Submillimeter wave exclusive Fourier transform spectrophotometer
Technique for supporting far infrared measurement
Use of Martin · Puppett type interferometer and Michelson type interferometer properly
Since Michelson interferometer uses multiple reflection of the beam splitter thickness, it is necessary to increase the film thickness as the wave number becomes lower.
Therefore, the absorption of the film itself becomes large, and measurement in the low wavenumber region of 10 cm -1 or less becomes difficult.
In Japan, Martin-Paplet interferometer with efficiency of less than 100 cm -1 is available.
In the wave number range of 80 cm -1 or less, a high pressure mercury light source which is stronger than the ceramic light source is used as the light source of the equipment.
As a detector, DLATGS of PE window which operates at room temperature is installed inside.
In addition, since it is designed so that a bolometer detector can be attached to the outside, measurement with higher sensitivity can be performed.
Measurement of Z-cut Quartz
The range from 100 GHz to 10 THz exists at the boundary between light waves and radio waves, and it transmits nonmetal and nonpolar substances such as semiconductors, plastics, paper and rubber. It corresponds to reflection measurement as well as transmission measurement. Figure 1 shows an example of Z-cut Quartz measurement. In FARIS-1, emission light in the THz region can also be measured. The system is a complete vacuum enclosure.
Evaluation method of silicon wafer using light in terahertz region
Physical properties of semiconductor wafers using light in the terahertz region are being actively evaluated.
By using the light in the terahertz region, plasma absorption of low-doped wafers can be measured, and it is possible to evaluate the resistance value of wafers normally used in LSI.
When general silicon wafers are measured with FARIS-1, absorption of only free carriers is obtained, and as a result, carrier density and resistance can be calculated from the Drude equation.
It is also possible to estimate wafer thickness and film thickness from the interference pattern of the obtained spectrum.
- Electrical and optical properties of semiconductor wafers
- The thickness of the relatively rough film
- Crystal structure of semiconductor wafers and films
- The terahertz measurement system FARIS-1 has a very wide range of applied power.
|Measurement wavenumber range||650 to 2 cm -1|
|Disassembly||0.25 to 16 cm -1|
|Interferometer||45 ° incidence Michelson interferometer (Martin · puppet interferometer compatible)|
|Beam splitter||Mylar film B / S, wire grid B / S|
|light source||Water-cooled high-pressure mercury light source|
|Detector||PE window DTGS, bolometer|
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