Direct write electron‐beam lithography is the most flexible technique for sub‐0.25 μm imaging in an advanced development environment. The resolution and custom exposure capabilities of electron‐beam lithography, as well as the rapid turnaround for new device designs, provide early device/technology feasibility demonstration, learning, and proof‐of‐concept not easily obtainable with other lithographies. We have used a 50 kV shaped‐beam system for advanced complementary metal–oxide–semiconductor (CMOS), bipolar, BiCMOS, and DRAM device prototyping as well as for front‐end and back‐end process development, metrology standard fabrication, exploratory device fabrication, and x‐ray mask fabrication. The high throughput, as compared to vector scan systems, of shaped‐beam electron‐beam lithography was found to be essential in satisfying the requirements of advanced development programs. The key to success has been a complete understanding and integration of the interaction of the resist process, tool, proximity c...