What is 2D material?

A 2D material is a layered material that only has a single or multiple atomic layers in therms of thickness and is stacked by van der Waals forces between layers. In the beginning, 2D semiconductor materials mainly revolved around carbon-based materials such as carbon nanotubes and graphene. A study by IBM shows that compared with silicon-based chips, graphene chips will have a greater improvement in performance and power consumption. For example, if the silicon-based chip manufacturing process is advanced from 7nm to 5nm, the chip speed will increase by 20%; and the graphene chip with the 7nm process will increase the speed by up to 300% compared with the silicon-based chip with the 7nm process.

The data of many laboratories can prove that carbon-based 2D materials can better continue Moore's law of electrons. 2D materials, on the other hand, can be structured into several or even single atomic layers, thus offering the possibility to provide very thin channel regions without worrying about short-channel effects.

After the discovery of graphene, two-dimensional transition metal dichalcogenides (TMDCs) have a similar structure and become a new type of graphene-like material. Therefore, in addition to graphene, materials such as MoS₂, WS₂, WSe₂ and black phosphorus represented by transition metal chalcogenides are also considered as 2D materials. Among them, the most widely studied is molybdenum disulfide (MoS₂). In theory, electrons should move through tungsten disulfide (another 2D material) faster than molybdenum disulfide. But in Intel's experiment, the molybdenum disulfide device was superior.

Experiments report that the highest mobility value for MoS₂-based devices is close to the theoretical value of 200 cm2/Vs. Due to their high mobility at extremely thin thicknesses, researchers at Stanford University also believe that transition metal dichalcogenides (TMDs) such as MoS₂ are the first choice for transistor materials in processes below 10nm.

At present, how to industrialize 2D materials is a problem that needs to be tackled. 

In industrial production, it is undoubtedly a very disruptive process for the entire semiconductor industry to adopt new materials. The current semiconductor industry wants to continue to ensure the continued growth of the $600 billion semiconductor market, and is struggling to expand Moore's Law, but there is still no new technology that can guarantee the continuation of Moore's Law. This is why 2D materials have begun to become the focus of the industry.

But the current situation of 2D materials is that they can only be produced in small batches in the laboratory to support academic research. There are many problems in the process of inheriting from 2D materials to expanding industrialization, including changes in design tools, material growth, material transfer and integration of production lines.

The first problem in industrializing 2D materials is addressing design tools and processes. It is not easy to produce 8-inch or 12-inch wafers according to the current industry yield standards. Each of these steps requires specially designed and customized professional production tools.

Starting with material production, chemical vapor deposition (CVD) is the most widely used process for producing graphene and other 2D materials such as hexagonal boron nitride.

Producing graphene involves exposing a heated substrate to a carbon-containing gas in a vacuum. As the gas is deposited on the hot substrate surface, the carbon grows into graphene's unique honeycomb pattern. This process requires tight control of temperature and other parameters to ensure that high-quality material can be grown to the desired wafer size.

The growth process is followed by a dry transfer process that separates the material from the growth substrate and moves it onto the production wafer. The automation of these processes is key to ensuring that 2D materials can be produced industrially.