Wet Surface Treatment By Usage of a Liquid Bath Containing Energy Limited Bubbles
a technology of liquid bath and wet surface, which is applied in the direction of cleaning process and equipment, cleaning process using liquids, chemistry apparatus and processes, etc., can solve the problems of fragile surface cleaning and/or ultra-cleaning process, easy to have unwanted debris, unwanted impurities or unwanted other matter trapped in difficult to reach recesses,
Inactive Publication Date: 2013-03-07
GOTKIS YEHIEL
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- Abstract
- Description
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- Application Information
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Benefits of technology
This approach allows for effective removal of unwanted particulate matter and impurities while preventing damage to fragile surface features, maintaining high cleanliness and purity levels without deteriorating production yields.
Problems solved by technology
As a result of such shrinkages and / or trends toward extremely asymmetric feature geometries, the on-wafer features that need to be preserved throughout the surface preparation, surface cleaning and / or ultracleaning processes have become more fragile, more susceptible to damage and more prone to having unwanted debris, unwanted impurities or unwanted other matter trapped in difficult to reach recesses.
Fragility of thin surface films and / or of ultra-fine surface patterns (e.g., delicate PR patterns) is a growing problem, particularly as the fragile surface features are subjected to cleaning / purifying liquids in combination with physical agitations or other applied energies (e.g., ultrasonic energy) that are poorly controlled and thus can become excessive.
This confluence of trends presents new challenges that artisans in the surface treatment and cleaning fields have not previously encountered.
However, a variety of uncontrolled wave interference and wave reinforcement patterns tend to develop at the wafer surface during use of Megasonic cleaning.
Without wishing to be bound to any specific theory, it is believed that these uncontrolled interfering and / or reinforcing ultrasonic wave patterns tend to create so called, pressure hot-spots at which excessive forces or temperatures build up to potentially damage or deform (e.g., collapse) the delicate films and / or fine patterns that are generally intended to be left behind and intact on the wafer work surface after the surface preparation, cleaning and / or ultracleaning processes complete.
As a result of such potentially damaging or deforming mechanisms, popular cleaning techniques such as Megasonics can cause production yields to disadvantageously deteriorate when applied to finely pitched patterns and / or ultra-thin surface films such as may be found on in-process silicon or other semiconductor wafers during mass production.
A rising and fast cooling bubble in such a case experiences rapid vapor condensation, resulting in the internal pressure drop and size contraction.
As the not-fully-collapsible surface sweeping bubble sweeps along the to-be-treated surface, the bubble tends to pick up unwanted and pre-loosened surface debris.
When a full or partial rapid bubble collapse occurs along the bubble rise path, the collapse event can produce localized agitation or shock waves of magnitude-limited levels near the to-be-cleaned surface.
Method used
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[0034]FIG. 1A is a conceptual cross sectional diagram of a wet cleaning system 100 in accordance with the disclosure. Some parts are not illustrated or may be shown rotated 90 degrees to their actual position so as to better relate certain concepts, as will become clearer below. Also, various features shown in FIG. 1A are not necessarily to scale.
[0035]In terms of general context, a supplied workpiece 115 is shown to be immersed face down in a liquid cleaning bath 121-122 and held by a moveable chuck 131 that is also referred to herein as a primary cooler 131. The workpiece 115 itself can be a finely patterned and / or thin film coated semiconductor wafer (e.g., one having a monocrystalline silicon substrate as part of its monolithic structure) where fabrication of the wafer is currently in-process and thus not fully completed. Alternatively, the workpiece can be another device or manufacture requiring delicate and ultra-pure cleaning and / or other surface treatment. It is to be unders...
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Abstract
A method controllably and sustainably creates an upwardly directed gradient of dropping temperatures in a wet treatment tank between a cooled and face down workpiece (e.g., an in-process semiconductor wafer) and a lower down heat source. A thermal fluid upwell containing thermally collapsible bubbles is then directed from the heat source to the face down workpiece. In one class of embodiments, bubble collapse energy release and / or bubble collapse locations are controlled so as to avoid exposing delicate features of the to-be-treated surface to damaging forces. In one class of embodiments the wet treatment includes ultra-cleaning of the work face. Cleaning fluids that are essentially free of predefined contaminates are upwelled to the to-be-cleaned surface and potentially contaminated after-flows are convectively directed away from the workpiece so as to prevent recontamination of the workpiece.
Description
FIELD OF DISCLOSURE[0001]The present disclosure of invention relates generally to wet treatments of delicate surfaces where such surfaces can be permanently or temporarily damaged by application of forces of excessive magnitude and / or by application of solutions that contain excessive quantities of undesired materials. Such wet treatments may include selective removal of unwanted particulate matter or unwanted impurities from a surface of a workpiece; a process that is sometimes referred to as surface preparation or surface cleaning. The disclosure relates more specifically to cleaning of workpieces having fine or delicate surface features such as may be found in in-process semiconductor wafers.CROSS REFERENCE TO CO-OWNED APPLICATION[0002]The following copending U.S. provisional patent application is owned by the owner of the present application, its teachings of inventive concepts are incorporated herein by reference and benefit of its filing date is claimed to the extent allowed b...
Claims
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IPC IPC(8): B08B3/10
CPCH01L21/02057B08B3/102
InventorGOTKIS, YEHIEL
OwnerGOTKIS YEHIEL