EUV photoresist and underlayer adhesion modulation

Abstract

Embodiments disclosed herein include a method of developing a patterned stack. In one embodiment, the method includes providing a patterned stack, where the patterned stack includes a bottom layer and a photoresist over the bottom layer, and where the bottom layer and the photoresist have a first adhesion strength. The method may further include exposing and developing the photoresist with electromagnetic radiation and a developer, wherein dross remains on a surface of the underlayer. In one embodiment, the method further includes disposing the bottom layer such that the bottom layer has a second adhesion strength with the dross, and removing the dross.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of U.S. Patent Application No. 18 / 379,106, filed on October 11, 2023, which claims the benefit of U.S. Provisional Application No. 63 / 430,596, filed on December 6, 2022, the entire content of which is incorporated herein by reference. Technical field

[0003] Embodiments of the present disclosure relate to the field of semiconductor processing, and in particular, to methods of forming photoresists having an underlying layer for adhesion modulation. Background art

[0004] Lithography has been used in the semiconductor industry for decades to create 2D and 3D patterns in microelectronic devices. The lithography process involves an underlying layer and a spin - coated deposition film (photoresist) above the underlying layer. These spin - coated films can include some chemical additives (such as promoters) for dose reduction. The process can continue by irradiating the film (exposure) with an energy source in a selected pattern and removing (etching) the exposed (positive tone) or non - exposed (negative tone) regions of the film by dissolving them in a solvent. A bake is performed to drive off the remaining solvent. Spin - coating the underlying solution has some drawbacks, especially in the case of extreme ultraviolet (EUV) lithography operations for smaller pitch features. For example, the drawbacks may include compound uniformity and poor adhesion to the photoresist.

[0005] The photoresist should be a radiation - sensitive material, and upon irradiation, a chemical transformation occurs in the exposed portion of the film, which changes the solubility between the exposed and non - exposed regions. Using this solubility change, the exposed or non - exposed regions of the photoresist are removed (etched). Now, the photoresist is developed, and the pattern can be transferred to the thin film or substrate of the underlying layer by etching. After transferring the pattern, the residual photoresist is removed, and repeating this process multiple times can result in 2D and 3D structures for microelectronic devices.

[0006] In the lithography process, some properties are important. Such important properties include sensitivity, resolution, low line edge roughness (LER), line width roughness (LWR), etch resistance, and the ability to form thinner layers. When the sensitivity is high, the energy required to change the solubility of the deposited film is low. This enables higher efficiency in the lithography process. Resolution and LER determine how narrow features can be achieved in the lithography process. Pattern transfer requires materials with higher etch resistance to form deep structures. Materials with higher etch resistance also enable thinner films. Thinner films improve the efficiency of the lithography process. LER and LWR are random effects in the lithography process. They can be at least partially related to the UV light - material interaction process (such as UV absorption, secondary electron generation, and back exposure from the underlying layer) and / or the photoresist - underlying layer interaction (e.g., adhesion). Summary of the Invention

[0007] Embodiments disclosed herein include methods of developing a patterned stack. In one embodiment, the method includes providing a patterned stack, where the patterned stack includes an underlying layer and a photoresist over the underlying layer, and where the underlying layer has a first adhesion strength with the photoresist. The method may further include exposing and developing the photoresist with electromagnetic radiation and a developer, where scum remains on the surface of the underlying layer. In one embodiment, the method further includes treating the underlying layer such that the underlying layer has a second adhesion strength with the scum, and removing the scum.

[0008] Embodiments disclosed herein may also include a method of patterning a substrate, the method including providing a patterned stack over the substrate. In one embodiment, the patterned stack includes a first underlying layer, a second underlying layer on the first underlying layer, and a photoresist over the second underlying layer. In one embodiment, the method further includes exposing the patterned stack to electromagnetic radiation, and developing the photoresist in the patterned stack. In one embodiment, the method further includes modifying the second underlying layer such that the adhesion strength to the photoresist is reduced, and removing any scum over the second underlying layer.

[0009] Embodiments disclosed herein may include a patterned stack. In one embodiment, the patterned stack includes a first underlying layer and a second underlying layer over the first underlying layer, where the second underlying layer has a thickness of up to about 5 nm, and where the second underlying layer has a hydrophobic surface. In one embodiment, the patterned stack may further include a photoresist over the second underlying layer, where the photoresist has a hydrophobic surface. Brief Description of the Drawings

[0010] Figure 1A is a cross - sectional view of a device including a photoresist layer disposed over an adhesion - promoting underlying layer, according to one embodiment.

[0011] Figure 1B FIG. Figure 1B is a cross-sectional view of a device including a photoresist layer disposed over a pair of adhesion promoting underlayers, in accordance with one embodiment.

[0012] Figure 2A FIG.

[0012] is a schematic view of a device having a photoresist and an underlayer, showing chemical bonds between the layers, in accordance with one embodiment.

[0013] Figure 2B FIG. Figure 2B is a schematic view of a device after the photoresist has been exposed to electromagnetic radiation, in accordance with one embodiment.

[0014] Figure 2C FIG. Figure 2C is a schematic view of a device after the photoresist has been developed and scum remains over the topmost underlayer, in accordance with one embodiment.

[0015] Figure 2D FIG. Figure 2D is a schematic view of a device after the underlayer has been exposed to a treatment that converts chemical bonds from hydrophobic to hydrophilic, in accordance with one embodiment.

[0016] Figure 2E FIG. Figure 2E is a cross-sectional view of a device after scum has been removed, in accordance with one embodiment.

[0017] Figure 3 FIG. Figure 3 is a process flow diagram of a process for patterning a photoresist layer including a pair of underlayers, in accordance with one embodiment.

[0018] Figure 4A FIG. Figure 4A is a schematic view of a device including a substrate, an underlayer, and a photoresist, in accordance with one embodiment.

[0019] Figure 4B FIG. Figure 4B is a schematic view of a device after the photoresist has been patterned and the underlayer has been treated, in accordance with one embodiment.

[0020] Figure 5A FIG. Figure 5A is a cross-sectional view of a device having an adhesion layer between the photoresist and a low absorption layer, in accordance with one embodiment.

[0021] Figure 5B FIG. Figure 5B is a cross-sectional view of a device having a low absorption layer under the photoresist, in accordance with one embodiment.

[0022] Figure 6A FIG. Figure 6A is a cross-sectional view of a device having a multi-layer patterned stack, in accordance with one embodiment.

[0023] Figure 6B FIG. Figure 6B is a cross-sectional view of a device having a multi-layer patterned stack with an anti-reflection coating (ARC), in accordance with one embodiment.

[0024] Figure 7A block diagram of an exemplary computer system in accordance with one embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0025] Methods of forming a photoresist having an underlying layer for adhesion modulation are described herein. In the following description, in order to provide a thorough understanding of embodiments of the present disclosure, numerous specific details are set forth, such as hot gas phase processes and material schemes for developing photoresists. It will be apparent to those skilled in the art that embodiments of the present disclosure may be practiced without these specific details. In other instances, conventional aspects, such as integrated circuit fabrication, are not described in detail so as not to unnecessarily obscure embodiments of the present disclosure. Further, it should be understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.

[0026] To provide context, photoresist systems used in extreme ultraviolet (EUV) lithography are inefficient. That is, existing photoresist material systems for EUV lithography require high doses in order to provide the solubility switch necessary to develop the photoresist material. One type of resist system for EUV lithography is a chemically amplified resist (CAR) system. A disadvantage of CAR systems is the limited CAR-underlying layer interface strength (adhesion). In particular, the bonding between the two layers is achieved through van der Waals forces. In many cases, a high adhesion strength between the photoresist and the underlying layer is a desirable property. A strong adhesion strength allows for the formation of high aspect ratio features without the risk of pattern collapse, pattern peeling, or other pattern defects. By tuning the underlying layer to form a strong bond with the overlying photoresist, a high adhesion strength can be provided. CAR photoresists are typically hydrophobic materials. Therefore, the underlying layer is also formed as a hydrophobic material to improve the bonding between the two layers.

[0027] However, strong adhesion properties can have negative drawbacks. For example, when the adhesion strength between layers is strong, it is difficult to completely remove the exposed photoresist with a developer solution. Sometimes the unwanted residual photoresist material can be referred to as scum. The presence of scum on the underlying layer can lead to patterning defects that ultimately transfer to the underlying layer and substrate. As a result, high-quality pattern transfer is not possible.

[0028] Accordingly, the embodiments disclosed herein include a modifiable underlying layer. As used herein, a modifiable layer can be a layer that can change its chemical composition or change the chemical nature of dangling bonds. For example, a treatment disclosed herein can convert a hydrophobic material into a hydrophilic material. When the underlying layer is hydrophilic, the bonding strength between the underlying layer and the overlying hydrophobic photoresist is reduced. This makes scum removal easier. In one embodiment, the treatment can include exposing the underlying layer to an alkaline solution. An alkaline solution (e.g., approximately 3% tetramethylammonium hydroxide (TMAH) and 97% water) is used during the lithography development process. Since the alkaline solution already has water, the underlying layer does not need to undergo an additional treatment to react with water to form OH bonds. Thus, the method described herein can be easily added to existing lithography processes.

[0029] It will be appreciated that a balance needs to be achieved between a high adhesion strength for patterning and a low adhesion strength for scum development and removal. Accordingly, some embodiments described herein include a dual underlying layer structure. A first underlying layer on a substrate can include a combination of materials that are highly reactive to a treatment, and a second underlying layer on the first underlying layer can be tuned for adhesion. More particularly, the second underlying layer can be thin (e.g., approximately 5 nm or less) and porous. This allows chemical changes in the first underlying layer to propagate through the second underlying layer to modify the interface between the second underlying layer and the photoresist.

[0030] In other embodiments, a single underlying layer is used. The underlying layer can include a doped amorphous SiC:H material. For example, the dopant can include Si, Ge, B, or P. In one particular embodiment, a boron dopant can have B2H6 co-flowing with the SiC:H precursor (e.g., trimethylsilane). The doped element readily reacts with water in an alkaline solution to form OH bonds, thereby converting the surface into a hydrophilic surface. The hydrophilic surface reduces the adhesion strength and makes scum removal easier.

[0031] In yet another embodiment, an adhesion layer (e.g., including SiCH, SiOC, etc.) can be provided on the low absorption layer. The adhesion layer described herein is formed by a CVD / ALD process, and this process can be easily modulated to control the overall composition, thereby improving surface bonding. For example, the adhesion layer can be modulated between silicon-rich and carbon-rich, which is difficult to achieve with spin-on solutions. However, in some embodiments, modulating the overall composition may not be sufficient to affect surface bonding. Therefore, additional surface treatment may be required to enhance surface capping (such as -CH3 capping). In one embodiment, the low absorption layer is also a CVD / ALD film, which can be modulated from silicon-rich to carbon-rich in a similar manner. However, the low absorption layer is for a different purpose and can have a different composition from the adhesion layer to provide optimal coupling and / or combination of the layers. The adhesion layer provides improved coupling with the overlying photoresist layer, while the low absorption layer improves pattern development. The embodiments disclosed herein can be used in combination with a dual bottom layer approach. For example, the bottom layer under the thin adhesion layer can react with water to form -OH bonds for modulating the adhesion between the CAR and the adhesion promoting layer, and / or is a low UV absorption layer, which can also reduce random effects such as line roughness (e.g., LER and LWR) and local CD uniformity (LCDU) reduction.

[0032] In the embodiments disclosed herein, a photoresist layer is generally described. The photoresist layer can include EUV resist materials, such as metal-oxo resist systems. In other embodiments, the photoresist layer can generally include a chemically amplified resist (CAR). The photoresist layer is adapted to be patterned in various electromagnetic radiations, including EUV, deep ultraviolet (DUV), ultraviolet (UV), etc. More generally, the photoresist layer described herein includes electromagnetic radiation-sensitive materials. The photoresist layer can have a hydrophobic surface provided by chemical bonds (such as CH3, etc.).

[0033] Now referring Figure 1A , a cross-sectional view of a device 100 according to one embodiment is shown. The device 100 can include a substrate 101. The substrate 101 can include layers to be patterned using a lithography process. The substrate 101 can include materials typically patterned for forming structures in semiconductor devices. For example, the substrate 101 can include semiconductor materials (e.g., silicon), metal layers, dielectric layers, or insulating layers. In some embodiments, the substrate 101 can also include layers that assist in transferring the pattern into the substrate 101. For example, the additional layers can include hard mask layers, antireflection coatings (ARC), and the like.

[0034] In one embodiment, device 100 may further include an adhesion promoting layer 110. The adhesion promoting layer 110 may be a material capable of achieving good adhesion strength between the substrate 101 and the overlying photoresist 120. The adhesion promoting layer 110 may have a surface that matches the hydrophobicity of the photoresist 120. Typically, the photoresist 120 is a hydrophobic material having CH3 dangling bonds. Thus, the adhesion promoting layer 110 may also include a hydrophobic surface capped with CH3. An example of such a material is hexamethyldisilazane (HMDS), and another CVD-based example is SiC:H or the like. In some embodiments, the adhesion promoting layer 110 may be further doped. For example, dopants such as silicon and boron may be provided in the adhesion promoting layer 110.

[0035] The adhesion promoting layer 110 may be a material having a modifiable attraction to water. For example, during the exposure and development of the overlying photoresist 120, the adhesion promoting layer 110 exhibits strong bonding with the photoresist through hydrophobic interactions. After development, any residual scum is removed. When the adhesion between the adhesion promoting layer 110 and the photoresist 120 decreases, the removal of the scum becomes easier. Thus, the attraction of the adhesion promoting layer 110 to water can be transformed into hydrophilicity. The hydrophobic first material (e.g., the photoresist 120) will tend to repel the hydrophilic second material (e.g., the modified adhesion promoting layer 110). The adhesion promoting layer 110 can be transformed into a hydrophilic surface by applying an alkaline solution. Water can react with the surface to form OH chemical bonds. Therefore, the scum can be more easily removed from the surface of the adhesion promoting layer 110, which provides better pattern transfer.

[0036] Now referring Figure 1B , a cross-sectional view of a device 100 according to an additional embodiment is shown. In one embodiment, the device 100 may include a substrate 101. Figure 1B The substrate 101 in Figure 1A may be substantially similar to the substrate 101 in

[0037] Figure 1BThe device 100 in can include a dual bottom layer solution instead of having a single adhesion promoting layer 110. A first bottom layer 115 can be disposed on the substrate 101, and a second bottom layer 110 can be disposed on the first bottom layer 115. The dual bottom layer structure 115 / 110 can include materials adapted to switch the surface between hydrophobic and hydrophilic conditions. In addition to providing a switch between attraction and repulsion of water, the dual bottom layer structure 115 / 110 allows for improved adhesion to the photoresist 120. This is because the second bottom layer 110 can be tuned to have a high adhesion strength, while the first bottom layer 115 can be tuned to be easily converted into a hydrophilic structure.

[0038] In one embodiment, the second bottom layer 110 can be a relatively thin layer. For example, the second bottom layer 110 can have a thickness of about 10 nm or less, or about 5 nm or less. Additionally, the second bottom layer 110 can be a porous material. Due to the small thickness and porosity of the second bottom layer 110, the hydrophobic-to-hydrophilic change in the first bottom layer 115 can easily propagate through the second bottom layer 110. In one embodiment, the first bottom layer 115 can include materials having Si-H bonds, Si-CH3 bonds, B-H bonds, etc. When exposed to an alkaline solution including water or the like, the bonds of the first bottom layer 115 can be easily converted to OH-terminated.

[0039] In one embodiment, the first bottom layer 115 can have a thickness greater than that of the second bottom layer 110. For example, the first bottom layer 115 can have a thickness of up to about 20 nm, up to about 30 nm, or up to about 50 nm. The combined thickness of the first bottom layer 115 and the second bottom layer 110 can be greater than the thickness of the photoresist 120. However, in other embodiments, the photoresist 120 can be thicker than one or both of the first bottom layer 115 and the second bottom layer 110.

[0040] In one embodiment, the photoresist 120 can be any suitable photoresist material. In one case, the photoresist 120 is any suitable CAR material. The photoresist 120 can be sensitive to EUV radiation, DUV radiation, or UV radiation.

[0041] Now refer to Figures 2A to 2E , according to one embodiment, a series of cross-sectional views depicting a process for patterning a photoresist 220 are shown. In the illustrated embodiment, the layers are separated from each other to more clearly illustrate the chemical bonding between the layers (e.g., dangling bonds on the surfaces of the layers). It should be understood that in reality, the different layers are in contact with each other through the adhesion strength provided by chemical bonds.

[0042] Now refer to Figure 2A, showing a cross-sectional view of a device 200 according to an embodiment. In one embodiment, the device 200 may include a substrate 201. The substrate 201 may be a material to be patterned (e.g., semiconductor, metal, dielectric, insulator, etc.). The substrate 201 may also include some pattern transfer layers (e.g., hard mask, ARC, etc.)

[0043] In one embodiment, a first bottom layer 215 may cover the substrate 201. The first bottom layer 215 may include a material having a hydrophobic surface. For example, the dangling bond 214 may include H, etc. Although only the dangling bond of H is shown in Figure 2A , in some embodiments, CH3 bonds may also be present on the surface of the first bottom layer 215. In one embodiment, the first bottom layer 215 may further include Si-H bonds, Si-CH3 bonds, B-H bonds, etc. The characteristics of these bonds may be hydrophobic.

[0044] In one embodiment, a second bottom layer 210 may be disposed above the first bottom layer 215. The second bottom layer 210 may have a bond 211 between the first bottom layer 215 and the second bottom layer 210. As shown, the bond 211 may include H bonds and CH3 bonds. The bond 211 may have the same polarity as the bond 214 on the first bottom layer. For example, in some embodiments, the bond 211 may be hydrophobic. Due to the matching hydrophobicity in the bond 211 and the bond 214, the first bottom layer 215 and the second bottom layer 210 have strong adhesion to each other, as indicated by the check mark between the bond 211 and the bond 214.

[0045] In one embodiment, the second bottom layer 210 may be a relatively thin layer. For example, the second bottom layer 210 may have a thickness of up to about 10 nm, up to about 5 nm, or up to about 2 nm. The second bottom layer 210 may also be a porous material. Due to the thin and porous nature of the second bottom layer 210, the surface condition of the first bottom layer 215 may be transmitted through the second bottom layer 210. That is, when the first bottom layer 210 has a bond 214 that is essentially hydrophobic, the second bottom layer 215 will have a bond 212 that is essentially also hydrophobic. Similarly, when the bond 214 turns hydrophilic, the bond 212 will also turn hydrophilic.

[0046] In this way, the combination of the first bottom layer 215 and the second bottom layer 210 can be used to provide a patterned stack that enables higher adhesion to the photoresist 220 at one time point and lower adhesion to the photoresist at a second time point. In particular, Figure 2A the shown bond 212 is essentially hydrophobic (e.g., CH3 and H) and firmly bonds with the hydrophobic bond 221 (e.g., CH3) of the photoresist 220.

[0047] The dual bottom layer structure is particularly beneficial as it allows for tuning of the patterned stack for adhesion and scum removal. The second bottom layer 210 in direct contact with the photoresist 220 can be specifically tuned for adhesion strength, while the first bottom layer 215 can be a material capable of easily switching between hydrophobic and hydrophilic properties. Since the second bottom layer 210 is relatively thin and porous, changes in the first bottom layer 215 can easily modify the surface conditions of the overlying second bottom layer 210. In this way, adhesion to residual scum after developing the photoresist can be reduced, and the scum can be easily removed.

[0048] It should be understood that the formation of the dual bottom layer architecture can be achieved by using a dry deposition process. For example, both the first bottom layer 215 and the second bottom layer 210 can be formed using a chemical vapor deposition (CVD) process, an atomic layer deposition (ALD) process, or a similar process. In one embodiment, the photoresist 220 can also be formed using a dry deposition process. In some embodiments, the first bottom layer 215, the second bottom layer 210, and the photoresist 220 can be formed in a single deposition chamber.

[0049] In one embodiment, the photoresist 220 can be any suitable photosensitive material used in semiconductor manufacturing. For example, the photoresist 220 can be any other suitable CAR material. The photoresist 220 can be sensitive to EUV, DUV, or UV electromagnetic radiation. In some embodiments, the electromagnetic radiation can change the chemical properties of the photoresist 220. In some cases, exposure to electromagnetic radiation can also change the chemical properties of one or both of the first bottom layer 215 and the second bottom layer 210.

[0050] Now referring Figure 2B , a cross-sectional view of a device 200 according to one embodiment is shown. As shown, electromagnetic radiation 251 passes through the mask 250 in order to expose a portion of the photoresist 220. As indicated by the different shading, the exposed region 222 can have a chemical composition different from that of the unexposed region of the photoresist 220. For example, the exposed region 222 can be more highly cross-linked than the unexposed region. In the illustrated embodiment, a mask 250 having an opening is used to selectively expose regions of the photoresist 220. However, it should be understood that the electromagnetic radiation can alternatively be reflected towards selected regions of the photoresist 220.

[0051] In one embodiment, the first bottom layer 215 and the second bottom layer 210 can also be changed by exposure to the electromagnetic radiation 251. For example, an exposed region 213 can be provided in the second bottom layer 210, and an exposed region 217 can be provided in the first bottom layer 215. Although shown as reacting to the electromagnetic radiation 251, it should be understood that one or both of the first bottom layer 215 and the second bottom layer 210 may not react to the electromagnetic radiation 251.

[0052] In one embodiment, exposure to electromagnetic radiation can alter bond layers 214, 211, and 212. As Figure 2B shown, the exposed portions of the bonds are decorated with an asterisk (*). The asterisk indicates that the bond has increased energy. This further improves the subsequent reaction to convert hydrophobic bonds to hydrophilic bonds, which will be described in more detail below.

[0053] Referring now to Figure 2C , a cross-sectional view of device 200 after a development process according to one embodiment is shown. In one embodiment, the development process can result in the removal of substantially all of the exposed regions 222 of photoresist 220. However, scum 223 or other remnants of photoresist 220 may remain in the openings 240. As indicated by the check marks between bonds 221 and 212, scum 223 remains firmly attached to the second underlying layer 210. Due to the strong adhesion between scum 223 and the second underlying layer 210, it is difficult to remove scum 223. Thus, the pattern transfer to the underlying layer will be sub-optimal. The development process can be a dry development process or a development process with liquid development chemicals.

[0054] Referring now to Figure 2D , a cross-sectional view of device 200 during a treatment according to one embodiment is shown. The treatment can be exposure to an alkaline solution 255. The alkaline solution 255 can contain H2O or other oxygen-containing chemicals. The alkaline solution 255 can react with the first underlying layer 215. The first underlying layer 215 can be readily converted such that the exposed regions 217 of bond layer 216 are converted to OH bonds. Similarly, bond layer 218 can be converted to OH bonds. Since bond layers 216 and 218 have the same bond type (i.e., hydrophilic), there is a strong bonding between the first underlying layer 215 and the second underlying layer 210, as indicated by the check marks.

[0055] Similarly, the bond layer 219 on the second underlying layer 210 can be converted to a hydrophilic bond type. The bond layer 219 can be converted by exposure to the alkaline solution 255 and / or by changing to bond layers 216 and 218. Due to the small thickness of the second underlying layer 210 and the porosity of the second underlying layer 210, it is possible for the hydrophilic type bonds to propagate through the second underlying layer 210.

[0056] As shown, the bond layer 219 of scum 223 no longer has a strong bond with the bond layer 221 of the second underlying layer 210, as indicated by the X-mark between the two. Since scum 223 has a hydrophobic nature (e.g., CH3 bonds) while the second underlying layer 210 has a hydrophilic nature (e.g., OH bonds), a weak bond is formed. Since the adhesion between the two layers is reduced, it is now easier to remove scum 223.

[0057] Referring now to Figure 2E, showing a cross-sectional view of device 200 after removal of scum 223 according to one embodiment. In the illustrated embodiment, the layers are now shown in direct contact with each other, and the bonding layer is not shown. However, it should be understood that the bonding layer as Figure 2D shown still exists, but is omitted for simplicity. As shown, photoresist 220 now has a clean opening 240 to expose regions 217 and 213 of the first underlying layer 215 and the second underlying layer 210, respectively. After removal of scum 223, the pattern of opening 240 can be transferred into underlying layers 210 and 215 and substrate 201.

[0058] Now referring to Figure 3 , showing a process flow diagram of a process 380 for scum removal according to one embodiment. Figure 3 The process 380 shown in Figures 2A to 2E can be substantially similar to the process described above with respect to

[0059] In one embodiment, process 380 may begin with operation 381, which includes forming a photoresist layer on the first underlying layer and the second underlying layer. In one embodiment, the second underlying layer is tuned to promote adhesion to the photoresist layer. For example, both the photoresist layer and the second underlying layer may have hydrophobic dangling bonds. In one embodiment, the second underlying layer may have a small thickness (e.g., up to about 10 nm, up to about 5 nm, or up to about 2 nm). The second underlying layer may also be porous. Thus, the surface properties of the underlying first underlying layer can propagate through the second underlying layer.

[0060] In one embodiment, process 380 may continue with operation 381, which includes patterning the photoresist layer by exposure to electromagnetic radiation and a developer. In an embodiment, the electromagnetic radiation may be EUV radiation, DUV radiation, UV radiation, etc. The development process may be a liquid development process or a dry development process. In one embodiment, the development process may result in residual scum at the bottom of the opening through the photoresist layer.

[0061] In one embodiment, process 380 may continue with operation 383, which includes modifying the second underlying layer to reduce adhesion to the residual scum on the second underlying layer. In one embodiment, the modification may be a treatment. The treatment may be exposing the first underlying layer and the second underlying layer to an alkaline solution. The first underlying layer may readily react with the alkaline solution to form OH bonds. Due to the thin and porous nature of the second underlying layer, the surface chemistry of the first underlying layer can propagate through the second underlying layer. In other embodiments, the alkaline solution may directly change the chemistry of the bonds on the second underlying layer. The modification causes the surface chemistry of the second underlying layer to change from hydrophobic to hydrophilic. Thus, the scum (hydrophobic) now has a weaker bond with the second underlying layer.

[0062] In one embodiment, process 380 may proceed to operation 384, which includes removing scum from the second underlying layer. Since the adhesion between the scum and the second underlying layer is reduced, the scum can be more easily removed. For example, a rinsing process or a similar process may be used to remove the scum. After removing the scum, the pattern in the photoresist layer can be transferred to the underlying layer and the substrate below.

[0063] Now refer to Figure 4A and Figure 4B , according to one embodiment, a pair of cross-sectional schematic views of a device 400 including treating an underlying layer to remove scum are shown.

[0064] Now refer to Figure 4A , a cross-sectional view of a device 400 is shown. The device 400 may include a substrate 401. The substrate 401 may be similar to any substrate structure described in more detail above. In one embodiment, an underlying layer 410 may be disposed on the substrate 401. A photoresist 420 may be disposed on the underlying layer 410. Although shown as spaced apart from the underlying layer 410, it should be understood that the photoresist 420 may be directly on the underlying layer 410. The spaced-apart relationship is shown to illustrate the presence of the bonding chemical 418.

[0065] In one embodiment, the underlying layer 410 may have a bonding chemical 418 including an amorphous SiC:H composition. The SiC:H combination may be doped with one or more dopant atoms. The dopant atoms may include Si, G e , B, P, or similar atoms. The dopant element is selected to easily react with water in an alkaline solution to form OH bonds. In Figure 4A , the dopant atoms are represented by X in the bonding chemical 418. As shown, the bonding chemical includes H bonds and CH3 bonds that provide a hydrophobic surface for the underlying layer 410. The bonding chemical 425 of the photoresist may be an organic compound, which also results in the formation of a hydrophobic surface. The matching hydrophobic surfaces result in a strong adhesion between the underlying layer 410 and the photoresist 420.

[0066] Now refer to Figure 4B , a cross-sectional view of the device 400 after exposure, development, and treatment according to one embodiment is shown. Exposure and development may result in the formation of an opening 440 through the photoresist 420. By using a treatment that converts the exposed portion of the underlying layer into a hydrophilic surface, residual scum can be removed from the opening 440. In particular, an alkaline solution is applied, and water easily reacts with the dopant to form OH bonds on the underlying layer surface. Since the surface is converted to a hydrophilic surface, the underlying layer 410 is no longer firmly attached to the scum. This makes the scum easy to remove (e.g., with a rinsing process).

[0067] Now refer to Figure 5A and Figure 5B, according to a pair of embodiments, a pair of cross-sectional views depicting a patterned stack for device 500 are shown. In Figure 5A the illustrated embodiment, device 500 includes a substrate 501 having stacks 561 and 562. Substrate 501 may be similar to any substrate described in more detail above. In one embodiment, stacks 561 and 562 may include any suitable materials. In particular, layer 562 may be a low-absorption layer. Low-absorption layer 562 may include SiCH and have C(H) bonds. The chemistry of low-absorption layer 562 may be selected to minimize absorption of EUV radiation.

[0068] In one embodiment, an adhesion layer 510 may be provided on low-absorption layer 562. Adhesion layer 510 may have a thickness of up to about 10 nm, up to about 5 nm, or up to about 2 nm. In one embodiment, adhesion layer 510 is a hydrophobic material that preferentially bonds to the overlying photoresist layer 520. Adhesion layer 510 may include SiCH, HMDS, SiOC, carbon, and the like. The surface of adhesion layer 510 may include H bonds or CH3 bonds. Photoresist layer 520 may have an opening 540. Photoresist layer 520 may also have a hydrophobic surface to facilitate bonding to adhesion layer 510.

[0069] Now referring to Figure 5B , a cross-sectional view of device 500 without adhesion layer 510 is shown according to one embodiment. In one embodiment, adhesion layer 510 may be removed when low-absorption layer 562 provides sufficient adhesion strength to the overlying photoresist layer 520.

[0070] Now referring to Figure 6A and Figure 6B , according to an alternative embodiment, a pair of cross-sectional views depicting a patterned stack are shown. Figure 6A and Figure 6B The illustrated embodiment may utilize any of the adhesion and release properties or systems described in more detail herein. That is, the embodiment may allow for an initial strong adhesion between photoresist layers, followed by a reduction in adhesion strength to allow for improved scum removal.

[0071] Now referring to Figure 6A , a cross-sectional view of device 600 is shown according to one embodiment. In one embodiment, device 600 may include a substrate 601. Substrate 601 may include layers that will be patterned using a lithography process. Substrate 601 may include materials typically patterned to form structures in semiconductor components. For example, substrate 601 may include semiconductor materials (e.g., silicon), metal layers, dielectric layers, or insulating layers. In some embodiments, substrate 601 may also include layers that help transfer the pattern into substrate 601. For example, additional layers may include hardmask layers, ARC, etc.

[0072] In one embodiment, a patterned stack can be provided on a substrate 601. The patterned stack can include a plurality of different layers. For example, the patterned stack can include a first layer 671, a second layer 672, and a third layer 673. In one embodiment, the first layer 671 can include one or more of silicon, oxygen, hydrogen, nitrogen, and carbon. In one embodiment, the second layer 672 can include one or more of silicon, amorphous silicon, oxygen, hydrogen, and nitrogen. In one embodiment, the third layer 673 can include at least carbon. For example, the carbon can be a CVD carbon layer, an ALD carbon layer, or the like. In some embodiments, an implanted substance (e.g., silicon, germanium, boron, phosphorus, iodine, and / or hydrogen) can be implanted into one or more of the layers 671 to 673 to change different properties such as adhesion strength, chemical reactivity, etc. A photoresist layer 620 can be disposed on the patterned stack. The photoresist layer 620 can be a metal oxide resist (MOR) or a chemically enhanced resist (CAR).

[0073] In a particular embodiment, the device 600 can include a stack having the following material layers. In one embodiment, the first layer 671 can include an oxide such as silicon oxide. The first layer 671 can have a thickness of up to about 100 nm. For example, the first layer 671 can have a thickness of about 50 nm or less. In one embodiment, the second layer 672 can include an amorphous silicon layer. The amorphous silicon layer can be formed by any suitable deposition process such as plasma enhanced CVD (PECVD). In some embodiments, the second layer 672 can have a thickness of up to about 50 nm. In a particular embodiment, the second layer 672 can have a thickness of about 20 nm or less. In one embodiment, the third layer 673 can include a carbon layer such as a CVD carbon layer. The third layer 673 can have a thickness of up to about 50 nm. For example, the third layer 673 can have a thickness of about 30 nm or less.

[0074] In yet another embodiment, the patterned stack can have the following material layers. In one embodiment, the first layer 671 can include silicon, oxygen, and nitrogen. For example, in some embodiments, the first layer 671 can include SiON. The second layer 672 can include silicon, oxygen, and hydrogen. In one embodiment, the third layer 673 can include the same components as the first layer 671. In the particular embodiments described herein, the third layer 673 can include silicon, oxygen, and nitrogen (e.g., SiON). The first layer 671, the second layer 672, and the third layer 673 can have a thickness of less than about For example, the first layer 671 can have a thickness of up to about The second layer 672 can have a thickness of up to about And the third layer 673 can have a thickness of up to about of thickness.

[0075] In yet another embodiment, the patterned stack can be constructed as follows. The first layer 671 can include an oxide, such as an oxide including silicon and oxygen (e.g., SiO2). The second layer 672 can include silicon. For example, the second layer 672 can include an amorphous silicon layer. In one embodiment, the third layer 673 can be any suitable underlying material. For example, the third layer can include silicon, carbon, and hydrogen (e.g., SiCH), HMDS, silicon, oxygen, and carbon (SiOC), etc. The first layer 671, the second layer 672, and the third layer 673 can each have a thickness of up to about 500 nm.

[0076] In yet another embodiment, the patterned stack can include an additional interface layer (not shown) between the substrate 601 and the first layer 671. For example, the interface layer can be considered an adhesion layer, a hard mask layer, or a similar layer. In some embodiments, the interface layer can include titanium and nitrogen. For example, in some embodiments, the interface layer can include TiN.

[0077] Now referring to Figure 6B , a cross-sectional view of a device 600 according to an additional embodiment is shown. Figure 6B The device 600 in Figure 6A can be substantially similar to the device 600 in

[0078] Figure 7 except that an anti-reflection coating (ARC) 675 is added on the third layer 673. The ARC 675 can be any suitable ARC material. For example, the ARC can include one or both of a dielectric ARC (DARC) or a bottom ARC (BARC). That is, in some embodiments, the ARC 675 can include at least two different layers. In some embodiments, the ARC 675 can have a thickness of up to about 40 nm. In a particular embodiment, the ARC 675 can have a thickness of up to about 20 nm.FIG. shows a schematic diagram of a machine in an exemplary form of computer system 700 within which a set of instructions for causing the machine to perform any one or more of the methods described herein may be executed. In alternative embodiments, the machine may be connected (e.g., networked) to other machines in a local area network (LAN), an intranet, an extranet, or the Internet. The machine may operate in a client-server network environment as a server or a client, or as a peer machine in a peer-to-peer (or distributed) network environment. The machine may be a personal computer (PC), a tablet computer, a set-top box (STB), a personal digital assistant (PDA), a cellular telephone, a network appliance, a server, a network router, a switch, or a bridge, or any machine capable of executing a set of instructions (sequentially or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is shown, the term "machine" shall also be taken to include any collection of machines (e.g., computers) that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methods described herein.

[0079] Exemplary computer system 700 includes a processor 702, a main memory 704 (e.g., read only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM)), a static memory 706 (e.g., flash memory, static random access memory (SRAM), MRAM, etc.), and an auxiliary memory 718 (e.g., a data storage device), which communicate with each other via a bus 730.

[0080] Processor 702 represents one or more general-purpose processing devices such as a microprocessor, a central processing unit, etc. More particularly, processor 702 may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing other instruction sets, or a processor implementing a combination of instruction sets. Processor 702 may also be one or more special-purpose processing devices such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), a network processor, etc. Processor 702 is configured to execute processing logic 726 for performing the operations described herein.

[0081] Computer system 700 may also include a network interface device 708. Computer system 700 may also include a video display unit 710 (e.g., a liquid crystal display (LCD), a light emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device 712 (e.g., a keyboard), a cursor control device 714 (e.g., a mouse), and a signal generation device 716 (e.g., a speaker).

[0082] The auxiliary storage 718 may include a machine-accessible storage medium (or more specifically, a computer-readable storage medium) 732 having stored thereon one or more sets of instructions (e.g., software 722) that embody any one or more of the methods or functions described herein. During execution of software 722 by the computer system 700, software 722 may also reside, in whole or in part, within the main memory 704 and / or within the processor 702, which also constitute machine-readable storage media. Software 722 may also be transmitted or received over the network 720 via the network interface device 708.

[0083] Although the machine-accessible storage medium 732 is shown as a single medium in the exemplary embodiment, the term "machine-readable storage medium" should be understood to include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) that store one or more sets of instructions. The term "machine-readable storage medium" should also be understood to include any medium that is capable of storing or encoding a set of instructions for execution by a machine and that causes the machine to perform any one or more of the methods of the present disclosure. Thus, the term "machine-readable storage medium" should be regarded as including, but not limited to, solid-state memories, optical and magnetic media.

[0084] According to an embodiment of the present disclosure, a machine-accessible storage medium has instructions stored thereon that cause a data processing system to perform a method of providing a photoresist stack having a first underlayer and a second underlayer. In one embodiment, the second underlayer has a thickness less than 5 nm and is tuned to have a high adhesion strength with the overlying photoresist layer. After patterning, the first underlayer and the second underlayer are treated with an aqueous alkaline solution. The solution converts the hydrophobic surfaces of the first underlayer and the second underlayer into hydrophilic surfaces with reduced bond strength to the photoresist layer. Any scum can then be easily rinsed off the stack.

[0085] Thus, a method for forming a photoresist stack with high adhesion and improved scum removal has been disclosed.

Claims

1. A method of developing a patterned stack, comprising: Providing a patterned stack, wherein the patterned stack includes a bottom layer and a photoresist on the bottom layer, and wherein the bottom layer and the photoresist have a first adhesion strength; Exposing and developing the photoresist with electromagnetic radiation and a developer, wherein scum remains on the surface of the bottom layer; Treating the bottom layer such that the bottom layer and the scum have a second adhesion strength; And Removing the scum.

2. The method of claim 1, wherein the bottom layer is hydrophobic before the treatment and hydrophilic after the treatment.

3. The method of claim 1, wherein the bottom layer includes H-termination and CH3-termination before the treatment.

4. The method of claim 3, wherein the bottom layer includes OH-termination after the treatment.

5. The method of claim 1, wherein the treatment is exposure to an alkaline solution.

6. The method of claim 1, wherein the bottom layer has a thickness of up to about 5 nm.

7. The method of claim 6, further comprising: A second bottom layer, the second bottom layer being below the bottom layer.

8. The method of claim 6, wherein the second bottom layer is more reactive to the treatment than the bottom layer.

9. The method of claim 1, wherein the bottom layer comprises an amorphous SiC:H material.

10. The method of claim 9, wherein the SiC:H is doped with one or more of Ge, B, and P.

11. The method of claim 10, wherein the one or more of Ge, B, and P are more reactive to the treatment to form OH bonds compared to the SiC:H.

12. A method of patterning a substrate, comprising: Providing a patterned stack above the substrate, wherein the patterned stack includes: A first bottom layer; A second bottom layer, the second bottom layer being above the first bottom layer; and A photoresist, the photoresist being above the second bottom layer; Exposing the patterned stack to electromagnetic radiation; Developing the photoresist in the patterned stack; Modifying the second bottom layer such that the adhesion strength to the photoresist is reduced; and Removing any scum above the second bottom layer.

13. The method of claim 12, wherein the second bottom layer has a thickness of up to about 5 nm.

14. The method of claim 13, wherein the second bottom layer is porous.

15. The method of claim 12, wherein the second bottom layer has a hydrophobic surface before modification and a hydrophilic surface after modification.

16. The method according to claim 12, wherein modifying the second underlying layer comprises: Exposing the first bottom layer and the second bottom layer to an alkaline solution.

17. The method of claim 12, wherein the photoresist is CAR.

18. A patterned stack, comprising: A first bottom layer; A second bottom layer, the second bottom layer being above the first bottom layer, and wherein the second bottom layer has a hydrophobic surface; And A photoresist, the photoresist being above the second bottom layer, wherein the photoresist has a hydrophobic surface.

19. The patterned stack according to claim 18, wherein the second underlying layer is converted into a hydrophilic surface after exposure to an alkaline solution.

20. A patterned stack, comprising: a first layer, wherein the first layer comprises one or more of silicon, oxygen, hydrogen, nitrogen, and carbon; a second layer, the second layer being above the first layer, wherein the second layer comprises one or more of silicon, amorphous silicon, oxygen, hydrogen, and nitrogen; a third layer, the third layer being above the second layer, wherein the third layer comprises carbon; and a photoresist, the photoresist being above the third layer, wherein the photoresist is a metal oxide resist (MOR) or a chemically amplified resist (CAR).

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