JP6976213B2 - Manufacturing method of semiconductor device and film forming device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device and a film forming device.

In a semiconductor device, tungsten (W) is used as a material for embedding contact holes or the like formed in a semiconductor wafer (hereinafter simply referred to as a wafer) and its mutual diffusion barrier material, or as a material for forming a transistor gate electrode or the like. Widely used.

The tungsten film is formed by, for example, a physical vapor deposition (PVD) method or a chemical vapor deposition (CVD) method. In the CVD method, for example _{, a method is known in which tungsten hexafluoride (WF 6 ) gas and H 2} gas, which is a reducing gas, are _{used as raw material gases, and a reaction of WF 6} + 3H ₂ → W + 6HF is generated on a wafer. Further, an _{atomic layer deposition (ALD) method in which WF 6} gas and H ₂ gas are alternately supplied is also known (see Patent Document 1).

When the silicon oxide film is formed on the upper layer of the tungsten film formed by using the above-mentioned tungsten hexafluoride as a raw material gas, there is a problem that voids (pinholes) are generated at the interface between the silicon oxide film and the tungsten film. Not only the existence of voids themselves, but also the occurrence of a large amount of voids leads to film peeling of the silicon oxide film, which causes a problem on the device. Therefore, it is required to form a silicon oxide film in which voids are not formed.

In the above void, fluorine remaining as an impurity in the tungsten film binds to silicon at the interface with the silicon oxide film, and silicon fluoride (SiF ₄ ) that can be vaporized in the atmosphere of film formation of silicon oxide is formed. It is thought that this is the reason. Vaporizable means having sufficient vapor pressure to become a gas in the atmosphere of silicon oxide film formation. Silicon fluoride is formed at the interface between the silicon oxide film and the tungsten film, and is desorbed as a gas to form voids.

In Patent Document 2, a tungsten film or a tungsten oxide film is formed on a object to be treated, and an aminosilane-based gas is supplied while heating the object to be treated to form a seed layer on the tungsten film or the tungsten oxide film to form a seed. A method of forming a silicon oxide film on a layer is disclosed.

Patent Document 3 discloses a method for producing a silicon oxide film in which a substrate is placed in a reaction vessel, hydrogen gas is supplied, and then an oxidation gas is supplied and a silicon-containing gas is supplied.

WO2015 / 080058 Pamphlet Japanese Unexamined Patent Publication No. 2012-138500 Japanese Unexamined Patent Publication No. 2015-56633

In the above, fluorine remains as an impurity in the tungsten film, and during the film formation of silicon oxide formed on the upper layer, silicon fluoride that can be vaporized by reacting with silicon is formed, and voids are formed. Further, in a method for manufacturing a semiconductor device having a structure in which a first layer and a second layer are laminated, when the first layer contains impurities that react with the material of the second layer to form a vaporizable substance. , Voids are formed in the same manner as above. That is, during the film formation of the second film, impurities in the first film and a substance that can be vaporized are formed from the material of the second film, and this is separated to generate voids at the interface between the first film and the second film. do.

In a method for manufacturing a semiconductor device having a structure in which a first layer and a second layer are laminated, when the first layer contains impurities that react with the material of the second layer to form a vaporizable substance, the first layer is used. There is a demand for a method for manufacturing a semiconductor device and a film forming device that suppress the generation of voids at the interface between the first film and the second film.

The method for manufacturing a semiconductor device according to one aspect of the present invention includes a step of heat-treating a first layer formed on a substrate to remove impurities contained in the first layer, and an upper layer of the first layer. , have a step of forming a second layer containing a component vaporizable material reacts with the impurities is formed, the first layer may include a possible formation of an oxide film components, the impurities Between the step of removing and the step of forming the second layer, a step of supplying a reducing gas to the substrate to remove the oxidizing component contained in the first layer in the reducing atmosphere, and a step of removing the oxidizing component contained in the first layer in the reducing atmosphere. A step of supplying the raw material gas of the second layer to the first layer and forming an atomic layer of the raw material gas on the first layer, and a step of forming an atomic layer of the raw material gas on the first layer. after the oxidation gas is supplied to the atomic layer of the material gas formed on the first layer, to have a, a step of forming an oxide film by oxidizing the raw material gas to the first layer.

According to the disclosed semiconductor device manufacturing method and film forming apparatus, impurities that react with the material of the second layer to form a vaporizable substance when the first layer and the second layer are laminated are contained in the first layer. Even if it is contained in the above, it is possible to suppress the generation of voids at the interface between the first film and the second film.

It is sectional drawing which shows an example of the film forming apparatus which concerns on 1st Embodiment of this invention which can be applied to the manufacturing method of the semiconductor apparatus which concerns on 1st Embodiment of this invention. It is a perspective view which shows the structure of the processing chamber of the film forming apparatus of FIG. It is a schematic top surface showing the structure of the processing chamber of the film forming apparatus of FIG. It is a partial cross-sectional view of the film forming apparatus of FIG. It is another partial sectional view of the film forming apparatus of FIG. It is a perspective sectional view which shows an example of the semiconductor device applicable to the manufacturing method of the semiconductor device which concerns on 1st Embodiment of this invention. It is a partially enlarged sectional view of the semiconductor device of FIG. It is sectional drawing (A)-(D) which shows the manufacturing process of the manufacturing method of the semiconductor device which concerns on 1st Embodiment of this invention. It is sectional drawing (A)-(D) which shows the manufacturing process of the manufacturing method of the semiconductor device which concerns on a comparative example of this invention. It is a figure which shows the temperature-dwelling desorption gas analysis result which concerns on Example of this invention. It is a top view which showed an example of the film forming apparatus which concerns on 2nd Embodiment of this invention. It is a sequence diagram which shows an example of the manufacturing method of the semiconductor device which concerns on 2nd Embodiment of this invention.

The embodiment for carrying out the present invention will be described below. The same members and the like are designated by the same reference numerals and the description thereof will be omitted.

In the method of manufacturing a semiconductor device, when a silicon oxide film is formed on the upper layer of a tungsten film formed by using tungsten hexafluoride as a raw material gas, voids (pinholes) are generated at the interface between the silicon oxide film and the tungsten film. There's a problem. In the void, fluorine (F) remaining as an impurity in the tungsten film is bonded to silicon at the interface with the silicon oxide film to form vaporizable silicon fluoride (SiF ₄ ), and silicon fluoride is used as a gas. It is thought to occur by desorption. Vaporizable means having sufficient vapor pressure to become a gas in the atmosphere of silicon oxide film formation.

In order to suppress the generation of voids at the interface between the silicon oxide film and the tungsten film, there is a method of lowering the film formation temperature of the silicon oxide film. The lower the film formation temperature of the silicon oxide film, the more the diffusion of fluorine in the tungsten film can be suppressed. As a result, the bond between fluorine (F) and silicon is suppressed, and the generation of voids can be suppressed. For example, a gas capable of forming a silicon oxide film at a lower temperature is selected to form an oxide film at a lower temperature. Process construction in a temperature range where fluorine in the tungsten film does not react with silicon when the silicon oxide film is formed, and the film formation of the silicon oxide film is set to a low temperature so that even if fluorine reacts with silicon, it does not grow to voids. The device is designed to have the thickness of the silicon oxide film.

However, although the film formation temperature of the silicon oxide film is lowered by the above method, the fluorine remaining in the tungsten film is not reduced or removed. Therefore, it is difficult to eliminate the generation of voids due to residual fluorine.

It is not limited to the case where the silicon oxide film is formed on the upper layer of the tungsten film containing fluorine. In the method for manufacturing a semiconductor device having a structure in which the first layer and the second layer are laminated, when the first layer contains impurities that react with the material of the second layer to form a vaporizable substance, the above-mentioned Voids can be formed as well.

In the present embodiment, impurities (fluorine) remaining in the first layer (tungsten film) that causes voids (pinholes) are removed by annealing at a high temperature before film formation. After that, by forming a film of the second layer (silicon oxide film), the second layer (silicon oxide film) can be formed without generating voids.

An example of a method for manufacturing a semiconductor device according to the present embodiment and a film forming device that can be used for the method will be described below.

[First Embodiment]
[Film formation device]
First, an example of the film forming apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 5. The film forming apparatus according to the first embodiment of the present invention is a film forming apparatus to which the exhaust pipe detoxification method according to the first embodiment of the present invention can be suitably applied. Here, the film forming apparatus is a film forming apparatus using a so-called rotary table type (described later) susceptor, and by supplying a processing gas containing a raw material gas toward a predetermined supply region, a plurality of substrates can be formed. An example of a film forming apparatus for forming a film on a surface will be described. The susceptor on which the substrate is placed does not necessarily have to be a rotary table type, and can be applied to various film forming apparatus using a nozzle.

FIG. 1 is a cross-sectional view of the film forming apparatus, and shows a cross-sectional view taken along the line I-I'of FIG. 2 and 3 are views for explaining the structure in the processing chamber 1 (described later). In FIGS. 2 and 3, for convenience of explanation, the top plate 11 (described later) is not shown.

FIG. 4 is a cross-sectional view of the processing chamber 1 along the concentric circles of the susceptor 2 (described later) from the processing gas nozzle 31 (described later) to the processing gas nozzle 32 (described later). FIG. 5 is a partial cross-sectional view showing a region where the ceiling surface 44 (described later) is provided.

As shown in FIGS. 1 to 3, the film forming apparatus includes a flat processing chamber 1 having a substantially circular planar shape, a susceptor 2 provided in the processing chamber 1, and an operation of the entire film forming apparatus (for example, a processing gas nozzle). A control unit 100 (control means) for controlling the gas supply timings of 31 and 32) is provided.

The processing chamber 1 includes a container body 12 having a bottomed cylindrical shape, and a top plate 11 airtightly and detachably arranged on the upper surface of the container body 12. The top plate 11 is arranged so as to be airtightly removable via a seal member 13 (FIG. 1) such as an O-ring, and secures the airtightness in the processing chamber 1.

The susceptor 2 is fixed to the cylindrical core portion 21 housed in the case body 20 with the center of the processing chamber 1 as the center of rotation. The susceptor 2 has a mounting portion on the upper surface on which a plurality of substrates (hereinafter, referred to as “wafer W”) are mounted.

The case body 20 is a cylindrical case having an open upper surface. The case body 20 is airtightly attached to the lower surface of the bottom portion 14 of the processing chamber 1 with a flange portion provided on the upper surface thereof. The case body 20 isolates the internal atmosphere from the external atmosphere.

The core portion 21 is fixed to the upper end of the rotating shaft 22 extending in the vertical direction. The rotating shaft 22 penetrates the bottom 14 of the processing chamber 1. Further, the lower end of the rotating shaft 22 is attached to a drive unit 23 that rotates the rotating shaft 22 around a vertical axis. Further, the rotating shaft 22 and the driving unit 23 are housed in the case body 20.

As shown in FIG. 3, the surface of the susceptor 2 has a plurality of circular recesses 24 (mounted on a substrate) for mounting a plurality of (five wafers W in this embodiment) along the rotation direction (circumferential direction). It has a placement area). Here, in FIG. 3, for convenience, the wafer W is illustrated only in one recess 24. The susceptor 2 that can be used in the present invention may have a configuration in which four or less or six or more wafers W are placed as a plurality of substrates.

In the present embodiment, the recess 24 has an inner diameter slightly larger than the diameter of the wafer W (for example, 300 mm) (for example, an inner diameter 4 mm larger). Further, the recess 24 has a depth substantially equal to the thickness of the wafer W. As a result, when the wafer W is placed in the recess 24, the film forming apparatus can make the surface of the wafer W and the surface of the susceptor 2 (the region where the wafer W is not placed) substantially the same height.

In the film forming apparatus, the processing gas nozzle 31 is a first gas supply unit, and is arranged in a first processing region (described later) partitioned above the susceptor 2. The processing gas nozzle 31 is used as a raw material gas supply nozzle for supplying the raw material gas to the wafer W. The processing gas nozzle 32 is a second gas supply unit, and is used as a reaction gas supply nozzle that supplies a reaction capable of reacting with a raw material gas to produce a reaction product. The processing gas nozzle 32 is arranged in a second processing region (described later) separated from the first processing region along the circumferential direction of the susceptor 2. The separated gas nozzles 41 and 42 are separated gas supply units and are arranged between the first processing region and the second processing region (hereinafter, may be simply referred to as "gas nozzles 31, 32, 41, 42"). It will be.). As the gas nozzles 31, 32, 41, 42, for example, a nozzle made of quartz may be used.

Specifically, as shown in FIGS. 2 and 3, the film forming apparatus is spaced clockwise from the transport port 15 for transporting the substrate (rotational direction of the susceptor 2) at intervals in the circumferential direction of the processing chamber 1. The processing gas nozzle 32, the separation gas nozzle 41, the processing gas nozzle 31 and the separation gas nozzle 42 are arranged in this order. These nozzles 31, 32, 41 and 42 fix the gas introduction ports 31a, 32a, 41a and 42a (FIG. 3), which are the base ends thereof, to the outer peripheral wall of the container body 12. Further, the gas nozzles 31, 32, 41 and 42 are introduced into the processing chamber 1 from the outer peripheral wall of the processing chamber 1. Further, the gas nozzles 31, 32, 41 and 42 are attached so as to extend along the radial direction of the container body 12 toward the center of the susceptor 2 and parallel to the susceptor 2.

The gas nozzles 31 and 32 are provided with a plurality of gas discharge holes 33 (see FIG. 4) that open downward toward the susceptor 2. The gas nozzles 31 and 32 can be arranged with openings at intervals of, for example, 10 mm along the length direction of the nozzles. As a result, the lower region of the processing gas nozzle 31 becomes a region for adsorbing the raw material gas on the wafer W (hereinafter referred to as “first processing region P1”). Further, the lower region of the processing gas nozzle 32 is a region in which the reaction gas is reacted with the raw material gas adsorbed on the wafer W and the reaction product of the raw material gas and the reaction gas is deposited (hereinafter, “second processing region P2”. ".) Since the first processing region P1 is a region for supplying the raw material gas, it may be referred to as a “raw material gas supply region P1”, and the second processing region P2 is a region for supplying the reaction gas that reacts with the raw material gas. Therefore, it may be referred to as "reaction gas supply region P2".

As the raw material gas, for example, an organometallic gas used for forming a high-k film film may be used as the raw material gas, and for example, tri (dimethylamino) cyclopentadienyl may be used. A gas such as zirconium (C ₁₁ H ₂₃ N ₃ Zr) may be used. In addition, an organometallic gas obtained by evaporating an organometallic compound containing a metal such as aluminum, hafnium, titanium or a metalloid such as silane may be used as a raw material gas. Further, as the reaction gas, a reaction gas such as an oxidation gas (for example, O ₂ gas or O ₃ gas) and a nitride gas (for example, NH ₃ gas) may be used.

Generally, the organometallic compound used as a raw material gas for forming a High-k film is a compound containing an amine and contains an amino group (-NH ₂ , -NHR, -NRR'). For example, when an organometallic gas reacts with an oxidizing gas to oxidize, the amino group is desorbed and a harmful gas is generated. In the exhaust pipe detoxification method and the film forming apparatus according to the present embodiment, a treatment for sufficiently oxidizing the amino group to detoxify the harmful gas is performed, and this point will be described later. However, the raw material gas is not limited to the above-mentioned gas, and various gases may be used.

The processing gas nozzle 32 is arranged in the reaction gas supply region P2 partitioned above the upper surface of the susceptor 2, and supplies the reaction gas into the processing chamber 1 (second processing region P2) toward the upper surface of the susceptor 2. Is possible.

The separation gas nozzles 41 and 42 are provided between the first processing region P1 and the second processing region P2, which are provided apart from each other along the circumferential direction. The separated gas nozzles 41 and 42 are connected to the separated gas supply source via a pipe or the like (not shown). That is, the separation gas nozzles 41 and 42 supply the separation gas to the upper surface of the susceptor 2.

As the reaction gas, various reaction gases capable of reacting with the raw material gas may be used, and for example, a so-called oxidizing gas containing oxygen may be used. In the present embodiment, an example in which an oxidizing gas is used as the reaction gas will be described below. The oxidizing gas is, for example, oxygen gas, ozone gas or water vapor. That is, the raw material gas supplied from the processing gas nozzle 31 and adsorbed on the substrate is oxidized by the reaction gas supplied from the processing gas nozzle 32 to generate an oxide.

The film forming apparatus uses an inert gas as the separation gas. The inert gas is, for example, a rare gas such as Ar or He or a nitrogen gas. The separation gas is used as a purge gas for purging the wafer W. In the present embodiment, generally N ₂ gas used will be described as an example of using as a separation gas as a purge gas.

As shown in FIGS. 2 and 3, two convex portions 4 are provided in the processing chamber 1 of the film forming apparatus. The convex portion 4 has a substantially fan-shaped planar shape whose top is cut into an arc shape. In the present embodiment, the convex portion 4 has an inner arc connected to the protruding portion 5. Further, the convex portion 4 is arranged so that the outer arc is along the inner peripheral surface of the container main body 12 of the processing chamber 1.

Specifically, the convex portion 4 is attached to the back surface of the top plate 11 as shown in FIG. Further, the convex portion 4 has a flat low ceiling surface 44 (first ceiling surface) which is the lower surface thereof and ceiling surfaces 45 (second ceiling surface) located on both sides of the ceiling surface 44 in the circumferential direction. Have. Here, the ceiling surface 45 of the convex portion 4 is a ceiling surface higher than the ceiling surface 44. As a result, the convex portion 4 forms a separation space H, which is a narrow space, and a space 481 and a space 482 in which gas flows from the separation space H in the processing chamber 1. That is, the convex portion 4 causes the formed narrow space H to function as the separation region D shown in FIG. 2, which will be described later.

Further, as shown in FIG. 4, the convex portion 4 has a groove portion 43 in the center in the circumferential direction. The groove 43 extends along the radial direction of the susceptor 2. Further, the groove portion 43 accommodates the separation gas nozzle 42. A groove 43 is also formed in the other convex portion 4, and the separation gas nozzle 41 is housed therein.

A gas discharge hole 42h is formed on the lower surface of the separation gas nozzle 42, that is, on the surface facing the susceptor 2. A plurality of gas discharge holes 42h are formed at predetermined intervals (for example, 10 mm) along the longitudinal direction of the separation gas nozzle 42. The opening diameter of the gas discharge hole 42h is, for example, 0.3 to 1.0 mm. Although not shown, the separation gas nozzle 41 is also formed with a gas discharge hole 42h.

Further, as shown in FIG. 4, the film forming apparatus is provided with the processing gas nozzles 31 and 32 in the space below the high ceiling surface 45, respectively. These processing gas nozzles 31 and 32 are provided in the vicinity of the wafer W at a distance from the ceiling surface 45. As shown in FIG. 4, the processing gas nozzle 31 is provided in the space 481 (the space below the high ceiling surface 45), and the processing gas nozzle 32 is provided in the space 482 (the space below the high ceiling surface 45). There is.

The processing gas nozzles 31 and 32 are provided near the surface of the wafer W, and the discharge holes 33 are formed on the lower surfaces of the processing gas nozzles 31 and 32 so as to face the surface of the wafer W. The distance between the discharge holes 33 of the processing gas nozzles 31 and 32 and the surface of the susceptor 2 where the recess 24 is not formed is set, for example, in the range of 1 to 5 mm, preferably around 3 mm. Further, the processing gas nozzle 31 for supplying the raw material gas may be configured to have a rectangular cross-sectional shape as shown in FIG. The other processing gas nozzle 32 and the separated gas nozzles 41 and 42 have an annular cross-sectional shape.

The low ceiling surface 44 forms a separation space H, which is a narrow space, with respect to the susceptor 2. When the separation gas nozzle 42 inert gas (e.g. N ₂ gas) is supplied, the inert gas is to flow through the separation space H, flows toward the spaces 481 and 482. Here, since the volume of the separation space H is smaller than the volume of the spaces 481 and 482, the film forming apparatus compares the pressure of the spaces 481 and 482 with the pressure of the separation space H using the supplied inert gas. Can be high. That is, in the gap between the spaces 481 and 482, the separation space H forms a pressure barrier.

Further, the inert gas flowing out from the separation space H to the spaces 481 and 482 is the first treatment gas (raw material gas) in the first treatment region P1 and the second treatment gas (reaction) in the second treatment region P2. It works as a counterflow to gas). Therefore, the film forming apparatus uses the separation space H to separate the first processing gas in the first processing region P1 and the second processing gas in the second processing region P2. That is, the film forming apparatus suppresses the reaction of the first processing gas and the second processing gas in the processing chamber 1 in a mixed manner.

The height h1 of the ceiling surface 44 with respect to the upper surface of the susceptor 2, based on such supply of the pressure in the processing chamber 1 during the deposition, the susceptor 2 the rotational speed and / or for supplying the separation gas (N ₂ gas) Therefore, the pressure of the separation space H can be set to a height suitable for increasing the pressure of the spaces 481 and 482 as compared with the pressure of the spaces 481 and 482. Further, the height h1 of the ceiling surface 44 with respect to the upper surface of the susceptor 2 can be set to a height corresponding to the specifications of the film forming apparatus and the type of gas to be supplied. Further, the height h1 of the ceiling surface 44 with respect to the upper surface of the susceptor 2 can be a height determined in advance by experiments, calculations, or the like.

As shown in FIGS. 2 and 3, a protruding portion 5 is provided on the lower surface of the top plate 11 so as to surround the outer periphery of the core portion 21 for fixing the susceptor 2. In the present embodiment, the protruding portion 5 is continuous with the portion on the rotation center side of the convex portion 4, and the lower surface thereof is formed at the same height as the ceiling surface 44.

As shown in FIG. 2, the peripheral portion of the substantially fan-shaped convex portion 4 (the portion on the outer edge side of the processing chamber 1) is a bent portion 46 that bends in an L shape so as to face the outer end surface of the susceptor 2. Is formed. The bent portion 46 suppresses the flow of gas between the space 481 and the space 482 through the space between the susceptor 2 and the inner peripheral surface of the container body 12. The fan-shaped convex portion 4 is provided on the top plate 11.

Since the top plate 11 can be removed from the container body 12, the film forming apparatus has a slight gap between the outer peripheral surface of the bent portion 46 and the container body 12. The film forming apparatus sets the gap between the inner peripheral surface of the bent portion 46 and the outer end surface of the susceptor 2 and the gap between the outer peripheral surface of the bent portion 46 and the container body 12, for example, the height of the ceiling surface 44 with respect to the upper surface of the susceptor 2. Can be set to the same dimensions as.

Referring to FIG. 3 again, between the susceptor 2 and the inner peripheral surface of the container body, the first exhaust port 610 communicating with the space 481 (FIG. 4) and the second exhaust port 610 communicating with the space 482 (FIG. 4). An exhaust port 620 is formed. As shown in FIGS. 1 and 7, the first exhaust port 610 and the second exhaust port 620 are connected to the vacuum exhaust means 640, 641 (for example, a vacuum pump) via the exhaust pipes 630 and 631, respectively. .. The pressure regulators 650 and 651 are provided in the path of the exhaust pipes 630 and 631 to the vacuum exhaust means 640 and 641.

As shown in FIGS. 1 and 5, a heater unit 7 as a heating means is provided in the space between the susceptor 2 and the bottom 14 of the processing chamber 1. The wafer W on the susceptor 2 is heated to the temperature determined by the process recipe (for example, 450 ° C.) via the susceptor 2. A ring-shaped cover member 71 is provided on the lower side near the peripheral edge of the susceptor 2 in order to prevent gas from entering the space below the susceptor 2.

As shown in FIG. 2, the cover member 71 includes an inner member 71a provided so as to face the outer edge portion of the susceptor 2 and the outer peripheral side of the outer edge portion from the lower side, and the inner wall surface of the inner member 71a and the processing chamber 1. It is provided with an outer member 71b provided between the two. The outer member 71b is provided below the bent portion 46 formed on the outer edge portion of the convex portion 4 and in close proximity to the bent portion 46. The inner member 71a surrounds the heater unit 7 over the entire circumference below the outer edge portion of the susceptor 2 (and below the portion slightly outside the outer edge portion).

The raw material supply system for supplying the raw material gas to the processing gas nozzle 31 includes, for example, a vaporizer, a mass flow controller (mass flow controller), a pressure gauge, a mass flow meter (mass flow meter), and an automatic pressure controller. , Piping, valves, etc. are provided.

The control unit 100 shown in FIG. 1 is a means for instructing each configuration of the film forming apparatus to operate and controlling the operation of each configuration. In the film forming apparatus, the control unit 100 is composed of a computer for controlling the operation of the entire apparatus. The control unit 100 executes a program stored in the storage unit 101, for example, and cooperates with the hardware to form a film on the surface of a plurality of substrates. The control unit 100 can be configured by an arithmetic processing unit including a general CPU (Central Processing Unit) and a memory (for example, ROM, RAM).

Specifically, the control unit 100 can store a program for causing the film forming apparatus to carry out the film forming method described later in the built-in memory. This program is organized into steps, for example. The control unit 100 can read the program stored in the medium 102 (hard disk, compact disk, magneto-optical disk, memory card, flexible disk, etc.) into the storage unit 101 and then install it in the control unit 100. ..

[Semiconductor device]
FIG. 6 is a perspective sectional view showing an example of a semiconductor device that can be manufactured by the method for manufacturing a semiconductor device according to the present embodiment. FIG. 7 is an enlarged cross-sectional view of a part of the semiconductor device of FIG. 6 (a portion surrounded by a broken line 211). The semiconductor device according to this embodiment is a NAND flash memory in which memory cell transistors (memory cells) are integrated in three dimensions (3D).

A polysilicon semiconductor layer 201 having a channel region, a silicon oxide tunnel insulating film 202, a silicon nitride charge trap layer 203, and a silicon oxide block insulating film 204 are formed on the outer periphery of a substantially cylindrical silicon oxide embedded insulating film 200. It is laminated. The tunnel insulating film 202 may be a laminated insulating film of silicon oxide-silicon nitride-silicon oxide. A silicon oxide embedded insulating film 205 is formed on the outer periphery of the block insulating film 204. In the embedded insulating film 205, a trench T is formed in a region where a gate electrode of a memory transistor is formed. The inner wall of the trench T is covered with a trench-covered insulating film 206 made of high-dielectric-constant aluminum oxide and a barrier metal layer 207 of titanium nitride. A trench T is embedded on the barrier metal layer 207 to form a tungsten gate electrode 208.

A silicon oxide seal insulating film 209 is formed on the gate electrode 208, and the seal insulating film 209 is also formed on the barrier metal layer 207, the trench-coated insulating film 206, and the embedded insulating film 205. Further, a silicon oxide embedded insulating film 210 is formed on the seal insulating film 209.

A block insulating film 204, a charge trap layer 203, and a tunnel insulating film 202 are laminated between the semiconductor layer 201 and the gate electrode 208 to form a memory cell transistor having a MONOS (Metal-Oxide-Nitride-Oxide-Silicon) structure. ing.

By applying a predetermined voltage to the gate electrode 208 and the semiconductor layer 201, electrons are injected from the semiconductor layer 201 into the charge trap layer 203 through the tunnel insulating film. The charge trap layer 203 has sites such as defects capable of trapping charges inside, and traps the injected electrons. The threshold value of the transistor is different between the state in which electrons are injected into the charge trap layer 203 and the state in which electrons are not injected. With this threshold value, for example, 1-bit data corresponding to two values of "0" and "1" can be stored. Further, it is possible to store 2-bit data corresponding to four values by storing the data in four-step threshold values according to the number of injected electrons. Further, multi-valued data can be stored, such as storing 3-bit data corresponding to eight values by storing the data with eight threshold values. Further, by applying a predetermined voltage to the gate electrode 208 and the semiconductor layer 201, electrons are emitted to the semiconductor layer 201 in the charge trap layer 203. The charge trap layer 203 is in a state where no electrons are injected, and the threshold value of the transistor returns to the initial value. As described above, the transistor functions as a memory cell transistor for storing data. The semiconductor device of the present embodiment shown in FIG. 6 is a NAND type semiconductor storage device in which a large number of memory cell transistors are connected in series.

In the above semiconductor device, a silicon oxide sealing insulating film 209 is formed on a tungsten gate electrode 208. If the fluorine remaining in the gate electrode 208 is not reduced or removed, voids will be generated at the interface between the gate electrode 208 and the seal insulating film 209 (the region shown by the broken line 212 in FIG. 7) due to the remaining fluorine. ..

In the present embodiment, as described later, tungsten that causes voids (pinholes) is formed by raising the film formation temperature of the silicon oxide seal insulating film 209 at the time of film formation or by annealing at a high temperature before film formation. Fluorine remaining in the gate electrode of is removed. After that, by forming a film of the seal insulating film 209, the seal insulating film can be formed without generating voids.

The semiconductor device shown in FIGS. 6 and 7 is only an example of a semiconductor device that can be manufactured by applying the method for manufacturing a semiconductor device according to the present embodiment. The method for manufacturing a semiconductor device according to this embodiment can be applied to semiconductor devices having other structures.

[Manufacturing method of semiconductor device]
Next, a method for manufacturing a semiconductor device according to the first embodiment of the present invention will be described. 8 (A) to 8 (D) are cross-sectional views showing a manufacturing process of a method for manufacturing a semiconductor device according to the first embodiment of the present invention.

First, as shown in FIG. 8A, for example, by the CVD method or the ALD method in which the processing temperature using _{WF 6 as the raw material gas 222 is set as the first temperature, WF 6} + 3H ₂ → W + 6HF is formed on the substrate 220. A reaction occurs to form a tungsten (W) film 221 that serves as a gate electrode. The substrate 220 is, for example, an embedded insulating film 200, a semiconductor layer 201, a tunnel insulating film 202, a charge trap layer 203, a block insulating film 204, an embedded insulating film 205, and a trench-coated insulating film of the semiconductor device shown in FIGS. 6 and 7. It has 206 and a barrier metal layer 207. _{When the tungsten film 221 is formed by the CVD method or the ALD method using WF 6} gas as the raw material gas, fluorine (F) 223 remains as an impurity in the tungsten film 221.

_{It is also possible to form a tungsten film by a CVD method or an ALD method using WCl 6} as a raw material gas, and in this case, chlorine (Cl) remains as an impurity in the tungsten film 221. The film formation temperature (first temperature) of the tungsten film 221 by the CVD method or ALD method using WCl ₆ is preferably 400 ° C. or higher, and the pressure at the time of film formation is preferably 5 Torr or higher. This is because if the film forming temperature is lower than 400 ° C., the film forming reaction is unlikely to occur, and if the pressure is lower than 5 Torr, the etching reaction is likely to occur at 400 ° C. or higher. When the film forming temperature is 400 ° C., the film forming amount tends to be small at 5 Torr, but since a sufficient film forming amount can be obtained at 10 Torr or more, it is preferably 400 ° C. or higher and 10 Torr or more. Further, when the film forming temperature is 500 ° C., the film forming amount is further increased, and a sufficient film forming amount can be obtained even with 5 Torr. Therefore, it is preferable to set the film forming amount to 500 ° C. or higher and 5 Torr or higher.

Next, as shown in FIG. 8 (B), the heat treatment is performed at a second temperature higher than the first temperature described above, and the fluorine (F) 223, which is an impurity remaining in the tungsten film 221, is removed from the tungsten film 221. It accelerates the diffusion inside and removes it to the outside of the tungsten film 221. As a result, as shown in FIG. 8C, most of the fluorine 223 remaining in the tungsten film 221 is removed. When a tungsten film is formed by a CVD method or an ALD method using _{WCl 6} as a raw material gas, chlorine (Cl) remaining in the tungsten film 221 is removed.

As the second temperature, which is the temperature of the above heat treatment, the heat treatment at the second temperature accelerates the diffusion of fluorine 223, which is an impurity in the tungsten film 221, and sublimates the fluorine 223 from the surface of the tungsten film 221. Set to a temperature that allows. The second temperature is higher than the first temperature, which is the film formation temperature of the tungsten film. The first temperature is, for example, about 400 ° C., while the second temperature is preferably 620 ° C. or higher, more preferably 700 ° C. or higher. Fluorine in the tungsten film has a peak of sublimation amount at temperatures of 300 ° C., 620 ° C., and 700 ° C. as described later. From the examples described later, by performing the heat treatment at 620 ° C, not only the sublimation component having a peak at 620 ° C. but also the fluorine content of the sublimation component having a peak at 700 ° C. could be almost removed. Therefore, by performing the heat treatment at a second temperature of 620 ° C. or higher, almost all fluorine, which is an impurity in the tungsten film, can be removed. Fluorine can be further removed by performing a heat treatment at 700 ° C. or higher. The second temperature can be, for example, the film forming temperature of silicon oxide in the next step. The upper limit of the second temperature can be, for example, 1000 ° C.

The above heat treatment is preferably performed in an atmosphere that suppresses thermal oxidation of the tungsten film 221. This is to prevent or suppress the oxidation of the tungsten film 221 to generate tungsten oxide. For example, the reducing atmosphere by supplying hydrogen or the like, the atmosphere having a lower oxygen concentration than the step of forming the tungsten film 221, or the atmosphere having a lower oxygen concentration and the reducing atmosphere than the step of forming the tungsten film 221.

Next, as shown in FIG. 8D, the silicon oxide film 224 is formed on the upper layer of the tungsten film 221 by, for example, the CVD method or the ALD method. For example, using a silicon-containing gas such as silane as a raw material gas and an oxygen-containing gas such as oxygen (O ₂ ) and ozone (O ₃ ), silicon is thermally heated at a second temperature of, for example, 700 ° C. or higher. Is formed by oxidation.

Since the silicon oxide film 224 is formed after the fluorine 223 remaining in the tungsten film 221 is removed by heat treatment at the second temperature as described above, the fluorine and silicon at the interface between the silicon oxide film and the tungsten film are formed. The reaction is suppressed and almost disappears. As a result, the generation of voids (pinholes) is suppressed, and the silicon oxide film 224 can be formed with almost no generation. As a result, voids (pinholes) at the interface between the silicon oxide film / tungsten film can be eliminated, film peeling of the silicon oxide film can be prevented, and device deterioration can be suppressed by reducing pinholes. can.

It is preferable that the above heat treatment and the film forming process of the silicon oxide film are performed in the same processing device without being exposed to the atmosphere. This is to prevent or suppress the possibility that the tungsten film will be oxidized when exposed to the atmosphere.

For example, the above heat treatment and the film forming process of the silicon oxide film can be performed (in-situ) by using the above film forming apparatus shown in FIGS. 1 to 5. It is also possible to incorporate the heat treatment into the recipe for film formation treatment of the silicon oxide film. Further, it is also possible to perform the above heat treatment by using the period until the substrate is heated to a second temperature and stabilized at the second temperature in order to perform the film forming process.

Regardless of the method for forming the silicon oxide film 224 on the upper layer of the tungsten film 221, various film forming methods can be applied. For example, the method described in Patent Document 2 can be applied. That is, a tungsten film is formed on the substrate, an aminosilane gas is supplied while heating the substrate to form a seed layer on the tungsten film, and a silicon oxide film is formed on the seed layer. As a result, the incubation time can be shortened, oxidation of the underlying tungsten film can be prevented, and a silicon oxide film can be formed.

Further, as a step of forming the silicon oxide film 224 on the upper layer of the tungsten film 221, the method described in Patent Document 3 can be applied. That is, a substrate is installed in the processing chamber, hydrogen gas is supplied (preflow), and then oxidation gas and silicon-containing gas are supplied. As a result, it is possible to prevent the oxidation of the tungsten film and, if tungsten oxide is formed, reduce it to tungsten. In the above heat treatment step, when the hydrogen gas is supplied and the reduction atmosphere is performed as described above, the hydrogen gas supplied in the heat treatment step may be used as it is as the preflow of the hydrogen gas at the time of forming the silicon oxide film. can.

For example, using the above-mentioned film-forming apparatus shown in FIGS. 1 to 5, the above-mentioned heat treatment and the film-forming treatment of the silicon oxide film are performed as follows. First, the substrate 220 on which the tungsten film 221 is formed is carried into the processing chamber 1 of the film forming apparatus from the transport port 15. Next, the transport port 15 is closed to seal the processing chamber 1, and hydrogen gas is supplied into the processing chamber 1 by the hydrogen gas supply means of the film forming apparatus. The hydrogen gas supply means is provided separately from the gas nozzles 31, 32, 41, 42 like the gas nozzles 31, 32, 41, 42, or is also used as any of the gas nozzles 31, 32, 41, 42. While supplying hydrogen gas, the temperature of the susceptor 2 is set to the second temperature. After the susceptor reaches the second temperature, the heat treatment at the second temperature is performed for a predetermined time. Next, the supply of hydrogen gas is stopped, and the supply of oxygen-containing gas and silicon-containing gas is started. Here, the silicon-containing gas is supplied from the processing gas nozzle 31, and the oxygen-containing gas is supplied from the processing gas nozzle 32. The silicon oxide film 224 is formed on the upper layer of the tungsten film 221 of the substrate 220 at a second temperature higher than the first temperature which is the film forming temperature of the tungsten film. As the oxygen-containing gas, oxygen or ozone can be used. Examples of the silicon-containing gas, for example, 3DMAS (trisdimethylaminosilane _{Si (N (CH 3) 2} ) 3 H), 4DMAS ( tetrakis (dimethylamino) silane _{Si (N (CH 3) 2} ) 4) aminosilane such or, TCS (tetrachlorosilane SiCl ₄ ), DCS (dichlorosilane SiH ₂ Cl ₂ ), SiH ₄ (monosilane), HCD (hexachlorodisilane Si ₂ Cl ₆ ) and the like can be preferably used.

As described above, by raising the film formation temperature at the time of film formation of the silicon oxide film or annealing at a high temperature before film formation, fluorine remaining in the tungsten film that causes voids (pinholes) is removed. do. By subsequently forming a silicon oxide film, the silicon oxide film can be formed without generating voids.

In the above embodiment, when fluorine and chlorine remain as impurities in the tungsten film, the heat treatment removes the fluorine and chlorine to form a silicon oxide film, but the present invention is limited to this. is not it. In the method for manufacturing a semiconductor device having a structure in which the first layer and the second layer are laminated, when the first layer contains impurities that react with the material of the second layer to form a vaporizable substance, the above-mentioned Voids are formed in the same manner as above. That is, during the film formation of the second film, impurities in the first film and a substance that can be vaporized are formed from the material of the second film, and this is separated to generate voids at the interface between the first film and the second film. do. In the present embodiment, the first layer is formed on the substrate, and the first layer is heat-treated to remove impurities contained in the first layer. Next, a second layer containing a component that reacts with impurities to form a vaporizable substance is formed on the upper layer of the first layer. According to the present embodiment, even if the first layer contains impurities that react with the material of the second layer to form a vaporizable substance when the first layer and the second layer are laminated, the first layer is contained. It is possible to suppress the generation of voids at the interface between the first film and the second film. For example, it can be applied when the first layer contains fluorine, chlorine and the like as impurities, and a titanium nitride film is formed as the second layer on the upper layer. Further, it can be applied when the first layer contains fluorine and a ruthenium-containing layer is formed as the second layer.

[Manufacturing method of semiconductor device according to a comparative example]
Next, a method of manufacturing a semiconductor device according to a comparative example will be described. 9 (A) to 9 (D) are cross-sectional views showing a manufacturing process of a method for manufacturing a semiconductor device according to a comparative example.

First, as shown in FIG. 9A, for example, by the CVD method or the ALD method in which the processing temperature using _{WF 6 as the raw material gas 322 is set as the first temperature, WF 6} + 3H ₂ → W + 6HF is formed on the substrate 320. A reaction occurs to form a tungsten (W) film 321 as a gate electrode. The substrate 320 is, for example, an embedded insulating film 200, a semiconductor layer 201, a tunnel insulating film 202, a charge trap layer 203, a block insulating film 204, an embedded insulating film 205, and a trench-coated insulating film of the semiconductor device shown in FIGS. 6 and 7. It has 206 and a barrier metal layer 207. _{When the tungsten film 321 is formed by the CVD method or the ALD method using WF 6} gas as the raw material gas, fluorine (F) 323 remains as an impurity in the tungsten film 321.

Next, as shown in FIG. 9B, the silicon oxide film 324 is formed on the upper layer of the tungsten film 321 by, for example, the CVD method or the ALD method. For example, it is formed by using a silicon-containing gas such as silane and an oxygen-containing gas such as oxygen (O ₂ ) and ozone (O _{3) as a raw material gas.}

When the silicon oxide film 324 is formed with the fluorine 323 remaining as described above, as shown in FIG. 9C, the diffusion of the fluorine 323 in the tungsten film 321 starts due to the temperature applied in the subsequent step, and the silicon oxide is silicon oxide. Fluorine 323 is deposited at the interface between the film 324 and the tungsten film 321. Then, as shown in FIG. 9D, the precipitated fluorine 323 reacts with the silicon oxide film 324 to generate silicon fluoride 325. The silicon fluoride 325 has a vapor pressure that can be vaporized and is desorbed from the interface between the silicon oxide film 324 and the tungsten film 321. As a result, voids (pinholes) are generated. The silicon oxide film peels off, and the pinhole deteriorates the device.

On the other hand, according to the method for manufacturing a semiconductor device according to the present embodiment, the fluorine that causes voids is removed from the tungsten film by heat treatment before the film formation of the silicon oxide film, and then the silicon oxide film is formed. By forming a film, a silicon oxide film can be formed without generating voids.

〔Example〕
TDS (Thermal Desorption Spectroscopy) test The TDS test is a test in which a sample is irradiated with lamp light in a vacuum to raise the temperature by light absorption, and the desorbed gas from the sample is detected by a mass spectrometer. Is.

In this embodiment, a thermal oxide film is formed on a silicon substrate with a film thickness of 100 nm, titanium nitride is formed on the upper layer with a film thickness of 5 nm by the CVD method, and a tungsten film is formed on the upper layer with a film thickness of 15 nm by the CVD method. It was formed by the film thickness. As described above, a sample a as a comparative example was prepared. In CVD forming a tungsten film, WF ₆ is used as a raw material gas, and fluorine remains as an impurity in the tungsten film.

The sample a was heat-treated at 300 ° C. using the film forming apparatus shown in FIGS. 1 to 5 in the above embodiment to obtain a sample b. Further, the sample a was similarly heat-treated at 620 ° C. to obtain a sample c. The TDS test was performed on the above samples a, b, and c by gradually increasing the temperature. Here, the rate of temperature rise was 60 ° C./min, and the strength of the mass spectrometer corresponding to the amount of desorbed gas when the substrate temperature was raised from room temperature to 900 ° C. was measured.

FIG. 10 is a diagram showing the results of temperature-increasing desorption gas analysis according to this embodiment. The TDS test results for the samples a, b, and c are shown in FIG. 10 by the solid line a, the broken line b, and the alternate long and short dash line c. In FIG. 10, the horizontal axis is the substrate temperature (° C.), and the vertical axis is the intensity of the mass spectrometer (arbitrary unit, a.u.).

From the result of TDS of the sample a, it was confirmed that the fluorine in the tungsten film had a peak of sublimation amount at the temperatures of 300 ° C., 620 ° C. and 700 ° C.

From the result of TDS of the sample b, the sublimated fluorine having a peak at 300 ° C. could be removed by performing the heat treatment at 300 ° C. It seems that most of the fluorine in the sublimation with a peak at 620 ° C was removed, but the fluorine in the sublimation with a peak at 700 ° C remained almost.

From the results of TDS of sample c, it was confirmed that by performing the heat treatment at 620 ° C, not only the sublimation component having a peak at 620 ° C. but also the fluorine content of the sublimation component having a peak at 700 ° C. could be almost removed. .. Therefore, it was found that by performing the heat treatment at a second temperature of 620 ° C. or higher, most of the fluorine, which is an impurity in the tungsten film, can be removed.

[Second Embodiment]
Next, a method for manufacturing the film forming apparatus and the semiconductor apparatus according to the second embodiment of the present invention will be described.

[Film formation device]
FIG. 11 is a plan view showing an example of the film forming apparatus according to the second embodiment. The film forming apparatus according to the second embodiment shown in FIG. 11 is the same as that according to the first embodiment in that a processing gas nozzle 34 is added in addition to the processing gas nozzle 32 in the second processing region P2. It is different from the membrane device.

The processing gas nozzle 34 is a gas supply means for supplying the reducing gas to the wafer W. As the reducing gas, various gases may be used depending on the intended use as long as it is a gas capable of reducing the oxide. For example, a hydrogen atom-containing gas may be used as the reducing gas, or hydrogen (H ₂ ), ammonia (NH ₃ ), or the like may be used. When the second layer to be formed by the film forming process is an oxide film, for example, hydrogen gas is used as the reducing gas.

Like the processing gas nozzle 32, the processing gas nozzle 34 may be provided so as to extend from the inner peripheral surface of the container body 12 of the vacuum container 1 toward the center of the susceptor 2 in parallel with the surface of the susceptor 2. Further, the reducing gas may be introduced through the gas introduction port 34a provided on the outer peripheral wall of the container main body 12.

As described in the first embodiment, the processing gas nozzle 32 is supplied with a reaction gas capable of reacting with the raw material gas to produce a reaction product. When the second layer to be formed on the wafer W is an oxide film, an oxidizing gas such as oxygen is supplied from the processing gas nozzle 32. The oxidation gas may be supplied with oxygen radicals activated by thermal oxidation.

As described above, the film forming apparatus according to the second embodiment has a configuration in which the reducing gas and the reaction gas can be supplied independently. In FIG. 11, the reducing gas is supplied from the upstream side in the rotation direction of the susceptor 2, and the reaction gas is supplied from the downstream side in the rotation direction of the susceptor 2. However, even if this arrangement is reversed. good. Further, in FIG. 11, the processing gas nozzles 32 and 34 are arranged adjacent to each other, but the processing gas nozzles 32 and 34 do not necessarily have to be arranged adjacent to each other. However, when hydrogen and oxygen are mixed when forming an oxide film, OH * (hydroxyl radical) with high oxidizing power is generated. Therefore, if you want to strengthen the oxidizing power, treat it to a distance where hydroxyl radical can be generated. It is preferable to arrange the gas nozzles 32 and 34 close to each other.

Further, in FIG. 11, an example in which the reducing gas and reaction gas supply means are configured as the processing gas nozzles 32 and 34 is given, but these may be integrally configured as a shower head. As described above, the reducing gas supply means and the reaction gas supply means can have various configurations depending on the application.

Further, the control unit 100 is configured to be able to control the supply of the reducing gas from the processing gas nozzle 34. The control unit 100 can control the entire film forming apparatus and implement the method for manufacturing a semiconductor apparatus according to the second embodiment described later.

Since the other components have the same configuration as the film forming apparatus according to the first embodiment, the description thereof will be omitted.

[Manufacturing method of semiconductor devices]
Next, a method for manufacturing the semiconductor device according to the second embodiment will be described.

FIG. 12 is a sequence diagram showing an example of a method for manufacturing a semiconductor device according to the second embodiment. The method for manufacturing the semiconductor device according to the second embodiment will be described below with reference to an example carried out using the film forming apparatus according to the second embodiment shown in FIG.

Further, the first layer formed on the wafer W is a tungsten film, and an example of forming a _{silicon oxide film (SiO 2) as a second layer on the tungsten film will be described.} Further, an example in which hydrogen gas is used as the reducing gas and oxygen gas is used as the reaction gas will be described.

_{In the first embodiment, an example of forming a silicon oxide film (SiO 2} ) on the upper layer of the tungsten film of the first layer has been described, but it is necessary for the film formation of the silicon oxide film on the tungsten film. Due to the influence of the oxidizing agent (oxidizing gas), the underlying tungsten film is oxidized, which may cause a problem that the resistance value of the tungsten film increases and the conductivity decreases. The tungsten film is a film that is very easily oxidized, and in many cases, a natural oxide film is formed on the surface. That is, in many cases, the surface layer of the tungsten film has already been oxidized by the reaction with the atmospheric component. In such a case, there is a possibility that the high conductivity inherent in the tungsten film cannot be sufficiently exhibited only by suppressing the oxidation when forming the silicon oxide film.

Therefore, in the method for manufacturing a semiconductor device according to the second embodiment, a method for forming a silicon oxide film without newly oxidizing the tungsten film while removing the oxidizing component due to natural oxidation of the surface of the tungsten film was examined. .. Such a method for manufacturing a semiconductor device is very effective when the fluorine component described in the first embodiment is removed and then the oxidizing component is further removed. That is, both the impurities of the fluorine component and the impurities of the oxidizing component contained in the tungsten film can be removed, and the film can be further formed on the tungsten film while maintaining the performance of the high-quality tungsten film. Therefore, the method of manufacturing the semiconductor device according to the second embodiment will be described below.

First, as a premise, a step of removing impurities contained in the first layer by the heat treatment described in FIGS. 8A to 8C of the first embodiment is carried out.

Specifically, the tungsten film 221 formed on the surface of the substrate 220 is heat-treated to remove the fluorine 223 in the tungsten film 221. Since this content has already been explained in FIGS. 8A to 8C, detailed content will be omitted.

After performing the steps of removing impurities by the heat treatments of FIGS. 8A to 8C, the sequence shown in FIG. 12 is carried out.

In FIG. 12, the horizontal axis represents time. As shown in step S100 of FIG. 12, first, hydrogen is supplied to the substrate 220, and a hydrogen supply step (or reduction step) is carried out. Specifically, hydrogen gas is supplied as a reducing gas from the processing gas nozzle 34 provided in the second processing region P2. At this time, oxygen gas, which is an oxidation gas, is not supplied, and only hydrogen gas is supplied in the second processing region P2. Further, the raw material gas is not supplied even in the first processing region P1.

In this way, by rotating the susceptor 2 while supplying only hydrogen gas, a reducing atmosphere is formed in the second processing region P2, and the tungsten film 221 is reduced. That is, the oxidizing components such as the natural oxide film formed on the surface of the tungsten film 221 are removed by reduction.

In step S110, the supply of the raw material gas is started, and the raw material gas supply step is carried out. Specifically, the silicon-containing gas, which is a raw material gas, is supplied from the processing gas nozzle 31 of the first processing region P1. As the silicon-containing gas, various gases such as 3DMAS described in the first embodiment can be used. By supplying the silicon-containing gas to the tungsten film 221 from which the oxide on the surface layer of the tungsten film 221 has been removed, the silicon-containing gas is adsorbed on the surface layer of the tungsten film 221 to form a silicon layer for several atomic layers. That is, the surface of the tungsten film 221 is capped and covered with silicon, and the surface of the tungsten film 221 from which the oxide has been removed can be prevented from being oxidized again.

At this time, the supply of hydrogen in the second processing region P2 continues, and the state in which oxygen is not supplied is maintained. As a result, after the raw material gas is supplied to the substrate 220, the substrate 220 passes through the reducing atmosphere, so that the raw material gas is adsorbed in a state where oxidation of the substrate 220 is always prevented.

In step S120, the supply of the oxidizing agent is started, the silicon layer formed on the surface of the tungsten film 221 is oxidized, and the silicon oxide film layer is formed on the tungsten film 221. Specifically, oxygen gas is supplied from the processing gas 32 in the second processing region P2, and oxidation of the raw material gas is started. Since the silicon layer is formed with the oxide removed from the surface of the tungsten film 221 and the silicon oxide film is formed, there is no _{tungsten oxide film (WO x) that increases the resistance value of the tungsten film 221.} A silicon oxide film can be formed on the tungsten film 221.

After that, the rotation of the susceptor 2 is continued with the supply of hydrogen, silicon-containing gas, and oxygen gas, and the silicon oxide film (second layer 224) is formed by ALD.

In the hydrogen gas supply step (or reduction step) of step S100, the raw material gas supply step of step S110, and the oxygen gas supply step (or oxidation step) of step S120, all the substrates 220 on the susceptor 2 are at least once. , It is necessary to be exposed to hydrogen gas, raw material gas, and oxidation gas, but the number of rotations of the susceptor 2 in each step S100, S110, and S120 can be appropriately determined according to the application. That is, when sufficient reduction is required, the time of step S100 may be lengthened, and the time adjustment of each such step can be appropriately adjusted according to the intended use.

Further, in the second embodiment, for easy understanding, the first layer is a tungsten film 221 and the second layer 224 is a silicon oxide film, hydrogen gas is used as the reducing gas, oxygen gas is used as the reaction gas, and silicon is used as the raw material gas. Although the example using the contained gas has been described, various combinations of the oxidizing gas, the reducing gas and the like can be made depending on the application. For example, as described in the first embodiment, it is also applicable when the second layer is a titanium nitride film or a ruthenium-containing layer.

Further, in the second embodiment, the description has been made on the premise that the impurity removing step in the first embodiment is performed, but only steps S100 to S120 in FIG. 12 are executed without performing the fluorine removing step. It may be a sequence.

According to the method for manufacturing a semiconductor device according to the second embodiment, the thin film of the second layer is formed into the first layer in a state where the oxidizing component of the surface layer of the first layer is removed and the performance of the first layer is sufficiently exhibited. Can be formed on top.

Although the embodiment for carrying out the present invention has been described in detail above, the present invention is not limited to such a specific embodiment, and is within the scope of the gist of the present invention described in the claims. Various modifications and changes are possible.

It is not limited to NAND flash memory. For example, any semiconductor device having a tungsten film and a silicon oxide film formed on the tungsten film can be applied to any semiconductor device.

1 Processing chamber 2 Suceptor 4 Convex part 5 Protruding part 7 Heater unit 11 Top plate 12 Container body 13 Sealing member 14 Bottom 15 Transport port 20 Case body 21 Core part 22 Rotating shaft 23 Drive part 24 Recessed part 31 Processing gas nozzle 31a Gas introduction port 32 Processing gas nozzle 32a Gas introduction port 34 Processing gas nozzle 34a Gas introduction port 33 Discharge hole 41 Separation gas nozzle 41a Gas introduction port 42 Separation gas nozzle 42a Gas introduction port 42h Gas discharge hole 43 Groove 44 Ceiling surface 45 Ceiling surface 46 Bending portion 71 Cover member 71a Inner member 71b Outer member 100 Control unit 101 Storage unit 102 Medium 200 Embedded insulating film 201 Semiconductor layer 202 Tunnel insulating film 203 Charge trap layer 204 Block insulating film 205 Embedded insulating film 206 Trench-coated insulating film 207 Barrier metal layer 208 Gate electrode 209 Seal Insulating film 210 Embedded insulating film 220 Substrate 221 Tungsten (W) film 222 Raw material gas 223 Fluorine (F)
224 Silicon oxide film 481 Space 482 Space 610 First exhaust port 620 Second exhaust port 630, 631 Exhaust pipe 640, 641 Vacuum exhaust means 650, 651 Pressure regulator

Claims (16)

A step of heat-treating the first layer formed on the substrate to remove impurities contained in the first layer, and a step of removing impurities.
Wherein the upper layer of the first layer, have a step of forming a second layer containing a component vaporizable material reacts with the impurities is formed,
The first layer contains a component capable of forming an oxide film, and the first layer contains a component capable of forming an oxide film.
Between the step of removing the impurities and the step of forming the second layer, a step of supplying a reducing gas to the substrate to remove the oxidizing component contained in the first layer in a reducing atmosphere.
A step of supplying the raw material gas of the second layer to the first layer in the reducing atmosphere and forming an atomic layer of the raw material gas on the first layer.
After the step of forming the atomic layer of the raw material gas on the first layer, the oxidation gas is supplied to the atomic layer of the raw material gas formed on the first layer, and the raw material gas is oxidized to form the first layer. the method of manufacturing a semiconductor device that perforated forming an oxide film on the layer, the. In the step of removing impurities contained in the first layer, the heat treatment is applied to the first layer to accelerate the diffusion of the impurities contained in the first layer and sublimate the impurities from the first layer. The method for manufacturing a semiconductor device according to claim 1. The first layer is formed at the first temperature and is formed.
The method for manufacturing a semiconductor device according to claim 1 or 2, wherein the heat treatment is performed at a second temperature higher than the first temperature in the step of removing impurities. The method for manufacturing a semiconductor device according to claim 3, wherein the second temperature is 620 ° C. or higher. The method for manufacturing a semiconductor device according to claim 3, wherein the second temperature is 700 ° C. or higher. The impurities contain fluorine,
The component that reacts with the impurities to form a vaporizable substance contains silicon and contains silicon.
The method for manufacturing a semiconductor device according to any one of claims 1 to 4, wherein the vaporizable substance is silicon fluoride. The method for manufacturing a semiconductor device according to any one of claims 1 to 5, wherein the first layer contains tungsten. The method for manufacturing a semiconductor device according to any one of claims 1 to 7, wherein the heat treatment is performed in an atmosphere that suppresses thermal oxidation of the first layer in the step of removing impurities. In the step of removing the impurities, the heat treatment is performed in a reducing atmosphere, an atmosphere having a lower oxygen concentration than the step of forming the first layer, or a reducing atmosphere having a lower oxygen concentration than the step of forming the first layer. The method for manufacturing a semiconductor device according to claim 8. After the step of forming the atomic layer of the raw material gas on the first layer, the oxidation gas is supplied to the atomic layer of the raw material gas formed on the first layer, and the raw material gas is oxidized to form the first layer. the method of manufacturing a semiconductor device according to claim 1, further comprising a step of forming an oxide film on the layer, the. The first layer contains tungsten and is
The method for manufacturing a semiconductor device according to claim 10 , wherein the raw material gas is a silicon-containing gas. The reducing gas is hydrogen gas,
The method for manufacturing a semiconductor device according to any one of claims 1 to 11, wherein the oxidation gas is oxygen gas. A step of forming the atomic layer of the raw material gas on the first layer and a step of forming an oxide film on the first layer are performed once, and then the step of supplying the raw material gas to the substrate and the step of supplying the raw material gas to the substrate. The method for manufacturing a semiconductor device according to claim 12 , wherein the step of supplying the oxidation gas to the substrate is periodically repeated. The substrate is placed along the circumferential direction of a rotatable susceptor provided in the processing chamber.
On the susceptor, a raw material gas supply region capable of supplying the raw material gas to the substrate along the rotation direction of the susceptor, and a reduction / oxidation region capable of supplying the hydrogen gas and / or the oxygen gas to the substrate. Are provided apart from each other
In the step of removing the oxidizing component contained in the first layer, the susceptor is rotated while supplying the hydrogen gas without supplying the oxygen gas in the reducing / oxidizing region, and the reducing / oxidizing region is applied to the substrate. Is done by passing at least once,
In the step of forming the atomic layer of the raw material gas on the first layer, the substrate is passed through the reduction / oxidation region at least once, and then the substrate is supplied with the raw material gas in the raw material gas supply region. It is carried out by passing the raw material gas at least once.
In the step of oxidizing the raw material gas to form an oxide film on the first layer, the raw material gas is passed through the substrate at least once, and then the hydrogen gas and the oxygen gas are supplied in the reduction / oxidation region. The method for manufacturing a semiconductor device according to claim 13 , wherein the substrate is passed through the reduction / oxidation region. After the step of oxidizing the raw material gas to form an oxide film on the first layer, the raw material gas is supplied from the raw material gas supply region, and the hydrogen gas and the oxygen gas are supplied from the reduction / oxidation region. The method for manufacturing a semiconductor device according to claim 14 , wherein the step of rotating the susceptor a plurality of times to supply the raw material gas to the substrate and the step of supplying the hydrogen gas and the oxidation gas to the substrate are periodically repeated. .. Processing room and
A rotatable susceptor, which is installed in the processing chamber and allows the substrate to be placed along the circumferential direction.
A raw material gas supply region provided on the susceptor along the rotation direction of the susceptor and capable of supplying the raw material gas to the substrate, and a raw material gas supply region.
A reduction / oxidation region provided on the susceptor on the downstream side in the rotation direction of the susceptor so as to be separated from the raw material gas supply region and capable of supplying hydrogen gas and / or oxygen gas to the substrate.
With a heater that can heat the susceptor,
A control for executing a step of removing the impurities contained in the first layer by heating the susceptor with the heater after the substrate on which the first layer containing impurities is formed is placed on the susceptor. and parts, the possess,
After performing the step of removing the impurities, the control unit
A step of rotating the susceptor while supplying the hydrogen gas without supplying the oxygen gas in the reduction / oxidation region to reduce the first layer.
After the step of reducing the first layer, the supply of the raw material gas is started in the raw material gas supply region while the rotation of the susceptor and the supply of the hydrogen gas are continued, and the raw material gas is supplied onto the reduced first layer. The process of forming the atomic layer of the raw material gas and
After the step of forming the atomic layer of the raw material gas on the first layer, the oxygen gas is supplied in the reduction / oxidation region while the rotation of the susceptor, the supply of the hydrogen gas and the supply of the raw material gas are continued. A film forming apparatus for starting the process of oxidizing the atomic layer of the raw material gas on the first layer to form an oxide film.

Images