KR101431506B1 - Stripping and removal of organic-containing materials from electronic device substrate surfaces - Google Patents

Abstract

Described herein are methods of removing organic-containing materials from exposed surfaces of large substrates (greater than 0.25 m ² ). The substrate may comprise an electronic device. The exposed surface is treated with a stripping solution containing ozone (O ₃ ) in a solvent containing acetic anhydride. The stripping solvent used to form the stripping solution may comprise a mixture of acetic anhydride and a co-solvent selected from the group consisting of carbonates containing from 2 to 4 carbons, ethylene glycol diacetate, and combinations thereof. In some cases, the stripping solution may contain only acetic anhydride and ozone, wherein the ozone concentration is typically about 300 ppm or more.

Description

STRIPPING AND REMOVAL OF ORGANIC-CONTAINING MATERIALS FROM ELECTRONIC DEVICE SUBSTRATE SURFACES BACKGROUND OF THE INVENTION [0001]

Field of invention

The present invention relates to a method of forming an organic-containing material, such as a photoresist, a high temperature organic layer, or an organic layer, from a substrate surface of a planar panel display or a solar cell array or other large scale substrate (typically a substrate larger than about 0.5 mx 0.5 m) And a method for removing organic dielectric material.

A brief description of the background technology

The information in this background section of the present disclosure is provided to enable the reader of the present invention to understand the present invention described below. The presence of the information in this background section of the present application does not acknowledge that the presented information or a combination of the presented information is prior art to the present invention.

The fabrication of electronic device structures is complicated by the number of different materials used to provide the elements of the functional device and as temporary processing structures during fabrication of the device. Since most devices involve the formation of interrelated complex and patterned structure layers, photoresist is used during patterning of the underlying material layer over a large surface area (typically about 0.25 m ² or more) And high temperature organic masking material are generally used. The patterned photoresist is one of the temporary processing structures and must be removed once the work on the underlying structure through the holes in the photoresist is complete. Thus, there is a need for an efficient and inexpensive method of removing, stripping, or cleaning organic photoresist as well as other organic layer residues from large substrate surfaces. For example, due to the various compositions of the substrate underlying the photoresist, it is important that the method used to remove the photoresist is not reactive (corrosive thereto) with the underlying surface of the photoresist. One problem was the presence of metallic materials and the tendency of these materials to oxidize and dissolve the oxidized layer.

In order to be useful in processing large surface areas, it is helpful to make the stripping and cleaning material a non-corrosive fluid. The fluid should be minimally affected by the presence of ambient atmospheric conditions. It is also useful when the removal process can be carried out at room temperature, or at least below about < RTI ID = 0.0 > 80 C. < / RTI > Finally, it is always desirable that the fluid used to remove the organic material is environmentally friendly.

BACKGROUND ART [0002] Various techniques have been used to strip organic materials, e.g., photoresists, for example, and in particular to strip photoresist from a large substrate surface. Representative techniques for removing photoresist as well as their advantages and disadvantages are described below.

Typically, a Piranha solution consisting of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide (H ₂ O ₂ ) at a volume ratio of 4: 1 works well for photoresist removal, but on the substrate surface containing the exposed metal Can not be used because such a solution will etch the metal. Further, since the pyran solution is very viscous, it is difficult to clean the substrate surface after the photoresist removal process. In addition, the H ₂ SO ₄ / H ₂ O ₂ solution can not be recovered or reused many times, because it is rapidly degraded. Finally, the solution should be applied at a relatively high temperature of 70 캜 or higher, typically about 120 캜.

Some other techniques for removal of organic photoresists include organic solvent-based stnppers such as monoethanolamine (MEA), dimethylsulfoxide (DMSO), n-methylpyrrolidone (NMP ), Propylene glycol monomethyl ether acetate (PGMEA), ethyl lactate, and methyl ethyl ketone (MEK). Unlike pyranic solutions, these organic solvent strippers can also be used in the presence of metals. However, these organic solvent strippers can not be easily recovered after saturation with the dissolved photoresist, because it is difficult for the photoresist to separate from the organic solvent. Thus, the saturated organic solvent stripper must be recycled for recycling, either by causing environmental problems, or by using cumbersome and costly distillation techniques. As with pyranate solutions, these solvents are typically heated prior to use, but at a somewhat lower temperature than the piranha solution, typically to about 50 ° C to 65 ° C.

Tanno et al., Japanese Patent Publication No. 59125760, published on Jan. 10, 1986, discloses a method of dissolving ozone in an organic acid (such as formic acid or acetic acid) and removing contaminants from the semiconductor substrate using ozonated organic acid . Any heavy metal on the wafer has been described as forming a formate or acetate and any organic contaminants can be decomposed by ozone to remove stains on the substrate surface.

tea. In a paper titled "Native Oxide Growth and Organic Impurity Removal on Si Surface with Ozone-Injected Ultrapure Water" (J. Electrochem. Soc, Vol. 140, No. 3, March 1993), T. Ohmi et al. Describes the use of ozone-infused ultra-pure water to remove organic impurities absorbed from the wafer surface before other wafer cleaning processes outside. The ozone concentration in water was 1 to 2 ppm. The process described by Omi et al. Is described as being capable of effectively removing organic contaminants from the wafer surface within a short time at room temperature. The processing of waste from the process has been described as being simple and the chemical composition of the ozone-injected ultra-pure water is described as being easily manageable.

U.S. Patent No. 5,464,480, issued November 7, 1995 to Matthews et al. Entitled " Process and Apparatus for Semiconductor Wafers in a Fluid " Discloses a method for removing organic materials from a semiconductor wafer using the same. The amount of ozone dissolved in water is temperature dependent. Lowering the water temperature has been shown to increase the concentration of ozone in water and to increase the photoresist strip ratio with ozone / cooled water solution.

U.S. Patent No. 5,632,847 issued to Ohno et al. On May 27, 1997, entitled " Film Removing Method and Film Removing Agent ", discloses that ozone is dissolved in a mineral acid aqueous solution (e.g., a mixed solution of dilute HF and dilute HCl (E.g., organic or metal contaminated film) from the substrate surface by injecting ozone into the substrate and directly contacting the film with a bubble formed by the ozone injection. Each bubble is described as consisting of an internal ozone bubble and an external acid aqueous solution bubble. Ohno et al. Recommend an aqueous acid solution of 5 wt% or less maintained at room temperature with an ozone concentration in the range of 40,000 ppm to 90,000 ppm. Ozone is also dissolved in sulfuric acid for use in cleaning semiconductor surfaces, for example, as described in U.S. Patent Nos. 4,917,123 and 5,082,518.

U.S. Patent No. 5,690,747, issued to Doscher on Nov. 25, 1997, entitled " Method for Removing Photoresist with Solvent and Ultrasonic Agitation, " Describes a method for removing photoresist using a liquid organic solvent comprising at least one polar compound having at least one alicyclic carbonate (e.g., ethylene carbonate).

European Patent Publication No. 0867924 of Stefan DeGendt et al., Entitled " Method for Removing Organic Contaminants from a Substrate ", issued September 30, 1998, , And an additive that acts as a scavenger. The use of liquid agents including water, ozone and additives acting as scavengers is also discussed. It is recommended that the additive is an OH radical scavenger such as a carboxylic acid or phosphoric acid or a salt thereof. Preferred examples are acetic acid and acetate, as well as carbonate and phosphate. Although a carboxylic acid as a whole is mentioned, there is no data for any carboxylic acid other than acetic acid. The inventors describe how the ozone level of the aqueous ozone solution increases when acetic acid is added to the aqueous solution. They also disclose that the photoresist strip ratio increases when acetic acid is added to aqueous ozone solutions. These publications are incorporated by reference in their entirety.

U. S. Patent No. 6,080, 531, entitled " Organic Removal Process ", issued June 27, 2000 to Carter et al., Describes a photoresist removal method wherein ozone and bicarbonate (or other suitable radical Scavenger) is used to treat the substrate for use in an electronic device. The concentration of bicarbonate ion or carbonate ion in the treatment solution is described to be substantially equal to or greater than the ozone concentration. Such methods have been described as being suitable for the removal of photoresist (as well as other organic materials) where metals, such as aluminum, copper and their oxides, are present on the substrate surface.

Lt; / RTI > published by Seiko Epson Corp. on Jan. 25, 2002; And Sumitomo Precision Prod. Japanese Patent Publication No. 2002/025971, which is assigned to Koch Co., teaches the use of ozonated water and ultraviolet radiation containing acetic acid to remove photoresist. The ozonated water containing acetic acid is continuously supplied to the center portion of the rotating substrate. UV light from a UV lamp is irradiated onto the substrate to remove the resist attached to the surface of the substrate. The process is described as removing organic material, e.g., resist, that is deposited on the substrate without the need for high temperature heat treatment.

U.S. Patent Application Publication No. 2002/0066717 A1 to Verhaverbeke et al., Entitled " Apparatus for Providing Ozone Process Fluid and Methods for Using Same ", issued Jun. 6, 2002, Lt; RTI ID = 0.0 > and / or < / RTI > Berhaberke et al. Teach that it is desirable to have as high an ozone concentration as possible in order to achieve rapid cleaning of electronic components. Berhaberbeck et al. Achieved an ozone concentration in water of up to 300 g / m ³ by using a closed vessel containing recycled ozonated liquid supplied under pressure. Berhberbeck et al. Describe the use of various chemically reactive process fluids that can be used with ozone, including inorganic acids, inorganic bases, fluorinated compounds, and acetic acid. The above-mentioned publications, such as Berhaberbeck, also provide an overview of the literature on the use of ozonated deionized water to remove photoresist from electronic component surfaces. Such open patent applications are hereby incorporated by reference in their entirety.

United States Patent Publication No. 2002/0173156 A1 to Yates et al., Published November 21, 2002, entitled " Removal of Organic Material in Integrated Circuit Fabrication Using Ozonated Organic Acid Solutions " Describes the use of organic acid components that increase the solubility of ozone in an aqueous solution used to remove organic materials, such as polymer resists or post-etch residues. It is described that each organic acid component is preferably selected for its metal-passivating effect. Such a solution has been described as having significantly lower corrosion rates compared to ozonated aqueous solutions using conventional inorganic acids for ozone solubility enhancement due to the surface passivating effect of organic acid components.

U.S. Patent No. 6,551,409 issued to DeGendt et al. On Apr. 22, 2003, entitled " Method of Removing Organic Contaminants from a Semiconductor Surface ", discloses a tank filled with a gas mixture comprising water vapor and ozone Lt; / RTI > discloses a method of immobilizing semiconductors and removing organic contaminants from such semiconductor surfaces. DeGent et al teaches that the use of gas phase processing to bring the substrate surface into contact with the ozone / water vapor mixture can increase the ozone concentration near the wafer surface.

The title of the invention "Method and Apparatus for Heating a Gas - Solvent Solution" and the shop, issued May 6 date of 2004 show Earth (Boyers), etc. U.S. Patent No. 6,674,054 discloses a gas, a relatively high temperature the solvent solution at a relatively low temperature T ₁ rapidly heated to T ₂ and by gas is described a method of the first higher melting than the dissolved gas concentration is much in the case of T ₂ into the solvent at T _2. An example of a gas-solvent solution is ozone gas in a water solution. The goal is to heat the cooled ozone-water solution using an inline heater just prior to applying the solution to the substrate surface to increase the rate of reaction at the substrate surface. Column A of column 33 shows the solubility of ozone gas in water as a function of temperature and pressure. Such U.S. Patent No. 6,674,054 is incorporated herein by reference in its entirety.

U.S. Patent No. 6,696,228, issued to Muraoka et al. On February 4, 2004, entitled " Method and Apparatus for Removing Organic Films ", discloses a process for removing organic films, For example, a method and an apparatus for removing a resist film are described. The treatment liquid is typically formed from liquid ethylene carbonate, liquid propylene carbonate, or mixtures thereof, and typically contains dissolved ozone. Since ethylene carbonate is a solid at room temperature, such photoresist removal methods require the use of elevated temperatures in the range of about 50 to 120 占 폚.

U.S. Patent No. 6,699,330, entitled " Method of Removing Contamination Adhered to Surfaces and Apparatus Used Therefor, " issued March 2, 2004 to Murataoka, discloses a method for removing surface-deposited contaminants from a substrate for an electronic device . Such methods include contacting the ozone-containing treatment solution with the surface of a treatment target (e.g., a semiconductor substrate) on which the contaminants are deposited. The ozone-containing treatment solution comprises an organic solvent having an ozone partition coefficient of 0.6 or greater, wherein the partition coefficient is an inert gas in the liquid phase in contact with the organic solvent present at the standard temperature and pressure, Indicating the distribution or separation of gaseous ozone between the gases. Any organic solvent has been described as useful in one invention to provide the desired partition coefficient. Preferably, the organic solvent is a fatty acid including acetic acid, propionic acid and butyric acid. Possible examples are provided for acetic acid. Ozonated acetic acid is used in a closed system with a constant ozone partial pressure on the system to maintain high ozone concentrations in acetic acid and minimize evaporation of acetic acid.

Although high ozone concentrations (≥ 200 ppm) can be obtained in acetic acid and ozonated acetic acid can provide rapid photoresist strip rates (≥1 μm / min), the use of ozonized acetic acid for photoresist removal There are major drawbacks. One of the first things to consider is corrosiveness. The presence of acetic acid has been observed to cause corrosion of metals, especially copper and molybdenum. These metals are commonly used in the flat panel display industry. In addition, acetic acid is a solid at temperatures below about 16.7 DEG C, which can cause problems under some desired processing conditions.

In view of the foregoing, there is a need for an improved method of stripping and cleaning organic materials from the surface of an electronic device, particularly from such electronic device surfaces when metal is present. In particular, there is a need for a stripping and cleaning method that has universal applicability in relation to the surface composition of the substrate. Due to the presence of common metals in semiconductor device substrates, flat panel display substrates and solar cell arrays, harmful organic material stripping and cleaning methods in the presence of metals have not been noticed.

In addition, in connection with the fabrication of large flat panel substrates (e.g., those used for AMLCD or AMOLED panels, in some cases solar panels), on a conveyor belt in a stationary object or in an environment vented to the atmosphere There is a need for stripping and cleaning solutions that can be applied to moving objects.

It would also be highly desirable if the stripping and cleaning solution could be reused over multiple processing cycles without the need for frequent replenishment or filtration of the solution. It would also be advantageous if such an improved method of removal of organic material could be performed at room temperature.

SUMMARY OF THE INVENTION

Methods for removing organic-containing materials from exposed surfaces of large substrates (greater than 0.25 m ² ) are described herein. The exposed surface of the substrate may comprise an electronic device. The exposed surface is treated with a stripping solution comprising ozone (O ₃ ) in a solvent, wherein such solvent comprises acetic anhydride. Such a method has a number of advantages including, but not limited to the following: a rapid organic material removal rate of 0.5 [mu] m / min or more, and typically greater than about 2 [mu] m / min is typically obtained. Low corrosion rates associated with metals such as copper, molybdenum and tungsten are observed where the corrosion rate was observed at about 1 nm / min for copper, at 0.6 nm / min for molybdenum, at 0 nm / min for tungsten Respectively. The reagent solution ("stripping solution") used to remove the organo-containing material is designed to avoid or minimize reactivity with the metal to some extent affect the overall electronic performance of the metal after the stripping process. The stripping process can be carried out at room temperature (about 25 캜) if desired. Additionally, the stripping process may be performed in an atmospheric pressure exhausted system if desired in terms of volatility of the stripping solution. The stripping solution can be recycled over multiple processing cycles, making it necessary to refresh for only about 24 hours or more. Further, the stripping solution is easily cleaned from the substrate surface by the water rinse solution.

The stripping solution contains ozone (O ₃ ) in the solvent, wherein such solvent comprises acetic anhydride. The stripping solvent used to form the stripping solution comprises a mixture of acetic anhydride and a co-solvent selected from the group consisting of carbonate, ethylene glycol diacetate and combinations thereof containing from 2 to 4 carbon atoms can do. The carbonate may be selected from the group consisting of ethylene carbonate, propylene carbonate, and combinations thereof. In some instances, the stripping solution may contain only acetic anhydride and ozone, wherein the ozone concentration is typically about 300 ppm or more. When a co-solvent is used, the stripping solution includes acetic anhydride, ozone, and a co-solvent that may be present in a concentration ranging from about 20% to about 80% by volume of the stripping solution. When the co-solvent is a mixture of carbonate and ethylene glycol diacetate, the ratio of carbonate to ethylene glycol diacetate may range from about 1: 1 to about 3: 1.

The method of the present invention can be used to strip organic material from the surface of the substrate without fear that the exposed metal will be detrimental in a manner that substantially affects the performance of the device depending on the performance of the metal.

The concentration of ozone in the stripping solution typically ranges from about 50 ppm to about 600 ppm; More typically from about 100 ppm to about 500 ppm; And often in the range of from about 300 ppm to about 500 ppm. If the stripping solution contains too little ozone, the organic material removal rate will be unacceptably slow. One skilled in the art will be able, with minimal experimentation, to determine an appropriate ozone concentration based on the composition of the substrate surface. Since the solubility of ozone in the acetic anhydride-containing stripping solution increases as the concentration of acetic anhydride increases, the concentration of acetic anhydride in the stripping solution is often as great as possible, depending on the composition of the substrate underlying the organic material being removed. When the stripping solution comprises a co-solvent with acetic anhydride, the co-solvent should not react with acetic anhydride or the substrate underlying the organic material. Particularly well-used co-solvents include ethylene carbonate and ethylene glycol diacetate.

When the stripping solution comprises acetic anhydride with one or more co-solvents of the kind described above, the concentration of ozone in the stripping solution typically ranges from about 50 ppm to about 300 ppm.

Pure acetic anhydride exhibits a vapor pressure of about 500 Pa at 20 < 0 > C. The acetic anhydride-containing stripping solvent typically has a pore size ranging from about 100 Pa to about 600 Pa; More typically, a vapor pressure within the range of about 100 Pa to about 500 Pa.

Acetic anhydride exhibits a vapor pressure of about 1/3 of the vapor pressure of acetic acid at 20 占 폚. As a result, when acetic anhydride is used as a stripping solvent, it smells much lighter than when acetic acid is used as a stripping solvent. The anhydrous stripping solvent may be used in an atmospheric evacuated environment.

Acetic anhydride is liquid at standard temperature (25 占 폚) and standard pressure because acetic anhydride has a melting point of approximately -73 占 폚. As a result, the problem that arises when acetic acid is used as a stripping solvent (acetic acid has a melting point of about 16.7 DEG C under standard pressure) does not occur when acetic anhydride is used as the stripping solvent. Since the solubility of ozone in acetic anhydride is essentially equal to the solubility in acetic acid, there is a clear advantage to using acetic anhydride as the major component in the stripping solvent. The use of acetic anhydride-containing stripping solvents at room temperature is advantageous. When pure acetic anhydride is used as the solvent portion of the stripping solvent, the recommended temperature range for removing organic material from the substrate is in the range of about 15 캜 to about 80 캜. More typically, the stripping temperature will range from about 20 캜 to about 40 캜.

The recommended temperature range is based on a combination of factors including the time required for stripping and cleaning (removing) the organic material and the decomposition rate of the organic material stripped in the stripping solution, the volatility of the stripping solution, and the melting point of the components of the stripping solution do. When the stripping solvent comprises acetic anhydride with one of a carbonate (e.g., ethylene carbonate), ethylene glycol diacetate, or combinations thereof containing from about 20% to about 80% by volume of from 2 to 4 carbons , A typical temperature range for removal of organic materials from the substrate is from about 15 [deg.] C to about 80 [deg.] C. In one exemplary embodiment, the stripping solution comprises about 10% by volume to about 95% by volume of acetic anhydride. In another exemplary embodiment, the stripping solvent comprises about 20% by volume of acetic anhydride, about 40% by volume of ethylene carbonate, and about 40% by volume of ethylene glycol diacetate. One skilled in the art will be able to optimize the stripping temperature range for a particular application after minimal experimentation based on the disclosure herein.

The stripping solution can be reused over a number of processing cycles since the organic compound is decomposed (rather than immediately dissolved) in the substantially ozonated anhydrous stripping solution. The number of cycles in which the stripping solution can be reused will depend on the maximum concentration of organic material residues acceptable to the stripping and cleaning solution. Typically, a production line that strips organic material from a substrate can operate for more than one day without having to refresh the stripping solution.

The addition of carbonate, or ethylene glycol diacetate, or a combination of these co-solvents to the acetic anhydride / ozone stripping solution reduces both the odor of the stripping solution and some of the corrosivity exhibited by the anhydrous-containing stripping solution. However, the solubility of ozone in the stripping solution is reduced by the co-solvent.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, together with the description, serve to explain the principles of the invention. Wherever possible, the same reference numbers are used to indicate the same elements that are common to the figures.
1 is a graph showing the concentration (in mg / L, i.e., ppm) of dissolved ozone as a function of deionized water temperature (in degrees Celsius) when the water surface is in contact with ozone gas in oxygen at a concentration of 240 mg / to be.
Figure 2a shows a schematic diagram of one embodiment of an organic material stripping system of the kind that can be used to process large substrates in relatively open and vented systems. The stripping solution is sprayed onto the substrate surface as the substrate moves along the conveyor.
2B is a schematic diagram illustrating an interior view of the closed stripping region 204 of FIG. 2A through which a large flat panel display substrate, e.g., a glass-containing substrate 210, passes below the overhead stripping solution supply conduit 213. FIG. to be. The stripping solution is applied by a spray 215 from a spray nozzle 214.
FIG. 3 is a schematic diagram of an exemplary stripping solution production system 300 in which the anhydride-containing solvent is ozonized to provide an ozonated anhydrous-containing stripping solution.
Figure 4a illustrates a bubbler device (not shown) that can be used to produce a vaporous ozonated anhydrous-containing stripping solution from a liquid ozonated anhydrous-containing stripping solution of the kind produced by the manufacturing system 300 shown in Figure 3. [ FIG.
4B is a schematic diagram illustrating a nozzle 412 that scans across the surface 405 of the substrate 406, which is a rotating wafer. The schematic is a specific method of applying a stripping solution on a substrate surface, wherein the anhydrous-containing stripping solution is present in vapor form 407 as it exits nozzle 412.
4C is a schematic diagram showing a steam distribution plate 430 used in combination with a bubbler 424 to produce a vapor form of the anhydrous-containing stripping solution. The steam distribution plate 430 evenly distributes the stripping vapor 432 over the surface 433 of the substrate 434.
5A is a schematic front view of an alternative specific system 500 for applying a liquid stripping solution or liquid rinse solution to substrate 502 surface 502 to remove stripping solution residues. The liquid is sprayed (508) onto the surface 502 as the substrate 504 passes over the spray applicator 506.
Figure 5b is a schematic side view of the alternative concrete system shown in Figure 5a. The substrate 504 is positioned at a constant angle? From horizontal so that the spray 508 from the spray applicator 506 is pulled toward the bottom of the substrate 504 with gravity help to remove the liquid stripping solution or liquid rinse solution will be.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

As used herein, the singular forms "a "," an "and" the ", as used in the specification and the appended claims, . As used herein, the term " about "refers to a value or range that may include +/- 10% of a particular recited value or range.

Figure 1 shows the concentration of dissolved ozone in deionized (DI) water on the shaft 102 (mg / L, i. E., The concentration of dissolved ozone) on the surface of a deionized (DI) water surface in contact with an ozone gas at a concentration of 240 mg / ppm) as a function of water temperature (DI) shown on axis 104. The solubility of ozone in the deionized water at room temperature (about 25 ° C) is only about 40 mg / L without any difficulty. This requires the use of a cooled (below room temperature) temperature in order to obtain a more useful ozone concentration directly in the stripping solution when a stripping solution of dissolved ozone in DI water is used.

The concentrations of ozone in deionized water, acetic acid, and acetic anhydride solvents are shown in Table 1, wherein the solvent temperature is 19 ° C and the solvent surface is contacted with ozone in oxygen at a concentration of about 240 mg / L at 19 ° C .

The ozone concentration in various solvents at < RTI ID = 0.0 > 19 C & menstruum Dissolved O ₃ concentration (mg / L) DI number 55 Acetic acid 503 Acetic anhydride 503

The concentration of ozone in the aqueous solution can be increased by adding acetic acid to the solution, as described in some publications referred to in the "brief description of the background art" above. Ozone can also be dissolved in pure acetic acid. Ozone dissolved in acetic acid or formic acid can be used to remove organic contaminants and strip the photoresist from the electronic device substrate. However, as discussed above, acetic acid and formic acid are corrosive to metals such as copper and molybdenum, and such metals are used in flat panel display electronic elements. Copper and molybdenum are often present on the surface of the substrate when it is desired to remove organic material from the surface of the substrate.

The use of acetic anhydride solvents other than acetic acid solvents makes it possible to reduce the corrosion of copper and molybdenum by a surprising amount. Table 2 below shows the metal corrosion rates for copper, molybdenum and tungsten when exposed to an ozone stripping solution in acetic acid compared to an ozone stripping solution in acetic anhydride. The concentration of ozone present in each solution is 300 mg / L, the exposure temperature is 20 ° C, and the exposure time period is 1 minute.

ozone In solution  Metal Corrosion Rate ( nm /minute) Stripping solvent Copper corrosion rate
(nm / min) Molybdenum corrosion rate
(nm / min) Tungsten corrosion rate
(nm / min) Acetic acid / ozone 20 4 0 Acetic anhydride / ozone One 0.6 0

Clearly, there is a surprising reduction in the rate of corrosion when the ozonated acetic acid stripping solvent is replaced by an ozonized acetic anhydride stripping solvent. This difference in erosion rate allows for a more complete removal of the organic material on the top while maintaining the performance of the metal-containing device structure exposed on the surface of the substrate over which the organic material is being removed.

Table 3 below illustrates the other important physical property differences between acetic acid and acetic anhydride, indicating that acetic anhydride is the preferred stripping solvent when compared to acetic acid.

Comparison of Physical Properties of Acetic Acid and Acetic Acid Anhydride Physical properties Acetic acid Acetic anhydride Vapor pressure (mmHg at 20 ° C) 11 3.75 Flash point (℃) 40 54 Melting point (캜) 16.7 -73 Boiling point (캜) 118 139

Table 3 shows lower vapor pressures for acetic anhydride. This helps reduce the odor in the workplace due to the presence of stripping solvents. The higher flash point of acetic anhydride reduces the risk of corrosion when acetic anhydride / ozone is used as the stripping solvent. The lower melting point of acetic anhydride ensures that such stripping solvent remains liquid under the conditions in which the stripping solvent is used.

Ozonated acetic anhydride at an ozone concentration of about 300 mg / L when used as a liquid stripping agonist at about 20 < RTI ID = 0.0 > C < / RTI > is removed from the surface of the semiconductor substrate (of the kind used to produce a flat panel display) The photoresist can be removed. Since organic compounds containing photoresist are typically decomposed (rather than directly dissolved) in an ozonated solution containing acetic anhydride, a significant amount of decomposition products volatilize and are easily removed. As a result, the stripping solution can be recycled for reuse over a number of processing cycles. The number of cycles in which the stripping solution can be reused will depend on the maximum concentration of organic material residues acceptable in the stripping and cleaning solution. Distilled or deionized water is frequently used to clean the residual stripping solution from the substrate surface. Depending on the ease of handling in a particular application, other solvents may be used to wash the residual stripping solution, which is not the only cleaning solution for which deionized water can be used.

However, since acetic anhydride is converted to acetic acid when exposed to water, the use of a water rinse liquid to remove the residual ozonated anhydride-containing stripping solution from the semiconductor substrate is easy. The required cleaning time using spray-on cleaning solution is in the range of about 30 seconds; The rinsing can be easily processed to remove dissolved organic material, and if desired, acetic acid is recovered from the wash liquor.

The corrosivity and volatility of the acetic anhydride can be further reduced by mixing the anhydride with another much less corrosive organic solvent. Other non-corrosive organic solvents should not react with ozone and should exhibit higher volatility, typically less than about 30%, than the volatility of acetic anhydride. When mixed with acetic anhydride, a solvent which is non-corrosive to metals, does not react with ozone or reacts hardly, does not react with acetic anhydride, dissolves in acetic anhydride, and is liquid at room temperature is most preferred. Solvents that meet these criteria include (but are not limited to) ethylene carbonate, propylene carbonate, and ethylene glycol diacetate.

Ethylene carbonate is a colorless, odorless solid, having a flash point of 143.7 ° C and a freezing point of 36.4 ° C. In its pure state, ethylene carbonate is a solid at room temperature. Ethylene carbonate is non-reactive to ozone, non-corrosive to metals and compatible with acetic anhydrides.

Similar to ethylene carbonate, propylene carbonate is colorless and odorless. Propylene carbonate is liquid at room temperature. The disadvantage of propylene carbonate is that it is less soluble in water than ethylene carbonate, and thus it is more difficult to clean the residual propylene carbonate from the stripped substrate surface.

Similar to ethylene carbonate and propylene carbonate, ethylene glycol diacetate is colorless and odorless. Ethylene glycol diacetate is liquid at room temperature.

The solubility of ozone in ethylene carbonate or propylene carbonate is significantly less than the solubility of ozone in acetic anhydride (at 20 DEG C, ozone in acetic anhydride is approximately 500 ppm, whereas ozone in ethylene carbonate is approximately 40 ppm). Because of this reduction in ozone solubility, the addition of the carbonate to the stripping solution will only be used if the substrate from which the organic material is being stripped is particularly susceptible to corrosion by the stripping solution.

In order to provide acceptable rates of organic material removal and to maximize corrosion protection, a balance must be made between the concentration of acetic anhydride and the concentration of co-solvent used in the stripping solution. Typically, the carbonate co-solvent containing from 2 to 4 carbon atoms is such that the stripping solvent comprises from about 10% to about 90% by volume of such co-solvent; More typically, the carbonate will comprise from about 20% to about 70% by volume of the stripping solvent; Often, the carbonate is added in an amount that makes up from about 30% to about 40% by volume of the solvent.

The process of the present invention for removing organo-containing materials can be carried out in a simple atmospheric evacuated environment since the solvent comprising the anhydrides alone or in combination with the co-solvents of the type described above, Because it is not particularly volatile at temperatures below that and does not cause discomfort to the smell. Owing to the relatively low volatility of the acetic anhydride and co-solvent referred to herein, the ozonated stripping solution can be sprayed without excessive evaporation and, in most cases, can be applied at room temperature as previously mentioned, Is much lower than the flash point of acetic anhydride.

Ideally, the ozone will completely decompose or oxidize the organic material to CO ₂ or carboxylic acid, and then exhausted through an exhaust system or held in a solvent. However, a small amount of non-oxidizable organic material may remain after the organic material removal process. These non-oxidizable components will eventually begin to increase in the stripping solution containing acetic anhydride and ozone. The solid contaminants remaining in the stripping solution upon recycling can be filtered from the solution. Sometimes it may be necessary for the stripping solution to be refreshed to remove any residue that accumulates (possibly depending on the solvent system, only once a day, or once in a time longer than the day in most cases). The organic residues can be removed by using a "bleed-and-feed" process of a kind known in the art.

The ozonated acetic anhydride-containing stripping solution is very easily removed from the substrate by washing with deionized water, as previously described, because acetic anhydride is converted to acetic acid, which is fully miscible with water. After the organic-containing material removal process, a final treatment with deionized or ozonated deionized water may be used to clean the residual stripping solution. Ozonated deionized water is used only when there is no corrosion problem on the substrate surface. Ozonated deionized water is useful for removing any residual organic material on a substrate surface containing a single carbon-to-carbon bond. In one embodiment of the method, in order to remove organic material from the substrate surface, the substrate surface is first sprayed with a liquid ozonated acetic anhydride-containing stripping solution, then removed to remove any residual organics, and the ozonated stripping The solution is secondly sprayed with liquid ozonated deionized water to clean it. Optionally, a final step of removing residues from the first rinse using deionized water may be used.

In another embodiment of the method of the present invention, the stripping solvent is applied to the substrate surface as a vapor (rather than a liquid). In the case of steam applications, the use of pure acetic anhydride / ozone stripping solution (as opposed to co-solvent use) simplifies the recycling of the stripping solution. It will be appreciated by those skilled in the art that the use of a combination of ingredients will typically cause the vapor concentration to differ from the liquid concentration. Typically, the volatilization temperature of the solvent is in the range of about 20 ° C to about 150 ° C. A solvent vapor is conveyed to contact the substrate such that the organic-containing material is stripped. The solvent vapor can then be condensed on the substrate surface leaving a condensed stripping solvent layer on the substrate surface and then contacting the condensed layer with the ozone gas. The ozone is dissolved into the stripping solvent to form a condensed layer of ozonated acetic anhydride-containing stripping solution, which will remove the organo-containing material.

In another embodiment, in order to deliver the vaporized acetic anhydride-containing solvent to the work surface, ozone gas may be used as the carrier gas. In this example, the stripping solvent is more easily a combination of such components to provide an ozonized stripping solution on the substrate surface as long as the components can be entrained in the ozone carrier gas.

I. DEVICE FOR CARRYING OUT THE INVENTION

Figure 2a shows one device embodiment that can be used to strip organic-containing materials from the surface of a large flat panel of the type used for flat panel display products. The apparatus 200 applies a stripping solvent to the surface of the substrate upon which the organic-containing material is to be removed by spraying. The apparatus illustrated in Figure 2a is useful for processing substrates that can be as wide as a few meters in width and length. The processing environment is open at the entry conveyor location 202 and is evacuated at the area where the stripping solvent is applied, e.g., at the closed stripping area 204. 2A illustrates a stripping region 204 that enters a closed stripping region 204 through a hole 206 in the leading end 208 of a loaded and closed stripping region 204 loaded on an open entry conveyor 202 Device 200 is shown. The substrate enters the closed (and evacuated, not shown) stripping region 204 where stripping solvent (not shown) is applied from the feeder 201 via conduit 203. 2B shows a close-up schematic view of the interior of the closed stripping area 204 where flat panel substrate 210 moves across transport roller 212 while stripping solution 215 is sprayed onto spray nozzles < RTI ID = 0.0 > Is sprayed onto the surface 216 of the substrate 210 through the opening 214. The spray nozzles 214 are arranged so that the entire surface 216 of the substrate 210 is evenly coated with the stripping solution.

After application of the stripping solution 215, the substrate moves into the enclosed region 205, where a cleaning liquid (not shown) is used to clean the residual stripping solvent from the substrate. The rinsing liquid can be applied in a manner similar to that shown for the stripping solvent in Figure 2b. After applying the cleaning liquid to the substrate surface, the substrate moves into the drying zone 207, and in such a drying zone, the substrate is heated by any of the methods known in the art, such as application of airflow across the substrate surface, And dried by other conventional techniques known in the art. After drying the substrate, the substrate is transferred onto the discharge conveyor 209 for further handling.

3 is a schematic diagram of an exemplary apparatus 300 for the preparation of an ozonated acetic anhydride-containing stripping solution. The stripped ozonated acetic anhydride-containing stripping solution may be supplied to, for example, but not limited to, a spray dispenser (e. G., As shown in FIG. 2B). The ozone used for ozonation of the stripping solution containing acetic anhydride, typically will be generated in the ozone generator 304, such ozone generator is oxygen source 302 (source of oxygen can provide an O ₂ or air ). Ozone is produced by applying a silent discharge (a discharge between two electrodes rather than self sustaining) to oxygen or air to produce an ozone containing gas. The ozone-containing gas is supplied to the solution preparation tank 314 through a line 310 which is supplied to a sparger / mixer 316 which supplies ozone to the solution- (Not shown) present in the liquid acetic acid-containing solvent 314. The apparatus 300 for producing an ozonized acetic anhydride-containing stripping solution also includes an acetic anhydride feed system (e.g., but not limited to), such an acetic anhydride feed system comprising acetic anhydride and other co- A solvent (not shown) may be supplied.

In one embodiment, for example, but not limited to, acetic anhydride in liquid form is fed from line 306 to a common line 312, and the co- To a common line 312, which enters a stripping solution supply tank 314. The stripping solution supply tank 314 is connected to the stripping solution supply tank 314, Acetic anhydride from line 306 may be fed to common line 312 and from there into common line 322 and into line 324 if stripping solution supply tank 314 is not full. And such acetic anhydride may be used to feed a stripping apparatus (not shown) in the process using an un-ozonated acetic anhydride stripping solvent. The common line 322 can also be used to drain the residual ozonated acetic anhydride-containing solution from the solution production tank 314 through the discharge line 326. The system may optionally include an additional solvent supply (not shown) for any co-solvent used in combination with the anhydrous stripping solvent (any such solvent may be, for example, but not limited to, A carbonate comprising from 2 to 4 carbons as described above, or ethylene glycol diacetate).

As discussed above, the acetic anhydride-containing stripping solution can alternatively be applied to the substrate surface in vapor form. 4A is a simplified schematic diagram of a bubbler device 400 that may be used to prepare a vaporous acetic anhydride -containing stripping solution and apply it to a substrate 406 surface 405. For example (and without limitation), a solution 403 containing acetic anhydride (and potentially any other solvent mixed with acetic anhydride) in the tank 402 is used to heat the heater 404 . The ozone gas is supplied to the tank 402 through the ozone inlet 408. The vaporous ozonated acetic anhydride-containing stripping solution 407 is supplied to the surface 405 of the substrate 406 through the line 410 and the nozzle 412. The temperature of the vaporous ozone saturated acetic anhydride-containing stripping solution 407 is maintained above the temperature of the wafer 406 surface 405. The ozone-saturated acetic anhydride-containing stripping solution vapor 407 condenses on the cooling surface 405 of the substrate 406. Fresh ozone is continuously introduced into the acetic anhydride-containing solution 403 in the tank 402 to increase the mass transfer of ozone to the substrate surface 405. The layer of stripping solution (not shown) on the substrate surface 405 is very thin, allowing the ozone to diffuse quickly through the layer.

Figure 4B illustrates the application of the vaporous stripping solution 407, in which the application nozzle 412 (e.g., but not limited to, several nozzles may be used) As shown in FIG. The substrate aids in the distribution of a constant feed of ozonated anhydride-containing stripping solvent (not shown) that typically rotates as indicated by arrow 414 in Figure 4a and condenses across the substrate surface 405.

4C is a simplified schematic diagram of another vaporous stripping solvent application apparatus 420 in which ozone is passed through ozone inlet line 422 to one or more anhydrous solvent (and potentially other co-solvent) To the bubbler tank 424. The ozonated solvent present in the bubbler tank 424 is heated by using the heater 426 to produce vapor that is supplied to the distribution plate 430 through the line 428 and the stripping vapor 432 Is dispensed onto a flat panel substrate 434 moving below the distribution plate 430 in a manner shown on a conveyor (not shown). The vapor is condensed on the surface 433 of the substrate 434 to produce condensed stripping solvent 435 on the surface 433 of the substrate 434. One of ordinary skill in the art will appreciate that the substrate 430 could be fixed and the distribution plate 430 could move past the substrate 430.

II. Example

Example  One: Ozonated  From the substrate surface using acetic anhydride Photo Removal of resist

A deep ultra-violet (DUV) photoresist layer sensitive to 248 nm radiation (UV 6 available from Shipley, Marlborough, MA) was deposited on the surface of a single crystal silicon wafer to a thickness of approximately 10,000 Angstroms Thickness. The photoresist was applied using a spin-on process, followed by baking at 95 占 폚 for 30 minutes. The ozonated acetic anhydride (100% acetic anhydride) stripping solution containing about 300 ppm (mg / L) of ozone was applied to a photoresist-coated RTI ID = 0.0 > substrate. ≪ / RTI > The ozonated acetic anhydride was reacted with the photoresist for a period of 30, 60, or 120 seconds and then the substrate surface was cleaned by spraying with deionized water for a period of 10 to 20 seconds.

A series of six substrate samples were tested, with 1 mu m of photoresist present on each substrate, and the exposure time to the stripping solution varied from 30 seconds to about 120 seconds. Following the photoresist stripping procedure, each sample was tested and measured against the remaining photoresist. It has been found that a 1 탆 photoresist has been removed after 30 seconds (or less) from all substrates.

Example  2: for aluminum Ozonated  Corrosivity of acetic anhydride

An aluminum layer was deposited to a thickness of about 10,000 Angstroms on the surface of a single crystal silicon wafer using a physical vapor deposition (PVD) process of the type known in the art. To test the corrosiveness of the ozonated acetic anhydride stripping solution to aluminum, a stripping solution of ozonated acetic anhydride (100% acetic anhydride) containing about 300 ppm (or mg / L) of ozone was dispensed System at room temperature (25 < 0 > C) using a dispensing system such as a system. The ozonated acetic anhydride stripping solution was allowed to react with aluminum for a period of 30, 60, or 120 seconds, and then the substrate surface was cleaned by spraying deionized water for a period of 10 to 20 seconds.

Within the accuracy of our ability to measure, aluminum was not removed by the ozonated acetic anhydride stripping solution. The thickness of the aluminum layer seemed to increase slightly, but the amount of increase was not consistent over time. Increase in the thickness of the aluminum layer can be attributed to the formation of Al ₂ O ₃ layer on the aluminum surface due to exposure to O _3. However, the amount of change in aluminum thickness due to exposure to the stripping solution is very small, less than 0.3%, and can be within the experimental error range of the measurement method. This indicates that there is substantially no corrosion of aluminum over an exposure time of 120 seconds for the stripping solution. In the case of measuring the formation of any significant amount of aluminum oxide, one skilled in the art can use techniques known in the art to remove the oxide to the extent necessary to permit device function in end- Lt; / RTI >

Example  3: For copper surfaces Ozonated  Corrosivity of acetic anhydride

A copper layer was deposited on the surface of a single crystal silicon wafer to a thickness of 8,000 A (800 nm) to 19,000 A (1,900 nm). Copper was deposited using electrochemical plating followed by a physical vapor deposition (PVD) process. In order to test the corrosiveness of the ozonated acetic anhydride stripping solution to copper, ozonated acetic anhydride (100% acetic anhydride) containing ozone at 300 ppm (or mg / L) Using a dispensing system at room temperature (25 < 0 > C) onto the surface of the copper-coated substrate. The ozonated acetic anhydride stripping solution was allowed to react with the copper surface for a period of 30, 60, or 120 seconds, and then the substrate surface was cleaned by spraying with deionized water for a period of 10 to 20 seconds.

Table 4 below shows the thickness of the titanium nitride layer before and after treatment with an ozonized acetic anhydride stripping solution containing 300 ppm (or mg / L) of ozone at room temperature (25 占 폚).

For copper Ozonated Propionic acid  Corrosivity of cleaning solution Sample number Processing time (seconds) Copper thickness before treatment (Å) Copper thickness after treatment (Å) Change in copper layer thickness (Å) 12 30 18,266 18,293 +26 13 60 8,636 8,619 -17 14 120 9,777 9,726 -51

Within the accuracy of our ability to measure, the data in Table 4 show that the thickness of the copper layer is only slightly reduced upon exposure to the ozonated acetic anhydride stripping solution.

While the invention has been described in detail with reference to certain embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. Accordingly, the scope of the present invention should be determined by the appended claims.

Claims (28)

A method of removing an organic-containing material from a surface of a substrate,
Providing a substrate having at least one or more electronic devices formed thereon, the substrate having organic-containing material disposed on a surface;
Removing the organic-containing material by exposing the surface of the substrate to a stripping solution comprising ozone (O ₃ ) in a solvent, wherein the concentration of ozone in the solution is from 50 ppm to 600 ppm and the solvent is acetic anhydride ≪ / RTI > A method of removing an organic-containing material from a surface of a substrate,
Providing a substrate having an organic-containing material disposed on a surface, wherein at least one electronic device is partially or fully formed and comprises an exposed metal;
Removing the organic-containing material by exposing the surface including a metal exposed to a stripping solution comprising ozone (O ₃ ) in a solvent, wherein the concentration of ozone is from 50 ppm to 600 ppm and the solvent is acetic anhydride ≪ / RTI > The method of claim 1 or 2, wherein said solvent comprises acetic anhydride in combination with at least one co-solvent, such co-solvent being miscible with said acetic anhydride and not reacting with said acetic anhydride. The method of claim 1 or 2, wherein the stripping solution comprises, in addition to the acetic anhydride, a co-solvent selected from the group consisting of carbonates containing from 2 to 4 carbons, ethylene glycol diacetate, ≪ / RTI > 5. The process of claim 4, wherein the carbonate is selected from the group consisting of ethylene carbonate, propylene carbonate, and combinations thereof. 4. The process of claim 3, wherein the co-solvent comprises from 20% to 80% by volume of the solvent in the stripping solution. 7. The process of claim 6, wherein the co-solvent contains carbonate and ethylene glycol diacetate, wherein the volume ratio of carbonate to ethylene glycol diacetate ranges from 1: 1 to 3: 1. 8. The method of claim 7, wherein the solvent comprises acetic anhydride in combination with one or more carbonates. 3. The method of claim 1 or 2, wherein the temperature at which the organic-containing material is removed from the substrate is in the range of 15 DEG C to 80 DEG C. 3. The process of claim 2, wherein the acetic anhydride comprises from 10% to 95% by volume of the stripping solution. A method of removing an organic-containing material from a substrate,
Providing a substrate having at least one or more electronic devices formed thereon, the substrate having organic-containing material disposed on a surface;
Vapor solvent and combined to expose the surface of the stripping steam containing ozone (O ₃₎ by Organic comprises removing containing material, the concentration of ozone in the stripping steam 50 ppm to 600 ppm, and wherein the steam St. Wherein the solvent comprises acetic anhydride. delete A method of removing an organic-containing material from a substrate,
Providing a substrate having an organic-containing material disposed on a surface, wherein at least one electronic device is partially or fully formed and comprises an exposed metal;
Removing the organic-containing material by exposing the metal-containing device surface to stripping vapors containing ozone (O ₃ ) in a vaporous solvent, wherein the ozone concentration is from 50 ppm to 600 ppm and the vaporous solvent comprises Acetic anhydride. 14. The method of claim 11 or 13, wherein the vaporous solvent further comprises one or more other vaporable miscible co-solvents, such that the vaporable miscible co-solvent does not react with the acetic anhydride. 15. The process of claim 14, wherein the co-solvent is selected from the group consisting of carbonates containing from 2 to 4 carbons, ethylene glycol diacetate, and combinations thereof. delete delete delete delete delete delete delete delete delete delete delete delete delete

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