Why Foundry Utilization Should Be Analyzed by Process Node
For foundry utilization, available capacity by process node and fab matters more than the companywide average. Learn to distinguish changes in the capacity denominator from fixed-cost effects when interpreting earnings.
Foundry utilization measures the share of production capacity actually used, but a companywide average alone cannot easily explain profitability. Leading-edge lines may be busy while other lines sit idle, and new fabs can expand the denominator so that output rises even as utilization falls.
First, Check How Capacity Is Defined
To calculate utilization, the numerator and denominator must refer to the same process, period, and unit. Dividing quarterly shipments directly by monthly wafer processing capacity already creates a period mismatch. Also check whether capacity means practical capacity after scheduled maintenance and process transitions or the theoretical design maximum. TSMC's annual report provides capacity and process portfolio information, but an outside analyst cannot use it to reconstruct exact utilization for every line. Explicitly distinguishing disclosed figures from estimates is essential for comparison.
Identify Where Fixed Costs Remain
Depreciation and the cost of maintaining personnel do not immediately disappear when a foundry reduces operations. Lower output can increase the cost burden per saleable unit. Conversely, increasing volume through greater use of existing facilities spreads fixed costs over more units. However, selling prices, initial yields, electricity costs, and materials costs vary by process, so utilization alone cannot determine margins. Separating better use of existing fabs from the initial costs of starting new fabs makes the drivers of earnings easier to explain.
Idle Equipment Does Not Always Mean Capacity to Accept Orders
Semiconductor capacity is not a shared pool that can be freely reassigned to any product. Customer designs are tailored to specific processes and qualification requirements, so an idle line cannot immediately substitute for another. When evaluating order growth, check available capacity for the relevant process and the associated packaging capacity. Do not conclude that low overall utilization necessarily leaves ample room for revenue growth, or that high utilization immediately requires expansion. The durability of customer orders and the feasibility of process transitions are separate decision variables. If a profit forecast assumes higher utilization, also specify whether the extra volume was secured through price cuts. Higher output may reduce the fixed-cost burden, but large price concessions can prevent the expected profit improvement.
Worked example
Hypothetical example: Quarterly capacity of 100,000 wafers and throughput of 80,000 wafers imply 80% utilization. If capacity rises to 120,000 wafers and throughput to 90,000 wafers the following quarter, throughput increases 12.5% but utilization falls to 75%. Holding fixed manufacturing costs at KRW 12 billion, the cost burden per wafer falls from KRW 150,000 to approximately KRW 133,000. In an actual situation where new facilities also increase fixed costs, that increase must be incorporated separately.
What to check
- Distinguish capacity by process node from the companywide average
- Check whether the numerator measures wafer starts, processing, or shipments
- Identify capacity expansion that increases the denominator
- Separate new-fab costs from efficiency at existing fabs
Sources and primary materials
This is educational material about research methods. For an actual company decision, verify the filings and primary sources for the relevant period.