Specific Process Knowledge/Characterization/Topographic measurement: Difference between revisions
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=Topographic measurements= | |||
Topographic measurements are measurements of height differences on your sample. If you measure many spots on the sample you can get a topographic image of the surface. | Topographic measurements are measurements of height differences on your sample. If you measure many spots on the sample you can get a topographic image of the surface. | ||
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*AFMs (AFM Icon-PT1 and AFM Icon-PT2) - ''AFMs for measuring nano structures'' | *AFMs (AFM Icon-PT1 and AFM Icon-PT2) - ''AFMs for measuring nano structures'' | ||
==High Aspect ratio structures==<br/> | |||
The fact that the stylus tip of a Dektak profilers or an AFM is shaped like a cone with some finite tip angle causes a problem when characterizing high aspect ratio structures. For instance, if a 20 µm wide trench is etched deeper than approximately 18 µm, the tip of the Dektak will not be able to reach the bottom. The optical profiler uses a light beam that is focused through an objective. Therefore it is able to measure higher aspect ratios. The aspect ratio is limited by the possibility for the light to reach the bottom and get back to the detector. On some samples we have been able to measure aspect ratios above 1:10. Otherwise the solution is to cleave the sample along a line that is perpendicular to the trench and then inspect the profile in a [[Specific Process Knowledge/Characterization/SEM: Scanning Electron Microscopy|scanning electron microscope]] or a microscope (for large structures). | The fact that the stylus tip of a Dektak profilers or an AFM is shaped like a cone with some finite tip angle causes a problem when characterizing high aspect ratio structures. For instance, if a 20 µm wide trench is etched deeper than approximately 18 µm, the tip of the Dektak will not be able to reach the bottom. The optical profiler uses a light beam that is focused through an objective. Therefore it is able to measure higher aspect ratios. The aspect ratio is limited by the possibility for the light to reach the bottom and get back to the detector. On some samples we have been able to measure aspect ratios above 1:10. Otherwise the solution is to cleave the sample along a line that is perpendicular to the trench and then inspect the profile in a [[Specific Process Knowledge/Characterization/SEM: Scanning Electron Microscopy|scanning electron microscope]] or a microscope (for large structures). | ||
==Measurements of thin film thickness== | |||
It is possible to use the profilers for measuring the thickness of optically transparent thin films or of etched non-transparent thin films. There are also other options for measuring film thickness. All the methods are compared on the [[Specific Process Knowledge/Characterization/Measurement of film thickness and optical constants|Thin film thickness and optical constants measurement page]] | |||
===Comparison of the stylus profilers, the optical profilers and the AFMs=== | ===Comparison of the stylus profilers, the optical profilers and the AFMs=== | ||