JPS637618B2 - - Google Patents
Info
- Publication number
- JPS637618B2 JPS637618B2 JP55148209A JP14820980A JPS637618B2 JP S637618 B2 JPS637618 B2 JP S637618B2 JP 55148209 A JP55148209 A JP 55148209A JP 14820980 A JP14820980 A JP 14820980A JP S637618 B2 JPS637618 B2 JP S637618B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- measured
- film
- thermal conductivity
- substrate
- 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
Links
- 239000010409 thin film Substances 0.000 claims description 30
- 239000010408 film Substances 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 16
- 239000000758 substrate Substances 0.000 claims description 12
- 239000000126 substance Substances 0.000 claims description 11
- 230000008018 melting Effects 0.000 claims description 7
- 238000002844 melting Methods 0.000 claims description 7
- 238000005259 measurement Methods 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 238000009792 diffusion process Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000001678 irradiating effect Effects 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000004093 laser heating Methods 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/18—Investigating or analyzing materials by the use of thermal means by investigating thermal conductivity
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Description
【発明の詳細な説明】
本発明は、蒸着、スパツタ等の方法により基板
上に形成した薄膜の熱伝導率の評価法に関するも
のである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for evaluating the thermal conductivity of a thin film formed on a substrate by a method such as vapor deposition or sputtering.
従来、物質の熱伝導率の評価法として、試料に
熱源として連続発振のレーザ光を照射し、その部
分の温度変化を熱電対で測定する方法が用いられ
てきた。この方法は、レーザ照射部と非照射部の
温度差の変化を、熱拡散の理論式に代入し、その
方程式中に物質固有の定数として含まれる熱伝導
率を求めるものである。この方法によれば、十分
厚い試料に対しては良い精度で測定できるが、基
板上に形成した薄膜状試料に対しては、測定結果
が基板の熱伝導率の影響を強くうけるため、正確
な測定を期待することができないという欠点があ
つた。 Conventionally, as a method for evaluating the thermal conductivity of a substance, a method has been used in which a sample is irradiated with a continuous wave laser beam as a heat source and the temperature change in that area is measured with a thermocouple. In this method, the change in temperature difference between the laser irradiated area and the non-irradiated area is substituted into a theoretical equation for thermal diffusion, and the thermal conductivity included in the equation as a constant specific to the material is determined. According to this method, sufficiently thick samples can be measured with good accuracy, but for thin film samples formed on a substrate, the measurement results are strongly influenced by the thermal conductivity of the substrate, so it is not accurate. The drawback was that measurements could not be expected.
例えば、基板の厚さが１mm、薄膜の厚さが1μ
ｍのとき、薄膜は1000倍も厚い基板と接している
ため、熱伝達の速さは、基板の熱伝導率によつて
支配され、薄膜の熱伝導率は測定結果（レーザ照
射部と非照射部との温度差）にほとんど影響しな
い。即ち、測定対象の薄膜が基板よりはるかに薄
いということが、この方法の適用を難しくしてい
る原因であつた。 For example, the substrate thickness is 1mm and the thin film thickness is 1μ.
Since the thin film is in contact with a substrate 1000 times thicker when m temperature difference). That is, the fact that the thin film to be measured is much thinner than the substrate is what makes it difficult to apply this method.
近年、薄膜電子素子の最適設計や、集積回路素
子の放熱用伝熱体の設計等を行なう上に、薄膜物
質（例えばカーボン膜等）の熱伝導率測定がしば
しば重要になつている。しかし上述したように、
従来技術によつては測定が困難を極め、しかも精
度よい測定結果は得られていなかつた。 In recent years, measurement of the thermal conductivity of thin film materials (for example, carbon films) has often become important in the optimal design of thin film electronic devices and the design of heat transfer bodies for heat dissipation in integrated circuit devices. However, as mentioned above,
Measurement is extremely difficult using conventional techniques, and moreover, accurate measurement results have not been obtained.
本発明は、上記従来技術の欠点を解決するため
になされたもので、精度よく薄膜の熱伝導率測定
を行なう方法を提供することを目的とするもので
ある。 The present invention was made in order to solve the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a method for accurately measuring the thermal conductivity of a thin film.
上記の目的を達成するために、本発明の測定に
は、熱源としてパルス幅がサブマイクロ秒のパル
ス・レーザ光を用いている。これを基板上の薄膜
に照射して薄膜表面が特定温度に達するときのレ
ーザ光のエネルギー値から、薄膜の熱伝導率を求
めるものである。この温度の特定には、熱電対で
測定する等の方法もあるが、本発明では特に次の
方法を提案する。すなわち、薄膜表面に融点既知
の物質をさらに膜状につけ、レーザ加熱によりそ
の物質が溶融変形を起こすことを利用する。 In order to achieve the above object, the measurement of the present invention uses a pulsed laser beam with a sub-microsecond pulse width as a heat source. The thermal conductivity of the thin film is determined from the energy value of the laser beam when the thin film on the substrate is irradiated with this laser beam and the surface of the thin film reaches a specific temperature. Although there are methods such as measuring with a thermocouple to specify this temperature, the following method is particularly proposed in the present invention. That is, the method utilizes the fact that a substance with a known melting point is further applied to the surface of the thin film in the form of a film, and the substance is melted and deformed by laser heating.
なお、パルス・レーザ光を用いるのは、既知の
エネルギーを持つたパルスを一発ずつ照射するた
めと、短い幅のパルスで照射することにより測定
対象薄膜における熱拡散がその薄膜表面近傍に限
られるからである。 Note that pulsed laser light is used because it irradiates pulses with known energy one by one, and by irradiating with short width pulses, heat diffusion in the thin film to be measured is limited to the vicinity of the thin film surface. It is from.
以下、本発明を図面を用いて詳細に説明する。 Hereinafter, the present invention will be explained in detail using the drawings.
第１図は本発明の一実施例を示すもので、同図
ａは薄膜の熱伝導率の測定系を示す模式図、ｂは
その系の温度プロフアイルを示す図である。 FIG. 1 shows an embodiment of the present invention. FIG. 1A is a schematic diagram showing a system for measuring the thermal conductivity of a thin film, and FIG. 1B is a diagram showing a temperature profile of the system.
基板１上に測定対象の薄膜物質２（こゝでは一
例として膜厚を5000Åとした）がある。さらに、
その上に融点が低くかつ既知の物質の膜３（こゝ
では一例として膜厚を500Åとした）をのせる。
この膜３としては、低融点であるばかりでなく、
照射するレーザ光の反射が少ない物質の膜である
ことが望ましい。例えば熱源用高出力のパルスレ
ーザとして炭酸ガスレーザを用いるとすると、そ
のレーザ光（波長10.6μｍ）を100％近く吸収する
物質として錫Sn、鉛Pbを用いることができる。
もし、膜３によるレーザ光の反射が大きい場合に
は、その反射率を測定し、吸収されるエネルギー
の値を補正すればよい。 There is a thin film substance 2 to be measured (here, the film thickness is 5000 Å as an example) on a substrate 1. moreover,
A film 3 made of a known substance with a low melting point (here, the film thickness is 500 Å as an example) is placed on top of the film.
This film 3 not only has a low melting point but also
It is desirable that the film be made of a material that reflects less of the irradiated laser light. For example, if a carbon dioxide laser is used as a high-output pulse laser for a heat source, tin, Sn, and lead Pb can be used as substances that absorb nearly 100% of the laser light (wavelength: 10.6 μm).
If the reflection of the laser beam by the film 3 is large, the reflectance may be measured and the value of absorbed energy may be corrected.
上記膜３は蒸着等の方法により測定対象の薄膜
物質２上に作成される。この系に上方からパル
ス・レーザ光４を照射すると、このレーザ光４は
膜３内で吸収され熱に変つて測定対象の薄膜物質
２内を拡散してゆく。熱拡散の理論解析によれ
ば、この場合の系の温度プロフアイルは第１図ｂ
のようになり、膜３の温度は測定対象の薄膜物質
２の熱伝導率により決定される。薄膜表面を顕微
鏡観察しながらパルス・レーザ・エネルギーを低
い方から高い値へと順次変えて行き、膜３が溶融
して変形を起こすパルス・レーザ光のエネルギー
値を求め、その値を熱拡散方程式
Ｋ∂2T／∂x2−cρ∂T／∂t＝Ｆ（ｔ）
（但し、Ｔ：温度、ｘ：膜の深さ方向の位置、
ｃ：比熱、ρ：密度、ｔ：時間、Ｆ（ｔ）：吸収さ
れるレーザ・エネルギー値である。）
に代入して、測定対象の薄膜物質２の熱伝導率Ｋ
を求める。 The film 3 is formed on the thin film material 2 to be measured by a method such as vapor deposition. When this system is irradiated with pulsed laser light 4 from above, the laser light 4 is absorbed within the film 3, converted to heat, and diffused within the thin film material 2 to be measured. According to the theoretical analysis of thermal diffusion, the temperature profile of the system in this case is shown in Figure 1b.
The temperature of the film 3 is determined by the thermal conductivity of the thin film material 2 to be measured. While observing the thin film surface with a microscope, the pulsed laser energy is sequentially changed from low to high, and the energy value of the pulsed laser light that causes the film 3 to melt and deform is determined, and this value is calculated using the thermal diffusion equation. K∂ 2 T/∂x 2 −cρ∂T/∂t=F(t) (where, T: temperature, x: position in the depth direction of the film,
c: specific heat, ρ: density, t: time, F(t): absorbed laser energy value. ) to obtain the thermal conductivity K of the thin film material 2 to be measured.
seek.
この方法によれば、試料表面の熱伝導およびそ
の溶融状態のみが測定に関与するため基板の影響
を排除することができる。熱伝導による温度変化
を表面近傍に限定するため、実際の測定には、レ
ーザのパルス幅は1μs以下が適している。なお、
レーザ照射部は１mmφ以下が望ましく、そこえパ
ルス一発当り例えば数ｍＪのエネルギーが集中さ
れる。 According to this method, only the thermal conduction of the sample surface and its molten state are involved in the measurement, so the influence of the substrate can be eliminated. In order to limit temperature changes due to heat conduction to the vicinity of the surface, a laser pulse width of 1 μs or less is suitable for actual measurements. In addition,
The laser irradiation part is preferably 1 mmφ or less, and energy of, for example, several mJ is concentrated therein per pulse.
以上説明したように、本発明の薄膜の熱伝導率
測定方法は、測定対象物表面に、融点が低く、レ
ーザ光を吸収する既知物質の膜を作成し、それに
サブマイクロ秒の幅のパルス・レーザ光を照射
し、表面の溶融を生ずるレーザ光のエネルギー値
を熱拡散方程式に代入することにより、測定対象
物の熱伝導率を測定するものである。 As explained above, the method for measuring the thermal conductivity of a thin film according to the present invention involves creating a film of a known substance with a low melting point and absorbing laser light on the surface of the object to be measured, and applying pulses of submicrosecond width to the film of a known substance that has a low melting point and absorbs laser light. The thermal conductivity of the object to be measured is measured by irradiating it with a laser beam and substituting the energy value of the laser beam that causes the surface to melt into the thermal diffusion equation.
本発明の方法によれば、測定が基板の影響をほ
とんどうけないため、膜厚1μｍ以下の薄膜でも
精度よく熱伝導率を測定できる利点がある。 According to the method of the present invention, since the measurement is hardly affected by the substrate, there is an advantage that the thermal conductivity can be measured with high accuracy even in a thin film having a thickness of 1 μm or less.
従来、困難とされていた薄膜の熱伝導率を本発
明により精度よく評価できれば、集積回路等の薄
膜電子素子の最適設計を図る上で非常に有効であ
り、その効果はきわめて大きい。 If the present invention can accurately evaluate the thermal conductivity of thin films, which has been considered difficult in the past, it will be very effective in optimally designing thin film electronic devices such as integrated circuits, and its effects will be extremely large.
第１図は本発明の一実施例を示すもので、同図
ａは薄膜の熱伝導率の測定系を示す模式図、ｂは
その系の温度プロフアイルを示す図である。
１…基板、２…測定対象の薄膜物質、３…融点
が低く既知の物質の膜、４…パルス・レーザ光。
FIG. 1 shows an embodiment of the present invention. FIG. 1A is a schematic diagram showing a system for measuring the thermal conductivity of a thin film, and FIG. 1B is a diagram showing a temperature profile of the system. 1...Substrate, 2...Thin film material to be measured, 3...Film of a known substance with a low melting point, 4...Pulsed laser light.
Claims (1)
吸収する、融点既知の物質を膜状に付着し、これ
にサブマイクロ秒の幅のパルス・レーザ光を照射
し、上記物質に溶融を生じさせるレーザ光のエネ
ルギー値から上記測定対象薄膜の熱伝導率を算出
することを特徴とする薄膜の熱伝導率の測定方
法。1 A film of a substance with a known melting point that absorbs laser light is attached to the surface of a thin film to be measured on a substrate, and this is irradiated with pulsed laser light with a sub-microsecond width to cause the substance to melt. A method for measuring the thermal conductivity of a thin film, comprising calculating the thermal conductivity of the thin film to be measured from the energy value of the laser beam.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14820980A JPS5772052A (en) | 1980-10-24 | 1980-10-24 | Measuring method for heat transmission factor of thin film |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14820980A JPS5772052A (en) | 1980-10-24 | 1980-10-24 | Measuring method for heat transmission factor of thin film |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5772052A JPS5772052A (en) | 1982-05-06 |
| JPS637618B2 true JPS637618B2 (en) | 1988-02-17 |
Family
ID=15447700
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14820980A Granted JPS5772052A (en) | 1980-10-24 | 1980-10-24 | Measuring method for heat transmission factor of thin film |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5772052A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59210352A (en) * | 1983-05-16 | 1984-11-29 | Nippon Telegr & Teleph Corp <Ntt> | Method and device for measuring thermal conductivity |
| JPS6110752A (en) * | 1984-06-26 | 1986-01-18 | Ichiro Hatta | Measurement for diffusitivity of heat by intermittent heating |
| JPS61205162A (en) * | 1985-03-08 | 1986-09-11 | Brother Ind Ltd | Paper feeder |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5060271A (en) * | 1973-09-26 | 1975-05-24 |
-
1980
- 1980-10-24 JP JP14820980A patent/JPS5772052A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5060271A (en) * | 1973-09-26 | 1975-05-24 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5772052A (en) | 1982-05-06 |
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