JP2019176014A - Deposition method - Google Patents

Abstract

To provide a technique capable of restraining ununiformity of a film to be deposited.SOLUTION: The shower head part 18 of a deposition device is sectioned into a central first gas chamber 19A, and a second gas chamber 19B provided to surround the first gas chamber 19A. A first gas port is connected with the first gas chamber 19A, and a second gas port is connected with the second gas chamber 19B. Deposition material gas (Center Gas) is ejected from the first gas chamber 19A to the central part of a semiconductor wafer W via the first gas port, and adjustment gas (Edge Gas) is ejected from the second gas chamber 19B to the peripheral part of the semiconductor wafer W via the second gas port, thus depositing on the semiconductor wafer W. With such an arrangement, ununiformity of film thickness or film quality of a film, deposited on the edge part and belly edge part, can be restrained.SELECTED DRAWING: Figure 4

Description

  The present disclosure relates to a film forming method.

  Plasma CVD (Chemical Vapor Deposition) is known as a technique for forming a thin film of a substance. For example, in the manufacture of a semiconductor integrated circuit, a film is formed on a substrate such as a semiconductor wafer by a film forming apparatus. The film formation apparatus arranges a substrate in a processing container having a predetermined degree of vacuum, generates a plasma by supplying a film formation source gas from above the substrate, and forms a film on the substrate.

JP 2010-59522 A

  The present disclosure provides a technique capable of suppressing nonuniformity of a film to be formed.

  A film forming method according to one embodiment of the present disclosure is a film forming method for forming a film on a substrate using plasma, and the film forming source gas is supplied from the first gas supply unit to the center of the substrate, and the substrate And a step of forming a film on the substrate by supplying an adjustment gas from a second gas supply unit to the periphery of the substrate.

  According to the present disclosure, nonuniformity of a film to be formed can be suppressed.

FIG. 1 is a cross-sectional view illustrating an example of a schematic configuration of a film forming apparatus according to the first embodiment. FIG. 2 is a plan view illustrating an example of the gas ejection surface side of the shower head unit according to the first embodiment. FIG. 3 is a graph showing an example of a change in film thickness of a film formed on a conventional semiconductor wafer. FIG. 4 is a diagram schematically illustrating an example of the configuration of the shower head unit and the mounting table according to the first embodiment. FIG. 5A is a graph showing an example of a change in the thickness of the formed SiO film. FIG. 5B is a graph showing an example of a change in film quality of the formed SiO film. FIG. 6A is a graph showing an example of a change in film thickness of the formed SiO film. FIG. 6B is a graph showing an example of a change in film quality of the formed SiO film. FIG. 7A is a graph showing an example of a change in the thickness of the formed SiO film. FIG. 7B is a graph showing an example of a change in film quality of the formed SiO film. FIG. 8A is a graph showing an example of a change in film thickness of the formed SiO film. FIG. 8B is a graph showing an example of a change in film quality of the formed SiO film. FIG. 9A is a graph showing an example of a change in film thickness of a formed SiO film. FIG. 9B is a graph showing an example of a change in film quality of the formed SiO film. FIG. 10 is a diagram showing an example of a change characteristic of the film thickness and the film quality by the gas supplied to the peripheral portion when forming the SiO film. FIG. 11A is a graph showing an example of a change in film thickness of a formed SiN film. FIG. 11B is a graph showing an example of a change in film quality of the formed SiN film. FIG. 12A is a graph showing an example of a change in film thickness of the formed SiN film. FIG. 12B is a graph showing an example of a change in film quality of the formed SiN film. FIG. 13A is a graph showing an example of a change in film thickness of a formed SiN film. FIG. 13B is a graph showing an example of a change in film quality of the formed SiN film. FIG. 14A is a graph showing an example of a change in film thickness of a formed SiN film. FIG. 14B is a graph showing an example of a change in film quality of the formed SiN film. FIG. 15A is a graph illustrating an example of a change in film thickness of a formed SiN film. FIG. 15B is a graph showing an example of a change in film quality of the formed SiN film. FIG. 16 is a diagram showing an example of a change characteristic of the film thickness and film quality by the gas supplied to the peripheral portion when forming the SiN film. FIG. 17 is a flowchart illustrating an example of the flow of the film forming method. FIG. 18 is a diagram illustrating an example of the configuration of the mounting table according to the second embodiment.

  Hereinafter, embodiments of a film forming method disclosed in the present application will be described in detail with reference to the drawings. Note that the disclosed film formation method is not limited by the present embodiment. In addition, the embodiments can be appropriately combined within a range that does not contradict processing contents.

  By the way, a substrate such as a semiconductor wafer has different electrical characteristics between the central portion and the edge portion. For this reason, in the film forming apparatus, when film forming raw material gas is supplied from the upper part of the substrate to generate plasma and the film is formed on the substrate, the film thickness and the like are not uniform between the central part and the edge part. There is. In particular, a so-called Very Edge portion that is the outermost shell of the substrate among the edge portions is likely to have a large non-uniformity in film thickness.

  Therefore, it is expected to suppress nonuniformity of the film to be formed.

(First embodiment)
[Configuration of deposition system]
The configuration of the film forming apparatus 12 according to the first embodiment will be described. FIG. 1 is a cross-sectional view illustrating an example of a schematic configuration of a film forming apparatus according to the first embodiment. The film forming apparatus 12 includes a processing container 14 formed into a cylindrical shape from, for example, aluminum or an aluminum alloy. The processing container 14 is grounded. In addition, a cooling jacket 110 is provided on the side wall and the ceiling wall of the processing container 14 to flow a coolant for cooling.

  The processing container 14 is provided with a shower head unit 18 on an internal ceiling, and various necessary gases can be introduced from the shower head unit 18 into the processing space S in the processing container 14.

The shower head portion 18 is entirely composed of a conductor such as nickel, hastelloy (trade name), aluminum, or a combination of these materials, and also serves as an upper electrode of a parallel plate electrode. The outer peripheral side and the upper side of the shower head 18 are entirely covered with a filling member 20 made of an insulating material such as quartz or alumina (Al ₂ O ₃ ). The shower head unit 18 is attached and fixed to the processing container 14 side through the filling member 20 in an insulated state.

  The shower head portion 18 is partitioned into a plurality of gas chambers, and gas can be individually introduced into the processing space S from each gas chamber. For example, the shower head portion 18 is partitioned into a first gas chamber 19A at the center and a second gas chamber 19B provided so as to surround the first gas chamber 19A. The shower head unit 18 has a large number of gas ejection ports 16 formed on a gas ejection surface 18A on the lower surface. The gas outlet 16 in the central portion of the shower head portion 18 penetrates to the first gas chamber 19A and ejects the gas in the first gas chamber 19A. The gas outlet 16 in the peripheral portion of the shower head 18 penetrates to the second gas chamber 19B, and jets the gas in the second gas chamber 19B.

  FIG. 2 is a plan view illustrating an example of the gas ejection surface side of the shower head unit according to the first embodiment. The gas ejection surface 18 </ b> A of the shower head unit 18 is formed in a disk shape corresponding to the shape of the semiconductor wafer W. FIG. 2 shows a range 21A of the region where the first gas chamber 19A is provided on the gas injection surface 18A and a range 21B of the region where the second gas chamber 19B is provided. The range 21A is the same size as the semiconductor wafer W. The range 21B is provided so as to surround the range 21A. The gas outlet 16A provided in the range 21A penetrates the first gas chamber 19A, and ejects the gas in the first gas chamber 19A. The gas outlet 16B provided in the range 21B penetrates the second gas chamber 19B and ejects the gas in the second gas chamber 19B.

  Returning to FIG. The shower head portion 18 is provided with a first gas introduction hole 22A communicating with the first gas chamber 19A and a second gas introduction hole 22B communicating with the second gas chamber 19B on the upper surface. The first gas introduction hole 22A and the second gas introduction hole 22B are individually connected to the gas supply mechanism 24 via gas flow paths 23A and 23B, respectively.

  The gas supply mechanism 24 has gas supply lines connected to gas supply sources for various gases used for film formation. Each gas supply line branches appropriately according to the film forming process, and is provided with an opening / closing valve and a flow rate controller. The gas supply mechanism 24 can control the flow rates of various gases by controlling on-off valves and flow rate controllers provided in each gas supply line.

  The gas supply mechanism 24 supplies various gases used for film formation to the first gas introduction hole 22A and the second gas chamber 19B via the gas flow paths 23A and 23B, respectively. For example, the gas supply mechanism 24 supplies the film forming source gas to the first gas chamber 19A via the gas flow path 23A and adjusts it to the second gas chamber 19B via the gas flow path 23B during film formation. Supply gas. The film forming source gas supplied to the first gas chamber 19A is ejected from a gas ejection port 16A connected to the first gas chamber 19A. The adjustment gas supplied to the second gas chamber 19B is ejected from a gas ejection port 16B connected to the second gas chamber 19B.

  The lower surface 20A of the filling member 20 is at the same horizontal level as the gas injection surface 18A of the lower surface of the shower head unit 18, and various gases introduced into the processing container 14 cause turbulent flow in the processing space S. The plasma is prevented from being unevenly distributed in the processing space S.

  Seal members 38 made of, for example, O-rings are interposed at the joints of the shower head portion 18, the filling member 20, and the wall portion of the processing container 14, respectively, so as to maintain the airtightness in the processing container 14. It has become.

  In addition, a high frequency power source 42 is connected to the shower head unit 18 via a matching circuit 44. The high frequency power supply 42 applies a high frequency voltage of a predetermined frequency (for example, 13.56 MHz) to the shower head unit 18 when generating plasma. The frequency of the high-frequency voltage used for generating plasma is not limited to 13.56 MHz, and other frequencies such as 450 kHz may be used. As the frequency of the high-frequency voltage used for plasma generation, a frequency within the range of 300 kHz to 27 MHz can be used. The film forming apparatus 12 may be provided with a plurality of high-frequency power sources 42 to generate plasma by applying high-frequency voltages with different frequencies to the shower head unit 18.

  A loading / unloading port 46 for loading / unloading the semiconductor wafer W is formed on the side wall of the processing container 14. The carry-in / out port 46 is provided with a gate valve 48 and can be opened and closed by the gate valve 48. The gate valve 48 is connected to a load lock chamber, a transfer chamber, and the like (not shown) for transporting the semiconductor wafer W without exposing it to the atmosphere.

  The center of the bottom of the processing container 14 is formed in a concave shape downward. An exhaust port 50 is formed in the concave side surface of the processing container 14. The exhaust port 50 is provided with an evacuation system 52 so that the inside of the processing container 14 can be evacuated. For example, the vacuum exhaust system 52 has an exhaust passage 54 connected to the exhaust port 50. In the exhaust passage 54, a pressure adjusting valve 56 and a vacuum pump 58 for adjusting the pressure in the processing container 14 are sequentially provided. And in the processing container 14, in order to mount the semiconductor wafer W, the mounting base 62 supported via the support | pillar 60 from the bottom part is provided. In the present embodiment, the semiconductor wafer W is assumed to have a diameter of 300 mm.

  The mounting table 62 also serves as a lower electrode. A ring-shaped focus ring 64 is provided at the upper peripheral edge of the mounting table 62 so as to surround the periphery of the semiconductor wafer W. The film forming apparatus 12 can generate plasma by applying a high frequency voltage to the upper electrode in the processing space S between the mounting table 62 as the lower electrode and the shower head unit 18 as the upper electrode. ing.

  The mounting table 62 is made of, for example, aluminum nitride (AlN), which is a ceramic material as a whole. In the mounting table 62, for example, heaters 66 made of a resistor such as molybdenum or tungsten wire are arranged in a predetermined pattern shape and embedded therein. A heater power source 68 is connected to the heater 66 via a wiring 70. The film forming apparatus 12 can control the temperature of the semiconductor wafer W to a predetermined temperature by supplying power to the heater 66 as necessary. In addition, in order to exhibit the function of the lower electrode, for example, an electrode main body 72 formed by meshing molybdenum wires or the like in a mesh shape (mesh shape) is provided in the mounting table 62 over substantially the entire area in the in-plane direction. Embedded. The electrode body 72 is grounded via the wiring 74. A high frequency voltage may be applied to the electrode body 72 as a bias voltage.

  The mounting table 62 is formed with three pin holes 76 penetrating in the vertical direction. In FIG. 1, only two pin holes 76 are shown. For example, a push-up pin 80 made of quartz is inserted into each pin hole 76 in a loosely fitted state. The lower ends of the push-up pins 80 are supported by arc-shaped connection rings 78. The connection ring 78 is supported on the upper end of the retracting rod 82. The retracting rod 82 penetrates the bottom of the container and has a lower end connected to the actuator 84, and can be moved in the vertical direction by the actuator 84. A bellows 86 that can be expanded and contracted is interposed in a penetrating portion of the in / out rod 82 with respect to the container bottom, and the in / out rod 82 can be moved up and down while maintaining airtightness in the processing container 14. .

  The operation of the film forming apparatus 12 configured as described above is comprehensively controlled by the control unit 106. The control unit 106 is, for example, a computer, and includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an auxiliary storage device, and the like. The CPU operates based on a program stored in the ROM or the auxiliary storage device or a film forming process condition, and controls the operation of the entire apparatus. For example, the control unit 106 starts and stops the supply of each gas, controls the flow rate of each gas, controls the temperature of the mounting table 62 on which the semiconductor wafer W is placed, controls the pressure in the processing container 14, and generates plasma. Controls the supply and stop of the supply of high-frequency power. Note that a computer-readable program necessary for control may be stored in the storage medium 108. The storage medium 108 includes, for example, a flexible disk, a CD (Compact Disc), a CD-ROM, a hard disk, a flash memory, or a DVD. The control unit 106 may be provided inside the film forming apparatus 12 or may be provided outside. In the case where the control unit 106 is provided outside, the control unit 106 can control the film forming apparatus 12 by a wired or wireless communication unit.

  Next, a flow of film formation performed using the film formation apparatus 12 will be briefly described. The film forming apparatus 12 opens the gate valve 48 provided on the side wall of the processing container 14. An unprocessed semiconductor wafer W is carried into the processing chamber 14 by a robot arm (not shown) through a loading / unloading port 46 from a load lock chamber or the like (not shown) to the film forming apparatus 12. The film forming apparatus 12 raises the push-up pins 80 and receives the semiconductor wafer W from the robot arm. After leaving the robot arm, the film forming apparatus 12 places the semiconductor wafer W on the mounting table 62 by lowering the push-up pins 80.

  Next, the film forming apparatus 12 closes the inside of the processing container 14 with the gate valve 48 closed, increases the input power to the heater 66, and sets the temperature of the mounting table 62 in the preheated state to the process temperature. The temperature is raised to a certain first temperature and maintained. The film forming apparatus 12 supplies a processing gas including a film forming raw material gas from the gas supply mechanism 24 to the shower head unit 18, and supplies the processing gas including the film forming raw material gas from the shower head unit 18 to the processing space S in the processing container 14. Introduce. Further, the film forming apparatus 12 evacuates the processing container 14 from the exhaust port 50 by the vacuum exhaust system 52 to maintain the processing container 14 at a predetermined process pressure.

  Then, the film forming apparatus 12 drives a high frequency power source 42 to apply a high frequency voltage of a predetermined frequency between the shower head unit 18 that is the upper electrode and the mounting table 62 that is the lower electrode. Thereby, plasma is generated in the processing space S, and film formation is performed on the surface of the semiconductor wafer W by the plasma.

  By the way, as described above, the semiconductor wafer W has different electrical characteristics between the central portion and the edge portion. For this reason, in the film forming apparatus 12, when a film forming raw material gas is supplied from the shower head unit 18 to generate plasma and the film is uniformly formed on the semiconductor wafer W under the same conditions, the center portion and the edge are formed. In some cases, the film thickness and the like are not uniform.

  FIG. 3 is a graph showing an example of a change in film thickness of a film formed on a conventional semiconductor wafer. FIG. 3 shows a film thickness profile corresponding to the distance from the center of the semiconductor wafer W when a SiO film is formed on the semiconductor wafer W. Since the diameter of the semiconductor wafer W is 300 mm, FIG. 3 shows the change in film thickness at each position with a radius of 0 to 150 mm. The film thickness is shown as a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 3, the film thickness gradually decreases in the central portion near the radius of 0 to 125 mm as compared with the center. Further, at the edge portion in the vicinity of the radius of 125 to 140 mm, the film thickness further decreases and then increases. Furthermore, at the belly edge portion near the radius of 140 to 150 mm, the film thickness increases rapidly. Since the edge portion and belly edge portion of the semiconductor wafer W are electrically discontinuous, the plasma state such as the electric field intensity distribution is different, and the film thickness control is difficult. For this reason, the fluctuation of the film thickness tends to be large at the edge portion and the belly edge portion.

  Therefore, the present applicant supplies the film forming raw material gas to the central portion of the semiconductor wafer W and supplies the adjustment gas to the peripheral portion of the semiconductor wafer W to perform film formation on the semiconductor wafer W, thereby forming the edge portion and The present inventors have found a technique capable of suppressing nonuniformity of the film such as film thickness and film quality formed on the belly edge portion.

  FIG. 4 is a diagram schematically illustrating an example of the configuration of the shower head unit and the mounting table according to the first embodiment. When film formation is performed, the semiconductor wafer W is mounted on the mounting table 62. In addition, a focus ring 64 is disposed around the semiconductor wafer W on the mounting table 62. The shower head unit 18 according to the present embodiment is partitioned into a first gas chamber 19A in the center and a second gas chamber 19B provided so as to surround the first gas chamber 19A. A gas outlet 16A is connected to the first gas chamber 19A. A gas outlet 16B is connected to the second gas chamber 19B. The gas in the first gas chamber 19A is ejected to the central portion of the semiconductor wafer W through the gas ejection port 16A. The gas in the second gas chamber 19B is ejected to the periphery of the semiconductor wafer W through the gas ejection port 16B. In the first embodiment, the first gas chamber 19A and the gas jet port 16A correspond to the first gas supply unit, and the second gas chamber 19B and the gas jet port 16B correspond to the second gas supply unit.

  The boundary between the first gas chamber 19 </ b> A and the second gas chamber 19 </ b> B may be outside the position where the variation in film thickness increases when the film is formed on the semiconductor wafer W, and from the end of the semiconductor wafer W to the outside. There may be. More preferably, the boundary between the first gas chamber 19A and the second gas chamber 19B is within a predetermined range with reference to the position of the end of the semiconductor wafer W. The predetermined range is, for example, within 20% of the radius of the semiconductor wafer W. When the radius of the semiconductor wafer W is 150 mm, the predetermined range is, for example, within 30 mm. In the present embodiment, the boundary between the first gas chamber 19A and the second gas chamber 19B is the end position of the semiconductor wafer W. The outermost gas outlet 16A is located at a position of 149.5 mm from the center of the semiconductor wafer W. The innermost gas ejection port 16B is located at a position of 156 mm from the center of the semiconductor wafer W.

For example, the film forming apparatus 12 supplies the film forming source gas from the gas supply mechanism 24 to the first gas chamber 19A through the gas flow path 23A, and also supplies the second gas from the gas supply mechanism 24 through the gas flow path 23B. The adjustment gas is supplied to the chamber 19B. For example, when forming a film of SiO, the film forming apparatus 12 transfers TEOS (Si (OC ₂ H ₅ ) ₄ ) / O ₂ / from the gas supply mechanism 24 to the first gas chamber 19A through the gas flow path 23A. supplies the respective gases Ar / He, the second gas chamber 19B through the gas flow path 23B from the gas supply mechanism 24 supplies a control gas containing any of He gas, Ar gas, _{O 2} gas. Further, for example, when forming a SiN film, the film forming apparatus 12 supplies each gas of SiH ₄ / NH ₃ / Ar / He from the gas supply mechanism 24 to the first gas chamber 19A through the gas flow path 23A. In addition to the supply, the adjustment gas containing any of Ar gas, He gas, N ₂ gas, and NH ₃ gas is supplied from the gas supply mechanism 24 to the second gas chamber 19B through the gas flow path 23B.

Here, an example of changes in film thickness and film quality to be formed will be described. First, the change of the film when He gas is supplied to the periphery of the semiconductor wafer W when SiO is deposited on the semiconductor wafer W will be described. For example, the film forming apparatus 12 supplies each gas of TEOS / O ₂ / Ar / He from the gas supply mechanism 24 to the first gas chamber 19A, and supplies He gas from the gas supply mechanism 24 to the second gas chamber 19B. Then, SiO was deposited on the semiconductor wafer W.

  FIG. 5A is a graph showing an example of a change in the thickness of the formed SiO film. FIG. 5A shows changes in film thickness when film formation is performed with He gas supplied to the second gas chamber 19B at 0 sccm, 200 sccm, 500 sccm, and 950 sccm. The film thickness is shown as a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 5A, the film thickness of the edge portion decreases as the supply amount of He gas increases.

  FIG. 5B is a graph showing an example of a change in film quality of the formed SiO film. FIG. 5B shows a change in refractive index as the film quality. FIG. 5B shows changes in the refractive index (RI) when film formation is performed with He gas supplied to the second gas chamber 19B at 0 sccm, 200 sccm, 500 sccm, and 950 sccm. The refractive index is indicated by a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 5B, the refractive index of the edge portion decreases as the supply amount of He gas increases.

Next, changes in the film when Ar gas is supplied to the peripheral portion of the semiconductor wafer W when the SiO film is formed on the semiconductor wafer W will be described. For example, the film forming apparatus 12 supplies each gas of TEOS / O ₂ / Ar / He from the gas supply mechanism 24 to the first gas chamber 19A, and Ar gas from the gas supply mechanism 24 to the second gas chamber 19B. Then, SiO was deposited on the semiconductor wafer W.

  FIG. 6A is a graph showing an example of a change in film thickness of the formed SiO film. FIG. 6A shows changes in film thickness when film formation is performed with Ar gas supplied to the second gas chamber 19B at 0 sccm, 500 sccm, and 950 sccm, respectively. The film thickness is shown as a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 6A, the film thickness of the edge portion increases as the supply amount of Ar gas increases.

  FIG. 6B is a graph showing an example of a change in film quality of the formed SiO film. FIG. 6B shows a change in refractive index as the film quality. FIG. 6B shows changes in the refractive index (RI) when film formation is performed with Ar gas supplied to the second gas chamber 19B at 0 sccm, 500 sccm, and 950 sccm. The refractive index is indicated by a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 6B, the refractive index of the edge portion increases as the supply amount of Ar gas increases.

Next, changes in the film when O ₂ gas is supplied to the peripheral portion of the semiconductor wafer W when SiO is deposited on the semiconductor wafer W will be described. For example, the film forming apparatus 12 supplies each gas of TEOS / O ₂ / Ar / He from the gas supply mechanism 24 to the first gas chamber 19A, and also supplies the O ₂ gas from the gas supply mechanism 24 to the second gas chamber 19B. To form a SiO film on the semiconductor wafer W.

FIG. 7A is a graph showing an example of a change in the thickness of the formed SiO film. FIG. 7A shows changes in film thickness when the O ₂ gas supply amount to the second gas chamber 19B is 10 sccm, 250 sccm, and 500 sccm. The film thickness is shown as a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 7A, the film thickness of the edge portion increases as the supply amount of O ₂ gas increases.

FIG. 7B is a graph showing an example of a change in film quality of the formed SiO film. FIG. 7B shows a change in refractive index as the film quality. FIG. 7B shows changes in the refractive index (RI) when the O ₂ gas supply amount to the second gas chamber 19B is 0 sccm, 250 sccm, and 500 sccm. The refractive index is indicated by a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 7B, the refractive index of the edge portion decreases as the supply amount of O ₂ gas increases.

Next, changes in the film when the TEOS gas is supplied to the peripheral portion of the semiconductor wafer W when SiO is deposited on the semiconductor wafer W will be described. For example, the film forming apparatus 12 supplies each gas of TEOS / O ₂ / Ar / He from the gas supply mechanism 24 to the first gas chamber 19A, and supplies the TEOS gas from the gas supply mechanism 24 to the second gas chamber 19B. Then, SiO was deposited on the semiconductor wafer W.

  FIG. 8A is a graph showing an example of a change in film thickness of the formed SiO film. FIG. 8A shows changes in film thickness when film formation is performed at TEOS gas supply rates to the second gas chamber 19B of 0 g / min, 0.2 g / min, and 0.4 g / min, respectively. ing. At 0 g / min, film formation was performed when Ar gas was included as a carrier gas at 150 sccm and when Ar gas was not included. At 0.2 g / min and 0.4 g / min, the film was formed when Ar gas was included at 150 sccm as the carrier gas. The film thickness is indicated by a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 8A, even if the supply amount of TEOS gas increases, the change in film thickness is poor.

  FIG. 8B is a graph showing an example of a change in film quality of the formed SiO film. FIG. 8B shows a change in refractive index as the film quality. FIG. 8B shows the change in refractive index (RI) when film formation is performed with the TEOS gas supply amount to the second gas chamber 19B being 0 g / min, 0.2 g / min, and 0.4 g / min. Each is shown. At 0 g / min, film formation was performed when Ar gas was included as a carrier gas at 150 sccm and when Ar gas was not included. At 0.2 g / min and 0.4 g / min, the film was formed when Ar gas was included at 150 sccm as the carrier gas. The refractive index is indicated by a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 8B, the film quality hardly changes even when the TEOS gas supply amount increases.

Next, a description will be given of changes in the film when a film-forming source gas similar to that in the central portion is supplied to the peripheral portion of the semiconductor wafer W when depositing SiO on the semiconductor wafer W. FIG. For example, the film forming apparatus 12 supplies each gas of TEOS / O ₂ / Ar / He from the gas supply mechanism 24 to the first gas chamber 19A, and from the gas supply mechanism 24 to the second gas chamber 19B. Each of the same TEOS / O ₂ / Ar / He gases was supplied to form a SiO film on the semiconductor wafer W.

  FIG. 9A is a graph showing an example of a change in film thickness of a formed SiO film. FIG. 9A shows changes in film thickness when film formation is performed with the supply amount of the film forming source gas to the second gas chamber 19B being 0%, 9%, and 18% in the center. . The film thickness is shown as a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 9A, the change in the film thickness is scarce even when the supply amount of the film forming source gas from the peripheral portion is increased.

  FIG. 9B is a graph showing an example of a change in film quality of the formed SiO film. FIG. 9B shows a change in refractive index as the film quality. FIG. 9B shows changes in the refractive index (RI) when the film formation is performed with the supply amount of the film formation source gas to the second gas chamber 19B being 0%, 9%, and 18% in the center. Has been. The refractive index is indicated by a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 9B, the change in film quality is scarce even when the supply amount of the film forming source gas from the peripheral portion is increased.

Thus, in the case of forming a SiO film, the film thickness and the refractive index can be changed by supplying He gas, Ar gas, and O ₂ gas to the peripheral portion of the semiconductor wafer W. FIG. 10 is a diagram illustrating an example of a change characteristic of the film thickness and the refractive index (RI) by the gas supplied to the peripheral portion when forming the SiO film. In FIG. 10, the magnitude of the degree of increase or decrease in the film thickness and refractive index is indicated by the number of arrows. As shown in FIG. 10, the He gas decreases the film thickness and decreases the refractive index. Ar gas increases the film thickness and increases the refractive index. O ₂ gas increases the film thickness and decreases the refractive index. The reason why the film thickness and refractive index are reduced by the He gas is presumed to be because the source gas is diluted by the He gas. The reason why the film thickness and refractive index are increased by Ar gas is presumed to be because the plasma density is increased by Ar gas.

Therefore, in the case of forming the SiO film, the film forming apparatus 12 supplies an appropriate amount of He gas, Ar gas, and O ₂ gas to the peripheral portion of the semiconductor wafer W, thereby reducing the film thickness of the film to be formed. A non-uniform refractive index can be suppressed. For example, the film forming apparatus 12 supplies He gas when reducing the thickness of the SiO film in the peripheral portion of the semiconductor wafer W, and Ar gas or O ₂ gas when increasing the thickness of the SiO film in the peripheral portion. Any one of the above is supplied. The film forming apparatus 12 supplies Ar gas when increasing the refractive index of the SiO film in the peripheral portion of the semiconductor wafer W, and He gas or O ₂ gas when decreasing the refractive index of the SiO film in the peripheral portion. Any one of the above is supplied. In addition, the film formation apparatus 12 supplies a suitable amount to the peripheral portion of the semiconductor wafer W by combining He gas, Ar gas, and O ₂ gas, thereby suppressing a change in one of the refractive index and the film thickness to be small. It can also be changed greatly. For example, the film forming apparatus 12 can change only the film thickness without changing the refractive index.

Next, changes in the film when He gas is supplied to the peripheral portion of the semiconductor wafer W when SiN is formed on the semiconductor wafer W will be described. For example, the film forming apparatus 12 supplies each gas of SiH ₄ / NH ₃ / Ar / He from the gas supply mechanism 24 to the first gas chamber 19A, and He gas from the gas supply mechanism 24 to the second gas chamber 19B. To form a SiN film on the semiconductor wafer W.

  FIG. 11A is a graph showing an example of a change in film thickness of a formed SiN film. FIG. 11A shows changes in film thickness when film formation is performed with the amount of He gas supplied to the second gas chamber 19B being 0 sccm, 500 sccm, and 950 sccm. The film thickness is shown as a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 11A, the film thickness of the edge portion decreases as the supply amount of He gas increases.

  FIG. 11B is a graph showing an example of a change in film quality of the formed SiN film. In FIG. 11B, the change in refractive index is shown as the film quality. FIG. 11B shows changes in the refractive index (RI) when the film formation is performed with the amount of He gas supplied to the second gas chamber 19B being 0 sccm, 500 sccm, and 950 sccm. The refractive index is indicated by a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 11B, the refractive index of the edge portion decreases as the supply amount of He gas increases.

Next, changes in the film when Ar gas is supplied to the periphery of the semiconductor wafer W when SiN is formed on the semiconductor wafer W will be described. For example, the film forming apparatus 12 supplies each gas of SiH ₄ / NH ₃ / Ar / He from the gas supply mechanism 24 to the first gas chamber 19A, and Ar gas from the gas supply mechanism 24 to the second gas chamber 19B. To form a SiN film on the semiconductor wafer W.

  FIG. 12A is a graph showing an example of a change in film thickness of the formed SiN film. FIG. 12A shows changes in film thickness when film formation is performed with Ar gas supplied to the second gas chamber 19B at 0 sccm, 500 sccm, and 950 sccm, respectively. The film thickness is shown as a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 12A, the film thickness of the edge portion increases as the supply amount of Ar gas increases.

  FIG. 12B is a graph showing an example of a change in film quality of the formed SiN film. FIG. 12B shows a change in refractive index as the film quality. FIG. 12B shows changes in the refractive index (RI) when film formation is performed with Ar gas supplied to the second gas chamber 19B at 0 sccm, 500 sccm, and 950 sccm, respectively. The refractive index is indicated by a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 12B, the refractive index of the edge portion increases as the supply amount of Ar gas increases.

Next, changes in the film when an N ₂ gas is supplied to the periphery of the semiconductor wafer W when SiN is formed on the semiconductor wafer W will be described. For example, the film forming apparatus 12 supplies each gas of SiH ₄ / NH ₃ / Ar / He from the gas supply mechanism 24 to the first gas chamber 19A, and N ₂ from the gas supply mechanism 24 to the second gas chamber 19B. A gas was supplied to form a SiN film on the semiconductor wafer W.

FIG. 13A is a graph showing an example of a change in film thickness of a formed SiN film. FIG. 13A shows changes in film thickness when film formation is performed with the supply amount of N ₂ gas to the second gas chamber 19B being 0 sccm, 250 sccm, and 500 sccm, respectively. The film thickness is shown as a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 13A, the film thickness of the edge portion increases as the supply amount of N ₂ gas increases.

FIG. 13B is a graph showing an example of a change in film quality of the formed SiN film. FIG. 13B shows a change in refractive index as the film quality. FIG. 13B shows changes in the refractive index (RI) when film formation is performed with the supply amount of N ₂ gas to the second gas chamber 19B being 0 sccm, 250 sccm, and 500 sccm, respectively. The refractive index is indicated by a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 13B, the refractive index of the edge portion decreases as the supply amount of N ₂ gas increases.

Next, changes in the film when SiH ₄ gas is supplied to the peripheral portion of the semiconductor wafer W when the SiN film is formed on the semiconductor wafer W will be described. For example, the film forming apparatus 12, the first gas chamber 19A from the gas supply mechanism _{24, SiH 4 / NH 3 /} Ar / supplies the respective gases, SiH ₄ from the gas supply mechanism 24 to the second gas chamber 19B A gas was supplied to form a SiN film on the semiconductor wafer W.

FIG. 14A is a graph showing an example of a change in film thickness of a formed SiN film. FIG. 14A shows changes in film thickness when film formation is performed with the supply amount of SiH ₄ gas to the second gas chamber 19B being 0 sccm, 10 sccm, and 20 sccm, respectively. The film thickness is shown as a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 14A, the film thickness of the edge portion slightly increases as the supply amount of SiH ₄ gas increases.

FIG. 14B is a graph showing an example of a change in film quality of the formed SiN film. FIG. 14B shows a change in refractive index as the film quality. FIG. 14B shows changes in the refractive index (RI) when film formation is performed with the supply amount of SiH ₄ gas to the second gas chamber 19B being 0 sccm, 10 sccm, and 20 sccm. The refractive index is indicated by a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 14B, even if the supply amount of SiH ₄ gas increases, the change in the refractive index is poor.

Next, a description will be given of changes in the film when a film forming material gas similar to that in the central part is supplied to the peripheral part of the semiconductor wafer W when forming the SiN film on the semiconductor wafer W. FIG. For example, the film forming apparatus 12 supplies each gas of SiH ₄ / NH ₃ / Ar / He from the gas supply mechanism 24 to the first gas chamber 19A, and from the gas supply mechanism 24 to the second gas chamber 19B. Each of SiH ₄ / NH ₃ / Ar / He gas similar to the above was supplied to form a SiN film on the semiconductor wafer W.

  FIG. 15A is a graph illustrating an example of a change in film thickness of a formed SiN film. FIG. 15A shows changes in film thickness when film formation is performed with the supply amount of the film forming source gas to the second gas chamber 19B being 0%, 9%, and 18% in the center. . The film thickness is shown as a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 15A, the change in the film thickness is scarce even when the supply amount of the film forming source gas from the peripheral portion is increased.

  FIG. 15B is a graph showing an example of a change in film quality of the formed SiN film. FIG. 15B shows a change in refractive index as the film quality. FIG. 15B shows changes in the refractive index (RI) when the film formation is performed with the supply amount of the film formation source gas to the second gas chamber 19B being 0%, 9%, and 18% in the center. Has been. The refractive index is indicated by a value normalized with reference to a value at a predetermined position (for example, the center) of the semiconductor wafer W. As shown in FIG. 15B, the change in the refractive index is scarce even when the amount of film forming material gas supplied from the peripheral portion increases.

In the formation of the SiN film, each gas of SiH ₄ / NH ₃ / Ar / He is supplied as a film forming source gas to the central portion of the semiconductor wafer W, and Ar gas, The case where He gas and N ₂ gas are supplied is illustrated. However, the gas supplied to the peripheral portion is not limited to Ar gas, He gas, and N ₂ gas, and NH ₃ gas may be supplied. When each gas of SiH ₄ / NH ₃ / Ar / He is supplied as a film forming source gas to be supplied to the central part, since the flow rate of NH ₃ gas from the central part is large, NH ₃ gas is supplied to the peripheral part. Although the change in film thickness and refractive index is small, it is presumed that the film thickness and refractive index can be controlled by supplying NH ₃ gas to the peripheral part if the conditions of the film forming raw material gas are changed. When NH ₃ gas is supplied to the peripheral part during the formation of the SiN film, the film thickness of the SiN film in the peripheral part of the semiconductor wafer W decreases, and the refractive index of the SiN film in the peripheral part decreases.

Thus, in the case of forming a SiN film, the film thickness and refractive index can be changed by supplying Ar gas, He gas, N ₂ gas, and NH ₃ gas to the peripheral portion of the semiconductor wafer W. FIG. 16 is a diagram illustrating an example of a change characteristic of the film thickness and the refractive index by the gas supplied to the peripheral portion when forming the SiN film. In FIG. 16, the magnitude of the degree of increase or decrease in film thickness and refractive index is indicated by the number of arrows. As shown in FIG. 16, the He gas decreases the film thickness and decreases the refractive index. Ar gas increases the film thickness and increases the refractive index. N ₂ gas increases the film thickness. The reason why the film thickness and refractive index are reduced by the He gas is presumed to be because the source gas is diluted by the He gas. The reason why the film thickness and refractive index are increased by Ar gas is presumed to be because the plasma density increases by Ar gas.

Therefore, in the case of forming a SiN film, the film forming apparatus 12 supplies a proper amount of Ar gas, He gas, N ₂ gas, and NH ₃ gas to the peripheral portion of the semiconductor wafer W to form a film. The film thickness and refractive index non-uniformity can be suppressed. For example, when the film forming apparatus 12 decreases the thickness of the SiN film in the peripheral portion of the semiconductor wafer W, it supplies either He gas or NH ₃ gas to increase the thickness of the SiN film in the peripheral portion. , Ar gas or N ₂ gas is supplied. Further, the film forming apparatus 12 supplies Ar gas when increasing the refractive index of the SiN film in the peripheral portion of the semiconductor wafer W, and He gas and NH ₃ gas when decreasing the refractive index of the SiN film in the peripheral portion. Any one of the above is supplied. In addition, the film forming apparatus 12 reduces a change in one of the refractive index and the film thickness by supplying an appropriate amount to the peripheral portion of the semiconductor wafer W by combining Ar gas, He gas, N ₂ gas, and NH ₃ gas. The other can be greatly changed. For example, the film forming apparatus 12 can change only the film thickness without changing the refractive index.

  In advance, the administrator experimentally obtains the condition of the adjustment gas that suppresses the non-uniformity of the film to be formed in accordance with the film forming condition. For example, the administrator supplies the film forming source gas to the central portion of the semiconductor wafer W using the film forming apparatus 12 and supplies the adjustment gas to the peripheral portion of the semiconductor wafer W in various types and supply amounts. Then, film formation is performed on the semiconductor wafer W, and the condition of the adjustment gas that makes the non-uniformity of the film to be formed a desired range is experimentally obtained. Then, the administrator stores the process conditions including the obtained conditions in the control unit 106 of the film forming apparatus 12 and causes the control unit 106 to perform film formation under the stored process conditions. Thereby, the film forming apparatus 12 can form a film on the semiconductor wafer W while suppressing non-uniformity of the film to be formed within a desired range.

  Alternatively, the administrator experimentally obtains a change in film thickness and refractive index according to the supply amount of the adjustment gas supplied to the peripheral portion of the semiconductor wafer W in advance during film formation. For example, the administrator supplies the film forming source gas to the central portion of the semiconductor wafer W using the film forming apparatus 12 and supplies the adjustment gas to the peripheral portion of the semiconductor wafer W in various types and supply amounts. Then, a film is formed on the semiconductor wafer W, and changes in film thickness and refractive index are obtained experimentally. Then, the administrator causes the control unit 106 of the film forming apparatus 12 to store data on changes in film thickness and refractive index in accordance with the type and supply amount of the supplied adjustment gas. When performing the film formation, the control unit 106 obtains the condition of the kind of the adjustment gas and the supply amount that reduce the non-uniformity of the film to be formed from the stored data. For example, the control unit 106 obtains conditions for the type and amount of adjustment gas that can change the film thickness to a desired range from the change in film thickness when the adjustment gas is not supplied to the peripheral portion of the semiconductor wafer W. The control unit 106 causes the control unit 106 to perform film formation under process conditions including the obtained conditions. Thereby, the film forming apparatus 12 can form a film on the semiconductor wafer W while suppressing non-uniformity of the film to be formed within a desired range.

[Flow of deposition method]
Next, the flow of film formation performed by the film formation apparatus 12 according to the first embodiment will be described. FIG. 17 is a flowchart illustrating an example of the flow of the film forming method.

  The control unit 106 controls the gas supply mechanism 24 in accordance with the film formation process conditions, and supplies the film forming source gas from the gas supply mechanism 24 to the first gas chamber 19A via the gas flow path 23A and supplies the gas. The adjustment gas is supplied from the mechanism 24 to the second gas chamber 19B through the gas flow path 23B (step S10). Thereby, the film forming source gas is supplied to the central portion of the semiconductor wafer W, and the adjustment gas is supplied to the peripheral portion of the semiconductor wafer W.

  The control unit 106 controls the evacuation system 52 to evacuate the processing container 14 from the exhaust port 50 by the evacuation system 52 to maintain the processing container 14 at a predetermined process pressure (step S11).

  The control unit 106 drives the high-frequency power source 42 to apply a high-frequency voltage of a predetermined frequency between the shower head unit 18 that is the upper electrode and the mounting table 62 that is the lower electrode (step S12).

  As described above, the film forming apparatus 12 according to the present embodiment supplies the film forming source gas to the central portion of the semiconductor wafer W and supplies the adjustment gas to the peripheral portion of the semiconductor wafer W to form the film on the semiconductor wafer W. I do. Thereby, the film-forming apparatus 12 can suppress nonuniformity of the film to be formed.

  Further, the film forming apparatus 12 according to the present embodiment supplies a rare gas as the adjustment gas. The film forming apparatus 12 can change the film thickness and refractive index of the film to be formed by supplying a rare gas to the peripheral portion of the semiconductor wafer W.

Further, the film forming apparatus 12 according to the present embodiment includes a TEOS gas as a film forming source gas, forms a SiO film on the semiconductor wafer W using plasma, and uses He gas, Ar gas, One of O ₂ gas is included. Thereby, the film-forming apparatus 12 can control the film thickness and refractive index of the SiO film to be formed.

Further, the film forming apparatus 12 according to the present embodiment includes SiH ₄ gas as a film forming source gas, forms a SiN film on the semiconductor wafer W using plasma, and uses Ar gas and He gas as adjustment gases. , N ₂ gas, or NH ₃ gas. Thereby, the film-forming apparatus 12 can control the film thickness and refractive index of the SiN film to be formed.

  In addition, the film forming apparatus 12 according to the present embodiment includes a first gas supply unit that supplies a film forming source gas corresponding to the upper part of the central portion of the semiconductor wafer W, and supplies a second adjustment gas. The gas supply unit was arranged around the first gas supply unit. Thereby, the film forming apparatus 12 can stably supply the adjustment gas to the peripheral portion of the semiconductor wafer W.

(Second Embodiment)
Next, a second embodiment will be described. In the film forming apparatus 12 according to the first embodiment described above, the shower head 18 is partitioned into a first gas chamber 19A and a second gas chamber 19B, and the second gas chamber 19B is used to form a peripheral portion of the semiconductor wafer W. The case where the adjustment gas is supplied has been described. In the film forming apparatus 12 according to the second embodiment, the case where the adjustment gas is supplied from the periphery of the mounting table 62 to the peripheral portion of the semiconductor wafer W will be described.

  FIG. 18 is a diagram illustrating an example of the configuration of the mounting table according to the second embodiment. The mounting table 62 has a cylindrical shape, and the semiconductor wafer W is mounted near the center of the upper surface. On the mounting table 62, a ring-shaped focus ring 64 is mounted around the semiconductor wafer W.

  The mounting table 62 is provided with a mechanism for supplying adjustment gas to the periphery. For example, in the mounting table 62, a gas flow path 120 penetrating to the upper surface is formed in the vicinity of the inner circumferential end. A gas supply line (not shown) is connected to the lower part of the gas flow path 120 and is connected to the gas supply mechanism 24 via the gas supply line. The adjustment gas is supplied from the gas supply mechanism 24 to the gas flow path 120. The gas flow path 120 and the focus ring 64 are covered with a cover 121. A gap 122 is formed between the cover 121 and the focus ring 64. The adjustment gas supplied to the gas flow path 120 flows through the gap 122 and is supplied to the peripheral portion of the semiconductor wafer W. In the second embodiment, the shower head unit 18 corresponds to the first gas supply unit, and the gas flow path 120 of the mounting table 62 corresponds to the second gas supply unit.

  Here, when the shower head part 18 is comprised like 1st Embodiment, the cost concerning manufacture of the shower head part 18 becomes large. On the other hand, when the shower head unit 18 is configured as in the second embodiment, it can be manufactured at a lower cost than in the case of configuring the shower head unit 18 as in the first embodiment.

  As described above, in the film forming apparatus 12 according to the present embodiment, the first gas supply unit that supplies the film forming source gas is disposed corresponding to the upper portion of the semiconductor wafer W, and the second gas supplying unit supplies the adjustment gas. The gas supply unit is arranged around the mounting table 62 on which the semiconductor wafer W is mounted. Thereby, the film forming apparatus 12 can stably supply the adjustment gas to the peripheral portion of the semiconductor wafer W. Further, the film forming apparatus 12 can be manufactured at low cost.

In the above-described embodiment, when the SiO film is formed, the adjustment gas including any one of He gas, Ar gas, and O ₂ gas is supplied to the peripheral portion of the semiconductor wafer W. Only one of Ar gas and O ₂ gas may be supplied as the adjustment gas. For example, when the film forming apparatus 12 reduces the film thickness of the SiO film in the peripheral part of the semiconductor wafer W, it supplies only He gas as the adjustment gas, and increases the film thickness of the SiO film in the peripheral part. or O ₂ gas alone may be supplied as the conditioning gas. In addition, when the refractive index of the SiO film in the peripheral portion of the semiconductor wafer W is increased, the film forming apparatus 12 supplies only Ar gas as the adjustment gas and decreases the refractive index of the SiO film in the peripheral portion. or O ₂ gas alone may be supplied as the conditioning gas.

In the above-described embodiment, when the SiN film is formed, the adjustment gas containing any of Ar gas, He gas, N ₂ gas, and NH ₃ gas is supplied to the periphery of the semiconductor wafer W. However, only one of Ar gas, He gas, N ₂ gas, and NH ₃ gas may be supplied as the adjustment gas. For example, when the film thickness of the SiN film in the peripheral portion of the semiconductor wafer W is reduced, the film forming apparatus 12 supplies only He gas or NH ₃ gas as the adjustment gas, and increases the thickness of the SiN film in the peripheral portion. In this case, only Ar gas or N ₂ gas may be supplied as the adjustment gas. In addition, when the refractive index of the SiN film in the peripheral part of the semiconductor wafer W is increased, the film forming apparatus 12 supplies only Ar gas as the adjustment gas, and in the case of decreasing the refractive index of the SiN film in the peripheral part, the He gas Alternatively, only NH ₃ gas may be supplied as the adjustment gas.

  Although the embodiment has been described above, the embodiment disclosed this time should be considered as illustrative in all points and not restrictive. Indeed, the embodiments described above can be embodied in various forms. The above-described embodiments may be omitted, replaced, and changed in various forms without departing from the scope and spirit of the claims.

DESCRIPTION OF SYMBOLS 12 Film-forming apparatus 14 Processing container 16, 16A, 16B Gas ejection port 18 Shower head part 19A 1st gas chamber 19B 2nd gas chamber 24 Gas supply mechanism 30 Processing container 31 Mounting stand 106 Control part 108 Storage medium 120 Gas flow path 121 Cover 122 Gap W Semiconductor wafer

Claims (8)

A film forming method for forming a film on a substrate using plasma,
A step of forming a film on the substrate by supplying a film forming source gas from a first gas supply unit to the central portion of the substrate and supplying an adjustment gas from a second gas supply unit to a peripheral portion of the substrate;
A film forming method comprising:   The film forming method according to claim 1, wherein the adjustment gas is a rare gas. The film forming source gas includes a TEOS gas, forms a SiO film on the substrate using plasma,
The adjustment gas includes any of He gas, Ar gas, and O ₂ gas.
The film forming method according to claim 1, wherein: When the film thickness of the SiO film in the peripheral part of the substrate is reduced, He gas is supplied as the adjustment gas, and when the film thickness of the SiO film in the peripheral part is increased, Ar gas, O as the adjustment gas _When either of the _two gases is supplied to increase the refractive index of the peripheral SiO film, Ar gas is supplied as the adjustment gas, and when the refractive index of the peripheral SiO film is decreased, the adjustment is performed. Supply either He gas or O ₂ gas as gas,
The film forming method according to claim 3. The film forming source gas includes SiH ₄ gas, and a SiN film is formed on the substrate using plasma,
The adjustment gas includes any of Ar gas, He gas, N ₂ gas, and NH ₃ gas,
The film forming method according to claim 1, wherein: When the film thickness of the SiN film in the peripheral part of the substrate is reduced, either the He gas or the NH ₃ gas is supplied as the adjustment gas, and the film thickness of the SiN film in the peripheral part is increased. When either Ar gas or N ₂ gas is supplied as a gas to increase the refractive index of the peripheral SiN film, Ar gas is supplied as the adjustment gas and the refractive index of the peripheral SiN film In the case of lowering, the adjustment gas is supplied with either He gas or NH ₃ gas.
The film forming method according to claim 5. The first gas supply unit is disposed corresponding to an upper portion of a central portion of the substrate,
The second gas supply unit is disposed around the first gas supply unit.
The film forming method according to claim 1, wherein: The first gas supply unit is disposed corresponding to the upper part of the substrate,
The second gas supply unit is disposed around a mounting table on which the substrate is mounted.
The film forming method according to claim 1, wherein:

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