Reactor for processing a workpiece using sonic energy

Details Reactor for processing a workpiece using sonic energy Reactor for processing a workpiece using sonic energy

2001-07-16

2003-01-28

Smith, Matthew (Department: 2825)

Semiconductor device manufacturing: process

Chemical etching

Combined with coating step

C438S691000, C438S782000, C438S913000, C269S020000, C269S021000, C156S345420, C134S153000, C134S157000

Reexamination Certificate

active

06511914

ABSTRACT:

The invention relates to surface preperation, cleaning, rising and drying of workpiece, such as semiconductor wafers, flat panel displays, rigid disk or optical media, thin film heads, or other workpieces form from a substrate on which microelectronic circuits, data storage elements or layers, or micro-mechanical elements may be formed. These and similar articles are collectively reffered to here as a “wafer” or “workpiece”.
BACKGROUND OF THE INVENTION
The semiconductor manufacturing industry is constantly seeking to improve the processes used to manufacture microelectronic circuits and components, such as the manufacture of integrated circuits from wafers. The objectives of many of these improved processes are decreasing the amount of time required to process a wafer to form the desired integrated circuits; increasing the yield of usable integrated circuits per wafer by, for example, decreasing contamination of the wafer during processing; reducing the number of steps required to create the desired integrated circuits; and reducing the costs of manufacture.
In the processing of wafers, it is often necessary to subject one or more sides of the wafer to a fluid in either liquid, vapor or gaseous form. Such fluids are used to, for example, etch the wafer surface, clean the wafer surface, dry the wafer surface, passivate the wafer surface, deposit films on the wafer surface, etc. Controlling how the processing fluids are applied to the wafer surfaces, is often important to the success of the processing operations.
Various machines and methods have been used for carrying out these manufacturing processes. However, existing machines have several disadvantages. These disadvantages include relatively large consumption of process chemicals and water. This consumption of process chemicals increases manufacturing costs, which ultimately increases the cost of the final product, such as e.g., computers, cell phones, and virtually all types of consumer, industrial, commercial and military electronic products. In addition, many process chemicals are toxic and require special handling, storage, and disposal methods. These can be costly and difficult, but are necessary for health, safety and environmental reasons. Consequently, reducing consumption of process chemicals has many advantages.
Reducing consumption of water is also beneficial. In many areas, water is becoming increasingly scarce. Due to population growth, there is greater competition for water. Disposing of waste water in environmentally friendly ways has also often become more difficult or costly. Accordingly, reducing water consumption in the manufacturing process is also important.
In many process manufacturing steps, the process chemicals used should be applied evenly onto the wafers, to avoid having too much or too little etching, film removal, etc. Existing machines often are not able to sufficiently uniformly apply process chemicals. This can result in lower yields. Moreover, many existing machines try to compensate for variations in applying process chemicals by using larger amounts of process chemicals. This inefficient use of process chemicals leads to the disadvantages described above. Accordingly, improved machines and methods which provide improved yield, consume less process chemicals and water, and offer better results in performing manufacturing operations, are needed.
Manufacturing semiconductor and similar products on a commercial scale requires a fab or manufacturing facility often costing hundreds of million dollars to build and equip. Operating and maintenance costs are also very high. Consequently, the output or yield of the fab is critical to successful operations. Faster processing can help increase the fab output. While conventional processing with liquids may produce the desired results, it can be time consuming. Accordingly, faster process methods and machines are very advantageous.
SUMMARY OF THE INVENTION
Machines and methods have now been invented which overcome the disadvantages described above. In one design, the machine includes a workpiece housing having a processing chamber. Processing fluids are distributed across the surface of the workpiece in the processing chamber, by centrifugal force.
In a first aspect, a system for processing a workpiece includes a bowl, chamber or recess for holding a liquid. A sonic energy source is associated with the bowl for introducing sonic energy into the liquid in the bowl. A process head lifter is positioned to move at least part of a process head holding a workpiece into and out of the liquid in the bowl. The process head preferably includes an upper element or rotor and a lower element or rotor, with the upper and lower rotors or elements engageable around a workpiece. Where upper and lower rotors are used, the process head also includes a motor or other device or technique for spinning the rotors.
In a second aspect, a sonic transducer, such as a megasonic or ultrasonic transducer is used as the sonic energy source.
In a third aspect, the lower rotor or element is moveable into a position where it substantially surrounds the sonic transducer. The transducer may be fixed in place within the bowl. Alternatively, the transducer may be on or in the upper and/or the lower rotors or elements.
In a fourth aspect, one or more liquid supplies are connected to the bowl. The liquid supplies provide liquids to the bowl, which may include water, HF, and ozonated water, or other cleaning chemistries such as SC
1
, SC
2
, Piranha, etc., and a combination of them.
In a fifth aspect, the sonic energy source or transducer has an opening with a liquid outlet nozzle positioned under the opening, with the nozzle positioned to apply a liquid or gas or vapor to a lower surface of the workpiece.
In a sixth aspect, a method for processing a workpiece includes the steps of holding a workpiece between an upper rotor or element and a lower rotor or element, and contacting the workpiece with a bath of liquid. Sonic energy is introduced into the bath of liquid and transmitted through the liquid to the workpiece. The workpiece is then rotated, during and/or after contact with the bath.
The use of sonic energy in these aspects expedites processing and provides more efficient processing. The use of sonic energy with reactors, such as described in International patent application No. WO 99/46064, (published Sep. 16, 1999 and incorporated herein by reference) which are currently in use is counter-intuitive, due to their often closed configuration; spinning rotors; and/or lack of a continuous liquid volume around the workpiece. It has now been discovered, however, that sonic energy can indeed be used in these types of reactors, providing improved processing.
Accordingly, it is an object of the invention to provide improved methods and apparatus for processing a workpiece. The invention resides as well in subcombinations of the steps and features described. The features described and illustrated in connection with one embodiment may or course be used in other embodiments as well.


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