Mikrostruktury i mikrosystemy - nowoczesne metody wytwarzania

W artykule przedstawiono podstawowe informacje o dotychczas stosowanych różnych metodach wytwarzania mikro- i nanostruktur. Scharakteryzowano procesy fotolitografii LIGA oraz metody wytwarzania nanorurek i kropek kwantowych. Porównano właściwości przedstawionych metod.

Miniaturisation of electronic devices: sensors, actuators etc occurs usually by using a suitable technology e.g.: photolithography, LIGA, chemical and plasma treatment of semiconductors. Photolithography is a specific variant of photography. This process consists of two stages: performing a mask and using the mask to produce duplicates. The mask is made of metal (chrome) spread on a glass or quartz wafer. In the next stage the mask is irradiated by ultraviolet rays (X-rays or an electron beam). The places when rays fall are selectively removed from the wafer by dry or wet etching. The other method is the soft photolithography which uses the soft polymer PDMS to carry out "stamping", this matrix can be them used for various purposes among others for: microcontact printing and capillary forming. The next stage is lithography with wet blade. It is a method using the microscope of atom forces. On this blade (it is to area of gold and make a self - assembled monolayer. Using the microscope of atom force it is possible to draw a very thin line which can be some atoms thick. The next method LIGA uses the synchrotron (circular accelerator of charged particles). The X-rays from a synchrotron source fall through a special mask onto a thick photoresist layer which covers a conductive substrate. The pattern formed is then electroplated with metal. The metal structures produced can be the final product, however it is common to produce a metal mould. This mould can then be filled with a suitable material, such as plastic, to produce the finished product made of that material. This is a high precision method but it is very expensive. The next group of technology are methods which produce nanotubes and quantum dots. Quantum dots are crystals made of several hundred atoms. One of the methods which produces these structures is the chemical reaction between metallic ions (cadmium) and selenium ions, which gives cadmium selenide as a result. Nanotubes are structures made of carbon atoms and can be produced in three stage: - the electric arc method - uses graphite electrodes and electric arc phenomena, - the CVD method - uses chemical reaction, - the laser method uses laser rays.