Patent Application
20080006303
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate several aspects of the invention and together with a description of the embodiments serve to explain the principles of the invention. A brief description of the drawings is as follows:
The embodiments of the present invention described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather a purpose of the embodiments chosen and described is so that the appreciation and understanding by others skilled in the art of the principles and practices of the present invention can be facilitated.
As noted above, the present invention contemplates removal of particles by causing liquid aerosol droplets comprising water and a tensioactive compound to contact a surface with sufficient force to remove particles from the surface. Because the liquid aerosol droplets are directed to the surface of the substrate with force, particles are removed from the substrate in a manner exceeding the amount of particles that can be rinsed away from the surface by conventional rinsing with the same composition. For example, removal of particles is conventionally tested by first applying silicon nitride particles by exposure of the surface to a spray or bath containing particles. Where this test surface is merely rinsed with a composition as described herein (with no additional cleaning steps being taken as part of a total treatment regimen), the number of particles that are removed is typically below the margin of error of the testing protocol. In contrast, the present method when carried out with no other cleaning steps but with sufficient force in an amount effective to remove particles can remove particles in a statistically significant manner, preferably greater than 40%, more preferably greater than 50%, and most preferably greater than 60%.
The substrate having a surface to be cleaned is preferably a microelectronic device requiring a high degree of cleanness, meaning that the surface of the substrate should be substantially free or have a great reduction in the number of undesired particle impurities after performance of the present process. Examples of such substrates include semiconductor wafers at any stage of processing whether raw, etched with any feature, coated, or integrated with conductor leads or traces as an integrated circuit device, and devices such as flat panel displays, micro-electrical-mechanical-systems (MEMS), microelectronic masks, advanced electrical interconnect systems, optical components and devices, components of mass data storage devices (disk drives), lead frames, medical devices, disks and heads, and the like.
The present method can be carried out as part of other treatment processes being performed on the substrate, either before or after any given process. Additional processes that may be performed on the substrate include either immersion process steps, spray process steps or combinations thereof. The present method is essentially a spray process step, and is readily incorporated in a substrate preparation protocol that includes only spray process steps, due to the efficiency in minimizing manipulation procedures by positioning the substrate in a spray process tool configuration and carrying out all treatments in the same configuration. The present method can be carried out in a tool having substrates provided in a single substrate configuration or a configuration for treatment of a plurality of substrates, either in a stack or a carousel array or both.
The substrate is preferably rotated during treatment to provide adequate and preferably uniform exposure to the aerosol droplets during the treatment process. Preferably, the substrate is rotated while it is oriented in a substantially horizontal manner, although it is contemplated that the microelectronic device can be otherwise supported at an angle tilted from horizontal (including vertical). The aerosol droplets can be dispensed to the center area of a rotating microelectronic device or toward one edge or another thereof or anywhere in-between, with it being preferable that a particle removal operation effectively treat the desired surface of the microelectronic device for a determined time period to achieve a clean device in accordance with predetermined conditions.
The liquid aerosol droplets, on contact with the surface, comprise water and a tensioactive compound. In one embodiment, the non-tensioactive compound liquid of the liquid aerosol droplets is the same composition as a conventional rinse fluid that can comprise any fluid that can be dispensed to the microelectronic device surface and that effectively rinses a device surface to reduce contaminants and/or prior applied processing liquid or gas. The liquid is preferably DI water, but optionally may include one or more treatment components, i.e. ingredients to treat the surface. An example of such a liquid composition comprising treatment components is the SC-1 composition, which is an ammonium hydroxide/hydrogen peroxide/water composition.
The tensioactive compound is selected from the group consisting of isopropyl alcohol, ethyl alcohol, methyl alcohol, 1-methoxy-2-propanol, di-acetone alcohol, ethylene glycol, tetrahydrofuran, acetone, perfluorohexane, hexane and ether. A particularly preferred tensioactive compound is isopropyl alcohol.
In an embodiment of the present invention, the tensioactive compound is present in the liquid aerosol droplet at a concentration of from about 0.1 to about 3 vol %. In another embodiment of the present invention, the tensioactive compound is present in the liquid aerosol droplet at a concentration of from about 1 to about 3 vol %.
Liquid aerosol droplets may be formed from any appropriate technique, such as by forcing fluid through a valve under pressure from a propellant, as in a conventional aerosol spray can, or more preferably by impinging streams of liquid or liquid and gas. Examples of nozzles suitable for use in preparing liquid aerosol droplets include those shown in U.S. Pat. Nos. 5,873,380; 5,918,817; 5,934,566; 6,048,409 and 6,708,903.
The gas may be any appropriate gas, including in particular non-reactive or relatively non-reactive gasses such as nitrogen, compressed dry air, carbon dioxide, and the noble gasses such as argon.
In a preferred embodiment, the tensioactive compound is provided to the droplet by incorporation of the compound in the gas. In one embodiment, the liquid aerosol droplets are formed by impinging at least one stream of a liquid composition comprising water with at least one gas stream of a tensioactive compound vapor-containing gas, thereby forming liquid aerosol droplets comprising water and a tensioactive compound. In another embodiment, the liquid aerosol droplets are formed by impinging two streams of liquid compositions, at least one of which comprises water with one gas stream of a tensioactive compound vapor-containing gas, thereby forming liquid aerosol droplets comprising water and a tensioactive compound.
Preferably, the tensioactive compound is present as about 1 to 3 vol % in the gas. Amounts of tensioactive compound higher than about 3% generally introduces handling complications, such as condensation of the compound out of the gas unless the supply lines are heated. Additionally, higher concentrations of tensioactive compounds tend to raise flammability concerns. The tensioactive compound can be incorporated in the gas in any desired manner, such as bubbling the gas through a solution of tensioactive compound.
Alternatively, the tensioactive compound can be provided as an ingredient in the liquid prior to dispensing through the liquid orifices. In this embodiment, the tensioactive compound is preferably provided as a pre-mixed solution provided to the tool in a pre-diluted manner. Alternatively, the tensioactive compound can be supplied to the liquid within the tool and upstream from or at the spray nozzle. This embodiment, however, is less preferred because the tensioactive compound would be necessarily present as a concentrated composition in the tool in a reservoir and in supply lines containing highly concentrated tensioactive compound. The presence of highly concentrated tensioactive compound in the tool is generally less desirable due to flammability and mix control concerns. In one embodiment, the liquid aerosol droplets are formed by impinging at least one stream of a liquid composition comprising water and a tensioactive compound with at least one gas stream, thereby forming liquid aerosol droplets comprising water and a tensioactive compound. In another embodiment, the liquid aerosol droplets are formed by impinging two streams of liquid compositions, at least one of which comprises water and a tensioactive compound with one gas stream, thereby forming liquid aerosol droplets comprising water and a tensioactive compound. In yet another embodiment, the liquid aerosol droplets are formed by impinging two streams of liquid compositions, at least one of which comprises water and a tensioactive compound, thereby forming liquid aerosol droplets comprising water and a tensioactive compound.
In the embodiment of the present invention where the liquid aerosol droplets are formed without the tensioactive compound, an atmosphere containing the tensioactive compound is created in the processing chamber prior to and during formation and direction of the liquid aerosol droplets toward the surface. The atmosphere containing the tensioactive compound is prepared in any manner such as will now be apparent to the skilled artisan. In an embodiment of the present invention, the tensioactive compound is present on the surface of the substrate. In another embodiment of the present invention, the tensioactive compound is present in the atmosphere at a level such that the tensioactive compound condenses on the surface of the substrate. In another embodiment of the present invention, the tensioactive compound is present in the atmosphere at a level below the saturation point, so that condensation of the tensioactive compound on the surface is avoided.
An embodiment of the present invention is schematically illustrated in
Spray bar 20 comprises a plurality of nozzles to direct liquid aerosol droplets onto wafer 13. Liquid is provided from liquid supply reservoir 22 through line 23, and gas is similarly provided from gas supply reservoir 24 though line 25. Spray bar 20 is preferably provided with a plurality of nozzles to generate the aerosol droplets. In a preferred embodiment, nozzles are provided at a spacing of about 3.5 mm in spray bar 20 at locations corresponding to either the radius of the wafer or the full diameter of the wafer when spray bar 20 is in position over wafer 13. Nozzles may optionally be provided at different spacing closer to the axis of rotation as compared to the spacing of the nozzles at the outer edge of the wafer. A preferred spray bar configuration is described in U.S. Patent Application Ser. No. 60/819,133, entitled BARRIER STRUCTURE AND NOZZLE DEVICE FOR USE IN TOOLS USED TO PROCESS MICROELECTRONIC WORKPIECES WITH ONE OR MORE TREATMENT FLUIDS, filed on Jul. 7, 2006; and also U.S. patent application Ser. No. [docket no FSI0202/US], entitled BARRIER STRUCTURE AND NOZZLE DEVICE FOR USE IN TOOLS USED TO PROCESS MICROELECTRONIC WORKPIECES WITH ONE OR MORE TREATMENT FLUIDS, filed on Jun. 20, 2007.
A cross-sectional view of a spray bar 30 is shown in
The location, direction of the streams and relative force of the streams are selected to preferably provide a directional flow of the resulting liquid aerosol droplets, so that the droplets are directed to the surface of a substrate to effect the desired particle removal. In one embodiment, the liquid aerosol droplets are caused to contact the surface at an angle that is perpendicular to the surface of the wafer. In another embodiment, the liquid aerosol droplets are caused to contact the surface of the wafer at an angle of from about 10 to less than 90 degrees from the surface of the wafer. In another embodiment, the liquid aerosol droplets are caused to contact the surface of the wafer at an angle of from about 30 to about 60 degrees from the surface of the wafer. In a preferred embodiment, the wafer is spinning at a rate of about 250 to about 1000 RPMs during contact of the aerosol droplets with the surface of the wafer. The direction of the contact of the droplets with the wafer may in one embodiment be aligned with concentric circles about the axis of spin of the wafer, or in another embodiment may be partially or completely oriented away from the axis of rotation of the wafer. System 10 preferably employs suitable control equipment (not shown) to monitor and/or control one or more of fluid flow, fluid pressure, fluid temperature, combinations of these, and the like to obtain the desired process parameters in carrying out the particular process objectives to be achieved.
The present method may be utilized at any stage of a substrate processing protocol, including prior to or between various treatment steps such as cleaning, masking, etching and other processing steps where removal of particles is desired. In a preferred embodiment of the present invention, the present method using aerosol droplets as described is part of a cleaning step prior to a final rinsing step.
After completion of the particle removal step as described herein, the substrate is preferably rinsed and also subjected to a drying step, which drying step comprises at least a continuation of the rotation of the microelectronic device after rinse fluid dispense is terminated for a determined time period to sling rinse fluid from the device surface. Delivery of drying gas, such as nitrogen that may or may not be heated, is also preferred during a drying step. The drying step is preferably continued for as long as necessary to render the substrate surface sufficiently dry to achieve satisfactory product at desired final contamination levels based upon any particular application. With hydrophilic surfaces, a measurable thin liquid film may still be present on some or all of a device surface. The drying step may be performed with the microelectronic device rotated at the same or at different revolutions per minute as the rinsing step.
Six silicon nitride particle challenged wafers were cleaned with a liquid deionized water aerosol process using a single wafer spin module in a aerosol created by impinging DI water at a flow rate of (1 LPM) with dry N2 gas stream at a flow rate of 120 slm. Five particle challenged wafers were cleaned with the same aerosol process where the aerosol was created by impinging DI water at a flow rate of (1 LPM) with a 1% IPA/N2 gas stream at a flow rate of 120 slm. All of the wafers were processed within about a 15 minute time frame. Particle measurements were made for sizes greater than 65 nm using a KLA-Tencor SP1/TBI measurement tool. Particle removal efficiency was improved from an average of 61.7% with dry N2 to an average of 66.8% with 1% IPA vapor in N2.
In this example, 200 mm wafers were contaminated with silicon nitride particles by spin deposition and then allowed to sit at ambient conditions to “age” for 24 hours. Five silicon nitride particle challenged wafers were cleaned with a liquid deionized water aerosol process using a single wafer spin module in a aerosol created by impinging DI water at a flow rate of 1 LPM with dry N2 gas stream at a flow rate of 200 slm. Six particle challenged wafers were cleaned with the same aerosol process where the aerosol was created by impinging DI water at a flow rate of 1 LPM with a 3% IPA/N2 gas stream at a flow rate of 200 slm. Particle removal efficiency reported in Table 1 is the average across the wafers run under each condition.
All patents, patent applications (including provisional applications), and publications cited herein are incorporated by reference as if individually incorporated. Unless otherwise indicated, all parts and percentages are by volume and all molecular weights are weight average molecular weights. The foregoing detailed description has been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described, for variations obvious to one skilled in the art will be included within the invention defined by the claims.
This application claims the benefit of U.S. Provisional Application Ser. No. 60/819,179, filed Jul. 7, 2006, entitled “LIQUID AEROSOL PARTICLE REMOVAL METHOD” which application is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60819179 | Jul 2006 | US |
