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Plasma etching solutions for two-dimensional materials in integrated circuits

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22 Apr,2021

Plasma etching solutions for two-dimensional materials in integrated circuits:
In recent years, there are many two-dimensional materials similar to graphene that have been discovered and studied. Due to its ultra-high mobility, people have paid wide attention to them, such as molybdenum sulfide, black phosphorus, silicon, tungsten selenide and so on. The common characteristics of this kind of two-dimensional materials are:

CRF Plasma etching
① is a layered structure, all atoms are located in one or two planes. These materials can form two-dimensional electron-gas transport in the two-dimensional direction, which enables them to have very high mobility in the undoped state, and the threshold voltage is very small. The device does not need to use the reverse region to operate, and does not need to use deep Wells to limit leakage and migration. These advantages will save a lot of plasma doping process for chip processing and greatly save the cost. The difficulty, of course, is finding the right dielectric layer and metal electrode; Predictably, once such materials are used in chip manufacturing, how to improve the contact resistance becomes a whole new problem.
② At present, such materials are not widely available. This kind of two-dimensional material has high activity, rigidity and easy fracture. At the beginning of the study are dispersed by ultrasonic material plasma in benign solvent in the monolayer or multilayer structure, the method of material area is not too big, but with the in-depth study and industrial demand, this kind of material is expected to the growth of large area, only need to explore the substrate material and the growth conditions.
(3) Such materials often do not have band structure or very narrow band, which leads to their high activity, easy to capture or release charge. In industry this makes the process more difficult.
The thermal conductivity and hardness are also good, and often have the characteristics of the dominant direction of heat conduction and the dominant direction of electrical transmission is different.
⑤ in the direction of the vertical two-dimensional surface conductivity is very low, even insulation. The above characteristics of these materials are both high performance and low practicability characteristics, but there is no doubt that every shortcomings to overcome will make it a step forward in the use of the road, will also bring great commercial value.
The etching of these materials is generally difficult, because they are characterized by strong activity, small volume and extremely thin thickness of the target material. It is difficult to control the etching parameters when using strong chemical etching plasma etching. It's obviously not a good idea to use a high-energy plasma, because that would damage the film. At present, there is no mature etching technology to carry out patterning. According to the development of etching technology in recent years, the increasingly mature atomic layer etching or remote plasma etching technology is expected to solve the etching problem of this kind of material. Atomic layer etching has the characteristic of precise positioning etching quantity, and distal plasma etching is the representative of low damage etching technology. In principle, plasma etching of two-dimensional materials is expected to be solved by it, and of course, it is hoped that other new etching processes will emerge.
At present, the semiconductor device processing of these two-dimensional materials is mostly in the laboratory stage. The main method of film formation is to peel the lamellar structure from the bulk material. Most of these 2D materials are highly active and have the characteristics of instability when they meet water and air. With time in the air, the morphology of black phosphorus peel changes constantly, and its thickness also increases. It is formed by the interaction with water and oxygen in the air, and this material property will greatly affect the stability of the device. Large area processing difficulties and harsh stability conditions are two major problems in the industrialization of two-dimensional materials.
The above is the CRF plasma etching manufacturer of two-dimensional materials in the application of plasma etching solutions in integrated circuits.

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