1：Experimental Design and Method Selection:

The study uses a hot-wire catalytic method to produce hydrogen radicals, with oxygen addition to generate oxidizing radicals. The experimental setup involves a vacuum chamber with gas flow controllers, a tungsten hot-wire catalyst, and optical interferometry for real-time film thickness measurement.

2：Sample Selection and Data Sources:

Samples include a positive-tone novolac photoresist (OFPR-800), poly(vinyl phenol) (PVP), and poly(methyl methacrylate) (PMMA) as base polymers. These are spin-coated onto Si wafers and pre-baked.

3：List of Experimental Equipment and Materials:

Equipment includes mass flow controllers (SEC-400MK2, SEC-400MK3), vacuum gauge (Baratron 622A12TAE), tungsten wire catalyst, DC power supply (EX-750L2), infrared thermometer (ISR12-L0), spin coater (Spinner-1H-III), oven (CLO-2AH), surface-texture measuring instrument (Surfcom 480A), green laser light source (520 nm), Si photodiode (S1787-04), and substrate stage heater. Materials include hydrogen gas (≥99.99%), oxygen gas (≥99.5%), ethyl lactate, and the photoresist polymers.

4：99%), oxygen gas (≥5%), ethyl lactate, and the photoresist polymers. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Hydrogen and oxygen gases are introduced at controlled flow rates (H2 fixed at 100 sccm, O2 varied from 0 to 2.0 sccm) into a vacuum chamber at 20 Pa. The tungsten catalyst is heated to 1.6×10^3 °C to produce radicals. Substrates with polymer films are placed 20 mm from the catalyst, and film thickness is measured in real-time using optical interferometry with a green laser. The substrate temperature is controlled and measured, and removal rates are calculated from thickness changes over time.

5：0 sccm) into a vacuum chamber at 20 Pa. The tungsten catalyst is heated to 6×10^3 °C to produce radicals. Substrates with polymer films are placed 20 mm from the catalyst, and film thickness is measured in real-time using optical interferometry with a green laser. The substrate temperature is controlled and measured, and removal rates are calculated from thickness changes over time. Data Analysis Methods:

5. Data Analysis Methods: Removal rates are calculated from the decrease in film thickness with respect to time, using time-averaged values. Data is plotted against substrate temperature to analyze the effects of oxygen addition.