Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
2000-12-22
2003-04-22
Mills, Gregory (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C118S733000, C118S728000, C118S715000
Reexamination Certificate
active
06551404
ABSTRACT:
The invention provides an apparatus for treating a wafer manufactured from semiconducting material, the apparatus comprising a first and a second housing part arranged for movement away from and towards each other, the two housing parts in a closed position, moved together, bounding a treatment chamber, at least one gas feed channel being provided in the first and/or second housing part which opens into the treatment chamber, the first and the second housing part around the treatment chamber being provided with a first and second boundary surface respectively, while in the closed position a gap is present between the first and the second boundary surface for discharging the gas fed into the treatment chamber in radially outward direction.
Such apparatus is known from Dutch patent application 103538 in applicant's name. The apparatus described is intended for performing a temperature treatment on a wafer manufactured from semiconducting material. The temperature treatment comprises, for instance, the steps of heating up a wafer within a short time, which wafer is subsequently held at a desired treatment temperature during a treatment period, for instance for annealing a doping. During this treatment period, a treatment gas may also be fed to the wafer, for instance for depositing material onto the wafer or etching material therefrom. The dimensions of the structures created on or in the wafer and the sharpness of the boundary surfaces between the structures and the bulk of the semiconducting material require a precision in the nanometer range. Greater variations may already inhibit or even impede the desired operation of the structures formed by the treatment.
Apparatuses for performing such temperature treatment on a wafer are already known in various other versions, for instance apparatuses where the wafer is irradiated by infrared lamps, or apparatuses where the wafer is placed directly on a temperature treatment surface, such as a heated plate. The drawback of these apparatuses is that the heat transfer between the wafer and the temperature treatment means of the apparatus is not uniform. This may lead to undesired effects. Thus, the non-uniform heat transfer may effect local overheating and/or underheating in the wafer, causing tensions in the wafer. Relaxation of these tensions results in dislocations and other defects in the crystalline semiconducting material of the wafer. These defects can degrade the electric properties of the material such that it no longer meets the desired specifications and becomes unusable for the intended application. In the second place, the heat transfer affects the course of the temperature-sensitive wafer treatment steps such as the deposition of material or the annealing of a doping introduced. Due to a non-uniform heat transfer, the temperature of the wafer to be treated is not uniform. Accordingly, during the treatment, the treatment period on some parts of the wafer is too short or too long, as a consequence of which the material is undertreated or overtreated respectively at those locations. Thus, at those locations of the wafer, this treatment does not lead to the desired electric and/or material properties, due to the non-uniform temperature of the wafer, so that in this way, too, the wafer may become unsuitable for further use.
The problems of a non-uniform heat transfer are avoided in the apparatus from Dutch patent 103538. To that end, the apparatus comprises a first and a second housing part, arranged for movement away from and towards each other. The two housing parts are brought to a specific treatment temperature. In fact, the temperature for the two housing parts may be different. The wafer to be treated is enclosed between the two housing parts in a treatment chamber. This involves the absence of mechanical contact between the two housing parts relative to each other. A gap between two boundary surfaces of the housing parts is sealed by a gas flowing radially outwards over the entire circumference and coming from the treatment chamber. The volume of the treatment chamber encloses the wafer very tightly, so that the heat transfer between the wafer and the two housing parts is effected substantially by means of a uniform heat conduction and only for a small part by radiation. As a consequence, the wafer rapidly takes over the temperature of the two housing parts. The housing parts have a very great heat capacity in relation to the wafer, so that the temperature of the housing parts hardly changes through the heat loss due to the heat transfer to the wafer. In the closed position of the two housing parts, moved towards each other, the treatment chamber should be closed off from the environment of the apparatus, such that no contaminants from the ambient air of the apparatus can reach the treatment chamber. Indeed, it is important that during the treatment in the treatment chamber, the wafer surface cannot contact such contaminants. During the treatment, this contaminant may adhere to the wafer surface or be incorporated into a layer deposited by the treatment, and accordingly render the wafer unusable for subsequent treatment steps and desired applications.
In the above-described apparatus, gas from the treatment chamber is used for sealing the gap between the two housing parts. Such contactless seal is preferred to a mechanical seal, which involves a contact surface between the two housing parts. After all, a mechanical seal must typically be of complex design to establish a proper closure of the treatment chamber. In that case, for instance an O-ring should be used, which is compressed in the contact surface when the housing parts are moved towards each other. In addition, such seal is subject to wear caused by the mechanical contact at the contact surface. Due to this wear, the quality of the seal between the two housing parts deteriorates upon repeated use. Moreover, due to the wear, particles are released from the housing parts. These particles may end up in the treatment chamber and accordingly contaminate the wafer surface. Such mechanical seal becomes additionally complicated if the housing parts are each brought to a treatment temperature for the treatment. Expansion of the hot housing parts may cause gaps in the contact surface, whereby the seal is broken. Moreover, the proper sealing of the hot housing parts is cumbersome when an O-ring is used.
In practice, the contactless closing of the two housing parts, with the gap between the housing parts being sealed by gas from the treatment chamber, is not sufficient to bring the contamination level in the treatment chamber to a desired low level. Indeed, via the gap, contamination from the environment may diffuse in the treatment chamber. A second drawback of the described sealing of the gap between the two housing parts is that a treatment gas to be used in the treatment space flows away to the environment of the apparatus via the gap. Many gases that serve for performing a wafer treatment are toxic and/or highly flammable upon contact with air, for instance silane, disilane and phosphine. In that case, it is important to avoid possible contact of this treatment gas with the ambient air.
The object of the present invention is to provide a solution to these problems. According to the invention, an apparatus of the type described in the preamble is characterized in that in at least one of the two boundary surfaces, there is provided a first groove connected to gas discharge means, while in at least one of the two boundary surfaces, there is provided a second groove connected to gas feed means, both the first and the second groove extending substantially along the circumference of the treatment chamber, the first groove being located radially within the second groove, and, in use, the pressure created by the gas feed means being such that from the second groove, gas flows both in radial inward and in radial outward direction in the gap between the first and the second boundary surface.
In use, a wafer is introduced into the treatment chamber between the two housing part
de Ridder Christianus Gerardus M.
Kuznetsov Vladimir Ivanovich
Snijders Gert-Jan
Terhorst Herbert
ASM International N.V.
Kackar Ram N
Mills Gregory
Weingarten Schurgin, Gagnebin & Lebovici LLP
LandOfFree
Apparatus for treating a wafer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for treating a wafer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for treating a wafer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3091802