Microchips. The importance of metal-free wafers
Microchips, also called integrated circuits, have become essential for the daily life of human beings in this technological age. We not only find them in electronic devices, such as mobile phones or tablets, but also in objects of our daily life, such as refrigerators or cars.
The manufacturing of the first microchip dates back to 1958. The engineer Jack St. Clair developed a small-sized structure made up of a semiconductor material capable of storing information, which was called “integrated circuit”. Microchips integrate all the elements of an electronic circuit in a small space, usually using a silicon wafer (mineral/semiconductor material) as support.
It is of vital importance that these wafers are perfectly clean, totally free of impurities (dust, particles, metallic traces, etc.), since otherwise they could cause defects and failures in the interconnections, causing the deterioration of the electronic device. For example, metallic traces of Iron (Fe), Chromium (Cr) or Zinc (Zn) on the surfaces of silicon wafers cause damage to the glass and cause microchips to malfunction. That is why one of the challenges that arises in the manufacture of these devices is to find the most effective cleaning method for the silicon wafers.
In recent years various cleaning methods have been proposed for the removal of metallic impurities, the use of sequestering agents being of particular relevance. As part of cleaning solutions, these compounds improve their stability and durability, while effectively removing any trace metal present. It has been proven that the best chelate for this process is 1,2-cyclohexanediaminetatraacetic acid, CDTA. Its high stability and the ability to remove large amounts of metals from contaminated wafers have made CDTA gain importance in recent years as an essential component of the cleaning process.
