Gas-phase processes, such as chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD), atomic layer deposition (ALD), atomic layer etch (ALE), and the like are often used to deposit materials onto a surface of a substrate, etch materials from a surface of a substrate, and/or clean or treat a surface of a substrate. For example, gas-phase processes can be used to deposit or etch layers on a substrate to form semiconductor devices, flat panel display devices, photovoltaic devices, microelectromechanical systems (MEMS), and the like.
Typically, multiple gas-phase processes are used to form such devices. Often, each process is carried out in its own reaction chamber, which may be a stand-alone chamber, or the chamber may be part of a cluster tool. Dedicating a reaction chamber to each process is desirable to prevent or mitigate cross contamination of reactants used or products formed within the reaction chamber. However, using dedicated reaction chambers requires significant capital costs and increases operating costs associated with making the devices. In addition, processing substrates in different reaction chambers often requires a vacuum and/or air break to remove a substrate from one reaction chamber and place the substrate in another reaction chamber.
In the case of ALD and ALE processes, multiple precursors are generally individually and sequentially introduced into a reaction chamber. Purge and/or exhaust steps are typically used to purge one precursor prior to introduction of another precursor. In other words, the precursors are introduced at different times to a reaction chamber to prevent unwanted mixing of the precursors. This is known as temporal processing. Although the introduction of different precursors is separated by time in such processes, the precursors can still undesirably mix and/or react, resulting in unwanted deposition within the reaction chamber and/or undesired particle formation.
To address these issues, spatial gas-phase reactors have been developed. Typical spatial gas-phase reactors include two or more processing regions coupled together along a horizontal direction, such that substrates can move from one processing region to another along a horizontal plane—e.g., along a conveyor or a turntable. Although these systems solve some problems associated with processing substrates in multiple reaction chambers and/or using multiple precursors within one reaction chamber, the systems still suffer drawbacks.
Horizontal transport systems require a significant amount of space, particularly floor space, for each processing region. In addition, the total process volume of such a system is relatively large, resulting in large purge gas requirements, long purge times, and slow substrate movement to maintain desired gas separation. Additionally, the relatively large processing region volumes can result in unwanted mixing of precursor gases.
In addition, precursor or reactant delivery schemes for horizontal transport systems are relatively complex. Further, the configuration of these systems is relatively inflexible, due at least in part to the timing requirements for the precursor or purge gas for each processing region relative to the speed at which the substrate moves. In addition, the mechanics of these systems can be relatively complicated and therefore such systems can be relatively unreliable and expensive to maintain.
Accordingly, improved gas-phase reactors, systems, and methods for carrying out multiple gas-phase processes are desired.