FLAT PANEL DISPLAY

Rhosonics helps the industry to use ultrasonic technology for in-line, real-time measurements, through which process optimization can be achieved, allowing a safer, more reliable, sustainable and cost-effective operation. This is how Rhosonics contributes to a smart and green world.

Rhosonics Analytical provides solutions for inline analysis in chemical blending. Serving virtually all electronics industries, inline analyzers are available for the following applications.

> related pages

lcd & tft productions

Rhosonics inline process analyzers are widely used in the production of LCD flat panel monitors. Within this industry, etchants (ITO-Etch), strippers, and developers (such as TMAH) are used. Measurement of photoresist is becoming increasingly important in this industry.

Rhosonics has developed a special instrument for the measurement of TMAH+PR (CCM B32). Strippers are used to exfoliate photoresist that is left in the photolithography process. Citric acid is often used as a substitute for acetic acid, which normally leaves a strong odor in the darkroom. Rhosonics is able to measure these kinds of liquids online. Detergents and surfactants can be measured easily.

Photolithography

In the flat panel display process concentration measurement is important to prevent issues in the cleaning or in the wet etching processes.

• Cleaning step
After the process step, the used materials should be cleaned with chemicals to prevent contamination in the next step. The goal of the cleaning step is to get rid of residues from previous steps that could affect the following steps’ performance. The cleaning chemicals should have the right concentrations to effectively clean the surface of the wafer. Otherwise, wafers may contain undesired organic/inorganic material. Wafers that have not been properly cleaned will not have the desired quality when the production line is completed. As a result, either the product will be counted as a defective product or sold as a lower-performance chip.

• Development step
The exposed wafers are developed in immersion baths or by spraying. The exposed area will be removed or remains depending on the resist type (negative or positive). This step is important to create a perfect resist pattern to control which part of the substrate will be etched. The positive resist or negative resist pattern should be the same as intended.

Otherwise, the wrong areas of the substrate will be removed in the next step which results in an ineffective product. Like every production step of the photolithography process, precision is key to achieving the desired results in the development stage. The concentration of the photoresist developer (e.g. TMAH) should stay within an optimum range to effectively remove the photoresist in the intended area.

For example, a typical TMAH solution should be kept in a concentration between 2.38%-2.62%. A real-time and accurate analyzer will help to keep the chemical properties under control and have an effective operation.

• Wet etching step
Wet etching (or isotropic etching) is a quick way to etch materials. In the wet etching process, different types of chemicals are used to create a pattern on the substrate of some material (usually silicon wafer). There is a trend for smaller and more compact chipsets, therefore the challenge of this process, step is to precisely create more complex patterns in the substrate using the right chemical concentrations.

product choice for this industry

chemical concentration
meter

Get in touch with Rhosonics for further information. If you want to learn more about our applications, then please also check our client cases and webinars.