CN103779203A - Plasma etching method - Google Patents

Plasma etching method Download PDF

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Publication number
CN103779203A
CN103779203A CN201310015232.XA CN201310015232A CN103779203A CN 103779203 A CN103779203 A CN 103779203A CN 201310015232 A CN201310015232 A CN 201310015232A CN 103779203 A CN103779203 A CN 103779203A
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film
gas
etching
silicon nitride
etched
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CN103779203B (en
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渡边智行
森本未知数
药师寺守
小野哲郎
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Hitachi Ltd
Hitachi High Tech Corp
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Hitachi Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
    • H01L21/3105—After-treatment
    • H01L21/311—Etching the insulating layers by chemical or physical means
    • H01L21/31105—Etching inorganic layers
    • H01L21/31111—Etching inorganic layers by chemical means
    • H01L21/31116—Etching inorganic layers by chemical means by dry-etching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32192—Microwave generated discharge
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
    • H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
    • H01L21/321—After treatment
    • H01L21/3213—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
    • H01L21/32131—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by physical means only
    • H01L21/32132—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by physical means only of silicon-containing layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/32—Processing objects by plasma generation
    • H01J2237/33—Processing objects by plasma generation characterised by the type of processing
    • H01J2237/334—Etching

Abstract

The invention relates to a plasma etching method. Compared with the prior art, the method can further improve etching selection ratio of a film which is different form an etched film. Compared with films different from the etched films selectively etching the etched films, the plasma etching method is characterized in that plasma etches the etched films by using gas of accumulation films which can generate same constituent with that of the films.

Description

Plasma etching method
Technical field
The present invention relates to use plasma to carry out etched plasma etching method.
Background technology
Because silicon oxide film and silicon nitride film have excellent characteristic as dielectric film, therefore in the manufacture of semiconductor device, in many operations, used.In the manufacturing process of semiconductor device, to being formed at silicon nitride film on silicon oxide film, to carry out etched operation more common.For example, in the time that transistorized doped layer forms, there is the manufacturing process of the distance piece structure of the both sides that are disposed at gate electrode.The general silicon nitride film that uses in described distance piece structure forms silicon nitride film on the silicon oxide film being formed at around gate electrode, just can manufacture by this silicon nitride film of etching.Barrier film during as silicon nitride film etching uses silicon oxide film.
As increase the silicon nitride film that the forms technology with respect to the etching selectivity of silicon oxide film on such silicon oxide film, disclose for example patent documentation 1 such by CHF 3gas or CH 2f 2the fluorocarbon gas such as gas are carried out silicon nitride film as etching gas.
In the disclosed technology of patent documentation 1, the radical reaction of silicon nitride film based on using fluoro free radical (F*) as main etching raw material and etched, by pile up the accumulating film of fluorocarbon system on silicon oxide film, can make etching speed reduce, and can increase the etching selectivity with respect to silicon oxide film.
Prior art document
Patent documentation
Patent documentation 1: Unexamined Patent 10-303187 communique
Summary of the invention
The problem that invention will solve
According to above-mentioned prior art, can increase the etching selectivity of silicon nitride film with respect to silicon oxide film.But, even for silicon oxide film, also mainly based on CF 3ion carries out etching as ion-assisted reaction mechanism (ion-assisted reaction mechanism) of main etching raw material.Therefore, shape control in the manufacturing process of the raising take silicon nitride film etching speed, described distance piece structure etc. is when object applies high bias voltage to wafer, even silicon oxide film also carries out etching, silicon nitride film reduces with respect to the selection ratio of silicon oxide film.
But along with the miniaturization of semiconductor device in recent years, in the manufacturing process of described distance piece structure, the filming of the silicon oxide film that the barrier film that etching is used as silicon nitride film uses is also remarkable.Therefore, more require to improve the selection ratio of silicon nitride film with respect to silicon oxide film.
In view of above problem, the object of the invention is to, plasma etching method is provided, and it can obtain in the silicon nitride film etching on the silicon oxide film relating in the manufacture of the semiconductor device of high miniaturization desired silicon nitride film with respect to the selection ratio of silicon oxide film.
For solving the means of problem
Plasma etching method of the present invention, it is with respect to selectively etched film described in etching of the film different from etched film, it is characterized in that, use can generate and contain and the composition of the described film gas with the accumulating film of sample ingredient, etched film described in plasma etching.
In addition, the invention provides plasma etching method, it,, with respect to selectively etched film described in etching of the film different from etched film, is characterized in that, use can generate the gas of the accumulating film that contains Si-O key, etched film described in plasma etching.
Invention effect
By formation of the present invention, compared with prior art can improve the etching selectivity with respect to the etched film of the film different from etched film.
Accompanying drawing explanation
Fig. 1 is the figure that represents the formation that is applicable to microwave plasma Etaching device of the present invention;
Fig. 2 is the figure of the result that compares with respect to the etching selectivity of silicon oxide film of the silicon nitride film in condition and the existence conditions representing embodiment 1;
Fig. 3 is the figure that represents the analysis result that uses x-ray photoelectron optical spectroscopy;
Fig. 4 is the figure that represents the etching process of embodiment 1;
Fig. 5 be represent silicon nitride film with respect in the etching selectivity of silicon oxide film with respect to by CH 3f gas and O 2the SiF of the mist that gas forms 4the figure of the interdependence of gas flow;
Fig. 6 be represent silicon nitride film with respect in the etching selectivity of silicon oxide film with respect to by CH 3f gas and SiF 4the O of the mist that gas forms 2the figure of the interdependence of gas flow;
Fig. 7 is the figure of the result that compares with respect to the etching selectivity of polysilicon film of the silicon nitride film in condition and the existence conditions representing embodiment 2;
Fig. 8 is the figure that represents the etching process of embodiment 2;
Fig. 9 is the figure that represents the etching process of the distance piece formation of the silicon nitride film of embodiment 2;
Figure 10 is the figure that represents the etching process of embodiment 3.
Symbol description:
100 samples
101 vacuum tanks
102 vacuum pumps
103 process chambers
104 magnetron power sources
105 waveguide pipe
106 resonance container
106 ' resonant chamber
107 sample benchs
108 magnetic plugs
109 window components
110 bath boards
111 high frequency bias power supplys
112 DC power supply
Embodiment
With reference to Fig. 1 ~ Figure 10, one embodiment of the invention are described below.
Fig. 1 is the sectional arrangement drawing of the formation of the microwave plasma Etaching device that uses in the present embodiment.In Fig. 1, plasma etching apparatus possesses: vacuum tank 101, to the device of vacuum tank 101 internal feed microwaves, by the exhaust apparatus of vacuum tank 101 exhaust gas inside.
Possess in vacuum tank 101 inside: process chamber 103, it forms isoionic space for side therein, and is disposed at the sample 100 as handling object of inner side by plasma treatment; Sample bench 107, it is disposed in process chamber 103 and sample 100 is loaded thereon face and is kept.In addition, above vacuum tank 101, dispose: supply with the magnetron power source 104 of microwave and propagate microwave and be waveguide pipe 105, be connected with waveguide pipe 105 and import the resonance container 106 resonating at the microwave of waveguide pipe 105 internal communications and in the generation of inner space to the pipeline of process chamber 103 interior importings.
In addition, in vacuum tank 101, dispose the magnetic plug 108 that magnetic field is produced.Magnetic plug 108 be surround the top of the vacuum tank 101 of drum periphery mode and configure, by coil supply with electric current occur magnetic field.In the present embodiment, magnetic plug 108 is with multistage configuration, waits the magnetic field of the shape that magnetic field expands gradually take axle as object to be imported into process chamber 103 inner sides around the central shaft of above-below direction downwards.
In addition, below vacuum tank 101, disposing exhaust apparatus is turbomolecular pump equal vacuum pump 102, the open communication of using with the circular exhaust being disposed under sample bench 107 in process chamber 103 bottoms.
The space that disposes the resonance use in the resonance container 106 with the drum consistent with axle above the process chamber 103 of drum be resonant chamber 106 '.This resonant chamber 106 ' and process chamber 103 between dispose form resonant chamber 106 ' the discoideus window component 109 of dielectric system of bottom surface.
Below window component 109 with window component 109 below separate gap and dispose side by side the discoideus bath board 110 of dielectric system, form the courtyard surface of process chamber 103 below bath board 110.
Bath board 110 configures with the subtend above of sample bench 107, and portion disposes the through hole of multiple gases of using from the interior importing processing of wafers of upper direction process chamber 103 in the central.The pipeline connection that gap between above-mentioned window component 109 and bath board 110 and the etching gas of supplying with from the gas source (not shown) being arranged at the building such as dust free room that is provided with microwave plasma Etaching device are through-flow, after importing to above-mentioned gap by pipeline with gas from the etching of gas source, flow into by through hole sample bench 107 directions downwards.
The internal configurations of sample bench 107 has the electrode of conduction system, and this electrode is electrically connected with the high frequency bias power supply 111 of High frequency power from assigned frequency to sample bench 107 that supply with.In mounting surface on sample bench 107, be placed with under the state of wafer, form bias by the High frequency power of supplying with from this high frequency bias power supply 111 in wafer surface, by and potential difference between the plasma of the process chamber 103 interior formation above sample bench 107 by ion guides to wafer.
In addition, dispose on the top of sample bench 107 by the Al of mounting surface that forms sample 2o 3and Y 2o 3the dielectric film (not shown) forming Deng dielectric substance, disposes therein, by static, chip sucking is attached to the electrode for electrostatic attraction in dielectric film surface, is electrically connected with this electrode for electrostatic attraction the DC power supply 112 of supplying with direct current power.
In the microwave plasma Etaching device that possesses above-mentioned formation, by utilizing the state of exhaust apparatus exhaust and then decompression in the inert gases such as the interior importing argon gas of process chamber 103 from gas source, utilizing the conveying devices such as mechanical arm (not shown), is wafer to carrying on sample bench 107 and in this handing-over by gate valve (not shown) by sample 100.
Sample 100 is after to be wafer loaded on the dielectric film of mounting surface that forms sample bench 107, and the electrode in from DC power supply 112 to dielectric film is supplied with electric power and forms electrostatic force, is adsorbed on dielectric film and is kept.
Etching is imported in process chamber 103 by the through hole of above-mentioned bath board 110 from gas source with gas, and by the balance of the exhaust that produces with vacuum pump 102, process chamber 103 inside are adjusted to the pressure of regulation simultaneously.In the interior propagation of waveguide pipe 105, arrive resonance container 106, at the electric field of inner resonant chamber 106 ' formation prescribed strength from the microwave of the vibration of magnetron power source 104.This electric field sees through window component 109, bath board 110 to the interior supply of process chamber 103.
By the interaction of the magnetic field of supplying with from magnetic plug 108 and the microwave of supplying with from resonance container 106, etching is excited and plasma with gas, and the space above the sample bench 107 in process chamber 103 forms plasma.Plasma by this formation is implemented etch processes to wafer.
Then,, the various embodiments of the present invention that used above-mentioned microwave plasma Etaching device are described.
Embodiment 1
At the CH using as shown in Table 1 3f gas, O 2gas and SiF 4the mist that gas forms carries out in the condition and existence conditions of etched the present embodiment, silicon nitride film and silicon oxide film respectively, and comparative studies silicon nitride film is with respect to the etching selectivity of silicon oxide film.Fig. 2 represents the result of comparative studies.
Table 1
CH 3F gas 50sccm
O 2Gas 20sccm
SiF 4Gas 5sccm
Gas pressure 0.5Pa
Microwave power supply power 1400W
Grid bias power supply power 40W
As shown in Figure 2, under existence conditions, silicon nitride film shows the high value that is about 17 with respect to the etching selectivity of silicon oxide film, and still, because the etching speed of silicon oxide film is for just, therefore the etching of silicon oxide film is carried out.
On the other hand, under the condition of the present embodiment, the etching speed of silicon nitride film is than the further increase of existence conditions.In addition, the etching speed of silicon oxide film becomes negative value, and is presented at and on silicon oxide film, is formed with deposit.Therefore,, under the condition of the present embodiment, silicon nitride film becomes ∞ with respect to the etching selectivity of silicon oxide film.
Like this, the present embodiment, compared with existence conditions, can significantly improve the etching selectivity of silicon nitride film with respect to silicon oxide film.In other words, can obtain in the silicon nitride film etching on the related silicon oxide film of the manufacture of semiconductor device of high miniaturization desired silicon nitride film with respect to the selection ratio of silicon oxide film.
At this, so-called silicon nitride film is with respect to the etching selectivity of silicon oxide film, for the etching speed of silicon nitride film is divided by the value of the etching speed of silicon oxide film.
Then, the mechanism improving with respect to the etching selectivity of silicon oxide film in order to investigate the silicon nitride film of the present embodiment, use x-ray photoelectron optical spectroscopy (X-Ray Photoelectron Spectroscopy: following, be called XPS) analyze silicon wafer surface after treatment under the condition of the present embodiment and existence conditions, Fig. 3 represents analysis result.
Under the condition of the present embodiment and existence conditions, all form deposit at silicon wafer surface.After this deposit that utilized XPS analysis, as shown in Figure 3, can confirm that existence conditions forms 2.2nm, embodiment condition and form the deposit of approximately 3 times of thickness of 6.6nm.In addition, the condition of embodiment, compared with existence conditions, also can confirm to contain a large amount of Si-O keys in deposit.According to this analysis result, think and be piled up on silicon oxide film and make to select than improving by the deposit that contains a large amount of Si-O keys.
According to the analysis result of above-mentioned XPS, by containing the deposit of a large amount of Si-O keys, significantly improve silicon nitride film and consider as follows with respect to the mechanism of the etching selectivity of silicon oxide film.
Fig. 4 be illustrated in etch processes basilar memebrane under the condition of embodiment be etched while being silicon oxide film, the etched film wafer that is silicon nitride film of silicon oxide film, mask carry out through figure.
Fig. 4 (a) by the free radical, the ion that are produced by plasma, carries out the etching of wafer after representing that plasma has just occurred take ion-assisted reaction as main body.In addition, SiF 4gas, O 2gas dissociates by plasma respectively, generates thus Si, O in plasma.As shown in Fig. 4 (b), these Si and O adhere to as the accumulating film of Si-O key at the mask surface of silicon oxide film.
On the other hand, on silicon nitride film surface, above-mentioned Si and O, before Si-O bonding, because the N bonding of O and silicon nitride film becomes the NOx that volatility is high, are therefore difficult to generate the accumulating film of Si-O key on silicon nitride film surface.This is because the bond energy (150Kcal/mol) of N-O key is higher than the bond energy of Si-N key (105Kcal/mol), therefore, in the time that O is attached on silicon nitride film surface, easily draws the N of silicon nitride film.
Therefore, as shown in Fig. 4 (c), the mask that becomes silicon oxide film not etched and only silicon nitride film carry out etched state.
After silicon nitride film is removed by etching, the silicon oxide film of basilar memebrane exposes, still, and as shown in Fig. 4 (d), even also same with on the mask surface of silicon oxide film on the silicon oxide film surface of basilar memebrane, the Si in plasma and O adhere to as the accumulating film of Si-O key.
At this moment, the etching of silicon nitride film is shaped as cone-shaped, and therefore, although need to carry out the etching of appending for being perpendicular shape, owing to generating the accumulating film that has Si-O key on the silicon oxide film surface at basilar memebrane, therefore the silicon oxide film of basilar memebrane is not etched.
Therefore,, as shown in Fig. 4 (e), can not cause damage and obtain perpendicular shape the silicon oxide film of basilar memebrane.
Then, investigation SiF 4gas for by silicon nitride film with respect to the CH in the etching selectivity of silicon oxide film 3f gas and O 2the flow interdependence of the mist that gas forms, Fig. 5 represents result.
As shown in Figure 5, as added SiF 4gas, the etching speed of silicon nitride film increases, and the etching speed of silicon oxide film becomes negative, becomes and does not carry out etched state.The etching speed of silicon nitride film is at SiF 4gas is with respect to by CH 3f gas and O 2the flow-rate ratio of mist that gas forms is to become maximum near 7%, and after this, when above-mentioned flow-rate ratio increases, etching speed reduces.
In the time that above-mentioned flow-rate ratio exceedes 20%, the etching speed of silicon nitride film becomes 3.0nm/min left and right, becomes the state of the etched etch stop that does not carry out silicon nitride film in the time that above-mentioned flow-rate ratio further increases.Therefore, wish SiF 4gas is with respect to by CH 3f gas and O 2the flow that the mist that gas forms becomes below 20% uses.
Then, investigation silicon nitride film is with respect to the O in the etching selectivity of silicon oxide film 2gas is for by CH 3f gas and SiF 4the flow interdependence of the mist that gas forms, Fig. 6 represents result.
As shown in Figure 6, can find out with respect to by CH 3f gas and SiF 4the O of the mist that gas forms 2it doesn't matter for the flow-rate ratio of gas, because the etching speed of silicon oxide film is negative value, therefore do not carry out the etching of silicon oxide film.
On the other hand, the etching speed of silicon nitride film depends on O 2the flow-rate ratio of gas and significantly change.At O 2the flow-rate ratio of gas below 25% and 45% more than region time, because silicon nitride film stops etching, therefore O 2the flow-rate ratio of gas is used as good in 25% ~ 45% region.
In addition, pass through O 2the flow-rate ratio of gas, because the etching speed of silicon nitride film significantly changes, therefore by suitably setting O 2the flow-rate ratio of gas can be the etching speed of expecting by the etching speed control of silicon nitride film.
Due to the miniaturization of semiconductor device in recent years, thereby become in the present embodiment the also filming of silicon nitride film of etch target.In the time of this film of etching, slow down by the etching speed that makes silicon nitride film, become easy thereby make to control etch quantity.In the present embodiment, as mentioned above, pass through O 2the flow-rate ratio of gas, can be controlled to the etching speed of silicon nitride film the etching speed of expectation, therefore, even be also effective for above-mentioned etching.
In the present embodiment, used by CH 3f gas, O 2gas and SiF 4the mist that gas forms, still, CH 3f gas and O 2even if gas uses respectively fluorocarbon gas, oxygen-containing gas also can obtain the effect same with the present embodiment.As fluorocarbon gas, can use CH 3f gas, CH 2f 2gas, CHF 3at least one gas in gas.
In addition, as oxygen-containing gas, can use O 2gas, CO gas, CO 2at least one gas in gas.In addition, by fluorocarbon gas, oxygen-containing gas and SiF 4in the mist that gas forms, also can add inert gas.Can use at least one gas in He gas, Ne gas, Ar gas, Xe gas, Kr gas as inert gas.
In addition, be the place of gas of gas as above-mentioned fluorocarbon, even if use by CH 4the mist that gas and fluoro-gas form, also can obtain the effect same with the present embodiment.As fluoro-gas, can use SF 6gas, CF 4at least one gas in gas.
In addition, in the present embodiment, etched film is made as to silicon nitride film, still, even silicon oxynitride film (SiON film), nitrogen silicon oxycarbide films (SiOCN film) also can be obtained to the effect same with the present embodiment as etched film.In addition, even silicon carbide film (SiC film), silicon oxycarbide films (SiOC film) also can be obtained to the effect same with the present embodiment as etched film.The in the situation that of silicon carbide film (SiC film), silicon oxycarbide films (SiOC film), in the time of etching, pass through O 2c bonding in the O of the generation of dissociating of gas and etched film, generates the high COx of volatility, therefore, can improve the etching selectivity of etched film with respect to silicon oxide film.
In addition, in the present embodiment, to having used the ECR (electron cyclotron resonace of microwave; Electron Cyclotron Resonance) Application Example of microwave plasma Etaching device of mode is illustrated, but be not limited to this, also gone for using the plasma etching apparatus of the plasma creating device of capacitive coupling type, inductance coupling high type.
Above, as mentioned above, the present invention is the gas that uses the film different from etched film and can generate the accumulating film of same sample ingredient, and etching suppresses the plasma etching method of the etched film of the generation of above-mentioned accumulating film.Therefore,, by the present invention, compared with prior art can significantly improve the etched film of the generation that suppresses above-mentioned accumulating film with respect to the etching selectivity of the film different from etched film.
As other embodiments of the invention, for example, even having used as basilar memebrane in the etching of polysilicon film of metal electrode material,, in the situation that basilar memebrane uses TaN film or WN film, use TaF 5gas or WF 6gas etch polysilicon film thus, can form the accumulating film that contains Ta or W on TaN film or WN film, therefore, compared with prior art can significantly improve the etching selectivity of polysilicon film with respect to TaN film or WN film.
Embodiment 2
In the distance piece formation of the silicon nitride film in the manufacturing process of nearest semiconductor device etc., the silicon nitride film of prior art becomes remarkable with respect to the selection of polysilicon film or silicon substrate than inadequate problem.Therefore, in the present embodiment, describe with respect to the device of the selection ratio of polysilicon film or silicon substrate improving silicon nitride film.
First, initial, comparative studies the etching selectivity of silicon nitride film with respect to silicon substrate.Use as shown in table 2 by CH 3f gas, O 2gas and SiF 4the mist that gas forms carries out in the condition and existence conditions of etched the present embodiment, replace silicon substrate to be etched in respectively polysilicon film (Poly-Si) and the silicon nitride film of film forming on silicon substrate, comparative studies silicon nitride film is with respect to the etching selectivity of polysilicon film.Fig. 7 represents the result of comparative studies.
In addition, why in order to ask silicon nitride film to replace silicon substrate to use polysilicon film with respect to the etching selectivity of silicon substrate, although be that Constitution Elements is silicon (Si) element at silicon substrate and polysilicon film because silicon substrate is the different substrate of crystallization that single crystals, polysilicon film are many crystallizations.
Table 2
CH 3F gas 50sccm
O 2Gas 20sccm
SiF 4Gas 5sccm
Gas pressure 0.5Pa
Microwave power supply power 1400W
Grid bias power supply power 40W
As shown in Figure 7, under existence conditions, silicon nitride film is about 10 with respect to the etching selectivity of silicon oxide film, and still, because the etching speed of polysilicon film is for just, therefore the etching of polysilicon film is carried out.
On the other hand, under the condition of the present embodiment, show that the etching speed of polysilicon film becomes negative value, and on polysilicon film, be formed with accumulation horizon.Therefore,, under the condition of the present embodiment, silicon nitride film becomes ∞ with respect to the etching selectivity of polysilicon film.
Like this, the present embodiment, compared with existence conditions, can significantly improve the etching selectivity of silicon nitride film with respect to polysilicon film.In other words, can obtain in the silicon nitride film etching on the related silicon substrate of the manufacture of semiconductor device of high miniaturization desired silicon nitride film with respect to the selection ratio of silicon substrate.
At this, so-called silicon nitride film is with respect to the etching selectivity of polysilicon film, for the etching speed of silicon nitride film is divided by the value of the etching speed of polysilicon film.
Because the gas system using in the present embodiment is the gas system same with the gas system using in embodiment 1, therefore according to the analysis result that uses the XPS shown in Fig. 3, think and compare with existence conditions, easily generate under the conditions shown in Table 2 the accumulating film that contains Si-O key, this accumulating film is piled up in the raising that contributes to select ratio on polysilicon film.
According to this result, below use Fig. 8 to illustrate by the condition shown in table 2 and significantly improve the mechanism of silicon nitride film with respect to the selection ratio of polysilicon film.
Fig. 8 is illustrated under the condition of embodiment, etch processes substrate be the etching while being silicon oxide film, the etched film wafer that is silicon nitride film of silicon substrate, mask carry out through figure.
Fig. 8 (a) by the free radical, the ion that are produced by plasma, carries out the etching take ion-assisted reaction as main body to wafer after representing that plasma has just occurred.In addition, SiF 4gas, O 2gas dissociates by plasma respectively, thus, generates Si, O in plasma.As shown in Fig. 8 (b), adhere to as the accumulating film containing Si-O key at the mask surface of silicon oxide film.
On the other hand, on silicon nitride film surface, above-mentioned Si and O are before Si-O bonding, and the N bonding of O and silicon nitride film and become the NOx that volatility is high, therefore, is difficult to generate the accumulating film of Si-O key on silicon nitride film surface.This be because, because the bond energy (150Kcal/mol) of N-O key is higher than the bond energy of Si-N key (105Kcal/mol), thus cutting off by ion after the Si-N key of silicon nitride film, N easily be attached to the O bonding on silicon nitride film.
Therefore,, as shown in Fig. 8 (c), become that to generate the mask of silicon oxide film of accumulating film etched and be only difficult to the state that the etching of the silicon nitride film that generates accumulating film is carried out.
After silicon nitride film is removed by etching, the silicon substrate of substrate exposes, and becomes the etched state by plasma.But, on silicon substrate surface, be attached with too deposit, by the O containing in deposit, silicon substrate surface is oxidized, forms silicon oxide film.
Therefore,, as shown in Fig. 8 (d), similarly on silicon substrate surface, also generate with the silicon oxide film of mask the accumulating film that contains Si-O key.Owing to generating this accumulating film, do not carry out the etching of silicon substrate, can obtain the high selection ratio as the silicon nitride film of etched film.Why on silicon substrate surface, form silicon oxide film, because cut off on silicon substrate surface after Si-Si key (bond energy: 76Kcal/mol) by the energy of ion, Si is again when bonding, compared with generating Si-Si key and Si-F key (bond energy: 130Kcal/mol), more easily generate with the O containing the Si-O key (bond energy: 192Kcal/mol) that energy is higher in accumulating film.
When Fig. 8 (d), the etching of silicon nitride film is shaped as cone-shaped, therefore, although need to carry out the etching of appending for being perpendicular shape, but on the silicon substrate surface of substrate, generate the accumulating film that contains Si-O key, therefore the silicon substrate of substrate is not etched.
Therefore,, as shown in Fig. 8 (e), can not obtain perpendicular shape to causing damage on the silicon substrate of substrate.
At this, the substrate that makes silicon nitride film is silicon substrate, still, even using polysilicon film as substrate, can obtain too high selection ratio same with silicon nitride film, can not cause damage and carries out etching.
Then, describe applied example of the present invention in need to forming with respect to the high selectivity of the silicon nitride film of silicon substrate with respect to the distance piece of the silicon nitride film of the high selectivity of the silicon nitride film of polysilicon film.
To on the silicon nitride film of the mode film forming to cover the gate electrode being formed by the polysilicon film (Poly-Si) shown in Fig. 9 (a), form distance piece, the silicon nitride film on etch-gate electrode top and the silicon nitride film on silicon substrate top, the silicon nitride film of the side of residual gate electrode and form the distance piece of silicon nitride film.
Because the silicon nitride film of the side of covering grid electrode must be not etched and residual, therefore, need to supply with high High frequency power from high frequency bias power supply 111, vertically introduce ion, carry out the etching that anisotropy is high.But because by supplying with high High frequency power, ion energy uprises, therefore, polysilicon film and silicon substrate are also easily etched.
Therefore, in the conventional method, in the high etching of anisotropy, likely silicon substrate and polysilicon film are brought to damage.That is, in now the distance piece of methodical silicon nitride film forms, can say with respect to the selection of the silicon nitride film of silicon substrate than and with respect to the selection of the silicon nitride film of polysilicon film than insufficient.
In addition, along with the miniaturization of semiconductor device, even if also more require etched anisotropy in distance piece forms, therefore, the high frequency bias electric power of use uprises.Therefore, there is in the conventional method the possibility that can not obtain necessary selection ratio.
In the time that the distance piece of the silicon nitride film shown in Fig. 9 (d) forms middle application the present embodiment, selectively pile up deposit on the surface of polysilicon film and silicon substrate, therefore, do not carry out the etching of polysilicon film and silicon substrate, can obtain the shape that there is no damage.Below, the example that has been suitable for the present embodiment in the distance piece of silicon nitride film forms is described.
Etching condition has used the condition identical with table 2.Process gas is interior by plasma at process chamber 103, generates free radical and ion.In addition, SiF 4gas, O 2gas dissociates by plasma respectively, thus, generates Si, O in plasma.
Carry out the etching as main body of ion-assisted reaction that free radical to be generated and ion produce.At this, introduce ion by the high frequency bias electric power applying to sample bench 107, therefore, as shown in Fig. 9 (b), the silicon nitride film on silicon substrate top and gate electrode top is etched.In addition, above-mentioned Si and O pile up as the accumulating film that contains Si-O key, but, as illustrated in the present embodiment, on silicon nitride film before Si-O bonding, the N bonding of O and silicon nitride film and become the NOx that volatility is high is therefore difficult to generate the accumulating film of Si-O key on silicon nitride film surface, and the etching of silicon nitride film is carried out.
In the time that the etching of silicon nitride film is carried out, as shown in Fig. 9 (c), silicon substrate firstly appears out from, and becomes the residual state of silicon nitride film on gate electrode top.Until during the etching of the silicon nitride film on gate electrode top finishes, the silicon substrate exposing is exposed in plasma, therefore, in the conventional method, in silicon substrate, produce damage.But, in the present embodiment, on silicon substrate, pile up and have the accumulating film that contains Si-O key, therefore do not carry out the etching of silicon substrate.Therefore, until during the etching of the silicon nitride film on gate electrode top finishes, silicon substrate is not etched yet.
In addition, after expose on gate electrode top, appending while carrying out etching, as shown in Fig. 9 (d), piled up on the top of polysilicon film the accumulating film that contains Si-O key, thus, polysilicon film is not etched yet.Therefore,, as shown in Fig. 9 (d), can be not silicon substrate and polysilicon film not be caused to damage and form the distance piece of silicon nitride film.
In Fig. 9 (c), the silicon nitride film on silicon substrate first disappears, and silicon substrate exposes, still, even the silicon nitride film on gate electrode top first disappears, in the situation that polysilicon film exposes too.
In addition, use silicon substrate as the substrate of gate electrode in the present embodiment, but, even use in the situation of silicon oxide film as the substrate of gate electrode, also same with the present embodiment, and the silicon oxide film surface sediment that expose etched at silicon nitride film the accumulating film that contains Si-O key, therefore, silicon oxide film is not etched.Therefore, same with the situation of silicon substrate, the silicon oxide film to substrate and polysilicon film do not cause damage and form the distance piece of silicon nitride film.
In the present embodiment, use by CH as process gas 3f gas, O 2gas and SiF 4the mist that gas forms, still, CH 3f gas and O 2even if gas uses respectively fluorocarbon gas, oxygen-containing gas also can obtain the effect same with the present embodiment.As fluorocarbon gas, can use CH 3f gas, CH 2f 2gas, CHF 3at least one gas in gas.
In addition, as oxygen-containing gas, can use O 2gas, CO gas, CO 2at least one gas in gas.In addition, also can be by fluorocarbon gas, oxygen-containing gas and SiF 4in the mist that gas forms, add inert gas.As inert gas, can use at least one gas in He gas, Ne gas, Ar gas, Xe gas, Kr gas.
In addition, be the place of gas of gas as above-mentioned fluorocarbon, even if use by CH 4the mist that gas and fluoro-gas form, also can obtain the effect same with the present embodiment.As fluoro-gas, can use SF 6gas, CF 4at least one gas in gas.
In addition, in the present embodiment, etched film is made as to silicon nitride film, still, even silicon oxynitride film (SiON film), nitrogen silicon oxycarbide films (SiOCN film) also can be obtained to the effect same with the present embodiment as etched film.
In addition, even silicon carbide film (SiC film), silicon oxycarbide films (SiOC film) also can be obtained to the effect same with the present embodiment as etched film.The in the situation that of silicon carbide film (SiC film), silicon oxycarbide films (SiOC film), in the time of etching, pass through O 2dissociating of gas and C bonding in the O and the etched film that produce generates the high COx of volatility, therefore, can improve the etching selectivity of etched film with respect to silicon substrate or polysilicon film.
In addition, in the present embodiment, the application examples of microwave plasma Etaching device to ECR (the Electron Cyclotron Resonance) mode that has used microwave is illustrated, but be not limited to this, also gone for using the plasma etching apparatus of the plasma creating device of capacitive coupling type, inductance coupling high type.
Embodiment 3
In the present embodiment, as using the film different from etched film and can generating the gas of the accumulating film of same sample ingredient, with respect to the optionally plasma etching method of the above-mentioned etched film of plasma etching of the film different from above-mentioned etched film, below, be that generating method of metal gate electrode describes to the etching of the polysilicon film take metal material as basilar memebrane.
As shown in Figure 10 (a), to make mask be hardmask (HM), make the metal material of basilar memebrane is nitrogenize tantalum film (TaN) etching polysilicon film (Poly-Si).Although use HBr or Cl as process gas in the etching of polysilicon film 2be gas Deng halogen, also can carry out etching but halogen is gas to tantalum nitride.
At this, be co-feeding gas to halogen be in gas, to generate the TaF having with the accumulating film of the nitrogenize tantalum film identical component of basilar memebrane at halogen 5gas and N 2gas.While using these gases to carry out etching, as shown in Figure 10 (b), from plasma, supply with tantalum to polysilicon film surface, still, also can remove with polysilicon film by the halogen such as Cl or Br simultaneously.Removing after polysilicon film by etching, the tantalum nitride of basilar memebrane exposes.
But, on the surface of tantalum nitride, compare the polysilicon film surface deposit that easily absorption contains tantalum nitride, therefore, as shown in Figure 10 (c), form the accumulating film that contains tantalum nitride, do not carry out the etching of tantalum nitride.In addition, need to be used for making polysilicon film shape of vertical append etching, still, owing to not carrying out the etching of tantalum nitride, therefore, can be not tantalum nitride not be caused to damage and obtains the perpendicular shape of Figure 10 (d).
Use tantalum nitride as metal material in the present embodiment, still, even in the situation that using tungsten nitride, by add WF in process gas 6and N 2also can obtain same effect.
In addition, in the present embodiment, the application examples of microwave plasma Etaching device to ECR (the Electron Cyclotron Resonance) mode that has used microwave is illustrated, but be not limited to this, also gone for using the plasma etching apparatus of the plasma creating device of capacitive coupling type, inductance coupling high type.
Above, as mentioned above, the present invention is the gas that uses the film different from etched film and can generate the accumulating film of same sample ingredient, with respect to the selectively plasma etching method of the above-mentioned etched film of plasma etching of the film different from above-mentioned etched film.Therefore, by the present invention, compared with prior art can significantly improve above-mentioned etched film with respect to from the etching selectivity of the different films of etched film.
In addition, the present invention uses the gas that can generate the accumulating film that contains Si-O key, with respect to the selectively plasma etching method of the above-mentioned etched film of plasma etching of the film different from etched film.Therefore, by the present invention, compared with prior art can significantly improve above-mentioned etched film with respect to from the etching selectivity of the different films of etched film.

Claims (11)

1. plasma etching method, it,, with respect to selectively etched film described in etching of the film different from etched film, is characterized in that,
Use can generate and contain and the composition of the described film gas with the accumulating film of sample ingredient, etched film described in plasma etching.
2. plasma etching method as claimed in claim 1, is characterized in that,
Described film is silicon oxide film, and described etched film is silicon nitride film, and described gas is for containing fluorocarbon gas, oxygen-containing gas and SiF 4the mist of gas.
3. plasma etching method as claimed in claim 2, is characterized in that,
Described fluorocarbon gas is CH 3f gas, described oxygen-containing gas is O 2gas.
4. plasma etching method as claimed in claim 2, is characterized in that,
Described mist also contains inert gas.
5. plasma etching method as claimed in claim 1, is characterized in that,
Described film is silicon oxide film, and described etched film is silicon nitride film, and described gas is for containing CH 4gas, fluoro-gas, oxygen-containing gas and SiF 4the mist of gas.
6. plasma etching method as claimed in claim 1, is characterized in that,
Described film is TaN film or WN film, and described etched film is polysilicon film, and described gas is TaF 5gas or WF 6gas.
7. plasma etching method, it,, with respect to selectively etched film described in etching of the film different from etched film, is characterized in that,
Use can generate the gas of the accumulating film that contains Si-O key, etched film described in plasma etching.
8. plasma etching method as claimed in claim 7, is characterized in that,
Described film is polysilicon film or silicon substrate, and described etched film is silicon nitride film, and described gas is for containing fluorocarbon gas, oxygen-containing gas and SiF 4the mist of gas.
9. plasma etching method as claimed in claim 8, is characterized in that,
Described fluorocarbon gas is CH 3f gas, described oxygen-containing gas is O 2gas.
10. plasma etching method as claimed in claim 8, is characterized in that,
Described mist also contains inert gas.
11. plasma etching methods as claimed in claim 7, is characterized in that,
Described film is polysilicon film or silicon substrate, and described etched film is silicon nitride film, and described gas is for containing CH 4gas, fluoro-gas, oxygen-containing gas and SiF 4the mist of gas.
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105719949A (en) * 2014-12-18 2016-06-29 朗姆研究公司 Selective Nitride Etch
CN105914146A (en) * 2015-02-23 2016-08-31 朗姆研究公司 Method for achieving ultra-high selectivity while etching silicon nitride
CN109564868A (en) * 2016-08-25 2019-04-02 日本瑞翁株式会社 Plasma-etching method
CN113544823A (en) * 2020-02-10 2021-10-22 株式会社日立高新技术 Plasma processing method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4793897A (en) * 1987-03-20 1988-12-27 Applied Materials, Inc. Selective thin film etch process
CN1224235A (en) * 1998-01-20 1999-07-28 日本电气株式会社 Anisotropic dry etching method
CN1781185A (en) * 2003-03-03 2006-05-31 兰姆研究有限公司 Method to improve profile control and N/P loading in dual doped gate applications

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4793897A (en) * 1987-03-20 1988-12-27 Applied Materials, Inc. Selective thin film etch process
CN1224235A (en) * 1998-01-20 1999-07-28 日本电气株式会社 Anisotropic dry etching method
CN1781185A (en) * 2003-03-03 2006-05-31 兰姆研究有限公司 Method to improve profile control and N/P loading in dual doped gate applications

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105719949A (en) * 2014-12-18 2016-06-29 朗姆研究公司 Selective Nitride Etch
CN105914146A (en) * 2015-02-23 2016-08-31 朗姆研究公司 Method for achieving ultra-high selectivity while etching silicon nitride
CN105914146B (en) * 2015-02-23 2019-03-15 朗姆研究公司 Method for realizing super high selectivity ratio in etching of silicon nitride
CN109564868A (en) * 2016-08-25 2019-04-02 日本瑞翁株式会社 Plasma-etching method
CN113544823A (en) * 2020-02-10 2021-10-22 株式会社日立高新技术 Plasma processing method
US11887814B2 (en) 2020-02-10 2024-01-30 Hitachi High-Tech Corporation Plasma processing method
CN113544823B (en) * 2020-02-10 2024-04-12 株式会社日立高新技术 Plasma processing method

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