JP7339134B2 - Pattern formation method and semiconductor manufacturing method including the method - Google Patents

Description

The present invention relates to a pattern forming method for forming a pattern on a thin precision electronic substrate such as a semiconductor wafer (hereinafter simply referred to as a "substrate") using an induced self-assembly technique, and semiconductor manufacturing including the method. Regarding the method.

Conventionally, photolithography has been used as a general technique for forming patterns on substrates such as semiconductor wafers. Photolithography involves coating a substrate with a resist, which is a photosensitive material, and exposing the resist using a mask with the shape of a circuit diagram drawn on it. It is a technique for forming the pattern shown in the figure.

In order to increase the degree of integration of semiconductor devices, miniaturization of patterns is necessary, and miniaturization of patterns by photolithography has been achieved by using a light source with a shorter wavelength during exposure processing. At present, for example, an ArF excimer laser (wavelength: 193 nm) is mainly used as a light source for exposure processing, but even if such a short wavelength light source is used, the limit of pattern miniaturization by photolithography is about 45 nm. It is believed that there are

EUV (extreme ultraviolet) exposure, direct writing with an electron beam, and the like have been proposed as photolithographic techniques capable of forming patterns finer than 45 nm. However, EUV exposure is extremely expensive, and direct writing with an electron beam requires a long time to form a pattern.

Therefore, Directed Self-Assembly (DSA) is being researched as a technique for achieving pattern miniaturization at low cost and in a relatively short period of time (for example, Patent Documents 1 and 2). Induced self-assembly technology utilizes the properties of specific block copolymers that self-assemble into spherical, plate-like, columnar or layered shapes.

JP 2014-22570 A Japanese Patent Publication No. 2016-518701

However, the conventional guided self-assembly technique has a problem that a pattern with sufficient etching resistance cannot be obtained and a desired etching selectivity cannot be obtained.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pattern forming technique capable of forming a pattern having excellent etching resistance.

In order to solve the above-mentioned problems, the invention of claim 1 provides a pattern forming method for forming a pattern on a substrate, in which a resin film made of an induced self-organizing material containing a polymer containing oxygen atoms is coated on the substrate. and a first heating step of heating the substrate to separate the resin film into a first phase containing the oxygen atom-containing polymer and a second phase not containing the oxygen atom-containing polymer. and an impregnation step of impregnating the first phase with a metal in a gas containing metal atoms, and a developing step of removing the second phase, wherein the impregnation step is performed in the gas containing the metal atoms. and a third heating step of heating the resin film to a predetermined temperature or higher for one second or less after the impregnation step.

According to a second aspect of the invention, in the pattern forming method according to the first aspect of the invention, the resin film is irradiated with flash light or laser light in the third heating step.

A third aspect of the invention is characterized in that, in the pattern forming method according to the first or second aspect of the invention, the second phase is removed by dry etching in the developing step.

The invention of claim 4 is the pattern forming method according to the invention of claim 1 or claim 2, wherein in the developing step, a developer is supplied to the resin film to dissolve and remove the second phase. Characterized by

The invention of claim 5 is characterized in that, in the pattern forming method according to the invention of claim 4 , the developing step is performed before the impregnation step.

The invention of claim 6 is the pattern forming method according to any one of claims 1 to 5 , wherein the oxygen atom content of the polymer is 20% by mass or more with respect to the total mass of the polymer. characterized by being

A seventh aspect of the invention is the pattern forming method according to the sixth aspect of the invention, wherein the polymer is hemicellulose.

According to an eighth aspect of the invention, there is provided a method for manufacturing a semiconductor, comprising the pattern forming method according to any one of the first to seventh aspects, wherein the substrate is etched using the resin film as a mask. and

According to the inventions of claims 1 to 8 , a resin film made of an induced self-assembly material is phased into a first phase containing a polymer containing oxygen atoms and a second phase not containing a polymer containing oxygen atoms. Since the first phase is separated and the metal is impregnated into the first phase in the gas containing metal atoms, the first phase is selectively hardened and a pattern having excellent etching resistance can be formed. Further, after the impregnation step, the resin film is heated to a predetermined temperature or higher for one second or less, so that the metal diffuses in the first phase of the resin film and the entire first phase can be cured.

4 is a flow chart showing a processing procedure of a pattern forming method according to the present invention; It is a figure which shows the cross-sectional structure of the semiconductor wafer used as processing object. It is a figure which shows the cross-sectional structure of the semiconductor wafer in which the guide pattern was formed. It is a figure which shows the cross-section of the semiconductor wafer in which the resin film of the induction self-assembly material was formed into a film. It is a figure which shows the cross-section of the semiconductor wafer which phase-separated in the resin film. FIG. 2 shows a cross-sectional structure of a semiconductor wafer in which the surface of the first phase containing hemicellulose is impregnated with aluminum; FIG. 4 is a diagram schematically showing a cross-sectional structure of a semiconductor wafer in which aluminum has diffused in the first phase of the resin film; FIG. 4 is a diagram showing a cross-sectional structure of a semiconductor wafer from which the second phase of the resin film has been removed by development; FIG. 4 is a diagram showing a cross-sectional structure of a semiconductor wafer in which a pattern is formed on an underlying film; FIG. 2 is a diagram showing an example of the structure of a polymer contained in an induced self-assembly material; FIG. 2 is a diagram showing an example of the structure of a polymer contained in an induced self-assembly material; FIG. 2 is a diagram showing an example of the structure of a polymer contained in an induced self-assembly material;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As used herein, hemicellulose means a resin containing units derived from sugar derivatives such as xylose, which constitutes hemicellulose. The sugar derivative can be extracted from plants, wood, etc., and can be produced, for example, by the method described in International Publication No. 2019/012716. In addition, in FIG. 1 and subsequent figures, the dimensions and numbers of each part are exaggerated or simplified as necessary for easy understanding.

FIG. 1 is a flow chart showing the processing procedure of the pattern forming method according to the present invention. In the embodiment of the present invention, a silicon semiconductor wafer W is used as a processing object, and the pattern forming method according to the present invention can be implemented as a semiconductor manufacturing method and is included in the semiconductor manufacturing method. Prior to the process shown in FIG. 1, a lower layer film is formed on the surface of the semiconductor wafer W to be processed. FIG. 2 is a diagram showing a cross-sectional structure of a semiconductor wafer W to be processed. A lower layer film 20 is formed on a substrate 10 of silicon (Si). The underlayer film 20 is a multilayer film in which, for example, thin films of silicon dioxide (SiO ₂ ) and thin films of silicon nitride (SiN) are alternately laminated. The underlayer film 20 is deposited on the substrate 10 by, for example, CVD. The underlayer film 20 may be amorphous silicon. A 3D-NAND flash memory, for example, is manufactured by forming deep holes in the lower layer film 20 by etching.

A guide pattern is formed on a semiconductor wafer W having a structure as shown in FIG. 2 (step S1). FIG. 3 is a diagram showing a cross-sectional structure of a semiconductor wafer W on which guide patterns 30 are formed. The guide pattern 30 is formed by a known photolithographic technique. Specifically, a resist is applied onto the lower layer film 20, and exposure processing is performed on the resist using a mask on which the shape of the guide pattern 30 is drawn. Thereafter, excess resist is removed by development to form the guide pattern 30 .

A resin film 40 of an induced self-assembly material is formed on the semiconductor wafer W on which the guide pattern 30 as shown in FIG. 3 is formed (step S2). FIG. 4 is a diagram showing a cross-sectional structure of a semiconductor wafer W on which a resin film 40 of an induced self-assembly material is formed. The resin film 40 of the induced self-assembly material is formed by applying a known spin coating method. Specifically, while the semiconductor wafer W as shown in FIG. The processing liquid is spread over the upper surface of the semiconductor wafer W by centrifugal force. As a result, as shown in FIG. 4, a coating film (resin film 40) made of the induced self-assembly material is formed on the area of the lower layer film 20 where the guide pattern 30 is not formed.

Here, the induced self-assembly material includes a block copolymer composed of multiple types of polymers. A plurality of types of polymers constituting the block copolymer are preferably incompatible with each other. In this embodiment, the semiconductor wafer W is discharged with a treatment liquid composed of an induced self-assembly material containing a block copolymer composed of two types of polymers. Further, in the present embodiment, the semiconductor wafer W is discharged with a treatment liquid composed of an induced self-assembly material containing a block copolymer containing hemicellulose. Therefore, the resin film 40 formed along the guide pattern 30 contains hemicellulose.

Next, the semiconductor wafer W on which the resin film 40 containing hemicellulose is formed is heated. The semiconductor wafer W may be heated by irradiating the semiconductor wafer W with light from a lamp, or by placing the semiconductor wafer W on a hot plate. Microphase separation occurs in the resin film 40 by heating the semiconductor wafer W on which the resin film 40 is formed as shown in FIG. 4 (step S3). FIG. 5 is a diagram showing a cross-sectional structure of a semiconductor wafer W in which phase separation has occurred in the resin film 40. As shown in FIG. The resin film 40 is made of an induced self-assembly material containing a block copolymer composed of two kinds of polymers. When the resin film 40 containing two types of polymers is heated to a predetermined temperature, the two types of polymers are phase-separated to form a first phase P1 composed of one polymer and a second phase P1 composed of the other polymer. Two phases P2 are formed. In the example of FIG. 5, linear first phases P1 and linear second phases P2 are alternately patterned along the guide pattern 30 .

In the present embodiment, when the resin film 40 undergoes phase separation, the first phase P1 contains hemicellulose and the second phase P2 no longer contains hemicellulose. That is, the resin film 40 is phase-separated into the first phase P1 containing hemicellulose and the second phase P2 not containing hemicellulose. The first phase P1 containing hemicellulose is hydrophilic and the second phase P2 without hemicellulose is hydrophobic.

After the resin film 40 is phase-separated and the pattern is formed, the resin film 40 is impregnated with a metal (step S4). This process proceeds by heating the semiconductor wafer W on which the resin film 40 is phase-separated to form a pattern in an atmospheric gas containing trimethylaluminum (TMA). The heating temperature of the semiconductor wafer W at this time is 20° C. or more and 400° C. or less. Also, the heating time is 30 seconds or more and 60 minutes or less. By heating the resin film 40 in an atmosphere containing trimethylaluminum, the vicinity of the surface of the first phase P1 containing hemicellulose in the resin film 40 is impregnated with metal aluminum (Al). At this time, since the second phase P2 containing no hemicellulose hardly reacts with metallic aluminum, the surface of the second phase P2 is not impregnated with metallic aluminum. That is, the surface of only the first phase P1 containing hemicellulose in the resin film 40 is impregnated with metal aluminum. FIG. 6 is a diagram showing a cross-sectional structure of a semiconductor wafer W in which the surface of the first phase P1 containing hemicellulose is impregnated with aluminum.

Next, short-time heat treatment is performed on the resin film 40 in which the surface of the first phase P1 is impregnated with aluminum (step S5). Specifically, the resin film 40 impregnated with aluminum is heated for one second or less. In this embodiment, flash lamp annealing (FLA: Flash Lamp Anneal) is performed on the semiconductor wafer W on which the resin film 40 is formed. A semiconductor wafer W in which the surface of the first phase P1 of the resin film 40 as shown in FIG. 6 is impregnated with aluminum is carried into a flash lamp annealing apparatus. The surface of the semiconductor wafer W is irradiated with flash light from a xenon flash lamp. The irradiation time of flash light is 0.1 ms to 100 ms. In this embodiment, flash light is emitted from the flash lamp for an irradiation time of 0.8 milliseconds, for example.

By irradiating the surface of the semiconductor wafer W with a flash of light having a high irradiation intensity and an extremely short irradiation time, only the vicinity of the surface of the semiconductor wafer W including the resin film 40 is heated for an extremely short time. The first phase P1 of the resin film 40 whose surface is impregnated with aluminum is heated for a short period of time of one second or less by flash light irradiation, whereby aluminum diffuses in the first phase P1. On the other hand, aluminum does not diffuse into the second phase P2 of the resin film 40 whose surface is not impregnated with aluminum. FIG. 7 is a diagram schematically showing a cross-sectional structure of a semiconductor wafer W in which aluminum is diffused in the first phase P1 of the resin film 40. As shown in FIG.

In step S<b>5 , the resin film 40 may be heated to a temperature higher than the thermal decomposition temperature of the resin film 40 . In flash lamp annealing, even if the resin film 40 is heated to the thermal decomposition temperature or higher, the time at which the resin film 40 is heated to the thermal decomposition temperature or higher is one second or less. Diffuse in the first phase P1. Further, the higher the temperature reached by the resin film 40 during flash light irradiation, the easier it is for aluminum to diffuse in the first phase P1.

Hemicellulose is a polymer rich in oxygen atoms. Aluminum diffuses in the first phase P1 by flash light irradiation and reacts with oxygen atoms of hemicellulose, thereby curing the entire first phase P1 of the resin film 40 and improving the etching resistance. On the other hand, the etching resistance of the second phase P2 of the resin film 40 that has not reacted with aluminum is relatively low compared to the first phase P1. As a result, only the first phase P1 containing hemicellulose in the resin film 40 is selectively cured to obtain high etching resistance.

After the short-time heating of the resin film 40 is completed, the resin film 40 is developed (step S6). In this embodiment, the resin film 40 is developed by reactive ion etching (RIE), which is dry etching. By performing reactive ion etching on the resin film 40 in which only the first phase P1 containing hemicellulose has high etching resistance, only the second phase P2 having relatively low etching resistance is selectively etched and removed. The Rukoto. FIG. 8 is a diagram showing a cross-sectional structure of the semiconductor wafer W from which the second phase P2 of the resin film 40 has been removed by development. Since the second phase P2 is removed by the development process, only the first phase P1 remains in the regions of the semiconductor wafer W where the guide pattern 30 is not formed. In this manner, a fine pattern is finally formed on the semiconductor wafer W. FIG.

Next, the lower layer film 20 is etched using the patterned resin film 40 as a mask (step S7). This etching process is also performed by reactive ion etching. By etching the lower layer film 20 using the resin film 40 as a mask, the pattern formed in the resin film 40 is transferred to the lower layer film 20 . That is, the region of the lower layer film 20 corresponding to the second phase P2 is etched. FIG. 9 is a diagram showing a cross-sectional structure of a semiconductor wafer W in which a pattern is formed on the lower layer film 20. As shown in FIG.

Etching is performed using the first phase P1 of the resin film 40, in which trimethylaluminum (TMA) has reacted with hemicellulose and hardened, as a mask to etch only the lower layer film 20 without damaging the first phase P1. becomes. As a result, as shown in FIG. 9, a deep hole is formed in the underlying film 20 to manufacture a semiconductor device.

In this embodiment, first, a semiconductor wafer W is coated with a resin film 40 made of an induced self-assembly material, and the semiconductor wafer W is heated to form a first phase P1 containing hemicellulose and a first phase P1 containing hemicellulose. It is phase-separated into a second phase P2 that does not exist. Although a pattern is formed simply by phase-separating the resin film 40, both the first phase P1 and the second phase P2 have low etching resistance and are difficult to use as an etching mask. Therefore, by impregnating metal aluminum in the vicinity of the surface of only the first phase P1 containing hemicellulose in the resin film 40 and diffusing the aluminum by flash lamp annealing, the first phase P1 is selectively hardened to increase the etching resistance. increasing. As a result, only the second phase P2, which has relatively low etching resistance, is selectively removed by development, while the hardened first phase P1 remains, so that a pattern with excellent etching resistance can be formed. .

Hemicellulose is a polymer rich in oxygen atoms. Therefore, hemicellulose has a property of being easily reacted with metals such as aluminum. Because of this characteristic, when the phase-separated resin film 40 is heated in an atmosphere of trimethylaluminum, the vicinity of the surface of only the first phase P1 containing hemicellulose is impregnated with metallic aluminum. As a result, only the first phase P1 of the resin film 40 can be selectively cured. In addition, hemicellulose, which is also contained in plant cell walls, is a relatively inexpensive material.

Although the embodiments of the present invention have been described above, the present invention can be modified in various ways other than those described above without departing from the scope of the invention. For example, in the above-described embodiment, the development treatment for removing the second phase P2 is performed by dry etching. Wet development may be performed. As the developer supplied to the resin film 40, for example, acetic acid, acetone, isopropyl alcohol (IPA), propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), ethyl lactate, butyl acetate, cyclohexanone, etc. may be used. can be done. By supplying such a developer to the resin film 40 in which only the first phase P1 is cured, only the second phase P2 having relatively low etching resistance is selectively removed, as in the dry etching of the above embodiment. to be removed.

In the above embodiment, the first phase P1 containing hemicellulose is impregnated with aluminum as a metal, but the present invention is not limited to this, and Li, Be, B, Na, Mg, Al, Si, K , Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, Cd, In , Sn, Sb, Te, Cs, Ba, La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po, Ce, Pr, Nd, Pm, Sm, Eu , Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc. may be impregnated on the surface of the first phase P1. Even in this manner, the first phase P1 of the resin film 40 can be cured to obtain the same effects as in the above embodiment.

In the above-described embodiment, the semiconductor wafer W was heated in an atmosphere containing trimethylaluminum when the first phase P1 of the phase-separated resin film 40 was impregnated with a metal. An atmosphere containing trimethylaluminum may be brought into contact with the first phase P1 containing trimethylaluminum. Even without heating, the surface of the first phase P1 containing hemicellulose containing many oxygen atoms can be impregnated with aluminum by bringing an atmosphere containing trimethylaluminum into contact with the vicinity of the surface of the first phase P1.

Further, in the above embodiment, the short-time heat treatment (step S5) is performed immediately after the metal impregnation treatment (step S4). may be followed by development treatment, followed by heat treatment for a short period of time. Even in such a case, the vicinity of the surface of the first phase P1 of the resin film 40 is impregnated with a metal such as aluminum, which improves the etching resistance. Therefore, even if the resin film 40 is developed by reactive ion etching (RIE), which is dry etching, only the second phase P2 of the resin film 40, which has relatively low etching resistance, remains. It is selectively etched and removed, and only the first phase P1 can be reliably left. Then, the aluminum impregnated in the first phase P1 can be diffused into the first phase P1 by short-time heat treatment, as in the case of the above embodiment.

In the above embodiment, the process of impregnating the first phase P1 of the resin film 40 with a metal such as aluminum (step S4) is performed before the development process (step S6). However, when this development process is performed by wet development in which a developer is supplied to the resin film 40 to dissolve and remove the second phase P2, the development process is performed first, and then the first phase P1 is removed. You may make it perform the process which impregnates a metal. Even in such a case, the metal can be diffused into the first phase P1 in the same manner as in the above-described embodiment by performing heat treatment for a short period of time thereafter.

Also, the short-time heat treatment in step S5 is not an essential step. Even without flash lamp annealing, if the first phase P1 of the resin film 40 is impregnated with aluminum, the reaction between the hemicellulose containing many oxygen atoms and the aluminum progresses to some extent, and the first phase P1 is cured to form a second phase. The required etching resistance can be imparted to the single phase P1. However, short-time heat treatment such as flash lamp annealing allows the reaction between hemicellulose and aluminum to proceed more effectively, thereby sufficiently curing the first phase P1 of the resin film 40 .

The short-time heat treatment in step S5 is not limited to flash lamp annealing, and may be laser annealing in which the surface of the semiconductor wafer W including the resin film 40 is irradiated with laser light. That is, it is sufficient that the first phase P1 of the resin film 40 impregnated with aluminum is heated to a predetermined temperature or higher for one second or less.

Further, flash lamp annealing may be used for heating for phase separation of the resin film 40 in step S3. By using flash lamp annealing, the resin film 40 can be phase-separated into the first phase P1 and the second phase P2 while suppressing the occurrence of defects.

Further, in the above embodiment, the resin film 40 containing hemicellulose is formed by ejecting the treatment liquid made of the induced self-assembly material containing the block copolymer containing hemicellulose onto the semiconductor wafer W. The polymer contained in is not limited to hemicellulose. The polymer contained in the block copolymer contained in the induced self-assembly material is a polymer containing oxygen atoms, and the oxygen atom content of the polymer is 20% by mass or more with respect to the total mass of the polymer. (Material 1) may be used. Hemicellulose is the polymer contained in the material 1 .

In particular, the induced self-assembly material has a structure represented by the general formula shown in FIG. 10 and a structure represented by the general formula shown in FIG. A block copolymer (material 2) containing a polymer portion b having a structure represented by the general formula 12 is preferred. The content of the polymerized part a in the block copolymer is 3% by mass or more and 80% by mass or less with respect to the total mass of the block copolymer.

10 and 11, each R1 independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group, an acyl group, an aryl group or a phosphoryl group; can be different. R5 represents a hydrogen atom or an alkyl group, and multiple R5s may be the same or different. X1 and Y1 each independently represent a single bond or a linking group, multiple X1s may be the same or different, and multiple Y1s may be the same or different. p represents an integer of 2 or more and 1500 or less, r represents an integer of 0 or more, and at least one of a plurality of r represents an integer of 1 or more. The * mark represents a binding site to any one of R1 when r is 2 or more, or represents a binding site to any one of the oxygen atoms to which R1 is bonded in place of R1.

In FIG. 12, W1 represents a carbon atom or a silicon atom, and plural W1 may be the same or different. W2 represents -CR2-, -O-, -S-, -SiR2-, and a plurality of W2 may be the same or different (provided that R is a hydrogen atom or a represents an alkyl group, and multiple Rs may be the same or different). R11 represents a hydrogen atom, a methyl group or a hydroxyl group, and plural R11 may be the same or different. R12 represents a hydrogen atom, a hydroxyl group, an acetyl group, a methoxycarbonyl group, an aryl group or a pyridyl group, and a plurality of R12 may be the same or different. q represents an integer of 2 or more and 3000 or less.

As material 2, for example, a block copolymer of sugar methacrylate and styrene described in Japanese Patent No. 6508422 is exemplified.

INDUSTRIAL APPLICABILITY The technique according to the present invention is suitable for a pattern forming method using an induced self-assembly technique and a semiconductor manufacturing method including the same.

REFERENCE SIGNS LIST 10 base material 20 underlayer film 30 guide pattern 40 resin film P1 first phase P2 second phase W semiconductor wafer

Claims (8)

A pattern forming method for forming a pattern on a substrate, comprising:
a film-forming step of coating and forming a resin film made of an induced self-assembly material containing a polymer containing oxygen atoms on a substrate;
a first heating step of heating the substrate to separate the resin film into a first phase containing the oxygen atom-containing polymer and a second phase not containing the oxygen atom-containing polymer;
an impregnation step of impregnating the first phase with a metal in a gas containing metal atoms;
a developing step to remove the second phase;
with
The impregnation step includes a second heating step of heating the substrate in a gas containing the metal atoms,
The pattern forming method , further comprising, after the impregnation step, a third heating step of heating the resin film to a predetermined temperature or higher for one second or less . In the pattern formation method according to claim 1 ,
The pattern forming method, wherein in the third heating step, the resin film is irradiated with flash light or laser light. In the pattern forming method according to claim 1 or 2 ,
The pattern forming method, wherein in the developing step, the second phase is removed by dry etching. In the pattern forming method according to claim 1 or 2 ,
The pattern forming method, wherein in the developing step, a developer is supplied to the resin film to dissolve and remove the second phase. In the pattern formation method according to claim 4 ,
The pattern forming method, wherein the developing step is performed before the impregnating step. In the pattern forming method according to any one of claims 1 to 5 ,
A pattern forming method, wherein the oxygen atom content of the polymer is 20% by mass or more with respect to the total mass of the polymer. In the pattern formation method according to claim 6 ,
A pattern forming method, wherein the polymer is hemicellulose. 8. A semiconductor manufacturing method comprising the pattern forming method according to claim 1 , wherein the substrate is etched using the resin film as a mask.

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