層の低音響インピーダンス層２１上に形成されている。なお、低音響インピーダンス層２１および高音響インピーダンス層２２それぞれの膜厚は、圧電層３２の共振周波数の弾性波（バルク弾性波）の波長の４分の１の値に設定すればよい。   The acoustic mirror 2 is formed by alternately laminating a low acoustic impedance layer 21 made of a material having a relatively low acoustic impedance and a high acoustic impedance layer 22 made of a material having a relatively high acoustic impedance. Is formed on the uppermost low acoustic impedance layer 21. The film thickness of each of the low acoustic impedance layer 21 and the high acoustic impedance layer 22 may be set to a value that is a quarter of the wavelength of the elastic wave (bulk elastic wave) at the resonance frequency of the piezoelectric layer 32.

本実施形態では、低音響インピーダンス層２１の材料としてＳｉＯ２、高音響インピーダンス層２２の材料としてＷを採用しているが、これらの材料は特に限定するものではなく、低音響インピーダンス層２１の材料としては、例えば、Ｓｉ，ｐｏｌｙ−Ｓｉ，Ａｌ，ポリマーなどを採用してもよく、高音響インピーダンス層２２の材料としては、例えば、Ａｕ，Ｍｏ，ＡｌＮ，ＺｎＯなどを採用してもよい。 In this embodiment, SiO 2 is used as the material of the low acoustic impedance layer 21 and W is used as the material of the high acoustic impedance layer 22. However, these materials are not particularly limited, and the material of the low acoustic impedance layer 21 is used. For example, Si, poly-Si, Al, polymer, or the like may be used. As the material of the high acoustic impedance layer 22, for example, Au, Mo, AlN, ZnO, or the like may be used.

なお、本実施形態におけるＢＡＷ共振装置では、共振子３の共振周波数を４ＧＨｚに設定してあり、下部電極３１の厚みを１００ｎｍ、圧電層３２の厚みを３００ｎｍ、上部電極３３の厚みを１００ｎｍ、低音響インピーダンス層２１の厚みを４００ｎｍ、高音響インピーダンス層２２の厚みを３５０ｎｍに設定してあるが、これらの数値は一例であって特に限定するものではない。また、共振周波数を３ＧＨｚ〜５ＧＨｚの範囲で設計する場合には、圧電層３２の厚みは２００ｎｍ〜６００ｎｍの範囲で、低音響インピーダンス層２１の厚みは２５０ｎｍ〜５５０ｎｍの範囲で、高音響インピーダンス層２２の厚みは２００ｎｍ〜４５０ｎｍの範囲で、それぞれ適宜設定すればよい。   In the BAW resonance device according to the present embodiment, the resonance frequency of the resonator 3 is set to 4 GHz, the thickness of the lower electrode 31 is 100 nm, the thickness of the piezoelectric layer 32 is 300 nm, the thickness of the upper electrode 33 is 100 nm, and low. Although the thickness of the acoustic impedance layer 21 is set to 400 nm and the thickness of the high acoustic impedance layer 22 is set to 350 nm, these numerical values are merely examples and are not particularly limited. When the resonance frequency is designed in the range of 3 GHz to 5 GHz, the piezoelectric layer 32 has a thickness of 200 nm to 600 nm, the low acoustic impedance layer 21 has a thickness of 250 nm to 550 nm, and the high acoustic impedance layer 22. The thickness of each may be set appropriately in the range of 200 nm to 450 nm.

以下、本実施形態のＢＡＷ共振装置の製造方法について図３を参照しながら説明するが、実施形態１の製造方法と同様の工程については説明を適宜省略する。   Hereinafter, the manufacturing method of the BAW resonator according to the present embodiment will be described with reference to FIG.

まず、圧電材料（例えば、ＰＺＴなど）からなる圧電層３２を単結晶Ｓｉ基板からなる支持基板１に比べて当該圧電層３２との格子定数差が小さく格子整合性の良い単結晶ＭｇＯ基板からなる圧電層形成用基板１０（図３（ａ）参照）の一表面側（図３（ａ）における下面側）に形成する圧電層形成工程を行い、その後、図３（ｂ）に示すように圧電層形成基板１０の上記一表面側の圧電層３２と支持基板１の上記一表面側の音響ミラー２上に形成した所定膜厚（例えば、１００ｎｍ）のＩｎ膜からなる下部電極３１とを対向させてから、図３（ｃ）に示すように圧電層形成基板１０の上記一表面と支持基板１の上記一表面側に形成した下部電極３１との間に圧電層３２が位置するように支持基板１の上記一表面側に圧電層形成基板を配置し、圧電層形成基板１０を透過するレーザ光を圧電層形成基板１０の他表面側（図３（ｂ）における上面側）から照射し圧電層３２と圧電層形成基板１０における圧電層３２側の界面（ここでは、圧電層形成基板１０と圧電層３２との界面）で吸収させて圧電層３２を支持基板１の上記一表面側に転写し圧電層形成基板１０を支持基板１から離す転写工程を行うことによって、図３（ｃ）に示す構造を得る。なお、支持基板１の上記一表面側に音響ミラー２を形成する音響ミラー形成工程は、転写工程よりも前に行えばよく、音響ミラー形成工程では、支持基板１の上記一表面側にＳｉＯ２膜からなる低音響インピーダンス層２１とＷ膜からなる高音響インピーダンス層２２とを例えばスパッタ法やＣＶＤ法などにより交互に成膜することで音響ミラー（音響多層膜）２を形成すればよい。 First, the piezoelectric layer 32 made of a piezoelectric material (for example, PZT) is made of a single crystal MgO substrate having a small lattice constant difference from the piezoelectric layer 32 and having good lattice matching as compared with the support substrate 1 made of a single crystal Si substrate. A piezoelectric layer forming step is performed on one surface side (the lower surface side in FIG. 3A) of the piezoelectric layer forming substrate 10 (see FIG. 3A), and then, as shown in FIG. The piezoelectric layer 32 on the one surface side of the layer forming substrate 10 and the lower electrode 31 made of an In film having a predetermined film thickness (for example, 100 nm) formed on the acoustic mirror 2 on the one surface side of the support substrate 1 are opposed to each other. After that, as shown in FIG. 3C, the support substrate is arranged such that the piezoelectric layer 32 is located between the one surface of the piezoelectric layer forming substrate 10 and the lower electrode 31 formed on the one surface side of the support substrate 1. 1. A piezoelectric layer forming substrate is arranged on the one surface side of 1 Laser light passing through the piezoelectric layer forming substrate 10 is irradiated from the other surface side (the upper surface side in FIG. 3B) of the piezoelectric layer forming substrate 10 and the interface between the piezoelectric layer 32 and the piezoelectric layer 32 side of the piezoelectric layer forming substrate 10 ( Here, a transfer process is performed in which the piezoelectric layer 32 is absorbed at the interface between the piezoelectric layer forming substrate 10 and the piezoelectric layer 32 to transfer the piezoelectric layer 32 to the one surface side of the supporting substrate 1 and separate the piezoelectric layer forming substrate 10 from the supporting substrate 1. As a result, the structure shown in FIG. The acoustic mirror forming step for forming the acoustic mirror 2 on the one surface side of the support substrate 1 may be performed before the transfer step. In the acoustic mirror forming step, SiO 2 is formed on the one surface side of the support substrate 1. The acoustic mirror (acoustic multilayer film) 2 may be formed by alternately forming the low acoustic impedance layer 21 made of a film and the high acoustic impedance layer 22 made of a W film by, for example, sputtering or CVD.

上述の転写工程の後、支持基板１の上記一表面側に上述の開孔部４ａを有する絶縁層４を形成する絶縁層形成工程を行うことによって、図３（ｄ）に示す構造を得る。   After the above-described transfer process, the structure shown in FIG. 3D is obtained by performing an insulating layer forming process for forming the insulating layer 4 having the above-described opening 4a on the one surface side of the support substrate 1.

上述の絶縁層形成工程の後、支持基板１の上記一表面側に上部電極３３を形成する上部電極形成工程を行うことによって、図３（ｅ）に示す構造のＢＡＷ共振装置を得ることができる。   After the above-described insulating layer forming step, the upper electrode forming step of forming the upper electrode 33 on the one surface side of the support substrate 1 is performed, whereby the BAW resonance device having the structure shown in FIG. .

しかして、本実施形態のＢＡＷ共振装置の製造方法によれば、実施形態１と同様、圧電層３２の結晶性を向上でき高品質の圧電層３２を得ることができるとともに圧電層形成基板１０の再利用が可能であり、しかも、圧電層形成基板１０に形成した圧電層３２を支持基板１側へ転写するための工程はレーザ光を照射して圧電層３２を転写する転写工程だけでよいから、従来のように接合工程と剥離工程との２つの工程を必要とする場合に比べて製造工程の簡略化を図れる。   Thus, according to the method of manufacturing the BAW resonator of the present embodiment, the crystallinity of the piezoelectric layer 32 can be improved and a high-quality piezoelectric layer 32 can be obtained as in the first embodiment, and the piezoelectric layer forming substrate 10 can be obtained. In addition, the process for transferring the piezoelectric layer 32 formed on the piezoelectric layer forming substrate 10 to the support substrate 1 side is only a transfer process for transferring the piezoelectric layer 32 by irradiating laser light. Thus, the manufacturing process can be simplified as compared with the conventional case where two processes of the joining process and the peeling process are required.

ところで、上記各実施形態１，２で説明した製造方法において説明した転写工程においては、Ｉｎ膜からなる下部電極３１が接合層を兼ねているが接合層は、少なくとも下部電極３１の一部により構成されていればよい。また、接合層の材料はＩｎに限らず、導電性エポキシ樹脂を採用してもよく、接合性および密着性を向上させることができる。また、転写工程において、圧電層形成基板１０の上記他表面側から圧力を印加するようにすれば、接合性および密着性を向上させることができる。また、支持基板１がフレキシブルな基板であれば、圧電層３２の応力を緩和することができる。   By the way, in the transfer process described in the manufacturing method described in the first and second embodiments, the lower electrode 31 made of an In film also serves as a bonding layer, but the bonding layer is configured by at least a part of the lower electrode 31. It only has to be done. Further, the material of the bonding layer is not limited to In, and a conductive epoxy resin may be adopted, and the bonding property and adhesion can be improved. Further, in the transfer step, if pressure is applied from the other surface side of the piezoelectric layer forming substrate 10, the bondability and adhesion can be improved. Moreover, if the support substrate 1 is a flexible substrate, the stress of the piezoelectric layer 32 can be relieved.

また、上記各実施形態１，２で説明したＢＡＷ共振装置を、３ＧＨｚ以上の高周波帯においてカットオフ特性が急峻で且つ帯域幅の広いフィルタ、例えば、ＵＷＢ用フィルタとして応用する場合には、複数個（例えば、８個）の共振子３を支持基板１の上記一表面側に形成し、これら複数個の共振子３をラダー型フィルタを構成するように接続すれば、ＵＷＢ用フィルタの低コスト化および小型化を図れる。   When the BAW resonator described in the first and second embodiments is applied as a filter having a sharp cutoff characteristic and a wide bandwidth in a high frequency band of 3 GHz or more, for example, a UWB filter, a plurality of BAW resonators are used. If (for example, eight) resonators 3 are formed on the one surface side of the support substrate 1 and the plurality of resonators 3 are connected to form a ladder filter, the cost of the UWB filter can be reduced. And downsizing can be achieved.

実施形態１のＢＡＷ共振装置の製造方法を説明するための主要工程断面図である。FIG. 4 is a main process sectional view for explaining the method for manufacturing the BAW resonator according to the first embodiment. 表１の説明図である。It is explanatory drawing of Table 1. FIG. 実施形態２のＢＡＷ共振装置の製造方法を説明するための主要工程断面図である。FIG. 10 is a main process sectional view for illustrating the method for manufacturing the BAW resonator according to the second embodiment. 従来例を示すＢＡＷ共振装置の製造方法を説明するための主要工程断面図である。It is main process sectional drawing for demonstrating the manufacturing method of the BAW resonance apparatus which shows a prior art example.

符号の説明Explanation of symbols

１ 支持基板
１ａ 空洞部
３ 共振子
４ 絶縁層
１０ 圧電層形成用基板
２０ 絶縁膜
３１ 下部電極
３２ 圧電層
３３ 上部電極 DESCRIPTION OF SYMBOLS 1 Support substrate 1a Cavity part 3 Resonator 4 Insulating layer 10 Substrate for piezoelectric layer formation 20 Insulating film 31 Lower electrode 32 Piezoelectric layer 33 Upper electrode

Claims (3)

支持基板と、支持基板の一表面側に形成された下部電極、下部電極における支持基板側とは反対側に形成され支持基板とは格子定数差のある圧電材料からなる圧電層、圧電層における下部電極側とは反対側に形成された上部電極を有する共振子とを備えたＢＡＷ共振装置の製造方法であって、圧電層を支持基板に比べて当該圧電層との格子整合性の良い圧電層形成用基板の一表面側に形成する圧電層形成工程と、圧電層形成基板の前記一表面と支持基板の前記一表面側に形成した下部電極との間に圧電層が位置するように支持基板の前記一表面側に圧電層形成基板を配置し、圧電層形成基板を透過するレーザ光を圧電層形成基板の他表面側から照射し圧電層と圧電層形成基板における圧電層側の界面で吸収させて圧電層を支持基板の前記一表面側に転写する転写工程とを備えることを特徴とするＢＡＷ共振装置の製造方法。   A support substrate, a lower electrode formed on one surface of the support substrate, a piezoelectric layer made of a piezoelectric material formed on the opposite side of the lower electrode from the support substrate side and having a lattice constant difference from the support substrate, and a lower portion of the piezoelectric layer A method of manufacturing a BAW resonance device including a resonator having an upper electrode formed on the side opposite to an electrode side, wherein the piezoelectric layer has a better lattice matching with the piezoelectric layer than the supporting substrate The piezoelectric substrate is formed on one surface side of the forming substrate, and the supporting substrate is positioned so that the piezoelectric layer is positioned between the one surface of the piezoelectric layer forming substrate and the lower electrode formed on the one surface side of the supporting substrate. A piezoelectric layer forming substrate is disposed on the one surface side of the substrate, and a laser beam transmitted through the piezoelectric layer forming substrate is irradiated from the other surface side of the piezoelectric layer forming substrate and absorbed at the interface between the piezoelectric layer and the piezoelectric layer forming substrate on the piezoelectric layer side. Let the piezoelectric layer on the support substrate Method for manufacturing a BAW resonator, characterized in that it comprises a transfer step of transferring to the side. 前記圧電材料が鉛系圧電材料であり、前記圧電層形成基板として、単結晶ＭｇＯ基板もしくは単結晶ＳＴＯ基板を用い、前記支持基板として単結晶Ｓｉ基板を用いることを特徴とする請求項１記載のＢＡＷ共振装置の製造方法。   The piezoelectric material is a lead-based piezoelectric material, a single crystal MgO substrate or a single crystal STO substrate is used as the piezoelectric layer forming substrate, and a single crystal Si substrate is used as the support substrate. A method of manufacturing a BAW resonance device. 前記圧電層形成工程よりも前に前記圧電層形成基板の前記一表面上にＰＬＴもしくはＰＴＯもしくはＳＲＯからなるシード層を形成するシード層形成工程を備え、前記転写工程では、前記レーザ光を前記圧電層形成基板と前記シード層との界面で吸収させて前記圧電層と前記シード層との積層膜を転写することを特徴とする請求項２記載のＢＡＷ共振装置の製造方法。   A seed layer forming step of forming a seed layer made of PLT, PTO, or SRO on the one surface of the piezoelectric layer forming substrate prior to the piezoelectric layer forming step; 3. The method of manufacturing a BAW resonance device according to claim 2, wherein the laminated film of the piezoelectric layer and the seed layer is transferred by absorption at an interface between the layer forming substrate and the seed layer.
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