Semiconductor Manufacturing The simplistic view of semiconductors manufacturing is a cycle of depositing material onto silicon, patterning (lithography) and, then etching. The deposition process uses some F-GHGs in order to maintain the cleanliness of the processing chamber as deposited material can contaminate the next wafer. The etch processes use a great deal of different F-GHGs to create the fine structures for circuitry. These F-GHGs can have high Global Warming Potentials (GWP) and long lifetimes in the atmosphere as seen in Table 1. An example is CF4, which has a 100 year GWP of 7,380 compared to 1 from CO2.
According to US Environmental Protection Agency's Facilities Level Information on Greenhouse gases Tool (FLIGHT) (4), the emission of the F-GHGs for a modern semiconductor fabrication plant can be in excess of 500,000 tons CO2e. However, the semiconductor industry has long recognised the potential impact of F-GHGs and has, over the last 25 years, strived to reduce the emissions of these gases. An example was The World Semiconductor Council, which agreed in 1999 to reduce emissions by 10% by 2010 (5). They have employed strategies such as optimization of processes, substitution of non- (or low-) GWP gases and particularly abatement, where the destruction of some of these gases can be particularly challenging. This means that emissions can be reduced by 90%. So, what does that mean for our environmental footprint of phones? The iPhone 14 Pro has a lifecycle carbon footprint of 63 kg CO2e of which 81% is from the production process (6). Increasing the memory from 128 GB to 512 GB increases the footprint to 84 kg CO2e; however, increasing to 1TB and it becomes 116 kg CO2e. Thus, the importance of reduction of F-GHGs in the semiconductor manufacturing process is paramount