JP2004140219A - Semiconductor fabricating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable an interlayer insulation film 25 to be embedded in a gaps between the interconnections 23 on a semiconductor substrate without damaging the insulation film 22 of its underlayer on the semiconductor substrate 21 by plasma ions, and without charging up the underlayer in a semiconductor fabricating method for forming the interlayer insulation film for filling the gaps between the interconnections 23. <P>SOLUTION: On the insulation film 22 containing the interconnections 23 in the semiconductor substrate 21 including the interconnections 23 on the insulation film 22, a thin protection film 24 is formed without applying a substrate bias voltage, and thereafter the interlayer insulating film 25 is formed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device in which an interlayer insulating film of a semiconductor device is formed by using a high-density plasma CVD method for applying high-frequency power to a semiconductor substrate.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a wiring configuration in a semiconductor device due to miniaturization of circuit elements of the semiconductor device requires multilayer wiring. In addition, the distance between lines and the line width due to miniaturization are reduced. However, in order to avoid an increase in wiring resistance due to the miniaturization of the wiring, a certain wiring cross-sectional area is required.
[0003]
For this reason, the height of the wiring is increased and the actual resistance is reduced. However, in order to bury the interlayer insulating film in a wiring pattern having a high aspect ratio in which the distance between the wirings is narrow and the height of the wiring is high, for example, bias plasma CVD for applying a high frequency power to a silicon substrate has a good embedding property. The law is mainly used.
[0004]
3A to 3C are views for explaining an example of a conventional method for manufacturing a semiconductor device. This manufacturing method is a method of forming an interlayer insulating film on a metal wiring having a narrow or wide interval. First, as shown in FIG. 3A, an insulating film 102 is formed on the surface of a silicon substrate 101, and patterned lower wirings 107a to 107e are formed on the insulating film 102.
[0005]
Next, as shown in FIG. 3B, high-frequency power is applied to the silicon substrate 101, and a thin silicon oxide film 108 is formed by a high-density plasma method with a high substrate bias of 13.5 MHz. That is, by forming a silicon oxide film at a frequency that plasma ions cannot follow, generation of interface states of a gate oxide film of a base transistor or the like is suppressed.
[0006]
Next, as shown in FIG. 3C, a silicon oxide film 109 is formed by using a low-frequency substrate bias of 400 kHz that can follow ions. As described above, in order to avoid plasma damage on the substrate, an oxide film is first formed by biasing at a high frequency that does not cause plasma damage, and thereafter, plasma ions are drawn in and a thick oxide film is formed between the wirings. It is embedded (see Patent Document 1).
[0007]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 11-154673 (Pages 12-13, FIG. 1)
[0008]
[Problems to be solved by the invention]
In the above-described conventional method for manufacturing a semiconductor device, although a thin oxide film is formed by applying a substrate bias having a high frequency that cannot follow ions, there is a risk that light ions or electrons in the plasma may be attracted. For this reason, the drawn electrons and light ions collide with the semiconductor substrate, causing a problem that the gate oxide film of the MOS transistor is damaged, not only shaving the oxide film underlying the semiconductor substrate, but also charging up the oxide film. .
[0009]
Further, when the gap between the wirings is filled with the interlayer insulating film, the frequency of the substrate bias must be changed, which is troublesome in operation. Further, there is a disadvantage that two high-frequency power sources are required and the equipment cost is increased.
[0010]
Accordingly, an object of the present invention is to provide an interlayer insulating film in a gap between wirings on a semiconductor substrate without scratching the underlying layer of a wiring layer formed on the semiconductor substrate with plasma ions or charging up the underlying layer. An object of the present invention is to provide a method for manufacturing a semiconductor device which can be embedded.
[0011]
[Means for Solving the Problems]
A feature of the present invention is a method of manufacturing a semiconductor device in which an interlayer insulating film is buried in a gap between wirings of a semiconductor device by using a high-density plasma CVD method in which high-frequency power is applied to the semiconductor substrate, wherein the insulating film is formed on the semiconductor substrate. Forming, forming a conductive layer on the insulating film, forming a wiring on the conductive layer by patterning, and then forming a protective insulating film on the wiring including the insulating layer. And a method for manufacturing a semiconductor device.
[0012]
Further, it is preferable that after forming the protective insulating film, an interlayer insulating film that fills a gap between the wirings is formed. Further, the thickness of the protective insulating film is desirably at least 20 nm. Further, it is desirable that the high-density plasma CVD method is a high-density plasma CVD method using an inductively coupled plasma generator.
[0013]
Another feature of the present invention is that a reaction chamber for accommodating a pedestal on which an insulating film is formed and a semiconductor substrate having wiring on the insulating film is placed, and a first induction coil disposed at the top of the reaction chamber A second induction coil disposed on a side wall of the reaction chamber, a top nozzle for leading a reaction gas from a top of the reaction chamber, a side nozzle for leading a reaction gas from a side wall of the reaction chamber, In an inductively coupled plasma CVD apparatus including a high frequency power supply for applying a substrate bias to a semiconductor substrate, the reaction gas is led out from the top nozzle to the depressurized reaction chamber, and a high frequency is supplied to the first and second induction coils. A semiconductor device in which plasma is generated by applying power and a protective film is formed on an insulating film of the semiconductor substrate including the wiring without applying a substrate bias to the semiconductor substrate. It is a production method.
[0014]
Further, after forming the protective film, the reaction gas is led out from the top nozzle and the side nozzle, high-frequency power is applied to the first and second induction coils to generate plasma, and the substrate is formed on the semiconductor substrate. It is desirable to apply a bias to form an interlayer insulating film that fills the space between the wirings of the semiconductor substrate.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a schematic cross-sectional view showing a configuration of an inductively coupled plasma CVD apparatus for describing a method of manufacturing a semiconductor device according to an embodiment of the present invention. As shown in FIG. 1, the inductively coupled plasma CVD apparatus, which is a high-density plasma CVD apparatus, has an induction coil 9 arranged at the top of the reaction chamber 1 and an induction coil 8 wound around the outer wall. Further, a top nozzle 3 and a side nozzle 2 for introducing a reaction gas into the reaction chamber 1 are provided. Then, plasma is generated in the reaction chamber 1 by applying the high-frequency power of the high-frequency power supply 11 and the high-frequency power of the high-frequency power supply 10 to the induction coil 8 and the induction coil 9 and the introduced reaction gas.
[0017]
The wafer 20 as a substrate to be processed is electrostatically attracted and held on a pedestal 4 whose surface is coated with ceramic or the like. Then, the rising temperature of the wafer is suppressed by helium supplied from the cooling gas supply device 7 to the back surface of the wafer 20. Even when heated by the plasma, for example, the temperature of wafer 20 is maintained at 350 degrees Celsius.
[0018]
On the other hand, the reaction gas supplied to the reaction chamber 1 is introduced from the top nozzle 3 at the top and the side nozzle 2 at the side wall. From top nozzle 3 is supplied with Ar and _{O 2} and a silane gas (SiH _4), likewise Ar and _{O 2} and a silane gas from the side nozzle 2 (SiH ₄₎ is supplied. The introduced reaction gas is depressurized by the turbo pump 6 and is adjusted by the throttle valve 13 so that the pressure becomes easily dischargeable.
[0019]
A high frequency power supply 10 and a high frequency power supply 11 for applying a high frequency power of 2 MHz are connected to the induction coil 9 and the induction coil 8 for exciting the plasma. On the other hand, a 13.56 MHz high frequency power supply 12 serving as a substrate bias is connected to the lower electrode 5 including the pedestal 4, and the action of attracting ions in the plasma is generated by applying the substrate bias. By applying this substrate bias, the sputter rate in the inclined portion is increased by utilizing the inclination angle dependence of the sputter etching rate due to argon ions.
[0020]
2A to 2D are cross-sectional views illustrating a method of manufacturing a semiconductor device according to an embodiment of the present invention in the order of steps for explaining the method. Next, a method for manufacturing a semiconductor device will be described with reference to FIGS.
[0021]
First, as shown in FIG. 2A, an insulating film 22 which is an oxide film is formed on a semiconductor substrate 21, a wiring layer is formed thereon, a resist is applied, and the resist is used as a mask, and the wiring layer is patterned. And the wiring 23 shown in FIG. 2B is formed. This step can also be performed by a general parallel plate type plasma CVD apparatus or ECR plasma CVD apparatus.
[0022]
Next, the semiconductor substrate 21 is placed on the pedestal 4 of the inductively coupled plasma CVD apparatus shown in FIG. 1, and the pressure in the reaction chamber 1 is reduced by the turbo pump 6. When the reaction chamber 1 reaches a predetermined pressure, 16 sccm of Ar, 45 sccm of O _2, and 18 sccm of SiH ₄ are led out of the top nozzle 3 into the reaction chamber 1, and high-frequency power is supplied from the high-frequency power supplies 11 and 10 to the induction coils 8 and 9. To generate plasma. As a result, radicals having no charge in the plasma adsorb to the semiconductor substrate heated by the plasma, and as shown in FIG. 2C, a thin silicon oxide film is formed on the insulating film 22 and the wiring 23. A protective film 24 having a similar thickness is formed.
[0023]
Since no substrate bias is applied to the semiconductor substrate, ions in the plasma are not drawn in, so that the insulating film 22 is not damaged and the gate oxide film is not broken. From various experiments, it is necessary that the thickness of the protective film 24 be at least 20 nm. The time required to reach the thickness of the protective film 24 is obtained in a few seconds.
[0024]
After forming the protective film 24, 16 sccm of Ar, 20 sccm of O ₂ , 9.5 sccm of SiH ₄ were led out to the reaction chamber 1 from the top nozzle 3, and 110 sccm of Ar and 120 sccm of O ₂ were introduced from the side nozzle 2. , SiH ₄ is led out to the reaction chamber 1 at 56 sccm, and high-frequency power is applied to the induction coil to generate plasma. Then, high frequency power, for example, 2000 to 3500 W is applied to the semiconductor substrate by the high frequency power supply 12 as a substrate bias.
[0025]
As a result, ions in the plasma are attracted, and deposition and sputtering occur simultaneously with the inclination angle dependence of the sputter etching rate due to the argon ions. As shown in FIG. The interlayer insulating film 25 is formed so as to fill the space. Further, a helium gas is supplied from the cooling gas supply device 7 so that the semiconductor substrate heated by the plasma does not rise in temperature, and the semiconductor substrate is cooled and maintained at 400 degrees Celsius.
[0026]
After the formation of the interlayer insulating film 25, the protrusion of the interlayer insulating film immediately above the wiring 23 is polished flat by CMP or the like.
[0027]
【The invention's effect】
As described above, the present invention forms a thin protective film on a semiconductor substrate having wiring on an insulating film on an insulating film including the wiring without applying a substrate bias, and then forms an interlayer insulating film. Therefore, an interlayer insulating film can be formed on the underlying insulating film without causing plasma damage or undercutting of the underlying film, and the yield of quality is improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of an inductively coupled plasma CVD apparatus for describing a method of manufacturing a semiconductor device according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a method of manufacturing a semiconductor device according to an embodiment of the present invention in the order of steps for describing the method.
FIG. 3 is a diagram illustrating an example of a conventional method for manufacturing a semiconductor device.
[Explanation of symbols]
Reference Signs List 1 reaction chamber 2 side nozzle 3 top nozzle 4 pedestal 5 lower electrode 6 turbo pump 7 cooling gas supply device 8, 9 induction coil 10, 11, 12 high frequency power supply 13 throttle valve 21 semiconductor substrate 22 insulating film 23 wiring 24 protective film 25 Interlayer insulating film

Claims (6)

A method of manufacturing a semiconductor device in which an interlayer insulating film is buried in a gap between wirings of a semiconductor device by using a high-density plasma CVD method of applying high-frequency power to a semiconductor substrate; Forming a conductive layer on an insulating film, forming a wiring on the conductive layer by patterning, and then forming a protective insulating film on the wiring including the insulating layer. A method for manufacturing a semiconductor device. 2. The method of manufacturing a semiconductor device according to claim 1, wherein after forming the protective insulating film, an interlayer insulating film filling a gap between the wirings is formed. 3. The method according to claim 1, wherein the thickness of the protective insulating film is at least 20 nm. 4. The method according to claim 1, wherein the high-density plasma CVD is a high-density plasma CVD using an inductively coupled plasma generator. A reaction chamber for housing a pedestal on which an insulating film is formed and on which a semiconductor substrate having wirings is mounted, a first induction coil disposed at the top of the reaction chamber, and a side wall of the reaction chamber. A second induction coil disposed, a top nozzle for leading a reaction gas from the top of the reaction chamber, a side nozzle for leading a reaction gas from a side wall of the reaction chamber, and applying a substrate bias to the semiconductor substrate In an inductively coupled plasma CVD apparatus having a high frequency power supply, the reaction gas is led out from the top nozzle to the depressurized reaction chamber, and high frequency power is applied to the first and second induction coils to generate plasma Forming a protective film on an insulating film of the semiconductor substrate including the wiring without applying a substrate bias to the semiconductor substrate. Law. After forming the protective film, the reaction gas is led out from the top nozzle and the side nozzle, high-frequency power is applied to the first and second induction coils to generate plasma, and a substrate bias is applied to the semiconductor substrate. 6. The method for manufacturing a semiconductor device according to claim 5, wherein the interlayer insulating film is formed so as to fill between the wirings of the semiconductor substrate by applying the voltage.

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