JP3326943B2 - Semiconductor device manufacturing method and 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 of manufacturing a semiconductor device and a semiconductor device, and more particularly to a structure and a method of manufacturing a semiconductor device capable of forming a fine pattern satisfactorily and stably.

[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 photolithography technology used in the development of these devices, an exposure apparatus called a stepper (reduction projection exposure machine) using light of a single wavelength as an exposure light source is used.

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 multiple 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 resist film. 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 on the resist surface, absorption by the substrate, light emitted from the resist, and the like. Show. The amount of absorbed light is the energy that causes the resist to undergo a photoreaction.

FIG. 2 shows a result of forming a resist film (XP8843) on a silicon substrate and examining a change in the amount of absorbed light depending on the thickness of the resist film. As the exposure light, KrF of λ = 248 nm was assumed. In an actual device, as shown in FIG. 3, the substrate surface always has irregularities. For example, there is a protrusion In such as polysilicon. For this reason, when the resist film RP is applied, the thickness of the resist film 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 resist film thickness d _{PR1 in the} other portions.

As described above, the standing wave effect differs depending on the resist film thickness. Therefore, the change in the amount of light absorbed by the resist due to the influence of the standing wave effect also changes. Come. As a result, the dimensions of the resist pattern obtained after the exposure and the phenomenon differ 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 using a stepper with the same wavelength and the same numerical aperture.
This phenomenon is common to all types of resist.

The dimensional accuracy of a resist pattern in a photolithography process at the time of manufacturing a semiconductor device is generally ± 5%. In order to achieve the dimensional accuracy of ± 5%, it is essential to reduce the standing wave effect. FIG. 4 shows a dimensional change of the resist pattern (vertical axis) with respect to a change in the amount of absorbed light in the resist film (horizontal axis). As is apparent from FIG. 4, for example, in fabricating a device with a rule of 0.35 μm, the variation in the amount of light absorbed by the resist film is 6% in the range.
It is required that:

[0007]

In order to meet the above-mentioned demands, anti-reflection techniques are being actively studied in various fields. As a result, high melting point metal silicide (for example, W-Si), metal (for example, A1-Si), silicon-based material (for example, P
As an excellent anti-reflective material on poly-Si), Si
_{C, SiO x, Si x O} y N z, Si x N y is, by the present inventors, have been found.

At the time of device fabrication, it is essential to employ a self-aligned contact (SAC) method, especially for a device having a design rule of 0.35 μm or less. To use this technique, for example, an offset oxide film is formed on a gate electrode using W-Si, a photoresist layer is formed on the oxide film, and a semiconductor mask pattern is transferred to a resist. Using the resist as a mask, an offset oxide film, a refractory metal silicide (for example, W-Si), a silicon-based material (for example, P
A semiconductor device is manufactured by etching poly-Si).

[0009] Refractory metal silicide (for example, WS
i), when forming a semiconductor mask pattern on a silicon-based material (for example, Poly-Si),
iO _x, Si _x N _y, the Si _x O _y N _z film antireflection film composed of such as, be deposited in the lower part of the resist film,
It has been found by the present inventors that it is effective in forming a fine pattern.

[0010] _{However, SiO x, Si x N y} , Si x
The O _y N _z film is not a stoichiometrically stable film.
_{Therefore, SiO x, Si x N y} , on the antireflection film, such as Si _x O _y N _z film, when forming a film, such as offset oxide film, to form a fine pattern thereon, the offset oxide During film formation, if the film formation temperature is high,
The film quality of the anti-reflection film changes (optical conditions change), the anti-reflection effect is weakened, and it has been difficult to form a fine pattern stably. Therefore, some countermeasures are urgently needed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is intended to prevent the deterioration of an antireflection film having a stoichiometrically unstable bond and to form a structure of a semiconductor device capable of forming a good and stable fine pattern. It is an object of the present invention to provide a manufacturing method thereof.

[0012]

According to the present invention, there is provided:
An anti-reflection coating having a stoichiometrically unstable bond when a semiconductor device is manufactured using i-line (365 nm) or shorter wavelength light, for example, i-line, KrF, or ArF excimer laser as a light source. In order to prevent the deterioration of the antireflection film, a protective film that does not deteriorate the film quality of the antireflection film (suppresses the change in the optical conditions) is determined on the antireflection film, thereby forming a fine and stable fine pattern. it can.

In determining the antireflection film, the following means were used. (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 is 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, with reference to the drawings, the above-mentioned means (I) to determine 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. 5).

An anti-reflection film ARL is formed between the resist and the underlying substrate to change the thickness d _arl and the optical constant thereof to n.
_arl and k _arl . Focusing on the film thickness at a certain point (for example, the film thickness at which the standing wave effect is maximized) in FIG.
_When n _arl and k _arl are changed _{while arl} is fixed, the amount of light absorbed by the resist film at that point changes. When this changing trajectory, that is, the contour line of the absorbed light amount is obtained, FIG.
It becomes as shown in.

With respect to other different resist film thicknesses d _PR , at least at four locations at λ / 8n _PR intervals, based on at least the film thickness that maximizes or minimizes the standing wave effect.
7 to 9 corresponding to FIG. 6 are obtained (FIGS. 6 to 9 define the antireflection film thickness to 20 nm,
The resist film thickness was 985 nm, 1000 nm, 101
8 nm and 1035 nm are shown). The above corresponds to the above means (I).

The common area of each of the graphs in FIGS.
For a specific thickness of the anti-reflection film, an area where the amount of absorbed light in the resist film does not change even when the resist film thickness changes is shown. 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. To find a common area, for example, simply put each figure (graph)
This can be done by taking a common area (of course, it may be done by searching for a common area on 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. This allows
The conditions of the thickness d _{arl of the} antireflection film and the optical constants n _arl and k _arl that minimize the standing wave effect 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.

The antireflection film which can be suitably used in the method according to the present invention was examined by means of the above (I) to (IV). As a result, monocrystalline silicon, polycrystalline silicon, amorphous silicon, and doped polysilicon were examined. silicon-containing film or tungsten, an antireflection film formed highly reflective substrate such as a refractory metal silicide-based film such as tungsten silicide, etc., Si _X O _y N _z film or Si
_X N _y film was found to be particularly suitable.

That is, as an anti-reflection film on a highly reflective substrate such as a silicon-based film such as single crystal silicon, polycrystalline silicon, amorphous silicon, and doped polysilicon, or a high melting point metal silicide-based film such as tungsten or tungsten silicide. Is n = 1.7 to 2.4, k ≦
0.90 (preferably 0.1 ≦ k ≦ 0.6) inorganic film having optical constants of a, in particular, the Si _X O _y N _z film (may contain hydrogen H) or Si _X N _y film , 20-300n
It has been found that it is preferable to use a film having a thickness of m.

[0024] For example, Si _X O _y N _z film (may contain hydrogen _{H, Si X O y N z} : also referred to as H film)
As shown in FIGS. 10 (A) and 10 (B), for example, depending on the flow rate ratio of the silane-based gas, for example, the wavelength 2
In the wavelength band of 48 nm, the real part n of the refractive index has a constant value of about 2.1, and the imaginary part k of the refractive index is arbitrarily controlled by changing the flow rate ratio of the silane-based gas. Can be. Therefore, an antireflection film having an optical constant value required as an antireflection film for a specific base substrate can be easily formed.

For example, when a W-Si substrate is used as a base substrate, n = 2.12, k = 0.54, d = 2
A 9 nm anti-reflection coating is optimal and can minimize standing wave effects. When an A1-Si substrate is used as a base substrate, n = 2.09, k = 0.87,
An antireflection film with d = 24 nm is optimal and can minimize the standing wave effect. When a Si substrate is used as a base substrate, n = 2.0, k = 0.55, and d = 32.
An anti-reflection coating of nm is optimal and can minimize standing wave effects.

The Si _x O _y N _z of the conditions: H film,
FIGS. 11 and 12 show the results obtained by forming films on tungsten silicide, aluminum silicon, and single crystal silicon as antireflection films, respectively, and showing their standing wave effects as compared with the case where they were not used. As shown in FIG. As shown in FIGS. 11 to 13, the Si _x O
_y N _z: H film, by using as an antireflection film, it is possible to suppress the standing wave effect, it is possible to achieve the anti-reflection effect.

[0027] However, the Si _x O _y N _z: H film,
Although the optical constant can be freely set according to the manufacturing conditions, the film is stoichiometrically unstable. For example, F shown in FIG.
As is apparent from the T-IR spectrum analysis, Si _x O
_y N _z: when annealed H film after film formation, when the annealing temperature is more than _{500 ℃, Si x O y N} z:
It can be seen that the bonding state of the H film is different from the bonding state immediately after the film formation. Si _x O _y N _z: if the bonding state changes H film, the optical conditions of the film also will vary, there may not be able to maintain a good anti-reflection effect.

Therefore, in order to protect the stoichiometrically unstable antireflection film, it is conceivable to form a protective film on the antireflection film. However, it does not mean that any kind of protective film may be used. That is, the optical characteristics of the antireflection film must not be changed by the heat treatment during the formation of the protective film.

The following has been found from experiments by the present inventor. That, Si _x O _y N _z as an antireflection film: H
To not alter the binding state of the membrane, a stoichiometrically stable film on the membrane, Si _x O _y N _z: was deposited at a deposition temperature comparable temperatures below the H film protection It may be used as a film.

An oxide film having a thickness of about 80 to 200 nm is used as an interlayer film when the self-align contact technique is used. The real part of the optical constant of the film is n = 1.4 to
It is about 1.7. Therefore, Si _x O _y N _z: on H film, using the same deposition apparatus, at the same deposition temperature, for example, a silicon oxide film by plasma TEOS (P-TEOS) process to 30nm formed, thereafter, the interlayer 720 as membrane
If about 140nm silicon oxide film by TEOS (LP-TEOS) method at a deposition temperature of ° C., Si _x O
_y N _z: it is possible to prevent deterioration of the H film. By a silicon oxide film a silicon oxide film and a TEOS method by a plasma TEOS process, since optically almost equivalent, Si _x O _y N
_z : The antireflection effect of the H film is not impaired.

That is, a good and stable mask pattern can be formed by using a protective film for preventing deterioration of an antireflection film having a stoichiometrically unstable bond.
Thereby, the above object has been achieved, and the present invention has been completed.
In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention includes, on a base substrate, a step of forming an antireflection film having a stoichiometrically unstable bond containing silicon ,
On this anti-reflection film containing silicon , a film forming process is performed later.
That to deter a change in the optical conditions of the anti <br/> antireflection film having the stoichiometric labile bond by heating, the reaction
Anti-reflection that can be formed without changing the optical conditions of the anti-reflection film
A step of forming a protective film for thermal protection of the film, a step of forming a resist film on the protective film directly or through an interlayer film, and processing the resist film into a predetermined pattern by a photolithography method And a step of performing.

[0032] The antireflection film, Si _x O _y N _z (where real numbers x is not including 0, real y, including a 0, z is 0
Is preferable. Si _X O _y N _z film or Si _X N _y film as an antireflection film,
A film can be easily formed by various CVD methods using a gas system containing at least silicon. For example, these films are formed by a parallel plate type plasma CVD method, ECR plasma C
Using a VD method or a bias ECR plasma CVD method, a mixed gas of a silane-based gas and a gas containing oxygen and nitrogen (for example, SiH ₄ + O ₂ + N ₂ ) or a silane-based gas and nitrogen is used by using microwaves. A film can be formed using a mixed gas of a gas containing the compound (for example, SiH ₄ + N ₂ O). At that time, as a buffer gas,
Argon Ar gas or the like can be used.

The Si _x O _y N _z film or the Si _x N _y film as an antireflection film is formed by using CF ₄ ,
CHF ₃ , C ₂ F ₆ , C ₄ F ₈ , SF ₆ , S ₂ F ₂ , N
Etching can be easily performed by RIE using F ₃ -based gas as an etchant and adding Ar to increase ionicity. The RIE is performed under a pressure of about 2 Pa for 10
It is preferable to perform the process with a power of about 100 W.
The flow rate of the gas during RIE is not particularly limited,
Preferably it is 5 to 70 SCCM.

It is preferable that the protective film is made of a material having substantially the same optical characteristics as the interlayer film formed on the protective film, particularly, an inorganic material. The thickness of the protective film is 20 to 2
It is preferably about 00 nm. The protective film is preferably made of an inorganic film having a refractive index (n) at a wavelength of exposure light of 1.4 or more and 1.7 or less, and the interlayer film is preferably made of a silicon oxide film.

Preferably, the protective film is a film formed by a plasma TEOS method or an ozone TEOS method. It is preferable that the protective film is formed at a temperature equal to or lower than the film forming temperature of the antireflection film. Specifically, it is preferable that the protective film is formed at a temperature of 500 ° C. or lower.

It is desirable that the antireflection film and the protective film, or the antireflection film, the protective film and the interlayer film are formed by using the same film forming apparatus. The protective film is an insulating film,
This protective film can also serve as an interlayer film. In order to achieve the above object, a first semiconductor device according to the present invention comprises:
On the gate electrode of the MOS transistor, Si _x O _y N
_An antireflection film composed of _z (where x is a real number not including 0, y is a real number including 0, and z is a real number not including 0) is formed. A protection film for suppressing a change in optical conditions of the antireflection film is formed, and this protection film is at least a part of the offset oxide film of the gate electrode.

A second semiconductor device according to the present invention has a lower wiring layer, an interlayer insulating film, and an upper wiring layer, and has a lower wiring layer and an upper wiring layer through contact holes formed in the interlayer insulating film. DOO is a semiconductor device which is connected, on the surface of the lower wiring layer, Si _x O _y N _z (here, x is 0
, Y is a real number including 0, and z is a real number not including 0). An anti- reflection film is formed on the anti-reflection film. By heat treatment
What interlayer insulating film having a function of preventing a change in the optical conditions of the anti-reflection film are formed.

[0038]

EXAMPLES Examples of the present invention will be specifically described below. However, the present invention is not limited by the following examples, and can be variously modified within the scope of the present invention.

Example 1 In this example, the present invention was applied to a highly reflective substrate using i-line (365 nm) or shorter wavelength light, for example, i-line, KrF, ArF excimer laser as a light source. When forming a semiconductor mask pattern, in order to prevent deterioration of the antireflection film having a stoichiometrically unstable bond, by using a protective film on the antireflection film that does not change the quality of the antireflection film, This is an embodiment in which a good and stable mask pattern can be formed.

As shown in FIG. 15, the semiconductor manufacturing method of the present embodiment can be suitably used in a gate electrode forming step using a refractory metal silicide such as W, W-Si or the like. However, the concept of this embodiment can be suitably applied irrespective of the type of substrate, the type of resist, and the type of high reflection layer.

The embodiment shown in FIG. 15 will be described in detail. FIG. 15 shows a process of manufacturing a semiconductor device such as an SRAM. A gate electrode of an NMOS transistor and a gate electrode of a PMOS transistor are formed on a semiconductor substrate 2.

As the semiconductor substrate 2, for example, a silicon wafer is used. An element isolation region 4 is formed on the surface of the semiconductor substrate 2. The element isolation region 4 is formed by, for example, a LOCOS method, a trench element isolation method, or the like. After forming the element isolation region 4 on the surface of the semiconductor substrate, a gate insulating film 6 is formed on the surface of the semiconductor substrate 2. Gate insulating film 6 is formed by thermally oxidizing the surface of semiconductor substrate 2 and is made of, for example, silicon oxide.

Next, for example, C is deposited on the surface of the gate insulating film.
The polysilicon film 8 is formed by the VD method. On the surface of the polysilicon film 8, a tungsten silicide film 10 is formed by, for example, a CVD method. The polysilicon film 8 and the tungsten silicide film 10 are patterned by the method of the present embodiment described below, and become a gate electrode of a MOS transistor.

In this embodiment, in order to process the polysilicon film 8 and the tungsten silicide film 10 into a fine pattern, first, an antireflection film 12 is formed thereon. As the antireflection film 12, n = 1.7 to 2.4, k ≦ 0.
90 (preferably _{0.1 ≦ k ≦ 0.6) Si X} O y N z having optical constants of: H film is used in a film thickness of 20 to 300 nm.

The Si _x O _y N _z : H film can be easily formed by various CVD methods using a gas system containing at least silicon. For example, this 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 a microwave and a silane-based gas and a gas containing oxygen and nitrogen (for example, SiH ₄ + O ₂ + N ₂ ) or a gas containing silane-based gas and nitrogen (eg, SiH ₄ + N
_A film can be formed using a mixed gas of 2O). In this case, an argon Ar gas or the like can be used as a buffer gas. Si _X O _y N _z: temperature during the deposition of the H film is not particularly limited, for example 350
400 ° C.

Next, in this embodiment, the antireflection film 12
A protective film 14 is formed thereon. In this embodiment, the protective film 14 also serves as an offset oxide film, and its thickness is not particularly limited, but is, for example, 20 to 200 nm. Protective film 14 is stoichiometrically unstable Si _x O _y
This is a film for suppressing a change in optical conditions of the anti-reflection film 12 composed of an N _z : H film. For example, a silicon oxide film formed by a CVD method at a film formation temperature of 500 ° C. or less, plasma TEOS And a silicon oxide film formed by an ozone TEOS method. The antireflection film 12 and the protective film 14 can be formed using the same film forming apparatus.

Thereafter, in this embodiment, a resist film (not shown) is formed on the protective film 14 also serving as an offset oxide film by a spin coating method or the like, and the resist film is subjected to photolithography. As exposure light used for photolithography, i-line (365 nm) or light having a shorter wavelength, for example, i-line, KrF, or ArF excimer laser is used.

The standing wave effect due to the presence of the highly reflective tungsten silicide film 10 under the resist film is favorably suppressed by the antireflection film 12, and a fine pattern can be formed with high precision. It is. Further, the optical conditions of the antireflection film are optimized so as to suppress the standing wave effect, and the change in the optical conditions is suppressed by the protective film 14 also serving as the offset oxide film. A good fine pattern can be stably formed.

Thereafter, using this resist film as a mask,
If the offset oxide film and protective film 14, the antireflection film 12, the tungsten silicide film 10, and the polysilicon film 8 are sequentially etched, the state shown in FIG. 15 is obtained. As an antireflection film _{12 Si x O y N z:} H film, CHF ₃
, C ₄ F ₈ , CHF ₃ , S ₂ F _2, etc. can be easily etched by RIE with enhanced ionicity using an etchant as a gas containing at least fluorine.

Thereafter, in this embodiment, in order to form the source / drain regions having the LDD structure, ions are implanted into each of the NMOS transistor region and the PMOS transistor region to form a low-concentration impurity diffusion layer 16. After that, the protective film 14 is used as an offset oxide film,
An insulating sidewall is formed on both sides thereof, and ion implantation for forming a source / drain region is performed thereon, thereby forming a source / drain region having an LDD structure. After that, according to the normal SRAM manufacturing process,
A semiconductor device is formed.

In this embodiment, when a semiconductor device is manufactured using i-line (365 nm) or light having a wavelength shorter than that, for example, i-line, KrF, or ArF excimer laser as a light source, stoichiometric imbalance occurs. Antireflection film 12 having stable connection
By using the protective film 14 on the anti-reflection film 12 which does not alter the quality of the anti-reflection film 12, a stable fine pattern can be formed satisfactorily. Further, since the protective film 14 can be used as it is as an offset oxide film, the number of manufacturing steps does not increase.

The following experiment has revealed that the protective film 14 of this embodiment can suppress a change in the optical conditions of the antireflection film 12 having a stoichiometrically unstable bond. As shown in FIG. 16, first, on the tungsten silicide substrate _{18, Si x O y N z} : to H film 20. Si _x O _y N _z: H film 20 by using the bias ECR plasma CVD method, a microwave (2.45 GHz)
Was formed using a mixed gas of SiH ₄ + O ₂ + N ₂ and Ar as a buffer gas. The temperature during the film formation was 360 ° C. At the time of deposition Si _x O _y N _z: thickness of the H membrane 20 was 30 nm.

[0053] The Si _x O _y N _z: on the H film 20, in the same deposition apparatus, at a deposition temperature of 420 ° C., by a CVD method, a silicon oxide film 22 was 170nm deposited. The film structure of this multilayer film is converted into a spectroscopic ellipsometer (eg, SOP).
Table 1 shows the results of measurement using an ELI system manufactured by RA Company.

[0054]

[Table 1]

[0055] In Table 1, the concentration and the silicon oxide film 22 or Si _x O _y N _z: percentage of voids in the H film 20 or indicates the percentage of silicon oxide in the intermediate layer 24, dense enough is negative It shows that the film is a good film. The intermediate film 24, the silicon oxide film 22 and the Si _x O _y N _z: H film 2
This is a mixed film formed at the interface of No. 0. Also, the film thickness is
This is the film thickness measured after forming the multilayer film.

[0056] As shown in Table 1, Si _x O _y in the above conditions
N _z: on the H film 20, by forming the silicon oxide film 22, the intermediate layer 24 is hardly formed, Si _x O
_y N _z: quality of the H film 20 hardly changes, the optical condition is proved unchanged.

On the other hand, except that the silicon oxide film 22 shown in FIG. 16 was formed by the LP-TEOS method at 720 ° C.
When an experiment was performed in the same manner as described above, the results shown in Table 2 were obtained.

[0058]

[Table 2]

As shown in Table 2, when the silicon oxide film 22 was formed by the LP-TEOS method at 720 ° C., the intermediate film 24 (mixed film) was formed to about 32.2 nm, and Si _x
It has been found that the film quality of the O _y N _z : H film 20 changes significantly and the optical conditions change.

This is because the FT-IR shown in FIG.
Is intended also get the prediction from the results of spectral analysis, Si _x O _y N _z as an antireflection film: The protective film formed on the H film, it is formed at 500 ° C. below the temperature Is preferred. Embodiment 2 In this embodiment, as shown in FIGS. 17 and 18, the present invention is applied to a wiring structure in which a first wiring layer 30 and a second wiring layer 32 are connected through a contact hole.

In this embodiment, as shown in FIG.
On the interlayer insulating film 36, a conductive layer to be the first wiring layer 30 is formed. The conductive layer serving as the first wiring layer is not particularly limited, but is, for example, tungsten silicide. First, the antireflection film 38 according to the present embodiment is formed on the conductive layer serving as the first wiring layer 30.

As the antireflection film 38, n = 1.7 to
2.4, k ≦ 0.90 (preferably 0.1 ≦ k ≦ 0.
Si _X O _y N _z having optical constants of 6): H film, 20
It is used with a thickness of 300 nm. Si _X O _y N _z: H film, various CV using a gas system comprising at least silicon
The film can be easily formed by the method D. For example, this 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 a microwave and a silane-based gas and a gas containing oxygen and nitrogen (for example, SiH 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). In this case, an argon Ar gas or the like can be used as a buffer gas. Si
_X O _y N _z: temperature during the deposition of the H film is not particularly limited, for example 350 to 400 ° C..

Next, in this embodiment, the anti-reflection film 38 is used.
A protective film 40 is formed on the substrate. Although the thickness of the protective film 40 is not particularly limited, it is, for example, 20 to 200 nm. In the present embodiment, since the interlayer film 42 described later is formed thereon, even if it is as thin as about 20 to 50 nm. good. Protective film 40, stoichiometrically unstable Si _x O _y N
_z : a film for suppressing a change in optical conditions of the antireflection film 38 composed of an H film, for example, a silicon oxide film formed by a CVD method at a film formation temperature of 500 ° C. or less,
It is composed of a silicon oxide film formed by a plasma TEOS method or an ozone TEOS method. Anti-reflection film 3
8 and the protective film 40 can be formed using the same film forming apparatus.

Thereafter, in this embodiment, a resist film (not shown) is formed on the protective film 40 by a spin coating method or the like, and the resist film is subjected to photolithography. As exposure light used for photolithography,
i-line (365 nm) or shorter wavelength light, for example, i-line, KrF, ArF excimer laser is used.

The standing wave effect due to the presence of the conductive film serving as the first wiring layer 30 made of a highly reflective tungsten silicide film or the like under the resist film is favorably suppressed by the antireflection film 38. Thus, it is possible to form a fine pattern with high accuracy. Further, the optical conditions of the antireflection film are optimized so as to suppress the standing wave effect, and the change in the optical conditions is suppressed by the protective film 40. It can be formed stably.

Then, using this resist film as a mask,
If the protective film 40, the antireflection film 38, and the conductive layer to be the first wiring layer 30 are sequentially etched, the first wiring layer 30 processed into a predetermined fine pattern is obtained. After that, in the present embodiment, a second interlayer insulating film 42 is formed on the first interlayer insulating film 36 and the protective film 40. Second interlayer insulating film 4
2 is not particularly limited, but is preferably an inorganic film having substantially the same optical constants as the protective film 40.
It is composed of a silicon oxide film formed by the P-TEOS method. The thickness of the second interlayer insulating film 42 is not particularly limited, but is, for example, about 80 to 200 nm.

Next, in this embodiment, a resist film 44 is formed on the second interlayer insulating film 42 by a spin coating method or the like, and the resist film 44 is subjected to photolithography. As exposure light used for photolithography,
i-line (365 nm) or shorter wavelength light, for example, i-line, KrF, ArF excimer laser is used.

On the lower layer side of the resist film 44, the first wiring layer 30 made of highly reflective tungsten silicide or the like is formed.
The standing wave effect due to the presence of the slab is well suppressed by the antireflection film 38, and the fine pattern 46 can be formed with high accuracy. Further, the optical conditions of the antireflection film 38 are optimized so as to suppress the standing wave effect.
Since the change in the optical conditions is suppressed by the protective film 40, even if the second interlayer insulating film 42 is formed under the condition of 500 ° C. or more, a good fine pattern 46 is stably formed on the resist film 44. Can be formed.

Then, using this resist film 44 as a mask, as shown in FIG. 18, the second interlayer insulating film 42, the protective film 40 and the antireflection film 38 are sequentially etched to form the fine pattern contact hole 34 with high precision. Formed. Thereafter, the second wiring layer 32 is formed so as to enter the contact hole 34, and the second wiring layer 32 and the first wiring layer 30 are connected.

In this embodiment, when a semiconductor device is manufactured using i-ray (365 nm) or light having a wavelength shorter than that, for example, i-ray, KrF, or ArF excimer laser as a light source, stoichiometry is not sufficient. Antireflection film 38 having stable connection
By using the protective film 40 which does not change the quality of the anti-reflection film 38 on the anti-reflection film 38, a stable fine pattern can be formed satisfactorily.

Further, by using the protective film 40 of this embodiment, even if the interlayer insulating film 42 is formed thereon at a temperature of 500 ° C. or more, the reflective film having a stoichiometrically unstable bond is formed. The following experiment has revealed that the change in the optical conditions of the prevention film 38 can be suppressed.

As shown in FIG. 19, first, a Si _x film as an antireflection film is formed on a tungsten silicide substrate 48.
O _y N _z: to H film 50. Si _x O _y N _z: H film 50 by using the bias ECR plasma CVD method, a microwave _{(2.45GHz), SiH 4 + O} 2
A film was formed using a mixed gas of + N ₂ and Ar as a buffer gas. The temperature during the film formation was 360 ° C. At the time of deposition Si _x O _y N _z: thickness of the H membrane 50 was 30 nm.

[0073] The Si _x O _y N _z: on the H film 50, in the same deposition apparatus, at a deposition temperature of 360 ° C., plasma TE
By the OS method, a P-TEOS silicon oxide film 52 as a protective film was formed to a thickness of 30 nm. Thereafter, the LP-TEOS silicon oxide film 54 is deposited as an interlayer insulating film by a low-pressure (LP) TEOS method at a deposition temperature of 720 ° C.
nm.

Table 3 shows the results of measurement of the film structure of this multilayer film using a spectroscopic ellipsometer (for example, ELLA system manufactured by SOPRA).

[0075]

[Table 3]

In Table 3, the concentration refers to the TEOS silicon oxide film 54, the P-TEOS silicon oxide film 52 or the Si _x
O _y N _z : ratio of voids in H film 50, or intermediate film 5
6 shows the ratio of P-TEOS silicon oxide, and a negative value indicates a denser film. An intermediate layer 56, P-TEOS silicon oxide film 52 and the Si _x O _y
N _z : a mixed film formed at the interface of the H film 50. The film thickness is a film thickness measured after the formation of the multilayer film.

[0077] As shown in Table 3, Si _x O _y in the above conditions
On the N _z : H film 50, a P-TEOS silicon oxide film 5 is formed.
By forming the 2 and TEOS silicon oxide film 54, the intermediate layer 56 not is hardly formed, Si _x O _y N _z: quality of the H film 50 hardly changes, the optical condition is proved unchanged .

[0078] Further, as shown in FIG. 19, under the conditions described above, on the tungsten silicide substrate 48, Si _x O _y N _z as an antireflection film: H film 50, P-TEOS silicon oxide film 52 and LP- TEOS silicon oxide film 5
Curve B in FIG. 20 shows the standing wave effect when the resist film 4 is formed and a resist film is mounted thereon. Further, Si _x O _y N _z as an antireflection film: the standing wave effect in the case of H film 50 is not provided is shown in curve B of Figure 20. As shown in the figure, it was confirmed that the standing wave effect could be considerably reduced.

In the simulation experiment shown in FIG. 20, KrF (wavelength λ = 248n) was used as the exposure light.
m) was used. XP8843 was used as the resist film, and its n _PR and k _PR were assumed to be 1.80 and 0.011, respectively. Further, n and k of the tungsten silicide substrate are 1.93 and 2.73, respectively.
Was assumed. _{Further, Si x O y N z:} n and k H film was assumed to respectively 2.12 and 0.54. Further, the LP-TEOS silicon oxide film and the P-TEOS
It was assumed that n and k of the silicon oxide film were 1.52 and 0, respectively.

Third Embodiment In the first embodiment, the offset oxide film shown in FIG. 15 is constituted by the protective film 14, but in the present embodiment, the offset oxide film has a laminated film structure of the protective film and the interlayer film. A semiconductor device was manufactured in the same manner as in Example 1 except for the configuration.

The protective film has a thickness of 20 to 100 nm, and is formed by a silicon oxide film, a plasma TEOS method or an ozone T
It was composed of a silicon oxide film or the like formed by the EOS method. Further, the interlayer film is preferably an inorganic film having a thickness of about 80 to 200 nm and having an optical constant substantially equal to that of the protective film, and is formed of, for example, a silicon oxide film formed by an LP-TEOS method. did.

[0082] EXAMPLE 4 In this example, described in the above Examples 1 to 3, Si _x O _y N _z as an antireflection film: except that the H film was formed by the following method, performed A semiconductor device was manufactured in the same manner as in the method of manufacturing a semiconductor device shown in Examples 1 to 3.

That is, in the present embodiment, the parallel plate type plasma CVD method, the ECR plasma CVD method, or the bias ECR plasma CVD method is used, and the microwave (2.45 GHz) is used to produce SiH ₄ + O ₂ + N ₂ . mixed gas, or using a mixed gas of _{SiH 4 + N 2 O, Si} x O y N z: to H film.

Embodiment 5 In this embodiment, the same as the embodiment 1 to embodiment 3 shown in FIG.
_x O _y N _z: H film, except that was formed by the following method, a semiconductor device was manufactured in the same manner as the manufacturing method of the semiconductor device shown in Examples 1-3.

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 form SiH ₄ + O ₂ + N ₂ . mixed gas or a gas mixture of SiH ₄ + N ₂ O using, using Ar as a buffer gas, Si _x O _y N _z:
An H film was formed.

Embodiment 6 In this embodiment, the same as the embodiment 1 to the embodiment 3 shown in FIG.
_x O _y N _z: H film, except that was formed by the following method, a semiconductor device was manufactured in the same manner as the manufacturing method of the semiconductor device shown in Examples 1-3.

That is, in this embodiment, parallel plate type plasma CVD, ECRCVD, or bias EC
Using R plasma CVD method, a gas mixture of _{SiH 4 + O 2 + N 2} , or using a mixed gas of _{SiH 4 + N 2 O, Si} x O y N z: to H film.

Embodiment 7 In this embodiment, the same as the embodiment 1 to the embodiment 3 shown in FIG.
_x O _y N _z: H film, except that was formed by the following method, a semiconductor device was manufactured in the same manner as the manufacturing method of the semiconductor device shown in Examples 1-3.

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.
+ N ₂ mixed gas or SiH ₄ + N ₂ O mixed gas, Ar _x buffer gas,
_{A yNz} : H film was formed.

[0090] In Example 8 This example, shown in Example 1~3, Si _x O _y N _z as an antireflection film: instead of an H film, using a Si _x N _y, it, the following A semiconductor device was manufactured in the same manner as in Examples 1 to 3, except that the film was formed by the technique.

That is, in this embodiment, the antireflection film is
Parallel plate plasma CVD, ECR plasma CVD
Or bias ECR plasma CVD using microwaves (2.45 GHz) to form SiH ₄
+ NH ₃ mixed gas or SiH ₂ Cl ₂ + NH ₃ mixed gas.

[0092] In Example 9 This example, shown in Example 1~3, Si _x O _y N _z as an antireflection film: instead of an H film, using a Si _x N _y, it, the following A semiconductor device was manufactured in the same manner as in Examples 1 to 3, except that the film was formed by the technique.

That is, in this embodiment, the anti-reflection film is
Parallel plate plasma CVD, ECR plasma CVD
Or bias ECR plasma CVD using microwaves (2.45 GHz) to form SiH ₄
+ O ₂ mixed gas or SiH ₂ Cl ₂ + NH ₃ mixed gas was used, and Ar was used as a buffer gas to form a film.

[0094] In Example 10 This example, shown in Example 1~3, Si _x O _y N _z as an antireflection film: instead of an H film, using a Si _x N _y, it, the following A semiconductor device was manufactured in the same manner as in Examples 1 to 3, except that the film was formed by the technique.

That is, in this embodiment, the antireflection film is
Parallel plate plasma CVD, ECR plasma CVD
Or a mixed gas of SiH ₄ + O ₂ or SiH ₂ Cl ₂ using a bias ECR plasma CVD method.
A film was formed using a + NH ₃ mixed gas.

[0096] In Example 11 This example, shown in Example 1~3, Si _x O _y N _z as an antireflection film: instead of an H film, using a Si _x N _y, it, the following A fine pattern was formed on a semiconductor device in the same manner as in Examples 1 to 3, except that a film was formed by a technique.

That is, in this embodiment, the antireflection film is
Parallel plate plasma CVD, ECR plasma CVD
Or a mixed gas of SiH ₄ + O ₂ or SiH ₂ Cl ₂ using a bias ECR plasma CVD method.
A film was formed using a mixed gas of + NH _{3 and} Ar as a buffer gas.

[0098]

As described above, according to the method of manufacturing a semiconductor device of the present invention, light having i-line (365 nm) or shorter wavelength, for example, i-line, KrF, ArF excimer laser is used as a light source. When using a semiconductor device, when using an antireflection film having a stoichiometrically unstable bond, by using a protective film on the antireflection film that does not alter the quality of the antireflection film. And a stable fine pattern can be formed satisfactorily.

[0099] That is, according to the present invention, has a step structure, and also a semiconductor mask pattern be one minute, antireflection effect and an inorganic mask function and an inorganic film having both, particularly Si _x O _y N _z : By using the H film, a stable mask pattern can be favorably formed on the wiring layer without increasing the number of steps.

[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 for estimating the effect of a step on a standing wave effect.

FIG. 4 is a graph showing a relationship between a variation in the amount of absorbed light and a variation in pattern dimension.

FIG. 5 is a diagram showing a standing wave effect on a silicon substrate.

FIG. 6 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. 7 is a diagram showing contour lines of the amount of absorbed light similar to FIG. 6 for other different resist film thicknesses.

FIG. 8 is a diagram showing contour lines of the amount of absorbed light similar to FIG. 6 for other different resist film thicknesses.

FIG. 9 is a diagram showing contour lines of the amount of absorbed light similar to FIG. 6 for other different resist film thicknesses.

[10] FIG. 10 (A), (B) is a graph showing changes in optical constants of the Si _x O _y N _z in the case of changing the manufacturing conditions.

Figure 11 is a tungsten silicide base substrate, Si _x O _y N _z: is a diagram showing an anti-reflection effect of the H film was deposited.

Figure 12 is Si _x O _y N _z on an aluminum silicon silicide substrate: is a diagram showing the reflection preventing effect in the case of H film.

[13] Figure 13 is a silicon substrate Si _x O _y N _z:
It is a figure which shows the antireflection effect at the time of forming a H film.

Figure 14 is Si _x O _y N _z: a FT-IR spectrum analysis diagram when annealed H film.

FIG. 15 is a fragmentary cross-sectional view showing the manufacturing process of the semiconductor device according to one embodiment of the present invention;

FIG. 16 is a schematic view showing an experimental example for confirming the effect of the protective film.

FIG. 17 is a schematic sectional view showing a manufacturing process of a semiconductor device according to another embodiment of the present invention.

FIG. 18 is a schematic cross-sectional view showing a step that follows the step shown in FIG. 17.

FIG. 19 is a schematic view showing an experimental example for confirming the effect of the protective film.

FIG. 20 is a graph showing a standing wave effect when an antireflection film and a protective film are stacked.

[Explanation of symbols]

 Reference Signs List 2 semiconductor substrate 4 element isolation region 6 gate insulating film 8 polysilicon film 10 tungsten silicide film 12 antireflection film 14 protective film (offset oxide film) 30 first wiring layer 32 second wiring layer 34 contact hole 36 first interlayer insulating film 38 anti-reflection film 40 protective film 42 second interlayer insulating film 44 resist film

Continuation of the front page (56) References JP-A-5-304090 (JP, A) JP-A-4-234109 (JP, A) JP-A-5-299338 (JP, A) JP-A-2-8852 (JP) JP-A-1-253256 (JP, A) JP-A-1-241125 (JP, A) JP-A-2-148731 (JP, A) JP-A-5-226652 (JP, A) 61-99331 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7/11 H01L 21/318

Claims (11)

(57) [Claims] 1. A method for manufacturing a semiconductor device, comprising: forming a resist film having a predetermined pattern on a base substrate by a photolithography method; performing etching using the resist film as a mask; and processing the base substrate. A step of forming an antireflection film having a stoichiometrically unstable bond containing silicon on the base substrate, and a later film forming step on this antireflection film containing silicon .
That to deter a change in the optical conditions of the anti <br/> antireflection film having the stoichiometric labile bond by heating, the reaction
Anti-reflection that can be formed without changing the optical conditions of the anti-reflection film
A step of forming a protective film for thermally protecting the film; a step of forming a resist film on the protective film directly or through an interlayer film; and processing the resist film into a predetermined pattern by photolithography. A method of manufacturing a semiconductor device, comprising: Wherein said anti-reflection film, Si _x O _y N _z (where real numbers x is not including 0, real y, including a 0, z is 0
2. The method of manufacturing a semiconductor device according to claim 1, wherein the method comprises: 3. The method of manufacturing a semiconductor device according to claim 1, wherein said protective film is made of a material having substantially the same optical characteristics as an interlayer film formed on said protective film. 4. The protective film is formed of an inorganic film having a refractive index (n) at a wavelength of exposure light of 1.4 or more and 1.7 or less, and the interlayer film is formed of a silicon oxide film. Item 4. The method for manufacturing a semiconductor device according to any one of Items 1 to 3. 5. The method for manufacturing a semiconductor device according to claim 1, wherein said protective film is a film formed by a plasma TEOS method. 6. The method according to claim 1, wherein the protective film is formed at a temperature equal to or lower than a film forming temperature of the antireflection film. 7. The method of manufacturing a semiconductor device according to claim 1, wherein said protective film is an insulating film, and said protective film also serves as an interlayer film. 8. A semiconductor device MOS transistor is formed on the gate electrode of the MOS transistor, Si _x O _y N
_z (where real numbers x is not including 0, y is a real number including 0, z is a real number not including 0) Yes with antireflection film deposition composed of, on the antireflective film, the Anti-reflective coating
A protective film for suppressing a change in the optical conditions of the antireflection film is formed by a heat treatment after the formation of the antireflection film.
A semiconductor device which is at least a part of an offset oxide film of a gate electrode. 9. A semiconductor device having a lower wiring layer, an interlayer insulating film, and an upper wiring layer, wherein the lower wiring layer and the upper wiring layer are connected through a contact hole formed in the interlayer insulating film. there are, on the surface of the lower wiring layer, Si _x O _y N _z (where real numbers x is not including 0, y is a real number including 0, z is a real number not including 0) antireflection film composed of Is formed on the anti-reflection film, and heat treatment is performed after the anti-reflection film is formed.
Therefore, a semiconductor device in which a protective film having a function of suppressing a change in optical conditions of the antireflection film is formed. 10. The semiconductor device according to claim 8, wherein the protective film is a film formed by a plasma TEOS method at a temperature equal to or lower than a film forming temperature of the antireflection film. 11. A plasma TEOS at a temperature equal to or lower than a film forming temperature of the antireflection film, wherein the protective film is an interlayer insulating film.
The semiconductor device according to claim 9, wherein the semiconductor device is a film formed by a method.