Merits of Batch ALD

In this presentation, we provide an overview of the merits and applications of batch ALD in a vertical furnace. In addition, a number of common perceptions related to cycle time, films specs and batch processing in industry will be examined more closely.

Batch ALD offers a significant cost-per-wafer reduction compared to clustered single-wafer tools for a range of existing and emerging materials and applications. We present results on cycle time reduction to 20 s and below for ALD Al₂O₃ and TiN processes without significantly impacting uniformity, resistivity and step coverage. How purge and precursor flows influence the deposition process will be shown by combining experiment and simulation. The influence of deposition temperature and growth inhibition will be covered by presenting a thermal process for the deposition of AlN. A throughput of >50 wafers per hour was achieved for 10 nm films. For Si solar cells, the throughput and costs requirements are the most stringent. We will show that a platform of 4 reactors with automated handling for square solar wafers can reach 4800 wafers/hour (5 nm Al2O3) with remarkably low TMA consumption.

With the workhorse materials being TiN and Al₂O₃ and applications as diverse as metal gates in logic, trench capacitor electrodes, capacitor dielectrics, barrier layers and passivation films, batch ALD has firmly established itself at device manufacturers and foundry sites. Prospects for emerging markets such as MEMS, solar and LED will be discussed.