WO2019058554A1

WO2019058554A1 - Manufacturing method of semiconductor device, substrate processing device and program

Info

Publication number: WO2019058554A1
Application number: PCT/JP2017/034543
Authority: WO
Inventors: 小川　有人
Original assignee: 株式会社ＫｏｋｕｓａｉＥｌｅｃｔｒｉｃ
Priority date: 2017-09-25
Filing date: 2017-09-25
Publication date: 2019-03-28
Also published as: JPWO2019058554A1; CN111095490A; SG11202001565UA; CN111095490B; JP6979463B2

Abstract

Problem: To suppress etching gas from reacting with films other than the etching target film that are exposed during etchback. Solution: A method involving: an etchback step in which an oxygen-containing gas and a fluorine-containing etching gas are supplied to a substrate, which comprises a first metal film formed on the surface and a second metal film embedded in an opening, to etch the second metal film; and a removal step in which the aforementioned oxygen-containing gas and the aforementioned fluorine-containing etching gas are removed.

Description

Semiconductor device manufacturing method, substrate processing apparatus and program

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

In general, a tungsten (W) film is used as a control gate of a NAND-type flush memory having a three-dimensional structure or an electrode for a word line of a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The W film is finally embedded in the hole, but at the time of film formation, the W film is completely embedded and closed in the hole. At this time, since the W film is formed on unnecessary portions, an etch back process is performed after the W film formation step to leave the W film only on the desired portion.

JP, 2015-109419, A

Conventionally, wet cleaning has been mainly used for etching back W films, but in recent years, etching back by dry etching has been considered. However, for example, when the W film is etched back, the film thickness of the W film to be etched back is larger (thicker) than the film thickness of the W film formed, and therefore, in the portion where the W film is not embedded The membrane may be exposed. The other exposed film may react with the etching gas to be scraped or form foreign matter.

An object of the present invention is to provide a technology capable of suppressing the reaction of the etching gas with a film other than the film to be etched which has been exposed during the etch back.

According to one aspect of the invention:
An oxygen-containing gas and a fluorine-containing etching gas are supplied to the substrate in which the second metal film is embedded in the opening in which the first metal film is formed on the surface, and the second metal film is etched back Etch back process,
Removing the oxygen-containing gas and the fluorine-containing etching gas;
Technology is provided.

According to the present invention, it is possible to suppress the reaction of the etching gas with a film other than the film to be etched which has been exposed at the time of etch back.

FIG. 1 shows a schematic of a device in an embodiment of the present invention. It is a longitudinal cross-sectional view which shows the outline of the vertical processing furnace of the substrate processing apparatus in one Embodiment of this invention. FIG. 3 is a schematic cross-sectional view taken along line AA in FIG. It is a schematic block diagram of the controller of the substrate processing apparatus in one Embodiment of this invention, and is a figure which shows the control system of a controller with a block diagram. It is a figure which shows the timing of gas supply in one Embodiment of this invention. It is a figure which shows the positional relationship of the kind of board | substrate accommodated in the processing chamber of the substrate processing apparatus at the time of evaluation by one Embodiment of this invention, and each board | substrate. It is a figure which shows the result of evaluation (XPS analysis of Si wafer) by one Embodiment of this invention. It is a figure which shows the modification of the timing of gas supply of one Embodiment of this invention, (A) is a figure which shows modification 1, (B) is a figure which shows modification 2, (C) is a figure. It is a figure which shows the modification 3, (D) is a figure which shows the modification 4, (E) is a figure which shows the modification 5, (F) is a figure which shows the modification 6. FIG.

For example, in the NAND-type flush memory, as described above, when the W film is etched back, the other film may be exposed at the portion where the W film is not embedded. As another film, for example, a silicon film (Si film), a silicon oxide film (SiO film), a silicon nitride film (SiN film), an aluminum oxide film (AlO film), etc. may be mentioned. In addition, there is also a portion that is exposed from the beginning, such as the back surface of the substrate. For example, in the case of a silicon (Si) substrate, Si is exposed on the back surface. In the case of a Si substrate, silicon 601 corresponds to the Si substrate. For example, as shown in FIG. 1, an aluminum oxide film 603 and a titanium nitride film 602 are formed on silicon 604, and tungsten 601 may be embedded.

For example, when Si is exposed, it may react with the etching gas to scrape Si, or the etched W may react with Si and W may enter Si. For example, when AlO is exposed, it may react with elements contained in the etching gas to form foreign matter, and the foreign matter may remain in the AlO. When a halogen-based etching gas is used as the etching gas, the foreign matter is mainly composed of Al and a halogen element. For example, when nitrogen trifluoride (NF ₃ ) gas, which is a fluorine-containing gas, is used as the etching gas, Al reacts with F to form AlF. Since AlF has a low vapor pressure, it may remain in AlO as a solid.

Therefore, the inventors conducted earnest studies and considered flowing an oxygen-containing gas simultaneously with the etching gas at the time of etch back. For example, by flowing an oxygen-containing gas, Si and O react with each other at the exposed portion of Si to form SiO, thereby suppressing the reaction with the etching gas and suppressing the removal of Si. It is possible to suppress the reaction between the etched W and Si, and the entry of W into Si. This is because Si reacts with W to form a tungsten silicon film (tungsten silicide, WSi), but SiO does not react with W. In addition, the reaction of AlO with the etching gas can be suppressed, and the formation of foreign matter can be suppressed by reacting with the elements contained in the etching gas. Details will be described below.

<One embodiment of the present invention>
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. The substrate processing apparatus 10 is configured as an example of an apparatus used in a manufacturing process of a semiconductor device.

(1) Configuration of Substrate Processing Apparatus The substrate processing apparatus 10 includes a processing furnace 202 provided with a heater 207 as a heating unit (heating mechanism, heating system). The heater 207 has a cylindrical shape and is vertically installed by being supported by a heater base (not shown) as a holding plate.

Inside the heater 207, an outer tube 203 which constitutes a reaction vessel (processing vessel) concentrically with the heater 207 is disposed. The outer tube 203 is made of, for example, a heat resistant material such as quartz (SiO ₂ ) or silicon carbide (SiC), and is formed in a cylindrical shape whose upper end is closed and whose lower end is open. Below the outer tube 203, a manifold (inlet flange) 209 is disposed concentrically with the outer tube 203. The manifold 209 is made of, for example, a metal such as stainless steel (SUS), and is formed in a cylindrical shape whose upper and lower ends are open. Between the upper end portion of the manifold 209 and the outer tube 203, an O-ring 220a as a sealing member is provided. By supporting the manifold 209 on the heater base, the outer tube 203 is placed vertically.

The inner tube 204 which comprises a reaction container is arrange | positioned inside the outer tube 203. As shown in FIG. The inner tube 204 is made of, for example, a heat resistant material such as quartz (SiO ₂ ) or silicon carbide (SiC), and is formed in a cylindrical shape whose upper end is closed and whose lower end is open. A processing vessel (reaction vessel) is mainly configured by the outer tube 203, the inner tube 204, and the manifold 209. A processing chamber 201 is formed in a cylindrical hollow portion (inner side of the inner tube 204) of the processing container.

The processing chamber 201 is configured to be able to accommodate the wafers 200 as a substrate in a state in which the wafers 200 are horizontally arranged in multiple stages in the vertical posture by a boat 217 described later.

In the processing chamber 201,

nozzles

410, 420, 430 are provided to penetrate the side wall of the manifold 209 and the inner tube 204.

Gas supply pipes

310, 320, and 330 as gas supply lines are connected to the

nozzles

410, 420, and 430, respectively. As described above, the substrate processing apparatus 10 is provided with the three

nozzles

410, 420, 430 and the three

gas supply pipes

310, 320, 330, and supplies a plurality of types of gas into the processing chamber 201. It is configured to be able to. However, the processing furnace 202 of this embodiment is not limited to the above-mentioned form.

Mass flow controllers (MFC) 312, 322, and 332, which are flow controllers (flow control units), are provided in the

gas supply pipes

310, 320, and 330 sequentially from the upstream side. In addition,

valves

314, 324 and 334, which are on-off valves, are provided in the

gas supply pipes

310, 320 and 330, respectively.

Gas supply pipes

610, 620, 630 for supplying an etching gas are connected to the downstream side of the

valves

314, 324, 334 of the

gas supply pipes

310, 320, 330, respectively. In the

gas supply pipes

610, 620, and 630,

MFCs

612, 622, and 632 as flow controllers (flow control units) and

valves

614, 624, and 634 as on-off valves are provided in this order from the upstream side. Further,

gas supply pipes

510, 520, and 530 for supplying an inert gas are connected to the downstream side of the

valves

314, 324, and 334 of the

gas supply pipes

310, 320, and 330, respectively. The

gas supply pipes

510, 520, and 530 are provided with MFCs 512, 522, and 532 as flow controllers (flow control units) and

valves

514, 524, and 534 as on-off valves in this order from the upstream side.

Nozzles

410, 420, and 430 are connected to and connected to tip ends of the

gas supply pipes

310, 320, and 330, respectively. The

nozzles

410, 420, 430 are configured as L-shaped nozzles, and the horizontal portion thereof is provided to penetrate the side wall of the manifold 209 and the inner tube 204. Vertical portions of the

nozzles

410, 420, 430 are provided inside a channel-shaped (groove-shaped) preliminary chamber 201a which is formed to project radially outward of the inner tube 204 and extend in the vertical direction. It is provided upward along the inner wall of the inner tube 204 in the preparatory chamber 201a (upward in the arrangement direction of the wafers 200).

The

nozzles

410, 420, 430 are provided to extend from the lower region of the processing chamber 201 to the upper region of the processing chamber 201, and a plurality of gas supply holes 410 a, 420 a, 430 a are provided at positions facing the wafer 200. Is provided. Thereby, the processing gas is supplied to the wafer 200 from the gas supply holes 410 a, 420 a, 430 a of the

nozzles

410, 420, 430 respectively. A plurality of

gas supply holes

410a, 420a, 430a are provided from the lower portion to the upper portion of the inner tube 204, have the same opening area, and are provided at the same opening pitch. However, the

gas supply holes

410a, 420a, 430a are not limited to the above-mentioned form. For example, the opening area may be gradually increased from the lower portion to the upper portion of the inner tube 204. This makes it possible to further equalize the flow rate of the gas supplied from the

gas supply holes

410a, 420a and 430a.

A plurality of

gas supply holes

410a, 420a, 430a of the

nozzles

410, 420, 430 are provided at heights from the lower portion to the upper portion of the boat 217 described later. Therefore, the processing gas supplied from the gas supply holes 410 a, 420 a, 430 a of the

nozzles

410, 420, 430 into the processing chamber 201 is stored in the wafer 200 stored from the lower part to the upper part of the boat 217, ie, the boat 217. The entire area of the wafer 200 is supplied. The

nozzles

410, 420, 430 may be provided so as to extend from the lower region to the upper region of the processing chamber 201, but are preferably provided so as to extend near the ceiling of the boat 217.

From the gas supply pipe 310, a source gas (metal-containing gas, source gas) containing a metal element is supplied as a processing gas into the processing chamber 201 via the MFC 312, the valve 314, and the nozzle 410. As a raw material, for example, tungsten (W) as a metal element is used, and a halogen-based raw material (halide) and tungsten hexafluoride (WF ₆ ) as a fluorine-containing raw material gas are used.

The reducing gas is supplied from the gas supply pipe 320 into the processing chamber 201 through the MFC 322, the valve 324, and the nozzle 420. For example, hydrogen (H ₂ ) gas can be used as the H-containing gas containing hydrogen (H) as the reducing gas.

An oxidizing gas is supplied from the gas supply pipe 330 into the processing chamber 201 via the MFC 332, the valve 334 and the nozzle 430. As the oxidizing gas, oxygen (O ₂ ) gas can be used, for example, as an O-containing gas containing oxygen (O).

As an inert gas, for example, nitrogen (N ₂ ) gas from the

gas supply pipes

510, 520, and 530 is, for example, a processing chamber via the MFCs 512, 522 and 532,

valves

514, 524 and 534, and

nozzles

410, 420 and 430, respectively. 201 is supplied. The following is a description of an example of using the N ₂ gas as the inert gas, the inert gas, in addition to N ₂ gas, for example, argon (Ar) gas, helium (He) gas, neon (Ne) gas Or a rare gas such as xenon (Xe) gas.

The etching gas is supplied from the

gas supply pipes

610, 620, and 630 into the processing chamber 201 through the

MFCs

612, 622, and 632, the

valves

614, 624, and 634, and the

nozzles

410, 420, and 430, respectively. As the etching gas, for example, nitrogen trifluoride (NF ₃ ) as a fluorine-containing etching gas that is a halogen-based etching gas containing a halogen element and contains a fluorine element can be used.

Mainly by

gas supply pipes

310, 320, 330, 610, 620, 630,

MFCs

312, 322, 332, 612, 622, 623,

valves

314, 324, 334, 614, 624, 634 and

nozzles

410, 420, 430 Although the gas supply system is configured, only the

nozzles

410, 420, and 430 may be considered as the gas supply system. When the raw material gas is allowed to flow from the

gas supply pipes

310 and 330, the raw material gas supply system mainly includes the

gas supply pipes

310 and 330, the

MFCs

312 and 332, and the

valves

314 and 334. It may be considered in the system. When the reducing gas flows from the gas supply pipe 320, the reducing gas supply system is mainly configured by the gas supply pipe 320, the MFC 322, and the valve 324, but the nozzle 420 may be included in the reducing gas supply system. When the etching gas flows from the

gas supply pipes

610, 620, 630, the etching gas supply system is mainly configured by the

gas supply pipes

610, 620, 630, the

MFCs

612, 622, 623, and the

valves

614, 624, 634. The

nozzles

410, 420 and 430 may be included in the etching gas supply system. The inert gas supply system is mainly configured by the

gas supply pipes

510, 520, 530, the MFCs 512, 522, 532, and the

valves

514, 524, 534. The inert gas supply system can also be referred to as a purge gas supply system, a dilution gas supply system, or a carrier gas supply system.

The gas supply method according to the present embodiment is performed in the annular longitudinal space defined by the inner wall of the inner tube 204 and the ends of the plurality of wafers 200, that is, in the spare chamber 201a in the cylindrical space. The gas is conveyed via the

nozzles

410, 420, 430 arranged in the Then, the gas is ejected from the plurality of gas supply holes 410 a, 420 a, 430 a provided at positions facing the wafer of the

nozzles

410, 420, 430 into the inner tube 204. More specifically, the source gas or the like is ejected in a direction parallel to the surface of the wafer 200, that is, in a horizontal direction by the gas supply holes 410a of the nozzle 410, the gas supply holes 420a of the nozzle 420, and the gas supply holes 430a of the nozzle 430. ing.

The exhaust hole (exhaust port) 204a is a side wall of the inner tube 204 and is a through hole formed at a position facing the

nozzles

410, 420, 430, that is, a position opposite to the preparatory chamber 201a by 180 degrees. The slit-like through holes are elongated in the vertical direction. Therefore, the gas supplied from the

gas supply holes

410a, 420a, 430a of the

nozzles

410, 420, 430 into the processing chamber 201 and flowing over the surface of the wafer 200, that is, the remaining gas (residual gas) is an exhaust hole 204a. Flow into the exhaust passage 206 formed of a gap formed between the inner tube 204 and the outer tube 203. Then, the gas that has flowed into the exhaust path 206 flows into the exhaust pipe 231 and is exhausted out of the processing furnace 202.

The exhaust holes 204a are provided at positions facing the plurality of wafers 200 (preferably, positions facing the lower and upper portions of the boat 217), and the

gas supply holes

410a, 420a, and 430a are provided for the wafers 200 in the processing chamber 201. The gas supplied to the vicinity flows in the horizontal direction, that is, in the direction parallel to the surface of the wafer 200, and then flows into the exhaust path 206 through the exhaust hole 204a. That is, the gas remaining in the processing chamber 201 is exhausted parallel to the main surface of the wafer 200 through the exhaust hole 204 a. The exhaust hole 204a is not limited to a slit-like through hole, and may be constituted by a plurality of holes.

The manifold 209 is provided with an exhaust pipe 231 for exhausting the atmosphere in the processing chamber 201. In the exhaust pipe 231, a pressure sensor 245 as a pressure detector (pressure detection unit) for detecting the pressure in the processing chamber 201, an APC (Auto Pressure Controller) valve 243, and a vacuum pump as an evacuation device in order from the upstream side. 246 are connected. The APC valve 243 can perform vacuum evacuation and vacuum evacuation stop in the processing chamber 201 by opening and closing the valve in a state where the vacuum pump 246 is operated, and further, the valve in a state where the vacuum pump 246 is operated. The pressure in the process chamber 201 can be adjusted by adjusting the opening degree. An exhaust system, that is, an exhaust line is mainly configured by the exhaust hole 204a, the exhaust passage 206, the exhaust pipe 231, the APC valve 243, and the pressure sensor 245. The vacuum pump 246 may be included in the exhaust system.

Below the manifold 209, a seal cap 219 is provided as a furnace port that can close the lower end opening of the manifold 209 in an airtight manner. The seal cap 219 is configured to abut on the lower end of the manifold 209 from the lower side in the vertical direction. The seal cap 219 is made of metal such as SUS, for example, and formed in a disk shape. On the top surface of the seal cap 219, an O-ring 220b is provided as a seal member that contacts the lower end of the manifold 209. On the opposite side of the processing chamber 201 in the seal cap 219, a rotation mechanism 267 for rotating a boat 217 containing the wafer 200 is installed. The rotation shaft 255 of the rotation mechanism 267 is connected to the boat 217 through the seal cap 219. The rotation mechanism 267 is configured to rotate the wafer 200 by rotating the boat 217. The seal cap 219 is configured to be lifted and lowered in the vertical direction by a boat elevator 115 as a lifting and lowering mechanism installed vertically on the outside of the outer tube 203. The boat elevator 115 is configured to be able to carry the boat 217 into and out of the processing chamber 201 by moving the seal cap 219 up and down. The boat elevator 115 is configured as a transfer device (transfer mechanism) that transfers the boat 217 and the wafers 200 stored in the boat 217 into and out of the processing chamber 201.

The boat 217 as a substrate support supports a plurality of, for example, 25 to 200 wafers 200 in a horizontal position and in a vertical direction with their centers aligned with one another, that is, It is configured to arrange at intervals. The boat 217 is made of, for example, a heat resistant material such as quartz or SiC. At the lower part of the boat 217, a heat insulating plate 218 made of a heat resistant material such as quartz or SiC is supported by multiple stages (not shown) in a horizontal posture. This configuration makes it difficult for the heat from the heater 207 to be transmitted to the seal cap 219 side. However, this embodiment is not limited to the above-mentioned form. For example, without providing the heat insulating plate 218 in the lower part of the boat 217, a heat insulating cylinder configured as a cylindrical member made of a heat resistant material such as quartz or SiC may be provided.

As shown in FIG. 3, a temperature sensor 263 as a temperature detector is installed in the inner tube 204, and by adjusting the amount of current supplied to the heater 207 based on the temperature information detected by the temperature sensor 263, The temperature in the processing chamber 201 is configured to have a desired temperature distribution. The temperature sensor 263 is L-shaped similarly to the

nozzles

410, 420 and 430, and is provided along the inner wall of the inner tube 204.

As shown in FIG. 4, the controller 121, which is a control unit (control means), is configured as a computer including a central processing unit (CPU) 121a, a random access memory (RAM) 121b, a storage device 121c, and an I / O port 121d. It is done. The RAM 121b, the storage device 121c, and the I / O port 121d are configured to be able to exchange data with the CPU 121a via an internal bus. An input / output device 122 configured as, for example, a touch panel or the like is connected to the controller 121.

The storage device 121 c is configured by, for example, a flash memory, a hard disk drive (HDD), or the like. The storage device 121c readably stores a control program for controlling the operation of the substrate processing apparatus, and a process recipe in which a procedure and conditions of a method of manufacturing a semiconductor device described later are described. The process recipe is a combination of processes so as to cause the controller 121 to execute each step (each step) in a method of manufacturing a semiconductor device to be described later so as to obtain a predetermined result, and functions as a program. Hereinafter, the process recipe, the control program and the like are generically referred to simply as a program. When the term "program" is used in the present specification, when only the process recipe alone is included, the case where only the control program alone is included, or a combination of the process recipe and the control program may be included. The RAM 121 b is configured as a memory area (work area) in which programs and data read by the CPU 121 a are temporarily stored.

The I / O port 121 d may be any of the above-mentioned

MFCs

312, 322, 332, 512, 522, 522, 612, 622, 632,

valves

314, 324, 334, 514, 534, 614, 624, 634, pressure sensors 245, It is connected to the APC valve 243, the vacuum pump 246, the heater 207, the temperature sensor 263, the rotation mechanism 267, the boat elevator 115 and the like.

The CPU 121a is configured to read out and execute the control program from the storage device 121c, and to read out a recipe or the like from the storage device 121c in response to an input of an operation command from the input / output device 122 or the like. The CPU 121a adjusts the flow rates of various gases by the

MFCs

312, 322, 332, 512, 522, 532, 612, 622, and 632, and the

valves

314, 324, 334, 514, 524, and 534 so as to conform to the contents of the read recipe. , 614, 624, 634, opening / closing operation of the APC valve 243 and pressure adjustment operation based on the pressure sensor 245 by the APC valve 243, temperature adjustment operation of the heater 207 based on the temperature sensor 263, start and stop of the vacuum pump 246, It is configured to control the rotation and rotational speed adjustment operation of the boat 217 by the rotation mechanism 267, the elevation operation of the boat 217 by the boat elevator 115, the accommodation operation of the wafer 200 in the boat 217, and the like.

The controller 121 is stored in an external storage device (for example, a magnetic tape, a magnetic disk such as a flexible disk or hard disk, an optical disk such as a CD or DVD, a magnetooptical disk such as MO, a semiconductor memory such as a USB memory or memory card) The above-described program can be configured by installing it on a computer. The storage device 121 c and the external storage device 123 are configured as computer readable recording media. Hereinafter, these are collectively referred to simply as recording media. In the present specification, the recording medium may include only the storage device 121 c alone, may include only the external storage device 123 alone, or may include both of them. The program may be provided to the computer using communication means such as the Internet or a dedicated line without using the external storage device 123.

(2) Substrate Processing Process As one process of manufacturing process of semiconductor device (device), it is a pattern provided on wafer 200 as a silicon substrate, and an AlO film and a titanium nitride film (TiN film) are formed in order on the surface An example of a W film formation step of embedding a W film in the hole of the pattern and an etch back step of etching back the W film will be described with reference to FIG. The W film forming step and the etch back step are performed using the processing furnace 202 of the substrate processing apparatus 10 described above. In the following description, the operation of each part constituting the substrate processing apparatus 10 is controlled by the controller 121.

The manufacturing process (substrate processing process) of the semiconductor device according to the present embodiment is as follows.
For a wafer 200 in which a second metal film (for example, a W film) is embedded in an opening (a hole) in which a first metal film (for example, a TiN film) is formed on the surface, oxygen containing gas (for example, O ₂ gas) And fluorine-containing gas (e.g., NF ₃ gas) to etch back the W film;
A removal step of removing O ₂ gas and NF ₃ gas;
including.

In the present specification, when the word "wafer" is used, it means "wafer itself" or "laminate (aggregate) of a wafer and a predetermined layer or film or the like formed on the surface". (That is, when a predetermined layer or film formed on the surface is referred to as a wafer). In addition, when the term "surface of wafer" is used in this specification, it means "surface (exposed surface) of wafer itself" or "surface of a predetermined layer or film or the like formed on a wafer" That is, it may mean "the outermost surface of the wafer as a laminate". In addition, when the word "substrate" is used in this specification, it is synonymous with the case where the word "wafer" is used.

(Wafer loading)
As shown in FIG. 1, when a wafer 200 having holes of a pattern in which an AlO film and a titanium nitride film (TiN film) are sequentially formed on a plurality of sheets is loaded on a boat 217 (wafer charging), The boat 217 supporting the plurality of wafers 200 is lifted by the boat elevator 115 and carried into the processing chamber 201 (boat loading). In this state, the seal cap 219 closes the lower end opening of the reaction tube 203 via the O-ring 220.

(Pressure adjustment and temperature adjustment)
The vacuum pump 246 evacuates the processing chamber 201 to a desired pressure (degree of vacuum). At this time, the pressure in the processing chamber 201 is measured by the pressure sensor 245, and the APC valve 243 is feedback-controlled based on the measured pressure information (pressure adjustment). The vacuum pump 246 keeps operating at all times at least until the processing on the wafer 200 is completed. The heater 207 heats the inside of the processing chamber 201 to a desired temperature. At this time, the amount of current supplied to the heater 207 is feedback-controlled based on the temperature information detected by the temperature sensor 263 (temperature adjustment) so that the interior of the processing chamber 201 has a desired temperature distribution. Heating of the processing chamber 201 by the heater 207 is continuously performed at least until processing of the wafer 200 is completed.

[W deposition process (W deposition)]
Perform the step of forming a W film.

(WF ₆ gas and H ₂ gas supply)
The

valves

314 and 324 are opened to flow the WF ₆ gas and the H ₂ gas into the

gas supply pipes

310 and 320, respectively. The flow rates of the WF ₆ gas and the H ₂ gas are adjusted by the

MFCs

312 and 324, respectively, supplied from the

gas supply holes

410a and 420a of the

nozzles

410 and 420 into the processing chamber 201, and exhausted from the exhaust pipe 231. At this time, WF ₆ gas and H ₂ gas are supplied to the wafer 200. At this time, the valves 514 and 524 may be simultaneously opened to flow an inert gas such as N ₂ gas into the

gas supply pipes

510 and 520. The flow rate of the N ₂ gas flowing in the

gas supply pipes

510 and 520 is adjusted by the MFCs 512 and 522, and is supplied together with the WF ₆ gas and the H ₂ gas into the processing chamber 201 and exhausted from the exhaust pipe 231. At this time, the valve 534 is opened to flow the N ₂ gas into the gas supply 530 in order to prevent the WF ₆ gas and the H ₂ gas from intruding into the nozzle 430. The N ₂ gas is supplied into the processing chamber 201 through the gas supply pipe 330 and the nozzle 430, and is exhausted from the exhaust pipe 231.

At this time, the APC valve 243 is adjusted to set the pressure in the processing chamber 201 to, for example, a pressure in the range of 10 to 6630 Pa. The supply amount of WF ₆ gas controlled by MFC 312 is, for example, the supply amount in the range of 0.01 to 5 slm, and the supply flow rate of H ₂ gas controlled by MFC 322 is, for example, the flow rate in the range of 0.1 to 50 slm. However, it may be determined according to the desired film thickness. The time for supplying the WF ₆ gas and the H ₂ gas to the wafer 200, that is, the gas supply time (irradiation time) is determined according to the desired film thickness. At this time, the temperature of the heater 207 is set such that the temperature of the wafer 200 is, for example, a temperature within a range of 100 ° C. to 500 ° C., preferably a temperature within a range of 150 to 450 ° C.

The WF ₆ gas and the H ₂ gas flowing into the processing chamber 201 react (gas phase reaction) in the gas phase or react (surface reaction) on the substrate surface, and a W film is formed on the wafer 200. At this time, the W film is embedded in the hole formed on the wafer 200, and the W film is also formed on the TiN film formed on the surface of the wafer 200.

(Remaining gas removal)
After the W film having a predetermined film thickness is formed, the

valves

314 and 324 are closed to stop the supply of the WF ₆ gas and the H ₂ gas. At this time, with the APC valve 243 kept open, the inside of the processing chamber 201 is evacuated by the vacuum pump 246, and the WF ₆ gas and the H ₂ gas remaining in the processing chamber 201 are removed from the processing chamber 201. At this time, the

valves

514, 524 and 534 are kept open to maintain the supply of N ₂ gas into the processing chamber 201. The N ₂ gas acts as a purge gas, and the effect of removing WF ₆ gas and H ₂ gas from the processing chamber 201 after contributing to the formation of unreacted or W film remaining in the processing chamber 201 can be enhanced.

[Etch back process]
Subsequently, the step of etching back the W film is performed.

(O ₂ gas supply (continuous supply))
The valve 334 is opened to flow the O ₂ gas into the gas supply pipe 330. The flow rate of the O ₂ gas is adjusted by the MFC 332, and the O ₂ gas is supplied from the gas supply holes 430 a of the nozzle 430 into the processing chamber 201 and exhausted from the exhaust pipe 231. At this time, O ₂ gas is supplied to the wafer 200. At this time, the valve 534 may be simultaneously opened to flow an inert gas such as N ₂ gas into the gas supply pipe 530. The flow rate of the N ₂ gas flowing in the gas supply pipe 530 is adjusted by the MFC 532, and is supplied into the processing chamber 201 together with the WF ₆ gas and the H ₂ gas, and exhausted from the exhaust pipe 231. At this time, in order to prevent WF ₆ gas and H ₂ gas from entering the nozzle 430, the valves 514 and 524 are opened to flow N ₂ gas into the

gas supply pipes

510 and 520. The N ₂ gas is supplied into the processing chamber 201 through the

gas supply pipes

310 and 320 and the

nozzles

410 and 420, and is exhausted from the exhaust pipe 231.

At this time, the APC valve 243 is adjusted to set the pressure in the processing chamber 201 to, for example, a pressure in the range of 1 to 399 Pa. The supply amount of O ₂ gas controlled by the MFC 332 is, for example, in the range of 0.1 to 30 slm. The time for supplying the O ₂ gas to the wafer 200, ie, the gas supply time (irradiation time) is, for example, a time within the range of 1 to 3600 seconds. At this time, the temperature of the heater 207 is set such that the temperature of the wafer 200 is, for example, a temperature within the range of 300 to 600 ° C., preferably a temperature within the range of 350 to 500 ° C.

(NF ₃ gas supply (intermittent supply))
While flowing the O ₂ gas, the NF ₃ gas is intermittently (pulsed) supplied a plurality of times. Specifically, the

valves

614, 624, 634 are opened to flow NF ₃ gas into the

gas supply pipes

610, 620, 630, respectively. The flow rates of the NF ₃ gas are adjusted by the

MFCs

612, 622 and 632, respectively, supplied from the gas supply holes 410 a, 420 a and 430 a of the

nozzles

410, 420 and 430 into the processing chamber 201 and exhausted from the exhaust pipe 231. At this time, O ₂ gas and NF ₃ gas are supplied to the wafer 200. At this time, when the N ₂ gas is flowing in the

gas supply pipes

510, 520, and 530, the N ₂ gas is supplied into the processing chamber 201 together with the O ₂ gas and the NF ₃ gas and exhausted from the exhaust pipe 231.

At this time, the APC valve 243 is adjusted to set the pressure in the processing chamber 201 while supplying the NF ₃ gas to a pressure in the range of 1 to 3990 Pa, for example. The supply amount of NF ₃ gas controlled by the

MFCs

612, 622, and 632 is, for example, in the range of 0.1 to 10 slm. The time for supplying the NF ₃ gas to the wafer 200, ie, the gas supply time (irradiation time), makes one pulse, for example, a time within the range of 0.1 to 60 seconds. Further, the cumulative irradiation time (total irradiation time) of the NF ₃ gas is, for example, a time within the range of 0.1 to 3600 seconds. At this time, the temperature of the heater 207 is set to be equal to the temperature at the O ₂ supply step.

When the etch back of the predetermined film thickness is completed, the

valves

614, 624, 634 are closed, the supply of the NF ₃ gas is stopped, and finally, the above-described O ₂ supply step is performed.

(After purge and return to atmospheric pressure)
The N ₂ gas is supplied into the processing chamber 201 from each of the

gas supply pipes

510, 520, and 530 and exhausted from the exhaust pipe 231. The N ₂ gas acts as a purge gas, whereby the inside of the processing chamber 201 is purged with the inert gas, and the gas and byproducts remaining in the processing chamber 201 are removed from the inside of the processing chamber 201 (after purge). Thereafter, the atmosphere in the processing chamber 201 is replaced with the inert gas (inert gas substitution), and the pressure in the processing chamber 201 is returned to normal pressure (atmospheric pressure recovery).

(Wafer unloading)
Thereafter, the seal cap 219 is lowered by the boat elevator 115, and the lower end of the reaction tube 203 is opened. Then, the processed wafer 200 is carried out (boat unloading) from the lower end of the reaction tube 203 to the outside of the reaction tube 203 while being supported by the boat 217. Thereafter, the processed wafers 200 are taken out of the boat 217 (wafer discharging).

The results of the evaluation will be described using FIGS. As shown in FIG. 6, in the evaluation according to the present embodiment, the Si wafer (bare wafer) for evaluation is housed in the boat 217 so as to be positioned near the center of the processing chamber 201. In the upper part of the Si wafer were housed _SiO 2 / Si wafer was formed a SiO ₂ film on the Si wafer. In the lower part of the Si wafer, a W / TiN / Si wafer in which a TiN film and a W film are sequentially formed on a Si wafer is accommodated, and in the lower part, a TiN / Si wafer in which a TiN film is formed on a Si wafer is accommodated. did. A dummy wafer (Dummy) was accommodated in the upper stage of the SiO ₂ / Si wafer and the lower stage of the TiN / Si wafer for evaluation.

FIG. 7 shows the result of XPS (X-ray Photoelection Spectroscopy) analysis of a Si wafer. The evaluation in the case where the oxygen-containing gas was not used (not added) at the time of etch back is shown as a comparative example (dotted line) and shown in comparison with the evaluation (solid line) according to this embodiment. The XPS spectrum of W4f is shown, the horizontal axis shows the binding energy (BE (eV)), and the vertical axis shows the intensity of tungsten (W4f). From these results, it can be understood that W adheres on Si when etching is performed using only NF ₃ gas. This means that the W-containing substance (W-based gas) obtained by etching and gasifying the W / TiN / Si wafer reacts with the exposed Si, and W adheres on the Si. On the other hand, when O ₂ gas was added to the evaluation (NF ₃ gas) in the present embodiment, W was not detected on Si. This is considered to be because the reaction with the gasified W-containing substance described above was suppressed by the oxidation of Si by the added O ₂ gas to form SiO. As described above, by adding the oxygen-containing gas to the etching gas, it is possible to suppress the reaction of the etching gas with the gas-containing W-containing substance from reacting with the other exposed film.

(3) Effects of the Present Embodiment According to the present embodiment, one or more of the following effects can be obtained.
(A) By adding the oxygen-containing gas when supplying the etching gas, it is possible to improve the etch back efficiency and to improve the throughput.
(B) When Si is exposed at the time of etch back, by reacting Si with O to form SiO, the reaction with the etching gas is suppressed to suppress the etching of Si. it can.
(C) When AlO is exposed at the time of etch back, it is possible to suppress the reaction of AlO with the etching gas, and to suppress the formation of foreign matter by reacting with the elements contained in the etching gas.
(D) By continuously supplying an oxygen-containing gas at the time of etch back, even if a film other than the film to be etched is scraped by the etching gas, the reaction with the etching gas is minimized by immediately oxidizing it. be able to.
(E) High safety can be obtained by supplying an oxygen-containing gas at the time of etch back.
(F) Since etching can be performed little by little by intermittently supplying an oxygen-containing gas at the time of etch back, even if a film other than the film to be etched is scraped by the etching gas, etching is performed immediately by oxidation. Reaction with gas can be minimized.
(G) By supplying an oxygen-containing gas into the processing chamber prior to the etching gas at the start of etch back, the exposed Si can be oxidized to SiO that does not react with W, and the etching gas it can be of irradiation (supply) during generated W inclusions (W, Wx, WF _6, etc.) and Si can be suppressed that reacts.
(H) At the end of etch back, after stopping the etching gas, by supplying an oxygen-containing gas into the processing chamber, the remaining etching gas reacts with W to form WFx (WF ₆ or the like), Si can be maintained as SiO so as to suppress the reaction of WF x with Si.
(I) By supplying the etching gas into the processing chamber from all the nozzles, it becomes possible to improve the uniformity of the etching gas distribution in the processing chamber, and even in the processing furnace accommodating a plurality of substrates, between the substrates It is possible to improve the etch back uniformity.

Below, the modification of embodiment mentioned above is demonstrated. The same parts as the above-described embodiment will be omitted in detail and different parts will be described.

<Modification 1>
In the first modification of the above-described embodiment, as shown in FIG. 8A, the O ₂ gas supply (continuous supply) step in the above-described etch back process is performed, and the NF ₃ gas is supplied once. That is, O ₂ gas is flowed in the processing chamber 201 in a state where NF ₃ gas is not flowing, supply of NF ₃ gas is started after a predetermined time elapses, supply of NF ₃ gas is stopped after a predetermined time elapse, and processing is performed again The O ₂ gas is supplied into the processing chamber 201 in a state where the NF ₃ gas is not flowing in the chamber 201. The time for flowing the NF ₃ gas is shorter than the time for flowing the O ₂ gas. According to this modification, one or more effects of the effects of the above-described embodiment can be obtained.

<Modification 2>
In the second modification of the above-described embodiment, as shown in FIG. 8B, the step of O ₂ gas supply (continuous supply) in the above-described etch back process is performed, and NF ₃ gas is supplied once. That is, in the processing chamber 201 begins to conduct NF ₃ gas and _{O 2} gas at the same time, to stop the supply of the NF ₃ gas after a predetermined time has elapsed, _{O 2} in a state where no NF ₃ gas flows into the processing chamber 201 Gas is supplied into the processing chamber 201. The time for flowing the NF ₃ gas is shorter than the time for flowing the O ₂ gas.

According to this modification, one or more of the effects of the above-described embodiment can be obtained, and further, the following effects can be obtained.
(J) The processing time can be shortened by starting to flow the etching gas at the same timing as the oxygen-containing gas.

<Modification 3>
In the third modification of the above-described embodiment, as shown in FIG. 8C, the supply of O ₂ gas and the supply of NF ₃ gas are alternately repeated n ₁ times. At that time, during the supply of each gas, the residual gas in the processing chamber 201 is removed in the same procedure as the residual gas removal step in the W film formation process. That is, the O ₂ gas and the NF ₃ gas are intermittently supplied so as not to be mixed with each other.

According to this modification, one or more of the effects of the above-described embodiment can be obtained, and further, the following effects can be obtained.
(K) By intermittently supplying the oxygen-containing gas and the etching gas, the etching gas can flow to the processing chamber 201 in a state where the oxygen-containing gas is not flowing, so that the etching efficiency can be further improved. .

<Modification 4>
In the fourth modification of the embodiment described above, as shown in FIG. 8D, the step of supplying O ₂ gas (continuous supply) in the above-described etch back step is performed, and NF ₃ gas is supplied once. That is, O ₂ gas is flowed in the processing chamber 201 in a state where NF ₃ gas is not flowing, and supply of NF ₃ gas is started after a predetermined time elapses, and after predetermined time elapses, supply of NF ₃ gas and O ₂ gas is the same. Stop at the timing. The time for flowing the NF ₃ gas is shorter than the time for flowing the O ₂ gas.

According to this modification, one or more of the effects of the above-described embodiment can be obtained, and further, the following effects can be obtained.
(L) The processing time can be shortened by stopping the supply of the etching gas and the oxygen-containing gas at the same timing.

<Modification 5>
In the fifth modification of the embodiment described above, as shown in FIG. 8E, the fourth modification is repeated n ₂ times. At that time, the residual gas in the processing chamber 201 is removed in the same procedure as the residual gas removing step in the W film forming process for each cycle. That is, O ₂ gas is flowed in the processing chamber 201 in a state where NF ₃ gas is not flowing, and supply of NF ₃ gas is started after a predetermined time elapses, and after predetermined time elapses, supply of NF ₃ gas and O ₂ gas is the same. Stop at the timing. Then, after removing the residual gas in the processing chamber 201, the flow of the O ₂ gas is started again while the NF ₃ gas is not flowing in the processing chamber 201 again. The time for flowing the NF ₃ gas is shorter than the time for flowing the O ₂ gas.

According to this modification, one or more of the effects of the above-described embodiment can be obtained, and further, the following effects can be obtained.
(M) the WFx produced by reacting with an etching gas (WF _6, etc.) can be efficiently discharged.

<Modification 6>
In the sixth modification of the above-described embodiment, as shown in FIG. 8F, the O ₂ gas supply (continuous supply) step in the above-described etch back process is performed, and the NF ₃ gas is continuously supplied. That is, the flow starts to flow the NF ₃ gas O ₂ gas into the processing chamber 201 at the same timing, and after a predetermined time passes, the supply of the NF ₃ gas and the O ₂ gas is stopped at the same timing. The time for flowing the NF ₃ gas and the time for flowing the O ₂ gas are the same. According to this modification, one or more effects of the effects of the above-described embodiment can be obtained.

In the above-described embodiment, the example of etching back the W film has been described. However, the present invention is not limited thereto. For example, TiN film, tantalum nitride film (TaN film), cobalt film (Co film) The present invention can also be applied to the case of etching a film containing a metal element such as a film or a metal carbide film.

In the above embodiment, as the oxygen-containing gas, an example has been described using an _{O 2} gas, not limited to this, nitric oxide (NO), nitrous oxide _(N 2 O), water _(H 2 O), It is also possible to use ozone (O ₃ ) or the like.

In the above embodiment, an example has been described using the NF ₃ gas is a fluorine-containing gas as the etching gas is not limited thereto, it is possible to use also other gases containing a halogen element. In particular, a gas having a low etching rate to the oxide film is preferable.

Further, although the example applied to the control gate of the NAND-type flush memory has been described in the above embodiment, the present invention is not limited to this, and can be applied to a word line electrode of MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

While various typical embodiments and modifications of the present invention have been described above, the present invention is not limited to these embodiments and examples, and may be used in appropriate combination.

10 substrate processing apparatus 121 controller 200 wafer (substrate)
201 processing room

Claims

An oxygen-containing gas and a fluorine-containing etching gas are supplied to the substrate in which the second metal film is embedded in the opening in which the first metal film is formed on the surface, and the second metal film is etched back Etch back process,
Removing the oxygen-containing gas and the fluorine-containing etching gas;
And manufacturing a semiconductor device.
The method for manufacturing a semiconductor device according to claim 1, wherein the oxygen-containing gas is continuously supplied to the substrate and the fluorine-containing etching gas is intermittently supplied plural times in the etch back step.
The etch back process is
Supplying the oxygen-containing gas to the substrate;
Simultaneously supplying the oxygen-containing gas and the fluorine-containing etching gas to the substrate;
Supplying the oxygen-containing gas to the substrate;
The method for manufacturing a semiconductor device according to claim 1, wherein
The etch back process is
Simultaneously supplying the oxygen-containing gas and the fluorine-containing etching gas to the substrate;
Supplying the oxygen-containing gas to the substrate;
The method for manufacturing a semiconductor device according to claim 1, wherein
The etch back process is
Supplying the oxygen-containing gas to the substrate;
Removing the oxygen-containing gas;
Supplying the fluorine-containing etching gas to the substrate;
Removing the fluorine-containing etching gas;
The method of manufacturing a semiconductor device according to claim 1, wherein the process is repeated several times in order.
The etch back process is
Supplying the oxygen-containing gas to the substrate;
Simultaneously supplying the oxygen-containing gas and the fluorine-containing etching gas to the substrate;
The method for manufacturing a semiconductor device according to claim 1, wherein
The etch back process is
Supplying the oxygen-containing gas to the substrate;
Simultaneously supplying the oxygen-containing gas and the fluorine-containing etching gas to the substrate;
Removing the oxygen-containing gas and the fluorine-containing etching gas;
The method of manufacturing a semiconductor device according to claim 1, wherein the process is repeated several times in order.
The substrate is a silicon substrate, and in the etch back step, the silicon substrate is oxidized on the back surface of the substrate where the first metal film and the second metal film are not formed to form a silicon oxide film. A method of manufacturing a semiconductor device according to any one of claims 1 to 7.
The method for manufacturing a semiconductor device according to any one of claims 1 to 8, wherein the first metal film is a titanium nitride film, and the second metal film is a tungsten film.
The method for manufacturing a semiconductor device according to any one of claims 1 to 9, wherein the oxygen-containing gas is oxygen gas, and the fluorine-containing etching gas is nitrogen trifluoride gas.
A processing chamber for containing a substrate;
A gas supply system for supplying an oxygen-containing gas and a fluorine-containing etching gas to the processing chamber;
An exhaust system for exhausting the processing chamber;
The oxygen-containing gas is accommodated in the processing chamber in which the substrate having the second metal film embedded in the opening formed with the first metal film formed on the surface is controlled by controlling the gas supply system and the exhaust system. And a control unit configured to perform a process of etching back the second metal film by supplying the fluorine-containing etching gas, and a process of removing the oxygen-containing gas and the fluorine-containing etching gas.
Substrate processing apparatus having:
An oxygen-containing gas and a fluorine-containing etching gas are supplied to a substrate having a first metal film formed on its surface and having a second metal film embedded in a processing chamber of a substrate processing apparatus. And etching back the second metal film;
Removing the oxygen-containing gas and the fluorine-containing etching gas;
A program that causes a computer to execute the substrate processing apparatus.