JP2013012776A - Plasma processing apparatus and substrate placement base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing apparatus which provides stress, which is larger than stress provided under the process conditions, to a thin film.SOLUTION: A plasma processing apparatus includes: a process container 1; a substrate placement base 3 provided in the process container 1 and on which a processed substrate W is placed; and a gas introduction part 27 supplying gas into the process container 1. A substrate placement surface 3a of the substrate placement base 3, on which the processed substrate W is placed, has a recess 3b. When the diameter of the recess 3b is set to be 200 mm, the depth of the deepest part is set to be 1 mm or less.

Description

  The present invention relates to a plasma processing apparatus and a substrate mounting table.

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 plasma processing apparatus and a substrate mounting table capable of applying a stress to a thin film that is greater than a stress given in process conditions.

  In order to solve the above problem, a plasma processing apparatus according to a first aspect of the present invention includes a processing container, a substrate mounting table provided in the processing container on which a substrate to be processed is mounted, and the processing A gas introduction part for supplying gas in the container, the substrate placement surface of the substrate placement table on which the substrate to be processed is placed has a depression, and the diameter of the depression is 200 mm. When the depth of the deepest part is 1 mm or less.

  A substrate mounting table according to a second aspect of the present invention is a substrate mounting table that is used in a plasma processing apparatus and on which a processing target substrate to be plasma processed is mounted, and the processing target substrate of the substrate mounting table. When the substrate mounting surface on which the substrate is mounted has a recess, and the diameter of the recess is 200 mm, the depth of the deepest portion is 1 mm or less.

  According to the present invention, it is possible to provide a plasma processing apparatus and a substrate mounting table that can apply a stress greater than the stress applied in the process conditions to the thin film.

Sectional drawing which shows typically an example of a plasma film-forming apparatus Plan view showing an example of a planar antenna The figure which shows an example of a mounting base Sectional view showing film formation The figure which shows the other example of a mounting base The figure which shows the relation between the processing pressure in plasma CVD and the magnitude of the stress of the silicon nitride film 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 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

  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 mounting table) 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 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 cleaning 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 cleaning 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.

As the cleaning gas, ClF ₃ , HF, NF ₃ or the like can be used.

  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 and the inert gas reach the gas introduction part 22b through the gas line 21a, 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 simultaneously with the film forming source gas.

  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.

  Furthermore, the susceptor (substrate mounting table) 3 of the plasma film forming apparatus 100a according to the present embodiment has the following configuration.

  3A is a perspective view showing an example of the mounting table 2, and FIGS. 3B and 3C are cross-sectional views taken along lines 3B-3B and 3C-3C in FIG. 3A, respectively.

  As shown in FIGS. 3A to 3C, the wafer placement surface 3a on which the wafer W of the susceptor 3 is placed has a spherical recess 3b. An example of the curved surface of the recess 3b is that a curvature radius R (R = r) is constant at any position when a virtual true sphere having a radius r is assumed on the placement surface 3a.

  The wafer W is chucked to the susceptor 3 with its center C0 positioned so as to correspond to the deepest part of the recess 3b, in this example, the center C1 of the recess 3b, and its edge E0 positioned in the recess 3b. Is done. As a result, the wafer W is depressed along the curved surface of the recess 3b with a constant radius of curvature at any position, for example, the uppermost surface (deposition surface on which a thin film is formed) TS0 of the wafer W is contracted. (See FIG. 4A).

  A thin film, in this example, a silicon nitride film 60, is formed on the wafer W while the uppermost surface TS0 of the wafer W is bent so as to contract (see FIG. 4B).

  When the wafer W on which the silicon nitride film 60 is formed is removed from the susceptor 3, the wafer W returns to the horizontal. Since the silicon nitride film 60 is formed in a bent state in accordance with the bending state of the wafer W, the area of the uppermost surface TS2 of the silicon nitride film 60 is smaller than the area of the lowermost surface BS2 (see FIG. 4C). When such a silicon nitride film 60 is returned to the horizontal position (see FIG. 4D), a force F that tries to spread from the center C0 of the wafer W toward the edge E0 acts on the top surface TS2 of the silicon nitride film 60 and its vicinity. (See FIG. 4E). When the force F acts, a high tensile stress is generated in the silicon nitride film 60. In this example, since the wafer W is recessed so that the radius of curvature is constant at any position, the force F acts uniformly on the silicon nitride film 60. Therefore, high tensile stress can be uniformly generated in the silicon nitride film 60.

  5A is a perspective view showing another example of the susceptor 3, and FIGS. 5B and 5C are sectional views taken along lines 5B-5B and 5C-5C in FIG. 5A, respectively.

  As shown in FIGS. 5A to 5C, the wafer placement surface 3a on which the wafer W of the susceptor 3 is placed may be provided with a spherical bulge 3c. In this case, compressive stress can be generated in the formed thin film. An example of the curved surface of the bulge 3c is to form a curvature radius R (R = r) at any position when a virtual true sphere with a radius r is hypothesized below the placement surface 3a. Also in this case, the wafer W is arranged so that its center C0 corresponds to the top of the bulge 3c, in this example, the center of the bulge 3c, and the edge of the wafer W is arranged in the bulge 3c. What is necessary is just to be chucked by the mounting base 2 in the state.

  The stress σ acting on the silicon nitride film 60 can be expressed by the following equation.

σ = Eh2 / {(1-ν) 6Rt}
Here, E / (1-ν) is the biaxial elastic modulus (Pa) of the wafer W, h is the thickness (m) of the wafer W, t is the thickness (m) of the silicon nitride film 60, and R is the curvature of the wafer W. The radius (m) and σ are the average stress (Pa) of the thin film. An example of the value of the biaxial elastic modulus E / (1-ν) is 1.805 × 10 ¹¹ Pa when the surface orientation of the wafer W is (100). When the average stress σ is positive, it is tensile stress, and when it is negative, it is compressive stress.

  The curvature radius R is infinite, that is, the curvature is zero when the wafer mounting surface 3a is flat. If a thin film is formed on the wafer W placed on the flat wafer placement surface 3a under the condition that neither tensile stress nor compressive stress is generated, no stress is generated. There is no stress. If the wafer mounting surface 3a is not flat, a finite value is generated in the radius of curvature R, and a recess 3b or a bulge 3c is generated on the wafer mounting surface 3a, and the mounted wafer W bends. If the bent wafer W is returned to the horizontal position, a tensile stress or a compressive stress is generated in the thin film formed on the wafer W.

  If the wafer W is bent too much, it may break. Further, if the deflection of the wafer W is small, even if the wafer W is returned to a horizontal position, the thin film is not stressed much. For this reason, the depression 3b or the bulge 3c has an upper limit and a lower limit.

  For example, when the diameter of the recess 3b is 200 mm, the lower limit is a spherical shape such that the depth of the deepest portion of the recess 3b is about 0.5 mm, and the upper limit is about 1 mm. It is good to make it spherical.

  Further, when the diameter of the bulge 3c is 240 mm, the lower limit is a spherical shape in which the height of the top of the bulge 3c is about 0.5 mm, and the upper limit is about 1 mm. It is good to make it spherical.

  The stress of the thin film varies depending on the film forming source gas and the processing pressure, that is, the process conditions.

  FIG. 6 is a diagram showing the relationship between the processing pressure in plasma CVD and the magnitude of stress in the silicon nitride film. The vertical axis in FIG. 6 indicates the magnitude of stress in the silicon nitride film, where the positive (plus) side is tensile stress and the negative (minus) side is compressive stress. In FIG. 6, the processing pressure on the horizontal axis indicates mTorr on a logarithmic scale. The upper part shows the value of mTorr, and the lower part shows the value of Pa converted.

In this test, the silicon nitride film was formed under the following plasma CVD conditions by changing the film forming gas.
<Plasma CVD film formation conditions (NH ₃ / Si ₂ H ₆ gas system)>
NH ₃ gas flow rate: 500 mL / min (sccm)
Si ₂ H ₆ gas flow rate; 5 mL / min (sccm)
Processing pressure: 2.7 Pa (20 mTorr), 6.7 Pa (50 mTorr), 40.0 Pa (300 mTorr) and 133.3 Pa (1 Torr)
Temperature of susceptor 3; 400 ° C
Microwave power: 2000W
<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 susceptor 3; 500 ° C
Microwave power: 3000W
6, when the film forming gas is NH ₃ / Si ₂ H ₆ gas, tensile stress is generated in the silicon nitride film, and the tensile stress tends to increase as the processing pressure increases. A tensile stress of about 400 MPa is obtained at a processing pressure of 7 Pa.

  Therefore, when tensile stress is applied to the silicon nitride film, the processing pressure is preferably 6.7 Pa (50 mTorr) or more. In order to form a silicon nitride film having a high tensile stress of 800 MPa or more, for example, 800 to 2000 MPa, the processing pressure is preferably set to 40 Pa or more, for example, 40 to 266.6 Pa (300 mTorr to 2 Torr).

  Furthermore, in order to give a high tensile stress of 1000 MPa or more, for example, 1000 to 2000 MPa, it is preferable to set the treatment pressure to 53.3 Pa or more, for example, 53.3 to 266.6 Pa (400 mTorr to 2 Torr). Furthermore, in order to give a high tensile stress of 1500 MPa or more, for example 1500 to 2000 MPa, it is preferable to set the treatment pressure to 133.3 Pa or more, for example 133.3 to 266.6 Pa (1 Torr to 2 Torr). This is considered that the tensile stress was increased by decreasing the Si—H amount and increasing the N—H amount having a large bonding force.

Further, when the film forming gas is an N ₂ / Si ₂ H ₆ gas system, compressive stress is generated in the silicon nitride film, and the compressive stress tends to increase as the processing pressure decreases, and is about 5.3 Pa ( A compressive stress exceeding about −800 MPa is obtained at a processing pressure of less than 40 mTorr). Therefore, when compressive stress is applied to the silicon nitride film, the processing pressure is preferably less than 5.3 Pa (40 mTorr). Furthermore, in order to obtain a silicon nitride film having a high compressive stress of 1000 MPa or more, for example, 1000 to 1500 MPa, it is preferable to set the processing pressure to 4 Pa or less, for example, 1.3 to 4 Pa (10 mTorr to 30 mTorr). This is presumably because N ₂ gas that does not contain N—H was used as the gas species, so that N—H was not taken into the film and N—H was not contained.

  As shown in FIG. 6, when the silicon nitride film is formed without bending the wafer W, the tensile stress takes a value as shown by the curve I, and the compressive stress takes a value as shown by the curve II. .

  Further, as in the present embodiment, when the silicon nitride film is formed with the wafer W bent, and the wafer W is returned to the horizontal after the film formation, the value of the tensile stress is as shown by the curve III. And the compressive stress value is improved as shown in curve IV.

  As described above, according to the plasma film forming apparatus 100a according to the first embodiment, the wafer mounting surface 3a of the susceptor 3 is provided with the spherical recess 3b or the spherical bulge 3c, and the wafer W is bent. Since the thin film is formed on the wafer W in the state, a high tensile stress or a compressive stress higher than the stress obtained under the process conditions can be applied to the thin film formed on the wafer W.

(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.

  In this example as well, although not shown in FIG. 7, as in the first embodiment, the wafer mounting surface 3 a of the susceptor 3 has a spherical recess 3 b as shown in FIGS. 3A to 3C, or A spherical bulge 3c as shown in FIGS. 5A to 5C is provided.

  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, and a plasma generation gas supply source 27c. In this example, silicon-containing gas, nitrogen and hydrogen-containing gas are supplied to the shower head 22c via 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.

  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. 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.

  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 treatment temperature dependence of the hydrogen amount, FIG. 9A shows the treatment conditions, and FIG. 9B shows the relationship between the hydrogen amount and the treatment temperature.

As shown in FIG. 9A, the processing condition is 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 increments of 100 ° C. The processing temperature is the heating temperature of the susceptor 3 in this example.

  As shown in FIG. 9B, when the treatment 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 amount of hydrogen in the film (Total H)) was greatly reduced when the treatment temperature was 400 ° C. compared to when the treatment temperature was 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. 10 is a diagram showing the dependence of the amount of hydrogen on the flow rate of silicon-containing gas, FIG. 10A shows the processing conditions, and FIG. 10B shows the relationship between the amount of hydrogen and the flow rate of silicon-containing gas.

As shown in FIG. 10A, 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. 10B, 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. 11 is a diagram showing the dependence of the amount of hydrogen on the microwave power, FIG. 11A shows the processing conditions, and FIG. 11B shows the relationship between the amount of hydrogen and the microwave power.

As shown in FIG. 11A, 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. 11B, 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 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. 12 is a diagram showing the processing pressure dependence of the hydrogen amount, FIG. 12A shows the processing conditions, and FIG. 12B shows the relationship between the hydrogen amount and the processing pressure.

As shown in FIG. 12A, 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. 12B, 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.

  In the present invention, a plasma CVD silicon nitride film with a small amount of hydrogen in the total film is further formed on the susceptor 3 provided with the recess 3b or the bulge 3c on the wafer mounting surface 3a. When a wafer W on which a plasma CVD silicon nitride film having a small amount of hydrogen in the film is formed is separated from the susceptor 3, a tensile stress or compression higher than the stress obtained under process conditions is applied to the plasma CVD silicon nitride film. Can give stress.

  Thus, according to the second embodiment, the total amount of hydrogen in the plasma CVD silicon nitride film can be reduced, and a plasma CVD silicon nitride film having a small total hydrogen amount can be obtained under process conditions. It is possible to provide a film forming method capable of applying a tensile stress higher than the stress or a compressive stress.

  Thus, the plasma CVD silicon nitride film with a small total amount of hydrogen formed at a low temperature using the method of the present invention has a low probability of generating vacancies caused by the escape of hydrogen from the film. 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.

(Third 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. 13 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. 13, 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.

As described above, the plasma CVD silicon nitride film having the N—H bond amount of 10 ²¹ atoms / cc order or less and the total film hydrogen amount of 10 ²¹ atoms / cc order or less is lower than the low pressure CVD silicon nitride film (3). Good etching resistance to hydrofluoric acid solution. 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 a total hydrogen amount in the order of 10 ²¹ atoms / cc or less is used as an etching stopper and a hard mask.

  14A to 14C 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. 14A, 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, an 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. With such film formation conditions, the hard mask 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, 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. 14B, the hard mask 204 is etched using the mask pattern 205 as a mask.

  Next, as shown in FIG. 14C, 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 a total hydrogen content of the order of 10 ²¹ atoms / cc or less at a low temperature has good etching resistance. Therefore, the etching stopper 202 for stopping the etching, the semiconductor integrated circuit such as the interlayer insulating film 203, etc. It is suitable for the hard mask 204 used as an etching mask when the internal structure is processed.

Further, as shown in FIG. 13, 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 ). 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. .

  As described above, the plasma CVD silicon nitride film suitable for the etching stopper 202 and the hard mask 204 formed at a low temperature by the method of the present invention, and the recess 3b or the bulge 3c on the wafer mounting surface 3a are provided. 3 is formed. For this reason, a high tensile stress or a compressive stress higher than the stress obtained under the process conditions can be applied to the plasma CVD silicon nitride film suitable for the etching stopper 202 and the hard mask 204.

(Application example 2)
Application Example 2 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 for a cap layer and a sidewall spacer in a self-aligned contact structure.

  15A to 15D 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. 15A, a semiconductor wafer W (a silicon wafer in this example) is thermally oxidized to form a thermal silicon oxide film to be a gate insulating film 301, and a gate is formed on the thermal silicon oxide film to be 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 film formation conditions, it is possible to form the cap layer 303 using a plasma CVD silicon nitride film having a total hydrogen content in the order of 10 ²¹ atoms / cc or less. 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. 15B, an insulating film to be the sidewall spacer 305 is formed on the source / drain regions 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. As a result, the sidewall spacer 305 using the plasma CVD silicon nitride film having a total hydrogen content in the order of 10 ²¹ atoms / cc or less can be formed at a low temperature.

  Next, as illustrated in FIG. 15C, 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. 15D, the contact hole 307 is filled with the conductive material 308, thereby forming the structure according to Application Example 2.

Since the plasma CVD silicon nitride film having a total hydrogen amount of 10 ²¹ atoms / cc or less has good etching resistance, the gate electrode when the contact hole 307 is formed in a self-aligned manner with respect to the space between the gate electrodes 302 is used. It is also suitable for the cap layer 303 covering the surface 302 and the side wall spacer 305.

  As described above, the plasma CVD silicon nitride film suitable for the cap layer 303 and the side wall spacer 305 formed at a low temperature by the method of the present invention is formed on the susceptor 3 provided with the recess 3b or the bulge 3c on the wafer mounting surface 3a. Form with. Therefore, a tensile stress or a compressive stress higher than the stress obtained under the process conditions can be applied to the plasma CVD silicon nitride film suitable for the cap layer 303 and the side wall spacer 305.

(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. 16 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. 16, 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 at a low temperature.

  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.

  17 is a cross-sectional view showing the step coverage of a plasma CVD silicon nitride film formed using ammonia gas, and FIG. 18 is a cross-sectional view showing the step coverage of a plasma CVD silicon nitride film formed using nitrogen gas. is there. FIG. 18 is a reference example.

As shown in FIG. 17, 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. 18, 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 at a low temperature using the film forming method described in the second embodiment can be used for nitriding by using nitrogen and hydrogen-containing gas as a nitriding process gas. It was confirmed that the step coverage can be improved as compared with the case of using nitrogen gas as the processing 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 this embodiment, after forming a plasma CVD silicon nitride film having a total hydrogen amount of, for example, the order of 10 ²¹ atoms / cc at a low temperature by the film forming method described in the second embodiment, Hydrogen is further desorbed from the plasma CVD 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.

  19A and 19B are cross-sectional views showing 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. 19A, the surface of a semiconductor wafer W (silicon wafer in this example) is thermally oxidized to form a thermal silicon oxide film to be a 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 shown in FIG. 19B, 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 a total hydrogen content 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 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.

  As described above, the plasma CVD silicon nitride film having good step coverage formed at a low temperature is formed on the susceptor 3 provided with the recess 3b or the bulge 3c on the wafer mounting surface 3a by the method of the present invention. For this reason, high tensile stress or compressive stress higher than the stress obtained under the process conditions can be applied to the plasma CVD silicon nitride film having good step coverage.

  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.

  For example, in the above embodiment, tensile stress or compressive stress is generated in the silicon nitride film, but the thin film that generates the stress is not limited to the silicon nitride film. For example, the present invention can be applied to any thin film that can be formed by a film formation apparatus, such as a silicon film, a silicon oxide film, a silicon oxynitride film, a metal film, and a metal silicide.

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

  DESCRIPTION OF SYMBOLS 1 ... Processing chamber (processing container), 2 ... Exhaust chamber, 3 ... Susceptor (substrate support stand), 3a ... Substrate mounting surface, 3b ... Spherical depression, 3c ... Spherical bulge, 4 ... Support part, 5 DESCRIPTION OF SYMBOLS ... Guide ring, 6 ... Heater, 7a ... Liner, 7b ... Baffle plate, 8 ... Post, 9 ... Gate valve, 10 ... Microwave introduction part, 11 ... Microwave transmission plate, 12 ... Planar antenna member, 13 ... Slow wave 14 ... annular support, 15 ... sealing member, 16 ... slot hole, 17 ... shield cover, 18 ... waveguide, 19 ... matching circuit, 20 ... microwave generator, 21 ... mode converter, 22a, 22b, 22d ... gas introduction unit, 22c ... shower head, 27 ... gas supply unit, 50 ... control unit, 51 ... process controller, 52 ... user interface, 53 ... storage unit, 100a, 00b ... Plasma deposition 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, 303 DESCRIPTION OF SYMBOLS ... 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 (2)

A processing vessel;
A substrate mounting table on which a substrate to be processed is mounted; provided in the processing container;
A gas introduction part for supplying gas in the processing container;
The substrate mounting surface of the substrate mounting table on which the substrate to be processed is mounted has a recess, and when the diameter of the recess is 200 mm, the deepest portion has a depth of 1 mm or less. Plasma processing equipment. A substrate mounting table that is used in a plasma processing apparatus and on which a substrate to be processed to be plasma is mounted,
The substrate mounting surface of the substrate mounting table on which the substrate to be processed is mounted has a recess, and when the diameter of the recess is 200 mm, the deepest portion has a depth of 1 mm or less. Substrate mounting table.

Images