Heat exchange – With retainer for removable article
Patent
1997-07-28
1998-07-14
Leo, Leonard R.
Heat exchange
With retainer for removable article
118725, F28F 700
Patent
active
057789690
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates in general to the processing of thin film wafers and more particularly to an improved apparatus for the thermal treatment of a thin film wafer in a high vacuum condition.
BACKGROUND OF THE INVENTION
Historically there has existed a drive in the semiconductor industry to reduce the size of the circuit elements of an integrated circuit. This both increases the number of circuits in a particular space and increases the speed of those circuits. The number of elements in a particular space is known as the integration density of the circuit where a greater number of elements in a particular space corresponds to a higher integration density.
The drive to higher integration densities, however, has meant that manufacturing methods that worked at a lower integration density might not work at a higher integration density. This is usually due to the minuteness of the resulting dimensions involved at higher integration densities. For example, at the relatively low integration density required for fabricating 1 MB DRAMs and 4 MB DRAMs, the aspect ratio of the height to the width of the elements was also relatively low. As a result, the method of metalization of the contact or via holes by wiring materials connecting the elements was possible by forming a metal film using sputter deposition equipment. However, at the relatively high integration density required for fabricating 64 MB DRAMs and 256 MB DRAMs, the aspect ratio is relatively high and the previous method of using sputter equipment to fill such holes is unsatisfactory. In order to overcome this, new methods are being developed so that a thin film deposited by the sputter equipment can form a metal film by self-diffusion of the atoms. This self-diffusion of the atoms is accomplished by first sputter depositing a thin film on the wafer and then heating the wafer at a temperature below its melting point in a chamber maintained in a continuous vacuum. This is known as a reflow process.
Further, the drive to higher integration densities has meant that manufacturing equipment that worked at a lower integration density might not work at a higher integration density. For example, at relatively low integration densities it was possible to sequentially process the wafers in conventional cluster equipment having a plurality of vacuum chambers for wafer processing. However, at relatively high integration densities the movement of the wafer can result in poor quality due to misalignment and contamination. In order to overcome this, new equipment is being developed so that a wafer is processed individually without being moved if possible. Such equipment allows a high degree of control over process parameters such as temperature distribution, pressure regulation, and contamination elimination.
In an attempt to design equipment to perform the reflow process above, an initial effort was made to combine equipment for the heating of the wafer with the sputter equipment. However, it proved difficult to uniformly heat the entire surface of the wafer to a temperature above or equal to 500.degree. C. and to attain a high degree of vacuum inside the sputter deposition chamber. A separate apparatus for the thermal treatment of the wafer was therefore developed.
In conventional apparatus for the thermal treatment of a thin film wafer, a heater assembly is provided inside a vacuum chamber. The heater assembly is located on an elevator mechanism that controls vertical movement of the heater assembly within the vacuum chamber. A clamp is provided inside the vacuum chamber above the heater assembly for clamping a wafer to the top of the heater assembly during thermal treatment. The conventional method of thermal treatment of a thin film wafer includes placing the wafer in the clamp in the vacuum chamber, raising the heater assembly with the elevator mechanism until the clamp presses the wafer against the top of the heater assembly, heating the wafer with the heater assembly, lowering the heater assembly with the elevator mechanism, an
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patent: 5421893 (1995-06-01), Perlov
Choi Chang-Hwan
Choi Won-Song
Kim Sek-Young
Kyung Hyun-Su
Lee Hueng-Jik
Leo Leonard R.
Novellus Systems Inc.
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