Fluid handling – Systems – With pump
Reexamination Certificate
1999-09-29
2001-05-01
Chambers, A. Michael (Department: 3753)
Fluid handling
Systems
With pump
C137S875000, C118S720000
Reexamination Certificate
active
06223770
ABSTRACT:
FIELD
This invention relates to semiconductor processing equipment. More particularly the invention relates to a valve for use in connecting semiconductor processing equipment through their vacuum lines.
BACKGROUND
Vacuum technology is used extensively in the manufacture of semiconductor devices. One reason for this is that the components of an environment can be very closely controlled under very low pressures. In other words, by creating a vacuum and then creating a processing environment, such as by introducing a gas, the environment contains a very large percentage of the gas, and a very small percentage of any other constituents, known collectively as contaminants. In this manner, the materials being processed in the environments are exposed mostly to the gas that is introduced, and minimally to the contaminants.
In order to more tightly control the processes that are conducted within the vacuum equipment, it is desirable to gather certain information in regard to the process. Some of this information has to do with the process chamber itself, and other of the information has to do with the environment created within the process chamber. For example, the ability for a process chamber to maintain the vacuum that is drawn on the chamber is an important processing characteristic. If a chamber dissipates the vacuum too quickly, known as a high leak rate, then this situation introduces a relatively greater amount of contaminants into the chamber during a given period of time. At a certain point, a chamber with a leak rate that is too high is unfit to process semiconductor devices.
Further, it may be anticipated that during a portion of the processing of the semiconductor devices, a specific ratio of materials will be found in the effluent gases being drawn under vacuum from the processing chamber. If a different ratio is detected during processing, it might mean that there is something wrong with the process, or that the desired processing has been completed. In either case, this information is valuable to the process operator or process design engineer.
Many different types of instruments have been designed to detect the type of information described above, and many other types of information. These instruments typically operate by tapping into the process chamber in which the processing occurs, and on which the desired measurements are to be taken. Unfortunately, many process chambers are designed to remain at all times at a relatively low pressure, or in other words a relatively high vacuum, so that the chamber can be kept as free of contaminants as possible. Thus, repeatedly venting the chamber so as to insert and remove an instrument head from the chamber tends to degrade the cleanliness of the chamber, and is undesirable.
These test heads for the diagnostic instruments also create another problem. Many process chambers are designed to process a single wafer at a time, which tends to increase the uniformity of the processing across the wafer surface, and from wafer to wafer. Because of this design goal, the process chambers are relatively small. By tapping an instrument test head into the chamber, the volume of the process chamber is significantly increased. When the volume of the process chamber is altered in this manner, the process parameters themselves, such as residence time of any gases that may be introduced, are similarly effected. This creates a situation in which the reaction intended to occur within the process chamber may not proceed as anticipated.
What is needed therefore, is an apparatus for connecting a second vacuum apparatus to a semiconductor processing apparatus that does not require the chamber to vented when the second apparatus is connected and disconnected, and which does not appreciably alter the volume of the semiconductor processing chamber.
SUMMARY
The above and other needs are met by an interface for connecting a first vacuum source to a first vacuum apparatus, and for selectively connecting the first vacuum source and the first vacuum apparatus to a second vacuum apparatus without venting the first vacuum apparatus. A third fitting is connected to the first vacuum source, and makes a hermetic seal between the first vacuum source and the interface. A vacuum source line, having a first end and a second end, is connected by its first end to the third fitting. The vacuum source line receives a vacuum from the first vacuum source, and conducts the vacuum through the vacuum source line.
A first tee section, having a first end and a second end, is connected by its first end to the second end of the vacuum source line. The first tee section receives the vacuum from the vacuum source line and conducts the vacuum through the first tee section. A first fitting is connected to the second end of the first tee section, and connects the first tee section to the first vacuum apparatus by making a hermetic seal between the interface and the first vacuum apparatus. The first fitting conducts the vacuum to the first vacuum apparatus.
A second tee section, having a first end, a second end, and a second volume, is connected by its first end to the second end of the vacuum source line. The second tee section receives the vacuum from the vacuum source line and the first tee section and conducts the vacuum through the second tee section. The second volume of the second tee section is no greater than about two percent of the first volume of the first vacuum apparatus.
A valve, having a first end and a second end, it connected by its first end to the second end of the second tee section. The valve selectively makes a hermetic seal at the second end of the second tee section, and alternately conducts at least a portion of the vacuum conducted through the second tee section. A second fitting is connected to the second end of the valve, and selectively connects the valve to the second vacuum apparatus, and makes a hermetic seal between the interface and the second vacuum apparatus.
Because the second tee section only has a volume that is no greater than about two percent of the volume of the first vacuum apparatus, it does not tend to create an appreciable impact on the process conducted within the processing chamber of the first vacuum apparatus. Further, because the valve can be selectively closed between the second tee section and the second fitting, the second vacuum apparatus, which may be the test instrument, can be selectively mounted and removed from the second fitting, without venting the process chamber of the first vacuum apparatus, and thereby will not degrade the environment within the process chamber.
In various preferred embodiment of the interface, the second vacuum apparatus comprises a residual gas analyzer (RGA), a leak checker, or even another semiconductor processing apparatus. The second vacuum apparatus may also have a second vacuum source for selectively drawing a vacuum from the first vacuum apparatus through at least the second fitting, the valve, the second tee section, the first tee section, and the first fitting. Thus, the environment within the process chamber of the first vacuum apparatus can be sampled through the second tee section in this manner.
The first vacuum apparatus may be semiconductor processing equipment, such as an Applied Materials Precision 5000 plasma etcher. This piece of equipment is extremely difficult to attach an instrument to. First, the physical layout of the Precision 5000 severely restricts the locations to which an instrument may be attached. Secondly, the size of the processing chamber of the Precision 5000, and the types of processes that are conducted within it, make it extremely susceptible to volume changes, as described above. In other words, changes in the process chamber volume of the Precision 5000 of more than about two percent will have an appreciable effect on the processes conducted within it.
The first, second, and third fittings are preferably KF type fittings, such as KF25's. Alternately, the first, second, and third fittings comprise welds to the first vacuum apparatus, the second vacuum app
Chambers A. Michael
LSI Logic Corporation
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