JP2004163451A - Method for forming pattern and method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a precise pattern can not be formed in an ArF resist for exposure to ArF excimer laser light because of inferior durability of the resist against fluorine-based dry etching. <P>SOLUTION: Etching durability of a resist mask 6 patterned by lithography is increased by injecting H<SP>+</SP>ions into the resist mask 6. As H<SP>+</SP>ions can be injected in a large amount into the resist without damaging the resist pattern, the resist mask 6 is modified to have sufficient etching durability. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pattern forming method using a resist (ArF resist) exposed by an ArF excimer laser beam as a mask, and more particularly to a method for improving the etching resistance of a resist mask to dry etching using a fluorine-based etching gas. .
[0002]
Photolithography using short-wavelength light of 200 nm or less, for example, ArF excimer laser light, is used for manufacturing semiconductor devices that require fine processing.
However, a resist (for example, an ArF resist) exposed by such short-wavelength light has poor dry etching resistance. Therefore, it is not possible to directly pattern an interlayer insulating film, wiring, or the like using this resist as a mask for dry etching. difficult. For this reason, it is common practice to transfer a resist mask pattern to a hard mask and pattern the interlayer insulating film, wiring, and the like using the hard mask as an etching mask. Nevertheless, it is difficult to form a sufficiently precise hard mask pattern due to the poor dry etching resistance of the resist.
[0003]
Therefore, there is a demand for a method of modifying a resist pattern formed by exposing and developing a short wavelength light resist to a resist mask having excellent dry etching resistance.
[0004]
[Prior art]
A resist exposed to light having a short wavelength of 200 nm or less, for example, an ArF resist exposed and patterned by ArF excimer laser light having a wavelength of 193 nm has low etching resistance particularly to dry etching using a raw material containing fluorine as an etching gas. Problems caused by the characteristics of the resist will be described with reference to a conventional hard mask forming process.
[0005]
FIG. 4 is a cross-sectional view of a conventional hard mask forming process, showing a process of forming a hard mask for etching an interlayer insulating film using an ArF resist as a mask.
Referring to FIG. 4A, first, an etching stopper film 2 and an interlayer insulating film 3 are sequentially stacked on a lower insulating film 1 formed on a semiconductor substrate (not shown). Further, a hard mask material film 4 and an antireflection film (BARC) 5 are sequentially formed on the interlayer insulating film 3. Next, an ArF resist is applied on the antireflection film 5, exposed to ArF excimer laser light, and developed to form a resist mask 6 made of a patterned ArF resist.
[0006]
4B and 4C, the anti-reflection film 5 and the hard mask material film 4 are sequentially dry-etched to form a hard mask made of the hard mask material film 4 to which the pattern of the resist mask 6 has been transferred. 4a is formed. The dry etching of the antireflection film 5 and the hard mask material film 4 uses a gas containing fluorine as an etching gas.
[0007]
Next, referring to FIG. 4D, the resist mask 6 and the antireflection film 5 remaining after the dry etching are removed by etching, leaving the hard mask 4a. The hard mask 4a thus formed is used as an etching mask in a subsequent dry etching step of the interlayer insulating film 3.
FIG. 5 is a plan view of a conventional hard mask forming process, showing resist mask patterns before and after dry etching. FIGS. 5A and 5B are plan views corresponding to FIGS. 4A and 4C, respectively, showing resist mask patterns at the time of forming a resist mask and at the time of forming a hard mask. ing.
[0008]
In the above-described process, referring to FIG. 5A, resist mask 6 formed by exposing and developing an ArF resist has a substantially parallel linear pattern. However, when the patterning of the anti-reflection film 5 and the hard mask material film 4 is completed and the hard mask 4a is formed, the pattern of the resist mask 6 which is initially linear, as shown in FIG. Deformed into a wiggling pattern. Furthermore, a large striation occurs on the side surface or the surface of the pattern of the hard mask 4a. Even if the interlayer insulating film 3 is patterned using such a hard mask, precise patterning cannot be performed.
[0009]
The occurrence of the wiggling and the striation is caused by the fact that the dry etching resistance of the resist is inferior to that of the resist exposed to light of 200 nm or more. The occurrence of such a defect can be prevented by irradiating an electron beam and curing the resist to enhance the dry etching resistance of the resist. On the other hand, curing by heating and ion irradiation does not provide sufficient dry etching resistance (for example, see Non-Patent Document 1).
[0010]
[Non-patent document 1]
Jiscoo Kim, Y. S. Chair (YS Chea), W.C. S. Lee (WS Lee), Jay. W. (JW Shon), Day. S. Nam (DS Nam), Etch. W. HW Kang, and Jay. Te. Moon (JT Moon), Sub 0.12 μm Nitride Hard Mask Open Process with ArF Photoresist, “2001 Dry Process International Symposium” (Sub 0.12 μm Nitride Hard Mask Open Process with ArF Photoresist) 2001 DRY PROCESS INTERNATIONAL SYMPOSIUM) ", USA, 2001, VI-12, p. 253-258
[0011]
[Problems to be solved by the invention]
As described above, a resist that can be exposed to light having a wavelength of 200 nm or less has low etching resistance to dry etching using an etching gas containing fluorine, and cannot accurately pattern a workpiece.
Further, the method of increasing the dry etching resistance by irradiating the resist mask with an electron beam to increase the dry etching resistance requires an expensive apparatus for the electron beam irradiation, and the irradiation time is long, so that the manufacturing cost is increased.
[0012]
An object of the present invention is to provide a method for forming a resist mask pattern having excellent dry etching resistance by modifying a resist mask in a short time using an inexpensive apparatus.
[0013]
[Means for Solving the Problems]
A first structure of the present invention for solving the above-mentioned problems includes a step of forming a resist mask on a workpiece, a step of implanting hydrogen ions (H ⁺ ions) into the resist mask, Patterning the workpiece by dry etching using the mask as an etching mask.
[0014]
According to a second structure of the present invention, a step of forming a resist mask on a workpiece, and a step of forming a resist mask on a hydrogen plasma generated by an inductively coupled or electron cyclotron resonance (ECR) plasma generator. A hydrogen plasma treatment step of exposing the mask; and a step of patterning the workpiece by dry etching using the resist mask as an etching mask.
[0015]
In the above-described first configuration of the present invention, hydrogen ions (H ⁺ ions) are implanted into the resist mask. As a result, the dry etching resistance of the resist mask is improved. At this time, the pattern of the resist mask is hardly deformed.
Although the reason why the etching resistance is improved without causing deformation of the resist pattern by the H ⁺ ion implantation has not been completely elucidated, the inventors of the present invention speculate as follows. In order to improve the dry etching resistance by modifying the resist, it is necessary to implant a sufficient amount of ions into the resist. However, when irradiation with ions having a large mass is performed, the resist pattern is etched, so that a large amount of ions cannot be implanted. On the other hand, since the H ⁺ ions have a small diameter and a small mass, the amount of etching of the resist is small even if it collides with the resist molecules. For this reason, since a large amount of ions are implanted into the resist without depleting the resist pattern, it is presumed that the resist can be sufficiently modified without deformation of the resist pattern.
[0016]
In the second configuration of the present invention, the resist mask is exposed to hydrogen plasma generated by an inductively coupled or electron cyclotron resonance type plasma generator. As a result, the dry etching resistance of the resist mask is improved as in the first configuration. Since the hydrogen plasma generated by such a plasma generator has a high degree of dissociation, the H ⁺ ion concentration ratio with respect to hydrogen molecules, hydrogen radicals, or hydrogen molecule ions is high. Therefore, also in the second configuration, as in the first configuration, a large amount of H ⁺ ions are implanted into the resist mask, so that the dry etching resistance of the resist is improved.
[0017]
In the exposure of the resist mask to the hydrogen plasma in the second configuration, it is preferable to dispose the resist mask outside the hydrogen plasma and expose the resist mask to a stream of ions emitted from the hydrogen plasma. Heavy ion species such as hydrogen molecules, hydrogen radicals, and hydrogen molecule ions are confined inside the hydrogen plasma because of their low velocity, and light H ⁺ ions increase outside the hydrogen plasma. Therefore, H ⁺ ions are implanted more effectively outside the hydrogen plasma than in the plasma.
[0018]
In the second configuration of the present invention, it is preferable that a high frequency bias voltage of 50 KHz to 1 MHz is applied to the workpiece holding table on which the workpiece is placed during the hydrogen plasma processing step. In the frequency range where the applied bias voltage is applied, the moving speed of heavy ions in the hydrogen plasma does not increase, and light H ⁺ ions are implanted into the resist mask. In order to selectively implant H ⁺ ions, it is more preferable to apply a high frequency bias voltage of 100 kHz to 600 kHz.
[0019]
Further, it is desirable to generate hydrogen plasma under a pressure of 0.66 Pa or less. Under low pressure, the bias voltage is high and the energy loss of ions is small, so that high-energy H ⁺ ions are implanted into the resist mask, so that the dry etching resistance is increased up to the deep portion of the resist pattern. This is effective in suppressing a reduction in the thickness of the resist mask due to dry etching.
[0020]
Further, in the first to third configurations of the present invention, the resist mask can be formed by developing a resist film exposed to light having a wavelength shorter than 200 nm, for example, light having a shorter wavelength than ArF excimer laser light. . Further, in the above-described pattern forming method of the present invention, the dry etching of the workpiece can be performed by reactive ion etching using an etching gas containing fluorine. Since a resist exposed to short-wavelength light such as ArF excimer laser light has low etching resistance particularly to dry etching using an etching gas containing fluorine, the present invention is applied to a pattern forming process using such a resist or an etching gas. It is useful to apply.
[0021]
A third configuration of the present invention is a method for manufacturing a semiconductor device, wherein an insulating film, for example, an interlayer insulating film is formed using the workpiece pattern formed by any one of the first to fourth configurations as a hard mask. And a step of performing dry etching.
In the present invention described above, H ⁺ ion implantation apparatus for reforming the resist mask, for example using a plasma generator implanting H ⁺ ions. Therefore, an expensive device such as an electron beam irradiation device is not required. Further, H ⁺ ion implantation by plasma irradiation is performed in a short time. Therefore, according to the present invention, the resist mask can be modified in a short time using an inexpensive apparatus.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be described in detail with reference to an embodiment in which the present invention is applied to a manufacturing process of a single damascene wiring of a semiconductor device. 1 and 2 are cross-sectional views (part 1) and (part 2) of a process according to an embodiment of the present invention, showing a process of forming a wiring groove for damascene wiring in an interlayer insulating film using a hard mask. . FIG. 3 is a sectional view of a resist mask processing apparatus according to an embodiment of the present invention, and shows a plasma processing apparatus for implanting H ⁺ ions.
[0023]
First, referring to FIG. 1A, a 30 nm-thick plasma SiC is formed on a semiconductor substrate (semiconductor substrate 11 in FIG. 3) having a diameter of 200 mm to 300 mm (not shown) on which a lower insulating film 1 is formed. An interlayer insulating film 3 having a thickness of 300 nm was laminated via a stopper film 2 made of. Note that a semiconductor circuit element is formed on the surface of the semiconductor substrate 11 in advance. The interlayer insulating film 3 is formed of a known organic Low-k (low dielectric constant) insulating film formed by, for example, a CVD method or a coating method. Next, a hard mask material film 4 made of plasma SiO _{2 having} a thickness of 50 nm is deposited. This hard mask material film 4 is the workpiece in the present embodiment. In addition, as the stopper film 2 and the hard mask material film 4, an SiN film, a SiO ₂ film, or a SiON film may be used. Next, an antireflection film (BARC) 5 having a thickness of 80 nm is applied and deposited, and an ArF resist (resist exposed by ArF excimer laser light) is applied thereon. Next, pre-annealing is performed at 200 ° C. for 1 minute.
[0024]
Next, the single damascene wiring pattern is exposed using ArF excimer laser light (wavelength 193 nm), and then developed using a 2.8% TMAH (tetramethylammonium hydroxide) solution to form an opening 7 having a wiring pattern shape. The opened resist mask 6 is formed. Note that post-baking was performed at 120 ° C. for 30 seconds.
[0025]
Next, referring to FIG. 1B, H ⁺ ions 8 are implanted into the resist mask 6. In the present embodiment, a normal inductively coupled plasma generator is used as a resist mask processing device used for H ⁺ ion implantation. Referring to FIG. 3, the resist mask processing apparatus includes a work holding table 10 for holding a work in a lower portion of chamber 15. A high frequency bias voltage can be applied to the workpiece holder 10 from a bias power supply 17. Further, a gas inlet 14 is provided in the upper part of the chamber 15, and an induction coil 12 for plasma excitation is provided on the outer periphery of the upper part of the chamber 15.
[0026]
First, the semiconductor substrate 11 is placed on the workpiece holder 10 with the resist mask 4a facing upward. Next, 300 sccm of H ₂ gas is flowed into the chamber 15 from the gas inlet 14, and the pressure in the chamber is maintained at 0.66 Pa. Next, plasma excitation power is applied to the induction coil 12 to generate a hydrogen plasma 13 in the upper part of the chamber 15. At the same time, a high frequency bias voltage is applied to the work holding table 10. As a result, H ⁺ ions 16 are selectively released from the hydrogen plasma 13 generated upward away from the resist mask 4a, accelerated to a high energy by a bias voltage, and implanted into the resist mask 4a. Next, the supply of the plasma excitation power and the high frequency bias voltage is stopped, and then the introduction of the H ₂ gas is stopped. In this H ⁺ ion implantation step, a high frequency of 13.56 MHz and 1 KW was used for plasma excitation, and a high frequency of 100 KHz and 1 KW was used as a high frequency bias voltage. As a result, a bias voltage of 1 KV was generated. The application time of these high frequencies was set to 10 seconds.
[0027]
Next, the semiconductor substrate 11 is carried into a parallel plate type reactive ion etching (RIE) apparatus, and the antireflection film 5 and the hard mask material film 4 are etched using an etching gas containing fluorine and a resist mask 6 as an etching mask. Dry etching is performed sequentially.
First, referring to FIG. 1C, the antireflection film 5 was etched using a mixed gas of CF ₄ and Ar as an etching gas. The etching gas pressure is 6.6 Pa, and the plasma excitation power is 500 W. Next, referring to FIG. 1D, the hard mask material film 4 was etched using a mixed gas of C ₄ F ₈ , O ₂ and Ar as an etching gas to form a hard mask 4a. Note that C ₄ F ₆ or C ₅ F ₈ may be used instead of C ₄ F ₈ of the etching gas. The etching gas pressure is 4.0 Pa and the plasma excitation power is 600 W.
[0028]
Next, referring to FIG. 2E, the resist mask 6 and the antireflection film 5 are sequentially removed to leave the hard mask 4a to which the wiring pattern has been transferred. The resist mask 6 was removed by oxygen plasma, and the antireflection film 5 was removed by wet etching. If there is no problem, the antireflection film 5 can be left. After this step, the pattern formation of the workpiece, that is, the pattern formation step of the hard mask 4a is completed.
[0029]
Next, referring to FIG. 2 (f), a hard mask 4a having an opening in a wiring pattern shape is used as an etching mask, and interlayer insulating is performed by reactive ion etching using a mixed gas of CF ₄ and CHF ₃ as an etching gas. The film 3 is etched to form a wiring groove 3a for a single damascene wiring having a wiring pattern shape.
[0030]
Next, a Cu film is deposited on the entire surface including the interlayer insulating film 3 and the wiring groove 3a, the Cu film on the interlayer insulating film 3 is removed by CMP (chemical mechanical polishing), and the single film embedded in the wiring groove 3a is removed. In the present embodiment in which the damascene Cu wiring 9 is formed, even if dry etching is performed using a gas containing fluorine to form the hard mask 4a, the pattern of the resist mask 6 is small and the precise hard mask 4a is formed. Could be formed.
[0031]
In the above-described embodiment of the present invention, the present invention is applied to a method of forming a hard mask. However, the present invention is not limited to this. For example, when a resist mask is used as a dry etching mask for forming a pattern of an interlayer insulating layer. As described above, the present invention can be applied to a process in which a resist mask is used as a dry etching mask.
In the above specification, the following supplementary inventions are disclosed.
[0032]
(Supplementary Note 1) a step of forming a resist mask on the workpiece;
Implanting hydrogen ions into the resist mask;
Patterning the workpiece by dry etching using the resist mask as an etching mask.
[0033]
(Supplementary Note 2) a step of forming a resist mask on the workpiece;
A hydrogen plasma processing step of exposing the resist mask to hydrogen plasma generated by an inductively coupled or electron cyclotron resonance plasma generator,
Patterning the workpiece by dry etching using the resist mask as an etching mask.
[0034]
(Supplementary Note 3) a step of forming a resist mask on the workpiece;
A hydrogen plasma processing step of generating hydrogen plasma by an inductively coupled or electron cyclotron resonance type plasma generator and exposing the resist mask to an ion stream emitted from the hydrogen plasma,
Patterning the workpiece by dry etching using the resist mask as an etching mask.
[0035]
(Supplementary Note 4) In the pattern forming method according to Supplementary note 2 or 3,
A pattern forming method, wherein a high-frequency bias voltage of 50 KHz to 1 MHz is applied to a workpiece holding table on which the workpiece is placed during the hydrogen plasma processing step.
(Supplementary Note 5) In the pattern forming method according to Supplementary Note 2, 3, or 4,
The pattern forming method, wherein the hydrogen plasma is a low-pressure plasma of 0.66 Pa or less.
[0036]
(Supplementary Note 6) In the pattern forming method according to Supplementary Note 1, 2, 3, 4, or 5,
The pattern forming method, wherein the resist mask is formed by developing a resist film exposed to light having a shorter wavelength than ArF excimer laser light.
(Supplementary Note 7) In the pattern forming method according to Supplementary Note 1, 2, 3, 4, 5, or 6, the dry etching of the workpiece is reactive ion etching using an etching gas containing fluorine. Pattern formation method.
[0037]
(Supplementary Note 8) The method further includes a step of dry-etching an insulating film using the workpiece pattern formed by the pattern forming method according to Supplementary Note 1, 2, 3, 4, 5, 6, or 7 as a hard mask. Semiconductor device manufacturing method.
[0038]
【The invention's effect】
According to the present invention, the dry etching resistance of a resist mask is improved by a short process using an inexpensive apparatus, so that a precise etching pattern can be formed at a low manufacturing cost, and the reliability of a semiconductor device is improved. And it greatly contributes to reduction of manufacturing cost.
[Brief description of the drawings]
FIG. 1 is a process sectional view of an embodiment of the present invention (part 1).
FIG. 2 is a process sectional view of an embodiment example of the present invention (part 2).
FIG. 3 is a sectional view of a resist mask processing apparatus according to an embodiment of the present invention. FIG. 4 is a sectional view of a conventional hard mask forming process. FIG. 5 is a plan view of a conventional hard mask forming process.
DESCRIPTION OF SYMBOLS 1 Lower insulating film 2 Stopper film 3 Interlayer insulating film 3a Wiring groove 4 Hard mask material film 4a Hard mask 5 Anti-reflection film 6 Resist mask 7 Opening 8 H ⁺ ion 9 Cu wiring 10 Work holding table 11 Semiconductor substrate 12 Induction coil 13 Hydrogen plasma 14 gas inlet 15 chamber 16 H ⁺ ion 17 bias power supply

Claims (5)

A step of forming a resist mask on the workpiece,
Implanting hydrogen ions into the resist mask;
Patterning the workpiece by dry etching using the resist mask as an etching mask. A step of forming a resist mask on the workpiece,
A hydrogen plasma processing step of exposing the resist mask to hydrogen plasma generated by an inductively coupled or electron cyclotron resonance plasma generator,
Patterning the workpiece by dry etching using the resist mask as an etching mask. 3. The pattern forming method according to claim 2,
A pattern forming method, wherein a high-frequency bias voltage of 50 KHz to 1 MHz is applied to a workpiece holding table on which the workpiece is placed during the hydrogen plasma processing step. The pattern forming method according to claim 1, 2 or 3,
The method of forming a pattern, wherein the resist mask is formed by developing a resist film exposed to light having a shorter wavelength than ArF excimer laser light. 5. A method for manufacturing a semiconductor device, comprising a step of dry-etching an insulating film using the workpiece pattern formed by the pattern forming method according to claim 1, 2, or 3 as a hard mask.

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