JP2700332B2 - Film stress measurement method using surface acoustic wave device - Google Patents
Film stress measurement method using surface acoustic wave deviceInfo
- Publication number
- JP2700332B2 JP2700332B2 JP24559188A JP24559188A JP2700332B2 JP 2700332 B2 JP2700332 B2 JP 2700332B2 JP 24559188 A JP24559188 A JP 24559188A JP 24559188 A JP24559188 A JP 24559188A JP 2700332 B2 JP2700332 B2 JP 2700332B2
- Authority
- JP
- Japan
- Prior art keywords
- piezoelectric material
- thin film
- oscillation circuit
- thin
- acoustic wave
- 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.)
- Expired - Lifetime
Links
- 238000010897 surface acoustic wave method Methods 0.000 title claims description 16
- 238000000691 measurement method Methods 0.000 title 1
- 239000010409 thin film Substances 0.000 claims description 36
- 230000010355 oscillation Effects 0.000 claims description 33
- 239000000463 material Substances 0.000 claims description 23
- 239000010408 film Substances 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 8
- 230000003068 static effect Effects 0.000 claims description 4
- 239000013078 crystal Substances 0.000 claims description 2
- 239000010453 quartz Substances 0.000 claims description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 2
- 238000000151 deposition Methods 0.000 claims 1
- 230000000694 effects Effects 0.000 description 6
- 238000001771 vacuum deposition Methods 0.000 description 4
- 239000000758 substrate Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
- 238000001947 vapour-phase growth Methods 0.000 description 1
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、弾性表面波デバイスを用いた膜応力測定方
法に関する。The present invention relates to a method for measuring a film stress using a surface acoustic wave device.
（従来の技術） 従来、真空蒸着、スパッタリング、その他気相成長な
どで薄膜が形成されるが、該薄膜中には、薄膜、基板の
物質、薄膜形成の条件によって異なるが、多かれ少なか
れ内部応力が必ず存在する。薄膜の耐久性、薄膜形成を
用いて作られる集積回路の性能の安定性を考えるとき、
内部応力は大きな要因をなすので、この内部応力を測定
することは必要である。(Prior art) Conventionally, a thin film is formed by vacuum deposition, sputtering, or other vapor phase growth. In the thin film, depending on the thin film, the material of the substrate, and the conditions for forming the thin film, the internal stress is more or less. Always exists. When considering the durability of thin films and the stability of performance of integrated circuits made using thin film formation,
Since internal stress is a major factor, it is necessary to measure this internal stress.
従来、薄膜の内部応力（膜応力）の測定方法として、
基板の曲率を、該基板に薄膜を付着する前及び後におい
て測定し、その差より膜応力により曲げモーメントを求
め、膜応力が求められた。Conventionally, as a method of measuring the internal stress (film stress) of a thin film,
The curvature of the substrate was measured before and after the thin film was attached to the substrate, and the bending moment was determined from the difference between the two before calculating the film stress, and the film stress was determined.
（発明が解決しようとする課題） 従来の前記方法は手数がかかり、膜生成時に測定する
ことが困難であるという課題があった。(Problem to be Solved by the Invention) The conventional method is troublesome, and has a problem that it is difficult to measure at the time of film formation.
本発明は、従来のこのような課題を解決することをそ
の目的とするものである。An object of the present invention is to solve such a conventional problem.
（課題を解決するための手段） 本発明は、上記の目的を達成するために、薄膜生成空
間に挿入された圧電材料薄板の第１の面に薄膜を付着さ
せる手段と、前記圧電材料薄板の第２の面に付着された
一対の相貫櫛形電極間の弾性表面波共振を用いた発振回
路と、該発振回路の発振周波数を測定する手段とを備
え、前記圧電材料薄板の第１の面に付着した薄膜の膜応
力が前記第２の面に作る歪に比例した前記発振周波数の
変化分を前記測定手段で測定し、該変化分より前記付着
した薄膜の膜応力を薄膜生成時に測定することを特徴と
し、薄膜生成空間に挿入され、第１の面に薄膜が付着し
ないようにされた第２の圧電材料薄板と、該第２の圧電
材料薄板の第２の面に付着された一対の相貫櫛形電極間
の弾性表面波共振を用いた第２の発振回路と、該第２の
発振回路の発振周波数を測定する手段とを備え、前記第
２の圧電材料薄板及び前記第２の発振回路は、前記第１
の圧電材料薄板及び前記第１発振回路と同じであり、該
第１の発振回路の発振周波数の変化分から該第２の発振
回路の発振周波数の変化分を差し引くことによって発振
周波数に及ぼう静圧力、温度等の影響を除くようにする
ことが好ましい。(Means for Solving the Problems) In order to achieve the above object, the present invention provides means for attaching a thin film to a first surface of a piezoelectric material thin plate inserted into a thin film forming space, An oscillation circuit using surface acoustic wave resonance between a pair of intermeshed comb electrodes attached to the second surface; and a means for measuring an oscillation frequency of the oscillation circuit, wherein the first surface of the piezoelectric material thin plate is provided. The measuring means measures a change in the oscillation frequency in which the film stress of the thin film attached to the surface is proportional to the strain created on the second surface, and measures the film stress of the attached thin film at the time of forming the thin film from the change. A second thin sheet of piezoelectric material inserted into the thin film forming space to prevent the thin film from adhering to the first face, and a pair of thin sheets of piezoelectric material adhered to the second face of the second thin sheet of piezoelectric material. A second oscillation circuit using surface acoustic wave resonance between the interdigital transducers; Means for measuring an oscillation frequency of the second oscillation circuit, wherein the second piezoelectric material thin plate and the second oscillation circuit
And a static pressure exerted on the oscillation frequency by subtracting the change in the oscillation frequency of the second oscillation circuit from the change in the oscillation frequency of the first oscillation circuit. It is preferable to eliminate the influence of temperature, temperature and the like.
（作 用） 圧電材料薄板の面に一対の相貫櫛形電極が形成された
弾性表面波デバイスの該薄板の電極形成面に薄膜を形成
した時、弾性表面波共振周波数は膜応力等によって摂動
することがシンハ氏等によって理論的に解析された（J.
Appl.Phys.49（１）、January 1978、第87頁〜第95頁の
H.F.Tiersten and B.K.Sinha「A perturbation analysi
s of the attenuation and dispersion of surface wav
e」の論文参照）。(Operation) When a thin film is formed on an electrode forming surface of a surface acoustic wave device having a pair of intermeshed comb-shaped electrodes formed on a surface of a piezoelectric material thin plate, the surface acoustic wave resonance frequency is perturbed by film stress or the like. Was theoretically analyzed by Shinha et al. (J.
Appl. Phys. 49 (1), January 1978, pp. 87-95.
HFTiersten and BKSinha `` A perturbation analysi
s of the attenuation and dispersion of surface wav
e)).
ところで、その理論式によれば、内部応力を持った薄
膜が形成された場合の共振周波数の変化割合は、膜厚は
比例し、膜応力、薄膜の弾性及び密度及び質量荷重効果
に影響されることが解るが、本発明者の実験によれば、
この共振周波数の変化に影響を及ぼす諸要因のうち質量
荷重効果の与える影響は非常に大きく、その影響下に膜
応力の影響が隠れてしまうことが分った。By the way, according to the theoretical formula, the change rate of the resonance frequency when a thin film having an internal stress is formed is proportional to the film thickness, and is affected by the film stress, the elasticity and density of the thin film, and the mass load effect. As you can see, according to our experiments,
Among the various factors affecting the change in the resonance frequency, the effect of the mass load effect is very large, and it has been found that the influence of the film stress is hidden under the influence.
本発明によれば、弾性表面波デバイスの圧電材料薄板
における非電極形成面に薄膜を形成すると、その膜応力
により圧電材料薄板の電極形成面には、電極形成面に薄
膜を形成した場合の1/2で符号が反対の歪を発生し、そ
の歪によってのみ弾性表面波共振周波数に影響を与え、
質量荷重効果は該共振周波数の変化に影響を与えない。According to the present invention, when the thin film is formed on the non-electrode forming surface of the piezoelectric material thin plate of the surface acoustic wave device, the film stress causes the electrode forming surface of the piezoelectric material thin plate to have a smaller thickness than the case where the thin film is formed on the electrode forming surface. / 2 generates the opposite distortion of the sign, affects the surface acoustic wave resonance frequency only by the distortion,
The mass loading effect does not affect the change in the resonance frequency.
（実施例） 以下本発明の実施例を図面につき説明する。Embodiment An embodiment of the present invention will be described below with reference to the drawings.
第１図は、本発明方法の実施に使用する真空蒸着によ
る薄膜形成装置を示す。同図において、１は薄膜の内部
応力を測定するための弾性表面波デバイスで、該デバイ
ス１は、圧電材料薄板1aの一方の面に一対の相貫櫛形電
極1bを設けて構成されており、その他方の面を表側にし
て取付基板２に指示されるようにする。該圧電材料薄板
1aには、共振周波数が91.25及び97.25MHzのSTカット水
晶を使用した。１′は前記デバイス１の薄膜の内部応力
に対する静圧力、温度等の影響を除くために使用する参
照用素子としての第２の弾性表面波デバイスで、該デバ
イス１′は、前記デバイス１と同じ圧電材料薄板1aの一
方の面に該デバイス１と同じ一対の相貫櫛形電極1bを設
けて構成されており、その他方の面にも薄膜が形成され
ないようにカバー３が施されて取付基板２に指示される
ようにする。４はヒーター５により加熱されるAgの蒸発
源で、前記第１及び第２弾性表面波デバイス１、１′と
共に真空室６の中に収容される。該室６は排気口７より
真空ポンプ（図示せず）によって10-4torrに排気され、
該室６内で真空蒸着が行われるようになっている。FIG. 1 shows an apparatus for forming a thin film by vacuum evaporation used for carrying out the method of the present invention. In FIG. 1, reference numeral 1 denotes a surface acoustic wave device for measuring the internal stress of a thin film, and the device 1 is provided with a pair of interdigital transducers 1b on one surface of a piezoelectric material thin plate 1a. The other surface is turned to the front side so as to be instructed by the mounting board 2. The piezoelectric material thin plate
For 1a, ST-cut quartz crystals having resonance frequencies of 91.25 and 97.25 MHz were used. 1 'is a second surface acoustic wave device as a reference element used for removing the influence of static pressure, temperature, etc. on the internal stress of the thin film of the device 1, and the device 1' is the same as the device 1 A piezoelectric material thin plate 1a is provided with a pair of intermeshed comb-shaped electrodes 1b on one surface of the device 1, and a cover 3 is provided on the other surface so that a thin film is not formed. As instructed. Reference numeral 4 denotes an evaporation source of Ag heated by a heater 5 and is housed in a vacuum chamber 6 together with the first and second surface acoustic wave devices 1 and 1 '. The chamber 6 is evacuated to 10 -4 torr by a vacuum pump (not shown) from an exhaust port 7.
Vacuum deposition is performed in the chamber 6.
前記デバイス１及び１′の各一対の相貫櫛形電極1b、
1bは、第２図示のように発振回路８に接続され、該発振
回路８は、周波数カウンタ９に接続されている。両発振
回路８は同じものを用いた。A pair of comb-through electrodes 1b of each of said devices 1 and 1 ',
1b is connected to an oscillation circuit 8 as shown in FIG. 2, and the oscillation circuit 8 is connected to a frequency counter 9. The same oscillation circuit 8 was used.
かくて真空蒸着による薄膜形成装置の作動によってデ
バイス１の電極1bが施されてない他方の面にAgの薄膜が
形成されたとき、その膜応力に応じて該電極1bに接続さ
れた発振回路８の発振する共振周波数が変化し、その変
化分は周波数カウンタ９で測定される。Thus, when the Ag thin film is formed on the other surface of the device 1 on which the electrode 1b is not applied by the operation of the thin film forming apparatus by vacuum deposition, the oscillation circuit 8 connected to the electrode 1b according to the film stress. Is changed, and the change is measured by the frequency counter 9.
一方、デバイス１′の相貫櫛形電極1bに接続された発
振回路８の発振する共振周波数の変化分も周波数カウン
タ９で測定される。そこで、デバイス１の周波数変化分
からデバイス１′の周波数変化分を差し引くことにより
静圧力、温度等に影響されない、膜厚の増加に対してほ
ぼ直線的に増加する共振周波数の変化が、理論値の変化
のオーダと一致した10ppmのオーダで得られ、この共振
周波数の変化より薄膜の内部応力を求めた。On the other hand, the frequency counter 9 also measures the change in the oscillating resonance frequency of the oscillation circuit 8 connected to the interdigital transducer 1b of the device 1 '. Therefore, by subtracting the frequency change of the device 1 ′ from the frequency change of the device 1, the change in the resonance frequency, which is not affected by the static pressure, the temperature, etc. and increases almost linearly with the increase in the film thickness, becomes the theoretical value. It was obtained on the order of 10 ppm which coincided with the order of the change, and the internal stress of the thin film was determined from the change of the resonance frequency.
なお、前記と同じ真空蒸着装置を用いて、弾性表面波
デバイス１の相貫櫛形電極1bを設けた面に前記と同じ条
件でAgの薄膜を形成して、前記と同じように共振周波数
の変化を測定したところ論理値のオーダより非常に大き
い100ppmのオーダであった。In addition, by using the same vacuum deposition apparatus as above, a thin film of Ag was formed on the surface of the surface acoustic wave device 1 on which the interdigital transducer 1b was provided under the same conditions as above, and the resonance frequency was changed in the same manner as above. Was found to be on the order of 100 ppm, which is much larger than the order of the logical values.
（発明の効果） 本発明によれば、上記の構成により、手数がかから
ず、また膜生成時にも膜応力を容易に測定することがで
きる効果を有する。(Effects of the Invention) According to the present invention, the above configuration has an effect that the number of steps is reduced and the film stress can be easily measured even when the film is formed.
【図面の簡単な説明】 第１図は、本発明方法の実施に使用する薄膜形成装置の
構成説明図、第２図は本発明方法の実施に使用する回路
のブロック図である。 １、１′……弾性表面波デバイス 1a……圧電材料薄板 1b……相貫櫛形電極 ８……発振回路 ９……周波数カウンタBRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a configuration of a thin film forming apparatus used for carrying out the method of the present invention, and FIG. 2 is a block diagram of a circuit used for carrying out the method of the present invention. 1, 1 ': surface acoustic wave device 1a: thin piezoelectric material plate 1b: interdigital transducer 8: oscillation circuit 9: frequency counter
フロントページの続き (56)参考文献 特開 平１−321329（ＪＰ，Ａ) 特開 昭64−43735（ＪＰ，Ａ) 特開 昭63−36132（ＪＰ，Ａ) 特開 昭62−169029（ＪＰ，Ａ) 特開 昭63−307326（ＪＰ，Ａ)Continuation of front page (56) References JP-A-1-321329 (JP, A) JP-A-64-43735 (JP, A) JP-A-63-36132 (JP, A) JP-A-62-169029 (JP, A) , A) JP-A-63-307326 (JP, A)
Claims (3)
第１の面に薄膜を付着させる手段と、前記圧電材料薄板
の第２の面に付着された一対の相貫櫛形電極間の弾性表
面波共振を用いた発振回路と、該発振回路の発振周波数
を測定する手段とを備え、前記圧電材料薄板の第１の面
に付着した薄膜の膜応力が前記第２の面に作る歪に比例
した前記発振周波数の変化分を前記測定手段で測定し、
該変化分より前記付着した薄膜の膜応力を薄膜生成時に
測定することを特徴とする弾性表面波デバイスを用いた
膜応力測定方法。1. A means for depositing a thin film on a first surface of a piezoelectric material thin plate inserted into a thin film forming space, and an elasticity between a pair of interdigital transducer electrodes attached to a second surface of the piezoelectric material thin plate. An oscillation circuit using surface wave resonance; and means for measuring an oscillation frequency of the oscillation circuit, wherein a film stress of a thin film adhered to the first surface of the piezoelectric material thin plate reduces distortion generated on the second surface. The proportional change in the oscillation frequency is measured by the measuring means,
A film stress measuring method using a surface acoustic wave device, wherein the film stress of the attached thin film is measured from the change when the thin film is formed.
を特徴とする請求項１記載の弾性表面波デバイスを用い
た膜応力測定方法。2. The method according to claim 1, wherein said piezoelectric material is ST-cut quartz crystal.
が付着しないようにされた第２の圧電材料薄板と、該第
２の圧電材料薄板の第２の面に付着された一対の相貫櫛
形電極間の弾性表面波共振を用いた第２の発振回路と、
該第２の発振回路の発振周波数を測定する手段とを備
え、前記第２の圧電材料薄板及び前記第２の発振回路
は、前記第１の圧電材料薄板及び前記第１の発振回路と
同じであり、該第１の発振回路の発振周波数の変化分か
ら該第２の発振回路の発振周波数の変化分を差し引くこ
とによって発振周波数に及ぼす静圧力、温度等の影響を
除くようにしたことを特徴とする請求項１記載の弾性表
面波デバイスを用いた膜応力測定方法。3. A second thin sheet of piezoelectric material inserted into the thin film forming space to prevent the thin film from adhering to the first surface, and a pair of thin sheets of piezoelectric material attached to the second surface of the second thin piezoelectric material plate. A second oscillation circuit using surface acoustic wave resonance between the interdigital transducers;
Means for measuring the oscillation frequency of the second oscillation circuit, wherein the second piezoelectric material thin plate and the second oscillation circuit are the same as the first piezoelectric material thin plate and the first oscillation circuit. In addition, by subtracting the change in the oscillation frequency of the second oscillation circuit from the change in the oscillation frequency of the first oscillation circuit, the influence of static pressure, temperature, etc. on the oscillation frequency is removed. A method for measuring film stress using the surface acoustic wave device according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24559188A JP2700332B2 (en) | 1988-09-29 | 1988-09-29 | Film stress measurement method using surface acoustic wave device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24559188A JP2700332B2 (en) | 1988-09-29 | 1988-09-29 | Film stress measurement method using surface acoustic wave device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0293333A JPH0293333A (en) | 1990-04-04 |
| JP2700332B2 true JP2700332B2 (en) | 1998-01-21 |
Family
ID=17136006
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24559188A Expired - Lifetime JP2700332B2 (en) | 1988-09-29 | 1988-09-29 | Film stress measurement method using surface acoustic wave device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2700332B2 (en) |
-
1988
- 1988-09-29 JP JP24559188A patent/JP2700332B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0293333A (en) | 1990-04-04 |
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