JPH0590225A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable a pattern to be formed with high precision by using a carbon film as a mask pattern during the dry-etching step. CONSTITUTION:After the formation of a carbon film 3, 250mum is thickness, by the sputtering step, a novolak base photoresist pattern 4 in specific pattern is formed on the carbon film 3 using the ordinary photolithgraphic technology. Next, the carbon film 3 is vertically processed using a resists pattern 4 (film thickness of 1.5mum) as a mask by the dry-etching technology using H2 gas to form the carbon film 3. Next, any residual resist 4 is removed by the down flow ashing step using CF4/O2 gas. At this time, the carbon film pattern 3 is left intact on a silicon oxide film 2. Through these procedures, the high temperature etching step can be made feasible.

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 more particularly to a method of manufacturing a semiconductor device with an improved dry etching process.

[0002]

2. Description of the Related Art In recent years, with the progress of semiconductor integrated circuits, the miniaturization of elements has been advancing, and the demand for higher precision of pattern dimensions is increasing. Generally, a semiconductor integrated circuit is
It is formed by laminating an insulating film such as silicon oxide having a predetermined pattern, a conductive film such as polycrystalline silicon, aluminum, copper, tungsten, or silicide on a semiconductor substrate such as a silicon substrate.

As a technique for processing these films into a desired pattern, a photosensitive resist is applied on the film, and then the resist is exposed to light and ultraviolet rays in a predetermined pattern to develop the resist. In the process, a lithography technique for forming a resist pattern by selectively removing the exposed or unexposed portion of the resist, a dry etching technique for etching the underlying film using the resist pattern as a mask, and A peeling technique for removing this resist pattern is used.

However, with the increase in the degree of integration of semiconductor elements, the minimum required pattern size is becoming smaller and the dimensional accuracy is becoming higher. Recently, it is necessary to form a fine pattern of 0.5 μm or less. Is becoming In order to deal with such a pattern of a fine area, various problems occur in the technique for forming the pattern described above, and it is necessary to greatly improve the technique.

These problems will be specifically described below.

Currently, using a fine resist pattern,
As one method of processing the underlying film, the RIE technique using plasma is widely used. In this method, for example, the substrate on which the film to be processed is deposited is housed in a vacuum container equipped with a pair of parallel plate electrodes, and the interior of the container is evacuated, and then a reactive gas containing a halogen atom or the like is added. Introduced,
This is a method in which a gas is made into plasma by discharge by applying high-frequency power, and a film to be processed is etched using the generated plasma.

According to this etching method, among various particles in plasma, ions are accelerated by the DC electric field generated in the ion sheath on the electrode surface, impact the film to be processed with a large amount of energy, and ion-enhancing chemical Cause a reaction. Therefore, the etching proceeds in the ion incident direction, and directional etching without undercut is possible.

However, since all the materials are excited or activated by this ion bombardment, the difference in reactivity peculiar to the substance is less likely to occur as compared with the etching using only radicals, and the etching rate ratio is generally different depending on the material. ,
That is, the selection ratio becomes small. For example, in etching Al, since the etching rate of the resist is high,
The pattern conversion difference is large, and it is difficult to form a pattern with high accuracy. Further, in the step-shaped portion, the film thickness of the resist becomes thin, so that there is a problem that the wiring portion is etched and the wiring is broken.

Further, in the etching of the silicon oxide film, the selection ratio of the silicon oxide film to the base material is small,
That is, silicon (Si) or aluminum (A
Since the etching rate of l) is high, the etching cannot be stopped with high accuracy when the surface of the base material is exposed. Therefore, when the contact holes having different depths are formed by etching, a considerable amount of silicon or aluminum, which is the base of the shallow holes, is etched, and there is a problem that the device characteristics are deteriorated.

Further, in such dry etching, since the moving directions of radicals are not aligned, the etching rate of the film to be etched is kept at a desired value in a moderate pressure range, and the film to be etched with respect to the mask is kept. If an attempt is made to increase the etching rate ratio (selectivity), undesired etching or deposition occurs on the side surface of the obtained pattern, making it impossible to form a highly accurate pattern.

Therefore, fundamentally, it is possible to realize anisotropic processing without side etching, increase the etching rate ratio (selectivity) of the film to be etched with respect to the mask, and increase the etching rate of the film to be etched. There was a trade-off with achieving it, and it was difficult to achieve all at the same time.

However, in recent years, by adding a mechanism for holding and controlling the wafer temperature at the time of etching at a low temperature of 0 ° C. or lower, the etching is performed at a high etching rate by the ion assist reaction in the depth direction, and the temperature is lowered in the lateral direction. The reaction made it possible to freeze the reaction and process it with high anisotropy. Further, since the reaction on the side wall of the pattern can be controlled by controlling the wafer temperature at a low temperature, it becomes possible to control the pattern shape. For example, in the etching of a silicon oxide film (SiO ₂ ), the dry process symposium (Dry Process Sympos)
ium p105, 1990), it is proposed that the silicon oxide film (SiO ₂ ) can be etched in a tapered shape within a range of appropriate pressure and substrate temperature.

However, with the increase in the degree of integration of semiconductor devices, the specifications required for contact holes are the reduction of the diameter of the holes and the increase of the depth of the holes. As the diameter of the hole becomes smaller and as the depth of the hole becomes deeper,
Since the side wall of the contact hole is tapered, the diameter of the bottom of the hole is smaller than the device specifications. The contact hole is a connection port that electrically connects the underlying silicon and the wiring on the silicon oxide film, and therefore metal such as aluminum or tungsten or polysilicon is embedded in the contact hole. Therefore, it is known that the larger the contact area between the buried metal or polysilicon and the underlying silicon, the better the electrical contact. Therefore, the etching shape of the contact hole must be vertical from the viewpoint of electrical characteristics or integration. In other words, the specifications required for processing contact holes used in high integration devices are:
It is necessary to have a high selection ratio to silicon (at least 20 or more) and to make the pattern shape vertical.

However, in the silicon oxide film, it is possible to make the pattern close to a vertical shape while maintaining a high selection ratio for silicon by raising the substrate temperature. However, when the substrate temperature becomes 160 ° C. or higher, Since the resist pattern is deformed by heat, the taper angle of the pattern side wall is limited to 83 degrees. Therefore, it is impossible to process a desired pattern with high accuracy. Therefore, Al, A using the ion milling method, etc.
In the processing of u and Pt, since high-energy particles collide with the substrate, the temperature of the substrate rises during etching, and the thermal deformation of the resist pattern due to it makes it difficult to perform highly accurate etching.

It has been reported that a silicon oxide film, a silicon nitride film or the like is used as a heat resistant mask and copper or the like is etched at a high temperature. In this case, copper is extremely likely to be oxidized at high temperature, so that a residue is generated, the shape is deteriorated, or copper is diffused into the mask material, and the electrical characteristics are deteriorated. Therefore, it is impossible to form a good wiring. Met.

Further, in etching tungsten or the like, since the etching rate is different between the peripheral portion and the central portion, when a region having a low etching rate is completely etched, overetching proceeds in a region having a high etching rate, There is a problem that the underlying material is etched in a considerable amount and the pattern shape is changed. Therefore, it has been impossible to process a desired pattern with high accuracy over the entire surface of the wafer as the diameter of the wafer increases.

Further, when an insulating film such as a silicon oxide film is used as a mask material, in the etching method using plasma, ions and electrons in the plasma are incident on the film to be etched. Charges are accumulated in the film (charge-up) by the ions and electrons incident on these films. For example, when electrons are obliquely incident on the mask pattern, they hit only one wall, so that the charges accumulated on the walls of the left and right mask patterns are different. As a result of this charge asymmetry, a new electric field generated in the lateral direction of the wall acts on the ions to bend the direction of motion and deteriorate the anisotropy of the pattern shape. Was difficult to etch.

In the case of etching a metal material, particularly AlSiCu, etc., if a resist film as an etching mask is peeled and then left to stand, corrosion of AlSiCu (corrosion) occurs, which causes a problem that device characteristics are deteriorated, resulting in high reliability. It was difficult to create a device with good properties.

[0019]

As described above, there have been the following problems when anisotropically processing a substrate to be processed by the reactive ion etching technique.

(1) It was impossible to process a silicon oxide film in a vertical shape while maintaining a high selection ratio with respect to silicon.

(2) The refractory metal film such as tungsten, the refractory metal silicide film, or the metal oxide has a large difference in etching rate between the central portion and the peripheral portion of the wafer as the diameter of the wafer becomes larger, and thus the high It was impossible to achieve uniformity.

(3) In reactive ion etching, since the dry etching selectivity of the etching mask to the material to be etched is small, the film thickness of the etching mask material during processing is severely reduced. Further, when the temperature of the substrate to be processed rises, the mask material deteriorates in heat resistance and the mask pattern is deteriorated, so that highly accurate processing cannot be performed.

(4) When copper or the like is etched at a high temperature, the copper is very likely to be oxidized at a high temperature, so that a residue is generated, the shape is deteriorated, or copper is diffused into the mask material, and the electrical characteristics are deteriorated. It was impossible to form good wiring.

(5) When an organic film is used as a mask material, since impurities such as fluorine (F) are contained in the film, these impurities are mixed in the plasma during the reactive ion etching. However, the object to be processed is contaminated. In particular, when the object to be processed is a metal material, there is a problem that corrosion (corrosion) induced by contamination occurs, and it is impossible to obtain a highly reliable device.

(6) When the mask material is organic or is an insulating film such as a silicon oxide film, it is accumulated in the mask due to the balance of ions and electrons incident on these films in plasma. The mask pattern is charged up depending on the amount of electric charge generated, and the incident direction of ions is bent by this, so that a fine pattern cannot be processed with high precision.

(7) Depending on the combination of the mask material, the material to be etched, and the material adjacent to the periphery,
It may be impossible to selectively remove the mask material without damaging the material to be etched or the material adjacent to the periphery.

The present invention has been made in consideration of the above circumstances, and when anisotropically etching a substrate to be processed in the dry etching technique, various problems (masking film and processed film) caused by the mask material or dry etching are caused. Etching selectivity ratio, selection ratio with the underlying material, charge-up, damage during mask peeling, heat resistance, contamination of the object to be processed, taper shape, etc.), and highly accurate pattern formation is possible. It is to provide a method for manufacturing a semiconductor device having high reliability.

[0028]

The essence of the present invention is that a carbon film is formed on a film to be processed as an etching mask for dry etching, and the film to be processed is dry-etched at a high temperature while heating the film to be processed. To do.

That is, according to the present invention (claim 1), a step of depositing a carbon film on a substrate to be processed, a step of forming an organic film pattern on the carbon film, and a step of using the organic film pattern as a mask A step of etching a carbon film to form a carbon film pattern, a step of removing the organic film pattern, an etching gas is introduced into a reaction region for accommodating the substrate, and a heating means provided on a support base of the substrate is used for treatment. An electric field is applied to the reaction region while heating the substrate to generate an electric discharge, and the formed plasma is used to anisotropically process the substrate to be processed using the carbon film pattern as a mask. A method of manufacturing a semiconductor device is provided.

Further, according to the present invention (claim 2), a step of depositing a carbon film on a silicon oxide film formed on a substrate, a step of forming an organic film pattern on the carbon film, and the organic film pattern. Using the as a mask to form a carbon film pattern by etching the carbon film, removing the organic film pattern, heating the substrate to 160 ° C. or higher, and applying a gas containing a fluorine atom and a carbon atom. The silicon oxide film is introduced anisotropically into the reaction region containing the substrate, an electric field is applied to the reaction region to generate a discharge, and the formed plasma is used to anisotropically process the silicon oxide film using the carbon film pattern as a mask. Provided is a method for manufacturing a semiconductor device, which comprises steps.

The present invention (claim 3) provides an etching gas containing a gas containing fluorine atoms and carbon atoms, or a mixed gas of a gas containing fluorine atoms and carbon atoms and carbon monoxide gas or hydrogen gas. 3. The method of manufacturing a semiconductor device according to claim 2, wherein the substrate is introduced into a reaction region that accommodates the substrate.

Further, according to the present invention (claim 4), a step of depositing a carbon film on a copper film formed on a substrate, a step of forming an organic film pattern on the carbon film, and a step of forming the organic film pattern A step of etching the carbon film using a mask to form a carbon film pattern, a step of removing the organic film pattern, and a reaction region in which the substrate is heated to about 150 ° C. or higher and an etching gas is contained in the substrate. And applying an electric field to the reaction region to generate an electric discharge, and using the formed plasma to anisotropically process the copper film using the carbon film pattern as a mask. A method of manufacturing a semiconductor device is provided.

In this case, the substrate is heated to 250 ° C. or higher,
An etching gas containing a chlorine atom and / or a bromine atom,
It is preferably introduced into the reaction region containing the substrate (claim 5).

Further, the present invention (claim 6) comprises a group consisting of a tungsten film, a nickel film, a titanium film, a tantalum oxide film, a strontium titanate film, an aluminum oxide film and an aluminum nitride film formed on a substrate. Forming a carbon film pattern by depositing a carbon film on a selected target film, forming an organic film pattern on the carbon film, and etching the carbon film using the organic film pattern as a mask A step of removing the organic film pattern,
And heating the substrate to 130 ° C. or higher, introducing an etching gas into a reaction region accommodating the substrate, applying an electric field to the reaction region to generate a discharge, and using the formed plasma to form the carbon film. A method of manufacturing a semiconductor device, comprising a step of anisotropically processing the film to be processed using a pattern as a mask.

In this case, it is preferable to introduce a gas containing at least one of chlorine atom, bromine atom and fluorine atom, or an etching gas composed of carbon monoxide gas into the reaction region containing the substrate.

It is preferable that the substrate is heated to 160 ° C. or higher in the first, fourth or sixth aspect (the eighth aspect).

Further, according to the present invention (claim 9), a step of depositing a carbon film on a target film containing aluminum as a main component formed on a substrate, and an organic film pattern is formed on the carbon film. A step of forming a carbon film pattern by etching the carbon film using the organic film pattern as a mask,
The step of removing the organic film pattern, introducing an etching gas containing chlorine atoms and / or bromine atoms into a reaction region accommodating the substrate, applying an electric field to the reaction region to generate discharge, and the plasma formed And a step of anisotropically processing the film to be processed by using the carbon film pattern as a mask, and a step of heating the substrate to 250 ° C. or higher. To do.

In addition, the present invention (claim 10) provides a step of forming a metal wiring containing aluminum as a main component formed on a substrate, a step of forming an insulating film on the metal wiring, and a step of forming an insulating film on the insulating film. A step of depositing a carbon film, a step of forming an organic film pattern on the carbon film, a step of etching the carbon film by using the organic film pattern as a mask to form a carbon film pattern, and a step of forming the organic film pattern. A step of removing, introducing an etching gas containing fluorine atoms into a reaction region accommodating the substrate, and applying an electric field to the reaction region to generate a discharge,
Manufacturing a semiconductor device, comprising: anisotropically processing the insulating film by using the formed plasma using the formed carbon film as a mask; and heating the substrate to 250 ° C. or higher. Provide a way.

In this case, in claim 9 or 10, it is preferable that the heating temperature of the substrate is 250 to 450 ° C (claim 11).

Further, the present invention (claim 12) includes the steps of forming an insulating film on a substrate, depositing a carbon film on the insulating film, and forming an organic film pattern on the carbon film. A step of etching the carbon film by using the organic film pattern as a mask to form a carbon film pattern, a step of removing the organic film pattern, and an etching gas containing fluorine atoms being introduced into a reaction region accommodating the substrate. A step of applying an electric field to the reaction region to generate an electric discharge and using the formed plasma to anisotropically process the insulating film by using the carbon film pattern as a mask; Provided is a method for manufacturing a semiconductor device, which comprises a step of heating.

In this case, the heating temperature of the substrate is 250-80.
It is preferably 0 ° C. (claim 13).

The preferred embodiments of the present invention are as follows.

(1) In the carbon film etching step,
As the etching gas, use an oxygen, nitrogen, halogen gas, an inert gas such as argon, krypton, or xenon, or hydrogen or a fluorocarbon gas.

(2) The carbon film should be formed by a sputtering method, a vacuum evaporation method or a CVD method.

(3) The substrate to be treated is placed in a vacuum container as a means for peeling off the resist pattern, and a mixed gas consisting of a gas containing at least a fluorine element and an oxygen gas is excited in a region different from the container, Using down-flow etching in which active species generated by excitation are supplied into a vacuum vessel.

[0046]

In the present invention, in order to investigate the dry etching characteristics when the carbon film is used as an etching mask, the substrate temperature is changed from room temperature to 600 ° C., and an etching apparatus capable of reactive ion etching is prepared.
In this etching apparatus, various gases are used as etching gas to change the substrate temperature, silicon oxide film,
The copper, tungsten or tantalum oxide film was etched, and its etching rate, processed shape and uniformity were investigated.

First, using the resist pattern as a mask, using a reactive gas containing at least C, F and H, such as CHF ₃ gas and CO gas, the substrate temperature is 50 ° C. under a predetermined pressure and high frequency power. To 300 ° C., the silicon oxide film was etched. As a result, when the substrate temperature is changed from 50 ° C to 160 ° C,
The taper angle of the side wall of the obtained silicon oxide film pattern was changed from 80 degrees to 83 degrees, and it was possible to make the processed shape close to vertical. However, if the substrate temperature is 160
When the temperature was raised to ℃ or higher, the resist pattern was deformed by heat, so that it was not possible to process a pattern having a desired pattern size with high accuracy.

Therefore, using a carbon film as an etching mask, the silicon oxide film was etched under the same conditions as above. As a result, it was found that the processed shape of the silicon oxide film pattern obtained at the substrate temperature of 50 ° C. changed to a taper angle of 80 ° on the side wall of the pattern and a taper angle of 83 ° at 170 ° C. Furthermore, at a substrate temperature of 260 ° C,
A silicon selection ratio of 20 and a taper angle of 90 degrees are obtained,
We succeeded in satisfying a large selection ratio to silicon and a processed shape at the same time. Further, it was found that although the substrate temperature was raised to 300 ° C. or higher, no deterioration or deformation due to heat was observed in the carbon film mask itself, and degassing was extremely small. Further, it was also found that the etching rate of the carbon film was extremely low.

That is, in this way, although the substrate temperature is raised above the temperature at which the resist is thermally deteriorated, and reactive ion etching has been carried out by controlling the substrate temperature, the substrate temperature is raised. It was discovered for the first time that a high-precision etching of a silicon oxide film becomes possible by using an appropriate etching gas and a carbon film mask at a high temperature.

Therefore, when the copper film was etched using chlorine gas in the same manner as described above, the substrate temperature was 2
It was found that the copper film was vertically etched at 50 ° C. or higher, and the etching rate of the carbon film was extremely low. That is, it can be seen that in normal dry etching, even with respect to a copper film or the like that produces only an etching product having a very low vapor pressure, it is possible to perform anisotropic processing with high accuracy without generating a residue.

Further, the tungsten and tantalum oxide films were etched by using a mixed gas of fluorine gas and chloride gas and appropriately changing the mixing ratio of this gas.
It has been found that the uniformity of the etching rate of the tungsten and tantalum oxide films improves as the substrate temperature rises, enabling highly accurate processing over the entire wafer surface.

Next, the present inventors performed etching of the AlSiCu film, the silicon oxide film having the AlSiCu film as the underlayer or the silicon oxide film having the Si substrate as the underlayer using the carbon film mask, and then the substrate temperature was changed. Raise
It was found that it is possible to remove contaminants or residues generated by etching when heat treatment is performed in vacuum or in a predetermined gas atmosphere. When heat treatment was performed in this manner, no corrosion or deterioration of electrical characteristics of the device was observed. That is, it is possible to form a highly reliable device in forming a wiring structure and a capacitor in a semiconductor integrated circuit.

[0053]

Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1] A first embodiment of the present invention is shown in FIG.
Will be explained.

First, as shown in FIG. 1A, a silicon oxide film 2 is formed on a silicon substrate 1 by thermal oxidation to 1.4 μm.
Deposited to a thickness of. Then, a carbon film 3 having a film thickness of 250 nm is formed by a sputtering method, and then a novolac-based photoresist pattern 4 (Tokyo Ohka: trade name TS, which has a desired pattern) of a desired pattern is formed on the carbon film 3 by an ordinary photolithography technique.
MR-CRBI) was formed. Then, a resist pattern 4 is formed by a dry etching technique using H ₂ gas.
The carbon film 3 was vertically processed using (film thickness 1.5 μm) as a mask to form a carbon film pattern 3.

Then, the remaining resist 4 was removed by downflow ashing using CF ₄ / O ₂ gas. Thereby, as shown in FIG. 1B, the carbon film pattern 3 was left on the silicon oxide film 2.

Then, as shown in FIG. 1C, the silicon oxide film 2 was etched by using a dry etching apparatus to form a silicon oxide film pattern 2a.

The process of FIG. 1C will be described in detail below.

First, a dry etching apparatus applied to this embodiment will be described with reference to FIG.

In the etching apparatus shown in FIG. 2, the etching chamber 20 includes a vacuum container 20a and a vacuum container 20a.
a for placing the substrate to be processed 21 placed in a
Electrode 22 and a blocking capacitor 29 for applying high frequency power of 13.56 MHz to the first electrode 22.
High-frequency power source 24 and the first electrode 22 connected via
And a heater 25 for controlling the substrate temperature of the substrate to be processed 21 to a desired temperature. Instead of the heater 25, heated silicon-based oil may be circulated in the first electrode to raise the temperature.

Further, in the etching chamber 20, a CHF ₃ gas supply line 28a and a carbon monoxide gas supply line 28 are provided.
b is connected, and CHF ₃ , CO is introduced into the vacuum container 20a from these supply lines 28a and 28b, and between the first electrode 22 and the inner wall (upper wall) of the vacuum container 20a which also serves as the second electrode. A high frequency voltage is applied.

Here, the vacuum container 20a is connected to the ground. The gas supply lines 28a and 28b are provided with valves 29a and 29b and flow rate adjusters 30a and 30b, respectively, so that the flow rate and gas pressure can be adjusted to desired values.

Further, samarium cobalt (Sm-) is provided above the upper wall which functions as the second electrode of the vacuum container 20a.
Co) are permanent magnets 26 are placed in series, the permanent magnet 26 is caused to rotate eccentrically about an axis of rotation 27 by a motor, 10 ^-3 Torr stand by the magnetic field of 50-500 gauss generated by the permanent magnets 26, It is configured so that high-density plasma can be generated and maintained even in a high vacuum of less than that. A large amount of ions are extracted from the high-density plasma generated in this manner, and the processed substrate 21 is irradiated with the ions and etched. Here, the magnetic field strength on the surface of the substrate 21 to be processed was 120 gauss.

Using the dry etching apparatus shown in FIG. 2, the silicon oxide film 2 was dry-etched as shown in FIG. 1 (c). As the etching gas,
A mixed gas of CHF ₃ and CO gas was used. The etching conditions are a CHF ₃ gas flow rate of 45 sccm and a CO gas flow rate of 15
The etching was performed at 5 sccm, a power of 2.6 W / cm ² , a pressure of 40 mTorr, and the substrate temperature was changed from 50 ° C. to 300 ° C.

FIG. 3 is a scanning electron microscope (SEM) showing the etching rate of the silicon oxide film 2, the etching selectivity to silicon, and the etching cross-sectional shape of the silicon oxide film pattern 2a when the substrate temperature was changed. It is a figure which shows the taper angle at the time of observing.

From FIG. 3, the taper angle of the pattern side wall is 80 ° at the substrate temperature of 50 ° C., the taper angle is 84 ° at the substrate temperature of 175 ° C., and the taper angle of 90 °, that is, the vertical shape at the substrate temperature of 260 ° C. It can be seen that it is. At a substrate temperature of 260 ° C. or higher, radicals in plasma accelerate etching of the silicon oxide film, resulting in undercuts under the carbon film mask.

The etching rate of the silicon oxide film linearly decreases as the substrate temperature rises. But,
Similarly, the etching rate of silicon decreases linearly as the substrate temperature rises from 50 ° C. to 170 ° C., so the selectivity does not change so much. But 170
It was found that in the temperature range of ℃ or higher, the amount of scattered matters from the carbon film pattern increases, so that the etching rate of silicon is further suppressed and the selectivity ratio increases in this temperature range.

Then, as shown in FIG. 1 (d), only the carbon film pattern 3 is removed by O ₂ plasma etching, and a highly accurate processed silicon oxide film having a side wall shape from a tapered shape to a vertical shape is formed. It was possible to obtain pattern 2a.

For comparison, when the silicon oxide film 2 was etched under exactly the same conditions as described above using the resist pattern as a mask, the taper angle of the side wall was changed from the substrate temperature of 50 ° C. to 160 ° C. 80 ° to 83
It was possible to approach the vertical up to °. However, when the substrate temperature is raised to 160 ° C. or higher, the resist pattern is deformed by heat, so that it is difficult to process a pattern having a desired pattern size with high accuracy.

Next, dry etching of the silicon oxide film was performed using only CHF ₃ gas as an etching gas without adding CO gas. That is, except that CO gas was not added and the flow rate of CHF ₃ gas was 200 sccm, the other conditions were exactly the same as those described above, and the power was 2.6 W / cm 2.
^2. Etching was performed at a pressure of 40 mTorr and a substrate temperature of 50 ° C. to 300 ° C.

As a result, in the case of CHF ₃ gas alone, 50
The taper angle is 74 ° at a substrate temperature of ℃, 84 ° at 125 ° C, and 9 at 170 ° C.
It became 0 °. In this way, CO is added to the CHF ₃ gas described above.
It was found that a vertical shape can be obtained at a lower temperature than when gas is added. However, at any temperature, the selection ratio to silicon was less than 10. When the total flow rate was kept constant at 200 sccm and the amount of CO gas added was increased to increase the selection ratio to silicon, the substrate temperature was 170 ° C.
At that time, CHF ₃ gas flow rate 70 sccm, CO gas flow rate 13
At 0 sccm, the selection ratio to silicon was 20. When the processed shape of the pattern at that time was observed by SEM, the taper angle was 84 °.

In addition to the substrate temperature described above, changes in pressure and power were also tried. However, in both cases, the taper angle and the selection ratio to silicon were only slightly affected.

From the above first embodiment, it was found that the substrate temperature must be controlled to 160 ° C. or more and less than 260 ° C. in order to achieve both the taper angle of 83 ° or more and the selection ratio to silicon of 20 or more. ..

Example 2 Next, the present invention will be described with reference to copper (Cu).
A second embodiment applied when a carbon film is used as an etching mask in the dry etching of 1. will be described. That is, in this example, since a halogen compound such as Cu has a low vapor pressure and a high energy impact such as ions and a high substrate temperature are required for etching, the carbon film pattern is used as an etching mask instead of an organic material such as a resist. It is an example used as.

[0075] First, as shown in FIG. 4 (a), to form an SiO ₂ film 42 on the Si substrate 41, the SiO ₂ film 42
A Cu film (400 nm) 43 was formed on the top by a sputtering method. After that, as shown in FIG.
Was formed to a thickness of 200 nm by the same sputtering method as above. At the same time, for comparison, a sample in which a silicon oxide film (SiO ₂ ) 44 'was formed to a thickness of 200 nm was also prepared by the sputtering method.

Next, as shown in FIG. 4C, a resist film 45 having a thickness of 1.6 μm is deposited on each of the carbon film 44 and the SiO ₂ film 44 ', and as shown in FIG. The resist pattern 45a was formed by exposing and developing the resist film 45 using the lithographic technique of. In the step shown in FIG. 4D, the carbon film 44
Alternatively, no elution and peeling of the SiO ₂ film 44 'occurred.

Next, as shown in FIG. 4E, the carbon film 44 was patterned by reactive ion etching using the resist pattern 45a as a mask. The dry etching device used is the reactive ion etching device on which the magnetron described above is mounted. The etching conditions were H ₂ gas flow rate of 100 sccm, pressure of 1.5 pa, high frequency power of 1.7 W / cm ² , and substrate temperature of 25 ° C.

As a result, a carbon film pattern 44a was formed as shown in FIG. 4 (e). The resist pattern 45a remains on the carbon film pattern 44a.
On the other hand, the SiO ₂ film 44 'was patterned using the resist pattern 45a as a mask in the same etching apparatus as described above. As for the patterning of the SiO ₂ film 44 ′, the etching was performed under the same conditions using H ₂ gas as in the above. As a result, a SiO ₂ film pattern 44a ′ was obtained as shown in FIG. 4 (e). This SiO ₂ film pattern 4
The resist pattern 45a also remains on 4a '.

Next, as shown in FIG. 4F, in order to remove the resist pattern 45a remaining on these thin films, the resist pattern 45a was stripped by an organic solution treatment. Thereby, the carbon film patterns 44a and S
Resist pattern 45a on iO ₂ film pattern 44a '
Were removed by etching, and an etching mask pattern consisting of the carbon film pattern 44a or the SiO ₂ film pattern 44a 'was formed.

Next, as shown in FIG. 4G, the Cu film 43 was etched using the carbon film pattern 44a or the SiO ₂ film pattern 44a 'as an etching mask. As the etching apparatus, the reactive ion etching apparatus on which the magnetron used in Example 1 was mounted was used. Cl ₂ (total flow rate 100 sccm) was used as an etching gas, and the substrate temperature was changed from 200 to 400 ° C. under a pressure of 0.5 Pa high frequency power of 1.7 W / cm ² .

First, when the etching rate of the Cu film was measured by changing the pressure and the substrate temperature without applying the high frequency power, as shown in FIG. 5, when the substrate temperature was less than 250 ° C., the pressure was changed. It was found that Cu was not etched at all. It was also found that the higher the pressure, the higher the etching rate of the Cu film. Further, the carbon film pattern was not etched at all under the above conditions, and was not deformed by heat.

Then, when high frequency power was applied and the Cu film was etched, it was found that the etching rate of the Cu film was extremely low when the substrate temperature was lower than 250 ° C.

Further, when the substrate temperature was raised to 300 ° C. or higher for etching, it was found that it was possible to etch Cu in a substantially vertical shape as shown in FIG. 4 (g). In addition, generation of residues and the like was not observed at all.

The etching rate of Cu at this time is 40
0 nm / min, etching rate of carbon film is 100 nm / min
, Cu and the carbon film have an etching selection ratio of 4. Therefore, even at a high temperature of 300 ° C. or higher, the carbon film is
Since it has heat resistance that it functions as a good etching mask for reactive ion etching using a halogen gas, it is possible to perform highly accurate etching even on a material such as Cu having a low vapor pressure of a halogen compound.

For comparison, a mask pattern made of a SiO ₂ film formed on a Cu film was etched under the above conditions, and at a substrate temperature of 300 ° C.
Evolution of residue was observed. This is due to the Si
It is speculated that since oxygen is generated from the O ₂ film, Cu etching products are generated, or the Cu etching surface is locally oxidized to form Cu oxide having an extremely low vapor pressure, which makes etching difficult. To be done.

On the other hand, when the carbon film mask is used, oxygen is not generated from the mask. Further, carbon or carbon chloride generated from the mask reacts with water and oxygen existing in the residual atmosphere, has an action of removing water and oxygen, and the Cu surface is hardly oxidized, so that no residue is generated.

Further, when a normal resist pattern was formed on the Cu film and etched by raising the substrate temperature, even if the resist pattern was subjected to a photo-curing treatment,
It was found that the resist pattern was deteriorated by heat when the substrate temperature was 150 ° C. or higher. On the other hand, when the carbon film pattern was used as a mask, deterioration of the pattern was not observed even at a substrate temperature of 400 ° C.

Then, as shown in FIG. 4 (h), in order to remove the carbon film pattern 44a from the Cu film 43, etching was carried out using an ordinary etching apparatus having parallel plate electrodes. As the etching gas, a gas containing at least fluorine atoms and containing no oxygen atoms, such as SF ₆ or NF ₃ , or H ₂ gas is used, and the pressure is 5
It was carried out at 0 mTorr, high frequency power of 150 W, and substrate temperature of 50 ° C.

After removing the carbon film pattern 44a, when the shape of the Cu film pattern 43a was observed by SEM, no deterioration of the pattern was observed, and high-precision etching was possible with a line and space of 0.4 μm dimension. It was

When a trialkylphosphine is used as an etching gas, the Cu film can be etched at a substrate temperature of 150 ° C. or higher.

[Third Embodiment] Next, a third embodiment in which the method of the present invention is applied to a tungsten pattern forming method will be described.

First, as in the second embodiment, as shown in FIG. 4A, a film thickness of 10 nm is formed on the silicon substrate 41 by thermal oxidation.
A silicon oxide (SiO ₂ ) film 42 was formed, and a 200 nm-thickness tungsten film (W) 43 was formed by the CVD method. Next, as shown in FIG. 4B, a carbon film (film thickness 100 nm) 44 was formed on this upper layer by a sputtering method.

Next, as shown in FIG. 4D, the carbon film 4
4 was coated with a photoresist, and as shown in FIG. 4C, a resist pattern 45a was formed by using an ordinary lithography technique. Next, as shown in FIG.
The carbon film 44 was processed into a vertical sidewall shape by a reactive ion etching method using H ₂ gas with the resist pattern 45a as a mask. Then, as shown in FIG. 4F, the resist pattern 45a was removed by downflow etching using CF ₄ / O ₂ gas to form a carbon film pattern 44a.

Next, as shown in FIG. 4G, the W film 4 is formed by using the carbon film pattern 44a as an etching mask.
3 was etched. Also in the etching of the W film 43, the dry etching apparatus described above was used.

The etching conditions were that the gas pressure in the reaction vessel was 50 mTorr, Cl ₂ gas or SF ₆ or a mixed gas of these was used as the etching gas, the mixing ratio of the mixed gas was changed, and under high frequency power of 150 W, Performed at room temperature. As a result, as shown in FIG. 6, when SF ₆ gas (100%) was used as the etching gas, the etching rate of the W film was 350 nm / min, whereas Cl ₂ gas (100%) was used. It was found that when used, the W film etch rate was reduced to 20 nm / min. At this time, the etching rate of the carbon film is SF ₆
For gas (100%), 10 nm / min, Cl ₂ gas (1
(00%), it was found to be extremely small at 5 nm / min. Further, when the distribution of the etching rate in the wafer surface was measured, with SF ₆ gas (100%), the etching rate in the peripheral portion of the wafer was high, and the uniformity was 75% (3σ /
x: average etching rate). Further, when the cross-sectional shape of the pattern obtained by etching was observed by SEM, SF ₆ gas (100
%), Undercut occurs in the W film 43 as shown in FIG. 7A, and conversely, under Cl ₂ gas (100%), as shown in FIG. It became a taper shape and could not be patterned with high precision.

Therefore, etching was carried out by raising the substrate temperature while appropriately changing the ratio of the mixed gas of SF ₆ gas and Cl ₂ gas. As a result, the substrate temperature is 130 ° C, C
When the gas partial pressures of l ₂ and SF ₆ were 7: 3, vertical patterning as shown in FIG. 7B was possible.

Further, as shown in FIG. 8, the etching rate of the W film increases as the substrate temperature rises, and it is 450 nm / min at 130 ° C., while the etching rate of the carbon film is 50 nm / min. Turned out to be extremely small,
It was revealed that the W film can be etched with a high selection ratio. Further, when the etching rate distribution in the wafer was measured, as shown in FIG. 8, a phenomenon that the etching uniformity was improved with the substrate temperature was found, and the uniformity (3σ / x) at the substrate temperature of 160 ° C. was 10%. %Met. This is because the concentration of tungsten chloride (WCl ₆ ) as an etching product is higher in the central portion of the wafer than in the peripheral portion of the wafer, and the etching rate is suppressed by redeposition of these products. .. Therefore, the etching rate in the central portion of the wafer is smaller than that in the peripheral portion, but by increasing the substrate temperature, the vapor pressure of these etching products (WCl ₆ ) and the like increases, and redeposition is less likely to occur. It is supposed to be. Further, when the substrate temperature was raised, the etching rate and the etching uniformity were improved, but an undercut occurred in the shape.

Therefore, in this region, CO gas was added and etching was performed. With addition of CO gas, W
Although the etching rates of the film and the carbon film gradually decreased, undercut was suppressed, and the shape could be controlled by the amount of CO added. It was also found that the etching uniformity did not change significantly by the addition of CO.

Therefore, in order to etch the W film or the like at a high etching rate with high uniformity within the wafer surface and with high accuracy, the substrate temperature is raised and a high carbon film mask is used. It has been found that etching with a selective ratio is extremely effective. In addition, the etching shape changes due to the rise of the substrate temperature. In this case,
The etching gas mixture ratio may be changed as appropriate, for example, C
It has been found that the addition of O gas enables highly accurate etching.

Finally, as shown in FIG. 4H, the carbon film pattern 44a was removed by etching with O ₂ gas in a barrel type plasma etching apparatus. After removing the carbon film pattern 44a, the W film pattern 43a is removed by S
When evaluated by EM, it was found that a vertical pattern having a line width of 0.4 μm was well formed over the entire wafer surface.

[Embodiment 4] Next, a fourth embodiment in which the present invention is applied to the formation of an Al alloy film pattern will be described.

FIG. 9 is a sectional view showing a process of forming an Al alloy film pattern. First, as shown in FIG.
The SiO ₂ film 52 is formed on the i-substrate 51, the SiO ₂
A Ti film and a TiN film (TiN / Ti) 5 are sequentially formed on the film 52.
3 and AlSiCu thin film 54 were deposited. Next, Al
The surface of the AlCuCu thin film 54 was modified by exposing the surface of the SiCu thin film 54 to plasma using oxygen gas. Then, as shown in FIG. 9B, a carbon film 55 (film thickness 200 nm) was formed on the thin film 54. Here, carbon film 5
No. 5 was deposited by a magnetron sputtering device.

Next, as shown in FIG. 9C, the carbon film 55 is formed.
Apply photoresist 56 (film thickness: 1.6 μm) on top,
The resist pattern 56 was formed by exposure and development using a normal lithography technique. In the step shown in FIG. 9C, an alkaline organic solvent is used as the developing solution, but since the carbon film 55 is formed on the base, AlSiCu is used.
No problem such as elution of the film 54 occurred.

After that, the carbon film 54 was patterned by reactive ion etching using the resist pattern 56 as a mask. The dry etching device used is the reactive ion etching device on which the magnetron described above is mounted. The etching condition is H ₂ gas flow rate 1
00sccm, pressure 1.5pa, high frequency power 1.7W / cm ² ,
The substrate temperature was 25 ° C. As a result, the carbon film pattern 5
5a was formed. Then, only the resist pattern 56 on the carbon film 55 was removed by a downflow ashing device using CF ₄ / O ₂ gas. As a result, as shown in FIG. 9D, the resist pattern 56 was entirely removed by etching, and an etching mask pattern made of the carbon film 55 was formed.

Next, as shown in FIG. 9E, the carbon film 5
The AlSiCu film 54 and the TiN / Ti film 53 were etched using 5a as an etching mask. This etching was performed using the above-mentioned magnetron-mounted dry etching apparatus. The etching condition is that the substrate temperature is 2
Hold at 5 ° C and use Cl ₂ and BCl ₃ as etching gases.
Was used, the etching pressure was 2.0 Pa, and the high frequency power was 0.8 W / cm ² .

At this time, the etching rate of the AlSiCu film 54 is about 350 nm / min, the etching rate of the TiN / Ti film 53 is about 150 nm / min, the etching rate of the carbon film is 20 nm / min, and AlSiCu and the carbon film are selected. The ratio was about 13. When the amount of residue generated on the wafer was observed under these conditions, no residue was found at all.
In addition, the shape of the etched AlSiCu film 54 is S
When observed by EM, an almost vertical sidewall-shaped pattern was obtained. After etching, the substrate was heated to 200 ° C. in an N ₂ atmosphere and post-treated for 2 minutes, and the sample was left in the air. The state of corrosion was evaluated by an optical microscope. However, no occurrence of corrosion was observed. Therefore, when the corrosion was evaluated by leaving it moisturized, the occurrence of corrosion was observed after 6 hours of humidification.

Therefore, when the substrate was heated to 350 ° C. after etching and post-treated for 2 minutes, no occurrence of corrosion was observed even after being left for 6 hours in humidification.

In order to investigate this factor, the TDS method (The The
Using rmal Desorption Spectra), that is, while heating the substrate temperature, degassing from the substrate was investigated by mass spectrometry. As a result, as shown in FIG. 10, it was found that Cl as an etching gas component and AlCl as an etching product are released as the substrate temperature rises. Therefore, it is assumed that the generation of corrosion due to humidification is caused by Cl and AlCl remaining after etching. In this way, by heating up to 450 ° C. by the TDS method, Cl and A
It was found that lCl was completely eliminated. Until now, when a resist film mask was used, the resist was 200 ° C.
At a substrate temperature of 200 ° C. or higher, thermal decomposition occurs from the vicinity, and a large amount of corrosion occurs because the decomposition product from the resist adheres to the AlSiCu film pattern.

However, by using a carbon film mask having heat resistance and extremely little degassing, it is possible to raise the substrate temperature to about 500 ° C. before removing the carbon film pattern. is there. In fact, even when the substrate temperature was raised to 1100 ° C., no degassing from the carbon film mask 55 was observed and no pattern deterioration due to thermal deformation was observed. However, it has been found that the heat treatment temperature is preferably 450 ° C. or lower because the AlSiCu film 54 is thermally deformed when the heat treatment is performed at a temperature higher than 450 ° C.

[Embodiment 5] Next, as a fifth embodiment of the present invention, in the step of forming a connecting portion (VIA contact) between an upper metal wiring and a lower metal wiring in a semiconductor device, the carbon film is used as an etching mask. An example applied as will be described with reference to FIG.

First, as shown in FIG. 11A, as the first metal wiring layer 63, for example, Al is formed on the first interlayer insulating film 62 deposited on the semiconductor substrate 61 on which the element is formed.
An alloy wiring film (Si: 1 wt%, Cu: 0.5 wt%) was deposited by sputtering to a film thickness of about 800 nm. Then, as a second interlayer insulating film, low temperature plasma CVD
TEOS (Tetraethoxysilane) with (vapor phase growth) equipment
A SiO ₂ film 64 was deposited using the above.

Then, as described in detail in Examples 1 to 4, S
A carbon film 60 is formed on the iO ₂ film 64 by sputtering.
deposited to a thickness of nm. A photoresist 65 was deposited on the carbon film 60, and the photoresist 65 was removed only by the ordinary photolithography process on the portion of the second interlayer insulating film 64 on the portion where the connection hole was to be formed.

Next, as shown in FIG. 11B, the carbon film 60 is anisotropically etched by the dry etching technique using H ₂ gas as described in detail in Example 2 using the photoresist 65 as a mask. The carbon film pattern 60a was formed. Then, as shown in FIG.
Similarly to the above, the resist film 65 was removed by etching by downflow ashing using CF ₄ / O ₂ gas.

Then, as shown in FIG. 11D, the first metal wiring 63 is exposed on the SiO ₂ film 64 by the reactive ion etching method using the dry etching apparatus used in the first to fourth embodiments. Is anisotropically etched to form the connection hole 66. In this etching, CHF ₃ gas was used as an etching gas, and the power was 1.4 W / c.
m ² , pressure 40 mTorr, gas flow 20 SCCM, substrate temperature 1
Performed at 50 ° C. When the etching rate of the SiO ₂ film was measured, the etching rate was 200 nm / min. When the shape at this time was observed by SEM, the shape of the side wall of the connection hole was almost vertical. However, by lowering the substrate temperature during etching to 100 ° C. or lower, the side wall of the connection hole of the SiO ₂ film 64 could be tapered.

When the side wall shape of the connection hole is vertical, a slight amount of deposit 68 is formed on the side surface of the side wall, but when the substrate temperature during etching is lowered and the side wall shape is tapered,
No deposit 68 was observed.

Then, as described in Example 2, the carbon film 60 was removed by O ₂ gas plasma etching. Then, as shown in FIG. 11E, the second metal wiring layer 67 (for example, AlSiCu) is formed on the entire surface by a sputtering method.
A film) was deposited and patterned to form a second metal wiring.

For comparison, a VIA contact was formed by using a resist as a conventional manufacturing method as an etching mask.

First, as shown in FIG. 12A, an AlSiCu film 73 as an Al alloy wiring is formed on the first interlayer insulating film 72 deposited on the semiconductor substrate 71 on which elements are formed.
(Si: 1 wt%, Cu: 0.5 wt%) 800 nm
Then, a SiO ₂ film 74 was deposited by a low temperature plasma CVD method as a second interlayer insulating film. The steps so far are exactly the same as those shown in FIG.

Next, a photoresist (1.6 μm thick) 75 is deposited on the SiO ₂ film 74, and only the resist 75 on the portion over the connection hole formation planned portion of the second interlayer insulating film 74 is formed by a normal photolithography process. Was removed. Then, as shown in FIG. 12B, the resist 75 is used as a mask to form the first SiO ₂ film 74 under the same conditions as described above.
Was anisotropically etched with CHF ₃ gas until the metal wiring 73 was exposed to form a connection hole 76.

At this time, when the substrate temperature was set to 130 ° C., the side wall of the connection hole of the SiO ₂ film 74 was slightly tapered. However, when the resist 75 was removed by normal O ₂ plasma ashing, as shown in FIG. 12B, a deposit 78 called a fence was formed on the side wall of the connection hole of the SiO ₂ film 74, as shown in FIG. It was found that a larger amount was formed as compared with the process using 60. However, lowering the substrate temperature during etching
When the side wall of the connection hole of the O ₂ film 74 was tapered, no deposit 78 was observed.

Next, as shown in FIG. 12C, a second metal wiring layer of AlS is formed on the entire surface by a sputtering method.
The iCu film 77 was deposited and patterned to form the second metal 77.

Next, the corrosion characteristics of the VIA contact formed by the above-described process using the carbon film as a mask (FIG. 11) and the process using the resist as a mask (FIG. 12) were evaluated. The evaluation was performed by leaving it in the air for a long time and examining the amount of corrosion generated in the chip by observing it with a microscope, as described in Example 4. As a result, a large amount of corrosion was observed in the process using the resist as a mask. on the other hand,
In the process using carbon as a mask, no corrosion was observed even if left for one week.

To investigate this factor, the wafer after the VIA contact opening was dipped in pure water and analyzed by ion chromatography. As a result, Cl and F were detected as impurities as shown in FIG. In particular, Cl using a resist as a mask compared to a carbon film mask,
It was found that the amount of F was high.

That is, as a cause of corrosion, if the first metal wiring layer 73 is left in the atmosphere after the opening of the connection hole and left in the atmosphere, impurities such as Cl and F existing on the surface of the first metal wiring layer 73 and moisture in the air cause HCl. , HF are formed. When HCl and HF are contained in water, water becomes an electrolyte and the following reaction easily occurs.

[0125] _{^{Al + 3Cl - → AlCl 3 +}} 3e - 2AlCl 3 + 6H 2 O → 2Al (OH) 3 + 6H + + 6Cl - When this reaction once starts, by Cl produced, corrosion AlSiCu constituting the first metal interconnection layer 73 Is considered to be promoted.

Thus, FIG. 11 (d) and FIG. 12 (b)
As shown in, at the time of connection opening by anisotropic etching,
Impurities contained in the photoresist 75 are released into the plasma and adhere to the side walls of the VIA opening. On the other hand, since the carbon film has a high purity, adhesion of impurities does not occur.

In addition, the etching is performed on the lower first metal wiring 7
3 reaches the surface of No. 3, the metal contained in the first metal wiring, the mask material (75 or 60) and the SiO ₂ film 74.
Atoms contained in are sputtered, and these substances adhere to the side surface of the connection hole 76 and the bottom surface of the connection hole 76. Since these deposits cannot be removed by O ₂ ashing, after ashing, for example, deposits (fences) on the side surface of the connection hole.
78 results. This causes an overhang shape when the upper second metal wiring layer 77 is sputtered in a later step, which causes a problem such as disconnection of wiring.

On the other hand, when the carbon film is used as the etching mask, compared with the case where the resist is used as the mask, the amount of decomposition products during the plasma etching is small, so that the deposits on the VIA side wall can be reduced. Is. Therefore, the problem of disconnection of the wiring described above does not occur. In the case of using the resist as a mask, Cl from resist, to impurities such as F occurs, after resist removal, easily by reaction with moisture in the air Cl ^-, F
^- ions are formed, corrosion is a large amount of generated.
On the other hand, in the carbon film mask, the amount of impurities in the VIA hole is extremely small because the resist is removed in advance. Therefore, corrosion hardly occurs.

Then, when the corrosion evaluation was carried out by leaving it in a humidified state, the occurrence of corrosion was observed by the standing in a humidified state for 6 hours as in Example 4. Therefore, various post-treatments were examined in order to suppress the occurrence of corrosion.

That is, after forming the contact hole, the substrate temperature was heated to 250 ° C. or higher and exposed to Si ₂ H ₆ or CO gas. When F or S remaining on the SiO ₂ surface or AlSiCu surface was changed to SiH As a result of mass spectrometric measurement, it was revealed that SiH _x F, COF, HF, HS, and COS are formed by reacting directly with H, SiH _x, Si, or CO generated by decomposition of ₄ . Therefore, SiO ₂ or AlSi formed after etching
The residue on the Cu surface can be removed by the above-mentioned substrate heating treatment and post-treatment by selecting an appropriate reactive gas.

After the above treatment, the corrosion was evaluated by the humidification evaluation, and no occurrence of corrosion was observed. In addition, in this process, it is necessary to heat the substrate to 250 ° C. or higher, and when a resist mask is used, degassing components from the resist adhere to the SiO ₂ or AlSiCu surface, so that complete removal is possible. Was impossible. Therefore, it was found that the process can be carried out by using a carbon film mask that has heat resistance and extremely less outgassing. Further, as shown in Example 4, when the substrate temperature exceeds 450 ° C., the underlying AlSiCu film is thermally deformed, so it has been found that the post-treatment temperature is preferably 250 ° C. or higher and 450 ° C. or lower.

Finally, as shown in FIG. 11E, the carbon film 60 was removed by ordinary O ₂ plasma ashing, and the electrical characteristics of the obtained wiring structure were evaluated. It was possible to create a reliable device.

<Sixth Embodiment> Next, as a sixth embodiment of the present invention, FIG. 14 shows an example in which a carbon film is applied as an etching mask in the step of opening a contact hole of a metal wiring in a semiconductor device. It will be explained using.

First, as shown in FIG. 14A, an impurity is introduced onto a Si substrate 81 having a plane orientation (100) to form a diffusion layer 82. Then, as shown in FIG.
After depositing a SiO ₂ film with a thickness of about 300 nm by the CVD method, BPSG (boron, phosphide silicate glass) with a thickness of about 600 nm is deposited on this SiO ₂ film, and the surface is flattened through a low temperature reflow process. Then, the interlayer insulating film 83 is formed.

Then, an opening is formed in the interlayer insulating film 83 as follows. In this step, FIG.
As shown in FIG. 5, a photoresist is deposited on the interlayer insulating film 83, and the resist patterned and opened by a normal photolithography technique is used as the etching mask 84 of the interlayer insulating film 83. As shown in the fifth embodiment, the interlayer insulating film 83 is opened by the same dry etching technique, as shown in FIGS.
By the process of (d), the interlayer insulating film 83 was opened using the carbon film as a mask 84.

Next, a mask 8 such as a resist and a carbon film
After removing 4, the metal film A for wiring is formed so as to fill the contact hole 86 in which the diffusion layer 82 is exposed in the opening.
The 1SiCu thin film 85 was deposited on the entire surface by the sputtering method.

When the characteristics of the contact hole thus formed were evaluated, when the contact was opened using the resist as a mask, the contact resistance increased, the junction was broken, the contact resistance was varied, and the AlSiCu wiring was corroded. It was Regarding corrosion, as shown in FIG. 13, an increase in the amount of corrosion was observed at the contact portion with the standing time. On the other hand, in the case of using the carbon film as a mask, deterioration such as increase in contact resistance and occurrence of corrosion were not observed.

This is because when a resist mask is used, impurities such as S, F, and Cl in the decomposed product from the resist generated during the reactive ion etching adhere to the contact holes, causing deterioration of the electrical characteristics. It is thought to be because.
On the other hand, when the carbon film is used, since the etching selectivity is high, the carbon film is less deteriorated during the etching. Further, when the metal adheres to the contact hole, since the adhered material from the mask is carbon, it is considered that there is no occurrence of corrosion or the like and no electrical characteristics are caused.

Further, when the carbon-containing halogen gas such as CHF ₃ is used as the etching gas as described above, the gas itself contains carbon, and the carbon from the mask material has particularly high electrical characteristics. It does not cause deterioration.

In this case as well, when an accelerated corrosion test by leaving it in a humidified state was conducted in the same manner as in Example 5, the occurrence of corrosion was observed even when the carbon film mask was used. Therefore, in the same manner as in Example 5, the substrate temperature is heated to 250 ° C. or higher, and Si ₂ H ₆ , CO, B ₂ H is added.
_When exposed to a gas such as _6, it was possible to remove the residue on the Si or SiO ₂ surface. Further, in this process, even if the substrate temperature was raised to about 1000 ° C., thermal deformation of the Si or SiO ₂ film did not occur. However, the impurity distribution in the diffusion layer and the like formed in the Si substrate changes at 800 ° C. Therefore, in order to obtain a reliable device, the heating temperature of the substrate is 80
It is preferably 0 ° C. or lower.

When the characteristics of the contact hole subjected to such post-treatment were evaluated, no corrosion was observed even in the accelerated corrosion test by leaving it in a humid condition. In addition, no deterioration in electrical characteristics such as increase in contact resistance was observed, and it was possible to manufacture a device with high reliability.

In the above Examples 1 to 6, a magnetron type reactive ion etching apparatus having a parallel plate was used as the etching apparatus. However, the ECR applying microwave and the reactivity using the discharge were used. An ion etching apparatus, a reactive ion etching apparatus in which a voltage is applied to a substrate to be etched under a discharge plasma generated by applying a microwave or an electron beam, or an ordinary parallel plate type etching apparatus is also used. Good.

Although the etching of the tungsten film is described in the fourth embodiment, nickel, titanium, tantalum, tantalum oxide, strontium titanate, aluminum oxide, aluminum nitride, etc., refractory metal, refractory metal silicidation, etc. It is also possible to use a carbon film as an etching mask for an object, a metal oxide, a metal nitride, etc., and increase the substrate temperature to etch these materials.

In addition, various modifications can be made without departing from the scope of the present invention.

[0145]

As described above, according to the method of the present invention, since the carbon film is used as the mask pattern in the dry etching, the temperature of the substrate to be processed is raised at the high temperature during the dry etching. It is possible to etch. Further, since the substrate to be processed is heat-treated at a high temperature after the etching and before the mask pattern is removed, it is possible to process the vertical sidewalls of silicon oxide and the like, and moreover, it is possible to process the base Si film with a large size. It becomes possible to obtain the selection ratio. Furthermore, even in a material such as copper having a very low vapor pressure of etching products, it is possible to form a pattern in which the side walls are vertical and there is no residue.

Also, tungsten, nickel, titanium,
Tantalum, tantalum oxide, strontium titanate,
Even materials such as aluminum oxide or aluminum nitride can be etched at a high etching rate with high accuracy and in-plane uniformity.

Further, since the high temperature heat treatment is performed after the etching using the halogen gas and before the mask pattern is peeled off, corrosion or deterioration of the electrical characteristics such as increase of contact resistance does not occur, and high temperature It is possible to create a highly reliable device.

[Brief description of drawings]

FIG. 1 is a sectional view showing a pattern forming step according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an etching apparatus used in the first embodiment.

FIG. 3 is a characteristic diagram showing a relationship between a substrate temperature, a taper angle of a pattern side wall, an etching rate, and a selection ratio.

FIG. 4 is a sectional view showing a pattern forming step according to a second embodiment of the present invention.

FIG. 5 is a characteristic diagram showing the relationship between substrate temperature and etching rate.

FIG. 6 is a characteristic diagram showing a relationship between a gas flow rate and an etching rate.

FIG. 7 is a cross-sectional view showing a change in the shape of the pattern side wall depending on the gas composition.

FIG. 8 is a characteristic diagram showing the relationship between substrate temperature and etching rate.

FIG. 9 is a sectional view showing a pattern forming step according to the fourth embodiment of the present invention.

FIG. 10 is a characteristic diagram showing a relationship between a substrate temperature and a degassing component.

FIG. 11 is a sectional view showing a pattern forming step according to the fourth embodiment of the present invention.

FIG. 12 is a sectional view showing a pattern forming step according to the fourth embodiment of the present invention.

FIG. 13 is a characteristic diagram showing the amounts of impurities in a case of using a carbon mask and a case of using a resist mask.

FIG. 14 is a sectional view showing a pattern forming step according to the sixth embodiment of the present invention.

[Explanation of symbols]

1, 41, 51, 61, 71, 81 ... Si substrate, 2, 4
2, 52, 62, 64, 72, 74, 83 ... SiO
₂ film, 3 ... 44, 55, 60, 84 ... Carbon film, 4, 4
5, 56, 65, 75 ... Photoresist, 43 ... Tungsten film, 53 ... TiN / Ti film, 54 ... AlSiCu
Thin film.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication H01L 21/302 F 7353-4M (72) Inventor Haruo Okano Komukai Toshiba Town, Kawasaki City, Kanagawa Prefecture No. 1 in Toshiba Research Institute, Inc. (72) Inventor, Kuki Hayashi No. 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa No. 1 in Toshiba Research Institute, Inc.

Claims (13)

[Claims] 1. A step of depositing a carbon film on a substrate to be processed,
A step of forming an organic film pattern on the carbon film, a step of etching the carbon film using the organic film pattern as a mask to form a carbon film pattern, a step of removing the organic film pattern, an etching gas The substrate is introduced into a reaction region, and an electric field is applied to the reaction region while heating the substrate to be processed by a heating means provided on the support base of the substrate to generate an electric discharge. A method of manufacturing a semiconductor device, comprising a step of anisotropically processing a substrate to be processed using a carbon film pattern as a mask. 2. A step of depositing a carbon film on a silicon oxide film formed on a substrate, a step of forming an organic film pattern on the carbon film, and the carbon film using the organic film pattern as a mask. A step of forming a carbon film pattern by etching, a step of removing the organic film pattern, and the substrate
The mixture is heated to 60 ° C. or higher, a gas containing fluorine atoms and carbon atoms is introduced into the reaction region containing the substrate, an electric field is applied to the reaction region to generate discharge, and the formed plasma is used to A method of manufacturing a semiconductor device, comprising a step of anisotropically processing the silicon oxide film using the carbon film pattern as a mask. 3. An etching gas containing a gas containing a fluorine atom and a carbon atom, or a mixed gas of a gas containing a fluorine atom and a carbon atom and a carbon monoxide gas or a hydrogen gas,
The method for manufacturing a semiconductor device according to claim 2, wherein the method is introduced into a reaction region that accommodates a substrate. 4. A step of depositing a carbon film on a copper film formed on a substrate, a step of forming an organic film pattern on the carbon film, and the etching of the carbon film using the organic film pattern as a mask. Forming a carbon film pattern, removing the organic film pattern, heating the substrate to about 150 ° C. or higher, introducing an etching gas into the reaction region containing the substrate, and applying an electric field to the reaction region. Is applied to generate a discharge, and the formed plasma is used to anisotropically process the copper film using the carbon film pattern as a mask. 5. The semiconductor device according to claim 4, wherein the substrate is heated to 250 ° C. or higher, and an etching gas containing chlorine atoms and / or bromine atoms is introduced into a reaction region containing the substrate. Production method. 6. A carbon to be processed film selected from the group consisting of a tungsten film, a nickel film, a titanium film, a tantalum oxide film, a strontium titanate film, an aluminum oxide film, and an aluminum nitride film formed on a substrate. A step of depositing a film, a step of forming an organic film pattern on the carbon film, a step of forming the carbon film pattern by etching the carbon film using the organic film pattern as a mask, and a step of removing the organic film pattern And a step of heating the substrate to 130 ° C. or higher, introducing an etching gas into a reaction region containing the substrate, applying an electric field to the reaction region to generate a discharge, and using the formed plasma, A method of manufacturing a semiconductor device, comprising a step of anisotropically processing the film to be processed using the carbon film pattern as a mask. 7. The method according to claim 6, wherein a gas containing at least one of a chlorine atom, a bromine atom and a fluorine atom, or an etching gas composed of carbon monoxide gas is introduced into the reaction region containing the substrate. Of manufacturing a semiconductor device of. 8. The method for manufacturing a semiconductor device according to claim 1, wherein the substrate is heated to 160 ° C. or higher. 9. A step of depositing a carbon film on a target film containing aluminum as a main component formed on a substrate, a step of forming an organic film pattern on the carbon film, and using the organic film pattern as a mask. A step of forming a carbon film pattern by etching the carbon film by using the step of removing the organic film pattern, introducing an etching gas containing a chlorine atom and / or a bromine atom into a reaction region containing the substrate, An electric field is applied to the reaction region to generate an electric discharge, and the formed film is used to anisotropically process the target film using the carbon film pattern as a mask, and the substrate is heated to 250 ° C. or higher. A method of manufacturing a semiconductor device, comprising: 10. A step of forming a metal wiring containing aluminum as a main component formed on a substrate, a step of forming an insulating film on the metal wiring, a step of depositing a carbon film on the insulating film, Forming an organic film pattern on the carbon film, etching the carbon film using the organic film pattern as a mask to form a carbon film pattern, removing the organic film pattern, etching containing fluorine atoms A gas is introduced into a reaction region that accommodates the substrate, an electric field is applied to the reaction region to generate a discharge, and the formed plasma is used to anisotropically form the insulating film using the carbon film pattern as a mask. A method of manufacturing a semiconductor device, comprising: a step of processing and a step of heating the substrate to 250 ° C. or higher. 11. The heating temperature of the substrate is 250 to 450.
11. The method for manufacturing a semiconductor device according to claim 9, wherein the temperature is C. 12. A step of forming an insulating film on a substrate, a step of depositing a carbon film on the insulating film, a step of forming an organic film pattern on the carbon film, using the organic film pattern as a mask A step of etching the carbon film to form a carbon film pattern, a step of removing the organic film pattern, an etching gas containing fluorine atoms is introduced into a reaction region containing the substrate, and an electric field is applied to the reaction region. Cause a discharge,
Manufacturing a semiconductor device, comprising: anisotropically processing the insulating film by using the formed plasma using the formed carbon film as a mask; and heating the substrate to 250 ° C. or higher. Method. 13. The heating temperature of the substrate is 250 to 800.
13. The method for manufacturing a semiconductor device according to claim 12, wherein the temperature is ° C.