JP2004200713A - Semiconductor device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device for forming an insulating film having a low dielectric constant and good adhesion characteristic with a copper wiring. <P>SOLUTION: A method of manufacturing a semiconductor device is provided, in which film-forming gas is made into plasma, making its containing gas react with each other, and forming an insulating film 39b having a low dielectric constant on a substrate. A film forming gas contains an alkyl compound, having a siloxane bond, Hydrocarbon (CxHy), and oxygen-containing gas. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly, to a semiconductor device for forming an interlayer insulating film having a low dielectric constant by covering a wiring mainly composed of a copper film and a method for manufacturing the same.

  In recent years, as the degree of integration and the density of semiconductor integrated circuit devices have been increased, higher data transfer speeds have been demanded. Therefore, an insulating film having a small RC delay and a low dielectric constant (hereinafter, referred to as a low dielectric constant insulating film) is used.

In order to form such a low dielectric constant insulating film, one known method is a plasma CVD method using trimethylsilane (SiH (CH ₃ ) ₃ ) and N ₂ O. For example, it is described in Non-Patent Document 1 and the like. A plasma CVD method using tetramethylsilane (Si (CH ₃ ) ₄ ) and N ₂ O is described in, for example, Non-Patent Document 2.

In addition, a plasma CVD method using phenylsilane or the like is also known. For example, it is described in Non-Patent Document 3, Non-Patent Document 4, and the like.
MJLoboda, JASeifferly, RFSchneider, and CMGrove, Electrochem.Soc.Fall Meeting Abstracts, p.344 (1998) J. Shi, MA-Plano, T. Mountsier, and S. Nag, SEMICON Korea Technical Symposium 2000, p.279 (2000) Kazuhiko Endo, Keisuke Shinoda, Toru Tatsumi, The 46th Spring Meeting of the Japan Society of Applied Physics (1999), p.897, Nobuo Matsushita, Yoshinori Mori, Yuichi Naito, Aya Matsuno, The 60th Autumn Meeting of the Japan Society of Applied Physics (1999) 1p-ZN-9 (1999), Yasutaka Uchida, Takeo Matsuzawa, Satoshi Sugano, Masakiyo Matsumura, 4th Spring Society of Applied Physics, p.897 (1999)

  However, these low dielectric constant insulating films have relatively low adhesion strength to wiring mainly composed of a copper film, and have low film hardness, so that improvement is desired.

  The present invention has been made in view of the problems of the conventional example described above, and has good adhesion to wiring mainly composed of a copper film, and has an appropriate film hardness, and has an insulating film having a low dielectric constant. An object of the present invention is to provide a method for manufacturing a semiconductor device which can be formed and a semiconductor device manufactured by the method.

In order to solve the above-mentioned problems, the invention according to claim 1 relates to a method of manufacturing a semiconductor device, and relates to a method of manufacturing a semiconductor device in which a film forming gas is turned into plasma and reacted to form an insulating film having a low dielectric constant on a substrate. In the method, the film forming gas includes an alkyl compound having a siloxane bond, a hydrocarbon (C _x H _y ), and an oxygen-containing gas,
The invention according to claim 2 relates to the method for manufacturing a semiconductor device according to claim 1, wherein the alkyl compound having a siloxane bond is hexamethyldisiloxane (HMDSO: (CH ₃ ) ₃ Si—O—Si (CH ₃ ) ₃ ), octamethylcyclotetrasiloxane (OMCTS: ((CH ₃ ) ₂ ) ₄ Si ₄ O ₄ ),

Or tetramethylcyclotetrasiloxane (TMCTS: (CH ₃ H) ₄ Si ₄ O ₄ )

Characterized by any one of the following,
The invention according to claim 3 relates to the method for manufacturing a semiconductor device according to claim 1 or 2, wherein the hydrocarbon (C _x H _y ) is acetylene (C ₂ H ₂ ), methylcyclohexane (CH ₃ C ₆ H). ₁₁ ), characterized in that it is any one of cyclohexane (C ₆ H ₁₂ ) or benzene (C ₆ H ₆ ),
According to a fourth aspect of the present invention, there is provided the method of manufacturing a semiconductor device according to any one of the first to third aspects, wherein the film-forming gas is methylsilane (SiH _n ( CH ₃ ) _4-n : n = 0, 1, 2, 3),
Invention of claim 5 relates to a method of manufacturing a semiconductor device according to claim 4, wherein said methylsilane _{(SiH n (CH 3) 4} -n: n = 0,1,2,3) is monomethyl silane (SiH ₃ (CH ₃ )), dimethylsilane (SiH ₂ (CH ₃ ) ₂ ), trimethylsilane (SiH (CH ₃ ) ₃ ), or tetramethylsilane (Si (CH ₃ ) ₄ ) Characterized by
The invention according to claim 6 relates to the method of manufacturing a semiconductor device according to any one of claims 1 to 5, wherein the film forming gas is helium (He), argon (Ar), or nitrogen (N ₂ ). Characterized by including any one of the following,
The invention according to claim 7 relates to a semiconductor device, wherein an insulation film is formed on a wiring mainly including a copper film, wherein the insulation film is according to any one of claims 1 to 6. Characterized by an insulating film having a low dielectric constant formed by a method of manufacturing a semiconductor device,
The invention according to claim 8 relates to the semiconductor device according to claim 7, wherein the insulating film formed on the wiring mainly composed of the copper film constitutes an interlayer insulating film sandwiched by the wiring mainly composed of the copper film. Characterized in that
The invention according to claim 9 relates to a semiconductor device, wherein at least a barrier insulating film in contact with a wiring mainly including a copper film and an insulating film over the barrier insulating film are formed on a wiring mainly including a copper film. Wherein the insulating film is an insulating film having a low dielectric constant formed by the method of manufacturing a semiconductor device according to any one of claims 1 to 6,
According to a tenth aspect of the present invention, there is provided the semiconductor device according to the ninth aspect, wherein a barrier insulating film formed on the wiring mainly including the copper film and in contact with the wiring mainly including the copper film, and on the barrier insulating film. This insulating film is characterized in that it constitutes an interlayer insulating film sandwiched by wiring mainly composed of a copper film.

  Hereinafter, the function achieved by the configuration of the present invention will be described.

  According to the experiment conducted by the inventor of the present invention, as shown in FIG. 2, the peel strength between the substrate and the insulating film is inversely proportional to the gas pressure of the film forming gas, and particularly, becomes extremely high when the gas pressure becomes lower than 1 Torr. Become. On the other hand, as shown in FIG. 6, the dielectric constant of the film formation is high in the film formation at a low gas pressure and is low in the film formation at a high gas pressure.

  Therefore, in the initial stage of film formation, a film is formed by converting a film forming gas having a low gas pressure into a plasma and reacting the film, and thereafter, a film forming gas having a high gas pressure is formed into a plasma and reacting the film to form a film. In addition, an insulating film having a low dielectric constant as a whole can be formed. In the experiment, the film was formed on the Si substrate, but the result is the same when the film was formed on the copper substrate.

  In particular, when an insulating film including a barrier insulating film is formed over a wiring mainly including a copper film, the barrier insulating film is formed by the method for manufacturing a semiconductor device of the present invention. That is, the initial film is formed as a low-voltage insulating film, and the rest is formed as a high-voltage insulating film. The frequency of the power for plasma conversion is set to a low frequency for both the low-voltage insulating film and the high-voltage insulating film.

  Although the adhesion is originally large when the film is formed by low-frequency power, the adhesion is increased by forming the film using a low-pressure gas at the beginning of the film formation.

Further, by using a nitrogen-containing gas such as ammonia (NH ₃ ) or nitrogen (N ₂ ) as a film forming gas for the barrier insulating film, the barrier properties can be improved. Alternatively, by using an inert gas such as helium (He), argon (Ar), or nitrogen (N ₂ ), the deposition gas can be diluted without lowering the adhesion of the deposition.

In the above, in addition to the main insulating film having a low dielectric constant, there is an application to a method of forming a barrier insulating film underlying the main insulating film, but for the purpose of simply forming a main insulating film having a low dielectric constant, As in the present invention, the gas pressure does not need to be changed during film formation. For example, an alkyl compound having a siloxane bond and acetylene (C ₂ H ₂ ), methylcyclohexane (CH ₃ C ₆ H ₁₁ ) or cyclohexane ( C ₆ H ₁₂ ), a film forming gas containing an oxygen-containing gas, or an alkyl compound having a siloxane bond, benzene (C ₆ H ₆ ), an oxygen-containing gas, and an inert gas. A desired main insulating film can be formed with the use of the film formation gas containing the same gas pressure while maintaining the same gas pressure.

Instead of the alkyl compound having a siloxane bond as the film forming gas, methylsilane _{(SiH n (CH 3) 4} -n: n = 0,1,2,3) may be used those containing.

As described above, the alkyl compound having a siloxane bond or methylsilane _{(SiH n (CH 3) 4} -n: n = 0,1,2,3) and, N ₂ O, one of H ₂ O or CO ₂ By a plasma CVD method using at least one oxygen-containing gas, the gas pressure is lowered (to less than 1 Torr) at the beginning of film formation, and the gas pressure is increased (to 1 Torr or more) when performing the remaining film formation. Then, an interlayer insulating film sandwiched between wirings mainly including a copper film or a barrier insulating film in contact with the wiring mainly including a copper film is formed.

  By lowering the gas pressure, it is possible to form an insulating film having good adhesion to wiring mainly composed of a copper film. By increasing the gas pressure, an insulating film having a low dielectric constant can be formed.

  Therefore, it is possible to form an interlayer insulating film having good adhesion to wiring mainly composed of a copper film and having a low dielectric constant.

  In addition, by applying a low-frequency power and adjusting and forming the barrier insulating film in the above two steps, it is possible to form a barrier insulating film having better adhesion with a wiring mainly composed of a copper film. Become.

Further, for the purpose of only forming a main insulating film having a low dielectric constant, the gas pressure does not need to be changed during the film formation as in the present invention, and an alkyl compound having a siloxane bond and an acetylene (C ₂ H ₂ ), a film forming gas containing any one of methylcyclohexane (CH ₃ C ₆ H ₁₁ ) or cyclohexane (C ₆ H ₁₂ ) and an oxygen-containing gas, or an alkyl compound having a siloxane bond, and benzene (C Using a deposition gas containing ₆ H ₆ ), an oxygen-containing gas, and an inert gas, a desired main insulating film can be formed while maintaining the same gas pressure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment)
FIG. 1 is a side view showing a configuration of a parallel plate type plasma film forming apparatus 101 used in a method of manufacturing a semiconductor device according to an embodiment of the present invention.

  The plasma film forming apparatus 101 includes a film forming section 101A that is a place where an insulating film is formed on a film formation target substrate 21 by a plasma gas, and a film forming gas supply having a plurality of gas sources constituting the film forming gas. And a unit 101B.

  As shown in FIG. 1, the film forming unit 101 </ b> A includes a chamber 1 that can be depressurized, and the chamber 1 is connected to an exhaust device 6 through an exhaust pipe 4. An opening / closing valve 5 for controlling conduction / non-conduction between the chamber 1 and the exhaust device 6 is provided in the exhaust pipe 4. The chamber 1 is provided with pressure measuring means such as a vacuum gauge (not shown) for monitoring the pressure in the chamber 1.

  The chamber 1 is provided with a pair of upper electrode (second electrode) 2 and lower electrode (first electrode) 3 facing each other, and supplies high frequency power of 13.56 MHz to the upper electrode 2. A power supply (RF power supply) 7 is connected, and a low-frequency power supply power supply 8 for supplying low-frequency power of a frequency of 380 kHz to the lower electrode 3 is connected. Electric power is supplied from the power sources 7 and 8 to the upper electrode 2 and the lower electrode 3 to turn the film forming gas into plasma. The upper electrode 2, the lower electrode 3, and the power supplies 7 and 8 constitute a plasma generating means for converting the film forming gas into plasma.

  The upper electrode 2 also serves as a dispersing device for the deposition gas. A plurality of through-holes are formed in the upper electrode 2, and the opening of the through-hole on the surface facing the lower electrode 3 serves as an outlet (inlet) for the film-forming gas. The discharge port for the film forming gas or the like is connected to the film forming gas supply unit 101B via a pipe 9a. In some cases, the upper electrode 2 may be provided with a heater (not shown). By heating the upper electrode 2 to a temperature of about 100 to 200 ° C. during film formation, it is possible to prevent particles made of a reaction product such as a film forming gas from adhering to the upper electrode 2.

  The lower electrode 3 also serves as a holder for the substrate 21 on which the film is to be formed, and includes a heater 12 for heating the substrate 21 on the holder.

The film forming gas supplying portion 101B includes a source of alkyl compound having the siloxane bond, methylsilane _{(SiH n (CH 3) 4} -n: n = 0,1,2,3) and a source of acetylene (C ₂ H ₂ ), cyclohexane (C ₆ H ₁₂ ), methylcyclohexane (CH ₃ C ₆ H ₁₁ ), benzene (C ₆ H ₆ ), methyl alcohol (CH ₃ OH) or ethyl alcohol (C ₂ H ₅ OH), a source of oxygen-containing gas, a source of ammonia (NH ₃ ), a source of diluent gas, and a source of nitrogen (N ₂ ) Supply source is provided.

  These gases are appropriately supplied into the chamber 1 of the film forming unit 101A through branch pipes 9b to 9j and a pipe 9a to which all of these branch pipes 9b to 9j are connected. Flow control means 11a to 11i and opening / closing means 10b to 10n and 10p to t for controlling conduction / non-conduction of the branch pipes 9b to 9j are provided in the middle of the branch pipes 9b to 9j. An opening / closing means 10a for closing / conducting is provided.

Further, in order to circulate the N ₂ gas and purge the residual gas in the branch pipes 9b to 9e, 9g and 9h, the branch pipe 9j connected to the N ₂ gas supply source and the other branch pipes 9b to 9e and 9g , 9h are provided with opening / closing means 10u to 10z for controlling conduction / non-conduction between them. The N ₂ gas purges residual gases in the pipe 9a and the chamber 1 in addition to the branch pipes 9b to 9e, 9g, and 9h. Alternatively, it may be used as a diluent gas.

  According to the film forming apparatus 101 as described above, the plasma generating means 2 includes a siloxane supply source, an oxygen-containing gas supply source, and an inert gas supply source, and further converts the film formation gas into plasma. , 7, 8 are provided.

  Accordingly, as described in the following embodiment, an insulating film having a low dielectric constant and high adhesion strength to a wiring mainly including a copper film can be formed by a plasma CVD method.

As plasma generation means, there is a means for generating plasma using, for example, a parallel plate type upper electrode 2 and lower electrode 3, and power supplies 7 and 8 for supplying electric power of two high and low frequencies to the upper electrode 2 and the lower electrode 3, respectively. Is connected. Therefore, it is possible to generate plasma by applying the power of these two frequencies to the electrodes 2 and 3 respectively. In particular, the insulating film formed in this manner is dense, and to include the CH _3, having a low dielectric constant.

  Preferred combinations of applying power to the upper electrode 2 and the lower electrode 3 are as follows.

  First, in the step of forming the low-voltage insulating film, low-frequency power having a frequency of 100 kHz or more and less than 1 MHz is applied to the lower electrode 3 or low-frequency power is applied to the lower electrode 3 and 1 MHz is applied to the upper electrode 2. In the step of applying the high-frequency power and forming the high-voltage insulating film, the high-frequency power is applied to the upper electrode 2.

  Second, in the step of forming the first high-voltage insulating film, low-frequency power is applied to the lower electrode 3 in addition to applying high-frequency power to the upper electrode 2.

  Third, in particular, in the step of forming the low-voltage insulating film by using the manufacturing method of the present invention for forming the barrier insulating film in the insulating film including the barrier insulating film, the frequency of the lower electrode 3 is not less than 100 kHz and less than 1 MHz. Is applied to the lower electrode 3 in the step of forming the high-voltage insulating film. At this time, high frequency power may be applied to the upper electrode 2.

  Next, as a film forming gas to which the present invention is applied, the following compounds can be used as representative examples of the alkyl compound having a siloxane bond, methylsilane, hydrocarbon, oxygen-containing gas, and diluent gas.

(I) alkyl compound hexamethyldisiloxane having a siloxane bond _{(HMDSO: (CH 3) 3} Si-O-Si (CH 3) 3)
Octamethylcyclotetrasiloxane _{(OMCTS: ((CH 3)} 2) 4 Si 4 O 4),

Tetramethylcyclotetrasiloxane (TMCTS: (CH ₃ H) ₄ Si ₄ O ₄ )

(Ii) Methylsilane (SiH _n (CH ₃ ) _4-n : n = 0, 1, 2, 3)
Monomethylsilane (SiH ₃ (CH ₃ ))
Dimethylsilane (SiH ₂ (CH ₃ ) ₂ )
Trimethylsilane (SiH (CH _{3) 3)}
Tetramethylsilane (Si (CH _{3) 4)}
(Iii) hydrocarbon (C _x H _y)
Acetylene (C ₂ H ₂ )
Methylcyclohexane (CH ₃ C ₆ H ₁₁₎
Cyclohexane (C ₆ H ₁₂ )
Benzene (C ₆ H ₆ )
(Iv) Oxygen-containing gas Nitric oxide (N ₂ O)
Water (H ₂ O)
Carbon dioxide (CO ₂ )
(V) Diluent gas helium (He)
Argon (Ar)
Nitrogen (N ₂₎
Next, an experiment performed by the present inventors will be described.

Under the following film forming conditions, a silicon oxide film was formed on a Si substrate by a plasma excitation CVD method (PECVD method) according to the film forming procedure of FIG. HMDSO was used as an alkyl compound having a siloxane bond, N ₂ O was used as an oxygen-containing gas, and He was used as a diluent gas. In the film formation, as shown in FIG. 7, the time required for replacing the gas in the chamber from the gas introduction to the start of film formation (plasma excitation) (stabilization period) is 1 minute 30 seconds, and the upper electrode The upper electrode 2 is heated at 100 ° C. in order to prevent reaction products from adhering to the upper electrode 2.

Deposition conditions Deposition gas HMDSO flow rate: 50 SCCM
N2O flow rate: 200 SCCM
He flow rate: 400 SCCM
Gas pressure (parameter): 0.75 to 1.75 Torr
Plasma excitation condition Lower electrode (first electrode)
Low frequency power (frequency 380 kHz) (parameter): 0 to 100 W
Upper electrode (second electrode)
High frequency power (frequency 13.56 MHz): 250 W
Substrate heating condition: 375 ° C
(A) Relationship Between Gas Pressure of Film-Forming Gas and Peeling Strength FIG. 2 is a diagram showing a relationship between gas pressure of the film-forming gas and peeling strength of a film formed on a Si substrate. The vertical axis indicates the peel strength (g weight) of the film formed on a linear scale, and the horizontal axis indicates the gas pressure (Torr) of the film forming gas on a linear scale.

  The insulating film for investigation is formed on the Si substrate under the two conditions of the gas pressure of the film forming gas of 0.9 and 1.5 Torr without applying the low frequency power to the lower electrode 3 among the parameters of the above film forming conditions. A film was formed. The peel strength was measured using a measuring device (Shimadzu scanning scratch tester SST101) manufactured by Shimadzu Corporation.

  According to FIG. 2, when the gas pressure was 1.5 Torr, the peel strength was about 5 to 6, and when the gas pressure was 0.9 Torr, the peel strength was greatly improved to about 15 to 16, which is about three times.

  Note that, in the above investigation, the peel strength with respect to the Si substrate is examined using the Si substrate as the substrate on which the film is to be formed, but the peel strength with respect to the copper substrate is considered to have the same tendency.

(B) Relationship between Low-Frequency Power of Film Deposition Substrate Bias and Peeling Strength FIG. 3 shows the relationship between low-frequency power applied to the lower electrode 3 under plasma excitation conditions and peeling strength of a film formed on a Si substrate. FIG. The vertical axis shows the peel strength (g weight) of the film formed on a linear scale, and the horizontal axis shows the low frequency power (W) on a linear scale.

  The inspection insulating film was formed under the following conditions: the gas pressure of the film forming gas was 1.5 Torr, and the low frequency power was 0, 10, 30, 50, 75, and 100 W. The same measuring device as in (a) was used.

  According to FIG. 3, when the low-frequency power is 30 W or less, the peel strength decreases as the power increases, from about 6 at 0 W to about 3.3 at 30 W. When the low-frequency power was larger than 30 W, the peel strength did not decrease so much and settled to around 3.

(C) Relationship Between Gas Pressure of Film Forming Gas and Film Hardness FIG. 4 is a diagram showing a relationship between the gas pressure of the film forming gas and the film hardness and Young's Modulus of the film formed on the Si substrate. . The left side of the vertical axis shows the film hardness of the film formed on a linear scale, the right side shows the Young's modulus (GP) of the film formed on a linear scale, and the horizontal axis shows the gas of the film forming gas expressed on a linear scale. Indicates pressure (Torr).

  In the inspection insulating film, of the parameters of the film forming conditions, the low-frequency power is not applied to the lower electrode 3 and the gas pressures of the film forming gas are 0.7, 0.9, 1.1, and 1.3. , 1.5, 1.7 Torr. The film hardness and Young's Modulus were measured using a measuring instrument (Shimazu Dynamic Ultra-Micro Hardness Tester DUH-W201S) manufactured by Shimadzu Corporation.

  According to FIG. 4, the film hardness decreases from 0.7 Torr to 1.3 Torr as the gas pressure increases. The gas pressure was about 230 when the gas pressure was 0.7 Torr, and was about 70 to 80 when the gas pressure was 1.3 Torr. When the gas pressure was higher than this, the film hardness settled to around 50 and did not change much.

  Young's Modulus showed almost the same tendency as the film hardness. The gas pressure was about 40 GP when the gas pressure was 0.7 Torr, and about 10 when the gas pressure was 1.3 Torr. When the gas pressure became higher than this, the Young's modulus settled around 10 GP.

(D) Relationship between Low-Frequency Power of Film Deposition Substrate Bias and Film Hardness FIG. 5 shows the low frequency power applied to the lower electrode 3 for forming a DC bias voltage for the film deposition substrate and the film formed on the Si substrate. FIG. 3 is a diagram illustrating a relationship between a film hardness and a Young's modulus of the film. The left side of the vertical axis shows the film hardness expressed on a linear scale, the right side shows the Young's modulus (GP) of the film formation expressed on a linear scale, and the horizontal axis shows the low frequency power (W) expressed on a linear scale. .

  The inspection insulating film was formed under the following conditions: the gas pressure of the film forming gas was 1.5 Torr, and the low frequency power was 0, 10, 30, 50, 75, and 100 W. The same measuring device as in (c) was used.

  According to FIG. 5, from 0 to 75 W of low frequency power, the film hardness increases as the low frequency power increases. As the low frequency power further increases, the film hardness gradually increases. The film hardness was about 50, 75 W when no low-frequency power was applied, about 290 at 100 W, and about 300 at 100 W.

  The Young's modulus also showed a tendency similar to the film hardness, and was about 8, 75 W when no low-frequency power was applied, and about 50 when 100 W was applied.

(E) Relationship between low-frequency power of substrate bias for film formation and relative dielectric constant of film formation FIG. 6 shows the relationship between low-frequency power applied to lower electrode 3 for forming a DC bias voltage for film formation substrate and Si substrate. FIG. 4 is a diagram showing a relationship between relative dielectric constants of a film formed in FIG. The vertical axis shows the relative dielectric constant of the film formed on a linear scale, and the horizontal axis shows the low frequency power (W) on a linear scale.

  The insulating film for inspection is formed under the three conditions of the gas pressure of the film forming gas of 0.9, 1.2, and 1.5 Torr and the low frequency power of 0, 10, 20, 50, 75 among the parameters of the above film forming conditions. , 100W. The relative permittivity was measured by a CV measurement method in which a signal having a frequency of 1 MHz was superimposed on a DC bias.

  In the figure, when the gas pressure is 1.5 Torr, the numbers near the inspection points indicate the film hardness.

  According to FIG. 6, when the gas pressure is 0.9 Torr, the relative dielectric constant sharply increases from 2.9 to 4.3 at a low frequency power of 0 to 20 W, and gradually decreases at a low frequency power of more than 2.9. I have. In the case of a gas pressure of 1.2 Torr, the relative dielectric constant sharply increases from 2.7 to about 3.9 from 0 to 20 W of low frequency power, and gradually increases from that point to about 4.8 at 100 W. . In the case of a gas pressure of 1.5 Torr, the relative dielectric constant sharply increases from 2.7 to 3.6 from 0 to 20 W of low-frequency power, as in the case of a gas pressure of 1.2 Torr. It gradually increases at low frequency power and reaches about 4.1 at 100 W.

  As described above, according to the first embodiment, it was found that the lower the deposition gas pressure, the higher the peel strength but the higher the relative dielectric constant. In particular, the peel strength is large at 1 Torr or less, and the relative dielectric constant is small at 1 Torr or more. Further, it was found that the smaller the low frequency power, the larger the peel strength and the lower the relative dielectric constant.

  Therefore, when an insulating film having a low dielectric constant is formed as an interlayer insulating film between wirings mainly composed of a copper film, the gas pressure is reduced to, for example, less than 1 Torr at the initial stage of film formation while sacrificing the relative dielectric constant somewhat. It is desirable that the peeling strength be increased by lowering the low-frequency power and the low frequency power be increased, and the remaining film be formed by increasing the gas pressure to, for example, 1 Torr or more, thereby lowering the relative dielectric constant of the entire film.

  In the case of forming a barrier insulating film in contact with a wiring mainly composed of a copper film, the gas pressure is adjusted in the same manner as the interlayer insulating film in the low-voltage insulating film and the high-pressure insulating film, but the power for plasma excitation is reduced. The frequency is not adjusted, and both the low-voltage insulating film and the high-voltage insulating film have a low frequency. That is, in the initial stage of film formation, the gas pressure is reduced to, for example, less than 1 Torr, the peel strength is increased by reducing the low-frequency power, and the gas pressure is reduced for the remaining film formation, at the expense of the relative dielectric constant to some extent. For example, it is desirable to increase the relative dielectric constant of the entire film to 1 Torr or more to lower the relative dielectric constant.

  Although the gas pressure is preferably less than 1 Torr at the beginning of film formation, if the gas pressure is less than 0.1 Torr, the film formation rate is too slow to be practical. In the remaining film formation, the gas pressure is preferably 1 Torr or more, but it is practical to set the gas pressure to 10 Torr at the maximum in terms of discharge.

(Second embodiment)
Next, a semiconductor device and a method of manufacturing the same according to a second embodiment of the present invention will be described with reference to FIGS.

FIG. 8A is a cross-sectional view showing a semiconductor device manufactured by the method for manufacturing a semiconductor device according to the second embodiment of the present invention. FIG. 2B is a cross-sectional view taken along the line II of FIG. HMDSO + N ₂ O + He is used as a film forming gas for the wiring interlayer insulating film 34 sandwiched between the lower wiring buried insulating film 32 in which the lower wiring 33 is buried and the upper wiring buried insulating film 35 in which the upper wiring 37 is buried. Used.

First, as shown in FIG. 8A, a wiring buried insulating film 32 made of a SiO ₂ film or a SiOCH film having a thickness of about 1 μm is formed on a substrate (substrate on which film is to be formed) 31. The SiOCH film is an insulating film containing Si, O, C, and H in the film.

  Subsequently, after the wiring buried insulating film 32 is etched to form a wiring groove, a TaN film 33a is formed on the inner surface of the wiring groove as a copper diffusion preventing film. Next, after a copper seed layer (not shown) is formed on the surface of the TaN film 33a by a sputtering method, the copper film is embedded by a plating method. The copper film and the TaN film 33a protruding from the wiring groove are polished by CMP (Chemical Mechanical Polishing) to planarize the surface. As a result, a lower wiring composed of the wiring 33b mainly composed of the copper film and the TaN film 33a is formed.

Next, a wiring interlayer insulating film 34 made of a PE-CVD SiOCH film having a thickness of several nm is formed by a plasma CVD method using HMDSO + N ₂ O + He. The details will be described below.

That is, in order to form the wiring interlayer insulating film 34, first, the substrate 21 to be formed is introduced into the chamber 1 of the film forming apparatus 101 and held by the substrate holder 3. Subsequently, the deposition target substrate 21 is heated to a temperature of 375 ° C. HMDSO is introduced at a flow rate of 50 sccm, N ₂ O gas at a flow rate of 200 sccm, and He gas at a flow rate of 400 sccm into the chamber 1 of the plasma film forming apparatus 101 shown in FIG. 1, and the pressure is maintained at 0.7 Torr. Next, a low-frequency power of 100 to 150 W with a frequency of 380 kHz is applied to the lower electrode 3, and a high-frequency power of 250 W (corresponding to 0.3 W / cm ² ) with a frequency of 13.56 MHz is applied to the upper electrode 2.

Thereby, HMDSO, N ₂ O, and He are turned into plasma. While maintaining this state for 40 seconds, a low-voltage insulating film 34a made of a PE-CVD SiOC film having a thickness of about 100 nm is formed. The SiOC film is an insulating film containing Si, O, and C in the film.

  Subsequently, using the same combination of reaction gases, maintaining the same flow rate, adjusting the gas pressure to 1.5 Torr, and forming a film under the same plasma excitation conditions. A high-voltage insulating film 34b made of a PE-CVD SiOCH film having a thickness of about 500 nm is formed.

  As described above, the wiring interlayer insulating film 34 including the low-voltage insulating film 34a and the high-voltage insulating film 34b is formed.

Next, a wiring buried insulating film 35 made of a SiO ₂ film or SiOCH film having a thickness of about 1 μm is formed by the same method as when the SiO ₂ film or SiOCH film 32 is formed on the wiring interlayer insulating film 34.

  Next, a connection conductor 36 mainly composed of a copper film and an upper wiring 37 are formed by a well-known dual damascene method. In the drawings, reference numerals 36a and 37a are TaN films, and reference numerals 36b and 37b are copper films.

  Next, a barrier insulating film 38 is formed on the entire surface. Thus, the semiconductor device is completed.

  As described above, according to the second embodiment, the wiring interlayer is formed between the lower wiring buried insulating film 32 in which the lower wiring 33 is buried and the upper wiring buried insulating film 35 in which the upper wiring 37 is buried. In the method of manufacturing a semiconductor device having the insulating film 34 interposed therebetween, an initial film is formed at a gas pressure of a film forming gas of less than 1 Torr, and the remaining film is formed at a pressure of 1 Torr or more by a plasma excitation CVD method. .

  Thereby, the interlayer insulating film 34 having high adhesion to the copper film 33b and having a low relative dielectric constant of 3 or less as a whole can be formed.

  As described above, the present invention has been described in detail with reference to the second embodiment. However, the scope of the present invention is not limited to the example specifically shown in the above embodiment, and the scope of the present invention does not depart from the gist of the present invention. Modifications of the above embodiment are included in the scope of the present invention.

Instead of the HMDSO used in the second embodiment, the other alkyl compound having a siloxane bond described in the first embodiment is replaced with methylsilane (SiH _n (CH ₃ ) _4-n : n = 0). , 1, 2, 3) can be used. The type of methylsilane has been described in the first embodiment, and will not be described here.

Further, the deposition gas may contain any one of acetylene (C ₂ H ₂ ), methylcyclohexane (CH ₃ C ₆ H ₁₁ ), and cyclohexane (C ₆ H ₁₂ ). The porosity of the membrane increases and the dielectric constant can be further reduced.

Further, the deposition gas may contain benzene (C ₆ H ₆ ).

Further, the deposition gas may contain methyl alcohol (CH ₃ OH) or ethyl alcohol (C ₂ H ₅ OH).

As the deposition gas, an inert gas containing any one of argon (Ar) and nitrogen (N ₂ ) may be added instead of helium (He).

  Further, the barrier insulating film 38 may be formed by the same film forming method as the barrier insulating film 39a according to the third embodiment described below.

(Third embodiment)
FIG. 9A is a cross-sectional view illustrating a method for manufacturing the semiconductor device according to the third embodiment. FIG. 9B is a cross-sectional view taken along the line II-II of FIG.

  8A and 8B is that the manufacturing method of the present invention is applied to a barrier insulating film 39a in contact with a wiring mainly composed of a copper film among the interlayer insulating films 39 including the barrier insulating films 39a and 39c. That is the point.

  Hereinafter, a method for manufacturing a semiconductor device according to the third embodiment will be described. 9A and 9B, the same reference numerals as those in FIGS. 8A and 8B indicate the same components as those in FIGS. 8A and 8B. The description is omitted.

First, in the same manner as in the second embodiment, a wiring buried insulating film 32 made of a SiO ₂ film or SiOCH film having a thickness of about 1 μm and a wiring buried insulating film In the wiring groove of the film 32, a wiring 33b mainly composed of a copper film and a lower wiring made of a TaN film 33a are formed.

Next, a barrier insulating film 39a in contact with the copper film in the wiring interlayer insulating film 39 is formed by a plasma CVD method using a film forming gas of HMDSO + N ₂ O + NH ₃ . The details will be described below.

That is, in order to form the barrier insulating film 39 a, first, the substrate 21 to be formed is introduced into the chamber 1 of the film forming apparatus 101 and held by the substrate holder 3. Subsequently, the deposition target substrate 21 is heated to a temperature of 375 ° C. HMDSO is introduced at a flow rate of about 50 sccm, N ₂ O is introduced at a flow rate of about 200 sccm, and NH ₃ gas is introduced at a flow rate of about 50 sccm into the chamber 1 of the plasma film forming apparatus 101 shown in FIG. 1, and the pressure is maintained at 0.7 Torr. . Note that a He gas may be added to the film forming gas, and in this case, the flow rate may be about 400 sccm.

  Next, a low-frequency power of about 150 W having a frequency of 380 kHz is applied to the lower electrode 3. No high-frequency power is applied to the upper electrode 2.

As a result, HMDSO, N ₂ O, and NH ₃ are turned into plasma. While maintaining this state for 5 seconds, a low-voltage insulating film 39aa made of a 10-nm-thick PE-CVD SiO ₂ film is formed.

  Subsequently, using the same combination of reaction gases, maintaining the same flow rate, adjusting the gas pressure to 1.5 Torr, and forming a film under the same plasma excitation conditions. A high-voltage insulating film 39ab made of a PE-CVD SiOCN film having a thickness of about 90 nm is formed.

  As described above, the barrier insulating film 39a including the low-voltage insulating film 39aa and the high-voltage insulating film 39ab is formed.

  Then, a main insulating film 39b having a low dielectric constant and a barrier insulating film 39c are sequentially formed on the barrier insulating film 39a by an ordinary well-known method of forming an insulating film having a low dielectric constant. To form

  Next, as in the second embodiment, a wiring buried insulating film 35, a connection conductor 36, an upper wiring 37, and a barrier insulating film 38 are sequentially formed on the wiring interlayer insulating film 39.

  As described above, according to this embodiment, when forming the interlayer insulating film 39 including the barrier insulating films 39a and 39c on the wiring mainly including the copper film, the barrier insulating film 39a is formed. The film is formed as the low-voltage insulating film 39aa, and the remainder is formed as the high-voltage insulating film 39ab. Both the low-voltage insulating film 39aa and the high-voltage insulating film 39ab use low-frequency power to convert the film-forming gas into plasma.

  Although the adhesion is originally large when the film is formed by low-frequency power, the adhesion strength can be further improved by forming the film using a film-forming gas having a low gas pressure in the initial stage of the film formation.

  As described above, the present invention has been described in detail with reference to the third embodiment. However, the scope of the present invention is not limited to the example specifically shown in the above embodiment, and a range that does not depart from the gist of the present invention. Modifications of the above embodiment are included in the scope of the present invention.

Instead of the HMDSO used in the third embodiment, another alkyl compound having a siloxane bond described in the first embodiment may be used, or methylsilane (SiH _n (CH ₃ ) _4-n : n = 0) , 1, 2, 3) can be used. The type of methylsilane has been described in the first embodiment, and will not be described here.

Further, the deposition gas may be a nitrogen-containing gas containing any one of ammonia (NH ₃ ) and nitrogen (N ₂ ).

Further, the deposition gas may be an inert gas containing any one of helium (He), argon (Ar), and nitrogen (N ₂ ). As a result, so-called cloudiness of the film formation can be prevented.

  The insulating film 39b of the interlayer insulating film 39 may be formed by the method for forming the insulating film 34b of the second embodiment. Further, among the interlayer insulating films 39, the barrier insulating film 39c may be formed by the same film formation method as the barrier insulating film 39a. However, the side in contact with the upper wiring 37 is a low-voltage insulating film. Further, the barrier insulating film 38 may be formed by the same film forming method as the barrier insulating film 39a.

(Fourth embodiment)
In the above embodiment, in addition to the main insulating film having a low dielectric constant, there is an application to a method of forming a barrier insulating film underlying the main insulating film. For the purpose, the gas pressure does not need to be changed during film formation, and an alkyl compound having a siloxane bond, acetylene (C ₂ H ₂ ), methylcyclohexane (CH ₃ C ₆ H ₁₁ ) or cyclohexane (C ₆ H ₁₂ ) And a film-forming gas containing an oxygen-containing gas, or a film-forming gas containing an alkyl compound having a siloxane bond, benzene (C ₆ H ₆ ), an oxygen-containing gas, and an inert gas. In this manner, a desired main insulating film can be formed while maintaining the same gas pressure.

  A method for manufacturing a semiconductor device according to the fourth embodiment will be described with reference to FIGS.

  The difference from the third embodiment is that the interlayer insulating film 39 including the upper and lower barrier insulating films 39a and 39c and the main insulating film 39b having a low dielectric constant is sandwiched between the barrier insulating films 39a and 39c. The point is that the manufacturing method of the present invention is applied to the main insulating film 39b having a low dielectric constant.

  Hereinafter, a method for manufacturing a semiconductor device according to the fourth embodiment will be described. The conditions for forming the main insulating film 39b are as follows.

Deposition gas HMDSO flow rate: 50 sccm
N ₂ O flow rate: 200 sccm
CH ₃ C ₆ H ₁₁ flow rate: 50 sccm
Gas pressure (parameter): 0.9 Torr
Plasma excitation condition Lower electrode (first electrode)
Low frequency power (frequency 380 kHz) (parameter): 0 W
Upper electrode (second electrode)
High frequency power (frequency 13.56 MHz): 250 W
Substrate heating condition: 375 ° C
First, in the same manner as in the second embodiment, a wiring buried insulating film 32 made of a PE-CVD SiO ₂ film having a thickness of about 1 μm and a wiring buried insulating film In the wiring groove of the film 32, a wiring 33b mainly composed of a copper film and a lower wiring made of a TaN film 33a are formed.

Next, as in the third embodiment, a barrier insulating film 39a in contact with the copper film in the wiring interlayer insulating film 39 is formed by a plasma CVD method using a deposition gas of HMDSO + N ₂ O + NH ₃ . The barrier insulating film 39a includes a low-voltage insulating film 39aa and a high-voltage insulating film 39ab.

  Next, a main insulating film 39b having a low dielectric constant and a barrier insulating film 39c are sequentially formed on the barrier insulating film 39a by a plasma CVD method using the above-described film forming gas, and a wiring interlayer insulating film 39 is formed.

In order to form the main insulating film 39b having a low dielectric constant, first, the deposition target substrate 21 is introduced into the chamber 1 of the deposition apparatus 101, and is held by the substrate holder 3. Subsequently, the deposition target substrate 21 is heated to a temperature of 375 ° C. HMDSO at a flow rate of 50 sccm, a flow rate 200sccm the N ₂ O gas, hold CH ₃ C ₆ H ₁₁ at a flow rate of 50 sccm, was introduced into the chamber 1 of the plasma film forming apparatus 101 shown in FIG. 1, the pressure in 0.9Torr I do. Next, a high frequency power of 250 W (corresponding to 0.3 W / cm ² ) having a frequency of 13.56 MHz is applied to the upper electrode 2. At this time, no low-frequency power is applied to the lower electrode 3.

Thus, HMDSO, N ₂ O, and CH ₃ C ₆ H ₁₁ are turned into plasma. While maintaining this state for 40 seconds, a main insulating film 39b made of a PE-CVD SiO ₂ film having a thickness of about 500 nm is formed.

  Next, as in the second embodiment, a wiring buried insulating film 35, a connection conductor 36, an upper wiring 37, and a barrier insulating film 38 are sequentially formed on the wiring interlayer insulating film 39.

  As described above, the present invention has been described in detail with reference to the fourth embodiment. However, the scope of the present invention is not limited to the examples specifically shown in the above-described embodiment, and the scope of the present invention does not depart from the gist of the present invention. Modifications of the above embodiment are included in the scope of the present invention.

Instead of the HMDSO used in the fourth embodiment, the other alkyl compound having a siloxane bond described in the first embodiment may be used, or methylsilane (SiH _n (CH ₃ ) _4-n : n = 0) , 1, 2, 3) can be used. The type of methylsilane has been described in the first embodiment, and will not be described here.

Further, the deposition gas may be an inert gas containing any one of helium (He), argon (Ar), and nitrogen (N ₂ ). In this case, benzene (C ₆ H ₆ ) may be used instead of acetylene (C ₂ H ₂ ), methylcyclohexane (CH ₃ C ₆ H ₁₁ ) or cyclohexane (C ₆ H ₁₂ ). .

FIG. 1 is a side view illustrating a configuration of a plasma film forming apparatus used in a method of manufacturing a semiconductor device according to an embodiment of the present invention. 4 is a graph showing a relationship between a peeling strength and a gas pressure of a deposition gas for a low dielectric constant insulating film according to the first embodiment of the present invention. 5 is a graph showing a relationship between peeling strength and low-frequency power for substrate bias when a film forming gas for a low dielectric constant insulating film according to the first embodiment of the present invention is turned into plasma. 3 is a graph showing the relationship between film hardness and Young's modulus with respect to the gas pressure of a film forming gas of a low dielectric constant insulating film according to the first embodiment of the present invention. 4 is a graph showing a relationship between film hardness and Young's modulus with respect to low-frequency power for substrate bias when a deposition gas for a low dielectric constant insulating film according to the first embodiment of the present invention is turned into plasma. 4 is a graph showing a relationship between a relative dielectric constant and a low-frequency power for substrate bias when a deposition gas for a low dielectric constant insulating film according to the first embodiment of the present invention is turned into plasma. FIG. 3 is a diagram illustrating a film forming procedure according to the first embodiment of the present invention. (A), (b) is sectional drawing which shows the semiconductor device which is the 2nd Embodiment of this invention, and its manufacturing method. (A), (b) is sectional drawing which shows the semiconductor device which is the 3rd and 4th embodiment of this invention, and its manufacturing method.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Chamber 2 Upper electrode 3 Lower electrode 4 Exhaust pipe 5 Valve 6 Exhaust device 7 High frequency power supply power supply (RF power supply)
8 Low frequency power supply power supply 9a Pipes 9b to 9j Branch pipes 10a to 10n, 10p to 10z Opening and closing means 11a to 11i Flow rate adjusting means 12 Heater 21 Deposition substrate 31 Substrate 32 Lower wiring embedded insulating film (SiO ₂ film or SiOCH film)
33 Lower wiring 33a, 36a, 37a TaN film 33b, 36b, 37b Copper film 34, 39 Wiring interlayer insulating film 34a, 39aa Low voltage insulating film 34b, 39ab High voltage insulating film 35 Upper wiring buried insulating film (SiO ₂ film or SiOCH film) )
36 connection conductor 37 upper wiring 38, 39a, 39c barrier insulating film 39b main insulating film 101A film forming unit 101B film forming gas supply unit

Claims (10)

In a method for manufacturing a semiconductor device, a film forming gas is turned into plasma and reacted to form an insulating film having a low dielectric constant on a substrate.
The method of manufacturing a semiconductor device, wherein the film forming gas contains an alkyl compound having a siloxane bond, a hydrocarbon (C _x H _y ), and an oxygen-containing gas. Examples of the alkyl compound having a siloxane bond include hexamethyldisiloxane (HMDSO: (CH ₃ ) ₃ Si—O—Si (CH ₃ ) ₃ ) and octamethylcyclotetrasiloxane (OMCTS: ((CH ₃ ) ₂ ) ₄ Si ₄ O ₄ ),

Or tetramethylcyclotetrasiloxane (TMCTS: (CH ₃ H) ₄ Si ₄ O ₄ )

2. The method for manufacturing a semiconductor device according to claim 1, wherein the method is any one of the following. The hydrocarbon (C _x H _y ) is any one of acetylene (C ₂ H ₂ ), methylcyclohexane (CH ₃ C ₆ H ₁₁ ), cyclohexane (C ₆ H ₁₂ ) and benzene (C ₆ H ₆ ). 3. The method of manufacturing a semiconductor device according to claim 1, wherein The film forming gas, instead of the alkyl compound having the siloxane bond, methylsilane _{(SiH n (CH 3) 4} -n: n = 0,1,2,3) according to claim 1, characterized in that comprising Or a method of manufacturing a semiconductor device according to item 3. The methyl silane (SiH _n (CH ₃ ) _4-n : n = 0, 1, 2, 3) is monomethyl silane (SiH ₃ (CH ₃ )), dimethyl silane (SiH ₂ (CH ₃ ) ₂ ), trimethyl silane _{(SiH (CH 3) 3)} , or method according to claim 4, wherein it is any one of tetramethylsilane _{(Si (CH 3) 4)} . The deposition gas, helium (He), argon (Ar) or nitrogen (N ₂₎ a method of manufacturing a semiconductor device in any one of claims 1 to 5, characterized in that the invention will include any one of the.   A semiconductor device in which an insulating film is formed on a wiring mainly composed of a copper film, wherein the insulating film has a low dielectric constant formed by the method of manufacturing a semiconductor device according to claim 1. A semiconductor device, comprising: an insulating film having the same.   8. The semiconductor device according to claim 7, wherein the insulating film formed on the wiring mainly composed of the copper film forms an interlayer insulating film sandwiched between the wiring mainly composed of the copper film.   A semiconductor device in which at least a barrier insulating film in contact with a wiring mainly including a copper film is formed over a wiring mainly including a copper film, and an insulating film over the barrier insulating film is formed. 7. A semiconductor device, which is an insulating film having a low dielectric constant formed by the method for manufacturing a semiconductor device according to any one of 1 to 6.   A barrier insulating film formed on the copper film-based wiring and in contact with the copper film-based wiring, and an insulating film on the barrier insulating film interposed between the copper film-based wiring and an interlayer insulating film 10. The semiconductor device according to claim 9, comprising a film.

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