Drying and gas or vapor contact with solids – Apparatus – Vacuum
Patent
1990-12-06
1993-01-12
Bennet, Henry A.
Drying and gas or vapor contact with solids
Apparatus
Vacuum
34233, 34239, F26B 1330
Patent
active
051778785
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an apparatus for treating a flat substrate more particularly a semiconductor wafer, under reduced pressure comprising a vacuum chamber provided with a substrate support having a body with heating and/or cooling means and a supporting surface at which a plurality of injection openings is present communicating with an injection space and a supplementary gas inlet, through which injection openings a gas can be supplied between the substrate and the supporting surface for forming a heat-exchanging gas cushion therebetween.
The invention also relates to a method of manufacturing electronic devices in which a flat substrate, more particularly a semiconductor wafer in the manufacture of integrated circuits, is treated under reduced pressure in an apparatus as mentioned before.
BACKGROUND OF THE INVENTION
The treatments necessary for the manufacture of semiconductor integrated circuits utilize for a large part processes of depositing or etching carried out in a treatment gas or of a mixture of several gases under reduced pressure. Besides the process of low-pressure chemical vapour deposition, known under the designation LPCVD, in which a chemical reaction is obtained merely due to the high temperature to which the substrate is brought, other processes more frequently give rise to an activation of the treatment gas by a plasma formed in the vacuum chamber, in which processes the substrate, in electrical connection with its support, forms one of the electrodes, while another electrode is disposed parallel to the substrate at a given distance therefrom.
Depending upon the type of process to be used, the power of the electrical field applied to the electrodes for producing the plasma can be greatly different, while the temperature at which the substrate must be kept can also vary within wide limits. As a result, in general a heat flow must be provided between the substrate and its support in one or the other direction, that is to say to that the substrate when the losses by radiation are preponderant, or to cool it when the power used in the plasma is high and exceeds the radiation losses.
Finally, annealing treatments at given temperatures in accordance with a very rapid cycle (less than one minute) are also susceptible to being carried out in a vacuum chamber, in which a atmosphere of a neutral (or reducing) gas may be established under reduced pressure in a chamber, or in a high-vacuum. Such rapid annealing treatments are used inter alia to obtain micro-alloys between materials of different kinds, which are initially superimposed.
It is well known that it is difficult to obtain a satisfactory heat exchange between a substrate and its support when the assembly is arranged in a chamber under reduced pressure. Now, this heat exchange plays an essential part in the control of the temperature to which the substrate must be brought during the treatment to obtain a temperature homogeneity of the substrate as satisfactory as possible and to obtain, if necessary, a speed of temperature increase of the substrate and a speed of cooling as high as possible. The processes of treatment in a vacuum or in a partial vacuum are in fact mostly very sensitive to the temperature so that a poor control of the temperature of the substrate would involve an unacceptable dispersion of the results both between one operation and the other and as a function of the position on the surface of the same substrate.
In order to meet these difficulties, it has already been proposed to inject between the back surface of the substrate and the supporting surface of the support a gas thus forming a heat-exchanging gas cushion therebetween facilitating the heat exchange between the substrate and the supporting surface of the support, whose temperature can be regulated in an active manner.
An apparatus utilizing such a technique and corresponding to the definition given in the introductory paragraph is known from the document German application No. DE-A-36 33 386.
In the known apparatus the gas injected under the back surface o
REFERENCES:
patent: 3717439 (1973-02-01), Sakai
patent: 4565601 (1986-01-01), Kakehi
Bennet Henry A.
Miller Paul R.
U.S. Philips Corporation
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