JP2009246129A - Method for forming plasma cvd silicon nitride film and method for manufacturing semiconductor integrated circuit device - Google Patents

Abstract

Deposition of a plasma CVD silicon nitride film capable of reducing N—H bonds and reducing the total amount of hydrogen in the total film, which is the sum of N—H bonds and Si—H bonds Providing a method.
A process for introducing a silicon-containing gas and a nitrogen- and hydrogen-containing gas into a processing container, a microwave radiated into the processing container, and a silicon-containing gas introduced into the processing container and A step of converting nitrogen- and hydrogen-containing gas into plasma, supplying plasma-converted silicon-containing gas and nitrogen- and hydrogen-containing gas onto the surface of the substrate W to be processed, and forming a silicon nitride film on the surface of the substrate W to be processed; Forming a silicon nitride film, the processing temperature is 300 ° C. or more and 600 ° C. or less, and the flow rate ratio between the silicon-containing gas and the nitrogen- and hydrogen-containing gas is 0.005 or more and 0.015 or less. the microwave power 0.5 W / cm ² or more 2.045W / cm ² or less, the process pressure and 133.3Pa than 13333Pa less.
[Selection] Figure 1

Description

  The present invention relates to a plasma CVD silicon nitride film forming method for forming a plasma CVD silicon nitride film used as an insulating film or a protective film in a semiconductor integrated circuit device, and a method for manufacturing a semiconductor integrated circuit device.

Silicon nitride films are used as insulating films and protective films in semiconductor integrated circuit devices. Such a silicon nitride film is formed by using, for example, a low pressure plasma CVD method using a silicon-containing compound gas such as silane (SiH ₄ ) as a source gas and a nitrogen-containing compound gas such as nitrogen gas or ammonia. It is known that a film can be formed. The low-pressure plasma CVD method is usually a plasma CVD method in which film formation is performed at a processing pressure of 1000 mTorr (133.3 Pa) or less.

  When a silicon nitride film is formed using a low pressure plasma CVD method using silane gas and nitrogen gas, a film with few N—H bonds is obtained although Si—H bonds are generated. Instead, since nitrogen gas is harder to decompose than ammonia gas, it is difficult to control, and excess Si is likely to be generated in the film.

  On the other hand, in the low pressure plasma CVD method using silane gas and ammonia gas, the reaction is more likely to occur and controllability is better than when nitrogen gas is used. However, the silicon nitride film contains a large amount of N—H bonds in addition to the Si—H bond, and the total amount of hydrogen in the film, which is the sum of the amount of Si—H bonds and the amount of N—H bonds, Compared to a silicon nitride film formed using nitrogen gas, the amount tends to increase.

  As the total amount of hydrogen in the silicon nitride film increases, the probability that vacancies are generated due to the escape of hydrogen from the film increases. When holes are generated in the film, for example, it becomes an electron trap, which accelerates deterioration of the film quality and greatly affects the life of the semiconductor integrated circuit device.

  Patent Document 1 describes that the hydrogen concentration in a silicon nitride film is one factor that affects the characteristics of a semiconductor device, for example, the threshold value of a transistor.

In particular, in Patent Document 1, the hydrogen concentration in the silicon nitride film formed on the control gate is controlled in the range of 1.5 × 10 ²¹ atoms / cm ^{3 to} 2.6 × 10 ²¹ atoms / cm ^3. Otherwise, it is described that it is difficult to suppress the threshold fluctuation of the nonvolatile memory cell.
JP 2006-173479 A

  Patent Document 1 describes the hydrogen concentration in the silicon nitride film. Whether the hydrogen concentration is a hydrogen concentration derived from a Si—H bond or a hydrogen concentration derived from an N—H bond, both The total hydrogen concentration is not clarified at all.

In the first place, the silicon nitride film described in Patent Document 1 is a thermal CVD silicon nitride film formed by using a low pressure CVD method. The thermal CVD silicon nitride film is a silicon nitride film (Si ₃ N ₄ film) having a stoichiometry of 0.75. The silicon nitride film described in Patent Document 1 is not a plasma CVD silicon nitride film formed using a plasma CVD method.

On the other hand, the plasma CVD silicon nitride film is a silicon nitride film (SiN _x film) whose stoichiometry changes depending on processing conditions. An example of stoichiometry of the plasma CVD silicon nitride film is 0.8 or more. Such a plasma CVD silicon nitride film is more likely to generate Si—H bonds and N—H bonds than a thermal CVD silicon nitride film, and the total amount of hydrogen in the total of the two results in the thermal CVD silicon nitride film. There is a tendency to increase in comparison.

  According to the present invention, the formation of a plasma CVD silicon nitride film capable of reducing N—H bonds and reducing the total amount of hydrogen in the total film, which is the sum of N—H bonds and Si—H bonds. It is an object of the present invention to provide a film method and a method for manufacturing a semiconductor integrated circuit device using the film formation method.

In order to solve the above-described problem, a plasma CVD silicon nitride film forming method according to a first aspect of the present invention is a plasma CVD silicon nitride film forming method using microwave-excited plasma, and a processing vessel A step of introducing a silicon-containing gas, a nitrogen- and hydrogen-containing gas, and a microwave is radiated into the processing vessel, and the silicon-containing gas and the nitrogen- and hydrogen-containing gas introduced into the processing vessel The plasma-containing silicon-containing gas and the nitrogen- and hydrogen-containing gas are supplied onto the surface of the substrate to be processed, and a silicon nitride film is formed on the surface of the substrate to be processed. A film forming condition of the silicon nitride film, a processing temperature of 300 ° C. to 600 ° C., a flow rate ratio of a silicon-containing gas to nitrogen and hydrogen-containing gas of 0.005 to 0.015, a microphone A wave power 0.5 W / cm ² or more 2.045W / cm ² or less, the process pressure and 133.3Pa than 13333Pa less.

According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor integrated circuit device, comprising: forming an etching stopper containing a material different from the insulating film on the insulating film; and the etching stopper above the etching stopper. A step of forming an interlayer insulating film containing a material different from the above, a step of forming a hard mask containing a material different from the interlayer insulating film on the interlayer insulating film, and using the hard mask as an etching mask, Forming a groove or a hole in the interlayer insulating film, wherein at least one of the etching stopper and the hard mask is a silicon nitride film, and a film forming condition of the silicon nitride film is set at a processing temperature. 300 ° C. or more and 600 ° C. or less, the flow rate ratio of the silicon-containing gas and nitrogen and hydrogen-containing gas is 0.005 or more and 0.015 or less, and the microwave power is 5W / cm ² or more 2.045W / cm ² or less, the process pressure and 133.3Pa than 13333Pa less.

According to a third aspect of the present invention, there is provided a method for manufacturing a semiconductor integrated circuit device, comprising: forming a gate electrode on a semiconductor substrate that is insulated from the semiconductor substrate and having a cap layer thereon; and masking the gate electrode And a step of introducing impurities for forming source / drain regions into the semiconductor substrate, and a step of forming a side wall spacer on the side wall of the gate electrode, and the cap layer and the side wall spacer. At least one of them is a silicon nitride film, and the film formation conditions of the silicon nitride film are as follows: the processing temperature is 300 ° C. or more and 600 ° C. or less, and the flow ratio of the silicon-containing gas and the nitrogen- and hydrogen-containing gas is 0.005 or more. 0.015 or less, a microwave power of 0.5 W / cm ² or more 2.045W / cm ² or less, the process pressure and 133.3Pa than 13333Pa less.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a semiconductor integrated circuit device, comprising: forming a gate electrode insulated from a semiconductor substrate on a semiconductor substrate; and using the gate electrode as a mask to form a source / drain Introducing a region forming impurity into the semiconductor substrate; and forming a stress liner on the semiconductor substrate to cover the gate electrode and apply stress to a portion of the semiconductor substrate under the gate electrode; The stress liner is a silicon nitride film, the film forming conditions for the silicon nitride film are a processing temperature of 300 ° C. or higher and 600 ° C. or lower, and a flow rate ratio of a silicon-containing gas and nitrogen and hydrogen-containing gas is 0. .005 least 0.015 or less, the microwave power 0.5 W / cm ² or more 2.045W / cm ² or less, the process pressure 133.3Pa than 13333Pa less To.

  According to the present invention, a plasma CVD silicon nitride film that can reduce N—H bonds and can reduce the total hydrogen amount in the total film, which is the sum of N—H bonds and Si—H bonds. And a method for manufacturing a semiconductor integrated circuit device using the film forming method.

  Embodiments of the present invention will be specifically described below with reference to the accompanying drawings as appropriate.

(First embodiment)
FIG. 1 is a cross-sectional view showing an example of a plasma CVD apparatus that can be used in the plasma CVD silicon nitride film forming method according to the first embodiment of the present invention.

  As shown in FIG. 1, the plasma CVD apparatus 100 radiates microwaves into a processing chamber (processing vessel) 1 by a RLSA (Radial Line Slot Antenna) which is a planar antenna having a plurality of slots. Thus, it is configured as an RLSA microwave plasma CVD apparatus for generating plasma.

  The plasma CVD apparatus 100 has a substantially cylindrical processing chamber (processing container) 1 that is airtight and grounded. In the processing chamber 1, a plasma CVD silicon nitride film is formed on a semiconductor wafer W that is a substrate to be processed. A circular opening 1b is formed at a substantially central portion of the bottom wall 1a of the processing chamber 1, and an exhaust chamber 2 that communicates with the opening 1b and protrudes downward is provided on the bottom wall 1a. Yes.

  Inside the processing chamber 1, a susceptor (substrate support) 3 made of ceramics such as AlN for horizontally supporting the wafer W is provided. The susceptor 3 is supported by a support member 4 made of ceramic such as cylindrical AlN extending upward from the center of the bottom of the exhaust chamber 2. A guide ring 5 for guiding the wafer W is provided on the outer edge of the susceptor 3. A resistance heating type heater 6 is embedded in the susceptor 3. The heater 6 is supplied with power from a heater power source 6 a to heat the susceptor 3, and heats the wafer W with the heat of the susceptor 3. A thermocouple 6 b is embedded in the susceptor 3. The susceptor 3 is temperature-controlled in a range from room temperature to 1000 ° C., for example, by a temperature controller (TC) 6c based on a temperature signal detected by the thermocouple 6b. In addition, a lower electrode 6d is embedded in the susceptor 3, and is connected to an RF power source 6f through a matcher 6e.

  The exhaust chamber 2 is connected to an exhaust pipe 2a, and an exhaust device 2b including a vacuum pump is connected to the exhaust pipe 2a. The exhaust device 2b includes a vacuum pump such as a turbo molecular pump, a pressure control valve, and the like, and sets the inside of the processing chamber 1 to a predetermined reduced pressure atmosphere.

  A gate valve 9 is provided on the side wall portion of the processing chamber 1. By opening and closing the gate valve 9, the processing chamber 1 is communicated with the outside world or airtightly blocked from the outside world. The wafer W is carried into and out of the processing chamber 1 through the gate valve 9.

  The upper part of the processing chamber 1 is an opening, and the microwave introduction part 10 is airtightly arranged so as to close the opening. The microwave introduction unit 10 includes a microwave transmission plate 11, a planar antenna member 12, and a slow wave material 13 in order from the susceptor 3 side.

The microwave transmission plate 11 is disposed in an airtight manner via a seal member 15 on an annular support 14 provided in an opening at the top of the processing chamber 1. The microwave transmission plate 11 is made of a dielectric material that transmits microwaves, for example, ceramics such as quartz, Al ₂ O ₃ , and AlN.

  The planar antenna member 12 is provided above the microwave transmission plate 11 and is locked to the upper end of the opening of the processing chamber 1. The planar antenna member 12 is made of, for example, a copper plate or an aluminum plate having a surface plated with gold or silver, and a plurality of slot holes 16 for radiating microwaves are formed in a predetermined pattern. The slot hole 16 has a pair of long grooves as shown in FIG. Typically, adjacent slot holes 16 are arranged in a T shape, and a plurality of slot holes 16 arranged in a T shape are arranged concentrically. The length and the arrangement interval of the slot holes 16 are determined according to the wavelength (λg) of the microwave. For example, the interval of the slot holes 16 is arranged to be λg / 4 to λg. In FIG. 2, the interval between adjacent slot holes 16 formed concentrically is indicated by “Δr”. The shape of the slot hole 16 may be, for example, a circular shape or an arc shape. The arrangement of the slot holes 16 is not particularly limited to a concentric shape, and can be arranged in a spiral shape or a radial shape, for example.

The slow wave material 13 is provided on the planar antenna member 12. The slow wave material 13 is composed of a dielectric having a dielectric constant larger than that of vacuum, for example, quartz, ceramics such as Al ₂ O ₃ , fluorine-based resin such as polytetrafluoroethylene, or polyimide-based resin. Since the wavelength of the wave becomes long, it has a function of adjusting the plasma by shortening the wavelength of the microwave. The planar antenna member 12 and the microwave transmission plate 11 and the planar antenna member 12 and the slow wave member 13 may be in close contact with each other or may be separated from each other.

  A cover 17 is provided above the processing chamber 1 so as to cover the planar antenna member 12 and the slow wave material 13. The cover 17 forms a planar antenna and a flat waveguide, and is disposed on the upper surface of the processing chamber 1 via a seal member 18 so that microwaves do not leak outside. The cover 17 is made of, for example, a metal material such as aluminum or stainless steel, and a cooling water passage 17a is formed inside. The cover 17, the slow wave material 13, the planar antenna 12, and the microwave transmission plate 11 are cooled by flowing the cooling water through the cooling water flow path 17 a, and the cover 17, the slow wave material 13, the planar antenna 12, and the microwave transmission are transmitted. The deformation and breakage of the plate 11 are prevented. The cover 17 is grounded via an antenna and a processing chamber.

  An opening 17 b is formed in the center of the upper wall of the cover 17. A waveguide 18 is connected to the opening 17b. A mode converter 21 and a rectangular waveguide are connected to the end of the waveguide 18, and a microwave generator 20 is connected via a matching circuit 19. The microwave generator 20 generates a microwave having a frequency of 2.45 GHz, for example. The generated microwave is propagated to the planar antenna member 12 through the waveguide 18. As the microwave frequency, 2.45 GHz, 8.35 GHz, 1.98 GHz, or the like can be used.

  The waveguide 18 is a coaxial waveguide 18a having a circular cross section extending upward from the opening 17b of the cover 17, and extends to the center of the coaxial waveguide 18a, and is fixedly connected to the center of the planar antenna member 12. An inner conductor 18c, and a horizontally extending rectangular waveguide 18b connected to the upper end of the coaxial waveguide 18a via a mode converter 21. The mode converter 21 converts the microwave propagating in the rectangular waveguide 18b in the TE mode into the TEM mode, and efficiently and uniformly propagates radially to the planar antenna member 12 via the inner conductor 18c.

  Between the susceptor 3 and the microwave introduction part 10 in the processing chamber 1, a shower plate 22 for introducing a processing gas is provided horizontally. As shown in FIG. 3, the shower plate 22 has a lattice-like gas flow path 23 and a large number of gas discharge holes 24 formed in the lattice-like gas flow path 23. A space 25 is formed between the lattice-like gas flow paths 23, and the gas discharge holes 24 are formed on the susceptor 3 side of the gas flow paths 23. A gas supply pipe 26 extending to the outside of the processing chamber 1 is connected to the gas flow path 23. The gas supply pipe 26 is connected to a gas supply unit 27 that supplies a processing gas for plasma processing.

  The gas supply unit 27 includes a silicon-containing gas supply source 27a for supplying a silicon-containing gas and a nitrogen and hydrogen-containing gas supply source 27b for supplying nitrogen and a hydrogen-containing gas as processing gases. The gas supply unit 27 supplies these processing gases to the gas supply pipe 26, the lattice-like gas passage 23, and the gas discharge holes 24 formed on the susceptor 3 side of the lattice-like gas passage 23. A flow rate is supplied to the space 1 c between the shower head 22 and the susceptor 3 in the processing chamber 1. An example of a silicon-containing gas is disilane, and an example of a nitrogen and hydrogen-containing gas is ammonia.

  On the side wall of the processing chamber 1 between the shower plate 22 and the microwave introduction unit 10, an annular plasma generation gas introduction unit 28 is provided. The plasma generation gas introduction unit 28 includes a plurality of discharge holes 28 a for discharging the plasma generation gas toward the inside of the processing chamber 1. The plasma generation gas introduction unit 28 is connected to a gas supply pipe 29 that supplies a plasma generation gas, and the gas supply pipe 29 is connected to a gas supply unit 30 that supplies a plasma generation gas.

  The gas supply unit 30 includes a plasma generation gas supply source 30a that supplies a plasma generation gas. The gas supply unit 30 supplies the plasma generation gas at a predetermined flow rate through the gas supply pipe 29, the gas introduction unit 28, and the discharge holes 28 a, and the shower head 22 and the microwave introduction unit 10. To the space 1d between the two. An example of the plasma generating gas is argon.

  The plasma generating gas supplied to the space 1d is turned into plasma by the microwave introduced into the space 1d through the microwave introduction unit 10. The gas converted into plasma passes through the space 25 of the shower plate 22 and is supplied to the space 1c. In the space 1c, the processing gas discharged from the gas discharge holes 24 of the shower plate 22 is converted into plasma.

  Each component of the plasma CVD apparatus 100 is controlled by the control unit 40. The control unit 40 includes a process controller 41 having a CPU, a user interface 42 and a storage unit 43 connected to the process controller 41. The user interface 42 includes a keyboard that allows a process manager to input commands to manage the plasma CVD apparatus 100, a display that visualizes and displays the operating status of the plasma CVD apparatus 100, and the like. The storage unit 43 stores a recipe in which a control program (software) for realizing various processes executed by the plasma CVD apparatus 100 under the control of the process controller 41 and processing condition data are recorded. An arbitrary recipe is called from the storage unit 43 by an instruction from the user interface 42 as necessary, and is executed by the process controller 41. When the process controller 41 executes the recipe, the plasma CVD apparatus 100 performs a desired process under the control of the process controller 41. The recipe is stored in a computer-readable storage medium such as a CD-ROM, a hard disk, a flexible disk, or a flash memory, or from another device, for example, via a dedicated line. It can be transmitted at any time and used online.

  The plasma CVD apparatus 100 configured as described above can deposit a silicon nitride film on the surface of the wafer W by the plasma CVD method in the following procedure, for example.

  First, the gate valve 9 is opened, and the wafer W is loaded into the processing chamber 1 and placed on the susceptor 3.

Next, the plasma generation gas is introduced from the gas supply unit 30 into the space 1 d of the processing chamber 1 through the discharge hole 28 a and the microwave from the microwave generator 20 is passed through the matching circuit 19. The rectangular waveguide 18b, the mode converter 21, and the coaxial waveguide 18a are sequentially passed through and supplied to the planar antenna member 12 through the inner conductor 18c. The microwave supplied to the planar antenna member 12 is radiated into the space 1 d of the processing chamber 1 from the slot hole 16 of the planar antenna member 12 through the transmission plate 11. The plasma generation gas is excited into plasma by being excited by the emitted microwave. The microwave-excited plasma becomes a low electron temperature plasma of, for example, a high density of about 1 × 10 ^{10 to} 5 × 10 ¹² / cm ³ and 2 eV or less by radiating microwaves from a large number of slot holes 16. The plasmaized gas passes through the space portion 25 of the shower head 22 and is supplied to the space 1c.

Next, a processing gas is supplied from the processing gas supply unit 27 through a gas supply pipe 26, a lattice-shaped gas flow path 23, and a gas discharge hole 24 formed on the susceptor 3 side of the lattice-shaped gas flow path 23. Is supplied into the space 1c of the inside of the processing chamber 1 at a flow rate of 1. The processing gas is excited and plasmatized by the plasmatized gas that has passed through the lattice-shaped space 25. In the vicinity of the wafer W, for example, low electron temperature plasma of about 1.5 eV or less is obtained. The plasma thus formed has little plasma damage caused by ions or the like on the underlying film. Then, dissociation of the processing gas proceeds in the plasma. For example, silicon nitride SiN _x (where x is not necessarily determined stoichiometrically and varies depending on the processing conditions due to the reaction of active species such as SiH and NH. A thin film is deposited.

  A plasma CVD silicon nitride film is formed using the plasma CVD apparatus 100 shown in FIG. 1, and the amount of hydrogen (Si—H bond, N—H bond, and Si—H bond) in the formed plasma CVD silicon nitride film. And the N—H bond) were measured for processing temperature dependency, silicon-containing gas flow rate dependency, microwave power dependency, and processing pressure dependency. The silicon-containing gas used in this measurement is disilane, nitrogen, and the hydrogen-containing gas is ammonia. For the analysis of the film quality of the plasma CVD silicon nitride film, Fourier transform infrared spectroscopy (FT-IR) is used. From the intensity of the spectrum derived from the N—H bond and the intensity of the spectrum derived from the Si—H bond, The amount of N—H bonds and the amount of Si—H bonds were determined. Further, the total amount of hydrogen in the film (total H) was obtained by summing the obtained amount of N—H bonds and the amount of Si—H bonds.

  FIG. 4 is a diagram showing the treatment temperature dependence of the hydrogen amount, FIG. 4A shows the treatment conditions, and FIG. 4B shows the relationship between the hydrogen amount and the treatment temperature.

As shown in FIG. 4A, the processing conditions are such that the processing temperature is a parameter (indicated by “−” in the figure), and the flow ratio of disilane (Si ₂ H ₆ ) and ammonia (NH ₃ ) is “5 sccm / 500 sccm = 0. .01 ", the microwave power was 1.023 W / cm ² (2 kW), and the processing pressure was 950 mTorr. Under such processing conditions, the processing temperature was changed from 300 ° C. to 600 ° C. in steps of 100 ° C. The processing temperature is the heating temperature of the susceptor 3 in this example.

  As shown in FIG. 4B, when the processing temperature was changed from 300 ° C. to 400 ° C., the amount of Si—H bonds showed a gradual increase, whereas the amount of N—H bonds was greatly reduced. The total value of Si—H bonds and N—H bonds (hereinafter referred to as the total hydrogen content in the film (Total H)) was greatly reduced when the processing temperature was 400 ° C. compared to 300 ° C. This is thought to be difficult for NH to be taken in due to the supply rate limiting region.

  Furthermore, when the treatment temperature was changed from 400 ° C. to 500 ° C., the amount of Si—H bonds showed a large decreasing tendency, and the amount of N—H bonds increased gradually. The total amount of hydrogen in the film was gradually increased as the amount of N—H bonds was increased, but the amount of Si—H bonds was decreased by an amount exceeding the increase amount of N—H bonds, so that compared with the case where the processing temperature was 400 ° C. In the case of 500 ° C., it decreased.

Furthermore, when the processing temperature was changed from 500 ° C. to 600 ° C., the amount of Si—H bonds continued to decrease. The amount of N—H bonds remained almost unchanged and showed a tendency to saturate. The total amount of hydrogen in the film was reduced when the treatment temperature was 600 ° C. compared to when the treatment temperature was 500 ° C.
This is thought to be because the reaction does not proceed because of the reaction rate limiting region, and a lot of NH is not taken up. Thus, it is considered that the rate is controlled at a temperature of 400 ° C. or lower, and the rate is controlled at a temperature exceeding 400 ° C.

The total amount of hydrogen in the film has a tendency to decrease as the processing temperature is increased. From the order of 10 ²² (atoms / cc) at a processing temperature of 300 ° C. to 600 ° C., 10 ²¹ (atoms / cc). It was confirmed that it was possible to reduce to the order of.

  FIG. 5 is a diagram showing the dependence of the amount of hydrogen on the flow rate of silicon-containing gas, FIG. 5A shows the processing conditions, and FIG. 5B shows the relationship between the amount of hydrogen and the flow rate of silicon-containing gas.

As shown in FIG. 5A, the flow rate of the silicon-containing gas, in this example, disilane (Si ₂ H ₆ ) is a parameter (indicated by “−” in the figure), the processing temperature (temperature of the susceptor 3) is 500 ° C., ammonia ( The flow rate of NH ₃ ) was 1000 sccm, the microwave power was 1.023 W / cm ² (2 kW), and the processing pressure was 1000 mTorr. Under such processing conditions, the flow rate of disilane is changed to 5 sccm, 10 sccm, 12.5 sccm, and 15 sccm, and the flow rate ratio of disilane to ammonia is changed to 0.005, 0.01, 0.0125, 0.015. I let you.

  As shown in FIG. 5B, when the flow rate ratio was changed from 0.005 to 0.01, the amount of Si—H bonds remained almost unchanged while the amount of N—H bonds tended to decrease. Indicated. The total amount of hydrogen in the film decreased when the flow rate ratio was 0.01 compared to when the flow rate ratio was 0.005.

  Further, when the ratio of disilane is increased so that the flow rate ratio becomes 0.0125 and 0.015 and the ratio of ammonia is decreased, the amount of Si—H bonds remains low, but the N—H bonds are not changed. The amount of continued to show a downward trend. The total amount of hydrogen in the film was decreased when the flow ratio was 0.025 compared to 0.01 and when the flow ratio was 0.125 compared with 0.125.

As described above, when the proportion of disilane in the processing gas is increased and the proportion of ammonia is decreased, the amount of N—H bonds can be reduced, although the amount of Si—H bonds is hardly changed. It was confirmed that the amount can be reduced to the order of 1 × 10 ²² (atoms / cc) or less. This is thought to be because it can be brought into the supply rate-limiting region.

  FIG. 6 is a diagram showing the dependence of the amount of hydrogen on the microwave power, FIG. 6A shows the processing conditions, and FIG. 6B shows the relationship between the amount of hydrogen and the microwave power.

As shown in FIG. 6A, the microwave power is a parameter (indicated by “−” in the figure), the processing temperature (temperature of the susceptor 3) is 500 ° C., the flow rate of disilane (Si ₂ H ₆ ) and ammonia (NH ₃ ). The flow rate ratio was 5.5 sccm / 1000 sccm = 0.0055, and the treatment pressure was 1000 mTorr. Under such processing conditions, the microwave power was changed to 0.511 W / cm ² (1 kW), 1.023 W / cm ² (2 kW), and 1.534 W / cm ² (3 kW).

As shown in FIG. 6B, when the microwave power is increased to 0.511 W / cm ² (1 kW), 1.023 W / cm ² (2 kW), and 1.534 W / cm ² (3 kW), Si—H bonding is achieved. It has been found that the amount of N—H bonds is reduced, while the amount of N remains almost unchanged. The total amount of hydrogen in the film decreases as the microwave power is increased to 0.511 W / cm ² (1 kW), 1.023 W / cm ² (2 kW), 1.534 W / cm ² (3 kW),. To do.

As described above, when the microwave power is practically increased in the range of 0.5 W / cm ^{2 to} 2.045 W / cm ^{2 (} (4 kw)), Si—H bonding Although the amount remains almost unchanged, the amount of N—H bonds can be reduced, and the total amount of hydrogen in the film can be reduced to an order of 1.4 × 10 ²² (atoms / cc) or less. This is thought to be because the plasma density increases and the reaction proceeds more by increasing the power.

  FIG. 7 is a graph showing the processing pressure dependence of the hydrogen amount, FIG. 7A shows the processing conditions, and FIG. 7B shows the relationship between the hydrogen amount and the processing pressure.

As shown in FIG. 7A, the processing pressure is a parameter (indicated by “−” in the figure), the processing temperature (temperature of the susceptor 3) is 600 ° C., the flow rate of disilane (Si ₂ H ₆ ), and ammonia (NH ₃ ). The flow rate ratio with respect to the flow rate was 5 sccm / 500 sccm = 0.01, the microwave power was 1.023 W / cm ² (2 kW), and the processing pressure was changed to 250 mTorr, 1000 mTorr, 2000 mTorr, and 3000 mTorr.

As shown in FIG. 7B, when the processing pressure in the chamber 1 is set to 1000 mTorr (133.3 Pa) or less as in the normal low pressure plasma CVD method, the N—H bond is dominant over the Si—H bond. It turned out to be. This is supply-limited. Specifically, when the plasma CVD apparatus 100 shown in FIG. 1 is used, when the processing pressure is 1000 mTorr or less, the amount of N—H bonds is on the order of 9 × 10 ²¹ atoms / cc or more. Thus, the amount of Si—H bonds remains on the order of 1 × 10 ²¹ atoms / cc or less. The total amount of hydrogen in the film is on the order of 9 × 10 ²¹ atoms / cc or more.

  On the other hand, when the processing pressure is increased to 1000 mTorr or more, the Si—H bond increases rapidly, but conversely, the N—H bond tends to decrease rapidly. This is reaction limited. Moreover, the decrease in N—H bonds is greater than the increase in Si—H bonds. For this reason, it was found that the total amount of hydrogen in the film, which was the sum of both, began to decrease.

Furthermore, as the processing pressure is increased, the amount of N—H bonds and the amount of Si—H bonds can be balanced even in the case of a plasma CVD silicon nitride film formed using ammonia gas. In addition, the amount of N—H bonds and the amount of Si—H bonds are balanced when the processing pressure is approximately 1800 mTorr (239.9 Pa). The total amount of hydrogen in the film at this time further decreases to the order of 8 × 10 ²¹ atoms / cc (in this example, the order of approximately 8.4 × 10 ²¹ atoms / cc).

  Further, when the processing pressure is increased to 1800 mTorr or more, plasma CVD nitridation in which the amount of N—H bonds is smaller than the amount of Si—H bonds even in a plasma CVD silicon nitride film formed using ammonia gas. A silicon film could be obtained.

For example, in this example, when the processing pressure is 2000 mTorr (266.6 Pa), the amount of N—H bonds is on the order of 3 × 10 ²¹ atoms / cc, and the amount of Si—H bonds is 5 × 10 ²¹ atoms / cc. A plasma CVD silicon nitride film of the order of 10 nm was obtained. The total amount of hydrogen in the film at this time is further reduced to the order of 8 × 10 ²¹ atoms / cc.

When the processing pressure was increased to 2000 mTorr or more, it was found that the decrease in N—H bonds continued, but the increase in Si—H bonds slowed down. That is, the increased Si—H bond begins to be saturated. The fact that the Si—H bond is saturated while the N—H bond decreasing trend continues means that the amount of hydrogen in the total film can be further reduced. In this example, when the processing pressure is 3000 mTorr (400 Pa), the amount of N—H bonds decreases to the order of 1 × 10 ²¹ atoms / cc, but the amount of Si—H bonds is 5 × 10 ²¹ atoms / cc. Almost no change in order. At this time, the total amount of hydrogen in the film continues to decrease to the order of 6 × 10 ²¹ atoms / cc.

Further, the total amount of hydrogen in the film is changed, for example, by changing the flow rate ratio between the flow rate of disilane (Si ₂ H ₆ ) and the flow rate of ammonia (NH ₃ ) so that the amount of Si—H bonds is reduced (flow rate ratio increase). And / or increase the microwave power, it can be reduced to 6 × 10 ²¹ atoms / cc or less. A plasma CVD silicon nitride film is better with fewer Si—H bonds in the film.

According to such a plasma CVD silicon nitride film forming method, even if a gas containing nitrogen and hydrogen, for example, ammonia gas is used as a nitrogen-containing gas that is a processing gas for forming a silicon nitride film. By setting the processing pressure to 1000 mTorr (133.3 Pa) or higher, the total amount of hydrogen in the film, which is the sum of the amount of Si—H bonds in the silicon nitride film and the amount of N—H bonds in the film, is 8.4. × it is possible to obtain a low hydrogen content of the plasma CVD silicon nitride film can be below ¹⁰ 21 atoms / cc.

  Incidentally, by setting the processing pressure to 1000 mTorr or more, the upper limit of the processing pressure is, for example, 100 Torr (for example) as long as the Si—H bond tends to be saturated while the N—H bond decreasing tendency is continued. 13333 Pa) or less. The pressure is preferably 10 Torr (1333 Pa) or less.

Furthermore, the flow ratio of the silicon-containing gas and a nitrogen and hydrogen-containing gas and 0.01 to 0.015 or less, and / or microwave power when the W / cm ² or more 2.045W / cm ² or less, film A plasma CVD silicon nitride film with fewer Si—H bonds therein can be obtained.

  In addition, since the plasma CVD silicon nitride film formed according to the film forming method of this example is formed using a gas containing nitrogen and hydrogen, for example, the plasma CVD silicon nitride film is formed using only nitrogen gas. The reaction is more likely to occur and the controllability is better than in the case of film formation. In addition, although the plasma CVD silicon nitride film is formed using a gas containing nitrogen and hydrogen, the amount of N—H bonds can be reduced. Furthermore, the amount of N—H bonds can be made equal to or less than the amount of Si—H bonds. Therefore, the situation that a large amount of N—H bonds are likely to be contained in the plasma CVD silicon nitride film formed using a gas containing nitrogen and hydrogen can be solved. It was. If the range of the total amount of hydrogen in the plasma CVD silicon nitride film is described, the range is equal to or less than the sum of the amount of N—H bonds and the amount of Si—H bonds and equal to or greater than the amount of Si—H bonds. . If the total amount of hydrogen in the film is in the above range, a plasma CVD silicon nitride film having a small total amount of hydrogen in the film can be obtained.

  In a plasma CVD silicon nitride film having a small total amount of hydrogen in the film, the probability that vacancies are generated due to the escape of hydrogen from the film is reduced. Therefore, the probability of occurrence of electron traps decreases, the film quality hardly deteriorates, and a highly reliable plasma CVD silicon nitride film that can maintain a good film quality for a long period of time is obtained. Such a plasma CVD silicon nitride film is advantageous for application to a semiconductor integrated circuit device.

  Thus, according to the plasma CVD silicon nitride film formed at a low temperature using the method of the present invention, N—H bonds can be reduced, and the amount of N—H bonds and the amount of Si—H bonds can be reduced. A method for forming a plasma CVD silicon nitride film capable of reducing the total amount of hydrogen in the total film can be provided.

(Second Embodiment)
Furthermore, the relationship between the amount of N—H bonds and the film quality of the plasma CVD silicon nitride film was examined. As an index indicating the film quality, an etching rate when a hydrofluoric acid solution was used as an etchant was used. For the calculation of the etching rate, the difference between the film thickness before etching and the film thickness after completion of etching was obtained by ellipsometry, and the etching amount per unit time was calculated.

FIG. 8 shows a plasma CVD silicon nitride film (SiN _x ), a low pressure CVD silicon nitride film (Si ₃ N ₄ ), a thermal silicon oxide film (SiO ₂ ), a plasma CVD silicon oxide film (SiO _x ), a CVD silicon oxide film ( TEOS-SiO ₂₎ is a diagram showing an etching rate for each of hydrofluoric acid solution.

As shown in FIG. 8, a plasma CVD silicon nitride film, in this example, a microwave plasma CVD silicon nitride film (1), (2) is a film formed according to the film forming method according to this embodiment. Two types of films were prepared: a film (1) with an N—H bond amount of the order of 10 ²² atoms / cc and a film (2) with an order of 10 ²¹ atoms / cc. Further, the low-pressure CVD silicon nitride film (3), the thermal silicon oxide film (4), the plasma CVD silicon oxide film (5), and the CVD silicon oxide film (6) are films formed according to existing film forming methods, respectively. is there. These films (3) to (6) are shown as comparative examples for the films (1) and (2).

  With respect to the films (3) to (6), the low pressure CVD silicon nitride film (3) has an etching rate of 2.86 A / min (0.8 .0) with respect to a hydrofluoric acid solution (0.5%) diluted with pure water. 286 nm / min), and the etching resistance to the hydrofluoric acid solution is the best. In the following, the etching resistance is a thermal silicon oxide film (4), a plasma CVD silicon oxide film (5), and a CVD silicon oxide film (6). Among the comparative examples, the CVD silicon oxide film (6) is the most hydrofluoric acid solution. It can be seen that the film is well etched.

The film (1) is a plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²² atoms / cc. The etching rate of the film (1) with respect to the hydrofluoric acid solution (0.5%) is 37.87 A / min (3.787 nm / min), and the etching rate of the plasma CVD silicon oxide film (5) is 40.35 A / min. As a result, the etching resistance to the hydrofluoric acid solution was better than (4.035 nm / min). However, the etching resistance of the film (1) to the hydrofluoric acid solution does not reach that of the low-pressure CVD silicon nitride film (3).

Further, for the film (2), that is, the plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc, in this example 3.43 × 10 ²¹ atoms / cc, a hydrofluoric acid solution (0. 5%) is an etching rate of 0.77 A / min (0.077 nm / min), which is an order of magnitude higher than the etching rate 2.86 A / min (0.286 nm / min) of the low-pressure CVD silicon nitride film (3), The result that the etching resistance with respect to a hydrofluoric acid solution was good was able to be obtained.

Thus, the plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc or less has better etching resistance to the hydrofluoric acid solution than the low-pressure CVD silicon nitride film (3). A film having such properties is advantageous for application to an internal structure of a semiconductor integrated circuit device as described below, for example.

(Application example 1)
Application Example 1 is an example in which a plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc or less is used as an etching stopper and a hard mask.

  9A to 9C are cross-sectional views showing a method of manufacturing a semiconductor integrated circuit device according to Application Example 1 in the order of main manufacturing steps.

First, as shown in FIG. 9A, an insulating film 201 such as an interlayer insulating film is formed on a semiconductor wafer (not shown). Next, an etching stopper 202 is formed over the insulating film 201. As the etching stopper 202, a plasma silicon nitride film is used. The plasma silicon nitride film is formed under the processing temperature of 300 ° C. or higher and 600 ° C. or lower, preferably 500 ° C. or lower as described above. , for example, disilane and the nitrogen and hydrogen-containing gas, for example, the flow rate ratio of ammonia 0.005 0.015, microwave power 0.5 W / cm ² or more 2.045W / cm ² or less, the process pressure 133. 3 Pa or more and 13333 Pa or less. Preferably, it is set to 1333 Pa or less. With such film formation conditions, the etching stopper 202 using a plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc or less can be formed. Next, an interlayer insulating film 203 is formed over the etching stopper 202. As the interlayer insulating film 203, for example, a known low dielectric constant insulating film having a dielectric constant lower than that of a silicon oxide film may be used. Next, a hard mask 204 is formed over the interlayer insulating film 203. As with the etching stopper 202, a plasma silicon nitride film is used for the hard mask 204. The film forming conditions of the plasma silicon nitride film to be the hard mask 204 are the same as the etching stopper 202, and the processing temperature is 300 ° C. or higher and 600 ° C. or lower, preferably 500 ° C. or lower, and a silicon-containing gas such as disilane. nitrogen and hydrogen-containing gas, for example, the flow rate ratio of ammonia 0.005 0.015, microwave power 0.5 W / cm ² or more 2.045W / cm ² or less, the process pressure 133.3Pa than 13333Pa less And Preferably, it is set to 1333 Pa or less. With such film formation conditions, the hard mask 202 using a plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc or less can be formed. Next, on the hard mask 204, a mask pattern 205 made of a photoresist, for example, a mask pattern 205 having a hole corresponding to a groove for embedding a wiring material and a hole for connecting wirings is formed.

  Next, as shown in FIG. 9B, the hard mask 204 is etched using the mask pattern 205 as a mask.

  Next, as shown in FIG. 9C, after removing the mask pattern 205, the interlayer insulating film 203 is etched using the hard mask 204 as an etching mask, and a groove for embedding a wiring material in the interlayer insulating film 203, or A hole 206 for connecting the wirings is formed. The etching of the interlayer insulating film 203 is continued until the etching stopper 202 is exposed. When the etching stopper 202 is exposed, the etching rate is reduced, and the etching is actually stopped.

A plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc or less at a low temperature has good etching resistance. Therefore, a semiconductor integrated circuit such as an etching stopper 202 for stopping etching or an interlayer insulating film 203 It is suitable for a hard mask 204 or the like used as an etching mask when processing the internal structure.

Further, the etching resistance of the plasma CVD silicon nitride film is better than that of the low pressure plasma CVD silicon nitride film (Si ₃ N ₄ ) as shown in FIG. Compared with the case of using the mask 204, the film thickness can be further reduced. If the thickness of the etching stopper 202 and the hard mask 204 can be reduced, for example, the film formation time and the etching time can be shortened, which helps to improve the throughput. In addition, since the internal structure in the vertical direction of the semiconductor integrated circuit device can be thinned, it is advantageous for the multilayer structure of the semiconductor integrated circuit device which is considered to be further developed in the future.

  In Application Example 1, the plasma CVD silicon nitride film according to the embodiment is used for both the etching stopper 202 and the hard mask 204. However, it is not necessarily used for both, and may be used for either one. .

(Application example 2)
Application Example 2 is an example in which a plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc or less is used for a cap layer and a sidewall spacer in a self-aligned contact structure.

  10A to 10D are cross-sectional views illustrating a method of manufacturing a semiconductor integrated circuit device according to Application Example 2 in order of main manufacturing steps.

As shown in FIG. 10A, a semiconductor wafer W (silicon wafer in this example) is thermally oxidized to form a thermally oxidized silicon film that becomes the gate insulating film 301, and a gate is formed on the thermally oxidized silicon film that becomes the gate insulating film 301. For example, a conductive polysilicon film to be the electrode 302 is formed. Next, a cap layer 303 is formed on the polysilicon film to be the gate electrode 302. For the cap layer 303, the plasma CVD silicon nitride film according to the embodiment is used, and the film formation conditions are a processing temperature of 300 ° C. or higher and 600 ° C. or lower, preferably 500 ° C. or lower, and a silicon-containing gas such as disilane. nitrogen and hydrogen-containing gas, for example, the flow rate ratio of ammonia 0.005 0.015, microwave power 0.5 W / cm ² or more 2.045W / cm ² or less, the process pressure 133.3Pa than 13333Pa less And Preferably, it is set to 1333 Pa or less. With such a film formation condition, the cap layer 303 using a plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc or less can be formed. Next, a gate pattern (not shown) made of a photoresist is formed on the cap layer 303, and the cap layer 303, the polysilicon film, and the thermal oxide film are sequentially etched using the gate pattern as a mask, and the cap layer 303 is formed above. Is formed. Next, using the gate electrode 302 as a mask, impurities for forming source / drain regions 304 having a conductivity type different from that of the wafer W are introduced into the wafer W.

Next, as illustrated in FIG. 10B, an insulating film to be the sidewall spacer 305 is formed on the source / drain region 304 and the gate electrode 302. The plasma CVD silicon nitride film according to the embodiment is used for the insulating film to be the sidewall spacer 305, and the film forming conditions are a processing temperature of 300 ° C. or higher and 600 ° C. or lower, preferably 500 ° C. or lower, and a silicon-containing gas. , for example, disilane and the nitrogen and hydrogen-containing gas, for example, the flow rate ratio of ammonia 0.005 0.015, microwave power 0.5 W / cm ² or more 2.045W / cm ² or less, the process pressure 133. 3 Pa or more and 13333 Pa or less. Preferably, it is set to 1333 Pa or less. Next, the insulating film to be the sidewall spacer 305 is anisotropically etched to form the sidewall spacer 305 on the sidewalls of the cap layer 303 and the gate electrode 302. In this manner, the sidewall spacer 305 using a plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc or less can be formed.

  Next, as illustrated in FIG. 10C, an interlayer insulating film 306 is formed on the cap layer 303, the source / drain regions 304, and the sidewall spacers 305. For the interlayer insulating film 306, for example, a known low dielectric constant insulating film having a dielectric constant lower than that of a silicon oxide film may be used. Next, a contact hole pattern (not shown) reaching the source / drain region 304 made of a photoresist is formed on the interlayer insulating film 306, and the interlayer insulating film 306 is etched using the contact hole pattern as a mask to form a contact hole. 307 is formed. The contact hole 307 in this example extends over the cap layer 303 and the side wall spacer 305, and the contact hole 307 is in contact with the space between the cap layer 303 and the side wall spacer 305 that covers the gate electrode 302, that is, the gate electrode 302. This is a so-called self-aligned contact structure formed in a self-aligned manner.

  Next, as illustrated in FIG. 10D, the contact hole 307 is filled with a conductive material 308 to form the structure according to the application example 2.

As described above, the plasma CVD silicon nitride film in which the amount of N—H bonds formed at a low temperature by the method of the present invention is on the order of 10 ²¹ atoms / cc or less has good etching resistance. Therefore, the contact hole 307 is formed between the gate electrodes 302. It is also suitable for the cap layer 303 covering the gate electrode 302 and the sidewall spacer 305 when forming in a self-aligning manner with respect to the space.

(Third embodiment)
Furthermore, the relationship between the amount of N—H bonds and the stress of the plasma CVD silicon nitride film was examined. For measurement of stress, FLX-2320 manufactured by KLA-Tencor was used.

  FIG. 11 is a diagram showing the relationship between the stress of the plasma CVD silicon nitride film and the amount of N—H bonds.

As shown in FIG. 11, the stress of the plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²² atoms / cc, in this example, the plasma CVD silicon nitride film of 1.32 × 10 ²² atoms / cc is It has a tensile stress of 1496 MPa.

On the contrary, the stress of the plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc, in this example, the plasma CVD silicon nitride film of 3.43 × 10 ²¹ atoms / cc is a compression of −1099 MPa. Have stress.

  Thus, it was confirmed that the stress of the film tends to shift from the tensile stress to the compressive stress as the amount of N—H bonds decreases from the plasma CVD silicon nitride film.

  Further, a plasma CVD silicon nitride film is formed using nitrogen and hydrogen-containing gas (for example, ammonia gas) as a nitriding process gas, and a nitrogen gas not containing hydrogen is used as a nitriding process gas. The step coverage of the formed film was examined when the film was formed.

  12 is a cross-sectional view showing the step coverage of a plasma CVD silicon nitride film formed using ammonia gas, and FIG. 13 is a cross-sectional view showing the step coverage of a plasma CVD silicon nitride film formed using nitrogen gas. is there. FIG. 13 is a reference example.

As shown in FIG. 12, the plasma CVD silicon nitride film 400 _NH3 formed using nitrogen and hydrogen containing gas, in this example, ammonia gas, has a film thickness (Side) on the step side surface and a film thickness (Step) The ratio “Side / Top” with respect to (Top) is about 91%, and the ratio “Btm / Top” between the film thickness (Btm) on the step bottom surface and the film thickness (Top) on the step top surface is about 97%. A step coverage of approximately 90% or more was obtained. The film forming conditions in this example are a processing temperature of 400 ° C., a flow rate ratio of disilane and ammonia of 5 sccm / 500 sccm, a microwave power of 1.023 W / cm ² (2 kW), and a processing pressure of 1000 mTorr.

On the other hand, as shown in FIG. 13, the plasma CVD silicon nitride film 400 _N2 formed using nitrogen gas has a ratio “Side / Top” of about 30% and a ratio “Btm / Top” of about 38%. The step coverage was generally 30 to 40%. The film forming conditions in this example are a processing temperature of 500 ° C., a flow ratio of disilane and nitrogen of 1 sccm / 1200 sccm, a microwave power of 1.023 W / cm ² (2 kW), and a processing pressure of 20 mTorr.

  As described above, the plasma CVD silicon nitride film formed at a low temperature according to the embodiment of the present invention uses nitrogen and hydrogen-containing gas as the nitriding processing gas, and uses nitrogen gas as the nitriding processing gas. It was confirmed that the step coverage can be improved as compared with. From the measurement result of the step coverage, as described in the first embodiment, the plasma CVD silicon nitride film is formed using nitrogen and hydrogen-containing gas, for example, only nitrogen gas is used. It was confirmed again that the reaction easily occurs and the controllability is improved as compared with the case of using the plasma CVD silicon nitride film.

As described above, when the plasma CVD silicon nitride film is formed using nitrogen and hydrogen-containing gas, the step coverage is good, and the amount of N—H bonds is increased from the order of 10 ²² atoms / cc to 10 ²¹ atoms. By reducing it to less than / cc order, either tensile stress or compressive stress can be selected and applied to the film stress. Further, a plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc or less can select either tensile stress or compressive stress as the film stress. A film having such properties is advantageous for application to an internal structure of a semiconductor integrated circuit device as described below, for example.

(Application example 3)
Application Example 3 is an example in which the plasma CVD silicon nitride film according to the embodiment of the present invention is used as a stress liner that applies stress to a channel of a transistor and improves charge mobility.

  14A and 14B are cross-sectional views illustrating a method of manufacturing a semiconductor integrated circuit device according to Application Example 3 in the order of main manufacturing steps.

  As shown in FIG. 14A, the surface of a semiconductor wafer W (in this example, a silicon wafer) is thermally oxidized to form a thermal silicon oxide film that becomes the gate insulating film 401, and on the thermal silicon oxide film that becomes the gate insulating film 401. For example, a conductive polysilicon film to be the gate electrode 402 is formed. Next, a gate pattern (not shown) made of a photoresist is formed on the polysilicon film to be the gate electrode 402, and the gate electrode 402 is formed by sequentially etching the polysilicon film and the thermal oxide film using the gate pattern as a mask. To do. Next, using the gate electrode 402 as a mask, impurities for forming source / drain regions 403 having a conductivity type different from that of the wafer W are introduced into the wafer W.

Next, as shown in FIG. 14B, a stress liner 404 is formed on the source / drain region 403 and the gate electrode 402. The plasma CVD silicon nitride film according to the embodiment is used for the insulating film serving as the stress liner 404, and the film forming conditions are such that the processing temperature is 300 ° C. or higher and 600 ° C. or lower, preferably 500 ° C. or lower, and the silicon-containing gas. , for example, disilane and the nitrogen and hydrogen-containing gas, for example, the flow rate ratio of ammonia 0.005 0.015, microwave power 0.5 W / cm ² or more 2.045W / cm ² or less, the process pressure 133. 3 Pa or more and 13333 Pa or less. Preferably, it is set to 1333 Pa or less. With such film formation conditions, the stress liner 404 using a plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc or less can be formed.

As shown in FIG. 11, the plasma CVD silicon nitride film having an N—H bond amount of the order of 10 ²¹ atoms / cc or less can selectively have either a tensile stress or a compressive stress. . For example, when the amount of N—H bonds is infinitely close to 1 × 10 ²² atoms / cc, a tensile stress of approximately 1250 MPa can be applied, and the amount of N—H bonds is approximately 6.5 × 10 ^21. On the contrary, if it is atoms / cc or less, compressive stress can be applied. For example, when the amount of N—H bonds is 3.43 × 10 ²¹ atoms / cc, a compressive stress of approximately −1099 MPa can be applied.

As described above, by using the plasma CVD silicon nitride film in which the amount of N—H bonds is controlled to the order of 10 ²¹ atoms / cc or less for the stress liner 404, tensile stress is applied to the channel, or compressive stress is applied to the channel. You can choose either to give.

For example, when the amount of N—H bonds in the plasma CVD silicon nitride film is more than 6.5 × 10 ²¹ atoms / cc and less than 1 × 10 ²² atoms / cc, the stress liner 404 has tensile stress. Can apply tensile stress to the channel. When tensile stress is applied to the channel, the mobility of electrons is improved, so that it can be effectively applied to an N-channel MOSFET or MISFET.

For example, when the amount of N—H bonds in the plasma CVD silicon nitride film is less than 6.5 × 10 ²¹ atoms / cc, the stress liner 404 has a compressive stress on the contrary, and the channel Compressive stress can be applied. When compressive stress is applied to the channel, the hole mobility is improved, so that it can be effectively applied to a P-channel MOSFET or MISFET.

When compressive stress is applied to the channel, the amount of N—H bonds in the plasma CVD silicon nitride film may be less than 6.5 × 10 ²¹ atoms / cc. It may be on the order of 10 ²⁰ atoms / cc, and there is no lower limit. However, if the lower limit is set intentionally, it will be 1 × 10 ²⁰ atoms / cc or more.

  In addition, the plasma CVD silicon nitride film according to the embodiment of the present invention has good step coverage because nitrogen and a hydrogen-containing gas such as ammonia are used as the nitriding process gas. For example, as described with reference to FIG. 12, a step coverage of approximately 90% or more can be obtained. Such a film is suitable for application to a stress liner. For example, if the step coverage of the stress liner is poor, the portion of the stress liner on the gate electrode becomes particularly thick, and the height of the gate electrode increases and the unevenness on the surface of the semiconductor wafer tends to increase. This leads to a situation in which, for example, it becomes difficult to fill the space between the gate electrodes with an interlayer insulating film. However, if the stress liner is formed of a film having a good step coverage, for example, a film having a step coverage of 90% or more, the situation where the portion of the stress liner on the gate electrode becomes particularly thick is solved. The Therefore, it is possible to prevent the unevenness on the surface of the semiconductor wafer from becoming large, and for example, it is possible to obtain an advantage that the gap between the gate electrodes can be easily filled with the interlayer insulating film.

  While the present invention has been described with reference to some embodiments, the present invention is not limited to the above embodiments, and various modifications can be made.

  For example, although disilane was used as the silicon-containing gas, silane, TSA, or the like can be used in addition to disilane. In addition, although ammonia was used as the nitrogen and hydrogen containing gas, it can be used as long as it contains nitrogen and hydrogen and can form a silicon nitride film by supplying it with the silicon containing gas. is there.

  Moreover, although the microwave plasma CVD apparatus was illustrated as a plasma CVD apparatus in the said embodiment, if it is a plasma CVD apparatus, it will not be restricted to a microwave plasma CVD apparatus.

  Moreover, in the said embodiment, although the shower head type microwave plasma CVD apparatus was illustrated as a microwave plasma CVD apparatus, microwave plasma CVD apparatuses other than a shower head type can also be utilized.

1 is a schematic cross-sectional view showing an example of a plasma CVD apparatus used in a plasma CVD silicon nitride film forming method according to a first embodiment of the present invention. Plan view showing an example of a planar antenna member Plan view showing an example of a shower head Diagram showing dependence of hydrogen amount on processing temperature Diagram showing the dependence of hydrogen content on the flow rate of silicon-containing gas Diagram showing the dependence of hydrogen content on microwave power Diagram showing dependence of hydrogen amount on processing pressure Diagram showing thin film etching rate Sectional drawing which shows the manufacturing method of the semiconductor integrated circuit device which concerns on the application example 1 in order of main manufacturing processes Sectional drawing which shows the manufacturing method of the semiconductor integrated circuit device concerning the application example 2 in order of main manufacturing processes The figure which shows the relationship between the stress of a plasma CVD silicon nitride film, and the quantity of NH bond. Sectional drawing which shows the step coverage of the plasma CVD silicon nitride film formed using ammonia gas Sectional view showing step coverage of plasma CVD silicon nitride film formed using nitrogen gas Sectional drawing which shows the manufacturing method of the semiconductor integrated circuit device concerning the application example 3 in order of main manufacturing processes

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Processing chamber (processing container), 2 ... Exhaust chamber, 3 ... Susceptor (substrate support stand), 4 ... Support part, 5 ... Guide ring, 6 ... Heater, 7 ... Baffle plate, 8 ... Support | pillar, 9 ... Gate valve DESCRIPTION OF SYMBOLS 10 ... Microwave introduction part, 11 ... Microwave transmission board, 12 ... Planar antenna member, 13 ... Slow wave material, 14 ... Ring support part, 15 ... Seal member, 16 ... Slot hole, 17 ... Shield cover, 18 DESCRIPTION OF SYMBOLS ... Waveguide, 19 ... Matching circuit, 20 ... Microwave generator, 21 ... Mode converter, 22 ... Shower head, 23 ... Gas flow path, 24 ... Gas discharge hole, 25 ... Space part, 26 ... Gas supply pipe 27 ... Gas supply unit, 28 ... Plasma introduction gas introduction unit, 29 ... Gas supply pipe, 30 ... Gas supply unit, 40 ... Control unit, 41 ... Process controller, 42 ... User interface, 43 ... , 100 ... plasma CVD apparatus, 201 ... insulating film, 202 ... etching stopper, 203 ... interlayer insulating film, 204 ... hard mask, 205 ... photoresist, 206 ... groove or hole, 301 ... gate insulating film, 302 ... gate electrode, DESCRIPTION OF SYMBOLS 303 ... Cap layer, 304 ... Source / drain region, 305 ... Side wall spacer, 306 ... Interlayer insulating film, 307 ... Contact hole, 308 ... Conductor, 401 ... Gate insulating film, 402 ... Gate electrode, 403 ... Source / drain region 404 ... Stress liner.

Claims (8)

A method for forming a plasma CVD silicon nitride film using microwave-excited plasma,
Introducing a silicon-containing gas and a nitrogen- and hydrogen-containing gas into the processing vessel;
Radiating microwaves into the processing vessel, and plasmatizing the silicon-containing gas and the nitrogen- and hydrogen-containing gas introduced into the processing vessel;
Supplying the plasma-containing silicon-containing gas and the nitrogen- and hydrogen-containing gas onto the surface of the substrate to be processed, and forming a silicon nitride film on the surface of the substrate to be processed.
The silicon nitride film is formed under the following conditions: the processing temperature is 300 ° C. or more and 600 ° C. or less, the flow rate ratio between the silicon-containing gas and nitrogen and hydrogen-containing gas is 0.005 or more and 0.015 or less, and the microwave power is 0.5 W. / Cm ² or more and 2.045 W / cm ² or less, and the processing pressure is 133.3 Pa or more and 13333 Pa or less.   2. The plasma CVD silicon nitride film forming method according to claim 1, wherein a processing pressure in the processing container in the step of depositing the silicon nitride film is set to 133.3 Pa or more and 400 Pa or less.   3. The plasma CVD silicon nitride film forming method according to claim 1, wherein the nitrogen and hydrogen-containing gas is ammonia.   4. The method of forming a plasma CVD silicon nitride film according to claim 3, wherein the silicon-containing gas is disilane.   The method of forming a plasma CVD silicon nitride film according to claim 1, wherein the microwave is radiated into the processing container through a planar antenna. Forming an etching stopper containing a material different from the insulating film on the insulating film;
Forming an interlayer insulating film containing a material different from the etching stopper above the etching stopper;
Forming a hard mask containing a material different from the interlayer insulating film on the interlayer insulating film;
Forming a groove or a hole in the interlayer insulating film using the hard mask as an etching mask, and
At least one of the etching stopper and the hard mask is a silicon nitride film,
The silicon nitride film is formed under the following conditions: the processing temperature is 300 ° C. or more and 600 ° C. or less, the flow rate ratio between the silicon-containing gas and nitrogen and hydrogen-containing gas is 0.005 or more and 0.015 or less, and the microwave power is 0.5 W. / Cm ² or more and 2.045 W / cm ² or less, and a processing pressure is set to 133.3 Pa or more and 13333 Pa or less. On the semiconductor substrate, forming a gate electrode insulated from the semiconductor substrate and provided with a cap layer on the top;
Introducing a source / drain region impurity into the semiconductor substrate using the gate electrode as a mask;
Forming a sidewall spacer on the sidewall of the gate electrode,
At least one of the cap layer and the sidewall spacer is a silicon nitride film,
The silicon nitride film is formed under the following conditions: the processing temperature is 300 ° C. or more and 600 ° C. or less, the flow rate ratio between the silicon-containing gas and nitrogen and hydrogen-containing gas is 0.005 or more and 0.015 or less, and the microwave power is 0.5 W. / Cm ² or more and 2.045 W / cm ² or less, and a processing pressure is set to 133.3 Pa or more and 13333 Pa or less. Forming a gate electrode insulated from the semiconductor substrate on the semiconductor substrate;
Introducing a source / drain region impurity into the semiconductor substrate using the gate electrode as a mask;
Forming a stress liner on the semiconductor substrate, covering the gate electrode and applying stress to a portion of the semiconductor substrate under the gate electrode;
The stress liner is a silicon nitride film;
The silicon nitride film is formed under the following conditions: the processing temperature is 300 ° C. or more and 600 ° C. or less, the flow rate ratio between the silicon-containing gas and nitrogen and hydrogen-containing gas is 0.005 or more and 0.015 or less, and the microwave power is 0.5 W. / Cm ² or more and 2.045 W / cm ² or less, and a processing pressure is set to 133.3 Pa or more and 13333 Pa or less.

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