JP2009246131A - Method of forming high-stress thin film, and method of manufacturing semiconductor integrated circuit device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a high-stress thin film that imparts stress larger than stress, imparted under process conditions, to a thin film. <P>SOLUTION: The method of forming the high-stress thin film includes a stage (step 1) in which a film forming material gas containing hydrogen is supplied into a chamber to form a thin film containing hydrogen on a semiconductor substrate, and stages (a step 2, and steps 11 and 12) in which while a hydrogen leaving gas containing a substance leaving hydrogen from the thin film is supplied into the chamber in a pulselike manner, the hydrogen is leaved from the thin film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for forming a high stress thin film and a method for manufacturing a semiconductor integrated circuit device using the film forming method.

Silicon nitride films are used as insulating films and protective films in various semiconductor devices. It is known that such a silicon nitride film can be formed, for example, by plasma CVD using a silicon-containing compound gas such as silane (SiH ₄ ) as a source gas and a nitrogen-containing compound gas such as nitrogen or ammonia. (For example, Patent Document 1).

  In a silicon nitride film formed by a plasma CVD method, it has been an important problem to suppress film stress that adversely affects device characteristics, that is, tensile stress and compressive stress. For example, when the compressive stress of a silicon nitride film is large, it is known that stress migration that causes disconnection of the metal wiring immediately below the film is caused by the stress. To prevent this, it is necessary to keep the compressive stress small. is there. In the case of the plasma CVD method, the direction of the stress (whether it is tensile stress or compression stress) and the magnitude of the silicon nitride film depend on film forming conditions such as pressure, temperature, and film forming gas type. For this reason, the conditions under which strong stress does not occur in the silicon nitride film have been selected, and a silicon nitride film having no stress has been formed by plasma CVD (for example, Non-Patent Document 1).

  However, in recent years, attempts have been made to improve device characteristics by positively utilizing the stress of the silicon nitride film in certain devices (for example, Patent Document 2).

However, stress applied to a thin film such as a silicon nitride film has a limit on the stress value because it depends on process conditions as described in Non-Patent Document 1.
JP 2000-260767 A JP 2007-49166 A Kazuo Maeda “VLSI and CVD” Tsubaki Shoten, issued July 31, 1997

  An object of the present invention is to provide a method for forming a high-stress thin film capable of applying a stress greater than the stress given by process conditions to the thin film, and a method for manufacturing a semiconductor integrated circuit device using the film forming method. And

  In order to solve the above-described problem, a method for forming a high stress thin film according to a first aspect of the present invention includes supplying a film forming source gas containing hydrogen into a chamber and placing the thin film into which hydrogen has been incorporated on a semiconductor substrate. And a step of desorbing hydrogen from the thin film while supplying a pulse of a hydrogen desorption gas containing a substance capable of desorbing hydrogen from the thin film to the chamber.

A method for forming a high stress thin film according to a second aspect of the present invention is a method for forming a high stress thin film using microwave-excited plasma, wherein a silicon-containing gas, nitrogen and hydrogen are contained in a processing vessel. A step of introducing a gas, a step of radiating microwaves into the processing container, and plasmatizing the silicon-containing gas and the nitrogen- and hydrogen-containing gas introduced into the processing container; The silicon-containing gas and the nitrogen- and hydrogen-containing gas are supplied onto the surface of the substrate to be processed, the film formation conditions are set on the surface of the substrate to be processed, the processing temperature is 300 ° C. to 600 ° C., and the silicon-containing gas. and the flow ratio of nitrogen and hydrogen-containing gas 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 1333 A step of forming a silicon nitride film at Pa or lower, and a step of releasing hydrogen from the thin film while supplying a pulse of a hydrogen releasing gas containing a substance for releasing hydrogen from the silicon nitride film to the chamber. To do.

  According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor integrated circuit device, wherein an etching stopper containing a material different from the insulating film is formed on the insulating film according to the first aspect or the second aspect. Forming an interlayer insulating film including a material different from the etching stopper above the etching stopper, and including a material different from the interlayer insulating film on the interlayer insulating film. Forming a hard mask using the film forming method according to the first aspect or the second aspect; forming a groove or a hole in the interlayer insulating film using the hard mask as an etching mask; Are provided.

  According to a fourth 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 the step of introducing impurities for forming source / drain regions into the semiconductor substrate, and the film forming method according to the first aspect or the second aspect on the sidewall of the gate electrode. And forming using the method.

  According to a fifth aspect of the present invention, there is provided a method of manufacturing a semiconductor integrated circuit device, comprising: forming a gate electrode insulated from the 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 applying a stress liner that covers the gate electrode on the semiconductor substrate and applies stress to the portion of the semiconductor substrate under the gate electrode. Forming using the film forming method according to the aspect or the second aspect.

  According to the present invention, it is possible to provide a method for forming a high-stress thin film capable of applying a stress greater than the stress given by process conditions to the thin film, 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 schematically showing an example of a plasma film forming apparatus that can be used for forming a thin film. The plasma film forming apparatus 100a has a high density by introducing a microwave into the chamber 1 with a planar antenna having a plurality of slots, particularly a RLSA (Radial Line Slot Antenna) to generate plasma. And an RLSA microwave plasma film forming apparatus capable of generating microwave-excited plasma having a low electron temperature, having a plasma density of 1 × 10 ^{10 to} 5 × 10 ¹² / cm ³ and 0.7 to 2 eV. Treatment with low electron temperature plasma is possible. Therefore, it can be suitably used for the purpose of forming a thin film by plasma CVD, for example, forming a silicon nitride film in the manufacturing process of various semiconductor devices.

  The plasma film forming apparatus 100a includes a substantially cylindrical processing chamber (processing container) 1 that is airtight and grounded. The chamber 1 may have a rectangular tube shape. In the processing chamber 1, a thin film such as 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 cover ring 5 for covering the outer edge and guiding the wafer W is provided on the outer edge of the susceptor 3. The cover ring 5 is a member made of a material such as quartz, AlN, Al ₂ O ₃ , or SiN. For example, 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. The susceptor 3 is provided with wafer support pins (not shown) for supporting the wafer W and moving it up and down so as to protrude and retract with respect to the surface of the susceptor 3.

  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.

  Below the antenna, gas inlets 22a and 22b are provided in an annular shape up and down, and each gas inlet 22a and 22b has a plurality of gas discharge holes on the side walls of the gas inlets 22a and 22b. It is formed uniformly along the inner periphery of the. A gas supply unit 27 for supplying a film forming source gas and a plasma excitation gas is connected to the gas introduction units 22a and 22b. The gas introduction parts 22a and 22b may be arranged in a nozzle shape or a shower shape.

  In this example, the gas supply unit 27 includes a silicon-containing gas supply source 27a, a nitrogen-containing gas supply source 27b, an inert gas supply source 27c, and a hydrogen desorption gas supply source 27d. The nitrogen-containing gas supply source 27b is connected to the upper gas introduction part 22a, and the silicon-containing gas supply source 27a, the inert gas supply source 27c, and the hydrogen desorption gas supply source 27d are connected to the lower gas introduction part 22b. ing.

As the nitrogen-containing gas that is a film forming material gas, for example, hydrazine derivatives such as nitrogen (N ₂ ), ammonia (NH ₃ ), and monomethyl hydrazine (MMH) can be used.

Moreover, as a silicon-containing gas that is another film forming source gas, for example, silane (SiH ₄ ), disilane (Si ₂ H ₆ ), and the like can be used, and disilane (Si ₂ H ₆ ) is particularly preferable.

For example, N ₂ gas or rare gas can be used as the inert gas. As the rare gas that is a plasma excitation gas, for example, Ar gas, Kr gas, Xe gas, He gas, or the like can be used. In terms of cost, Ar gas is preferable.

The hydrogen desorption gas is a gas for desorbing hydrogen from the thin film formed, and includes a substance for desorbing hydrogen from the thin film. As the substance for releasing hydrogen from the thin film, for example, a halogen-containing gas can be used. Examples of the halogen include fluorine or chlorine, and examples of a preferable halogen-containing gas include a fluoride of nitrogen or a fluoride of chlorine. Examples of nitrogen fluoride, chlorine fluoride, or gas containing these fluorides include NF ₃ gas, NF ₃ -containing gas, ClF ₃ gas, or ClF ₃ -containing gas. be able to. Furthermore, it is preferable to use a rare gas, for example, an Ar gas, as a dilution gas that stably generates plasma. Further, when a nitrogen fluoride, a chlorine fluoride, or a gas containing these fluorides is used as the hydrogen desorption gas, it can also be used as a cleaning gas for cleaning the inside of the chamber 1 and the like. . In this case, the hydrogen desorption gas may be supplied from a cleaning gas supply source connected to the plasma film forming apparatus 100a.

  The nitrogen-containing gas reaches the gas introduction part 22a via the gas line 21a, and is introduced into the chamber 1 from the gas introduction part 22a.

  The silicon-containing gas, the inert gas, and the hydrogen desorption gas reach the gas introduction part 22b through the gas lines 21a, respectively, and are introduced into the chamber 1 from the gas introduction part 22b.

  Each gas line 21a connected to each gas supply source is provided with a mass flow controller 21b and an opening / closing valve 21c before and after the mass flow controller 21b, and is configured to be able to switch the supplied gas and control the flow rate. Yes. Note that a rare gas for plasma excitation such as Ar is an arbitrary gas and is not necessarily supplied at the same time as the film forming source gas, but is preferably used in consideration of stable generation of plasma.

  In this example, the hydrogen desorption gas is supplied into the chamber 1 from the lower gas introduction part 22b, but may be supplied from the upper gas introduction part 22a, or the gas introduction part 22a and You may make it supply from the gas introduction part of hydrogen desorption gas introduction provided separately from 22b.

  Each component of the plasma film forming apparatus 100 a is controlled by the control unit 50. The control unit 50 includes a process controller 51 including a CPU, a user interface 52 connected to the process controller 51, and a storage unit 53. The user interface 52 includes a keyboard on which a process manager manages command input to manage the plasma CVD apparatus 100b, a display that visualizes and displays the operating status of the plasma CVD apparatus 100a, and the like. The storage unit 53 stores a recipe in which a control program (software) for realizing various processes executed by the plasma CVD apparatus 100a under the control of the process controller 51, processing condition data, and the like are recorded. An arbitrary recipe is called from the storage unit 53 by an instruction from the user interface 52 as necessary, and is executed by the process controller 51. When the process controller 51 executes the recipe, the plasma film forming apparatus 100 a performs a desired process under the control of the process controller 51. 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 film forming apparatus 100a configured in this way can proceed with damage-free plasma processing to the base film or the like at a low temperature of 800 ° C. or lower, preferably 600 ° C. or lower, and has excellent plasma uniformity. Process uniformity can be achieved.

  FIG. 3A is a flowchart showing a basic flow of the film forming method according to the present embodiment.

  As shown in FIG. 3A, first, a film forming source gas containing hydrogen is supplied into the chamber 1, and a thin film into which hydrogen has been taken is formed on a semiconductor substrate (step 1).

  Next, a hydrogen desorption gas for desorbing hydrogen from the thin film is supplied into the chamber 1 to desorb hydrogen from the formed thin film (step 2).

  FIG. 4 is a diagram showing the difference (stress change amount) between the stress during deposition and the stress after desorption of hydrogen. FIG. 4 shows a case where the thin film is a silicon nitride film in which hydrogen is incorporated.

  As shown in FIG. 4, the stress greatly changes as the concentration decreases greatly, that is, as the amount of detached hydrogen increases. In particular, when the thin film is a silicon nitride film, compressive stress is increased.

  FIG. 5 is a diagram showing the relationship between the stress generated in the thin film and the processing pressure.

  A line I in FIG. 5 indicates stress generated in the silicon nitride film formed under the following process conditions.

<Plasma CVD film forming conditions (N ₂ / Si ₂ H ₆ gas system)>
N ₂ gas flow rate (gas introduction part 15a); 1100 mL / min (sccm)
Si ₂ H ₆ gas flow rate; 1 mL / min (sccm)
N ₂ gas flow rate (gas introduction part 15b); 100 mL / min (sccm)
Processing pressure: 4.0 Pa (30 mTorr), 6.7 Pa (50 mTorr), 13.3 Pa (100 mTorr) and 66.6 Pa (500 mTorr)
Temperature of mounting table 2; 500 ° C
Microwave power: 3000W
A line I in FIG. 5 represents a stress applied to the formed thin film under process conditions. A compressive stress is generated in the silicon nitride film formed using the N ₂ / Si ₂ H ₆ gas as a film forming source gas, and the compressive stress tends to increase as the processing pressure decreases.

  When hydrogen is released from the formed silicon nitride film, the compressive stress shown in FIG. 4 can be applied to the compressive stress shown by the line I. As a result, the compressive stress generated in the silicon nitride film is further increased as shown by line II in FIG.

  As described above, by releasing hydrogen from the formed thin film, it is possible to apply a greater stress to the formed thin film than the stress given in the process conditions.

However, when the hydrogen desorption gas reacts well with the thin film on which the film has been formed, the hydrogen desorption gas may rather cause the thin film to decrease. In particular, when the hydrogen desorption gas is fluorine, chlorine, or a single compound gas containing both fluorine and chlorine, the thin film tends to decrease in thickness. In particular, when the formed thin film is a silicon nitride film in which hydrogen is taken in, and the hydrogen desorption gas is NF ₃ gas, this tendency to reduce the film is remarkable. Furthermore, the film thickness can be further reduced by diluting with a rare gas.

  When the amount of film reduction increases, it becomes difficult to satisfy the designed film thickness of the silicon nitride film, and the silicon nitride film that should have been formed may disappear. As semiconductor elements become finer year by year, the thin films in semiconductor integrated circuits tend to be thinner. For this reason, when film thickness reduction occurs, there is a possibility that the characteristics of the semiconductor integrated circuit will be significantly affected in the future. Moreover, this effect may increase at an accelerated rate in the future. Even if it was possible to apply more stress to the formed thin film than is possible under the process conditions, it is difficult to apply it to an actual semiconductor device process if the film thickness is reduced. This makes it difficult to form a thin film having a stress greater than that given by process conditions.

  Therefore, in the present embodiment, the invention has been devised so that hydrogen can be efficiently removed without reducing the film thickness by minimizing the amount of the halogen compound gas from the thin film by using a dilution gas as described below.

First, a rare gas for plasma excitation, for example, Ar gas is supplied into the chamber 1 and microwaves are emitted from the microwave radiation holes 33 to make the inside of the chamber 1 a plasma atmosphere. Then, as shown in FIG. 3B, hydrogen desorption gas is supplied into the chamber 1 for a predetermined time (step 11). An example of the predetermined time is a time during which the amount of film reduction of the formed thin film falls within an allowable range from the start of supply of the hydrogen desorption gas, or a time during which the formed thin film does not decrease. FIG. 6 shows an example of a specific time chart. As shown in the period from time T1 to time T2 in FIG. 6, in this example, rare gas 2000 sccm and NF ₃ gas were supplied to the chamber 1 at a flow rate of 20 sccm for 3 seconds. Thus, the atmosphere of the chamber 1 becomes an atmosphere for releasing hydrogen from the thin film. In this example, the thin film is a silicon nitride film in which hydrogen is incorporated.

Next, as shown in FIG. 3B, the supply of the hydrogen desorption gas is stopped, and the atmosphere in the chamber 1 is returned to the atmosphere before the hydrogen desorption gas is supplied (step 12). The atmosphere before the hydrogen desorption gas is supplied is a state where there is no or almost no hydrogen desorption gas in the atmosphere in the chamber 1. In this example, as shown in the period from time T2 to time T3 in FIG. 6, the supply of NF ₃ gas is stopped, and exhaust or natural extinction or exhaust and natural extinction is used so that the NF ₃ gas does not remain in the chamber 1. Then, while reducing the concentration of the NF ₃ gas in the chamber 1, the atmosphere before the NF ₃ gas supply is restored (from time T2 to time T3). In this example, the supply of NF ₃ gas was stopped for 60 seconds while exhausting the inside of the chamber 1 with a predetermined exhaust amount.

  Further, in the present embodiment, steps 11 and 12 are repeated a predetermined number of times.

In this example, as shown in the period from time T3 to time T4 in FIG. 6, when the atmosphere of the chamber 1 returns to the atmosphere before the NF ₃ gas supply, the NF ₃ gas is again supplied at a flow rate of 20 sccm for 3 seconds. Supplied to. Thereafter, as shown in the period from time T4 to time T5, the supply of the NF ₃ gas is stopped again, and the atmosphere in the chamber 1 is returned to the atmosphere before the NF ₃ gas supply. By repeating steps 11 and 12 in this manner, the hydrogen desorption gas, in this example, NF ₃ gas, is supplied in a pulsed manner into the chamber 1. When Steps 11 and 12 are repeated a predetermined number of times, the process of desorbing hydrogen ends, and the thin film formation process ends.

As described above, in this example, the NF ₃ gas is supplied into the chamber 1 in a pulsed manner so that the atmosphere inside the chamber 1 is changed to an NF ₃ gas-containing atmosphere for a short period of several seconds to several tens of seconds. It is possible to return to the atmosphere before the NF ₃ gas supply, that is, the atmosphere without or almost without the NF ₃ gas.

Even if the inside of the chamber 1 has an NF ₃ gas-containing atmosphere for several seconds to several tens of seconds from the start of the supply of NF ₃ gas, hydrogen is released from the silicon nitride film that has taken in hydrogen. As shown in FIG. 6, the amount of the detached hydrogen is accumulated every time the steps 11 and 12 are repeated.

  Thus, according to this example, hydrogen can be released from the formed silicon nitride film. Therefore, it is possible to apply more stress to the formed silicon nitride film than can be given under process conditions.

Additionally, a short period of several seconds to several tens of seconds from the start of the supply of the NF ₃ gas, NF ₃ gas, for example, a period that is not spread sufficiently at a concentration sufficient to the chamber 1. For this reason, it is a period in which the amount of reducing the nitrogen silicon film is very small, or a period in which the film is not reduced at all. As shown in FIG. 6, the reduction amount of the silicon nitride film by NF ₃ gas is also accumulated every time the above steps are repeated, but the reduction amount is very small or not reduced at all. The film amount can be reduced as compared with the comparative example (shown by the dotted line in FIG. 6) in which the NF ₃ gas is continuously supplied into the chamber 1, or the film reduction amount can be made zero.

  Thus, according to this example, a thin film having a stress greater than the stress given by the process conditions can be formed in a state where there is no risk of film thickness reduction or film thickness reduction does not occur. The ability to form a high-stress thin film with an amount of film reduction that does not interfere or with no film thickness reduction is advantageous for further miniaturization of semiconductor elements in the future.

In the first embodiment, the NF ₃ gas is supplied to the inside of the chamber 1 in a pulsed manner. However, even if the plasma is pulsed, the reduction amount of the silicon nitride film is reduced. It can be made small or can be in a state where no film reduction occurs.

(Second Embodiment)
FIG. 7 is a cross-sectional view showing an example of a plasma film forming apparatus that can be used in the plasma CVD silicon nitride film forming method according to the second embodiment of the present invention.

  As shown in FIG. 7, the plasma film forming apparatus 100b differs from the apparatus 100a shown in FIG. 1 in that the gas introduction part is a shower head 22c and the susceptor 3 is embedded with a lower electrode 6d. It is connected to the RF power source 6f through the matcher 6e.

  Between the susceptor 3 and the microwave introduction unit 10 in the processing chamber 1, a shower head 22 c for introducing a processing gas is provided horizontally. As shown in FIG. 8, the shower head 22 c 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.

In this example, the gas supply unit 27 includes a silicon-containing gas supply source 27a, a nitrogen and hydrogen-containing gas supply source 27b, a plasma generation gas supply source 27c, and a hydrogen desorption gas supply source 27d. In this example, silicon-containing gas, nitrogen and hydrogen-containing gas, and hydrogen desorption gas are supplied to the shower head 22c through the gas line 21a. In FIG. 7, illustration of a mass flow controller, a valve, and the like is omitted. The shower head 22c allows the gas to flow inside the processing chamber 1 at a predetermined flow rate through the lattice-like gas flow passages 23 and the gas discharge holes 24 formed on the susceptor 3 side of the lattice-like gas flow passages 23. Among these, it supplies to the space 1c between the shower head 22c and the susceptor 3. An example of a silicon-containing gas is disilane, and an example of a nitrogen and hydrogen-containing gas is ammonia. An example of the hydrogen desorbing gas is, for example, a halogen-containing gas, as in the first embodiment. Examples of the halogen include fluorine or chlorine, and examples of the halogen-containing gas include a fluoride of nitrogen or a fluoride of chlorine. Examples of nitrogen fluoride, chlorine fluoride, or gas containing these fluorides include NF ₃ gas, NF ₃ -containing gas, ClF ₃ gas, or ClF ₃ -containing gas. be able to. Further, when a nitrogen fluoride, a chlorine fluoride, or a gas containing these fluorides is used as the hydrogen desorption gas, it can also be used as a cleaning gas for cleaning the inside of the chamber 1 and the like. . In this case, the hydrogen desorption gas may be supplied from a cleaning gas supply source connected to the plasma film forming apparatus 100a.

  On the side wall of the processing chamber 1 between the shower head 22c and the microwave introduction unit 10, an annular plasma generation gas introduction unit 22d is provided. The plasma generation gas introduction section 222 d includes a plurality of discharge holes 22 e for discharging the plasma generation gas toward the inside of the processing chamber 1. The plasma generating gas is supplied to the gas introduction part 22d. In FIG. 7, illustration of a mass flow controller, a valve, and the like is omitted. The gas introduction unit 22d supplies the plasma generation gas to the space 1d between the shower head 22c and the microwave introduction unit 10 in the processing chamber 1 through the discharge hole 22e. 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 plasma gas is supplied to the space 1c through the space 25 of the shower head 22c, and the processing gas discharged from the gas discharge holes 24 of the shower head 22c is converted into plasma in the space 1c.

  The plasma film forming apparatus 100b configured as described above deposits 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 27 into the space 1 d of the processing chamber 1 through the discharge hole 22 e, 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 25 of the shower head 22c and is supplied to the space 1c.

Next, silicon-containing gas, nitrogen and hydrogen-containing gas are supplied from the gas supply unit 27 into the space 1c in the processing chamber 1 through the gas discharge holes 24 of the shower head 22c. The gas is excited and plasmatized by the plasmatized gas that has passed through the lattice-like 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.

  Next, hydrogen is released from the deposited thin film using the method described in the first embodiment.

  A plasma CVD silicon nitride film is formed using the plasma film formation apparatus 100b shown in FIG. 7, and the amount of hydrogen (Si—H bond, N—H bond, and Si—H in the formed plasma CVD silicon nitride film is formed. The processing temperature dependency, the silicon-containing gas flow rate dependency, the microwave power dependency, and the processing pressure dependency were measured. 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. 9 is a diagram showing the processing pressure dependence of the hydrogen amount, FIG. 9A shows the processing conditions, and FIG. 9B shows the relationship between the hydrogen amount and the processing pressure.

As shown in FIG. 9A, 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. 9B, when the processing pressure in the chamber 1 is set to 1000 mTorr (133.3 Pa) or less, the N—H bond is superior to the Si—H bond as in the normal low pressure plasma CVD method. It turned out to be. This is supply-limited. Specifically, when the plasma CVD apparatus 100b shown in FIG. 7 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.

Furthermore, in this example, after obtaining a plasma CVD silicon nitride film with a small amount of hydrogen in the total film, hydrogen is further desorbed from the plasma CVD silicon nitride film using the method described in the first embodiment. . Therefore, a plasma CVD silicon nitride film having a total hydrogen content of 2 × 10 ²¹ atoms / cc or less can be obtained.

Further, in this example, the hydrogen desorption gas for desorbing hydrogen from the plasma CVD silicon nitride film is supplied to the chamber 1 in a pulsed manner, the plasma is pulsed, or the hydrogen desorbing gas is supplied in a pulsed manner. At the same time, hydrogen is released from the plasma CVD silicon nitride film while pulsing the plasma. Therefore, it is possible to obtain a plasma CVD silicon nitride film having a total hydrogen amount of 10 ²¹ atoms / cc or less in a range where there is no problem or no film reduction occurs.

  Thus, in the plasma CVD silicon nitride film having a small amount of hydrogen in the total film, the probability that vacancies are generated due to hydrogen escape from the film is reduced. Therefore, the probability of occurrence of electron traps is reduced, the film quality is hardly deteriorated, 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 according to the second embodiment, the plasma CVD capable of reducing the total hydrogen amount in the film, which is the sum of the amount of N—H bonds and the amount of Si—H bonds. A method for forming a silicon nitride film can be provided.

(Third embodiment)
FIG. 10 shows the relationship between the flow rate ratio between the halogen compound gas and the rare gas (halogen compound gas / rare gas) and the film reduction rate.

  As shown in FIG. 10, the film reduction rate is reduced by reducing the flow rate ratio between the halogen compound gas and the rare gas. Practically, the film reduction rate is preferably 5% or less, and in order to make the film reduction rate 5% or less, the flow rate ratio between the halogen compound gas and the rare gas should be 0.006 or less. preferable.

  Thus, a film with little hydrogen and difficult to reduce the film 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 a total hydrogen amount in the order of 10 ²¹ atoms / cc or less is used as an etching stopper and a hard mask.

  11A to 11C are cross-sectional views illustrating 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. 11A, 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. Furthermore, hydrogen is released from the formed plasma silicon nitride film using the method described in the first embodiment. By separating hydrogen in this manner, the etching stopper 202 using a plasma CVD silicon nitride film having a total hydrogen amount in 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. Furthermore, hydrogen is released from the formed plasma silicon nitride film using the method described in the first embodiment. By desorbing hydrogen in this manner, the hard mask 202 using a plasma CVD silicon nitride film having a total hydrogen content in 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. 11B, the hard mask 204 is etched using the mask pattern 205 as a mask.

  Next, as shown in FIG. 11C, 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.

In the method of the present invention, a hydrogen desorbing gas for desorbing hydrogen from a plasma CVD silicon nitride film is supplied to the chamber 1 in a pulsed manner, a plasma is pulsed in, or a hydrogen desorbing gas is supplied in a pulsed manner. At the same time, hydrogen is released from the plasma CVD silicon nitride film while pulsing the plasma. For this reason, even if the plasma CVD silicon nitride film is thinly formed, the total amount of hydrogen in the film is 10 ²¹ atoms / cc or less in a state where there is no reduction in film thickness, or no film reduction occurs. A CVD silicon nitride film can be obtained.

  Thus, since the plasma CVD silicon nitride film formed by the method of the present invention is difficult to reduce, the internal structure of the semiconductor integrated circuit such as the etching stopper 202 for stopping the etching and the interlayer insulating film 203 is processed. It is suitable for a hard mask 204 used as an etching mask.

  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 formed by the method of the present invention is used for a cap layer and a sidewall spacer in a self-aligned contact structure.

  12A to 12D 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. 12A, a semiconductor wafer W (a 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. Furthermore, hydrogen is released from the formed plasma silicon nitride film using the method described in the first embodiment. By separating hydrogen in this manner, the cap layer 303 using a plasma CVD silicon nitride film having a total hydrogen amount in 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. 12B, 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. Furthermore, hydrogen is released from the formed plasma silicon nitride film using the method described in the first embodiment. 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. By separating hydrogen as described above, the sidewall spacer 305 using the plasma CVD silicon nitride film having a total hydrogen amount in the order of 10 ²¹ atoms / cc or less can be formed.

  Next, as illustrated in FIG. 12C, 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. 12D, the contact hole 307 is filled with the conductive material 308, thereby forming the structure according to Application Example 2.

In the method of the present invention, a hydrogen desorbing gas for desorbing hydrogen from a plasma CVD silicon nitride film is supplied to the chamber 1 in a pulsed manner, a plasma is pulsed in, or a hydrogen desorbing gas is supplied in a pulsed manner. At the same time, hydrogen is released from the plasma CVD silicon nitride film while pulsing the plasma. For this reason, even if the plasma CVD silicon nitride film is thinly formed, the total amount of hydrogen in the film is 10 ²¹ atoms / cc or less in a state where there is no reduction in film thickness, or no film reduction occurs. A CVD silicon nitride film can be obtained. Therefore, since the plasma CVD silicon nitride film formed by the method of the present invention has good etching resistance, the contact hole 307 is formed on the gate electrode 302 when the contact hole 307 is formed in a self-aligned manner with respect to the space between the gate electrodes 302. It is also suitable for the cap layer 303 and the side wall spacer 305 to be covered.

(Fourth 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. 13 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. 13, 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, particularly the total amount of hydrogen in the total film, decreases from the plasma CVD silicon nitride film.

In the present embodiment, a plasma CVD silicon nitride film having a total hydrogen content of, for example, the order of 10 ²¹ atoms / cc is formed by the film forming method described in the second embodiment, and then the plasma CVD silicon nitride is formed. Further desorb hydrogen from the membrane. For this reason, the total amount of hydrogen in the film is less than the order of 10 ²¹ atoms / cc, such as the order of 10 ²⁰ atoms / cc, the order of 10 ¹⁹ atoms / cc, the order of 10 ¹⁸ atoms / cc, and so on. A plasma CVD silicon nitride film is obtained. For this reason, for example, a plasma CVD silicon nitride film having a compressive stress exceeding −1500 Pa can be obtained.

  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.

  FIG. 14 is a cross-sectional view showing the step coverage of a plasma CVD silicon nitride film formed using ammonia gas, and FIG. 15 is a cross-sectional view showing the step coverage of a plasma CVD silicon nitride film formed using nitrogen gas. is there. FIG. 15 is a reference example.

As shown in FIG. 14, 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 on the step upper surface (Side). 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. 15, 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.

  Thus, for example, a plasma CVD silicon nitride film formed by using the film forming method described in the second embodiment uses a nitrogen- and hydrogen-containing gas as a nitriding process gas, so that the nitriding process is performed. It was confirmed that the step coverage can be improved as compared with the case of using nitrogen gas as the gas. 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.

Furthermore, in the present embodiment, after the plasma CVD silicon nitride film having a total hydrogen amount in the order of 10 ²¹ atoms / cc is formed by the film forming method described in the second embodiment, this plasma CVD is performed. Hydrogen is further released from the silicon nitride film. For this reason, for example, a plasma CVD silicon nitride film having a compressive stress exceeding −1500 Pa can be obtained with good step coverage. The film is advantageous, for example, for application to an internal structure of a semiconductor integrated circuit device as described below.

(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.

  16A and 16B 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. 16A, the surface of the semiconductor wafer W (silicon wafer in this example) is thermally oxidized to form a thermal silicon oxide film to be the gate insulating film 401, and on the thermal silicon oxide film to be 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 illustrated in FIG. 16B, 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. Furthermore, hydrogen is released from the formed plasma silicon nitride film using the method described in the first embodiment. By releasing hydrogen in this manner, the stress liner 404 using a plasma CVD silicon nitride film having a total hydrogen amount in the order of 10 ²¹ atoms / cc or less can be formed.

A plasma CVD silicon nitride film having a total hydrogen content in the order of 10 ²¹ atoms / cc or less can have a compressive stress of −1500 Pa or less, for example, as shown in FIG.

As described above, by using the plasma CVD silicon nitride film in which the total amount of hydrogen in the film is controlled to the order of 10 ²¹ atoms / cc or less for the stress liner 404, a strong compressive stress can be applied to the channel. 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.

  Further, when the plasma CVD silicon nitride film uses nitrogen and hydrogen containing gas, for example, ammonia, as the nitriding process gas, the step coverage is good. For example, as described with reference to FIG. 17, 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 embed between 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.

In addition, in this example, hydrogen is released from the plasma CVD silicon nitride film while supplying a hydrogen release gas for releasing hydrogen from the plasma CVD silicon nitride film to the chamber 1 in a pulsed manner. Therefore, it is possible to obtain a plasma CVD silicon nitride film having good step coverage and a total amount of hydrogen in the film of 10 ²¹ atoms / cc or less in a state where there is no problem or no film thickness reduction occurs. .

  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.

  In the above embodiment, the microwave plasma film forming apparatus is exemplified as the film forming apparatus. However, the present invention is not limited to the microwave plasma film forming apparatus, and other plasma film forming apparatuses can be used.

  Furthermore, in the above-described embodiment, another new stress is generated in addition to the stress given by the process conditions in the silicon nitride film formed by releasing hydrogen, but another new stress is generated. The thin film to be formed is not limited to the silicon nitride film. The present invention can be applied to any thin film as long as another new stress is caused by releasing hydrogen.

  Further, although the microwave plasma film forming apparatus is used for forming the thin film, the present invention is not limited to the thin film formed using the microwave plasma film forming apparatus. A thin film formed using a parallel plate type plasma film forming apparatus may be used, or a thin film formed using a thermal film forming apparatus is not limited to plasma. Further, the film forming method is not limited to the CVD method, and a thin film formed by using the sputtering method may be used. Further, the present invention can be applied not only to vapor phase growth but also to liquid layer growth, for example, a thin film formed using an LPD method or a plating method.

Sectional drawing which shows typically an example of a plasma film-forming apparatus Plan view showing an example of a planar antenna A flow chart showing a basic flow of a film forming method according to an embodiment Diagram showing the relationship between the amount of detached hydrogen and stress Diagram showing the relationship between stress and processing pressure Diagram showing an example of hydrogen desorption process Schematic sectional view showing an example of a plasma CVD apparatus used in a method for forming a plasma CVD silicon nitride film according to the second embodiment of the present invention Plan view showing an example of a shower head Diagram showing dependence of hydrogen amount on processing pressure Diagram showing the relationship between the flow rate ratio between the halogen compound gas and the rare gas and the film reduction 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, 7a ... Liner, 7b ... Baffle plate, 8 ... Strut, DESCRIPTION OF SYMBOLS 9 ... Gate valve, 10 ... Microwave introduction part, 11 ... Microwave transmission board, 12 ... Planar antenna member, 13 ... Slow wave material, 14 ... Ring-shaped support part, 15 ... Seal member, 16 ... Slot hole, 17 ... Shield cover, 18 ... waveguide, 19 ... matching circuit, 20 ... microwave generator, 21 ... mode converter, 22a, 22b, 22d ... gas introduction part, 22c ... shower head, 27 ... gas supply part, 50 ... Control unit 51 ... Process controller 52 ... User interface 53 ... Storage unit 100a, 100b ... Plasma film forming apparatus 201 ... Insulating film 202 ... Etchan Stopper, 203 ... Interlayer insulating film, 204 ... Hard mask, 205 ... Photoresist, 206 ... Groove or hole, 301 ... Gate insulating film, 302 ... Gate electrode, 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 (12)

Supplying a film-forming source gas containing hydrogen into the chamber, and forming a thin film into which hydrogen has been incorporated on a semiconductor substrate;
And a step of desorbing hydrogen from the thin film while supplying a hydrogen desorption gas containing a substance capable of desorbing hydrogen from the thin film to the chamber in a pulsed manner. A method for forming a high-stress thin 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;
The plasma-containing silicon-containing gas and the nitrogen- and hydrogen-containing gas are supplied onto the surface of the substrate to be processed, the film formation conditions are set on the surface of the substrate to be processed, the processing temperature is 300 ° C. or more and 600 ° C. hereinafter, the flow ratio of the silicon-containing gas and a nitrogen and hydrogen-containing gas 0.005 0.015, microwave power 0.5 W / cm ² or more 2.045W / cm ² or less, 133.3 Pa process pressure A step of forming a silicon nitride film at 13333 Pa or less;
Desorbing hydrogen from the thin film while supplying a hydrogen desorption gas containing a substance for desorbing hydrogen from the silicon nitride film in a pulsed manner to the chamber;
A method of forming a high-stress thin film, comprising:   The method for forming a high-stress thin film according to claim 1 or 2, wherein the substance for releasing hydrogen from the thin film is a halogen-containing gas.   3. The method for forming a high stress thin film according to claim 1, wherein the halogen is fluorine or chlorine. The film forming raw material gas containing hydrogen includes a gas containing silicon hydride and a gas containing nitrogen,
The high stress thin film forming method according to claim 1, wherein the thin film is a silicon nitride film.   6. The method of forming a high stress thin film according to claim 5, wherein the substance for releasing hydrogen from the silicon nitride film is a fluoride of nitrogen or a fluoride of chlorine.   7. The method for forming a high stress thin film according to claim 6, wherein the gas containing the fluoride of nitrogen or the fluoride of chlorine is a cleaning gas for cleaning the inside of the chamber. Removing hydrogen from the thin film,
The hydrogen desorbing gas is introduced into the chamber within a time when the amount of film reduction of the formed thin film falls within an allowable range from the start of supply of the hydrogen desorbing gas or within a time when the formed thin film does not decrease. A first step of supplying;
A second step of stopping the supply of the hydrogen desorbing gas and returning the atmosphere in the chamber to the atmosphere before the hydrogen desorbing gas is supplied,
3. The method for forming a high stress thin film according to claim 1, wherein the first step and the second step are repeated a predetermined number of times.   3. The method for forming a high stress thin film according to claim 1, wherein the step of releasing hydrogen from the thin film is performed in a plasma atmosphere. Forming an etching stopper containing a substance different from the insulating film on the insulating film using the film forming method according to claim 1;
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 using the film forming method according to claim 1;
Forming a groove or a hole in the interlayer insulating film using the hard mask as an etching mask;
A method for manufacturing a semiconductor integrated circuit device, comprising: 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 using the film forming method according to any one of claims 1 to 9;
A method for manufacturing a semiconductor integrated circuit device, comprising: 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;
10. The film forming method according to claim 1, wherein a stress liner is provided on the semiconductor substrate to cover the gate electrode and apply stress to a portion of the semiconductor substrate under the gate electrode. 11. Forming, and
A method for manufacturing a semiconductor integrated circuit device, comprising:

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