JPH10154834A - Ferroelectric element and manufacture thereof - Google Patents
Ferroelectric element and manufacture thereofInfo
- Publication number
- JPH10154834A JPH10154834A JP31049196A JP31049196A JPH10154834A JP H10154834 A JPH10154834 A JP H10154834A JP 31049196 A JP31049196 A JP 31049196A JP 31049196 A JP31049196 A JP 31049196A JP H10154834 A JPH10154834 A JP H10154834A
- Authority
- JP
- Japan
- Prior art keywords
- film
- ferroelectric
- lower electrode
- substrate
- forming
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 19
- 239000000758 substrate Substances 0.000 claims abstract description 63
- 239000007789 gas Substances 0.000 claims abstract description 42
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 34
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 26
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000001301 oxygen Substances 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 20
- 229910052786 argon Inorganic materials 0.000 claims abstract description 19
- 239000000463 material Substances 0.000 claims abstract description 10
- 238000004544 sputter deposition Methods 0.000 claims description 34
- 239000013078 crystal Substances 0.000 claims description 18
- 239000007772 electrode material Substances 0.000 claims description 11
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 8
- 235000002639 sodium chloride Nutrition 0.000 claims description 8
- 239000011780 sodium chloride Substances 0.000 claims description 8
- 229910052741 iridium Inorganic materials 0.000 claims description 5
- 229910052763 palladium Inorganic materials 0.000 claims description 5
- 229910052737 gold Inorganic materials 0.000 claims description 4
- 229910052697 platinum Inorganic materials 0.000 claims description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 abstract description 10
- 229910001882 dioxygen Inorganic materials 0.000 abstract description 10
- 230000015572 biosynthetic process Effects 0.000 abstract description 8
- 239000010408 film Substances 0.000 description 92
- 239000010410 layer Substances 0.000 description 32
- 239000010409 thin film Substances 0.000 description 19
- 239000000203 mixture Substances 0.000 description 15
- 229910018487 Ni—Cr Inorganic materials 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000002131 composite material Substances 0.000 description 5
- 238000001755 magnetron sputter deposition Methods 0.000 description 5
- 238000009792 diffusion process Methods 0.000 description 4
- 230000002411 adverse Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000005137 deposition process Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910000599 Cr alloy Inorganic materials 0.000 description 1
- 229910018106 Ni—C Inorganic materials 0.000 description 1
- 239000012790 adhesive layer Substances 0.000 description 1
- NKZSPGSOXYXWQA-UHFFFAOYSA-N dioxido(oxo)titanium;lead(2+) Chemical compound [Pb+2].[O-][Ti]([O-])=O NKZSPGSOXYXWQA-UHFFFAOYSA-N 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 238000005459 micromachining Methods 0.000 description 1
- 238000009751 slip forming Methods 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
Landscapes
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
- Micromachines (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、焦電型赤外線セン
サ、圧電力学量センサ、あるいは圧電アクチュエータ等
に使用される強誘電体薄膜を用いた各種強誘電体素子お
よびその製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various ferroelectric elements using a ferroelectric thin film used for a pyroelectric infrared sensor, a piezoelectric dynamic quantity sensor, a piezoelectric actuator, and the like, and a method of manufacturing the same.
【０００２】[0002]
【従来の技術】強誘電体のエレクトロニクス分野におけ
る応用は、赤外線センサ、圧電素子、光変調素子、メモ
リ素子などさまざまなものがある。例えば、焦電型の赤
外線センサとして、高山らにより、ＭｇＯ基板上に、下
部電極として（１００）面に配向したＰｔ膜を形成し、
その上にｃ軸配向したペロブスカイト構造のランタンを
添加したチタン酸鉛系強誘電体（ＰＬＴ）薄膜を形成さ
せ、上部受光電極としてＮｉ−Ｃｒ膜を形成したデバイ
スが報告されている（Jounal of Applied Physics,63(1
2),1988 p5868-5872）。この場合、強誘電体である焦電
体は、分極処理を行わなくても、分極方向が一方向に揃
っており、赤外線の入射とともに焦電電流が検出され
る。さらに、分極処理したバルク焼結体と比較して、約
３倍の焦電特性が得られている。また、小谷らにより、
上記例とほぼ同様の構成を有する、ＭｇＯ基板の表面マ
イクロマシンニングを用いて形成したマイクロキャビテ
ィを有する赤外線センサの例が報告されている（Japane
se Jounal of Applied Physics,32,1993 p6297-630
0）。2. Description of the Related Art There are various applications of ferroelectrics in the field of electronics, such as infrared sensors, piezoelectric elements, light modulation elements, and memory elements. For example, as a pyroelectric infrared sensor, Takayama et al. Formed a Pt film oriented on a (100) plane as a lower electrode on an MgO substrate,
A device has been reported in which a lead titanate ferroelectric (PLT) thin film to which a lanthanum having a perovskite structure with c-axis orientation is added is formed thereon, and a Ni—Cr film is formed as an upper light receiving electrode (Jounal of Applied). Physics, 63 (1
2), 1988 p5868-5872). In this case, the pyroelectric body, which is a ferroelectric substance, has a uniform polarization direction without performing the polarization process, and the pyroelectric current is detected together with the incidence of infrared rays. Furthermore, the pyroelectric property is about three times that of the polarized bulk sintered body. Also, by Kotani et al.
An example of an infrared sensor having a microcavity formed using surface micromachining of an MgO substrate and having a configuration substantially similar to the above example has been reported (Japane).
se Jounal of Applied Physics, 32,1993 p6297-630
0).
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、これら
従来例のような構成では、デバイス化プロセスにおける
エッチング工程、実装の際のワイヤボンディング工程な
どにおいて、Ｐｔ等の下部電極とＭｇＯ基板の間の密着
力が弱いために種々の不都合が生じていた。すなわち、
下部電極がＭｇＯ基板から剥離することによる不良を起
こしたり、前記密着力が弱いことが電気特性自体にも悪
影響を及ぼすために製造歩留まりが悪くなるなどであ
る。また、下部電極上に強誘電体膜を形成する際に、初
期堆積過程において組成ずれを起こし、その後の堆積過
程において組成は化学量論比となるものの全体的な素子
特性は低下するという問題があった。本発明は、上記の
ような下部電極膜の剥離や、強誘電体膜の組成ずれを解
決し、小型で高感度な強誘電体素子を提供することを目
的とする。また、本発明は、そのような強誘電体素子を
歩留まり良く製造する方法を提供することを目的とす
る。However, in such a configuration as in the prior art, the adhesion between the lower electrode such as Pt and the MgO substrate in the etching step in the device fabrication process, the wire bonding step in the mounting, and the like. Had a variety of inconveniences. That is,
The lower electrode may cause a defect due to peeling off from the MgO substrate, or the weak adhesion may adversely affect the electric characteristics itself, thereby lowering the production yield. In addition, when a ferroelectric film is formed on a lower electrode, a composition shift occurs in an initial deposition process, and in the subsequent deposition process, the composition becomes a stoichiometric ratio, but overall device characteristics are deteriorated. there were. An object of the present invention is to provide a small and highly sensitive ferroelectric element which solves the above-described peeling of the lower electrode film and the composition deviation of the ferroelectric film. Another object of the present invention is to provide a method for manufacturing such a ferroelectric element with high yield.
【０００４】[0004]
【課題を解決するための手段】本発明の強誘電体素子
は、基板、並びに前記基板上に順次配置した密着層、下
部電極、強誘電体膜、および上部電極を具備し、前記密
着層が前記下部電極を構成する材料と酸素からなる。本
発明の第１の強誘電体素子の製造方法は、基板上に密着
層を形成する工程、前記密着層上に下部電極を形成する
工程、前記下部電極上に強誘電体膜を形成する工程、お
よび前記強誘電体膜上に上部電極を形成する工程を有
し、前記密着層を形成する工程が、分圧比２０％以上の
酸素を含むアルゴンガス雰囲気中において下部電極材料
をターゲットとしたスパッタリング法により行われ、前
記密着層上に下部電極を形成する工程が、前記密着層の
形成工程に引き続きアルゴンガスのみの雰囲気中におい
て下部電極材料をターゲットとしたスパッタリング法に
より行われる。A ferroelectric device according to the present invention comprises a substrate, and an adhesion layer, a lower electrode, a ferroelectric film, and an upper electrode sequentially arranged on the substrate, wherein the adhesion layer is It is composed of oxygen and a material constituting the lower electrode. According to the first method of manufacturing a ferroelectric element of the present invention, a step of forming an adhesion layer on a substrate, a step of forming a lower electrode on the adhesion layer, and a step of forming a ferroelectric film on the lower electrode And forming an upper electrode on the ferroelectric film, wherein the step of forming the adhesion layer is performed by sputtering using a lower electrode material as a target in an argon gas atmosphere containing oxygen having a partial pressure ratio of 20% or more. The step of forming a lower electrode on the adhesion layer is performed by a sputtering method using the lower electrode material as a target in an atmosphere containing only argon gas, following the step of forming the adhesion layer.
【０００５】本発明の第２の強誘電体素子の製造方法
は、基板上に下部電極を形成する工程、前記下部電極上
に強誘電体膜を形成する工程、および前記強誘電体膜上
に上部電極を形成する工程を有し、前記強誘電体膜を形
成する工程が、アルゴンガス雰囲気中において酸化物を
ターゲットとしたスパッタリング法により強誘電体膜を
形成する工程と、引き続き酸素を含むアルゴンガス雰囲
気中において前記酸化物をターゲットとしたスパッタリ
ング法により強誘電体膜を形成する工程からなる。第２
の製造方法において、アルゴンガス雰囲気中で形成する
強誘電体膜の厚みは、５ｎｍ以上２０ｎｍ以下とするの
が好ましい。また、第２の製造方法において、下部電極
を形成する工程に先だって、基板上に密着層を形成する
工程を有することが好ましい。According to a second method of manufacturing a ferroelectric element of the present invention, a step of forming a lower electrode on a substrate, a step of forming a ferroelectric film on the lower electrode, and a step of forming a ferroelectric film on the ferroelectric film Forming a ferroelectric film by sputtering using an oxide target in an argon gas atmosphere; and forming argon gas containing oxygen continuously. A step of forming a ferroelectric film by a sputtering method using the oxide as a target in a gas atmosphere. Second
In the method described above, the thickness of the ferroelectric film formed in an argon gas atmosphere is preferably 5 nm or more and 20 nm or less. In the second manufacturing method, it is preferable that the method further includes a step of forming an adhesion layer on the substrate before the step of forming the lower electrode.
【０００６】上記において、密着層の厚みは、５ｎｍ以
上５０ｎｍ以下であることが好ましい。また、基板は、
ＭｇＯ単結晶基板または岩塩型結晶構造の酸化物膜を積
層した基板であることが好ましい。前記岩塩型結晶構造
の酸化物膜としては、ＭｇＯ、ＮｉＯ、およびＣｏＯか
らなる群より選ばれた少なくとも一種の膜が好ましい。
下部電極材料は、Ｐｔ、Ｐｄ、Ｉｒ、およびＡｕからな
る群より選ばれた少なくとも一種であることが好まし
い。[0006] In the above, the thickness of the adhesion layer is preferably 5 nm or more and 50 nm or less. Also, the substrate is
An MgO single crystal substrate or a substrate on which an oxide film having a rock salt type crystal structure is stacked is preferable. As the oxide film having the rock salt type crystal structure, at least one film selected from the group consisting of MgO, NiO, and CoO is preferable.
The lower electrode material is preferably at least one selected from the group consisting of Pt, Pd, Ir, and Au.
【０００７】[0007]
【発明の実施の形態】本発明の強誘電体素子は、上記の
ように、基板と下部電極との間に、下部電極を構成する
材料と酸素からなる密着層を有する。この密着層によ
り、基板と下部電極膜との密着性が向上する。一般に、
基板とその上に積層する薄膜の密着性は、それぞれの材
料のもつ熱膨張係数の違いと、積層する薄膜の成膜時の
真空度に基づく膜内残留応力が原因する。例えば、Ｍｇ
Ｏ基板とその上に形成する下部電極としてのＰｔ膜と
は、熱膨張係数に違いがある。さらに、Ｐｔ膜の成膜時
の真空度（ガス圧）によっては、Ｐｔ膜内は圧縮応力に
なったり、引張り応力になったりする。比較的高い基板
温度でスパッタ成膜する場合、基板とその上に形成され
る膜との界面には、熱拡散やスパッタリング効果による
基板元素と膜元素から構成される混合層が形成される。
混合層が緻密に形成されれば、基板と膜の密着性が向上
する。本発明では、この混合層として、下部電極材料と
酸素からなる層を利用する。この密着層は、前記第１の
製造方法で述べたように、分圧比２０％以上の酸素を含
むアルゴンガス雰囲気中において下部電極材料をターゲ
ットとしたスパッタリング法により行い、引き続きアル
ゴンガスのみの雰囲気中において下部電極材料をターゲ
ットとしたスパッタリング法により下部電極を形成する
のが好ましい。BEST MODE FOR CARRYING OUT THE INVENTION As described above, a ferroelectric device of the present invention has an adhesion layer made of a material constituting a lower electrode and oxygen between a substrate and a lower electrode. The adhesion layer improves the adhesion between the substrate and the lower electrode film. In general,
The adhesion between the substrate and the thin film laminated thereon is caused by the difference in thermal expansion coefficient of each material and the residual stress in the film based on the degree of vacuum at the time of forming the laminated thin film. For example, Mg
The O substrate and the Pt film as the lower electrode formed thereon have different coefficients of thermal expansion. Further, depending on the degree of vacuum (gas pressure) at the time of forming the Pt film, the inside of the Pt film becomes a compressive stress or a tensile stress. When a film is formed by sputtering at a relatively high substrate temperature, a mixed layer composed of a substrate element and a film element is formed at an interface between the substrate and a film formed thereon by thermal diffusion or a sputtering effect.
If the mixed layer is formed densely, the adhesion between the substrate and the film is improved. In the present invention, a layer composed of a lower electrode material and oxygen is used as the mixed layer. As described in the first manufacturing method, this adhesion layer is formed by a sputtering method using a lower electrode material as a target in an argon gas atmosphere containing oxygen at a partial pressure ratio of 20% or more, and then in an atmosphere containing only argon gas. Preferably, the lower electrode is formed by a sputtering method using a lower electrode material as a target.
【０００８】複合酸化物材料を結晶成長させるために、
比較的高い基板温度でスパッタ成膜する場合、その材料
を構成する各元素のスパッタ率の違いや蒸気圧の違いに
より、化学量論比の組成のものを得ることは非常に難し
い。組成が化学量論比からずれると、形成される複合酸
化物薄膜の結晶性や膜特性に悪い影響を及ぼす。そこ
で、本発明では、アルゴンガス雰囲気中において酸化物
をターゲットとしたスパッタリング法により強誘電体膜
を形成する工程と、引き続き酸素を含むアルゴンガス雰
囲気中において前記酸化物をターゲットとしたスパッタ
リング法により強誘電体膜を形成する工程により、強誘
電体膜を形成する。このように、強誘電体膜の成膜初期
過程において、酸素ガス未導入により特にＰｂ元素のス
パッタ率を上昇させて成膜する。酸素ガス未導入時は、
酸素が不足すると考えられるが、酸化物のターゲットを
用いていることと、その後の酸素ガスを含む雰囲気中の
成膜によるスパッタリング効果や熱拡散効果により、不
足分の酸素が補足されるのである。[0008] In order to grow the crystal of the composite oxide material,
When a sputter film is formed at a relatively high substrate temperature, it is very difficult to obtain a composition having a stoichiometric composition due to a difference in sputtering rate and a difference in vapor pressure of each element constituting the material. When the composition deviates from the stoichiometric ratio, the crystallinity and film characteristics of the formed composite oxide thin film are adversely affected. Thus, in the present invention, a step of forming a ferroelectric film by a sputtering method using an oxide as a target in an argon gas atmosphere, and a subsequent step of forming a ferroelectric film by a sputtering method using the oxide as a target in an argon gas atmosphere containing oxygen. The ferroelectric film is formed by the step of forming the dielectric film. As described above, in the initial stage of the film formation of the ferroelectric film, the film is formed by increasing the sputtering rate of the Pb element in particular by introducing no oxygen gas. When oxygen gas is not introduced,
It is thought that oxygen is insufficient. However, the lack of oxygen is supplemented by the use of an oxide target and the subsequent sputtering effect and thermal diffusion effect of film formation in an atmosphere containing oxygen gas.
【０００９】[0009]
【実施例】以下、本発明を実施例により詳細に説明す
る。 《実施例１》図１は本実施例の強誘電体素子１０を示
す。基板１１は、（１００）面で劈開し、鏡面研磨処理
したＭｇＯ単結晶基板からできている。この基板１１上
には、密着層１２としての酸素とＰｔからなる膜、Ｐｔ
膜からなる下部電極１３、強誘電体膜１４としてのＰｂ
0.9Ｌａ0.1Ｔｉ0.975Ｏ3（ＰＬＴ）膜、およびＮｉ−Ｃ
ｒ膜からなる上部電極１５が順次配置されている。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. << Embodiment 1 >> FIG. 1 shows a ferroelectric element 10 of this embodiment. The substrate 11 is made of a MgO single crystal substrate that has been cleaved on the (100) plane and mirror-polished. On this substrate 11, a film made of oxygen and Pt as an adhesion layer 12, Pt
Pb as the lower electrode 13 made of a film and the ferroelectric film 14
0.9 La 0.1 Ti 0.975 O 3 (PLT) film and Ni-C
Upper electrodes 15 made of an r film are sequentially arranged.
【００１０】次に、この強誘電体素子１０の形成方法に
ついて説明する。まず、真空槽内にＭｇＯ単結晶基板１
１を設置し、槽内を真空に排気した後、基板１１を６０
０℃まで加熱し、ＲＦマグネトロンスパッタ法により４
インチのＰｔ板をターゲットとしてＡｒとＯ2の混合ガ
ス、例えば混合比Ａｒ：Ｏ2＝１：１をスパッタガスと
し、ガス圧１Ｐａ、ＲＦ電力１００Ｗにて密着層１２を
厚み１５ｎｍ形成した。その密着層１２上に、引き続き
マグネトロンスパッタ法で同温度、同電力にて下部電極
としてのＰｔ膜１３をＡｒスパッタガスのみを用いて１
Ｐａのガス圧にて厚み２００ｎｍ形成した。さらに、そ
のＰｔ１３上にＲＦマグネトロンスパッタ法により６イ
ンチのＰＬＴ焼結体ターゲット（ＰｂＯを化学量論比よ
り２０ｍｏｌ％過剰に添加）を用い、５８０℃にてＰＬ
Ｔ薄膜１４をガスの混合比Ａｒ：Ｏ2 ＝２５：１、ガス
圧０．４Ｐａのスパッタガス雰囲気中、ＲＦ電力４００
Ｗにて厚み２μｍ形成した。その後、上部電極１５とし
てＮｉ−Ｃｒ膜をＤＣスパッタ法により４インチのＮｉ
−Ｃｒ合金のターゲットを用い、スパッタリングガスの
Ａｒガス０．７Ｐａの雰囲気中で１００Ｗの電力によ
り、基板を加熱せずにＡｒスパッタガスを用いて厚み１
０ｎｍ形成した。Next, a method of forming the ferroelectric element 10 will be described. First, the MgO single crystal substrate 1 was placed in a vacuum chamber.
1 was set, and the inside of the tank was evacuated to a vacuum.
Heat to 0 ° C, and use RF magnetron sputtering
Using an inch Pt plate as a target, a mixed gas of Ar and O 2 , for example, a mixture ratio of Ar: O 2 = 1: 1 was used as a sputtering gas, and a gas pressure of 1 Pa and an RF power of 100 W were used to form an adhesion layer 12 having a thickness of 15 nm. On the adhesive layer 12, a Pt film 13 as a lower electrode is continuously formed by magnetron sputtering at the same temperature and power using only Ar sputtering gas.
At a gas pressure of Pa, a thickness of 200 nm was formed. Further, on the Pt13, a 6-inch PLT sintered body target (PbO was added in an excess of 20 mol% from the stoichiometric ratio) by RF magnetron sputtering, and the PL was irradiated at 580 ° C.
The T thin film 14 is mixed with a gas mixture ratio of Ar: O 2 = 25: 1 and a gas pressure of 0.4 Pa in an atmosphere of a sputtering gas at an RF power
W was formed to a thickness of 2 μm. After that, a Ni-Cr film was formed as a 4-inch Ni
Using a target of -Cr alloy and a power of 100 W in an atmosphere of Ar gas as a sputtering gas of 0.7 Pa, the substrate is heated to a thickness of 1 using an Ar sputtering gas without heating the substrate.
0 nm was formed.
【００１１】上記において、密着層１２を形成する際の
酸素ガスの分圧比を変えて密着層を形成し、その上に下
部電極を形成し、下部電極の剥離による不良率を調べ
た。その結果を図２に示す。酸素ガスの分圧比が０、す
なわち、密着層１２がない場合は、下部電極Ｐｔ膜１３
上にＡｌリード線をワイヤボンディングする際、２０〜
３０％程度の剥離不良が発生した。引張り試験時も含め
ると剥離不良は６０％強となる。一般に、基板とその上
に積層する薄膜の密着性は、それぞれの材料のもつ熱膨
張係数の違いと、積層する薄膜の成膜時の真空度に基づ
く膜内残留応力が原因する。この場合も、ＭｇＯ基板と
Ｐｔ膜とは熱膨張係数に違いがある。さらに、前記した
成膜時の真空度（ガス圧）においては、Ｐｔ膜内は圧縮
応力となる。比較的高い基板温度でスパッタ成膜する場
合、基板とその上に形成される膜との界面には、熱拡散
やスパッタリング効果による基板元素と膜元素から構成
される混合層が形成される。混合層が緻密に形成されれ
ば、基板と膜の密着性が向上する。本実施例において、
ＭｇＯ基板上にスパッタリング法でＰｔ電極膜を形成す
る場合に、Ｏ2ガス分圧比２０％以上のＡｒとＯ2の混合
ガス雰囲気で、その厚みを５ｎｍ以上５０ｎｍ以下の範
囲で形成すれば、酸素とＰｔからなる良好な密着層が形
成される。そして、その上に形成した下部電極膜１３上
にＡｌリード線をワイヤボンディングしても、下部電極
膜１３の剥離不良は５％以下に抑えることができる。In the above, the adhesion layer was formed by changing the partial pressure ratio of oxygen gas when forming the adhesion layer 12, the lower electrode was formed thereon, and the defect rate due to the separation of the lower electrode was examined. The result is shown in FIG. If the partial pressure ratio of oxygen gas is 0, that is, if there is no adhesion layer 12, the lower electrode Pt film 13
When wire bonding an Al lead wire on top,
Approximately 30% peeling failure occurred. If the tensile test is also included, the peeling failure is more than 60%. Generally, the adhesion between a substrate and a thin film laminated thereon is caused by a difference in thermal expansion coefficient of each material and a residual stress in the film based on the degree of vacuum at the time of film formation of the laminated thin film. Also in this case, there is a difference in the thermal expansion coefficient between the MgO substrate and the Pt film. Further, at the degree of vacuum (gas pressure) at the time of the film formation, the Pt film has a compressive stress. When a film is formed by sputtering at a relatively high substrate temperature, a mixed layer composed of a substrate element and a film element is formed at an interface between the substrate and a film formed thereon by thermal diffusion or a sputtering effect. If the mixed layer is formed densely, the adhesion between the substrate and the film is improved. In this embodiment,
When a Pt electrode film is formed on a MgO substrate by a sputtering method, if the Pt electrode film is formed in a mixed gas atmosphere of Ar and O 2 having a partial pressure ratio of O 2 gas of 20% or more and a thickness of 5 nm or more and 50 nm or less, oxygen can be obtained. And a good adhesion layer made of Pt is formed. Then, even if an Al lead wire is wire-bonded on the lower electrode film 13 formed thereon, peeling failure of the lower electrode film 13 can be suppressed to 5% or less.
【００１２】ただし、密着層１２の厚みが５ｎｍより薄
い場合は、ＭｇＯ基板表面の凹凸自体がこの程度あるた
め、Ｐｔ膜とＭｇＯ基板の間に密着層が介在しない領域
が存在し、ボンディングの不良率が急に増大する。ま
た、密着層１２の厚みが５０ｎｍを越える場合は、密着
性は良好なものの、その上に形成する下部電極１３の表
面凹凸状態が粗くなり、さらにその上に形成するＰＬＴ
強誘電体薄膜１４の特性が低下するという現象が起き
る。強誘電体薄膜を形成する場合、下地基板表面の結晶
性や凹凸の程度が、強誘電体膜自体の結晶性および膜特
性に影響を与える。この場合、密着層１２の厚みが５０
ｎｍ以下であれば、下部電極上に形成するＰＬＴ膜はｃ
軸配向の強い膜特性の良好なものが得られた。However, when the thickness of the adhesion layer 12 is smaller than 5 nm, the unevenness of the surface of the MgO substrate itself is at this level, and there is a region where the adhesion layer is not interposed between the Pt film and the MgO substrate. The rate increases sharply. When the thickness of the adhesion layer 12 exceeds 50 nm, although the adhesion is good, the surface unevenness of the lower electrode 13 formed thereon becomes rough, and the PLT formed thereon further becomes rough.
A phenomenon occurs in which the characteristics of the ferroelectric thin film 14 deteriorate. When a ferroelectric thin film is formed, the crystallinity and the degree of irregularities on the surface of the underlying substrate affect the crystallinity and film characteristics of the ferroelectric film itself. In this case, the thickness of the adhesion layer 12 is 50
nm or less, the PLT film formed on the lower electrode is c
A film with strong axial orientation and good film properties was obtained.
【００１３】ここで、基板１１としてＭｇＯ、ＮｉＯ、
ＣｏＯ等の岩塩型結晶構造の酸化物膜を積層した基板を
用いても、強誘電体薄膜の膜特性を損なうことなく、下
部電極と基板の密着性の良好な結果が得られた。また、
下部電極１３として、Ｐｄ、Ｉｒ、またはＡｕを用いて
も、強誘電体薄膜１４の特性を損なうことなく、同様に
下部電極と基板の密着性の良好な結果が得られた。Here, MgO, NiO,
Even when a substrate on which an oxide film of a rock salt type crystal structure such as CoO was laminated was used, a favorable result of the adhesion between the lower electrode and the substrate was obtained without impairing the film characteristics of the ferroelectric thin film. Also,
Even when Pd, Ir, or Au was used as the lower electrode 13, a favorable result of the adhesion between the lower electrode and the substrate was similarly obtained without impairing the characteristics of the ferroelectric thin film.
【００１４】《実施例２》本実施例の強誘電体素子の構
成を図３に示す。この強誘電体素子２０は、基板２１と
して（１００）面に配向したＭｇＯ単結晶基板を用いて
いる。この基板２１上に、Ｐｔ膜からなる下部電極２３
を配置し、その上に強誘電体膜２４としてＰｂ0.9Ｌａ
0.1Ｔｉ0.975Ｏ3（ＰＬＴ）膜を配置し、さらにその上
にＮｉ−Ｃｒ膜からなる上部電極２５が配置されてい
る。Embodiment 2 FIG. 3 shows a configuration of a ferroelectric element of this embodiment. This ferroelectric element 20 uses a MgO single crystal substrate oriented in the (100) plane as the substrate 21. On this substrate 21, a lower electrode 23 made of a Pt film is formed.
Is disposed thereon, and Pb 0.9 La is formed thereon as a ferroelectric film 24.
A 0.1 Ti 0.975 O 3 (PLT) film is disposed, and an upper electrode 25 made of a Ni—Cr film is disposed thereon.
【００１５】この強誘電体素子２０の形成方法について
以下に説明する。まず、真空槽内にＭｇＯ単結晶基板２
１を設置し、槽内を真空排気した後、基板２１を６００
℃まで加熱し、ＲＦマグネトロンスパッタ法により４イ
ンチのＰｔ板をターゲットとして、Ａｒスパッタガス圧
１Ｐａ、ＲＦ電力１００Ｗにて下部電極としてＰｔ膜２
３を厚み２００ｎｍ形成した。さらに、そのＰｔ下部電
極膜２３上に、ＲＦマグネトロンスパッタ法により６イ
ンチのＰＬＴ焼結体ターゲットを用いて、設定温度５８
０℃、ガス圧０．４ＰａのＡｒのみのスパッタガス雰囲
気中、ＲＦ電力４００Ｗにて第１のＰＬＴ薄膜２４を厚
み約１０ｎｍ形成した後、同温度、同電力、ガス比Ａ
ｒ：Ｏ2 ＝２５：１、ガス圧０．４Ｐａのスパッタガス
雰囲気中にて第２のＰＬＴ薄膜２５を厚み２μｍ形成し
た。その後、上部電極２６としてＮｉ−Ｃｒ膜をＤＣス
パッタ法にて基板を加熱せずにＡｒスパッタガスを用い
て厚み１０ｎｍ形成した。A method for forming the ferroelectric element 20 will be described below. First, the MgO single crystal substrate 2 was placed in a vacuum chamber.
1 was set, and the inside of the tank was evacuated to vacuum.
C., and a Pt film 2 as a lower electrode at an Ar sputtering gas pressure of 1 Pa and an RF power of 100 W using a 4 inch Pt plate as a target by RF magnetron sputtering.
3 was formed to a thickness of 200 nm. Further, on the Pt lower electrode film 23, a set temperature of 58 mm was set by RF magnetron sputtering using a 6-inch PLT sintered body target.
After forming the first PLT thin film 24 to a thickness of about 10 nm at a RF power of 400 W in a sputtering gas atmosphere of only Ar at 0 ° C. and a gas pressure of 0.4 Pa, the same temperature, the same power and the gas ratio A are used.
A second PLT thin film 25 was formed in a thickness of 2 μm in a sputtering gas atmosphere of r: O 2 = 25: 1 and gas pressure of 0.4 Pa. Thereafter, as the upper electrode 26, a Ni-Cr film was formed by a DC sputtering method to a thickness of 10 nm using an Ar sputtering gas without heating the substrate.
【００１６】複合酸化物材料を結晶成長させるために、
比較的高い基板温度でスパッタ成膜する場合、その材料
を構成する各元素のスパッタ率の違いや蒸気圧の違いに
より、化学量論比の組成のものを得ることは非常に難し
い。組成が化学量論比からずれると、形成される複合酸
化物薄膜の結晶性や膜特性に悪い影響を及ぼす。実際、
この複合酸化物の強誘電体素子を形成する場合も、Ｐｔ
下部電極上にＰＬＴ薄膜を形成する際に、最初からガス
混合比Ａｒ：Ｏ2 ＝２５：１の酸素ガスを含む雰囲気で
成膜する時は、下部電極との界面から２０ｎｍ付近まで
はＰｂ元素の不足による組成ずれが観測された。しかし
ながら、本実施例により形成したＰＬＴ薄膜素子におい
ては、素子特性（焦電性能指数）に１０％程度の向上が
みられた。これはＰＬＴ成膜初期過程において、酸素ガ
ス未導入によりＰｂ元素のスパッタ率を上昇させて成膜
したために組成が合った結果と考えられる。酸素ガス未
導入時は、酸素が不足すると考えられるが、酸化物のタ
ーゲットを用いていることと、その後の酸素ガスを含む
雰囲気中の成膜によるスパッタリング効果や熱拡散効果
により、不足分の酸素が補足されると考えられる。この
ように本実施例のような構成の製造方法により、特性の
良好な強誘電体素子を実現することができる。In order to grow a composite oxide material,
When a sputter film is formed at a relatively high substrate temperature, it is very difficult to obtain a composition having a stoichiometric composition due to a difference in sputtering rate and a difference in vapor pressure of each element constituting the material. When the composition deviates from the stoichiometric ratio, the crystallinity and film characteristics of the formed composite oxide thin film are adversely affected. In fact,
When forming a ferroelectric element of this composite oxide, Pt
When forming a PLT thin film on the lower electrode, when forming a film in an atmosphere containing an oxygen gas having a gas mixture ratio of Ar: O 2 = 25: 1 from the beginning, a Pb element is formed up to about 20 nm from the interface with the lower electrode. The composition deviation due to the shortage was observed. However, in the PLT thin film device formed according to the present embodiment, the device characteristics (pyroelectric performance index) were improved by about 10%. This is considered to be the result of the fact that the composition was matched in the initial stage of the PLT film formation because the film was formed by increasing the sputtering rate of the Pb element without introducing oxygen gas. When oxygen gas is not introduced, it is considered that oxygen is insufficient.However, due to the use of an oxide target and the subsequent sputtering effect and thermal diffusion effect of film formation in an atmosphere containing oxygen gas, the insufficient oxygen is used. Is thought to be supplemented. As described above, a ferroelectric element having good characteristics can be realized by the manufacturing method having the configuration as in the present embodiment.
【００１７】ここで、基板２１として、ＭｇＯ、Ｎｉ
Ｏ、ＣｏＯ等の岩塩型結晶構造の酸化物膜を積層した基
板を用いても、全く同様に強誘電体薄膜の特性の良好な
素子を形成することできる。また、下部電極２３とし
て、Ｐｄ、Ｉｒ、またはＡｕを用いても、全く同様の結
果が得られる。また、基板上に下部電極を形成する前
に、Ｔｉ等の密着層、またはアルゴン、酸素の混合ガス
雰囲気で下部電極材料を用いて形成する混合密着層を形
成した場合も全く同様に強誘電体薄膜の特性の良好な素
子を形成することできる。この場合は、下部電極の密着
性も良好となり、素子製造の歩留まりが大幅に向上す
る。Here, as the substrate 21, MgO, Ni
Even if a substrate on which an oxide film having a rock salt type crystal structure such as O or CoO is laminated is used, a device having excellent characteristics of a ferroelectric thin film can be formed in exactly the same manner. Further, even when Pd, Ir, or Au is used as the lower electrode 23, exactly the same result can be obtained. Similarly, when an adhesion layer made of Ti or the like or a mixed adhesion layer formed using a lower electrode material in a mixed gas atmosphere of argon and oxygen is formed before the lower electrode is formed on the substrate, the ferroelectric substance is completely similar. An element having good thin film characteristics can be formed. In this case, the adhesion of the lower electrode is also improved, and the yield of element production is greatly improved.
【００１８】[0018]
【発明の効果】以上のように本発明によれば、下部電極
膜の剥離や、強誘電体膜の組成ずれを解決し、小型で高
感度な強誘電体素子を得ることができる。また、本発明
の製造方法によれば、小型で高感度な強誘電体素子を従
来に比べて低価格で製造することができる。As described above, according to the present invention, the separation of the lower electrode film and the deviation of the composition of the ferroelectric film can be solved, and a small and highly sensitive ferroelectric element can be obtained. Further, according to the manufacturing method of the present invention, a small and high-sensitivity ferroelectric element can be manufactured at a lower price than before.
【図１】本発明の一実施例における強誘電体素子の縦断
面図である。FIG. 1 is a longitudinal sectional view of a ferroelectric element according to an embodiment of the present invention.
【図２】下部電極成膜時のスパッタガスの酸素分圧比と
下部電極の密着性の関係を示す。FIG. 2 shows the relationship between the oxygen partial pressure ratio of the sputtering gas and the adhesion of the lower electrode during film formation of the lower electrode.
【図３】本発明の他の実施例における強誘電体素子の縦
断面図である。FIG. 3 is a longitudinal sectional view of a ferroelectric element according to another embodiment of the present invention.
１０ 強誘電体素子 １１ ＭｇＯ単結晶基板 １２ 密着層（Ｐｔ酸素混合層） １３ 下部電極（Ｐｔ膜） １４ 強誘電体膜（ＰＬＴ膜） １５ 上部電極（Ｎｉ−Ｃｒ膜） ２０ 強誘電体素子 ２１ ＭｇＯ単結晶基板 ２３ 下部電極（Ｐｔ膜） ２４ 第１の強誘電体膜（ＰＬＴ膜） ２５ 第２の強誘電体膜（ＰＬＴ膜） ２６ 上部電極（Ｎｉ−Ｃｒ膜） DESCRIPTION OF SYMBOLS 10 Ferroelectric element 11 MgO single crystal substrate 12 Adhesion layer (Pt oxygen mixed layer) 13 Lower electrode (Pt film) 14 Ferroelectric film (PLT film) 15 Upper electrode (Ni-Cr film) 20 Ferroelectric element 21 MgO single crystal substrate 23 Lower electrode (Pt film) 24 First ferroelectric film (PLT film) 25 Second ferroelectric film (PLT film) 26 Upper electrode (Ni-Cr film)
フロントページの続き (72)発明者 神野 伊策 大阪府門真市大字門真1006番地 松下電器 産業株式会社内 (72)発明者 高山 良一 大阪府門真市大字門真1006番地 松下電器 産業株式会社内Continuing from the front page (72) Inventor Iku Jinno 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.
Claims (13)
密着層、下部電極、強誘電体膜、および上部電極を具備
し、前記密着層が前記下部電極を構成する材料と酸素か
らなる強誘電体素子。1. A ferroelectric element comprising: a substrate; and an adhesion layer, a lower electrode, a ferroelectric film, and an upper electrode sequentially arranged on the substrate, wherein the adhesion layer is made of a material constituting the lower electrode and oxygen. Body element.
である請求項１に記載の強誘電体素子。2. The ferroelectric device according to claim 1, wherein the thickness of the adhesion layer is 5 nm or more and 50 nm or less.
結晶構造の酸化物膜を積層した基板である請求項１に記
載の強誘電体素子。3. The ferroelectric element according to claim 1, wherein the substrate is an MgO single crystal substrate or a substrate on which an oxide film having a rock salt type crystal structure is laminated.
Ｏ、ＮｉＯ、およびＣｏＯからなる群より選ばれた少な
くとも一種の膜である請求項３に記載の強誘電体素子。4. An oxide film having a rock salt type crystal structure, wherein
The ferroelectric device according to claim 3, wherein the ferroelectric device is at least one film selected from the group consisting of O, NiO, and CoO.
よびＡｕからなる群より選ばれた少なくとも一種である
請求項１に記載の強誘電体素子。5. The ferroelectric device according to claim 1, wherein the lower electrode material is at least one selected from the group consisting of Pt, Pd, Ir, and Au.
着層上に下部電極を形成する工程、前記下部電極上に強
誘電体膜を形成する工程、および前記強誘電体膜上に上
部電極を形成する工程を有し、前記密着層を形成する工
程が、分圧比２０％以上の酸素を含むアルゴンガス雰囲
気中において下部電極材料をターゲットとしたスパッタ
リング法により行われ、前記密着層上に下部電極を形成
する工程が、前記密着層の形成工程に引き続きアルゴン
ガスのみの雰囲気中において下部電極材料をターゲット
としたスパッタリング法により行われる強誘電体素子の
製造方法。6. A step of forming an adhesion layer on a substrate, a step of forming a lower electrode on the adhesion layer, a step of forming a ferroelectric film on the lower electrode, and a step of forming a ferroelectric film on the ferroelectric film. Forming an electrode, wherein the step of forming the adhesion layer is performed by a sputtering method using a lower electrode material as a target in an argon gas atmosphere containing oxygen having a partial pressure ratio of 20% or more. A method for manufacturing a ferroelectric element, wherein the step of forming a lower electrode is performed by a sputtering method using a lower electrode material as a target in an atmosphere containing only argon gas subsequent to the step of forming the adhesion layer.
とした請求項６に記載の強誘電体素子の製造方法。7. The method for manufacturing a ferroelectric device according to claim 6, wherein the thickness of the adhesion layer is 5 nm or more and 50 nm or less.
下部電極上に強誘電体膜を形成する工程、および前記強
誘電体膜上に上部電極を形成する工程を有し、前記強誘
電体膜を形成する工程が、アルゴンガス雰囲気中におい
て酸化物をターゲットとしたスパッタリング法により強
誘電体膜を形成する工程と、引き続き酸素を含むアルゴ
ンガス雰囲気中において前記酸化物をターゲットとした
スパッタリング法により強誘電体膜を形成する工程から
なる強誘電体素子の製造方法。8. The method according to claim 1, further comprising forming a lower electrode on the substrate, forming a ferroelectric film on the lower electrode, and forming an upper electrode on the ferroelectric film. Forming a ferroelectric film by sputtering using an oxide in an argon gas atmosphere; and sputtering using the oxide in an argon gas atmosphere containing oxygen. A method for manufacturing a ferroelectric element, comprising the step of forming a ferroelectric film by using the method.
体膜の厚みを５ｎｍ以上２０ｎｍ以下とした請求項８に
記載の強誘電体素子の製造方法。9. The method for manufacturing a ferroelectric device according to claim 8, wherein the thickness of the ferroelectric film formed in an argon gas atmosphere is 5 nm or more and 20 nm or less.
塩型結晶構造の酸化物膜を積層した基板である請求項６
または８に記載の強誘電体素子の製造方法。10. The substrate is an MgO single crystal substrate or a substrate on which an oxide film having a rock salt type crystal structure is laminated.
Or the method for manufacturing a ferroelectric element according to 8.
Ｏ、ＮｉＯ、およびＣｏＯからなる群より選ばれた少な
くとも一種の膜である請求項１０に記載の強誘電体素子
の製造方法。11. An oxide film having a rock salt type crystal structure is made of Mg
The method for manufacturing a ferroelectric device according to claim 10, wherein the film is at least one film selected from the group consisting of O, NiO, and CoO.
およびＡｕからなる群より選ばれた少なくとも一種であ
る請求項６または８に記載の強誘電体素子の製造方法。12. The lower electrode material is composed of Pt, Pd, Ir,
9. The method according to claim 6, wherein the ferroelectric element is at least one selected from the group consisting of Au and Au.
基板上に密着層を形成する工程を有する請求項８に記載
の強誘電体素子の製造方法。13. A method for forming a lower electrode, comprising:
The method for manufacturing a ferroelectric device according to claim 8, further comprising a step of forming an adhesion layer on the substrate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31049196A JPH10154834A (en) | 1996-11-21 | 1996-11-21 | Ferroelectric element and manufacture thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31049196A JPH10154834A (en) | 1996-11-21 | 1996-11-21 | Ferroelectric element and manufacture thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10154834A true JPH10154834A (en) | 1998-06-09 |
Family
ID=18005876
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31049196A Pending JPH10154834A (en) | 1996-11-21 | 1996-11-21 | Ferroelectric element and manufacture thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10154834A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002027809A1 (en) * | 2000-09-27 | 2002-04-04 | Matsushita Electric Industrial Co., Ltd. | Dielectric thin film element, actuator comprising it, ink jet head, and ink jet recorder. |
| US6604431B1 (en) | 1999-09-29 | 2003-08-12 | International Business Machines Corporation | Apparatus and method for fixing and checking connections of piezoelectric sensor, actuator, and disk unit |
| JP2011203169A (en) * | 2010-03-26 | 2011-10-13 | Seiko Epson Corp | Thermal photodetector, thermal photodetection device, and electronic instrument |
| US9892950B2 (en) | 2011-10-11 | 2018-02-13 | Ngk Insulators, Ltd. | Ceramic member, member for semiconductor manufacturing apparatus, and method for manufacturing ceramic member |
-
1996
- 1996-11-21 JP JP31049196A patent/JPH10154834A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6604431B1 (en) | 1999-09-29 | 2003-08-12 | International Business Machines Corporation | Apparatus and method for fixing and checking connections of piezoelectric sensor, actuator, and disk unit |
| WO2002027809A1 (en) * | 2000-09-27 | 2002-04-04 | Matsushita Electric Industrial Co., Ltd. | Dielectric thin film element, actuator comprising it, ink jet head, and ink jet recorder. |
| JP2011203169A (en) * | 2010-03-26 | 2011-10-13 | Seiko Epson Corp | Thermal photodetector, thermal photodetection device, and electronic instrument |
| US9892950B2 (en) | 2011-10-11 | 2018-02-13 | Ngk Insulators, Ltd. | Ceramic member, member for semiconductor manufacturing apparatus, and method for manufacturing ceramic member |
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