US20230384030A1 - Wafer drying system - Google Patents
Wafer drying system Download PDFInfo
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- US20230384030A1 US20230384030A1 US18/446,858 US202318446858A US2023384030A1 US 20230384030 A1 US20230384030 A1 US 20230384030A1 US 202318446858 A US202318446858 A US 202318446858A US 2023384030 A1 US2023384030 A1 US 2023384030A1
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Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/14—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects using gases or vapours other than air or steam, e.g. inert gases
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B11/00—Machines or apparatus for drying solid materials or objects with movement which is non-progressive
- F26B11/18—Machines or apparatus for drying solid materials or objects with movement which is non-progressive on or in moving dishes, trays, pans, or other mainly-open receptacles
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B25/00—Details of general application not covered by group F26B21/00 or F26B23/00
- F26B25/22—Controlling the drying process in dependence on liquid content of solid materials or objects
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B3/00—Drying solid materials or objects by processes involving the application of heat
- F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
- F26B3/04—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour circulating over or surrounding the materials or objects to be dried
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
- H01L21/67011—Apparatus for manufacture or treatment
- H01L21/67017—Apparatus for fluid treatment
- H01L21/67028—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like
- H01L21/67034—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like for drying
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
- H01L21/67242—Apparatus for monitoring, sorting or marking
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
- H01L21/67242—Apparatus for monitoring, sorting or marking
- H01L21/67253—Process monitoring, e.g. flow or thickness monitoring
Definitions
- Production equipment used in semiconductor manufacturing can be a source of particles for wafers in an integrated circuit (IC) fabrication facility.
- IC integrated circuit
- semiconductor wafers undergo numerous processing operations. The number of particles on a wafer's surface can increase during IC fabrication as the wafer is exposed to additional processing.
- FIG. 1 is a schematic view of an a single wafer drying station, according to some embodiments.
- FIG. 2 is flow chart of a wafer drying method, according to some embodiments.
- FIG. 3 is a wafer drying system, according to some embodiments.
- first and second features are formed in direct contact
- additional features may be formed that are between the first and second features, such that the first and second features are not in direct contact.
- spatially relative terms such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures.
- the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.
- the apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
- nominal refers to a desired, or target, value of a characteristic or parameter for a component or a process operation, set during the design phase of a product or a process, together with a range of values above and/or below the desired value.
- the range of values is typically due to slight variations in manufacturing processes or tolerances.
- vertical means nominally perpendicular to the surface of a substrate.
- One way to control wafer contamination from particles is to prevent contaminating the wafer during processing. However, this is not always possible, and once the wafer is contaminated, the contaminants may be removed by cleaning.
- the goal for the wafer cleaning process is to remove wafer surface contaminants, such as particles, organics (e.g., organic byproducts), metallics (traces of metals), and native oxides.
- the wafers in semiconductor manufacturing environment can be cleaned by dry cleaning methods, wet cleaning methods, or combinations thereof.
- wet cleaning methods can be performed in wet tools, which can handle either one wafer at a time (e.g., “single-wafer” tools) or large batches of wafers at once (e.g., “batch” tools).
- the wafer enters the cleaning module and is positioned on a wafer stage (holder).
- the wafer is then subjected to a wet cleaning method via one or more nozzles positioned above the wafer's surface.
- the one or more nozzles can flow chemicals (e.g., a chemical solution, deionized water, etc.) under pressure on the wafer's surface to remove the targeted contamination (e.g., particles, metallic contaminants, organic material, etc.).
- the wafer can be rinsed with DI water and dried via spinning, while an inert gas (such as nitrogen, helium, or clean dry air with a moisture content below ⁇ 73° C. dew point, less than 1 part per million carbon dioxide, and/or less than 0.003 parts per million hydrocarbon vapor) is flown over the surface of the wafer to accelerate the drying process.
- an inert gas such as nitrogen, helium, or clean dry air with a moisture content below ⁇ 73° C. dew point, less than 1 part per million carbon dioxide, and/or less than 0.003 parts per million hydrocarbon vapor
- the wafers can be either submerged in one or more cleaning baths or be disposed into a sealed reactor, where an array of nozzles on reactor sidewalls can spray one or more chemical towards the surfaces of the wafers.
- the wafers can be subsequently rinsed with deionized water and dried with a method similar to that of the single wafer drying process.
- the wafers can be dried via spinning while an in
- the wafers can be removed from the wet cleaning tool.
- One or more wafers can be randomly selected to be screened for contaminants and particles to assess the efficiency of the wet cleaning process.
- contaminants can either refer to any unwanted particles, organics, metallics, or native oxides on the wafer's surface that endured the wet cleaning process, or to chemical traces from the wet cleaning solutions used in the wet cleaning and drying processing (e.g., water spots, acids, derivatives of ammonia, etc.).
- the wafer can be “reworked” (e.g., it can be subjected to an additional cleaning cycle) or scrapped (e.g., discarded from the production line).
- established baseline refers to a contamination level that has been deemed to have minimal impact on subsequent processing operations or have any appreciable impact on die yield loss.
- the aforementioned process can be both time consuming and costly because the contamination level is not measured concurrently (in real time) with the drying process—for example, the sampling process described above requires that the wafer (or wafers) be removed from the wet cleaning tool after the drying process, measured on a different tool (e.g., on a different part of the fabrication facility), and then returned to the wet cleaning tool for another round of cleaning, if necessary.
- analysis for the selected few wafers can take a substantial amount of time (e.g., one or more hours) that can impact the overall chip production throughput.
- This disclosure is directed to a wafer drying method that utilizes real-time detection of contaminants in a drying gas as a feedback parameter for a wafer drying process. More specifically, the method includes collecting the drying gas from a drying station, analyzing the drying gas to determine its airborne molecular contamination concentration and to compare the concentration to an established baseline. Based on the results of the comparison, the method can adjust the wafer drying process. For example, if the concentration of airborne molecular contamination in the drying gas is equal to or below the established baseline, the wafer (or wafers) can be removed from the drying station and transferred to the next processing operation.
- Airborne molecular contamination is chemical contamination that can be incorporated into the drying gas in the form of vapors or aerosols. These chemicals can be organic or inorganic in nature and can include acids, bases, polymer additives, organometallic compounds, dopants, and the like. By way of example and not limitation, the airborne molecular contamination can include volatile organic compounds, amines, inorganic acids, acetone, sulfur dioxide (SO 2 ), isopropyl alcohol (IPA), water vapors (humidity), or any combination thereof.
- FIG. 1 is a schematic view of a single-wafer drying station 100 .
- single-wafer drying station 100 is a module on a wet cleaning cluster tool (not shown in FIG. 1 for simplicity).
- the wet cleaning cluster tool may include additional components required for its operation.
- additional modules e.g., transfer modules, wet clean stations, etc.
- robotic arms pumps, exhaust lines, heating elements, gas and chemical delivery lines, mass flow controllers, gate valves, slot valves, hoses, external and internal electrical connections to other components of the cluster tool—such as computer units, chemical analyzers, controller units, pressure controllers, valves, pumps, and the like.
- These additional components may or may not be depicted in FIG. 1 for ease of illustration. However, these components are within the spirit and scope of this disclosure.
- a wafer 110 rests on wafer holder 120 .
- Wafer holder 120 attaches to a base 130 , which can rotate wafer holder 120 and spin wafer 110 during the drying process.
- Drying station 100 can further include one or more gas outlets (not shown in FIG. 1 ), which can dispense one or more drying gases 140 above the surface of wafer 110 , as shown in FIG. 1 .
- drying gas 140 can be dispensed from a central location above wafer 110 in a top down fashion, as shown in FIG. 1 .
- this is not limiting and other configurations are possible depending on the design of single-wafer drying station 100 .
- drying gas 140 can be dispensed on wafer 110 at an angle from one or more locations or from a location on the sidewalls of drying station 100 . Regardless of the configuration and the position of the gas outlet relative to the position of wafer 110 , drying gas 140 can flow substantially parallel the surface of wafer 110 before exiting drying station 100 through exhaust line 150 , as shown in FIG. 1 .
- Base 130 and its rotating mechanism can be isolated from drying gas 140 via a cover 160 .
- a drying process involves spinning wafer 110 at a predetermined speed and concurrently dispensing drying gas 140 towards the surface of the wafer at a predetermined rate. Drying gases 140 that can be used in the wafer drying process include, but are not limited to, inert gases such as nitrogen, helium, and argon. Alternatively, clean dry air can be used as a drying gas.
- the gas outlet(s) can be connected via one or more gas boxes to one or more external tanks that contain respective drying gases in high purity (above 99.999%) and under pressure.
- the gas boxes can be part of a gas distribution system where a network of gas valves and gas distribution lines are housed.
- the gas boxes and the external tanks are not shown in FIG. 1 for simplicity.
- drying station 100 in FIG. 1 is not limiting.
- drying station 100 can be configured to perform additional operations, such as dispensing deionized water on the surface of wafer 110 .
- drying station 100 can be equipped with one or more nozzles connected to external chemical lines, not shown in FIG. 1 for simplicity.
- a wet cleaning station can perform the functions of drying station 100 .
- drying station 100 can be designed to dry more than one wafer at a time (e.g., batches of wafers) using the same or similar principles described above.
- drying station 100 can include a rotating wafer holder on which up to 25 wafers can be loaded at a time.
- the drying gas can be dispensed from multiple locations of drying station 100 rather than from a top location.
- the drying gas can be dispensed from outlets located on the sidewalls of drying station 100 . Regardless of the location of the gas outlets with respect to the surface of the wafers, the drying gas can be directed towards the surface of the wafers and can exit the drying station via one or more exhaust lines, such as the exhaust line 150 .
- drying station 100 includes an exhaust line 150 though which drying gas 140 can exit from drying station 100 .
- drying station 100 can be equipped with more than one exhaust line.
- drying gas 140 once removed from drying station 100 , can be diverted to an analytical unit that can measure the concentration of airborne molecular contamination in drying gas 140 . Since drying gas 140 contacts the surface of wafer 110 , traces of chemical signatures from the wet cleaning process can be incorporated in drying gas 140 in the form of airborne molecular contamination.
- a system can determine whether wafer 110 needs to be “reworked”; for example, undergo another cycle of rinse and dry process in drying station 100 .
- collection and analysis of drying gas 140 is performed in real-time—for example, while wafer 110 is being dried in drying station 100 .
- wafer 110 is not removed from drying station 100 until the contamination analysis on drying gas 140 has been completed and the analyzed concentration of airborne molecular contaminants is equal to or below an established baseline.
- the analytical unit is configured to detect more than one airborne molecular contaminant, including, but not limited to, volatile organic compounds, amines (e.g., derivatives of ammonia), acids, acetone, sulfuric oxide, isopropyl alcohol, water vapors, etc.
- the analytical unit can include a time of flight mass spectrometer (TOFMS) that can detect volatile organic compounds, an ion mobility spectrometer that can detect traces of amines or acids, humidity detectors, or other suitable detectors for the detection of desired airborne molecular contaminants.
- TOFMS time of flight mass spectrometer
- the detection limits can depend on the type of the detectable chemicals and the analytical method used for the chemical detection.
- contamination concentration levels in the parts per trillion (ppt) or parts per million (ppm) can be measured by embodiments of the present disclosure.
- FIG. 2 is a flow chart of a wafer drying method 200 that detects airborne molecular contaminants in a drying gas as a feedback parameter for a wafer drying process, according to some embodiments.
- wafer drying method 200 can be performed in single-wafer drying station, like drying station 100 shown in FIG. 1 , or a multiple wafer drying station that can handle more than one wafer at a time—e.g., a batch of wafers.
- this disclosure is not limited to this operational description. Rather, other operations are within the spirit and scope of the present disclosure. It is to be appreciated that additional operations may be performed. Moreover, not all operations may be needed to perform the disclosure provided herein.
- wafer drying method 200 is described with reference to the embodiments shown in FIGS. 1 and 3 . Based on the disclosure herein, other configurations of single-wafer drying station 100 or drying stations that are configured to dry batches of wafers at a time, as discussed above, can be used with wafer drying method 200 as long as at least one drying gas is participating in the wafer drying process. These wafer drying stations and their configurations are within the spirit and scope of this disclosure.
- Wafer drying method 200 begins with operation 210 , where a wafer (e.g., wafer 110 ) is transferred to drying station 100 shown, for example, in FIGS. 1 and 3 .
- wafer 110 can be transferred to drying station 100 from a transfer module, a wet cleaning station, or from another module—all of which are not shown in FIGS. 1 and 3 for simplicity.
- drying station 100 can be integrated in a cluster tool.
- the cluster tool can be a wet cleaning tool that includes one or more cleaning stations, other modules (e.g., transfer modules), mechanical equipment, pneumatic equipment, electrical equipment, or other equipment required for operation.
- wafer 110 is transferred to drying station 100 from a wet cleaning station.
- drying station 100 can function as a wet cleaning station, or include additional components that are not depicted in FIGS. 1 and 3 .
- a drying gas (e.g., drying gas 140 shown in FIG. 1 ) is dispensed over wafer 110 in wafer drying station 100 .
- drying gas 140 is dispensed through one or more gas outlets located over wafer 110 .
- drying gas 140 can be dispensed from a central location above wafer 110 and cascade downwards towards the surface of wafer 110 as shown by flow lines 170 , as shown in FIG. 1 . Upon reaching the surface, drying gas 140 can flow parallel to the wafer's top surface.
- this is not limiting and other configurations are possible, where the flow lines of drying gas 140 are different from the ones shown in FIG. 1 .
- drying gas 140 can flow across the surface of wafer 110 before exiting drying station 100 through exhaust line 150 .
- a drying process involves rotating wafer 110 at a predetermined speed and concurrently dispensing drying gas 140 on the surface of the wafer at a predetermined rate.
- drying gas 140 can include an inert gas such as nitrogen, helium, or argon.
- drying gas 140 can include dry clean air.
- drying gas 140 can function as a “carrier gas” that transports the airborne molecular contaminants away from the wafer's surface, but does not chemically react with them.
- the airborne molecular contaminants can include volatile organic compounds, derivatives of ammonia (e.g., amines), acids (such as hydrofluoric acid, hydrochloric acid. etc.), acetone, sulfur dioxide, isopropyl alcohol, water vapors, other types of chemicals that have been used in a prior wafer wet cleaning operation, or combinations thereof.
- drying gas 140 may exit drying station 100 via exhaust line 150 .
- drying gas 140 can be collected from the station's exhaust line 150 .
- drying gas 140 can be diverted from main exhaust 320 (e.g., via a valve 310 ) to a detector unit 330 , according to some embodiments.
- detector unit 330 can be an intermediate station, where drying gas 140 can be chemically identified and temporarily stored until a predetermined volume of drying gas 140 has been collected.
- detector unit 330 can determine whether drying gas 140 is nitrogen, helium, argon, clean dry air, or another gas.
- one or more detector units 330 may be used to collect drying gases from respective one or more drying stations.
- the collected drying gas 140 can be analyzed to obtain a concentration of contaminants incorporated in drying gas 140 .
- the contaminants are airborne molecular contaminants in drying gas 140 that can be identified and quantified.
- drying gas 140 is transferred from detector unit 330 to one or more analyzers 340 .
- analyzer 340 can detect more than one type of airborne molecular contaminant.
- analyzer 340 may be limited to detecting a single type of airborne molecular contaminants (e.g., volatile organic compounds).
- each analyzer 340 may be required for the detection of additional types of multiple airborne molecular contaminants in drying gas 140 (e.g., inorganic contaminants). Further, each analyzer 340 can be configured to receive samples of drying gas 140 from one or more detector units 330 . In some embodiments, the one or more analyzers 340 can be disposed within or be part of detector unit 330 .
- analyzer 340 includes a time of flight mass spectrometer for volatile organic compound detection, an ion mobility spectrometer for amine and acid detection, other types of detectors for sulfuric oxide detection, humidity detectors, other types of detectors depending on the airborne molecular contaminants of interest, or combinations thereof.
- analyzer 340 can provide concentration levels of airborne molecular contaminants incorporated into drying gas 140 in parts per million (ppm), parts per billion (ppb), in atomic percentage (at. %), in a percentage by volume, or other suitable units.
- the concentration data of the airborne molecular contaminants from analyzer 340 can be sent to a computer unit or circuitry 350 , where the concentration data can be compared to an established baseline.
- the established baseline can include allowable levels of contamination for airborne molecular contaminants in drying gas 140 .
- the allowable levels of contamination can be the result of a correlation between historical contamination data and the contamination's impact on yield and/or between historical contamination data and the contamination's impact on subsequent operations or processes.
- the established baseline for each airborne molecular contaminant in drying gas 104 can be different.
- the established baseline can be adjusted depending on the type of airborne molecular contaminants and the contaminant's impact on yield or the overall yield goals.
- the established baseline can be one or more stored values in a database or a server.
- the established baseline can be one or more stored values on a local storage medium, such as a hard drive in computer unit 350 .
- computer unit 350 can be integrated with wafer drying station 100 or an integral part of the cluster tool that includes wafer drying station 100 and additional modules.
- computer unit 350 can be a remote unit, such as a server or a server network.
- computer unit 350 can be an integral part of a network system that collects and analyzes data from a variety of sources, such as, but not limited to, cluster tools, pressure sensors, analytical tools, mass flow controllers, and the like.
- computer unit 350 can be configured to receive output data from one or more analyzers 340 , compare the output data to baseline data, and provide commands to other units or modules based on the results of the comparative analysis it performs.
- wafer 110 can be reworked or removed from dry station 100 based on the comparison analysis in operation 250 .
- the rework process can include subjecting wafer 110 to a deionized water rinse and a subsequent wafer dry process in drying station 100 or subjecting wafer 110 to a wafer drying process in drying station 100 .
- computer unit 350 can send one or more commands to a control unit 360 to either rework wafer 110 in drying station 100 or remove wafer 110 from drying station 100 .
- control unit 360 can be a communication interface between computer unit 350 and drying station 100 .
- control unit 360 can be integrated with (e.g., a part of) the wet cleaning cluster tool.
- wafer 110 can be removed from drying station 100 .
- wafer 110 can be either rinsed with deionized water and dried or subjected to a drying process without a prior rinse.
- computer unit 350 can command control unit 360 to subject the wafer to a deionized water rinse followed by a drying cycle in drying station 100 .
- the drying cycle can include spinning the wafer in drying station 100 and disposing drying gas 140 over the rotating wafer.
- computer unit 350 can command cluster control unit 360 to subject the wafer to a drying cycle without a deionized water rinse.
- the drying gas used in the rework operation can be analyzed for airborne molecular contaminants according to the operations of wafer drying method 200 . This is to ensure that the rework operation has removed the targeted contaminants from the surface of the wafer.
- wafer drying method 200 can be applied to stations that can dry multiple wafers at a time (e.g., multi-wafer drying stations).
- the wafers can be transferred to a multi-wafer drying station. Similar to the case of a single wafer, the wafers are transferred to a holder.
- the wafer holder in the multi-wafer drying station can stack the wafers vertically or laterally. In some embodiments, the holder can hold 25 wafers or more at a time.
- a drying gas is dispensed over the wafers. In some embodiments, during the drying process, the wafers spin while the drying gas is released.
- the drying gas is collected via a gas exhaust in the multi-wafer drying station.
- the drying gas can be sampled and analyzed for airborne molecular contaminants using operations 240 through 250 of wafer drying method 200 .
- the same or similar detector units 330 , analyzers 340 and/or computer units 350 of FIG. 3 can be utilized to perform operations 240 and 250 .
- the wafers in the multi-wafer drying station can be reworked or removed from the multi-wafer drying station based on the comparison results from operation 250 .
- control unit 360 can be a communication interface between computer unit 350 and the multi-wafer drying station.
- control unit 360 can be a batch wet cleaning cluster tool with multi-wafer drying stations.
- This disclosure is directed to a wafer drying method that detects (e.g., real-time detection) airborne molecular contaminants in a drying gas as a feedback parameter for a single wafer or multi-wafer drying process. More specifically, the method includes collecting the drying gas from a single-wafer and/or a multi-wafer drying station, analyzing the drying gas to determine its airborne molecular contamination concentration, and comparing the concentration to one or more established baseline values. According to the comparison results, the method can make adjustments to the wafer drying process.
- the method includes collecting the drying gas from a single-wafer and/or a multi-wafer drying station, analyzing the drying gas to determine its airborne molecular contamination concentration, and comparing the concentration to one or more established baseline values. According to the comparison results, the method can make adjustments to the wafer drying process.
- the wafer (or wafers) can be removed from the single-wafer (or multi-wafer) drying station and transferred to the next processing operation. If the concentration of airborne molecular contamination is above the established baseline, the wafer (or wafers) can be subjected to an additional rinse with deionized water and additional drying operation or subjected to an additional drying operation.
- the airborne molecular contamination includes, but is not limited to, volatile organic compounds, amines, inorganic acids, acetone, sulfur dioxide (SO 2 ), isopropyl alcohol (IPA), water vapors (humidity), etc.
- the drying gas includes, but is not limited to, nitrogen, argon, helium, clean dry air, or any other suitable gas that does not chemically react with the airborne molecular contaminants to form deposits on the wafers.
- a wafer drying system includes a wafer drying station configured to dispense a drying gas over one or more wafers to dry the one or more wafers, an analyzer configured to detect contamination in the drying gas and determine the concentration of the contamination in the drying gas; and a circuitry.
- the circuitry is further configured to compare the concentration of the contamination to a baseline value, command the wafer drying station to remove the one or more wafers in response to the concentration being equal to or less than the baseline value, and command the wafer drying station to dry the one or more wafers in response to the concentration being greater than the baseline value.
- a method of drying wafers includes dispensing in a wafer drying station a drying gas over one or more wafers; collecting the drying gas from an exhaust of the wafer drying station; determining the concentration of contaminants in the drying gas; re-dispensing the drying gas over the one or more wafers in response to the concentration of contaminants being higher than a baseline value; and transferring the one or more wafers out of the wafer drying station in response to the concentration being equal to or less than the baseline value.
- a wafer drying system includes a wafer drying station configured to dispense a drying gas over one or more wafers; a detector configured to collect from an exhaust line of the wafer drying station the drying gas that has been dispensed over the one or more wafers; one or more analyzers configured to analyze the collected drying gas and output the concentration of airborne molecular contaminants dissolved in the drying gas.
- the wafer drying system also includes a circuitry that is configured to compare the concentration of airborne molecular contaminants to one or more baseline values; command the wafer drying station to remove the one or more wafers from the drying station in response to the concentration of airborne molecular contaminants being equal to or less than the baseline value; and command the wafer drying station to re-dispense the drying gas over the one or more wafers in response to the concentration of airborne molecular contaminants being greater than the baseline value.
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Abstract
The present disclosure is directed to a wafer drying system and method that detects airborne molecular contaminants in a drying gas as a feedback parameter for a single wafer or multi-wafer drying process. For example, the system comprises a wafer drying station configured to dispense a drying gas over one or more wafers to dry the one or more wafers, a valve configured to divert the drying gas to a first portion and a second portion, and an exhaust line configured to exhaust the first portion of the drying gas. The system further comprises a detector configured to receive the second portion of the drying gas and to determine a real time property of the second portion of the drying gas, and a control unit configured to control a feedback operation of the wafer drying station based on the real time property of the second portion of the drying gas.
Description
- This application is a divisional application of U.S. patent application Ser. No. 17/216,452, titled “Wafer Drying System,” filed on Mar. 29, 2021, which is a continuation application of U.S. patent application Ser. No. 16/034,526, titled “Wafer Drying System,” filed on Jul. 13, 2018, both of which are incorporated herein by reference in their entireties.
- Production equipment used in semiconductor manufacturing can be a source of particles for wafers in an integrated circuit (IC) fabrication facility. During the wafer fabrication process, semiconductor wafers undergo numerous processing operations. The number of particles on a wafer's surface can increase during IC fabrication as the wafer is exposed to additional processing.
- Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with common practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
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FIG. 1 is a schematic view of an a single wafer drying station, according to some embodiments. -
FIG. 2 is flow chart of a wafer drying method, according to some embodiments. -
FIG. 3 is a wafer drying system, according to some embodiments. - The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed that are between the first and second features, such that the first and second features are not in direct contact.
- Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
- The term “nominal” as used herein refers to a desired, or target, value of a characteristic or parameter for a component or a process operation, set during the design phase of a product or a process, together with a range of values above and/or below the desired value. The range of values is typically due to slight variations in manufacturing processes or tolerances.
- The term “substantially” as used herein indicates the value of a given quantity varies by ±5% of the value.
- The term “vertical,” as used herein, means nominally perpendicular to the surface of a substrate.
- One way to control wafer contamination from particles is to prevent contaminating the wafer during processing. However, this is not always possible, and once the wafer is contaminated, the contaminants may be removed by cleaning. The goal for the wafer cleaning process is to remove wafer surface contaminants, such as particles, organics (e.g., organic byproducts), metallics (traces of metals), and native oxides. The wafers in semiconductor manufacturing environment can be cleaned by dry cleaning methods, wet cleaning methods, or combinations thereof.
- Wet cleaning methods can be performed in wet tools, which can handle either one wafer at a time (e.g., “single-wafer” tools) or large batches of wafers at once (e.g., “batch” tools). In a single-wafer tool, the wafer enters the cleaning module and is positioned on a wafer stage (holder). The wafer is then subjected to a wet cleaning method via one or more nozzles positioned above the wafer's surface. The one or more nozzles can flow chemicals (e.g., a chemical solution, deionized water, etc.) under pressure on the wafer's surface to remove the targeted contamination (e.g., particles, metallic contaminants, organic material, etc.). After the cleaning process, the wafer can be rinsed with DI water and dried via spinning, while an inert gas (such as nitrogen, helium, or clean dry air with a moisture content below −73° C. dew point, less than 1 part per million carbon dioxide, and/or less than 0.003 parts per million hydrocarbon vapor) is flown over the surface of the wafer to accelerate the drying process. In the case of batch tools, the wafers can be either submerged in one or more cleaning baths or be disposed into a sealed reactor, where an array of nozzles on reactor sidewalls can spray one or more chemical towards the surfaces of the wafers. The wafers can be subsequently rinsed with deionized water and dried with a method similar to that of the single wafer drying process. For the example, the wafers can be dried via spinning while an inert gas or clean dry air is flown over the surface of the wafers to accelerate the drying process.
- Once the drying process is completed, the wafers can be removed from the wet cleaning tool. One or more wafers can be randomly selected to be screened for contaminants and particles to assess the efficiency of the wet cleaning process. The term “contaminants,” as used herein, can either refer to any unwanted particles, organics, metallics, or native oxides on the wafer's surface that endured the wet cleaning process, or to chemical traces from the wet cleaning solutions used in the wet cleaning and drying processing (e.g., water spots, acids, derivatives of ammonia, etc.).
- If the concentration of contaminants (e.g., the contamination level) on the wafer is elevated compared to an established baseline, the wafer can be “reworked” (e.g., it can be subjected to an additional cleaning cycle) or scrapped (e.g., discarded from the production line). The term “established baseline,” as used herein, refers to a contamination level that has been deemed to have minimal impact on subsequent processing operations or have any appreciable impact on die yield loss. The aforementioned process can be both time consuming and costly because the contamination level is not measured concurrently (in real time) with the drying process—for example, the sampling process described above requires that the wafer (or wafers) be removed from the wet cleaning tool after the drying process, measured on a different tool (e.g., on a different part of the fabrication facility), and then returned to the wet cleaning tool for another round of cleaning, if necessary. In some cases, analysis for the selected few wafers can take a substantial amount of time (e.g., one or more hours) that can impact the overall chip production throughput.
- This disclosure is directed to a wafer drying method that utilizes real-time detection of contaminants in a drying gas as a feedback parameter for a wafer drying process. More specifically, the method includes collecting the drying gas from a drying station, analyzing the drying gas to determine its airborne molecular contamination concentration and to compare the concentration to an established baseline. Based on the results of the comparison, the method can adjust the wafer drying process. For example, if the concentration of airborne molecular contamination in the drying gas is equal to or below the established baseline, the wafer (or wafers) can be removed from the drying station and transferred to the next processing operation. If the concentration of airborne molecular contamination is above the established baseline, an additional rinse (e.g., with deionized water) and dry cycle can be performed on the wafer (or wafers). Airborne molecular contamination is chemical contamination that can be incorporated into the drying gas in the form of vapors or aerosols. These chemicals can be organic or inorganic in nature and can include acids, bases, polymer additives, organometallic compounds, dopants, and the like. By way of example and not limitation, the airborne molecular contamination can include volatile organic compounds, amines, inorganic acids, acetone, sulfur dioxide (SO2), isopropyl alcohol (IPA), water vapors (humidity), or any combination thereof.
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FIG. 1 is a schematic view of a single-wafer drying station 100. In some embodiments, single-wafer drying station 100 is a module on a wet cleaning cluster tool (not shown inFIG. 1 for simplicity). The wet cleaning cluster tool may include additional components required for its operation. By way of example, such components can include, but are not limited to, additional modules (e.g., transfer modules, wet clean stations, etc.), robotic arms, pumps, exhaust lines, heating elements, gas and chemical delivery lines, mass flow controllers, gate valves, slot valves, hoses, external and internal electrical connections to other components of the cluster tool—such as computer units, chemical analyzers, controller units, pressure controllers, valves, pumps, and the like. These additional components may or may not be depicted inFIG. 1 for ease of illustration. However, these components are within the spirit and scope of this disclosure. - In single-
wafer drying station 100, awafer 110 rests onwafer holder 120. Wafer holder 120 attaches to abase 130, which can rotatewafer holder 120 andspin wafer 110 during the drying process.Drying station 100 can further include one or more gas outlets (not shown inFIG. 1 ), which can dispense one ormore drying gases 140 above the surface ofwafer 110, as shown inFIG. 1 . In some embodiments,drying gas 140 can be dispensed from a central location abovewafer 110 in a top down fashion, as shown inFIG. 1 . However, this is not limiting and other configurations are possible depending on the design of single-wafer drying station 100. For example, dryinggas 140 can be dispensed onwafer 110 at an angle from one or more locations or from a location on the sidewalls of dryingstation 100. Regardless of the configuration and the position of the gas outlet relative to the position ofwafer 110, dryinggas 140 can flow substantially parallel the surface ofwafer 110 before exiting dryingstation 100 throughexhaust line 150, as shown inFIG. 1 .Base 130 and its rotating mechanism can be isolated from dryinggas 140 via acover 160. In some embodiments, a drying process involves spinningwafer 110 at a predetermined speed and concurrently dispensing dryinggas 140 towards the surface of the wafer at a predetermined rate. Dryinggases 140 that can be used in the wafer drying process include, but are not limited to, inert gases such as nitrogen, helium, and argon. Alternatively, clean dry air can be used as a drying gas. - By way of example and not limitation, the gas outlet(s) can be connected via one or more gas boxes to one or more external tanks that contain respective drying gases in high purity (above 99.999%) and under pressure. The gas boxes can be part of a gas distribution system where a network of gas valves and gas distribution lines are housed. The gas boxes and the external tanks are not shown in
FIG. 1 for simplicity. - The illustration of drying
station 100 inFIG. 1 is not limiting. For example, dryingstation 100 can be configured to perform additional operations, such as dispensing deionized water on the surface ofwafer 110. For example, dryingstation 100 can be equipped with one or more nozzles connected to external chemical lines, not shown inFIG. 1 for simplicity. Alternatively, a wet cleaning station can perform the functions of dryingstation 100. - In some embodiments, drying
station 100 can be designed to dry more than one wafer at a time (e.g., batches of wafers) using the same or similar principles described above. For example, dryingstation 100 can include a rotating wafer holder on which up to 25 wafers can be loaded at a time. In this configuration, and during the drying process, the drying gas can be dispensed from multiple locations of dryingstation 100 rather than from a top location. By way of example and not limitation, the drying gas can be dispensed from outlets located on the sidewalls of dryingstation 100. Regardless of the location of the gas outlets with respect to the surface of the wafers, the drying gas can be directed towards the surface of the wafers and can exit the drying station via one or more exhaust lines, such as theexhaust line 150. - As discussed above, and referring to
FIG. 1 , dryingstation 100 includes anexhaust line 150 though which dryinggas 140 can exit from dryingstation 100. However, this is not limiting and dryingstation 100 can be equipped with more than one exhaust line. According to some embodiments, dryinggas 140, once removed from dryingstation 100, can be diverted to an analytical unit that can measure the concentration of airborne molecular contamination in dryinggas 140. Since dryinggas 140 contacts the surface ofwafer 110, traces of chemical signatures from the wet cleaning process can be incorporated in dryinggas 140 in the form of airborne molecular contamination. By measuring the concentration of the airborne molecular contamination in dryinggas 140, a system can determine whetherwafer 110 needs to be “reworked”; for example, undergo another cycle of rinse and dry process in dryingstation 100. In some embodiments, collection and analysis of dryinggas 140 is performed in real-time—for example, whilewafer 110 is being dried in dryingstation 100. Further, in some embodiments,wafer 110 is not removed from dryingstation 100 until the contamination analysis on dryinggas 140 has been completed and the analyzed concentration of airborne molecular contaminants is equal to or below an established baseline. - In some embodiments, the analytical unit is configured to detect more than one airborne molecular contaminant, including, but not limited to, volatile organic compounds, amines (e.g., derivatives of ammonia), acids, acetone, sulfuric oxide, isopropyl alcohol, water vapors, etc. By way of example and not limitation, the analytical unit can include a time of flight mass spectrometer (TOFMS) that can detect volatile organic compounds, an ion mobility spectrometer that can detect traces of amines or acids, humidity detectors, or other suitable detectors for the detection of desired airborne molecular contaminants. The detection limits can depend on the type of the detectable chemicals and the analytical method used for the chemical detection. In some embodiments, contamination concentration levels in the parts per trillion (ppt) or parts per million (ppm) can be measured by embodiments of the present disclosure.
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FIG. 2 is a flow chart of awafer drying method 200 that detects airborne molecular contaminants in a drying gas as a feedback parameter for a wafer drying process, according to some embodiments. In some embodiments,wafer drying method 200 can be performed in single-wafer drying station, like dryingstation 100 shown inFIG. 1 , or a multiple wafer drying station that can handle more than one wafer at a time—e.g., a batch of wafers. Further, this disclosure is not limited to this operational description. Rather, other operations are within the spirit and scope of the present disclosure. It is to be appreciated that additional operations may be performed. Moreover, not all operations may be needed to perform the disclosure provided herein. Additionally, some of the operations may be performed simultaneously, or in a different order than shown inFIG. 2 . In some implementations, one or more other operations may be performed in addition to or in place of the presently described operations. For illustrative purposes,wafer drying method 200 is described with reference to the embodiments shown inFIGS. 1 and 3 . Based on the disclosure herein, other configurations of single-wafer drying station 100 or drying stations that are configured to dry batches of wafers at a time, as discussed above, can be used withwafer drying method 200 as long as at least one drying gas is participating in the wafer drying process. These wafer drying stations and their configurations are within the spirit and scope of this disclosure. -
Wafer drying method 200 begins withoperation 210, where a wafer (e.g., wafer 110) is transferred to dryingstation 100 shown, for example, inFIGS. 1 and 3 . By way of example and not limitation,wafer 110 can be transferred to dryingstation 100 from a transfer module, a wet cleaning station, or from another module—all of which are not shown inFIGS. 1 and 3 for simplicity. As discussed above, dryingstation 100 can be integrated in a cluster tool. The cluster tool can be a wet cleaning tool that includes one or more cleaning stations, other modules (e.g., transfer modules), mechanical equipment, pneumatic equipment, electrical equipment, or other equipment required for operation. In some embodiments,wafer 110 is transferred to dryingstation 100 from a wet cleaning station. According to some embodiments, dryingstation 100 can function as a wet cleaning station, or include additional components that are not depicted inFIGS. 1 and 3 . - In
operation 220 ofwafer drying method 200, a drying gas (e.g., dryinggas 140 shown inFIG. 1 ) is dispensed overwafer 110 inwafer drying station 100. In some embodiments, dryinggas 140 is dispensed through one or more gas outlets located overwafer 110. In some embodiments, dryinggas 140 can be dispensed from a central location abovewafer 110 and cascade downwards towards the surface ofwafer 110 as shown byflow lines 170, as shown inFIG. 1 . Upon reaching the surface, dryinggas 140 can flow parallel to the wafer's top surface. However this is not limiting and other configurations are possible, where the flow lines of dryinggas 140 are different from the ones shown inFIG. 1 . Regardless of the configuration or the position of the gas outlet relative to the position ofwafer 110, dryinggas 140 can flow across the surface ofwafer 110 before exiting dryingstation 100 throughexhaust line 150. In some embodiments, a drying process involvesrotating wafer 110 at a predetermined speed and concurrently dispensing dryinggas 140 on the surface of the wafer at a predetermined rate. By way of example and not limitation, dryinggas 140 can include an inert gas such as nitrogen, helium, or argon. Alternatively, dryinggas 140 can include dry clean air. - As drying
gas 140 travels along the surface of spinningwafer 110, airborne molecular contaminants can be incorporated, dissolved, or suspended in dryinggas 140. In other words, dryinggas 140 can function as a “carrier gas” that transports the airborne molecular contaminants away from the wafer's surface, but does not chemically react with them. By way of example and not limitation, the airborne molecular contaminants can include volatile organic compounds, derivatives of ammonia (e.g., amines), acids (such as hydrofluoric acid, hydrochloric acid. etc.), acetone, sulfur dioxide, isopropyl alcohol, water vapors, other types of chemicals that have been used in a prior wafer wet cleaning operation, or combinations thereof. Based on the type of airborne molecular contaminants to be detected, a selection of an appropriate drying gas can be made. For example, the drying gas should not chemically react with the airborne molecular contaminants because such reaction can result in the formation of deposits on the wafer's surface or in alteration of the airborne molecular contaminants. For example, dry clean air may not be appropriate for certain categories of airborne molecular contaminants due to its reactivity. Referring toFIGS. 1 and 3 , dryinggas 140 may exit dryingstation 100 viaexhaust line 150. -
Wafer drying method 200 continues withoperation 230, where dryinggas 140 can be collected from the station'sexhaust line 150. In referring toFIG. 3 , dryinggas 140 can be diverted from main exhaust 320 (e.g., via a valve 310) to adetector unit 330, according to some embodiments. By way of example and not limitation,detector unit 330 can be an intermediate station, where dryinggas 140 can be chemically identified and temporarily stored until a predetermined volume of dryinggas 140 has been collected. For example,detector unit 330 can determine whether dryinggas 140 is nitrogen, helium, argon, clean dry air, or another gas. In some embodiments, one ormore detector units 330 may be used to collect drying gases from respective one or more drying stations. - In
operation 240 ofwafer drying method 200, the collected dryinggas 140 can be analyzed to obtain a concentration of contaminants incorporated in dryinggas 140. In some embodiments, inoperation 240, the contaminants are airborne molecular contaminants in dryinggas 140 that can be identified and quantified. For example, and referring toFIG. 3 , dryinggas 140 is transferred fromdetector unit 330 to one ormore analyzers 340. In some embodiments,analyzer 340 can detect more than one type of airborne molecular contaminant. In other embodiments,analyzer 340 may be limited to detecting a single type of airborne molecular contaminants (e.g., volatile organic compounds). Consequently, one ormore analyzers 340 may be required for the detection of additional types of multiple airborne molecular contaminants in drying gas 140 (e.g., inorganic contaminants). Further, eachanalyzer 340 can be configured to receive samples of dryinggas 140 from one ormore detector units 330. In some embodiments, the one ormore analyzers 340 can be disposed within or be part ofdetector unit 330. - In some embodiments,
analyzer 340 includes a time of flight mass spectrometer for volatile organic compound detection, an ion mobility spectrometer for amine and acid detection, other types of detectors for sulfuric oxide detection, humidity detectors, other types of detectors depending on the airborne molecular contaminants of interest, or combinations thereof. In some embodiments,analyzer 340 can provide concentration levels of airborne molecular contaminants incorporated into dryinggas 140 in parts per million (ppm), parts per billion (ppb), in atomic percentage (at. %), in a percentage by volume, or other suitable units. - In referring to
FIG. 3 andoperation 250 ofwafer drying method 200 ofFIG. 2 , the concentration data of the airborne molecular contaminants fromanalyzer 340 can be sent to a computer unit orcircuitry 350, where the concentration data can be compared to an established baseline. By way of example and not limitation, the established baseline can include allowable levels of contamination for airborne molecular contaminants in dryinggas 140. The allowable levels of contamination can be the result of a correlation between historical contamination data and the contamination's impact on yield and/or between historical contamination data and the contamination's impact on subsequent operations or processes. In some embodiments, the established baseline for each airborne molecular contaminant in drying gas 104 can be different. Further, the established baseline can be adjusted depending on the type of airborne molecular contaminants and the contaminant's impact on yield or the overall yield goals. By way of example and not limitation, the established baseline can be one or more stored values in a database or a server. In some embodiments, the established baseline can be one or more stored values on a local storage medium, such as a hard drive incomputer unit 350. - By way of example and not limitation,
computer unit 350, shown inFIG. 3 , can be integrated withwafer drying station 100 or an integral part of the cluster tool that includeswafer drying station 100 and additional modules. Alternatively,computer unit 350 can be a remote unit, such as a server or a server network. Further,computer unit 350 can be an integral part of a network system that collects and analyzes data from a variety of sources, such as, but not limited to, cluster tools, pressure sensors, analytical tools, mass flow controllers, and the like. In some embodiments,computer unit 350 can be configured to receive output data from one ormore analyzers 340, compare the output data to baseline data, and provide commands to other units or modules based on the results of the comparative analysis it performs. - In
operation 260 ofwafer drying method 200,wafer 110 can be reworked or removed fromdry station 100 based on the comparison analysis inoperation 250. In some embodiments, the rework process can include subjectingwafer 110 to a deionized water rinse and a subsequent wafer dry process in dryingstation 100 or subjectingwafer 110 to a wafer drying process in dryingstation 100. For example, referring toFIG. 3 ,computer unit 350 can send one or more commands to acontrol unit 360 to either reworkwafer 110 in dryingstation 100 or removewafer 110 from dryingstation 100. In some embodiments,control unit 360 can be a communication interface betweencomputer unit 350 and dryingstation 100. In some embodiments,control unit 360 can be integrated with (e.g., a part of) the wet cleaning cluster tool. - In some embodiments, if the concentration of the airborne molecular contaminants in drying
gas 140 is equal to or below the established baseline,wafer 110 can be removed from dryingstation 100. On the other hand, if the concentration of the airborne molecular contaminants in dryinggas 140 is above the established baseline,wafer 110 can be either rinsed with deionized water and dried or subjected to a drying process without a prior rinse. For example, if the concentration of volatile organic compounds, amines, or sulfuric oxide is above the established baseline for these contaminants,computer unit 350 can commandcontrol unit 360 to subject the wafer to a deionized water rinse followed by a drying cycle in dryingstation 100. The drying cycle can include spinning the wafer in dryingstation 100 and disposing dryinggas 140 over the rotating wafer. On the other hand, if the measured humidity levels of dryinggas 140 are above the allowable levels,computer unit 350 can commandcluster control unit 360 to subject the wafer to a drying cycle without a deionized water rinse. - In some embodiments, after the rework process, the drying gas used in the rework operation can be analyzed for airborne molecular contaminants according to the operations of
wafer drying method 200. This is to ensure that the rework operation has removed the targeted contaminants from the surface of the wafer. - As discussed above,
wafer drying method 200 can be applied to stations that can dry multiple wafers at a time (e.g., multi-wafer drying stations). For example, inoperation 210 ofwafer drying method 200 ofFIG. 2 , the wafers can be transferred to a multi-wafer drying station. Similar to the case of a single wafer, the wafers are transferred to a holder. The wafer holder in the multi-wafer drying station can stack the wafers vertically or laterally. In some embodiments, the holder can hold 25 wafers or more at a time. Inoperation 220, a drying gas is dispensed over the wafers. In some embodiments, during the drying process, the wafers spin while the drying gas is released. Inoperation 230 ofwafer drying method 200, the drying gas is collected via a gas exhaust in the multi-wafer drying station. In some embodiments, the drying gas can be sampled and analyzed for airborne molecularcontaminants using operations 240 through 250 ofwafer drying method 200. For example, the same orsimilar detector units 330,analyzers 340 and/orcomputer units 350 ofFIG. 3 can be utilized to performoperations operation 260 ofwafer drying method 200, the wafers in the multi-wafer drying station can be reworked or removed from the multi-wafer drying station based on the comparison results fromoperation 250. InFIG. 3 ,control unit 360 can be a communication interface betweencomputer unit 350 and the multi-wafer drying station. In some embodiments,control unit 360 can be a batch wet cleaning cluster tool with multi-wafer drying stations. - This disclosure is directed to a wafer drying method that detects (e.g., real-time detection) airborne molecular contaminants in a drying gas as a feedback parameter for a single wafer or multi-wafer drying process. More specifically, the method includes collecting the drying gas from a single-wafer and/or a multi-wafer drying station, analyzing the drying gas to determine its airborne molecular contamination concentration, and comparing the concentration to one or more established baseline values. According to the comparison results, the method can make adjustments to the wafer drying process. For example, if the concentration of airborne molecular contamination in the drying gas is equal to or below the established baseline, the wafer (or wafers) can be removed from the single-wafer (or multi-wafer) drying station and transferred to the next processing operation. If the concentration of airborne molecular contamination is above the established baseline, the wafer (or wafers) can be subjected to an additional rinse with deionized water and additional drying operation or subjected to an additional drying operation. In some embodiments, the airborne molecular contamination includes, but is not limited to, volatile organic compounds, amines, inorganic acids, acetone, sulfur dioxide (SO2), isopropyl alcohol (IPA), water vapors (humidity), etc. In some embodiments, the drying gas includes, but is not limited to, nitrogen, argon, helium, clean dry air, or any other suitable gas that does not chemically react with the airborne molecular contaminants to form deposits on the wafers.
- In some embodiments a wafer drying system includes a wafer drying station configured to dispense a drying gas over one or more wafers to dry the one or more wafers, an analyzer configured to detect contamination in the drying gas and determine the concentration of the contamination in the drying gas; and a circuitry. The circuitry is further configured to compare the concentration of the contamination to a baseline value, command the wafer drying station to remove the one or more wafers in response to the concentration being equal to or less than the baseline value, and command the wafer drying station to dry the one or more wafers in response to the concentration being greater than the baseline value.
- In some embodiments, a method of drying wafers, includes dispensing in a wafer drying station a drying gas over one or more wafers; collecting the drying gas from an exhaust of the wafer drying station; determining the concentration of contaminants in the drying gas; re-dispensing the drying gas over the one or more wafers in response to the concentration of contaminants being higher than a baseline value; and transferring the one or more wafers out of the wafer drying station in response to the concentration being equal to or less than the baseline value.
- In some embodiments, a wafer drying system includes a wafer drying station configured to dispense a drying gas over one or more wafers; a detector configured to collect from an exhaust line of the wafer drying station the drying gas that has been dispensed over the one or more wafers; one or more analyzers configured to analyze the collected drying gas and output the concentration of airborne molecular contaminants dissolved in the drying gas. The wafer drying system also includes a circuitry that is configured to compare the concentration of airborne molecular contaminants to one or more baseline values; command the wafer drying station to remove the one or more wafers from the drying station in response to the concentration of airborne molecular contaminants being equal to or less than the baseline value; and command the wafer drying station to re-dispense the drying gas over the one or more wafers in response to the concentration of airborne molecular contaminants being greater than the baseline value.
- It is to be appreciated that the Detailed Description section, and not the Abstract of the Disclosure section, is intended to be used to interpret the claims. The Abstract of the Disclosure section may set forth one or more but not all possible embodiments of the present disclosure as contemplated by the inventor(s), and thus, are not intended to limit the subjoined claims in any way.
- The foregoing disclosure outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art will appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art will also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
Claims (20)
1. A method of drying wafers, comprising:
dispensing, in a wafer drying station, a drying gas over one or more wafers;
diverting a first portion of the drying gas to an exhaust line and a second portion of the drying gas to a detector;
exhausting, via the exhaust line, the first portion of the drying gas from the wafer drying station;
collecting the second portion of the drying gas to determine a real time property of the second portion of the drying gas; and
controlling a feedback operation of the wafer drying station based on the real time property of the second portion of the drying gas.
2. The method of claim 1 , further comprising measuring a concentration of a contaminant in the second portion of the drying gas based on the real time property of the second portion of the drying gas received from the detector.
3. The method of claim 2 , further comprising comparing the concentration of the contamination to a baseline value.
4. The method of claim 3 , further comprising:
in response to the concentration being equal to or less than the baseline value, removing the one or more wafers from the wafer drying station; and
in response to the concentration being greater than the baseline value, rinsing the one or more wafers with deionized water and drying the one or more wafers.
5. The method of claim 2 , wherein measuring the concentration of the contaminant comprises measuring volatile organic compounds, amines, inorganic acids, acetone, sulfur dioxide, isopropyl alcohol, water vapors, or combinations thereof.
6. The method of claim 1 , wherein dispensing the drying gas comprises dispensing an inert gas or clean dry air.
7. The method of claim 6 , wherein dispensing the inert gas comprises dispensing nitrogen, argon, or helium.
8. The method of claim 1 , further comprising dispensing deionized water over the one or more wafers.
9. A method, comprising:
dispensing a drying gas over a wafer;
analyzing the drying gas to determine a concentration of a contaminant in the drying gas;
performing a removal operation on the wafer in response to the concentration of the contaminant being equal to or less than a baseline; and
performing a rework operation on the wafer in response to the concentration of the contaminant being greater than the baseline.
10. The method of claim 9 , wherein performing the rework operation comprises rinsing the wafer with deionized water.
11. The method of claim 10 , wherein performing the rework operation further comprises dispensing an inert gas over the wafer after rinsing the wafer.
12. The method of claim 9 , wherein analyzing the drying gas comprises sampling the drying gas while dispensing the drying gas over the wafer.
13. The method of claim 9 , further comprising analyzing the drying gas to determine a humidity level of the drying gas.
14. The method of claim 13 , further comprising performing a dry operation on the wafer in response to the humidity level being greater than a baseline humidity level.
15. A method, comprising:
dispensing a drying gas over a wafer;
collecting a portion of the drying gas;
analyzing the portion of the drying gas to determine a property of the drying gas;
performing a comparison between the property of the drying gas and a baseline reference; and
performing a feedback operation on the wafer based on the comparison.
16. The method of claim 15 , wherein dispensing the drying gas over the wafer comprises dispensing the drying gas while spinning the wafer.
17. The method of claim 15 , wherein collecting the portion of the drying gas comprises collecting a predetermined volume of the drying gas.
18. The method of claim 15 , wherein analyzing the portion of the drying gas comprises chemically identifying the portion of the drying gas.
19. The method of claim 15 , wherein analyzing the portion of the drying gas comprises measuring, in the portion of the drying gas, a concentration of volatile organic compounds, amines, inorganic acids, acetone, sulfur dioxide, isopropyl alcohol, water vapors, or combinations thereof.
20. The method of claim 15 , wherein performing the comparison between the property of the drying gas and the baseline reference comprises comparing a contamination level of the drying gas and a baseline contamination level.
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US18/446,858 US20230384030A1 (en) | 2018-07-13 | 2023-08-09 | Wafer drying system |
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US16/034,526 US10962285B2 (en) | 2018-07-13 | 2018-07-13 | Wafer drying system |
US17/216,452 US11927392B2 (en) | 2018-07-13 | 2021-03-29 | Wafer drying system |
US18/446,858 US20230384030A1 (en) | 2018-07-13 | 2023-08-09 | Wafer drying system |
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US10962285B2 (en) * | 2018-07-13 | 2021-03-30 | Taiwan Semiconductor Manufacturing Co., Ltd. | Wafer drying system |
US11581199B2 (en) * | 2018-10-30 | 2023-02-14 | Taiwan Semiconductor Manufacturing Co., Ltd. | Wafer drying system |
KR102267912B1 (en) * | 2019-05-14 | 2021-06-23 | 세메스 주식회사 | Method for treating a substrate and an apparatus for treating a substrate |
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TWI240952B (en) | 2003-10-28 | 2005-10-01 | Samsung Electronics Co Ltd | System for rinsing and drying semiconductor substrates and method therefor |
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TWI728399B (en) | 2021-05-21 |
US10962285B2 (en) | 2021-03-30 |
TW202006856A (en) | 2020-02-01 |
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