Methods of eliminating pattern collapse on photoresist patterns

A stabilizing solution for treating photoresist patterns and methods of preventing profile abnormalities, toppling and resist footing are disclosed. The stabilizing solution comprises a non-volatile component, such as non-volatile particles or polymers, which is applied after the photoresist material has been developed. By treating the photoresist with the solution containing a non-volatile component after developing but before drying, the non-volatile component fills the space between adjacent resist patterns and remains on the substrate during drying. The non-volatile component provides structural and mechanical support for the resist to prevent deformation or collapse by liquid surface tension forces.

FIELD OF THE INVENTION

The invention relates to the fabrication of electronic components such as integrated circuit semiconductors and, in particular, to methods for avoiding resist pattern collapse in the photolithography steps of integrated circuit fabrication.

BACKGROUND OF THE INVENTION

Photolithographic patterning is a well-established technology in the manufacturing processes of various kinds of semiconductor devices and liquid crystal display panels. According to photolithographic patterning, a photosensitive resist composition is first coated onto a surface of a substrate to form a photoresist layer. The photoresist layer is then exposed to radiation, such as ultraviolet light or electron beam, so that some portions of the photoresist are impacted by radiation while other portions of the photoresist are not impacted by the radiation. Subsequently, the photoresist is subjected to a developer solution, which selectively removes either the impacted or non-impacted portions of the photoresist. If the photoresist is a positive photoresist, the impacted portions are selectively removed; if the photoresist is a negative photoresist, the non-impacted portions are selectively removed. The photoresist material remaining after development shields or masks the regions of the substrate from subsequent etch or implant operations.

The development process of photoresist is conducted to provide the pattern which will serve as a mask for etching, ion-implantation or lift-off, for example, on the substrate. One of the goals of an effective development process is minimizing pattern distortion. Pattern distortion is the result of many factors, two primary ones being resist roughness and surface tension. Surface tension pulls down the walls of the photoresist (also known as toppling) during the rinsing and drying steps of the development process, therefore destroying the pattern that was originally formed. As illustrated inFIG. 1, for example, fine lines formed by photoresist are used to pattern electrical connections onto a blanket layer, for example a blanket metal layer. When the walls of the photoresist topple, the connections cannot be properly placed onto the blanket metal layer. Toppling of the photoresist causes damage to the substrate, is costly as substrates must be scrapped, and time consuming.

Accordingly, there is a need for a photoresist stabilizing solution that will reduce or eliminate the toppling of the photoresist, therefore improving manufacturing efficiency and production yields. Also needed are methods of increasing the mechanical and structural strength of photoresist patterns to prevent deformation, profile abnormalities or collapse by liquid surface tension forces in high density semiconductor fabrication.

SUMMARY OF THE INVENTION

The present invention provides a stabilizing solution for treating photoresist patterns to prevent profile abnormalities, toppling and resist footing. The stabilizing solution comprises a non-volatile component, such as non-volatile particles or polymers, which is applied after the photoresist material has been developed. By treating the photoresist with the solution containing a non-volatile component after developing but before drying, the non-volatile component fills the space between adjacent resist patterns and remains on the substrate during drying. In this manner, the non-volatile component provides structural and mechanical support for the resist to prevent deformation or collapse by liquid surface tension forces.

The present invention also provides a method of stabilizing a photoresist layer. The method comprises the steps of forming a photoresist layer on a substrate, exposing the photoresist layer through a mask to create an exposed area of photoresist and an unexposed area of photoresist; developing the photoresist layer; and applying a stabilizing treatment to the photoresist layer without changing the physical and chemical properties of the photoresist.

Additional advantages and features of the present invention will be apparent from the following detailed description and drawings which illustrate preferred embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, reference is made to various specific embodiments in which the invention may be practiced. These embodiments are described with sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be employed, and that structural and logical changes may be made without departing from the spirit or scope of the present invention.

The terms “substrate” and “wafer” can be used interchangeably in the following description and may include any semiconductor-based structure or insulating structure on or at the surface if which circuitry may be formed. The structure should be understood to include silicon, silicon-on insulator (SOI), silicon-on-sapphire (SOS), doped and undoped semiconductors, epitaxial layers of silicon supported by a base semiconductor foundation, and other semiconductor and insulating structures. The semiconductor need not be silicon-based. The semiconductor could be silicon-germanium, germanium, or gallium arsenide. When reference is made to the substrate in the following description, previous process steps may have been utilized to form regions or junctions in or over the base semiconductor or foundation.

The inventors of the present invention have realized that pattern density may be increased and toppling and resist profile abnormalities may be reduced if photoresist patterns are immersed in a stabilizing solution and subjected to a stabilizing treatment. In one embodiment, the stabilizing solution comprises a non-volatile component which is applied to displace at least part of the rinse solution after the photoresist material has been developed. By treating the photoresist with a solution containing a non-volatile component after developing but before drying, the non-volatile component fills the space between adjacent resist patterns and remains on the substrate during drying. In this manner, the non-volatile component provides structural and mechanical support for the resist to prevent deformation or collapse by liquid surface tension forces.

In yet another embodiment, the stabilizing solution is a polymer solution. During the developing stage, preferably during the puddle time, at least part of the developing solution is replaced with the polymer solution by spinning off and continuously adding the polymer solution, so that the developing solution is replaced by the polymer solution. Subsequent to the displacement of the developing solution by the polymer solution, the wafer is baked so that solvent (such as water, for example) from the polymer solution evaporates, living polymer material to fill in the space between adjacent resist patterns. In this manner, the remaining polymer material provides structural and mechanical support for the resist to prevent deformation or collapse by liquid surface tension forces.

In yet another embodiment of the present invention, the stabilizing solution comprises a polymer solution which replaces a developing solution used for patterning a bilayer photoresist. During the developing stage, preferably during the puddle time, at least part of the developing solution is replaced with the polymer solution by spinning off and continuously adding the polymer solution, so that the developer is replaced by the polymer solution. Subsequent to the displacement of the developer by the polymer solution, the wafer is baked so that solvent (for example, water) from the polymer solution evaporates, living polymer material to fill at least partially the space between adjacent bilayer resist patterns. In this manner, the remaining polymer material provides structural support for the bilayer resist to prevent deformation or collapse by liquid surface tension forces.

In the embodiments of the present invention, physical and chemical properties of the photoresist material are substantially retained, while high strength developed photoresist is achieved to prevent pattern collapse in high density semiconductor fabrication.

Referring now to the drawings, where like elements are designated by like reference numerals,FIGS. 2–6illustrate a method of forming photoresist patterns using a positive photoresist according to an embodiment of the present invention. For exemplary purposes only, the embodiments below will be described with reference to a positive photoresist; however, the invention also contemplates methods of forming photoresist patterns using a negative photoresist.

For a better understanding of the present invention, a brief description of the principal characteristics of positive and negative resists will be provided below and before detailing the specific embodiments of the present invention. As known in the art, positive resists are sensitized when exposed to ultraviolet light so that exposed areas will dissolve in a developer solution leaving behind unexposed areas. In contrast, negative resists are hardened by exposure to ultraviolet light so that exposed areas are inhibited from being dissolved by the developer solution while unexposed areas are dissolved.

Positive photoresists are typically three-component materials, consisting of a matrix material, a photo-sensitive component and a solvent. Generally, the matrix components of positive photoresists are low-molecular weight phenolic polymers, acrylic polymers or other addition polymers, that provide the mechanical properties of the photoresist layer. The matrix polymers contain some level of pendant acidic site precursors such as alkyl esters. The photoresist formulation also contains a photosensitive component which, upon exposure to actinic light, for example, generates an acid. This acid catalytically cleaves the ester linkage causing the polymer to become soluble in the aqueous alkaline developer. The solvent component suspends the matrix polymer and photosensitive compound in a flowable liquid until the photoresist layer is cured with a soft-bake prior to being exposed to actinic light. Typical positive photoresist solvents include ketones, esters and alcohols, e.g., heptanone, propylene glycol methyl ether acetate, ethyl lactate, propylene glycol methyl ether.

Negative photoresists are also three-component materials, consisting of a matrix component, a sensitizer component and a solvent. Typically, negative photoresists comprise the same or similar polymers and photosensitive compounds as the positive photoresists, except that they contain cross-linkable groups rather than cleavable acid protecting groups. Negative photoresist solvents are generally similar to those used for positive photoresists.

Referring back toFIG. 2, a positive photoresist layer15is formed by deposition or spin coating, for example, on a layer12which in turn is formed over a substrate10. The layer12containing the pattern lines to be formed may comprise any layer of material used in an electronic or semiconductor device, such as an insulating, metal or semiconductor layer. Preferably, layer12comprises an insulating layer in a semiconductor device, such as a first level insulating layer or an intermetal dielectric. Layer12may also comprise an antireflective coating (ARC), such as a BARC layer or a DARC layer, for example, as well-known in the art.

After the photoresist layer15has been formed on layer12over substrate10, the photoresist layer15is preferably soft-baked to remove any existing solvents. For example, the soft-baking may be conducted at a temperature of about 90° C. to 150° C. for about 30 to 120 seconds on a hot plate. However, any suitable time and temperature and baking equipment may be used depending on the photoresist material.

The photoresist layer15is subsequently exposed to radiation18, such as actinic light or other suitable UV radiation, through openings19in the opaque pattern17in a mask or reticle20to form exposed regions25in the photoresist layer15, as illustrated inFIG. 2. During this step, the exposed regions25of the positive photoresist layer15are rendered soluble to developer solution. In contrast, remaining regions26of the photoresist layer15are shielded by the opaque layer17of the mask20and are not exposed. Thus, the exposed photoresist regions25are separated by unexposed regions26, which remain insoluble to the developer.

After the exposing step, the photoresist layer15is developed to remove the exposed photoresist regions25from the unexposed regions26and to provide openings22within the photoresist layer15, as shown inFIG. 3. Photoresist regions26are not removed during development and are used in subsequent steps and processes, such as etching or implanting of the underlying layer12. The photoresist layer15may be developed by any of the methods known in the art, including but not limited to quiescence, immersion, spray and puddle development. A brief description of these development methods is provided below.

The quiescense method adds developer to the exposed wafer surface and, after a period of time sufficient to develop the pattern, a rinse composition is added to the wafer surface and the wafer is then dried.

The immersion process comprises dipping the exposed semiconductor wafer into a bath of the developer composition for a predetermined period of time, and then removing the wafer from the bath. After the wafer has been removed from the immersion bath, it is immersed in a rinse bath. A displacement rinse method may be used using the same tank for both the development immersion and rinsing. Instead of immersing the developed wafer, the immersed wafer could be rinsed by spraying.

In the spray development method, the exposed wafer is sprayed with the developing composition for a certain period of time to develop the pattern typically for about 1 to 2 minutes. The developed wafer is then sprayed with the rinse composition to rinse the developer from the wafer surface. The rinse composition is typically sprayed for about 1 to 2 minutes and then dried using conventional techniques such as air drying.

In the puddle development process, which is the preferred development method in the present invention, the developing composition is puddled onto the exposed semiconductor wafer while the wafer is at rest and then the wafer is spun slowly at, for example, 100 rpm to distribute the developing composition over the wafer surface. The developer is then left on the wafer surface for sufficient time to develop the pattern, for example about 10 seconds to 2 minutes. The rinse composition is then puddled onto the still wet wafer surface typically while the wafer is at rest and spun similarly to the developing composition to rinse the wafer.

The developing composition which may be used in the methods of the present invention may be any suitable commercial developer. Developing compositions are typically basic and may contain potassium hydroxide, sodium hydroxide, sodium silicate and the like as the principal component, but it is preferred that the basic component be a basic organic compound which is free from metal ions such as tetramethyl ammonium hydroxide.

In the developing step, which can employ any of the development methods described above, the exposed areas25of positive photoresist layer15are removed by a developing solution to leave the desired pattern image on surface13of the layer12. At the end of the developing step, the surface13is rinsed to stop the developing reaction and remove the developer solution from the surface. As noted above, typical positive resist developer solutions are alkaline solutions diluted with water, which require only a water rinse. Negative resist developer solutions may be organic solvents, which require rinsing with other organic solvents (e.g. n-butyl acetate). Thus, for the positive photoresist layer15described above, a rinse solution such as an aqueous rinse, for example de-ionized (DI) water rinse, is conducted to stop the developing reaction and remove the developer solution from the surface13of the layer12. The rinse solution rapidly dilutes the developer chemical so that the developing action stops. The rinse also removes any partially polymerized pieces of resist from the open regions in the resist film.

As illustrated inFIG. 3, subsequent to the development and rinse of the photoresist layer15but before drying, the rinse solution is displaced by a stabilizing solution or suspension50containing at least one non-volatile component and the substrate is subjected to a stabilizing treatment according to a method of the present invention. Solution50containing at least one non-volatile component is applied to the remaining positive photoresist layer15(i.e., the unexposed resist26) by displacing at least part of the rinse solution. In a preferred embodiment, the solution50containing non-volatile components is added to gradually replace the rinse solution. However, it must be understood that the invention also contemplates embodiments wherein the solution50containing non-volatile components is applied to the substrate10by immersing the substrate in a separate bath containing the solution50containing non-volatile components. In addition, the solution50containing non-volatile components may be applied only to one area of interest of the photoresist layer15, whereas the other remaining photoresist areas may be subjected to a drying process, for example. In this case, only the area of interest of the photoresist layer15may be immersed or submerged in the solution50containing non-volatile components, while the rest of the substrate may be allowed to dry.

The solution or suspension50containing at least one non-volatile component of the present invention may comprise a solvent (such as water, for example) and any non-volatile component that can be dry etched highly selectable to the photoresist material15. For example, the non-volatile component may comprise non-volatile particles such as silica gel particles (SiOx particles), graphite particles, Bucky balls (C60) or latex spheres, among many others, or combinations of such particles. The non-volatile component may also comprise precipitants such as glucose, sugar or starch, or a combination of non-volatile particles and precipitants.

Reference is now made toFIG. 4. Subsequent to the displacement of the rinse solution with the solution50containing at least one non-volatile component of the present invention, substrate10is subjected to a heat treatment, for example a bake at about 90° C. to about 200° C., so that water or the solvent of the solution50containing at least one non-volatile component evaporates, living non-volatile component55filling in the space between adjacent regions26of the photoresist layer15. Although the non-volatile component55is illustrated inFIG. 4as only partially filling in the space between adjacent photoresist regions26, the invention also contemplates the embodiment wherein the non-volatile component55completely fills in the space between adjacent photoresist regions26. The non-volatile component55remaining between adjacent photoresist regions26acts as a support layer and provides structural and mechanical support for the photoresist regions26to prevent deformation or collapse of these regions by liquid surface tension forces during any additional rinse steps. Thus, although the physical and chemical properties of the photoresist material of the photoresist regions26are not altered, high strength developed photoresist patterns are achieved to prevent pattern collapse in high density semiconductor fabrication.

The structure ofFIG. 4is then subjected to an etching process to remove the non-volatile component55from the substrate and to further etch the layer12to form photolithographic pattern100comprising desired patterns or lines28provided within layer12, as shown inFIG. 5. The etching process may be a dry etching, such as a plasma etching (for example an O2plasma etching), or a wet etching employing a liquid etching medium, which removes the non-volatile component55and etched below the underlying surface13and within the layer12through openings23, as illustrated inFIG. 5. In this manner, patterns or lines28are formed within the layer12by employing photoresist patterns, such as the photoresist regions26ofFIGS. 3–4, which have reduced toppling and increased strength.

Subsequent to the removal of the non-volatile component55, the structure ofFIG. 5is dried and optionally treated with ultraviolet radiation to reduce the tendency of the photoresist to flow during subsequent processing steps where the photoresist will experience high temperatures, which may including bake cycles, plasma etching, ion implantation and ion milling, for example. This treatment is typically accomplished by irradiating the dried photoresist with deep UV while heating the substrate to a high temperature (e.g., 120–190° C.) for approximately a minute. Alternatively, the developed, rinsed, treated and dried photoresist layer may be further treated by irradiating the surface with electron beams with energies of about 1 to 100 KeV.

The embodiment of the present invention described above is further explained with reference to the following example and in conjunction withFIG. 6. The invention is not intended to be limited to the particular example described below:

A bare silicon wafer was processed with 2800A AR360 resist on 450A DongJin Barc and exposed with a reticle at standard exposure/focus. The wafer received a standard post-exposure bake. The wafer was subsequently developed and rinsed in a dump rinse tank, and then pulled out from the tank and placed horizontally. A Klebesol slurry using silica particles was applied to the wafer before the drying process could induce collapse (toppling) of the patterns26a(FIG. 6). The time from the pulling out of the tank of the wafer to applying the Klebesol slurry was preferably under 10 seconds, to avoid collapse of the patterns.

FIG. 6is a photograph illustrating silica particles55aof the Klebesol slurry physically supporting resist lines26awithout collapse, fabricated as detailed in Example 1. As shown inFIG. 6, the resist lines26ahave a vertical and substantially defect-free profile, with virtually no pattern collapse and no resist footing or profile abnormalities. The silica particles55awere dry etched with minimal etching of the resist lines. Dry etching is preferred to a wet etching, as a wet etching may induce surface tension which, in turn, may produce collapse.

Reference is now made toFIGS. 7–10, which illustrate another exemplary embodiment of the method of the present invention, according to which a stabilizing solution comprising a non-volatile polymer component displaces a developing solution. During the developing stage, preferably during the puddle time, the developing solution is replaced with a polymer solution by spinning off and continuously adding the polymer solution. Subsequent to the displacement of the developing solution by the polymer solution, the wafer is baked so that water or solvent from the polymer solution evaporates, living polymer material to fill in the space between adjacent resist patterns. The remaining polymer material provides structural and mechanical support for the resist to prevent deformation or collapse by liquid surface tension forces. The polymer solution may replace the rinse solution or, alternatively, may be employed in conjunction with the rinse solution.

FIG. 7illustrates the structure ofFIG. 3at the end of the development stage and formed as described in detail above with reference to the first exemplary embodiment of the present invention. Subsequent to the development of the photoresist layer15but before drying, the developing solution is displaced by a polymer solution or suspension150and the substrate is subjected to a stabilizing treatment according to a method of the present invention. Polymer solution150is applied to the remaining positive photoresist layer15(i.e., the unexposed resist26) by displacing at least part of the developing solution. In a preferred embodiment, the polymer solution150displaces the developing solution and is added to gradually replace the developing solution. However, it must be understood that the invention also contemplates embodiments wherein the polymer solution150is applied to the substrate by immersing the substrate in a separate bath containing the polymer solution150. In addition, the polymer solution150may be applied only to one area of interest of the photoresist layer15, whereas the other remaining areas are subjected to a drying process, for example. In this case, only the area of interest of the photoresist layer15may be immersed or submerged in the solution150, while the rest of the substrate may be allowed to dry.

The polymer solution150of the present invention may comprise any non-volatile polymer component that can be dry etched highly selectable to the photoresist material15. In addition, the non-volatile polymer component needs to be soluble in a suitable solvent to form the polymer solution150. For example, in one embodiment of the present invention, the polymer solution150is an aqueous polymer solution which may comprise PVA (polyvinyl alcohol) or any polymer, such as for example, an acrylic polymer, which is soluble in water. The polymer may further comprise chemical cross-links throughout the polymer. Exemplary polymers include homopolymers and copolymers comprising polyhydroxyethylmethacrylate, polymethylmethacrylate, substituted polymethylmethacrylate, and polystyrene, among others. The polymer may also comprise an acidic unit (if the resist needs to be smoothed effectively) or, alternatively, an acidic additive may be subsequently added to the aqueous polymer solution150.

In another embodiment of the present invention, the polymer solution150may comprise PVA (polyvinyl alcohol) or any polymer such as the ones described above and further in combination with a polymeric precursor (which may include cross-linking materials) suspended or dissolved in a suitable solvent (and further optionally comprising water). Solvents can include, for example, ethyl lactate, methylamylketone, polypropyleneglycol monomethyletheracetate (PGMEA), and propyleneglycol monomethylether (PGME), in applications in which the polymeric precursors comprise benzoyl peroxide, benzil and/or benzil derivatives, together with cross-linking materials selected from the group consisting of hexamethoxymethirol melamine and tetramethoxyglycouril.

Subsequent to the displacement of the developing solution with the polymer solution150of the present invention, substrate10is subjected to a heat treatment, for example a bake at about 90° C. to about 200° C., so that the water or the solvent (or a combination of water/solvent) of the polymer solution150evaporates, living non-volatile polymer155filling in the space between adjacent regions26of the photoresist layer15. Although the non-volatile polymer155is illustrated inFIG. 8as totally filling in the space between adjacent photoresist regions26, the invention also contemplates embodiments wherein the non-volatile polymer155only partially fills in the space between adjacent photoresist regions26. As in the previously-described embodiment, the non-volatile polymer155remaining between adjacent photoresist regions26acts as a support layer and provides structural and mechanical support for the photoresist regions26, to prevent deformation or collapse of these regions.

The structure ofFIG. 8is then subjected to an etching process to remove the non-volatile polymer155from the substrate and to further etch the layer12to form photolithographic pattern200comprising desired patterns or lines128within layer12, as shown inFIG. 9. Depending on the nature of the polymer, the etching process may be a dry etching, such as a plasma etching, or a wet etching employing a liquid, which is permitted to remove the non-volatile polymer155and to reach the underlying surface13of the layer12through openings23, as illustrated inFIG. 9. In this manner, patterns or lines128are formed within the layer12by employing photoresist patterns, such as the photoresist regions26ofFIGS. 7–8, which have reduced toppling and increased strength.

Subsequent to the removal of the non-volatile polymer155, the structure ofFIG. 9is dried and optionally treated with ultraviolet radiation to reduce the tendency of the photoresist to flow during subsequent process steps, as in the previously-described embodiment.

The second embodiment of the present invention described above is further explained with reference to the following example and in conjunction withFIG. 10. The invention is not intended to be limited to the particular example described below:

A bare silicon wafer was processed with 2000A AR360 resist from JSR on 450A DongJin Barc. After the resist formation, the wafer was baked at a temperature of about 130° C. for about 90 seconds and then exposed on an ASML scanner PAS1100. The wafer was baked again, at a temperature of about 130° C. for about 90 seconds. The wafer was subsequently developed with ARCH 4262 developer for about 30 seconds. While spinning the developer on the wafer, a TOK FSC050 polymer solution was added by spin coating to displace the developer. The wafer was rinsed in a dump rinse tank, and then pulled out from the tank and baked at a temperature of about 170° C. for about 60 seconds. After the baking, a de-ionized (DI) water rinse was applied.

FIG. 10is a photograph illustrating resist pattern lines126awithout profile abnormalities and without toppling, fabricated as detailed in Example 2 above. As shown inFIG. 10, the resist lines126ahave a vertical and substantially defect-free profile, with virtually no pattern collapse and minimal resist roughness or profile abnormalities.

Although the embodiment above has been described with reference to the polymer solution150displacing the developing solution and used in lieu of a rinse solution, it must be understood that the invention is not limited to this embodiment and also contemplates using the polymer solution150in conjunction with a rinse solution. In this case, the rinse solution is applied subsequently to the polymer solution150and before the drying step. For the positive photoresist layer15ofFIG. 7, a rinse solution such as a de-ionized (DI) water rinse may be applied to remove any partially polymerized pieces of resist from the open regions in the resist film.

FIGS. 11–13illustrate yet a third embodiment of the present invention, according to which resist patterns or lines having a vertical and substantially defect-free profile are formed within a bilayer photoresist215, and not within a photoresist layer, such as the photoresist layer15as in the previously described embodiments. Thus,FIGS. 11–13illustrate a method of forming resist lines and patterns having no pattern collapse and no resist roughness or profile abnormalities, similar in part to that described above with reference toFIGS. 7–9, but different in that the photoresist layer15ofFIGS. 7–9is replaced with a bilayer photoresist215inFIGS. 11–13.

Accordingly,FIG. 11illustrates non-exposed photoresist regions226of the bilayer photoresist215at the end of the development stage. The bilayer photoresist215may be any known bilayer photoresist known in the art, such as for example, DPSC-011 from TOK or SR2420 from Shipley Co., among others. Subsequent to the development of the bilayer photoresist215but before drying, the developing solution is displaced by a polymer solution or suspension150and the substrate is subjected to a stabilizing treatment according to a method of the present invention. Polymer solution150is applied to the remaining bilayer photoresist215(i.e., the unexposed resist226) by displacing at least part of the developing solution. In a preferred embodiment, the polymer solution150is added to gradually replace the developing solution but, as in the previously-described embodiments, the invention is not limited to this embodiment. In addition, the polymer solution150may be applied only to one area of interest of the bilayer photoresist215, whereas the other remaining areas are subjected to a drying process, for example.

Subsequent to the displacement of the developing solution with the polymer solution150of the present invention, substrate10is subjected to a heat treatment, for example a bake at about 90° C. to about 200° C., so that the water or the solvent (or a combination of water/solvent) of the polymer solution150evaporates, living non-volatile polymer255(FIG. 12) filling in the space between adjacent regions226of the bilayer photoresist215. Although the non-volatile polymer255is illustrated inFIG. 12as totally filling in the space between adjacent photoresist regions226, the invention also contemplates the embodiment wherein the non-volatile polymer255only partially fills in the space between adjacent photoresist regions226. The non-volatile polymer255remaining between adjacent photoresist regions226acts as a support layer and provides structural and mechanical support for the photoresist regions226to prevent deformation or collapse of these regions.

The structure ofFIG. 12is then subjected to an etching process to remove the non-volatile polymer255from the substrate and to further etch the layer12to form photolithographic pattern300comprising desired patterns or lines228within layer12, as shown inFIG. 13. Depending on the nature of the polymer, the etching process may be a dry etching, such as a plasma oxygen etching, or a wet etching employing a liquid etching medium, which is permitted to remove the non-volatile polymer255and to reach the underlying surface13of the layer12through openings23, as illustrated inFIG. 13. In this manner, patterns or lines228are formed within the layer12by employing bilayer photoresist patterns, such as the photoresist regions226ofFIGS. 11–12, which have reduced toppling and increased strength.

Subsequent to the removal of the non-volatile polymer255, the structure ofFIG. 12is dried and optionally treated with ultraviolet radiation to reduce the tendency of the photoresist to flow during subsequent process steps, as in the previously-described embodiment.

Although the embodiment above has been described with reference to the polymer solution150displacing the development solution and used in lieu of a rinse solution, it must be understood that the invention is not limited to this embodiment and also contemplates using the polymer solution150in conjunction with a rinse solution. In this case, the rinse solution is applied subsequent to the polymer solution150and before the drying step. For the bilayer photoresist215ofFIG. 11, a rinse solution such as a de-ionized (DI) water rinse may be applied to remove partially polymerized pieces of resist from the open regions in the resist film.

Although the embodiments above have been illustrated with reference to the formation of pattern lines, such as pattern lines28,128and228ofFIGS. 5,9and13, respectively, it must be understood that the invention is not limited to the formation of pattern lines within a photoresist layer. Accordingly, the invention may be also employed for the formation of any semiconductor pattern that requires patterning and etching, for example, for defining any openings within a semiconductor substrate, including an insulating layer. Thus, the methods of the present invention may be also employed to form a contact hole or a capacitor hole having a high aspect ratio, typically higher than 2.0, or a combination of such structures. Referring toFIG. 5, for example, opening23may be of any capacitor structure or contact hole opening having a high aspect ratio of about 2.0, preferably higher than 2.0 and most preferably of about 3.0. Accordingly, the stabilizing methods and compositions of the present invention may be employed for the patterning of capacitor structures and contact holes, among others, during IC fabrication.

The above description illustrates preferred embodiments that achieve the features and advantages of the present invention. It is not intended that the present invention be limited to the illustrated embodiments. Modifications and substitutions to specific process conditions and structures can be made without departing from the spirit and scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description and drawings, but is only limited by the scope of the appended claims.