TFA Thin Film Analyzer

Transcription

1 TFA Thin Film Analyzer

2 Thin Film Analyzer LINSEIS Thin Film Analyzer (TFA) Motivation The LINSEIS Thin Film Analyzer is the perfect solution to characterize a broad range of thin film samples in a very comfortable and quick way. It is an easy to use, single stand alone system and delivers high quality results using an optimized measurement design as well as the proven LINSEIS Firmware and Software package. The big advantage of this system is the simultaneous determination of all interesting physical properties within one measurement run at one sample. Therefore all measured results are very comparable and errors due to different environmental conditions like sample geometry, composition or heat profile can be avoided. Another big advantage is the modular System design. If you only want to measure a part of the possible properties, you can start with a basic device and upgrade your system later if necessary. The characterization of the thermal properties of thin film materials is important both for understanding of their structure and conduction mechanisms and for their technical applications. LINSEIS TFA The TFA has been developed to reach highest demands on measurement requirements in a Temperature range from -150 C up to 400 C. Samples can be measured under the influence of a very strong magnetic field up to ±1 Tesla. Measurement Setup The System can also handle a very broad range of different materials. It is possible to measure samples with metallic behavior as well as ceramics or organics. Therefore many different deposition methods like PVD, CVD or Spin coating are possible to use. The measurements are taken using the very well known Van-der-Pauw Method and the 3w hot strip technique. 2

3 Measuring setup Packaging options Components The basic setup consists of a measurement chip on which the sample can be easily deposited and the measurement chamber to provide the required environmental conditions. Depending on the application, the setup can be utilized with a Lock-In amplifier and / or a strong electric magnet. The measurements are usually taken under UHV and the samples temperature can be controlled between 150 K and 700 K during the measurement using LN2 and powerful heaters. Because of easily with either the transient upgrade kit to measure the thermal conductivity and specific heat with the 3w Method or the magnetic upgrade kit to take Hall constant, mobility and charge carrier concentration measurements. Packaging options Following packaging options are available for the LINSEIS Thin Film Analyzer (TFA): 1. Basic device: Consists of measurement chamber, vacuum pump, basic sample holder with included heater, measurement electronics, PC and LINSEIS Software package. The design is optimized to measure following physical properties: l - Thermal Conductivity (steady state / in plane) r - Electrical Resistivity s - Electrical Conductivity S - Seebeck Coefficient e - Emissivity the symmetric and thermally optimized design, it is also possible to apply variable temperature gradients. Modular design Due to the unique optimized design of the system, different chips like the Lambda, Sigma or the ZT Chip can be used. As there are many different applications, it is also possible to create and use custom designed chips, to adapt customer requirements to the existing layout. Starting with a basic setup to measure, the System can be upgraded 2. Transient package: Consisting of system integrated lock-in amplifier, electronics and evaluation software for 3w- method. The design is optimized for measuring the following parameters: l - Thermal Conductivity (transient / in plane and cross plane) c p - Specific Heat 3. Magnetic package: Selection of integrated electrical magnet, depending on application requirements. The design is optimized for measuring the following parameters: A H - Hall Constant μ - Mobility n - Charge carrier concentration 4. Low temperature option for controlled cooling down to 100 K TFA/KREG controlled cooling unit TFA/KRYO Dewar 25l 3

4 Measuring principles 1. Van-der-Pauw Method The sample with a defi ned geometry gets connected by four electrodes. A current is applied between two of the contacts and the voltage between the remaining two is measured. The same procedure is done clockwise for other constellations and using the Van-der-Pauw equation, the resistivity of the sample can be calculated very exactly. By applying a magnetic fi eld and measuring the change of the Van-der-Pauw resistivity, the Hall coeffi cient of the sample can be measured using the same setup. The sample size is approx. 25 mm² and the possible specifi c resistivity to measure is from 0.1Ω up to 100 MΩ. With additional thermometers near the contacts, the Seebeck coeffi cient can be measured in different directions at the same sample. S Seebeck Coeffi cient 2. Hot stripe measurement Membrane (λ M d M ) Hot Wire Sample (λ S d S ) The sample is deposited on the bottom side of a very thin Membrane. A very samll wire is deposited on the topside of this Membrane. For the measurement, a current is applied to the hotwire which is heated up due to Joule heating. Because of the temperature rise, the resistivity of the wire is changing and can be measured easily. From this resistivity change, it is possible to calculate back to the thermal conductivity of the sample. This setup can be used either with a DC or AC (3w) current. Depending on the used method it is also possible to measure the emissivity and specifi c heat of the sample. Si Si To measeure high quality results, the sample thickness times sample thermal conductivity must be equal or bigger than 2 x 10E-7 W/K. 4

5 Measurements Thermal conductivity measurement (DC) 6 5 λ layer [W/(m K)] T 0 [K] Thermal conductivity of a Bi0.9Sb0.1 film with a thickness of 100nm as function of temperature. Specific heat measurement (AC 3w) c p [J/(cm 3 K)] T 0 [K] Specific heat capacity of a 30nm thin Ag film as function of temperature between 80 and 300K. 5

6 Thermal conductivity measurement (DC & AC) λ[w/(m K)] 1.5 steady-state transient Thermal conductivity of an 800nm thin SiO 2 / Si 3 N 4 sandwich, measured with the steady state (red) and the transient (blue) technique in the temperature range K T 0 [K] 6

7 Applications Thermoelectric devices A typical application is the characterization of thin films made out of thermoelectric materials. A lot of research is done to improve the efficiency of thermoelectric devices. Integrated devices For the development and design of new and robust integrated devices like sensors or microchips, the semiconducting industry needs to know a lot about the physical properties of the used films. For example for the heat management or the electric insolation of such devices. Thermal barrier coatings Another interesting field for thin films are thermal barrier coatings as they are used in aircraft engines. Many new materials have been developed and characterized, especially in regard to their thermal behavior. Tribological stress The last application example is the determination of material parameters for thin films used in tools. The understanding is very important to avoid wear due to tribological stress to ensure an extended product life cycle. 7

8 LINSEIS GmbH Vielitzerstr Selb Germany Tel.: (+49) Fax: (+49) LINSEIS Inc. 109 North Gold Drive Robbinsville, NJ USA Tel.: +01 (609) Fax: +01 (609) Products: DIL, TG, STA, DSC, HDSC, DTA, TMA, MS/FTIR, In-Situ EGA, Laser Flash, Seebeck Effect Services: Service Lab, Calibration Service