The present invention relates to semiconductor fabrication equipment, and in particular, relates to an apparatus for supporting and maneuvering (transporting) wafers between a plurality of wafer processing stations in an automated manner.
In the fabrication of semiconductor devices, IC wafers, which typically take the form of flat disks made from silicon, gallium arsenide or other materials, may be processed using various chemicals. During the fabrication process, the wafers are often thinned to expose interconnect pads to provide fan-out wafer level packaging (FOWLP). One promising technique for thinning is single wafer wet etching, in which wafers are immersed in one or more etchants, then cleaned and dried. Each of these steps in the fabrication process occurs within a separate station within a wet etching processing system. The wafers, being thin and sensitive to slight damage, must be transferred between the stations with great care.
Processing systems typically employ a robot arm that can swivel, pivot and/or translate from one station to another within the processing system. The robot arms may be equipped with grippers and vacuum suction to secure wafers from shifting horizontally or vertically during transfers between stations. However, one drawback of using conventional vacuum suction to secure wafers is that the suction forces the wafer surface into contact with the supporting surface on the robot arm, which can potentially damage components on the wafer surface.
It would therefore be advantageous to provide a robot arm support for wafer transfers that avoids undue forcible contact with wafer surfaces.
It is with respect to these and other considerations that the disclosure made herein is presented.
Embodiments of the present invention provide an apparatus for supporting and maneuvering a wafer. The apparatus comprises a handle section including a gas inlet adapted to couple to a gas supply, a supporting surface coupled and adjacent to the handle section including a frame structure having a plurality of edge segments connecting to one another at vertices and a plurality of spoke elements extending from a center of the frame structure to the vertices, a gas supply channel coupled to the gas inlet that extends from the handle and branches into channels that run through the plurality of spoke elements, and a plurality of nozzles positioned at the vertices on the supporting surface and coupled to the gas supply channel via the channels in the spoke elements. Gas provided to the plurality of nozzles exits the nozzles in a high-speed stream directed parallel to the supporting surface, and the stream of gas generates attractive and repulsive forces enabling a wafer to be securely supported in a floating manner over the supporting surface without coming into direct contact with the supporting surface or the plurality of nozzles.
In some embodiments, the apparatus further comprises a vacuum check port positioned in the handle and a vacuum check circuit that extends from the vacuum check port through the edge segments of the supporting surface frame structure to the plurality of nozzles, wherein the vacuum check circuit enables detection of whether a wafer is being supported by the supporting surface. The apparatus can also include at least one restraining device adapted to prevent a supported wafer from moving in a plane parallel to the supporting surface. In some implementations, the restraining device includes movable grippers coupled to the handle and stationary retainers coupled to an end of the supporting surface.
The gas supply preferably provides a supply of nitrogen gas. In certain embodiments, each of the plurality of nozzles includes an annular top plate joined at an inner rim to a bottom plate, the bottom plate having a set of holes coupled to a respective spoke channel that are configured to force supplied gas through an interface between the outer rim of the top plate and the bottom plate.
Embodiments of the present invention also provide a system for supporting and maneuvering a wafer. The system comprises an apparatus for supporting and maneuvering the wafer that includes a handle section including a gas inlet adapted to couple to a gas supply, a supporting surface coupled and adjacent to the handle section including a frame structure having a plurality of edge segments connecting to one another at vertices and a plurality of spoke elements extending from a center of the frame structure to the vertices, a gas supply channel coupled to the gas inlet that extends from the handle and branches into channels that run through the plurality of spoke elements, and a plurality of nozzles positioned at the vertices on the supporting surface and coupled to the gas supply channel via the channels in the spoke elements, the plurality of nozzles providing a high speed stream directed parallel to the supporting surface. The system further includes a control sub-system positioned between the gas supply and the apparatus and adapted to regulate a pressure supplied to the apparatus based on a size of the wafer.
In some embodiments the control sub-system includes a pressure sensor coupled to the gas supply and adapted to determine a current gas pressure of the gas supply and an electronic pressure regulator coupled to the pressure sensor and adapted to receive pressure data from the pressure sensor and to modify the pressure of gas received from the gas supply based on the pressure data and the size of the wafer to be supported. Implementations of the control sub-system can also include a filter positioned downstream from the electronic pressure regulator for removing impurities from the gas supply before the gas reaches the apparatus. The gas supply of the system preferably provides a supply of nitrogen gas.
These and other aspects, features, and advantages can be appreciated from the following description of certain embodiments of the invention and the accompanying drawing figures and claims.
Embodiments of the present invention provide an apparatus for supporting and maneuvering wafers that is shaped in the form of a paddle and configured to transport a wafer between processing stations. The paddle includes one or more nozzles, referred to as “Bernoulli nozzles”, that generate a lateral flow of high speed gas, such as nitrogen (N2). The high-speed gas flow creates a low-pressure region in the vicinity of the gas flow according to the well-known Bernoulli equation. The low-pressure region, in turn, generates a lift force that attracts objects toward the nozzles. In addition, in some embodiments, the apparatus includes mounts for the one or more nozzles that have walls higher than the nozzle surfaces. This mount configuration forces the flow of gas exiting the nozzles through a narrow gap which creates a countervailing repulsive force in the opposite direction of the lift, away from the nozzles. With suitable control of gas pressure and mount design, the opposing attractive and repulsive forces can be set to balance one another, enabling a wafer to be supported at a distance from the nozzle in a floating manner, avoiding contact between the wafer and the surface of the nozzles on the paddle. Advantageously, the balance of attractive and repulsive forces produced by the gas flow can maintain the wafer in place relative to the supporting surface when the wafer is positioned on top of the paddle surface, in an upside-down arrangement in which the wafer is positioned below the paddle, and at oblique angles in between. Thereby, the paddle can be turned while still supporting a wafer, enabling the wafer to be flipped for two-sided processing.
In the depicted embodiment, each of the vertices 131-136 of the supporting surface include a mount for receiving a Bernoulli nozzle as described further below. The overall sizes and dimensions of the apparatus 100 and its components are designed to accommodate a standard-sized semiconductor circular wafer of a diameter such as 200, 300 or 450 mm. It is to be appreciated however that the apparatus can be adapted for smaller or larger-sized wafers.
Referring now to
Turning now to the cross-sectional view of
In operation, when nitrogen gas is supplied to the Bernoulli nozzles of the supporting apparatus, a high-speed radial flow of gas is generated, creating a lower pressure region. The low pressure provides an attractive lift force which causes wafers place on the supporting surface to adhere. Since the walls of the mount at the flange are positioned above the nozzle surface, nitrogen gas that exits the nozzle is forced through a small gap between the mount flange and the wafer, which generates a counteracting repulse force tending to push the wafer away from the nozzle. Pressure regulation allows a balance to be achieved between the lift and repulsion, enabling the wafer to float in place a small gap distance from the supporting surface.
In the embodiments depicted, several nozzles are installed on a single paddle apparatus for handling wafers. The apparatus can be actuated such that wafers can be picked up from below, with the nozzles underneath the wafer, and then flipped over with the wafer in it, allowing the wafer to be put down with the nozzles on the top side of the wafer. In this way, the apparatus allows both sides of the wafer to be processed conveniently.
The combination of the movable grippers and stationary retainers prevent wafers from floating off the paddle to the sides. The movable grippers are retracted to pick up wafers and then moved gently to rest against the wafer, securing the wafer in place on the supporting surface of the paddle. When secured by the grippers and retainers, the precise location of a retained wafer is defined, which allows the wafer to be accurately moved and positioned.
In addition, the vacuum check channel can be plumbed to a pressure sensor. The pressure read will vary largely between two values, a lower value which indicates that a wafer is positioned above the supporting surface of the paddle, and a higher value indicating that the wafer is absent. The wafer present/absent indication can be used as a control signal for adjusting a robot arm to move, pick up, deploy, and/or put down a wafer in a location in a processing station.
It is to be understood that any structural and functional details disclosed herein are not to be interpreted as limiting the systems 112 and methods, but rather are provided as a representative embodiment and/or arrangement for teaching one skilled in the art one or more ways to implement the methods.
It is to be further understood that like numerals in the drawings represent like elements through the several figures, and that not all components and/or steps described and illustrated with reference to the figures are required for all embodiments or arrangements
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Terms of orientation are used herein merely for purposes of convention and referencing and are not to be construed as limiting. However, it is recognized these terms could be used with reference to a viewer. Accordingly, no limitations are implied or to be inferred.
Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications will be appreciated by those skilled in the art to adapt a particular instrument, situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
The present invention claims priority to and the benefit of US patent application Ser. No. 62/686,494, filed Jun. 18, 2018, which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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62686494 | Jun 2018 | US |