Electricity: motive power systems – Positional servo systems – With particular motor control system responsive to the...
Reexamination Certificate
1999-06-03
2001-04-24
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Positional servo systems
With particular motor control system responsive to the...
C414S777000, C414S936000
Reexamination Certificate
active
06222339
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a system and method for controlling the attitude of a substrate. More specifically, the invention relates to a system and method for controlling the attitude of a disk-shaped substrate, such as a semiconductor wafer, an LCD glass wafer, a photo-magnetic disk, a compact disk and a minidisk.
2. Related Background Art
In a typical production process for a semiconductor equipment, there is widely adopted a substrate treatment system for sequentially transporting disk-shaped substrates (which will be hereinafter referred to as “wafers”), such as semiconductor wafers, which are to be treated, to a cleaning bath, in which a treatment solution, such as a chemical and a rinsing solution (a cleaning solution), is stored, and a drying section to clean and dry the substrates.
In order to efficiently clean a plurality of wafers, e.g., 50 wafers, using such a substrate treatment system, there is preferably adopted a method for transporting a plurality of wafers, e.g., 50 wafers, while causing the wafers to have the same attitude, i.e., while vertically arranging the wafers at regular intervals, by means of a wafer delivery unit, which is provided in a wafer delivery section provided between a wafer introducing/discharging section and a treatment section, and for carrying the wafers in and out of each of treatment units.
Therefore, there is known a conventional wafer attitude control system shown in FIG.
13
. This wafer attitude control system comprises: a driving shaft b, which extends in directions of arrangement of a plurality of wafers W and which has a diameter so as to be receivable in a notch (a positioning notch) a for contacting the lower portion of the outer peripheral portion of each of the plurality of wafers W due to the weight of the wafers W to rotate the wafers W; idle pulleys c, each of which is rotatably provided so as to correspond to each of the plurality of wafers W and each of which is associated with the driving shaft b for supporting the corresponding wafer W to rotate in accordance with the rotation of the corresponding wafer W; and stoppers d, each of which contacts the outer peripheral portion of each of the wafers W moved downward due to gravity when the position of the notch a corresponds to the position of the driving shaft b after each of the wafers W is rotated, and each of which is associated with the corresponding idle pulley c to support the corresponding wafer W so that the driving shaft b does not contact the inner surface of the notch a of the corresponding wafer W (see Japanese Patent Laid-Open No. 6-345208).
However, in such a conventional system, the wafers W are rotated by the driving shaft b for a predetermined period of time to allow the notches a to engage the driving shaft b to align the notches a. Therefore, even after the notch a of one of the wafers W is arranged at a predetermined position, when the notches a of other wafers W are not aligned with each other, the driving shaft b remains rotating with respect to the wafer W, the notch a of which has been arranged at the predetermined position, until the notches a of all of the wafers W are aligned with each other. Therefore, the driving shaft b contacts the outer peripheral portions or notches a of a number of wafers W until the notches a of all of the wafers Ware aligned with each other. Consequently, there is a problem in that dust is produced to be splashed to adhere to the wafers W. In addition, since the driving shaft b is thin, it is easily worn down, so that there is a problem that the wear of the driving shaft b does not only obstruct the rotation of the wafers W, but it also obstructs the attitude control of the wafers W.
Such problems are common to the positioning of disk-shaped substrates other than the wafers W, such as photo-magnetic disks or compact disks.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to eliminate the aforementioned problems and to provide a substrate-attitude control system and method which can prevent dust from being produced to reduce the wear of a driving part to enhance the reliability of the system.
In order to accomplish the aforementioned and other objects, according to the present invention, when the positioning notches of a plurality of substrates are aligned, it is detected that the positioning notch of a certain substrate is arranged at a predetermined position, so as to individually prevent the substrate, which has been arranged at the predetermined position, from being unnecessarily rotated. Thus, it is possible to prevent the substrate, which has been arranged at the predetermined position, from being unnecessarily rotated until all of the substrates are aligned, so that it is possible to decrease the opportunity to produce friction between the substrates and rotating means.
According to one aspect of the present invention, a substrate-attitude control system comprises: holding means for holding a plurality of disk-shaped substrates so that the substrates are rotatable in circumferential directions; rotation transmitting means for contacting a peripheral portion of each of the substrates to rotate the substrates; a rotation driving source for rotating the substrates; transmission switching means for selectively transmitting a power from the rotation driving source to the rotation transmitting means so as to be capable of switching transmission
on-transmission; detecting means for detecting a positioning notch formed in the peripheral portion of each of the substrates; and control means for controlling the operation of the transmission switching means on the basis of a detection signal outputted from the detecting means.
The control means may be capable of controlling the operation of the rotation driving source. The rotation transmitting means may be integral with the transmission switching means.
Preferably, the holding means comprises one or a plurality of holding rods having holding grooves for holding the substrates so that the substrates are able to be supported in the holding grooves of at least one of the holding rods.
The holding means may comprise one or a plurality of holding rods, each of which has a plurality of holding grooves for holding the substrates at regular intervals so that the substrates are able to be supported in the holding grooves of at least one of the holding rods; the rotation transmitting means may comprise a first rotation transmitting roller group comprising a plurality of transmission rollers for independently transmitting rotation to the substrates in odd rows, and a second rotation transmitting roller group comprising a plurality of transmission rollers for independently transmitting rotation to the substrate in even rows; the transmission switching means may comprise switching rollers, each of which is capable of selectively contacting a corresponding one of the transmission rollers of the first and second rotation transmitting roller groups, and a moving mechanism for moving the switching rollers so that each of the switching rollers contacts or leaves the corresponding one of the transmission rollers; and the detecting means may comprise a plurality of sensors for detecting the positioning notch formed in the peripheral portion of each of the substrates. In this case, the substrate-attitude control system preferably includes an intermediate roller, provided between the first and second rotation transmitting roller groups and the switching rollers of the transmission switching means, for contacting the transmission rollers of the first and second rotation transmitting roller groups and the switching rollers.
The holding means may comprise one or a plurality of holding rods, each of which has a plurality of holding grooves for holding the substrates at regular intervals so that the substrates are able to be supported in the holding grooves of at least one of the holding rods; the rotation transmitting means comprises a rotation transmitting roller group comprising a plurality of transm
Kimura Shigeru
Yamasaki Katuki
Morrison & Foerster
Ro Bentsu
Tokyo Electron Limited
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