WO1998006128A1

WO1998006128A1 - Dry etching method and device used for the same

Info

Publication number: WO1998006128A1
Application number: PCT/JP1996/003612
Authority: WO
Inventors: Masaru Izawa; Shinichi Tachi; Kazunori Tsujimoto; Tokuo Kure; Hironobu Kawahara; Ryouji Hamasaki; Yoshinao Kawasaki
Original assignee: Hitachi, Ltd.
Priority date: 1996-08-07
Filing date: 1996-12-11
Publication date: 1998-02-12
Also published as: WO1998006126A1

Abstract

An object is etched in an atmosphere in which the ratio of the number of oxygen atoms to that of carbon atoms is less than 10 while the deposition of a protective film and etching are controlled. Consequently, the side etching amount can be reduced at the time of forming wiring and finer wiring can be formed with higher dimensional accuracy even when the selection ratio to resist is raised.

Description

Description Dry etching method and its apparatus

Technical field

The present invention relates to a fine processing method and apparatus for a semiconductor device, and particularly to a dry etching method and apparatus for realizing high-precision processing.

Background art

One of the technologies for fine processing of semiconductor devices is dry etching technology. In dry etching, an etching gas is introduced into a vacuum vessel, a high-frequency bias or wave is applied to the gas, plasma is generated, and a pattern on the wafer is generated by active ions and ions generated in the plasma. To process. The active species formed in the plasma are adsorbed on the octagonal surface, and the etching is performed by introducing ions accelerated by a high-frequency bias into the active species adsorption surface. Since ions are accelerated only in the depth direction of the pattern, only the bottom surface of the pattern on the wafer is scraped, and the side surface of the pattern is not etched because there is no ion incidence. Thus, dry etching achieves anisotropic processing.

In the wiring processing of semiconductor devices made of aluminum (aluminum-copper-silicon (A1-Cu-Si) whose main component is AU), chlorine gas is used regardless of the plasma dissociation of the introduced gas, chlorine gas. Since A1 is etched by the mask, it is necessary to form a protective film so that the side of the pattern is not etched. This has been done by organic products evolving from it. During this wiring processing, the ions are also incident on the resist, so that the resist is also etched. The resist etching produces a resist product, which re-enters the wafer and adheres to the side surface of the Al-Cu-Si alloy pattern to form a protective film. This protective film enabled anisotropic processing of wiring materials.

Also, the processing accuracy must be within 10%, preferably ± 5% or less, of the mask width. For example, about 50ηηι the wiring member side surface scraping case (Sai de etching) is that Ji raw force within an acceptable range ffl machining accuracy if the wiring processing of 500 nm width ';, advances of 300Ti _m miniaturization When processing the width of wiring, the allowable amount of side etching (side etching) on the wiring material must be kept at least 30 nm or less. As a countermeasure against this side etching, if the resist film 15 is sufficiently higher than the thickness of the wiring pattern, the resist selectivity to resist is increased in order to increase the amount of resist products that serve as protective films. And the registration area has been widened.

On the other hand, there is Japanese Patent Publication No. 03-36300 as a method of performing etching by controlling the mixture ratio of carbon-containing gas and oxygen. The purpose of introducing oxygen is to efficiently generate chlorine from carbon tetrachloride in plasma. The oxygen / carbon ratio of the gas introduced is between 16 and 80%. In addition, the amount of oxygen (oxygen radical equivalent) generated from the inner wall of the etching apparatus is about 2 _SCC m, and even if carbon generated from the resist material is added, the oxygen / carbon ratio incident on the wafer is very good. More than%.

Also, in order to realize anisotropic etching in A The method of adding the gas is described in USP 4,618,398. Here, methane gas is added in an amount of 5 to 30% based on the total amount of etching gas chlorine and boron trichloride.

However, in the above-described method of forming a protective film so that the side surface of the pattern is not etched, the anisotropic processing of the wiring material can be performed by using the protective film, but the amount of generated resist products is controlled. However, the mechanism of protective film formation and the factor that inhibits it were not clear. Furthermore, it was unknown how much of the product of the registry would re-enter the wafer. In such a situation, since the protective film on the side face cannot be controlled, it has become difficult to obtain sufficient processing dimensional accuracy as the wiring pattern becomes finer.

In addition, in the method of suppressing the selectivity to the resist or increasing the resist area, when the wiring width is reduced, it is necessary to reduce the thickness of the resist from the viewpoint of the exposure technology, The thickness of the pattern cannot be reduced due to its electrical conductivity. Therefore, it is necessary to increase the resist selectivity. However, it is necessary to reduce the resist selectivity to prevent side etching. In other words, there is a trade-off between the resist selectivity and the side etching, making finer processing difficult. Furthermore, increasing the resist area not only limits the wiring structure, but also increases the integration density of the semiconductor device, which complicates the wiring structure and increases the register area more than necessary. Becomes difficult in practice.

Furthermore, anisotropic processing of fine patterns cannot be achieved by the method described in Japanese Patent Publication No. 3-36300. In addition, since carbon tetrachloride, which is subject to CFC regulations, is used as the halogenated carbon gas, Cannot be realized as a process.

In addition, in the methods of USP 4, 618, and 398, methane gas is added in an amount of 5% or more, and the deposition property is higher than that of halides. It will be.

An object of the present invention is to obtain a side surface protective film that does not depend on the amount of organic products generated from a resist, prevent the generation of foreign substances, improve the processing dimensional accuracy of wiring, and eliminate the trade-off. It is in. Disclosure of the invention

(Solution)

The above object is to supply oxygen and carbon to the object to be etched so that the ratio of the number of oxygen atoms to the number of carbon atoms becomes a finite value of 10% or less, and control the deposition and etching of the protective film to process the object. Achieved by etching things. Alternatively, the etching gas is achieved by adding to the etching gas 7 to 35% of the etching gas with a hydrocarbon haptic compound. In addition, as the halogenated compound, there may be mentioned, for example, a black mouth form. Furthermore, if the inner wall of the processing chamber is made of quartz,

(The quartz inner wall area X the quartz inner wall etching rate X the quartz inner wall oxygen density)

÷ (the area of the resist X the speed of the resist etching X the density of the resist carbon X 2.5

+ Supply of gas containing carbon)

Is achieved by introducing a halogen-substituted hydrocarbon and etching the metal film so that the value of is less than 0.1. (Action)

Conventionally, etching of an Al-Cu-Si alloy film has been performed with an etching gas mainly composed of chlorine gas and ions generated in plasma within a range of pressure 1Pa to 5Pa. Under these conditions, when a 6-inch wafer with a resist area of 50% is cut at a resist etching speed of 400 nm / min, the amount of generated resist products is at most about 5 sccm, and the amount of chlorine gas supplied Although it is only about 5% compared to about 100sccm, in reality this 5% of the resist product is effectively used for forming a protective film.

The resist product generated on the wafer has a short mean mean free path of 3 or less in the region of several Pa, and is not exhausted without colliding with other molecules. The direction of the movement to leave is lost. Therefore, W is incident on the wafer again. The re-injected resist product, once desorbed from the wafer, is not easily evacuated due to collisions with other molecules: the product concentration near the wafer is high. When the area where the product concentration is low is obtained from the diffusion equation, the vertical separation from the wafer reaches about the radius of the wafer. Such a region having no product concentration is called a double-assembly region, and is a region around the wafer, in which the distance from the wafer is equal to the radius of the wafer (the region not only in the vertical direction but also in the lateral direction of the wafer). Including). When a double-face region is formed on the wafer, the concentration of the resist product increases due to the stay of the resist product, so that the resist product enters the wafer many times. The probability of deposition on the side surface of the 確率 1-Cu-Si alloy film increases due to the incidence of the resist product many times.

Under the above etching conditions, the amount of generated resist products was about 5 sccm. However, the pressure of the resist product on the wafer is estimated to be about 0.13 Pa due to the stay effect. This amount is equivalent to the addition of about 13 sccm of the resist product from the outside to the etching cloth. In other words, the effect of forming a protective film on the resist product is about 2.5 times that of the gas introduced from the outside.

On the other hand, as for chlorine, the partial pressure of chlorine is reduced on the wafer because it is consumed on the wafer. Therefore, the amount of chlorine incident on the wafer is smaller than the supply amount. Specifically, the total pressure is lPa, the total flow rate is 100 sccm, of which the chlorine supply is 80 sccm, and the etching rate of the A1-Cu-Si alloy film etching of a 6-inch wafer is 800 nm / tn ir. Describes the case of performing in <>. If the etching reaction does not occur, the chlorine gas pressure is 0.8 Pa, but if the etching reaction occurs, the partial pressure of chlorine on the wafer is reduced to about 0.3 Pa.

As described above, the ratio of the resist product incident on the wafer to chlorine is about 50% due to the stay of the product and the consumption of chlorine in the two-face area formed up to the wafer radial distance. However, the resist product effectively acts on the formation of the protective film.

In addition, carbon-based protective films can be easily removed by oxygen contamination. That is, the incidence of oxygen impedes the formation of the deposited protective film. Oxygen is mainly generated by etching the material of the inner wall of the etching apparatus, for example, quartz. Thus, since oxygen has the effect of suppressing the formation of the protective film, it is necessary to reduce the amount of oxygen incident. However, in the anoxic condition, a certain amount is required because the deposits of the resist products form foreign matter and dust bases. However, since the effect of removing the protective film by the stay of the product and oxygen near the wafer was not known in the past, the formation of the protective film could not be controlled, and the resist selection ratio, the resist area, etc. There was a trade-off in between. In other words, when the resist area is small, or when the resist selectivity is high and the amount of generated resist products is small, the side surfaces of the Al-Cu-Si alloy are scraped off, and the mask pattern is faithfully adjusted. Reproduce Λ 1-Cu-Si alloy could not be machined. The resist product is mainly a carbon chloride-based compound and contains carbon, which is sedimentary. Therefore, in order to accurately anisotropically process the metal Cu-Si alloy film, it is necessary to control the amount of gas containing carbon including the resist product and the amount of oxygen incident on the wafer. It is important to control the carbon incidence ratio. By controlling the oxygen-Z carbon ratio, side etching can be reduced, and the trade-off between resist area and the trade-off between the resist area and the side etching is eliminated, increasing the resist selectivity. Wiring processing becomes possible.

Specific methods for increasing the carbon content include a method in which gas is introduced directly into the two-face area and a carbon ring product that is generated by installing a force ring around the wafer and etching the force bond. Can be introduced into the wafer, and a method of adding a gas so that the amount of gas containing carbon incident on the wafer becomes an appropriate amount. On the other hand, as a method of controlling the amount of oxygen, a method of covering the inner wall surface of the etching apparatus with a film that does not generate oxygen can be considered.

Figure 1 shows the relationship between the side-etching amount and the oxygen-carbon injection ratio. Reference numeral 102 denotes an area in which foreign matter dust is generated, and reference numeral 103 denotes a range of an oxygen / carbon incidence ratio within an allowable amount of deviation from a mask size. Sa The curve 101 indicating the amount of etching increases with an increase in the oxygen-Z carbon ratio. Therefore, in order to obtain sufficient processing accuracy, it is necessary to make the oxygen / carbon ratio smaller than a certain value, depending on the pattern size. For example, if the amount of side etching is suppressed to 15 nm or less in a pattern of 300 nm, the oxygen / carbon ratio is generally 10% or less. If the oxygen-Z carbon ratio is reduced, the amount of side etching is reduced, but if the oxygen-free state is approached, the accumulation of resist products and the like is not suppressed, so that they will accumulate in the etching device and become Causes problems such as dust. Since this problem depends on the device structure, the lower limit of the oxygen-carbon ratio differs from device to device. In particular, in an oxygen-free state, deposition cannot be suppressed, and consequently, the generation of foreign matters and the like becomes remarkable.

As described above, the reduction of the side etching is realized by reducing the oxygen / carbon ratio within a range in which the dust and the like are not generated.

(Effect)

According to the present invention, side etching in wiring can be reduced by setting the ratio of the number of oxygen atoms to the number of carbon atoms incident on the wafer to be processed to be 10% or less. As a result, finer wiring can be processed with high dimensional accuracy even if the selectivity to resist is increased. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a conceptual diagram showing the dependence of the amount of side etching on the carbon-oxygen ratio, FIG. 2 is a sectional view of a dry etching apparatus used in the present invention, FIG. 3 is a sectional view of a substrate before etching used in the embodiment, FIG. 4 is a cross-sectional view of the substrate after etching under the conventional conditions, and FIG. 5 shows the effect of the present invention. FIG. 6 is a cross-sectional view of the dry etching apparatus according to the present invention in the embodiment, and FIG. 7 is a cross-sectional view of the dry etching apparatus according to the present invention in the embodiment, showing that the side etching is reduced. FIG. 8 is a cross-sectional view of the semiconductor device structure before etching used in the embodiment, FIG. 9 is a cross-sectional view of the semiconductor device structure showing the effect of the present invention, and FIG. 10 is dry etching according to the present invention in the embodiment. FIG. 11 is a cross-sectional view of a dry etching apparatus according to the present invention in an embodiment, and FIG. 12 is a view showing a relationship between a resist surface ratio of the present invention and a necessary carbon gas addition amount. It is.

BEST MODE FOR CARRYING OUT THE INVENTION

(Example 1)

An embodiment according to the present invention will be described with reference to wiring processing using a microwave dry etching apparatus (FIG. 2) for generating high-density plasma using electron cyclotron resonance.

Fig. 3 shows the structure on a 6-inch silicon substrate, which is the object to be etched. Silicon dioxide (SiO ₂ ) 25, lower titanium nitride (TiN) film 24, ΛΙ-Cu-Si alloy film 23, upper TiN film 22, and mask pattern are formed on silicon substrate 26. The transferred resist mask 21 is formed. The pattern width of the resist mask is 300 nm, and the area of the resist is 50% of the silicon substrate. The substrate 6 is transferred to a processing table 5 (FIG. 2) of an etching apparatus, and as an etching gas, chlorine gas 80 sccm controlled by a flow rate controller 10 through a conductance valve 9, boron trichloride, The gas 20 seem is introduced into the vacuum processing chamber 1 from the gas-carrying population 11 and the etching is performed so that the total pressure is 1 Pa. A microwave is supplied from the microwave generator 2 through the waveguide, and a density plasma is generated in synergy with a magnetic field generated from the solenoid coil 4. Further, the chamber 1 is made of quartz 13, and the gas in the chamber 1 is sent to the exhaust pump 7 via the exhaust valve 8 and exhausted. The substrate temperature at the time of etching is 40 ° C, and the RF bias applied to the substrate is applied to the processing table 5 at 800 kHz and 70 W from the RF power supply 12. Etching is performed in the order of upper Πλ ', Λ1-Cu-Si alloy, and lower TiN. The etching speed of TiN is about 500nni / min, A1-Cu—Si alloy is about 800nm / min, and the resist (warp) 4 OOnm / m J n Fig. 4 shows a schematic diagram of the shape after etching. Since the consumption of chlorine is small and excessive chlorine is present in the processing chamber at the initial stage during the etching of the Al-Cu-Si alloy film, the side surface of the Al-Cu-Si alloy film 23 just below the upper TiN 22 However, it can be cut by about 60t m, and it is not possible to obtain sufficient machining accuracy. Further, the side surface of the Al—Cu—Si alloy film 23 is entirely cut off by about 40 nm. It is considered that the reason for the side surface being scraped off is that chlorine is excessively present in the processing chamber and the protective film on the side surface is insufficiently formed. Insufficient formation of the overcoat may be due to low resist products or the presence of oxygen which inhibits overcoat formation. As the ratio of oxygen concentration to resist product increases, the oxygen will remove the side protective film.

Since the protective film is formed from the resist product, it is important to estimate how much the resist product re-enters the Si substrate in controlling the protective film formation. The amount of resist product generated is estimated by the product of the density of the resist, the etching rate of the resist, and the area of the resist. The etching rate of the resist is 400 nm / min, and the area is 88 square centimeters (6 In the case of 50% of the silicon substrate, it is about 5 sccm. The resist product generated on the silicon substrate has a mean free path of about 3 mm at a pressure of lPa and the size of the processing chamber of the etching apparatus (for example, the length from the silicon substrate to the top of the vacuum processing chamber is about 20 cm). ) Because it is shorter, it collides with other molecules and its direction becomes random. For this reason, the product stays within the distance (two-face-to-face area) to the radius of the Si substrate immediately above the Si substrate. As a result, the product re-enters the Si substrate many times. The number of re-injections is estimated to be about 15 times from Monte Carlo calculations without considering the gas flow inside the vacuum processing chamber. The effect of the flow is as follows: From the gas flow calculation, the concentration decreases slightly more than about 10% as the total flow rate of gas increases by l OOsc cm. I do. Therefore, it is estimated that the number of re-injections is about 13 times at the total flow rate lOOsccm. When this number is multiplied by the amount of resist product generated, the product re-injection amount is estimated, and the pressure becomes about 0.13 Pa. This pressure is about 2.5 times the pressure expected from the amount of resist product generated. As described above, the phenomenon of the stay of the product on the Si substrate plays an important role in forming the protective film.

On the other hand, oxygen is generated from the inner wall of the quartz chamber 13 of the etching equipment, and the surface of the inner wall has a surface area of about 2900 square centimeters and can be cut off by about 15 nm per minute during plasma discharge. The volume is estimated at about 2 sccm. The amount of oxygen incident on the silicon substrate is about 0.02 Pa in terms of oxygen radical pressure. Here, the oxygen radical reduced pressure is a pressure when oxygen and oxygen radicals are all incident as oxygen radicals. The amount of oxygen incident on the resist product on the silicon substrate is about 15%.

We have mentioned that the side surfaces of Cu-Si can be cut off under the above-mentioned etching conditions. The resist product that forms the protective film is presumed to be a carbon chloride compound because the resist is an organic polymer. Therefore, as a gas to be added, a lOsccm chromium form was added to increase the number of carbon atoms incident on the silicon substrate. In this case, the pressure of the gas containing carbon on the wafer is about 0.23 Pa, which is the sum of the amount of the resist product and the form of the cross-hole. The ratio of the amount of oxygen incident to the amount of carbon-containing gas (carbon incident) is about 9%. When the same silicon substrate as described above is etched under these conditions, the side surface of the Au-Cu-Si alloy film 23 is etched without being scraped, as shown in FIG. When the addition amount of the mouth form is increased and 20 sccm is added, the pattern of the lower Tin becomes slightly thicker and the forward taper It becomes one shape. The oxygen / carbon incidence ratio at this time is 6%. Further, in a region where the amount of the addition of the cross-hole form is 35 sccm, that is, in a region where the ratio of the addition gas to the etching gas exceeds 35%, deposits accumulate inside the etching apparatus and become dust. Conversely, when the addition amount of black form is reduced to 5 sccm, the amount of abrasion on the side surface of Al-Cu-Si decreases less than before addition, and the force effect is small. The amount of abrasion on the side of the A1-Cu-Si alloy can be improved by adding more than 7 sccm of the aperture form. At 7 sccm, that is, when the ratio of the added gas to the etching gas is 7%, the ratio of the number of oxygen atoms to the number of carbon atoms incident on the substrate is about 10% .Especially, a good shape is obtained. The low dust generation is between 10 and 25 sccm, that is, the ratio of the additive gas to the etching gas is between 10% and 25%. The incidence ratio of oxygen at 25 sccm is 5%.

Next, when the resist area is about 30%, the amount of register products generated is reduced by about 40%. Need to increase. In this case, it is necessary to add more than 12 sccm.

If the output of the RF bias is lowered and the selectivity to the resist is raised, the amount of resist product generated decreases, so the amount of black form added must be increased. When the selectivity is doubled to about 4 with a resist area of 50%, the side etching is reduced by adding about 15 sccm of the cross-hole form, and the side etching is about the measurement limit with the addition of more than 20 sccm. become.

In general, the following equation shows the ratio of the number of oxygen atoms to the wafer and the number of carbon atoms incident on the wafer.By introducing a close-up form so that this value becomes 10% or less, a sufficient processed shape can be obtained. Can be Particularly desirable areas Is between 5 and 9%.

(Inner wall area X Inner wall etching speed X Inner wall oxygen density)

÷ (Regist area X resist etching rate X resist carbon density X 2.5 + supply of gas containing carbon) According to this equation, when the etching rate of the resist is reduced (to the resist selectivity) In this case, it is only necessary to increase the addition amount of the additional form of the form-hole form.

Next, 6-inch wafer one, 1 P a, C 1 Bruno C 1 ₃ a flow 1 0 0 sccm, in the case where the oxygen generation amount to zero by comprising a 2 scc ni, registry against registration be sampled area ratio The relationship between the product concentration and the area ratio of the register and the amount of the lowest carbon-containing gas added is shown in Fig. 2 and _r . However, if the area of the registry is less than about 80%, the carbon supplied from the registry power is not enough, and it is necessary to supply carbon.- The area of the registry is more than 80% Then, there is no need to lend carbon from a non-registry shack.

Chlorine and boron trichloride are used as the etching gas, and fluorine, chlorine or ethane, methane, propylene or butane, or ethane, methane, propylene or butane is used as the additive gas in addition to the crotch form. bromine substituents, or Cal borane bromide carbon is halogen substituents (CBr ,, CHBr _3, etc.) and chloride force Rubora emission compound _{_{(CC1 3 BC1 2, CHCl BCL}} ,, CC1: (BCU) CIIC1 (BC1 2 ) ₂ , BC1 (CHC1 ₂ ) _2, etc.) have the same effect.

The effect of the present invention is not limited to the above-described microwave etching apparatus. For example, other devices such as RIE, magnetron RIE, helicon resonant RIE, and inductively coupled RIE can achieve the same effect.

(Example 2)

FIG. 6 shows another embodiment of the dry etching equipment according to the present invention. In this system, an etching gas is introduced into the vacuum processing chamber 1, a high frequency of 2.45 GHz is generated in the microwave generator 2, and this high frequency is transported to the vacuum processing chamber 1 through the waveguide 3 to generate gas plasma. Let it. Two solenoid coils 4 for generating a magnetic field are arranged around the vacuum processing chamber for high-efficiency discharge, and the two coil currents are controlled so that the 875 Gauss magnetic field is almost directly above the processing table. A high-density plasma is generated using electron cyclotron resonance. The vacuum processing chamber 1 has a processing table 5 on which an object 6 (often a wafer) is placed and subjected to etching by gas plasma. The etching gas is introduced into the vacuum processing chamber 1 through the gas flow controller 10 and the gas inlet 11, and is exhausted out of the vacuum processing chamber 1 by the exhaust pump 7. The processing table 5 on which the workpiece is to be installed is provided with an RF power supply 12, and can apply an RF bias from 400 Hz to 13.56 MHz. Around the outer periphery of the processing base, the processing base is connected via a conductance valve 703 and a gas flow controller 702 so that gas can be efficiently introduced into the two-assembly area near the workpiece. A gas inlet 70 1 is provided.

The 12-inch silicon substrate is transported to this rice paddy. As shown in FIG. 3, the silicon substrate has a silicon dioxide film 25, a lower TiN film 24, an Al-Cu-Si alloy film 23, and an upper TiN film 2 on the substrate 26. 2 and a resist mask 21 onto which the mask pattern was transferred. The pattern width of the resist mask is 300 nm, and the area of the resist is 20% of the control board.

The processing table temperature is 50 ° C, the total pressure is 1 Pa, the RF power is 800 kHz, and the power is 120 W. 150 _sccm of chlorine gas, 50 sccm of boron _trichloride , 5 sccm of black mouth form from the upper gas inlet, and approximately 2 sccm of black mouth form from the gas inlet near the outer periphery of the processing board. Is etched.

The ratio of the number of oxygen atoms and the number of carbon atoms incident on the silicon substrate is about 7.5%, and the Al-Cu-Si alloy side surface hardly cuts or thickens (forward taper). In addition, there is no difference in the abrasion of the A] -Cu-Si side surfaces at the center and outside of the silicon substrate, and the pattern in the substrate is uniformly etched. On the other hand, when the form gas is not introduced from the periphery of the processing table, the re-injection of the resist product is large near the center of the silicon substrate and the number of re-injections is reduced on the outside by exhaust. However, it was difficult to process uniformly.

The effect of the present invention is not limited to the above-described microwave etching apparatus, and similar effects can be obtained with other apparatuses such as RIE, magnetron RIE, helicon resonance RIE, and inductively coupled RIE.

(Example 3)

Another embodiment of the dry etching apparatus according to the present invention is shown in FIG. In this system, an etching gas is introduced into the vacuum processing chamber 1, a high frequency of 2.45 GHz is generated in the microwave generator 2, and this high frequency is transported to the vacuum processing chamber 1 through the waveguide 3 to generate gas plasma. Let it. Two solenoid coils 4 for generating a magnetic field are placed around the vacuum processing chamber for high-efficiency discharge, and the two coil currents are controlled so that the 875-gauss magnetic field is almost directly above the processing table. High using electron cyclotron resonance Generate a density plasma. The vacuum processing chamber 1 has a processing table 5 on which an object 6 to be processed is installed, and is subjected to etching processing by gas plasma. The etching gas is introduced into the vacuum processing chamber 1 through the gas flow control device, and is exhausted out of the vacuum processing chamber 1 by the exhaust pump 7. The processing table 5 on which the object is to be installed is equipped with an RF power supply 12 and can apply an RF bias from 400 Hz to 13.56 MHz. A carbon ring 801 with a height of cm cm is installed near the outer periphery of the processing table in the near surf area.

The 12-inch silicon substrate is transported to this device. As shown in FIG. 3, the silicon substrate has a silicon oxide film 25, a lower iN film 24, an Al-Cu-Si alloy film 23, and an upper Ti. 2 and a resist mask 21 onto which the mask pattern has been transferred. The pattern width of the resist mask is 300 ntn, and the area of the resist is 20% of the silicon substrate.

The processing table temperature is 50 ° C, the total pressure is 1 Pa, the RI's temperature is 800 kHz, and the power is 120 W. The introduced silicon substrate is etched by introducing a 150 sccm salt gas, a 50 sccm boron trichloride, and a 4 scctn chlorophonolem through the upper gas inlet.

The oxygen-Z carbon ratio on the silicon substrate is about 7.5%, including the gas (approximately 3 sccm) generated when the carbon ring is chipped, and the side surface of the Al-Cu-Si alloy is cut and fattened. Hardly occurs. Furthermore, there is no difference in the abrasion of the Al-Cu-Si side surfaces on the center and outside of the silicon substrate, and the pattern in the substrate is uniformly etched. On the other hand, when the carbon ring is not introduced near the outer periphery of the processing table, the re-injection of the resist product is large near the center of the silicon substrate, and the exhaust gas is exhausted outside. As a result, the number of re-incidents is reduced, making it difficult to perform uniform processing.

Although a high frequency of 2.45 GHz was used here, the same effect can be obtained by using other frequencies.

The effect of the present invention is not limited to the above-described microwave etching apparatus, and the same effect can be obtained with other equipment such as RIE, magnetron RIE, helicon resonance RIE, and inductively coupled RIE.

(Example 4)

Another embodiment according to the present invention will be described. By using the etching method of the embodiment, a wiring having a width of about 100 nm is formed on an M0S transistor having a gate length and a width of about 100 nm formed on a 6-inch silicon substrate. As shown in Fig. 8, M0S transistor 121, capacitor and polysilicon wiring are processed on the silicon substrate, and the space between the lines is insulated by silicon dioxide film 25. ing. On this silicon S plate, a lower film 241 'film 24, a Cu-Si alloy film 23, an upper Ti \ 22, and a resist film 21 to which a mask pattern is transferred are formed. Then, a part of the lower TiN is electrically connected to the M0S transistor and the polysilicon wiring through the contact hole 122 filled with the polysilicon. . By etching this substrate without side etching, the first layer wiring is formed. The resist area on the silicon substrate is about 30%.

The silicon substrate is carried into an etching apparatus, and the Ti 7A Cu-Si / TiN film is processed. The gas to be introduced is about 80 sccm of chlorine, about 20 sccm of boron trichloride, and about 20 sccm of a croft form. When etching is performed under these etching conditions and the resist is removed, A1- Wiring with little scraping or thickening of the side surface of the Si-Cu wiring is formed. As a result, wiring with a width of about 100 nm, which is almost equal to the gate width, can be processed. A silicon dioxide film containing phosphorus and contact holes are formed on the substrate on which the wiring has been processed, and a second layer of TiN / Al-Cu-Si / TiN wiring is further formed thereon. By repeating the formation of the wiring in this manner, a semiconductor device is manufactured. Since the wiring dimensions are as small as about 100 nm, which is about the gate length, the semiconductor device will be a highly integrated semiconductor device. In particular, by reducing the processing dimensions of the wiring, it is possible to reduce the number of wiring layers and the wiring length. Therefore, by using the wiring etching method according to the present invention, it is possible to manufacture a semiconductor device which operates at high speed at lower cost. On the other hand, when the form gas is not added, the side surface of the Al-Cu-Si film is shaved, and the shaved amount exceeds the width of the Al-Cu-Si alloy film (about lOOnm). Was difficult.

Thus, fine wiring processing of a semiconductor device can be performed by using the etching method according to the present invention. Such a wiring process is also possible if the gas type is changed to carborane chloride, carbon bromide, etc., even if the gas is introduced from near the etching equipment processing table.

(Example 5)

Another embodiment of the dry etching apparatus according to the present invention is shown in FIG. In this apparatus, an etching gas is introduced into the vacuum processing chamber 1, a high frequency of 2.45 GHz is generated in the microphone mouth wave generator 2, and this high frequency is transported to the vacuum processing chamber 1 through the waveguide 3 and is subjected to gas plasma. Generate. Two solenoid coils 4 for generating a magnetic field are arranged around the vacuum processing chamber for high-efficiency discharge, and the two coil currents are controlled so that the 875 Gauss magnetic field is almost directly above the processing table. Using Rotron resonance Generate high-density plasma. The vacuum processing chamber 1 has a processing table 5 on which an object 6 is to be processed, and is subjected to etching processing by gas plasma. The etching gas is introduced into the vacuum processing chamber 1 through the gas flow control device, and is exhausted out of the vacuum processing chamber 1 by the exhaust pump 7. The processing table 5 on which the object is to be installed is equipped with an RF power supply 12 and can apply an RF bias from 400 Hz to 13.56 MHz. The inner wall of the quartz chamber 113 is coated with a silicon nitride film 110 so as to prevent oxygen from being emitted.

A 6-inch silicon substrate is transported to this device. This silicon substrate has a silicon oxide film, a lower TiN film, an Al-Cu-Si alloy film, an upper TiN film, and a resist mask on which a mask pattern is transferred on a substrate. The pattern width of the resist mask is 300 nm, and the area of the resist is 50% of the silicon substrate. The substrate is transported to an etching apparatus, and 70 sccm of chlorine gas and 30 sccm of boron trichloride gas are introduced into the etching apparatus as an etching gas, and the etching is performed so that the total pressure becomes lPa. Do. The substrate temperature at the time of etching is 50 ° C., and the RF bias applied to the substrate is approximately 70 kHz at 800 kHz. Etching is performed in the order of upper TiN, Al-Cu-Si alloy and lower TiN.The etching speed of TiN is about 450 nm / min, A1-Cu-Si alloy is about 750 nm / min, and the resist is about 350 nm / min. It is.

When the etching is performed under the above-described conditions, the removal reaction of the resist product by oxygen does not occur, so that dust resulting from the resist product becomes a problem. Under this etching condition, when oxygen gas of about 0.3 sccm (about 0.6 _SCC m in terms of oxygen atoms) is added (0.3% of the total gas flow rate), a highly anisotropic shape can be obtained without generating dust. Oxygen / carbon ratio at this time Is about 5%. In addition, increasing the oxygen gas addition to 1 sccm will cut the side of the A1 alloy. In particular, the side of the A1 alloy just below the upper TiN is cut by about 40 ηιη. The method of reducing the supply amount of oxygen gas to 0.3% can also be achieved by increasing the coating area of the silicon nitride film to 80% or more. By controlling the oxygen gas addition amount between 0.06 sccm and 0.6 scctn, highly accurate anisotropic processing of the A1-Cu-Si alloy film can be performed. This added amount of oxygen gas corresponds to 0.06% to 0.6% of the total gas flow rate. Oxygen Z Carbon incident amount ratio at this time is the oxygen contamination traces of considered It Then 2 from the inner wall surface 1 about 0% _r

In this way, a vacuum treatment that does not generate oxygen: A1-Cu-Si alloy with a small amount (0.06 to 1%) of oxygen gas added using the inner wall material, and the side surfaces of the A1-Cu-Si alloy are reduced in size and thickness A processed shape can be obtained.

The effect of the present invention is not limited to the above-described microwave cutting device, and the same effect can be obtained in other devices such as RIE, magneto-opening RIE, silicon resonance RIE, and inductively coupled RIE. There is.

(Example 6)

Another embodiment according to the present invention will be described. Using the apparatus of Example 1, a multilayer film having the same structure as that shown in FIG. 3 is etched. On the silicon substrate 26, a silicon dioxide film 25, a lower TiN 'film 24, an Al-Cu-Si alloy film 23, an upper TiN film 22 and a resist mask 21 to which a mask pattern is transferred are formed. Is formed. The substrate is conveyed to a processing table 5 of an etching apparatus, and 80 sccm of chlorine gas and 20 sccm of boron trichloride gas are introduced as an etching gas, which is composed of 96% of argon and 4% of methane. The gas is added at 100 sccm, and the pressure in the vacuum processing chamber is controlled to about 2 Pa. Oxygen emitted from the wall is about 2sc _C tri. Silicon group The board is 8 inches and the resist area on the board is about 50%. The substrate temperature during etching is 50 ° C, and the RF bias applied to the substrate is 2 MHz and 100 W from the RF power supply 12 and is applied to the processing table 5 at 100 W.

The etching rate of the Al-Cu-Si film is about 800 nm / min, and the etching rate of the resist is about 300 nm / min. The amount of resist product generated is about 7 sccm in terms of carbon atoms. Taking into account that the resist product deposition effect near the wafer increases the resist product deposition effect by about 2.5 times, the oxygen-carbon incidence ratio is about 11%. When the added methane is added to this, the oxygen-to-coal / injection ratio becomes about 9%. When etching is performed under these conditions, side etching is reduced, and the amount of side etching is reduced to about 10 nm or less. The effect of suppressing side etching rapidly appears when the methane content in the mixed gas is 2% or more, and when 5% or more is added, deposits are generated in the vacuum processing chamber and adhere to the wafer as foreign matter. Can be seen. The reason for this is considered to be that methane is more sedimentable than chlorine-containing gases such as black hole form.

As described above, when adding methane gas, it is desirable to add methane gas in the range of 2 to 5% as compared with the introduction amount of chlorine and boron trichloride gas.

Similar effects can be obtained with etane and butane. In the case of ethane, the introduction amount is half that of methane, which has the effect of suppressing side etching.

In addition, since hydrocarbon gases such as methane and ethane are flammable gases, when used in production lines, safety can be achieved by diluting with an inert gas such as argon, neon, or xenon. It is desirable to secure In addition, although not as effective as methane, the addition of argon gas Excess chlorine gas and oxygen are exhausted, and side etching is slightly reduced.

The effects of the present invention are not limited to the above-described microwave etching apparatus, and similar effects can be obtained with other apparatuses such as RIE, magnetron RIE, helicon resonance RIE, and inductively coupled RIE.

(Example 7)

Another embodiment of the dry etching apparatus according to the present invention is shown in FIG. In this system, an etching gas is introduced into the etching chamber 1, a high frequency is generated from 1 MHz to 2.45 GHz by a second RF (high frequency) power supply 31, and the high frequency is passed through the antenna 32 to perform etching. Propagate to chamber 1 to generate gas plasma. A dielectric 33 is formed on the surface of the antenna 32 to prevent the antenna from being etched. The etching chamber 1 has a processing table 5 on which an object 6 to be processed is placed, and an etching process is performed by gas plasma. The etching gas is introduced into the etching chamber 1 through the gas flow control device, and is exhausted out of the etching chamber 1 by the exhaust pump 7. The processing table 5 on which the workpiece is installed is equipped with an RF power supply 12 and can apply a high frequency (RF) bias from 400 Hz to 1 GHz.

Using the above-described apparatus, a multilayer film having the same structure as that shown in FIG. 3 is etched. On the silicon substrate 26, a silicon dioxide film 25, a lower TiN film 24, an Al-Cu-Si alloy film 23, an upper TiN film 22, and a resist on which a mask pattern is transferred Mask 21 is formed. The substrate is transported to the processing table 5 of the etching apparatus, and as an etching gas, 70 sccm of chlorine gas and 30 sccm of boron trichloride gas are introduced, and it is composed of 96% of argon and 4% of methane. 100 sccm of gas to be added and vacuum processing Control the pressure in the chamber to about 2Pa. Oxygen emitted from the wall is about 2sccm. The silicon substrate is 8 inches and the resist area on the substrate is about 50%. The substrate temperature during etching is 50 ° C, the frequency of the second RF power supply 31 is 13.56 MHz, the output is 300 W, and the RF bias applied to the substrate is 800 kHz from the RF power supply 12. , 100 W at the processing table 5.

The etching rate of the Al-Cu-Si film is about 750 nm / min, and the etching rate of the resist is about 300 nm / min. The amount of the resist product generated is about 7 sccm when converted to the number of carbon atoms. Taking into account the fact that the resist product deposition effect near the wafer increases the resist product deposition effect by about 2.δ, the oxygen / carbon incidence ratio is about 11%. When the added methane is added, the oxygen / carbon injection ratio is about 9%. When etching is performed under these conditions, side etching is reduced, and the amount of side etching becomes about 10 nm. When the methane content in the mixed gas is 2% or more, the effect of suppressing side etching is sharply exhibited. Can be It is considered that the reason for this is that methane is more sedimentable than chlorine-containing gas such as chloroform.

Thus, when adding methane gas, it is desirable to add methane gas in the range of 2 to 5% as compared with the introduction amount of chlorine and boron trichloride gas.

Furthermore, hydrocarbon gases such as methane-ethane are flammable gases. Therefore, when used in a production line, it is desirable to ensure safety by diluting with an inert gas such as argon, neon, xenon or the like. In addition, although not as effective as methane, the addition of argon gas facilitates the exhaust of excess chlorine and oxygen and slightly reduces side etching. As the inert gas, argon having a small difference in mass from chlorine ions is preferably used. The reason for this is that the etching speed is reduced due to the lightness of the helicopter, while the selectivity is reduced due to the heavy weight of xenon and the like.

Industrial applicability

INDUSTRIAL APPLICABILITY The present invention is excellent in microfabrication of a semiconductor device, and is particularly suitable for etching an aluminum film; it can also be applied to etching of an insulating film and the like.

Claims

The scope of the claims

1. A dry etching method characterized in that an object to be processed is etched in a double-faced atmosphere in which the ratio of the number of oxygen atoms to the number of carbon atoms is more than 0% and not more than 10%.

2. A step of introducing an etching gas into a processing chamber for accommodating an object to be processed having a metal film formed on a substrate, a step of plasma-forming the etching gas, and a step of reducing the ratio of the number of oxygen atoms to the number of carbon atoms to 0. %; More than 0%; and a step of etching the metal film.

3. a step of evacuating a filter processing chamber for accommodating an object to be processed having a metal film formed on a surface thereof, a step of introducing an etching gas into the processing chamber, and a step of plasma-forming the gas. Introducing a gas containing a carbon atom into the first field region; and injecting the gas into the object so that the number of severe elements becomes 10% or less of the number of carbon atoms. And d) etching the film.

4. The dry etching method according to claim 3, wherein the treatment chamber is formed of quartz, and the oxygen ': -ί' · is supplied from quartz.

5. A process in which a workpiece having a resist pattern formed on an aluminum film or an aluminum alloy film on a substrate is placed on a sample stage in a processing chamber, and a step of introducing gas into the processing chamber. A step of converting the gas into a plasma, and contacting the object to be treated with plasma to obtain ethane, methane, flavan or butane fluorine, chlorine or nitrogen-substituted substance, or carborane. Introducing the Haguchigen-substituted gas into the processing chamber, the ratio of the number of oxygen atoms to the number of carbon atoms exceeds 0% and is 10% or less. A step of etching the aluminum film or the aluminum alloy film in a double-faced atmosphere set forth below.

6. A step of introducing an etching gas into a processing chamber for accommodating an object to be processed in which a metal film is formed on a silicon substrate, and a step of introducing a carbon gas from a solid containing oxygen and carbon provided in a double-layer space. Is supplied to the object to be processed, and the metal film is etched so that the ratio of the number of oxygen atoms to the number of carbon atoms incident on the object to be processed becomes greater than 0% and 10% or less. And a dry etching method.

7. a step of introducing an etching gas and an additional gas of 7% to less than 35% of the etching gas into the processing chamber; a step of converting the etching gas into plasma; Etching the workpiece placed in the processing chamber.

8. The dry etching method according to claim 7, wherein the etching gas is a mixed gas of a chlorine gas and a boron trichloride gas, and the additive gas is a haptic compound of a hydrocarbon.

9. The dry etching method according to claim 8, wherein the hydrocarbon halide is a co-form.

10. A step of placing an object to be etched on which a resist film having a predetermined pattern is formed on a table in a processing chamber having an inner wall made of quartz, (the quartz inner wall area X the quartz inner wall etching speed X The quartz inner wall oxygen density)

÷ (the resist area X the resist etching rate X the resist carbon density X 2.δ + Supply of gas containing carbon)

A dry etching method characterized in that the object to be processed is etched such that the value of is not more than 0.1.

11. A step of placing a semiconductor wafer on which a resist mask having a predetermined pattern is formed on an aluminum film on a table in a processing chamber whose inner wall surface is made of a dielectric material other than oxide; A step of introducing an etching gas into the chamber, a step of adding an oxygen gas in a range of 0.06% to 0.6% with respect to the etching gas and introducing the same, and forming the etching gas into a plasma in the processing chamber. And etching the aluminum film in a region exposed by contacting the aluminum film with the plasma. A dry etching method, comprising:

12. The dry etching method according to item 11, wherein the etching gas comprises chlorine gas and boron trichloride gas.

13. The dry etching method according to item 11, wherein at least 80% of the inner wall surface is made of a dielectric material other than an oxide.

14. The dry etching method according to item 11 or 13, wherein the dielectric other than the oxide is a silicon nitride.

15. A dry etching method, characterized in that an object to be processed is etched in a double-faced atmosphere in which the ratio of the number of oxygen atoms to the number of carbon atoms is 5% or more and 9% or less.

16. A process of evacuating a processing chamber for accommodating the processing object on which the metal film is formed, a step of introducing an etching gas into the processing chamber, a step of converting the gas into plasma, Oxygen is incident on the surface, and the carbon-containing solid material provided in the two-face region makes it possible to Dry etching, wherein the metal film is etched by injecting carbon into the object to be processed so that the number of oxygen atoms to be incident is more than 0% and not more than 10% of the number of carbon atoms. Method.

17. Irradiate the gas to be processed with gaseous molecules containing oxygen and carbon atoms so that the ratio of the number of oxygen atoms to the number of carbon atoms is more than 0% and not more than 10%. A dry etching method characterized by etching.

18. The object to be treated is irradiated with oxygen and carbon by controlling the ratio of the number of carbon atoms and the number of oxygen atoms in the two-face region to etch the object. Etching method.

19. A processing chamber for accommodating the object to be etched, a means for exhausting the processing chamber, a table provided in the processing chamber for mounting the object to be etched, and a means for applying a high frequency to the object to be etched. A dry etching apparatus having a gas inlet for introducing a gas contributing to an etching reaction of the etching target object into the secondary etching region.

20. A processing chamber for accommodating an object to be processed, means for evacuating the processing chamber, means for introducing an etching gas into the processing chamber, means for applying a high frequency to the object to be processed, A dry etching apparatus, comprising: a sample stage on which an object to be processed is placed; and a gas inlet for introducing a gas containing carbon to an outer periphery of the sample stage.

21. A processing chamber for accommodating an object to be processed, means for evacuating the processing chamber to K empty space, means for introducing an etching gas into the processing chamber, means for applying a high frequency to the object to be processed, A carbon-containing solid material provided in the two-face region. Device.

22. a step of forming an insulating film on the base, a step of forming a connection port in the insulating film, a step of filling the connection port with a conductive layer, and forming a wiring layer on the insulating film; Forming a resist pattern on the wiring layer, and etching the exposed wiring layer so that the number of oxygen atoms incident on the wiring layer is 10% or less of the number of carbon incident atoms. And a method for manufacturing a semiconductor device.

23. The method of manufacturing a semiconductor device according to item 22, wherein the wiring layer is a laminated film of a first titanium nitride layer, an aluminum layer, and a second titanium nitride layer.