JP2006093971A - Peelable lithium tantalate single crystal compound substrate - Google Patents
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- 239000000758 substrate Substances 0.000 title claims abstract description 149
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 title claims abstract description 68
- 239000013078 crystal Substances 0.000 title claims abstract description 66
- 150000001875 compounds Chemical class 0.000 title abstract 3
- 229920005989 resin Polymers 0.000 claims abstract description 9
- 239000011347 resin Substances 0.000 claims abstract description 9
- 239000002131 composite material Substances 0.000 claims description 21
- 239000007767 bonding agent Substances 0.000 claims description 16
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 239000004840 adhesive resin Substances 0.000 claims description 4
- 229920006223 adhesive resin Polymers 0.000 claims description 4
- 239000000853 adhesive Substances 0.000 abstract description 6
- 238000010897 surface acoustic wave method Methods 0.000 description 28
- 238000004519 manufacturing process Methods 0.000 description 10
- 238000000034 method Methods 0.000 description 6
- 238000007517 polishing process Methods 0.000 description 6
- 239000001993 wax Substances 0.000 description 6
- 239000007788 liquid Substances 0.000 description 5
- 230000001070 adhesive effect Effects 0.000 description 4
- 238000000151 deposition Methods 0.000 description 4
- 239000007772 electrode material Substances 0.000 description 4
- 239000010408 film Substances 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 239000010453 quartz Substances 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 235000008331 Pinus X rigitaeda Nutrition 0.000 description 3
- 235000011613 Pinus brutia Nutrition 0.000 description 3
- 241000018646 Pinus brutia Species 0.000 description 3
- 238000004891 communication Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 239000006061 abrasive grain Substances 0.000 description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 230000001413 cellular effect Effects 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910052741 iridium Inorganic materials 0.000 description 2
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 2
- 229910052808 lithium carbonate Inorganic materials 0.000 description 2
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- 239000004820 Pressure-sensitive adhesive Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- 229910001947 lithium oxide Inorganic materials 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
本発明は、携帯電話等に用いられる弾性表面波素子用タンタル酸リチウム単結晶基板に関するものである。 The present invention relates to a lithium tantalate single crystal substrate for a surface acoustic wave device used for a mobile phone or the like.
携帯電話等の高周波通信において周波数選択用の部品として、例えば圧電基板上に弾性表面を励起するための櫛形電極が形成された弾性表面波（Surface Acoustic Wave、ＳＡＷ）素子が用いられる。弾性表面波素子は、タンタル酸リチウム等からなる圧電基板と、それに接合される補助基板とからなる。圧電基板としては、例えば、３６°〜４２°回転Ｙカットのタンタル酸リチウム単結晶基板等が用いられる。圧電基板と補助基板とは、接着剤接合や直接接合によって接合される。（特許文献１〜３参照） A surface acoustic wave (SAW) element in which a comb electrode for exciting an elastic surface is formed on a piezoelectric substrate is used as a frequency selection component in high-frequency communication such as a cellular phone. The surface acoustic wave element includes a piezoelectric substrate made of lithium tantalate and the like, and an auxiliary substrate bonded thereto. As the piezoelectric substrate, for example, a 36 ° to 42 ° rotated Y-cut lithium tantalate single crystal substrate or the like is used. The piezoelectric substrate and the auxiliary substrate are bonded by adhesive bonding or direct bonding. (See Patent Documents 1 to 3)
近年、携帯電話の薄型化に伴い弾性表面波素子も薄型化が進行し、その結果、基板材料であるタンタル酸リチウム単結晶に対しても薄型化の要求が強まっている。
従来、弾性表面波素子として用いられるタンタル酸リチウム単結晶基板の厚さは、３５０〜５００μｍであったが、この薄型化の要求に応えるために、最近では基板の加工方法を改善することで、２００〜２５０μｍ程度まで薄型化が進行している。
In recent years, the surface acoustic wave element has been made thinner as the mobile phone is made thinner, and as a result, the demand for thinning the lithium tantalate single crystal, which is a substrate material, has increased.
Conventionally, the thickness of a lithium tantalate single crystal substrate used as a surface acoustic wave element has been 350 to 500 μm, but in order to meet this demand for thinning, recently, by improving the processing method of the substrate, Thinning is progressing to about 200 to 250 μm.
表面弾性波素子として利用されるタンタル酸リチウム単結晶の厚さは、表面弾性波素子で使われる周波数にもよるが、２０μｍの厚さがあれば表面弾性波素子としての機能は発揮できる。
しかし、タンタル酸リチウム単結晶を単独でそこまで薄膜とすることは、非常に困難である。薄膜の強度を考慮して、例えば４０μｍ程度の厚さにまで加工することは、ラップ工程、研磨工程でワレが生じたり、また、現状の４インチサイズの基板を取り扱う方法がないのが実状である。
また、たとえ４０μｍ程度の厚さをもったタンタル酸リチウム単結晶基板が加工できたとしても、表面弾性波素子を製造するための金属膜蒸着、露光といった工程に流すための治具等が無く、４０μｍ程度の厚さのタンタル酸リチウム単結晶基板は弾性表面波素子の製造には適さないといった問題がある。
The thickness of the lithium tantalate single crystal used as the surface acoustic wave device depends on the frequency used in the surface acoustic wave device, but if it is 20 μm thick, the function as the surface acoustic wave device can be exhibited.
However, it is very difficult to make a lithium tantalate single crystal alone as a thin film. Considering the strength of the thin film, processing to a thickness of about 40 μm, for example, causes cracks in the lapping process and polishing process, and there is no way to handle the current 4-inch size substrate. is there.
Moreover, even if a lithium tantalate single crystal substrate having a thickness of about 40 μm can be processed, there is no jig etc. for flowing through a process such as metal film deposition and exposure for manufacturing a surface acoustic wave device, There is a problem that a lithium tantalate single crystal substrate having a thickness of about 40 μm is not suitable for manufacturing a surface acoustic wave device.
本発明は、上記した問題を解決しようとするものであり、最終的には、特性上の問題が生じないまでの極めて薄いタンタル酸リチウム単結晶基板を提供することを目的とするものであって、剥離することによって直ちに弾性表面波素子として組み上げることができる複合化されたタンタル酸リチウム単結晶基板を提供することを課題とする。 An object of the present invention is to solve the above-described problems, and finally, an object of the present invention is to provide a very thin lithium tantalate single crystal substrate that does not cause a problem in characteristics. An object of the present invention is to provide a composite lithium tantalate single crystal substrate that can be immediately assembled as a surface acoustic wave device by peeling.
上記目的を達成するために、本発明による剥離可能なタンタル酸リチウム単結晶複合基板は、厚さ２０〜１００μｍのタンタル酸リチウム単結晶である第１の基板が第２の基板に剥離可能に接合された剥離可能なタンタル酸リチウム単結晶複合基板であって、前記第１の基板の面方向における線膨張係数の最大値と前記第２の基板の面方向における線膨張係数の最大値の差が３×１０-6／℃以下であることを特徴とする。前記第１の基板となるタンタル酸リチウム単結晶が３６°〜４２°回転Ｙカットであること、前記第１の基板となるタンタル酸リチウム単結晶が３６°〜４２°回転Ｙカットであり、タンタル酸リチウム単結晶複合基板の厚さが２００〜６００μｍであること、また、前記第２の基板が３６°〜４２°回転Ｙカットのタンタル酸リチウム単結晶、面内にＸ軸を含むニオブ酸リチウム、面内にＸ軸を含む水晶、のいずれかであること、さらに、前記第１の基板と前記第２の基板との接合が、真空における変形温度が２００℃以上である接合剤によってなされていること、前記接合剤が、紫外線で硬化する粘着性を持った樹脂であること、さらにまた、前記接合が、両面に紫外線で硬化する粘着性を持った樹脂層を有するテープ材でなされること、がそれぞれ好ましい。 In order to achieve the above object, a peelable lithium tantalate single crystal composite substrate according to the present invention has a first substrate which is a lithium tantalate single crystal having a thickness of 20 to 100 μm and is detachably bonded to a second substrate. A peelable lithium tantalate single crystal composite substrate, wherein a difference between a maximum value of the linear expansion coefficient in the plane direction of the first substrate and a maximum value of the linear expansion coefficient in the plane direction of the second substrate is 3 × 10 −6 / ° C. or less. The lithium tantalate single crystal serving as the first substrate is a 36 ° to 42 ° rotated Y-cut, and the lithium tantalate single crystal serving as the first substrate is a 36 ° to 42 ° rotated Y cut. The lithium oxide single crystal composite substrate has a thickness of 200 to 600 μm, and the second substrate is a 36 ° to 42 ° rotated Y-cut lithium tantalate single crystal, and the surface contains an X axis lithium niobate , And the first substrate and the second substrate are bonded by a bonding agent whose deformation temperature in vacuum is 200 ° C. or higher. The bonding agent is an adhesive resin that is cured by ultraviolet rays, and the bonding is made of a tape material having an adhesive resin layer that is cured by ultraviolet rays on both sides. ,But Each Re preferred.
本発明によれば、第１の基板たるタンタル酸リチウム単結晶基板を第２の基板に剥離可能に接合して複合化して厚さを増すことによって、ラップあるいは研磨工程に流すことが可能となり、また、基板加工工程および弾性表面波素子製造工程での取り扱いも可能となる。特に、第１の基板と第２の基板との線膨張係数の差を３×１０-6／℃以下とする場合には、第１の基板に金属アルミニウムを主体とする電極材料を蒸着する工程では約２００〜２５０℃の温度が加わる、弾性表面波素子製造工程中の電極形成工程に付しても、複合化した基板が剥離するという不具合を抑えることが可能となる。
第１の基板と第２の基板との接合に、真空における変形温度が２００℃以上である接合剤を使用することにより、電極材料となる金属膜を真空中で蒸着する工程で第１の基板と第２の基板とが剥離をするとか、お互いに位置がずれるといった不具合を防ぐことができる。
According to the present invention, the lithium tantalate single crystal substrate, which is the first substrate, is releasably bonded to the second substrate and combined to increase the thickness, thereby allowing the lapping or polishing process to flow. In addition, handling in the substrate processing process and the surface acoustic wave element manufacturing process is also possible. In particular, when the difference in coefficient of linear expansion between the first substrate and the second substrate is 3 × 10 −6 / ° C. or less, an electrode material mainly composed of metallic aluminum is deposited on the first substrate. Then, even if it is subjected to an electrode forming step in the surface acoustic wave element manufacturing process where a temperature of about 200 to 250 ° C. is applied, it is possible to suppress a problem that the combined substrate is peeled off.
By using a bonding agent having a deformation temperature in vacuum of 200 ° C. or higher for bonding the first substrate and the second substrate, the first substrate is formed in a step of depositing a metal film as an electrode material in vacuum. And the second substrate can be prevented from being separated from each other or the positions can be shifted from each other.
また、複合化を剥離可能な接合とすることで、タンタル酸リチウム単結晶基板上に表面弾性波素子のパターンを形成した後で、かつチップにダイシングする前に第１の基板と第２の基板とを剥離して、第２の基板を繰り返し利用することが可能となる。この場合に、接合剤に紫外線で硬化する粘着性を持った樹脂を用いると第１の基板と第２の基板とを弾性表面波素子の素子製造工程に流した後に、紫外線を照射することで粘着材を硬化させ、第１の基板と第２の基板とを剥離でき、その後、第１の基板は例えばダイシングテープに貼り付けてチップに加工し、第２の基板は回収して繰り返し利用することになる。 Further, by making the composite a peelable bond, the first substrate and the second substrate are formed after the surface acoustic wave element pattern is formed on the lithium tantalate single crystal substrate and before dicing into the chip. And the second substrate can be used repeatedly. In this case, if an adhesive resin that is cured by ultraviolet rays is used as the bonding agent, the first substrate and the second substrate are passed through the element manufacturing process of the surface acoustic wave element and then irradiated with ultraviolet rays. The adhesive material can be cured, and the first substrate and the second substrate can be peeled off. Thereafter, the first substrate is attached to, for example, a dicing tape and processed into a chip, and the second substrate is collected and repeatedly used. It will be.
本発明は、タンタル酸リチウム単結晶を第２の基板に剥離可能に接合して見かけ上の厚さを増加させることにより、携帯電話等の高周波通信において周波数選択用の部品としての所望の厚さの薄膜にすることができ、圧電基板上に弾性表面を励起するための櫛形電極を容易に形成させることができるようにしたことを基本とする。
以下に、本発明を詳細に説明する。
本発明に用いるタンタル酸リチウム結晶は、以下のようにして得る。
はじめに、炭酸リチウムと五酸化タンタルとを秤量し、混合し、電気炉で１０００℃以上に加熱することで、多結晶のタンタル酸リチウムを得る。
The present invention provides a desired thickness as a frequency selection component in high-frequency communication such as a cellular phone by increasing the apparent thickness by releasably bonding a lithium tantalate single crystal to a second substrate. Basically, a comb-shaped electrode for exciting the elastic surface can be easily formed on the piezoelectric substrate.
The present invention is described in detail below.
The lithium tantalate crystal used in the present invention is obtained as follows.
First, lithium carbonate and tantalum pentoxide are weighed, mixed, and heated to 1000 ° C. or higher in an electric furnace to obtain polycrystalline lithium tantalate.
得られた多結晶のタンタル酸リチウムを、イリジウム製のルツボに入れ、加熱、溶融後に種結晶を用いて回転引上げて育成する（いわゆるチョクラルスキー法）ことで、例えば直径が４インチのタンタル酸リチウム単結晶粗柱を得る。
この場合に、種結晶として、例えば４２°回転Ｙ方向の種結晶を用いることにより、４２°回転Ｙ方向のタンタル酸リチウム単結晶粗柱が得られる。他の角度の回転Ｙ方向の種結晶、例えば３６°回転Ｙ方向の種結晶を用いることにより、３６°回転Ｙカットのタンタル酸リチウム単結晶基粗柱が得られる。
タンタル酸リチウム単結晶基粗柱は、適宜の太さとすることができる。以下では、公称４インチのタンタル酸リチウム単結晶基粗柱を例に説明する。
The obtained polycrystalline lithium tantalate is placed in an iridium crucible, and heated and melted to grow it by using a seed crystal (so-called Czochralski method), for example, tantalum acid having a diameter of 4 inches. Lithium single crystal rough pillars are obtained.
In this case, for example, by using a seed crystal in the 42 ° rotation Y direction as the seed crystal, a lithium tantalate single crystal coarse column in the 42 ° rotation Y direction can be obtained. By using a seed crystal in the rotation Y direction at another angle, for example, a seed crystal in the 36 ° rotation Y direction, a 36 ° rotation Y-cut lithium tantalate single crystal based rough column can be obtained.
The lithium tantalate single crystal-based rough column can have an appropriate thickness. In the following, a nominal 4-inch lithium tantalate single crystal based rough column will be described as an example.
このようにして得られた４インチのタンタル酸リチウム単結晶粗柱を単分域化処理した後に、例えば、ワイヤソーを用いて、スライスすることで、直径４インチ、厚さ５００μｍのスライス処理がおこなわれた４２°回転Ｙカットのタンタル酸リチウム単結晶基板が得られる。さらに、この単結晶基板をラップ機で処理することで、直径４インチ、厚さ４００μｍの、表面状態が整えられ、ラップされたタンタル酸リチウム単結晶基板が得られる。
表面状態が整えられたタンタル酸リチウム単結晶基板は、バックアップ用の第２の基板に接合される。
第２の基板としては、第１の基板たるタンタル酸リチウム単結晶基板の面方向における線膨張係数との差が小さいものであることが好ましい。具体的には、第１の基板の面方向における線膨張係数の最大値と前記第２の基板の面方向における線膨張係数の最大値の差が３×１０-6／℃以下であることが好ましい。
After the 4-inch lithium tantalate single crystal coarse column obtained in this way is subjected to a single domain treatment, it is sliced by using, for example, a wire saw, thereby performing a slice treatment with a diameter of 4 inches and a thickness of 500 μm. A 42 ° rotated Y-cut lithium tantalate single crystal substrate is obtained. Further, by processing this single crystal substrate with a lapping machine, a surface condition of 4 inches in diameter and 400 μm in thickness is prepared, and a wrapped lithium tantalate single crystal substrate is obtained.
The lithium tantalate single crystal substrate whose surface state is adjusted is bonded to the second substrate for backup.
The second substrate preferably has a small difference from the linear expansion coefficient in the plane direction of the lithium tantalate single crystal substrate which is the first substrate. Specifically, the difference between the maximum value of the linear expansion coefficient in the surface direction of the first substrate and the maximum value of the linear expansion coefficient in the surface direction of the second substrate is 3 × 10 −6 / ° C. or less. preferable.
第１の基板である３６°〜４２°回転Ｙカットのタンタル酸リチウム単結晶基板で面方向の線膨張係数の最大値は、１６．１×１０-6／℃である。第２の基板として、第１の基板と同じものを用いれば、線膨張係数の差がないものとすることができる。
他に、第２の基板と用いられ得る物質の線膨張係数を以下に列挙する。
面内にＸ軸を含む６４°回転Ｙカットのニオブ酸リチウム基板は、Ｘ軸方向の線膨張係数が１５．４×１０-6／℃である。タンタル酸リチウム単結晶基板とニオブ酸リチウム単結晶基板の線膨張係数の最大値を与える方向をほぼそろえることで線膨張係数差による熱応力を小さくできる。
１２８°回転Ｙニオブ酸リチウム基板（面方向における線膨張係数の最大値、つまりＸ軸方向の線膨張係数は１５．４×１０-6／℃）、６４°回転Ｙニオブ酸リチウム基板（Ｘ軸方向の線膨張係数は１５．４×１０-6／℃）、ＳＴカット水晶（面方向における線膨張係数の最大値は１３．４×１０-6／℃）等が挙げられる。石英基板（線膨張係数０．５×１０-6／℃）、アルミナ基板（線膨張係数７．２×１０-6／℃）、シリコン基板（線膨張係数 ４．２×１０-6／℃）等は、方向性がなく、後述するように、本件発明の第２の基板として適当ではない。
The maximum value of the linear expansion coefficient in the plane direction of the first substrate 36 ° to 42 ° rotated Y-cut lithium tantalate single crystal substrate is 16.1 × 10 −6 / ° C. If the same substrate as the first substrate is used as the second substrate, there can be no difference in linear expansion coefficient.
In addition, the linear expansion coefficients of materials that can be used with the second substrate are listed below.
The 64 ° rotated Y-cut lithium niobate substrate including the X axis in the plane has a linear expansion coefficient in the X axis direction of 15.4 × 10 −6 / ° C. The thermal stress due to the difference in linear expansion coefficient can be reduced by aligning the directions of giving the maximum values of the linear expansion coefficients of the lithium tantalate single crystal substrate and the lithium niobate single crystal substrate.
128 ° rotated Y lithium niobate substrate (maximum value of linear expansion coefficient in the plane direction, that is, the linear expansion coefficient in the X axis direction is 15.4 × 10 −6 / ° C.), 64 ° rotated Y lithium niobate substrate (X axis) The linear expansion coefficient in the direction is 15.4 × 10 −6 / ° C., ST-cut quartz (the maximum value of the linear expansion coefficient in the plane direction is 13.4 × 10 −6 / ° C.), and the like. Quartz substrate (linear expansion coefficient 0.5 × 10 −6 / ° C.), alumina substrate (linear expansion coefficient 7.2 × 10 −6 / ° C.), silicon substrate (linear expansion coefficient 4.2 × 10 −6 / ° C.) Etc. have no directivity and are not suitable as the second substrate of the present invention, as will be described later.
第２の基板の厚さは、接合され、加工された第１の基板との合計厚さが２００μｍ以上であることが必要であり、好ましくはこの数値が２００〜６００μｍであることを勘案して、１８０μｍ以上であることが必要である。ただし、厚すぎても、格別の利点が生じず、コスト高に繋がるので、第２の基板の厚さは、好ましくは１８０〜５８０μｍ、より好ましくは２００〜５００μｍである。
第１の基板と第２の基板とを接合する接合剤としては、接合力があり、必要なときに接合を解除できる接合剤が用いられる。この条件を満足する接合剤として、ＵＶ硬化型の粘着剤、松脂からなる液状ワックスが挙げられる。
The thickness of the second substrate is required to be 200 μm or more in total thickness with the bonded and processed first substrate, and preferably this value is 200 to 600 μm. , 180 μm or more is necessary. However, even if it is too thick, there is no particular advantage and the cost is increased. Therefore, the thickness of the second substrate is preferably 180 to 580 μm, more preferably 200 to 500 μm.
As a bonding agent for bonding the first substrate and the second substrate, there is used a bonding agent that has a bonding force and can release bonding when necessary. Examples of the bonding agent that satisfies this condition include a UV curable pressure-sensitive adhesive and a liquid wax made of pine resin.
前者は紫外線を照射して硬化させることによって粘着力が失せ、後者はワックス洗浄液でワックスを洗浄除去することにより、第１の基板と第２の基板とが剥離可能となる。
第１の基板と第２の基板とを接合する接合剤としては、接合状態で第１の基板に電極材料を蒸着する工程に際して加わる２００〜２５０℃程度の温度でも剥離することのない接合剤、すなわち、真空における変形温度が２００℃以上である接合剤であることが好ましい。前者の接合剤は、この条件をも満足する。
接合剤を具体的に例示すれば、ＵＶ硬化型の粘着剤としては、アクリル系マレイシド樹脂、ポリエステル・ポリエーテル系マレイシド樹脂等が、また、松脂からなる液状ワックスとしては、日化精工（株）製商品名：スカイリキッドＰＷ−２５１１等が挙げられる。
接合剤は、第１の基板および／または第２の基板に塗布して用いることもできるが、接合剤を両面にあらかじめ塗布して、紫外線で硬化するテープ材（硬化して剥離することができるようになるテープ材）として用いることもできる。
The former loses its adhesive strength by being cured by irradiating with ultraviolet rays, and the latter can be peeled off from the first substrate and the second substrate by washing and removing the wax with a wax cleaning solution.
As a bonding agent for bonding the first substrate and the second substrate, a bonding agent that does not peel even at a temperature of about 200 to 250 ° C. applied during the step of vapor-depositing the electrode material on the first substrate in a bonded state, That is, a bonding agent having a deformation temperature in vacuum of 200 ° C. or higher is preferable. The former bonding agent also satisfies this condition.
Specific examples of bonding agents include UV-curable adhesives such as acrylic maleside resins and polyester / polyether maleic resins, and liquid waxes made of pine resin include Nikka Seiko Co., Ltd. Product name: Sky Liquid PW-2511 and the like.
The bonding agent can be used by being applied to the first substrate and / or the second substrate. However, the bonding agent is applied to both surfaces in advance and cured with ultraviolet rays (can be cured and peeled off). It can also be used as a tape material).
接合された第１の基板と第２の基板との複合材は、第１の基板を所望の厚さへと薄膜化するために、ラップあるいは研磨工程に付される。
複合材は、バックアップの第２の基板が接合されているので、十分な厚さを有しており、通常のラップあるいは研磨工程に用いられる治具をそのまま問題なく利用することができる等、ラップあるいは研磨工程に格別の創意工夫を施すことなく容易・簡便に、通例通り、実行することができる。
ラップあるいは研磨工程によって得られる第１の基板の厚さは、所望により適宜とすることが可能であるが、前述のとおり、表面弾性波素子としての機能を発揮できるのは２０μｍ以上であり、それ以下にまで薄膜化しても意味がない。厚い方は、任意に設定することができるが、従来達成されていた表面弾性波素子として利用されるタンタル酸リチウム単結晶基板の厚さが２００〜２５０μｍ程度まで薄型化が進行していたのであるから、１００μｍ以下とすることが好ましい。
The composite material of the bonded first substrate and second substrate is subjected to a lapping or polishing process in order to reduce the thickness of the first substrate to a desired thickness.
The composite material has a sufficient thickness because the back-up second substrate is bonded, so that a normal lap or a jig used in the polishing process can be used without any problem. Or it can carry out as usual, easily and simply, without giving special ingenuity to the polishing process.
The thickness of the first substrate obtained by the lapping or polishing process can be appropriately set as desired. However, as described above, the thickness of the first substrate that can function as a surface acoustic wave device is 20 μm or more. There is no point in reducing the film thickness to the following. The thicker one can be arbitrarily set, but the thinning of the lithium tantalate single crystal substrate used as a surface acoustic wave element, which has been achieved in the past, has been reduced to about 200 to 250 μm. Therefore, the thickness is preferably 100 μm or less.
第１の基板を所望の厚さにラップあるいは研磨した状態で、複合材として流通・取り引きさせることができる。複合材を購入したものが、必要により、更なる基板加工工程あるいは弾性表面波素子製造工程を施して、弾性表面波素子を製造することができる。
第１の基板が所望の厚さになされた複合材に、第１の基板に、櫛形化成形加工工程、電極材料を蒸着する工程等の、所要の弾性表面波素子製造工程を施して、弾性表面波素子用のタンタル酸リチウムとなしたタンタル酸リチウム単結晶複合基板として流通・取り引きさせることもできる。
弾性表面波素子用のタンタル酸リチウムとなしたタンタル酸リチウム単結晶複合基板を購入したものが、必要により、若干の弾性表面波素子製造工程を施して、弾性表面波素子を製造することができる。
The first substrate can be distributed and traded as a composite material in a state of being lapped or polished to a desired thickness. Those who have purchased the composite material can perform a further substrate processing step or a surface acoustic wave device manufacturing step to manufacture a surface acoustic wave device, if necessary.
The composite material in which the first substrate has a desired thickness is subjected to necessary surface acoustic wave element manufacturing processes such as a comb-forming process and an electrode material deposition process on the first substrate, and the elasticity It can also be distributed and traded as a lithium tantalate single crystal composite substrate that has become lithium tantalate for surface acoustic wave devices.
What purchased the lithium tantalate single crystal composite substrate made into lithium tantalate for the surface acoustic wave element can be subjected to some surface acoustic wave element manufacturing processes to manufacture the surface acoustic wave element if necessary. .
以下に、本発明の実施例をあげてさらに具体的に説明するが、本発明は、これらに限定されるものではない。
［実施例・比較例］
炭酸リチウムと五酸化タンタルとをコングルエント組成比となるように秤量し、混合し、電気炉で１０００℃以上に加熱することで得られた多結晶のタンタル酸リチウムを、イリジウム製のルツボに入れ、加熱、溶融後に、４２°回転Ｙ方向の種結晶を用いて回転引上げ（いわゆるチョクラルスキー法）にて育成し、直径が４インチの４２°回転Ｙ方向のタンタル酸リチウム単結晶粗柱を育成した。
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
[Examples and Comparative Examples]
Lithium carbonate and tantalum pentoxide are weighed so as to have a congruent composition ratio, mixed, and polycrystalline lithium tantalate obtained by heating to 1000 ° C. or higher in an electric furnace is placed in an iridium crucible, After heating and melting, grow by rotating pulling (so-called Czochralski method) using a 42 ° rotated Y-direction seed crystal to grow a 42 ° rotated Y-direction lithium tantalate single crystal crude column with a diameter of 4 inches. did.
このようにして得られた４インチのタンタル酸リチウム単結晶粗柱を電気炉中で６５０℃に加熱し、予めセットしていた金製の電極に電圧を印加することで単分域化処理を行い、両端を切断し、４インチの太さになるように円筒研削をした後に、ワイヤソーを用いてスライスして（スライス処理がされた）直径４インチ、厚さ５００μｍの４２°回転Ｙカットのタンタル酸リチウム単結晶基板となし、さらにこの単結晶基板をラップ機でＧＣ＃１０００のＳｉＣ砥粒を用いて研磨して直径４インチ、厚さ４００μｍのラップ基板とした。 The 4-inch lithium tantalate single crystal coarse column obtained in this way is heated to 650 ° C. in an electric furnace, and a voltage is applied to a gold electrode that has been set in advance to perform a single domain treatment. After cutting both ends and cylindrical grinding to a thickness of 4 inches, it was sliced using a wire saw (sliced), 4 inches in diameter and 500 μm in thickness, 42 ° rotated Y-cut This was formed as a lithium tantalate single crystal substrate, and this single crystal substrate was polished with a GC # 1000 SiC abrasive grain by a lapping machine to obtain a lapping substrate having a diameter of 4 inches and a thickness of 400 μm.
この厚さ４００μｍの４インチ、４２°回転Ｙカットのタンタル酸リチウムラップ基板を２枚用意し、松脂からなる液状ワックス：スカイリキッド ＰＷ−２５１１（日化精工（株）製商品名）を塗布し、加熱し、線膨張係数が最大値となるＸ軸方向を揃えて接合した。その後、第１の基板となる４インチ４２°回転Ｙカットのタンタル酸リチウム基板を、研削盤を用いて厚さ１００μｍまで研削し、ワックス剥離液：デベールＡ（日化精工（株）製商品名）で２枚のタンタル酸リチウム基板を分離した。 Two 400-μm thick 4-inch, 42 ° rotated Y-cut lithium tantalate wrap substrates are prepared, and liquid wax composed of pine resin: Sky Liquid PW-2511 (trade name, manufactured by Nikka Seiko Co., Ltd.) is applied. Then, the X-axis direction where the linear expansion coefficient becomes the maximum value is aligned and joined. Thereafter, a 4-inch 42 ° rotated Y-cut lithium tantalate substrate as a first substrate is ground to a thickness of 100 μm using a grinder, and a wax remover: Deveil A (trade name, manufactured by Nikka Seiko Co., Ltd.) ) To separate the two lithium tantalate substrates.
このようにして得られた厚さ６０μｍのタンタル酸リチウム基板と組み合わせる第２の基板を選択するために、厚さ４００μｍのタンタル酸リチウム基板以外に、市販の４インチサイズの１２８°回転Ｙニオブ酸リチウム基板（面方向における線膨張係数の最大値、つまりＸ軸方向の線膨張係数は１５．４×１０-6／℃）、６４°回転Ｙニオブ酸リチウム基板（Ｘ軸方向の線膨張係数は１５．４×１０-6／℃）、ＳＴカット水晶（面方向における線膨張係数の最大値は１３．４×１０-6／℃）、石英基板（方向性無し；線膨張係数０．５×１０-6／℃）、アルミナ基板（方向性無し；線膨張係数７．２×１０-6／℃）、シリコン基板（方向性無し；線膨張係数 ４．２×１０-6／℃）を準備し、厚さ４００μｍになるようにＧＣ＃１０００のＳｉＣ砥粒でラップした。 In order to select a second substrate to be combined with the 60 μm-thick lithium tantalate substrate thus obtained, in addition to the 400 μm-thick lithium tantalate substrate, a commercially available 4-inch size 128 ° rotated Y niobate Lithium substrate (the maximum value of the linear expansion coefficient in the plane direction, that is, the linear expansion coefficient in the X axis direction is 15.4 × 10 −6 / ° C.), the 64 ° rotated Y lithium niobate substrate (the linear expansion coefficient in the X axis direction is 15.4 × 10 −6 / ° C.), ST cut quartz (maximum linear expansion coefficient in the plane direction is 13.4 × 10 −6 / ° C.), quartz substrate (no directivity; linear expansion coefficient 0.5 × 10 −6 / ° C.), alumina substrate (no directivity; linear expansion coefficient 7.2 × 10 −6 / ° C.), silicon substrate (no directivity; linear expansion coefficient 4.2 × 10 −6 / ° C.) And GC # 1000 Si to a thickness of 400 μm It was wrapped in abrasive grains.
前記した研削盤で厚さ６０μｍとした４インチ４２°回転Ｙカットのタンタル酸リチウム基板と上述の各種の直径４インチ厚さ４００μｍの基板とをＵＶ硬化型粘合剤であるアクリル系マレイシド樹脂：ＵＶＡ３２００（東亞合成（株）製商品名））で接合した試料を作製し、弾性表面波素子を製造するための金属膜蒸着条件である２００℃、真空、１５分間での耐熱試験を行った。結果を表１に示す。 Acrylic maleside resin, which is a UV curable adhesive, comprising a 4-inch 42 ° rotated Y-cut lithium tantalate substrate having a thickness of 60 μm and a substrate having various diameters of 4 inches and a thickness of 400 μm, as described above: A sample joined by UVA3200 (trade name, manufactured by Toagosei Co., Ltd.) was prepared, and a heat resistance test was performed at 200 ° C. under vacuum and for 15 minutes, which are metal film deposition conditions for producing a surface acoustic wave device. The results are shown in Table 1.
表１より、４２°回転Ｙのタンタル酸リチウム基板と組み合わせることが可能な基板材料としては、耐熱試験の結果「剥離無し」となるためには、面内方向の線膨張係数の差が３×１０-6／℃以下であることが必要であることがわかる。 According to Table 1, as a substrate material that can be combined with a 42 ° rotation Y lithium tantalate substrate, the difference in linear expansion coefficient in the in-plane direction is 3 × in order to be “no peeling” as a result of the heat resistance test. It can be seen that it is necessary to be 10 −6 / ° C. or less.
本発明によれば、十分に薄層化した圧電基板（タンタル酸リチウム基板）が簡易・簡便に従来の技術の範囲で得ることができるので、弾性表面波（Surfaca Acoustic Wave、ＳＡＷ）素子が安価に多量に確実に得られ、携帯電話等の高周波通信分野に裨益するところが大きい。 According to the present invention, a sufficiently thin piezoelectric substrate (lithium tantalate substrate) can be obtained easily and easily within the range of conventional techniques, so that a surface acoustic wave (SAW) element is inexpensive. In particular, it can be obtained in large quantities and is beneficial in the field of high-frequency communications such as mobile phones.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010219706A (en) * | 2009-03-16 | 2010-09-30 | Murata Mfg Co Ltd | Surface acoustic wave element |
| JP2010232725A (en) * | 2009-03-25 | 2010-10-14 | Ngk Insulators Ltd | Composite substrate, elastic wave device using the same, and method for manufacturing composite substrate |
| WO2013141168A1 (en) * | 2012-03-23 | 2013-09-26 | 株式会社村田製作所 | Elastic wave device and manufacturing method for same |
| JPWO2013031650A1 (en) * | 2011-09-02 | 2015-03-23 | 株式会社村田製作所 | Elastic wave device and manufacturing method thereof |
| WO2019130905A1 (en) * | 2017-12-25 | 2019-07-04 | 株式会社村田製作所 | High-frequency apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010219706A (en) * | 2009-03-16 | 2010-09-30 | Murata Mfg Co Ltd | Surface acoustic wave element |
| JP2010232725A (en) * | 2009-03-25 | 2010-10-14 | Ngk Insulators Ltd | Composite substrate, elastic wave device using the same, and method for manufacturing composite substrate |
| JPWO2013031650A1 (en) * | 2011-09-02 | 2015-03-23 | 株式会社村田製作所 | Elastic wave device and manufacturing method thereof |
| WO2013141168A1 (en) * | 2012-03-23 | 2013-09-26 | 株式会社村田製作所 | Elastic wave device and manufacturing method for same |
| CN104205629A (en) * | 2012-03-23 | 2014-12-10 | 株式会社村田制作所 | Elastic wave device and manufacturing method for same |
| JPWO2013141168A1 (en) * | 2012-03-23 | 2015-08-03 | 株式会社村田製作所 | Elastic wave device and manufacturing method thereof |
| US9413334B2 (en) | 2012-03-23 | 2016-08-09 | Murata Manufacturing Co., Ltd. | Elastic wave device using SH surface acoustic wave |
| CN104205629B (en) * | 2012-03-23 | 2016-12-28 | 株式会社村田制作所 | Acoustic wave device and manufacture method thereof |
| WO2019130905A1 (en) * | 2017-12-25 | 2019-07-04 | 株式会社村田製作所 | High-frequency apparatus |
| US11482987B2 (en) | 2017-12-25 | 2022-10-25 | Murata Manufacturing Co., Ltd. | High-frequency apparatus |
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