In-line sputter deposition system

Details In-line sputter deposition system In-line sputter deposition system

1999-09-23

2001-04-17

Bratlie, Steven A. (Department: 3652)

Material or article handling

Apparatus for moving material between zones having different...

C414S935000, C414S939000, C414S941000

Reexamination Certificate

active

06217272

ABSTRACT:

FIELD OF THE INVENTION
The invention relates generally to apparatus and methods for processing substrates and more particularly to apparatus and methods for simultaneously processing multiple batches of substrates.
BACKGROUND INFORMATION
Microelectronic and electrooptic devices are fabricated by numerous sequential processing steps which include at least one step of depositing a thin metal or dielectric films onto substrates such as silicon, gallium arsenide, and glass. Thin metals and dielectrics are deposited in a vacuum chamber by numerous techniques known in the art, such as sputtering, evaporation, and Chemical Vapor Deposition (CVD). Sputtering is a versatile deposition technique because it can be used to deposit a wide variety of materials at relatively high deposition rates. Sputtering is particularly useful for depositing multiple layers of materials or materials with complex stochiometries.
Sputtering systems typically bias a target comprising the material to be sputtered at a relatively high voltage, typically about −500 volts, in a vacuum chamber filled with an inert gas such as argon, at pressures ranging from 0.1 mtorr to 100 mtorr. The bias potential induces a breakdown of the gas and the formation of a plasma glow discharge. The ions in the plasma are accelerated by the negative potential into the target thereby producing secondary atomic emission which deposits sputtered material on a substrate placed in the path of the sputtered ions. Magnetic fields are typically used to confine the plasma in order to increase the sputtering rate.
It is sometimes desirable to deposit multiple layers of different material on substrates without removing the substrates from the process chamber. However, most prior art sputtering systems are designed to depositing one material, which may be a single metal or dielectric or a combination of several metals or dielectrics. Thus, if multiple layers of different materials have to be deposited on substrates, the sputtering systems usually need to be reconfigured.
It is desirable to process multiple substrates simultaneously in order to increase process throughput and thus reduce the manufacturing costs of the end product. Modern deposition tools used in the microelectronics industry include multiple chambers and complex mechanical devices that transport the substrates between the chambers of the tools. Modern processing tools typically have numerous sections including at least one substrate storage area, a substrate preparation or cleaning area and a deposition chamber. There are three general design approaches to making high-throughput deposition tools.
Batch processing systems process an entire batch of substrate simultaneously. Substrates are either loaded in the process chamber one-by-one or they are loaded onto a pallet, which is then loaded into the process chamber. These tools can have a very high throughput, but they are difficult to automate. The throughput is typically limited by the substrate handling mechanisms. Batch systems have become less popular because they are difficult to scale to large wafer sizes.
Cluster tools include a plurality of process chambers that are clustered around a central platform. A transport mechanism or robot moves the substrates between the various process chambers. Typically, each process chamber attached to the cluster tool performs a single task and can be operated independent of the other process chambers. For example, the individual process chambers may clean substrates before processing, etch substrates or a film deposited on substrates, or deposit metal or dielectric films on substrates. The throughput of cluster tools can be very high because multiple chambers can process substrates simultaneously.
Typically, the deposition chambers within cluster tools are configured to deposit only one metal or dielectric film. Consequently, if the process requires multiple layers of metals or dielectric films, the multiple layers are sequentially deposited in different process chambers. State-of-the-art cluster tools typically have between about four and eight process chambers. Therefore, cluster tools have a limited capability to deposit multi-layer film coatings.
In-line processing tools process substrates one-by-one, through a series of process steps. In-line processing tools are versatile tools that have relatively high throughput. One disadvantage of in-line processing tools is that the throughput of these tools is limited by the process time of the longest process step. Another disadvantage of in-line tools is that they are physically very long in length compared to other processing tools because of their linear design and because separate stations are required for loading and unloading the substrates. In order to dimension these tools to fit into modern semiconductor processing facilities, where floor space is very costly, complex mechanical designs are often used.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an in-line processing system that simultaneously transports substrates into or out of a load lock while processing substrates in at least one of a first process chamber and a second process chamber. A principle discovery of the present invention is that an in-line processing system can be constructed where a load lock, a sputter cleaning chamber, and a sputter deposition chamber can be operated simultaneously.
Accordingly, the present invention features an apparatus for simultaneously transporting and processing substrates. The substrates may be semiconductor wafers. The substrates may be positioned on a pallet or free standing. The apparatus includes a load lock that stores at least one substrate prior to processing and that stores at least one substrate after processing. The load lock may be a vacuum load lock. The load lock may include a first valve that defines a first end of the load lock for loading and unloading substrates and a second valve that defines a second end of the load lock. A robot arm positioned in an atmospheric pressure environment may be used to load at least one substrate into and out of the first end of the load lock.
A first transport mechanism transports at least one substrate into and out of the load lock. In one embodiment, the first transport mechanism comprises a plurality of tubes or solid members. A multi-stage elevator is adapted to receive the first transport mechanism. A first process chamber is vertically disposed from the multi-stage elevator. The multi-stage elevator vertically transports at least one substrate into and out of the first process chamber. In one embodiment, the multi-stage elevator includes a first and a second elevator stage, where the second stage is vertically aligned and separated from the first stage. Each of the first and the second elevator stage are adapted to support at least one substrate and to accept the first transport mechanism.
A second process chamber may be coupled to the multi-stage elevator. A second transport mechanism transports at least one substrate between the multi-stage elevator and the second process chamber. In one embodiment, the second transport mechanism comprises a plurality of tubes or solid members. The first process chamber may be a sputter cleaning chamber.
In one embodiment, the second process chamber is a multi-layer sputter deposition chamber that includes a plurality of magnetrons mounted on a rotatable member. The rotatable member may define an aperture that is substantially at atmospheric pressure. A predetermined one of the plurality of magnetron is positionable proximate to a substrate in the second process chamber. A transport mechanism transports the substrate proximate to the predetermined one of the plurality of magnetron in a first and a second direction. The second direction may be substantially opposite to the first direction.
The present invention also features a method of simultaneously transporting a batch of substrates in an apparatus while processing a batch of substrates in at least one process chamber of the apparatus. A first batch of substrates

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