Sidewall image transfer pitch doubling and inline critical dimension slimming

A method for patterning a substrate is described. The patterning method may include performing a lithographic process to produce a pattern and a critical dimension (CD) slimming process to reduce a CD in the pattern to a reduced CD. Thereafter, the pattern is doubled to produce a double pattern using a sidewall image transfer technique.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a method for patterning a thin film on a substrate, and more particularly to a method for multiple patterning a thin film on a substrate.

2. Description of Related Art

In material processing methodologies, pattern etching comprises the application of a layer of radiation-sensitive material, such as photo-resist, to an upper surface of a substrate, the formation of a pattern in the layer of radiation-sensitive material using photo-lithography, and the transfer of the pattern formed in the layer of radiation-sensitive material to an underlying thin film on the substrate using an etching process. The patterning of the radiation-sensitive material generally involves exposure of the radiation-sensitive material to a pattern of electromagnetic (EM) radiation using, for example, a photo-lithography system, followed by the removal of the irradiated regions of the radiation-sensitive material (as in the case of positive tone resist), or non-irradiated regions (as in the case of negative tone resist) using a developing solution.

More recently, a double patterning approach has been introduced to allow the patterning of smaller features at a smaller pitch than what is currently possible with standard lithographic techniques. One approach to reduce the feature size is to use standard lithographic pattern and etch techniques on the same substrate twice (i.e., LELE, or Litho/Etch/Litho/Etch), thereby forming larger patterns spaced closely together to achieve a smaller feature size than would be possible by single exposure. During LELE double patterning, the substrate is exposed to a first pattern, the first pattern is developed in the radiation-sensitive material, the first pattern formed in the radiation-sensitive material is transferred to an underlying layer using an etching process, and then this series of steps is repeated for a second pattern.

Another approach to reduce the feature size is to use standard lithographic pattern on the same substrate twice followed by etch techniques (i.e., LLE, or Litho/Litho/Etch), thereby forming larger patterns spaced closely together to achieve a smaller feature size than would be possible by single exposure. During LLE double patterning, the substrate is exposed to a first pattern, the substrate is exposed to a second pattern, the first pattern and the second pattern are developed in the radiation-sensitive material, and the first pattern and the second pattern formed in the radiation-sensitive material are transferred to an underlying layer using an etching process.

One approach to LLE double patterning includes a Litho/Freeze/Litho/Etch (LFLE) technique that utilizes an application of a freeze material on a first pattern in a first patterning layer to cause “freezing” or cross-linking therein, thus allowing the first patterning layer to withstand subsequent processing of a second patterning layer with a second pattern. However, conventional double patterning techniques still have a limit to the ultimate feature size that is printable.

SUMMARY OF THE INVENTION

The invention relates to a method for patterning a thin film on a substrate. The invention also relates to methods for double patterning or quadruple patterning a thin film on a substrate. The invention further relates to a method for patterning a thin film on a substrate using a LFLE double patterning technique and a sidewall image transfer technique. Further yet, the LFLE double patterning technique and sidewall image transfer technique includes a critical dimension (CD) slimming process.

According to one embodiment, a method for patterning a substrate is described. The method may include performing a lithographic process to produce a pattern and a CD slimming process to reduce a CD in the pattern to a reduced CD. Thereafter, the pattern is doubled to produce a double pattern using a sidewall image transfer technique.

According to another embodiment, a method for patterning a substrate is described. The method may include a LFLE technique to produce a first double pattern that includes a first CD slimming process to reduce a first CD to a first reduced CD in the first double pattern and a second CD slimming process to reduce a second CD to a second reduced CD in the first double pattern. Thereafter, the first double pattern is doubled to produce a second double pattern using a sidewall image transfer technique.

According to another embodiment, a method for patterning a substrate is described. The method may include: preparing a pattern in a layer of radiation-sensitive material using a lithographic process, the pattern being characterized by a CD; following the preparing the pattern, performing a CD slimming process to reduce the CD to a reduced CD; conformally depositing a material layer over the pattern with the reduced CD; partially removing the material layer using an etching process to expose a top surface of the pattern, open a portion of the material layer at a bottom region between adjacent features of the pattern, and retain a remaining portion of the material layer on sidewalls of the pattern; and removing the pattern using one or more etching processes to leave a final pattern comprising the remaining portion of the material layer that remained on the sidewalls of the pattern.

According to another embodiment, a method for patterning a substrate is described. The method comprises: forming a first layer of radiation-sensitive material; preparing a first pattern in the first layer of radiation-sensitive material using a first lithographic process, the first pattern being characterized by a first CD; following the preparing the first pattern, performing a first CD slimming process to reduce the first CD to a first reduced CD; freezing the first pattern with the first reduced CD in the first layer of radiation-sensitive material using a freeze process; forming a second layer of radiation-sensitive material on the first pattern with the first reduced CD in the first layer of radiation-sensitive material; preparing a second pattern in the second layer of radiation-sensitive material using a second lithographic process, the second pattern being characterized by a second CD; and following the preparing the second pattern, performing a second CD slimming process to reduce the second CD to a second reduced CD. The method further comprises conformally depositing a material layer over the first pattern with the first reduced CD and the second pattern with the second reduced CD, partially removing the material layer using an etching process to expose a top surface of the first pattern and a top surface of the second pattern, open a portion the material layer at a bottom region between the first pattern and the second pattern, and retain a remaining portion of the material layer on sidewalls of the first pattern and the second pattern; and removing the first pattern and the second pattern using one or more etching processes to leave a third pattern comprising the remaining portion of the material layer that remained on the sidewalls of the first pattern and the second pattern.

According to yet another embodiment, a line pattern formed in one or more layers of radiation-sensitive material comprising a line pattern CD less than 10 nm is described.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS

A method for patterning a substrate is disclosed in various embodiments. However, one skilled in the relevant art will recognize that the various embodiments may be practiced without one or more of the specific details, or with other replacement and/or additional methods, materials, or components. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of various embodiments of the invention.

Similarly, for purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the invention. Nevertheless, the invention may be practiced without specific details. Furthermore, it is understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.

Nonetheless, it should be appreciated that, contained within the description are features which, notwithstanding the inventive nature of the general concepts being explained, are also of an inventive nature.

Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views,FIGS. 1A through 1J, andFIG. 2illustrate a method for patterning a substrate according to an embodiment. The method is illustrated in a flow chart200, and begins in210with preparing a pattern in a layer of radiation-sensitive material using a lithographic process, wherein the pattern is characterized by a critical dimension (CD).

As shown inFIG. 1A, the preparing of the pattern may include forming a first layer of radiation-sensitive material120on a substrate110. The first layer of radiation-sensitive material120may include a photo-resist. For example, the first layer of radiation-sensitive material120may comprise a 248 nm (nanometer) resist, a 193 nm resist, a 157 nm resist, an EUV (extreme ultraviolet) resist, or an electron beam sensitive resist. Furthermore, for example, the first layer of radiation-sensitive material120may comprise a thermal freeze photo-resist, an electromagnetic (EM) radiation freeze photo-resist, or a chemical freeze photo-resist.

The first layer of radiation-sensitive material120may be formed by spin-coating the material onto substrate110. The first layer of radiation-sensitive material120may be formed using a track system. For example, the track system can comprise a Clean Track ACT® 8, ACT® 12, LITHIUS®, LITHIUS™ Pro™, or LITHIUS™ Pro V™ resist coating and developing system commercially available from Tokyo Electron Limited (TEL). Other systems and methods for forming a photo-resist film on a substrate are well known to those skilled in the art of spin-on resist technology. The coating process may be followed by one or more first post-application bakes (PAB) to heat the substrate110and one or more cooling cycles, following the one or more first PABs, to cool the substrate110.

As shown inFIG. 1B, the preparing of the pattern may further include preparing a first pattern122in the first layer of radiation-sensitive material120using a first lithographic process, wherein the first pattern122is characterized by a first critical dimension (CD)124. The substrate110having the first layer of radiation-sensitive material120is aligned at a first alignment position in a radiation exposure system and imaged with first radiation having a first image pattern. The radiation exposure system may include a dry or wet photo-lithography system. The first image pattern may be formed using any suitable conventional stepping lithography system, or scanning lithography system. For example, the photo-lithography system may be commercially available from ASML Netherlands B.V. (De Run 6501, 5504 DR Veldhoven, The Netherlands), or Canon USA, Inc., Semiconductor Equipment Division (3300 North First Street, San Jose, Calif. 95134). Alternatively, the first image pattern may be formed using an electron beam lithography system.

The first layer of radiation-sensitive material120, having been exposed to the first image pattern, is subjected to a developing process in order to remove the first image pattern region, and form the first pattern122in the first layer of radiation-sensitive material120. The first pattern122may be characterized by the first CD124. The first pattern122may include a first line pattern. The developing process can include exposing the substrate to a developing solution in a developing system, such as a track system. For example, the track system can comprise a Clean Track ACT® 8, ACT® 12, LITHIUS®, LITHIUS™ Pro™, or LITHIUS™ Pro V™ resist coating and developing system commercially available from Tokyo Electron Limited (TEL). The developing process may be preceded by one or more first post-exposure bakes (PEB) to heat the substrate110and one or more cooling cycles, following the one or more first PEBs, to cool the substrate110.

In220, a CD slimming process is performed, following the preparing the pattern, to reduce the CD to a reduced CD. The performing the CD slimming process may include, as shown inFIG. 1C, performing a first CD slimming process to reduce the first CD124to a first reduced CD126.FIG. 3illustrates a CD slimming process, andFIGS. 4A and 4Bprovide exemplary data for the CD slimming process.

As shown inFIG. 1D, the first pattern122with the first reduced CD126in the first layer of radiation-sensitive material120is frozen using a freeze process to form a frozen first layer of radiation-sensitive material120′. In one embodiment, the first layer of radiation-sensitive material120may include a thermally curable freeze resist, wherein freezing the first pattern122in the first layer of radiation-sensitive material120using the freeze process comprises baking (or thermally heating) the first layer of radiation sensitive material120to thermally cure and preserve the first pattern122with the first reduced CD126. During the freeze process, the temperature and the bake time are process parameters that may be adjusted to achieve pattern CD control.

As will be discussed later and while not intended to be limiting, the terms “freeze”, “freezing”, “frozen”, etc., as used herein, represent a process or a result of the process wherein a layer of radiation-sensitive material is prepared and/or treated to alter a condition of the layer of radiation-sensitive material to withstand subsequent lithographic processing. For example, once a pattern is frozen in the layer of radiation-sensitive material, the pattern substantially remains with or without some change to the pattern CD following an additional lithographic process.

In an alternate embodiment, the first layer of radiation-sensitive material120may include an EM radiation curable freeze resist, wherein freezing the first pattern122in the first layer of radiation-sensitive material120using the freeze process comprises exposing the first layer of radiation sensitive material120to EM radiation to radiatively cure and preserve the first pattern122with the first reduced CD126. During the freeze process, the EM intensity and the time for exposure are process parameters that may be adjusted to achieve pattern CD control.

In yet another alternate embodiment, the first layer of radiation-sensitive material120may include a chemically curable freeze resist, wherein freezing the first pattern122in the first layer of radiation-sensitive material120using the freeze process comprises applying a chemical freeze material to and reacting the chemical freeze material with the first layer of radiation sensitive material120to chemically cure and preserve the first pattern122with the first reduced CD126. During the freeze process, the concentration and type of the chemical freeze material, and the time for exposure are process parameters that may be adjusted to achieve pattern CD control.

Therein, a chemical freeze material may be applied over the first layer of radiation-sensitive material120to chemically interact with the first layer of radiation-sensitive material120. The chemical freeze material may be formed by spin-coating the material onto substrate110. The chemical freeze material may be formed using a track system. For example, the track system can comprise a Clean Track ACT® 8, ACT® 12, LITHIUS®, LITHIUS™ Pro™, or LITHIUS™ Pro V™ resist coating and developing system commercially available from Tokyo Electron Limited (TEL). Other systems and methods for forming a photo-resist film on a substrate are well known to those skilled in the art of spin-on resist technology. The coating process may be followed by one or more bake processes to heat substrate110and cure at least a portion of the chemical freeze material.

As a result of applying the chemical freeze material to substrate110and heating substrate110, a portion of the chemical freeze material reacts with the exposed surface of the first layer of radiation-sensitive material120to form the frozen first layer of radiation-sensitive material120′. Thereafter, the chemical freeze material is stripped from the substrate110using a strip solution to preserve the first pattern122in the frozen first layer of radiation-sensitive material120′. The strip solution may contain a conventional strip solution or a high normality strip solution. For example, the strip solution contains an active solute having a normality (N) greater than 0.26. Alternatively, the strip solution contains an active solute having a normality (N) greater than 0.3. Alternatively, the strip solution contains an active solute having a normality (N) greater than 0.4. Alternatively, the strip solution contains an active solute having a normality (N) greater than 0.5.

The strip solution may comprise an aqueous alkali solution. Additionally, the strip solution may contain a hydroxide. Additionally, the strip solution may contain a quaternary ammonium hydroxide. Furthermore, the strip solution may include tetramethyl ammonium hydroxide (TMAH). The normality (N) of TMAH in the strip solution may be equal to or greater than 0.26. Alternatively, the normality (N) of TMAH in the strip solution may be greater than or equal to 0.3. Alternatively, the normality (N) of TMAH in the strip solution may be greater than or equal to 0.4. Alternatively, the normality (N) of TMAH in the strip solution may be greater than or equal to 0.5. Alternatively yet, the normality (N) of TMAH in the strip solution may be about 0.32. The concentration of TMAH in the strip solution may be equal to or greater than 2.36 (Yow/v (or 2.36 grams of solute per 100 milliliters (ml) of solution). Alternatively, the concentration of TMAH in the strip solution may be greater than 2.72 (Yow/v (or 2.72 grams of solute per 100 milliliters (ml) of solution). Conventional strip solutions have a normality (N) of 0.26 or less. For example, TMAH-based strip solutions are readily available from a commercial vendor with a normality of 0.26. The increase of the normality (N) in excess of 0.26 leads to an increase in substrate throughput for the double patterning process and a decrease in substrate defectivity which affects device yield.

In each embodiment, the freeze process creates a protective layer, extending partly or wholly through the first pattern122, that protects the first pattern122in the first layer of radiation-sensitive material120from subsequent lithographic processes, such as coating, exposing, developing, and slimming processes, hence, “freezing” the first layer of radiation-sensitive material120to form the frozen first layer of radiation-sensitive material120′ characterized by the first reduced CD.

The first layer of radiation-sensitive material, whether it be a thermally curable freeze resist, an EM curable freeze resist, or a chemically curable freeze resist, may include a material that exhibits cross-linking when thermally treated, radiatively treated, or chemically treated. Additionally, the chemical freeze material may include any removable material that may cause cross-linking in a layer of radiation-sensitive material. The chemical freeze material may include a polymeric material. For example, these materials may include materials commercially available from JSR Micro, Inc. (1280 North Mathilda Avenue, Sunnyvale, Calif. 94089), including, for example, FZX F112 freeze material. Alternatively, for example, these materials may include materials commercially available from Rohm and Haas, a wholly owned subsidiary of Dow Chemical Company (100 Independence Mall West, Philadelphia, Pa. 19106), including, for example, SC™ 1000 Surface Curing Agents (SCA).

As shown inFIG. 1E, the preparing of the pattern may further include forming a second layer of radiation-sensitive material140on substrate110. The second layer of radiation-sensitive material140may include a photo-resist. For example, the second layer of radiation-sensitive material140may comprise a 248 nm (nanometer) resist, a 193 nm resist, a 157 nm resist, an EUV (extreme ultraviolet) resists, or an electron beam sensitive resist. The second layer of radiation-sensitive material140may be formed by spin-coating the material onto substrate110. The second layer of radiation-sensitive material140may be formed using a track system. For example, the track system can comprise a Clean Track ACT® 8, ACT® 12, LITHIUS®, LITHIUS™ Pro™, or LITHIUS™ Pro V™ resist coating and developing system commercially available from Tokyo Electron Limited (TEL). Other systems and methods for forming a photo-resist film on a substrate are well known to those skilled in the art of spin-on resist technology. The coating process may be followed by one or more second PABs to heat the substrate110and one or more cooling cycles, following the one or more second PABs, to cool the substrate110.

As shown inFIG. 1F, the preparing of the pattern may further include preparing a second pattern142in the second layer of radiation-sensitive material140using a second lithographic process, wherein the second pattern142is characterized by a second CD144. The substrate110having the second layer of radiation-sensitive material140is aligned at a second alignment position in a radiation exposure system and imaged with second radiation having a second image pattern. The second radiation may be the same as the first radiation or different than the first radiation. The radiation exposure system may include a dry or wet photo-lithography system. The second image pattern may be formed using any suitable conventional stepping lithography system, or scanning lithography system. For example, the photo-lithography system may be commercially available from ASML Netherlands B.V. (De Run 6501, 5504 DR Veldhoven, The Netherlands), or Canon USA, Inc., Semiconductor Equipment Division (3300 North First Street, San Jose, Calif. 95134). Alternatively, the second image pattern may be formed using an electron beam lithography system.

The second layer of radiation-sensitive material140, having been exposed to the second image pattern, is subjected to a developing process in order to remove the second image pattern region, and form a second pattern142in the second layer of radiation-sensitive material140. The second pattern142may be characterized by a second critical dimension (CD)144. The second pattern142may include a second line pattern. The developing process can include exposing the substrate to a developing solution in a developing system, such as a track system. For example, the track system can comprise a Clean Track ACT® 8, ACT® 12, LITHIUS®, LITHIUS™ Pro™, or LITHIUS™ Pro V™ resist coating and developing system commercially available from Tokyo Electron Limited (TEL). The developing process may be preceded by one or more second PEBs to heat the substrate110and one or more cooling cycles, following the one or more second PEBs, to cool the substrate110.

The performing the CD slimming process may further include, as shown inFIG. 1G, performing a second CD slimming process to reduce the second CD144to a second reduced CD146, thus leaving behind a mandrel pattern150having the first pattern122and the second pattern142.FIG. 3illustrates a CD slimming process, andFIGS. 4A and 4Bprovide exemplary data for the CD slimming process.

In230and as shown inFIG. 1H, a material layer160is conformally deposited over the pattern with the reduced CD, wherein the pattern with the reduced CD may include the mandrel150including the first pattern122with the first reduced CD126and the second pattern142with the second reduced CD146. The technique of conformally depositing material layer160may include a CVD (chemical vapor deposition) process, a plasma enhanced CVD process, an atomic layer deposition (ALD) process, a plasma enhanced ALD process, or more generally, a monolayer deposition process.

The material layer160may include an oxide, a nitride, or an oxynitride. For example, the material layer160may include silicon oxide (SiOx), silicon nitride (SiNy), or silicon oxynitride (SiOxNy). However, the material layer160may include other materials.

In240and as shown inFIG. 11, the material layer160is partially removed using an etching process to expose a top surface164of the pattern, such as mandrel pattern150, and open a portion of the material layer160at a bottom region163between adjacent features of the pattern. As a result, a remaining portion162of the material layer160is retained on sidewalls165of the pattern. The etching process may include any combination of a wet or dry etching process. The dry etching process may include a dry plasma etching process or a dry non-plasma etching process. In one embodiment, a dry plasma etching process using plasma formed of a process composition containing CxFyand/or CxFyH, is contemplated.

In250and as shown inFIG. 1J, the pattern, such as the mandrel pattern150including the first pattern122with the first reduced CD126and the second pattern142with the second reduced CD146, is removed using one or more etching processes to leave a final pattern170comprising the remaining portion162of the material layer160that remained on the sidewalls165of the pattern. As a result, final pattern170may include a quadruple pattern originating from the first and second patterns (122,142). The one or more etching processes may include any combination of wet or dry etching processes. The dry etching processes may include dry plasma etching processes or dry non-plasma etching processes. In one embodiment, a wet etching process is contemplated. In an alternate embodiment, a dry plasma etching process using plasma formed of a process composition containing oxygen is contemplated.

Thereafter, the final pattern170, including the remaining portion162of the material layer160, is transferred to an underlying layer of the substrate110using one or more etching processes. The one or more etching processes may include any combination of wet or dry etching processes. The dry etching processes may include dry plasma etching processes or dry non-plasma etching processes.

As illustrated pictorially inFIG. 3, the CD slimming process, such as the first CD slimming process and/or the second CD slimming process referred to above, comprises a process sequence300beginning with preparing a layer of radiation-sensitive material320overlying a substrate310. As described above, following the exposure of the layer of radiation-sensitive material320to electromagnetic (EM) radiation in the photo-lithography system, the layer of radiation-sensitive material320is developed by exposing the layer of radiation-sensitive material320to a first developing solution, thus, leaving behind a pattern321having CD325. During the exposure of the layer of radiation-sensitive material320to EM radiation, a (cross-hatched) portion of the pattern321is exposed to EM radiation of intermediate intensity, yet remains following exposure to the first developing solution.

In301, the layer of radiation-sensitive material320is developed further by exposing the layer of radiation-sensitive material320to a second developing solution at an elevated temperature. In doing so, the second developing solution at the elevated temperature removes the (cross-hatched) portion of the pattern321that is exposed to EM radiation of intermediate intensity leaving behind an intermediate pattern322with an intermediate reduced CD326. As an example, the second developing solution may include a TMAH-containing solution elevated to a hot develop temperature greater than or equal to about 23 degrees C. Alternatively, as an example, the second developing solution may include a TMAH-containing solution elevated to a hot develop temperature greater than or equal to about 25 degrees C. Alternatively, as an example, the second developing solution may include a TMAH-containing solution elevated to a hot develop temperature greater than or equal to about 30 degrees C. Alternatively, as an example, the second developing solution may include a TMAH-containing solution elevated to a hot develop temperature greater than or equal to about 23 degrees C. and less than or equal to about 50 degrees C. Alternatively yet, as an example, the second developing solution may include a TMAH-containing solution elevated to a hot develop temperature greater than or equal to about 30 degrees C. and less than or equal to about 50 degrees C. In this process step, the concentration of the developing solution, the temperature, and the time for exposure are process parameters that may be adjusted to achieve pattern CD control.

In302, the intermediate pattern322with intermediate reduced CD326is treated with an acid (represented with “+” signs, and/or H+) solution. As an example, an acid-containing solution may be applied to the layer of radiation-sensitive material320with intermediate reduced CD326via spin-coating, as described above. In this process step, the concentration of the acid-containing solution, the temperature, and the time for exposure are process parameters that may be adjusted to achieve pattern CD control.

In303, the layer of radiation-sensitive material320is elevated in temperature to diffuse the acid into the pattern in the layer of radiation-sensitive material320. As an example, the layer of radiation-sensitive material320is elevated to a bake temperature greater than or equal to about 50 degrees C. Alternatively, as an example, the layer of radiation-sensitive material320is elevated to a bake temperature ranging from about 50 degrees C. to about 180 degrees C. In this process step, the temperature and the time for exposure are process parameters that may be adjusted to achieve pattern CD control.

In304, the layer of radiation-sensitive material320is developed further yet by exposing the layer of radiation-sensitive material320to a third developing solution. In doing so, the third developing solution produces a final pattern323in the layer of radiation-sensitive material320with a reduced CD335. As an example, the third developing solution may include a TMAH-containing solution at room temperature. In this process step, the concentration of the developing solution, the temperature, and the time for exposure are process parameters that may be adjusted to achieve pattern CD control.

Additional details for a CD slimming process may be found in U.S. Patent Application Publication Serial No. 2010/0291490A1, entitled “Resist Pattern Slimming Treatment Method”. Other details for a CD slimming process may be found in U.S. patent application Ser. No. 12/751,362, entitled “Method of Slimming Radiation-Sensitive Material Lines in Lithographic Applications” and filed on Mar. 31, 2010, or U.S. patent application Ser. No. 13/077,833, entitled “Method of Slimming Radiation-Sensitive Material Lines in Lithographic Applications” and filed on Mar. 31, 2011.

As shown inFIGS. 4A and 4B, a CD slimming process is performed to reduce a first line CD410of about 50 nm (nanometers) to a second line CD420of about 29.2 nm.

At least one process parameter for the first CD slimming process, the second CD slimming process, the freeze process, the first lithographic process, or the second lithographic process, or any combination of two or more thereof may be optimized to prevent collapse of said first pattern and said second pattern. Further, at least one process parameter for the first CD slimming process, the second CD slimming process, the freeze process, the first lithographic process, or the second lithographic process, or any combination of two or more thereof may be optimized to produce the second reduced CD in the second pattern while minimally impacting the first reduced CD in the first pattern that has been subjected to the freeze process.

As an example, the first CD for the first pattern and/or the second CD for the second pattern may be adjusted to achieve optimal printing of the first and second patterns with reduced CD. Alternatively, as an example, the amount of reduction between the first CD and the first reduced CD and/or the amount of reduction between the second CD and the second reduced CD may be adjusted to achieve optimal printing of the first and second patterns with reduced CD.

In one embodiment, the second CD slimming process may be designed to achieve the second reduced CD in the second pattern, while minimally impacting the first reduced CD in the first pattern. For example, the first lithographic process and the second lithographic process may be performed to print a first CD and a second CD that are substantially or approximately equivalent. Thereafter, the first CD slimming process reduces the first CD to the first reduced CD, and the second CD slimming process reduces the second CD to the second reduced CD, while not impacting the first reduced CD, such that the first reduced CD and the second reduced CD are substantially or approximately equivalent.

In an alternate embodiment, the second CD slimming process may be designed to achieve reduction of both the first reduced CD and the second CD. For example, the first lithographic process and the second lithographic process may be performed to achieve a first CD and a second CD, wherein the first CD is printed larger than the second CD. Additionally, for example, the first CD may be printed up to about 5% larger than the second CD. Additionally, for example, the first CD may be printed up to about 10% larger than the second CD. Additionally, for example, the first CD may be printed up to about 15% larger than the second CD. Additionally, for example, the first CD may be printed up to about 25% larger than the second CD. Additionally, for example, the first CD may be printed about 25% to about 50% larger than the second CD. Additionally yet, for example, the first CD may be printed about 50% to about 75% larger than the second CD. Thereafter, the first CD slimming process reduces the first CD to the first reduced CD, and the second CD slimming process reduces the second CD to the second reduced CD, while further reducing the first reduced CD to a third reduced CD, such that the third reduced CD and the second reduced CD are substantially or approximately equivalent.

As shown inFIG. 5, sub-30 nm (nanometer), 1:1 pitch line patterns containing a first line pattern510and a second line pattern520may be produced. Additionally, sub-25 nm (nanometer), 1:1 pitch line patterns may be produced, and even sub-20 nm (nanometer), 1:1 pitch line patterns may be produced. For example, using a thermally curable freeze resist as the first layer of radiation-sensitive material, the inventors have discovered that sub-20 nm (nanometer), 1:1 pitch line patterns may be produced by printing the first CD larger than the second CD using the first and second lithographic processes, respectively, and optimizing the second CD slimming process. Additionally, for example, using a thermally curable freeze resist as the first layer of radiation-sensitive material, the inventors expect that sub-10 nm (nanometer), 1:1 pitch line patterns may be produced by using a LFLE technique to produce a double pattern, printing the first CD larger than the second CD using the first and second lithographic processes, respectively, optimizing the second CD slimming process, and using the double pattern resulting from the LFLE technique as a mandrel in a sidewall image transfer technique.

Although only certain embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention.