CN114678260A - Anti-reflection layer and patterning method - Google Patents

Abstract

The invention discloses an anti-reflection layer and a patterning method, relates to the technical field of semiconductor manufacturing, and aims to improve the pattern profile defect caused by reflection, realize the precision of a pattern, improve the product yield and improve the equipment integration level by implementing a fine mode. The anti-reflective layer contains a porous structure. The invention also provides a patterning processing method.

Description

Anti-reflection layer and patterning method

Technical Field

The invention relates to the technical field of semiconductor manufacturing, in particular to an anti-reflection layer and a patterning method.

Background

In the photoetching process, in order to ensure that the formed photoresist pattern is relatively accurate, an anti-reflection layer is formed on the surface of the substrate before a photoresist layer is formed on the substrate, and the anti-reflection layer is utilized to inhibit the reflection phenomenon of the substrate, so that the influence of the reflection phenomenon on the photoresist pattern is reduced.

The effect of the antireflection layer on inhibiting the reflection of light by the substrate is influenced by the thickness and the refractive index of the antireflection layer. However, it is difficult to improve the accuracy of the photoresist pattern by optimizing the refractive index of the anti-reflective layer, so that the accuracy of the formed photoresist pattern is not guaranteed.

Disclosure of Invention

The present invention is directed to an anti-reflective layer and a patterning method for improving a pattern profile defect due to reflection to achieve a precise pattern, thereby increasing a product yield and increasing a device integration level by implementing a fine mode.

In order to achieve the above object, the present invention provides an anti-reflection layer having a porous structure.

Optionally, the porous structure is a shaped porous structure.

Optionally, each pore in the porous structure has a pore diameter of

Optionally, the refractive index of the anti-reflection layer is 1.5-2.5.

Optionally, the porous structure is a plurality of bubble structures formed in the anti-reflection layer; alternatively, the porous structure is a plurality of micro-porous structures formed within the anti-reflective layer.

Optionally, the anti-reflection layer is made of one or more of silicon oxynitride, silicon nitride, silicon oxide, titanium nitride, and gallium nitride.

Compared with the prior art, the anti-reflection layer provided by the invention contains a porous structure. Each pore structure can be considered an air film. Further, the refractive index of air is smaller than that of the antireflection layer material, so that the refractive index of the entire antireflection layer including a porous structure is lowered. Based on this, even if light is emitted to the substrate through the anti-reflection layer, the substrate reflects the light. When the reflected light is refracted to the air by the anti-reflection layer with the porous structure, the exit angle of the reflected light is reduced due to the relatively low overall refractive index of the anti-reflection layer, and therefore, the resolvable size of the light refracted by the anti-reflection layer with the porous structure is smaller relative to the critical size of the photoresist pattern. At this time, although there is still a problem of light refraction, the degree of influence of the refracted light on the photoresist pattern has been reduced, thereby ensuring the fineness of the photoresist pattern. Meanwhile, the refractive index of the porous structure is relatively low, so that part of reflected light is reflected by the porous structure to the direction of the substrate. Based on the phase cancellation principle, the energy of the light rays is gradually lost under the repeated reflection, so that the light rays have small influence on the photoresist pattern even if the light rays irradiate to the photoresist layer from the anti-reflection layer, and the fineness of the photoresist pattern is further ensured.

The invention also provides a patterning method, which is characterized by comprising the following steps:

providing a substrate;

forming an anti-reflection layer on a substrate; the anti-reflection layer contains a porous structure;

and forming a photoresist pattern on the anti-reflection layer.

Optionally, forming an anti-reflection layer on the substrate includes: and forming an anti-reflection layer on the substrate by adopting a plasma enhanced chemical vapor deposition process.

Preferably, the anti-reflective layer is formed on the substrate by a plasma enhanced chemical vapor deposition process, including:

in the plasma enhanced chemical vapor deposition process, a solvent or a polymer precursor solution is added to form an anti-reflection layer with a porous structure inside on a substrate.

Optionally, forming an anti-reflection layer on the substrate includes: and forming an anti-reflection layer with a porous structure inside on the substrate by adopting a spin coating method.

Preferably, the spin coating method for forming an anti-reflection layer having a porous structure therein on a substrate includes:

spin-coating a viscous material layer with air bubbles on a substrate;

and performing heat treatment on the adhesive material layer to form an anti-reflection layer with air bubbles inside on the substrate.

Preferably, the spin coating method is used to form an anti-reflection layer having a porous structure inside on the substrate, and further includes:

before a viscous material layer with air bubbles is coated on a substrate in a spin coating mode, a viscous material sol is formed through a sol-gel method.

Optionally, forming a photoresist pattern on the anti-reflection layer includes:

forming a photoresist layer covering the anti-reflection layer;

and exposing and developing the photoresist layer to form a photoresist pattern on the anti-reflection layer.

Compared with the prior art, the beneficial effect of the patterning method provided by the invention is the same as that of the anti-reflection layer provided by the technical scheme, and the detailed description is omitted here.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a flow chart illustrating a patterning method in the prior art;

FIG. 2 is a cross-sectional view of an anti-reflective layer provided in accordance with an embodiment of the present invention;

FIG. 3 is a schematic diagram of a substrate after providing a substrate according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of an embodiment of the present invention after forming an anti-reflection layer;

FIG. 5 is a schematic structural diagram illustrating a photoresist pattern formed according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram obtained after the patterning method provided by the embodiment of the invention.

Reference numerals:

100-substrate, 101-antireflective layer, 102-photoresist layer, 103-mask plate, L-minimum resolution distance.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is illustrative only and is not intended to limit the scope of the present disclosure. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure.

Various structural schematics according to embodiments of the present disclosure are shown in the figures. The figures are not drawn to scale, wherein certain details are exaggerated and possibly omitted for clarity of presentation. The shapes of various regions, layers, and relative sizes and positional relationships therebetween shown in the drawings are merely exemplary, and deviations may occur in practice due to manufacturing tolerances or technical limitations, and a person skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions, as actually required.

In the context of the present disclosure, when a layer/element is referred to as being "on" another layer/element, it can be directly on the other layer/element or intervening layers/elements may be present. In addition, if a layer/element is "on" another layer/element in one orientation, then that layer/element may be "under" the other layer/element when the orientation is reversed.

The photolithography process is a precision microfabrication process. Specifically, a photoresist layer is formed on a substrate to be patterned. And then, irradiating the photoresist layer by light through the mask plate to cause the photoresist in the exposure area to generate chemical reaction. And dissolving and removing the reacted photoresist by a developing technology to copy the pattern on the mask plate to the photoresist layer to form a photoresist pattern. And finally, transferring the pattern to the substrate to be patterned by utilizing an etching technology under the mask action of the photoresist pattern.

In the photolithography process, when the photoresist layer is subjected to photolithography, the exposure light emitted toward the substrate inevitably undergoes a reflection phenomenon. The reflection phenomenon can cause the resolution of the formed photoresist pattern to be reduced, the imaging minimum resolution distance is increased, and finally, the pattern contour has defects and the pattern refinement is influenced. Based on this, in order to make the formed photoresist pattern more accurate, before forming the photoresist layer on the substrate, an anti-reflection layer may be formed on the surface of the substrate. The anti-reflection layer can inhibit the reflection phenomenon of the substrate, reduce the influence of the reflection phenomenon on the photoresist pattern and contribute to exposing the pattern with smaller size.

However, in practical applications, the wavelength of the light is a constant value when the type of the irradiation light is determined. At this time, the effect of suppressing the reflection phenomenon of the substrate is affected by the layer thickness and refractive index of the antireflection layer. It is very difficult to optimize the refractive index of the anti-reflection layer according to the wavelength of light. Referring to fig. 1, in the case where an anti-reflection layer having an inappropriate layer thickness and/or refractive index setting is formed, when a photoresist layer is patterned, a portion of reflected light still exists within the photoresist layer. Moreover, the reflected light causes the photoresist in the unexposed region to react and be removed, which causes the minimum resolution L distance of the image to be increased, resulting in lower precision of the photoresist pattern, and thus lower precision of the manufactured and formed semiconductor device.

In order to solve the above technical problem, an embodiment of the present invention provides an anti-reflection layer 101. Referring to fig. 2, the interior of the anti-reflection layer 101 contains a porous structure.

Specifically, the number of the holes in anti-reflection layer 101 may be set according to actual needs, and is not limited herein. As for the arrangement of the holes, a random arrangement is preferable. Therefore, in the process of performing photolithography on the photoresist layer 102, the porous structure is randomly arranged to reflect part of the light reflected by the substrate 100 for multiple times, so that the energy of the light is gradually lost, thereby suppressing the influence of the reflection phenomenon on the photoresist pattern.

Referring to fig. 2, the porous structure may be a regular porous structure, and the pores in the porous structure may be regular pores, for example: regular holes such as circular holes, elliptical holes, square holes, rectangular holes, etc., but not limited thereto. The porous structure can also be a special-shaped porous structure. The irregular holes included in the anisotropic porous structure may be irregular holes having shapes close to a circle, an ellipse, a square hole, a rectangular hole, etc., but are not limited thereto.

It should be noted that, in the process of performing photolithography on the photoresist layer 102, since the irregular porous structure in the anti-reflection layer 101 includes a regular porous structure and an irregular porous structure, and the multiple porous structures with various shapes can change the optical path of the reflected light to generate reflected light in more directions, so that multiple destructive interference occurs, thereby suppressing the influence of the reflected light reflected by the substrate 100 on the pattern of the photoresist layer 102. Meanwhile, the special-shaped hole structure can reflect part of the light rays reflected by the substrate 100 for multiple times, so that the energy of the light rays is gradually lost, and further the refinement of the photoresist pattern is ensured.

In one example, referring to FIG. 2, the refractive index of the anti-reflection layer 101 may be 1.5 to 2.5. Therefore, the antireflection layer 101 can fully exert antireflection capability, so that the antireflection effect of the antireflection layer 101 is optimal. Also, the refractive index of anti-reflective layer 101 may be controlled within a certain range by changing the ratio of the respective components in anti-reflective layer 101.

In one example, the porous structure is a plurality of micro-porous structures formed within anti-reflective layer 101. For example: the pore diameter of each pore in the microporous structure is

The diameter of each pore can be determined by, for example, ellipsometry porosimetry. In practical applications, the anti-reflective layer 101 having a plurality of micro-porous structures may be formed by a plasma enhanced chemical vapor deposition process.

The material of the anti-reflection layer 101 may be silicon oxynitride (SiON), silicon nitride (e.g., SiN and Si)₃N₄) Silicon oxide (SiO)₂) Titanium nitride (TiN), gallium nitride (GaN).

For example, when the substrate 100 is a silicon substrate, antireflection is formedDuring layer 101, Silane (SiH) may be used₄) And ammonia (NH)₃) As a gas source, preparing Si with passivation and antireflection effects by using a plasma enhanced chemical vapor deposition process₃N₄A film. Si formed at this time₃N₄The anti-reflection layer has compact structure, uniform film thickness, high hardness and high dielectric strength, can resist the corrosion of metal ions in the metal layer and has strong anti-reflection capability. In addition, Silane (SiH) may be varied₄) For ammonia (NH)₃) To obtain Si of different refractive index₃N₄The anti-reflection layer film can optimize the anti-reflection capability.

In another example, the porous structure may be a plurality of bubble structures formed within anti-reflective layer 101. The anti-reflection layer 101 including a plurality of bubble structures may be formed on the substrate 100 by a spin coating method. The anti-reflection layer 101 having a plurality of bubble structures is formed by a spin coating method, and the anti-reflection layer 101 having the bubble structures is formed by forming a viscous material having a sol structure by a sol-gel method to enhance the adhesion between the anti-reflection layer 101 and the substrate 100, and then spin coating the viscous material having the bubble on the substrate 100.

The embodiment of the invention also provides a patterning method. The procedure of the patterning processing method will be described below with reference to cross-sectional views of operations shown in fig. 3 to 6.

Referring to fig. 3, a substrate 100 is provided. The substrate 100 may be a substrate on which any film layer is not formed. For example: the substrate on which no film layer is formed may be a semiconductor substrate such as a silicon substrate, a germanium substrate, a silicon-on-insulator substrate, a germanium-on-insulator substrate, a silicon-germanium substrate, or a silicon-germanium-on-insulator substrate. In addition, the substrate 100 may be a substrate on which some film layers are formed. The film layer may be any film layer to be patterned.

Referring to fig. 4, an anti-reflection layer 101 shown in fig. 2 is formed on a substrate 100. The anti-reflection layer 101 has a porous structure inside.

In particular, in one example, a plasma enhanced chemical vapor deposition process can be used to form a porous structure containingAnti-reflective layer 101. Below with Si₃N₄The anti-reflection layer 101 formed by material manufacturing is taken as an example, and a specific manufacturing process of the anti-reflection layer 101 having a porous structure is described:

a sample on which the substrate 100 is placed on a cathode of glow discharge under pressure and temperature, and the sample is heated to a predetermined temperature by the glow discharge (or another heating element). Then introducing Silane (SiH) as active gas source₄) And ammonia (NH)₃) Before or simultaneously adding a solvent (such as alcohol, a high-molecular organic solvent and the like) or a polymer precursor solution. Under vacuum and high temperature conditions, the added solution is volatile and can be gasified or decomposed in molecular form. Based on this, the introduced gas and the molecules of the additive solution undergo a series of chemical reactions and plasma reactions to form Si with porous structure and anti-reflection effect on the surface of the substrate 100₃N₄An anti-reflective layer film. The deposition temperature is higher in the common silicon nitride deposition technique>600 deg.C), and the temperature for depositing the silicon nitride by the plasma enhanced chemical vapor deposition method is lower (<350 deg.c), so that the silicon nitride anti-reflecting layer can be formed at a relatively low temperature by using a plasma enhanced chemical vapor deposition method.

In another example, spin coating may be used to form anti-reflection layer 101 having a porous structure on substrate 100. Specifically, the spin coating process generally uses a spin coater (also called spin coater, etc.), and the working principle thereof is a process of using centrifugal force generated during high-speed rotation to cause the glue solution on the substrate 100 to diffuse outward from the center to form a uniform film layer. For example, a spin coating liquid is dropped onto the surface of the substrate 100 by a syringe, and the substrate 100 is driven to rotate so that the liquid is uniformly distributed on the substrate 100. At this time, a viscous material sol having fine bubbles inside is formed by a sol-gel method. The viscous material sol is then spin-coated on the substrate 100 to form a viscous material layer having bubbles. Finally, the adhesive material layer having the air bubbles is subjected to heat treatment to remove the liquid remaining in the anti-reflection layer 101, thereby forming the anti-reflection layer 101 having the air bubbles.

Of course, the anti-reflection layer 101 having a porous structure may be formed by other methods than the above two methods.

Referring to fig. 5 and 6, a photoresist pattern is formed on the anti-reflection layer 101.

In practical applications, referring to fig. 5 and 6, photoresist layer 102 may be formed on anti-reflective layer 101, and the solvent in photoresist layer 102 is removed by pre-baking, so that the adhesion between photoresist layer 102 and anti-reflective layer 101 is relatively high. Next, the photoresist layer 102 is exposed to an exposure light under the mask of the mask plate 103, so that the pattern is transferred to the photoresist layer 102, thereby forming a desired photoresist pattern on the antireflective layer 101.

It is noted that, referring to fig. 6, in the patterning method provided in the embodiment of the invention, the anti-reflective layer 101 includes a porous structure therein. Each pore structure can be considered an air film. Further, the refractive index of air is smaller than that of the antireflection layer material, so that the refractive index of the entire antireflection layer 101 including a porous structure is lowered. Based on this, even if light is emitted to the substrate 100 through the anti-reflection layer 101, the substrate 100 reflects the light. When the reflected light is refracted to the air by the anti-reflection layer 101 having a porous structure, the exit angle of the reflected light is reduced because the refractive index of the whole anti-reflection layer 101 is relatively low. Therefore, the light-resolvable size refracted by the anti-reflection layer 101 having the porous structure is relatively small with respect to the critical size of the photoresist pattern, so that the minimum resolution distance L in photolithography is reduced. At this time, although there is still a light reflection problem, the degree of influence of the refracted light on the photoresist pattern has been reduced, pattern profile defects due to a reflection phenomenon are improved, thereby securing photoresist pattern fineness, increasing yield of semiconductor devices, and increasing device integration by implementing a fine pattern mode.

In the above description, the technical details of patterning, etching, and the like of each layer are not described in detail. It will be appreciated by those skilled in the art that layers, regions, etc. of the desired shape may be formed by various technical means. In addition, in order to form the same structure, those skilled in the art can also design a method which is not exactly the same as the method described above. Further, although the embodiments are described separately above, this does not mean that the measures in the respective embodiments cannot be used advantageously in combination.

The embodiments of the present disclosure have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the present disclosure, and such alternatives and modifications are intended to be within the scope of the present disclosure.

Claims (12)

1. An anti-reflective layer, wherein said anti-reflective layer comprises a porous structure.

2. Antireflection layer according to claim 1, characterized in that said porous structure is a profiled porous structure.

3. Antireflection layer according to claim 1, characterized in that each hole of the porous structure has a pore diameter of

And/or the presence of a gas in the gas,

the refractive index of the anti-reflection layer is 1.5-2.5.

4. An anti-reflective layer as recited in claim 1, wherein said porous structure is a plurality of bubble structures formed within said anti-reflective layer; or the like, or a combination thereof,

the porous structure is a plurality of microporous structures formed within the antireflective layer.

5. Anti-reflection layer according to any one of claims 1 to 4, wherein the material of the anti-reflection layer is one or more of silicon oxynitride, silicon nitride, silicon oxide, titanium nitride and gallium nitride.

6. A patterning method, comprising:

providing a substrate;

forming an anti-reflection layer on the substrate; the anti-reflection layer contains a porous structure;

and forming a photoresist pattern on the anti-reflection layer.

7. The patterning method according to claim 6, wherein the forming an anti-reflection layer on the substrate includes:

and forming the anti-reflection layer on the substrate by adopting a plasma enhanced chemical vapor deposition process.

8. The patterning method of claim 7, wherein the forming the anti-reflective layer on the substrate using a plasma enhanced chemical vapor deposition process comprises:

in the plasma enhanced chemical vapor deposition process, a solvent or a polymer precursor solution is added to form the anti-reflection layer with a porous structure inside on the substrate.

9. The patterning method according to claim 6, wherein the forming an anti-reflection layer on the substrate includes:

and forming the anti-reflection layer with a porous structure inside on the substrate by adopting a spin coating method.

10. The patterning method according to claim 9, wherein the forming of the anti-reflection layer having a porous structure therein on the substrate by using a spin coating method includes:

spin-coating a viscous material layer with air bubbles on the substrate;

and carrying out heat treatment on the viscous material layer, and forming an anti-reflection layer with air bubbles inside on the substrate.

11. The patterning method according to claim 10, wherein the forming of the antireflection layer having a porous structure therein on the substrate by using a spin coating method further comprises:

and before the viscous material layer with the air bubbles is coated on the substrate in a spin mode, forming viscous material sol by a sol-gel method.

12. The patterning method of claim 6, wherein forming a photoresist pattern on the anti-reflection layer comprises:

forming a photoresist layer covering the anti-reflection layer;

and exposing and developing the photoresist layer to form a photoresist pattern on the anti-reflection layer.

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