Dry cleaning method

Details Dry cleaning method Dry cleaning method

2000-08-18

2002-12-31

Stinson, Frankie L. (Department: 1746)

Cleaning and liquid contact with solids

Processes

Including application of electrical radiant or wave energy...

C134S001300, C134S021000, C134S025100, C134S026000, C015S001510

Reexamination Certificate

active

06500268

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to techniques for cleaning objects. More particularly, the invention provides a technique including a method for cleaning objects using a combination of a high energy light source and electrostatic bias for removing impurities, such as particles and the like from integrated circuits, for example. But it will be recognized that the invention has a wider range of applicability; it can also be applied to other devices such as three-dimensional packaging of integrated semiconductor devices, photonic devices, opto-electronic devices, piezoelectronic devices, microelectromechanical systems (“MEMS”), sensors, actuators, solar cells, flat panel displays (e.g., LCD, AMLCD), biological and biomedical devices, and the like.
As integrated circuit device sizes become smaller, it is more desirable to remove particulate contamination from surfaces of such devices. Many techniques have been proposed or used to remove such particulate contamination. In the early days, such techniques have been limited to wet processing methods. These wet processing methods include a cascade rinse. The cascade rinse often utilizes a cascade rinser which includes inner and outer chambers, each separated by a partition. Rinse water flows from a water source into the inner chamber. The rinse water from the inner chamber cascades into the outer chamber. An in-process wafer such as an etched wafer is typically rinsed in the cascade rinser by dipping the etched wafer into the rinse water of the inner chamber. This process is often used to neutralize and remove acid from the etched wafer, which often remains in the rinse chamber to create particulate contamination problems.
Another technique often used to rinse wafers is the “quick dump” method. The quick dump method relies upon the rapid deployment of water from the rinse tank to remove water and impurities from the semiconductor wafer. A limitation with this method is its inability to actually clean or remove particles from the wafer. In fact, the rapid deployment of water from the tank often transfers more particles onto the wafer. In addition, the wafers from the quick dump tank must still undergo a drying operation, further increasing the number of particles on the wafer. As previously noted, more particles often relates to lower die yields on the semiconductor wafer.
A further technique used to both rinse and dry wafers relies upon a spin rinse/dryer. The spin rinse/dryer uses a combination of rinse water spray to rinse and centrifugal force to remove water from the semiconductor wafer. The dry step often removes the water from the semiconductor wafer substantially by centrifugal force and evaporation. However, the spin rinse/dryer often introduces more particles onto the wafer. In fact, initially dissolved or suspended contaminants such as particles in the water are often left on the semiconductor wafer, thereby reducing the number of good dies on the wafer. Another limitation with the spin rinse/dryer is its complex mechanical design with moving parts and the like. The complex mechanical design often leads to certain problems such as greater downtime, wafer breakage, more spare parts, greater costs, among others. A further limitation is static electricity often builds up on the wafers during the spin cycle, thereby attracting even more particles onto the surface of the semiconductor. Accordingly, the spin rinse/drying does not clean or remove particles from the wafer.
Other techniques used to dry wafers include an isopropyl alcohol (IPA) vapor dryer, full displacement IPA dryer, and others. These IPA-type dryers often rely upon a large quantity of a solvent such as isopropyl alcohol and other volatile organic liquids to facilitate drying of the semiconductor wafer. A limitation with this type of dryer is its use of the large solvent quantity, which is hot, highly flammable, and extremely hazardous to health and the environment.
Several dry techniques have also been used. For example, silicon wafers have been cleaned using an argon
itrogen cryogenic aerosol process. Such dry technique has had many promising characteristics, but has had limited use in the manufacture of integrated circuits so far. Other techniques that have been proposed but still lack wide acceptance in the manufacture of integrated circuits. Such techniques often require the use of expensive equipment, chemicals, and the like. Additionally, such techniques have proved not to be significantly effective for cleaning silicon wafers.
From the above, it is seen that an improved method for cleaning objects is highly desirable.
SUMMARY OF THE INVENTION
According to the present invention, a technique including a method for manufacturing objects is provided. More particularly, the invention provides a technique including a method for cleaning objects using a combination of a high energy light source and electrostatic bias for removing impurities, such as particles and the like from integrated circuits, for example. But it will be recognized that the invention has a wider range of applicability; it can also be applied to other devices such as three-dimensional packaging of integrated semiconductor devices, photonic devices, opto-electronic devices, piezoelectronic devices, microelectromechanical systems (“MEMS”), sensors, actuators, solar cells, flat panel displays (e.g., LCD, AMLCD), biological and biomedical devices, and the like.
In a specific embodiment, the present invention provides a method for cleaning objects (e.g., wafers, integrated circuits, photonic devices, opto-electronic devices, piezoelectronic devices, microelectromechanical systems (“MEMS”), sensors, actuators, solar cells, flat panel displays (e.g., LCD, AMLCD), biological and biomedical devices) of particles (e.g., particulate contamination) that attach themselves to surfaces of the objects. The method includes applying high energy (e.g., photons) from a high energy source (e.g., flash lamp, laser, light) on a surface of a substrate to release one or more particles from the surface of the substrate while maintaining the substrate in a predetermined (e.g., vacuum, atmospheric) environment; and applying an electrostatic source directed to the substrate to attract the released one or more particles from the substrate to remove the one or more particles from the surface of the substrate. The force should be applied simultaneously with the high energy source in some embodiments. The method also removes the substrate from the predetermined environment.
In an alternative embodiment, the invention provides a method for cleaning objects of particles that attach themselves to surfaces of the objects and chamber cleaning. The method includes inserting a substrate into a chamber. A step of applying a high energy source on a surface of the substrate to release one or more particles from the surface of the substrate while maintaining the substrate in a predetermined (e.g., vacuum) environment of the chamber is also included. The method applies an electrostatic source comprising an electrode directed to the substrate to attract the released one or more particles from the substrate to remove the one or more particles from the surface of the substrate. The substrate is removed from the chamber. The steps above are repeated for one or more substrates, until the electrode becomes dirty and ineffective. The method then inserts a collector substrate into the chamber; and applies a high energy light source on the electrode to release one or more particles from the surface of the electrode while maintaining the electrode in the predetermined (e.g., vacuum) environment of the chamber. An electrostatic source is applied to the collector substrate to attract the released one or more particles from the electrode to the collection substrate to remove the one or more particles from the surface of the electrode to clean the electrode from the particles. The collector substrate permanently removes the particles from the electrode and other areas of the chamber. The method removes the collection substrate

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