JP5692337B2 - Film forming apparatus, film forming method, and storage medium - Google Patents

Description

  The present invention relates to a film forming apparatus for forming a thin film on a substrate in a vacuum vessel, a film forming method, and a storage medium storing this method.

  As one of film formation methods for forming a thin film on the surface of a substrate such as a semiconductor wafer, for example, a first reaction gas and a second reaction gas are alternately supplied to the substrate to generate a reaction of an atomic layer or a molecular layer. Known are ALD (Atomic Layer Deposition) and MLD (Molecular Layer Deposition) for stacking objects. In these film formation methods, for example, when the film formation temperature is low, organic substances in the reaction gas may be mixed as impurities into the thin film. Therefore, in order to remove such impurities from the thin film, a modification process such as an annealing process or a plasma process may be performed.

  However, since this plasma treatment can be modified only to the depth of the extreme surface layer of the thin film, a uniform modification effect cannot be obtained in the film thickness direction when the plasma treatment is performed after the thin film is formed. Further, in the case of using a plasma processing apparatus that performs plasma processing together with the film forming apparatus, the film forming process and the modification process are performed in each processing container, which requires a long time for stacking thin films. .

  On the other hand, as a so-called mini-batch type apparatus that performs such a film forming process on a plurality of wafers simultaneously, as described in, for example, Patent Documents 1 to 3, a plurality of the above-described reactive gases are supplied. 2. Description of the Related Art A film forming apparatus that performs a film forming process while rotating a mounting table on which a plurality of wafers are mounted relative to a reactive gas supply unit is known. However, these patent documents do not specifically examine the aforementioned problems.

US Pat. No. 7,153,542: FIGS. 8 (a) and 8 (b) Japanese Patent No. 3144664: FIG. 1, FIG. 2, Claim 1 US Pat. No. 6,634,314

  The present invention has been made in view of such circumstances, and an object of the present invention is to relatively rotate a reaction gas supply means for supplying a reaction gas to a table on which a substrate is placed to thereby rotate a reaction product. An object of the present invention is to provide a film forming apparatus, a film forming method, and a storage medium storing the method, which can form a thin film having a good film quality in the film thickness direction and a uniform thin film.

The film forming apparatus of the present invention
A table provided in a vacuum vessel and having a substrate placement region for placing a substrate;
First reaction gas supply means for supplying a first reaction gas adsorbed on the surface of the substrate to a first processing region in the vacuum vessel;
A second reaction which is provided at a position spaced in the circumferential direction of the table with respect to the first reaction gas supply means and reacts with a component of the first reaction gas on the surface of the substrate to generate a reaction product. A second reactive gas supply means for supplying a gas to a second processing region in the vacuum vessel;
In order to modify the reaction product on the substrate, the plasma obtained by converting the reformed gas into plasma is provided at a position spaced apart from the second reactant gas supply means in the circumferential direction of the table. Plasma processing means for supplying a plasma processing region in the vacuum vessel;
A rotating mechanism for relatively rotating the table and the first reactive gas supply means, the second reactive gas supply means and the plasma processing means;
A film forming-modifying step for performing a plurality of steps in which the substrate on the table passes through the first processing region, the second processing region, and the plasma processing region in this order, and the film forming process are stopped. And a reforming step in which the substrate on the table passes through the plasma processing region, and control means for outputting a control signal so as to perform at least once in this order.

The control means aligns the supply amount of the second reaction gas between these steps in order to suppress pressure fluctuations in the vacuum vessel at the time of switching from the film formation-modification step to the modification step. In this way, a control signal may be output.
In the modification step, the first reaction gas supply unit, the second reaction gas supply unit, and the second reaction gas supply unit with respect to the table so that the substrate on the table passes through the plasma processing region a plurality of times. It may be a step of relatively rotating the plasma processing means a plurality of times. The reformed gas is at least one of a rare gas and an O2 gas. The degree of reforming in the reforming step is larger than that in the film-forming step.

The film forming method of the present invention comprises:
A step of placing a substrate on a substrate placement region of a table provided in a vacuum vessel;
Next, the table is rotated relative to the first reaction gas supply unit, the second reaction gas supply unit, and the plasma processing unit that are spaced apart from each other in the circumferential direction of the table by using a rotation mechanism. A process of
A first processing region to which a first reaction gas is supplied from the first reaction gas supply unit; a second processing region to which a second reaction gas is supplied from the second reaction gas supply unit; and A film-forming step for performing a plurality of steps in which a substrate on the table passes through a plasma processing region to which plasma generated by plasma-forming of the reformed gas is supplied in this order, and a film-forming process. And a step of performing a modification step in which the substrate on the table passes through the plasma processing region at least once in this order.
In order to suppress pressure fluctuations in the vacuum vessel at the time of switching from the film-forming step to the reforming step, the second reaction gas supply amount between these steps may be uniform.

The storage medium of the present invention is
A substrate is placed on a substrate placement region on a table in a vacuum vessel, and at least two kinds of reaction gases are sequentially supplied to the substrate, and a layer of reaction products is stacked by executing this supply cycle a plurality of times. In a storage medium storing a computer program used in a film forming apparatus for forming a thin film,
In the computer program, steps are set so as to perform any one of the film forming methods.

  The present invention rotates the first reactive gas supply means, the second reactive gas supply means, and the plasma processing means relative to the table on which the substrate is placed, and the first reactive gas on the substrate surface. A film forming process for reacting the above components with the second reaction gas to generate a reaction product, and a film forming-modifying step for performing a reforming process for modifying the reaction product with plasma in this order; And the reforming step of performing the reforming process by rotating the table and the plasma processing means relatively and stopping the supply of the reactive gas 1 in this order. A thin film having a good and uniform film quality can be obtained.

FIG. 4 is a vertical cross-sectional view taken along the line I-I ′ of FIG. 3 showing a vertical cross section of the film forming apparatus according to the embodiment of the present invention. It is a perspective view which shows schematic structure inside the said film-forming apparatus. It is a cross-sectional plan view of the film forming apparatus. It is a longitudinal cross-sectional view which shows a schematic structure of a part inside the said film-forming apparatus. It is an expansion perspective view which shows an example of the activated gas injector of this invention. It is a longitudinal cross-sectional view which shows the activated gas injector provided in the said film-forming apparatus. It is a longitudinal cross-sectional view of the film-forming apparatus which shows the said activated gas injector. It is a schematic diagram which shows the mode of the thin film produced | generated by modification | reformation in the said film-forming apparatus. It is the schematic which shows an example of the gas supply sequence of each step performed in the said film-forming apparatus. It is the schematic which shows an example of the gas supply sequence of each step performed in the said film-forming apparatus. It is a schematic diagram which shows the flow of the gas in the said film-forming apparatus. It is a characteristic view obtained in the Example of this invention.

  As shown in FIG. 1 (a cross-sectional view taken along line II ′ in FIG. 3), a film forming apparatus as an example of an embodiment of the present invention includes a flat vacuum container 1 having a substantially circular planar shape, The rotary table 2 is provided in the vacuum vessel 1 and has a rotation center at the center of the vacuum vessel 1. The vacuum vessel 1 is configured such that the top plate 11 can be separated from the vessel body 12. The top plate 11 is pressed against the container main body 12 via a seal member provided on the upper end surface of the container main body 12, for example, an O-ring 13, and maintains an airtight state. Is separated upward from the container body 12 by a drive mechanism (not shown).

  The rotary table 2 is fixed to a cylindrical core portion 21 at the center, and the core portion 21 is fixed to the upper end of a rotary shaft 22 extending in the vertical direction. The rotating shaft 22 passes through the bottom surface portion 14 of the vacuum vessel 1, and a lower end thereof is attached to a driving unit 23 that is a rotating mechanism that rotates the rotating shaft 22 around the vertical axis in this example in the clockwise direction. The rotating shaft 22 and the drive unit 23 are accommodated in a cylindrical case body 20 whose upper surface is open. The case body 20 has a flange portion provided on the upper surface thereof attached to the lower surface of the bottom surface portion 14 of the vacuum vessel 1 in an airtight manner, and the airtight state between the internal atmosphere and the external atmosphere of the case body 20 is maintained.

  As shown in FIGS. 2 and 3, a plurality of, for example, five semiconductor wafers (hereinafter referred to as “wafers”) W are placed on the surface of the turntable 2 along the rotation direction (circumferential direction). For this purpose, a circular recess 24 is provided. In FIG. 3, the wafer W is drawn only in one recess 24 for convenience. The recess 24 has a diameter slightly larger than the diameter of the wafer W, for example, 4 mm, and the depth is set to be equal to the thickness of the wafer W. Therefore, when the wafer W is dropped into the recess 24, the surface of the wafer W and the surface of the turntable 2 (region where the wafer W is not placed) are aligned. On the bottom surface of the recess 24, a through hole (not shown) through which, for example, three lifting pins for supporting the back surface of the wafer W to raise and lower the wafer W is formed. The recess 24 is for positioning the wafer W so that it does not pop out due to the centrifugal force associated with the rotation of the turntable 2, and corresponds to the substrate mounting area of the present invention.

  As shown in FIG. 2 and FIG. 3, there are a first reactive gas nozzle 31 and a second reactive gas nozzle 32 made of, for example, quartz, respectively, The separation gas nozzles 41 and 42 and the activated gas injectors 220 are radially arranged at intervals in the circumferential direction of the vacuum vessel 1 (the rotation direction of the rotary table 2). In this example, the activated gas injector 220, the separation gas nozzle 41, the first reaction gas nozzle 31, the separation gas nozzle 42, and the second reaction gas nozzle 32 are clockwise (as viewed in the rotation direction of the turntable 2) as viewed from a later-described transfer port 15. Are arranged in this order, and the activated gas injector 220 and the nozzles 31, 32, 41, 42 are introduced into the vacuum vessel 1 from the outer peripheral wall of the vacuum vessel 1, for example, at the rotation center of the rotary table 2. It is attached so as to extend horizontally facing the wafer W. Gas introduction ports 31 a, 32 a, 41 a, 42 a that are the base ends of the nozzles 31, 32, 41, 42 penetrate the outer peripheral wall of the vacuum vessel 1. The reaction gas nozzles 31 and 32 constitute first reaction gas supply means and second reaction gas supply means, respectively, and the separation gas nozzles 41 and 42 each constitute separation gas supply means. The activated gas injector 220 will be described in detail later.

  The first reaction gas nozzle 31 and the second reaction gas nozzle 32 respectively supply a first reaction gas containing Si (silicon), for example, a gas source of diisopropylaminosilane gas, and a second reaction via a flow rate adjustment valve (not shown). Gases such as O3 (ozone) gas and O2 (oxygen) gas mixed gas supply sources (both not shown) are connected to each other, and the separation gas nozzles 41 and 42 are connected via a flow rate adjusting valve or the like. It is connected to a gas supply source (not shown) of N2 (nitrogen) gas which is a separation gas. In the following description, the second reaction gas will be described as O3 gas for convenience.

  In the reaction gas nozzles 31, 32, the gas discharge holes 33 are arranged at regular intervals with an interval of, for example, 10 mm over the length direction of the nozzles. The lower regions of the reaction gas nozzles 31 and 32 are used to react the first processing region P1 for adsorbing the Si-containing gas onto the wafer W and the Si-containing gas on the wafer W adsorbed on the wafer W, respectively. This becomes the second processing region P2. The reactive gas nozzles 31 and 32 are provided in the vicinity of the wafer W so as to be separated from the ceiling surface 45 in the processing regions P1 and P2.

  The separation gas nozzles 41 and 42 are for forming a separation region D that separates the first processing region P1 and the second processing region P2, and the top plate 11 of the vacuum vessel 1 in the separation region D is provided on the top plate 11. As shown in FIG. 2 and FIG. 3, the planar shape formed by dividing the circle drawn around the rotation center of the turntable 2 and along the vicinity of the inner peripheral wall of the vacuum vessel 1 in the circumferential direction is a fan shape and is downward. A protruding portion 4 is provided. The separation gas nozzles 41 and 42 are accommodated in a groove 43 formed so as to extend in the radial direction of the circle at the center of the convex portion 4 in the circumferential direction of the circle.

For example, a flat low ceiling surface 44 (first ceiling surface) that is the lower surface of the convex portion 4 exists on both sides in the circumferential direction of the separation gas nozzles 41 and 42, and both sides of the ceiling surface 44 in the circumferential direction are present. The ceiling surface 45 (second ceiling surface) higher than the ceiling surface 44 exists. The role of the convex portion 4 is a narrow space for preventing the first reactive gas and the second reactive gas from entering the rotary table 2 and preventing the mixing of the reactive gases. It is to form a space.
That is, taking the separation gas nozzle 41 as an example, the second reactive gas is prevented from entering from the upstream side in the rotational direction of the turntable 2, and the first reactive gas is prevented from entering from the downstream side in the rotational direction. To do. The separation gas is not limited to nitrogen (N2) gas, and an inert gas such as argon (Ar) gas may be used.

  On the other hand, on the lower surface of the top plate 11, as shown in FIG. 4, a protruding portion 5 is provided so as to face a portion on the outer peripheral side of the core portion 21 in the rotary table 2 and along the outer periphery of the core portion 21. It has been. The projecting portion 5 is formed continuously with the portion on the rotation center side of the convex portion 4, and the lower surface thereof is formed at the same height as the lower surface (ceiling surface 44) of the convex portion 4. 2 and 3 show the top plate 11 cut horizontally at a position lower than the ceiling surface 45 and higher than the separation gas nozzles 41 and 42.

  The lower surface of the top plate 11 of the vacuum vessel 1, that is, the ceiling surface viewed from the wafer placement area (recessed portion 24) of the rotary table 2 is the first ceiling surface 44 and the second higher than the ceiling surface 44 as described above. FIG. 1 shows a longitudinal section of a region where the high ceiling surface 45 is provided, and FIG. 4 shows a region where the low ceiling surface 44 is provided. The longitudinal section about is shown. As shown in FIGS. 2 and 4, the peripheral portion of the fan-shaped convex portion 4 (the portion on the outer edge side of the vacuum vessel 1) is bent in an L shape so as to face the outer end surface of the rotary table 2. Thus, a bent portion 46 is formed. Since the fan-shaped convex portion 4 is provided on the top plate 11 side and can be detached from the container main body 12, there is a slight gap between the outer peripheral surface of the bent portion 46 and the container main body 12. There is. The bent portion 46 is also provided for the purpose of preventing the reaction gas from entering from both sides in the same manner as the convex portion 4 and preventing the mixture of both reaction gases. The inner peripheral surface of the bent portion 46 and the rotary table are provided. 2 and the clearance between the outer peripheral surface of the bent portion 46 and the container body 12 are set to the same dimensions as the height of the ceiling surface 44 with respect to the surface of the turntable 2, for example.

  As shown in FIG. 4, the inner peripheral wall of the container main body 12 is formed on a vertical surface close to the outer peripheral surface of the bent portion 46 as shown in FIG. 4. For example, the vertical cross-sectional shape is cut out in a rectangular shape from the portion facing the outer end surface of the turntable 2 to the bottom surface portion 14 and is recessed outward. When the regions communicating with the first processing region P1 and the second processing region P2 described above in the depressed portion are referred to as a first exhaust region E1 and a second exhaust region E2, respectively, As shown in FIGS. 1 and 3, a first exhaust port 61 and a second exhaust port 62 are formed at the bottoms of the exhaust region E1 and the second exhaust region E2, respectively. As shown in FIG. 1, the first exhaust port 61 and the second exhaust port 62 are each connected to, for example, a vacuum pump 64 that is a vacuum exhaust unit via an exhaust pipe 63. In FIG. 1, 65 is a pressure adjusting means.

  As shown in FIGS. 1 and 4, a heater unit 7 serving as a heating unit is provided in the space between the turntable 2 and the bottom surface portion 14 of the vacuum vessel 1. The wafer W is heated to a temperature determined by the process recipe, for example, 450 ° C. On the lower side near the periphery of the turntable 2, the atmosphere from the upper space of the turntable 2 to the exhaust areas E 1 and E 2 and the atmosphere in which the heater unit 7 is placed are partitioned and below the turntable 2. In order to suppress intrusion of gas into the region, a ring-shaped cover member 71 is provided so as to surround the heater unit 7 over the entire circumference. The cover member 71 includes an outer member of the turntable 2 and an inner member 71a provided so as to face the outer peripheral side of the outer edge from the lower side, and between the inner member 71a and the inner wall surface of the vacuum vessel 1. An outer member 71b provided. The outer member 71b is cut, for example, in an arc shape in order to connect the exhaust ports 61 and 62 and the upper region of the rotary table 2 above the exhaust ports 61 and 62 described above, and the exhaust regions E1 and E2 The lower end of the bent portion 46 is arranged so that the upper end surface is close to the bent portion 46.

  The bottom surface portion 14 in a portion closer to the rotation center than the space where the heater unit 7 is disposed protrudes upward so as to approach the core portion 21 near the center portion of the lower surface of the turntable 2 to form a protrusion 12a. ing. The space between the projecting portion 12a and the core portion 21 is a narrow space, and the clearance between the inner peripheral surface and the rotating shaft 22 is narrower with respect to the through hole of the rotating shaft 22 that passes through the bottom surface portion 14. These narrow spaces communicate with the inside of the case body 20. The case body 20 is provided with a purge gas supply pipe 72 for supplying N2 gas as a purge gas into the narrow space for purging. Further, a purge gas supply pipe 73 for purging the arrangement space of the heater unit 7 is provided on the bottom surface portion 14 of the vacuum vessel 1 at a plurality of positions in the circumferential direction at a position below the heater unit 7. Between the heater unit 7 and the turntable 2, in order to suppress the intrusion of gas into the region where the heater unit 7 is provided, the upper end portion of the protruding portion 12 a from the inner peripheral wall of the outer member 71 b described above A covering member 7a made of, for example, quartz is provided to connect between the two in the circumferential direction.

  Further, a separation gas supply pipe 51 is connected to the central portion of the top plate 11 of the vacuum vessel 1 so that N2 gas as separation gas is supplied to a space 52 between the top plate 11 and the core portion 21. Has been. The separation gas supplied to the space 52 is discharged toward the periphery along the surface of the turntable 2 on the wafer mounting region side through a narrow gap 50 between the protruding portion 5 and the turntable 2. Become. Since the space surrounded by the protrusion 5 is filled with the separation gas, the reaction gas (Si-containing) is interposed between the first processing region P1 and the second processing region P2 via the center of the turntable 2. Gas and O3 gas) are prevented from mixing.

  Further, as shown in FIGS. 2 and 3, a transfer port 15 for transferring a wafer W as a substrate between the external transfer arm 10 and the rotary table 2 is formed on the side wall of the vacuum vessel 1. The transport port 15 is opened and closed by a gate valve (not shown). Further, since the wafer 24 is transferred to and from the transfer arm 10 at the position facing the transfer port 15 in the recess 24 which is a wafer placement area on the rotary table 2, the transfer position is below the rotary table 2. Are provided with lifting pins for passing through the recess 24 to lift the wafer W from the back surface and lifting mechanisms (both not shown).

  Next, the aforementioned activated gas injector 220 will be described in detail. The activated gas injector 220 generates plasma from the center side of the turntable 2 to the outer peripheral side of the turntable 2 in the substrate placement region on which the wafer W is placed, for example, the reaction of Si-containing gas and O3 gas. The silicon oxide film (SiO2 film), which is a reaction product formed on the wafer W, is modified every time the turntable 2 rotates. As shown in FIGS. 5 and 6, this activated gas injector 220 is a gas introduction nozzle that constitutes a reformed gas supply means made of, for example, quartz in order to supply a reformed gas for generating plasma into the vacuum vessel 1. 34 is provided. A pair of rod-like sheath tubes 35a and 35b parallel to each other in order to turn the reformed gas introduced from the gas introduction nozzle 34 into the plasma downstream of the gas introduction nozzle 34 in the rotation direction of the turntable 2. A plasma processing means 80 is provided. In this example, a plurality of sets, for example, two sets of plasma processing means 80 are provided so as to be parallel to each other, and the respective plasma processing means 80 and 80 are arranged so that their length dimensions are equal to each other. .

  The gas introduction nozzle 34 and the plasma processing means 80, 80 are arranged on the outer periphery of the vacuum container 1 so as to be parallel to the wafer W on the turntable 2 and to be orthogonal to the rotation direction of the turntable 2. The base end portion 80a provided on the surface is inserted into the vacuum vessel 1 in an airtight manner toward the central portion of the turntable 2. In FIG. 6, 341 are gas holes provided at a plurality of locations along the length direction of the gas introduction nozzle 34.

  As shown in FIG. 3 described above, one end side of a plasma gas introduction path 251 for supplying a reforming gas for generating plasma is connected to the gas introduction nozzle 34, and the other end side of the plasma gas introduction path 251 is connected. Is connected via a valve 252 and a flow rate adjusting unit 253 to a plasma generation gas source 254 in which a reforming gas for generating plasma, such as O 2 gas, for generating plasma is stored. As the reformed gas, a rare gas such as Ar (argon) gas or He (helium) gas may be used instead of or together with the O2 gas.

  The sheath tubes 35a and 35b in each plasma processing means 80 are made of, for example, quartz, alumina (aluminum oxide), or yttria (yttrium oxide, Y2O3). Further, in these sheath tubes 35a and 35b, as shown in FIG. 6, electrodes 36a and 36b made of, for example, nickel alloy or titanium are respectively inserted to form parallel electrodes. As shown in FIG. 3, the high frequency power of 13.56 MHz, for example, 500 W is supplied to 36 b in parallel from the high frequency power source 224 outside the vacuum vessel 1 via the matching unit 225. In FIG. 2, reference numeral 37 denotes a protective tube connected to the base end side (the inner wall side of the vacuum vessel 1) of the sheath tubes 35 a and 35 b, and drawing is omitted in FIG. 5 and the like. Except for FIG. 6, the sheath tubes 35a and 35b are simplified.

  In FIG. 5, reference numeral 221 denotes a cover body arranged so as to cover the region where the gas introduction nozzle 34 and the sheath tubes 35a and 35b are arranged from the upper side and side surfaces (both side surfaces in the long side direction and the short side direction). The cover body 221 is made of an insulator such as quartz. Further, in FIG. 5, reference numeral 222 denotes an air flow regulating surface that extends horizontally in a flange shape from the lower ends of both side surfaces of the cover body 221 along the length direction of the activated gas injector 220. The gap dimension t between the lower end surface of the air flow regulating surface 222 and the upper surface of the turntable 2 is small in order to suppress the intrusion of O3 gas or N2 gas flowing from the upstream side into the inner region of the cover body 221. Further, the width dimension u is formed so as to increase from the center side of the turntable 2 toward the outer peripheral side of the turntable 2 where the gas flow becomes faster. In FIG. 7, reference numeral 223 denotes support members provided at a plurality of positions between the cover body 221 and the top plate 11 of the vacuum vessel 1 in order to support the cover body 221, and the positions thereof are schematically shown. Yes.

  In addition, the film forming apparatus is provided with a control unit 100 including a computer for controlling the operation of the entire apparatus as a control unit. The memory of the control unit 100 rotates as described later. A film forming-modifying step (first step) for performing the film forming process and the reforming process each time the table 2 rotates, and a reforming step (second step) for performing only the reforming process each time the rotary table 2 rotates. ) Are stored in this order. That is, in this memory, the processing time ratio (T1 / T2) and the film formation-modification step are defined by assuming that the processing times of the film formation-modification step and the modification step are T1 and T2, respectively. The processing cycle time (T1 + T2) including the step and the reforming step, the number of processing cycles, and the like are stored. This program has a set of steps so as to execute the operation of the apparatus described later, and is installed in the control unit 100 from the storage unit 101 such as a hard disk, a compact disk, a magneto-optical disk, a memory card, or a flexible disk.

  Next, the operation of the above embodiment will be described. First, a gate valve (not shown) is opened, and the wafer W is transferred from the outside to the recess 24 of the turntable 2 through the transfer port 15 by the transfer arm 10. This delivery is performed by raising and lowering a lifting pin (not shown) from the bottom side of the vacuum vessel 1 through the through hole on the bottom surface of the recess 24 when the recess 24 stops at a position facing the transport port 15. The delivery of the wafer W is performed by intermittently rotating the turntable 2, and the wafer W is placed in each of the five recesses 24 of the turntable 2. Subsequently, the gate valve is closed and the inside of the vacuum vessel 1 is pulled out by the vacuum pump 64, and then the inside of the vacuum vessel 1 is adjusted to a preset processing pressure by the pressure adjusting means 65, and the rotary table 2 is rotated clockwise. For example, the wafer W is heated to 450 ° C., for example, by the heater unit 7 while rotating at 20 rpm. Further, the Si-containing gas and the O3 gas are discharged from the reaction gas nozzles 31 and 32, respectively, and the O2 gas is discharged from the gas introduction nozzle 34 at a predetermined flow rate, for example, 5 slm, to be 13.56 MHz between the sheath tubes 35a and 35b. Power is supplied at a high frequency of 400W. Further, N2 gas, which is a separation gas, is discharged from the separation gas nozzles 41 and 42 at a predetermined flow rate, and N2 gas is also discharged from the separation gas supply pipe 51 and the purge gas supply pipes 72 and 72 at a predetermined flow rate.

At this time, in the activated gas injector 220, the O 2 gas discharged from the gas introduction nozzle 34 through the gas holes 341 toward the sheath tubes 35a and 35b is supplied to the region between the sheath tubes 35a and 35b. When activated by the generated high frequency, plasma such as O ⁻ ions and O radicals is generated. This plasma (active species) descends toward the wafer W that moves (rotates) together with the rotary table 2 on the lower side of the activated gas injector 220.

  On the other hand, due to the rotation of the turntable 2, the Si-containing gas is adsorbed on the surface of the wafer W in the first processing region P1, and then the Si-containing gas adsorbed on the wafer W in the second processing region P2 is oxidized. The molecular layer of the silicon oxide film is formed in one or more layers, and the reaction product is deposited. This silicon oxide film may contain impurities such as moisture (OH group) or organic matter because of residual groups contained in, for example, a Si-containing gas. When the wafer W reaches the modified region 150, which is the lower region of the activated gas injector 220, the silicon oxide film is modified by the plasma. Specifically, as schematically shown in the left side of FIG. 8, the film formation process and the modification process, for example, when the plasma collides with the surface of the wafer W, the impurities are released from the silicon oxide film, for example. In other words, the elements in the silicon oxide film are rearranged so that the silicon oxide film is densified (densified). In this way, by rotating the turntable 2 for a total of two times, that is, by performing a film formation-modification step including a film formation process and a modification process for, for example, 6 seconds, a predetermined film thickness, for example, 0 is applied to the surface of the wafer W. A reaction product of .25 nm is formed.

Here, for example, depending on the supply amount of each reaction gas, the film thickness of a reaction product formed every film formation process (every rotation of the turntable 2), the number of rotations of the turntable 2, etc. In this reforming treatment, the reaction product may not be sufficiently reformed. That is, the reaction product formed on the wafer W by the above-described film formation-modification step may still contain impurities or the silicon oxide film may not be sufficiently densified. . Therefore, in order to sufficiently modify the reaction product formed on the wafer W in this film formation-modification step, the following modification step is performed.
Specifically, the supply amounts of the respective gases from the second reaction gas nozzle 32, the gas introduction nozzle 34, the separation gas nozzles 41 and 42, and the supply pipes 51 and 72 are the same as those in the above-described film-forming step. The supply of the Si-containing gas from the first reaction gas nozzle 31 is stopped while maintaining the above. At this time, since the supply amount of the Si-containing gas is smaller than the supply amount of the separation gas and the O3 gas, when the film formation-reforming step is switched to the reforming step (when the supply of the Si-containing gas is stopped). The pressure fluctuation in the vacuum vessel 1 can be suppressed.

  When the supply of the Si-containing gas is stopped, the Si-containing gas is quickly exhausted from the vacuum vessel 1 to the outside by the separation gas, and the Si-containing gas slightly remaining in the first reaction gas nozzle 31 is similarly applied. The air is quickly exhausted to the outside through the inner region of the vacuum vessel 1. Therefore, it can be said that the first processing region P1 is not formed in the vacuum vessel 1 in this reforming step. Therefore, the wafer W on the turntable 2 passes through the second processing region P2 and the modified region 150 in this order by the rotation of the turntable 2.

  In the second processing region P2, when the reaction product on the surface of the wafer W has already been oxidized, the wafer W is not adversely affected. On the other hand, in the modified region 150, as described above, a modification process is performed in which impurities are discharged from the reaction product on the surface of the wafer W, or the elements in the silicon oxide film are rearranged. Thus, by rotating the turntable 2 for 6 times, that is, by performing the modification step for 18 seconds, for example, the reaction product on the surface of the wafer W is exposed to the plasma a plurality of times. -The degree of reforming is greater than the reforming process in the reforming step. In addition, since the reaction product at this time has a thin film thickness as described above, the modification treatment by plasma is uniformly performed in the film thickness direction.

  Therefore, as schematically shown on the right side of FIG. 8, the rearrangement of the elements described above also occurs between the reaction products stacked in the vertical direction (Nth layer and (N + 1) th layer). A reaction product having a uniform film quality in the direction is formed. At this time, when the processing times in the film-forming step and the reforming step are T1 and T2, respectively, the ratio of these processing times (T1 / T2) is, for example, 1/3 (6 seconds / 18 seconds). . Further, the time (T1 + T2) of the processing cycle including these film formation-modification step and the modification step is, for example, 24 seconds (6 seconds + 18 seconds). Here, when such a processing cycle is viewed from the gas supply side, Si-containing gas is intermittently supplied as shown in FIG. 9, while O3 gas and plasma (O2 gas) have a plurality of processing cycles. Will continue to be supplied at the same flow rate. Further, when the processing cycle is viewed from a certain wafer W on the turntable 2, as shown in FIG. 10, in the film forming / modifying step, the supply of each gas and plasma is sequentially performed a plurality of times, and the modification is performed. In the quality step, the supply of each gas other than the Si-containing gas and the plasma is performed a plurality of times in order.

  Then, by performing this treatment cycle a plurality of times, for example, 40 times, a plurality of reaction products that have been successfully modified as described above are laminated to form a thin film with a good and uniform film quality in the film thickness direction. It is formed. Here, since the five wafers W are placed on the turntable 2 in the circumferential direction, Si-containing gas is supplied to each of the wafers W when, for example, the film formation-modification step is started. When the O3 gas or plasma is first supplied before, or when switching from the film forming-modifying step to the modifying step, for example, the Si-containing gas may be supplied only to an intermediate portion in the plane of the wafer W. . Therefore, for example, in one processing cycle, there may be slight variations in film thickness between wafers W or within the surface of one wafer W. However, by performing the processing cycle a plurality of times in this way, the number of gas supply and the supply site are leveled within and between the surfaces of the wafer W, so that variations in processing are alleviated and uniform film thickness and film quality are achieved. A thin film is formed.

  At this time, since the separation region D is not provided between the activated gas injector 220 and the second reactive gas nozzle 32 in the vacuum container 1, the activated gas injector 220 is drawn by the rotation of the rotary table 2. O3 gas and N2 gas flow from the upstream side toward However, since the cover body 221 is provided so as to cover each plasma processing means 80 and the gas introduction nozzle 34 as described above, the lower side of the cover body 221 (between the air flow regulating surface 222 and the turntable 2). The area above the cover body 221 is wider than the gap t). In addition, since the reformed gas is supplied from the gas introduction nozzle 34 to the inner region of the cover body 221, the inner region is slightly more positive than the outside (inside the vacuum vessel 1). Therefore, the gas flowing from the upstream side in the rotation direction of the turntable 2 is less likely to enter the lower side of the cover body 221. Further, since the gas flowing toward the activated gas injector 220 is drawn from the upstream side by the rotation of the turntable 2, the flow velocity becomes faster as it goes from the radially inner periphery side to the outer periphery side of the turntable 2. However, since the width dimension u of the air flow regulating surface 222 on the outer peripheral side is larger than the inner peripheral side of the turntable 2, the gas to the inside of the cover body 221 extends in the length direction of the activated gas injector 220. Intrusion is suppressed. Accordingly, the gas flowing from the upstream side toward the activated gas injector 220 flows to the exhaust port 62 on the downstream side through the upper region of the cover body 221 as shown in FIG. Therefore, since these O3 gas and N2 gas are hardly affected by activation or the like due to high frequency, for example, generation of NOx or the like is suppressed, and corrosion of members constituting the vacuum vessel 1 is suppressed. Further, the wafer W is hardly affected by these gases. The impurities discharged from the silicon oxide film by the reforming process are then gasified and exhausted toward the exhaust port 62 together with O2 gas and N2 gas.

  Further, since N2 gas is supplied between the first processing region P1 and the second processing region P2 and N2 gas which is a separation gas is also supplied to the central region C, as shown in FIG. For example, in the film forming / modifying step, each gas is exhausted so that the Si-containing gas and the O3 gas are not mixed.

In this example, the inner peripheral wall of the container main body 12 along the space below the second ceiling surface 45 where the reaction gas nozzles 31 and 32 and the activated gas injector 220 are disposed is the inner wall as described above. Since the peripheral wall is notched and widened, and the exhaust ports 61 and 62 are located below the wide space, the narrow space below the first ceiling surface 44 and each of the central region C The pressure in the space below the second ceiling surface 45 is lower than the pressure.
Since the lower side of the turntable 2 is purged with N2 gas, the gas flowing into the exhaust region E passes through the lower side of the turntable 2 and, for example, Si-containing gas flows into the O3 gas supply region. There is no fear.

  Here, an example of the processing parameters will be described. The rotation speed of the turntable 2 is, for example, 1 rpm to 500 rpm when the wafer W having a diameter of 300 mm is used as the substrate to be processed, the process pressure is 1067 Pa (8 Torr), and the Si-containing gas. And the flow rates of O3 gas are, for example, 100 sccm and 10000 sccm, respectively, the flow rate of N2 gas from the separation gas nozzles 41 and 42 is, for example, 20000 sccm, and the flow rate of N2 gas from the separation gas supply pipe 51 at the center of the vacuum vessel 1 is, for example, 5000 sccm. . Further, the number of reaction gas supply cycles for one wafer W varies depending on the target film thickness, but is, for example, 1000 times.

  According to the above-described embodiment, the turntable 2 is rotated to adsorb the Si-containing gas onto the wafer W, and then the Si-containing gas adsorbed onto the surface of the wafer W is supplied by supplying O3 gas to the surface of the wafer W. After performing a film forming-reforming step consisting of a film forming process for reacting to form a silicon oxide film and a reforming process for modifying the silicon oxide film using plasma, A reforming step is performed in which the supply is stopped and the silicon oxide film is reformed using plasma. Therefore, a thin film having a good and uniform film thickness can be obtained in the film thickness direction. Further, since the ratio of the processing time of each step (T1 / T2) and the time of the processing cycle (T1 + T2) are adjusted, the degree of modification of the thin film (reaction product) is adjusted over a wide range. be able to. Therefore, for example, the number of film forming processes in the film forming-modifying step is reduced (the processing time T1 is shortened), the processing time T2 in the modifying step is increased, or the processing cycle time (T1 + T2) is shortened. By thinning the reaction product formed in one processing cycle, the degree of plasma reforming effect can be increased. For this reason, as shown in the examples described later, for example, it is the same as the thermal oxide film. It is possible to form a thin film having a film quality.

  At this time, for example, when the film forming process and the reforming process are performed for each rotation of the turntable 2 using only the film forming-modifying step without performing the reforming step, the reaction product on the lower layer side After the reforming treatment is performed, a reaction product on the upper layer side is newly formed on the reaction product, and thereafter, these treatments are alternately performed so that the reaction products are stacked in multiple layers. Become. Therefore, since the modification by the plasma occurs only up to the extreme surface layer of the wafer W, there is a possibility that the reaction product is laminated in a multilayer state in a state where the modification is insufficient. Therefore, in order to reliably modify the reaction product, for example, sufficient reforming is performed in a very short time before the wafer W passes through the reforming region 150 before the upper-layer reaction product is stacked. It is preferable to carry out the treatment.

  Therefore, for example, in order to sufficiently modify the reaction products formed by various recipes as well, that is, to secure a wide range in which the reaction products (thin films) can be well modified by this film forming apparatus. In this case, for example, the high-frequency output supplied from the high-frequency power source 224 to the plasma processing unit 80 is increased, the plasma processing unit 80 is disposed close to the wafer W on the turntable 2, or the modified region 150 is formed. It is conceivable to arrange a large number of plasma processing means 80 for widening.

However, in this embodiment, since the sequence of the processing cycle is adjusted instead of changing the configuration on the apparatus side, the range in which the reaction product can be modified without complicating the apparatus configuration (thin film The characteristic adjustment range can be widened.
Further, since the supply amount of O3 gas is made uniform in the film forming-reforming step and the reforming step, the pressure fluctuation in the vacuum vessel 1 can be suppressed, so that the gas flow in the vacuum vessel 1 is disturbed and the vacuum is concerned. Damage due to pressure fluctuations of members in the container 1 can be suppressed. For example, when the gas flow in the vacuum vessel 1 is not disturbed, the supply of O3 gas may be stopped in the reforming step. When the supply of O3 gas is stopped, the flow rate of O3 gas is stopped. The flow rate of the separation gas may be increased by that amount.

  Furthermore, when switching each step, as shown in FIG. 10 described above, since the Si-containing gas is turned off when the turntable 2 is rotated n times (n: integer), the film thickness of the reaction product is changed. There is an advantage that it is easy to manage the switching timing of each step. At this time, since the supply timing of each gas is different for each wafer W on the turntable 2 as described above, the switching timing of each step may be one revolution or less. However, by repeating a plurality of processing cycles, the film quality and film thickness of the thin film are made uniform between and within the wafers W. When the steps are switched during one rotation of the turntable 2 as described above, the Si-containing gas is not supplied only to a certain wafer W on the turntable 2, that is, uniformly to each wafer W. The switching timing of each step is adjusted so that the Si-containing gas is supplied.

  Further, in the film forming-modifying step, the reforming process is performed every time the film forming process is performed inside the vacuum vessel 1. In other words, in the circumferential direction of the rotary table 2, the wafer W passes through the processing regions P 1 and P 2. The reforming process is performed so as not to interfere with the film forming process in the middle of the passing path. In addition, the reforming step is performed every time the film forming-modifying step is performed. Therefore, for example, the thin film can be modified in a shorter time than when the modification treatment is performed after the thin film is formed.

  In addition, since the gas flowing from the upstream side by the cover body 221 can be suppressed from entering the inside of the cover body 221, for example, there is a dedicated space between the second reaction gas nozzle 32 and the activated gas injector 220. Since it is not necessary to provide the separation region D, the reforming process can be performed while reducing the cost of the film forming apparatus, and the generation of by-product gases such as NOx can be suppressed to prevent corrosion of members constituting the apparatus. Can be suppressed. In addition, since the cover body 221 is made of an insulator, no plasma is formed between the cover body 221 and the plasma processing means 80, so that the cover body 221 can be disposed close to the plasma processing means 80. Therefore, the apparatus can be miniaturized.

  As the processing gas for forming the above-described silicon oxide film, the first reaction gas is BTBAS [Bistal Butylaminosilane], DCS [Dichlorosilane], HCD [Hexachlorodisilane], 3DMAS [Trisdimethylaminosilane], Monoaminosilane or the like may be used, TMA [trimethylaluminum], TEMAZ [tetrakisethylmethylaminozirconium], TEMAH [tetrakisethylmethylaminohafnium], Sr (THD) 2 [strontium bistetramethylheptanedionato], Ti (MPD) (THD) [titanium methylpentanedionatobistetramethylheptaneedionate] or the like is used as the first reaction gas, and an aluminum oxide film, a zirconium oxide film, a hafnium oxide film, a strontium oxide film, a titanium oxide film, etc. The It may be membrane. Water vapor or the like may be employed as the second reaction gas that is an oxidizing gas that oxidizes these source gases. Further, when a TiN film is modified in a process that does not use O3 gas as the second reaction gas, such as a TiN (titanium nitride) film, the modified gas for plasma generation supplied from the gas introduction nozzle 34 is used. May use a gas containing N (nitrogen) such as NH3 (ammonia) gas.

Further, in the above-described example, the example in which the reaction product is formed using two kinds of reaction gases has been described. However, in the case where the reaction product is formed using two or more kinds, for example, three kinds or four kinds of reaction gases. The present invention may be applied.
Further, although two sets of plasma generating means 80 are provided, one set may be used, or three or more sets may be used. Furthermore, as described above, the capacitively coupled plasma is generated using the parallel electrodes (electrodes 36a and 36b). However, the inductively coupled plasma may be generated using a coil-type electrode.
In each of the above-described examples, the rotary table 2 is rotated with respect to the gas supply system (nozzles 31 to 34, 41, and 42 (300)). good.

Then, the Example performed in order to confirm the effect of this invention is described below. In this example, when the silicon oxide film described above was formed, it was evaluated how the properties of the thin film were improved by performing the modification step in addition to the film formation-modification step. In addition, as shown in the following table, the characteristics of the thin film were similarly evaluated when the ratio of the processing times (T1: T2) was changed. In this table, the processing times T1 and T2 are shown together with the ratio of the processing times.
(table)

  In addition, as a reference example, when only the film-forming step is performed without performing the modification step, and when only the film-forming process is performed without performing the plasma modification, it is ideal as a silicon oxide film. Each characteristic of the thermal oxide film considered to have the characteristics is shown. In addition, the characteristics of these thin films are evaluated by applying a negative bias voltage to the thin film after film formation and measuring the value of the leakage current depending on the magnitude of the negative bias voltage. Went by. Therefore, it can be said that a dense thin film with few impurities is formed when the leakage current is small. The rotation speed of the turntable 2 is 20 rpm. Further, since other processing conditions are the same in each example, description thereof is omitted.

  As a result, as shown in FIG. 12, the film quality of the thin film is improved by performing the reforming step together with the film forming-modifying step as compared with the case where the plasma reforming is not performed and the case where the reforming step is not performed. When the ratio of processing times (T1: T2) = 1: 3, the characteristics were at the same level as that of the thermal oxide film considered to be an ideal characteristic of the silicon oxide film.

DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Rotary table C Center area | region D Separation area | region E Exhaust area W Wafer 31,32,41,42 Gas nozzle 61,62 Exhaust port 80 Plasma generation part P1, P2 Processing area 220 Activated gas injector

Claims (11)

A table provided in a vacuum vessel and having a substrate placement region for placing a substrate;
First reaction gas supply means for supplying a first reaction gas adsorbed on the surface of the substrate to a first processing region in the vacuum vessel;
A second reaction which is provided at a position spaced in the circumferential direction of the table with respect to the first reaction gas supply means and reacts with a component of the first reaction gas on the surface of the substrate to generate a reaction product. A second reactive gas supply means for supplying a gas to a second processing region in the vacuum vessel;
In order to modify the reaction product on the substrate, the plasma obtained by converting the reformed gas into plasma is provided at a position spaced apart from the second reactant gas supply means in the circumferential direction of the table. Plasma processing means for supplying a plasma processing region in the vacuum vessel;
A rotating mechanism for relatively rotating the table and the first reactive gas supply means, the second reactive gas supply means and the plasma processing means;
A film forming-modifying step for performing a plurality of steps in which the substrate on the table passes through the first processing region, the second processing region, and the plasma processing region in this order, and the film forming process are stopped. And a reforming step in which the substrate on the table passes through the plasma processing region, and a control means for outputting a control signal so as to perform at least once in this order. apparatus.   The control means aligns the supply amount of the second reaction gas between these steps in order to suppress pressure fluctuations in the vacuum vessel at the time of switching from the film formation-modification step to the modification step. The film forming apparatus according to claim 1, wherein the control signal is output as follows.   In the modifying step, the first reactive gas supply means, the second reactive gas supply means, and the plasma processing are performed on the table so that the substrate on the table passes through the plasma processing region a plurality of times. 3. The film forming apparatus according to claim 1, wherein the film forming device is a step of relatively rotating the means a plurality of times.   The film forming apparatus according to claim 1, wherein the reformed gas is at least one of a rare gas and an O 2 gas.   5. The film forming apparatus according to claim 1, wherein the reforming process in the reforming step has a higher degree of reforming than the reforming process in the film-forming-modifying step. . A step of placing a substrate on a substrate placement region of a table provided in a vacuum vessel;
Next, the table is rotated relative to the first reaction gas supply unit, the second reaction gas supply unit, and the plasma processing unit that are spaced apart from each other in the circumferential direction of the table by using a rotation mechanism. A process of
A first processing region to which a first reaction gas is supplied from the first reaction gas supply unit; a second processing region to which a second reaction gas is supplied from the second reaction gas supply unit; and A film-forming step for performing a plurality of steps in which a substrate on the table passes through a plasma processing region to which plasma generated by plasma-forming of the reformed gas is supplied in this order, and a film-forming process. And a step of performing a modification step in which the substrate on the table passes through the plasma processing region at least once in this order.   In order to suppress pressure fluctuations in the vacuum vessel at the time of switching from the film-forming / modifying step to the reforming step, the supply amount of the second reaction gas between these steps is uniform. The film forming method according to claim 6.   In the modifying step, the first reactive gas supply means, the second reactive gas supply means, and the plasma processing are performed on the table so that the substrate on the table passes through the plasma processing region a plurality of times. The film forming method according to claim 6, wherein the film forming step is a step of relatively rotating the means a plurality of times.   The film forming method according to claim 6, wherein the reformed gas is at least one of a rare gas and an O 2 gas.   10. The film forming method according to claim 6, wherein the degree of reforming in the reforming process in the reforming step is larger than that in the film forming-modifying step. . A substrate is placed on a substrate placement region on a table in a vacuum vessel, and at least two kinds of reaction gases are sequentially supplied to the substrate, and a layer of reaction products is stacked by executing this supply cycle a plurality of times. In a storage medium storing a computer program used in a film forming apparatus for forming a thin film,
A storage medium characterized in that the computer program includes steps so as to implement the film forming method according to any one of claims 6 to 10.

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