Contamination analysis unit and method thereof, and reticle cleaning system

A contamination analysis unit and method for inspecting pollutants remaining on a target side of an inspection object such as a reticle after cleaning the object is provided. After steeping the target side in a solution, a sampling liquid may be abstracted therefrom after a predetermined time and may be analyzed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application claims priority under 35 U.S.C. §119 of Korean Patent Application No. 10-2007-0016070 filed on Feb. 15, 2007, the disclosure of which is incorporated herein by reference in its entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to systems and methods for manufacturing substrates. More particularly, the present invention relates to a contamination analysis unit and method for inspecting pollutants remaining on the surface of a cleaned reticle, and a reticle cleaning system.

Semiconductor devices are fabricated by way of plural processes such as ion implantation, deposition, diffusion, photolithography, etching, and so forth. Among those processing steps, photolithography is used for shaping designed patterns on a wafer. Photolithography is carried out by conducting the steps of coating a photoresist film on a wafer, exposing the wafer by transcribing the mask pattern into the photoresist film on the wafer, and then developing the pattern on the wafer by removing the photoresist film from specific regions thereon.

In the exposing step, a reticle is used as a mask that has a circuit pattern. During the exposing step, a pellicle (i.e., a thin and transparent film) is adhered to the reticle in order to protect the surface of the reticle from pollutants such as floating particles. The reticle is cleaned of pollutants at various periods of time. Often a first pellicle is removed from the reticle to clean the reticle and a new pellicle is then adhered to the reticle after cleaning the reticle.

With an increase of integration density in semiconductor devices, the reliability and yield thereof becomes lower due to pollutants on the molecular level that have not previously been considered as troublesome contamination. This is a particular concern when conducting the exposing step under the condition that various pollutants, e.g., ammoniums (NH3), sulfuric acids (SOx), or organic substances, remain on the reticle. Light irradiation of the reticle can induce optical reactions of the pollutants, and a haze on the surface of the reticle results. This degrades transmissivity of the reticle, and may result in detrimental critical dimension or pattern bridging effects on a pattern formed by the photoresist film.

To prevent these problems related to the reticle, one usually analyzes contamination on the surface of the reticle, on which light is irradiated, (hereinafter, referred to as the ‘target side’) after cleaning the reticle. Generally, a unit for cleaning the reticle and a unit for analyzing contamination of the reticle are provided at respective independent stations. After cleaning the reticle by a reticle cleaning system, an operator requests contamination analysis of the reticle from the contamination analysis station and then is informed of an analyzed result. Thus, it can take significant time for the operator to be informed of the analyzed result after cleaning the reticle, so that a number of reticles must be prepared in order to enhance the rate of operation of an exposing unit.

In the meantime, the contamination analysis to the reticle surface is generally carried out such that the target side of the reticle is placed face upward and a small amount of deionized water at room temperature is supplied to the target side. After a predetermined time when the deionized water is supplied, the deionized water on the target side of the reticle is delivered to an analysis unit such as a high-performance ion chromatography (HPIC) analyzer for examining contamination.

SUMMARY OF THE INVENTION

The present invention is directed to a contamination analysis unit and method capable of improving inspection reliability in analyzing pollutants remaining on a target side of a reticle after cleaning the reticle.

The present invention is also directed to a contamination analysis unit and method capable of shortening the time for analyzing pollutants remaining on a target side of a reticle after cleaning the reticle.

The present invention is further directed to a reticle cleaning system and method capable of improving reliability in cleaning a reticle and improving process efficiency in semiconductor fabrication exposing processes.

According to an embodiment of the invention, there may be provided a contamination analysis unit for inspecting pollutants on a target side of an inspection object. The unit may comprise a sampling module abstracting a sampling liquid by contacting the target side of the inspection object with a solution and an analyzer configured to analyze pollutants from the sampling liquid. The sampling module may include a liquid tub having a containing space that accommodates the target side of the inspection object while in the solution and a liquid supply nozzle configured to supply the solution into the containing space of the liquid tub.

The sampling module may further comprise a chamber providing a space that is isolated from the external environment. The chamber may include a housing with a side having a path through which the inspection object is introduced and a door opening and closing the path.

The sampling module may further include a purge gas supplying member configured to supply a purge gas into the chamber.

The sampling module may further include a heating member configured to heat the solution accommodated in the containing space. The sampling module may further include a temperature detecting member sensing temperature of the solution accommodated in the containing space.

According to one embodiment, the containing space may have a groove formed at the upper side of the liquid tub, and the door may be placed on the top of the housing, opposite to the containing space.

The liquid tub may include stay projections supporting the inspection object in the containing space so as to isolate the target side of the inspection object from the bottom of the containing space.

The sampling module may further include a liquid supply pipe providing the solution to the liquid supply nozzle and a valve installed in the liquid supply pipe which may open and close an internal path.

In addition, the sampling module may further include an exhaust pipe connecting the containing space to the analyzer so as to deliver the abstracted sampling liquid to the analyzer.

According to another embodiment, the sampling module may be shaped to abstract or collect the sampling liquid from a reticle that is used in a semiconductor process as the inspection object.

The present invention also provides a method for analyzing contamination in a target side of an inspection object that may be carried out by obtaining a sampling liquid by steeping or soaking for a period of time the target side of the inspection object in the liquid tub solution, and analyzing contamination through inspecting the sampling liquid.

According to an embodiment, the method may comprise filling the solution in a containing space formed on the top of the liquid tub and steeping the target side of the inspection object in the solution after facing the target side of the inspection object toward the liquid tub solution, so that the side opposite that of the target side is apart from and not in contact with the solution.

The target side of the inspection object may contact with the solution in a space airtight to the external environment, and a purge gas may spread in the space while the inspection object is accessing the space.

According to another embodiment, the target side of the inspection object may be steeped into a heated solution. The solution may be heated while the target side of the inspection object is steeping in the solution.

In addition, an opening time of a valve installed in a liquid supply pipe for supplying the solution into the containing space may be regulated by a controller so as to provide an uniform amount of the solution filling the containing space.

Another embodiment of the present invention may be a reticle cleaning system. The system may be comprised of a cleaning apparatus configured to clean a reticle and a contamination analysis unit configured to inspect pollutants remaining on a target side of the reticle that has been washed by the cleaning apparatus. The contamination analysis unit may include a chamber; a liquid tub provided in the chamber, including a containing space accommodating the target side of the reticle; a liquid supply nozzle configured to supply a solution into the containing space of the liquid tub; and an analyzer configured to analyze pollutants from a sampling liquid obtained by steeping the target side of the reticle in the solution.

The chamber may include a housing including the liquid tub, a path for the reticle; and a door for opening and closing the path. The contamination analysis unit may further include a purge gas supplying member configured to supply a purge gas into the chamber.

The contamination analysis unit may further include a heating member configured to heat the solution in the containing space.

According to another embodiment, the contamination analysis unit may further include a liquid supply pipe configured to supply the solution to the liquid supply nozzle and a valve installed in the liquid supply pipe; the valve opening and closing an internal path. The system may further include a controller operating to control an opening time of the valve.

According to another embodiment, the system may further include a controller for receiving an analyzed result from the analyzer and for adjusting a recipe of the cleaning apparatus with reference to the analyzed result. The reticle cleaning system may further include an alarm configured to alarm in response to the analyzed result provided from the analyzer.

Still another aspect of the present invention is a reticle cleaning method. This method may be comprised of: cleaning reticles by means of a cleaning apparatus; inspecting pollutants remaining on a target side of a selected reticle; and adjusting a recipe of the cleaning apparatus with reference to a result of the inspection. Inspecting the pollutants may be carried out by steeping the target side of the reticle in a liquid tub, abstracting a sampling liquid from the reticle, and analyzing contamination of the sampling liquid.

The solution may be heated while the target side of the reticle is steeping in the solution.

The reticle may be re-cleaned by the cleaning apparatus if the inspection result is out of a predetermined permissible range. An alarm may be generated if the inspection result is out of the permissible range.

A further understanding of the nature and advantages of the present invention herein may be realized by reference to the remaining portions of the specification and the attached drawings.

DETAILED DESCRIPTION OF THE EMBODIMENTS

It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected or coupled” to another element, there are no intervening elements present. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first layer could be termed a second layer, and, similarly, a second layer could be termed a first layer without departing from the teachings of the disclosure.

In the description, a term “substrate” used herein may include a structure based on a semiconductor, having a semiconductor surface exposed. It should be understood that such a structure may contain silicon, silicon on insulator, silicon on sapphire, doped or undoped silicon, epitaxial layer supported by a semiconductor substrate, or another structure of a semiconductor. And, the semiconductor may be silicon-germanium, germanium, or germanium arsenide, not limited to silicon. In addition, the substrate described hereinafter may be one in which regions, conductive layers, insulation layers, their patterns, and/or junctions are formed.

FIG. 1is a schematic diagram showing a reticle cleaning system1in accordance with an embodiment of the present invention. Referring toFIG. 1, the reticle cleaning system1may be comprised of a cleaning apparatus10, a contamination analysis unit20, and a controller30. The cleaning apparatus10may be operated to clean the reticle70(FIG. 3) wherein a pellicle (not shown) is removed from the surface on which light is irradiated, after the substrate is subjected to an exposing process. After the exposing process, the pellicle is removed from the surface on which light is irradiated. This irradiated surface of the reticle is referred to as a ‘target side’72(FIG. 3). The contamination analysis unit20inspects pollutants on the target side72of the cleaned reticle70. The controller30may receive an inspection result from the contamination analysis unit20and then may adjust a cleaning recipe of the cleaning apparatus10in accordance with the inspection result.

Hereinafter will be described the structures of the members shown inFIG. 1.FIG. 2schematically shows an organization of the cleaning apparatus10shown inFIG. 1. Referring toFIG. 2, the cleaning apparatus10may include a loader12a, a cleaning section13, and an unloader12b. A reticle (not shown) used in a semiconductor fabrication exposing process may be introduced into the cleaning apparatus10by way of the loader12a. After removing pollutants from the surface (i.e., the target side) of the reticle, the pollutants flow out of the cleaning apparatus10through the unloader12b. The cleaning apparatus10may be organized as plural cleaning units14a,14b,16a,16b, and18. The cleaning apparatus10may include the chemical cleaning units14aand14bfor chemically cleaning the reticle70, the rinsing units16aand16bfor rinsing the reticle by deionized water at room temperature or higher, and the dry unit18for drying the reticle. The liquid or solution for cleaning the reticle may be made of ammonia liquor, sulfuric acid, fluoric acid, nitric acid, SC-1 (ammonia-hydrogen peroxide mixture), or SC-2 (hydrochloric acid-hydrogen peroxide mixture). Drying may be carried out by means of isopropyl-alcohol vapor. Each of the units14ato18may be configured for the steeping of the reticle in a solution or rinsing liquid, or for supplying a solution or rinsing liquid to the reticle that is rotating. The units14ato18may be configured to repeat the liquid cleaning and the rinsing in sequence a plurality of times, and the cleaned reticle may be dried.

The contamination analysis unit20may be configured to inspect pollutants remaining on the target side of the reticle that has been cleaned. A reticle is selected from the solution of the cleaned reticles may be transported into the contamination analysis unit20by means of an automatic carrying machine (not shown) or directly by an operator. The contamination analysis unit20may include a sampling module22for abstracting the sampling liquid from the reticle, and an analyzer24for detecting a degree of contamination.

FIG. 3is a sectional diagram schematically illustrating an embodiment of the sampling module22shown inFIG. 1. The sampling module22may comprise a chamber100, a liquid tub200, a heating member400, a temperature detecting member460, a liquid supplying nozzle520, and a purge gas supplying member600. The chamber100may provide a space102airtight to the external environment. The chamber100has a housing120and a door140. The housing120may be configured as a parallelepiped tub. On the top of the housing120, an opening may be provided to permit entrance and exit of the reticle70. The door140may be provided to open and close the opening. The door140may be constructed to be operable by rotation.

The chamber100may include the liquid tub200. The liquid tub200may have a containing space220. For example, the liquid tub200may be shaped in a parallelepiped plate with the top on which a groove may be formed. The groove is provided in the containing space. Thus, the containing space220is formed by a sidewall222and a bottom face224. The reticle70moves downward vertically through the opening in the housing120and the target side72is introduced into the liquid tub200. The liquid tub200may be formed in a size sufficient to accept the target side72of the reticle70. The liquid tub200may be made of quartz or other material that will not contaminate the liquid that is filled in the containing space220. The liquid tub may be supported by a prop260, being isolated from the bottom of the housing120.

Stay projections240extending upward may be placed in order to prevent the target side72of the reticle70, from contacting with the bottom of the containing space220. Stay projections240may be provided and positioned so as to contact the edge of the reticle70. The stay projections240permit the reticle70to be mounted thereon to minimize a contacting area of other faces with the sampling solution and to allow only the target side72of the reticle70to contact the solution. If the other faces contact the solution, inspection reliability to contamination may be degraded because all of the faces are contacting the solution. Each stay projection240may be shaped in a form point-contacting the reticle70. For example, the stay projection240may be shaped in a hemisphere. Locations and shapes of the stay projection are variable in accordance with structural conditions and the selection of location or shape of which will be within the skill of one in the art.

In abstracting a sampling liquid by supplying a solution to the target side72of the reticle70, the inspection reliability could be degraded because the liquid does not contact uniformly with the target side72. But, according to the present invention, by abstracting the sampling liquid in the condition of steeping or soaking the target side72of the reticle70in the solution, the inspection reliability may be improved because the target side72of the reticle70is in uniform contact with the solution.

The liquid tub200may be configured to reduce the amount of solution used so that the amount used may be less than 450 milliliters, and often is less than 100 milliliters.

A liquid supply nozzle520supplies the solution into the containing space220of the liquid tub200. As an example, the liquid supply nozzle520may be disposed to make an inject hole522face toward the edge of the containing space220. The liquid supply nozzle520may be comprised of a supply rod524inclined upward to the top of the liquid tub200from the inner wall of the housing120, and an inject rod522extending downward from the end of the supply rod520. The inject rod522may be positioned so as to not interfere with the reticle70while the reticle70moves into the containing space220.

A liquid supply pipe540may be located out of the housing120, connecting a liquid reservoir to the liquid supply nozzle520so as to flow the solution from the liquid reservoir into the liquid supply nozzle520. The liquid supply nozzle520may include a valve542opening and closing its internal path. Opening and closing the valve542may be carried out by the controller30. The controller30opens the valve542for a predetermined time so as to regulate an amount of the solution to the containing space220at a constant rate. An amount of the solution supplied into the containing space220may be set to a rate sufficient to have the target side72of the reticle70in the solution, but not to allow a counter face of the target side72of the reticle70to contact the solution. In an embodiment, the amount of solution may be optimized to be as small as possible so as to not contact the side or part of the reticle70not steeped in the solution.FIG. 4illustrates an embodiment wherein the reticle70is steeped in the solution.

Different from the aforementioned, the supply of the solution to the containing space220may be manually carried out by an operator. But, this manual supply may cause variation in an amount of the solution, degrading the inspection reliability. Therefore, in one embodiment, an opening time of the valve542by the controller30may be controlled so as to provide an uniform amount of the solution supplied into the containing space220.

The heating member400may heat the solution that is in contact with the target side72of the reticle70. As an example, the heating member400may be configured to continuously heat the solution while the target side72of the reticle70is in contact with the solution. The heating member may be comprised of a heating plate420placed under the liquid tub200and a heating line440inserted in the plate420. Otherwise, the heating line400may be inserted in the liquid tub200.

On the bottom of the containing space220may be set a temperature detecting member460. The temperature detecting member460continuously senses temperature of the solution and a sensed value of temperature is transferred to the controller30. The controller30may be able to control a rate of power supplied to the heating member440with reference to the sensed value of temperature.

In abstracting a sampling liquid by contacting the solution room temperature with the target side72of the reticle70, it may be desirable to have a sufficient length of time of contacting the reticle70with the solution so as to make pollutants of the target side72fully contained in the sampling solution (e.g., deionized water). But, as aforementioned, even with a relatively short time in contacting the target side72of the reticle70to the heated solution, the pollutants of the target side72may be sufficiently contained in the solution. According to an experiment, in the inspection reliability, a case that the target side72of the reticle70contacts with the solution at about 90° C. for 30 minutes is much better than a case that the target side72of the reticle70contacts with the solution at about room temperature for 1 hour.

While this embodiment is described about the structure with the heating member400installed in the liquid tub200, the location and kind of the heating member400may be modified or altered in various forms as will be within the skill of one in the art.

The heating member400may have a heater installed on the liquid supply pipe540. In this case, it may be necessary to lengthen a time of contacting the target side72of the reticle70to the solution, in order to obtain the desired inspection reliability, because the temperature of the solution is lowered over time. Thus, in one embodiment, the solution may be continuously heated while the target side72of the reticle70is in contact with the solution.

The purge gas supplying member600may supply a purge gas into the chamber100. The purge gas supplying member600may be comprised of a gas jet nozzle620and a gas supply pipe640. The purge gas may be nitrogen or an inert gas such as helium, neon, argon, krypton, and xenon. The gas jet nozzle620may be located at the upper side of the chamber100. The gas supply pipe640may be placed out of the chamber100, supplying the purge gas through the gas jet nozzle620. The gas supply pipe640may include a valve642, operated by the controller30. The purge gas may be jetted into the chamber100while the reticle70comes in and exits out of the chamber100through the door140. The purge gas in one embodiment may be continuously supplied into the chamber even while the reticle70is in contact with the solution. The purge gas acts to minimize an inflow amount of external air into the chamber100and exhausts remaining air out of the chamber100. An exhaust pipe160may be connected to the bottom or to the side of the housing120.

By steeping the reticle70in the solution for a predetermined time, a sampling liquid that contains the pollutants from the target side72of the reticle70may be obtained. The reticle70may be removed from the containing space220and the sampling liquid is delivered to the analyzer24. The liquid tub200may be configured in a structure separable from the chamber100. For example, the liquid tub200may be mounted in the heating member400or the prop260, fixed to the heating member400or the prop260by means of a jointing member (not shown). In this case, with the sampling liquid, the operator separates the liquid tub200from the chamber100and provides the sampling liquid to the analyzer24.

Selectively, as shown inFIG. 5, the liquid tub200may also be connected to a liquid outflow pipe700. The liquid outflow pipe700may be provided to supply the sampling liquid into the analyzer24. The liquid outflow pipe700may include a valve720opening and closing its internal path. The valve720may be operated by the controller30.

The analyzer24detects pollutants such as ammonium (NH3), sulfuric oxide (SOx), and various organic substances. The analyzer24may be an HPIC analyzer, such as those known to one skilled in the art.

A result of inspection by the analyzer24may be transferred to the controller30. If the inspection result informs that concentration of contamination is within a permissible range, the controller30may provide the reticle70to the semiconductor fabrication exposing apparatus (not shown) and the fabrication exposing process may be kept going. Otherwise, if the concentration of contamination is out of the permissible range, an alarm40may inform the operator of that contamination. Additionally, the controller30may operate to control migration of the reticle70so as to re-clean the reticle70if necessary. The controller30may be able to correct a cleaning recipe, e.g., an amount or concentration of cleaning liquid or a cleaning time.

In the above description, it is described such that the operator controls the entrance and exit of the reticle70in and out of the sampling module22. But, it is also possible to provide an automatic mechanism (not shown) including a robot automatically controlling movement of the reticle70, such as the entrance/exit into/from the sampling module22, and transportation by the cleaning apparatus10and the sampling module22.

Hereinafter will be described a method of cleaning the reticle70in conjunction withFIGS. 6 through 15.FIG. 6is a flow chart showing a procedure of cleaning the reticle andFIG. 7is a flow chart of the reticle inspecting procedure shown inFIG. 6.FIGS. 8 through 15are sectional diagrams sequentially illustrating the reticle inspecting procedure. Among the valves162,542, and642, the unshaded valves denote that their corresponding paths are open, while the shaded valves denote that their corresponding paths are closed.

The reticles treated by the exposing apparatus may be transported into the cleaning apparatus. The reticle may be cleaned while passing through the units of the cleaning apparatus (step S100). After cleaning the reticle by chemical means, a step of rinsing the reticle by deionized water may be repeated a plurality of times and in the last step the reticle may be dried.

Once pluralities of the reticles are cleaned, one of the reticles may be put into the inspection to find whether it has been successfully cleaned to a required level (step S200). As shown inFIG. 8, first, the solution (deionized water) may fill the containing space220of the liquid tub200placed in the sampling module22(step S210). The solution may be supplied to the containing space220by way of the liquid supply nozzle520. The controller30may adjust an opening time of the valve542so as to supply the solution to the containing space220in a predetermined amount.

Then, referring toFIG. 9, the solution filling the containing space220may be heated to a predetermined temperature (step S220). As an example, the predetermined temperature may be about 90° C.

Next, referring toFIG. 10, a purge gas may be supplied into the chamber100through the gas supply nozzle620(step S230). The supply of the purge gas may precede the supply or heating of the solution.

Thereafter, referring toFIG. 11, the upper side of the housing120may be opened by the door140of the chamber100and the reticle90may be introduced into the chamber100(step S240). The reticle70moves down vertically with the target side72facing downward, being laid on the stay projections240of the containing space220. The movement of the reticle70may be conducted by the operator or a carrying robot.

Then, as illustrated inFIG. 12, the target side72of the reticle70may be steeped in the solution for a predetermined time (step S250). For example, the predetermined time may be about 30 minutes. While the reticle70is being steeped in the solution, the solution may be continuously heated to maintain the predetermined temperature.

After the predetermined time, referring toFIG. 13, the top of the housing is opened by the door140of the chamber100and the reticle70is drawn out of the chamber100(step S260). The purge gas supply as shown inFIG. 10may still be carried out without interruption.

Next, as illustrated inFIG. 14, the sampling liquid remaining in the containing space220may be provided to the analyzer24(step S270). By using the sampling module shown inFIG. 3, the operator may be able to manually supply the sampling liquid to the analyzer24after separating the liquid tub200from the chamber100. By using the sampling module shown inFIG. 5, the sampling liquid may be supplied into the analyzer24by way of the outflow pipe700connected to the liquid tub200.

Referring toFIG. 15, after closing the door140of the chamber100, the purge gas may be supplied into the chamber100and a cleaning solution may be supplied to clean the inside of the sampling module (step S280). The purge gas and the cleaning solution are discharged out of the chamber100through the exhaust pipe160. The cleaning solution may be supplied through the liquid supply nozzle520, or another nozzle different from the liquid supply nozzle520, into the containing space220of the liquid tub200.

The analyzer24may inspect concentration of contamination from the sampling liquid and results of the inspection may be transferred to the controller30(step S300). The controller30may transport the reticle70to the exposing apparatus if the concentration of contamination is within a permissible range (step S400). If concentration of contamination is out of the permissible range, the controller30may generate an alarm and the reticle may be transported back into the cleaning apparatus10and then re-cleaned. During this, the controller30may be able to correct the recipe of the cleaning apparatus10(step S500).

According to some embodiments of the present invention, the inspection reliability in analyzing pollutants remaining on the target side of an object to be inspected, such a reticle, after cleaning the reticle may be improved.

Further, according to embodiments of the present invention, inspection reliability may be improved by minimizing an area of contact of the other faces, except for the target side of the reticle.

Further, according to embodiments of the present invention, inspection reliability may be improved by abstracting the sampling liquid while steeping the target side of the reticle in the solution.

Further, according to embodiments of the present invention, the time for analyzing pollutants that remain on the target side of the reticle after cleaning the reticle may be reduced.

Moreover, since the reticle is re-cleaned or the cleaning recipe is corrected unless the reticle has not been cleaned to the desired level, embodiments of the present invention assure high reliability in cleaning the reticle.