Batch Processes

Batch Processes

Batch processes involve simultaneously processing multiple products, and in the context of IC (Integrated Circuit) manufacturing, these products are semiconductor wafers. These batches are commonly referred to as “lots.” Modern semiconductor manufacturing facilities employ various batch fabrication equipment, like furnaces designed for high-volume wafer processing. This approach enables these factories to achieve substantial throughputs, often processing tens of thousands of wafers each month.

One example of a batch process in semiconductor manufacturing is chemical vapor deposition (CVD). In this type of hot-wall, reduced-pressure reactor, a quartz furnace tube is heated in three separate zones, with reactive gas introduced at one end and pumped out at the opposite end. The wafers are positioned vertically side by side in a container referred to as a “boat.” The deposition of desired thin films occurs as a result of gases reacting on the surface of the wafers.

However, it’s essential to note that the high manufacturing throughput characteristic of batch processing can sometimes come at the cost of uniformity and precise process control. In the case of CVD, for instance, wafers situated farthest from the gas inlet may experience lower deposition rates due to reduced access to reactant gases. These gases tend to get consumed by reactions occurring closer to the inlet. To mitigate this issue, one approach is to increase the deposition temperature in each successive reaction zone starting from the inlet, which can help compensate for the variations in deposition rates across the wafers.