ETCHING || MODULE 4 || EC 465 || KTU MEMS || LECTURE 35

Hi all, today we are going to discuss about etching So what is etching? Etching is the process of removal of materials in desired areas by physical or chemical means Etching is the process of removing materials in desired areas by physical or chemical means Etching is used to shape the geometry of micro components in MEMS and Microsystems Of the two common types of etching mentioned above 1. Physical Etching 2. Chemical Etching Physical etching is usually referred to as dry etching or plasma etching Chemical etching is referred to as wet etching Basically we use two types of etching 1. Physical Etching 2. Chemical Etching Physical Etching is another name for dry etching or plasma etching Chemical Etching is another name for wet etching Let us see what is chemical etching Chemical etching involves using solutions with diluted chemicals to dissolve substrates. For instance, diluted hydrofluoride solution is used to dissolve silicon dioxide, silicon nitrate and polycrystalline silicon, whereas potassium hydroxide is used to etch silicon substrate. Also, etching rate vary depending upon the substrate material to be etched and the concentration of chemical reactants in the solution as well as the temperature of the solution. the solution as well as the temperature of the solution as well as the temperature of the solution as well as the temperature of the solution as well as the temperature of the I am using potassium tetrazolide as etchant This is the diagram Wet etching is a faster etching process compared to dry etching The etching rate in wet etching is several tens of micrometer per minute There are some disadvantages to wet etching It often results in poor quality of etched surface due to bubbles and flow patterns of the solution Due to the bubbles and flow patterns of the solution, the quality of the solution will be poor No effective wet etching is available for some substrate such as silicon nitride If the substrate is like silicon nitride, there is no effective wet etching method This is wet etching The next etching is plasma etching The plasma etching is used for etching is a stream of positive charge-carrying ions of substrate with a large number of electrons diluted in an inert carrier such as argon The plasma etching is used for etching is a stream of positive charge-carrying ions of substrate with a large number of electrons diluted in an inert carrier such as argon and it can be generated continuous application of high voltage electric charge or by radio frequency sources As we said in CVD process, we use radio frequency sources in plasma etching This process is carried out in a low-pressure environment or vacuum The high-energy plasma-containing gas molecules, free electrons, and gas ions bombard the surface of the target substrate and knock the substrate material from its surface This process, in a way, is like a reverse-dispersion process at low temperature in the range of 50 to 100 degrees Celsius It takes place in high vacuum The high-energy plasma-containing gas molecules, free electrons, and gas ions bombard the surface of the target substrate and knock the substrate material from its surface This process, in a way, is like a reverse-dispersion process at low temperature in the range of 50 to 100 degrees Celsius As we said earlier, this is a plasma etching process The process is carried out in vacuum So, this is etching What is etching? Etching is the removal of material in desired area by physical or chemical means Etching is used to shape the geometry of micro-components Etching is used in MEMS and Microsystems There are two types of etching Physical etching and chemical etching Physical etching is usually referred to as dry etching or plasma etching Chemical etching is referred to as wet etching Chemical etching involves the removal of a part of a chemical There are two types of chemical etching Isotropic etching and anisotropic etching Next is physical etching Physical etching is referred to as plasma etching We know what is happening inside this High energy plasma There are gas molecules, free electrons and gas ions They hit or knock on the surface of the target substrate This is how it is removed from there This is carried out in low temperature Temperature is around 50 to 100 degree Celsius This process is carried out in high vacuum This is all about etching I hope everyone understood this small topic See you in the next video See you