Patent Application
20110291022
The present invention relates generally to ion implantation systems, and more specifically to preventing condensation from forming on a workpiece in an ion implantation system.
Electrostatic clamps or chucks (ESCs) are often utilized in the semiconductor industry for clamping workpieces or substrates during plasma-based or vacuum-based semiconductor processes such as ion implantation, etching, chemical vapor deposition (CVD), etc. Clamping capabilities of the ESCs, as well as workpiece temperature control, have proven to be quite valuable in processing semiconductor substrates or wafers, such as silicon wafers. A typical ESC, for example, comprises a dielectric layer positioned over a conductive electrode, wherein the semiconductor wafer is placed on a surface of the ESC (e.g., the wafer is placed on a surface of the dielectric layer). During semiconductor processing (e.g., ion implantation), a clamping voltage is typically applied between the wafer and the electrode, wherein the wafer is clamped against the chuck surface by electrostatic forces.
For certain ion implantation processes, cooling the workpiece via a cooling of the ESC is desirable. At colder temperatures, however, condensation can form on the workpiece, or even freezing of atmospheric water on the surface of the workpiece can occur, when the workpiece is transferred from the cold ESC in the process environment (e.g., a vacuum environment) to an external environment (e.g., higher pressure, temperature, and humidity). For example, after an implantation of ions into the workpiece, the workpiece is typically transferred into a load lock chamber, and the load lock chamber is subsequently is vented. When the load lock chamber is opened to remove the workpiece therefrom, the workpiece is typically exposed to ambient atmosphere (e.g., warm, “wet” air), wherein condensation can occur. The condensation can deposit particles on the workpiece, and/or leave residues on the workpiece that can have adverse effects on front side particles (e.g., on active areas), and can lead to defects and production losses.
Therefore, a need exists in the art for an apparatus, system, and method for mitigating condensation on a workpiece when transferred from a cold environment to a warmer environment.
The present invention overcomes the limitations of the prior art by providing a system, apparatus, and method for abating condensation on a workpiece in a chilled ion implantation system. Accordingly, the following presents a simplified summary of the disclosure in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is intended to neither identify key or critical elements of the invention nor delineate the scope of the invention. Its purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
In accordance with the present disclosure, an ion implantation system for implanting ions into a cold workpiece is provided. The ion implantation system, for example, comprises an ion implantation apparatus configured to provide a plurality of ions to a workpiece positioned in a process chamber. A sub-ambient temperature chuck, such as a cryogenically cooled electrostatic chuck, is configured to support the workpiece within the process chamber during an exposure of the workpiece to the plurality of ions. The cryogenic chuck is further configured to cool the workpiece to a processing temperature, wherein the process temperature is below a dew point of an external environment.
According to one aspect, a load lock chamber is operably coupled to the process chamber and configured to isolate a process environment associated with the process chamber from the external environment. The external environment, for example, is thus at an external temperature that is greater than the processing temperature. The load lock chamber further comprises a workpiece support configured to support the workpiece during a transfer of the workpiece between the process chamber and the external environment.
A light source configured to provide a predetermined wavelength or spectrum of electromagnetic radiation to the workpiece concurrent with the workpiece residing within the load lock chamber is further provided. According to the disclosure, the predetermined wavelength or range of wavelengths is associated with a maximum radiant energy absorption range of the workpiece, wherein the light source is configured to selectively heat the workpiece.
The above summary is merely intended to give a brief overview of some features of some embodiments of the present invention, and other embodiments may comprise additional and/or different features than the ones mentioned above. In particular, this summary is not to be construed to be limiting the scope of the present application. Thus, to the accomplishment of the foregoing and related ends, the invention comprises the features hereinafter described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.
The present disclosure is directed generally toward a system, apparatus, and method for abating condensation on a workpiece in an ion implantation system. Accordingly, the present invention will now be described with reference to the drawings, wherein like reference numerals may be used to refer to like elements throughout. It is to be understood that the description of these aspects are merely illustrative and that they should not be interpreted in a limiting sense. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be evident to one skilled in the art, however, that the present invention may be practiced without these specific details. Further, the scope of the invention is not intended to be limited by the embodiments or examples described hereinafter with reference to the accompanying drawings, but is intended to be only limited by the appended claims and equivalents thereof.
It is also noted that the drawings are provided to give an illustration of some aspects of embodiments of the present disclosure and therefore are to be regarded as schematic only. In particular, the elements shown in the drawings are not necessary to scale with each other, and the placement of various elements in the drawings is chosen to provide a clear understanding of the respective embodiment and is not to be construed as necessarily being a representation of the actual relative locations of the various components in implementations according to an embodiment of the invention. Furthermore, the features of the various embodiments and examples described herein may be combined with each other unless specifically noted otherwise.
It is also to be understood that in the following description, any direct connection or coupling between functional blocks, devices, components, circuit elements or other physical or functional units shown in the drawings or described herein could also be implemented by an indirect connection or coupling. Furthermore, it is to be appreciated that functional blocks or units shown in the drawings may be implemented as separate features or circuits in one embodiment, and may also or alternatively be fully or partially implemented in a common feature or circuit in another embodiment. For example, several functional blocks may be implemented as software running on a common processor, such as a signal processor. It is further to be understood that any connection which is described as being wire-based in the following specification may also be implemented as a wireless communication, unless noted to the contrary.
Referring now to the figures,
A load lock chamber 116 is operably coupled to the process chamber 106, wherein the load lock chamber is configured to isolate a process environment 118 (e.g., a substantially dry vacuum environment) associated with the process chamber from an external environment 120, and further provides for a transfer of workpieces 104 into and out of the process environment without compromising the vacuum or pressure quality within the process environment. The load lock chamber 116, for example, comprises a workpiece support 122 configured to support the workpiece 104 during a transfer of the workpiece between the process chamber 106 and the external environment 120.
The workpieces 104, for example, travel between a FOUP 124 (e.g., a unit configured to carry the workpieces in the external environment 120) and the load lock chamber 116. The external environment 124 in which the FOUP 124 carries workpieces is in an ambient atmosphere that can have a relatively high dew point, depending on various environment factors, such as weather conditions, room ventilation, season, etc.
The ion implantation apparatus 102 of the present disclosure is configured to implant the plurality of ions 108 into the workpiece 104 at a low process temperature (e.g., any temperature below a dew point temperature of the external environment 120). Condensation has a tendency to form on a workpiece 104, however, if the workpiece is transferred from the implantation system to the external environment 120 when the workpiece is cooler than an ambient dew point in the external environment. If the temperature of the workpiece 104 is below the freezing point of water, for example, the workpiece will further develop frost upon being exposed to ambient water in the air (e.g., humidity) of the external environment 120.
In accordance with one example, a sub-ambient temperature chuck 126 is provided, wherein the sub-ambient temperature chuck is configured to support the workpiece 104 within the process chamber 106 during an exposure of the workpiece to the plurality of ions 108. The sub-ambient temperature chuck 126, for example, comprises an electrostatic chuck 127 and is configured to cool or chill the workpiece 104 to a processing temperature below the ambient dew point (also called dew point temperature) of the external environment 120, such as approximately −40 degrees C. As such, the processing temperature is significantly lower than the external temperature of the external environment 120, and without warming of the workpiece 104 prior to exposure to the external environment, condensation may form thereon, thus potentially deleteriously affecting the workpiece.
Accordingly, in accordance with the present disclosure, a light source 128 is associated with the load lock chamber 116, wherein the light source is configured to provide one or more predetermined wavelengths (e.g., a singular wavelength, plurality of wavelengths, or a wavelength spectrum) of electromagnetic radiation 130 to the workpiece 104 concurrent with the workpiece residing within the load lock chamber. The predetermined wavelength or wavelength spectrum of the electromagnetic radiation 130, in accordance with the present disclosure, is associated with a maximum radiant energy absorption range of the workpiece 104, wherein the light source 128 is configured to selectively heat the workpiece within the load lock chamber 116 prior to being exposed to the external environment 120. The light source 128 is further powered by a controllable power source 131.
In accordance with the present disclosure, the light source 128 of
In accordance with another aspect, the load lock chamber 116 of
According to another example, a secondary monitoring device 156 is provided, wherein the secondary monitoring device is configured to measure at least the external temperature of the external environment 120. The secondary monitoring device 156, in another example, is further configured to measure relative humidity (RH) in the external environment 120. Accordingly, the controller 148 is configured to determine a temperature of the workpiece 104 at which condensation will not form on the workpiece when the workpiece is transferred from the load lock chamber 116 to the external environment 120, wherein the determination is made based, at least in part, on data from the workpiece temperature monitoring device 146 and secondary temperature monitoring device 156.
In accordance with yet another example, a gas and/or vacuum source 158 is provided in selective fluid communication with the load lock chamber 116, wherein the gas and/or vacuum source is configured to provide a dry gas and/or vacuum to the load lock chamber.
In accordance with another exemplary aspect of the invention,
The method 200 of
In act 210, a workpiece is transferred from a process environment to the load lock chamber. The workpiece, for example, is transferred from a sub-ambient temperature chuck, wherein the workpiece has undergone a cold ion implantation, and is at a process temperature or first predetermined temperature that is lower than the dew point of the environment. In act 215, the workpiece is exposed to the light source, therein warming the workpiece to a second predetermined temperature. The second predetermined temperature, for example, is greater than the dew point temperature of an external environment. In act 220, the workpiece is transferred from the load lock chamber to the external environment, wherein condensation is abated by raising the temperature of the workpiece via the light source.
According to one example, a temperature of the workpiece is measured concurrent with exposing the workpiece to the light source in act 215. Accordingly, the workpiece is transferred to the external environment from the load lock chamber in act 220 after measured temperature meets or exceeds the second predetermined temperature.
Although the invention has been shown and described with respect to a certain embodiment or embodiments, it should be noted that the above-described embodiments serve only as examples for implementations of some embodiments of the present invention, and the application of the present invention is not restricted to these embodiments. In particular regard to the various functions performed by the above described components (assemblies, devices, circuits, etc.), the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiments of the invention. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several embodiments, such feature may be combined with one or more other features of the other embodiments as may be desired and advantageous for any given or particular application. Accordingly, the present invention is not to be limited to the above-described embodiments, but is intended to be limited only by the appended claims and equivalents thereof.
This application claims priority to and the benefit of U.S. Provisional Application Ser. No. 61/349,547 which was filed May 28, 2010, entitled Active Dew Point Sensing and Load Lock Venting to Prevent Condensation on Workpieces, the entirety of which is hereby incorporated by reference as if fully set forth herein.
| Number | Date | Country | |
|---|---|---|---|
| 61349547 | May 2010 | US |
