KR20070008703A - Compositions and methods for drying patterned wafers during manufacture of integration circuitry products - Google Patents

Abstract

Drying of patterned wafers is achieved in a manner effecting removal of water from the patterned wafers without collapse or deterioration of the pattern structures thereof. The drying is carried out in one aspect of the invention with a composition containing supercritical fluid, and at least one water-reactive agent that chemically reacts with water to form reaction product(s) more soluble in the supercritical fluid than water. Various methodologies are described for use of supercritical fluids to dry patterned wafers, which avoid the (low water solubility) deficiency of supercritical fluids such as supercritical CO2. ® KIPO & WIPO 2007

Description

Compositions and Methods for Drying Patterned Wafers in the Manufacturing of Integrated Circuit Products {Compositions and Methods for Drying Patterned Wafers During Manufacture of Integration Circuitry Products}

background

The present invention relates to compositions and methods for drying patterned wafers in the manufacture of integrated circuit products.

Related Background

In the manufacture of integrated circuit (IC) products, residual liquids such as water, alcohols and the like must be completely removed from the patterned wafer by drying. However, it does not cause collapse of the lithographic pattern shape when the critical dimensions are smaller than about 100 nanometers (nm), but patterned with high aspect ratio trenches and vias. There is a difficulty in removing residual water from the wafer.

For example, in the development of photo-exposed lithography resists, the patterned image is often dried with hexanes and nitrogen, or isopropanol and nitrogen. This conventional drying method does not work well for images with critical dimension widths <100 nm and aspect ratios greater than one. In this particular dimension, the surface tension of isopropanol or hexane pulls the images together, leading to collapse of the lithographic resist and loss of the patterned image, or erosion of the polymer resist.

Accordingly, there is a need in the art for an improved technique for drying patterned wafers that is effective to completely remove water, alcohol, and the like, without causing collapse or other adverse effects of the pattern on the patterned wafers.

Summary of the Invention

The present invention is directed to a composition and methodology for drying patterned wafers for removing water, alcohol, and the like from a wafer without causing a pattern collapse or other adverse effect on the wafer article.

In one aspect, the invention relates to a patterned wafer drying composition for removing water from a patterned wafer, wherein the composition is a supercritical fluid and a reaction product (s) that is more soluble in the supercritical fluid than in the water. At least one water-reactive agent that chemically reacts with water to form.

In another aspect, the present invention relates to a method of drying a patterned wafer for removing water from the patterned wafer, wherein the method is more soluble in the supercritical fluid and in the supercritical fluid than in the water. Contacting with a composition comprising at least one water-reactive agent that chemically reacts with water to form a reactive product (s).

Another aspect of the invention relates to a method of drying a patterned wafer for removing water from the patterned wafer, the method comprising contacting the patterned wafer with a first composition comprising liquid CO ₂ and And then contacting the patterned substrate with a second composition comprising SCCO 2 to perform drying of the patterned substrate without damaging the pattern of the patterned substrate.

Another aspect of the invention relates to a method of drying a patterned wafer for removing water from the patterned wafer, the method comprising (a) a patterned wafer at a pressure of about 1000 psi or higher and a temperature of about 32 ° C. or lower Contacting the first composition comprising an alcohol, (b) contacting the patterned wafer with a second composition comprising an alcohol / CO ₂ solution, and (c) contacting the patterned substrate with SCCO 2. Contacting with the third composition to effect drying of the patterned substrate without damaging the pattern of the patterned substrate.

In other respects, features and implementations of the present invention will become more apparent from the following specification and the appended claims.

Detailed description of the invention and preferred implementation thereof

The present invention is based on the use of a supercritical fluid (SCF) as a cleaning medium for drying patterned wafers in various approaches that avoid problems that are likely to occur incidentally to the use of a supercritical fluid.

Because supercritical fluids have high diffusion rates, low viscosities, near zero surface tension, and good permeability, they are considered as potentially useful media for the drying of patterned wafers, while supercritical CO ₂ Supercritical fluids such as (SCCO2) are non-polar and therefore not useful for drying patterned wafers. For example, if the solubility of water in supercritical CO ₂ is less than 0.1% by weight, the supercritical CO ₂ will be unsuitable for removing residual water on the patterned wafer.

The present invention seeks to overcome the problems that are likely to occur incidentally to the use of supercritical fluids in a drying medium.

Although the present invention has been described below with reference to CO ₂ as an illustrative supercritical fluid species, it does not mean that the application of the present invention is limited thereto, and in the practice of the present invention the supercritical fluids may be of any suitable type. It will be self-evident.

Supercritical fluids are formed under conditions where the liquid phase density of the material is equal to the gas phase density. For example, carbon dioxide (CO ₂ ), a gas at standard temperature and pressure, changes from liquid to SCF above the critical point, corresponding to T _c ≧ 31.1 ° C. and P _c ≧ 72.8 atm. Once formed, the density of the SCF can change from liquid-like to gas-like, with different solvability, by varying the pressure and temperature. Supercritical fluids have liquid and gas phase, density / soluble and diffusivity close to their respective properties. In addition, the surface tension of SCFs is ignored.

Although the present invention may be practiced with any suitable SCF species, with the selection of a particular SCF according to the particular application involved, supercritical CO due to its readily manufactured properties, lack of toxicity and negligible environmental effects. ₂ is the preferred SCF in the broad practice of the present invention. Other preferred SCF species useful in the practice of the present invention include oxygen, argon, krypton, xenon, and ammonia.

In one embodiment, the supercritical fluids comprise a dry composition comprising at least one water-reactive agent that chemically reacts with water in a patterned wafer to form a reaction product species that is more soluble than water in the supercritical fluid. As a drying medium for patterned wafers.

As an example, hexafluoroacetone (HFA) is usefully used as a water-reactive agent in SCCO2 to provide a supercritical fluid composition that has a high effect on the drying of patterned wafers. In the composition, HFA reacts immediately with water and forms soluble and volatile diols quantitatively, as shown in the following reaction.

H ₂ O + CF ₃ COCF ₃ → CH ₃ C (OH) ₂ CF ₃

CH ₃ C (OH) ₂ CF ₃ , ie, the product diol, is highly soluble in SCCO 2 and readily dissolved by the supercritical fluid, resulting from contacting the patterned wafer substrate with the supercritical fluid composition comprising SCCO 2 and HFA. Effectively removes water

More generally, water-reactive preparations in supercritical fluid-based wafer drying compositions include other halogenated aldehydes and ketones; Halogenated diketones, optionally represented by (hfac) H, for example 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (1,1,1, 5,5,5-hexafluoro-2,4 pentanedione); Halogenated esters; Carboxylic anhydrids such as (CH ₃ CO) ₂ O; Siloxanes; And halogenated silanes; And any other compounds or materials that readily react with water and form derivatives that can be dissolved in supercritical CO ₂ or other supercritical fluid species.

In general, water-reactive formulations may be prepared in supercritical fluid compositions at any suitable concentration effective to remove water from the patterned wafer substrate. In various embodiments, the concentration of the water-reactive formulation is determined depending on the particular supercritical fluid species used and is about 0.01% to about 10.0% by weight, based on the total weight of the supercritical fluid and the water-reactive formulation. It is a range, preferably about 0.1% to 7.5% by weight based on the same total weight, more preferably from about 0.1% to about 5.0% by weight based on the same total weight.

  Supercritical fluid drying compositions other than supercritical fluids and water-reactive preparations remove other components other than water from the patterned substrate, such as those needed or desirable for a given application of the drying composition. Co-solvent (s) and active agent (s), surfactant (s), chelating agent (s), etc., other than water-reactive agents.

As used in this context, an "active agent" is used in a cleaning composition or on the surface of a patterned substrate structure to enhance the cleaning and / or removal action of the composition with respect to the composition lacking the material. It is a substance that induces a physical improvement of reaction and / or solubility.

Illustrative co-solvent species include, but are not limited to, xylene, methanol, ethanol, and higher alcohols, N-methyl-, N- N-alkylpyrrolidiones such as octyl- (N-octyl-), or N-phenyl-pyrrolidones, dimethylsulfoxide, sulfolane ), Catechol, ethyl lactate, acetone, methyl ethyl ketone, butyl carbitol, monoethanolamine, butyrol lactone ), Diglycol amine, alkyl ammonium fluoride Γ-butyrolactone butylene carbonate, ethylene carbonate, propylene carbonate, and the like. Can be.

The co-solvent species may be a single component co-solvent or two or more solvent components. The co-solvent can be provided to the supercritical fluid-based dry composition at any suitable concentration, consistent with the solubility of the co-solvent in the supercritical fluid.

Examples of active agents include, but are not limited to, acids, bases, reducing agents, and oxidizing agents. When the reducing agent is solubilized in the supercritical fluid, the reducing agent requires activation by an activation process that includes, for example, activation of thermal, optical, and / or sonic. can do.

Surfactants useful in the dry compositions of the present invention may also be in any suitable form, including anionic, neutral cation, and dipolar ionic forms. Illustrative surfactant species include, but are not limited to, acetylenic alcohols and diols, and long alkyl chains, secondary and tertiary amines.

 Chelating agents useful in the dry compositions of the invention include, for example, polycarboxylic acids such as iminodiacetic acid and lauryl ethylenediamine triacetic acid, 2,4 -Pentanedione (2,4-pentanedione); 1,1,1-trifluoro-2,4-pentanedione (1,1,1-trifluoro-2,4-pentanedion); And β-diketones such as 1,1,1,5,5,5-hexafluoro-2,4-pentadione (1,1,1,5,5,5-hexafluoro-2,4-pentanedion) (β-diketones), substituted dithiocharbanates, malonic acid esters, and polyethylene glycols.

Illustrative species of acids useful in the dry compositions of the present invention include, but are not limited to, perfluorocarboxylic acids, and alkyl or aryl sulfonic acids. . Illustrative species of bases useful in the dry compositions of the present invention include, but are not limited to, amines such as alkyl amines. Oxidizing agents useful in the broad practice of the present invention include, but are not limited to, oxygen, ozone and nitric oxide. Reducing agents usefully employed in the dry compositions of the present invention include, but are not limited to, hydrogen, ammonia, xylenes, hydrides, silanes, alkylsilanes, Hydrazine hydrate or alkyl hydrazine.

Various compositions may be used within the scope of the present invention, wherein the compositions optionally comprise, consist of, or consist essentially of the specifically identified component (s) described herein to be preferred for a given application of the present invention. It can be configured as.

The step of contacting the patterned substrate with the dry composition may be usefully provided depending on the nature and amount of water that other (more or less) contact time is to be removed from the patterned substrate, and the process conditions used for drying. However, it is performed for a suitable time, which may be exemplified in about 20 seconds to about 60 seconds in a specific implementation.

After drying of the patterned substrate, the contact vessel, in which the supercritical fluid-based composition is in contact with the patterned substrate, separates the supercritical fluid composition from the patterned substrate and reclaims the supercritical fluid regenerated from the contact vessel. The high pressure may be reduced to discharge so that non-supercritical component (s), such as soluble water reaction product (s), may be carried in the regasified supercritical fluid and may likewise be removed from the drying site.

The depressurization step may be longer or shorter, depending on the nature of the material to be removed from the patterned substrate and the nature of the process, but may be performed for a suitable time, for example, from 10 seconds to 40 seconds. If desired, repeated cycles of contact and depressurization may be used to achieve sufficiently complete removal of water from the patterned substrate article.

The above-described compositions and methods can be usefully used to clean residual water from small volumes on a semiconductor substrate immediately after the photolithographic image pattern process without the occurrence of pattern collapse.

In another aspect, the present invention seeks to use supercritical fluid-based drying compositions as part of a two-step process to obtain efficient drying without the collapse of the patterned forms. In the drying process, in order to achieve drying of the patterned substrate without damaging the patterned wafer, the first drying step is performed by contacting the liquid CO ₂ with the patterned substrate, and patterning A second drying step is then performed comprising contacting the substrate with the SCCO 2.

In the two-step drying process, the liquid CO ₂ in the first step has a higher density than SCCO ₂ to solvate the water and / or alcohol of the patterned substrate, but only the contacting step drys the patterned substrate. Insufficient to complete the process, a second step of rinsing the patterned substrate is used to achieve effective removal of water and / or alcohol on the substrate.

The advantages of the two-step drying process described above were demonstrated using patterned wafers of the type shown in FIG. 1.

1 is a scanning electron microscope (SEM) photograph of a patterned wafer showing details of the pattern structure, used as a control sample, with respect to FIGS.

In the drying test, the test wafers were each dipped in water for several minutes and then in pure alcohol, after which the wafers were placed in a cleaning chamber for drying.

The first test wafer was air-dried. FIG. 2 is an SEM photograph of the patterned wafer of the type shown in FIG. 1 after the air-drying of the wafer. As shown in FIG. 2, water and alcohol were not completely removed and residual amounts of contaminants resulted in the collapse of the pattern structure.

The second test wafer was dried with liquid CO ₂ . 3 is a SEM photograph of the patterned wafer of the type shown in FIG. 1 after the drying of the wafer with liquid CO ₂ . As shown in FIG. 3, water and alcohol were not completely removed, resulting in the collapse of the pattern structure at the high level of residual amount of contaminants.

The third test wafer includes the first step of contacting the patterned wafer with liquid CO ₂ and after the first contacting step, a second step of contacting the patterned wafer with supercritical CO ₂ , as described above. It was dried in the same two-step process. FIG. 4 is an SEM photograph of the patterned wafer of the type shown in FIG. 1, after the drying of the wafer, first with liquid CO ₂ and then with supercritical CO ₂ . The patterned structure of the wafer was not changed by the two-step drying process, and the pattern remained consistent with the control wafer (compare FIGS. 1 and 4).

The two-step process described above can be carried out under certain suitable process conditions and for any suitable duration in the first and second steps, respectively. In one embodiment, the first liquid CO ₂ contacting step may be performed for about 0.5 minutes to about 20 minutes at a temperature ranging from about 20 ° C. to about 30 ° C., and the second SCCO2 contacting step may be from about 32 ° C. to about 75 ° C. It can be performed for about 0.5 minutes to about 20 minutes at a temperature in the range.

In another embodiment, the present invention seeks to use supercritical fluid-based drying compositions as part of a three step process to achieve effective drying without the collapse of the patterned form.

In the drying process, the patterned substrate is contacted with alcohol at a pressure of at least about 1000 psi and a critical temperature of CO ₂ , i.e., 32 ° C. or lower, for a suitable time, for example, from about 1 minute to about 15 minutes. The first drying step is performed. The alcohol may be a single component alcohol or a mixture of alcohol species, and the alcohol may be recycled in contact with the patterned substrate or contacted in a batch or semibatch form.

The second step is performed after the alcohol contacting step and includes contacting the alcohol / CO ₂ solution with the patterned substrate to remove the alcohol from the first contacting step. The preferred second step is that the alcohol / CO ₂ solution passes through the contact chamber containing the patterned substrate, although the contacting step may be a single-pass or a batch or semi-batch mode of the process. Is performed by recycling. The second step contact may be performed at a temperature in a range of about 22 ° C. to about 31 ° C. for about 0.5 minutes to about 20 minutes. As in the first step, the alcohol can be a single component alcohol or a mixture of alcohol species.

The alcohol used in the first and second contacting steps may be the same or different. The alcohol may be in any suitable form. In one embodiment of the invention, the alcohol is a C ₁ ~ C ₄ alcohol (ie methanol, ethanol, propanol, or butanol), or two or the alcohol species thereof It contains a mixture of the above.

The third step is performed after the alcohol / CO ₂ solution contacting step and includes rinsing the patterned substrate with SCCO 2. The supercritical fluid rinsing step may be performed at a temperature in the range of about 32 ° C. to about 75 ° C. and a pressure in the range of about 80 atm to about 300 atm, for about 0.5 to about 30 minutes. Each of the first and second or third steps is suitably valved for recycling and the same process vessel of a manifolded pipe, if necessary for the delivery of the continuous dry compositions. Can be performed.

Alcohol / CO ₂ solutions are prepared with alcohol at any suitable concentration. In one embodiment, the concentration of alcohol in the alcohol / CO ₂ solution is, based on the total weight of the alcohol component in the alcohol and CO ₂ / CO ₂ solution, from about 1% to about 15% by weight. The alcohol / CO ₂ solution may also be combined with other components as exemplarily described above (eg, co-solvent, active agent (s), surfactant (s) and / or chelating agent (s)). Together preferably.

Although the present invention has been described herein with reference to various specific aspects, features, and implementations, the present invention is not limited thereto, and as will be apparent to one of ordinary skill in the art within the scope of the disclosure, On the basis of this, it will be apparent that other changes, modifications, and implementations are included.

Accordingly, the invention will be construed broadly, including other changes, modifications, and embodiments within the spirit and scope of the invention as claimed hereinafter.

1 is a scanning electron micrograph (SEM) of a patterned wafer showing details of the pattern structure, used as a control sample, in connection with FIGS. 2-4.

FIG. 2 is an SEM photograph of the patterned wafer of the type shown in FIG. 1 after air-drying the wafer.

3 is a SEM photograph of the patterned wafer of the type shown in FIG. 1 after drying the wafer with liquid CO ₂ .

FIG. 4 is a SEM photograph of the patterned wafer of the type shown in FIG. 1, first treated with liquid CO ₂ and then dried with supercritical CO ₂ .

Claims (45)

For removing water from a patterned wafer comprising a supercritical fluid and at least one water-reactive agent that chemically reacts with water to form reaction product (s) that are more soluble in the supercritical fluid than water. Drying composition for patterned wafers. The supercritical fluid of claim 1, wherein the supercritical fluid is selected from the group consisting of carbon dioxide, oxygen, argon, krypton, xenon, and ammonia. A composition comprising a fluid species. The composition of claim 1, wherein the supercritical fluid comprises carbon dioxide. The method of claim 1, wherein the at least one water-reactive agent comprises halogenated aldehydes and ketones; Halogenated diketones; Halogenated esters; Carboxylic anhydrids; Siloxanes; And an agent selected from the group consisting of halogenated silanes. The method of claim 1, wherein the at least one water-reactive agent comprises hexafluoroacetone; (CH ₃ CO) ₂ O; And 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (1,1,1,5,5,5-hexafluoro-2,4-pentanedione) A composition comprising a formulation. The composition of claim 1, wherein the at least one water-reactive agent comprises hexafluoroacetone. The method of claim 1, wherein the at least one water-reactive agent is 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (1,1,1,5,5,5- hexafluoro-2,4-pentanedione). The composition of claim 1, wherein the at least one water-reactive formulation is in a concentration ranging from about 0.01 to 10 weight percent based on the total weight of the supercritical fluid and the water-reactive formulation. The composition of claim 1, wherein the supercritical fluid comprises SCCO 2 and the water-reactive agent comprises hexafluoroacetone. Contacting the patterned wafer with a composition comprising a supercritical fluid and at least one water-reactive agent that chemically reacts with water to form a reaction product that is more soluble in the supercritical fluid than water. Characterized in that the method of patterned wafer drying to remove water from the patterned wafer. The supercritical fluid of claim 10, wherein the supercritical fluid is selected from the group consisting of carbon dioxide, oxygen, argon, krypton, xenon, and ammonia. And a fluid species. The method of claim 10, wherein the supercritical fluid comprises carbon dioxide. The method of claim 10, wherein the at least one water-reactive agent comprises halogenated aldehydes and ketones; Halogenated diketones; Halogenated esters; Carboxylic anhydrids; Siloxanes; And an agent selected from the group consisting of halogenated silanes. The method of claim 10, wherein the at least one water-reactive agent comprises hexafluoroacetone; (CH ₃ CO) ₂ O; And 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (1,1,1,5,5,5-hexafluoro-2,4-pentanedione) A method comprising a formulation. The method of claim 10, wherein said at least one water-reactive agent comprises hexafluoroacetone. The method of claim 10, wherein the at least one water-reactive agent is 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (1,1,1,5,5,5- hexafluoro-2,4-pentanedione). The method of claim 10, wherein the at least one water-reactive formulation is in a concentration ranging from about 0.01 to 10.0 wt%, based on the total weight of the supercritical fluid and the water-reactive formulation. The method of claim 10, wherein the supercritical fluid comprises SCCO 2 and the water-reactive agent comprises hexafluoroacetone. The method of claim 10 wherein said contacting step is performed for about 20 to 60 seconds. The method of claim 10 wherein said contacting step is performed at the contacting zone into which said composition is introduced. The method of claim 20, wherein the composition flows through the contact area. The method of claim 21, wherein the composition is recycled through the contacting zone. The method of claim 20, wherein after a predetermined contact time, the contact region is depressurized to eject the composition from the contact region. The method of claim 23, wherein the contacting zone is depressurized for about 10-40 seconds to drain the composition from the contacting zone and remove water. The method of claim 10, wherein the contacting step is performed without disrupting the pattern of the patterned wafer. Contacting the patterned wafer with a first composition comprising liquid CO ₂ , and then contacting the patterned substrate with a second composition comprising SCCO 2 to provide a patterned substrate without damaging the pattern of the patterned substrate. A method of patterned wafer drying for removing water from a patterned wafer, comprising performing a drying of the patterned wafer. 27. The method of claim 26, wherein contacting the first composition is performed at a temperature in the range of about 20 to 30 ° C. The method of claim 27, wherein contacting the first composition is performed for about 0.5 to 20 minutes. 27. The method of claim 26, wherein contacting the second composition is performed at a temperature in the range of about 32 to 75 ° C. 30. The method of claim 29, wherein contacting the second composition is performed for about 0.5 to 20 minutes. The method of claim 26, wherein the first composition contacting step is performed for about 0.5 to 20 minutes at a temperature in the range of about 20 to 30 ° C., and the second composition contacting step is about 0.5 to 20 at a temperature in the range of about 32 to 75 ° C. 27. Characterized in that performed for minutes. (a) contacting the patterned wafer with a first composition comprising alcohol at a pressure of about 1000 psi or higher and a temperature of 32 ° C. or less, (b) bringing the patterned wafer into an alcohol / CO ₂ solution Contacting the patterned substrate with a third composition comprising SCCO 2 to dry the patterned substrate without damaging the pattern of the patterned substrate. Characterized in that the method of patterned wafer drying to remove water from the patterned wafer. 33. The method of claim 32, wherein said contacting step (a) is performed for about 1 to 15 minutes. The method of claim 32, wherein the alcohol of the first composition comprises at least one C ₁ -C ₄ alcohol. 33. The method of claim 32, wherein said alcohol of said first composition comprises methanol. 33. The method of claim 32, wherein the alcohol of the first composition is the same as the alcohol of the second composition. 33. The method of claim 32, wherein the first composition is recycled in contact with the patterned wafer. 33. The method of claim 32, wherein the second composition is recycled in contact with the patterned wafer. 33. The method of claim 32, wherein the third composition is recycled in contact with the patterned wafer. 33. The method of claim 32, wherein said contacting step (b) is performed at a temperature in the range of about 22 to 31 ° C. 33. The method of claim 32, wherein said contacting step (b) is performed for about 0.5 to 20 minutes. 33. The method of claim 32, wherein said contacting step (c) is performed at a temperature of about 32 to 75 ° C. 33. The method of claim 32, wherein said contacting step (c) is performed for about 0.5 to 20 minutes. 33. The method of claim 32, wherein the concentration of alcohol in the second composition is in a range of about 1 to 15 weight percent based on the total weight of the alcohol and the CO ₂ in the second composition. 33. The method of claim 32, wherein said contacting steps (a), (b) and (c) are performed in the same chamber.

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