1. Field of the Invention
Embodiments of the present invention generally relate to apparatus and methods for supporting and transferring substrates during photomask fabrication.
2. Description of the Related Art
A technique commonly used to form precise patterns on substrates is photolithography. In conventional photolithographic processes, a photoresist material is applied on a substrate layer to be etched. A light source emitting ultraviolet (UV) light is typically used to expose the photoresist layer to chemically alter the composition of the photoresist. However, the photoresist layer is only selectively exposed. In this respect, a photomask, or “reticle,” is positioned between the light source and the substrate being processed. The photomask contains the desired configuration of features for the substrate. The exposed, or alternatively, the unexposed photoresist material is then removed to expose the underlying material of the substrate. The retained photoresist material remains as an etch resistant pattern on the substrate. The exposed underlying material may then be etched to form the desired features in the substrate, i.e., contacts, vias, or other features.
Photolithographic photomasks, or reticles, typically comprise a substrate of an optically transparent silicon based material, such as quartz. A light-shielding layer of metal, typically chromium, is patterned on the surface of the substrate. The metal layer is patterned and etched to form features which define the pattern, and correspond to the dimensions of the features to be transferred to a substrate, such as a semiconductor substrate.
The deposition and etching processes employed to fabricate the photomask requires that the substrate be transferred and supported within a processing system. It has become desirable to utilize processing equipment and systems which are configured for processing the substrates themselves when fabricating the photomasks. However, these systems are typically configured to process circular substrates, and must be reconfigured to support and transfer rectangular photomasks. In addition, the systems used to support and transport the substrates used in photomask fabrication must carefully handle the substrates to prevent scratches and other defects from being formed on the substrates. These defects can alter the light transmission properties of the substrates and result in defective photomasks.
Therefore, there is a need for a method and apparatus for transferring and supporting substrates in processing systems which minimizes defect formation.
The present invention generally provides an apparatus to minimize defect formation in a substrate during processing and handling of substrates in a plasma etch chamber by supporting a portion of a substrate in a chamber to minimize contact between the substrate and the chamber components during processing.
In one aspect, an apparatus is provided for supporting a substrate including a base plate having an inner perimeter and an outer perimeter, a substrate support member extending horizontally from the inner perimeter of the base plate, at least one substrate support guide extending horizontally from the inner perimeter of the base plate and disposed adjacent the substrate support member, wherein the substrate support member and the at least one substrate support guide are adapted to receive a portion of a substrate.
In another aspect, an apparatus is provided for supporting a substrate including a ring, a plurality of spacers disposed on the ring, a plurality of substrate receiving members disposed on the plurality of spacers, wherein the substrate receiving members comprise a base plate having an inner perimeter and an outer perimeter, at least one substrate support guide extending horizontally from the inner perimeter of the base plate and disposed adjacent the substrate support member, wherein the substrate support member and the at least one substrate support guide are adapted to receive a portion of a substrate and the inner perimeter of the base plates are positioned to face an axis of the ring.
The apparatus may be used in a loadlock chamber further including one or more walls defining an enclosure, the walls having a sealable loading port selectively sealable by a door and at least one substrate transfer slot selectively sealable by one or more slit valves, the substrate transfer slots disposed substantially opposite of the loading port, at least one substrate support disposed in the enclosure, each substrate support including a ring, a plurality of spacers disposed on the ring, a plurality of substrate receiving members disposed on the plurality of spacers, wherein the substrate receiving members comprise a base plate having an inner perimeter and an outer perimeter, a substrate support member extending horizontally from the inner perimeter of the base plate, and at least one substrate support guide extending horizontally from the inner perimeter of the base plate and disposed adjacent the substrate support member, wherein the substrate support member and the at least one substrate support guide are adapted to receive a portion of a substrate and the inner perimeter of the base plates are position to face an axis of the ring. The loadlock chamber may also be used in a substrate processing system comprising a transfer chamber, at least the one processing chamber coupled to the transfer chamber, and a substrate handler disposed in the transfer chamber.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
Aspects of the invention will be described below in reference to a photolithographic reticle, or photomask, etch system having an inductively coupled plasma etch chamber. The photomask etch system may be a cluster tool similar to that shown in
Transfer of a substrate 218 between the process chambers 112 is typically managed by a substrate handling module, or substrate handier, 118, preferably with the substrate handling blade 150 mounted thereon. The substrate handler 118 is located in the central transfer chamber 114. After a substrate is processed, the substrate is retrieved from the processing chambers 112 and transferred to one or more of the load lock chambers 116 and into one or more substrate cassette (not shown) disposed within the one or more load lock chambers 116. The substrates can then be retrieved from the loadlock chambers 116 and transferred to the next system for additional processing. In photomask manufacturing processing, the process chambers 112 are etching chambers, preferably plasma etching chambers
A substrate support ring 220 is disposed within the loadlock chamber 116 to support the substrates 218 in a spaced relationship in the loadlock chamber 116 so that a substrate handler 118 can pass between the substrates 218 to place and remove substrates 218 from the loadlock 116. The substrate support ring 220 preferably supports a plurality of substrates 218 in a vertically displaced arrangement on substrate receiving members 222 disposed on the substrate support ring 220 as shown in
The substrate receiving members 222 are typically disposed in pairs having an inward facing orientation and are supported in spaced relation by spacers (not shown). The substrate supporting ring 220 may hold a plurality of sets of substrate receiving members 222 and may be vertically disposed from each other at a sufficient distance to allow a substrate handler to position and remove substrates 218 therefrom, such as a distance between about 0.1 inches and about 6 inches, for example, about 0.6 inches to about 0.7 inches apart. In the embodiment shown in
The substrate receiving members 222 are adapted to define an opening 217 that a substrate handler blade. 150 can be moved to transfer a substrate with minimal contact between components of the system. An example of a suitable substrate handler blade is described in U.S. Pat. No. 6,537,011 issued on Mar. 25, 2003, and incorporated herein by reference to the extent not inconsistent with the disclosure and claimed aspects herein. While not shown, an actuator may be coupled to the loadlock 116 to raise and lower the loadlock to vertically displace the substrate receiving members 222 to align and receive substrates from a plane of the substrate handler.
An on-board vacuum pump (not shown) is mounted on the system 100 adjacent the loadlock chamber 116 and the transfer chamber 114 to pump down the loadlock chamber 116 and the transfer chamber 114. An exhaust port (not shown) is disposed through the bottom of the loadlock chamber 116 and is connected to the pump via exhaust line. The pump is preferably a high vacuum turbo pump capable of providing milliTorr pressures with very low vibration.
Referring to
Spacers 234 are adapted to be mounted on the annular ring structure 230 and may be further adapted to be mounted on the substrate receiving members 222. The spacers 234 include one or more apertures for receiving a fastener 235 and may also have one or more protrusion for mating with apertures in the substrate receiving members 222 or annular ring structure 230 surface. Multiple spacers and corresponding substrate receiving members 222 may be aligned and secured by one or more fasteners to provide a stack for receiving more than one substrate. The spacers 234 and the substrate receiving members 222 can form sets that may be repeatedly stacked to form any number vertically displaced sets as the loadlock will physically allow. The spacers 234 and the substrate receiving members 222 are configured on the annular ring structure vertically above or below the plane of the annular ring structure 230 and are configured to define an opening 217 for a substrate handler to position and remove substrates therefrom. The spacers 234 typically provide a spacing of between about 0.1 inches and six inches between substrate receiving members 222 mounted thereon and the ring 230, for example, the spacer 234 may have a thickness of about 0.625 inches and provide a distance between substrate receiving members of at least that distance
The spacers are typically disposed diametrically opposed from each other on the annular ring structure 230. However, variation in the number and orientation of the spacers 234 may occur for supporting substrates in the loadlock chamber. The spacers are made of a material that is inert or substantially inert with etching gases or processing gases that may contact the spacers, such as aluminum or aluminum oxide, as well as suitable polymers or rubbers.
Alternatively, while not shown, the spacers 234 may be adapted to have one or more shelves or lips to provide additional contact surface with the substrate receiving members 222 to help distribute stress or weight when receiving a substrate. The shelf or lip may be a parallel extension of a surface of the spacer 234 that contacts the substrate receiving surface 222, or alternatively, annular ring structure 230.
Referring to
The lower portion 266 of the substrate support member 260 has an inclined surface for receiving the substrate thereon, such as the edge of the substrate. The surface is inclined at an angle a between about 2° and about 7°, preferably between about 2.5° and about 5°, for example, about 2.5°. The inclination of the substrate support member 260 minimizes the surface area contact between the substrate 218 and the substrate support member 260 as shown in
Referring to
The substrate receiving member 222 may further comprise one or more substrate support guides 270. The substrate support guides 270 extend from the base plate 252 along a substantially horizontal plane with the base plate 252. The substrate support guides are generally formed at the ends of the inner perimeter 256 on either side of the substrate support member 260. The substrate support guides are adapted to contact or enclose the sides of a substrate 218 positioned on the substrate support member 260 of the substrate receiving member 222.
The substrate support guides include an inner surface 271 and an outer surface 272. The inner surface 271 has a thickness of approximately the thickness of the base plate 252 and at least a portion up to the complete thickness of the inner surface 271 is angled. The angled surface comprises an inwardly sloping angle θ from the normal of between about 5° and about 30°, such as 15°. In one embodiment of the inner surface 271, the angled surface has the same angle as the upper aligning surface 264 of the angular support portion 261. The angled inner surface 271 is believed to further minimize contact with a substrate 218 disposed thereon. Optionally, recesses 275 are disposed between the substrate support guides 270 and the substrate support member 260 to also further minimize contact with a substrate 218 disposed thereon.
The substrate support member 260 is generally formed from of an etch resistant, high temperature resistant material, such as aluminum or aluminum oxide, to enable the substrate support member 260 to be used repetitively in the etching process without damage such as scratching or deformation.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.