WO2012043250A1 - Method and device for forming insulation film - Google Patents

Method and device for forming insulation film Download PDF

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Publication number
WO2012043250A1
WO2012043250A1 PCT/JP2011/071080 JP2011071080W WO2012043250A1 WO 2012043250 A1 WO2012043250 A1 WO 2012043250A1 JP 2011071080 W JP2011071080 W JP 2011071080W WO 2012043250 A1 WO2012043250 A1 WO 2012043250A1
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WO
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Prior art keywords
insulating film
plasma
gas
film forming
substrate
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PCT/JP2011/071080
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French (fr)
Japanese (ja)
Inventor
西森　年彦
河野　雄一
嶋津　正
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三菱重工業株式会社
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Publication of WO2012043250A1 publication Critical patent/WO2012043250A1/en

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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
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
    • H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
    • H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
    • H01L21/02271—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
    • H01L21/02274—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition in the presence of a plasma [PECVD]
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/04—Coating on selected surface areas, e.g. using masks
    • C23C16/045—Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
    • C23C16/45523—Pulsed gas flow or change of composition over time
    • 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
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
    • H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
    • H01L21/0217—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz

Definitions

  • the present invention relates to an insulating film forming apparatus and method.
  • an insulating film such as a silicon oxide film or a silicon nitride film is used, which is formed using a plasma CVD (Chemical Vapor Deposition) apparatus or the like.
  • the trench 31 (step) having a high aspect ratio (for example, 10: 1) formed in the substrate 30 the thickness of the SiN film 33 on the side wall 32 is reduced, and insulation at the reduced portion is performed. Performance deteriorates.
  • the reason why the thickness of the SiN film 33 is reduced on the side wall 32 is that the gas contributing to the film formation adheres to the side wall 32, so that the gas contributing to the film formation reaches the side wall 32 in the deep part of the trench 31. This is because the amount is reduced. Further, as shown in FIG. 9B, the higher the gas deposition probability to the side wall 32, the thinner the side wall 32 becomes.
  • SiH 4, N 2 if the film formation method of NH 3 as a raw material, in order to form a SiN film having excellent insulating properties, sticking probability is high excited species, for example, SiH 2 It is necessary to use a condition in which (NH 2 ) [adhesion probability: 0.08] occurs frequently.
  • the gas having a higher adhesion probability has a property that the film thickness on the side wall becomes thinner, and sufficient step coverage cannot be obtained (refer to Conventional Example 2 in Table 1 described later).
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide an insulating film forming apparatus and method that improve the insulation as well as the step coverage.
  • An insulating film forming apparatus for solving the above-mentioned problems is as follows.
  • a gas supply means for supplying a plurality of gases, including a main source gas containing Si and a sub-source gas not containing Si; Plasma generating means for generating plasma of the gas; Control means for controlling the gas supply means and the plasma generation means,
  • the control means includes At least the main raw material gas is supplied by the gas supply means, and the plasma generation means generates plasma containing excited species having a lower probability of adhesion to the substrate than the main excited species at the time of plasma generation, and uses the plasma
  • a film forming step for forming a precursor film on the step, After the film formation step, the auxiliary material gas is supplied by the gas supply unit, the plasma of the auxiliary material gas is generated by the plasma generation unit, and the composition ratio of Si in the precursor film is generated using the plasma.
  • the composition ratio reducing step is performed by reducing the thickness
  • An insulating film forming apparatus for solving the above-mentioned problems is as follows.
  • the control means is characterized in that the film forming step and the composition ratio decreasing step are alternately performed a plurality of times.
  • An insulating film forming apparatus for solving the above-described problem is In the insulating film forming apparatus according to the first or second invention, Furthermore, bias application means for applying a bias to the substrate, The control means includes In the composition ratio decreasing step, a bias is applied to the substrate by the bias applying means.
  • the control means includes Before the composition ratio reduction step, A rare gas is supplied by the gas supply means, a bias is applied to the substrate by the bias application means, a plasma of the rare gas is generated by the plasma generation means, and the precursor film is sputter etched using the plasma. A sputter etch process is performed.
  • the control means includes After the composition ratio reduction step, A rare gas is supplied by the gas supply means, a bias is applied to the substrate by the bias application means, a plasma of the rare gas is generated by the plasma generation means, and the insulating film is sputter etched using the plasma. A sputter etch process is performed.
  • An insulating film forming apparatus for solving the above-described problems is as follows.
  • SiH 4 is used as the main source gas
  • SiH 3 is generated as an excited species having a low adhesion probability.
  • An insulating film forming method for solving the above-described problems is as follows.
  • an insulating film forming method for forming an insulating film covering a step formed on a substrate Supplying at least the main source gas out of the main source gas containing Si and the auxiliary source gas not containing Si, and generating plasma containing excited species having a lower adhesion probability to the substrate than the main excited species at the time of plasma generation
  • a film forming step of forming a precursor film on the step using the plasma After the film forming step, the auxiliary material gas is supplied, plasma of the auxiliary material gas is generated, and the composition ratio of Si in the precursor film is reduced by using the plasma to form an insulating film. And a reduction process.
  • An insulating film forming method according to an eighth invention for solving the above-described problems is as follows.
  • the film forming step and the composition ratio decreasing step are alternately performed a plurality of times.
  • An insulating film forming method according to a ninth invention for solving the above-described problems is as follows.
  • a bias is applied to the substrate.
  • An insulating film forming method for solving the above-mentioned problems is as follows.
  • a sputter etch step of supplying a rare gas, applying a bias to the substrate, generating a plasma of the rare gas, and sputter-etching the precursor film using the plasma;
  • the sputter etching process is performed before the composition ratio decreasing process.
  • An insulating film forming method according to an eleventh invention for solving the above problem is as follows: In the insulating film forming method according to the ninth invention, A sputter etch step of supplying a rare gas, applying a bias to the substrate, generating a plasma of the rare gas, and sputter-etching the insulating film using the plasma; The sputter etching process is performed after the composition ratio decreasing process.
  • An insulating film forming method for solving the above-described problem is In the insulating film forming method according to any one of the seventh to eleventh inventions, When the insulating film is a silicon nitride film, SiH 4 is used as the main source gas, Using at least one of NH 3 or N 2 as the auxiliary source gas, SiH 3 is generated as an excited species having a low adhesion probability.
  • an insulating film having both step coverage and good insulating properties can be formed as the insulating film covering the step.
  • an insulating film having a desired film thickness can be formed on the side wall of the step.
  • the reaction rate in the composition ratio reduction step, the reaction rate can be promoted to shorten the time.
  • the film forming process in the film forming process, blockage near the entrance of the step can be prevented, and the step coverage can be further improved, and the composition ratio decreasing step after the sputter etching step The time can be shortened.
  • blockage in the vicinity of the step entrance can be prevented in the film forming process, and the step coverage can be further improved.
  • a silicon nitride film having good step coverage and high insulation can be formed as the insulating film covering the steps.
  • FIG. 3 is a time chart showing an example (Example 1) of an insulating film forming method in the insulating film forming apparatus shown in FIG.
  • FIGS. 3A and 3B are diagrams illustrating a process of forming a silicon nitride film by the insulating film forming method illustrated in FIG. 2, where FIG. 3A is a cross-sectional view of a step before formation, FIG. c) is a cross-sectional view of the step in the nitriding step, and (d) is a cross-sectional view of the step after the entire process is repeated a plurality of times.
  • FIGS. 6A and 6B are diagrams illustrating a process of forming a silicon nitride film by the insulating film forming method illustrated in FIG. 5, in which FIG. 5A is a cross-sectional view of a step in a film forming process, and FIG. (C) is sectional drawing of the level
  • FIG. 7A is a cross-sectional view of a step in a film forming process
  • FIG. (C) is sectional drawing of the level
  • (d) is sectional drawing of the level
  • step difference coverage in the conventional plasma CVD apparatus (a) is a case where a sticking probability is 0.1, (b) is a case where a sticking probability is 0.8.
  • FIG. 1 is a schematic configuration diagram showing an example of an embodiment of an insulating film forming apparatus according to the present invention.
  • the insulating film forming apparatus of this embodiment is a so-called plasma CVD apparatus.
  • the inside of a metal cylindrical vacuum chamber 1 is configured as a processing chamber 2, and a circular opening made of an insulating material is formed in the upper opening of the vacuum chamber 1.
  • a plate-like ceiling board 3 is disposed so as to close the upper opening.
  • a lower support 10 that holds the support 4 and the support 4 is provided below the vacuum chamber 1, and a substrate 5 (for example, Si wafer) made of a semiconductor material is placed on the upper surface of the support 4.
  • the vacuum chamber 1 is made of, for example, a metal such as aluminum, and the inner wall thereof is anodized, and the ceiling plate 3 is made of, for example, ceramics such as alumina.
  • a high-frequency antenna 6 made of, for example, a plurality of circular rings is disposed above the ceiling plate 3.
  • a high-frequency antenna (RF) having a frequency of several hundred kHz to several hundred MHz is connected to the high-frequency antenna 6 via a matching unit 7.
  • a power source 8 is connected (plasma generating means).
  • the vacuum chamber 1 is provided with a plurality of gas nozzles 9 for introducing a plurality of desired gases into the processing chamber 2 (gas supply means).
  • an electrode unit 11 is provided on the support table 4 that supports the substrate 5, and a low frequency (LF) power source 13 is connected to the electrode unit 11 via a matching unit 12.
  • the low frequency power supply 13 is configured to apply a lower frequency than that of the high frequency power supply 8 to the electrode portion 11 and to apply a bias power to the substrate 5 (bias applying means).
  • the support table 4 is also provided with an electrostatic chuck mechanism, and the substrate 5 can be attracted and held on the surface of the support table 4 by power supply from the electrostatic chuck power source.
  • the insulating film forming apparatus of this embodiment also includes a control device (control means) for controlling the above-described plasma generation means, gas supply means, and bias application means.
  • the insulating film forming apparatus configured as described above, by supplying RF power to the high-frequency antenna 6, electromagnetic waves are incident on the vacuum chamber 1 through the ceiling plate 3 and introduced into the vacuum chamber 1 through the gas nozzle 9. The gas is turned into plasma by the incident electromagnetic wave. And the thin film is formed on the board
  • a process gas such as silane (SiH 4 ), ammonia (NH 3 ), nitrogen (N 2 ) or the like is used.
  • the insulating film forming apparatus having the above configuration is an example, and any other structure may be used as long as it is a plasma CVD apparatus capable of performing the insulating film forming method of the present embodiment to be described later. Various configurations can be applied.
  • excited species having a low adhesion probability to the substrate surface are selected from the main source gas (containing Si) and the auxiliary source gas (containing no Si) used for forming the insulating film.
  • a precursor film having good step coverage with respect to a step is formed by generating plasma containing the plasma and performing film formation using the plasma. Thereafter, the formed precursor film is subjected to plasma processing using the plasma of the auxiliary material gas, and the Si composition ratio is reduced from the precursor film, thereby forming an insulating film having high insulating properties.
  • FIG. 3A illustrates the trench 20 formed in the substrate 5 with a depth of 10 ⁇ m and a width of 1 ⁇ m.
  • the step is not limited to the trench, and may be a step having another shape.
  • the film is not limited to a silicon nitride film, and may be a silicon oxide film (SiO film), a silicon oxynitride film (SiON film), or the like.
  • a film forming process is performed.
  • a gas nozzle 9 is used to supply SiH 4 gas (main raw material gas) and NH 3 gas (sub raw material gas) used for forming the SiN film, and plasma generating means (high frequency antenna 6, matching unit). 7.
  • SiH 3 [attachment probability: 0.05] which is an excitation species having a lower adhesion probability to the substrate 5 than SiH 2 (NH 2 ) [0.08], which is the main excitation species, is used.
  • a plasma is generated so as to include more of the excited species than the main excited species, and a precursor film 22 is formed in the trench 20 using the plasma (FIGS. 2, 3A, and 3B). )reference).
  • the precursor film 22 is Si-rich in the film composition (particularly when only the SiH 4 gas is supplied), and the insulating property is not high in that state.
  • a nitriding process (composition ratio decreasing process) is performed after the film forming process.
  • this nitriding process using a gas nozzle 9, supplying NH 3 gas by-material gas (or N 2 gas), using a plasma generating means (radio-frequency antenna 6, the matching unit 7, the high-frequency power source 8), NH A plasma of 3 gas (or N 2 gas) is generated, and the Si composition ratio is reduced by using the plasma to form the SiN film 23 (see FIGS. 2 and 3C). That is, by nitriding the precursor film 22 having good step coverage but not high insulation with NH 3 gas (or N 2 gas) plasma, the Si composition ratio is reduced, and the step coverage is improved.
  • the SiN film 23 is good and has high insulating properties.
  • a film forming process with good step coverage and a nitriding process with good insulation are alternately performed at least once to form a SiN film 23 having a desired film thickness on the side wall 21 of the trench 20. (See FIG. 3D).
  • the SiN film 23 having a desired film thickness with good step coverage and high insulation can be formed.
  • one nitriding step is 180 seconds, and the precursor film 22 is nitrided with plasma of NH 3 gas (or N 2 gas).
  • the RF power conditions at this time may be the same as the conditions in the film forming process, or may be changed as appropriate.
  • the film thickness that can be nitrided with NH 3 gas plasma is 0.3 nm
  • the film thickness that can be nitrided with N 2 gas plasma is 0.5 nm
  • N 2 gas is more NH 3 gas. Thicker film that can be nitrided than gas.
  • the experimental examples 1 to 3 of this example and the conventional examples 1 and 2 are compared with respect to the film thickness of the inner wall of the trench. At this time, using the pattern substrate on which the trench 20 was formed, both the experimental examples 1 to 3 of this example and the conventional examples 1 and 2 were formed so that the film thickness on the surface of the substrate 5 was 30 nm.
  • the film forming process and the nitriding process are alternately repeated about 60 to 100 times to form a film.
  • the thickness is 5 nm on the side wall 21 having a depth of 4 ⁇ m from the surface of the substrate 5 (FIG.
  • Example 2 This embodiment is based on the first embodiment. Therefore, the description of the present embodiment will be described with the description overlapping with that of the first embodiment, for example, the configuration of the insulating film forming apparatus and the basic portion of the insulating film forming method (film forming process, nitriding process) are omitted.
  • a bias is applied to the substrate 5 using bias applying means (electrode unit 11, matching unit 12, low frequency power supply 13) in the nitriding step described in the first embodiment.
  • bias applying means electrode unit 11, matching unit 12, low frequency power supply 13
  • ions and electrons in the plasma are irradiated to the substrate 5.
  • energy to the precursor film 22 obtained in the film forming process the nitriding reaction is promoted. ing.
  • the LF power is preferably 250 W or less, which is less affected by the sputter etch amount.
  • the nitriding rate can be increased, and the nitriding time, in other words, the nitriding step can be shortened.
  • the substrate evaluated in FIG. 4 has a diameter of 300 mm (30 cm). Therefore, when the diameter of the substrate are different, in terms of the above 250W to the LF power density (W / cm 2) per substrate area (approximately 0.35W / cm 2.), Such LF power density A bias power as described below may be applied according to the substrate diameter (substrate area).
  • Example 3 This embodiment is also based on the first embodiment. Therefore, as in the second embodiment, the description overlapping with the first embodiment is omitted, and the present embodiment will be described. Note that the present embodiment may be based on the second embodiment.
  • a sputter etch process is added between the film forming process and the nitriding process described in the first embodiment. Specifically, as shown in the time chart of FIG. 5, the sputter etch process is performed after the film formation process and before the nitriding process. This is the same even when the film forming process and the nitriding process are repeated a plurality of times.
  • a rare gas such as Ar is supplied using a gas nozzle 9, and a bias is applied to the substrate 5 using bias applying means (electrode unit 11, matching unit 12, low frequency power supply 13). Then, plasma generation means (high frequency antenna 6, matching unit 7, high frequency power supply 8) is used to generate a rare gas plasma, and the precursor film 22 obtained in the film forming process using the plasma is sputter etched. Is going.
  • the precursor film 22 is formed in the trench 20 using the film formation process described in the first embodiment (see FIG. 6A).
  • plasma containing excited species SiH 3 having a low adhesion probability is used.
  • an overhang portion 22 a is still formed in the precursor film 22 near the entrance of the trench 20.
  • it is preferable that the overhang portion 22a is small (thin film thickness is thin).
  • the overhang portion 22a is sputter-etched using a rare gas, for example, Ar gas plasma, by performing a sputter etch process after the film formation process is completed.
  • the hang portion 22a is removed to prevent the vicinity of the entrance of the trench 20 (see FIG. 6B).
  • LF 1500 W.
  • the precursor film 22 formed in the trench 20 is nitrided to form the SiN film 23 (see FIG. 6C). Then, the film forming process, the sputter etching process, and the nitriding process are performed at least once in this order to form the SiN film 23 having a desired film thickness on the side wall 21 of the trench 20 (FIG. 6 ( d)).
  • the film thickness on the side wall 21 of the trench 20 is further increased, so that the step coverage is further improved and the SiN film 23 having a desired film thickness can be formed.
  • the film thickness to be nitrided in the nitriding process is reduced, so that the time in the nitriding process can be shortened.
  • Example 4 This embodiment is also based on the first embodiment. Therefore, as in the second embodiment, the description overlapping with the first embodiment is omitted, and the present embodiment will be described. This embodiment may also be based on the second embodiment. Further, this embodiment corresponds to a modification of the third embodiment.
  • the sputter etch process is performed after the nitriding process described in the first embodiment. That is, the order of adding the sputter etch process is different from that of the third embodiment. This is the same even when the film forming process and the nitriding process are repeated a plurality of times.
  • a rare gas for example, Ar
  • a bias is applied to the substrate 5 to generate a rare gas plasma.
  • Sputter etching of the SiN film 23 obtained after the nitriding process is performed using plasma.
  • the precursor film 22 is formed in the trench 20 using the film forming process described in the first embodiment (see FIG. 8A), and then the trench 20 is formed using the nitriding process described in the first embodiment.
  • the precursor film 22 thus formed is nitrided to form a SiN film 23 (see FIG. 8B).
  • an overhang portion 22a is still formed in the precursor film 22 near the entrance of the trench 20, and in the nitriding process, Since the precursor film 22 is nitrided, an overhang portion 23 a is formed near the entrance of the trench 20. In order to further improve the step coverage, it is preferable that the overhang portion 23a is small (thin film thickness is thin).
  • the overhang portion 23a is sputter-etched by using a rare gas, for example, Ar gas plasma, by performing a sputter etch process after the nitridation process is completed.
  • the portion 23a is removed to prevent the vicinity of the entrance of the trench 20 (see FIG. 8C).
  • the sputter etching time does not have to be long, for example, about 0.1 seconds.
  • the film forming process, the nitriding process, and the sputter etching process are performed at least once in this order to form the SiN film 23 having a desired film thickness on the side wall 21 of the trench 20 (FIG. 8 ( d)).
  • the step coverage is further improved, and the SiN film 23 having a desired film thickness with high insulation can be formed.
  • the present invention is applied to a semiconductor device, and is particularly suitable as an insulating film covering a step having a high aspect ratio.

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Abstract

Provided are a device and a method for forming an insulation film having improved ability to cover a difference in level and improved insulating properties. For this purpose, when an insulation film is formed to cover a difference in level that has been formed on a substrate, the following processes are performed: a film formation process, whereby a primary raw material gas and a secondary an auxiliary raw material gas for use in forming an insulation film are supplied, a plasma is generated containing an excited species having a lower probability of adhesion with respect to the substrate than the primary excited species when the plasma is generated, and a precursor film is formed on the difference in level using said plasma; and a composition ratio reduction process (nitridation process), whereby an auxiliary raw material gas is supplied after the film formation process and a plasma of the auxiliary raw material gas is generated, and an insulation film is formed by using said plasma to reduce the primary raw material gas component of the precursor film. In addition, the film formation process and the composition ratio reduction process are performed alternately.

Description

絶縁膜形成装置及び方法Insulating film forming apparatus and method
　本発明は、絶縁膜形成装置及び方法に関する。 The present invention relates to an insulating film forming apparatus and method.
　半導体デバイス等の半導体装置では、酸化珪素膜や窒化珪素膜等の絶縁膜が用いられており、プラズマＣＶＤ（Chemical Vapor Deposition）装置等を用いて形成されている。 In a semiconductor device such as a semiconductor device, an insulating film such as a silicon oxide film or a silicon nitride film is used, which is formed using a plasma CVD (Chemical Vapor Deposition) apparatus or the like.
特開２０１０－０６７９９３号公報JP 2010-066793 A
　半導体デバイス製作に必要な段差を、絶縁膜の１つである窒化珪素膜（ＳｉＮ膜）で被覆するとき、従来のプラズマＣＶＤ装置を用いた場合、図９（ａ）に示すような段差被覆性となる。具体的には、基板３０に形成した高アスペクト比（例えば、１０：１）のトレンチ３１（段差）において、側壁３２でのＳｉＮ膜３３の膜厚が薄くなり、その薄くなった部分での絶縁性能が悪くなる。側壁３２においてＳｉＮ膜３３の膜厚が薄くなる理由は、成膜に寄与するガスが側壁３２に付着していくため、トレンチ３１の深い部分での側壁３２では、成膜に寄与するガスの到達量が減るためである。又、図９（ｂ）に示すように、ガスの側壁３２への付着確率が高いほど、側壁３２の膜厚が薄くなる性質を持つ。 When a step necessary for manufacturing a semiconductor device is covered with a silicon nitride film (SiN film) which is one of insulating films, when a conventional plasma CVD apparatus is used, the step coverage as shown in FIG. It becomes. Specifically, in the trench 31 (step) having a high aspect ratio (for example, 10: 1) formed in the substrate 30, the thickness of the SiN film 33 on the side wall 32 is reduced, and insulation at the reduced portion is performed. Performance deteriorates. The reason why the thickness of the SiN film 33 is reduced on the side wall 32 is that the gas contributing to the film formation adheres to the side wall 32, so that the gas contributing to the film formation reaches the side wall 32 in the deep part of the trench 31. This is because the amount is reduced. Further, as shown in FIG. 9B, the higher the gas deposition probability to the side wall 32, the thinner the side wall 32 becomes.
　従来のプラズマＣＶＤ装置において、ＳｉＨ4、Ｎ2、ＮＨ3を原料とする成膜方法の場合、絶縁性に優れたＳｉＮ膜を形成するためには、付着確率が高い励起種、例えば、ＳｉＨ2（ＮＨ2）［付着確率：０．０８］が多く発生する条件を用いる必要がある。しかしながら、前述したように、付着確率が高いガスほど側壁での膜厚が薄くなる性質を持ち、十分な段差被覆性を得ることはできない（後述する表１の従来例２参照）。 In the conventional plasma CVD apparatus, SiH 4, N 2, if the film formation method of NH 3 as a raw material, in order to form a SiN film having excellent insulating properties, sticking probability is high excited species, for example, SiH 2 It is necessary to use a condition in which (NH 2 ) [adhesion probability: 0.08] occurs frequently. However, as described above, the gas having a higher adhesion probability has a property that the film thickness on the side wall becomes thinner, and sufficient step coverage cannot be obtained (refer to Conventional Example 2 in Table 1 described later).
　一方、付着確率が低い励起種、例えば、ＳｉＨ3［付着確率：０．０５］を用いた場合には、段差被覆性は向上するが、膜組成がＳｉリッチとなり、絶縁性が低下する問題があった（後述する表１の従来例１参照）。 On the other hand, when an excited species having a low adhesion probability, for example, SiH 3 [adhesion probability: 0.05] is used, the step coverage is improved, but the film composition becomes Si-rich, resulting in a problem that the insulating property is lowered. (See Conventional Example 1 in Table 1 to be described later).
　このように、従来のプラズマＣＶＤ装置における成膜方法では、段差被覆性と絶縁性を両立することが難しかった。 Thus, it has been difficult to achieve both step coverage and insulation in the film forming method in the conventional plasma CVD apparatus.
　本発明は上記課題に鑑みなされたもので、段差被覆性と共に絶縁性を向上させる絶縁膜形成装置及び方法を提供することを目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to provide an insulating film forming apparatus and method that improve the insulation as well as the step coverage.
　上記課題を解決する第１の発明に係る絶縁膜形成装置は、
　基板に形成された段差を被覆する絶縁膜を形成する絶縁膜形成装置において、
　Ｓｉを含有する主原料ガスとＳｉを含有しない副原料ガスとを含めて、複数のガスを供給するガス供給手段と、
　前記ガスのプラズマを生成するプラズマ生成手段と、
　前記ガス供給手段及び前記プラズマ生成手段を制御する制御手段とを有し、
　前記制御手段は、
　前記ガス供給手段により、少なくとも前記主原料ガスを供給し、前記プラズマ生成手段により、プラズマ生成時の主な励起種より前記基板に対する付着確率が低い励起種を含むプラズマを生成し、当該プラズマを用いて前記段差へ前駆体膜を成膜する成膜工程を実施し、
　前記成膜工程の後、前記ガス供給手段により前記副原料ガスを供給し、前記プラズマ生成手段により前記副原料ガスのプラズマを生成し、当該プラズマを用いて前記前駆体膜中のＳｉの組成比を減少させて絶縁膜とする組成比減少工程を実施することを特徴とする。 An insulating film forming apparatus according to a first invention for solving the above-mentioned problems is as follows.
In an insulating film forming apparatus for forming an insulating film covering a step formed on a substrate,
A gas supply means for supplying a plurality of gases, including a main source gas containing Si and a sub-source gas not containing Si;
Plasma generating means for generating plasma of the gas;
Control means for controlling the gas supply means and the plasma generation means,
The control means includes
At least the main raw material gas is supplied by the gas supply means, and the plasma generation means generates plasma containing excited species having a lower probability of adhesion to the substrate than the main excited species at the time of plasma generation, and uses the plasma A film forming step for forming a precursor film on the step,
After the film formation step, the auxiliary material gas is supplied by the gas supply unit, the plasma of the auxiliary material gas is generated by the plasma generation unit, and the composition ratio of Si in the precursor film is generated using the plasma. The composition ratio reducing step is performed by reducing the thickness of the insulating film.
　上記課題を解決する第２の発明に係る絶縁膜形成装置は、
　上記第１の発明に記載の絶縁膜形成装置において、
　前記制御手段は、前記成膜工程と前記組成比減少工程とを交互に複数回実施することを特徴とする。 An insulating film forming apparatus according to a second invention for solving the above-mentioned problems is as follows.
In the insulating film forming apparatus according to the first invention,
The control means is characterized in that the film forming step and the composition ratio decreasing step are alternately performed a plurality of times.
　上記課題を解決する第３の発明に係る絶縁膜形成装置は、
　上記第１又は第２の発明に記載の絶縁膜形成装置において、
　更に、前記基板にバイアスを印加するバイアス印加手段を有し、
　前記制御手段は、
　前記組成比減少工程において、前記バイアス印加手段により前記基板へバイアスを印加することを特徴とする。 An insulating film forming apparatus according to a third invention for solving the above-described problem is
In the insulating film forming apparatus according to the first or second invention,
Furthermore, bias application means for applying a bias to the substrate,
The control means includes
In the composition ratio decreasing step, a bias is applied to the substrate by the bias applying means.
　上記課題を解決する第４の発明に係る絶縁膜形成装置は、
　上記第３の発明に記載の絶縁膜形成装置において、
　前記制御手段は、
　前記組成比減少工程の前に、
　前記ガス供給手段により希ガスを供給し、前記バイアス印加手段により前記基板へバイアスを印加し、前記プラズマ生成手段により前記希ガスのプラズマを生成し、当該プラズマを用いて前記前駆体膜をスパッタエッチするスパッタエッチ工程を実施することを特徴とする。 An insulating film forming apparatus according to a fourth invention for solving the above-mentioned problems is as follows.
In the insulating film forming apparatus according to the third invention,
The control means includes
Before the composition ratio reduction step,
A rare gas is supplied by the gas supply means, a bias is applied to the substrate by the bias application means, a plasma of the rare gas is generated by the plasma generation means, and the precursor film is sputter etched using the plasma. A sputter etch process is performed.
　上記課題を解決する第５の発明に係る絶縁膜形成装置は、
　上記第３の発明に記載の絶縁膜形成装置において、
　前記制御手段は、
　前記組成比減少工程の後に、
　前記ガス供給手段により希ガスを供給し、前記バイアス印加手段により前記基板へバイアスを印加し、前記プラズマ生成手段により前記希ガスのプラズマを生成し、当該プラズマを用いて前記絶縁膜をスパッタエッチするスパッタエッチ工程を実施することを特徴とする。 An insulating film forming apparatus according to a fifth invention for solving the above-mentioned problems is as follows.
In the insulating film forming apparatus according to the third invention,
The control means includes
After the composition ratio reduction step,
A rare gas is supplied by the gas supply means, a bias is applied to the substrate by the bias application means, a plasma of the rare gas is generated by the plasma generation means, and the insulating film is sputter etched using the plasma. A sputter etch process is performed.
　上記課題を解決する第６の発明に係る絶縁膜形成装置は、
　上記第１～第５のいずれか１つの発明に記載の絶縁膜形成装置において、
　前記絶縁膜が窒化珪素膜である場合、
　前記主原料ガスとしてＳｉＨ4を用い、
　前記副原料ガスとしてＮＨ3又はＮ2の少なくとも一方を用い、
　前記付着確率が低い励起種としてＳｉＨ3を生成することを特徴とする。 An insulating film forming apparatus according to a sixth invention for solving the above-described problems is as follows.
In the insulating film forming apparatus according to any one of the first to fifth inventions,
When the insulating film is a silicon nitride film,
SiH 4 is used as the main source gas,
Using at least one of NH 3 or N 2 as the auxiliary source gas,
SiH 3 is generated as an excited species having a low adhesion probability.
　上記課題を解決する第７の発明に係る絶縁膜形成方法は、
　基板に形成された段差を被覆する絶縁膜を形成する絶縁膜形成方法において、
　Ｓｉを含有する主原料ガスとＳｉを含有しない副原料ガスのうち、少なくとも前記主原料ガスを供給し、プラズマ生成時の主な励起種より前記基板に対する付着確率が低い励起種を含むプラズマを生成し、当該プラズマを用いて前記段差へ前駆体膜を成膜する成膜工程と、
　前記成膜工程の後、前記副原料ガスを供給し、前記副原料ガスのプラズマを生成し、当該プラズマを用いて前記前駆体膜中のＳｉの組成比を減少させて絶縁膜とする組成比減少工程とを有することを特徴とする。 An insulating film forming method according to a seventh invention for solving the above-described problems is as follows.
In an insulating film forming method for forming an insulating film covering a step formed on a substrate,
Supplying at least the main source gas out of the main source gas containing Si and the auxiliary source gas not containing Si, and generating plasma containing excited species having a lower adhesion probability to the substrate than the main excited species at the time of plasma generation And a film forming step of forming a precursor film on the step using the plasma,
After the film forming step, the auxiliary material gas is supplied, plasma of the auxiliary material gas is generated, and the composition ratio of Si in the precursor film is reduced by using the plasma to form an insulating film. And a reduction process.
　上記課題を解決する第８の発明に係る絶縁膜形成方法は、
　上記第７の発明に記載の絶縁膜形成方法において、
　前記成膜工程と前記組成比減少工程とを交互に複数回実施することを特徴とする。 An insulating film forming method according to an eighth invention for solving the above-described problems is as follows.
In the insulating film forming method according to the seventh invention,
The film forming step and the composition ratio decreasing step are alternately performed a plurality of times.
　上記課題を解決する第９の発明に係る絶縁膜形成方法は、
　上記第７又は第８の発明に記載の絶縁膜形成方法において、
　前記組成比減少工程において、前記基板へバイアスを印加することを特徴とする。 An insulating film forming method according to a ninth invention for solving the above-described problems is as follows.
In the insulating film forming method according to the seventh or eighth invention,
In the composition ratio reduction step, a bias is applied to the substrate.
　上記課題を解決する第１０の発明に係る絶縁膜形成方法は、
　上記第９の発明に記載の絶縁膜形成方法において、
　希ガスを供給し、前記基板へバイアスを印加し、前記希ガスのプラズマを生成し、当該プラズマを用いて前記前駆体膜をスパッタエッチするスパッタエッチ工程を更に有し、
　前記組成比減少工程の前に前記スパッタエッチ工程を実施することを特徴とする。 An insulating film forming method according to a tenth invention for solving the above-mentioned problems is as follows.
In the insulating film forming method according to the ninth invention,
A sputter etch step of supplying a rare gas, applying a bias to the substrate, generating a plasma of the rare gas, and sputter-etching the precursor film using the plasma;
The sputter etching process is performed before the composition ratio decreasing process.
　上記課題を解決する第１１の発明に係る絶縁膜形成方法は、
　上記第９の発明に記載の絶縁膜形成方法において、
　希ガスを供給し、前記基板へバイアスを印加し、前記希ガスのプラズマを生成し、当該プラズマを用いて前記絶縁膜をスパッタエッチするスパッタエッチ工程を更に有し、
　前記組成比減少工程の後に前記スパッタエッチ工程を実施することを特徴とする。 An insulating film forming method according to an eleventh invention for solving the above problem is as follows:
In the insulating film forming method according to the ninth invention,
A sputter etch step of supplying a rare gas, applying a bias to the substrate, generating a plasma of the rare gas, and sputter-etching the insulating film using the plasma;
The sputter etching process is performed after the composition ratio decreasing process.
　上記課題を解決する第１２の発明に係る絶縁膜形成方法は、
　上記第７～第１１のいずれか１つの発明に記載の絶縁膜形成方法において、
　前記絶縁膜が窒化珪素膜である場合、
　前記主原料ガスとしてＳｉＨ4を用い、
　前記副原料ガスとしてＮＨ3又はＮ2の少なくとも一方を用い、
　前記付着確率が低い励起種としてＳｉＨ3を生成することを特徴とする。 An insulating film forming method according to a twelfth invention for solving the above-described problem is
In the insulating film forming method according to any one of the seventh to eleventh inventions,
When the insulating film is a silicon nitride film,
SiH 4 is used as the main source gas,
Using at least one of NH 3 or N 2 as the auxiliary source gas,
SiH 3 is generated as an excited species having a low adhesion probability.
　第１、第７の発明によれば、段差を被覆する絶縁膜として、段差被覆性と良好な絶縁性を両立する絶縁膜を形成することができる。 According to the first and seventh aspects of the invention, an insulating film having both step coverage and good insulating properties can be formed as the insulating film covering the step.
　第２、第８の発明によれば、段差の側壁において、所望の膜厚の絶縁膜を形成することができる。 According to the second and eighth inventions, an insulating film having a desired film thickness can be formed on the side wall of the step.
　第３、第９の発明によれば、組成比減少工程において、その反応速度を促進して、時間短縮を図ることができる。 According to the third and ninth inventions, in the composition ratio reduction step, the reaction rate can be promoted to shorten the time.
　第４、第１０の発明によれば、成膜の過程において、段差の入口付近の閉塞を防止して、段差被覆性を更に向上させることができ、又、スパッタエッチ工程後の組成比減少工程において、時間短縮を図ることができる。 According to the fourth and tenth aspects of the present invention, in the film forming process, blockage near the entrance of the step can be prevented, and the step coverage can be further improved, and the composition ratio decreasing step after the sputter etching step The time can be shortened.
　第５、第１１の発明によれば、成膜の過程において、段差の入口付近の閉塞を防止して、段差被覆性を更に向上させることができる。 According to the fifth and eleventh inventions, blockage in the vicinity of the step entrance can be prevented in the film forming process, and the step coverage can be further improved.
　第６、第１２の発明によれば、段差を被覆する絶縁膜として、段差被覆性がよく、絶縁性も高い窒化珪素膜を形成することができる。 According to the sixth and twelfth inventions, a silicon nitride film having good step coverage and high insulation can be formed as the insulating film covering the steps.
本発明に係る絶縁膜形成装置の実施形態の一例を示す概略構成図である。It is a schematic structure figure showing an example of an embodiment of an insulating film formation device concerning the present invention. 図１に示した絶縁膜形成装置における絶縁膜形成方法の一例（実施例１）を示すタイムチャートである。3 is a time chart showing an example (Example 1) of an insulating film forming method in the insulating film forming apparatus shown in FIG. 図２に示した絶縁膜形成方法による窒化珪素膜の形成過程を説明する図であり、（ａ）は形成前の段差の断面図、（ｂ）は成膜工程での段差の断面図、（ｃ）は窒化工程での段差の断面図、（ｄ）は全工程を複数回繰り返した後の段差の断面図である。FIGS. 3A and 3B are diagrams illustrating a process of forming a silicon nitride film by the insulating film forming method illustrated in FIG. 2, where FIG. 3A is a cross-sectional view of a step before formation, FIG. c) is a cross-sectional view of the step in the nitriding step, and (d) is a cross-sectional view of the step after the entire process is repeated a plurality of times. 本発明に係る絶縁膜形成方法の他の一例（実施例２）を説明するグラフである。It is a graph explaining another example (Example 2) of the insulating film formation method which concerns on this invention. 本発明に係る絶縁膜形成方法の他の一例（実施例３）を説明するタイムチャートである。It is a time chart explaining other examples (Example 3) of the insulating film formation method which concerns on this invention. 図５に示した絶縁膜形成方法による窒化珪素膜の形成過程を説明する図であり、（ａ）は成膜工程での段差の断面図、（ｂ）はスパッタエッチ工程での段差の断面図、（ｃ）は窒化工程での段差の断面図、（ｄ）は全工程を複数回繰り返した後の段差の断面図である。FIGS. 6A and 6B are diagrams illustrating a process of forming a silicon nitride film by the insulating film forming method illustrated in FIG. 5, in which FIG. 5A is a cross-sectional view of a step in a film forming process, and FIG. (C) is sectional drawing of the level | step difference in a nitriding process, (d) is sectional drawing of the level | step difference after repeating all the processes in multiple times. 本発明に係る絶縁膜形成方法の他の一例（実施例４）を説明するタイムチャートである。It is a time chart explaining other examples (Example 4) of the insulating film formation method concerning this invention. 図７に示した絶縁膜形成方法による窒化珪素膜の形成過程を説明する図であり、（ａ）は成膜工程での段差の断面図、（ｂ）は窒化工程での段差の断面図、（ｃ）はスパッタエッチ工程での段差の断面図、（ｄ）は全工程を複数回繰り返した後の段差の断面図である。8A and 8B are diagrams illustrating a process of forming a silicon nitride film by the insulating film forming method illustrated in FIG. 7, in which FIG. 7A is a cross-sectional view of a step in a film forming process, and FIG. (C) is sectional drawing of the level | step difference in a sputter etching process, (d) is sectional drawing of the level | step difference after repeating all the processes in multiple times. 従来のプラズマＣＶＤ装置における段差被覆性を説明する図であり、（ａ）は付着確率が０．１の場合、（ｂ）は付着確率が０．８の場合である。It is a figure explaining the level | step difference coverage in the conventional plasma CVD apparatus, (a) is a case where a sticking probability is 0.1, (b) is a case where a sticking probability is 0.8.
　以下、図１～図８を参照して、本発明に係る絶縁膜形成装置及び形成方法の実施形態について説明を行う。 Hereinafter, embodiments of an insulating film forming apparatus and a forming method according to the present invention will be described with reference to FIGS.
（実施例１）
　図１は、本発明に係る絶縁膜形成装置の実施形態の一例を示す概略構成図である。
　本実施例の絶縁膜形成装置は、所謂、プラズマＣＶＤ装置である。具体的には、図１に示すように、金属製の円筒状の真空チャンバ１の内部が処理室２として構成されるものであり、真空チャンバ１の上部開口部には、絶縁材料からなる円板状の天井板３が、上部開口部を閉鎖するように配設されている。又、真空チャンバ１の下部には支持台４及び支持台４を保持する下部支持台１０が備えられ、半導体材料からなる基板５（例えば、Ｓｉウェハ）が支持台４の上面に載置される。真空チャンバ１は、例えば、アルミニウム等の金属から構成されて、その内壁がアルマイト処理されており、又、天井板３は、例えば、アルミナ等のセラミクスにより構成されている。 Example 1
FIG. 1 is a schematic configuration diagram showing an example of an embodiment of an insulating film forming apparatus according to the present invention.
The insulating film forming apparatus of this embodiment is a so-called plasma CVD apparatus. Specifically, as shown in FIG. 1, the inside of a metal cylindrical vacuum chamber 1 is configured as a processing chamber 2, and a circular opening made of an insulating material is formed in the upper opening of the vacuum chamber 1. A plate-like ceiling board 3 is disposed so as to close the upper opening. A lower support 10 that holds the support 4 and the support 4 is provided below the vacuum chamber 1, and a substrate 5 (for example, Si wafer) made of a semiconductor material is placed on the upper surface of the support 4. . The vacuum chamber 1 is made of, for example, a metal such as aluminum, and the inner wall thereof is anodized, and the ceiling plate 3 is made of, for example, ceramics such as alumina.
　天井板３の上方には、例えば、複数の円形リングからなる高周波アンテナ６が配置されており、高周波アンテナ６には整合器７を介して、数百ｋＨｚ～数百ＭＨｚの周波数の高周波（ＲＦ）電源８が接続されている（プラズマ生成手段）。又、真空チャンバ１には、処理室２内に所望の複数のガスを導入する複数のガスノズル９が設けられている（ガス供給手段）。 A high-frequency antenna 6 made of, for example, a plurality of circular rings is disposed above the ceiling plate 3. A high-frequency antenna (RF) having a frequency of several hundred kHz to several hundred MHz is connected to the high-frequency antenna 6 via a matching unit 7. ) A power source 8 is connected (plasma generating means). The vacuum chamber 1 is provided with a plurality of gas nozzles 9 for introducing a plurality of desired gases into the processing chamber 2 (gas supply means).
　又、基板５を支持する支持台４には、電極部１１が設けられており、電極部１１には整合器１２を介して低周波（ＬＦ）電源１３が接続されている。低周波電源１３は、高周波電源８より低い周波数を電極部１１に印加し、基板５にバイアス電力を印加できるようになっている（バイアス印加手段）。なお、図示は省略しているが、支持台４には、静電チャック機構も設けられており、静電チャック用電源からの給電により、基板５を支持台４表面に吸着保持できるようになっている。加えて、図示は省略しているが、本実施例の絶縁膜形成装置は、上述したプラズマ生成手段、ガス供給手段、バイアス印加手段を制御する制御装置（制御手段）も備えている。 In addition, an electrode unit 11 is provided on the support table 4 that supports the substrate 5, and a low frequency (LF) power source 13 is connected to the electrode unit 11 via a matching unit 12. The low frequency power supply 13 is configured to apply a lower frequency than that of the high frequency power supply 8 to the electrode portion 11 and to apply a bias power to the substrate 5 (bias applying means). Although not shown, the support table 4 is also provided with an electrostatic chuck mechanism, and the substrate 5 can be attracted and held on the surface of the support table 4 by power supply from the electrostatic chuck power source. ing. In addition, although not shown, the insulating film forming apparatus of this embodiment also includes a control device (control means) for controlling the above-described plasma generation means, gas supply means, and bias application means.
　上記構成の絶縁膜形成装置では、高周波アンテナ６にＲＦパワーを供給することにより、天井板３を介して電磁波が真空チャンバ１に入射され、ガスノズル９を介して真空チャンバ１内に導入されたプロセスガスが、入射された電磁波によりプラズマ化されている。そして、プラズマ化されたプロセスガスを用いて、基板５上に薄膜を形成している。例えば、ＳｉＮ膜を成膜する場合には、シラン（ＳｉＨ4）、アンモニア（ＮＨ3）、窒素（Ｎ2）等のプロセスガスが用いられる。 In the insulating film forming apparatus configured as described above, by supplying RF power to the high-frequency antenna 6, electromagnetic waves are incident on the vacuum chamber 1 through the ceiling plate 3 and introduced into the vacuum chamber 1 through the gas nozzle 9. The gas is turned into plasma by the incident electromagnetic wave. And the thin film is formed on the board | substrate 5 using the process gas converted into plasma. For example, when forming a SiN film, a process gas such as silane (SiH 4 ), ammonia (NH 3 ), nitrogen (N 2 ) or the like is used.
　なお、上記構成の絶縁膜形成装置は一例であり、後述する本実施例の絶縁膜形成方法を実施できるプラズマＣＶＤ装置であれば、他の構成でもよく、例えば、プラズマ生成手段やガス供給手段等は様々な態様の構成が適用可能である。 The insulating film forming apparatus having the above configuration is an example, and any other structure may be used as long as it is a plasma CVD apparatus capable of performing the insulating film forming method of the present embodiment to be described later. Various configurations can be applied.
　次に、本実施例の絶縁膜形成方法について説明する。
　本実施例においては、半導体デバイスにおける高アスペクト比の段差（例えば、トレンチ等）に対して、段差被覆性と良好な絶縁性を両立する絶縁膜を形成するため、概略して、次のような工夫を行っている。具体的には、まず、上記構成の絶縁膜形成装置において、絶縁膜の形成に用いる主原料ガス（Ｓｉ含有）と副原料ガス（Ｓｉ非含有）から、基板表面に対する付着確率が低い励起種を含むプラズマを生成し、当該プラズマを用いて成膜を行うことで、段差への段差被覆性の良い前駆体膜を形成している。その後、副原料ガスのプラズマを用いて、形成した前駆体膜をプラズマ処理し、前駆体膜からＳｉの組成比を減少させることにより、絶縁性の高い絶縁膜としている。 Next, the insulating film forming method of this embodiment will be described.
In this embodiment, in order to form an insulating film that achieves both step coverage and good insulation for a step with a high aspect ratio in a semiconductor device (for example, a trench), the following outline is given. I'm doing some ingenuity. Specifically, first, in the insulating film forming apparatus having the above-described configuration, excited species having a low adhesion probability to the substrate surface are selected from the main source gas (containing Si) and the auxiliary source gas (containing no Si) used for forming the insulating film. A precursor film having good step coverage with respect to a step is formed by generating plasma containing the plasma and performing film formation using the plasma. Thereafter, the formed precursor film is subjected to plasma processing using the plasma of the auxiliary material gas, and the Si composition ratio is reduced from the precursor film, thereby forming an insulating film having high insulating properties.
　以降、一例として、段差をトレンチ（アスペクト比＝１０：１）とし、絶縁膜を窒化珪素膜（ＳｉＮ膜）とする場合について、図２のタイムチャート、図３の断面図を参照して、本実施例の絶縁膜形成方法を詳細に説明する。なお、図３（ａ）には、基板５に深さ１０μｍ、幅１μｍで形成したトレンチ２０を例示しているが、段差は、トレンチに限らず、他の形状の段差でもよく、又、絶縁膜も、窒化珪素膜に限らず、例えば、酸化珪素膜（ＳｉＯ膜）や酸化窒化珪素膜（ＳｉＯＮ膜）等でもよい。 Hereinafter, as an example, the case where the step is a trench (aspect ratio = 10: 1) and the insulating film is a silicon nitride film (SiN film) is described with reference to the time chart of FIG. 2 and the cross-sectional view of FIG. The method for forming the insulating film of the example will be described in detail. FIG. 3A illustrates the trench 20 formed in the substrate 5 with a depth of 10 μm and a width of 1 μm. However, the step is not limited to the trench, and may be a step having another shape. The film is not limited to a silicon nitride film, and may be a silicon oxide film (SiO film), a silicon oxynitride film (SiON film), or the like.
　本実施例の絶縁膜形成方法においては、まず、成膜工程を実施している。
　この成膜工程では、ガスノズル９を用いて、ＳｉＮ膜の形成に用いるＳｉＨ4ガス（主原料ガス）とＮＨ3ガス（副原料ガス）とを供給し、プラズマ生成手段（高周波アンテナ６、整合器７、高周波電源８）を用いて、主な励起種であるＳｉＨ2（ＮＨ2）［０．０８］より基板５に対する付着確率が低い励起種であるＳｉＨ3［付着確率：０．０５］を生成すると共に、この励起種を主な励起種より多く含むようにプラズマを生成し、当該プラズマを用いてトレンチ２０へ前駆体膜２２を成膜する（図２及び図３（ａ）、（ｂ）参照）。 In the insulating film forming method of this embodiment, first, a film forming process is performed.
In this film forming process, a gas nozzle 9 is used to supply SiH 4 gas (main raw material gas) and NH 3 gas (sub raw material gas) used for forming the SiN film, and plasma generating means (high frequency antenna 6, matching unit). 7. Using a high-frequency power source 8), SiH 3 [attachment probability: 0.05], which is an excitation species having a lower adhesion probability to the substrate 5 than SiH 2 (NH 2 ) [0.08], which is the main excitation species, is used. At the same time, a plasma is generated so as to include more of the excited species than the main excited species, and a precursor film 22 is formed in the trench 20 using the plasma (FIGS. 2, 3A, and 3B). )reference).
　このとき、付着確率が低い励起種ＳｉＨ3を多く含むプラズマを生成することが重要であり、励起種ＳｉＨ3を多く生成できれば、後述する表１に示すように、ＳｉＨ4ガスだけ供給してもよい。又、ＮＨ3ガスに換えて、Ｎ2ガスを供給するようにしてもよいし、ＮＨ3ガスと共にＮ2ガスを供給するようにしてもよい。 At this time, it is important to generate a plasma containing a large amount of excited species SiH 3 having a low adhesion probability. If a large amount of excited species SiH 3 can be generated, even if only SiH 4 gas is supplied as shown in Table 1 described later. Good. Further, in place of the NH 3 gas, may be supplied with N 2 gas, may be supplied with N 2 gas with NH 3 gas.
　この成膜工程では、付着確率が低い励起種ＳｉＨ3を含むプラズマを用いているので、トレンチ２０の深い部分の側壁２１において、成膜に寄与する励起種ＳｉＨ3の到達量の減少を抑制することができ、その結果、側壁２１に成膜される前駆体膜２２の膜厚の減少も抑制することになり、段差被覆性を向上させることができる（図３（ａ）、（ｂ）参照）。しかしながら、この前駆体膜２２は、膜組成がＳｉリッチであり（特に、ＳｉＨ4ガスだけ供給して成膜した場合）、その状態のままでは絶縁性が高くない。 In this film forming process, plasma containing excited species SiH 3 having a low adhesion probability is used, so that a decrease in the amount of excited species SiH 3 contributing to film formation on the side wall 21 in the deep portion of the trench 20 is suppressed. As a result, a decrease in the film thickness of the precursor film 22 formed on the side wall 21 is also suppressed, and the step coverage can be improved (see FIGS. 3A and 3B). ). However, the precursor film 22 is Si-rich in the film composition (particularly when only the SiH 4 gas is supplied), and the insulating property is not high in that state.
　そこで、本実施例の絶縁膜形成方法においては、成膜工程の後、窒化工程（組成比減少工程）を実施している。
　この窒化工程では、ガスノズル９を用いて、副原料ガスであるＮＨ3ガス（又はＮ2ガス）を供給し、プラズマ生成手段（高周波アンテナ６、整合器７、高周波電源８）を用いて、ＮＨ3ガス（又はＮ2ガス）のプラズマを生成し、当該プラズマを用いて前駆体膜２２中のＳｉの組成比を減少させてＳｉＮ膜２３としている（図２及び図３（ｃ）参照）。つまり、段差被覆性はよいが、絶縁性が高くない前駆体膜２２を、ＮＨ3ガス（又はＮ2ガス）のプラズマで窒化することにより、Ｓｉの組成比を減少させて、段差被覆性がよく、絶縁性も高いＳｉＮ膜２３としている。 Therefore, in the insulating film forming method of this embodiment, a nitriding process (composition ratio decreasing process) is performed after the film forming process.
In this nitriding process, using a gas nozzle 9, supplying NH 3 gas by-material gas (or N 2 gas), using a plasma generating means (radio-frequency antenna 6, the matching unit 7, the high-frequency power source 8), NH A plasma of 3 gas (or N 2 gas) is generated, and the Si composition ratio is reduced by using the plasma to form the SiN film 23 (see FIGS. 2 and 3C). That is, by nitriding the precursor film 22 having good step coverage but not high insulation with NH 3 gas (or N 2 gas) plasma, the Si composition ratio is reduced, and the step coverage is improved. The SiN film 23 is good and has high insulating properties.
　そして、段差被覆性が良好な成膜工程、絶縁性が良好な窒化工程を交互に少なくとも１回以上実施して、トレンチ２０の側壁２１における膜厚が所望の膜厚となるＳｉＮ膜２３を形成することになる（図３（ｄ）参照）。上述した工程を経ることにより、段差被覆性がよく、絶縁性も高い所望の膜厚のＳｉＮ膜２３を成膜することができる。 Then, a film forming process with good step coverage and a nitriding process with good insulation are alternately performed at least once to form a SiN film 23 having a desired film thickness on the side wall 21 of the trench 20. (See FIG. 3D). By passing through the process mentioned above, the SiN film 23 having a desired film thickness with good step coverage and high insulation can be formed.
　本実施例のプロセス条件のいくつかを後述する表１の実験例１～３に例示して説明する。１回の成膜工程は２秒であり、この間に０．１ｎｍの膜厚の前駆体膜２２が成膜される。又、表１の実験例１～３に示すように、成膜工程におけるＲＦパワーの条件を、各々、０．５ｋＷ、１．５ｋＷ、４ｋＷとし、ガス流量比［ＮＨ3／（ＳｉＨ4＋ＮＨ3）］を、各々、０以上０．２以下、０以上０．３５以下、０以上０．５以下とした。なお、実験例１～３では、ガス流量比を変更する際には、ＳｉＨ4ガス＝６０ｓｃｃｍの流量に固定し、ＮＨ3ガスの流量を変更した。 Some of the process conditions of this example are illustrated and described in Experimental Examples 1 to 3 in Table 1 to be described later. One film formation process takes 2 seconds, and a precursor film 22 having a thickness of 0.1 nm is formed during this process. Further, as shown in Experimental Examples 1 to 3 in Table 1, the RF power conditions in the film forming process are 0.5 kW, 1.5 kW, and 4 kW, respectively, and the gas flow rate ratio [NH 3 / (SiH 4 + NH 3 )] Was set to 0 or more and 0.2 or less, 0 or more and 0.35 or less, and 0 or more and 0.5 or less, respectively. Incidentally, in Examples 1 to 3, when changing the gas flow ratio was fixed to the flow rate of SiH 4 gas = 60 sccm, it was changed flow rate of the NH 3 gas.
　又、１回の窒化工程は１８０秒であり、ＮＨ3ガス（又はＮ2ガス）のプラズマで前駆体膜２２の窒化を行った。このときのＲＦパワーの条件は、成膜工程における条件と同様でよいし、適宜変更してもよい。又、ＮＨ3ガス（又はＮ2ガス）の流量の条件は、成膜工程において使用していれば、そのままの流量でもよいが、ＳｉＨ4ガスのみだった場合には、ＮＨ3ガス（又はＮ2ガス）を適宜な流量で供給する必要がある。なお、同等の条件の場合、ＮＨ3ガスのプラズマで窒化できる膜厚は０．３ｎｍであり、Ｎ2ガスのプラズマで窒化できる膜厚は０．５ｎｍであり、Ｎ2ガスの方がＮＨ3ガスよりも窒化できる膜厚が厚い。 Further, one nitriding step is 180 seconds, and the precursor film 22 is nitrided with plasma of NH 3 gas (or N 2 gas). The RF power conditions at this time may be the same as the conditions in the film forming process, or may be changed as appropriate. Further, the flow rate conditions of the NH 3 gas (or N 2 gas), if used in the film forming step, in the case may be as flow rate, was only SiH 4 gas, NH 3 gas (or N 2 gas) must be supplied at an appropriate flow rate. Under the same conditions, the film thickness that can be nitrided with NH 3 gas plasma is 0.3 nm, the film thickness that can be nitrided with N 2 gas plasma is 0.5 nm, and N 2 gas is more NH 3 gas. Thicker film that can be nitrided than gas.
　トレンチ内壁の膜厚について、本実施例の実験例１～３と従来例１、２とを比較する。このとき、トレンチ２０が形成されたパターン基板を用い、本実施例の実験例１～３も従来例１、２も、共に、基板５の表面における膜厚が３０ｎｍとなるように成膜した。本実施例の実験例１～３の場合、上記成膜工程及び窒化工程を交互に６０～１００回程度繰り返し行って成膜している。そして、成膜により得られた膜の断面構造を調べてみると、従来例では、基板５の表面から４μｍの深さの側壁２１において、５ｎｍの膜厚であるのに対して（図３（ｄ）の点線２４、表１の従来例２参照）、本実施例では、基板５の表面から４μｍの深さの側壁２１において、７ｎｍの膜厚であり、段差被覆性がよいことが確認できた（図３（ｄ）、表１の実験例１～３参照）。 The experimental examples 1 to 3 of this example and the conventional examples 1 and 2 are compared with respect to the film thickness of the inner wall of the trench. At this time, using the pattern substrate on which the trench 20 was formed, both the experimental examples 1 to 3 of this example and the conventional examples 1 and 2 were formed so that the film thickness on the surface of the substrate 5 was 30 nm. In Experimental Examples 1 to 3 of this example, the film forming process and the nitriding process are alternately repeated about 60 to 100 times to form a film. When the cross-sectional structure of the film obtained by the film formation is examined, in the conventional example, the thickness is 5 nm on the side wall 21 having a depth of 4 μm from the surface of the substrate 5 (FIG. 3 ( d) (see dotted line 24 in Table 1 and Conventional Example 2 in Table 1) In this example, it can be confirmed that the film thickness is 7 nm on the side wall 21 having a depth of 4 μm from the surface of the substrate 5 and the step coverage is good. (See FIG. 3 (d), Experimental Examples 1 to 3 in Table 1).
　又、絶縁性についても比較したところ（平面基板にＳｉＮ膜を成膜して膜抵抗を評価）、本実施例の場合、いずれも１×１０14Ω・ｍであり、表１に示す従来例１、２と比較して、絶縁性も高いことが確認できた（表１の実験例１～３、従来例１、２参照）。 In addition, when the insulating properties were compared (film resistance was evaluated by forming a SiN film on a flat substrate), in the case of this example, all were 1 × 10 14 Ω · m, and the conventional examples shown in Table 1 were used. It was confirmed that the insulation was higher than those of 1 and 2 (see Experimental Examples 1 to 3 and Conventional Examples 1 and 2 in Table 1).
　なお、表１には、本実施例の実験例１～３、従来例１、２と共に、比較例１、２として、本実施例の成膜工程のみでの成膜、即ち、本実施例の窒化工程がない成膜も行っており、この成膜により得られた膜についても、段差被覆性、絶縁性を評価した。比較例１、２においても、従来例１、２と同様に、段差被覆性と良好な絶縁性は両立していない。これに対して、本実施例では、実験例１～３に示すように、段差被覆性と良好な絶縁性が両立可能である。 In Table 1, the experimental examples 1 to 3 of this example and the conventional examples 1 and 2 as well as the comparative examples 1 and 2, the film formation only in the film forming process of this example, that is, of this example Film formation without a nitriding step was also performed, and the step coverage and insulating properties of the film obtained by this film formation were also evaluated. In Comparative Examples 1 and 2, similarly to Conventional Examples 1 and 2, the step coverage and good insulation are not compatible. On the other hand, in this embodiment, as shown in Experimental Examples 1 to 3, both step coverage and good insulation can be achieved.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
（実施例２）
　本実施例は、上記実施例１を前提とするものである。従って、実施例１と重複する説明、例えば、絶縁膜形成装置の構成や絶縁膜形成方法（成膜工程、窒化工程）の基本的な部分等は省略して、本実施例の説明を行う。 (Example 2)
This embodiment is based on the first embodiment. Therefore, the description of the present embodiment will be described with the description overlapping with that of the first embodiment, for example, the configuration of the insulating film forming apparatus and the basic portion of the insulating film forming method (film forming process, nitriding process) are omitted.
　本実施例では、実施例１で説明した窒化工程において、バイアス印加手段（電極部１１、整合器１２、低周波電源１３）を用いて、基板５にバイアスを印加している。基板５にバイアスを印加することにより、プラズマ中のイオンや電子を基板５へ照射するようにしており、成膜工程で得られた前駆体膜２２にエネルギーを与えることで、窒化反応を促進している。 In this embodiment, a bias is applied to the substrate 5 using bias applying means (electrode unit 11, matching unit 12, low frequency power supply 13) in the nitriding step described in the first embodiment. By applying a bias to the substrate 5, ions and electrons in the plasma are irradiated to the substrate 5. By applying energy to the precursor film 22 obtained in the film forming process, the nitriding reaction is promoted. ing.
　図４は、ＬＦ＝０Ｗ、即ち、基板５にバイアスを印加しない場合の窒化速度を１とし、各ＬＦパワーにおける窒化速度を規格化したグラフである。図４に示すように、ＬＦ＝３０Ｗ、６０Ｗ、１８０Ｗの場合、ＬＦ＝０Ｗの場合よりも窒化速度が速いことがわかる。一方、ＬＦ＝２５０Ｗの場合、ＬＦ＝０Ｗの場合と同等の窒化速度であり、ＬＦ＝３００Ｗの場合、ＬＦ＝０Ｗの場合よりも窒化速度が遅くなっている。これは、ＬＦパワーが大きくなると、スパッタエッチ量が増えて、窒化速度に寄与しなくなってくるためである。従って、ＬＦパワーとしては、スパッタエッチ量の影響が小さい、２５０Ｗ以下が望ましい。このように、窒化工程において、基板５にバイアスを印加することにより、窒化速度を速くすることができ、窒化時間、換言すれば、窒化工程の時間を短縮することができる。例えば、ＬＦ＝３０Ｗの場合、窒化速度はＬＦ＝０Ｗの場合の約１．１倍であり、１０％程度の時間短縮が可能である。 FIG. 4 is a graph obtained by standardizing the nitriding rate at each LF power, assuming that LF = 0 W, that is, the nitriding rate when the bias is not applied to the substrate 5 is 1. FIG. As shown in FIG. 4, it can be seen that the nitriding rate is faster when LF = 30 W, 60 W, and 180 W than when LF = 0 W. On the other hand, when LF = 250 W, the nitriding rate is the same as when LF = 0 W, and when LF = 300 W, the nitriding rate is slower than when LF = 0 W. This is because as the LF power increases, the amount of sputter etch increases and does not contribute to the nitriding rate. Accordingly, the LF power is preferably 250 W or less, which is less affected by the sputter etch amount. Thus, in the nitriding step, by applying a bias to the substrate 5, the nitriding rate can be increased, and the nitriding time, in other words, the nitriding step can be shortened. For example, when LF = 30 W, the nitriding rate is about 1.1 times that when LF = 0 W, and the time can be reduced by about 10%.
　なお、図４において評価した基板は３００ｍｍ（３０ｃｍ）径である。従って、基板の径が異なる場合には、上記の２５０Ｗを基板面積当たりのＬＦパワー密度（Ｗ／ｃｍ2）に換算し（約０．３５Ｗ／ｃｍ2となる。）、このようなＬＦパワー密度以下となるようなバイアスパワーを、基板径（基板面積）に応じて印加すればよい。 Note that the substrate evaluated in FIG. 4 has a diameter of 300 mm (30 cm). Therefore, when the diameter of the substrate are different, in terms of the above 250W to the LF power density (W / cm 2) per substrate area (approximately 0.35W / cm 2.), Such LF power density A bias power as described below may be applied according to the substrate diameter (substrate area).
（実施例３）
　本実施例も、上記実施例１を前提とするものである。従って、実施例２と同様に、実施例１と重複する説明は省略して、本実施例の説明を行う。なお、本実施例は、実施例２を前提としてもよい。 (Example 3)
This embodiment is also based on the first embodiment. Therefore, as in the second embodiment, the description overlapping with the first embodiment is omitted, and the present embodiment will be described. Note that the present embodiment may be based on the second embodiment.
　本実施例では、実施例１で説明した成膜工程と窒化工程の間にスパッタエッチ工程を追加している。具体的には、図５のタイムチャートに示すように、成膜工程の終了後、窒化工程を実施する前に、スパッタエッチ工程を実施している。これは、成膜工程及び窒化工程を複数回繰り返す場合でも同様である。 In this embodiment, a sputter etch process is added between the film forming process and the nitriding process described in the first embodiment. Specifically, as shown in the time chart of FIG. 5, the sputter etch process is performed after the film formation process and before the nitriding process. This is the same even when the film forming process and the nitriding process are repeated a plurality of times.
　このスパッタエッチ工程では、ガスノズル９を用いて、希ガス、例えば、Ａｒ等を供給し、バイアス印加手段（電極部１１、整合器１２、低周波電源１３）を用いて、基板５にバイアスを印加し、プラズマ生成手段（高周波アンテナ６、整合器７、高周波電源８）を用いて、希ガスのプラズマを生成し、当該プラズマを用いて成膜工程で得られた前駆体膜２２のスパッタエッチを行っている。 In this sputter etching process, a rare gas such as Ar is supplied using a gas nozzle 9, and a bias is applied to the substrate 5 using bias applying means (electrode unit 11, matching unit 12, low frequency power supply 13). Then, plasma generation means (high frequency antenna 6, matching unit 7, high frequency power supply 8) is used to generate a rare gas plasma, and the precursor film 22 obtained in the film forming process using the plasma is sputter etched. Is going.
　図５に示す各工程について、図６を参照して説明する。実施例１で説明した成膜工程を用いて、トレンチ２０に前駆体膜２２を成膜する（図６（ａ）参照）。この成膜工程では、付着確率が低い励起種ＳｉＨ3を含むプラズマを用いているが、それでも、トレンチ２０の入口付近の前駆体膜２２にはオーバーハング部分２２ａが形成されてしまう。更に段差被覆性を向上させるためには、このオーバーハング部分２２ａが小さい（膜厚が薄い）方がよい。 Each step shown in FIG. 5 will be described with reference to FIG. The precursor film 22 is formed in the trench 20 using the film formation process described in the first embodiment (see FIG. 6A). In this film forming process, plasma containing excited species SiH 3 having a low adhesion probability is used. However, an overhang portion 22 a is still formed in the precursor film 22 near the entrance of the trench 20. In order to further improve the step coverage, it is preferable that the overhang portion 22a is small (thin film thickness is thin).
　そこで、本実施例においては、成膜工程の終了後にスパッタエッチ工程を実施することにより、希ガス、例えば、Ａｒガスのプラズマを用いてオーバーハング部分２２ａをスパッタエッチしており、これにより、オーバーハング部分２２ａを除去し、トレンチ２０の入口付近の閉塞を防止するようにしている（図６（ｂ）参照）。このスパッタエッチ工程は、スパッタエッチ量を大きくするために、上記実施例２とは異なり、ＬＦパワーも大きくしており、例えば、ＬＦ＝１５００Ｗとしている。このようなＬＦパワーを用いることにより、プラズマ中のイオンや電子を基板５へより多く照射し、スパッタエッチ量を大きくしている。但し、スパッタエッチにより削るオーバーハング部分２２ａは薄いため、そのスパッタエッチ時間は長くなくてよく、例えば、０．１秒程度でよい。 Therefore, in the present embodiment, the overhang portion 22a is sputter-etched using a rare gas, for example, Ar gas plasma, by performing a sputter etch process after the film formation process is completed. The hang portion 22a is removed to prevent the vicinity of the entrance of the trench 20 (see FIG. 6B). In this sputter etch process, in order to increase the sputter etch amount, unlike the second embodiment, the LF power is also increased, for example, LF = 1500 W. By using such LF power, more ions and electrons in the plasma are irradiated onto the substrate 5 to increase the amount of sputter etch. However, since the overhang portion 22a to be shaved by sputter etching is thin, the sputter etching time does not have to be long, for example, about 0.1 second.
　その後、実施例１で説明した窒化工程を用いて、トレンチ２０に成膜した前駆体膜２２の窒化を行い、ＳｉＮ膜２３としている（図６（ｃ）参照）。そして、成膜工程、スパッタエッチ工程及び窒化工程を、この順序で少なくとも１回以上実施して、トレンチ２０の側壁２１における膜厚が所望の膜厚となるＳｉＮ膜２３を形成する（図６（ｄ）参照）。 Thereafter, using the nitriding step described in Example 1, the precursor film 22 formed in the trench 20 is nitrided to form the SiN film 23 (see FIG. 6C). Then, the film forming process, the sputter etching process, and the nitriding process are performed at least once in this order to form the SiN film 23 having a desired film thickness on the side wall 21 of the trench 20 (FIG. 6 ( d)).
　上述した工程を経ることにより、トレンチ２０の側壁２１における膜厚が更に厚くなるため、段差被覆性が更によくなり、絶縁性も高い所望の膜厚のＳｉＮ膜２３を成膜することができる。特に、本実施例の場合、窒化工程の前にスパッタエッチ工程を実施するので、窒化工程で窒化する膜厚が薄くなるため、窒化工程における時間短縮が可能となる。 Through the above-described steps, the film thickness on the side wall 21 of the trench 20 is further increased, so that the step coverage is further improved and the SiN film 23 having a desired film thickness can be formed. In particular, in the case of the present embodiment, since the sputter etching process is performed before the nitriding process, the film thickness to be nitrided in the nitriding process is reduced, so that the time in the nitriding process can be shortened.
（実施例４）
　本実施例も、上記実施例１を前提とするものである。従って、実施例２と同様に、実施例１と重複する説明は省略して、本実施例の説明を行う。なお、本実施例も、実施例２を前提としてもよい。又、本実施例は、実施例３の変形例に該当する。 Example 4
This embodiment is also based on the first embodiment. Therefore, as in the second embodiment, the description overlapping with the first embodiment is omitted, and the present embodiment will be described. This embodiment may also be based on the second embodiment. Further, this embodiment corresponds to a modification of the third embodiment.
　本実施例では、図７のタイムチャートに示すように、実施例１で説明した窒化工程の終了後に、スパッタエッチ工程を実施している。つまり、実施例３とは、スパッタエッチ工程を追加する順序が異なっている。これは、成膜工程及び窒化工程を複数回繰り返す場合でも同様である。 In this embodiment, as shown in the time chart of FIG. 7, the sputter etch process is performed after the nitriding process described in the first embodiment. That is, the order of adding the sputter etch process is different from that of the third embodiment. This is the same even when the film forming process and the nitriding process are repeated a plurality of times.
　又、本実施例のスパッタエッチ工程でも、希ガス（例えば、Ａｒ等）を供給し、基板５にバイアスを印加し、希ガスのプラズマを生成しているが、実施例３とは異なり、当該プラズマを用いて窒化工程後に得られたＳｉＮ膜２３のスパッタエッチを行っている。 Also, in the sputter etch process of the present embodiment, a rare gas (for example, Ar) is supplied and a bias is applied to the substrate 5 to generate a rare gas plasma. Sputter etching of the SiN film 23 obtained after the nitriding process is performed using plasma.
　図７に示す各工程について、図８を参照して説明する。実施例１で説明した成膜工程を用いて、トレンチ２０に前駆体膜２２を成膜し（図８（ａ）参照）、その後、実施例１で説明した窒化工程を用いて、トレンチ２０に成膜した前駆体膜２２の窒化を行い、ＳｉＮ膜２３としている（図８（ｂ）参照）。 Each step shown in FIG. 7 will be described with reference to FIG. The precursor film 22 is formed in the trench 20 using the film forming process described in the first embodiment (see FIG. 8A), and then the trench 20 is formed using the nitriding process described in the first embodiment. The precursor film 22 thus formed is nitrided to form a SiN film 23 (see FIG. 8B).
　この成膜工程では、付着確率が低い励起種ＳｉＨ3を含むプラズマを用いているが、それでも、トレンチ２０の入口付近の前駆体膜２２にはオーバーハング部分２２ａが形成されてしまい、窒化工程では、その前駆体膜２２の窒化を行っているため、トレンチ２０の入口付近にはオーバーハング部分２３ａが形成されてしまう。更に段差被覆性を向上させるためには、このオーバーハング部分２３ａが小さい（膜厚が薄い）方がよい。 In this film forming process, plasma containing an excited species SiH 3 having a low adhesion probability is used. However, an overhang portion 22a is still formed in the precursor film 22 near the entrance of the trench 20, and in the nitriding process, Since the precursor film 22 is nitrided, an overhang portion 23 a is formed near the entrance of the trench 20. In order to further improve the step coverage, it is preferable that the overhang portion 23a is small (thin film thickness is thin).
　そこで、本実施例においては、窒化工程の終了後にスパッタエッチ工程を実施することにより、希ガス、例えば、Ａｒガスのプラズマを用いてオーバーハング部分２３ａをスパッタエッチしており、これにより、オーバーハング部分２３ａを除去し、トレンチ２０の入口付近の閉塞を防止するようにしている（図８（ｃ）参照）。ここでも、スパッタエッチにより削るオーバーハング部分２３ａは薄いため、そのスパッタエッチ時間は長くなくてよく、例えば、０．１秒程度でよい。 Therefore, in the present embodiment, the overhang portion 23a is sputter-etched by using a rare gas, for example, Ar gas plasma, by performing a sputter etch process after the nitridation process is completed. The portion 23a is removed to prevent the vicinity of the entrance of the trench 20 (see FIG. 8C). Again, since the overhang portion 23a to be shaved by sputter etching is thin, the sputter etching time does not have to be long, for example, about 0.1 seconds.
　そして、成膜工程、窒化工程及びスパッタエッチ工程を、この順序で少なくとも１回以上実施して、トレンチ２０の側壁２１における膜厚が所望の膜厚となるＳｉＮ膜２３を形成する（図８（ｄ）参照）。上述した工程を経ることにより、トレンチ２０の側壁２１における膜厚が更に厚くなるため、段差被覆性が更によくなり、絶縁性も高い所望の膜厚のＳｉＮ膜２３を成膜することができる。 Then, the film forming process, the nitriding process, and the sputter etching process are performed at least once in this order to form the SiN film 23 having a desired film thickness on the side wall 21 of the trench 20 (FIG. 8 ( d)). By passing through the process mentioned above, since the film thickness in the side wall 21 of the trench 20 becomes still thicker, the step coverage is further improved, and the SiN film 23 having a desired film thickness with high insulation can be formed.
　本発明は、半導体装置に適用するものであり、特に、アスペクト比が高い段差を被覆する絶縁膜として好適である。 The present invention is applied to a semiconductor device, and is particularly suitable as an insulating film covering a step having a high aspect ratio.
　５　　基板
　６　　高周波アンテナ
　７　　整合器
　８　　高周波電源
　９　　ガスノズル
　１１　電極部
　１２　整合器
　１３　低周波電源
　２０　トレンチ
　２１　側壁
　２２　前駆体膜
　２２ａ　オーバーハング部
　２３　ＳｉＮ膜
　２３ａ　オーバーハング部 DESCRIPTION OF SYMBOLS 5 Substrate 6 High frequency antenna 7 Matching device 8 High frequency power supply 9 Gas nozzle 11 Electrode part 12 Matching device 13 Low frequency power supply 20 Trench 21 Side wall 22 Precursor film 22a Overhang part 23 SiN film 23a Overhang part

Claims (12)

  1. 　基板に形成された段差を被覆する絶縁膜を形成する絶縁膜形成装置において、
    　Ｓｉを含有する主原料ガスとＳｉを含有しない副原料ガスとを含めて、複数のガスを供給するガス供給手段と、
    　前記ガスのプラズマを生成するプラズマ生成手段と、
    　前記ガス供給手段及び前記プラズマ生成手段を制御する制御手段とを有し、
    　前記制御手段は、
    　前記ガス供給手段により、少なくとも前記主原料ガスを供給し、前記プラズマ生成手段により、プラズマ生成時の主な励起種より前記基板に対する付着確率が低い励起種を含むプラズマを生成し、当該プラズマを用いて前記段差へ前駆体膜を成膜する成膜工程を実施し、
    　前記成膜工程の後、前記ガス供給手段により前記副原料ガスを供給し、前記プラズマ生成手段により前記副原料ガスのプラズマを生成し、当該プラズマを用いて前記前駆体膜中のＳｉの組成比を減少させて絶縁膜とする組成比減少工程を実施することを特徴とする絶縁膜形成装置。     In an insulating film forming apparatus for forming an insulating film covering a step formed on a substrate,
    A gas supply means for supplying a plurality of gases, including a main source gas containing Si and a sub-source gas not containing Si;
    Plasma generating means for generating plasma of the gas;
    Control means for controlling the gas supply means and the plasma generation means,
    The control means includes
    At least the main raw material gas is supplied by the gas supply means, and the plasma generation means generates plasma containing excited species having a lower probability of adhesion to the substrate than the main excited species at the time of plasma generation, and uses the plasma A film forming step for forming a precursor film on the step,
    After the film formation step, the auxiliary material gas is supplied by the gas supply unit, the plasma of the auxiliary material gas is generated by the plasma generation unit, and the composition ratio of Si in the precursor film is generated using the plasma. An insulating film forming apparatus is characterized in that a composition ratio reducing step is performed in which the composition ratio is reduced to form an insulating film.
  2. 　請求項１に記載の絶縁膜形成装置において、
    　前記制御手段は、前記成膜工程と前記組成比減少工程とを交互に複数回実施することを特徴とする絶縁膜形成装置。     In the insulating film forming apparatus according to claim 1,
    The said control means implements the said film-forming process and the said composition ratio reduction process alternately several times, The insulating film formation apparatus characterized by the above-mentioned.
  3. 　請求項１又は請求項２に記載の絶縁膜形成装置において、
    　更に、前記基板にバイアスを印加するバイアス印加手段を有し、
    　前記制御手段は、
    　前記組成比減少工程において、前記バイアス印加手段により前記基板へバイアスを印加することを特徴とする絶縁膜形成装置。     In the insulating film forming apparatus according to claim 1 or 2,
    Furthermore, bias application means for applying a bias to the substrate,
    The control means includes
    In the composition ratio decreasing step, a bias is applied to the substrate by the bias applying means.
  4. 　請求項３に記載の絶縁膜形成装置において、
    　前記制御手段は、
    　前記組成比減少工程の前に、
    　前記ガス供給手段により希ガスを供給し、前記バイアス印加手段により前記基板へバイアスを印加し、前記プラズマ生成手段により前記希ガスのプラズマを生成し、当該プラズマを用いて前記前駆体膜をスパッタエッチするスパッタエッチ工程を実施することを特徴とする絶縁膜形成装置。     In the insulating film forming apparatus according to claim 3,
    The control means includes
    Before the composition ratio reduction step,
    A rare gas is supplied by the gas supply means, a bias is applied to the substrate by the bias application means, a plasma of the rare gas is generated by the plasma generation means, and the precursor film is sputter etched using the plasma. An insulating film forming apparatus that performs a sputter etching process.
  5. 　請求項３に記載の絶縁膜形成装置において、
    　前記制御手段は、
    　前記組成比減少工程の後に、
    　前記ガス供給手段により希ガスを供給し、前記バイアス印加手段により前記基板へバイアスを印加し、前記プラズマ生成手段により前記希ガスのプラズマを生成し、当該プラズマを用いて前記絶縁膜をスパッタエッチするスパッタエッチ工程を実施することを特徴とする絶縁膜形成装置。     In the insulating film forming apparatus according to claim 3,
    The control means includes
    After the composition ratio reduction step,
    A rare gas is supplied by the gas supply means, a bias is applied to the substrate by the bias application means, a plasma of the rare gas is generated by the plasma generation means, and the insulating film is sputter etched using the plasma. An insulating film forming apparatus that performs a sputter etching process.
  6. 　請求項１から請求項５のいずれか１つに記載の絶縁膜形成装置において、
    　前記絶縁膜が窒化珪素膜である場合、
    　前記主原料ガスとしてＳｉＨ4を用い、
    　前記副原料ガスとしてＮＨ3又はＮ2の少なくとも一方を用い、
    　前記付着確率が低い励起種としてＳｉＨ3を生成することを特徴とする絶縁膜形成装置。     In the insulating film forming apparatus according to any one of claims 1 to 5,
    When the insulating film is a silicon nitride film,
    SiH 4 is used as the main source gas,
    Using at least one of NH 3 or N 2 as the auxiliary source gas,
    An insulating film forming apparatus, wherein SiH 3 is generated as an excited species having a low adhesion probability.
  7. 　基板に形成された段差を被覆する絶縁膜を形成する絶縁膜形成方法において、
    　Ｓｉを含有する主原料ガスとＳｉを含有しない副原料ガスのうち、少なくとも前記主原料ガスを供給し、プラズマ生成時の主な励起種より前記基板に対する付着確率が低い励起種を含むプラズマを生成し、当該プラズマを用いて前記段差へ前駆体膜を成膜する成膜工程と、
    　前記成膜工程の後、前記副原料ガスを供給し、前記副原料ガスのプラズマを生成し、当該プラズマを用いて前記前駆体膜中のＳｉの組成比を減少させて絶縁膜とする組成比減少工程とを有することを特徴とする絶縁膜形成方法。     In an insulating film forming method for forming an insulating film covering a step formed on a substrate,
    Supplying at least the main source gas out of the main source gas containing Si and the auxiliary source gas not containing Si, and generating plasma containing excited species having a lower adhesion probability to the substrate than the main excited species at the time of plasma generation And a film forming step of forming a precursor film on the step using the plasma,
    After the film forming step, the auxiliary material gas is supplied, plasma of the auxiliary material gas is generated, and the composition ratio of Si in the precursor film is reduced by using the plasma to form an insulating film. An insulating film forming method comprising: a reducing step.
  8. 　請求項７に記載の絶縁膜形成方法において、
    　前記成膜工程と前記組成比減少工程とを交互に複数回実施することを特徴とする絶縁膜形成方法。     The insulating film forming method according to claim 7,
    The method for forming an insulating film, wherein the film forming step and the composition ratio decreasing step are alternately performed a plurality of times.
  9. 　請求項７又は請求項８に記載の絶縁膜形成方法において、
    　前記組成比減少工程において、前記基板へバイアスを印加することを特徴とする絶縁膜形成方法。     In the insulating film formation method according to claim 7 or 8,
    In the composition ratio reduction step, a bias is applied to the substrate.
  10. 　請求項９に記載の絶縁膜形成方法において、
    　希ガスを供給し、前記基板へバイアスを印加し、前記希ガスのプラズマを生成し、当該プラズマを用いて前記前駆体膜をスパッタエッチするスパッタエッチ工程を更に有し、
    　前記組成比減少工程の前に前記スパッタエッチ工程を実施することを特徴とする絶縁膜形成方法。     In the insulating film formation method according to claim 9,
    A sputter etch step of supplying a rare gas, applying a bias to the substrate, generating a plasma of the rare gas, and sputter-etching the precursor film using the plasma;
    An insulating film forming method, wherein the sputter etching step is performed before the composition ratio reducing step.
  11. 　請求項９に記載の絶縁膜形成方法において、
    　希ガスを供給し、前記基板へバイアスを印加し、前記希ガスのプラズマを生成し、当該プラズマを用いて前記絶縁膜をスパッタエッチするスパッタエッチ工程を更に有し、
    　前記組成比減少工程の後に前記スパッタエッチ工程を実施することを特徴とする絶縁膜形成方法。     In the insulating film formation method according to claim 9,
    A sputter etch step of supplying a rare gas, applying a bias to the substrate, generating a plasma of the rare gas, and sputter-etching the insulating film using the plasma;
    An insulating film forming method, wherein the sputter etching process is performed after the composition ratio decreasing process.
  12. 　請求項７から請求項１１のいずれか１つに記載の絶縁膜形成方法において、
    　前記絶縁膜が窒化珪素膜である場合、
    　前記主原料ガスとしてＳｉＨ4を用い、
    　前記副原料ガスとしてＮＨ3又はＮ2の少なくとも一方を用い、
    　前記付着確率が低い励起種としてＳｉＨ3を生成することを特徴とする絶縁膜形成方法。     In the insulating film formation method according to any one of claims 7 to 11,
    When the insulating film is a silicon nitride film,
    SiH 4 is used as the main source gas,
    Using at least one of NH 3 or N 2 as the auxiliary source gas,
    A method of forming an insulating film, wherein SiH 3 is generated as an excited species having a low adhesion probability.
PCT/JP2011/071080 2010-09-30 2011-09-15 Method and device for forming insulation film WO2012043250A1 (en)

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