CN114839834A

CN114839834A - Mask base plate for projection type photoetching, photomask and preparation method thereof

Info

Publication number: CN114839834A
Application number: CN202210262229.7A
Authority: CN
Inventors: 季明华; 黄早红; 林岳明
Original assignee: Shanghai Chuanxin Semiconductor Co ltd
Current assignee: Shanghai Chuanxin Semiconductor Co ltd
Priority date: 2022-03-16
Filing date: 2022-03-16
Publication date: 2022-08-02

Abstract

The invention provides a mask base plate for projection photoetching, a photomask and a preparation method thereof, wherein the mask base plate comprises: a light-transmitting substrate; a shading layer covering the surface of the light-transmitting substrate; and the surface plasmon layer covers the surface of the shading layer and is used for generating surface plasmon under the action of exposure light so as to enhance the intensity of the exposure light on the surface and the periphery of the patterned mask base plate. According to the invention, the surface plasma excimer layer is arranged on the surface of the mask base plate, and the field intensity of the exposure window light on the patterned surface of the mask base plate can be effectively enhanced through the interaction of the exposure light and the surface plasma excimer layer, so that the resolution and the contrast of the projection type photoetching process are greatly improved.

Description

Mask base plate for projection type photoetching, photomask and preparation method thereof

Technical Field

The invention belongs to the field of semiconductor manufacturing, and particularly relates to a mask base plate for projection lithography, a photomask and a preparation method thereof.

Background

The photolithography technology is accompanied by the continuous progress of the manufacturing method of the integrated circuit, the line width is continuously reduced, the area of the semiconductor device is becoming smaller and smaller, and the layout of the semiconductor is developed from the common single function separation device to the integrated circuit integrating high-density and multi-function; from the first IC (integrated circuit) to the next LSI (large scale integrated circuit), VLSI (very large scale integrated circuit), to today's ULSI (ultra large scale integrated circuit), the area of the device is further reduced. Considering the restrictions of adverse factors such as complexity of process development, long-term performance, high cost and the like, how to further improve the integration density of devices on the basis of the prior art level to obtain as many effective chips as possible on the same silicon chip, thereby improving the overall benefits will be more and more emphasized by chip manufacturers. The projection lithography process plays a key role, and the projection lithography apparatus, process and mask technology are important in the case of the projection lithography technology.

The simplest binary photomasks (BIM) or phase shift Photomasks (PSM) have a mask layer Cr with a thickness of about 50-100 nm. The phase shift of the phase shift photomask may be provided by the trench depth on the patterned quartz substrate or by the phase shift layer material.

The bi-layer phase shift photomask may include a light-shielding Cr layer and a MoSiON layer having a MoSiON layer thickness of about 50-150nm to ensure its phase shift and attenuation functions. After patterning of the bilayer phase shift photomask is completed, the amount of phase shift and the amount of attenuation of the bilayer phase shift photomask are determined by the thickness of the MoSiON layer. The phase shift photomask may also include a multi-layer structure to achieve better photomask performance.

However, the above photomask still has problems of insufficient resolution and contrast of the pattern on the silicon wafer.

It should be noted that the above background description is only for the convenience of clear and complete description of the technical solutions of the present application and for the understanding of those skilled in the art. Such solutions are not considered to be known to the person skilled in the art merely because they have been set forth in the background section of the present application.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, it is an object of the present invention to provide a mask blank, a photomask and a method for manufacturing the same, which are used to solve the problems of insufficient resolution and contrast of the photomask in the prior art of projection type.

To achieve the above and other related objects, the present invention provides a mask blank for projection lithography, comprising: a light-transmitting substrate; the shading layer covers the surface of the light-transmitting substrate; and the surface plasmon layer is covered on the surface of the shading layer and used for generating surface plasmon under the action of exposure light so as to enhance the field intensity of the exposure light of the exposure window on the surface after the mask base plate is patterned.

Optionally, the material of the surface plasmon layer includes one of a metal and a transparent conductive oxide, the metal includes one or a combination of Al, Au, Ag and Pd, and the transparent conductive oxide includes one or a combination of indium oxide, tin oxide, indium tin oxide and zinc oxide.

Optionally, the thickness of the surface plasmon layer is between one half and three times the wavelength of the exposure light.

Optionally, the mask substrate further includes a phase shift material layer, and the phase shift material layer is located between the light-transmitting substrate and the light-shielding layer.

Optionally, the material of the transparent substrate includes synthetic quartz glass, the material of the light shielding layer includes one or a combination of several of chromium, chromium oxide and chromium nitride, and the material of the phase shift material layer includes one or a combination of several of molybdenum silicon oxide, molybdenum silicon oxynitride, molybdenum silicon oxycarbide, chromium silicon oxide, chromium silicon oxynitride and chromium silicon oxycarbide.

The present invention also provides a method of preparing a mask blank for projection lithography according to any one of the above aspects, comprising the steps of: providing a light-transmitting substrate; forming a light shielding layer on the light-transmitting substrate; and forming a surface plasma laser element layer on the light shielding layer.

The present invention also provides a photomask for projection lithography, the photomask comprising: a light-transmitting substrate; the shading layer covers the surface of the light-transmitting substrate; the surface plasmon layer is covered on the surface of the shading layer and used for generating surface plasmon under the action of exposure light so as to enhance the field intensity of the exposure light on the surface and the edge of an exposure window of the photomask; and the exposure window comprises an opening pattern penetrating through the surface plasma laser element layer and the light shielding layer.

Optionally, the photomask further includes a phase shift material layer, the phase shift material layer is located between the light-transmitting substrate and the light-shielding layer, and the pattern of the exposure window stops at a top surface of the phase shift material layer.

Optionally, at least one of the opening patterns comprises a subwavelength hole array structure.

Optionally, the sub-wavelength hole array structure includes a nano slit and/or a nano hole therein.

Optionally, the sub-wavelength range of the sub-wavelength hole array structure is one eighth to one half of the wavelength of the exposure light.

Optionally, the subwavelength hole array structure is disposed in a portion of the opening pattern for enhancing light transmission of a specific region.

The present invention also provides a method for manufacturing a photomask according to any one of the above aspects, comprising the steps of: providing a light-transmitting substrate; forming a light shielding layer on the light-transmitting substrate; forming a surface plasma excimer layer on the light-shielding layer; and forming an exposure window in the surface plasma laser element layer and the light shielding layer, wherein the exposure window comprises a pattern penetrating through the surface plasma laser element layer and the light shielding layer.

As described above, the mask blank, the photomask and the method for manufacturing the same according to the present invention have the following advantageous effects:

according to the mask base plate, the photomask and the preparation method thereof, the surface plasma laser layer is arranged on the surface of the mask base plate, and the light intensity around the edge of the surface exposure window of the mask plate (after patterning) can be effectively enhanced through the interaction of exposure light (UV light sources such as 365nm i-line light, 248nm ultraviolet light UV, 193nm deep ultraviolet light DUV and the like) and the surface plasma laser layer, so that the resolution and the contrast of a photoetching process are greatly improved.

The invention can further redesign the exposure window through the patterns of the plasmon layer and the exposure window, the small nanometer slits or the nanometer holes or the combination of the small nanometer slits and the nanometer holes to form an abnormal optical transmission (EOT) coupling enhancement structure so as to enhance the intensity of the whole exposure light of the exposure window, thereby further obtaining better resolution and contrast in the projection type photoetching process.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the application, are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. It is to be understood that the drawings in the following description are of some embodiments of the application only.

Fig. 1 to 3 are schematic views showing structures at respective steps of a method for manufacturing a mask blank according to embodiment 1 of the present invention, in which fig. 3 is a schematic view showing a structure of a mask blank according to an embodiment of the present invention.

Fig. 4 to 7 are schematic views showing structures at respective steps of the method for manufacturing a mask blank according to embodiment 2 of the present invention, wherein fig. 7 is a schematic view showing a structure of a mask blank according to an embodiment of the present invention.

Fig. 8 is a schematic structural diagram of a photomask (after patterning) according to embodiment 3 of the present invention.

Fig. 9 is a schematic structural diagram of a photomask (after patterning) according to embodiment 4 of the present invention.

Fig. 10 to 13 are schematic diagrams illustrating the pattern arrangement in the exposure window of the photomask according to the embodiment of the present invention.

Description of the element reference numerals

301 light-transmitting substrate

302 light-shielding layer

303 surface plasmon layer

304 phase shift material layer

401 exposure window

4011 nanometer slit

4012A nanopore

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps or components.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.

As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structures are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

Spatially relative terms, such as "under," "below," "lower," "below," "over," "upper," and the like, may be used herein for convenience in describing the relationship of one element or feature to another element or feature illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

In the context of this application, a structure described as a first feature being "on" a second feature may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.

Example 1

As shown in fig. 3, the present embodiment provides a mask blank for projection lithography, the mask blank comprising: a light-transmitting substrate 301, a light-shielding layer 302, and a surface plasmon layer 303.

In one embodiment, the light transmittance of the light-transmitting substrate 301 is greater than 80%, and the light-transmitting substrate 301 may include synthetic quartz glass, soda glass, or the like, but is preferably synthetic quartz glass. The thickness of the transparent substrate 301 may be a conventional thickness or thinner, and by way of example, the thickness of the transparent substrate 301 may be between 2 mm and 8 mm, for example, the thickness of the transparent substrate 301 may be 6 mm.

As shown in fig. 3, the light-shielding layer 302 covers the surface of the light-transmitting substrate 301. The light shielding layer 302 may be, for example, one or a combination of chromium (Cr), chromium nitride (CrN), chromium oxide (CrO), and the like, and the light shielding layer 302 may be formed on the light-transmitting substrate 301 by, for example, a magnetron sputtering process.

As shown in fig. 3, the surface plasmon layer 303 covers the surface of the light shielding layer 302, and the surface plasmon layer 303 is configured to generate surface plasmons under the action of exposure light to enhance the field intensity of the exposure light of the exposure window on the surface after the mask substrate is patterned.

In one embodiment, the exposure light includes, for example, 365nm i-line light, 248nm UV light, 193nm DUV light, and the like.

In one embodiment, surface plasmons are generated when exposure light is irradiated to the surface plasmon layer 303, and the surface plasmons of this embodiment, which are surface wave modes of an electromagnetic field propagating at an interface between a conductor (e.g., a metal) and a medium, are formed by bulk oscillation of a high-density free electron gas in the conductor under excitation of the electromagnetic field of the exposure light, and have a high near-field enhancement effect and a high optical field locality of a super-diffraction limit, so that the field intensity of the exposure light on the surface of the mask substrate can be effectively enhanced.

In one embodiment, the material of the surface plasmon layer 303 comprises one of a metal and a transparent conductive oxide, wherein the metal comprises one or a combination of Al, Au, Ag and Pd, and the transparent conductive oxide comprises one or a combination of indium oxide, tin oxide, indium tin oxide and zinc oxide. In this embodiment, the material of the surface plasmon layer 303 is gold (Au).

In one embodiment, since the surface plasmon layer 303 needs to be patterned in a subsequent process, the surface plasmon layer 303 with too large thickness increases the time and difficulty of the patterning process, and is likely to cause particle residue, the surface plasmon layer 303 with too small thickness, the surface plasmon effect generated thereby is reduced, which is disadvantageous for the enhancement of the exposure light on the surface of the mask substrate, and therefore, the surface plasmon layer 303 has a preferable thickness range, in this embodiment, the thickness of the surface plasmon layer 303 is between one half to three times of the wavelength of the exposure light, so as to ensure the time and difficulty required for patterning in the subsequent process, and on the other hand, the intensity of the surface plasmon effect can be ensured, so that the field intensity of the exposure light on the surface of the mask base plate is effectively and greatly enhanced. More preferably, the thickness of the surface plasmon layer 303 is between one half and one time of the wavelength of the exposure light, so as to further improve the above effect.

As shown in fig. 1 to 3, the present embodiment also provides a method for manufacturing a mask blank for projection lithography, the method comprising the steps of:

as shown in fig. 1, step 1) is performed to provide a transparent substrate 301.

In one embodiment, the method further includes a step of cleaning the transparent substrate 301 to remove polymer, impurity particles, and the like on the transparent substrate 301.

As shown in fig. 2, step 2) is then performed to form a light-shielding layer 302 on the transparent substrate 301.

In one embodiment, the light-shielding layer 302 may be formed on the transparent substrate 301 by, for example, a magnetron sputtering process, and the light-shielding layer 302 may be, for example, chromium (Cr), chromium nitride (CrN), chromium oxide (CrO), or the like.

As shown in fig. 3, step 3) is finally performed to form a surface plasmon layer 303 on the light shielding layer 302, where the surface plasmon layer 303 is used to generate surface plasmons under the action of the exposure light to enhance the field intensity of the exposure light at the exposure window on the surface after the mask substrate is patterned.

Since the surface plasmon layer 303 needs to be patterned in the subsequent process, the surface plasmon layer 303 with too large thickness increases the time and difficulty of the patterning process, and is likely to cause particle residue, and the surface plasmon layer 303 with too small thickness, the surface plasmon effect generated thereby is reduced, which is disadvantageous for the enhancement of the field intensity of the exposure light on the surface of the mask substrate, and therefore, the surface plasmon layer 303 has a preferable thickness range, in this embodiment, the thickness of the surface plasmon layer 303 is between one half to three times of the wavelength of the exposure light, so as to ensure the time and difficulty required for patterning in the subsequent process, and on the other hand, the intensity of the surface plasmon effect can be ensured, so that the field intensity of the exposure light on the surface of the mask base plate is effectively and greatly enhanced. More preferably, the thickness of the surface plasmon layer 303 is between one half and one time of the wavelength of the exposure light, so as to further improve the above effect.

In one embodiment, the surface plasmon layer 303 may be formed on the light-shielding layer 302 by, for example, a magnetron sputtering process, a chemical vapor deposition process, or the like. The material of the surface plasmon layer 303 includes one of a metal including one of Al, Au, Ag, and Pd, and a transparent conductive oxide including one of indium oxide, tin oxide, indium tin oxide, and zinc oxide. In this embodiment, the surface plasmon layer 303 is made of gold (Au), and is formed on the light shielding layer 302 by a magnetron sputtering process, and the surface plasmon layer 303 prepared by the magnetron sputtering process has high thickness uniformity and precision of thickness control.

Example 2

As shown in fig. 7, this embodiment provides a method for manufacturing a mask substrate for projection lithography, the basic steps of the manufacturing method are as in embodiment 1, wherein the difference from embodiment 1 is that the mask substrate further includes a phase shift material layer 304, and the phase shift material layer 304 is located between the light-transmitting substrate 301 and the light-shielding layer 302.

As shown in fig. 4 to 7, this embodiment further provides a method for manufacturing a mask blank, which basically includes the steps of embodiment 1, wherein the method is different from embodiment 1 in that the method further includes the steps of: between the light-shielding layers 302, a phase shift material layer 304 is formed on the light-transmitting substrate 301.

In one embodiment, the phase shift material layer 304 is made of one of molybdenum silicon oxide, molybdenum silicon oxynitride, molybdenum silicon oxycarbide, chromium silicon oxide, chromium silicon oxynitride, and chromium silicon oxycarbide, wherein the composition can vary and can determine the degree of phase transition and/or optical attenuation. By controlling the thickness and material composition of the phase shift material layer 304 to control the phase transition and/or light attenuation ratio of the exposure light passing through the phase shift material layer 304, for example, the phase shift material layer 304 can change the phase transition of the exposure light passing through the phase shift material layer 304 by 0-180 degrees, such as 90 degrees, 180 degrees, etc., according to the difference of the composition or thickness of different phase shift material layers 304. The phase-shift material layer 304 has a light attenuation ratio of 0-80%, for example, 20%, 30%, 50%, 60% or the like, with respect to exposure light transmitted through the phase-shift material layer 304.

Example 3

As shown in fig. 1 to 3, 8, and 10 to 13, the present embodiment provides a photomask for projection lithography, including: a light-transmitting substrate 301, a light-shielding layer 302, a surface plasmon layer 303, and an exposure window 401.

As shown in fig. 3, the surface plasmon layer 303 covers the surface of the light shielding layer 302, and the surface plasmon layer 303 is configured to generate surface plasmons under the action of exposure light, so as to enhance the field intensity of the exposure light on the surface and the edge of the exposure window of the photomask.

In one embodiment, surface plasmons are generated when exposure light is irradiated to the surface plasmon layer 303, and the surface plasmons of this embodiment, which are surface wave modes of an electromagnetic field propagating at an interface between a conductor (e.g., a metal) and a medium, are formed by bulk oscillation of a high-density free electron gas in the conductor under excitation of an electric field of the exposure light, and have a high near-field enhancement effect and a high optical field locality of a super-diffraction limit, so that the field intensity of the exposure light on the surface of the mask substrate can be effectively enhanced.

In one embodiment, the material of the surface plasmon layer 303 comprises one of a metal comprising one of Al, Au, Ag, and Pd, and a transparent conductive oxide comprising one of indium oxide, tin oxide, indium tin oxide, and zinc oxide. In this embodiment, the material of the surface plasmon layer 303 is gold (Au).

In one embodiment, since the surface plasmon layer 303 needs to be patterned in a subsequent process, the surface plasmon layer 303 with too large thickness increases the time and difficulty of the patterning process, and is likely to cause particle residue, the surface plasmon layer 303 with too small thickness, the surface plasmon effect generated thereby is reduced, which is disadvantageous for the enhancement of the field intensity of the exposure light on the surface of the mask substrate, and therefore, the surface plasmon layer 303 has a preferable thickness range, in this embodiment, the thickness of the surface plasmon layer 303 is between one half to three times of the wavelength of the exposure light, so as to ensure the time and difficulty required for patterning in the subsequent process, and on the other hand, the intensity of the surface plasmon effect can be ensured, so that the field intensity of the exposure light on the surface of the mask base plate is effectively and greatly enhanced. More preferably, the thickness of the surface plasmon layer 303 is between one half and one time of the wavelength of the exposure light, so as to further improve the above effect.

As shown in fig. 8, the exposure window 401 includes an opening pattern penetrating the surface plasmon layer 303 and the light shielding layer 302, and the plasmon layer and the pattern constitute an extraordinary ray transmission EOT coupling enhancement structure.

In one embodiment, at least one of the opening patterns includes a sub-wavelength hole array structure including nano slits and/or nano holes, a sub-wavelength range of the sub-wavelength hole array structure is one eighth to one half of a wavelength of the exposure light, and the sub-wavelength hole array structure is disposed in a portion of the opening pattern for enhancing light transmission of a specific region. When exposure light is normally incident on the surface plasmon layer 303 with the exposure window 401, surface plasmon polariton is generated by excitation, the surface plasmon polariton propagates to the opening pattern of the exposure window 401 along the metal surface and is converted into a transmission field through the pattern, and the transmission field interferes with a field directly transmitted by the exposure light at the opening pattern to form an enhanced transmission field.

In one embodiment, as shown in fig. 10, the opening pattern of the exposure window 401 may coincide with the exposure window 401.

As shown in fig. 11 to 13, the exposure window 401 includes a plurality of opening patterns arranged at intervals and penetrating through the surface plasmon layer 303 and the light shielding layer 302. For example, the width of the opening pattern of the exposure window 401 is at least one eighth of the wavelength of the exposure light, and the distance between the opening patterns of the exposure window 401 is at least one eighth of the wavelength of the exposure light.

As shown in fig. 11, in an embodiment, the opening pattern of the exposure window 401 includes a plurality of nano slits 4011 arranged at intervals in the exposure window 401, and the width and the interval of the nano slits 4011 in the exposure window 401 are one eighth to one half of the wavelength of the exposure light. In this embodiment, due to the strong near-field coupling of the localized surface plasmon of the surface plasmon layer 303 near the nanoslit 4011 and the localized surface plasmon between adjacent nanoslits 4011, an enhanced transmission peak with high transmission and narrow bandwidth can be obtained, and this embodiment can effectively adjust the abnormal optical transmission (EOT) characteristic by changing the parameters including the width of the nanoslit 4011.

As shown in fig. 12, in another embodiment, the opening pattern of the exposure window 401 includes a plurality of nano holes 4012 arranged at intervals in the exposure window 401, the width and the interval of the nano holes 4012 in the exposure window 401 are one eighth to one half of the wavelength of the exposure light, and the nano holes 4012 may be, for example, circular holes or elliptical holes. To further obtain a clearer exposure window 401 boundary, a nano slit 4011 may be provided at the exposure window 401 boundary, as shown in fig. 12. In this embodiment, due to the strong near-field coupling of the localized surface plasmon of the surface plasmon layer 303 near the nanopore 4012 and the localized surface plasmon between adjacent nanopores 4012, a high transmission and a narrow bandwidth enhanced transmission peak can be obtained, and this embodiment can effectively adjust the extraordinary light transmission (EOT) characteristics by changing parameters including the size and shape of the nanopore 4012.

As shown in fig. 13, in a further embodiment, the opening pattern of the exposure window 401 includes a combination of a plurality of nano holes 4012 and a plurality of nano slits 4011 located in the exposure window 401, and the width and the pitch of the nano slits and/or the nano holes 4012 in the exposure window 401 are one eighth to one half of the wavelength of the exposure light, so as to obtain an extraordinary light transmission (EOT) characteristic better than that of the exposure window 401 pattern of fig. 11 or 12, and at the same time, to effectively expand the functionality of the photomask. To further obtain a clearer exposure window 401 boundary, a nano slit 4011 may be provided at the exposure window 401 boundary, as shown in fig. 13.

As shown in fig. 1 to 3, 8, and 10 to 13, the present invention also provides a method for manufacturing a photomask for projection lithography, including the steps of:

As shown in fig. 3, step 3) is finally performed to form a surface plasmon layer 303 on the light shielding layer 302, where the surface plasmon layer 303 is used to generate surface plasmons under the action of the exposure light so as to enhance the field strength of the exposure light on the surface and edge of the exposure window of the photomask.

As shown in fig. 8, step 4) is performed next, an exposure window 401 is formed in the surface plasmon layer 303 and the light shielding layer 302, the exposure window 401 includes a pattern penetrating through the surface plasmon layer 303 and the light shielding layer 302, and the plasmon layer and the pattern constitute an extraordinary light transmission EOT coupling enhancement structure.

For example, the exposure window 401 may be formed by a dry etching process equal to that of the surface plasmon layer 303 and the light shielding layer 302.

As shown in fig. 11 to 13, the exposure window 401 includes a plurality of patterns arranged at intervals penetrating the surface plasmon layer 303 and the light-shielding layer 302. For example, the width of the opening pattern of the exposure window 401 is at least one eighth of the wavelength of the exposure light, and the distance between the opening patterns of the exposure window 401 is at least one eighth of the wavelength of the exposure light.

As shown in fig. 11, in an embodiment, the opening pattern of the exposure window 401 includes a plurality of nano slits 4011 that are located in the exposure window 401 and arranged at intervals, and the width and the interval of the nano slits 4011 in the exposure window 401 are one eighth to one half of the wavelength of the exposure light. In this embodiment, due to the strong near-field coupling of the localized surface plasmon of the surface plasmon layer 303 near the nanoslit 4011 and the localized surface plasmon between adjacent nanoslits 4011, an enhanced transmission peak with high transmission and narrow bandwidth can be obtained, and this embodiment can effectively adjust the abnormal optical transmission (EOT) characteristic by changing the parameters including the width of the nanoslit 4011.

It should be noted that when the light shielding layer 302 has a sufficiently high free electron gas therein, the light shielding layer 302 can simultaneously serve as the surface plasmon layer 303, and the effect of enhancing the coupling of the extraordinary light transmission EOT can also be generated by the above-mentioned opening pattern design of the exposure window 401.

Example 4

As shown in fig. 9 to 13, the present embodiment provides a photomask whose basic structure is as in embodiment 3, wherein the difference from embodiment 3 is that: the photomask further comprises a phase shift material layer 304, wherein the phase shift material layer 304 is located between the light-transmitting substrate 301 and the light-shielding layer 302, and the pattern of the exposure window 401 stops at the top surface of the phase shift material layer 304.

As shown in fig. 4 to 7 and 9 to 13, the present embodiment provides a method for manufacturing a photomask, which includes the basic steps of embodiment 3, wherein the method is different from embodiment 3 in that the method further includes the steps of: between the formation of the light-shielding layer 302, a phase-shift material layer 304 is formed on the light-transmitting substrate 301, and the pattern of the exposure window 401 stops on the top surface of the phase-shift material layer 304.

In one embodiment, the phase shift material layer 304 is made of one or more of molybdenum silicon oxide, molybdenum silicon oxynitride, molybdenum silicon oxycarbide, chromium silicon oxide, chromium silicon oxynitride, and chromium silicon oxycarbide, wherein the composition may vary and determine the degree of phase transition and/or optical attenuation. By controlling the thickness and material composition of the phase shift material layer 304 to control the phase transition and/or light attenuation ratio of the exposure light passing through the phase shift material layer 304, for example, the phase shift material layer 304 can change the phase transition of the exposure light passing through the phase shift material layer 304 by 0-180 degrees, such as 90 degrees, 180 degrees, etc., according to the difference of the composition or thickness of different phase shift material layers 304. The phase-shift material layer 304 attenuates the light generated by the exposure light passing through the phase-shift material layer 304 by a ratio of 0 to 80%, for example, 20%, 30%, 50%, 60%, or the like.

according to the mask base plate, the photomask and the preparation method thereof, the surface plasma laser layer is arranged on the surface of the mask base plate, and the light intensity around the edge of the surface exposure window of the mask plate (after patterning) can be effectively enhanced through the interaction of exposure light (such as 365nm i-line light, 248nm ultraviolet light UV, 193nm deep ultraviolet light DUV and the like) and the surface plasma laser layer, so that the resolution and the contrast of a photoetching process are greatly improved.

The invention can further redesign the exposure window through the opening patterns of the plasmon layer and the exposure window and through the small nano slits or nano holes or the combination of the small nano slits and the nano holes to form an abnormal optical transmission (EOT) coupling enhancement structure so as to enhance the intensity of the whole exposure light of the exposure window, thereby further obtaining better resolution and contrast in the projection type photoetching process.

Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A mask substrate for projection lithography, the mask substrate comprising:

a light-transmitting substrate;

the shading layer covers the surface of the light-transmitting substrate;

and the surface plasmon layer is covered on the surface of the shading layer and used for generating surface plasmon under the action of exposure light so as to enhance the field intensity of the exposure light of the exposure window on the surface after the mask base plate is patterned.

2. The mask template for projection lithography according to claim 1, wherein: the material of the surface plasma excimer layer comprises one of metal and transparent conductive oxide, the metal comprises one or a combination of more of Al, Au, Ag and Pd, and the transparent conductive oxide comprises one or a combination of more of indium oxide, tin oxide, indium tin oxide and zinc oxide.

3. The mask template for projection lithography according to claim 1, wherein: the thickness of the surface plasma excimer layer is between one half and three times of the wavelength of the exposure light.

4. The mask template for projection lithography according to claim 1, wherein: the mask base plate further comprises a phase shift material layer, and the phase shift material layer is located between the light-transmitting substrate and the light shielding layer.

5. The mask template for projection lithography according to claim 4, wherein: the material of the transparent substrate comprises synthetic quartz glass, the material of the light shielding layer comprises one or a combination of several of chromium, chromium oxide and chromium nitride, and the material of the phase shift material layer comprises one or a combination of several of molybdenum silicon oxide, molybdenum silicon oxynitride, molybdenum silicon oxycarbide, chromium silicon oxide, chromium silicon oxynitride and chromium silicon oxycarbide.

6. A method of preparing a mask blank for projection lithography according to any one of claims 1 to 5, comprising the steps of:

providing a light-transmitting substrate;

forming a light shielding layer on the light-transmitting substrate;

and forming a surface plasma laser element layer on the light shielding layer.

7. A photomask for projection lithography, said photomask comprising:

a light-transmitting substrate;

the shading layer covers the surface of the light-transmitting substrate;

the surface plasmon layer is covered on the surface of the shading layer and used for generating surface plasmon under the action of exposure light so as to enhance the field intensity of the exposure light on the surface and the edge of an exposure window of the photomask;

and the exposure window comprises an opening pattern penetrating through the surface plasma laser element layer and the light shielding layer.

8. The photomask for projection lithography according to claim 7, wherein: the material of the surface plasma excimer layer comprises one of metal and transparent conductive oxide, the metal comprises one or a combination of more of Al, Au, Ag and Pd, and the transparent conductive oxide comprises one or a combination of more of indium oxide, tin oxide, indium tin oxide and zinc oxide.

9. The photomask for projection lithography according to claim 7, wherein: the thickness of the surface plasma laser element layer is between one half and three times of the wavelength of the exposure light.

10. The photomask for projection lithography according to claim 7, wherein: the photomask also comprises a phase shift material layer, the phase shift material layer is positioned between the light-transmitting substrate and the light shielding layer, and the pattern of the exposure window is stopped at the top surface of the phase shift material layer.

11. The photomask for projection lithography according to claim 10, wherein: the material of the transparent substrate comprises synthetic quartz glass, the material of the light shielding layer comprises one or a combination of several of chromium, chromium oxide and chromium nitride, and the material of the phase shift material layer comprises one or a combination of several of molybdenum silicon oxide, molybdenum silicon oxynitride, molybdenum silicon oxycarbide, chromium silicon oxide, chromium silicon oxynitride and chromium silicon oxycarbide.

12. The photomask for projection lithography according to claim 7, wherein: at least one of the opening patterns includes a subwavelength hole array structure.

13. The photomask for projection lithography according to claim 12, wherein: the subwavelength hole array structure comprises a nanometer slit and/or a nanometer hole.

14. The photomask for projection lithography according to claim 12, wherein: the sub-wavelength range of the sub-wavelength long hole array structure is one eighth to one half of the wavelength of the exposure light.

15. The photomask for projection lithography according to claim 12, wherein: the sub-wavelength hole array structure is arranged on a part of the opening pattern for enhancing light transmission of a specific area.

16. A method of manufacturing a photomask for projection lithography according to any one of claims 7 to 15, comprising the steps of:

providing a light-transmitting substrate;

forming a light shielding layer on the light-transmitting substrate;

forming a surface plasma excimer layer on the light-shielding layer;

and forming an exposure window in the surface plasma laser element layer and the light shielding layer, wherein the exposure window comprises an opening pattern penetrating through the surface plasma laser element layer and the light shielding layer.