JP2012142367A - Method for manufacturing semiconductor device and substrate processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the crystal structure of at lease one part of a TiO film formed above a TiN film as a brookite-type structure or a rutile-type structure, and enhance the dielectric constant of the TiO film.SOLUTION: The crystal structure of at lease one part of a zirconium oxide film is made as a cubic structure or a tetragonal structure by controlling the film thickness of the zirconium oxide film. Thereby, the crystal structure of at lease one part of a titanium oxide film is made as a brookite-type structure or a rutile-type structure.

Description

  The present invention relates to a semiconductor device manufacturing method and a substrate processing apparatus.

  Some semiconductor devices such as DRAM (Dynamic Random Access Memory) have an MIM (Metal-Insulator-Metal) structure including a capacitor insulating film sandwiched between upper and lower electrode films. In order to increase the dielectric constant, for example, a titanium oxide (TiO) film is used as the capacitor insulating film. The TiO film is formed, for example, by supplying a titanium-containing gas and an oxygen-containing gas into a processing chamber in which a substrate is accommodated.

  The dielectric constant of the TiO film is increased by taking a crystal structure having a brookite structure or a rutile structure. However, for example, when a TiO film is formed using a titanium nitride (TiN) film as a lower electrode film as a base film, the TiO film may have a crystal structure having an anatase structure having a lower dielectric constant than a brookite structure or the like. there were.

  An object of the present invention is to provide a semiconductor device manufacturing method and a substrate capable of increasing the dielectric constant of a TiO film by making the crystal structure of at least a part of the TiO film formed on the TiN film into a brookite structure or a rutile structure. It is to provide a processing device.

  One embodiment of the present invention includes a zirconium oxide film forming step of forming a zirconium oxide film on a titanium nitride film formed on a substrate, and a titanium oxide film formation of forming a titanium oxide film on the zirconium oxide film And controlling the film thickness of the zirconium oxide film to change the crystal structure of at least a part of the zirconium oxide film into a cubic structure or a tetragonal structure, whereby the titanium oxide film This is a method for manufacturing a semiconductor device in which at least a part of the crystal structure is a brookite structure or a rutile structure.

In another aspect of the present invention, a processing chamber that houses a substrate on which a titanium nitride film is formed, a heating unit that heats the substrate, a zirconium-containing gas supply unit that supplies a zirconium-containing gas into the processing chamber, A titanium-containing gas supply unit that supplies a titanium-containing gas into the processing chamber; an oxygen-containing gas supply unit that supplies an oxygen-containing gas into the processing chamber; an exhaust unit that exhausts the atmosphere in the processing chamber; the heating unit; A control unit that controls the zirconium-containing gas supply unit, the titanium-containing gas supply unit, the oxygen-containing gas supply unit, and the exhaust unit, and the control unit includes zirconium in the processing chamber in which the substrate is accommodated. Supplying and exhausting the containing gas, supplying and exhausting the oxygen-containing gas into the processing chamber, supplying and exhausting the zirconium-containing gas and supplying and exhausting the oxygen-containing gas This cycle is repeated a predetermined number of times to form a zirconium oxide film on the titanium nitride film, and the zirconium oxide film is heated to change the crystal structure of at least a part of the zirconium oxide film. The titanium-containing gas is supplied and exhausted in the processing chamber, the oxygen-containing gas is supplied and exhausted in the processing chamber, and the supply and exhaust of the titanium-containing gas and the supply and exhaust of the oxygen-containing gas are performed in one cycle. By performing this cycle a predetermined number of times, a titanium oxide film is controlled to be formed on the phase-changed zirconium oxide film, and the zirconium oxide film is controlled by controlling the film thickness of the zirconium oxide film. The film is heated to change the crystal structure of at least a part of the zirconium oxide film to a cubic structure or a tetragonal structure. The phases were transferred to the system structure, thereby, at least a part of the crystal structure of the titanium oxide layer is a substrate processing apparatus configured to brookite structure or rutile structure.

  According to the present invention, at least a part of the crystal structure of the TiO film formed on the TiN film has a brookite structure or a rutile structure, and a semiconductor device manufacturing method and substrate capable of increasing the dielectric constant of the TiO film A processing device is obtained.

It is a perspective view of the substrate processing apparatus which concerns on one Embodiment of this invention. It is a block diagram of the process furnace which concerns on one Embodiment of this invention, Comprising: It is a figure which shows a process chamber part with sectional drawing especially. It is a block diagram of the processing furnace which concerns on one Embodiment of this invention, Comprising: It is AA sectional drawing of the processing furnace part of FIG. It is sectional drawing which shows the main structure part of the semiconductor device which concerns on one Embodiment of this invention. It is a flowchart which shows the manufacturing process of the main structure part of the semiconductor device which concerns on one Embodiment of this invention. It is a flowchart which illustrates the substrate processing process concerning one embodiment of the present invention. It is a gas supply timing diagram of the substrate processing process concerning one embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is drawing which shows the difference in the crystal structure per the same number of molecules of the capacitor insulating film which concerns on one Embodiment of this invention, Comprising: (a) is a schematic diagram which shows the crystal state of an anatase type structure, (b) is brookite It is a schematic diagram which shows the crystal state of a mold structure. It is a graph which shows the IV characteristic of the semiconductor device which concerns on the reference example of this invention. It is a graph which shows the measurement result of the X-ray diffraction of the capacitor insulating film which concerns on the Example of this invention. It is a graph which shows the measurement result of EOT of the capacitor insulating film based on the Example of this invention.

<One Embodiment of the Present Invention>
First, the configuration of a substrate processing apparatus according to an embodiment of the present invention will be described below.

(1) Overall Configuration of Substrate Processing Apparatus FIG. 1 is a perspective view of a substrate processing apparatus 101 according to this embodiment. As shown in FIG. 1, the substrate processing apparatus 101 according to the present embodiment includes a housing 111. In order to transport the wafer 200 as a substrate into and out of the casing 111, a cassette 110 as a wafer carrier (substrate storage container) that stores a plurality of wafers 200 is used. A cassette loading / unloading port (substrate storage container loading / unloading port, not shown), which is an opening for conveying the cassette 110 into and out of the housing 111, is provided on the front surface of the housing 111. A cassette stage (substrate storage container delivery table) 114 is provided inside the cassette loading / unloading casing 111. The cassette 110 is placed on the cassette stage 114 by an in-factory transport device (not shown), and is carried out of the casing 111 from the cassette stage 114.

  The cassette 110 is configured to be placed on the cassette stage 114 by a transfer device in the factory so that the wafer 200 in the cassette 110 is in a vertical posture and the wafer loading / unloading port of the cassette 110 faces upward. . The cassette stage 114 rotates the cassette 110 90 degrees toward the rear of the casing 111 to bring the wafer 200 in the cassette 110 into a horizontal posture, and directs the wafer loading / unloading port of the cassette 110 toward the rear in the casing 111. Is configured to be possible.

  A cassette shelf (substrate storage container mounting shelf) 105 is installed in a substantially central portion of the housing 111 as viewed in the front-rear direction. The cassette shelf 105 is configured to store a plurality of cassettes 110 in a plurality of rows and a plurality of rows. The cassette shelf 105 is provided with a transfer shelf 123 in which a cassette 110 to be transferred by a wafer transfer mechanism 125 described later is stored. In addition, a spare cassette shelf 107 is provided above the cassette stage 114 and is configured to store the spare cassette 110.

  A cassette transfer device (substrate container transfer device) 118 is provided between the cassette stage 114 and the cassette shelf 105. The cassette transport device 118 includes a cassette elevator (substrate storage container lifting mechanism) 118a that can be moved up and down while holding the cassette 110, and a cassette transport mechanism (substrate storage container transport mechanism) as a transport mechanism that can move horizontally while holding the cassette 110. 118b. The cassette 110 is transported between a predetermined position of the cassette shelf 105 excluding the cassette stage 114 and the transfer shelf 123, the spare cassette shelf 107, and the transfer shelf 123 by continuous operation of the cassette elevator 118a and the cassette transport mechanism 118b. It is configured as follows.

  A wafer transfer mechanism (substrate transfer mechanism) 125 is provided behind the cassette shelf 105. The wafer transfer mechanism 125 includes a wafer transfer device (substrate transfer device) 125a that can rotate or linearly move the wafer 200 in the horizontal direction, and a wafer transfer device elevator (substrate transfer device) that moves the wafer transfer device 125a up and down. Elevating mechanism) 125b. The wafer transfer device 125a includes a tweezer (substrate holder) 125c that holds the wafer 200 in a horizontal posture. By continuous operation of the wafer transfer device 125a and the wafer transfer device elevator 125b, the wafer 200 is picked up from the cassette 110 on the transfer shelf 123 and loaded into a boat (substrate holder) 217 described later (wafer charge). The wafer 200 is removed from the boat 217 (wafer discharge) and stored in the cassette 110 on the transfer shelf 123.

  A processing furnace 202 is provided above the rear portion of the casing 111. An opening is provided at the lower end of the processing furnace 202, and the opening is configured to be opened and closed by a furnace port shutter (furnace port opening / closing mechanism) 147. The configuration of the processing furnace 202 will be described later.

  Below the processing furnace 202, a transfer chamber 124, which is a space for loading and unloading the wafers 200 into and from the boat (substrate holder) 217 from the cassette 110 on the transfer shelf 123, is provided. In the transfer chamber 124, a boat elevator (substrate holder lifting mechanism) 115 is provided as a lifting mechanism that lifts and lowers the boat 217 into and out of the processing furnace 202. The elevator 128 of the boat elevator 115 is provided with an arm 128 as a connecting tool. On the arm 128, a seal cap 219 is provided in a horizontal posture as a furnace port lid body that supports the boat 217 vertically and that hermetically closes the lower end of the processing furnace 202 when the boat 217 is raised by the boat elevator 115. It has been.

  The boat 217 includes a plurality of holding members, and a plurality of (for example, about 50 to 150) wafers 200 are aligned in the vertical direction in a horizontal posture and in a state where the centers thereof are aligned in multiple stages. Configured to hold.

  Above the cassette shelf 105, a clean unit 134a having a supply fan and a dustproof filter is provided. The clean unit 134a is configured to circulate clean air, which is a cleaned atmosphere, inside the casing 111.

In addition, a clean unit (not shown) including a supply fan and a dustproof filter is installed on the opposite side of the wafer transfer device elevator 125b and the boat elevator 115 and on the left end of the housing 111 to supply clean air. Has been. The clean air blown from the clean unit is configured to be sucked into an exhaust device (not shown) and exhausted to the outside of the casing 111 after passing through the wafer transfer device 125a and the boat 217.

(2) Operation of Substrate Processing Apparatus Next, the operation of the substrate processing apparatus 101 according to the present embodiment will be described.

  First, the cassette 110 is loaded from a cassette loading / unloading port (not shown) by the in-factory transfer device, the wafer 200 is placed in a vertical posture, and the wafer loading / unloading port of the cassette 110 faces upward. Placed. Thereafter, the cassette 110 is rotated 90 ° toward the rear of the casing 111 by the cassette stage 114. As a result, the wafer 200 in the cassette 110 assumes a horizontal posture, and the wafer loading / unloading port of the cassette 110 faces rearward in the housing 111.

  Next, the cassette 110 is automatically transported to the designated shelf position of the cassette shelf 105 (excluding the transfer shelf 123) or the spare cassette shelf 107 by the cassette transport device 118, delivered, and temporarily stored. Then, the cassette is transferred from the cassette shelf 105 or the spare cassette shelf 107 to the transfer shelf 123 or directly transferred to the transfer shelf 123.

  When the cassette 110 is transferred to the transfer shelf 123, the wafer 200 is picked up from the cassette 110 through the wafer loading / unloading port by the tweezer 125c of the wafer transfer device 125a, and the wafer transfer device 125a and the wafer transfer device elevator 125b are picked up. Are loaded (wafer charged) into the boat 217 behind the transfer chamber 124. The wafer transfer mechanism 125 that has transferred the wafer 200 to the boat 217 returns to the cassette 110 and loads the next wafer 200 into the boat 217.

  When a predetermined number of wafers 200 are loaded into the boat 217, the furnace port shutter 147 that has closed the lower end of the processing furnace 202 is opened. Subsequently, as the seal cap 219 is raised by the boat elevator 115, the boat 217 holding the wafers 200 is loaded into the processing furnace 202 (boat loading). After boat loading, arbitrary processing is performed on the wafer 200 in the processing furnace 202. Such processing will be described later. After the processing, the wafer 200 and the cassette 110 are carried out of the casing 111 by a procedure reverse to the above procedure.

(3) Configuration of Processing Furnace Next, the configuration of the processing furnace 202 according to the present embodiment will be described with reference to FIG. 2 and FIG. FIG. 2 is a configuration diagram of the processing furnace 202 of the substrate processing apparatus 101 shown in FIG. 1, and particularly shows a processing chamber 201 portion in a sectional view. FIG. 3 is a cross-sectional view taken along line AA of the processing furnace 202 portion of FIG.

(Processing room)
The processing furnace 202 according to the present embodiment is configured as a batch type vertical hot wall type processing furnace based on, for example, an ALD (Atomic Layer Deposition) method. As shown in FIG. 2, the processing furnace 202 includes a reaction tube 203 and a manifold 209. The reaction tube 203 is made of a heat-resistant non-metallic material such as quartz (SiO ₂ ) or silicon carbide (SiC), and has a cylindrical shape with its upper end closed and its lower end open. The manifold 209 is made of, for example, a metal material such as SUS, and has a cylindrical shape with an upper end portion and a lower end portion opened. The reaction tube 203 is supported vertically by the manifold 209 from the lower end side. Lower end of reaction tube 203, manifold 209
An annular flange is provided at each of the upper and lower opening end portions of each. A sealing member 220 such as an O-ring is provided between the lower end of the reaction tube 203 and the flange at the upper end of the manifold 209, and the gap between the two is hermetically sealed.

  Inside the reaction tube 203 and the manifold 209, a processing chamber 201 for storing a plurality of stacked wafers 200 as substrates is formed. The boat 217 as the substrate holder is configured to be inserted into the processing chamber 201 from below by the boat elevator 115 as the substrate holder lifting mechanism described above.

  The boat 217 is configured to hold a plurality of (for example, about 50 to 150) wafers 200 in multiple stages with a predetermined gap (substrate pitch interval) in a substantially horizontal state. The maximum outer diameter of the boat 217 loaded with the wafers 200 is configured to be smaller than the inner diameters of the reaction tube 203 and the manifold 209. The boat 217 is mounted on the seal cap 219 via a boat support 218 as a holding body that holds the boat 217. The seal cap 219 is configured to contact the lower end of the manifold 209 from the lower side in the vertical direction. The seal cap 219 is made of a metal such as SUS and is formed in a disk shape. When the boat elevator 115 is raised, the sealing member 220 provided between the flange at the lower end of the manifold 209 and the seal cap 219 is configured to be hermetically sealed between the two. Since the space between the reaction tube 203 and the manifold 209 and the space between the manifold 209 and the seal cap 219 are hermetically sealed, the airtightness in the processing chamber 201 is maintained. Further, the boat 217 can be transported into and out of the processing chamber 201 by raising and lowering the seal cap 219 in the vertical direction by the boat elevator 115.

  A rotation mechanism 267 is provided below the seal cap 219. The rotation shaft 255 of the rotation mechanism 267 is connected to the boat 217 through the seal cap 219, and can rotate the boat 217 on which a plurality of wafers 200 are mounted while maintaining the airtightness in the processing chamber 201. It is configured to be able to. By rotating the boat 217, the processing uniformity of the wafers 200 can be improved.

  On the outer periphery of the reaction tube 203, a heater 207 as a heating unit is provided in a cylindrical shape concentric with the reaction tube 203, and the wafer 200 inserted into the processing chamber 201 is heated to a predetermined temperature. Has been. The heater 207 is vertically installed by being supported by a heater base 210 as a holding plate. The heater base 210 is fixed to the manifold 209.

  A temperature sensor 263 as a temperature detector is installed in the reaction tube 203, and by adjusting the power supply to the heater 207 based on the temperature information detected by the temperature sensor 263, The temperature is configured to have a desired temperature distribution. The temperature sensor 263 is configured in an L shape similarly to porous nozzles 270a, 270b, and 270c described later, and is provided along the inner wall of the reaction tube 203.

(Porous nozzle)
In the processing chamber 201, multi-hole nozzles 270a, 270b, and 270c that are provided in the processing chamber 201 along the stacking direction of the wafers 200 and have a plurality of gas supply ports 248a, 248b, and 248c, respectively, are disposed. . The perforated nozzles 270a, 270b, and 270c are each configured in an L shape having a vertical portion and a horizontal portion. The vertical portions of the multi-hole nozzles 270a, 270b, 270c are arranged in the vertical direction along the inner wall of the reaction tube 203, respectively. The horizontal portions of the perforated nozzles 270a, 270b, and 270c are provided so as to penetrate the side walls of the manifold 209, respectively.

  A plurality of gas supply ports 248a, 248b, and 248c are provided on the vertical side surfaces of the porous nozzles 270a, 270b, and 270c, respectively, so as to be arranged in the vertical direction. The gas supply ports 248a, 248b, 248c are configured to open between the stacked wafers 200, respectively. The gas supply ports 248a, 248b, and 248c are configured to face substantially the center in the processing chamber 201 (substantially the center of the wafer 200 loaded into the processing chamber 201), respectively, and the gas supply ports 248a, 248b, and 248c are configured. Are supplied so as to be injected toward the substantial center in the processing chamber 201. The opening diameters of the gas supply ports 248a, 248b, 248c may be the same from the lower part to the upper part, or may gradually increase from the lower part to the upper part.

(Oxygen-containing gas supply unit)
The downstream end of an oxygen-containing gas supply pipe 232a that supplies, for example, ozone (O ₃ ) gas as an oxygen (O) -containing gas is connected to the upstream end (horizontal end) of the porous nozzle 270a. The oxygen-containing gas supply pipe 232a is provided with an O ₃ gas supply source (not shown), a mass flow controller 241a that is a flow rate control mechanism, and a valve 252a that is an on-off valve in order from the upstream side. By opening the valve 252a, while the flow rates were controlled by the mass flow controller 241a, O ₃ and O ₃ gas into the processing chamber 201 from the gas supply source is configured to be supplied.

A downstream end of an inert gas supply pipe 234a for supplying an inert gas is further connected to the downstream side of the valve 252a of the oxygen-containing gas supply pipe 232a. The inert gas supply pipe 234a is provided with an inert gas supply source, a mass flow controller 243a, and a valve 254a (not shown) in order from the upstream side. By opening the valve 254a, the inert gas can be supplied into the processing chamber 201 from the inert gas supply source while the flow rate is controlled by the mass flow controller 243a. By supplying the inert gas, for example, after the supply of the O ₃ gas is completed, the inert gas is purged to remove the O ₃ gas remaining in the processing chamber 201, or other gas when the gas supply pipe 232a is not used. When the gas is supplied, the backflow of other gases can be prevented.

Oxygen that supplies O ₃ gas as an oxygen-containing gas into the processing chamber 201 mainly by an oxygen-containing gas supply pipe 232a, an O ₃ gas supply source, a mass flow controller 241a, a valve 252a, a porous nozzle 270a, and a gas supply port 248a A contained gas supply unit is configured.

  In addition, as shown in FIG. 3, the porous nozzle 270a is provided in the position which adjoins the porous nozzles 270b and 270c, for example. However, in FIG. 2, in order to show the detailed structure of the porous nozzle 270a and the like, for convenience, the oxygen-containing gas supply unit including the porous nozzle 270a is illustrated at a position on the right side of the drawing facing the porous nozzles 270b and 270c.

(Zirconium-containing gas supply unit)
The case where the zirconium (Zr) -containing gas is, for example, a TEMAZ gas obtained by vaporizing TEMAZ (tetrakisethylmethylaminozirconium: Zr (NEtMe) ₄ ) as a liquid raw material will be described. Since TEMAZ is a liquid at room temperature, in order to supply TEMAZ gas into the processing chamber 201, a method of supplying TEMAZ after heating and vaporizing it, helium (He) gas and neon (Ne) gas as carrier gases. A method of supplying an inert gas such as argon (Ar) gas or nitrogen (N ₂ ) gas into the liquid of TEMAZ and supplying the vaporized TEMAZ into the processing chamber 201 together with the carrier gas (bubbling method) )and so on. The following is a configuration when TEMAZ gas is supplied by a bubbling method using a carrier gas as an example.

  A downstream end of a Zr-containing gas supply pipe 233b for supplying a TEMAZ gas as a Zr-containing gas is connected to the upstream end (horizontal end) of the porous nozzle 270b. A carrier gas supply pipe 232b for supplying a carrier gas is provided on the further upstream side of the Zr-containing gas supply pipe 233b via a TEMAZ container 261b. A carrier gas supply source, a mass flow controller 241b, a valve 252b, and a TEMAZ container 261b (not shown) are provided in this order from the upstream side in the carrier gas supply pipe 232b. The TEMAZ liquid is stored in the TEMAZ container 261b, and the downstream end of the carrier gas supply pipe 232b is immersed in the TEMAZ liquid. The upstream end of the Zr-containing gas supply pipe 233b is disposed above the TEMAZ liquid level in the TEMAZ container 261b. A valve 253b is provided on the downstream side of the Zr-containing gas supply pipe 233b, and the downstream end of the Zr-containing gas supply pipe 233b is connected to the upstream end of the porous nozzle 270b as described above. The Zr-containing gas supply pipe 233b is provided with a heater 281b, and the Zr-containing gas supply pipe 233b is maintained at about 130 ° C., for example. By opening the valve 252b, the carrier gas is supplied from the carrier gas supply source into the TEMAZ container 261b while the flow rate is controlled by the mass flow controller 241b, so that the vaporized TEMAZ gas can be generated. Then, by opening the valve 253b, the TEMAZ gas vaporized in the TEMAZ container 261b can be supplied into the processing chamber 201 together with the carrier gas.

  A downstream end of an inert gas supply pipe 234b for supplying an inert gas is further connected to the downstream side of the valve 253b of the Zr-containing gas supply pipe 233b. The inert gas supply pipe 234b is provided with an inert gas supply source, a mass flow controller 243b, and a valve 254b (not shown) in order from the upstream side. By opening the valve 254b, the inert gas can be supplied into the processing chamber 201 from the inert gas supply source while the flow rate is controlled by the mass flow controller 243b.

  Mainly in the processing chamber 201 by the carrier gas supply pipe 232b, the carrier gas supply source, the mass flow controller 241b, the valve 252b, the TEMAZ container 261b, the Zr-containing gas supply pipe 233b, the valve 253b, the porous nozzle 270b, and the gas supply port 248b. A Zr-containing gas supply unit that supplies TEMAZ gas as the Zr-containing gas is configured.

(Titanium-containing gas supply unit)
The case where the titanium (Ti) -containing gas is TiCl ₄ gas obtained by vaporizing, for example, tetrachlorotitanium (TiCl ₄ ) as a liquid raw material will be described. Since TiCl ₄ is a liquid at room temperature, a configuration in the case of supplying TiCl ₄ gas by a bubbling method using a carrier gas will be described as an example here as in the case of TEMAZ.

A downstream end of a Ti-containing gas supply pipe 233c that supplies TiCl ₄ gas as a Ti-containing gas is connected to the upstream end (horizontal end) of the porous nozzle 270c. A carrier gas supply pipe 232c for supplying a carrier gas is provided on the further upstream side of the Ti-containing gas supply pipe 233c via a TiCl ₄ container 261c. The carrier gas supply pipe 232c is provided with a carrier gas supply source (not shown), a mass flow controller 241c, a valve 252c, and a TiCl ₄ container 261c in order from the upstream side. The TiCl ₄ container 261c are stored liquids TiCl _4, the downstream end of the carrier gas supply pipe 232c is immersed in liquid TiCl _4. Then, the upstream end of the Ti-containing gas supply pipe 233c is disposed above the liquid surface of TiCl ₄ in the TiCl ₄ container 261 c. A valve 253c is provided on the downstream side of the Ti-containing gas supply pipe 233c, and the downstream end of the Ti-containing gas supply pipe 233c is connected to the upstream end of the porous nozzle 270c as described above. The Ti-containing gas supply pipe 233c is provided with a heater 281c, and the Ti-containing gas supply pipe 233c is maintained at about 40 ° C., for example. By opening the valve 252c, the carrier gas is supplied from the carrier gas supply source into the TiCl ₄ container 261c while controlling the flow rate by the mass flow controller 241c.
It is configured so that a vaporized gas of iCl ₄ can be generated. By opening the valve 253c, the TiCl ₄ gas vaporized in the TiCl ₄ container 261c can be supplied into the processing chamber 201 together with the carrier gas.

  A downstream end of an inert gas supply pipe 234c for supplying an inert gas is further connected to the downstream side of the valve 253c of the Ti-containing gas supply pipe 233c. The inert gas supply pipe 234c is provided with an inert gas supply source, a mass flow controller 243c, and a valve 254c (not shown) in order from the upstream side. By opening the valve 254c, the inert gas can be supplied into the processing chamber 201 from the inert gas supply source while the flow rate is controlled by the mass flow controller 243c.

Mainly, in the processing chamber 201, a carrier gas supply pipe 232c, a carrier gas supply source, a mass flow controller 241c, a valve 252c, a TiCl ₄ container 261c, a Ti-containing gas supply pipe 233c, a valve 253c, a porous nozzle 270c, and a gas supply port 248c. A Ti-containing gas supply unit that supplies TiCl ₄ gas as a Ti-containing gas is configured.

(Exhaust part)
An exhaust pipe 231 is connected to the side wall of the manifold 209. The exhaust pipe 231 includes a pressure sensor 245 as a pressure detector (pressure detector) for detecting the pressure in the processing chamber 201 in order from the upstream side, an APC (Auto Pressure Controller) valve 251 as a pressure regulator, and a vacuum exhaust device. A vacuum pump 246 is provided. The APC valve 251 is an on-off valve that can be evacuated and stopped by opening and closing the valve and that can further adjust the opening of the valve. By adjusting the opening degree of the opening / closing valve of the APC valve 251 while operating the vacuum pump 246, the inside of the processing chamber 201 can be set to a desired pressure.

  The exhaust pipe 231, the pressure sensor 245, the APC valve 251, and the vacuum pump 246 mainly constitute an exhaust unit that exhausts the atmosphere in the processing chamber 201.

  As shown in FIG. 3, the exhaust pipe 231 is provided, for example, at a position close to the porous nozzle 270c. However, in FIG. 2, in order to show the detailed structure of the exhaust pipe 231 and the like, for convenience, the exhaust part including the exhaust pipe 231 is illustrated at a position on the right side of the drawing facing the porous nozzles 270b and 270c.

(Control part)
The controller 280 serving as a control unit includes mass flow controllers 241a, 241b, 241c, 243a, 243b, 243c, APC valves 251, valves 252a, 252b, 252c, 253b, 253c, 254a, 254b, 254c, temperature sensors 263, heaters 207, The pressure sensor 245, the vacuum pump 246, the rotation mechanism 267, the boat elevator 115, etc. are connected. The controller 280 adjusts the flow rate of the mass flow controllers 241a, 241b, 241c, 243a, 243b, 243c, the opening / closing operation of the APC valve 251, valves 252a, 252b, 252c, 253b, 253c, 254a, 254b, 254c, Pressure adjustment operation, temperature detection operation of the temperature sensor 263, temperature adjustment operation of the heater 207, pressure detection operation of the pressure sensor 245, start / stop of the vacuum pump 246, rotation speed adjustment of the rotation mechanism 267, and lifting / lowering operation of the boat elevator 115 Control is performed.

(4) Manufacturing Method of Semiconductor Device Next, the substrate processing process according to this embodiment will be described. The substrate processing process according to the present embodiment is performed as one process of manufacturing a semiconductor device such as a DRAM having a capacitor having an MIM structure, for example. FIG. 4 shows main structural portions of the semiconductor device 1 according to the present embodiment. The main structure of the semiconductor device 1 is formed of a lower electrode film 310 made of a titanium nitride (TiN) film and a zirconium oxide (ZrO) film on a wafer 200 made of, for example, silicon (Si) according to the process shown in FIG. A seed barrier film 320, a capacitor insulating film 330 made of a titanium oxide (TiO) film, and an upper electrode film 340 made of a gold (Au) film are laminated in this order, and dry etching or the like using a predetermined resist pattern (not shown) as a mask. Each film is formed by etching.

  Application of the high dielectric constant insulating film such as a TiO film of the semiconductor device 1 to a capacitor insulating film in a DRAM having a half pitch of 40 nm or more is being studied. In place of the HfO film and the ZrO film that have been used in the DRAM having a half pitch of about 50 nm, for example, a TiO film is used, so that the dielectric constant of the capacitor insulating film is increased and an equivalent oxide film thickness (EOT: Equivalent Oxide Thickness) is increased. It becomes possible to reduce.

  When the TiO film is applied to the capacitor insulating film, there are problems in controlling the crystal structure of the TiO film that affects the dielectric constant and reducing the leakage current density of the TiO film having a small band gap. In this embodiment, in order to solve the above-described problem, a ZrO film having a predetermined crystal structure that becomes a seed film (seed film) of a crystal structure of a TiO film and also serves as a leakage current prevention film (barrier film) is used as a seed barrier film. Form as. Hereinafter, each process according to the present embodiment will be described in detail.

[Lower electrode film formation process]
First, prior to the substrate processing step in the processing furnace 202, a TiN film as a lower electrode film is formed on the wafer 200 made of Si in a processing furnace different from the processing furnace 202 according to the present embodiment. At this time, the TiN film is formed as a crystalline film having a non-rutile structure, for example.

[Substrate processing step by the processing furnace 202]
Subsequently, as a substrate processing step performed by the processing furnace 202 according to the present embodiment, for example, film formation using an ALD method will be described. For example, in the case of the conventional CVD (Chemical Vapor Deposition) method, a plurality of types of gases including a plurality of elements constituting the film to be formed are simultaneously supplied to the substrate, and in the case of the ALD method, a plurality of gases constituting the film to be formed are supplied. A plurality of types of gas containing these elements are alternately supplied to the substrate. Then, a silicon oxide (SiO) film or a silicon nitride (SiN) film is controlled by controlling film supply conditions such as a supply flow rate at the time of gas supply, a supply time, a temperature in the processing chamber 201, and plasma power in the case of a plasma system. Etc. For example, in the formation of the SiO film, the film formation conditions are controlled so that the composition ratio of the film becomes O / Si≈2 which is the stoichiometric composition. In the formation of the SiN film, the film formation conditions are controlled so that the composition ratio of the film is N / Si≈1.33 which is the stoichiometric composition.

  Alternatively, the film formation conditions can be controlled so that the composition ratio of the film to be formed becomes a predetermined composition ratio different from the stoichiometric composition. That is, the film formation conditions are controlled so that at least one element out of a plurality of elements constituting the film to be formed becomes excessive with respect to the stoichiometric composition than the other elements. As described above, film formation can be performed while controlling the ratio of a plurality of elements constituting the film to be formed, that is, the composition ratio of the film.

  As described above, in the ALD method, a gas containing an element constituting a desired film is alternately supplied to the substrate one by one and adsorbed on the substrate in units of one atomic layer to form a film by surface reaction. For example, in the case of a SiO film, the process of supplying each of a silicon (Si) -containing gas and an oxygen (O) -containing gas is one cycle, and if the deposition rate is 0.1 nm / cycle, 20 cycles are performed A 2 nm SiO film can be formed.

Hereinafter, an example of a sequence for forming a film having a stoichiometric composition as a main composition by alternately supplying a plurality of types of gases containing different types of elements to the substrate by the ALD method will be described. The stoichiometric composition of the ZrO film according to this embodiment is O / Zr≈2, and the ZrO film to be formed below is a zirconium oxide film having an arbitrary composition ratio including ZrO ₂ . The stoichiometric composition of the TiO film according to this embodiment is O / Ti≈2, and the TiO film formed below is a titanium oxide film having an arbitrary composition ratio including TiO ₂ .

  FIG. 6 is a flowchart of a substrate processing process performed by the processing furnace 202. FIG. 7 is a timing chart illustrating each gas supply timing when the supply of each gas according to this embodiment is alternately repeated. In the following description, the operation of each part constituting the processing furnace 202 shown in FIG. 2 is controlled by the controller 280.

(Substrate carrying-in process S10)
First, a plurality of wafers 200 on which TiN films are formed are loaded into the boat 217 (wafer charge). Then, the boat 217 holding the plurality of wafers 200 is lifted by the boat elevator 115 and loaded into the processing chamber 201 (boat loading). In this state, the seal cap 219 is in a state of hermetically sealing the lower end of the manifold 209 via the sealing member 220. In the substrate carry-in step S10, it is preferable that the valves 254a, 254b, and 254c are opened and an inert gas as a purge gas such as N ₂ gas is continuously supplied into the processing chamber 201.

(Decompression step S20, temperature raising step S30)
Subsequently, the valves 254a, 254b, and 254c are closed, and the inside of the processing chamber 201 is exhausted by the vacuum pump 246. In addition, the temperature in the processing chamber 201 is controlled by the heater 207 so that the wafer 200 has a desired temperature, specifically, a range of 150 ° C. to 350 ° C., for example, 250 ° C. At this time, feedback control of the power supply to the heater 207 is performed based on the temperature information detected by the temperature sensor 263 so that the processing chamber 201 has a desired temperature distribution. Then, the boat 217 is rotated by the rotation mechanism 267, and the rotation of the wafer 200 is started.

  In parallel with the substrate loading step S10 to the temperature raising step S30, a TEMAZ gas as a Zr-containing gas obtained by vaporizing TEMAZ as a liquid raw material is generated (preliminary vaporization). That is, by opening the valve 252b with the valve 253b closed, the carrier gas is supplied into the TEMAZ container 261b from a carrier gas supply source (not shown) while controlling the flow rate by the mass flow controller 241b, and the TEMAZ gas is vaporized in advance. Keep it. When the TEMAZ gas is not used, the vaporized TEMAZ gas is exhausted by bypassing the processing chamber 201 with an exhaust pipe (not shown), for example.

At this time, it keeps the TiCl ₄ gas as Ti-containing gas obtained by vaporizing the TiCl ₄ as the liquid raw material to generate (preliminary vaporization). That is, by opening the valve 252c with the valve 253c closed, the carrier gas is supplied into the TiCl ₄ container 261c from a carrier gas supply source (not shown) while controlling the flow rate by the mass flow controller 241c, and the TiCl ₄ gas is preliminarily supplied. Let it evaporate. When the TiCl ₄ gas is not used, the vaporized TiCl ₄ gas is exhausted by bypassing the processing chamber 201 with an exhaust pipe (not shown), for example.

In order to supply the TEMAZ gas and the TiCl ₄ gas in a stable state by the bubbling method, a predetermined time is required for gas vaporization. Prior to the start of gas supply to be described later, the TEMAZ gas or TiCl ₄ gas can be vaporized in advance as described above to ensure a stable supply state.

(Zirconium oxide film forming step S40)
In forming a TiO film as a capacitor insulating film, which will be described later, the crystal structure of the base film of the TiO film can affect the crystal structure of the TiO film. That is, when a TiO film is directly formed on the lower electrode film, what the lower electrode film is has an influence on the crystal structure of the TiO film. For example, when a ruthenium (Ru) film having a rutile crystal structure is used as a base film, a rutile TiO film having a high dielectric constant is easily obtained. However, for example, when a TiN film is used as a base film, the TiO film formed thereon is an anatase type (dielectric constant: 114) or an anatase type (dielectric constant: 78) having a lower dielectric constant than a rutile type (relative dielectric constant: 78). Dielectric constant: 48).

  Therefore, in this embodiment, a ZrO film as a seed barrier film is formed on the TiN film as a base film for the TiO film. That is, S41 to S44 of FIG. 6 described later is one cycle, and this cycle is performed a predetermined number of times (S45), thereby forming a ZrO film having a predetermined thickness on the TiN film. At this time, the ZrO film is formed as an amorphous film, for example. Thereafter, in the phase transition step S46, at least a part of the crystal structure of the ZrO film is phase-transformed into a cubic structure or a tetragonal structure.

  In this way, the TiO film is not formed directly on the TiN film, but a ZrO film having at least a part of a cubic or tetragonal crystal structure is used as a base film, and a TiO film is formed therethrough. As a result, the influence of the TiN film can be suppressed, the crystal structure of at least a part of the TiO film can be changed to a brookite structure or a rutile structure, and the dielectric constant of the TiO film can be increased. Further, the leakage current density can be reduced by the ZrO film. Hereinafter, the zirconium-containing gas supply step S41 to the phase transition step S46 will be described in detail.

(Zirconium-containing gas supply step S41)
In the zirconium-containing gas supply step S41, a TEMAZ gas as a Zr-containing gas is flowed into the processing chamber 201, and TEMAZ molecules and the like are adsorbed on the TiN film. Specifically, the TEMAZ gas vaporized in the TEMAZ container 261b is supplied into the processing chamber 201 together with the carrier gas by opening the valve 253b. At this time, the opening degree of the APC valve 251 is adjusted to maintain the pressure in the processing chamber 201 within a range of 30 Pa to 500 Pa, for example, 100 Pa. The flow rate of the carrier gas supplied together with the TEMAZ gas is, for example, 5 slm. The supply time of the TEMAZ gas (and carrier gas) is, for example, in the range of 1 second to 360 seconds. When the predetermined time has elapsed, the valve 253b is closed and the supply of the TEMAZ gas is stopped.

  During the supply of the Zr-containing gas, the inert gas supply pipe 234a connected to the oxygen-containing gas supply pipe 232a and the valves 254a and 254c of the inert gas supply pipe 234c connected to the Ti-containing gas supply pipe 233c are performed. Opening and flowing an inert gas can prevent the TEMAZ gas from entering the oxygen-containing gas supply pipe 232a and the Ti-containing gas supply pipe 233c.

At this time, the gas flowing into the processing chamber 201 is only an inert gas such as TEMAZ gas and N ₂ gas, and there is no oxygen-containing gas such as O ₃ gas. Therefore, the TEMAZ gas causes chemical adsorption (surface reaction) with the surface portion of the TiN film on the wafer 200 without causing a gas phase reaction to form an adsorption layer or a Zr layer of TEMAZ molecules. The adsorption layer of TEMAZ molecules includes a discontinuous adsorption layer as well as a continuous adsorption layer of TEMAZ molecules. The Zr layer includes not only a continuous layer composed of Zr but also a Zr thin film formed by overlapping these layers. In the following, all of these are also referred to as Zr-containing layers.

(Exhaust process S42)
After the valves 252b and 253b are closed and the supply of the TEMAZ gas into the processing chamber 201 is stopped, the APC valve 251 is opened to exhaust the atmosphere in the processing chamber 201, and the remaining vaporized TEMAZ gas and reaction generation Exclude things. At this time, if an inert gas such as N ₂ is supplied into the processing chamber 201 from the inert gas supply pipes 234a, 234b, and 234c and purged, the effect of removing the residual gas from the processing chamber 201 can be further enhanced. it can. After a predetermined time has elapsed, the valves 234a, 234b, 234c are closed, and the exhaust process S42 is completed.

(Oxygen-containing gas supply step S43)
In the oxygen-containing gas supply step S43, an O ₃ gas as an oxygen-containing gas is flowed into the processing chamber 201 to form a ZrO layer on the TiN film. Specifically, by opening the valve 252a, while the flow rates were controlled by the mass flow controller 241a, supplying the _{O 3} gas into the processing chamber 201 from the _{O 3} gas supply source (not shown). At this time, the opening degree of the APC valve 251 is adjusted to maintain the pressure in the processing chamber 201 within a range of 30 Pa to 500 Pa, for example, 130 Pa. Further, the concentration of O ₃ gas is set to 250 g / m ³ , for example, and the flow rate of O ₃ gas is set to 15 slm, for example. The supply time of the O ₃ gas is set to 120 seconds, for example. When the predetermined time has elapsed, the valve 252a is closed and the supply of O ₃ gas is stopped.

Note that when the ZrO film is initially formed, specifically, when ZrO is a layer having a thickness of about 0.5 nm to 2 nm, the underlying TiN film is prevented from being oxidized by setting the O ₃ gas to a relatively low concentration. be able to. On the other hand, when the ZrO layer being formed has a thickness that can sufficiently suppress the oxidation of the TiN film, increasing the concentration of O ₃ gas can reduce impurities in the formed ZrO film and improve the film quality. Can be made. Specifically, the O ₃ gas is set to 200 g / N · m ³ or less at the initial stage of the formation of the ZrO film, and thereafter 200 g / N · m ³ or more.

Further, while supplying the oxygen-containing gas, the inert gas supply pipe 234b connected to the Zr-containing gas supply pipe 233b and the valves 254b and 254c of the inert gas supply pipe 234c connected to the Ti-containing gas supply pipe 233c are provided. Opening and flowing an inert gas can prevent O ₃ gas from flowing into the Zr-containing gas supply pipe 233b and the Ti-containing gas supply pipe 233c.

By supplying the O ₃ gas in this way, the Zr-containing layer adsorbed on the TiN film is oxidized, and a ZrO thin film of less than one atomic layer to several atomic layers is formed on the TiN film.

(Exhaust process S44)
After the valve 252a is closed and the supply of O ₃ gas into the processing chamber 201 is stopped, the APC valve 251 is opened to evacuate the atmosphere in the processing chamber 201, and the remaining O ₃ gas and the like are removed. At this time, if an inert gas such as N ₂ is supplied into the processing chamber 201 from the inert gas supply pipes 234a, 234b, and 234c and purged, the effect of removing the residual gas from the processing chamber 201 can be further enhanced. it can.

(Predetermined number of execution steps S45)
The S41 to S44 are set as one cycle, and this cycle is performed a predetermined number of times to form a ZrO film having a predetermined thickness on the TiN film. FIG. 7 shows an example in which the above cycle is performed m times. In FIG. 7, the horizontal axis indicates the elapsed time, and the vertical axis indicates the supply timing of each gas. The thickness of the ZrO film to be formed can be controlled by arbitrarily changing the number of cycles (the value of m).

Note that the thickness of the ZrO film is, for example, 4 nm or more. Thus, by controlling the film thickness of the ZrO film to be equal to or larger than the predetermined film thickness, at least a part of the crystal structure of the ZrO film is changed to a cubic structure or a tetragonal structure in a phase transition step S46 described later. Thus, the phase transition can be more reliably performed. As a result, the TiO film formed on the ZrO film can have a predetermined crystal structure, and the dielectric constant can be increased and EOT can be reduced.

  At this time, the thickness of the ZrO film is, for example, 12 nm or less. This is because it is not preferable to increase the film thickness of the entire capacitor structure from the viewpoint of the device structure. That is, in order to suppress the film thickness of the entire capacitor structure, it is preferable to make the ZrO film as thin as possible within the range of the film thickness that allows the phase transition.

(Phase transition step S46)
When the ZrO film having a predetermined thickness is formed, the valves 254a, 254b, and 254c are opened, and an inert gas such as N ₂ gas is supplied into the processing chamber 201. Further, the degree of energization to the heater 207 is controlled to raise the temperature of the wafer 200 to a temperature of 350 ° C. or higher and 450 ° C. or lower, for example. At this time, the opening degree of the APC valve 251 is adjusted so that the internal pressure of the processing chamber 201 is within a range of 10 Pa to 500 Pa, for example, 20 Pa. The flow rate of the inert gas is in the range of 1 slm to 10 slm, for example, and is 5 slm, for example. The supply time of the inert gas is, for example, in the range of 1 second to 3 hours. When the predetermined time has elapsed, the state of energization to the heater 207 is controlled so that the wafer 200 reaches, for example, the processing temperature in the titanium oxide film forming step S50 to be performed next, specifically, a predetermined temperature of 450 ° C. or lower. Further, the valves 254a, 254b, 254c are closed, and the supply of the inert gas is stopped.

  By raising the temperature of the ZrO film as described above, a phase transition due to heating occurs, and at least a part of the crystal structure of the ZrO film becomes a cubic structure or a tetragonal structure. At this time, as described above, by controlling the film thickness of the ZrO film to, for example, 4 nm or more, it becomes possible to more reliably phase-transform the crystal structure of the ZrO film.

(Titanium oxide film forming step S50)
Subsequently, a TiO film as a capacitor insulating film is formed on the ZrO film. That is, S51 to S54 in FIG. 6 are defined as one cycle, and this cycle is performed a predetermined number of times (S55), thereby forming a TiO film having a predetermined thickness on the ZrO film. By forming a TiO film on a ZrO film having at least a part of a cubic structure or a tetragonal structure, at least a part of the TiO film is formed into a brookite structure or a rutile structure.

(Titanium-containing gas supply step S51)
In the titanium-containing gas supply step S51, TiCl ₄ gas as a Ti-containing gas is flowed into the processing chamber 201, and TiCl ₄ molecules and the like are adsorbed on the ZrO film. Specifically, the TiCl ₄ gas vaporized in the TiCl ₄ container 261c is supplied into the processing chamber 201 together with the carrier gas by opening the valve 253c. At this time, the opening degree of the APC valve 251 is adjusted to maintain the pressure in the processing chamber 201 within a range of 30 Pa to 500 Pa, for example, 100 Pa. The flow rate of the carrier gas supplied together with the TiCl ₄ gas is 3 slm, for example. The supply time of TiCl ₄ gas (and carrier gas) is, for example, 40 seconds. When the predetermined time has elapsed, the valve 253c is closed and the supply of TiCl ₄ gas is stopped.

During the supply of the Ti-containing gas, the inert gas supply pipe 234a connected to the oxygen-containing gas supply pipe 232a and the valves 254a and 254b of the inert gas supply pipe 234b connected to the Zr-containing gas supply pipe 233b are connected. Opening and flowing an inert gas can prevent the TiCl ₄ gas from flowing into the oxygen-containing gas supply pipe 232a and the Zr-containing gas supply pipe 233b.

At this time, the gas flowing into the processing chamber 201 is only an inert gas such as TiCl ₄ gas and N ₂ gas, and there is no oxygen-containing gas such as O ₃ gas. Therefore, TiCl ₄ gas causes chemical adsorption (surface reaction) with the surface portion of the ZrO film without causing a gas phase reaction, thereby forming an adsorption layer or Ti layer of TiCl ₄ molecules. The adsorption layer of TiCl ₄ molecules, in addition to a continuous adsorption layer of TiCl ₄ molecules, including a discontinuous adsorption layer. The Ti layer includes a continuous layer composed of Ti and a Ti thin film formed by overlapping these layers. In the following, all of these are also referred to as Ti-containing layers.

(Exhaust process S52)
After the valves 252c and 253c are closed and the supply of TiCl ₄ gas into the processing chamber 201 is stopped, the APC valve 251 is opened to exhaust the processing chamber 201, and the remaining vaporized TiCl ₄ gas and reaction products are generated. Exclude things. At this time, if an inert gas such as N ₂ is supplied into the processing chamber 201 from the inert gas supply pipes 234a, 234b, and 234c and purged, the effect of removing the residual gas from the processing chamber 201 can be further enhanced. it can. After elapse of a predetermined time, the valves 234a, 234b, 234c are closed, and the exhaust process S52 is completed.

(Oxygen-containing gas supply step S53)
In the oxygen-containing gas supply step S53, an O ₃ gas as an oxygen-containing gas is flowed into the processing chamber 201 in the same procedure as the above-described oxygen-containing gas supply step S43, and a TiO layer is formed on the ZrO film. The processing conditions can be the same as in the oxygen-containing gas supply step S43, but the O ₃ gas supply time is, for example, 60 seconds. At this time, an inert gas may be supplied into the processing chamber 201 as in the oxygen-containing gas supply step S43.

By supplying the O ₃ gas in this way, the Ti-containing layer adsorbed on the ZrO film is oxidized, and a TiO thin film having a thickness of less than one atomic layer to several atomic layers is formed on the ZrO film.

(Exhaust process S54)
Residual gas is removed from the processing chamber 201 in the same procedure as the exhaust process S44 described above. At this time, the inert gas may be purged.

(Predetermined number of execution steps S55)
The above S51 to S54 are defined as one cycle, and this cycle is performed a predetermined number of times to form a TiO film having a predetermined film thickness, for example, 6 nm to 15 nm on the ZrO film. FIG. 7 shows an example in which the above cycle is performed n times. The thickness of the TiO film to be formed can be controlled by arbitrarily changing the number of cycles (the value of n).

  When a TiO film is directly formed on a TiN film, as described above, an anatase TiO film is likely to be formed. For example, if this is to be phase-transformed into a rutile or brookite type TiO film by heating as in the phase transition step S46, the TiO film is formed to a thickness of 50 nm or more, and at a high temperature of 800 ° C. or more. This heat treatment becomes necessary. Such a thick TiO film is not preferable in terms of the device structure, and heat treatment at a high temperature may adversely affect semiconductor devices, particularly electrode characteristics.

  However, according to the present embodiment, the TiO film is formed through the ZrO film having at least a part of the cubic or tetragonal crystal structure. As a result, a TiO film having at least a part of the crystal structure of a brookite structure or a rutile structure can be formed at a temperature of 450 ° C. or less without going through a phase transition by heating. At this time, as the film thickness of the TiO film, a film thickness that is preferable from the viewpoint of the device structure, for example, a film thickness of 6 nm or more and 15 nm or less can be selected as described above.

(Temperature drop step S60, normal pressure return step S70)
When the ZrO film and the TiO film having desired thicknesses are formed, the power supply to the heater 207 is stopped, and the boat 217 and the wafer 200 are lowered to a predetermined temperature. While the temperature is lowered, the valves 254a, 254b, and 254c are kept open, and the supply of the purge gas into the processing chamber 201 is continued. Thereby, the inside of the processing chamber 201 is replaced with the purge gas, and the pressure in the processing chamber 201 is returned to the normal pressure.

(Substrate unloading step S80)
When the wafer 200 is lowered to a predetermined temperature and the inside of the processing chamber 201 returns to normal pressure, the wafer 200 after film formation is unloaded from the processing chamber 201 by a procedure reverse to the above procedure. That is, the seal cap 219 is lowered by the boat elevator 115 to open the lower end of the manifold 209, and the processed wafer 200 is carried out from the lower end of the manifold 209 to the outside of the reaction tube 203 while being held by the boat 217. Unload). Thereafter, the processed wafer 200 is taken out from the boat 217 (wafer discharge). Note that when the boat 217 is carried out, it is preferable that the valves 254 a, 254 b, and 254 c are opened and the purge gas is continuously supplied into the processing chamber 201. Thus, the substrate processing process by the processing furnace 202 is completed.

[Upper electrode film formation process]
The upper electrode film forming step shown in FIG. 5 is performed in a processing furnace different from the processing furnace 202, for example. An Au film as an upper electrode film is formed on the TiO film formed in the previous step. Through the above steps, one step of the manufacturing process of the semiconductor device 1 according to this embodiment is completed.

(5) Effects according to the present embodiment According to the present embodiment, the following one or more effects are achieved.

(A) According to the present embodiment, a TiO film is not directly formed on a TiN film, but a TiO film is formed on a ZrO film in which at least a part of the crystal structure is a cubic structure or a tetragonal structure. A film is formed. As a result, at least a part of the crystal structure of the TiO film formed on the TiN film has a brookite structure or a rutile structure, and the dielectric constant of the TiO film can be increased.

  When forming the TiO film as the capacitor insulating film, the crystal structure of the TiO film can be influenced by what kind of film is selected as the base film of the TiO film. For example, when a TiO film is formed using a TiN film as a base film, an anatase TiO film having a dielectric constant lower than that of a rutile or brookite type is likely to be obtained.

  The difference in dielectric constant due to the crystal structure is caused by the difference in polarizer density inside each crystal. FIG. 8 is a drawing showing the difference in crystal structure per number of molecules of the TiO film according to the present embodiment, where (a) is a schematic diagram showing the crystal state of the anatase structure, and (b) is brookite. It is a schematic diagram which shows the crystal state of a mold structure. In the figure, black spheres are Ti atoms and white spheres are O atoms. As shown in FIG. 8B, when the TiO film has a brookite structure, the surface area per the same number of molecules is reduced compared to the anatase structure in FIG. 8A, the charge density is increased, and the dielectric constant is increased. Get higher.

  In this embodiment, since the TiO film is formed via the ZrO film that becomes the seed film (seed film) of the crystal structure of the TiO film, even if the TiO film is formed on the TiN film, the TiO film At least a part of the crystal structure can be a brookite structure or a rutile structure, and the dielectric constant of the TiO film can be increased. Therefore, a capacitor insulating film having a high dielectric constant can be obtained, and EOT can be reduced.

(B) Further, according to the present embodiment, the thickness of the ZrO film is controlled to be equal to or greater than a thickness that enables phase transition by heating. Thereby, it is possible to cause the phase transition of at least a part of the ZrO film more reliably and to control the crystal structure of the TiO film more reliably.

(C) Further, according to the present embodiment, at least a part of the TiO film formed on the ZrO film having the predetermined crystal structure has a brookite structure or a rutile structure. Therefore, in order to obtain a desired crystal structure, for example, a step such as heating the TiO film to cause phase transition is not necessary.

  For example, in order to change the phase of a TiO film formed in an anatase structure into a rutile or brookite type TiO film by heating, the TiO film must have a film thickness of a predetermined value or more, for example, a film thickness of 50 nm or more. The heating temperature must be 800 ° C. or higher, for example.

  However, in this embodiment, a TiO film having a desired crystal structure can be obtained without undergoing phase transition by heating. That is, the film thickness of the TiO film can be set to a film thickness preferable for the device structure, for example, in the range of 6 nm to 15 nm, while suppressing adverse effects on the electrode characteristics under relatively low temperature film formation conditions of 450 ° C. or lower.

(D) According to the present embodiment, the zirconium oxide film forming step S40 and the titanium oxide film forming step S50 are each performed once to form a two-layer structure of the ZrO film and the TiO film. Yes. Thus, the ZrO film serves as a leakage current preventing film (barrier film), and the leakage current density from the TiO film as the capacitor insulating film can be reduced.

  When a TiO film having a small band gap is used for the capacitor insulating film, the stacked layer structure with a ZrO film or a hafnium oxide (HfO) film may be able to reduce the leakage current density. The formation of such a laminated film is not limited to the method of forming each film once and forming a two-layer film of a ZrO film (or HfO film) and a TiO film as in the present embodiment, for example, and each atomic layer A method is conceivable in which ZrTiO films (or HfTiO films) are formed by alternately laminating each film formed in a few atomic layers from less than a plurality of times (by laminating films).

As a reference example, FIG. 9 shows IV characteristics of a semiconductor device having, as a capacitor insulating film, an HfTiO film in which HfO films and TiO films are alternately laminated. The horizontal axis of FIG. 9 indicates the voltage Vg (V) applied to the semiconductor device, and the vertical axis indicates the leakage current density I (A / cm ² ). In the figure, the solid line is data when the composition ratio of Ti in the capacitor insulating film (HfTiO film) included in the semiconductor device is 50%, the alternate long and short dash line is data when the composition ratio of Ti is 12%, and the broken line is Ti The data is when the composition ratio is 6%. Each semiconductor device according to the reference example having a Ti composition ratio of 50%, 12%, and 6% includes a lower electrode film made of a TiN film on a wafer 200, and a HfTiO film in which a TiO film and an HfO film are laminated. The capacitor insulating film made of and an upper electrode film made of an Au film are formed. After the laminate film formation, the HfTiO film of each semiconductor device is heat-treated at 700 ° C.

In the above, if the specification value is that the leakage current density is less than 1 × 10 ⁻⁷ A / cm ² when the applied voltage is 1.5 V, the specification value is not satisfied in any of the above Ti composition ratios. As the Ti composition ratio increases, the leakage current density also increases. Thus, it can be seen that when the capacitor insulating film is laminated, good IV characteristics cannot be obtained. This is considered to be the same for the capacitor insulating film (ZrTiO film) in which the ZrO film and the TiO film are laminated.

However, in this embodiment, since the ZrO film and the TiO film are formed once to form a laminated film, it is presumed that the effect of reducing the leakage current density is higher than in the case of the laminated film formation.

(E) Further, according to the present embodiment, the zirconium-containing gas supply step S41 to the exhaust step S44 are set as one cycle, and this cycle is performed a predetermined number of times (predetermined number of times execution step S45). A ZrO film having a predetermined thickness is formed. Thereby, the film thickness of the ZrO film can be controlled with high accuracy, and the phase transition of at least a part of the ZrO film can be caused more reliably.

<Other Embodiments of the Present Invention>
As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, It can change variously in the range which does not deviate from the summary.

For example, in the above-described embodiment, the case where the TEMAZ gas is used as the Zr-containing gas has been described. However, the Zr-containing gas is not limited to this. For example, Zr (O-tBu) ₄ gas, TDMAZ (tetrakisdimethylaminozirconium: Zr (NMe ₂ ) ₄ ) gas, TDEAZ (tetrakisdiethylaminozirconium: Zr (NEt ₂ ) ₄ ) gas, Zr (MMP) ₄ gas, or the like can be used.

In the above embodiments, descriptions have been given of the case using a TiCl ₄ gas as a Ti-containing gas, a Ti-containing gas is not limited to this, for example, TDMAT (tetrakis-dimethylamino titanium: Ti _{(NMe 2) 4)} gas, TDEAT (tetrakisdiethylaminotitanium: Ti (NEt ₂ ) ₄ ) gas or the like can be used.

In the above-described embodiment, the case where O ₃ gas is used as the oxygen-containing gas has been described. However, the oxygen-containing gas is not limited thereto, and for example, oxygen (O ₂ ) gas, H ₂ O gas (water vapor), or the like. Can be used. In particular, if H ₂ O gas having a lower oxidizing power than O ₃ gas is used at the initial stage of forming the ZrO film, the effect of suppressing the oxidation of the lower electrode film is enhanced.

In the above-described embodiment, the phase change step S46 is performed in the processing furnace 202. However, such a step may be performed in a heating furnace including a lamp heating unit, for example. Further, as the atmosphere gas during heating, in addition to _{N 2} (nitrogen) gas, it can be used Ar (argon) gas, _{H 2} (hydrogen) gas, _{O 2} (oxygen) gas and the like.

  In the above-described embodiment, the DRAM having the MIM structure capacitor has been described as an example. However, the semiconductor device to which the present invention is applied may be, for example, a trench type DRAM or a stacked type DRAM. The present invention can also be applied to the case where other insulating films such as a gate insulating film and a charge holding film of a flash memory are formed.

  Moreover, although the vertical processing furnace using the ALD method has been described as an example of the substrate processing apparatus for performing the manufacturing method according to the present embodiment, the present invention is, for example, various substrate processing using the CVD method or plasma technology. It is possible to carry out with an apparatus. Further, for example, a series of processes including a lower electrode film forming process to an upper electrode film forming process can be performed in the same processing furnace.

Example 1
First, Example 1 of the present invention will be described. In this example, the ZrO film and the TiO film were formed in this order on the bare silicon wafer by the same process as the substrate processing process (S10 to S80) according to the above-described embodiment. At this time, samples each having a TiO film thickness of 10 nm and different ZrO film thicknesses of 1.5 nm, 4.0 nm, and 6.5 nm were prepared. For these samples, X-ray diffraction (XRD: X-Ray Diffract)
ion), the state of the crystal structure of the ZrO film and the TiO film was examined.

  FIG. 10 shows the measurement result of the X-ray diffraction. The horizontal axis in FIG. 10 indicates the diffraction angle (°), and the vertical axis indicates the diffraction intensity (arbitrary unit). In the figure, the solid line is data of a sample having a ZrO film thickness of 6.5 nm, the alternate long and short dash is data of 4.0 nm, and the dotted line is data of 1.5 nm.

As shown in FIG. 10, in the samples with the ZrO film thicknesses of 6.5 nm and 4.0 nm, the peaks at the diffraction angles indicating the presence of cubic ZrO ₂ are around 30 ° and around 50 °. As a result, it can be seen that the crystal structure of at least a part of the ZrO film is cubic. In addition, since a peak is obtained in the vicinity of a diffraction angle of 30 ° indicating the presence of brookite-type TiO ₂ , it can be seen that at least a part of the crystal structure of the TiO film is a brookite-type.

On the other hand, in the sample having a ZrO film thickness of 1.5 nm, no peaks are observed at 30 ° and 50 ° indicating cubic ZrO ₂ and brookite type TiO ₂ , and the presence of anatase type TiO ₂ is observed. A peak is obtained in the vicinity of 25 °. Therefore, it can be seen that almost no phase transition of the ZrO film to the cubic system occurs, and the TiO film formed thereon has become substantially anatase type.

  From the above data, it can be seen that the thickness of the ZrO film must be greater than or equal to a predetermined value in order to cause the phase transition of the ZrO film to the cubic system by heating. In this example, when the thickness of the ZrO film was 4.0 nm, at least a part of the ZrO film could be transformed into a cubic system.

(Example 2)
Next, a second embodiment of the present invention will be described. In this example, a semiconductor device having the same structure as the semiconductor device 1 shown in FIG. 4 of the above-described embodiment was manufactured. At this time, samples having different thicknesses of the TiO film having a constant value of 10 nm and different ZrO film thicknesses of 1.5 nm, 5.0 nm, and 6.5 nm were prepared. EOT was measured for these samples.

  FIG. 11 shows the measurement result. The horizontal axis in FIG. 11 indicates the total film thickness (nm) of the ZrO film and the TiO film, and the vertical axis indicates EOT (nm).

  As shown in FIG. 11, when the thickness of the ZrO film is 5.0 nm (total thickness is 15.0 nm), compared to when the thickness of the ZrO film is 1.5 nm (total thickness is 11.5 nm). In addition, when the film thickness of the ZrO film is 6.5 nm (total film thickness is 16.5 nm), the EOT decreases. It can also be seen that the EOT has a minimum value in the vicinity where the thickness of the ZrO film becomes 5.0 nm.

  From the result of Example 1 described above, since the phase transition of the ZrO film is possible at a film thickness of about 4.0 nm, the decrease in EOT at 5.0 nm and 6.5 nm is observed in the ZrO film and the TiO film. This is considered to be an effect obtained by obtaining a desired crystal structure. Note that the slight increase in EOT seen when the film thickness of the ZrO film is 6.5 nm is considered to be simply due to an increase in the total film thickness of the ZrO film and the TiO film.

  On the other hand, when the thickness of the ZrO film is 1.5 nm, the EOT increases despite the decrease in the total thickness of the ZrO film and the TiO film. This is because, as the film thickness of the ZrO film decreases, the phase transition to the cubic system as seen in the above-mentioned Example 1 hardly occurs, and the TiO film formed thereon also has an anatase type structure. This is thought to be due to an increase in the share.

  In combination with the data of Example 1 described above, if the thickness of the ZrO film is 4.0 nm or more, at least a part of the ZrO film can be phase-shifted more reliably, and a superior result can be obtained in EOT. I understand that

<Preferred embodiment of the present invention>
Hereinafter, preferred embodiments of the present invention will be additionally described.

One embodiment of the present invention provides:
A zirconium oxide film forming step of forming a zirconium oxide film on the titanium nitride film formed on the substrate;
A titanium oxide film forming step of forming a titanium oxide film on the zirconium oxide film,
By controlling the film thickness of the zirconium oxide film, the crystal structure of at least a part of the zirconium oxide film is changed to a cubic structure or a tetragonal structure, whereby a crystal structure of at least a part of the titanium oxide film is formed. Is a manufacturing method of a semiconductor device having a brookite structure or a rutile structure.

Another aspect of the present invention is:
A zirconium oxide film forming step of forming a zirconium oxide film on the titanium nitride film formed on the substrate;
A titanium oxide film forming step of forming a titanium oxide film on the zirconium oxide film,
The zirconium oxide film forming step includes
Supplying and exhausting a zirconium-containing gas into a processing chamber containing the substrate;
Supplying and exhausting an oxygen-containing gas into the processing chamber, and performing this cycle a predetermined number of times to form a zirconium oxide film on the titanium nitride film;
Heating the zirconium oxide film to cause a phase transition of at least a part of the crystal structure of the zirconium oxide film,
The titanium oxide film forming step includes
Supplying and exhausting a titanium-containing gas into the processing chamber;
Supplying and exhausting the oxygen-containing gas into the processing chamber, and performing this cycle a predetermined number of times to form a titanium oxide film on the phase-changed zirconium oxide film. And
By controlling the thickness of the zirconium oxide film, the zirconium oxide film is heated to cause a phase transition of the crystal structure of at least a part of the zirconium oxide film to a cubic structure or a tetragonal structure, Thus, the semiconductor device manufacturing method has a brookite structure or a rutile structure in at least a part of the crystal structure of the titanium oxide film.

Preferably,
The film thickness of the zirconium oxide film is controlled to be greater than a film thickness that enables a phase transition by heating at least a part of the crystal structure of the zirconium oxide film to a cubic structure or a tetragonal structure.

Also preferably,
The thickness of the zirconium oxide film is controlled to 4.0 nm or more.

Also preferably,
In the step of heating and phase transition of the zirconium oxide film,
The zirconium oxide film is heated at a temperature of 350 ° C. or higher and 450 ° C. or lower.

Also preferably,
In the titanium oxide film forming step,
The titanium oxide film having the crystal structure is formed at a temperature of 450 ° C. or lower.

Still another aspect of the present invention provides:
A processing chamber for accommodating a substrate on which a titanium nitride film is formed;
A heating unit for heating the substrate;
A zirconium-containing gas supply unit for supplying a zirconium-containing gas into the processing chamber;
A titanium-containing gas supply unit for supplying a titanium-containing gas into the processing chamber;
An oxygen-containing gas supply unit for supplying an oxygen-containing gas into the processing chamber;
An exhaust section for exhausting the atmosphere in the processing chamber;
A control unit for controlling the heating unit, the zirconium-containing gas supply unit, the titanium-containing gas supply unit, the oxygen-containing gas supply unit, and the exhaust unit;
The controller is
Supplying and exhausting a zirconium-containing gas into the processing chamber containing the substrate, supplying and exhausting an oxygen-containing gas into the processing chamber, and supplying and exhausting the zirconium-containing gas and supplying and exhausting the oxygen-containing gas. This cycle is repeated a predetermined number of times to form a zirconium oxide film on the titanium nitride film, and the zirconium oxide film is heated to change the crystal structure of at least a part of the zirconium oxide film. Let
Titanium-containing gas is supplied and exhausted into the processing chamber, and the oxygen-containing gas is supplied and exhausted into the processing chamber. By performing a predetermined number of cycles, control to form a titanium oxide film on the zirconium oxide film that has undergone phase transition,
By controlling the thickness of the zirconium oxide film, the zirconium oxide film is heated to cause a phase transition of the crystal structure of at least a part of the zirconium oxide film to a cubic structure or a tetragonal structure, Thus, the substrate processing apparatus is configured such that at least a part of the crystal structure of the titanium oxide film has a brookite structure or a rutile structure.

Still another aspect of the present invention provides:
A zirconium oxide film forming step of forming a zirconium oxide film having at least a part of a cubic structure or a tetragonal structure on a titanium nitride film formed on a substrate;
Forming a titanium oxide film having a brookite structure or a rutile structure at least partially on the zirconium oxide film at a temperature of 450 ° C. or lower; and forming a high dielectric constant insulating film It is.

Preferably,
In the zirconium oxide film forming step,
The film thickness of the zirconium oxide film is controlled so that the total film thickness of the zirconium oxide film and the titanium oxide film approaches a minimum value capable of maintaining a predetermined high dielectric constant.

DESCRIPTION OF SYMBOLS 1 Semiconductor device 101 Substrate processing apparatus 200 Wafer (substrate)
201 processing chamber 207 heater 280 controller

Claims (2)

A zirconium oxide film forming step of forming a zirconium oxide film on the titanium nitride film formed on the substrate;
A titanium oxide film forming step of forming a titanium oxide film on the zirconium oxide film,
By controlling the film thickness of the zirconium oxide film, the crystal structure of at least a part of the zirconium oxide film is changed to a cubic structure or a tetragonal structure, whereby a crystal structure of at least a part of the titanium oxide film is formed. A manufacturing method of a semiconductor device, characterized in that a brookite structure or a rutile structure is used. A processing chamber for accommodating a substrate on which a titanium nitride film is formed;
A heating unit for heating the substrate;
A zirconium-containing gas supply unit for supplying a zirconium-containing gas into the processing chamber;
A titanium-containing gas supply unit for supplying a titanium-containing gas into the processing chamber;
An oxygen-containing gas supply unit for supplying an oxygen-containing gas into the processing chamber;
An exhaust section for exhausting the atmosphere in the processing chamber;
A control unit for controlling the heating unit, the zirconium-containing gas supply unit, the titanium-containing gas supply unit, the oxygen-containing gas supply unit, and the exhaust unit;
The controller is
Supplying and exhausting a zirconium-containing gas into the processing chamber containing the substrate, supplying and exhausting an oxygen-containing gas into the processing chamber, and supplying and exhausting the zirconium-containing gas and supplying and exhausting the oxygen-containing gas. This cycle is repeated a predetermined number of times to form a zirconium oxide film on the titanium nitride film, and the zirconium oxide film is heated to change the crystal structure of at least a part of the zirconium oxide film. Let
Titanium-containing gas is supplied and exhausted in the processing chamber, the oxygen-containing gas is supplied and exhausted in the processing chamber, and the titanium-containing gas supply / exhaust and the oxygen-containing gas supply / exhaust are set as one cycle. By performing a predetermined number of cycles, control to form a titanium oxide film on the zirconium oxide film that has undergone phase transition,
By controlling the thickness of the zirconium oxide film, the zirconium oxide film is heated to cause a phase transition of the crystal structure of at least a part of the zirconium oxide film to a cubic structure or a tetragonal structure, Thus, the substrate processing apparatus is configured such that the crystal structure of at least a part of the titanium oxide film has a brookite structure or a rutile structure.

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