JP3385087B2 - Pt thin film integrated with substrate, thin film heater using the same, temperature detecting element and gas sensor - Google Patents
Pt thin film integrated with substrate, thin film heater using the same, temperature detecting element and gas sensorInfo
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- JP3385087B2 JP3385087B2 JP35051693A JP35051693A JP3385087B2 JP 3385087 B2 JP3385087 B2 JP 3385087B2 JP 35051693 A JP35051693 A JP 35051693A JP 35051693 A JP35051693 A JP 35051693A JP 3385087 B2 JP3385087 B2 JP 3385087B2
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- thin film
- substrate
- film
- hkl
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Description
【0001】[0001]
【技術分野】本発明は、Pt薄膜、Pt薄膜化技術およ
びPt薄膜抵抗体に関する。TECHNICAL FIELD The present invention relates to a Pt thin film, a Pt thinning technology, and a Pt thin film resistor.
【0002】[0002]
【従来技術】Proc. 1st Int’l Sym
p. on ISSP ’91 Tokyo(199
1)p.73には、スパッタリング法により、各種機能
性薄膜を作製している。ある種の結晶化薄膜は、Pt上
にしか結晶構造を取らず、またその結晶化薄膜の特性
と、Pt(111)配向度に関する考察をこの論文で報
告している。Pt(111)面の配向性はXRDにより
その半値幅から定量され、配向度の向上と機能性薄膜特
性の信頼性には相関があった。Pt薄膜に要求される結
晶性は、最終的にはサファイア単結晶基板上に、エピタ
キシャル成長させたPtエピタキシャル膜が最も高い信
頼性を(その上層の機能性薄膜)与えた。また、米国特
許第4,952,904号には、マイクロブリッジ上に
形成される気体質量流量センサに、Pt薄膜抵抗体を使
用し、該Pt膜の膜剥離を防止するために金属酸化膜層
を、Pt膜上下層に設けることを開示している。特公平
3−44401号公報には、Pt薄膜抵抗体の膜剥離を
防止するために、Pt膜上下層にTiO2層を設けてい
る。2. Description of the Related Art Proc. 1st Int'l Sym
p. on ISSP '91 Tokyo (199
1) p. Various functional thin films are formed on 73 by a sputtering method. Some crystallized thin films have a crystal structure only on Pt, and the characteristics of the crystallized thin films and a discussion on the degree of Pt (111) orientation are reported in this paper. The orientation of the Pt (111) plane was quantified by XRD from its half-value width, and there was a correlation between the improvement of the orientation and the reliability of the functional thin film characteristics. Regarding the crystallinity required for the Pt thin film, finally, the Pt epitaxial film epitaxially grown on the sapphire single crystal substrate provided the highest reliability (the functional thin film as the upper layer). Also, in US Pat. No. 4,952,904, a Pt thin film resistor is used in a gas mass flow sensor formed on a microbridge, and a metal oxide film layer is formed to prevent the Pt film from peeling off. Is provided on the upper and lower layers of the Pt film. In Japanese Examined Patent Publication No. 3-44401, a TiO 2 layer is provided above and below the Pt film in order to prevent film peeling of the Pt thin film resistor.
【0003】[0003]
【目的】Ptは(1)抵抗率が10.8×10-6Ω・c
m(室温)と他の金属と較べて比較的高い、(2)通電
によるPt原子移動(エレクトロマイグレーション)が
ほとんど無い、(3)高い温度抵抗係数を持ち(370
0ppm)、かつ温度抵抗係数の直線性が良い、(4)
酸、アルカリに侵されることなく、かつ化学的に安定で
ある。前記のような特徴を有するPtはヒータ材料とし
て適しており、また、抵抗値を測定することで、温度の
測温もできる。さらに、素子の小型化の要請から、近年
Ptを各種の真空製膜法により薄膜とし、これら機能を
実現する試みがある。特にマイクロマシーン加工による
Si基板上でのマイクロ素子では、マイクロブリッジ上
にPt薄膜抵抗体を形成させ、その機能を小型化、高感
度化、高機能化、低消費電力、高速応答等を実現させて
きている。例えば、金属酸化物半導体の高温時における
吸着現象による抵抗値変化を利用したガスセンサでは、
酸化物半導体の薄膜形成、および加熱用にPt薄膜抵抗
体の発熱素子を配置させ、ここにPt薄膜ヒータが使用
されている。熱式気体質量流量計では同様に、マイクロ
ブリッジ上にPt薄膜ヒータを、また気体移動に伴う熱
移動を正確に測定するために、Pt薄膜測温体を対称位
置に配置させた素子がある。これら各種センサに共通し
ている構造は、マイクロブリッジ(絶縁体物質で構成さ
れている)上にPt薄膜を積層し、更に絶縁体のパッシ
ベーション膜を積層していることである。しかし、Pt
は安定な金属であるために、Ptと下地絶縁物質、およ
びPtとその上のパッシベーション膜との接着強度が弱
く、はがれ易いという問題がある。この対策として、T
i、Ta、Cr等のPtや絶縁体、および半導体材料と
接着強度が高い(密着性の良い)金属膜が採用されてい
る。しかしこのような密着補強層の採用は以下の不都合
を生じる。
(1)Pt薄膜抵抗体を薄膜ヒータとして用いた場合、
通電による発熱により、下地金属層とPt薄膜間で合金
化、固溶化が進行する。TiはPtと同じ結晶構造を取
り、比較的低温で固溶し、この場合グレイン成長が進行
する。Ta、CrのPt反応性は、これらがPtと異な
る結晶構造を有しているため、Ptグレインは反応の進
行に伴い、微粒子化する。この時、抵抗率、温度抵抗係
数はいずれの場合にも変化し、従って経時変化がある。
特に、ガスセンサ等に用いられるPt薄膜ヒータに於い
ては、酸化物半導体の電荷吸着が450℃程の高温であ
るために、経時変化が著しい。
(2)Pt薄膜抵抗体を熱式質量流量計の測温体に用い
る場合、熱収支による薄膜温度変化の対応を正確に検出
するため、温度抵抗係数が高いことが望まれる。Pt自
身のそれは金属元素の中で高い値を持つグループに属し
ており、その値はバルク体で3700ppm(室温〜3
00℃)に達しているが、先の密着補強のための金属は
Ptより温度抵抗係数が低いため、積層構造では結果と
して温度抵抗係数が低くなってしまう。一例を示すと、
スパッタ製膜した膜厚1000ÅのPt薄膜の温度抵抗
係数は2600ppmであり、Cr300Å、Pt10
00Åの積層試料では1900ppmになってしまっ
た。すなわち、Pt密着補強のための金属膜の採用は、
膜剥離という故障は回避できるものの、Pt本来の持つ
物性値を低減させてしまい、特性を劣化させてしまう欠
点を有する。前記の従来技術の項で示した2件の特許
は、密着補強層として電気的に絶縁体である金属酸化物
を採用している。すなわち、米国特許第4952904
では、極薄膜20〜100Åの金属酸化膜を使用してい
る。また特公平3−44401ではTiO2を400Å
堆積させ、積層している。一般に薄膜形成の機構は、質
量膜厚が薄い成長初期においては島状構造を取り、質量
膜厚の増加に伴い連続膜へと形態変化をする。従って、
先の20〜100Åの膜厚は、部分的に、ピンホールを
有する非連続膜に近い。このような下地にPt薄膜が堆
積されれば、ピンホール部において密着強度の劣る、絶
縁材料/Ptの界面が存在し、駆動時(薄膜ヒータとし
て使用した場合)の熱による熱応力の発生と歪みにより
剥離が生じることがある。TiO2400Å様に厚くな
ると、先の問題は無くなるが、積層構造において、3次
元的にパターンが立体化してくる。これは次の問題を招
く。パッシベーションは環境から素子を保護する目的で
堆積させるものである。仮にTiO2(400Å)/P
t(1000Å)/TiO2(400Å)の積層構造を
取ると、このパターンにより生じる段差は1800Åに
なり、ステップカバレッジを考慮したときのパッシベー
ション膜厚は4000Å程になってしまう。各種マイク
ロセンサに共通する応答速度の高速化は、熱容量が膜厚
の増加により増えてしまうという物理的な制約により、
その特性劣化を免れることは出来ない。すなわち、金属
酸化物のような電気的に不活性な材料を用いても、以上
の不具合を生じる。更につけ加えれば、密着補強層など
を施すことは基本的には工程数の増加につながり、工程
の煩雑さを増し、製品コストを高くし、歩留まりを低下
させるものであり好ましくない。本発明の目的は、これ
ら各種マイクロセンサを作製するに当り、Pt薄膜抵抗
体を用いる場合、Pt膜の膜剥離故障を防ぐため、従来
から報告されている密着補強層を採用することなくPt
薄膜の構造制御により十分な密着力を確保することによ
り解決するものである。したがって、今まで述べてきた
マイクロセンサ等の素子に対し、高信頼性を持つPt薄
膜抵抗体を提供するものである。[Purpose] Pt has (1) resistivity of 10.8 × 10 -6 Ω · c
m (room temperature), which is relatively high compared to other metals, (2) almost no Pt atom transfer (electromigration) due to energization, (3) high temperature resistance coefficient (370
(0 ppm) and good linearity of temperature resistance coefficient (4)
It is chemically stable without being attacked by acids and alkalis. Pt having the above characteristics is suitable as a heater material, and the temperature can be measured by measuring the resistance value. In addition, due to the demand for miniaturization of elements, there have been attempts in recent years to form Pt into a thin film by various vacuum film forming methods to realize these functions. In particular, in the case of a micro device on a Si substrate processed by a micro machine, a Pt thin film resistor is formed on a micro bridge, and its function is miniaturized, high sensitivity, high functionality, low power consumption, high speed response, etc. are realized. Is coming. For example, in a gas sensor using a resistance change due to an adsorption phenomenon of a metal oxide semiconductor at high temperature,
A Pt thin film heater is used for arranging a heating element of a Pt thin film resistor for forming and heating an oxide semiconductor thin film. Similarly, in the thermal gas mass flowmeter, there is an element in which a Pt thin film heater is arranged on the microbridge and a Pt thin film temperature measuring element is arranged in a symmetrical position in order to accurately measure heat transfer due to gas transfer. The structure common to these various sensors is that a Pt thin film is laminated on a microbridge (composed of an insulator material), and a passivation film of an insulator is further laminated. But Pt
Since P is a stable metal, there is a problem that the adhesion strength between Pt and the underlying insulating material, and Pt and the passivation film on Pt is weak, and peeling easily occurs. As a countermeasure against this, T
A metal film having high adhesion strength (good adhesion) with Pt such as i, Ta, Cr, an insulator, and a semiconductor material is adopted. However, the use of such an adhesion reinforcing layer has the following disadvantages. (1) When a Pt thin film resistor is used as a thin film heater,
Due to heat generated by energization, alloying and solid solution progress between the underlying metal layer and the Pt thin film. Ti has the same crystal structure as Pt and forms a solid solution at a relatively low temperature, in which case grain growth proceeds. Regarding the Pt reactivity of Ta and Cr, since these have a crystal structure different from Pt, Pt grains become fine particles as the reaction progresses. At this time, the resistivity and the temperature resistance coefficient change in both cases, and thus change with time.
Particularly, in a Pt thin film heater used for a gas sensor or the like, since the charge adsorption of the oxide semiconductor is as high as 450 ° C., the change over time is remarkable. (2) When the Pt thin film resistor is used as a temperature measuring element of a thermal mass flowmeter, a high temperature resistance coefficient is desired in order to accurately detect the correspondence of the thin film temperature change due to the heat balance. That of Pt itself belongs to a group having a high value among metal elements, and the value is 3700 ppm in bulk body (room temperature to 3
However, since the metal for adhesion reinforcement has a lower temperature resistance coefficient than Pt, the laminated structure results in a lower temperature resistance coefficient. For example,
The temperature resistance coefficient of the Pt thin film with a film thickness of 1000 Å sputtered is 2600 ppm, and Cr 300 Å, Pt 10
In the case of the laminated sample of 00Å, it became 1900 ppm. That is, the adoption of the metal film for Pt adhesion reinforcement is
Although the failure of film peeling can be avoided, it has a drawback that it reduces the physical properties inherent to Pt and deteriorates the characteristics. The two patents mentioned in the above-mentioned prior art section employ a metal oxide that is an electrically insulating material as the adhesion reinforcing layer. That is, US Pat. No. 4,952,904.
Then, an extremely thin metal oxide film of 20 to 100 Å is used. In addition, in Japanese Examined Patent Publication No. 3-44401, TiO 2 is 400 Å
Deposited and laminated. In general, the thin film formation mechanism takes an island-like structure in the early stage of growth when the mass film thickness is small, and changes to a continuous film as the mass film thickness increases. Therefore,
The aforementioned film thickness of 20 to 100Å is partially close to a discontinuous film having pinholes. If a Pt thin film is deposited on such an underlayer, there is an insulating material / Pt interface having poor adhesion strength in the pinhole portion, and thermal stress is generated due to heat during driving (when used as a thin film heater). Peeling may occur due to distortion. When the thickness is increased to TiO 2 400Å, the above problem disappears, but in the laminated structure, the pattern becomes three-dimensional in three dimensions. This leads to the following problems. Passivation is deposited for the purpose of protecting the device from the environment. If TiO 2 (400 Å) / P
When a laminated structure of t (1000Å) / TiO 2 (400Å) is adopted, the step difference caused by this pattern becomes 1800Å, and the passivation film thickness when considering step coverage becomes about 4000Å. The increase in the response speed common to various microsensors is due to the physical restriction that the heat capacity increases due to the increase in the film thickness.
The characteristic deterioration cannot be avoided. That is, even if an electrically inactive material such as a metal oxide is used, the above problems occur. In addition, the provision of an adhesion reinforcing layer or the like basically leads to an increase in the number of steps, increases the complexity of the steps, raises the product cost, and lowers the yield, which is not preferable. It is an object of the present invention to use Pt thin film resistors in the production of these various microsensors without using the adhesion reinforcing layer that has been reported in the past, in order to prevent film peeling failure of the Pt film.
The solution is to secure sufficient adhesion by controlling the structure of the thin film. Therefore, it is intended to provide a highly reliable Pt thin film resistor for the elements such as the microsensor described above.
【0004】[0004]
【構成】本発明による基板と一体化されたPt薄膜の結
晶構造は、若干の(111)面優先配向を示す多結晶体
であり、シェラーの関係式より求められる結晶子サイズ
が150〜170Åである薄膜である。若干の(11
1)面優先配向とは、式(I)で定義する配向度に於い
て、60〜70%であることを意味する。またシェラー
の関係式とはX線回折に於いて、回折線の幅の広がりが
結晶子の大きさのみに基づくと仮定し、式(II)で示さ
れるものである。[Structure] The crystal structure of the Pt thin film integrated with the substrate according to the present invention is a polycrystal exhibiting a slight (111) plane preferential orientation, and the crystallite size obtained from Scherrer's relational expression is 150 to 170Å. It is a thin film. Some (11
1) The plane-preferred orientation means that the degree of orientation defined by the formula (I) is 60 to 70%. The Scherrer's relational expression is expressed by the formula (II) on the assumption that the broadening of the width of the diffraction line is based only on the size of the crystallite in X-ray diffraction.
【数3】
〔(111)面配向度〕=〔I(111)/ΣI(hkl)〕×100 (I)
I(111)はXRD測定における(111)面回折強
度、ΣI(hkl)は測定範囲内で測定される全ての回
折強度の和である。## EQU3 ## [(111) plane orientation degree] = [I (111) / ΣI (hkl)] × 100 (I) I (111) is the (111) plane diffraction intensity in XRD measurement, and ΣI (hkl) is the measurement It is the sum of all diffraction intensities measured within the range.
【数4】Dhkl=Kλ/βcosθ (II)
Dhklは(hkl)面に垂直方向の結晶子の大きさ
(Å)、λはX線の波長(Å)、βは回折線幅(ra
d)、θは回折角(゜)である。Kは定数であり、0.
9である。(4) D hkl = Kλ / β cos θ (II) D hkl is the crystallite size (Å) perpendicular to the (hkl) plane, λ is the X-ray wavelength (Å), and β is the diffraction line width (ra).
d) and θ are diffraction angles (°). K is a constant, and 0.
It is 9.
【0005】本発明の基板と一体化されたPt薄膜は、
例えばArおよび酸素混合ガスによるスパッタリング法
で製膜して作成することができる。一般的なArスパッ
タリングによる基板と一体化されたPt製膜は、エピタ
キシャル条件を満たす基板以外の場合、例えばアモルフ
ァス基板では(111)配向膜が得られる。この時の配
向度は先述の式(I)の定義によれば95%以上の結晶
化配向膜が得られている。エピタキシャル基板としては
MgO(100)上では、Pt(100)エピタキシャ
ル膜が、またサファイア(001)基板では、Pt(1
11)エピタキシャル膜が製膜される。アモルファスT
a2O5膜を製膜した基板上でのPt膜成長過程をRH
EEDで観察すると、成長初期からスポティな配向成長
がRHEEDパターンから観察される。この原因は、堆
積粒子(スパッタ粒子)の運動エネルギー密度が非常に
高く、基板到達粒子は、その運動エネルギーにより基板
上をマイグレートし、最も安定した状態で付着するから
である。一般にこの安定状態とは、各種エネルギー平衡
により決定され、結果として密度の最も充填される方位
に配向成長すると考えられる。先のエネルギー平衡と
は、単結晶基板上での成長では、基板原子の配列状態が
作用し、(111)配向でないエピタキシャル成長がな
される場合もある。アモルファス基板上の95%以上の
(111)配向膜で観察されるXRDより求めた結晶子
サイズはシェラーの関係式からは推定出来ないほどの大
きな結晶子である。推定出来ないほどとは、X線装置、
および光学系の揺らぎによる回折ピークの広がりがあ
り、結晶子サイズ2000Å以上ではその測定される半
値幅が、結晶子の大きさに依存するのか、光学系の揺ら
ぎに依存するのかが区別できなくなるからである。この
ことから先のPt薄膜の結晶子の大きさは、2000Å
以上と推定でき、RHEED、レウエ像、TEM像、表
面形態観察からの総合的な判断により、2〜4μmの結
晶子(すなわち、グレイン)になっていることがわかっ
た。このような基板と一体化された単結晶薄膜に近いP
t薄膜は、膜特有の応力が欠陥に集中することなく、膜
全体に応力が保持され、密着性の不良の場合には容易に
剥離してしまう。従って、基板との密着性を向上させる
には、適度な応力集中点を形成させる必要が有り、従っ
て、この欠陥を結晶成長の積層欠陥(スタッキングフォ
ールト)で形成し、かつ結晶子サイズを微粒子化すれば
良い。本発明は、スパッタリングで基板と一体化された
Pt薄膜を作製するが、その時スパッタガスとして通常
用いられているArガスの他に、O2ガスを導入し、こ
れら混合ガスによるスパッタを行う。これは、後で述べ
る実施例にデータを示すが、O2ガスの導入により、本
来ならば(111)面配向をするところが、(200)
面の成長が認められ、結晶子サイズも小さくなる、とい
う発見に基づくものである。これは、酸素イオンのPt
ターゲットへの衝突エネルギーが、Arのそれと比較し
て小さいことに起因している。The Pt thin film integrated with the substrate of the present invention is
For example, it can be formed by forming a film by a sputtering method using a mixed gas of Ar and oxygen. In the case of a Pt film integrated with a substrate by general Ar sputtering, a (111) oriented film is obtained in a substrate other than a substrate satisfying the epitaxial condition, for example, an amorphous substrate. According to the definition of the above-mentioned formula (I), a crystallized orientation film having a degree of orientation of 95% or more is obtained. As an epitaxial substrate, a Pt (100) epitaxial film is used on MgO (100), and Pt (1) is used on a sapphire (001) substrate.
11) An epitaxial film is formed. Amorphous T
RH growth process of Pt film on the substrate with a 2 O 5 film formed
When observed by EED, spotty oriented growth is observed from the RHEED pattern from the initial stage of growth. This is because the kinetic energy density of the deposited particles (sputtered particles) is very high, and the particles reaching the substrate migrate on the substrate due to the kinetic energy and adhere in the most stable state. Generally, this stable state is determined by various energy balances, and as a result, it is considered that orientation growth occurs in the direction in which the density is most filled. The above-mentioned energy equilibrium means that in the growth on a single crystal substrate, the arrangement state of the substrate atoms acts and epitaxial growth not in the (111) orientation may be performed. The crystallite size obtained by XRD observed in 95% or more of the (111) oriented film on the amorphous substrate is a crystallite that cannot be estimated from Scherrer's relational expression. What can not be estimated is an X-ray device,
Also, there is a broadening of the diffraction peak due to fluctuations in the optical system, and at a crystallite size of 2000 Å or larger, it is impossible to distinguish whether the measured half-value width depends on the crystallite size or the fluctuation of the optical system. Is. From this, the crystallite size of the Pt thin film is 2000 Å
It can be presumed from the above, and it was found that the crystallites (that is, grains) of 2 to 4 μm were formed based on the comprehensive judgment from the RHEED, the Reue image, the TEM image, and the surface morphology observation. P close to a single crystal thin film integrated with such a substrate
In the t thin film, the stress peculiar to the film is not concentrated on the defects, the stress is held in the entire film, and the film is easily peeled off in the case of poor adhesion. Therefore, in order to improve the adhesion to the substrate, it is necessary to form an appropriate stress concentration point. Therefore, these defects are formed by stacking faults (stacking faults) in crystal growth, and the crystallite size is made finer. Just do it. In the present invention, a Pt thin film integrated with a substrate is produced by sputtering. At that time, O 2 gas is introduced in addition to Ar gas which is usually used as a sputtering gas, and sputtering is performed with these mixed gases. The data are shown in Examples described later. However, when the O 2 gas is introduced, the (111) plane orientation should be (200).
It is based on the finding that surface growth is observed and the crystallite size is also small. This is Pt of oxygen ion
This is because the energy of collision with the target is smaller than that of Ar.
【0006】本発明による基板と一体化されたPt薄膜
は、それ自身が素子作製プロセス中で剥離を発生させる
ことなく、十分密着性が有るものであり、従って、各種
密着層を積層することなく、すなわち、積層による不具
合の発生がなくなり、良好な結果を与えるものである。
これら基板と一体化されたPt薄膜抵抗体は、通電する
ことにより加熱する、所謂発熱体として用いたり、正の
温度係数を利用した温度検出素子に用いたり、またこれ
らをマイクロブリッジ上に形成させた各種センサに用い
ることを特徴とするPt薄膜抵抗体素子、さらにそのセ
ンサ素子である。以下、実施例に基づき説明する。The Pt thin film integrated with the substrate according to the present invention itself has sufficient adhesiveness without causing peeling during the device manufacturing process, and therefore, without laminating various adhesive layers. That is, the occurrence of defects due to lamination is eliminated, and good results are provided.
The Pt thin film resistor integrated with these substrates is used as a so-called heat generating element that is heated by energization, a temperature detecting element using a positive temperature coefficient, or these are formed on a microbridge. And a Pt thin film resistor element which is used for various sensors, and a sensor element thereof. Hereinafter, description will be made based on examples.
【0007】[0007]
【実施例】(100)Siウエハ基板にTa2O5膜を
スパッタリング法により1.5μm堆積する。このTa
2O5膜はアモルファスである。次に、基板温度:20
0℃、Ar/O2流量比:3/1、スパッタ圧:0.7
×10−3Torr、スパッタパワー密度:3〜4W/
cm2にて膜厚1000ÅのPt薄膜を堆積する。この
時のPt薄膜のXRDパターンを図1に示す。また酸素
ガス導入なしでのPt薄膜のXRDパターンを図2に示
す。このように酸素ガス導入により(200)面配向が
出現し結晶子サイズが数百Å程の多結晶Pt薄膜が得ら
れた。詳細な実験の結果、酸素混合比の増加に伴い(2
00)面配向が増加し、酸素分圧50%で、(111)
面配向率は55%まで低下した。同様に結晶子サイズも
2000Å以上から酸素分圧の増加に伴い減少し、酸素
分圧25%で数百Åになり、それ以上の酸素分圧の増加
に対しては、減少は認められなかった。このように基板
上に各種配向度、結晶子の異なるPt薄膜を作製し、基
板とPt薄膜の密着強度を測定した。測定方法は引っ張
り法(peel test)で行った。薄膜、基板の境
界面に垂直な引っ張り応力を加えて、Pt薄膜を基板か
ら剥離させ、剥離に要した力を検出する方法である。剥
離試験板とPt薄膜の接着には、十分ヤング率の高いエ
ポキシ系接着剤を使用した。その結果を表1に示す。EXAMPLE A Ta 2 O 5 film is deposited on a (100) Si wafer substrate by sputtering to a thickness of 1.5 μm. This Ta
The 2 O 5 film is amorphous. Next, substrate temperature: 20
0 ° C., Ar / O 2 flow rate ratio: 3/1, sputtering pressure: 0.7
× 10 −3 Torr, sputter power density: 3 to 4 W /
A Pt thin film with a film thickness of 1000 Å is deposited at cm 2 . The XRD pattern of the Pt thin film at this time is shown in FIG. An XRD pattern of the Pt thin film without introducing oxygen gas is shown in FIG. Thus, the introduction of oxygen gas caused the (200) plane orientation to appear, and a polycrystalline Pt thin film having a crystallite size of several hundred Å was obtained. As a result of detailed experiments, as the oxygen mixture ratio increased (2
(00) plane orientation increases and oxygen partial pressure 50%, (111)
The plane orientation ratio was lowered to 55%. Similarly, the crystallite size decreased from 2000 Å or more with the increase of oxygen partial pressure to several hundred Å at the oxygen partial pressure of 25%, and no decrease was observed with the increase of the oxygen partial pressure beyond that. . In this way, Pt thin films having different orientations and different crystallites were formed on the substrate, and the adhesion strength between the substrate and the Pt thin film was measured. The measuring method was a tensile test. In this method, a tensile stress perpendicular to the boundary surface between the thin film and the substrate is applied to separate the Pt thin film from the substrate, and the force required for the separation is detected. An epoxy adhesive having a sufficiently high Young's modulus was used for bonding the peel test plate and the Pt thin film. The results are shown in Table 1.
【0008】[0008]
【表1】
従って従来の接着強度の10倍ほどの改善がなされた。
このPt薄膜抵抗体を用いて、図3に示す各種のマイク
ロセンサを試作した。図3は酸化物半導体の電荷吸着・
脱離現象による抵抗率変化を検出する所謂ガスセンサで
ある。Si基板上にマイクロブリッジ形成のための、絶
縁性アモルファス上のTa2O5膜をスパッタリング法に
より1.5μm堆積した。次に本発明に係るPt薄膜を
ArとO2の混合ガスによるスパッタリング法により1
000Å堆積させ、通常のフォトリソグラフィ・エッチ
ングにより薄膜ヒータを形成した。層間絶縁膜として、
Ta2O5膜、SiO2膜を製膜し、コンタクトホール開
孔、Si異方性エッチング用のエッチングホールを開孔
後、KOHのアルカリエッチングにより基板Siを除去
し、マイクロブリッジを得た。次にマスク蒸着により所
望する箇所に酸化スズ膜(酸化物半導体)の堆積を行っ
た。酸化スズの酸素の電荷吸着が生じる450℃まで、
Pt薄膜抵抗体に電流を流し発熱させ、駆動を行った。
このPt薄膜抵抗体は従来と同様の信頼性を有する薄膜
であった。図4は気体質量流量センサであり、本発明に
係るPt薄膜抵抗体を有するものである。この薄膜抵抗
体の抵抗率は18μΩ・cm、温度抵抗係数は2300
ppmであり、従来のPt薄膜での値:15μΩ・c
m、2570ppmと比較して、遜色のない値であり、
この質量流量センサを試作したところ、実用に値する特
性を示した。[Table 1] Therefore, an improvement of about 10 times the conventional adhesive strength was made.
Using this Pt thin film resistor, various microsensors shown in FIG. 3 were prototyped. Figure 3 shows the charge adsorption of oxide semiconductors.
This is a so-called gas sensor that detects a change in resistivity due to a desorption phenomenon. A Ta 2 O 5 film on an insulating amorphous film for depositing a microbridge was deposited on the Si substrate by a sputtering method to a thickness of 1.5 μm. Next, the Pt thin film according to the present invention is formed by a sputtering method using a mixed gas of Ar and O 2.
A thin film heater was formed by 000Å deposition and ordinary photolithography etching. As an interlayer insulating film,
After forming a Ta 2 O 5 film and a SiO 2 film and opening contact holes and etching holes for Si anisotropic etching, the substrate Si was removed by KOH alkali etching to obtain a microbridge. Next, a tin oxide film (oxide semiconductor) was deposited on a desired portion by mask vapor deposition. Up to 450 ℃, where oxygen adsorption of tin oxide occurs
The Pt thin film resistor was driven by applying an electric current to generate heat.
This Pt thin film resistor was a thin film having the same reliability as conventional ones. FIG. 4 shows a gas mass flow sensor having a Pt thin film resistor according to the present invention. This thin film resistor has a resistivity of 18 μΩ · cm and a temperature resistance coefficient of 2300.
ppm, value with conventional Pt thin film: 15 μΩ · c
m, a value comparable to 2570 ppm,
When this mass flow sensor was prototyped, it showed practically useful characteristics.
【0009】[0009]
【発明の効果】本発明によれば、Pt薄膜と基板との接
着強度が増し、強固な各種マイクロセンサ用Pt薄膜抵
抗体が得られ、その工業的価値は高い。According to the present invention, the adhesion strength between the Pt thin film and the substrate is increased, and a strong Pt thin film resistor for various microsensors can be obtained, and its industrial value is high.
【図1】Ar+O2混合ガスのスパッタリングによって
製膜したPt膜のXRDパターン。FIG. 1 is an XRD pattern of a Pt film formed by sputtering Ar + O 2 mixed gas.
【図2】Arガスのみのスパッタリングによって製膜し
たPt膜のXRDパターン。FIG. 2 is an XRD pattern of a Pt film formed by sputtering only Ar gas.
【図3】酸化物半導体の電荷吸着・脱離現象による抵抗
率変化を検出するマイクロガスセンサの平面を模式的に
示す図である。FIG. 3 is a diagram schematically showing a plane of a micro gas sensor for detecting a change in resistivity due to a charge adsorption / desorption phenomenon of an oxide semiconductor.
【図4】本発明のPt薄膜抵抗体を有する気体質量流量
センサの平面を模式的に示す図である。FIG. 4 is a diagram schematically showing a plane of a gas mass flow sensor having a Pt thin film resistor of the present invention.
1 エッチングホール 2 白金薄膜線 3 酸化物半導体層 4 マイクロブリッジ 5 白金薄膜ヒーター 6 コンタクトホール 7 温度測定線 8 温度測定線 1 Etching hole 2 Platinum thin film wire 3 Oxide semiconductor layer 4 micro bridge 5 Platinum thin film heater 6 contact holes 7 Temperature measurement line 8 temperature measurement line
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7,DB名) H01C 7/02 - 7/22 ─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. 7 , DB name) H01C 7/ 02-7/22
Claims (4)
度が60〜70%であり、かつ下式(II)で定義される
シェラーの関係式より求められる結晶子サイズが150
〜170ÅであるPt薄膜を有することを特徴とする基
板と一体化されたPt薄膜。 【数1】 〔(111)面配向度〕=〔I(111)/ΣI(hkl)〕×100 (I) 【数2】Dhkl=Kλ/βcosθ (II) 〔上式中、I(111)はXRD測定における(11
1)面回折強度、ΣI(hkl)は測定範囲内で測定さ
れる全ての回折強度の和、Dhklは(hkl)面に垂
直方向の結晶子の大きさ(Å)、λはX線の波長
(Å)、βは回折線幅(rad)、θは回折角(゜)で
ある。Kは定数であり、0.9である。〕1. An orientation degree defined by the following formula (I) is 60 to 70% on a substrate, and a crystallite size determined by Scherrer's relational formula defined by the following formula (II) is 150.
A Pt thin film integrated with a substrate, characterized in that it has a Pt thin film of ˜170Å. [Formula 1] [(111) plane orientation degree] = [I (111) / ΣI (hkl)] × 100 (I) D hkl = Kλ / β cosθ (II) [wherein I (111) ) Is (11) in XRD measurement
1) Plane diffraction intensity, ΣI (hkl) is the sum of all diffraction intensities measured in the measurement range, D hkl is the crystallite size (Å) perpendicular to the (hkl) plane, and λ is the X-ray The wavelength (Å), β is the diffraction line width (rad), and θ is the diffraction angle (°). K is a constant and is 0.9. ]
薄膜よりなる薄膜ヒータ。2. Pt integrated with the substrate of claim 1.
Thin film heater made of thin film.
薄膜よりなる正の温度係数を利用した温度検出素子。3. Pt integrated with the substrate of claim 1.
A temperature detection element that uses a positive temperature coefficient consisting of a thin film.
は請求項3記載の温度検出素子をマイクロブリッジ上に
有するガスセンサ。4. A gas sensor having the thin film heater according to claim 2 and / or the temperature detecting element according to claim 3 on a microbridge.
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JP35051693A JP3385087B2 (en) | 1993-12-28 | 1993-12-28 | Pt thin film integrated with substrate, thin film heater using the same, temperature detecting element and gas sensor |
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---|---|---|---|
JP35051693A JP3385087B2 (en) | 1993-12-28 | 1993-12-28 | Pt thin film integrated with substrate, thin film heater using the same, temperature detecting element and gas sensor |
Publications (2)
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JPH07201521A JPH07201521A (en) | 1995-08-04 |
JP3385087B2 true JP3385087B2 (en) | 2003-03-10 |
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ID=18411030
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JP2007243173A (en) * | 2006-02-09 | 2007-09-20 | Mitsui Mining & Smelting Co Ltd | Laminate, thin film sensor, and thin film sensor module |
EP1988554A1 (en) * | 2006-02-09 | 2008-11-05 | Mitsui Mining & Smelting Co., Ltd | Laminate, thin film sensor, thin film sensor module, and method for manufacturing the thin film sensor |
JP4811316B2 (en) * | 2007-03-28 | 2011-11-09 | 三菱マテリアル株式会社 | Thin film thermistor element and method for manufacturing thin film thermistor element |
JP5163276B2 (en) * | 2007-05-18 | 2013-03-13 | アズビル株式会社 | Manufacturing method of platinum resistance thermometer |
JP5163277B2 (en) * | 2007-05-18 | 2013-03-13 | 山里産業株式会社 | Method for manufacturing platinum resistance thermometer element |
JP5287017B2 (en) * | 2008-08-07 | 2013-09-11 | 山里産業株式会社 | Platinum resistance thermometer and method for manufacturing platinum resistance thermometer element |
DE112013003510T5 (en) * | 2012-07-13 | 2015-04-30 | Semitec Corp. | Thin-film thermistor element and method of making the same |
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