Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Reexamination Certificate
1998-01-29
2002-05-21
Weisberger, Rich (Department: 2164)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
C428S306600
Reexamination Certificate
active
06391437
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composite material and a manufacturing method thereof, a substrate processing apparatus and a preparing method thereof, a substrate mounting stage and a preparing method thereof, and a substrate processing method.
2. Description of the Related Art
A recent ultra LSI is required to integrate more than million of elements in a chip of several square mm. The dry etching technique for achieving fine processing of an ultra LSI and the chemical vapor deposition (CVD) technique, one of the thin film forming techniques, are required to achieve a further higher accuracy, and there are proposed process resulting from contrivances in gas chemistry, plasma source and wafer temperature control.
For the manufacture of a semiconductor apparatus, there are available many processes of applying a plasma treatment to various semiconductor boards, wafers or various thin films formed thereon, including plasma etching and plasma CVD. These carious semiconductor boards, wafers and various thin films formed thereon may sometimes be collectively referred to as substrates. In these plasma treatment, particularly in plasma etching or the like, treatment while holding a substrate at a low temperature within a range of from room temperature to below 0° C. is increasingly being adopted with a view to achieving a high processing accuracy. Importance of temperature control and temperature administration of substrate is now therefore being recognized.
Along with the progress made in multi-layer wiring technology in the area of semiconductor apparatus, there is a demand for using copper (Cu) as a material for wiring for the purpose of reducing wiring resistance or improving resistance to electro-migration, and technical development efforts are made to appropriately dry-etch a wiring material composing copper. There is another demand for adopting high-density plasma CVD in gap filling technology. As a result, not only the processes for plasma treatment at room temperature or at a lower temperature, but also processes of applying a plasma treatment while holding a substrate at a high temperature are having an increasing importance.
In such a plasma treatment at a high temperature, however, there occurs a considerable heat input from the plasma into the substrate as a result of ionic impact to the substrate in etching, or irradiation of a high-density plasma onto the substrate in filling CVD. Consequently, the substrate temperature may be raised by 40° C. to 100° C. as compared with that before generation of plasma. In a process of heating the substrate by a substrate mounting stage (such as a wafer stage) holding the substrate, to apply a plasma treatment at a high temperature, therefore, it is technically important to inhibit the influence of heat input from plasma into the substrate and control the substrate at a set temperature at a high accuracy.
Control of side wall and ceiling plate is also important as one of the process control parameters in various substrate processing apparatuses such as an etching unit and a CVD unit. Control of upper opposite electrode in an etching unit is also important. Reaction products produced in etching or CVD tend to accumulate on side wall, ceiling plate and upper opposite electrode (these may sometimes be referred to as “side wall and the like”) of these apparatuses. When the thus accumulating reaction products peel off from the side walls and the like of the apparatus, this may lead to a particle-level deterioration. Or, when a processor such as a polymer accumulates on the side wall and the like of an etching unit during etching of an oxide film, the side wall and the like serve as a scavenger of fluorocarbon polymer precursor, resulting in a variation in the ratio of carbon to fluorine in plasma, thus causing a problem of deterioration of etching property. It is therefore a common practice to adopt a technique for presenting accumulation by causing separation of the accumulating precursor through heating of the side wall and the like to a high temperature and irradiation onto the side wall and the like of the etching unit.
In the conventional art, temperature control of a substrate at high temperature is far from being sufficient. In the conventional art, occurrence of heating of the substrate to the aforesaid extent during processing is deemed to be natural, and temperature of the substrate mounting stage is previously set at a low temperature with heating of the substrate in view. Proceeding of the process in an anticipation of such heating results in many problems to be solved, including an extended period of processing time, a decrease in throughput, and deterioration of reproducibility and controllability of the process as a result of considerable variation of temperature.
A conceivable means for solving these problems is to mount an electrostatic chuck onto the substrate mounting stage to be heated to a high temperature. In order to mount an electrostatic chuck onto the substrate mounting stage, however, there is an important problem of how to connect the heated substrate mounting stage and a dielectric body composing the electrostatic chuck. This problem has prevented practical application of a substrate mounting stage having an electrostatic chuck mounted thereon. More specifically, in a substrate mounting stage based on high-temperature specifications, it is necessary to efficiently conduct heat to the substrate upon attracting the substrate and securing it onto the substrate mounting stage via the electrostatic shuck. The substrate mounting stage and the electrostatic chuck must therefore be connected with a good heat conductivity.
As a material for the substrate mounting stage in a substrate processing apparatus such as an etching unit, a CVD unit or a sputtering unit, it is common to adopt aluminum (Al) for a high heat conductivity and easy processing. Aluminum has a linear expansion coefficient of about 23×10
−6
/K. In general a ceramics material is used as a dielectric body composing the electrostatic chuck. When directly connecting the substrate mounting stage and the electrostatic chuck, therefore a damage such as cracks is caused in the ceramics material by heating and cooling of the substrate mounting stage as a result of the difference in linear expansion coefficient between the ceramics material composing the electrostatic chuck and aluminum composing the substrate mounting stage, resulting in a problem of breakage of the electrostatic chuck.
It is therefore a usual practice to fix the electrostatic chuck to the substrate mounting stage by means of screw-fitting or the like. In this structure, however, evacuation of the substrate processing apparatus causes vacuum isolation of the connection interface between the electrostatic chuck and the substrate mounting stage, resulting in a degraded efficiency of heat exchange between the substrate mounting stage and the substrate via the electrostatic chuck. As a result, the substrate suffers heat from plasma, leading to heating of the substrate to a temperature over the set temperature.
The side wall and the like of the substrate processing apparatus are usually made of stainless steel or aluminum. It is therefore a common practice, during etching, to form an Al
2
O
3
layer (alumite layer) on the surface of the side wall and the like made of aluminum with a view to preventing occurrence of metal contamination caused by the side wall and the like directly exposed to plasma or preventing corrosion of the side wall and the like by a halogen gas. When the side wall is made of stainless steel, and Al
2
O
3
reflector is provided near the side wall in the interior of the substrate processing apparatus.
When the substrate processing apparatus is heated in this state, with side wall and the like made of aluminum, cracks tend to be caused in an Al
2
O
3
layer formed on the surface of the side wall and the like, as a result of the difference in linear expansion coefficient between aluminum and Al
2
O
3
. When an Al
2
Hirano Shinsuke
Kadomura Shingo
Takatsu Kei
Kananen Ronald P.
Rader & Fishman & Grauer, PLLC
Sony Corporation
Weisberger Rich
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