What are 2D materials?

2D materials are layered materials composed of single or multiple atomic layers in terms of thickness and stacked between van der Waals forces. Initially, 2D semiconducting materials mainly focused on carbon-based materials, such as carbon nanotubes and graphene. According to a study by IBM, graphene chips have shown greater performance and improvement in power consumption compared to silicon-based chips. For instance, the chip speed of the 7 nm silicon-based chip will only be enhanced by 20% when it is narrowed down to 5 nm, whereas the 7 nm graphene chip demonstrated 300X greater speed than the 7 nm silicon-based chip.

Research data have proven that carbon-based 2D materials can better extend Moore's Law. 2D materials can be structured into several or even single atomic layers, potentially providing extremely thin channel regions without confronting the short-channel effects.

2D materials have gained attention due to their excellent electrical, thermal, and mechanical properties. After the discovery of graphene, two-dimensional transition metal dichalcogenides (TMDCs), another kind of 2D material with similar structures, became 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 2D materials. Among them, the most widely studied is MoS2 (molybdenum disulfide). In theory, electrons should move through tungsten disulfide (another 2D material) faster than MoS2. However, Intel's experiment showed that the MoS2-based device had superior performance.

Experiments report that the highest mobility value for MoS2-based devices is close to the theoretical value, 200 cm2/Vs. Due to its high mobility and extremely thin thickness, researchers at Stanford University believe that TMDs such as MoS2 is the ideal choice for transistor materials in processes below 10 nm.

Currently, there is an urgent need to address the challenges of 2D material industrialization.

The semiconductor industry, striving to maintain the growth of the $600 billion market and extend Moore's Law, is facing a disruptive process in industrial production as it attempts to adopt new materials. With no new technology that guarantees the continuation of Moore's Law, 2D materials have become the focus of the industry.

However, the current situation of 2D materials is that they can only be produced in small batches in the laboratory that support academic research. The transition process for industrialization confronts various challenges, including changes in design tools, material growth, material transfer, and integration of production lines.

The industrialization of 2D materials presents challenges in terms of design tools and processes. For instance, producing 8-inch or 12-inch wafers according to the current industry yield standards is difficult and requires specially designed and customized professional production tools in order to achieve the desired results.

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

Meanwhile, producing graphene involves exposing a heated substrate to a carbon-containing gas in a vacuum. The gas is then deposited on the hot substrate surface, forming the unique graphene honeycomb pattern. To ensure high-quality material and the desired wafer size, tight control of temperature and other parameters is necessary.

The growth process is followed by a dry transfer process that separates materials from the growth substrate and moves them onto the wafer. Hence, automating these processes is the key to ensuring that 2D materials can be produced industrially.

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