Communications: electrical – Continuously variable indicating – Condition responsive
Reexamination Certificate
2002-02-27
2003-11-04
Noland, Thomas P. (Department: 2856)
Communications: electrical
Continuously variable indicating
Condition responsive
C073S865900, C340S870070
Reexamination Certificate
active
06642853
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to methods and apparatuses for testing or aligning the various parts of a processing system. Specifically, the present invention relates to methods and apparatuses for leveling and aligning the processing system and the various structures within the processing system that support and/or transfer processing objects, such as substrates, through the processing system so that the processing system and each structure is substantially level and so that each structure receives, supports and/or transfers the substrates in substantially the same inclination and without slippage of or damage to the substrates.
2. Background of the Related Art
Processing systems for processing 100 mm, 200 mm, 300 mm or other diameter substrates are generally known. Typically, such processing systems have a centralized transfer chamber mounted on a monolith platform. The transfer chamber is the center of activity for the movement of substrates being processed in the system. One or more process chambers mount on the transfer chamber at slit valves through which substrates are passed by a substrate handler, or robot. Access to the transfer chamber from the clean ambient environment is typically through one or more load lock chambers attached at other slit valves. The load lock chambers may open to a very clean room, referred to as the white area, or to an optional substrate handling chamber, typically referred to as a mini-environment.
In addition to the substrate handler disposed within the transfer chamber, a processing system may have several other structures, including, but not limited to, indexers in the load lock chambers, lift pins in the process chambers, and substrate chucks in the process chambers, which will support or handle the substrates in one manner or another. The lift and support structures within the processing system may exchange substrates more rapidly, without slippage or backside contamination of the substrates, if the lift and support structures are level. Additionally, the extremely fine and delicate nature of the circuits and other structures being constructed on the substrates may require that the processing system as a whole, and particularly each substrate support structure, be set as near to level as possible. Typically, assemblers or operators of the processing systems may try to ensure that, at a minimum, the various substrate support structures are in alignment relative to each other, so that even if each support structure is not perfectly level, at least they are all at the same inclination. Additionally, the assemblers or operators will attempt to ensure that the substrate support structures, which move the substrates laterally, accelerate and decelerate at suitable rates and without discontinuous, or jerking, motion, so that the substrates do not slip on the support structure. Failure to ensure that the processing system and/or each of the substrate support structures is properly level and/or aligned and is operating smoothly may cause damage to or improper processing of the substrates and can reduce the throughput of the processing system since substrate exchanges may not be performed at maximum speed.
Relative alignment of the substrate support structures is typically more important than absolute leveling of the entire processing system since substrate exchange handling can result in significant slippage due to improper alignment. When the substrate support structures, within a processing system, are improperly aligned, however, the support structures do not hold the substrates at about the same inclination, or tilt. Thus, when one support structure transfers a substrate to another support structure, such as when the lift pins remove a substrate from a blade of the transfer chamber substrate handler or place a substrate onto the substrate chuck in a process chamber, one point of the substrate will always touch the receiving support structure before other points do. If substantial motion occurs prior to the remaining points making contact, then the substrate can slip. In this manner, potentially contaminating particles may be scraped from the contacting points of the substrate causing backside contamination of the substrate. These particles may eventually work their way around to the top of the substrate and be deposited on the processed surface of the substrate, thereby contaminating the micro circuits or other structures constructed thereon. Additionally, when the substrate does not touch a receiving support structure with all points in very close alignment, then the substrate may be shifted from its proper, or expected, position, so that the substrate is off-center. An off-center substrate may undergo uneven or otherwise improper processing or may come in contact with surfaces or objects within the processing system that will contaminate the substrate, create potentially contaminating airborne particles or even break the substrate. Thus, exchanges of the substrate between lifting or supporting structures within the processing system requires a coplanar interface. If the exchange is not coplanar, then the substrate will have the propensity to slip, resulting in misalignment and backside contamination of the substrate.
When a processing system as a whole is improperly leveled, the system chambers, such as the transfer chamber, are inclined at an angle and can cause problems with the handling and processing of substrates and can exacerbate the problems with substrate support structures that are further inclined relative to the processing system. Since the substrate support structures are mounted to the processing system, if the processing system is inclined and the support structures are level relative to the processing system, then the support structures will also be inclined, though the support structures may, nevertheless, be aligned with each other. When the processing system is inclined, but the support structures are aligned, then the processing system may still operate properly, but possibly at a lower than optimum speed. Additionally, performance of certain functions that are sensitive to gravity may be affected by the inclination of the system. When a transfer chamber substrate handler, for example, accelerates a substrate in a manner that may be appropriate for a level system, the substrate may, nevertheless, slide off-center due to the inclination, thereby exposing the substrate to potential damage from particles that may be generated by the slide or to potential collision with a surface or object in the processing system that requires a relatively close centering tolerance of the substrate for clearance.
The substrate support structures typically may be leveled independently within the processing system. Thus, after the transfer chamber and the processing chambers are leveled as a whole, the transfer chamber substrate handler or the process chamber lift pins or chuck may be additionally leveled independently. It is even possible for a substrate handler to be fairly level while the transfer chamber is significantly inclined, or vice versa. In such manner, the substrate handler may be aligned with an opening through which it passes substrates to and from a process chamber on one side of the transfer chamber, yet be out of alignment with an opening for a process chamber on the opposite side of the transfer chamber. Therefore, the transfer chamber substrate handler must be fairly closely aligned with the inclination of the transfer chamber to permit proper functioning of the entire system.
FIG. 1
a
shows a prior art method of determining the inclination of a transfer chamber substrate handler
10
. The transfer chamber
12
is shown with a lid
14
partially lifted to expose the interior of the chamber body
16
. The substrate handler
10
is mounted in about the center of the transfer chamber
12
and rotates about a center point. The substrate handler
10
extends a blade
18
to insert a substrate
20
through a slit valve opening
22
to access a process chamber (n
Applied Materials Inc.
Moser Patterson & Sheridan
Noland Thomas P.
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