JP3339153B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a fine pattern and a method for manufacturing a semiconductor device using the method.

[0002]

2. Description of the Related Art Currently, in the research and development of semiconductor integrated circuits, design rule devices in the sub-half micron range are being researched and developed. In the photolithography technology used in the development of these devices, the most advanced stepper (reduction projection exposure machine) currently uses a KrF excimer laser beam (248 nm) as a light source, and a light source of 0.37 to 0.37 nm.
A lens having a numerical aperture (NA) of about 0.50 is mounted (for example, Nikon NSR1505EX1, Canon FP
A4500). Research and development of design rule devices in the sub-half micron (0.5 μm or less) region have been studied using these steppers.

A stepper uses light of a single wavelength as an exposure light source. It is widely known that when exposure is performed at a single wavelength, a phenomenon called a standing wave effect occurs.
The reason why the standing wave is generated is that light interference of exposure light occurs in the resist film. That is, as shown in FIG. 1, the incident light P and the reflected light R from the interface between the resist PR and the substrate S cause interference in the film of the resist RR.

As a result, as shown in FIG. 2, the amount of light absorbed by the resist (vertical axis) changes depending on the resist film thickness (horizontal axis). In this specification, the amount of light absorbed by the resist refers to the amount of light absorbed by the resist itself, excluding surface reflection, absorption by the substrate, and the amount of light emitted from the resist. Such absorption light quantity,
It becomes the energy to cause a photoreaction of the resist.

FIG. 2 shows the result of examining a change in the amount of absorbed light depending on the thickness of a resist film (XP8843) formed on a silicon substrate. As the exposure light, KrF of λ = 248 nm was assumed. Further, the degree of change in the amount of absorbed light differs depending on the type of the underlying substrate, as can be understood from a comparison between FIG. 3 and FIG. Figures 2, 3, 4
, XP8843 (Shipley) is used as a resist, but the underlying layers are Si and A1-S, respectively.
i, W-Si. That is, the degree of change in the amount of absorbed light is determined by the complex amplitude reflectance (R) in consideration of multiple interference determined by the optical constant (n, k) of the base (substrate) and the optical constant (n, k) of the resist. ((R) is a vector quantity having a real part and an imaginary part).

Further, in an actual device, there are always irregularities on the surface of the substrate S as schematically shown in FIG. For example, a predetermined pattern of a polysilicon film or the like may be formed on the substrate S, and a projection In such as polysilicon is present. Therefore, when the resist PR is applied, the resist film thickness differs between the upper part and the lower part of the step.
That is, the resist film thickness d _PR2 on the protrusion In is smaller than the other resist film thickness d _PR1 .

As described above, the standing wave effect varies depending on the resist film thickness. Therefore, the effect of the standing wave effect changes the amount of light absorbed by the resist. come. As a result, the dimensions of the resist pattern obtained after exposure and development are different between the upper part and the lower part of the step.

The effect of the standing wave effect on the pattern size becomes more pronounced as the pattern becomes finer when a stepper having the same wavelength and the same numerical aperture is used, and is common to any type of resist. It is a phenomenon.
Generally, the dimensional accuracy of a resist pattern in a photolithography process at the time of manufacturing a device such as a semiconductor device is ±
5%. The total accuracy is considered to be practicable even if it is less than ± 5%, but considering the occurrence of variations due to other factors such as focus, the pattern accuracy at the time of resist exposure is kept within ± 5%. It is desired. In order to achieve the dimensional accuracy of ± 5%, it is essential to reduce the standing wave effect.

FIG. 6 shows a dimensional change (vertical axis) of the resist pattern with respect to a change in the amount of absorbed light in the resist film (horizontal axis). As is apparent from FIG.
In order to manufacture a device having a rule of 5 μm, the fluctuation of the amount of light absorbed by the resist film is required to be within a range of 6% or less.

Further, when an actual semiconductor device is manufactured, a single step is performed on a base substrate having a step structure and a plurality of regions A and B having different reflectivities as shown in FIG. It is required that a fine resist pattern can be satisfactorily and stably formed by exposure. In FIG. 7, reference numeral 2 denotes a silicon substrate, reference numeral 4 denotes a polysilicon film, reference numeral 6 denotes a tungsten silicide film, reference numeral 8 denotes a silicon oxide film, reference numeral 10 denotes a resist film, and reference numeral 12 denotes a photomask. In the example shown in FIG. 7, an example in which the silicon oxide film 8 is patterned using a photomask 12 is shown.
The reflectance from the base substrate is different between the region A and the region B.

As shown in FIG. 8, when the reflectance from the underlying substrate is different, the amount of light absorbed by the resist film is naturally different. Even in such a situation, in order to form a fine and fine resist pattern with a single exposure, and stably,
The variation in the amount of light absorbed by the resist film requires that the above range be 6% or less even if there are regions where the reflectance from the underlying substrate differs on the film surface of the substrate.

[0012]

In order to meet the above-mentioned demands, antireflection techniques are being actively studied in various fields. The inventor of the present invention has made intensive studies on means for reducing the variation in the amount of light absorbed by the resist film to, for example, a range of 6% or less. As a result, refractory metal silicide such as tungsten silicide, metal such as Al-Si, and polysilicon SiC, SiO _x , S on silicon-based material
i _x O _y N _z, an antireflection film such as Si _z N _y is deposited,
It has been found that the standing wave effect can be reduced by forming a resist film thereon.

However, the materials of these antireflection films are determined in accordance with the material of the substrate to be antireflection. Naturally, in actual device fabrication, when a mask pattern must be formed on a substrate having a step structure and having a different reflectivity at the location of the mask pattern within a single exposure area. There is. In this case, the amount of light absorbed by the resist film differs at the location of the mask pattern due to the difference in reflectance at the location, and as a result, the variation in the amount of light absorbed by the resist film is reduced to a range of 6% or less. Can not do.

As a conventional technique for forming a good mask pattern on a base substrate having a stepped structure and having different reflectivities at places, a multilayer resist method, and further, a mask is divided into a plurality of sheets. That is, a method of performing pattern formation by a plurality of exposures is known.

However, the multi-layer resist method is complicated due to the complexity of the process.
Since the demand for alignment accuracy becomes extremely strict, it is required in the manufacturing process of semiconductor devices, etc.
It cannot be a method for forming a fine pattern.

Therefore, a fine resist pattern can be satisfactorily and stably formed by a single exposure even on an undersubstrate having a step structure and a plurality of different high reflection regions having different reflectivities. It is desired to establish an anti-reflection technology capable of performing the above. The present invention has been made in view of the above circumstances, and forms a fine resist pattern in a single exposure on a base substrate including at least two regions having mutually different optical conditions, in a favorable and stable manner. It is an object of the present invention to provide a method for manufacturing a fine pattern and a method for manufacturing a semiconductor device using the same.

[0017]

[0018]

[0019]

[0020]

To achieve SUMMARY and operation for solving the above objects, a manufacturing method of the engaging Ru semi conductor arrangement in the present invention,
On the film to be processed, a high light-absorbing property with respect to the wavelength of the exposure light used in the photolithography process, and a high melting point metal, a high melting point metal compound, or a high melting point metal silicide Forming an absorption film, forming an antireflection film on the high absorption film, forming a resist film on the antireflection film, and processing the resist film into a predetermined pattern by photolithography. Forming a hole in the film to be processed by etching the antireflection film, the high absorption film and the film to be processed into a predetermined pattern by using the resist film having the predetermined pattern as a mask; As described above, on the antireflection film, a base film made of any one of a high melting point metal, a high melting point metal compound and a high melting point metal silicide is formed. And a step of burying and forming a conductive plug layer in the hole in which the base film is formed, and thereafter, a base film other than the inside of the hole, an antireflection film, a high absorption film, Etching the upper part of the conductive plug layer.

In the present invention, light having a wavelength of i-ray (365 nm) or shorter, for example, i-ray, KrF, ArF
Using excimer laser as a light source, when forming a fine pattern on the underlying substrate, in order to form a fine resist pattern in a single exposure, good and stable
First, a high absorption film is formed on the base substrate. This high absorption film is a film having a high light absorption for the wavelength of the exposure light used in the photolithography process. By forming this film, the region where the optical conditions are different (and both have relatively high reflection) Light reflected from the undersubstrate on which the (region) is formed can be reduced to 2% or less. By forming this high absorption film on the underlying substrate, the reflected light reflected from the regions having different optical conditions is 2% or less, and the underlying substrate can be regarded as a single type of substrate.

The following means was used to determine a high-absorbing film so that the amount of light reflected from regions having different optical conditions with respect to the exposure light was 2% or less. (I) An area in which the optical conditions are different is regarded as a single substrate, and the energy for photoreacting the resist with respect to each of the plurality of substrates in consideration of multiple interference of exposure light in the resist film. The amount of light absorbed by the resist is determined. The degree of the amount of absorbed light differs depending on the optical constant (n, k) of each substrate.

(II) For each of a plurality of substrates having different optical constants, assuming that a high absorption film (k> 0) is formed on the substrate, the thickness of the high absorption film is gradually reduced. The amount of light absorbed by the resist film is determined in consideration of the multiple interference of the exposure light within the resist film.

(III) Variations in the amount of absorbed light inside the resist film for each substrate obtained on the assumption that there are high absorption films on a plurality of substrates having different optical constants obtained in (II) above. Here, the optical constant and the film thickness of the high absorption film are determined so that each result is the same.

(IV) A film of an actual material having the conditions obtained in the above (III) is used as the high absorption film in the present invention. When a high-absorbing film that can be used in the present invention was searched for using the above-mentioned means (I) to (IV), n = 0.
It has been found that silicon-based materials such as monocrystalline silicon, polycrystalline silicon, amorphous silicon, and doped silicon having 5 to 7 and k = 1.5 to 3.5 are desirable. The thickness of such a silicon-based high absorption film is 9.5 to 40 n.
It has been found preferable to use m.

It has also been found that a high melting point metal such as tungsten or titanium or a compound of a high melting point metal, particularly a titanium-based material such as titanium nitride or titanium oxynitride, is desirable. Such a refractory metal or a compound of a refractory metal has n =
It has an optical constant of 0.5 to 3.0 and k = 0.5 to 3.0. In addition, it has been found that the thickness of the high-absorbing film made of the high-melting-point metal or the compound of the high-melting-point metal is preferably 15 to 120 nm.

Further, it has been found that a high melting point metal silicide-based material such as tungsten silicide is desirable. This refractory metal silicide-based material is
It has optical constants of n = 0.5 to 4.5 and k = 1.5 to 3.5. Further, it has been found that the thickness of the high absorption film composed of the high melting point metal silicide is preferably 8 to 30 nm.

By forming a highly absorbing film of such a material on a base substrate including at least two regions having mutually different optical conditions, the reflectance from the base substrate can be suppressed to 2% or less. Optically, the underlying substrate can be regarded as a single type of substrate.

In the present invention, on such a high absorption film,
An anti-reflection film is formed. The determination of the antireflection film was performed using the following means. (I) For a resist film of a certain thickness that is arbitrarily determined,
Contour lines of the amount of light absorbed in the resist film when the optical conditions (n, k) of the antireflection film are continuously changed (however, the thickness of the antireflection film is fixed) are obtained.

(II) In the result of the contour line of the amount of absorbed light inside the resist at the thickness of each resist film obtained in the above (I), a common area where the difference in the amount of absorbed light is minimized is found and limited by this common area. Optical conditions, (I)
The optical conditions (n, k) for the film thickness of the antireflection film determined in the above.

(III) By changing the thickness of the antireflection film,
By repeating the above operations (I) and (II), the optical constants (n, k) of each optimum condition for each film thickness of the antireflection film are obtained. (IV) An anti-reflection film of an actual material having an optical constant of the optimum condition obtained in the above (III) is found.

Next, referring to the drawings, the above means (I) to (4) for determining the comprehensive conditions of the antireflection film used in the present invention.
(IV) will be described more specifically. Between the maximum value of the standing wave effect, or resist film thickness between the minimum value, when the refractive index of the resist and n _PR, the wavelength of the exposure light is lambda, it is given by lambda / 4n (see FIG. 9).

Antireflection between resist and underlying substrate
In the process of the film ARL, its thickness d _arl, The optical constant is n
_arl, K_arlAnd One point in FIG. 9 (for example, when the standing wave effect is maximal)
The thickness d of the anti-reflection film
_arlAnd fix n_arl, K_arlIf you change the
The amount of light absorbed by the resist film at a point changes. This change
When the locus of the light, that is, the contour line of the absorbed light quantity is obtained, FIG.
0.

With respect to other different resist film thicknesses d _PR , at least at four locations at λ / 8n _PR intervals, based on the film thickness at which the standing wave effect is maximized or minimized.
11 to 13 corresponding to FIG. 10 are obtained (FIGS. 10 to 13 show that the antireflection film thickness is 20 nm).
And the resist film thicknesses are 985 nm and 1000 n, respectively.
m, 1018 nm, and 1035 nm are shown).
The above corresponds to the above means (I).

The common areas of the graphs in FIGS. 10 to 13 show areas where the amount of absorbed light in the resist film does not change even if the resist film thickness changes for a specific antireflection film thickness. . That is, the common area is an area where the standing wave effect is minimized and the antireflection effect is the highest.
Therefore, such a common area is found. The common area can be found, for example, simply by superimposing the respective figures (graphs) and taking the common area (of course, the common area may be searched by a computer). This corresponds to the above-mentioned means (II).

Next, the above is repeated while the thickness d of the antireflection film is continuously changed. For example, assuming that the operation is performed with d = 20 nm up to the first step, the above is repeated while changing d. Thereby, the thickness d _{arl of the} antireflection film that minimizes the standing wave effect,
The conditions of the optical constants n _arl and k _arl can be specified. This corresponds to the above means (III).

The type of film that satisfies the conditions (film thickness, optical constant) to be satisfied by the antireflection film specified above is found by measuring the optical constant of each film type in exposure light. This corresponds to the means (IV). The above method is applicable in principle to all wavelengths and all underlying substrates.

[0038] In means of the (I) ~ (IV), was examined for the reflection preventing film can be suitably used in the process according to the present invention, Si _X O _y N _z film or Si _X N _y film is particularly It turned out to be appropriate. That is, when the above material is used as the high absorption film, the antireflection film is an organic film or an inorganic film having an optical constant of n = 1.8 to 2.6 and k = 0.1 to 0.8. film, in particular, Si _X O _y N
The _z film (may contain hydrogen H) or Si _X N _y film was found that it is preferable to use a film thickness of 20 to 150 nm.

[0039] These Si _X O _y N _z film or Si _X N _y
The film can be easily formed by various CVD methods. For example, these films are formed by parallel plate type plasma CVD.
Method, ECR plasma CVD method, or bias ECR
A silane-based gas and a gas containing oxygen and nitrogen (for example, Si
A film can be formed using a mixed gas of H ₄ + O ₂ + N ₂ ) or a mixed gas of a silane-based gas and a gas containing nitrogen (for example, SiH ₄ + N ₂ O). At that time,
Argon Ar gas or the like can be used as the buffer gas.

For example, as shown in FIG. 14, the optical constants (n, k) of the obtained Si _x O _y N _z film are changed according to the conditions at the time of film formation, particularly the flow rate ratio of the silane-based gas. , N can be freely changed in the range of 1.5 to 2.7 and k is in the range of 0.1 to 0.8, so that the optical constant required as an antireflection film for a specific base substrate can be changed. An antireflection film having a value can be easily formed.

The Si _X O _y N _z film or Si
_{The XNy} film is formed of CF ₄ , CHF using a resist as a mask.
_3, C ₂ F _6, the _{C 4 F 8, SF 6,} S 2 F 2, NF 3 series gas as an etchant, by the addition of Ar RIE with increased ionic, can be easily etched. The RIE is performed under a pressure of about 2 Pa,
It is preferable to apply power of about 00W. Further, the flow rate of the gas at the time of RIE is not particularly limited.
Preferably it is ~ 70 SCCM.

After the pattern is transferred to the underlying substrate using the highly absorbent film to which the pattern has been transferred as a mask, a silicon-based, high-melting-point metal-based, high-melting-point metal is etched by an etch-back method using a fluorine-based gas. The metal compound-based or high melting point metal silicide-based highly absorbent film can be easily removed.

In the above-described method for manufacturing a fine pattern according to the present invention, the i-line (365n) is formed even on a base substrate having a plurality of regions having steps and different optical conditions.
light of shorter wavelength than m), such as i-line, KrF, ArF
Using an excimer laser as a light source, a fine resist pattern can be satisfactorily and stably formed by a single exposure.

The method for producing a fine pattern according to the present invention comprises:
In particular, it can be suitably used for a method for manufacturing a semiconductor device having a fine pattern.

[0045]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to the following examples, and can be variously modified within the scope of the present invention. Embodiment 1 In this embodiment, when manufacturing a semiconductor using light having a wavelength shorter than i-line (365 nm), for example, i-line, KrF, or ArF excimer lithography, a plurality of high reflectivity elements having different reflectivities are used. In a semiconductor manufacturing process in which a fine mask pattern is transferred onto one base substrate having a reflective layer region, polycrystalline silicon, amorphous silicon, doped polysilicon, or the like is used as a high absorption film formed on the entire base substrate. This is an example using a silicon-based material.

In the semiconductor manufacturing method of the present embodiment, first, as shown in FIG. 15, a semiconductor substrate 20 made of, for example, a silicon wafer is placed on a semiconductor substrate 20 with a gate insulating layer interposed therebetween.
Polysilicon layer 22 and tungsten silicide 24
A gate electrode having a polycide structure composed of A transparent insulating film 26 such as a silicon oxide film is formed thereon.
In the transparent insulating film 26, a region A located above the tungsten silicide 24 and a region B located above the impurity diffusion layer formed on the surface of the semiconductor substrate 20 are exposed using the photomask 30. At this time, the base substrate 25 (the semiconductor substrate 2 on which the polysilicon film 22, the tungsten silicide film 24, and the transparent insulating film 26 are formed)
The optical condition 0) is different.

Therefore, in this embodiment, first, the high absorption film 32 is formed on the entire surface of the transparent insulating film 26. In this embodiment, as the high absorption film 32, a silicon-based material such as polysilicon, amorphous silicon, and doped silicon is used. i-line (365 nm), KrF (248 nm), Ar
F (193 nm) polycrystalline silicon (Poly-
The optical constants (refractive index n) and absorption coefficient α (1 / nm) of Si) and amorphous silicon (α-Si) are as shown in Table 1 below.

[0048]

[Table 1]

The transmittance T of the film having the thickness d is represented by the incident light amount I₀ ,
Let the transmitted light amount be I, the wavelength be λ, and the absorption coefficient of the film be α
(= 4πk / λ), T (= I₀ / I) = exp (−αd). You
That is, the transmittance T increases as the absorption coefficient increases, and
Is larger, the smaller the 1 / e^Two The transmittance is 13.
It is about 5%. Incident light is reflected at the interface between the film and the underlying film
When the ratio is R (= 10 to 80%), I × R light is transmitted to the film.
And reflect. Therefore, the reflection that returns in one reflection
Assuming that the incident light amount is 1, the light component is 0.135 (= 1 /
e^Two) × (0.1-0.8) (= R) × 0.135 (=
1 / e ^Two) = Attenuate to about 0.0018 to 0.014
You. That is, 1 / e^Two A film that attenuates light to some extent
By using it, the reflected light can no longer be ignored.
It becomes.

Therefore, if a high absorption film satisfying such conditions is formed on the entire surface of the base substrate, the same substrate can be formed on the base substrate having a plurality of high reflection layers having different reflectivities. Is equivalent to a single substrate having only the reflectance of In the case where a silicon-based material such as polycrystalline silicon, amorphous silicon, or doped polysilicon is used as the high-absorbency film, as shown in Table 1, in order to satisfy αd ≧ 2, d = 9.5 to 40 nm. It can be seen that it is sufficient to use a film having a thickness of.

FIG. 16 shows the standing wave effect when a polysilicon film having a thickness of 40 nm is formed on a silicon substrate and a resist is applied on the film. As a resist, XP8
843 was used. The n _PR and k _PR of the resist were 1.802 and 0.0107, respectively. The n _poly and k _poly of the polysilicon film were 1.68 and 3.27, respectively. _Nsub and k of the semiconductor substrate
_sub was 1.572 and 3.583, respectively. KrF having a wavelength λ of 248 nm was used as exposure light.

FIG. 17 shows that tungsten silicide is
Again, a standing wave effect when a polysilicon film having a thickness of 40 nm is formed and a resist is applied on the film is shown. XP8843 was used as a resist. The n _PR and k _PR of the resist were 1.802 and 0.0107, respectively. The n _poly and k _poly of the polysilicon film were 1.68 and 3.27, respectively. The n _WSi and k _WSi of the tungsten silicide were 1.96 and 2.69, respectively. As the exposure light, the wavelength λ is 2
48 nm KrF was used.

In both figures, the horizontal axis represents the resist film thickness, and the vertical axis represents the amount of resist absorption which is a component that actually exposes the resist. 16 and 17 show the same result. That is, a silicon-based material such as polycrystalline silicon, amorphous silicon, or doped polysilicon having a thickness of 9.5 to 40 nm can be formed on an underlying substrate having a plurality of highly reflective layer regions having different reflectivities. By forming a film on the entire surface, the base substrate is substantially equivalent to a substrate having only the same reflection.

Therefore, as shown in FIG. 15, the high absorption layer 32 of the present embodiment is provided on the entire surface of the base substrate 25 on which the regions A and B having different optical conditions are formed. Has been proved to be able to be treated optically like a single substrate.

A resist film 28 shown in FIG. 15 is formed directly or via an antireflection film 34 on the surface of the high absorption layer 32. After that, if the resist film 28 is patterned using the photomask 30, the standing wave effect can be minimized.
The resist film 28 can be processed into a fine pattern with high accuracy.

FIG. 18 shows that a 9.5 to 40 nm polysilicon film is formed as a high absorption film on each of a silicon substrate and tungsten silicide as a base substrate.
When a Si _x O _y N _z film (containing hydrogen H) having a thickness of 20 to 150 nm is formed thereon as an antireflection film, and a resist film is formed thereon, the standing wave effect is obtained. Is shown.
As is clear from FIG. 18, regardless of the type of the underlying substrate,
It has been confirmed that the standing wave effect can be similarly minimized in both cases.

In the experiment shown in FIG. 18, XP8843 was used as a resist. The n _PR and k _PR of the resist were 1.802 and 0.0107, respectively. The n _poly and k _poly of the polysilicon film were 1.68 and 3.27, respectively. The n _WSi and k _WSi of the tungsten silicide were 1.96 and 2.69, respectively. _Nsub and k of the semiconductor substrate
_sub was 1.572 and 3.583, respectively. Si _X O _y N _z n _arl and k _arl membranes were respectively 2.15 and 0.67.

As exposure light, KrF having a wavelength λ of 248 nm was used. Further, the Si _X O _y N _z film is formed by using a parallel plate type plasma CVD method, an ECR plasma CVD method, or a bias ECR plasma CVD method and using microwaves (2.45 GHz) to form SiH ₄ + O ₂ + N _2.
Was formed using a mixed gas of

Example 2 In Example 2, the effect of the present invention was evaluated in the same manner as in Example 1 except that a titanium-based material such as titanium nitride or titanium oxynitride was used as the high absorption film. Proved.

I-line (365 nm), KrF (248 n
m), TiN, TiON in ArF (193 nm)
Constant (refractive index n) and absorption coefficient α (l / nm)
Are as shown in Table 2 below.

[0061]

[Table 2]

From Table 2 above, in the same manner as in Example 1, in order to satisfy αd ≧ 2 in titanium-based materials such as titanium nitride and titanium oxynitride, d
It can be seen that a film thickness of 15 to 120 nm may be used. FIG. 19 shows the standing wave effect when a titanium nitride TiN film having a thickness of 120 nm is formed on a silicon substrate and a resist is applied on the film. As a resist,
XP8843 was used. The n _PR and k _PR of the resist are
They were 1.802 and 0.0107, respectively. Ti
The n _TiN and k _TiN of the N film were 2.19 and 1.6, respectively. N _sub and k _sub of the semiconductor substrate are
They were 1.57 and 3.58, respectively. KrF having a wavelength λ of 248 nm was used as exposure light.

FIG. 20 shows that on tungsten silicide
Again, a standing wave effect when a 120 nm thick TiN film is formed and a resist is applied on the film is shown. XP8843 was used as a resist. The n _PR and k _PR of the resist were 1.802 and 0.0107, respectively. N _TiN and k _TiN of the TiN film are each 2.1.
9 and 1.6. N of tungsten silicide
_WSi and k _WSi are 1.96 and 2.69, respectively.
Met. As the exposure light, K having a wavelength λ of 248 nm is used.
rF was used.

In both figures, the horizontal axis indicates the resist film thickness, and the vertical axis indicates the amount of resist absorption which is a component that actually exposes the resist. 19 and 20 show the same result. That is, even on an undersubstrate having a plurality of high-reflection layer regions having different reflectivities, a titanium-based material such as TiN or TiON having a film thickness of 15 to 120 nm is formed on the entire undersubstrate so that the undersubstrate can be formed. This is substantially equivalent to a substrate having only the same reflection.

Therefore, as shown in FIG. 15, the high absorption layer 32 of the present embodiment is provided on the entire surface of the base substrate 25 on which the regions A and B having different optical conditions are formed. Has been proved to be able to be treated optically like a single substrate.

A resist film 28 shown in FIG. 15 is formed directly or via an antireflection film 34 on the surface of the high absorption layer 32. After that, if the resist film 28 is patterned using the photomask 30, the standing wave effect can be minimized.
The resist film 28 can be processed into a fine pattern with high accuracy.

Example 3 In Example 3, the present invention was carried out in the same manner as in Example 1 except that a high melting point metal such as tungsten or tungsten silicide or a high melting point metal silicide-based material was used as the high absorption film. Proven effectiveness.

I-line (365 nm), KrF (248 n
m), optical constants (refractive index n) and absorption coefficient α (1 / nm) of W and WSi in ArF (193 nm) are as shown in Table 3 below.

[0069]

[Table 3]

As shown in Table 3, in the same manner as in Example 1, in the case of a high melting point metal such as tungsten and tungsten silicide or a high melting point metal silicide-based material, αd ≧ 2
It can be seen that in order to satisfy the above condition, the film thickness d should be 8 to 30 nm. FIG. 21 shows that 30 n
m of tungsten silicide WSi film,
7 shows the standing wave effect when a resist is applied on the film. XP8843 was used as a resist. Resist n
_PR and k _PR were 1.802 and 0.010, respectively.
It was 7. The n _WSi and k _WSi of the WSi film were 1.96 and 2.69, respectively. N of the semiconductor substrate
_sub and k _sub are 1.57 and 3.58, respectively.
Met. As the exposure light, K having a wavelength λ of 248 nm is used.
rF was used.

FIG. 22 shows that tungsten silicide is
Again, a standing wave effect when a WSi film having a thickness of 30 nm is formed and a resist is applied on the film is shown. XP8843 was used as a resist. N _PR and k of resist
_{The PR} was 1.802 and 0.0107, respectively. N _WSi and k _WSi of the WSi film are respectively 1.9.
6 and 2.69. Exposure light has a wavelength λ
Used KrF of 248 nm.

In both figures, the horizontal axis represents the resist film thickness, and the vertical axis represents the amount of resist absorption which is a component that actually exposes the resist. 21 and 22 show the same result. That is, a high melting point metal such as W or WSi or a high melting point metal silicide-based material such as W or WSi having a thickness of 8 to 30 nm is formed on the entire surface of the base substrate even on the base substrate having a plurality of high reflection layer regions having different reflectivities. Thereby, the base substrate is substantially equivalent to a substrate having only the same reflection. Therefore, as shown in FIG. 15, by providing the high absorption layer 32 of the present embodiment on the entire surface of the base substrate 25 on which the regions A and B having different optical conditions are formed, It was proved that it was possible to handle the same as a single substrate.

A resist film 28 shown in FIG. 15 is formed directly or via an antireflection film 34 on the surface of the high absorption layer 32. After that, if the resist film 28 is patterned using the photomask 30, the standing wave effect can be minimized.
The resist film 28 can be processed into a fine pattern with high accuracy.

Embodiment 4 In Embodiment 4, as shown in FIG. 23, a method of actually manufacturing a fine pattern on a semiconductor device will be described. As shown in FIG. 23A, a gate electrode having a polycide structure including a polysilicon layer 22 and a tungsten silicide 24 is formed on a semiconductor substrate 20 formed of, for example, a silicon wafer via a gate insulating layer. A transparent insulating film 26 such as a silicon oxide film is formed thereon as a film to be processed. In the transparent insulating film 26, a region located above the tungsten silicide 24 and a region located above the impurity diffusion layer formed on the surface of the semiconductor substrate 20 have a lower substrate 25 (poly) when performing exposure. Semiconductor substrate 2 on which silicon film 22, tungsten silicide film 24 and transparent insulating film 26 are formed
The optical condition 0) is different.

Therefore, in this embodiment, first, the high absorption film 32 is formed on the entire surface of the transparent insulating film 26. In this embodiment, as in the first embodiment, a silicon-based material such as polysilicon, amorphous silicon, or doped silicon is used as the high absorption film 32. The thickness of the high absorption film 32 is, for example, 40 nm. By forming a silicon-based material such as polycrystalline silicon, amorphous silicon, or doped polysilicon having a thickness of 40 nm over the entire surface of the base substrate 25, the base substrate 25 is substantially the same as a substrate having only the same reflection. Are equivalent to each other.

Next, an antireflection film 34 is formed on the surface of the high absorption film 32. As the anti-reflection film 34, for example, a Si _X O _y N _z film (containing hydrogen H) or a Si _X N _y film having a thickness of about 30 nm is formed by a parallel plate type plasma CVD.
Method, ECR plasma CVD method, or bias ECR
Microwave (2.45 GHz) using plasma CVD
Using z), a film was formed using a mixed gas of SiH ₄ + O ₂ + N ₂ .

Next, a resist film 28 was formed on the antireflection film 34. As the resist film 28, XP8
843 was used. Next, exposure was performed using a photomask to form fine patterns 40a and 40b on the resist. As exposure light, KrF having a wavelength λ of 248 nm is used.
Was used.

At this time, the high absorption film 32 and the anti-reflection film 34 are positioned below the resist film 28 so that even if a region having different optical conditions is formed on the underlying substrate 25, the standing wave effect can be obtained. Was almost eliminated, and good fine patterns 40a and 40b could be formed stably.

Next, in this embodiment, as shown in FIG. 23B, the antireflection layer 34 and the high absorption layer 32 were etched using the resist film 28 on which the fine patterns 40a and 40b were formed as a mask. When etching, C
Using a fluorine gas such as HF ₃ (50-100 SCCM) + O ₂ (30 SCCM), under a pressure of about 2 Pa, 100-1
RIE with high power of about 000W to enhance ionicity
(Reactive ion etching).

Next, as shown in FIG. 23C, the resist 28 was removed using oxygen plasma. Next, FIG.
In the state shown in (C), the entire surface of the base substrate 25 was etched back. In the etch-back process, fluorine gas was used at a pressure of about 2 Pa, a power of about 10 to 100 W was applied, and etch-back was performed by RIE with enhanced ionicity. By this etch back, FIG.
As shown in (D) and (E), an anti-reflection film 34 composed of a Si _x O _y N _z film or a Si _x N _y film and a high absorption film 32 composed of a silicon-based material form a transparent underlayer. Etching is performed together with the insulating film 26. The etch-back process is performed on the tungsten silicide layer 24 and the semiconductor substrate 2.
Contact holes 42a, 42 reaching the surface
The process ends when b is formed.

At the time when the above-mentioned etch-back process is completed, a fine mask pattern is formed by one exposure on the base substrate 25 having a plurality of high reflection layers having different reflectivities. Fifth Embodiment In a fifth embodiment, a method of actually manufacturing a fine pattern on a semiconductor device as shown in FIG. 23 will be described. In the fifth embodiment, as compared with the fourth embodiment, the high absorption film 32 is formed of a titanium-based material film (100 nm) such as titanium nitride or titanium oxynitride.
At the time of etching the high absorption film 32 made of a titanium-based material in the process shown in FIG.
In the etch-back process of the steps shown in FIGS.
A semiconductor device was manufactured in the same manner as in Example 4, except that a fluorine gas such as HF ₃ (50 to 100 SCCM) + C ₂ F ₂ (30 SCCM) was used.

Note that the steps shown in FIGS.
The etching selectivity in _Two / SiO_xN_y:
H = about 3 to 8, SiO_Two / TiN = about 3 to 8
Was. This etch back is performed by the gate electrode and active
Etching reaches the surface of the semiconductor substrate
It ends when it does.

At the time when the above etching is completed,
On a base substrate having a plurality of high reflection layers having different reflectances,
A fine mask pattern can be formed by one exposure. Embodiment 6 In Embodiment 6, as shown in FIG. 23, a method for actually manufacturing a fine pattern on a semiconductor device will be described. In the sixth embodiment, as compared with the fourth embodiment, as the high absorption film 32, a high melting point metal such as tungsten or tungsten silicide or a high melting point metal silicide-based material film (30 nm) is used.
When the high absorption film 32 made of a high melting point metal or a high melting point metal silicide-based material is etched in the step shown in FIG.
In the etch-back process in the steps shown in (C) to (E), CH
Except that a fluorine gas such as F ₃ (50-100 SCCM) + C ₂ F ₂ (30 SCCM) was used,
A semiconductor device was manufactured.

Also in this embodiment, a fine mask pattern can be formed on a base substrate having a plurality of high reflection layers having different reflectivities by a single exposure. Embodiment 7 In Embodiment 7, as shown in FIG. 24, a method of actually manufacturing a fine pattern on a semiconductor device will be described.

As shown in FIG. 24A, a gate electrode having a polycide structure composed of a polysilicon layer 22 and a tungsten silicide 24 is formed on a semiconductor substrate 20 composed of, for example, a silicon wafer via a gate insulating layer. Form. A transparent insulating film 26 such as a silicon oxide film is formed thereon as a film to be processed. In the transparent insulating film 26, a region located above the tungsten silicide 24 and a region located above the impurity diffusion layer formed on the surface of the semiconductor substrate 20 have a lower substrate 25 (poly) when performing exposure. The optical conditions of the semiconductor substrate 20) on which the silicon film 22, the tungsten silicide film 24, and the transparent insulating film 26 are formed are different.

Therefore, in this embodiment, first, the high absorption film 32 is formed on the entire surface of the transparent insulating film 26. In this embodiment, a titanium-based material such as titanium nitride or titanium oxynitride is used for the high absorption film 32 as in the second embodiment. The thickness of the high absorption film 32 is, for example, 1
00 nm. By forming a high absorption film 32 of a titanium-based material with a thickness of 100 nm over the entire surface of the base substrate 25, the base substrate 25 is substantially equivalent to a substrate having only the same reflection.

Next, an anti-reflection film 34 is formed on the surface of the high absorption film 32. As the anti-reflection film 34, for example, a Si _X O _y N _z film (containing hydrogen H) or a Si _X N _y film having a thickness of about 100 nm is formed by a parallel plate type plasma CV.
D method, ECR plasma CVD method, or bias EC
Microwave (2.45G) using R plasma CVD method
(Hz) using a mixed gas of SiH ₄ + O ₂ + N ₂ .

Next, a resist film 28 was formed on the antireflection film 34. As the resist film 28, XP8
843 was used. Next, exposure was performed using a photomask to form fine patterns 40a and 40b on the resist. As exposure light, KrF having a wavelength λ of 248 nm is used.
Was used.

At this time, the high absorption film 32 and the anti-reflection film 34 are positioned below the resist film 28, so that even if a region having different optical conditions is formed on the underlying substrate 25, the standing wave effect can be obtained. Was almost eliminated, and good fine patterns 40a and 40b could be formed stably.

Next, in this embodiment, FIG.
As described above, the registration with the fine patterns 40a and 40b
Anti-reflection layer 34, high absorption layer
32 and the transparent insulating film 26 were sequentially etched. S
i_XO_yN_zFilm (containing hydrogen H) or Si_XN_yWith membrane
At the time of etching the antireflection layer 34 thus constituted,
_Two F_Two (5-30 SCCM), C_Four F₈ (30-70 SCCM)
+ CHF_Three (10-30 SCCM), CHF_Three (50-10
0SCCM) + O _Two (3-20 SCCM) or other fluorine gas
Under a pressure of about 2 Pa, about 100 to 1000 W
RIE (Reactive)
Ion etching).

The etching of the titanium-based high absorption film 32 is performed by
This was performed using a chlorine-based gas. The etching of the transparent insulating film 26 is performed by S ₂ F ₂ (5 to 30 SCCM) and C ₄ F ₈ (30 to ₇ SCCM).
0 SCCM) + CHF ₃ (10-30 SCCM), CHF ₃ (5
0 to 100 SCCM) + O ₂ (3 to 20 SCCM), etc., and under a pressure of about 2 Pa, 100 to 1000
This was performed by RIE (reactive ion etching) in which a power of about W was applied and ionicity was enhanced. This etching ends when the etching reaches the surface of the gate electrode having the tungsten silicide film 24 and the surface of the active layer of the semiconductor substrate 20. By this etching, contact holes 42a and 42b of a fine pattern were formed in the transparent insulating film 26.

Next, as shown in FIG. 24C, the resist 28 was removed using oxygen plasma. Next, FIG.
2C, the surface of the base substrate 25 is
4D, the contact holes 42a, 42a
A titanium film 46 and a titanium nitride film 48 were formed to have a thickness of about 2 nm and 30 nm, respectively, so as to enter the area b.
This is a layer that becomes an adhesion layer when a wiring structure is formed using selective tungsten.

Thereafter, the conductive plug layers 44a and 44b made of tungsten were buried in the contact holes 42a and 42b by using the selective growth method using tungsten. Thereafter, a conductive plug layer 44a composed of tungsten, 44b using a fluorine-based gas, after etch back, a titanium film 46, a titanium nitride film 48, SiO _x N _y: H or Si _x N _y, etc. -Reflection layer 34 composed of: and titanium-based high absorption film 32
Was removed using a chlorine-based gas.

As a result, as shown in FIG. 25F, a semiconductor device in which the conductive plug layers 44a and 44b were buried in the fine pattern contact holes 42a and 42b was obtained. Example 8 In this example, the Si film shown in Examples 1 to 7 was used.
The _x O _y N _z film, except that to form an antireflection film was formed by the following method, in the same manner as those in Example, was formed a fine pattern on a semiconductor device.

That is, in the present embodiment, a parallel plate type plasma CVD method, an ECR plasma CVD method, or a bias ECR plasma CVD method is used, and microwaves (2.45 GHz) are used to form SiH ₄ + O ₂ + N ₂ . An antireflection film was formed using a mixed gas or a mixed gas of SiH ₄ + N ₂ O.

Embodiment 9 In this embodiment, the same as the embodiment 1 to the embodiment 7 shown in FIG.
The _x O _y N _z film, except that to form an antireflection film was formed by the following method, in the same manner as those in Example, was formed a fine pattern on a semiconductor device.

That is, in this embodiment, a parallel plate type plasma CVD method, an ECR plasma CVD method, or a bias ECR plasma CVD method is used, and a microwave (2.45 GHz) is used to produce SiH ₄ + O ₂ + N ₂ . Using a mixed gas or a mixed gas of SiH ₄ + N ₂ O,
An antireflection film was formed using Ar as a buffer gas.

Embodiment 10 In this embodiment, the same as the embodiment 1 to the embodiment 7 shown in FIG.
The _x O _y N _z film, except that to form an antireflection film was formed by the following method, in the same manner as those in Example, was formed a fine pattern on a semiconductor device.

That is, in this embodiment, parallel plate type plasma CVD, ECRCVD, or bias EC
A film was formed using a mixed gas of SiH ₄ + O ₂ + N ₂ or a mixed gas of SiH ₄ + N ₂ O by utilizing the RCVD method.

Embodiment 11 In this embodiment, the same as the embodiment 1 to the embodiment 7 shown in FIG.
The _x O _y N _z film, except that to form an antireflection film was formed by the following method, in the same manner as those in Example, was formed a fine pattern on a semiconductor device.

That is, in this embodiment, a parallel plate type plasma CVD method, an ECR plasma CVD method, or a bias ECR plasma CVD method is used to form SiH ₄ + O _2.
+ Mixed gas of N _2, or using a SiH ₄ + N ₂ O gas mixture was formed using Ar as a buffer gas.

Embodiment 12 In this embodiment, the same as the embodiment 1 to the embodiment 7 shown in FIG.
The _x N _y film, except that to form an antireflection film was formed by the following method, in the same manner as those in Example, was formed a fine pattern on a semiconductor device.

That is, in this embodiment, a parallel plate type plasma CVD method, an ECR plasma CVD method, or a bias ECR plasma CVD method is used, and a mixed gas of SiH ₄ + NH ₃ is used by using microwave (2.45 GHz). Alternatively, an anti-reflection film was formed using a mixed gas of SiH ₂ C ₁₂ + NH 3.

Embodiment 13 In this embodiment, the same as the embodiment 1 to the embodiment 7 shown in FIG.
The _x N _y film, except that to form an antireflection film was formed by the following method, in the same manner as those in Example, was formed a fine pattern on a semiconductor device.

That is, in this embodiment, a mixed gas of SiH ₄ + O ₂ , a parallel plate type plasma CVD method, an ECR plasma CVD method, or a bias ECR plasma CVD method is used by using microwaves (2.45 GHz). Alternatively, an anti-reflection film was formed using a mixed gas of SiH ₂ Cl ₂ + NH _{3 and} Ar as a buffer gas.

Embodiment 14 In this embodiment, the same as the embodiment 1 to the embodiment 7 shown in FIG.
The _x N _y film, except that to form an antireflection film was formed by the following method, in the same manner as those in Example, was formed a fine pattern on a semiconductor device.

That is, in this embodiment, a parallel plate type plasma CVD method, an ECR plasma CVD method, or a bias ECR plasma CVD method is used to form SiH ₄ + NH.
_An antireflection film was formed using a mixed gas of ₃ or a mixed gas of SiH ₂ Cl ₂ + NH ₃ .

Embodiment 15 In this embodiment, the same as the embodiment 1 to the embodiment 7 shown in FIG.
The _x N _y film, except that to form an antireflection film was formed by the following method, in the same manner as those in Example, was formed a fine pattern on a semiconductor device.

That is, in this embodiment, a parallel plate type plasma CVD method, an ECR plasma CVD method, or a bias ECR plasma CVD method is used to form SiH ₄ + O _2.
An anti-reflection film was formed using a mixed gas or a mixed gas of SiH ₂ C ₁₂ + NH _{3 and} Ar as a buffer gas.

[0110]

As described above, according to the present invention, even on an undersubstrate having a plurality of regions having steps and having different optical conditions, shorter than the i-line (365 nm). A fine resist pattern can be satisfactorily and stably formed by one exposure using light of a wavelength, for example, i-line, KrF, or ArF excimer laser as a light source.

The method for producing a fine pattern according to the present invention comprises:
In particular, it can be suitably used for a method for manufacturing a semiconductor device having a fine pattern.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing light interference in a resist film.

FIG. 2 is a diagram showing a standing wave effect on a silicon substrate.

FIG. 3 is a diagram showing a standing wave effect on aluminum silicide.

FIG. 4 is a diagram illustrating a standing wave effect on tungsten silicide.

FIG. 5 is a diagram for estimating the effect of a step on the standing wave effect.

FIG. 6 is a graph showing a relationship between a variation in the amount of absorbed light and a variation in pattern dimension.

FIG. 7 is a cross-sectional view showing a problem in forming a fine pattern on a base substrate in which a plurality of regions having different reflectivities are formed.

FIG. 8 is a graph showing that when the reflectance of the base substrate is different, the absorption amount of the resist is different.

FIG. 9 is a diagram showing a standing wave effect on a silicon substrate.

FIG. 10 is a diagram showing contour lines of the amount of absorbed light when the optical constants n and k are changed while the thickness of the antireflection film is fixed.

FIG. 11 is a diagram showing contour lines of the amount of absorbed light similar to FIG. 10 for other different resist film thicknesses.

FIG. 12 is a diagram showing contour lines of the amount of absorbed light similar to FIG. 10 for other different resist film thicknesses.

FIG. 13 is a diagram showing contour lines of the amount of absorbed light similar to FIG. 10 for other different resist film thicknesses.

FIG. 14 is a graph illustrating the relationship between the manufacturing conditions and the Si _x
O is a graph showing changes in optical constants of _y N _z.

FIG. 15 is a cross-sectional view when a fine pattern is formed on a transparent insulating film of a semiconductor device.

FIG. 16 is a diagram showing a standing wave effect when a polysilicon film is formed on a silicon substrate.

FIG. 17 is a diagram showing a standing wave effect when a polysilicon film is formed on tungsten silicide.

Figure 18 is a polysilicon film is formed on a silicon substrate or tungsten silicide, Si _X thereon
9 is a graph showing a reduction in a standing wave effect when an O _y N _z film is formed.

FIG. 19 is a diagram showing a standing wave effect after a titanium-based film is formed on a silicon substrate.

FIG. 20 is a diagram showing a standing wave effect after a titanium-based film is formed on tungsten silicide.

FIG. 21 is a diagram showing a standing wave effect after a tungsten silicide film is formed on a silicon substrate.

FIG. 22 is a diagram showing a standing wave effect after a tungsten silicide film is formed on tungsten silicide.

FIGS. 23A to 23E are main-portion cross-sectional views showing a manufacturing process of the semiconductor device according to the embodiment of the present invention.

24A to 24E are main-portion cross-sectional views showing a process of manufacturing a semiconductor device according to another embodiment of the present invention.

FIG. 25 (F) is a fragmentary cross-sectional view showing a step that follows the step shown in FIG. 24 (E).

[Explanation of symbols]

 Reference Signs List 20 semiconductor substrate 22 polysilicon film 24 tungsten silicide film 25 base substrate 26 transparent insulating film 28 resist film 32 high absorption film 34 antireflection film 42a, 42b contact holes 44a, 44b conductive plug layer

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/027

Claims (2)

(57) [Claims] A resist film having a predetermined pattern is formed by a photolithography method on a film to be processed formed on a surface of a semiconductor substrate so that at least two regions having mutually different optical conditions are formed; A method of manufacturing a semiconductor device, comprising the step of etching using the resist as a mask and processing the film to be processed, wherein the wavelength of exposure light used in the photolithography step is formed on the film to be processed. A step of forming a high absorption film having high light absorption, a step of forming an anti-reflection film on the high absorption film, a step of forming a resist film on the anti-reflection film, and a photolithography method using the resist film. And processing the antireflection film and the high-absorbency film into a predetermined pattern using the resist film of the predetermined pattern as a mask. An etching process; and, after removing the resist film, etching the film to be processed using the antireflection film and the high-absorption layer having a predetermined pattern as a mask. Production method. 2. A resist film having a predetermined pattern is formed by a photolithography method on a film to be processed formed on a surface of a semiconductor substrate so that at least two regions having mutually different optical conditions are formed. A method of manufacturing a semiconductor device, comprising the step of etching using the resist as a mask and processing the film to be processed, wherein the wavelength of exposure light used in the photolithography step is formed on the film to be processed. A step of forming a high-absorbing film having a high light-absorbing property and made of any one of a high-melting-point metal, a high-melting-point metal compound, and a high-melting-point metal silicide; and forming an anti-reflection film on the high-absorbing film Performing a step of forming a resist film on the antireflection film; and processing the resist film into a predetermined pattern by a photolithography method. Using the resist film of the predetermined pattern as a mask, etching the antireflection film, the high absorption film and the film to be processed into a predetermined pattern, and forming a hole in the film to be processed; On the antireflection film,
Forming a base film made of any one of a high-melting-point metal, a high-melting-point metal compound, and a high-melting-point metal silicide; and burying a conductive plug layer in the hole in which the base film is formed. Forming, and thereafter, etching the upper part of the base film other than the inside of the hole, the antireflection film, the high absorption film, and the conductive plug layer by the whole surface etch back method. Manufacturing method of a semiconductor device.