SEALING||MODULE 6 || EC 465 || KTU MEMS || LECTURE 44

Hi all, today we are going to discuss about the topic called Sealing. The most critical problem in microsystem packaging is the interfacing of key components. We all know that the biggest problem in microsystem packaging is the interfacing of key components. For example, the micro sensors or accelerometers we use now are all devices that come in direct contact with our measurement medium. Likewise, micro valves, micro channels, pumps are all used in micro fluidic systems. They come in contact with the working fluids. So, all these devices and systems required to the contacting fluids be hermetically sealed off from the package. Either for the purpose of protecting the delicate core components such as sensing elements, check valves or agitating beams, or for the proper functioning of the device. So, sealing is the same critical challenge to design engineers. That's why sealing is so important in the case of design engineers. This figure shows the sealing provided for the micro pressure sensor, micro valves, and micro pumps. We have already studied the structure of micro valves, pumps, and pressure sensors. Now, let's see where all the sealing is applied. The figure shows the sealing provided for the micro valves, pumps, and micro pumps. Surface micromachining is used to produce these micro shells. We have already studied bulk micromachining and surface micromachining. Surface micromachining is done through a process called surface micromachining. Surface micromachining is done by depositing a sacrificial layer over the die to be protected. What happens to the sacrificial layer? A gap is formed between the micro shell and the die. This gap is approximately 100 nanometers. This method is called sealing by micro shell. Micro shells are produced to protect the delicate sensing or actuating elements in micro devices. A surface micromachining technique is used to produce micro shells. The procedure involves depositing a sacrificial layer over the die to be protected. A shell material is then deposited over the sacrificial layer. An etching process then follows to remove the sacrificial layer. A gap is formed between the die and the micro shell. This gap is approximately 100 nanometers. This is sealing by micro shell. Next is reactive sealing technique. This technique involves chemical reactions. The encapsulant cover for the die is initially placed on the top of the die or constraint base with a small gap. After that, the unit is subjected to chemical reactions such as thermal oxidation process. Silicon dioxide is formed at the two ends of the die. A sealing process is carried out using silicon dioxide. This was about the sealing process. Hope everyone understood. See you in the next lecture.