Photoresist composition, pattern forming method of near-field surface imaging, and deposition apparatus

Abstract

The present disclosure provides a photoresist composition, a pattern forming method of near-field surface layer imaging, and a deposition apparatus. The photoresist composition includes a solvent; a molecular glass compound, which is a calixarene derivative grafted with a diazonaphthoquinone, as a film forming component and a photosensitive component; and an affinity inhibitor, which is used at least to protect a hydroxyl group in the photoresist composition, to improve contrast between an exposed region and a non-exposed region during a pattern forming process. The photoresist composition of the present disclosure can be exposed over the entire thickness of the photoresist using near-field lithography, thereby achieving high-resolution pattern imaging.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of photoresist, in particular to a photoresist composition, a pattern forming method of near-field surface layer imaging and a deposition device. BACKGROUND

[0002] Near-field lithography can break through the technical predicament of current optical lithography resolution limit, and realize super-resolution exposure by using a long-wavelength light source (such as an I-line light source with a wavelength of 365 nm). However, due to the characteristics of evanescent waves, the transmission depth of evanescent fields carrying high-frequency information can only cover the thickness of the photoresist film layer (depending on the resolution) of 5-10 nm. Thin film layer photoresist is prone to defects such as pinholes, and increases the difficulty of etching process. For this problem, researchers found that using a special film layer structure (metal enhancement layer) can excite surface plasmons by evanescent waves, and realize their transmission in the photoresist layer. Although this strategy can improve the exposure depth and etching resistance to a certain extent, it still has limited effect on the improvement of the practical thickness of photoresist, and there is still a significant gap from the requirements of commercial photoresist. In addition, the weak adhesion of photoresist on the metal substrate, the selection of surface modification materials, and the additional dry etching process of the metal layer and other problems also prevent the obtaining and practical application of high-resolution patterns. Therefore, to obtain the super-resolution advantage of near-field lithography, a new surface imaging process needs to be developed, so that the evanescent waves which decay rapidly on the surface can be fully utilized.

[0003] The existing near-field lithography technology mainly has the following problems: 1. The exposure focal depth is too shallow, and it is impossible to realize full-depth exposure on photoresist thick enough, so only ultra-thin photoresist film layer can be used; 2. The ultra-thin photoresist film layer is prone to film quality problems, and it is difficult to realize the subsequent etching transfer process; 3. The light field intensity and contrast distribution in the depth range of the photoresist layer are inconsistent, resulting in poor straightness of the side wall of the photoresist after development.

[0004] Among them, the traditional polymer photoresist also has certain disadvantages: 1. The traditional polymer photoresist has a large molecular volume, and the obtained photoresist pattern usually has poor line edge / width roughness; 2. The traditional polymer photoresist mostly has strong affinity adsorption ability with hard mask precursor materials, and there is a certain thickness of deposition in the non-exposed area during the hard mask deposition process, which reduces the final imaging contrast. SUMMARY

[0005] (I) Technical problems to be solved

[0006] In view of the above problems, the present disclosure provides a photoresist composition, a pattern forming method of near-field surface layer imaging and a deposition device, which are used to solve the technical problems that the focal depth of the traditional near-field lithography is short and the photoresist cannot be exposed in the full thickness range.

[0007] (II) Technical Solution

[0008] In one aspect, the present disclosure provides a photoresist composition, comprising: a solvent; a molecular glass compound, which is a calixarene derivative grafted with diazonaphthoquinone, as a film-forming component and a photosensitive component; and an affinity inhibitor, which is used at least to protect hydroxyl groups in the photoresist composition, so as to improve the contrast between exposed areas and non-exposed areas in a pattern forming process.

[0009] Further, the molecular glass compound is 1,3-dihydroxyl calix[4]arene methyl grafted with diazonaphthoquinone; the grafting rate of the diazonaphthoquinone in the molecular glass compound is 37.5% to 50%; and the molecular weight of the molecular glass compound is 1200 to 1500.

[0010] Further, the molecular glass compound has the following structural formula I:

[0011]

[0012] Further, the affinity inhibitor is triphenol A grafted with diazonaphthoquinone; the grafting rate of the diazonaphthoquinone in the affinity inhibitor is 70% to 100%; and the molecular weight of the affinity inhibitor is 900 to 1200.

[0013] Further, the affinity inhibitor has the following structural formula II:

[0014]

[0015] Further, the mass percentage of the molecular glass compound and the affinity inhibitor in the photoresist composition is 2.5% to 5%; and the mass of the affinity inhibitor is 10% to 100% of the mass of the molecular glass compound.

[0016] Further, the solvent comprises a mixture of one or more of propylene glycol methyl ether acetate, n-butyl acetate, ethyl acetate, γ-butyrolactone, and propylene glycol methyl ether.

[0017] Another aspect of the present disclosure provides a pattern forming method for near-field surface layer imaging, comprising: S1, applying the aforementioned photoresist composition on a substrate to form a photoresist layer; the photoresist layer comprises a molecular glass compound, an affinity inhibitor and a solvent; S2, exposing the photoresist layer to light using near-field lithography, and the surface layer of the photoresist layer in the exposed area is photosensitive and cured; S3, selectively depositing a hard mask precursor on the photoresist layer, and heating to combine the hard mask precursor with the photoresist layer in the exposed area, while the affinity inhibitor is used to inhibit the combination of the hard mask precursor with the photoresist layer in the non-exposed area; S4, performing light etching on the deposited photoresist layer to remove the residual organic matter in the exposed area and oxidize the deposited hard mask precursor in the exposed area to form a hard mask layer; S5, performing deep etching on the photoresist layer to selectively etch away the photoresist layer in the non-exposed area which is not protected by the hard mask layer, thereby obtaining a high-resolution imaging pattern.

[0018] Further, S2 further comprises: S21, baking the photoresist layer to cause cross-linking reaction of the photoresist layer in the non-exposed area, so as to further inhibit the combination of the hard mask precursor with the photoresist layer in the non-exposed area in S3; wherein the baking temperature is 120-145℃, and the baking time is 1-5min.

[0019] Further, S4 further comprises: S41, etching to remove the residual hard mask precursor and the excess hard mask layer in the non-exposed area.

[0020] Further, the method for selectively depositing a hard mask precursor on the photoresist layer in S3 comprises a gas phase deposition method and a liquid phase deposition method; the hard mask precursor is a silicon-based material or a metal-based material, and is preferably a mixture of one or more of titanium chloride, titanium isopropoxide, tetrakis(dimethylamino)hafnium, tetrakis(methyl ethylamino)zirconium, dimethylsilyl dimethylamine, trimethylsilyl dimethylamine, trimethylsilyl diethylamine, 2,2,4,4,6,6-hexamethylcyclotrisilazane, 1,1,3,3,5,5-hexamethylcyclotrisiloxane and bis(dimethylamino)dimethylsilane.

[0021] Another aspect of the present disclosure provides a gas phase hard mask deposition device, comprising: a main cavity having a relatively closed sample cavity, the sample cavity controls the volume in the cavity through a position-adjustable cover plate; the sample cavity contains the substrate obtained in the aforementioned S2; a liquid supply unit containing a hard mask precursor, the liquid inlet pipe of the liquid supply unit extends into the sample cavity; a liquid inlet control unit is arranged on the liquid inlet pipe of the liquid supply unit, which is used to control the hard mask precursor to enter the sample cavity, and the hard mask precursor is evaporated in the sample cavity and then deposited on the substrate containing the photoresist layer; a heating unit is used to heat the substrate containing the photoresist layer during the deposition process; a gas control unit comprising a gas inlet assembly for introducing a displacement gas and a gas exhaust assembly for vacuum pumping and exhaust.

[0022] (III) Beneficial effects

[0023] The photoresist composition, the pattern forming method of near-field surface layer imaging and the deposition device of the present disclosure utilize a molecular glass compound to form a film and serve as a main photosensitive component, and provide hydroxyl sites for the deposition of a hard mask precursor in the exposed area; an affinity inhibitor is utilized to protect the hydroxyl groups in the photoresist composition, and further thermal crosslinking with the molecular glass compound can be performed to cooperatively reduce the affinity of the non-exposed area with the hard mask precursor. Near-field lithography is performed using the photoresist composition, a hard mask layer is formed in the exposed area using a hard mask precursor, and exposure can be performed in the full thickness range of the photoresist to achieve high-resolution pattern imaging. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A flowchart of the pattern forming method of near-field surface layer imaging according to an embodiment of the present disclosure is schematically shown;

[0025] Figure 2 A schematic diagram of the lithography principle according to an embodiment of the present disclosure is schematically shown;

[0026] Figure 3 A complete process flowchart of the pattern forming method of near-field surface layer imaging according to an embodiment of the present disclosure is schematically shown;

[0027] Figure 4 A structural schematic diagram of a gas-phase hard mask deposition device according to an embodiment of the present disclosure is schematically shown;

[0028] Figure 5 A 64nm half-period pattern obtained according to Example 1 of the present disclosure is schematically shown.

[0029] Figure 6 A 64nm half-period pattern obtained according to Example 2 of the present disclosure is schematically shown.

[0030] Figure 7 A 44nm half-period pattern obtained according to Example 2 of the present disclosure is schematically shown.

[0031] Figure 8 A 64nm half-period pattern obtained according to Comparative Example 1 of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present disclosure more clear and apparent, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the drawings.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the terms "comprises", "comprising", "includes", "including" and the like are specifically intended to be open-ended and to mean that other features, steps, operations, and / or components can be added.

[0034] All terms used herein, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art unless otherwise defined herein. It should be noted that the terms used herein are defined as having meanings that are consistent with the context of the specification in which the terms are used and should not be interpreted in an overly idealized or overly formal way.

[0035] The present disclosure provides a photoresist composition, comprising: a solvent; a molecular glass compound, a calixarene derivative grafted with diazonaphthoquinone, as a film-forming component and a photosensitive component; an affinity inhibitor, at least for protecting hydroxyl groups in the photoresist composition to improve the contrast between the exposed area and the non-exposed area in the pattern forming process.

[0036] The photoresist composition of the present disclosure comprises a molecular glass compound, an affinity inhibitor and a solvent. Among them, the molecular glass compound selects a calixarene derivative with excellent film-forming performance and uniform molecular weight distribution as a film-forming component, and grafted diazonaphthoquinone as a photosensitive component, and provides hydroxyl sites for the deposition of hard mask precursors in the exposed area in the pattern forming process. The affinity inhibitor, on the one hand, protects the hydroxyl groups in the photoresist composition through weak interactions such as hydrogen bonds to prevent the exposure of hydroxyl groups, and is used to regulate the content of hydroxyl groups in the non-exposed area, thereby reducing the affinity of the photoresist composition and the hard mask precursor; on the other hand, it can further thermally cross-link with the molecular glass compound to synergistically reduce the affinity of the non-exposed area and the hard mask precursor. The molecular glass compound and the affinity inhibitor are indispensable to each other.

[0037] On the basis of the above-mentioned embodiments, the molecular glass compound is 1,3-dihydroxycalix[4]arene methyl grafted with diazonaphthoquinone; the grafting rate of diazonaphthoquinone in the molecular glass compound is 37.5% to 50%; and the molecular weight of the molecular glass compound is 1200 to 1500.

[0038] Preferably, the molecular glass compound is 1,3-dihydroxycalix[4]arene methyl grafted with diazonaphthoquinone, and its structural formula is shown as formula I:

[0039]

[0040] On the basis of the above-mentioned embodiments, the affinity inhibitor is triphenol A grafted with diazonaphthoquinone; the grafting rate of diazonaphthoquinone in the affinity inhibitor is 70% to 100%; and the molecular weight of the affinity inhibitor is 900 to 1200.

[0041] Preferably, the affinity inhibitor is trisphol A grafted with diazonium naphthoquinone, whose structural formula is shown as formula II:

[0042]

[0043] The grafting rate of diazonium naphthoquinone in the affinity inhibitor is high, which is conducive to the inhibition of hydroxyl groups in the system and enhances the chemical contrast between the exposed area and the non-exposed area.

[0044] On the basis of the above-mentioned embodiments, the mass percentage of the molecular glass compound and the affinity inhibitor in the photoresist composition is 2.5-5%, and the mass of the affinity inhibitor is 10%-100% of the mass of the molecular glass compound.

[0045] Preferably, the mass percentage of the molecular glass compound and the affinity inhibitor is 2.5-5%, and the mass percentage of the solvent in the photoresist composition can be 94-97.5%. In addition, other additive ingredients can be selected to be added to the photoresist composition, including a mixture of one or more of a dissolution promoter, a leveling agent, a surfactant, and a stabilizer, and the total mass percentage of the additive ingredients is not more than 1%. The above-mentioned proportions are based on the optimized values for forming an ultra-thin film layer below 100 nm. Too little solvent will make it difficult to form an ultra-thin film layer by spin coating (spin coating speed is 1500-4000 rpm), and too much solvent will make the photoresist composition too dilute to form a high-quality photoresist film layer. The mass ratio of the molecular glass compound to the affinity inhibitor in the above-mentioned range can make the exposed area and the non-exposed area have a higher chemical contrast, thereby ensuring the formation of high-resolution patterns.

[0046] On the basis of the above-mentioned embodiments, the solvent includes a mixture of one or more of propylene glycol methyl ether acetate, n-butyl acetate, ethyl acetate, γ-butyrolactone, and propylene glycol methyl ether.

[0047] The solvent can make the photoresist composition in a liquid state, which is convenient for coating, and other components are mixed by the solvent to form the photoresist composition. The above-mentioned solvent has a good coverage range for dissolving various photoresist components with different polarities.

[0048] The present disclosure also provides a pattern forming method for near-field surface imaging, which is described in detail in the following Figure 1, comprising: S1, applying a photoresist composition on a substrate to form a photoresist layer; the photoresist layer comprises a molecular glass compound, an affinity inhibitor and a solvent; S2, exposing the photoresist layer to light using near-field lithography, and the surface layer of the photoresist layer in the exposed area is photosensitive and cured; S3, selectively depositing a hard mask precursor on the photoresist layer, and heating to combine the hard mask precursor in the exposed area with the photoresist layer, while the affinity inhibitor is used to inhibit the combination of the hard mask precursor in the non-exposed area with the photoresist layer; S4, performing mild etching on the deposited photoresist layer to remove the residual organic matter in the exposed area and oxidize the deposited hard mask precursor in the exposed area to form a hard mask layer; S5, performing deep etching on the photoresist layer to selectively etch away the photoresist layer in the non-exposed area which is not protected by the hard mask layer, and obtaining a high-resolution imaging pattern.

[0049] The present disclosure utilizes the characteristics of near-field lithography to perform high-resolution exposure on the surface of the photoresist composition, and the lithography principle is as shown in Figure 2 Because the content of hydroxyl groups in the exposed area and the non-exposed area of the photoresist composition is significantly different, a specific hard mask precursor can react with the hydroxyl groups in the exposed area rich in hydroxyl groups, thereby incorporating the hard mask precursor into the exposed area of the photoresist composition. Then, the photoresist composition in the non-exposed area is selectively etched and removed by oxygen plasma to obtain a pattern.

[0050] In the oxygen plasma mild etching stage, the hard mask precursor in the exposed area of the photoresist composition is oxidized on the surface of the photoresist composition to form an oxide hard mask layer (such as silicon oxide, titanium oxide, hafnium oxide, etc.), which can prevent further etching of the underlying photoresist composition, while the non-exposed area will be etched away quickly due to only containing organic components, forming a lithography pattern. Although this method is theoretically applicable to various photoresist systems containing hydroxyl groups and various hard mask precursors, only a specific combination of materials matched with a specific process step can form a nanoscale resolution pattern image.

[0051] The pattern forming method of the present disclosure can break through the diffraction limit of optical lithography and achieve super-resolution imaging, and can also solve the problem of short focal depth of near-field lithography and the inability to expose the entire thickness of the photoresist by combining a hard mask layer.

[0052] On the basis of the above-mentioned embodiments, S2 further comprises: S21, baking the photoresist layer to cause cross-linking reaction of the photoresist layer in the non-exposed area, so as to further inhibit the combination of the hard mask precursor in the non-exposed area with the photoresist layer in S3; wherein the baking temperature is 120-145℃, and the baking time is 1-5min.

[0053] On the basis of the above-mentioned embodiments, S4 further comprises: S41, etching to remove the residual hard mask precursor and the excess hard mask layer in the non-exposed area.

[0054] The complete process flow chart of the pattern forming method of the present disclosure is shown in Figure 1, which comprises the following steps: Figure 3

[0055] S1, Preparation of photoresist layer: using the photoresist composition provided by the present disclosure to form a photoresist layer on a substrate; spin coating the photoresist composition at a speed of 1500-4000 rpm, and then pre-baking at 90-110°C for 30-180 s to obtain a film thickness of 30-120 nm, preferably 60-90 nm, and more preferably 70-80 nm.

[0056] S2, Exposure: using near-field lithography to expose the photoresist layer with a mask having a nanoscale pattern; at this time, due to the rapid attenuation characteristics of the evanescent wave, only the 5-10 nm surface layer of the photoresist layer can be exposed (depending on the pattern size and film layer structure), and the exposed part undergoes a chemical reaction to expose a large number of hydroxyl groups;

[0057] S21, Optional crosslinking reaction: optionally, baking the photoresist layer to cause a certain crosslinking reaction between the diazonium naphthoquinone structure (including diazonium naphthoquinone on the molecular glass compound and diazonium naphthoquinone on the affinity inhibitor) in the non-exposed area and the hydroxyl group, further weakening the interaction between the non-exposed area and the hard mask precursor; while in the exposed area, due to the large conversion of the diazonium naphthoquinone structure, the crosslinking degree is much lower than that in the non-exposed area. The baking temperature for crosslinking reaction is 120-145°C, and the baking time is 1-5 min.

[0058] S3, Hard mask deposition: placing the substrate containing the photoresist layer in an environment containing the hard mask precursor to perform selective deposition, and under appropriate heating conditions, causing the hard mask precursor to selectively bond with the hydroxyl group in the exposed area.

[0059] S4, Mild etching hardening: using oxygen plasma or the like to perform mild etching on the deposited photoresist layer, so that the organic matter in the exposed area after treatment with the hard mask precursor is removed and a hard mask layer is formed on the surface.

[0060] S41, Optional back etching: since a small amount of hard mask deposition is inevitable in the non-exposed area, halogen-containing atmosphere can be selected to perform back etching on the photoresist layer to remove the residual hard mask precursor and excess hard mask layer in the non-exposed area.

[0061] S5, Deep etching: using oxygen plasma or the like to perform deep etching on the photoresist layer, and the pattern is obtained by selectively etching away the photoresist layer not protected by the hard mask layer; wherein the etching oxygen flow is 5-10 sccm, the power is 5-10 W, and the time is 120-300 s.

[0062] ​The pattern forming method of the present disclosure realizes high-resolution pattern imaging by screening and regulating photoresist materials, hard mask precursor materials and processes; meanwhile, the problem of too small exposure depth of focus and defects of thin film photoresist in near-field lithography is solved by surface imaging. The method of the present disclosure is suitable for near-field lithography and can realize high-resolution pattern imaging below 50 nm using long-wavelength ultraviolet light sources.

[0063] On the basis of the above-mentioned embodiments, the method for selectively depositing a hard mask precursor on the photoresist layer in S3 includes a gas phase deposition method and a liquid phase deposition method; the hard mask precursor is a silicon-based material or a metal-based material.

[0064] The hard mask precursor can be a silicon-based material or a metal-based material, including but not limited to one of titanium chloride, titanium isopropyl alcohol, hafnium tetrakis(dimethylamide), zirconium tetrakis(methyl ethyl amide), dimethylsilyl dimethylamine, trimethylsilyl dimethylamine, trimethylsilyl diethylamine, 2,2,4,4,6,6-hexamethylcyclotrisilazane (HMCTS), 1,1,3,3,5,5-hexamethylcyclotrisiloxane and bis(dimethylamino)dimethylsilane. Considering the pattern quality (compactness of the obtained pattern) and the solubility of the hard mask precursor to the photoresist, HMCTS is preferred.

[0065] The method for selective deposition includes a gas phase deposition method and a liquid phase deposition method, as follows:

[0066] The gas phase deposition method: the substrate with the photoresist layer obtained in step S2 or step S21 is placed in a gas phase deposition device, the cavity is vacuumed, preheated at 100-120℃ for 2-8 min, the hard mask precursor is introduced, the temperature is kept at 100-120℃, the photoresist layer is allowed to react with the hard mask precursor for 10-20 min, vacuumed again to remove residual gas, washed with nitrogen gas for 2-3 times, and then the sample is taken out.

[0067] The liquid phase deposition method: the liquid phase composition includes a hard mask precursor, a diffusion promoter (resin solvent) and a resin non-solvent, wherein the diffusion promoter can be propylene glycol methyl ether acetate or N-methyl pyrrolidone, and the resin non-solvent can be o-xylene, m-xylene or p-xylene; the weight percentage of the hard mask precursor in the liquid phase composition is 5-15%, the weight percentage of the diffusion promoter in the liquid phase composition is not more than 5%, and the weight percentage of the resin non-solvent in the liquid phase composition is 80-95%. The temperature for liquid phase deposition is 25-40℃, and the time is 0.5-2 min.

[0068] The disclosure also provides a vapor phase hard mask deposition device, comprising: a main cavity with a relatively closed sample cavity, the sample cavity controls the volume in the cavity through a position-adjustable cover plate; the sample cavity contains a substrate obtained according to S2 described above; a liquid supply unit containing a hard mask precursor, the liquid inlet pipe of the liquid supply unit extends into the sample cavity; a liquid inlet control unit is arranged on the liquid inlet pipe of the liquid supply unit, used to control the hard mask precursor to enter the sample cavity, and the hard mask precursor is deposited on the substrate containing a photoresist layer after evaporation in the sample cavity; a heating unit is used to heat the substrate containing a photoresist layer during deposition; a gas control unit, comprising a gas inlet assembly for introducing a displacement gas and a gas exhaust assembly for vacuumizing and exhausting waste gas.

[0069] As shown in Figure 4 The liquid supply unit is located outside the main cavity and is made of stainless steel (or quartz); the liquid inlet pipe in the main cavity is made of quartz, the tail is bent downward, the bottom of the liquid inlet pipe is the liquid outlet, and the liquid inlet control unit (for example, a liquid inlet valve) is arranged on the liquid inlet pipe, which is automatically opened when the cavity is filled with liquid, used to control the hard mask precursor to enter the vacuum main cavity; the evaporation dish and the substrate sample (containing a photoresist layer) are placed in the sample cavity, the liquid outlet is arranged above the evaporation dish, and the volume of the sample cavity (thus controlling the vapor concentration on the sample surface) can be controlled by a position-adjustable cover plate; the heating unit (not shown) is used to heat the substrate, the gas inlet assembly is used to introduce nitrogen and other displacement gases for gas washing treatment, and the gas exhaust assembly is used to vacuumize and exhaust waste gas.

[0070] The working process of the mechanism is as follows:

[0071] (1) When the vacuum degree and temperature in the main cavity reach the set value, the system automatically opens the liquid inlet control unit, and due to the effect of vacuum, the hard mask precursor is sucked into the main cavity (the flow rate is controllable), and completely vaporizes on the evaporation dish below the quartz liquid outlet;

[0072] (2) Since the vaporization platform and the substrate sample are placed in a relatively closed space (i.e. the sample cavity), a higher gas concentration relative to other positions in the cavity is obtained, which is more conducive to the surface treatment of the substrate sample;

[0073] (3) The liquid inlet pipe and the sample cavity are made of quartz, which is conducive to observing the effect of the treatment process;

[0074] (4) During the gas displacement process by the gas inlet assembly, the residual liquid vapor is completely displaced by the gas exhaust assembly (such as a vacuum pump), including the residual vapor in the quartz pipe.

[0075] The pattern forming method of the present disclosure can effectively utilize near-field lithography to image in a high-resolution light field of the surface layer of a photoresist layer; since the exposure is not dependent on the full thickness range of the photoresist, the theoretical thickness of the photoresist used by the method can be arbitrarily large, effectively solving the problem of short focal depth of near-field lithography and widening the process window. At the same time, the hard mask precursor material and process are optimized to achieve the effect of high selectivity deposition in the exposed area and the non-exposed area; the photoresist composition material system and process are optimized to maximize the hydroxyl concentration gradient in the exposed area and the non-exposed area, so that the resolution is improved to an unprecedented level; the etching process is optimized to achieve the transfer of the hard mask layer on the surface to the entire photoresist layer thickness, thereby solving the problem that near-field lithography cannot expose on thick photoresist.

[0076] The present disclosure will be further described below through specific embodiments. In the following examples, the above-mentioned photoresist composition, near-field surface imaging pattern forming method and deposition equipment are specifically described. However, the following examples are only used to illustrate the present disclosure, and the scope of the present disclosure is not limited thereto.

[0077] The photoresist composition of the present disclosure comprises: a molecular glass compound, which is 1,3-dihydroxy calix[4]arene methyl grafted with 37.5% to 50% diazonaphthoquinone, has a molecular weight of 1200 to 1500, and has a structural formula as shown in Formula I; an affinity inhibitor, which is triphenol A grafted with 70% to 100% diazonaphthoquinone, has a molecular weight of 900 to 1200, and has a structural formula as shown in Formula II; and a solvent, which is a mixture of one or more of propylene glycol methyl ether acetate, n-butyl acetate, ethyl acetate, γ-butyrolactone and propylene glycol methyl ether.

[0078] The near-field surface imaging pattern forming method of the present disclosure, as shown in Figure 1 , Figure 3 comprises the following steps performed in sequence:

[0079] Step 1: spin coating the above-mentioned photoresist composition on a substrate at a rotation speed of 1500 to 4000 rpm, and then pre-baking at 90 to 110°C for 30 to 180s to obtain a photoresist layer with a film thickness of 30 to 120 nm; equivalent to the above-mentioned step S1.

[0080] Step 2: exposing the photoresist layer using near-field lithography with a mask having a nanoscale pattern close to the photoresist layer; the surface layer of the photoresist layer can be exposed at a depth of 5 to 10 nm; equivalent to the above-mentioned step S2.

[0081] Step 21: optionally, baking the photoresist layer to cause a certain cross-linking reaction of the diazonaphthoquinone structure and hydroxyl groups in the non-exposed area (including the diazonaphthoquinone on the molecular glass compound and the diazonaphthoquinone on the affinity inhibitor) to further inhibit the combination of the hard mask precursor and the photoresist layer in the non-exposed area in S3; equivalent to the above-mentioned step S21.

[0082] Step 3, selectively depositing a hard mask precursor on the photoresist layer, and heating to make the hard mask precursor in the exposed area combine with the photoresist layer; equivalent to the above-mentioned step S3.

[0083] Step 4, lightly etching the deposited photoresist layer with oxygen plasma to remove residual organic matter in the exposed area and oxidize the deposited hard mask precursor in the exposed area to form a hard mask layer; equivalent to the above-mentioned step S4.

[0084] Step 41, optionally, etching to remove residual hard mask precursor and excess hard mask layer in the non-exposed area; equivalent to the above-mentioned step S41.

[0085] Step 5, deeply etching the photoresist layer with oxygen plasma to selectively etch away the photoresist layer in the non-exposed area not protected by the hard mask layer, to obtain a high-resolution imaging pattern; equivalent to the above-mentioned step S5.

[0086] According to the above-mentioned photoresist composition and the steps 1-5 of the pattern forming method, six specific examples and three comparative examples are provided below.

[0087] Example 1:

[0088] The photoresist composition of this example includes a molecular glass compound with a grafting rate of 37.5%, a triphenol A affinity inhibitor with a grafting rate of 70% diazonium naphthoquinone, and a PGMEA solvent, wherein the mass percentage of the molecular glass compound and the affinity inhibitor in the photoresist composition is 2.5%, and the mass of the affinity inhibitor is 50% of the mass of the molecular glass compound.

[0089] The implementation steps of the pattern forming method of this example are as follows:

[0090] Step 1-1, prepare a photoresist layer with a thickness of about 30 nm on a Si substrate by spin coating at a speed of 1500 rpm for 30 s, and pre-bake on a 90°C hot plate for 30 s; obtain a sample containing a photoresist layer.

[0091] Step 1-2, expose the sample with a near-field photolithography machine with a center wavelength of 365 nm, the mask pattern is a grating with a half period of 64 nm, and the exposure dose is about 40 mJ / cm 2 .

[0092] Step 1-3, place the sample in a deposition solution containing: bis(dimethylamino)dimethylsilane, propylene glycol methyl ether acetate and o-xylene (wherein the weight percentages of the three components are 5%, 3% and 92% respectively). Soak for 2 min at a temperature of 30°C. Finally, gently rinse the surface of the sample with o-xylene and dry with a nitrogen gun.

[0093] Step 1-4, the deposited photoresist layer was slightly etched by oxygen plasma, the etching power was 10 W, the cavity pressure was 1 Pa, the sample stage temperature was 10℃, and the etching time was about 30 s.

[0094] Step 1-5, the photoresist layer was deeply etched by oxygen plasma, the etching time was about 120 s, the power was 5 W, and the oxygen flow rate was 5 sccm.

[0095] Figure 5 The 64 nm half-period pattern obtained from Example 1 was observed, and it can be seen from the pattern that the lines are clear, the outline is clear, and the edge is slightly rough.

[0096] Example 2:

[0097] The photoresist composition of this example includes a molecular glass compound with a grafting rate of 37.5%, a triphenol A affinity inhibitor with a grafting rate of 100% diazonaphthoquinone, and a PGMEA solvent, wherein the mass percentage of the molecular glass compound and the affinity inhibitor in the photoresist composition is 3.8%, and the mass of the affinity inhibitor is 100% of the mass of the molecular glass compound.

[0098] The implementation steps of the pattern forming method of this example are as follows:

[0099] Step 2-1, a photoresist layer with a thickness of about 65 nm was prepared on a Si substrate by spin coating, the spin coating speed was 4000 rpm, the time was 30 s, and the sample was baked on a 100℃ hot plate for 120 s and then cooled to room temperature after being taken out; a sample containing a photoresist layer was obtained.

[0100] Step 2-2, the sample was exposed by a near-field photolithography machine with a center wavelength of 365 nm, and the mask pattern was a grating with a half-period of 44 nm and 64 nm, respectively, and the exposure dose was about 72 mJ / cm 2 .

[0101] Step 2-21, then baked on a 120℃ hot plate for 2 min.

[0102] Step 2-3, the sample was placed in a gas phase hard mask deposition device as shown in Figure 4 , and the atmosphere in the device was a vacuum environment, the sample was treated with HMCTS hard mask precursor at a temperature of 110℃ for 15 min.

[0103] Step 2-4, the deposited photoresist layer was slightly etched by oxygen plasma, the etching power was 10 W, the cavity pressure was 1 Pa, the sample stage temperature was 10℃, and the etching time was about 30 s.

[0104] Step 2-41, the photoresist layer was etched back with a mixture of trifluoromethane plasma (25 sccm) and sulfur hexafluoride plasma (5 sccm) at a volume ratio of 5:1, the etching time was about 30 s, the vacuum degree was 7x10 -3 pa, and the cavity pressure was 1 Pa.

[0105] Step 2-5, finally, the photoresist layer was etched deeply with oxygen plasma, the etching time was about 200 s, the power was 10 W, and the oxygen flow rate was 10 sccm.

[0106] Figure 6 For the 64 nm half-period pattern obtained in Example 2, there was no residual glue around the line, and the line was clear and smooth; Figure 7 For the 44 nm half-period pattern obtained in Example 2, the line was clear and uniform.

[0107] Comparative Example 1:

[0108] The photoresist composition of the present comparative example comprises a molecular glass compound with a grafting rate of 37.5% and a PGMEA solvent, wherein the mass percentage of the molecular glass compound in the photoresist composition is 3%.

[0109] The implementation steps of the pattern forming method of the present comparative example are as follows:

[0110] Step 3-1, a photoresist layer with a thickness of about 65 nm was prepared on a Si substrate by spin coating, the spin coating speed was 4000 rpm, the time was 30 s, and the pre-baking was performed on a 100°C hot plate for 120 s, and then the sample was cooled to room temperature after being taken out. A sample containing a photoresist layer was obtained.

[0111] Step 3-2, the sample was exposed to light using a near-field photolithography machine with a center wavelength of 365 nm, the mask pattern was a grating with a half-period of 64 nm, and the exposure dose was about 72 mJ / cm 2 .

[0112] Step 3-21, then baked on a 120°C hot plate for 2 min.

[0113] Step 3-3, the sample was placed in the vapor phase hard mask deposition equipment shown in Figure 4 , the atmosphere in the equipment was a vacuum environment, the sample was treated with HMCTS hard mask precursor at a temperature of 110°C for 15 min;

[0114] Step 3-4, the photoresist layer was etched lightly with oxygen plasma, the etching power was 10 W, the cavity pressure was 1 Pa, the sample stage temperature was 10°C, and the etching time was about 30 s;

[0115] Step 3-41, the photoresist layer is etched back with a mixture of trifluoromethane plasma (25 sccm) and sulfur hexafluoride plasma (5 sccm) at a volume ratio of 5:1, the etching time is about 30 s, the vacuum degree is 7x10 -3 pa, the cavity pressure is 1 Pa.

[0116] Step 3-5, finally, the photoresist layer is etched in depth with oxygen plasma, the etching time is about 200 s, the power is 10 W, and the oxygen flow is 10 sccm.

[0117] Figure 8 For the 64 nm half-period pattern obtained from Comparative Example 1, the cross-linking between lines is obvious, the line edges are rough, and the non-exposed area has serious residual glue.

[0118] Similarly, the experimental parameters and the obtained pattern quality results of Example 3 to Example 6 and Comparative Example 2 to Comparative Example 3 are shown in the following table, and the specific process will not be described here.

[0119]

[0120]

[0121] Comparative Example 2 is used to compare the case where the cross-linking temperature exceeds the upper limit of the above temperature range (145°C), and Comparative Example 3 is used to compare the case where the temperature is lower than the lower limit of the above temperature range (100°C) when the vapor deposition hard mask layer is used.

[0122] According to the above table, it can be concluded that the final patterning effect of the present disclosure needs to match the material with the corresponding process condition range, so as to achieve the effect.

[0123] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present disclosure, and it should be understood that the above description is only for specific embodiments of the present disclosure and is not intended to limit the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A pattern forming method of near-field surface layer imaging, characterized by, The application relates to a photoresist composition and a preparation method thereof. S1, applying a photoresist composition on a substrate to form a photoresist layer; the photoresist layer comprises a molecular glass compound, an affinity inhibitor and a solvent; the molecular glass compound is a calixarene derivative grafted with diazonaphthoquinone, serving as a film-forming component and a photosensitive component; the affinity inhibitor is used at least for protecting hydroxyl groups in the photoresist composition to improve the contrast between exposed areas and non-exposed areas in a pattern forming process; the affinity inhibitor is triphenol A grafted with diazonaphthoquinone; the grafting rate of diazonaphthoquinone in the affinity inhibitor is 70% to 100%; the molecular weight of the affinity inhibitor is 900 to 1200; the structural formula of the affinity inhibitor is as shown in formula II below: Formula II; S2, exposing the photoresist layer to light by using near-field lithography, and making the surface layer of the photoresist layer in the exposed area photosensitive and cured; S3, selectively depositing a hard mask precursor on the photoresist layer, and heating to make the hard mask precursor in the exposed area combine with the photoresist layer, while the affinity inhibitor is used to inhibit the combination of the hard mask precursor with the photoresist layer in the non-exposed area; S4, performing light etching on the deposited photoresist layer to remove the residual organic matter in the exposed area and make the hard mask layer formed by oxidizing the hard mask precursor deposited on the exposed area; S5, performing deep etching on the photoresist layer to selectively etch away the photoresist layer in the non-exposed area which is not protected by the hard mask layer, and obtaining a high-resolution imaging pattern.

2. The pattern forming method of near-field surface-layer imaging according to claim 1, wherein The S2 further comprises: S21, baking the photoresist layer to make the photoresist layer in the non-exposed area crosslink, so as to further inhibit the combination of the hard mask precursor with the photoresist layer in the non-exposed area in S3; The baking temperature is 120 to 145 DEG C, and the baking time is 1 to 5 min.

3. The pattern forming method of near-field surface-layer imaging according to claim 1, wherein The S4 further comprises: S41, etching to remove the residual hard mask precursor and the excess hard mask layer in the non-exposed area.

4. The pattern forming method of near-field surface-layer imaging according to claim 1, wherein The method for selectively depositing a hard mask precursor on the photoresist layer in S3 comprises a gas phase deposition method and a liquid phase deposition method; The hard mask precursor is a silicon-based material or a metal-based material, and is a mixture of one or more of the following: titanium chloride, titanium isopropyl alcohol, tetrakis (dimethylamine) hafnium, tetrakis (methyl ethylamine) zirconium, dimethylsilyl dimethylamine, trimethylsilyl dimethylamine, trimethylsilyl diethylamine, 2, 2, 4, 4, 6, 6-hexamethylcyclotrisilazane, 1, 1, 3, 3, 5, 5-hexamethylcyclotrisiloxane and bis (dimethylamino) dimethylsilane.

5. The pattern forming method of near-field surface-layer imaging according to claim 1, wherein The molecular glass compound is 1, 3-dihydroxycalix[4]arene methyl grafted with diazonaphthoquinone; The grafting rate of diazonaphthoquinone in the molecular glass compound is 37.5% to 50%; The molecular weight of the molecular glass compound is 1200 to 1500.

6. The pattern forming method of near-field surface-layer imaging according to claim 5, wherein The structural formula of the molecular glass compound is as shown in formula I below: Formula I.

7. The pattern forming method of near-field surface-layer imaging according to claim 1, wherein The mass percentage of the molecular glass compound and the affinity inhibitor in the photoresist composition is 2.5% to 5%; The mass of the affinity inhibitor is 10% to 100% of the mass of the molecular glass compound.

8. The pattern forming method of near-field surface-layer imaging according to claim 1, wherein The solvent includes a mixture of one or more of propylene glycol methyl ether acetate, n-butyl acetate, ethyl acetate, gamma-butyrolactone, and propylene glycol methyl ether.

9. The near-field surface-layer imaging patterning method according to any one of claims 1 to 8, wherein The pattern forming method forms a pattern using a vapor phase hard mask deposition apparatus including: a main cavity having a relatively closed sample cavity, the sample cavity controlling the volume in the cavity through a position-adjustable cover plate; the sample cavity containing a substrate obtained from S2; a liquid supply unit containing a hard mask precursor, the liquid supply unit having a liquid inlet pipe extending into the sample cavity; a liquid inlet control unit provided on the liquid inlet pipe of the liquid supply unit, for controlling the hard mask precursor to enter the sample cavity, the hard mask precursor being deposited on the substrate containing a photoresist layer after evaporation in the sample cavity; a heating unit for heating the substrate containing a photoresist layer during deposition; a gas control unit including a gas inlet assembly for introducing a replacement gas and a gas exhaust assembly for vacuum pumping and exhausting waste gas.

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