Microwave enhanced atomic layer deposition (MW-ALD): Incorporating a microwave antenna into an ALD system and performing <i>in situ</i> direct microwave exposure during ALD

Self-limiting, purge-separated, cyclic reactions enable atomic layer deposition (ALD) to produce highly uniform and conformal films with precise thickness control. However, the typical relatively low deposition temperatures can lead to residual impurities, defects, and suboptimal material properties. To address this, we introduce microwave enhanced ALD (MW-ALD), an energy enhanced ALD technique in which in situ microwave exposure is included in each ALD cycle. The design of the microwave antenna and exposure system and integration into a commercial ALD chamber are first described. The benefits of MW-ALD are then demonstrated using Al2O3, a material that in bulk form is not expected to strongly interact with microwaves. Through ellipsometry and electrical measurements, we show that in situ MW irradiation annealing can reduce thickness, improve film properties such as refractive index, reduce high field current leakage, and improve breakdown strength. In all cases, MW-ALD produced a greater change in properties than was produced by an equivalent microwave exposure performed post deposition.