CN109206605B

CN109206605B - Block copolymer for directed self-assembly and directed self-assembly method using the same

Info

Publication number: CN109206605B
Application number: CN201811008058.5A
Authority: CN
Inventors: 傅志伟; 吴信; 王宝清; 戴俊燕; 毛国平; 冉瑞成; 张宝林; 韦亚一
Original assignee: Jiangsu Hantuo Optics Material Co ltd
Current assignee: Xuzhou B&c Chemical Co ltd
Priority date: 2018-08-31
Filing date: 2018-08-31
Publication date: 2020-11-24
Anticipated expiration: 2038-08-31
Also published as: CN109206605A

Abstract

The present application relates to a block copolymer for directed self-assembly having a structure represented by the following general formula (I):

wherein A is an etching-resistant homopolymer chain segment rich in C element or Si element; b is an easily-etched homopolymer chain segment rich in O element; and X-H is a functional linking segment containing an active H. The application also relates to a directed self-assembly method using the block copolymer and a directed self-assembly structure with a vertical phase separation structure obtained by the method. The application also relates to the use of the above block copolymers in the processing of electronic components. The block copolymer comprises two blocks of polar active H, and in the phase splitting process of the block copolymer, the active H is anchored with Si-OH on the surface of a silicon wafer through hydrogen bond action, so that the surface energy of the difference of two ends of the block copolymer is overcome, and the vertical phase splitting is promoted under the condition without a neutral layer.

Description

Block copolymer for directed self-assembly and directed self-assembly method using the same

Technical Field

The present application relates to the field of self-assembly and lithography. In particular, the present application relates to a block copolymer for directed self-assembly and a directed self-assembly method using the same.

Background

The ability to fabricate smaller devices is determined by the smaller feature, reliable resolution lithography. The ability to achieve finer resolution due to the nature of the optical properties is somewhat limited by the optical wavelength used to create the optical pattern. Therefore, in the photolithography process, light sources having shorter and shorter wavelengths tend to be used. This trend has now shifted from so-called I-Line radiation (365nm) to the use of KrF radiation (248nm), ArF (193nm) and even EUV (13.5 nm). However, with the requirements of resolution, density, high integration, and other performances, the integrated circuit is under the 10nm node and is under intense research. Under the radiation light sources of I-Line (365nm), KrF (248nm) and ArF (193nm), the application on a 7nm node and a 5nm node is difficult due to the limitation of wavelength diffraction, and even the current mainstream 193 immersion lithography can not be realized below a 10nm node at one time.

EUV and DSA are expected to be applied to the next generation of photoresists. Extreme ultraviolet EUV (13.5nm) can significantly improve resolution due to short wavelength, but rapid development is limited due to challenges in transmission, resist sensitivity and defectivity. DSA uses as a starting material a block copolymer of two chemically different monomers polymerized, phase-separated under thermal annealing to form a nanoscale pattern, and due to covalent bonds between the two blocks, phase separation occurs on a macromolecular length scale, about 5 to 50nm full pitch, which is exactly approximately equal to the target pitch size of the upcoming semiconductor node. And inducing the pattern into a regularized nanowire or nanopore array by a certain method, thereby forming an etching template to manufacture the nanostructure. DSA has the advantages of low cost, high resolution and high yield compared to other technologies because it does not need a light source and a mask, and is getting attention, and many international companies including Intel, IBM and IMEC and research institutions have made corresponding research on this technology.

It is well known that block copolymers are used for directed self-assembly due to their microphase separation properties; meanwhile, the structure comprises an etching resistant section rich in C (or Si, Ti and the like) and a high-selectivity plasma etching section rich in O. According to the block copolymer theory, the microphase separation capability structurally depends on Flory Huggins interaction parameter (chi) and polymerization degree N, and only when the chi N is N>10.5, microphase separation can occur. However line width

So as to reduce L₀It is necessary to decrease the degree of polymerization N, but when the value of χ is small after decreasing N, it is not possible to satisfy the requirement of χ N>10.5 microphase separation requirements. Therefore, research currently applied below the 10nm node is directed to increasing the χ value of BCP to reduce L₀。

Since the poly (styrene-b-methyl methacrylate) has a small χ value between the PS end and the PMMA end, the minimum Pitch (Pitch) of the layer is about 28nm, and it is difficult to achieve an application of L/S below the 10nm node after selective etching, it is desirable to design a high χ value block.

However, the high χ value corresponds to the high incompatibility of the two blocks and the difference in surface energy, so that in practical application, the silicon wafer must be treated with a neutral layer to eliminate the difference in surface energy of the block copolymers, so that the silicon wafer is selectively arranged and cannot be vertically phase-separated. To a large extent, the difference in surface energy in the films of block copolymers determines the orientation of the BCP. A method of orienting BCP vertically, i.e. overcoming the effect of surface energy, with a neutral layer and top-coat (top-coat) has been developed. Two interfaces in a BCP system, namely the air/BCP and BCP/substrate interfaces, if one block of the BCP has a preference for air or substrate, neither BCP can form a vertical orientation, and only if there is no preference at both interfaces, the block copolymer will microphase separate to vertically phase separate. So in DSA, it is well known that BCP is vertically phase-separated at the neutral layer.

Domestic patents CN 103843112, CN 105742236, CN 106125504, etc. have studied many different types of high χ value blocks, including styrene and 4- (tert-butyldimethylsiloxane) oxystyrene (PS-b-PSSi), styrene and dimethylsiloxane (PS-b-PDMS), styrene and vinylpyrrolidone (PS-b-PVP), and styrene and polyethylene oxide (PS-b-PEO), etc., although the system exhibits good phase separation capability, it needs to adopt a neutral layer to form vertical phase separation well.

U.S. Pat. No. 3,416,4557 introduces an alkyl side chain containing F into the block copolymer PS-b-PC, and due to the low surface energy of the F element, the block copolymer is dragged to form a similar inverted "V" state due to the kinetic shift of the low surface energy side chain toward the Air/BCP interface during phase separation, so that the two phases are better vertically separated. However, due to the incompatibility and the difference in surface energy of the blocks themselves, the blocks cannot be vertically separated under the condition of no neutral layer, and the processing steps and the cost are increased.

For this reason, there is a strong need in the art to develop a block copolymer for directed self-assembly that can be phase-separated vertically without a neutral layer.

Disclosure of Invention

The present application relates to novel Block Copolymers (BCPs) comprising two blocks and a linking group therebetween, wherein the linking group comprises at least one reactive H group capable of forming a hydrogen bond. The block copolymer can generate a vertical phase separation structure (such as a layered structure, a columnar structure and the like) through Self-assembly (SA) or Directed Self-assembly (DSA), and can be applied to processing of electronic components.

The application designs a novel diblock containing polar active H, in the phase splitting process of a block copolymer, the active H is anchored with Si-OH on the surface of a silicon wafer through hydrogen bond action, the surface energy of the difference of two ends of the block copolymer is overcome, the vertical phase splitting is promoted under the condition without a neutral layer, and the application in the aspect of directional self-assembly is enhanced, wherein the specific schematic diagram is shown in figure 1.

In order to achieve the above object, the present application provides the following technical solutions.

In a first aspect, the present application provides a block copolymer for directed self-assembly having a structure represented by the following general formula (I):

wherein A is an etching-resistant homopolymer chain segment rich in C element or Si element; b is an easily-etched homopolymer chain segment rich in O element; and X-H is a functional linking segment containing an active H.

In one embodiment of the first aspect, a is homopolymerized, but is not limited to, a monomer having a structure represented by the following general formula (II):

wherein the groups R1, R2, R3, R4 and R5 are each independently selected from: a hydrogen atom, a methyl group, a trimethylsilyl group or a pentamethyldisilyl group.

In one embodiment of the first aspect, B is homopolymerized, but is not limited to, a monomer having the structure:

in one embodiment of the first aspect, X-H is polymerized from, but is not limited to, monomers having the structure of formula (III):

wherein R is₂To represent

And m and n are each independently integers greater than 0 and less than 5.

In one embodiment of the first aspect, the block copolymer used for directed self-assembly includes, but is not limited to, the following structures:

wherein the groups R1, R2, R3, R4 and R5 are each independently selected from: a hydrogen atom, a methyl group, a trimethylsilyl group, or a pentamethyldisilyl group;

wherein m and n are each independently integers between greater than 0 and less than 100;

wherein x is an integer greater than 0 and less than 5.

In one embodiment of the first aspect, the block copolymer does not require the use of a neutral layer for directed self-assembly.

In a second aspect, the present application provides a method of directed self-assembly using a block copolymer for directed self-assembly as described in the first aspect.

In one embodiment of the second aspect, the method does not use a neutral layer.

In a third aspect, the present application provides a directed self-assembled structure formed by the method as described in the second aspect, comprising a vertical phase-splitting structure.

In a fourth aspect, the present application provides the use of a block copolymer as described in the first aspect for directed self-assembly in the processing of electronic components.

Compared with the prior art, the block copolymer has the beneficial effects that the block copolymer contains a diblock with polar active H, in the phase splitting process of the block copolymer, the active H is anchored with Si-OH on the surface of a silicon wafer through hydrogen bond action, the surface energy of the difference of two ends of the block copolymer is overcome, and the vertical phase splitting is promoted under the condition without a neutral layer.

Drawings

FIG. 1 schematically shows a schematic diagram of an active H-containing block copolymer according to the present application without neutral lamellar phase separation.

Fig. 2 schematically shows an atomic force microscope picture of a directed self-assembled structure according to the present application.

Fig. 3 schematically shows an atomic force microscope picture of the directed self-assembled structure of comparative example 1 according to the effect.

Fig. 4 schematically shows an atomic force microscope picture of the directed self-assembled structure of comparative example 2 according to the effect.

Detailed Description

Unless otherwise indicated, implied from the context, or customary in the art, all parts and percentages herein are by weight and the testing and characterization methods used are synchronized with the filing date of the present application. Where applicable, the contents of any patent, patent application, or publication referred to in this application are incorporated herein by reference in their entirety and their equivalent family patents are also incorporated by reference, especially as they disclose definitions relating to synthetic techniques, products and process designs, polymers, comonomers, initiators or catalysts, and the like, in the art. To the extent that a definition of a particular term disclosed in the prior art is inconsistent with any definitions provided herein, the definition of the term provided herein controls.

The numerical ranges in this application are approximations, and thus may include values outside of the ranges unless otherwise specified. A numerical range includes all numbers from the lower value to the upper value, in increments of 1 unit, provided that there is a separation of at least 2 units between any lower value and any higher value. For example, if a compositional, physical, or other property (e.g., molecular weight, melt index, etc.) is recited as 100 to 1000, it is intended that all individual values, e.g., 100, 101,102, etc., and all subranges, e.g., 100 to 166,155 to 170,198 to 200, etc., are explicitly recited. For ranges containing a numerical value less than 1 or containing a fraction greater than 1 (e.g., 1.1, 1.5, etc.), then 1 unit is considered appropriate to be 0.0001, 0.001, 0.01, or 0.1. For ranges containing single digit numbers less than 10 (e.g., 1 to 5), 1 unit is typically considered 0.1. these are merely specific examples of what is intended to be expressed and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application. The numerical ranges within this application provide, among other things, the amount of each comonomer in the acrylate copolymer, the amount of each component in the photoresist composition, the temperature at which the acrylate is synthesized, and the various characteristics and properties of these components.

When used with respect to chemical compounds, the singular includes all isomeric forms and vice versa (e.g., "hexane" includes all isomers of hexane, individually or collectively) unless expressly specified otherwise. In addition, unless explicitly stated otherwise, the use of the terms "a", "an" or "the" are intended to include the plural forms thereof.

The terms "comprising," "including," "having," and derivatives thereof do not exclude the presence of any other component, step or procedure, and are not intended to exclude the presence of other elements, steps or procedures not expressly disclosed herein. To the extent that any doubt is eliminated, all compositions herein containing, including, or having the term "comprise" may contain any additional additive, adjuvant, or compound, unless expressly stated otherwise. Rather, the term "consisting essentially of … …" excludes any other components, steps or processes from the scope of any of the terms hereinafter recited, except those necessary for performance. The term "consisting of … …" does not include any components, steps or processes not specifically described or listed. Unless explicitly stated otherwise, the term "or" refers to the listed individual members or any combination thereof.

Definition of terms

As used herein, the term "composition" means a mixture or blend of two or more components.

As used herein, the terms "blend," "polymer blend," and the like refer to a mixture of two or more polymers, as well as mixtures of polymers with various additives. Such blends may or may not be miscible. Such blends may or may not be phase separated. Such blends may or may not contain one or more domain configurations, such as those determined by transmission electron microscopy, light scattering, X-ray scattering, and any other method known in the art.

As used herein, the term "polymer" is a macromolecular compound prepared by reaction (i.e., polymerization) between monomers of the same or different types. The polymers may include homopolymers and copolymers.

As used herein, the term "homopolymer" refers to a macromolecular compound prepared by reaction between monomers of the same type.

As used herein, the term "copolymer" refers to a macromolecular compound prepared by reaction between at least two different types of comonomers. The term "copolymer" in the present application may include a block copolymer, a random copolymer, a graft copolymer, a star copolymer, or the like, unless otherwise specified.

Examples

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The reagents and raw materials used are commercially available unless otherwise specified.

The block compound containing active H is prepared through controllable free radical polymerization ATRP technology, initiating polymerization of styrene or styrene derivative with ATRP initiator, modifying to introduce active H radical and active radical hydroxyl-OH, and ring-opening polymerization (ROP) to synthesize the block copolymer with powerful microphase separation and excellent etching selectivity.

Synthesis example 1

Synthesis step 1: synthesis of macroinitiator PS-Br

The synthetic route of the step is as follows:

ATRP is used to synthesize polymers containing halogen end groups that can be reactivated in the presence of a metal/ligand complex to form free radicals. Styrene (20g, 192.03mmol) and anisole (5ml) were mixed and stirred, after evacuation three times, argon protection was performed, then cuprous bromide (0.55g, 3.83mmol), N, N, N' -pentamethyldiethylenetriamine (0.66g, 3.81mmol) were added, after evacuation three times, argon protection was performed, stirring was performed for about 20min, initiator (1-bromoethyl) benzene (0.70g, 3.78mmol) was added, argon protection was performed while setting the temperature at 105 ℃, heating was turned on, after 1.5h, the reaction vessel was placed in dry ice and stirred and cooled. The reaction solution was precipitated in methanol, dried by vacuum-pumping at 40 ℃ and then dissolved in Tetrahydrofuran (THF) to prepare a 20 wt% solution, and this polymer was further precipitated in methanol and repeated three times, and then dried by vacuum-pumping at 40 ℃. Mn (gpc) 3900, Mw 4800, PDI 1.22.

And 2, synthesis step: macromolecular initiator PS-NH- (CH) containing active H₂)₂-synthesis of OH¹(*¹: reference documents: synthesis of polymers with hydroxyl end groups by atom transfer polymerization)

The synthetic route of the step is as follows:

polystyrene with bromine end groups (Mn 3900, Mw/Mn 1.22) was reacted with 10 equivalents of ethanolamine in the presence of triethylamine at room temperature for 48 hours. The product was precipitated in methanol, dried under vacuum at 40 ℃ and dissolved in THF to prepare a 20 wt% solution, which was then precipitated in methanol three times.

And 3, synthesis step: synthesis of block copolymer PS-b-PC containing active H

The synthetic route of the step is as follows:

10g of PS-OH containing active H was added to a four-necked flask followed by trimethylene carbonate (TMC, 12g, 117.43mmol) and dichloromethane (DCM, 10ml), the solution was stirred until the sample was completely dissolved, 1, 8-diazabicycloundecen-7-ene (DBU, 0.2g, 1.32mmol) was added and the solution was reacted at 30 ℃ for 7H.

After 7 hours of reaction, the system was brought to ambient temperature, DCM (10ml), acetyl chloride (2g, 25.48mmol) and triethylamine (2.5g, 25.64mmol) were added and the reaction was continued for two hours at ambient temperature. The polymer solution was repeatedly settled in methanol 3 times, after which a sample according to Synthesis example 1 was measured by a fractionation treatment, and the results of characterization thereof are shown in Table 1.

TABLE 1 Property parameters of active H Block copolymers

Synthesis comparative example 1

This comparative example 1 relates to the synthesis of an active H-free block copolymer PS-b-PC.

Taking a sample classified in the step 3 of the synthetic example 1, adding 10 times of equivalent weight of n-butyl glycidyl ether and a certain amount of THF solution, placing the sample in an oil bath at 50 ℃, stirring the mixture overnight, preparing a 20% THF solution, settling the solution with methanol, repeating the process for 3 times, and then placing the solution in a vacuum oven at 50 ℃ for drying.

Effects of the embodiment

Effect example 1

The sample according to synthesis example 1 was dissolved in Propylene Glycol Methyl Ether Acetate (PGMEA) solution, spin-coated on a clean silicon wafer surface, and then annealed at 165 deg.c to obtain an oriented self-assembled structure according to effect example 1. The morphology was observed by Atomic Force Microscopy (AFM) and the results are shown in FIG. 2. Referring to FIG. 2, BCP type contains active H, i.e., a sample prepared in step 3 of Synthesis example 1 was spin-coated directly on a silicon wafer without a neutral layer, and thermal annealing was performed to obtain an electron microscope image. The electron microscope result shows that a long-range ordered vertical phase-splitting structure is formed. The active H block copolymer can be anchored with the silicon surface on the surface of the silicon substrate through hydrogen bonds, so that the selective wetting of BCP on the surface of the substrate due to different surface energies is overcome, and the vertical phase separation is promoted under the condition without a neutral layer.

See table 2 for specific process parameters and morphology characteristics.

Effect comparative example 1

The sample according to synthesis comparative example 1 was dissolved in Propylene Glycol Methyl Ether Acetate (PGMEA) solution, spin-coated on a clean silicon wafer surface, and then annealed at 165 ℃, to obtain the oriented self-assembled structure according to effect comparative example 1. The morphology was observed by Atomic Force Microscopy (AFM) and the picture obtained is shown in FIG. 3. Referring to fig. 3, BCP type does not contain active H, i.e. the product of step 3 of synthesis example 1 is reacted with n-butyl glycidyl ether to consume the active H, and then spin-coated on a silicon wafer without a neutral layer, and thermally annealed and then subjected to electron microscope imaging. The electron microscope result shows that after the active H is eliminated, vertical phase splitting cannot be formed under the condition without a neutral layer due to the difference of surface energies of two ends of BCP.

See table 2 for specific process parameters and morphology characteristics.

Comparative Effect example 2

The surface of the silicon chip is treated by Hexamethyldisilazane (HMDS), the HMDS is coated on the surface of the silicon chip in a spinning mode, and Si-OH on the surface of the silicon chip is eliminated after baking and crosslinking. Then, the sample according to synthesis example 1 was dissolved in Propylene Glycol Methyl Ether Acetate (PGMEA) solution, and then spin-coated on the HDMS-treated silicon wafer surface, followed by annealing at 165 ℃, to obtain the oriented self-assembled structure according to effect comparative example 2. The morphology was observed by Atomic Force Microscopy (AFM) and the picture obtained is shown in FIG. 4. Referring to fig. 4, the BCP type contains active H, but the surface of the silicon wafer is treated with HMDS, HMDS is spin-coated on the surface of the silicon wafer, Si — OH on the surface of the silicon wafer is eliminated after baking and crosslinking, then a sample containing active H is spin-coated in step 3, and an electron microscope image is obtained after thermal annealing. The electron microscope result shows that no obvious vertical phase separation structure appears. Si-OH on the surface of the silicon wafer is eliminated, so that BCP containing active H cannot be anchored with a base material by a hydrogen bond to overcome the influence of surface energy, and thus, vertical phase splitting cannot be formed.

See table 2 for specific process parameters and morphology characteristics.

From the self-assembly information shown in Table 2 and FIGS. 2 to 4, it can be seen that the block copolymer containing active H of example 1 can be anchored to the silicon surface at the surface of the silicon substrate by hydrogen bonding, promoting vertical phase separation without a neutral layer. Effect comparative example 1 the vertical phase splitting effect disappears under the condition that the active H is consumed. Effect comparative example 2 the silicon wafer treated by HDMS eliminated Si-OH on the surface of the silicon wafer and the vertical phase splitting effect disappeared. In conclusion, the influence of active H on the vertical phase splitting of the neutral-free layer is verified.

TABLE 2 active H Block copolymer self-Assembly

The embodiments described above are intended to facilitate the understanding and appreciation of the application by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present application is not limited to the embodiments herein, and those skilled in the art who have the benefit of this disclosure will appreciate that many modifications and variations are possible within the scope of the present application without departing from the scope and spirit of the present application.

Claims

1. A block copolymer for directed self assembly, characterized in that it has the following structure:

wherein x is an integer between greater than 0 and less than 5;

the block copolymer does not need to use a neutral layer when performing directed self-assembly.

2. A method for directed self-assembly using the block copolymer for directed self-assembly according to claim 1, which comprises coating the block copolymer for directed self-assembly on a hydroxyl group-containing substrate and then annealing at a temperature of 200 ℃ or less to obtain a directed self-assembly structure.

3. The method of claim 2, wherein the method does not use a neutral layer.

4. A directionally self-assembled structure formed by the method of claim 2, comprising a vertical phase-splitting structure.

5. Use of a block copolymer according to claim 1 for directed self-assembly in the processing of electronic components.