JP2003077677A - Thin film el element and manufacturing method therefor - Google Patents
Thin film el element and manufacturing method thereforInfo
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- JP2003077677A JP2003077677A JP2001261653A JP2001261653A JP2003077677A JP 2003077677 A JP2003077677 A JP 2003077677A JP 2001261653 A JP2001261653 A JP 2001261653A JP 2001261653 A JP2001261653 A JP 2001261653A JP 2003077677 A JP2003077677 A JP 2003077677A
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- film
- dielectric film
- dielectric
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、表示装置等に用いられ
る発光素子に関するものであり、さらに詳しくは、交流
電圧を印加することにより、ＥＬ（Electro luminescen
ce）発光が得られる薄膜ＥＬ素子に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting element used in a display device or the like, and more specifically, it applies to an EL (Electro luminescen) by applying an AC voltage.
ce) The present invention relates to a thin film EL device capable of emitting light.
【０００２】[0002]
【従来の技術】交流電圧を印加するとＥＬ発光が得られ
る薄膜ＥＬ素子は、図７に示されるように、例えば、基
板２１上に、下部電極２２、酸化シリコン膜２４及び窒
化シリコン膜２５（下部絶縁層）、発光層２６、窒化シ
リコン膜２７及び酸化シリコン膜２８（上部絶縁層）、
上部電極２９とをこの順で積層してなるものである。2. Description of the Related Art As shown in FIG. 7, a thin-film EL device that emits EL light when an AC voltage is applied is, for example, on a substrate 21, a lower electrode 22, a silicon oxide film 24 and a silicon nitride film 25 (lower part). Insulating layer), light emitting layer 26, silicon nitride film 27 and silicon oxide film 28 (upper insulating layer),
The upper electrode 29 and the upper electrode 29 are laminated in this order.
【０００３】発光層を構成する材料としては、通常、硫
化亜鉛や硫化ストロンチウム等の硫化物が用いられてい
る。具体的には、表示パネルとして商品化されている薄
膜ＥＬ素子には、発光層として、硫化亜鉛にマンガンを
微量添加した蛍光体が用いられており、これにより黄橙
色発光が得られている。また、発光層として、硫化亜鉛
にテルビウムを付活した蛍光体も用いられており、これ
により緑色発光が得られている。As a material for forming the light emitting layer, sulfides such as zinc sulfide and strontium sulfide are usually used. Specifically, in a thin film EL element commercialized as a display panel, a phosphor obtained by adding a small amount of manganese to zinc sulfide is used as a light emitting layer, whereby yellow-orange emission is obtained. In addition, a phosphor obtained by activating terbium in zinc sulfide is also used as the light emitting layer, whereby green light emission is obtained.
【０００４】絶縁層を構成する材料としては、通常、酸
化シリコン、窒化シリコン、酸化タンタル等の誘電体が
用いられている。しかしながら、これらの誘電体は、比
誘電率が低く、それぞれ２０、４、７．５程度である。
このため、例えば発光層に比誘電率８程度の硫化亜鉛を
用いた場合、大きい電圧が絶縁層に掛かってしまい、
（発光層のクランプ電界×発光層の膜厚）よりも非常に
高い閾値電圧が発光に必要となる。その結果、高価な高
耐圧ＩＣドライバが必要となる。また、発光開始後の無
機ＥＬの発光輝度Ｌは、理論上、次の式（１）：As a material for forming the insulating layer, a dielectric such as silicon oxide, silicon nitride or tantalum oxide is usually used. However, these dielectrics have low relative dielectric constants of about 20, 4, and 7.5, respectively.
Therefore, for example, when zinc sulfide having a relative dielectric constant of about 8 is used for the light emitting layer, a large voltage is applied to the insulating layer,
A threshold voltage much higher than (clamping electric field of light emitting layer × film thickness of light emitting layer) is required for light emission. As a result, an expensive high voltage IC driver is required. Further, the light emission luminance L of the inorganic EL after the start of light emission is theoretically expressed by the following formula (1):
【０００５】
Ｌ∝η・Ｅｃ・ｄｚ・Ｃｉ・φ・Ｖｍ （１）
（ここで、ηは発光効率、Ｅｃは発光層のクランプ電
界、ｄｚは発光層の膜厚、Ｃｉは絶縁層の容量、φは駆
動周波数、Ｖｍは変調電圧である）で表される。このこ
とから分かるように、絶縁層の誘電率が低いとＣｉが低
くなり、高輝度が得られないという問題があった。L∝η · Ec · dz · Ci · φ · Vm (1) (where η is the luminous efficiency, Ec is the clamp electric field of the light emitting layer, dz is the thickness of the light emitting layer, and Ci is the capacitance of the insulating layer. , Φ is a drive frequency, and Vm is a modulation voltage). As can be seen from this, when the dielectric constant of the insulating layer is low, Ci is low, and there is a problem that high brightness cannot be obtained.
【０００６】これに対して、高い誘電率を有する強誘電
体を薄膜ＥＬ素子の絶縁層に用いる試みが行われてい
る。例えば、特開平８−８３６８６号公報では、比誘電
率が５００〜１０００程度のチタン酸ジルコン酸鉛薄膜
を絶縁層に用いた硫化亜鉛系発光素子が開示されてい
る。また、Y. Fujitaらの、Proc. SID 25/3（1984）P.
177によれば、比誘電率が１００〜２００程度のチタン
酸ストロンチウムを主成分とする絶縁層を用いることが
開示されている。On the other hand, attempts have been made to use a ferroelectric material having a high dielectric constant as an insulating layer of a thin film EL element. For example, Japanese Patent Application Laid-Open No. 8-83686 discloses a zinc sulfide-based light emitting device using a lead zirconate titanate thin film having a relative dielectric constant of about 500 to 1000 as an insulating layer. Also, Y. Fujita et al., Proc. SID 25/3 (1984) P.
177 discloses that an insulating layer containing strontium titanate as a main component and having a relative dielectric constant of about 100 to 200 is used.
【０００７】[0007]
【発明が解決しようとする課題】しかしながら、これら
の強誘電体は絶縁破壊耐圧（電界値）が低いという問題
がある。具体的には、チタン酸ジルコン酸鉛の絶縁破壊
耐圧は０．５〜１ＭＶ／ｃｍ程度で、チタン酸ストロン
チウムのそれは２〜３ＭＶ／ｃｍ程度であり、酸化シリ
コンや窒化シリコンの絶縁破壊耐圧（６〜８ＭＶ／ｃ
ｍ）よりも低く、薄膜ＥＬ素子に用いた場合には信頼性
がないという問題があった。なお、絶縁破壊耐圧は、絶
縁膜の膜厚が厚くなるにつれ減少する傾向にあるため、
これにより電圧の絶対値を上げることは難しい。また、
膜厚が厚くなると、クラック等が発生しやすく、また生
産コストが増加することにより実用的ではない。However, these ferroelectrics have a problem of low dielectric breakdown voltage (electric field value). Specifically, the breakdown voltage of lead zirconate titanate is about 0.5 to 1 MV / cm, that of strontium titanate is about 2 to 3 MV / cm, and the breakdown voltage of silicon oxide or silicon nitride (6 ~ 8MV / c
m), which is unreliable when used in a thin film EL device. Since the breakdown voltage tends to decrease as the thickness of the insulating film increases,
This makes it difficult to increase the absolute value of the voltage. Also,
When the film thickness is thick, cracks and the like are likely to occur, and the production cost increases, which is not practical.
【０００８】また、鉛を含まないチタン酸ストロンチウ
ムや、チタン酸バリウム等の薄膜材料は、緻密な結晶質
膜を得るために、例えばスパッタ法では堆積速度を低く
しなければならず、化学溶液堆積法や有機金属気相成長
法では成膜条件が限定されてしまい製造工程が煩雑であ
る。例えば、化学溶液堆積法によれば、先ず前駆体膜を
形成し、次いで熱処理を繰返し、膜厚数十ｎｍ程度の非
常に薄い膜を重ねていかなければならないといった条件
が必要となり、生産性が低く、量産化が困難であった。Thin film materials such as lead-free strontium titanate and barium titanate must be deposited by chemical solution deposition in order to obtain a dense crystalline film, for example, by sputtering. Method and metal organic chemical vapor deposition method, the film forming conditions are limited and the manufacturing process is complicated. For example, according to the chemical solution deposition method, a precursor film is formed first, and then heat treatment is repeated, so that a very thin film having a thickness of several tens of nm must be stacked, which results in high productivity. It was low and mass production was difficult.
【０００９】これに対して、特開平１−１２４９９８号
公報では、絶縁破壊耐圧が２ＭＶ／ｃｍ程度のチタン酸
ストロンチウム（膜厚５００ｎｍ）上に、酸化タンタル
を膜厚５０〜２５０ｎｍ程度に積層することで、素子の
耐圧を上昇させることが報告されている。特に、酸化タ
ンタルを膜厚１００ｎｍ程度にすると、絶縁破壊耐圧が
最高４ＭＶ／ｃｍ(２４０Ｖ)にまで上昇することが報告
されている。しかしながら、このような方法では、絶縁
層の比誘電率が５０程度まで低下し、発光輝度が低下す
るため、高誘電体を絶縁層に用いるメリットが少なくな
る。On the other hand, in Japanese Patent Application Laid-Open No. 1-124998, tantalum oxide is laminated to a film thickness of about 50 to 250 nm on strontium titanate (film thickness 500 nm) having a breakdown voltage of about 2 MV / cm. It has been reported that the breakdown voltage of the device is increased. In particular, it has been reported that when the film thickness of tantalum oxide is about 100 nm, the dielectric breakdown voltage rises up to 4 MV / cm (240 V). However, in such a method, the relative permittivity of the insulating layer is reduced to about 50 and the emission luminance is reduced, so that the merit of using a high dielectric material for the insulating layer is reduced.
【００１０】また、硫化物系材料を発光層として用いる
薄膜ＥＬ素子の絶縁層として、チタン酸ジルコン酸鉛を
用いた場合、発光層形成後の熱処理時にチタン酸ジルコ
ン酸鉛の鉛分が発光層の硫黄成分と反応しやすくなる。
その結果、素子が変色してしまい、絶縁破壊が起こりや
すくなる。このことは、一般に広く用いられているガラ
ス基板等の低耐熱基板に、チタン酸ジルコン酸鉛を形成
する際に、低温でその結晶性、緻密性を向上させるた
め、鉛を化学量論比よりも過剰に仕込まなくてはなら
ず、その過剰な鉛分が揮発することによるものと考えら
れる。また、発光層にチタン酸ジルコン酸鉛のような複
合金属酸化物が接触すると、高電圧駆動中にメタルイオ
ンの拡散や発光層の酸化が起こるという問題もある。Further, when lead zirconate titanate is used as an insulating layer of a thin film EL device using a sulfide-based material as a light emitting layer, the lead content of lead zirconate titanate during the heat treatment after the formation of the light emitting layer is the light emitting layer. It becomes easy to react with the sulfur component of.
As a result, the element is discolored and dielectric breakdown easily occurs. This means that when lead zirconate titanate is formed on a low heat-resistant substrate such as a glass substrate that is widely used in general, the crystallinity and density of lead zirconate are improved at low temperatures. It is thought that this is due to the excess lead volatilizing. Further, when a composite metal oxide such as lead zirconate titanate comes into contact with the light emitting layer, there is a problem that metal ions are diffused and the light emitting layer is oxidized during high voltage driving.
【００１１】これに対して、特開平７−４５３６８号公
報では、発光層とチタン酸ストロンチウムとの反応防止
層として、窒化シリコンを用いることが提案されている
が、チタン酸ジルコン酸鉛を用いた素子に関しては、チ
タン酸ジルコン酸鉛と窒化シリコンとが剥離しやすいと
いう問題がある。上記の問題に鑑みて、本発明は、特定
の材料からなる３層以上の誘電体薄膜を絶縁層に使用し
た薄膜ＥＬ素子が、上記問題を解決することを見出し、
本発明を完成するに至った。On the other hand, JP-A-7-45368 proposes to use silicon nitride as a reaction preventing layer between the light emitting layer and strontium titanate, but lead zirconate titanate was used. Regarding the element, there is a problem that lead zirconate titanate and silicon nitride are easily separated. In view of the above problems, the present invention has found that a thin film EL device using three or more dielectric thin films made of a specific material as an insulating layer solves the above problems,
The present invention has been completed.
【００１２】[0012]
【課題を解決するための手段】かくして、本発明によれ
ば、基板上に、下部電極、下部絶縁層、発光層、上部絶
縁層、上部電極をこの順で構成してなる薄膜ＥＬ素子に
おいて、下部絶縁層及び上部絶縁層の両方又はいずれか
一方が、少なくとも、チタン酸ジルコン酸鉛を主成分と
する第一誘電体膜と、チタン酸バリウム若しくは酸化チ
タンを主成分とする第二誘電体膜と、窒化シリコン若し
くは酸窒化シリコンを主成分とする第三誘電体膜とをこ
の順に積層したものであることを特徴とする薄膜ＥＬ素
子が提供される。Thus, according to the present invention, in a thin film EL element comprising a substrate, a lower electrode, a lower insulating layer, a light emitting layer, an upper insulating layer, and an upper electrode in this order, At least one of the lower insulating layer and / or the upper insulating layer is at least a first dielectric film containing lead zirconate titanate as a main component and a second dielectric film containing barium titanate or titanium oxide as a main component. And a third dielectric film containing silicon nitride or silicon oxynitride as a main component, which are laminated in this order.
【００１３】この薄膜ＥＬ素子では、第一誘電体膜に、
低温で形成しても緻密性、比誘電率が高く、比較的低誘
電損失なチタン酸ジルコン酸鉛を主成分とする薄膜を用
い、第二誘電体膜に、低温で形成すると緻密化しづら
く、リーキーで誘電損失が高いチタン酸バリウム若しく
は酸化チタンを主成分とする薄膜を用い、第三の誘電体
膜に、低温で形成しても高耐圧、低誘電損失な窒化シリ
コン若しくは酸窒化シリコンを主成分とする薄膜を用い
ている。これらの誘電体膜を積層すると、高耐圧、高容
量な絶縁層が得られ、この絶縁層を用いた薄膜ＥＬ素子
は高輝度が得られる。In this thin film EL element, the first dielectric film is
Even if formed at low temperature, it is difficult to densify when formed at low temperature in the second dielectric film by using a thin film containing lead zirconate titanate as a main component, which has high density and high relative dielectric constant and relatively low dielectric loss. A thin film containing barium titanate or titanium oxide as a main component that is leaky and has a high dielectric loss, and is mainly composed of silicon nitride or silicon oxynitride that has a high withstand voltage and low dielectric loss even when formed at a low temperature as the third dielectric film. A thin film as a component is used. When these dielectric films are laminated, a high breakdown voltage and high capacity insulating layer is obtained, and a thin film EL element using this insulating layer can obtain high brightness.
【００１４】また、本発明によれば、予め下部電極が形
成された基板上に、チタン酸ジルコン酸鉛を主成分とし
た非晶質の第一誘電体膜の前駆体膜を成膜し、第一誘電
体膜の前駆体膜上に酸化チタンを主成分とした非晶質の
第二誘電体膜の前駆体膜を成膜し、チタン酸ジルコン酸
鉛の結晶化温度以上に熱処理して第一誘電体膜及び第二
誘電体膜を形成することを特徴とする上記の薄膜ＥＬ素
子の製造方法が提供される。According to the present invention, a precursor film of an amorphous first dielectric film containing lead zirconate titanate as a main component is formed on a substrate on which a lower electrode is formed in advance. An amorphous second dielectric film precursor film containing titanium oxide as a main component is formed on the precursor film of the first dielectric film, and heat-treated at a temperature above the crystallization temperature of lead zirconate titanate. There is provided a method for manufacturing a thin film EL device as described above, which comprises forming a first dielectric film and a second dielectric film.
【００１５】この製造方法によれば、第一誘電体膜の余
分な鉛分の多くが酸化チタンと反応して安定化し、素子
の変色を防止することができる。According to this manufacturing method, most of the excess lead content of the first dielectric film reacts with titanium oxide and is stabilized, and discoloration of the device can be prevented.
【００１６】[0016]
【発明の実施の形態】以下、本発明を実施の形態に基づ
き、図面を参照しながら詳しく説明するが、これにより
本発明が限定されることはない。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail based on embodiments with reference to the drawings, but the present invention is not limited thereto.
【００１７】実施形態１
図１に本実施形態の薄膜ＥＬ素子の概略断面図を示す。
図１の薄膜ＥＬ素子は、基板１上に、下部電極２、第一
誘電体膜３、第二誘電体膜４、第三誘電体膜５、発光層
６、窒化シリコン膜７、酸化シリコン膜８、上部電極９
がこの順で積層されてなる。なお、下部絶縁層は、第一
誘電体膜３、第二誘電体膜４及び第三誘電体膜５からな
り、上部絶縁層は、窒化シリコン膜７及び酸化シリコン
膜８からなる。Embodiment 1 FIG. 1 shows a schematic sectional view of a thin film EL element of this embodiment.
1 includes a lower electrode 2, a first dielectric film 3, a second dielectric film 4, a third dielectric film 5, a light emitting layer 6, a silicon nitride film 7, and a silicon oxide film on a substrate 1. 8, upper electrode 9
Are laminated in this order. The lower insulating layer is composed of the first dielectric film 3, the second dielectric film 4 and the third dielectric film 5, and the upper insulating layer is composed of the silicon nitride film 7 and the silicon oxide film 8.
【００１８】以下、この薄膜ＥＬ素子の製造方法を説明
する。例えば、ガラス基板１上に、酸化インジウム錫
（ＩＴＯ）を、スパッタ法等の公知の方法により膜厚２
００ｎｍに形成し、フォトリソグラフィ法でパターニン
グすることにより下部電極２を形成する。なお、基板１
としては、薄膜ＥＬ素子の基板として通常用いられてい
る透明で６００℃程度の耐熱性があれば特に限定され
ず、ガラスもしくは石英等が挙げられる。The method of manufacturing this thin film EL element will be described below. For example, indium tin oxide (ITO) having a film thickness of 2 is formed on the glass substrate 1 by a known method such as a sputtering method.
Then, the lower electrode 2 is formed by patterning with a thickness of 00 nm and patterning with a photolithography method. The substrate 1
There is no particular limitation as long as it is transparent and has a heat resistance of about 600 ° C. which is usually used as a substrate of a thin film EL element, and examples thereof include glass and quartz.
【００１９】また、下部電極２としては、多くの場合、
透明導電膜が用いられている。一般的な薄膜ＥＬ素子に
おいては、透明導電膜としてＩＴＯ、酸化錫、ＩＤＩＸ
Ｏ（Ｉｎ2Ｏ3−ＺｎＯ系材料）等が用いられる。中でも
ＩＴＯは、光透過性、ファインパタン加工性、低抵抗率
に優れており、液晶表示パネル等において広く用いられ
ており、公知のフォトリソグラフィ法を用いることでフ
ァインパタンを形成することが可能であるので好まし
い。下部電極２の形成方法は、公知の方法、例えばスパ
ッタ法、抵抗加熱蒸着法、電子ビーム法、スプレー法等
により成膜することができる。下部電極２の膜厚は、特
に限定されないが、通常、１５０〜２５０ｎｍ程度であ
る。In many cases, the lower electrode 2 is
A transparent conductive film is used. In general thin film EL devices, ITO, tin oxide, IDIX are used as transparent conductive films.
O (In 2 O 3 -ZnO-based material) is used. Among them, ITO is excellent in light transmission, fine pattern processability, and low resistivity, and is widely used in liquid crystal display panels and the like, and it is possible to form fine patterns by using a known photolithography method. It is preferable because it exists. The lower electrode 2 can be formed by a known method such as a sputtering method, a resistance heating vapor deposition method, an electron beam method, or a spray method. The thickness of the lower electrode 2 is not particularly limited, but is usually about 150 to 250 nm.
【００２０】次に、下部電極２を含むガラス基板１上
に、化学溶液堆積法により、チタン酸ジルコン酸鉛膜
（ＰＺＴ）（第一誘電体膜３）を形成する。具体的に
は、鉛、ジルコン、チタンのアルコキシド若しくは有機
金属塩を主成分とし、少量のランタンを含む溶液を反応
させたものを用いた。なお、ランタンの添加は本発明を
限定するものではなく、無添加でもよい。また、ストロ
ンチウム、バリウム、カルシウム、錫、アルミニウム、
ニオブなど他の元素を添加してもよい。これら成分の構
成比は、適宜調節され、特に限定されるものではない
が、チタン酸ジルコン酸鉛の結晶化温度が低減可能であ
ることから、鉛を多く含むのが好ましい。なお、本実施
形態では、各成分の構成比を、鉛：ランタン：ジルコ
ン：チタン＝１．２：０．０５：０．４：０．６とする
（本実施形態では、鉛を化学量論比よりも２０％過剰に
含む。なお、ランタンが全て置換されると仮定した場
合、鉛を化学量論比よりも２５％過剰に含ませる）。Next, a lead zirconate titanate film (PZT) (first dielectric film 3) is formed on the glass substrate 1 including the lower electrode 2 by a chemical solution deposition method. Specifically, a solution was used in which a solution containing lead, zircon, titanium alkoxide or an organic metal salt as a main component and a small amount of lanthanum was reacted. It should be noted that addition of lanthanum does not limit the present invention and may be added without addition. Also, strontium, barium, calcium, tin, aluminum,
Other elements such as niobium may be added. The composition ratio of these components is appropriately adjusted and is not particularly limited, but it is preferable to contain a large amount of lead because the crystallization temperature of lead zirconate titanate can be reduced. In the present embodiment, the composition ratio of each component is set to lead: lanthanum: zircon: titanium = 1.2: 0.05: 0.4: 0.6 (in the present embodiment, lead is stoichiometric). 20% excess over the ratio, and assuming that all the lanthanum is replaced, lead is included over the stoichiometric ratio by 25%).
【００２１】この化学溶液をガラス基板１上に塗布し、
１００℃程度で乾燥して溶媒を除去し、３５０℃程度で
仮焼成して残留有機物を除去し、チタン酸ジルコン酸鉛
の結晶化温度以上の温度（本実施形態では６００℃以
上）で結晶化焼成を施すことにより、チタン酸ジルコン
酸鉛膜（第一誘電体膜３）を形成する。なお、この第一
誘電体膜３は、膜厚が２８０ｎｍ、比誘電率が３３６、
誘電損失が１．８％である。This chemical solution is applied on the glass substrate 1,
The solvent is removed by drying at about 100 ° C., the residual organic matter is removed by calcination at about 350 ° C., and crystallization is performed at a temperature above the crystallization temperature of lead zirconate titanate (600 ° C. or above in this embodiment). By firing, a lead zirconate titanate film (first dielectric film 3) is formed. The first dielectric film 3 has a film thickness of 280 nm, a relative dielectric constant of 336,
The dielectric loss is 1.8%.
【００２２】第一誘電体膜３の膜厚は、特に限定されな
いが、化学溶液堆積法で一回の塗布工程で得られて生産
性がよいこと等から、２００〜３００ｎｍ程度が好まし
く、さらには、再現性のよい特性が得られることから、
２２０〜２６０ｎｍ程度がより好ましい。第一誘電体膜
３の膜厚が２００ｎｍを下回ると、素子破壊電圧が低く
なり、逆に膜厚が３００ｎｍを上回ると、クラックがで
きやすく、疎で素子破壊電界が低くなるので好ましくな
い。The thickness of the first dielectric film 3 is not particularly limited, but is preferably about 200 to 300 nm, and more preferably about 200 to 300 nm, since it can be obtained by a single coating step by the chemical solution deposition method and the productivity is good. , Because reproducible characteristics are obtained,
It is more preferably about 220 to 260 nm. When the film thickness of the first dielectric film 3 is less than 200 nm, the element breakdown voltage is low, and conversely, when the film thickness is more than 300 nm, cracks are likely to occur and the element breakdown electric field is low, which is not preferable.
【００２３】次に、第一誘電体膜３上に、バリウム、チ
タンのアルコキシド若しくは有機金属塩を主成分とした
溶液を反応させたものを用いて、化学溶液堆積法により
チタン酸バリウム膜（ＢＴＯ）（第二誘電体膜４）を膜
厚３００ｎｍ程度に形成する。具体的には、構成比を
（バリウム：チタン＝７：３）とした上記化学溶液を第
一誘電体膜３上に塗布し、１００℃程度で乾燥して溶媒
を除去し、３５０℃程度で仮焼成して残留有機物を除去
し、チタン酸バリウムの結晶化温度以上の温度（本実施
形態では６００℃以上）で結晶化焼成を施すことによ
り、チタン酸バリウム膜（第二誘電体膜４）を形成す
る。Next, a barium titanate film (BTO titanate film (BTO) is formed on the first dielectric film 3 by a chemical solution deposition method using a reaction product of a solution containing barium, an alkoxide of titanium, or an organic metal salt as a main component. ) (Second dielectric film 4) is formed to a film thickness of about 300 nm. Specifically, the above chemical solution having a composition ratio of (barium: titanium = 7: 3) is applied on the first dielectric film 3 and dried at about 100 ° C. to remove the solvent, and at about 350 ° C. By calcination to remove residual organic substances, and crystallization and calcination at a temperature above the crystallization temperature of barium titanate (600 ° C. or above in this embodiment), the barium titanate film (second dielectric film 4) is obtained. To form.
【００２４】第二誘電体膜４の膜厚は、特に限定されな
いが、化学溶液堆積法で一回若しくは二回の塗布工程で
得られて生産性がよいこと等から、１５０〜３５０ｎｍ
程度が好ましく、さらには、再現性のよい特性が得られ
ることから、２００〜３００ｎｍ程度がより好ましい。
第二誘電体膜４の膜厚が１５０ｎｍを下回ると、発光層
６の熱処理時に第一誘電体膜３から揮発する鉛分の拡散
を防ぐのが不充分であり、素子が黒色化しやすいので好
ましくない。逆に膜厚が３５０ｎｍを上回ると、クラッ
クが発生しやすく、安定な素子を作製するのが難しいの
で好ましくない。The thickness of the second dielectric film 4 is not particularly limited, but is 150 to 350 nm because it is obtained by a chemical solution deposition method in one or two coating steps and has good productivity.
The range is preferably about 200 to 300 nm, since the characteristics are preferably reproducible.
When the thickness of the second dielectric film 4 is less than 150 nm, it is insufficient to prevent the diffusion of lead volatilized from the first dielectric film 3 during the heat treatment of the light emitting layer 6, and the element is easily blackened, which is preferable. Absent. On the contrary, if the film thickness exceeds 350 nm, cracks are likely to occur and it is difficult to manufacture a stable element, which is not preferable.
【００２５】なお、本実施形態では、第二誘電体膜４と
してチタン酸バリウムを用いたが、第二誘電体膜４は、
主成分がバリウム、チタン、酸素の結晶質膜であればよ
く、例えばストロンチウムやカルシウム、ジルコニウ
ム、錫、アルミニオブ、ニオブなどをさらに添加したも
のであってもよい。In the present embodiment, barium titanate is used as the second dielectric film 4, but the second dielectric film 4 is
Any crystalline film containing barium, titanium, or oxygen as a main component may be used, and for example, strontium, calcium, zirconium, tin, aluminium, niobium, or the like may be further added.
【００２６】第一、第二誘電体膜の積層膜は、比誘電率
が３８７、誘電損失が８％である。また、第二誘電体膜
４の下部電極２上での単膜特性は、リーク電流が非常に
高く、正確な値が得られないため測定できない。なお、
上記第一誘電体膜３及び第二誘電体膜４は、化学溶液堆
積法以外の方法で形成することもでき、例えばスパッタ
法やＭＯＣＶＤ法などの気相成長法で形成することもで
きる。The laminated film of the first and second dielectric films has a relative dielectric constant of 387 and a dielectric loss of 8%. Further, the single film characteristic of the second dielectric film 4 on the lower electrode 2 cannot be measured because the leak current is very high and an accurate value cannot be obtained. In addition,
The first dielectric film 3 and the second dielectric film 4 may be formed by a method other than the chemical solution deposition method, for example, a vapor phase growth method such as a sputtering method or a MOCVD method.
【００２７】次に、第二誘電体膜４上に、反応性スパッ
タ法により、基板温度２００℃程度にして窒化シリコン
膜（ＳｉＮｘ）（第三誘電体膜５）を５０ｎｍ程度に形
成する。なお、第三誘電体膜５を構成する材料として
は、窒化シリコン又は酸窒化シリコンを主成分とするも
のが挙げられる。Next, a silicon nitride film (SiNx) (third dielectric film 5) is formed on the second dielectric film 4 at a substrate temperature of about 200 ° C. to a thickness of about 50 nm by a reactive sputtering method. As a material forming the third dielectric film 5, a material containing silicon nitride or silicon oxynitride as a main component can be used.
【００２８】第三誘電体膜５の膜厚は、特に限定されな
いが、長期信頼性が確保でき、第一、第二誘電体膜の特
性を生かせるなどの理由から、４０〜１００ｎｍ程度が
好ましく、さらには、高安定で、発光効率及び輝度の高
いものが得られるという点で、５０〜８０ｎｍ程度がよ
り好ましい。第三誘電体膜５の膜厚が４０ｎｍを下回る
と、高電界で素子駆動中に第一、第二誘電体膜から拡散
するメタルイオンが発光層６に進入して、輝度が低下す
るので好ましくない。逆に膜厚が１００ｎｍを上回る
と、素子耐圧は高くなるが積層膜の容量が大幅に低下
し、高誘電体材料を使用する利点が少なくなるので好ま
しくない。The thickness of the third dielectric film 5 is not particularly limited, but is preferably about 40 to 100 nm for the reason that long-term reliability can be secured and the characteristics of the first and second dielectric films can be utilized. Further, about 50 to 80 nm is more preferable from the viewpoint that a highly stable, high luminous efficiency and high luminance can be obtained. When the film thickness of the third dielectric film 5 is less than 40 nm, metal ions diffused from the first and second dielectric films enter the light emitting layer 6 during driving of the device under a high electric field, and the brightness is reduced, which is preferable. Absent. On the other hand, if the film thickness exceeds 100 nm, the element breakdown voltage increases, but the capacitance of the laminated film decreases significantly, and the advantage of using a high dielectric material decreases, which is not preferable.
【００２９】第一、第二、第三誘電体膜の積層膜は、比
誘電率が１２２、誘電損失が１．５％である。また、第
三誘電体膜５の下部電極２上での単膜特性は、比誘電率
が７．５、誘電損失が１％以下である。The laminated film of the first, second and third dielectric films has a relative dielectric constant of 122 and a dielectric loss of 1.5%. The single film characteristics of the third dielectric film 5 on the lower electrode 2 are a relative dielectric constant of 7.5 and a dielectric loss of 1% or less.
【００３０】これら誘電体膜の単膜及び積層膜の電流密
度と印加電圧との関係を表わすグラフを図２に示す。こ
のグラフから、第一誘電体膜３（ＰＺＴ）、第二誘電体
膜４（ＢＴＯ）、第三誘電体膜５（ＳｉＮｘ）の単膜
は、耐圧値がそれぞれ２５Ｖ、５Ｖ、２６Ｖ程度である
ことが分かる。第一誘電体膜３と第二誘電体膜４との積
層膜では、リーク電流密度は高くなり、耐圧は１２５Ｖ
まで増加する。第一誘電体膜３と第二誘電体膜４と第三
誘電体膜５との積層膜では、耐圧は２００Ｖ以上まで増
加することが分かった。また、積層膜であるため、ピン
ホールにも強い。FIG. 2 is a graph showing the relationship between the current density and the applied voltage of the single film and the laminated film of these dielectric films. From this graph, the withstand voltage values of the single films of the first dielectric film 3 (PZT), the second dielectric film 4 (BTO), and the third dielectric film 5 (SiNx) are about 25V, 5V, and 26V, respectively. I understand. In the laminated film of the first dielectric film 3 and the second dielectric film 4, the leak current density is high and the breakdown voltage is 125V.
To increase. It was found that the withstand voltage of the laminated film of the first dielectric film 3, the second dielectric film 4, and the third dielectric film 5 increased to 200 V or more. Further, since it is a laminated film, it is strong against pinholes.
【００３１】下部絶縁層は、本発明の効果を妨げるもの
でなければ、さらに公知の誘電体膜又は絶縁体膜が積層
されたものであってもよい。The lower insulating layer may be formed by further laminating a known dielectric film or insulating film as long as it does not impair the effects of the present invention.
【００３２】次に、第三誘電体膜５上に、マンガンを付
活した硫化亜鉛を真空蒸着法により膜厚６００ｎｍに成
膜して硫化亜鉛膜（発光層６）形成する。なお、発光層
を構成する材料としては、通常、無機ＥＬ素子に用いら
れるものであれば特に限定されないが、例えば、硫化亜
鉛、硫化ストロンチウム、硫化カルシウム、ＣａＧａ2
Ｓ4、ＳｒＧａ2Ｓ4等が挙げられる。また、これらの材
料には、通常、Ｍｎ、ＰｒＦ3、ＴｂＦ3、ＳｍＦ3、Ｔ
ｂＦ3、ＤｙＦ3、ＨｏＦ3、ＥｒＦ3、ＴｍＦ3、ＹｂＦ3
等の発光中心が付活される。これらの発光中心は、所望
の発光色に合わせて適宜選択される。発光層の膜厚は、
特に限定されないが、通常、５００〜１５００ｎｍ程度
である。発光層の形成方法は、公知の手法、例えばスパ
ッタ法、抵抗加熱蒸着法、電子ビーム法、スプレー法等
により成膜することができる。Next, a zinc sulfide film (light emitting layer 6) is formed on the third dielectric film 5 by vacuum evaporation of zinc sulfide to a thickness of 600 nm. The material forming the light emitting layer is not particularly limited as long as it is usually used for an inorganic EL element. For example, zinc sulfide, strontium sulfide, calcium sulfide, CaGa 2
S 4 , SrGa 2 S 4 and the like can be mentioned. In addition, these materials are usually Mn, PrF 3 , TbF 3 , SmF 3 and T.
bF 3 , DyF 3 , HoF 3 , ErF 3 , TmF 3 , YbF 3
The luminescence center such as is activated. These emission centers are appropriately selected according to the desired emission color. The thickness of the light emitting layer is
Although not particularly limited, it is usually about 500 to 1500 nm. The light emitting layer can be formed by a known method such as a sputtering method, a resistance heating vapor deposition method, an electron beam method or a spray method.
【００３３】次に、発光層６上に、スパッタ法により、
窒化シリコン膜７及び酸化シリコン膜８をこの順で成膜
して上部絶縁層を形成する。窒化シリコン膜７及び酸化
シリコン膜８の膜厚は、それぞれ５０ｎｍにする。Next, on the light emitting layer 6, by a sputtering method,
A silicon nitride film 7 and a silicon oxide film 8 are formed in this order to form an upper insulating layer. The thickness of each of the silicon nitride film 7 and the silicon oxide film 8 is 50 nm.
【００３４】なお、上部絶縁層には、窒化シリコン又は
酸化シリコンの他に、酸化タンタルやＰｂＴｉＯ3など
の高誘電体を用いてもよい。また、チタン酸ジルコン酸
鉛を主成分とする第一誘電体膜と、チタン酸バリウム若
しくは酸化チタンを主成分とする第二誘電体膜と、窒化
シリコン若しくは酸窒化シリコンを主成分とする第三誘
電体膜とをこの順に積層したものであってもよい。この
ように上部絶縁層及び下部絶縁層を特定の材料からなる
３層の積層誘電体膜にすると、さらに発光輝度を高くす
ることができる。上部絶縁層の膜厚は、特に限定されな
いが、通常、７０〜１５０ｎｍ程度である。In addition to silicon nitride or silicon oxide, a high dielectric material such as tantalum oxide or PbTiO 3 may be used for the upper insulating layer. Also, a first dielectric film containing lead zirconate titanate as a main component, a second dielectric film containing barium titanate or titanium oxide as a main component, and a third dielectric film containing silicon nitride or silicon oxynitride as a main component. The dielectric film may be laminated in this order. When the upper insulating layer and the lower insulating layer are each formed of a three-layer laminated dielectric film made of a specific material as described above, the emission brightness can be further increased. The thickness of the upper insulating layer is not particularly limited, but is usually about 70 to 150 nm.
【００３５】次に、発光層６の結晶性を向上させるため
に、得られた積層膜を、不活性ガス中、６３０℃で１時
間熱処理を行う。ここで、第二誘電体膜４及び／又は第
三誘電体膜５を形成しなかった場合は、第一誘電体膜３
の成分である鉛と発光層６の成分である硫黄とが反応し
て、素子が黒色化する。Next, in order to improve the crystallinity of the light emitting layer 6, the obtained laminated film is heat-treated in an inert gas at 630 ° C. for 1 hour. Here, when the second dielectric film 4 and / or the third dielectric film 5 is not formed, the first dielectric film 3
The element, which is lead, reacts with the element, which is the light-emitting layer 6, that is sulfur, and the element is blackened.
【００３６】次に、酸化シリコン膜８上に、真空蒸着法
によりアルミニウム膜を成膜し、ホトリソグラフィーを
行って、上部電極９を形成する。なお、上部電極９を構
成する材料としては、特に限定されるものではなく、公
知のもの、例えばアルミニウム、アルミニウム・リチウ
ム合金、マグネシウム・銀合金、インジウム等が挙げら
れる。上部電極９の形成方法は、公知の手法、例えばス
パッタ法、抵抗加熱蒸着法、電子ビーム法、スプレー法
等により成膜することができる。上部電極の膜厚は、特
に限定されないが、通常、１００〜１０００ｎｍ程度で
ある。Next, an aluminum film is formed on the silicon oxide film 8 by a vacuum vapor deposition method, and photolithography is performed to form an upper electrode 9. The material forming the upper electrode 9 is not particularly limited, and known materials such as aluminum, aluminum-lithium alloy, magnesium-silver alloy, and indium can be used. The upper electrode 9 can be formed by a known method such as a sputtering method, a resistance heating vapor deposition method, an electron beam method, or a spray method. The thickness of the upper electrode is not particularly limited, but is usually about 100 to 1000 nm.
【００３７】こうして作製される薄膜ＥＬ素子の発光輝
度と印加電圧との関係を表わすグラフを図３に示す。ま
た、比較として、第二誘電体膜を形成しなかった場合の
素子のグラフ及び下部絶縁層が窒化シリコン２４（膜厚
２１０ｎｍ）及び酸化シリコン２５（膜厚３５ｎｍ）か
らなる従来の素子（図７）のグラフも図３に示す。FIG. 3 is a graph showing the relationship between the light emission luminance of the thin film EL element thus manufactured and the applied voltage. For comparison, a graph of the device in which the second dielectric film is not formed and the conventional device in which the lower insulating layer is composed of silicon nitride 24 (film thickness 210 nm) and silicon oxide 25 (film thickness 35 nm) (FIG. 7). The graph of) is also shown in FIG.
【００３８】図３によれば、本実施形態の薄膜ＥＬ素子
は、従来の素子よりも、閾値が３０Ｖ以上低下し、ま
た、各閾値から電圧をさらに４０Ｖ印加したとき（本実
施形態では、印加電圧１８０Ｖ、従来例では、印加電圧
２１０Ｖ）において、２倍以上の輝度が得られることが
分かる。また、第二誘電体膜を形成しなかった素子は閾
値の低下が見られ、１５５Ｖ付近で素子が破壊する。こ
れに対し、本実施形態の薄膜ＥＬ素子は２９０Ｖまで素
子破壊が見られない。また、加速試験によれば、５００
００時間後も安定した発光特性が得られることが分か
る。According to FIG. 3, the thin film EL element of the present embodiment has a threshold value lower than that of the conventional element by 30 V or more, and when a voltage of 40 V is applied from each threshold value (in the present embodiment, the voltage is applied). It can be seen that at a voltage of 180 V, and in the conventional example, an applied voltage of 210 V), the brightness twice or more can be obtained. In addition, the threshold value of the element in which the second dielectric film is not formed is lowered, and the element is destroyed at around 155V. On the contrary, in the thin film EL device of this embodiment, no device breakdown is observed up to 290V. Moreover, according to the acceleration test, 500
It can be seen that stable emission characteristics can be obtained even after 00 hours.
【００３９】以上、本実施形態の薄膜ＥＬ素子は、特定
の材料からなる３層の誘電体膜が下部絶縁層として構成
されてなるため、高容量・高耐圧を示し、素子特性とし
て高輝度・高信頼性を有することが示された。As described above, the thin-film EL device of this embodiment has three layers of dielectric films made of a specific material as the lower insulating layer, and therefore exhibits high capacity and high withstand voltage and high luminance as device characteristics. It was shown to have high reliability.
【００４０】実施形態２
図４に本実施形態の薄膜ＥＬ素子の概略断面図を示す。
図４の薄膜ＥＬ素子は、基板１１上に、下部電極１２、
第一誘電体膜１３、第二誘電体膜１４、第三誘電体膜１
５、発光層１６、窒化シリコン膜１７、酸化シリコン膜
１８、上部電極１９がこの順で積層されてなる。なお、
下部絶縁層は、第一誘電体膜１３、第二誘電体膜１４及
び第三誘電体膜１５からなり、上部絶縁層は、窒化シリ
コン膜１７及び酸化シリコン膜１８からなる。Embodiment 2 FIG. 4 shows a schematic sectional view of the thin film EL element of this embodiment.
The thin film EL device of FIG. 4 has a lower electrode 12,
First dielectric film 13, second dielectric film 14, third dielectric film 1
5, the light emitting layer 16, the silicon nitride film 17, the silicon oxide film 18, and the upper electrode 19 are laminated in this order. In addition,
The lower insulating layer is composed of the first dielectric film 13, the second dielectric film 14 and the third dielectric film 15, and the upper insulating layer is composed of the silicon nitride film 17 and the silicon oxide film 18.
【００４１】以下、この薄膜ＥＬ素子の製造方法を説明
する。実施形態１と同様にして、ガラス基板１１上にＩ
ＴＯ電極（下部電極１２）、チタン酸ジルコン酸鉛膜
（第一誘電体膜１３）を形成する。The method of manufacturing this thin film EL element will be described below. In the same manner as in the first embodiment, I on the glass substrate 11
A TO electrode (lower electrode 12) and a lead zirconate titanate film (first dielectric film 13) are formed.
【００４２】次に、第一誘電体膜１３上に、チタンのア
ルコキシド若しくは有機金属塩を主成分とした溶液を反
応させたものを用いて、化学溶液堆積法により、酸化チ
タン膜（第二誘電体膜１４）を膜厚１５０ｎｍに形成す
る。具体的には、上記化学溶液を第一誘電体膜１３上に
塗布し、１００℃程度で乾燥して溶媒を除去し、３５０
℃程度で仮焼成して残留有機物を除去し、酸化チタンの
結晶化温度以上の温度（本実施形態では６００℃以上）
で結晶化焼成を施すことにより、酸化チタン膜（第二誘
電体膜１４）を形成する。Next, a titanium oxide film (second dielectric film) is formed on the first dielectric film 13 by chemical solution deposition using a solution obtained by reacting a solution containing titanium alkoxide or an organic metal salt as a main component. The body film 14) is formed to a film thickness of 150 nm. Specifically, the chemical solution is applied onto the first dielectric film 13 and dried at about 100 ° C. to remove the solvent.
A temperature higher than the crystallization temperature of titanium oxide (600 ° C. or higher in the present embodiment) by calcination at about ℃ to remove residual organic substances.
Then, the titanium oxide film (second dielectric film 14) is formed by performing crystallization baking.
【００４３】なお、第一誘電体膜１３と第二誘電体膜１
４とは次の方法によって同時に形成できる。すなわち、
第一誘電体膜１３となるチタン酸ジルコン酸鉛の溶液を
ガラス基板１１に塗布し、３５０℃程度で仮焼成して非
晶質膜（第一誘電体膜の前駆体膜）にする。次いで、そ
の上に、第二誘電体膜１４となる酸化チタンの溶液を塗
布し、１００℃程度で乾燥して溶媒を除去し、３５０℃
程度で仮焼成して残留有機物を除去し、非晶質膜（第二
誘電体膜の前駆体膜）にする。次いで、チタン酸ジルコ
ン酸鉛の結晶化温度以上の温度で結晶化焼成を施すこと
により、第一誘電体膜１３及び第二誘電体膜１４を同時
に形成する。この方法によれば、チタン酸ジルコン酸鉛
にある過剰の鉛成分が酸化チタンと反応するので、発光
層と鉛との反応防止効果が向上する。The first dielectric film 13 and the second dielectric film 1
4 and 4 can be formed simultaneously by the following method. That is,
A solution of lead zirconate titanate to be the first dielectric film 13 is applied to the glass substrate 11 and calcined at about 350 ° C. to form an amorphous film (precursor film of the first dielectric film). Then, a solution of titanium oxide to be the second dielectric film 14 is applied thereon, and dried at about 100 ° C. to remove the solvent, and 350 ° C.
Approximately calcination is performed to remove the residual organic matter to form an amorphous film (precursor film for the second dielectric film). Then, the first dielectric film 13 and the second dielectric film 14 are simultaneously formed by performing crystallization firing at a temperature equal to or higher than the crystallization temperature of lead zirconate titanate. According to this method, the excess lead component in lead zirconate titanate reacts with titanium oxide, so that the effect of preventing the reaction between the light emitting layer and lead is improved.
【００４４】第二誘電体膜１４の膜厚は、特に限定され
ないが、化学溶液堆積法で一回若しくは二回の塗布工程
で得られて生産性がよいこと等から、１００〜２００ｎ
ｍ程度が好ましく、さらには、再現性のよい特性が得ら
れることから、１２０〜１６０ｎｍ程度がより好まし
い。第二誘電体膜１４の膜厚が１００ｎｍを下回ると、
発光層１６の熱処理時に第一誘電体膜１３から揮発する
鉛分の拡散を防ぐのが不充分であり、素子が黒色化しや
すいので好ましくない。逆に膜厚が２００ｎｍを上回る
と、クラックが発生しやすく、安定な素子を作製するの
が難しいので好ましくない。The thickness of the second dielectric film 14 is not particularly limited, but is 100 to 200 n because it is obtained by a chemical solution deposition method in one or two coating steps and has good productivity.
m is preferable, and further, about 120 to 160 nm is more preferable because characteristics with good reproducibility are obtained. When the film thickness of the second dielectric film 14 is less than 100 nm,
It is not preferable because it is insufficient to prevent the diffusion of lead volatilized from the first dielectric film 13 during the heat treatment of the light emitting layer 16 and the element is easily blackened. On the contrary, if the film thickness exceeds 200 nm, cracks are likely to occur and it is difficult to manufacture a stable element, which is not preferable.
【００４５】第一、第二誘電体膜の積層膜は、比誘電率
が２３２、誘電損失が９％である。また、第二誘電体膜
１４の下部電極１２上での単膜特性は、リーク電流が非
常に高く、正確な値が得られない。The laminated film of the first and second dielectric films has a relative dielectric constant of 232 and a dielectric loss of 9%. In addition, the single film characteristic of the second dielectric film 14 on the lower electrode 12 has a very high leak current and an accurate value cannot be obtained.
【００４６】次に、第二誘電体膜１４上に反応性スパッ
タ法にて、基板温度２００℃程度で窒化シリコン膜（第
三誘電体膜１５）を５０ｎｍ程度に形成する。第一、第
二、第三誘電体膜の積層膜は、比誘電率が１０９、誘電
損失が１．８％である。また、第三誘電体膜１５の下部
電極１２上での単膜特性は、比誘電率が７．５、誘電損
失が１％以下である。Next, a silicon nitride film (third dielectric film 15) is formed on the second dielectric film 14 by reactive sputtering at a substrate temperature of about 200 ° C. to a thickness of about 50 nm. The laminated film of the first, second and third dielectric films has a relative dielectric constant of 109 and a dielectric loss of 1.8%. The single film characteristics of the third dielectric film 15 on the lower electrode 12 are a relative dielectric constant of 7.5 and a dielectric loss of 1% or less.
【００４７】これらの単膜及び積層膜の電流密度と印加
電圧との関係を表わすグラフを図５に示す。このグラフ
から、第一誘電体膜１３（ＰＺＴ）、第二誘電体膜１４
（ＴｉＯ2）、第三誘電体膜１５（ＳｉＮｘ）は単膜で
は耐圧値がそれぞれ２５Ｖ、１０Ｖ、２６Ｖ程度である
ことが分かる。第一誘電体膜１３と第二誘電体膜１４と
の積層膜では、リーク電流密度は高いものの、耐圧は１
３０Ｖまで増加する。第一誘電体膜１３と第二誘電体膜
１４と第三誘電体膜１５との積層膜では、耐圧は２００
Ｖ以上まで増加することが分かる。また、積層膜である
ため、ピンホールにも強い。FIG. 5 is a graph showing the relationship between the current density and the applied voltage of these single film and laminated film. From this graph, the first dielectric film 13 (PZT), the second dielectric film 14
It can be seen that the withstand voltage values of (TiO 2 ) and the third dielectric film 15 (SiNx) are about 25V, 10V, and 26V, respectively. In the laminated film of the first dielectric film 13 and the second dielectric film 14, the leak current density is high, but the breakdown voltage is 1.
Increase to 30V. The withstand voltage of the laminated film of the first dielectric film 13, the second dielectric film 14, and the third dielectric film 15 is 200.
It can be seen that it increases to V or more. Further, since it is a laminated film, it is strong against pinholes.
【００４８】次に、実施形態１と同様にして、第三誘電
体膜１５上に、発光層１６、窒化シリコン膜１７、酸化
シリコン膜１８、アルミニウム膜（上部電極１９）を形
成する。ここで、第二誘電体膜１４及び／又は第三誘電
体膜１５を形成しなかった場合、第一誘電体膜１３の成
分である鉛と発光層１６の成分である硫黄とが反応し
て、素子が黒色化する。Next, similarly to the first embodiment, the light emitting layer 16, the silicon nitride film 17, the silicon oxide film 18, and the aluminum film (upper electrode 19) are formed on the third dielectric film 15. Here, when the second dielectric film 14 and / or the third dielectric film 15 is not formed, lead which is a component of the first dielectric film 13 and sulfur which is a component of the light emitting layer 16 react with each other. , The element turns black.
【００４９】こうして作製された本実施形態の薄膜ＥＬ
素子の発光輝度と印加電圧との関係を表わすグラフを図
６に示す。また、比較として、第二誘電体膜１４を形成
しなかった素子のグラフ及び下部絶縁層が窒化シリコン
２４（膜厚２１０ｎｍ）及び酸化シリコン２５（膜厚３
５ｎｍ）からなる従来の素子（図７）のグラフも図６に
示す。The thin film EL of this embodiment manufactured in this way
A graph showing the relationship between the light emission luminance of the device and the applied voltage is shown in FIG. For comparison, the graph of the device in which the second dielectric film 14 is not formed and the lower insulating layer are silicon nitride 24 (film thickness 210 nm) and silicon oxide 25 (film thickness 3).
A graph of a conventional device (FIG. 7) composed of 5 nm) is also shown in FIG.
【００５０】本実施形態の薄膜ＥＬ素子は、従来の素子
と比較して３０Ｖ以上の閾値低下が見られ、各閾値から
さらに電圧を４０Ｖ印加したとき（本実施形態では１８
０Ｖ、従来例では２１０Ｖ）、２倍以上の輝度が得られ
る。また、第二誘電体膜１４を形成しなかった素子は、
閾値の低下が見られ、１５５Ｖ付近で素子が破壊する。
これに対し、本実施形態の薄膜ＥＬ素子は２９０Ｖまで
素子破壊が見られない。また、本実施形態の薄膜ＥＬ素
子は、加速試験により５００００時間後も安定した発光
特性が得られることが分かる。The thin film EL element of the present embodiment shows a threshold voltage drop of 30 V or more as compared with the conventional element, and when a voltage of 40 V is applied from each threshold value (18 in the present embodiment).
0 V, 210 V in the conventional example), and a brightness more than twice as high can be obtained. In addition, the element in which the second dielectric film 14 is not formed is
A decrease in the threshold is seen, and the device breaks down near 155V.
On the contrary, in the thin film EL device of this embodiment, no device breakdown is observed up to 290V. In addition, the thin film EL element of the present embodiment shows that stable light emission characteristics can be obtained even after 50,000 hours by the acceleration test.
【００５１】以上、本実施形態の薄膜ＥＬ素子は、特定
の材料からなる３層の誘電体膜が下部絶縁層として構成
されてなるため、高容量・高耐圧を示し、素子特性とし
て高輝度・高信頼性を有することが示された。As described above, since the thin film EL element of this embodiment is composed of three layers of dielectric films made of a specific material as the lower insulating layer, it exhibits high capacity and high breakdown voltage, and has high luminance and element characteristics. It was shown to have high reliability.
【００５２】[0052]
【発明の効果】本発明によれば、薄膜ＥＬ素子を構成す
る絶縁層として、結晶性高誘電体膜に低温で形成しても
緻密性、比誘電率が高いチタン酸ジルコン酸鉛を主成分
とする第一誘電体薄膜、結晶性誘電体膜に低温で形成す
ると緻密化しづらく、誘電損失が高いチタン酸バリウム
若しくは酸化チタンを主成分とする第二誘電体膜、低温
で形成しても高耐圧、低誘電損失な窒化シリコン若しく
は酸窒化シリコンを主成分とする第三誘電体膜をこの順
に積層したものを用いることにより、絶縁耐圧が飛躍的
に上昇し、さらに硫化物系発光層との反応により、黒色
化するといった問題を解決できる。According to the present invention, lead zirconate titanate, which has a high density and a high relative dielectric constant even when formed on a crystalline high-dielectric-constant film at a low temperature, is used as an insulating layer constituting a thin film EL element. It is difficult to densify the first dielectric thin film or the crystalline dielectric film when formed at a low temperature, and the second dielectric film containing barium titanate or titanium oxide as a main component has a high dielectric loss. By using a third dielectric film mainly composed of silicon nitride or silicon oxynitride having a low withstand voltage and a low dielectric loss in this order, the withstand voltage is dramatically increased, and further, a sulfide-based light emitting layer is formed. The reaction can solve the problem of blackening.
【図１】実施形態１の薄膜ＥＬ素子の概略断面図であ
る。FIG. 1 is a schematic cross-sectional view of a thin film EL element according to a first embodiment.
【図２】実施形態１で用いた絶縁層の「電流密度−印加
電圧」特性グラフである。FIG. 2 is a “current density-applied voltage” characteristic graph of the insulating layer used in the first embodiment.
【図３】実施形態１の薄膜ＥＬ素子の「印加電圧−発光
輝度」特性グラフである。FIG. 3 is a characteristic graph of “applied voltage-light emission luminance” of the thin film EL element of the first embodiment.
【図４】実施形態２の薄膜ＥＬ素子の概略断面図であ
る。FIG. 4 is a schematic cross-sectional view of a thin film EL element of Embodiment 2.
【図５】実施形態２で用いた絶縁層の「電流密度−印加
電圧」特性グラフである。FIG. 5 is a “current density-applied voltage” characteristic graph of the insulating layer used in the second embodiment.
【図６】実施形態２の薄膜ＥＬ素子の「印加電圧−発光
輝度」特性グラフである。FIG. 6 is a characteristic graph of “applied voltage-luminance” of the thin film EL element of the second embodiment.
【図７】従来の薄膜ＥＬ素子の概略断面図である。FIG. 7 is a schematic cross-sectional view of a conventional thin film EL element.
１、１１、２１ 基板 ２、１２、２２ 下部電極 ３、１３ 第一誘電体膜（チタン酸ジルコン酸鉛膜） ４ 第二誘電体膜（チタン酸バリウム膜） ５、１５ 第三誘電体膜（窒化シリコン膜） ６、１６、２６ 発光層 ７、１７、２５、２７ 窒化シリコン膜 ８、１８、２４、２８ 酸化シリコン膜 ９、１９、２９ 上部電極 １４ 第二誘電体膜（酸化チタン膜） 1, 11, 21 substrate 2, 12, 22 Lower electrode 3, 13 First dielectric film (lead zirconate titanate film) 4 Second dielectric film (barium titanate film) 5, 15 Third dielectric film (silicon nitride film) 6, 16, 26 Light emitting layer 7, 17, 25, 27 Silicon nitride film 8, 18, 24, 28 Silicon oxide film 9, 19, 29 Upper electrode 14 Second dielectric film (titanium oxide film)
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 3K007 AB00 AB02 AB07 CA01 CB01 DA02 DA05 DB01 DB02 DC02 DC04 EC01 EC03 FA01 FA03 ─────────────────────────────────────────────────── ─── Continued front page F-term (reference) 3K007 AB00 AB02 AB07 CA01 CB01 DA02 DA05 DB01 DB02 DC02 DC04 EC01 EC03 FA01 FA03
Claims (6)
層、上部絶縁層、上部電極をこの順で構成してなる薄膜
ＥＬ素子において、 下部絶縁層及び上部絶縁層の両方又はいずれか一方が、
少なくとも、チタン酸ジルコン酸鉛を主成分とする第一
誘電体膜と、チタン酸バリウム若しくは酸化チタンを主
成分とする第二誘電体膜と、窒化シリコン若しくは酸窒
化シリコンを主成分とする第三誘電体膜とをこの順に積
層したものを含むことを特徴とする薄膜ＥＬ素子。1. A thin-film EL device comprising a substrate and a lower electrode, a lower insulating layer, a light emitting layer, an upper insulating layer, and an upper electrode in this order, wherein either or both of the lower insulating layer and the upper insulating layer are formed. One is
At least a first dielectric film containing lead zirconate titanate as a main component, a second dielectric film containing barium titanate or titanium oxide as a main component, and a third dielectric film containing silicon nitride or silicon oxynitride as a main component. A thin film EL element comprising a dielectric film and a dielectric film laminated in this order.
成分とし、膜厚１５０〜３５０ｎｍを有する請求項１に
記載の薄膜ＥＬ素子。2. The thin film EL device according to claim 1, wherein the second dielectric film contains barium titanate as a main component and has a film thickness of 150 to 350 nm.
し、膜厚１００〜２００ｎｍを有する請求項１に記載の
薄膜ＥＬ素子。3. The thin film EL device according to claim 1, wherein the second dielectric film contains titanium oxide as a main component and has a film thickness of 100 to 200 nm.
ｍである請求項１〜３のいずれかに記載の薄膜ＥＬ素
子。4. The thickness of the first dielectric film is 200 to 300 n.
The thin film EL element according to any one of claims 1 to 3, wherein m is m.
である請求項１〜４のいずれかに記載の薄膜ＥＬ素子。5. The thickness of the third dielectric film is 40 to 100 nm.
The thin film EL element according to any one of claims 1 to 4.
タン酸ジルコン酸鉛を主成分とした非晶質の第一誘電体
膜の前駆体膜を成膜し、第一誘電体膜の前駆体膜上に酸
化チタンを主成分とした非晶質の第二誘電体膜の前駆体
膜を成膜し、チタン酸ジルコン酸鉛の結晶化温度以上に
熱処理して第一誘電体膜及び第二誘電体膜を形成するこ
とを特徴とする請求項１〜５のいずれかに記載の薄膜Ｅ
Ｌ素子の製造方法。6. A precursor film of an amorphous first dielectric film having lead zirconate titanate as a main component is formed on a substrate on which a lower electrode is formed in advance, and the precursor film of the first dielectric film is formed. An amorphous second dielectric film precursor film containing titanium oxide as a main component is formed on the precursor film, and heat-treated at a temperature not lower than the crystallization temperature of lead zirconate titanate to form the first dielectric film and The thin film E according to claim 1, wherein a second dielectric film is formed.
Manufacturing method of L element.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003323981A (en) * | 2002-05-01 | 2003-11-14 | Tdk Corp | Dielectric layer patterning method, thin film el element manufacturing method and thin film el element |
| WO2005017859A1 (en) * | 2003-08-19 | 2005-02-24 | Fuji Electric Holdings Co., Ltd. | Display and method for driving same |
| US7560749B2 (en) | 2006-01-27 | 2009-07-14 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting material, light emitting device, and electronic device |
| US7851997B2 (en) | 2006-06-02 | 2010-12-14 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting element and light emitting device |
-
2001
- 2001-08-30 JP JP2001261653A patent/JP3895141B2/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003323981A (en) * | 2002-05-01 | 2003-11-14 | Tdk Corp | Dielectric layer patterning method, thin film el element manufacturing method and thin film el element |
| WO2005017859A1 (en) * | 2003-08-19 | 2005-02-24 | Fuji Electric Holdings Co., Ltd. | Display and method for driving same |
| JPWO2005017859A1 (en) * | 2003-08-19 | 2007-10-04 | 富士電機ホールディングス株式会社 | Display device and driving method thereof |
| US7560749B2 (en) | 2006-01-27 | 2009-07-14 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting material, light emitting device, and electronic device |
| US7851997B2 (en) | 2006-06-02 | 2010-12-14 | Semiconductor Energy Laboratory Co., Ltd. | Light emitting element and light emitting device |
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