Patent Application
20230207377
The field relates to a semiconductor processing device with wafer edge purging. For example, the field is generally related to a susceptor assembly that includes one or more channels to deliver a purge gas to an edge of a semiconductor wafer. Additionally or alternatively, the field relates to a showerhead assembly configured to supply a reactant gas to a front surface of the semiconductor wafer and a purge gas to the edge of the wafer.
During semiconductor processing, various vaporized precursor(s) are fed into a reaction chamber. In some applications, suitable source chemicals that are in solid or liquid phase at ambient pressure and temperature are provided in a source vessel. These solid or liquid source substances may be heated to sublimation or evaporation to produce a vaporized precursor for a reaction process, such as vapor deposition. Chemical Vapor Deposition (CVD) may call for the supply of continuous streams of precursor vapor to the reaction chamber, while Atomic Layer Deposition (ALD), pulsed CVD and hybrids thereof may call for continuous streams or pulsed supply to the reaction chamber, depending on the desired configuration.
In view of the above-mentioned situation, one object of one or more aspects of the disclosed embodiments is to provide a susceptor assembly to eliminate any backside wafer deposition.
In some embodiments, the susceptor assembly may include a wafer support configured to support a wafer, which may comprise a wafer support body configured to support the wafer on a support surface of the wafer support body. The wafer support may further comprise a purge channel extending laterally from an inner portion of the wafer support body to an outer portion of the wafer support body and a first plenum channels disposed at the outer portion of the wafer support being in fluid communication with the purge channel, and an outlet to deliver purge gas to an edge of the wafer, said outlet is fluidly communicated with the first plenum channel. The susceptor assembly may further comprise a purge gas supply hole on a surface opposite to the support surface of the wafer support body, said purge gas supply hole being in fluid communication with the purge channel, and a plurality of first purge holes fluidly communicated with the first plenum channel and the purge channel. The wafer support may comprise a cylindrical body and the outlet may be concentric with the wafer support and a plurality of the purge channels extending symmetrically from the inner portion.
In some embodiments, the wafer support body may comprise a recess portion configured to support the wafer, and the outlet may be formed on the recess portion and in fluid communication with the first plenum. The wafer support may further comprise an annular ridge on the recess portion, and said annular ridge may be concentric with a circumference of the wafer to be treated. Said annular ridge may be configured to be disposed within a perimeter of the wafer to be treated. The outlet may be formed along an outermost periphery of the annular ridge. A depth of the recess portion at an outer diameter side of the annular ridge may be deeper than an inner diameter side of the annular ridge and progressively decreased toward a perimeter of the cylindrical body.
In some embodiments, a second plenum channel may be formed at the outer portion of the wafer support which is positioned vertically apart from the first plenum in a thickness direction of the wafer support body. The wafer support may further comprise a plurality of second purge holes providing fluidly communicated with the first plenum channel and the second plenum channel. The plurality of first purge holes may be fluidly communicated with second plenum channel and respective purge channels. A number of the second purge holes may be greater than a number of the first purge holes.
In some embodiments, the susceptor assembly may be coupled to a shaft which comprises a vacuum tube and an inner gas supply tube, and a plurality of purge gas supply holes may be configured to be fluidly connected to an inert gas source through the inner gas supply tube. The wafer support body may comprise a Nickel-Chromium Molybdenum alloy. The susceptor assembly may further comprise a vacuum chuck groove disposed at the inner portion of the wafer support and a vacuum chuck hole in fluid communication with a plurality of vacuum chuck grooves through the vacuum tube. The vacuum chuck hole may be configured to be in fluid connection with a vacuum source. The wafer support body may comprise Hastelloy® C22® material.
In some embodiments, a susceptor assembly may comprise a wafer support configured to support a wafer, which may comprise a wafer support body configured to support a wafer to be treated, a plurality of purge channels extending laterally from an inner portion of the wafer support body to an outer portion of the wafer support body, a first plenum channel disposed at the outer portion of the wafer support, and a second plenum channel positioned vertically apart from the first plenum. The susceptor assembly may further comprise a second plenum channel which is in fluid communication with the plurality of purge channels by way of a plurality of first purge holes and in fluid communication with the first plenum by way of a plurality of second purge holes and an outlet in fluid communication with the first plenum to deliver purge gas to an edge of the wafer. The wafer support body may comprise a recess portion configured to support the wafer, and the outlet may be formed on the recess portion and in fluid communication with the first plenum. The susceptor assembly may be coupled to a shaft which comprises a purge gas supply tube connected to an inert gas source.
In some embodiments, a susceptor assembly may comprise a cap and a heater pedestal, wherein the cap comprises the wafer support and the surface opposite to the recess portion is configured to be disposed on a heater pedestal. The wafer support body may comprise a recess portion configured to support the wafer, and the outlet is formed on the recess portion and in fluid communication with the first plenum. The heater pedestal may be coupled to a shaft which comprises a vacuum tube and an inner gas supply tube. The heater pedestal may comprise one or more vacuum holes configured to couple to the respective vacuum chuck holes, and one or more purge gas holes configured to couple to the respective purge gas supply holes. The one or more vacuum holes may be configured to be fluidly connected to a vacuum source through the vacuum tube, and the one or more purge holes may be configured to be fluidly connected to an inner gas source through the inner gas supply tube. The susceptor assembly may comprises three temperature control zones which allows better tuning of the outer portion and improve within wafer (WiW)NU %.
Another object of one or more aspects of the present invention is to provide a showerhead assembly for treating a wafer which prevents back diffusion so that backside wafer deposition is eliminated.
In some embodiments, the showerhead assembly may comprise a showerhead plenum, a plurality of openings in fluid communication with the showerhead plenum, and an edge purge injection holes configured to be disposed outside of a perimeter of the wafer to be treated and in fluid communication with a purge gas source. The plurality of openings may be configured to convey vaporized precursor(s) from the showerhead plenum and onto a wafer support configured to support the wafer and the edge purge injection hole may be arranged to direct a purge gas to prevent back-diffusion of gases to the wafer.
In some embodiments, the showerhead assembly may include the plurality of edge purge injection holes are directed circumferentially outwardly relative to the wafer to be treated. The showerhead assembly may further comprise a plurality of edge purge injection holes. The edge purge injection hole may not be in fluid communication with the showerhead plenum.
In some embodiments, a showerhead assembly, for treating a wafer, may comprise a showerhead plenum, a plurality of openings in fluid communication with the showerhead plenum, the plurality of openings configured to convey a vaporized precursor from the showerhead plenum and onto the wafer; and an edge purge injection hole configured to be disposed outside of a perimeter of the wafer to be treated and in fluid communication with a purge gas source. The purge gas may be directed circumferentially outwardly relative to the wafer support. The showerhead assembly may further comprise a plurality of edge purge injection holes.
In some embodiments, a showerhead assembly, for treating a wafer, may comprise a showerhead plenum, a substrate support configured to support the wafer, and a plurality of openings in fluid communication with the showerhead plenum and disposed over the substrate support. The plurality of openings may be configured to convey a vaporized precursor from the showerhead plenum and onto the wafer. A gap between the showerhead assembly and the substrate support may be narrower at an outer edge of the showerhead assembly than over the substrate support. The gap may be at least partially defined by a recess portion and a depth of the recess portion is progressively varied (e.g., decreased) toward an outer edge of the showerhead.
Yet, another object of one or more aspects of the present invention is to provide a method for purging an edge of wafer.
In some embodiments, the method may include placing a wafer to be treated on a support surface of a wafer support, delivering a purge gas laterally along a purge gas channel of the wafer support to an outer portion of the wafer support, and directing the purge gas upwardly from the purge channel through a first plenum and through an outlet to an outer edge of the wafer. The method may further comprise holding the wafer onto the wafer support by applying vacuumed to a vacuum chuck and applying precursor gas to the wafer. The purge gas may be directed from the purge channel through the first plenum, a second plenum and an outlet.
In some embodiments, the method may comprise placing a wafer to be treated on a substrate support, providing a precursor gas to the wafer from a showerhead, and delivering a purge gas through an edge purge injection hole outside of a perimeter of the wafer to be treated. The purge gas may be directed circumferentially outwardly.
In some embodiments, the method may comprise placing a wafer to be treated on a substrate support, providing a precursor gas to the wafer from a showerhead, and directing the precursor gas laterally relative to the showerhead through a gap between the showerhead and the substrate support, the gap narrower at an outer edge of the showerhead than over the wafer.
The foregoing and other objectives and advantages will appear from the description to follow. In the description reference is made to the accompanying drawing, which forms a part hereof, and in which is shown by way of illustration specific embodiments in which the disclosed embodiments may be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the disclosed embodiments, and it is to be understood that other embodiment may be utilized and the structural changes may be made without departing from the scope of the disclosed embodiments. The accompanying drawings, therefore, are submitted merely as showing the preferred exemplification of the disclosed embodiments. Accordingly, the following detail description is not to be taken in a limiting sense, and the scope of the disclosed embodiments is best defined by the appended claims.
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. However, it will be obvious to one with ordinary skill in the art that the embodiments may be practiced without these specific details. In other instances, well known methods, procedures, components, and mechanism have not been described in detail as not to unnecessarily obscure aspects of the present invention.
In general, in these apparatuses used in formation of a film in semiconductor manufacturing steps, a susceptor and heat source can be arranged under a wafer, and a rear-surface heating method which can supply a uniform process gas from the top is used, which may create film growth on a backside of the wafer. During deposition processes, a high thickness on a wafer edge is observed for some processes due to backside deposition caused by back diffusion of precursors from a dead volume behind the wafer. Purging the wafer edge from a backside of the wafer will eliminate deposition on the backside of the wafer and also allow better tuning of wafer edge thickness. In order to enable backside purge and secure the wafer to the susceptor during processing, a vacuum chucking susceptor or an electrostatic chucking susceptor can be provided to hold the wafer while purging the backside can be used. The susceptor can also comprise or serve as a heater to heat the wafer during processing.
For example, a vacuum chuck aluminum nitride (AlN) susceptor heater can be used, however, a dedicated edge purge channel may not be available with the AlN heater due to poor machinability and durability. A flow from the lower chamber caused by the pressure difference between upper and lower chamber can be utilized to prevent backside deposition. However, it is difficult to control the flow and only control a limited flow rate range can be provided using pressure differentials. Further, as the geometry of the AlN heater is a ceramic, the AlN heater cannot have an edge bias of greater than 10° C. without breakage and may have only a 2-zone temperature control. For certain processes, that causes degrading an emissivity and thickness non-uniformity (NU %), which cannot be recovered by outer zone susceptor temperature tuning. Thus, there is a need in the art for susceptor assembly that provides an enhancement of tuning of wafer edge thickness.
The wafer support 10 may further comprise one or more first plenum channels 15 formed at the outer portion 14 of the wafer support 10. As indicated in
As shown in
The susceptor assembly 1 may be coupled to a shaft 31 which comprises a vacuum tube 33 and one or more inner gas supply tubes 32. The purge gas supply holes 18 may be configured to fluidly connect to the inert gas source 24 through the inner gas supply tube 32. The inert gas can be delivered from the inert gas source vertically upward through the supply tube 32 within the shaft and to the purge channels 12 through the supply holes 18. The inert gas may be delivered laterally outward to the plurality of primary purge holes 19 through the purge channels 12. The inert gas may be supplied to the first plenum 15 through the plurality of primary purge holes 19 and delivered to the second plenum channel 16 through the plurality of secondary purge holes 20 for the multiple plenum embodiment of
The susceptor assembly 1 may further comprise one or a plurality of vacuum chuck grooves 22 disposed at the inner portion 13 of the wafer support 10. The plurality of vacuum chuck grooves 22 may be in fluid communication with at least two vacuum chuck holes 23 through vacuum tubes 32 in a shaft 31 so that the vacuum chuck grooves 22 apply suction to the wafer W to be treated. In other embodiments, the susceptor assembly 1 can comprise an electrostatic chuck to support the wafer W.
The wafer support 10 may comprise a Nickel-Chromium Molybdenum alloy having a good machinability, durability. The disclosed alloy can have a higher ramp rate per min compared to other materials (such as aluminum nitride (AlN)) for the susceptor heater, which allows a narrow slit design for outlet 17 to deliver a uniform flow to the edge of the wafer and a plurality of (e.g., three) temperature control zones, namely, the inner portion, outer portion and a portion therebetween, which allows better tuning of the outer portion and improve within wafer (WiW) non-uniformity (NU %). In some embodiments, the Nickel-Chromium Molybdenum alloy may comprise Hastelloy® C22® material, sold by Central States Industrial of Springfield, Mo.
As shown in
The present disclosure also relates to methods for purging an edge of wafer using the susceptor assembly or showerhead assembly described herein, such as semiconductor wafers, in gas-phase reactors, such as chemical vapor deposition (CVD) reactors, including plasma-enhanced CVD (PECVD) reactors, low-pressure CVD (LPCVD) reactors, atomic layer deposition (ALD) reactors, and the like. By way of examples, the assemblies and components described herein can be used in showerhead-type gas-phase reactor systems, in which gasses generally flow in a downward direction from a showerhead and toward a substrate.
For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.
Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment.
Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.
Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount.
The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted fairly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.
This application is a nonprovisional of, and claims priority to and the benefit of, U.S. Provisional Patent Application No. 63/266,099, filed Dec. 28, 2021 and entitled “SEMICONDUCTOR PROCESSING DEVICE WITH WAFER EDGE PURGING,” which is hereby incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 63266099 | Dec 2021 | US |
