In semiconductor wafer manufacturing, flat panel display coating, or university new material research and development, the control of film thickness and step height directly determines product yield. The application of non-contact profilometer has become the core technical means in this field. So, how does the application of non-contact profilometer achieve film thickness measurement? What are the irreplaceable advantages of it compared to traditional contact methods?
The non-contact profilometer is used to analyze the spacing and shape of these interference fringes, and calculate the thickness or step height of the film using algorithms. The entire process does not touch the surface of the sample at all, avoiding the risk of probes scratching brittle materials such as sapphire and GaN wafers. This is one of the reasons why non-contact profilometers are widely used in the semiconductor and panel industries.
The first step is sample placement and autofocus: Place the test film sample on the stage, and the device automatically searches for the focal plane through a vertical scanning mechanism. The entire process does not require human intervention.
Step 2, select the measurement area: locate the edge or scratch of the film to be measured using a high-definition camera. For measuring the height of steps, it usually spans both the covered and uncovered areas of the film.
Step three, perform scanning: activate the white light vertical scanning interference mode. The optical lens moves vertically with sub nanometer step sizes, capturing an interferogram with each step of movement.
Step 4, Data Processing and Output: The software extracts the maximum contrast position of each pixel in all interferograms and reconstructs the three-dimensional morphology of the sample surface. The final film thickness value is directly given (usually in nm or μ m).
Non destructive and fast: The stylus type requires physical contact and may leave scratches on soft thin films such as photoresist and organic light-emitting layers; The non-contact profilometer application completely avoids this damage.
Suitable for large curvature or soft surfaces: For samples such as wafer warpage and flexible display screens, the stylus may not be able to closely follow the surface undulations, while non-contact profilometer applications are perfectly solved through optical principles.
More comprehensive data: One scan can obtain three-dimensional data of millions of points within the entire field of view, rather than cross-sectional data of a single line. This is particularly crucial when calculating the uniformity of thin films.
Among the solutions provided by Unicon Technology to over 300 universities and research institutes in China, non-contact profilometers have become a standard configuration in material characterization laboratories.
Semiconductor manufacturing: measuring the thickness of photoresist film on wafers, indentation and erosion after CMP (chemical mechanical polishing), and etching groove depth. A survey of over 2000 customers shows that the introduction of this technology has resulted in an average increase of 40% in process anomaly detection efficiency.
Panel industry: Testing the thickness of each organic layer of OLED (organic light-emitting diode) and the gate step of TFT (thin film transistor). Due to the extreme sensitivity of these film layers to scratches, non-contact profilometer application is the only feasible measurement option.
University research: Verify the continuity of thin films after transfer or deposition in the preparation of new two-dimensional materials such as graphene and perovskite solar cells.
Misconception 1: All non-contact profilometers can measure transparent films. In fact, measuring the thickness of transparent films requires a specialized film analysis module, otherwise only opaque films or steps can be measured.
Misconception 2: The higher the vertical resolution, the better. The vertical resolution can reach 0.1nm or even lower, but the actual system repeatability accuracy is also affected by environmental vibration and temperature drift. When providing equipment, Nikon Technology emphasizes "effective resolution" rather than theoretical indicators.
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