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AssigneeNorthrop Grumman Corporation
InventorsMichael D. Lammert, Victor J. Watson, John M. DiMond, Michael E. Barsky
Estimating the term…
Semiconductor wafer (11) are uniformly and thoroughly cleaned of particulate and organic contaminants by sweeping the wafer with a hydraulic broom that sprays cleaning solution onto the wafer. The broom contains an aspirating nozzle (3) for connection to a source of pressurized gas, such as nitrogen, and to a source of cleaning fluid, such as acetone, wherein cleaning fluid aspirated by the gas stream is expressed through the nozzle outlet to impact the surface of the wafer, dislodging particulate matter and dissolving organic contaminants. A programmed controller (9) controls movement of the hydraulic broom relative to the wafer to ensure that the entire surface is cleaned and permits a variety of sweeping patterns.
An automated cleaning apparatus for cleaning semiconductor wafers, comprising:
The cleaning apparatus for cleaning semiconductor wafers, comprising:
The method of cleaning the surface of a semiconductor wafer comprising the steps of:
Dependencies are inferred from the claim text.
From the US filing history. Foreign family members aren’t listed.
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For wet cleaning or washing: using mainly spraying means, e.g. nozzles
Cleaning by the force of jets or sprays: cleaning by means of spray elements moving over the surface to be cleaned
Cleaning by methods involving the use of air flow or gas flow: cleaning by the force of jets, e.g. blowing-out cavities
Generic processes or apparatus for the manufacture or treatment of devices covered
Term ended 13 Dec 2021 (estimated)
This invention relates to cleaning of semiconductor wafers, including Germanium, Silicon and all other semiconductor compounds, such as Gallium Arsenide (“GaAs”) and Indium Phosphide (“InP”) and, more particularly, to a method and apparatus for thoroughly spray cleaning the surface of semiconductor wafers of particulate and organic contaminants in a manner that assures uniform and reproducible cleanliness of each wafer cleaned.
Semiconductor devices are typically fabricated on single crystal wafers of semiconductor materials using photo-lithographic mask and etch or ion-bombardment techniques. Typically the wafer contains a large number of semiconductor devices which are fabricated simultaneously. Initially, and at the completion of each step in the semiconductor fabrication process, some residue remains; the kind or type of residue being in part dependent on the stage of fabrication processing, and the wafer surface must be cleaned in preparation for a succeeding step. Depending upon the particular process step in the semiconductor device fabrication process being completed, the completion of a particular process step may incidentally also produce particulate debris, organic contaminants and/or unwanted pieces of thin film metallization layers on the surface of the semiconductor wafer. The residue, particulate debris, organic contaminants and metal pieces must be removed before proceeding with the next step in the fabrication process.
Mass produced semiconductors typically employ silicon technology and cleaning equipment exists to handle such mass production. Such cleaning equipment, however, is unsuited to semiconductors that use the III-V compounds identified in the Periodic Table of the Elements, such as InP and GaAs. First, cleaning solvents used for cleaning silicon wafers are either strong acids or strong bases, which are very harsh chemicals inappropriate for InP and GaAs wafers and produces a lower overall cleanliness. As an advantage, the present invention avoids harsh chemicals detrimental to the wafer. Second, the semiconductor chips produced on silicon wafers are not as fragile as the semiconductor chips fabricated on InP or GaAs wafers. Certain cleaning apparatus designed for cleaning of silicon wafers, such as brush scrubbing, produces structural damage when applied to cleaning of semiconductor devices constructed on InP or GaAs or other compound semiconductor wafers, especially for wafers containing gold metallization layers. As an advantage, the present cleaning system is less harmful mechanically to the semiconductor chips on the wafer.
In the drawings:
FIG. 1 illustrates a wafer cleaning system in accordance with the invention;
FIG. 2 illustrates a preferred routing program of the relative movement of the wafer and spray nozzle elements in the operation of the embodiment of FIG. 1;
Reference is made to the pictorial illustration of FIG. 1, illustrating a wafer cleaning system constructed in accordance with the invention. The cleaning system includes a vacuum chuck 1 and a fluid nozzle 3 that are coupled, as hereafter described in greater detail, to a three axis positioner 5, X-axis, Y-axis and theta (rotation) axis positioning, all of which components are contained within a housing 7, represented by dash lines, and a programmed controller 9 that controls operation of the positioner.
A semiconductor wafer 11, represented as having a rectangular geometry is illustrated seated upon chuck 1, for the purpose of assisting in the description of operation, later herein presented, it being understood that the wafer is not a component of the apparatus, but is to be acted upon by the apparatus. For purposes of discussion the sides of the wafer labeled “a” and “b” are designated as the front and back edges of the wafer, respectively, and the sides labeled “c” and “d” are designated as the left and right side edges, respectively, of the wafer. The foregoing designation is arbitrary and is solely for the purpose of providing reference locations helpful in the description of operation of the invention.
Positioner 5 is controlled by a programmed controller 9, which may be a micro-controller that is operated in accordance with a hard-wired program in read-only memory (“ROM”) or a general purpose computer programmed with software to carry out the described functions. The positioner is illustrated as a servo-motor driven belt type system for the X and Y axis positioning and a pneumatic stepper motor for theta (rotation).