Embodiments of the present disclosure generally relate to semiconductor processing equipment.
A semiconductor substrate is handled on the substrate edge and backside numerous times during the manufacturing process, for example during metal deposition, chemical vapor deposition, or etching processes. Such handling can cause contaminants to adhere to the backside of the substrate and travel from chamber to chamber, substrate to substrate, front-opening unified pod (FOUP) to FOUP, or process tool to process tool along with the substrate. These contaminants can migrate to the front side of the substrate, resulting in yield loss. Alternatively, the contaminants can cause the substrate to not lay flat on a substrate support in a process tool. For example, in a lithography step, the contaminants can undesirably cause a substrate to lay unevenly atop a support stage in a lithography tool beyond a working depth of field of the stepper lens.
Typical solutions to the problem have been to remove the contaminants through an in-production-line cleaning tool using wet chemicals, backside scrubbing, attempts to limit particle formation, and/or frequent cleaning of process tools. However, these steps only mitigate the yield loss and are costly in terms of equipment and consumables. For example, use of wet chemicals requires wet chemistry handling and disposal, and possible undesired damage to the backside of the substrate.
As such, the inventors have provided improved methods and apparatus for cleaning particle contamination from a substrate.
Embodiments of methods and apparatus for cleaning contaminants from a substrate are disclosed herein. In some embodiments, a substrate cleaning apparatus includes: a substrate support to support a substrate along an edge of the substrate, wherein the substrate further includes a first side and an opposing second side having contaminants disposed on the second side; a showerhead disposed a first distance of about 1.5 mm to about 4.4 mm opposite the substrate support and facing the first side of the substrate; and one or more nozzles disposed a second distance of about 1 inch to about 2 inches beneath the substrate support to discharge a mixture of solid and gaseous carbon dioxide toward the contaminants on the second side of the substrate, and wherein the one or more nozzles have an angle of about 20 to about 40 degrees
In some embodiments, a method of cleaning contaminants from a substrate disposed atop a substrate support member is provided. In some embodiments, a method of cleaning contaminants from a substrate includes: (a) directing a mixture of solid and gaseous carbon dioxide from one or more nozzles to the second side of the substrate to remove one or more contaminants from the contaminated second side of the substrate, wherein the one or more nozzles are coupled to a moveable arm and disposed a distance of about 1 inch to about 2 inches beneath the substrate support, and wherein the one or more nozzles have an angle of about 20 to about 40 degrees; and (b) directing a flow of gas from a showerhead toward the first side of the substrate, wherein the showerhead is disposed a distance of about 1.5 mm to about 4.4 mm opposite the substrate support.
In some embodiments, a method of cleaning contaminants from a substrate disposed atop a substrate support, wherein the substrate has a first side, an opposing contaminated second side and an edge between the first side and the second side, the method includes: (a) directing a mixture of solid and gaseous carbon dioxide from one or more nozzles to the second side of the substrate to remove one or more contaminants from the contaminated second side of the substrate, wherein the one or more nozzles are coupled to a moveable arm and disposed a distance of about 1 inch to about 2 inches beneath the substrate support, and wherein the one or more nozzles have an angle of about 20 to about 40 degrees; (b) directing a flow of gas at a flow rate of about 300 slm to about 500 slm from a showerhead toward the first side of the substrate while directing the mixture of solid and gaseous carbon dioxide to the second side of the substrate, wherein the showerhead is disposed a distance of about 1.5 mm to about 4.4 mm opposite the substrate support; (c) rotating the substrate while directing the mixture of solid and gaseous carbon dioxide to the contaminated second side of the substrate; (d) actuating the arm to move from a center of the rotating substrate to an outer edge of the rotating substrate while dispensing the mixture; and (e) heating the showerhead to a temperature of about 120 degrees Celsius to about 150 degrees Celsius while directing the flow of gas from the showerhead toward the first side of the substrate.
Other and further embodiments of the present disclosure are described below.
Embodiments of the present disclosure, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the disclosure depicted in the appended drawings. However, the appended drawings illustrate only typical embodiments of the disclosure and are therefore not to be considered limiting of scope, for the disclosure may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Embodiments of the disclosure provide improved methods and apparatus for cleaning a substrate. Embodiments of the present disclosure may advantageously allow for the removal of contamination accumulated on a substrate during the manufacturing process, such as while handling the substrate between process steps and while chucking the substrate inside a process chamber, which can limit or prevent contaminants from reaching the front-side of a substrate and causing yield loss. Embodiments of the present disclosure may advantageously allow for the removal of the contamination without the potential damage to the substrate associated with contact cleaning or wet cleaning. Embodiments of the present disclosure may be used on a wide variety of cleaning surfaces to obtain high particle removal plus very low addition of particles, for example, in display processing, silicon chip packaging, hard disk media cleaning, and optics manufacturing.
Embodiments of the disclosure provide an improved apparatus for cleaning a substrate. As described below, an apparatus for removing contaminants from a substrate includes a substrate support to support a substrate, a heated showerhead disposed opposite the substrate support and one or more nozzles disposed beneath the substrate support to discharge a mixture of solid and gaseous carbon dioxide toward the contaminants on the second side of the substrate. As described below, the inventors have observed that the distance, described below, between the heated showerhead and the substrate allows for effective heat transfer between the showerhead and the substrate. As a result, the showerhead advantageously heats that substrate to reduce or prevent condensation from forming on the substrate as a result of the cleaning process. In addition, the distance between the showerhead and the substrate, as well as a sufficient flowrate of gas from the showerhead, advantageously create a suitable gas velocity and pressure at the peripheral edge of the substrate to advantageously reduce or prevent contaminants removed from the second side of the substrate from migrating to the first side of the substrate. Furthermore, the inventors have observed that the distance, described below, between the one or more nozzles and the substrate and the nozzle angle, described below, can advantageously improve contaminant removal from the second side of the substrate.
The particular embodiment of the substrate cleaning apparatus 200 shown herein is provided for illustrative purposes and should not be used to limit the scope of the disclosure. The substrate cleaning apparatus 200 depicted in
The substrate 220 may be any suitable substrate used in a semiconductor or similar thin-film manufacturing processes, such as circular, square, rectangular, or other shaped substrates of various materials. In some embodiments, the substrate 220 may be a semiconductor wafer (e.g., a 200 mm, 300 mm, 450 mm, or the like silicon wafer). The substrate 220 to be cleaned generally includes an uncontaminated first side 236 and a contaminated second side 222. In some embodiments, the substrate support 218 grips the substrate 220 by an outer edge of the substrate 220 without gripping the first side 236, in order to prevent contamination of the first side 236, and without gripping the second side 222, in order to allow full access to the second side 222 of the substrate 220.
Below the substrate 220 are one or more nozzles coupled to a moveable arm. For example, as depicted in
In some embodiments, the one or more nozzles 212 are disposed a second distance beneath the substrate support. In some embodiments, the one or more nozzles are disposed about 1 to about 2 inches beneath the substrate support 218. In some embodiments, the one or more nozzles 212 are supported at an angle of about 20 to about 40 degrees from the substrate plane. The inventors have observed that a nozzle distance of about 1 to about 2 inches beneath the substrate support 218 and a nozzle angel of about 20 to about 40 degrees from the substrate 220 plane is optimal to remove contaminants from the second side 222 of the substrate 220.
In some embodiments, an outer surface of each of the one or more nozzles (e.g., 212, 238, 300, 302) is covered by a heating element 802. In some embodiments, as depicted in
Application of the first mixture to the contaminated second side 222 removes contaminants 240 from the second side 222. In some embodiments, the liquid carbon dioxide is supplied to the first nozzle 212 at a pressure of about 200 to about 1000 psi, or in some embodiments, about 800 to about 850 psi. In some embodiments, the liquid carbon dioxide is supplied to the first nozzle 212 at a pressure dependent upon the vapor pressure of liquid CO2 at room temperature (e.g., about 25 degrees Celsius). In some embodiments, the first nozzle 212 is a throttling nozzle, which causes an isenthalpic expansion of the liquid carbon dioxide, such that when the carbon dioxide exits the first nozzle 212, the liquid carbon dioxide expands into the first mixture 214. In some embodiments, the first mixture 214 comprises about 30% to about 40% solid carbon dioxide and about 60% to about 70% gaseous carbon dioxide.
Without wishing to be bound by theory, the inventors believe that the solid carbon dioxide particles strike the contaminants 240 on the second side 222 and change from the solid phase to the gas phase, resulting in an expansion which pushes the contaminants 240 off of the second side 222. However, other physical, chemical, and/or thermal processes that cause the removal of the contaminants 240 are possible.
In some embodiments, the first nozzle 212 is coupled to a gaseous carbon dioxide source 204 (e.g., a second carbon dioxide source), and discharges a second mixture comprising a stream of solid carbon dioxide entrained in a stream of gaseous carbon dioxide to the second side 222 of the substrate 220. A switch or other plumbing may be provided to selectively couple the first nozzle 212 to the liquid carbon dioxide source 202 or the gaseous carbon dioxide source 204. In some embodiments, the gaseous carbon dioxide passes through the fine mesh filter 210 (e.g., nickel mesh filter) as described above, to advantageously remove gross particulates from the gaseous carbon dioxide prior to discharge from the first nozzle 212.
Alternatively, in some embodiments, either the gaseous carbon dioxide source 204 or the liquid carbon dioxide source 202 is coupled to a second nozzle 238 which discharges the second mixture 216 to the second side 222 of the substrate 220. In some embodiments, the second nozzle is coupled to the moveable arm 208. In some embodiments, the gaseous carbon dioxide passes through a fine mesh filter 210 (e.g., nickel mesh filter) before being discharged by the second nozzle 238.
Similar to the first nozzle 212, in some embodiments, the second nozzle 238 is a throttling nozzle which causes an expansion of the gaseous carbon dioxide, such that when the gaseous carbon dioxide exits the second nozzle 238, the gaseous carbon dioxide expands into the second mixture 216. However, the second mixture 216 contains lesser solid carbon dioxide particles, in size as well as in amount, than the first mixture 214. In some embodiments, the second mixture 216 comprises about 1% to about 20% solid carbon dioxide and about 99% to about 80% gaseous carbon dioxide.
In some embodiments, as depicted in
In some embodiments where the substrate 220 is held in a stationary position, as depicted in
In some embodiments, as depicted in
In some embodiments, as depicted in
In one embodiment, as depicted in
In some embodiments, a showerhead 228 directs a flow of gas toward the first side 236 of the substrate 220. In some embodiments, the first gas may be air or nitrogen gas (N2). The showerhead 228 is disposed a first distance opposite the substrate support 218 and facing the first side of the substrate 220. The first distance is about 1.5 mm to about 4.4 mm. In some embodiments, a filter 255 is fluidly coupled to the showerhead 228 to remove contaminants from the gas. In some embodiments, a fan 257 is fluidly coupled to the filter 255 to direct a gas to the showerhead 228. In some embodiments, the gas is air or an inert gas, such as argon or helium. In some embodiments, the gas flow rate through the showerhead 228 is about 300 slm to about 500 slm. In some embodiments, a heater 227 is coupled to the showerhead 228 to heat the showerhead 228 to a temperature of about 120 to about 150 degrees Celsius. In some embodiments, the heater 227 may be an electric coil wrapped around the showerhead 228 or embedded in the showerhead 228. In some embodiments, the showerhead 228 is heated to a temperature of about 120 to about 150 degrees Celsius.
The inventors have observed that directing the mixtures 214, 216 of solid and gaseous carbon dioxide, which are typically at a temperature of about −40 degrees Celsius, toward the contaminated second side 222 of the substrate 220 results in localized condensation within the area contacted by the mixture 214, 216. The inventors have observed that a distance of about 1.5 mm to about 4.4 mm between the showerhead 228 and the substrate support 218 and a showerhead 228 temperature of about 120 to about 150 degrees Celsius heats the substrate 220 to about a temperature of about 80 to about 100 degrees Celsius. The inventors have observed that a substrate temperature of about 80 to about 100 degrees Celsius eliminates the localized condensation in areas contacted by the mixtures 214, 216.
In some embodiments, as depicted in
In some embodiments, the process chamber 232 comprises an exhaust system 224, fluidly coupled to the first volume 234, to remove loose contaminants and carbon dioxide particles from the first volume 234. In some embodiments, the exhaust system 224 is disposed in the direction of the mixture flow to avoid recirculation and provide flow toward the exhaust. In some embodiments, the exhaust pressure is about 0.3 to about 0.5 atm.
At 102, a mixture of solid and gaseous carbon dioxide is directed from one or more nozzles (e.g., 212, 238, 300, 302), toward the contaminated second side 222 of the substrate 220. The one or more nozzles (e.g., 212, 238, 300, 302) are disposed a second distance of about 1 inch to about 2 inches beneath the substrate support and at an angle of about 20 to about 40 degrees from the substrate plane. At 104, a flow of gas from the showerhead is directed toward the first side 236 of the substrate 220 while directing at least one of the first mixture 214 or second mixture 216 of solid and gaseous carbon dioxide to the second side 222 of the substrate 220. As discussed above, the showerhead is disposed a distance of about 1.5 mm to about 4.4 mm opposite the substrate support and is heated to a temperature of about 120 to about 150 degrees Celsius. Following completion of the cleaning process, the transfer arm 606 is extended underneath the substrate 220 to receive the substrate 220 from the gripping elements 602.
By way of illustration, a particular cluster tool 580 is shown in a plan view in
In some embodiments the exemplary method 100 of cleaning contaminants from a substrate, as described above, may be performed in connection with processing the substrate within at least one of the processing chambers. For example, at least one of the processing chambers (for example, any of 590A-D) may be a plasma etch chamber or other process chamber that performs a process on a substrate leading to contaminants begin disposed on the backside of the substrate necessitating removal. Accordingly, for example, following an etch or other process, the substrate may be removed from the plasma etch chamber and transported to the substrate cleaning chamber by the robot 589 and the pod loader 585 to remove contamination caused during the etch process. By providing a cleaning apparatus coupled to the same cluster tool as the process chambers processing the substrate, the substrate may be cleaned as soon as possible after processing to advantageously minimize contact of the contaminated substrate with processing equipment and migration of the contamination to other components or substrates as well as potentially damaging the substrate or other substrates.
The cleaning apparatus may be located in any of a number of locations on the cluster tool 580. For example, the cleaning apparatus may be disposed on a side of the factory interface, or front-end environment 583, as depicted by dashed box A. Alternatively or in combination a cleaning apparatus may be coupled to or disposed in place of one of the pods 587 coupled to the front-end environment 583, as depicted by dashed box B. Alternatively or in combination a cleaning apparatus may be coupled to or disposed at a central portion of the front-end environment 583, opposite the load locks 584, as depicted by dashed box C. Alternatively or in combination a cleaning apparatus may be coupled to or disposed along an upper surface of the front-end environment 583, as depicted by dashed box D. In positions A-C, the cleaning apparatus may or may not be disposed in a chamber. In position D, the cleaning apparatus may be provided with no chamber and may be configured to clean substrates as they move past the cleaning apparatus between pods 587 and the load locks 584. Other locations or configurations of the cleaning apparatus may also be used.
Thus, improved methods and apparatus for cleaning a substrate have been disclosed herein. The inventive apparatus may advantageously allow for the removal of contamination accumulated on a substrate during the manufacturing process, such as during handling the substrate between process steps and while chucking the substrate inside a process chamber to prevent contaminants from reaching the front-side of a substrate and causing yield loss.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof.
This application is a continuation of U.S. application Ser. No. 14/749,209, filed Jun. 24, 2015, which claims benefit of U.S. provisional patent application Ser. No. 62/153,785, filed Apr. 28, 2015, both of which are herein incorporated by reference in their entirety.
Number | Date | Country | |
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62153785 | Apr 2015 | US |
Number | Date | Country | |
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Parent | 14749209 | Jun 2015 | US |
Child | 16838848 | US |