K-Patents Oy - semiconductor

K-Patents Applications in Semiconductor Industry Semiconductor and Microelectronics Fabrication: Wet Chemical Processes The K-Patents Semicon Refractometer PR-23-MS measures real-time the liquid chemical concentrations through the whole semiconductor fabrication process, i.e. from chemical supplies down to fab in-line and tool in-situ chemical quality control. The concentration of dissolved solids is determined by making an optical measurement of the solution’s refractive index. The advantage of this principle is that the same instrument can be used to measure any chemical. The PR-23-MS provides a continuous 4-20 mA or digital measurement signal and immediate feedback to the control system, if the chemical is not within the specifications. The PR-23-MS is physically small and easy to install in the bulk chemicals dispense, and in point of use chemical blending, spiking and monitoring applications. Ref. Application Note 5.00.000 Bulk Chemical Supplies Fabs with many products typically use a high number of different bulk chemicals. And since the predominant delivery method of chemicals in Fabs is by drum, every time a person handles a new drum there is a potential for human error. Occasionally, wafer defects occur due to wrong drum of chemical being dispensed onto the wafers. Therefore, the type of chemical should always be monitored and validated before it enters the process. For instance, lithography is a fabrication process, where all photoresists should be physically measured and checked for consistency. If a wrong photoresist is used this may lead to a very costly production problems and wafer damage. Resolving wafer defects often requires purging the wrong photoresist to drain and cleaning the tool, before more wafers can be processed. With K-Patents technology, low and high concentration alarms can be configured to eliminate these defects caused by human errors in container handling or equipment failure at the distribution point. Typical wet process chemicals that can be monitored with the same K-Patents refractometer are: Sulphuric acid Isopropyl alcohol: IPA Hydrochloric acid: HCl Hydrogen peroxide: H₂O2 Hydrofluoric acid: HF Phosphoric acid: H₃PO₄ Ammonium hydroxide: NH₄OH N-Methylpyrrolidone: NMP Propylene glycol monomethyl ether acetate: PGMEA EKC-265 Nitric acid: HNO₃ etc. Ref. Paper: In-Situ Chemical Monitoring in Semiconductor Fabrication Chemical Supplies To top of the page Wet Etch Wet etch is used to chemically remove layers (metal, silicon, photoresist) from the surface of a wafer. For instance, potassium hydroxide (KOH) is commonly used for this purpose. The etch rate of silicon in a KOH bath depends on the bath temperature and the KOH concentration. K-Patents Semicon Refractometer PR-23-MS provides a real-time indication of the KOH concentration. As several wafers are etched in the same bath, dissolved silicate is released into the solution and it becomes a tertiary (three component) solution. K-Patents provides a method (patent pending) for compensating the influence of the dissolved silicate in the refractometer output reading. To top of the page
Post-Etch Wafer Cleaning: Indication of Bath Life K-Patents Semicon Refractometer PR-23-MS (or Stainless steel version PR-23-AC) is used for concentration measurement of aqueous mixtures, such as EKC-265. EKC-265 is formulated to remove etching residues namely the remaining polymer material after the etching and the ashing operation (where the photoresist layer is removed). The purpose of the real-time in situ measurement is to determine the bath life. The water content of the rinsing bath starts from 18% and goes down to 13% where it stabilizes. The more water, the more aggressive the solution is. The refractometer provides a reliable indication of the bath life, so that the bath lifetime can be extended, the wafer throughput can be increased and the overall chemical consumption can be reduced. To top of the page Chemical Production: Wet Process Chemicals Photoresist Production: Recirculation Line of Chemical Formulator Tank K-Patents Semicon Refractometer PR-23-MS is used for monitoring the total solids concentration (TSC) of photoresist chemicals (PAC/PAG, resin, additives) and solvent in the recirculation line of the photoresist formulator tank. The photoresist solution is recirculated until it is ready and within the specifications. Some of the solvent may evaporate during the recirculation and therefore needs to be continuously monitored and replaced. K-Patents real-time measurement provides fast and reliable indication as to changes in the photoresist solution and to precise dosing and mixing of solvent in the formulation process and before filling. K-Patents measurement signal is not influenced by the entrapped air. To top of the page
To find out how You can benefit from using a K-Patents Process Refractometer, please contact us or send us an Information request.