Patent Application
20230253189
The present disclosure relates generally to systems, apparatus, and methods for seal venting in substrate processing chambers, and more particularly to the venting of barrier and vacuum seal arrangements therein.
Conventional vacuum seal arrangements in substrate processing chambers may suffer from so-called “virtual leaks”. A virtual leak can occur when internally trapped air appears to “leak” towards a vacuum source or chamber, as opposed to being derived from an external source of air that enters through a “real” hole or leak in the chamber somewhere. It will be appreciated that, whether virtual or not, a leak can impair the effectiveness of a vacuum seal. In more extreme cases, a virtual leak can defeat the purpose of a vacuum system, which is to achieve vacuum and prevent the intrusion of atmospheric gas into the process volume.
In single vacuum seal arrangements, air can become trapped on a bottom vacuum-side area (or toe) of the seal gland (or groove) in which the vacuum seal sits. In a double-seal arrangement, air can become trapped in both toes of the barrier-seal gland, the inner toe of the vacuum-seal gland, and in the space between the two seals. The trapped air can give rise to virtual leaks.
The background description provided herein is to generally present the context of the disclosure. It should be noted that the information described in this section is presented to provide the skilled artisan some context for the following disclosed subject matter and should not be considered as admitted prior art. More specifically, work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
The present disclosure relates generally to systems, apparatus, and methods for seal venting in substrate processing chambers, and more particularly to the venting of double seal arrangements therein. In some aspects, the present disclosure relates to techniques for venting certain vacuum-seal interfaces to reduce or prevent the occurrence of virtual leaks. In some examples, these techniques may be applied at component interfaces at which a separate chemically-resistant seal is used to shield a primary vacuum seal from process chemistry such as aggressive plasma gases and the like. At the top of a vacuum chamber, for example, an example interface may include two concentric O-ring face seals, the inner seal presenting a barrier to the process chemistry and the outer being the vacuum seal. The purpose of this double-seal arrangement is to enable the use of more cost effective or higher performing vacuum seals by decoupling the function of chemical resistance from the function of providing a vacuum seal.
Oxygen radicals are an example of process chemistry components that can be highly damaging to vacuum seals. One aspect of this disclosure is to provide a venting arrangement which creates such a venting passage that process chemistry (for example, the oxygen radicals) are unable to travel backstream (against the direction of applied vacuum) to the vacuum seal. The more collisions the radicals undergo, the more likely they are to recombine. In some examples, the number of collisions through a venting pathway path is proportional to the cross-sectional size, length, and tortuousness of the path. In some examples, one or more venting pathways are provided to establish a venting passageway that is sufficiently constrictive, long and tortuous that the probability of radicals reaching the vacuum seal before recombination becomes exceedingly low.
In some examples, a double seal arrangement for a substrate processing chamber is provided. An example double seal arrangement comprises a radially inner barrier seal disposed within a barrier seal gland, the barrier seal gland including an inner toe and an outer toe; a radially outer vacuum seal disposed within a vacuum seal gland; the vacuum seal gland including at least an inner toe; a first venting pathway between the inner toe of the vacuum seal gland and the outer toe of the barrier seal gland; a second venting pathway between the outer toe of the barrier seal gland and the inner toe of the barrier seal gland; a third venting pathway in communication at least with the inner toe of the barrier seal gland; and a vacuum source connected to at least one of the first, second, and third venting pathways.
In some examples, the second venting pathway includes a cross channel passing underneath the barrier seal.
In some examples, the first and second vent pathways include or are defined by a common cross channel extending between the vacuum seal gland and the barrier seal gland, the cross channel passing underneath a lower surface of the barrier seal at a first circumferential location of the barrier seal gland.
In some examples, a dimension of the cross channel prevents closure thereof by the harrier seal when the double seal arrangement is under vacuum.
In some examples, the cross channel includes a recess permitting access by a machining tool into the barrier seal gland during formation of the cross channel.
In some examples, the third venting pathway includes or is defined by a venting port provided at a second circumferential location of the harrier seal gland.
In some examples, the first and second venting pathways are provided at a common location, and the third venting pathway is provided at a separate location.
In some examples, the second and third venting pathways are provided at a common location, and the first venting pathway is provided at a separate location.
In some examples, the first, second and third venting pathways are each provided at a separate location.
In some examples, the first and second venting pathways are provided at respective separate locations on the respective barrier and vacuum seal glands.
In some examples, the third venting pathway is provided at a respective separate location with respect to the first and second venting pathways.
In some examples, the vacuum source includes or is generated by the processing chamber.
In some examples, the vacuum source includes an exhaust line of the processing chamber.
In some examples, the vacuum source includes an external vacuum source.
In some examples, the double seal arrangement further comprises a vacuum retarding means disposed in any one or more of the first, second, and third venting pathways.
In some examples, the vacuum retarding means includes a thread screw or tortuous path.
In some examples, a wall of the barrier seal gland or the vacuum seal gland includes an anodized aluminum material.
In some examples, an apparatus for providing a double seal arrangement for a substrate processing chamber is provided. An example apparatus comprises a radially inner barrier seal gland for receiving a barrier seal therein, the barrier seal gland including an inner toe and an outer toe; a radially outer vacuum seal gland for receiving a vacuum seal therein, the vacuum seal gland including at least an inner toe; a first venting pathway between the inner toe of the vacuum seal gland and the outer toe of the harrier seal gland; a second venting pathway between the outer toe of the barrier seal gland and the inner toe of the barrier seal gland; and a third venting pathway between the inner toe of the barrier seal gland and a vacuum source.
In some examples, the apparatus is defined by a single component.
In some examples, the apparatus is defined by multiple components.
In some examples, the apparatus further comprises a barrier seal and a vacuum seal.
In some examples, a processing chamber is proved. An example chamber comprises a double seal arrangement, the double seal arrangement comprising: a radially inner barrier seal disposed within a barrier seal gland, the barrier seal gland including an inner toe and an outer toe; a radially outer vacuum seal disposed within a vacuum seal gland, the vacuum seal gland including at least an inner toe; a first venting pathway between the inner toe of the vacuum seal gland and the outer toe of the barrier seal gland; a second venting pathway between the outer toe of the barrier seal gland and the inner toe of the barrier seal gland, a third venting pathway in communication at least with the inner toe of the barrier seal gland; and a vacuum source connected to at least one of the first, second, and third venting pathways.
Some embodiments are illustrated by way of example and not limitation in the views of the accompanying drawings.
The description that follows includes systems, arrangements, methods, techniques, and computing machine program products that embody illustrative embodiments of the present disclosure. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of example embodiments. It will be evident, however, to one skilled in the art that the present disclosure may be practiced without these specific details.
A portion of the disclosure of this patent document may contain material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever. The following notice applies to any data as described below and in the drawings that form a part of this document: Copyright Lam Research Corporation, 2020, All Rights Reserved.
An upper electrode 108 is located above the wafer 104. The upper electrode 108 is grounded.
An electrical insulator ring 110 insulates the upper electrode 108 from the processing chamber 102. Confinement rings 116 may be placed between the upper electrode 108 and a bottom electrode, such as the chuck 103 in
When RF power is supplied to chuck 103 from the dual-frequency power source 106, equipotential field lines are set up over wafer 104. The equipotential field lines are the electric field lines across the plasma sheath that is between wafer 104 and the plasma 112. During plasma processing, the positive ions accelerate across the equipotential field lines to impinge on the surface of wafer 104, thereby providing the desired etch effect, such as improving etch directionality. Due to the geometry of the upper electrode 108 and the chuck 103, the field lines may not be uniform across the wafer surface and may vary significantly at the edge of the wafer 104. Accordingly, a focus ring 120 is typically provided to improve process uniformity across the entire wafer surface. With reference to
An electrically conductive shield 122 substantially encircles the focus ring 120. The electrically conductive shield 122 is configured to be substantially grounded within the plasma processing chamber 100. The conductive shield 122 prevents the presence of unwanted equipotential field lines outside of focus ring 120. In relation to the chamber source gas supplied via the mixed gas line 114, it has been found that the gas transport characteristics within the plasma reactor and upstream of it can be the most sensitive variables contributing to etch or deposition non-uniformities.
As mentioned above, conventional vacuum seal arrangements in substrate processing chambers may suffer from so-called “virtual leaks”. A virtual leak can occur when internally trapped air appears to “leak” towards a vacuum source or chamber, as opposed to being derived from an external source of air that enters through a “real” hole or leak in the chamber somewhere. It will be appreciated that, whether virtual or not, a leak can negatively affect, if not completely destroy, the effectiveness of a vacuum seal.
In the illustrated example, a vented threaded screw 204 is provided. The vented threaded screw 204 includes a center bore 210 or vent that spans the length of the threaded screw 204 from head 206 to shank 212. The trapped gases and air can escape through the bore 210 at 214.
In some examples, the purpose of the double seal arrangement is to enable the use of more cost effective or higher performing vacuum seals by relieving them of the burden of requiring one seal that functions as bath a chemical barrier as well as a vacuum seal. In other words, the function of providing chemical resistance is decoupled from the function of providing a vacuum seal. As discussed above, double seal arrangements may result in the capture of a non-negligible volume of trapped air at the bottom radii of the seal glands (also referred to herein as “toes”) and in areas between the two seals. The term “toe” is not intended to be limiting to any particular shape necessarily. It is intended to include within its ambit a curved toe having an arcuate outline of the type defined by a dovetail gland for example, as well as a rectangular toe such as a square corner defined by a rectangular groove, for example. Other toe shapes are possible, and may include obtuse or acute corners, for example. In any event, air trapped within a toe or other volume is sought to be vented to prevent virtual leaks. One challenge therein is that the provision of direct-venting features would expose the vacuum seal to the chemistry, defeating the purpose of the barrier seal.
Undesired air can become trapped in the inner toe 406 and outer toe 408 of the barrier seal gland 402, and in the thin space 414, and also in at least the inner toe 410 of the vacuum seal gland 404. Unless vented, this trapped air can cause virtual leaks and cause at least some of the issues discussed herein. To this end, some examples herein provide a double seal arrangement that includes a first venting pathway between the inner toe of the vacuum seal gland and the outer toe of the barrier seal gland; a second venting pathway between the outer toe of the barrier seal gland and the inner toe of the harrier seal gland; and a third venting pathway between the inner toe of the barrier seal gland and a vacuum source. As will be explained more fully below, in some examples the venting pathways are provided at different locations around the periphery of the barrier seal gland 402 and the vacuum seal gland 404 to provide and define a constricted, long and tortuous venting passage for the trapped air that significantly impedes the passage of harmful radicals in the opposite direction.
In this regard, an expanded sectional view of the processing chamber 102 is shown in
In the illustrated example, the first and second venting pathways are coincident and defined by a common cross channel 602 at the Location A. In other examples, the first and second venting pathways may not be coincident or may be separately provided at different locations. The illustrated example cross channel 602 passes underneath the barrier seal 304 in use and includes a hollow recess 608 at an inner end thereof allowing, or created by, passage of a machining tool into the barrier seal gland 402 during formation of the cross channel 602. In some examples, the hollow recess 608 enhances access by vented air to the inner toe 406 at Location A. From that location, the vented air can travel around the circumference of the inner toe 406 in either direction to Location B. A third venting pathway (or escape) provided at Location B is described further below.
In some examples, a dimension of the cross channel 602 prevents closure thereof by the barrier seal 304 when the double seal arrangement is under vacuum, i.e., when the barrier seal 304 is compressed. In other words, a depth (for example) of the cross channel 602 is selected in light of a known compressibility of the barrier seal 304 such that a compressed barrier seal 304 is not able to deform downwardly to fill the cross channel 602.
A gap 610 or notch provided in the center wall 612 between the barrier seal gland 402 and the vacuum seal gland 404 allows the enclosed. space 414 access to the cross channel 602 and the first or second venting pathways. The enclosed space 414 can be vented, accordingly. Thus, so far, an example venting passage is created by and includes the first and second pathways defined by the first portion 604 and second portion 606 of the cross channel 602 and the internal volume of the inner toe 406 arounds the semicircular periphery of the barrier seal gland 402 where the barrier seal gland 402 reaches Location B. The enclosed space 414 is provided access to that venting passageway, or parts of it along the way. Other numbers and/or configurations of venting passages and pathways are possible.
Reference is now made to
In some examples, the vacuum source includes or is generated by the processing chamber 102, as described above. In some examples, a venting pathway or passageway is connected to or includes an exhaust line 118 of the processing chamber 102 . In some examples, a venting pathway or passageway is connected to or includes an external vacuum source, such as a vacuum pump. As mentioned above, other numbers and/or configurations of venting passages and pathways are possible. In this regard, a venting pathway or passageway may include vacuum retarding means or obstructions that add complexity, length, or constriction to the pathway or passageway. An example venting passageway may include a tubular venting pathway in which a vacuum retarding means includes a threaded screw. A space between the threads of the screw and the walls of the tubular pathway serve to add a spiral portion to the venting pathway or passageway. Other configurations are possible. In some examples, a second vacuum source is connected directly to the first or second venting pathways, in addition to or instead of the vacuum source being connected to the third venting passageway. In view of the aggressive nature of the processing chemistry being managed by the present examples, a wall of the barrier seal gland 402 and the vacuum seal gland 404 may include an anodized aluminum material. The profiles of these features may be smoothly rounded to minimize the creation of corrosion or stress points.
Thus, in some examples, a double seal arrangement is provided which creates a constrictive, long and tortuous venting passage in which process chemistry is unable to travel (or is significantly impeded from traveling) backstream to the vacuum seal 306. As described herein, one or more venting pathways are provided to establish a venting passage that is sufficiently constrictive, long and tortuous that the probability of radicals reaching the vacuum seal before recombination becomes exceedingly low. In the illustrated examples, a full venting passageway, viewed overall, may include first and second pathways defined by the first portion 604 and second portion 606 of the cross channel 602, and the internal volume of the inner toe 406 around the semicircular periphery of the barrier seal gland 402 at the point that the barrier seal gland 402 reaches Location B. At Location B, the venting passageway proceeds to include the third venting pathway defined by the venting port 802 and thence to the processing chamber 102. Further or other venting pathways are possible.
Although examples have been described with reference to specific example embodiments or methods, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader scope of the embodiments. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. The accompanying drawings that form a part hereof, show by way of illustration, and not of limitation, specific embodiments in which the subject matter may be practiced. The embodiments illustrated are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed herein. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled.
Such embodiments of the inventive subject matter may be referred to herein, individually and/or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept if more than one is in fact disclosed. Thus, although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description.
This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 63/051,253, filed on Jul. 13, 2020, which is incorporated by reference herein in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/039981 | 6/30/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63051253 | Jul 2020 | US |
