A material-filled protective photolithography mask and its preparation method

Abstract

The present disclosure provides a method for preparing a material-filled protective photolithography mask, including: S1, depositing a photolithography mask material on a mask substrate to prepare a mask pattern structure; S2, filling a transparent dielectric material into the mask pattern structure; S3, annealing the mask obtained in S2; S4, chemically mechanically polishing the surface of the mask obtained in S3 to expose the mask pattern structure, thereby obtaining a material-filled protective photolithography mask. By filling the mask pattern structure with a material during the contact photolithography mask pattern processing, the present disclosure increases the contact area and strength between the mask pattern structure and the photosensitive material, thereby effectively improving the service life of the contact photolithography mask, reducing the mask processing cost, and expanding the application range of the contact photolithography technology.

Description

Technical Field

[0001] The present disclosure relates to the field of super-resolution imaging technology, and particularly relates to a material-filled protective lithography mask and a preparation method thereof. Background Art

[0002] The resolution of traditional imaging systems is limited by the Rayleigh resolution limit, and the highest resolution is about half a wavelength. The surface plasmon (SP) super-resolution imaging technology, which is based on the principle of manipulating evanescent waves to participate in imaging, breaks through the diffraction limit of the imaging resolution of about half a wavelength of traditional optical systems and realizes sub-wavelength scale resolution imaging. However, it still faces the problem of near-field diffraction limit, that is, the resolvable object detail size is limited by the illumination wavelength and the distance between the object and the image. Under this physical limitation, there are restrictive relationships between the resolution and the working distance, depth of focus, etc., which become the fundamental obstacles to improving the performance of super-resolution imaging.

[0003] Due to the near-field diffraction limit problem, in lithography technology, the distance range between the mask pattern and the imaging recording structure is extremely limited. As a result, in SP lithography experiments, contact lithography or an integrated SP lens structure has to be adopted. For example, in the super-lens verification experiment, to achieve a resolution of 60 nm half-period, the equivalent air working distance between the mask pattern and the super-lens is only about 20 nm. The traditional lithography mask patterns are often metal structures processed by focused ion beam or electron beam direct writing technology. The adjacent periodic metal structures are filled with air, and the metal structures generally only account for half or even less of the area of the mask pattern region. In the contact-mode lithography method, this will cause problems such as damage or even destruction of the mask pattern due to the extrusion between the mask pattern and the photosensitive material, seriously affecting the service life of the contact lithography mask and its application in integrated circuit processing. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] In view of the above problems, the present disclosure provides a material-filled protective lithography mask and a preparation method thereof, which are used to solve the technical problems such as the easy extrusion damage of traditional contact lithography masks.

[0006] (II) Technical Solutions

[0007] On the one hand, the present disclosure provides a preparation method of a material-filled protective lithography mask, including: S1, depositing a lithography mask material on a mask substrate to prepare a mask pattern structure; S2, filling a transparent dielectric material into the mask pattern structure; S3, annealing the mask obtained in S2; S4, chemically mechanically polishing the surface of the mask obtained in S3 to expose the mask pattern structure, so as to obtain a material-filled protective lithography mask.

[0008] Further, the method for depositing the photolithography mask material in S1 includes one of sputter deposition, evaporation deposition, atomic layer deposition, and chemical vapor deposition.

[0009] Further, the photolithography mask material in S1 is a hard metal, and the thickness of the photolithography mask material is 20 - 300 nm.

[0010] Further, the method for preparing the mask pattern structure in S1 includes one of electron beam direct writing lithography, laser direct writing lithography, focused ion beam direct writing lithography, surface plasmon lithography, projection lithography, ion beam etching, reactive ion etching, inductively coupled plasma etching, and wet etching.

[0011] Further, the method for filling the transparent dielectric material in S2 includes one of sputter deposition, evaporation deposition, atomic layer deposition, chemical vapor deposition, and spin coating.

[0012] Further, the transparent dielectric material in S2 includes one of silicon dioxide, silicon nitride, diamond, aluminum oxide, organic carbon, and magnesium fluoride.

[0013] Further, the temperature of the annealing treatment in S3 is 100°C - 1000°C, the heating rate is 10°C - 100°C / minute, the cooling rate is 10°C - 50°C / minute, and the holding time is 0.5 - 10 hours.

[0014] Further, the annealing treatment in S3 includes annealing the entire mask or annealing the upper surface part of the mask with the transparent dielectric material.

[0015] Further, S4 includes: chemically - mechanically polishing the surface of the mask obtained in S3 until all the parts of the transparent dielectric material higher than the mask pattern structure are removed.

[0016] On the other hand, the present disclosure provides a photolithography mask with material - filling protection, which is prepared by using the aforementioned method for preparing a photolithography mask with material - filling protection.

[0017] (III) Beneficial Effects

[0018] For the photolithography mask with material - filling protection and its preparation method of the present disclosure, by filling the mask pattern structure with a transparent dielectric material and performing chemical - mechanical polishing, a planarized photolithography mask filled with the transparent dielectric is obtained, effectively improving the strength of the mask pattern structure; during contact lithography, it is beneficial to increase the contact area between the mask pattern structure and the photosensitive material, reducing the risk of pattern damage caused by extrusion with the photosensitive material, thus effectively improving the service life of the contact photolithography mask and reducing the mask processing cost at the same time. Brief Description of the Drawings

[0019] Figure 1 Schematically shows a flowchart of a method for preparing a material-filled protective photomask according to an embodiment of the present disclosure;

[0020] Figure 2 Schematically shows a structural change diagram of a method for preparing a material-filled protective photomask according to an embodiment of the present disclosure;

[0021] Explanation of reference numerals in the drawings:

[0022] 1, mask substrate; 2, photomask material; 3, cavity; 4, transparent dielectric material. Detailed implementation manners

[0023] To make the objectives, technical solutions, and advantages of the present disclosure clearer and more understandable, the present disclosure will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0024] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0025] It should be noted that if there are directional indications in the embodiments of the present disclosure, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0026] An embodiment of the present disclosure provides a method for preparing a material-filled protective photomask. Please refer to Figure 1 , including: S1, depositing a photomask material on a mask substrate to prepare a mask pattern structure; S2, filling a transparent dielectric material into the mask pattern structure; S3, annealing the mask obtained in S2; S4, performing chemical mechanical polishing on the surface of the mask obtained in S3 to expose the mask pattern structure, thereby obtaining a material-filled protective photomask.

[0027] Based on the prepared mask pattern structure, the present disclosure uses a material filling technology and a planarization technology to fill a transparent dielectric material into the mask pattern structure and perform chemical mechanical polishing, obtaining a planarized photomask filled with a transparent dielectric material. Without affecting the mask pattern, the strength of the mask pattern structure is effectively improved; during contact lithography, it is beneficial to increase the contact area between the mask pattern structure and the photosensitive material, reducing the risk of pattern damage caused by extrusion with the photosensitive material, and greatly improving the service life of the existing contact photomask.

[0028] Based on the above embodiments, the method for depositing the photolithography mask material in S1 includes one of sputtering deposition, evaporation deposition, atomic layer deposition, and chemical vapor deposition. The photolithography mask material is a hard metal, and the thickness of the photolithography mask material is 20 - 300 nm.

[0029] In S1, the mask substrate can be a quartz substrate, a glass substrate, a sapphire substrate, or an organic thin film substrate; the method for depositing the photolithography mask material can be sputtering deposition, evaporation deposition, atomic layer deposition, chemical vapor deposition, etc., and the photolithography mask material can be Cr, Mo, or other hard metals.

[0030] Based on the above embodiments, the method for preparing the mask pattern structure in S1 includes one of electron beam direct writing lithography, laser direct writing lithography, focused ion beam direct writing lithography, surface plasmon lithography, projection lithography, ion beam etching, reactive ion etching, inductively coupled plasma etching, and wet etching.

[0031] After the deposition of the photolithography mask material is completed, various photolithography or etching methods can be used to prepare the mask pattern structure. The mask pattern structure can be a periodic pattern or an aperiodic pattern, and can be a one-dimensional pattern or a two-dimensional pattern. The present disclosure has no special requirements for the photolithography mask material and the preparation method of the mask pattern structure, and subsequent preparation methods can continue after the existing mask pattern structure preparation process is completed.

[0032] Based on the above embodiments, the method for filling the transparent dielectric material in S2 includes one of sputtering deposition, evaporation deposition, atomic layer deposition, chemical vapor deposition, and spin coating; the transparent dielectric material in S2 includes one of silicon dioxide, silicon nitride, diamond, aluminum oxide, organic carbon, and magnesium fluoride. Among them, the thickness of the filled transparent dielectric material should be higher than the height of the mask pattern structure to achieve complete coverage of the mask pattern structure.

[0033] The filled transparent dielectric material should have the characteristics of high strength, high transmittance in the ultraviolet band, and high purity. Silicon dioxide, silicon nitride, diamond, aluminum oxide, magnesium fluoride, etc. can be filled by deposition methods, and organic carbon can be filled by spin coating on a spin coater.

[0034] Based on the above embodiments, the temperature of the annealing treatment in S3 is 100°C to 1000°C, the heating rate is 10°C to 100°C / minute, the cooling rate is 10°C to 50°C / minute, and the holding time is 0.5 to 10 hours.

[0035] Based on the above embodiments, the annealing treatment in S3 includes annealing the entire mask or annealing the upper surface part of the mask with the transparent dielectric material.

[0036] Annealing the mask can be carried out on the whole mask. Annealing the whole mask means putting the entire mask substrate including the transparent dielectric material into an annealing device for annealing. It can also be carried out only on the upper surface part of the mask with the transparent dielectric material. Annealing the surface means only heating the surface of the mask substrate and the transparent dielectric material, while the back surface of the mask substrate is not heated for annealing.

[0037] Annealing the mask can reduce the cavities in the transparent dielectric material, increase the hardness of the transparent dielectric material, and improve the adhesion between the transparent dielectric material and the mask substrate.

[0038] The difference between annealing the whole mask and annealing only the upper surface part of the mask with the transparent dielectric material is that for the whole mask annealing, the whole mask is put into the annealing device for annealing, while for the surface annealing, only the upper surface part of the mask with the transparent dielectric material contacts the heat source, and the bottom does not contact the heat source. Whole mask annealing is mainly applicable to the annealing process at a relatively high temperature (>300 °C), and surface annealing is mainly applicable to the annealing process at a relatively low temperature (<300 °C).

[0039] Based on the above embodiments, S4 includes: chemically mechanically polishing the surface of the mask obtained in S3 until all the parts of the transparent dielectric material higher than the mask pattern structure are removed.

[0040] Chemical Mechanical Polishing (CMP) technology is a process technology for achieving global planarization. CMP presses the workpiece to be polished on a polishing pad soaked with a polishing liquid composed of sub-micron or nano abrasive grains and a chemical solution under a certain pressure. By means of the relative movement between the workpiece to be polished and the polishing pad, the chemical reaction products formed on the surface of the workpiece to be polished are removed through the mechanical friction of the abrasive grains, realizing ultra-precision surface machining and obtaining a smooth surface. CMP removes the transparent dielectric material higher than the lithography mask material, and can just polish to the upper surface of the mask pattern structure, or can be slightly over-etched to obtain a planarized lithography mask structure.

[0041] The present disclosure also provides a lithography mask with material filling protection, which is prepared by using the aforementioned preparation method of the lithography mask with material filling protection.

[0042] Through the preparation method of the present disclosure, only conventional coating and planarization technologies are needed to obtain a lithography mask with material filling protection, which overcomes the problems such as damage and even destruction of the mask pattern structure caused by the extrusion between the mask pattern structure and the photosensitive material in the current contact lithography method, and effectively improves the service life of the lithography mask.

[0043] The present disclosure will be further described below through specific embodiments. In the following embodiments, the above-mentioned material-filled protective photolithography mask and its preparation method will be specifically described. However, the following embodiments are only used to illustrate the present disclosure, and the scope of the present disclosure is not limited thereto.

[0044] The preparation method of the material-filled protective photolithography mask in the following embodiments includes the following steps:

[0045] Step (1): Deposit a photolithography mask material on a mask substrate to prepare a mask pattern structure; equivalent to S1 above.

[0046] Step (2): Fill a transparent dielectric material on the mask pattern structure; equivalent to S2 above.

[0047] Step (3): Anneal the mask obtained in step (2); equivalent to S3 above.

[0048] Step (4): Chemically mechanically polish (CMP) the surface of the mask obtained in step (3) to remove the part of the transparent dielectric material that is higher than the photolithography mask material. The remaining transparent dielectric material and the mask pattern structure together form a planarized photolithography mask structure, that is, a material-filled protective photolithography mask; equivalent to S4 above.

[0049] Specifically, the following 3 embodiments are provided:

[0050] Embodiment 1:

[0051] As Figure 2 shown, 1 is a mask substrate, 2 is a photolithography mask material, 3 is a cavity, and 4 is a transparent dielectric material. A material-filled protective photolithography mask and its preparation method according to the present disclosure are specifically implemented as follows:

[0052] Step (11): As Figure 2 shown in (a), deposit a photolithography mask material Cr on a quartz mask substrate to prepare a mask pattern structure; the mask pattern structure is a Cr grating with a period of 64 nm, and the thickness of Cr is 50 nm;

[0053] Step (12): As Figure 2 shown in (b), fill a transparent dielectric material silicon nitride on the mask pattern structure by LPCVD method; the thickness of the transparent dielectric material silicon nitride is 200 nm;

[0054] Step (13): As Figure 2 shown in (c), anneal the entire mask including the transparent dielectric material, the annealing temperature is 500 °C, the annealing time is 3 hours, the heating rate is 20 °C / minute, and the cooling rate is 20 °C / minute; to reduce defects such as holes in the transparent dielectric material silicon nitride and improve the density and hardness of the transparent dielectric material silicon nitride;

[0055] Step (14): As Figure 2 shown in (d), chemically mechanically polish the surface of the mask to remove the silicon nitride that is higher than the lithography mask material. The remaining silicon nitride and the Cr mask pattern structure together form a planarized lithography mask structure.

[0056] Example 2:

[0057] As Figure 2 shown, 1 is a mask substrate, 2 is a lithography mask material, 3 is a cavity, and 4 is a transparent dielectric material. A method for fabricating a material-filled protected lithography mask and a method for fabricating the same according to the present disclosure are as follows:

[0058] Step (21): As Figure 2 shown in (a), deposit a lithography mask material Cr on a sapphire mask substrate by an ion beam sputtering method to prepare a mask pattern structure; the mask pattern structure is a Cr non-periodic two-dimensional pattern with a minimum line width of 22 nm, and the thickness of Cr is 60 nm;

[0059] Step (22): As Figure 2 shown in (b), fill the mask pattern structure with a transparent dielectric material alumina by a magnetron sputtering method; the thickness of the transparent dielectric material alumina is 150 nm;

[0060] Step (23): As Figure 2 shown in (c), anneal the entire sapphire mask including the transparent dielectric material at an annealing temperature of 500 °C, an annealing time of 5 hours, a heating rate of 50 °C / minute, and a cooling rate of 20 °C / minute; to reduce defects such as pores in the transparent dielectric material alumina and improve the density and hardness of the transparent dielectric material alumina;

[0061] Step (24): As Figure 2 shown in (d), chemically mechanically polish the surface of the sapphire mask to remove the alumina that is higher than the lithography mask material. The remaining alumina and the Cr mask pattern structure together form a planarized lithography mask structure.

[0062] Example 3:

[0063] As Figure 2 shown, 1 is a mask substrate, 2 is a lithography mask material, 3 is a cavity, and 4 is a transparent dielectric material. A method for fabricating a material-filled protected lithography mask and a method for fabricating the same according to the present disclosure are as follows:

[0064] Step (31): As Figure 2As shown in (a), deposit the photolithography mask material Cr on the quartz mask substrate to prepare a mask pattern structure; the mask pattern structure is a Cr grating with a period of 88 nm and a Cr thickness of 40 nm;

[0065] Step (32): As shown in (b), fill the mask pattern structure with the transparent dielectric material diamond by CVD method; the thickness of the transparent dielectric material diamond is 300 nm; Figure 2 As shown in (b), fill the mask pattern structure with the transparent dielectric material diamond by CVD method; the thickness of the transparent dielectric material diamond is 300 nm;

[0066] Step (33): As shown in (c), anneal the upper surface part of the quartz mask including the transparent dielectric material, the annealing temperature is 200 °C, the annealing time is 1 hour, the heating rate is 10 °C / min, and the cooling rate is 20 °C / min; to reduce defects such as holes in the transparent dielectric material silicon nitride and improve the density and hardness of the transparent dielectric material diamond; Figure 2 As shown in (c), anneal the upper surface part of the quartz mask including the transparent dielectric material, the annealing temperature is 200 °C, the annealing time is 1 hour, the heating rate is 10 °C / min, and the cooling rate is 20 °C / min; to reduce defects such as holes in the transparent dielectric material silicon nitride and improve the density and hardness of the transparent dielectric material diamond;

[0067] Step (34): As shown in (d), perform chemical mechanical polishing on the surface of the mask to remove the diamond higher than the photolithography mask material, and the remaining diamond and the Cr mask pattern structure together form a planarized photolithography mask structure. Figure 2 As shown in (d), perform chemical mechanical polishing on the surface of the mask to remove the diamond higher than the photolithography mask material, and the remaining diamond and the Cr mask pattern structure together form a planarized photolithography mask structure.

[0068] The present disclosure introduces high-strength materials in the contact photolithography mask pattern processing technology to fill and protect the photolithography mask and improve the mask preparation method, effectively enhancing the strength of the mask pattern structure; during contact photolithography, the contact area between the mask pattern structure and the photosensitive material is increased, thereby effectively improving the service life of the contact photolithography mask, reducing the mask processing cost at the same time, and expanding the application range of the contact photolithography technology.

[0069] The above specific embodiments further elaborate on the purpose, technical solution and beneficial effects of the present disclosure. It should be understood that the above are only specific embodiments of the present disclosure and do not limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for preparing a material-filled protective photolithography mask, characterized in that, Including: S1, depositing a photolithography mask material on a mask substrate to prepare a mask pattern structure; The photolithography mask material is a hard metal, and the thickness of the photolithography mask material is 20 - 300 nm; S2, filling a transparent dielectric material into the mask pattern structure, where the transparent dielectric material is used to enhance the structural strength of the mask pattern structure, and the transparent dielectric material includes silicon nitride, diamond, and alumina; S3, annealing the mask obtained in S2; the temperature of the annealing treatment is 100°C - 1000°C, the heating rate is 10°C - 100°C / minute, the cooling rate is 10°C - 50°C / minute, and the holding time is 0.5 - 10 hours; S4, chemically mechanically polishing the surface of the mask obtained in S3 to expose the mask pattern structure, obtaining a photolithography mask protected by material filling.

2. The method for preparing a material-filled protective photolithography mask according to claim 1, characterized in that, The method for depositing the photolithography mask material in S1 includes one of sputtering deposition, evaporation deposition, atomic layer deposition, and chemical vapor deposition.

3. The method for preparing a material-filled protective photolithography mask according to claim 1, characterized in that, The method for preparing the mask pattern structure in S1 includes one of electron beam direct writing lithography, laser direct writing lithography, focused ion beam direct writing lithography, surface plasmon lithography, projection lithography, ion beam etching, reactive ion etching, inductively coupled plasma etching, and wet etching.

4. The method for preparing a material-filled protective photolithography mask according to claim 1, characterized in that, The method for filling the transparent dielectric material in S2 includes one of sputtering deposition, evaporation deposition, atomic layer deposition, chemical vapor deposition, and spin coating.

5. The method for preparing a material-filled protective photolithography mask according to claim 1, characterized in that, The annealing treatment in S3 includes annealing the whole mask or annealing the upper surface part of the mask with the transparent dielectric material.

6. The method for preparing a material-filled protective photolithography mask according to claim 1, characterized in that, S4 includes: Chemically mechanically polishing the surface of the mask obtained in S3 until all the parts of the transparent dielectric material higher than the mask pattern structure are removed.

7. A material-filled protective photolithography mask, characterized in that, The photolithography mask is prepared by using the preparation method of the material-filled protected photolithography mask according to any one of claims 1 - 6.

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