Thin Film Formation Method and Apparatus

Abstract

The present invention relates to a thin film forming method and apparatus, and more particularly, to a method and apparatus for forming a gate oxide film. An embodiment of the thin film forming method of the present invention includes: a silicon oxide thin film forming step of forming a silicon oxide thin film on a substrate; a first silicon oxynitride thin film forming step of forming a first silicon oxynitride thin film on the silicon oxide thin film, and further including first process conditions for adjusting the nitrogen (N) content in the first silicon oxynitride thin film to form the first silicon oxynitride thin film; a second silicon oxynitride thin film forming step of forming a second silicon oxynitride thin film on the first silicon oxynitride thin film, and further including second process conditions for adjusting the nitrogen (N) content in the second silicon oxynitride thin film to form the second silicon oxynitride thin film; wherein the first process conditions and the second process conditions are adjusted so that the nitrogen (N) content in the first silicon oxynitride thin film is greater than the nitrogen (N) content in the second silicon oxynitride thin film.

Description

Technical Field

[0001] The present invention relates to a method and apparatus for forming a thin film, and more particularly, to a method and apparatus for forming a gate oxide film. Background Art

[0002] Field effect transistors (FETs), such as NFETs and PFETs, are commonly present in CMOS (Complementary Metal Oxide Semiconductor) devices. In a MOSFET device, a gate electrode or gate may include an insulator such as a gate oxide film, or doped polysilicon or a metal conductor formed on the gate insulator. Additionally, a gate electrode stack includes a semiconductor layer or substrate on which a gate insulating film is formed. The substrate region under the gate oxide film is a channel region, and source / drain pairs are formed in the substrate on both sides of the channel.

[0003] In semiconductor processes, silicon (Si) can be used as a substrate material. Silicon germanium (SiGe) is used as an alternative to silicon, enabling transistors to switch faster and achieve high performance. For example, SiGe can be used in high-frequency devices, and the SiGe process improves the PMOS performance of nano-devices.

[0004] SiGe has a larger lattice constant than Si and is more prone to dislocation during oxidation than Si. As a result, alternative methods to the oxidation process are used on the SiGe surface.

[0005] Therefore, a gate oxide film formed by an alternative method to the oxidation process is required. For this purpose, research is being conducted on a gate oxide film having a structure in which a part of a silicon oxide thin film is nitrided to form a silicon oxide thin film containing nitrogen (N) on the surface of the silicon oxide thin film. The nitrogen (N) content of the gate oxide film of this structure is shown in Figure 1 If nitrogen (N) is increased in the silicon oxide thin film, the dielectric constant can be easily adjusted. Such a gate oxide film requires complex heat treatments and plasma treatments such as heat treatment in an oxygen environment, plasma treatment for nitridation, heat treatment in an oxygen environment, and heat treatment in a nitrogen environment after forming the silicon oxide thin film, resulting in a problem of reduced productivity. Additionally, since the gate oxide film is manufactured by the above method, the gate oxide film cannot be manufactured in-situ in one device.

[0006] Then, in the case of forming a gate oxide film by the above method, as shown in Figure 1 nitrogen piles up between the substrate and the silicon oxide thin film interface, resulting in a problem of deteriorated electrical characteristics. Summary of the Invention

[0007] Problems to be Solved

[0008] The present invention is proposed to solve the above-mentioned conventional problems, and aims to provide a method and apparatus for forming a thin film. In order to adjust the dielectric constant, a gate oxide film including a silicon oxynitride film is formed, and the gate oxide film can also be formed in-situ, and the accumulation of nitrogen at the interface between the substrate and the oxide film is minimized.

[0009] Means for Solving the Problems

[0010] An embodiment of the thin film forming method of the present invention for solving the above technical problems includes: a silicon oxide film forming step of forming a silicon oxide film on a substrate; a first silicon oxynitride film forming step of forming a first silicon oxynitride film on the silicon oxide film, and further including a first process condition for adjusting the nitrogen (N) content in the first silicon oxynitride film to form the first silicon oxynitride film; a second silicon oxynitride film forming step of forming a second silicon oxynitride film on the first silicon oxynitride film, and further including a second process condition for adjusting the nitrogen (N) content in the second silicon oxynitride film to form the second silicon oxynitride film; wherein, the first process condition and the second process condition are adjusted so that the nitrogen (N) content in the first silicon oxynitride film is greater than the nitrogen (N) content in the second silicon oxynitride film.

[0011] In some embodiments of the thin film forming method of the present invention, the first silicon oxynitride film forming step is performed by atomic layer deposition (ALD) that repeatedly executes a first cycle period including at least one first silicon (Si) gas supply step, a first oxygen (O) gas supply step, and a first nitrogen (N) gas supply step; the second silicon oxynitride film forming step is performed by atomic layer deposition (ALD) that repeatedly executes a second cycle period including at least one second silicon (Si) gas supply step, a second oxygen (O) gas supply step, and a second nitrogen (N) gas supply step.

[0012] In some embodiments of the thin film forming method of the present invention, the first process condition and the second process condition are the types of oxygen (O) gas, and the first oxygen (O) gas supplied in the first silicon oxynitride film forming step and the second oxygen (O) gas supplied in the second silicon oxynitride film forming step can be gases of different types.

[0013] In some embodiments of the thin film forming method of the present invention, the first oxygen-containing (O) gas is nitrous oxide (N2O), and the second oxygen-containing (O) gas may be oxygen (O2).

[0014] In some embodiments of the thin film forming method of the present invention, between the silicon oxide thin film forming step and the first silicon oxynitride thin film forming step, there is further included a third silicon oxynitride thin film forming step of forming a third silicon oxynitride thin film on the silicon oxide thin film, and there are also included third process conditions for adjusting the nitrogen (N) content in the third silicon oxynitride thin film to form the third silicon oxynitride thin film; adjusting the first process conditions, the second process conditions and the third process conditions so that the nitrogen (N) content in the third silicon oxynitride thin film is less than the nitrogen (N) content in the second silicon oxynitride thin film; the first silicon oxynitride thin film forming step is performed by repeatedly executing an atomic layer deposition (ALD) method of a first cycle period including at least one first silicon (Si) gas supply step, a first oxygen (O) gas supply step, and a first nitrogen (N) gas supply step; the second silicon oxynitride thin film forming step is performed by repeatedly executing an atomic layer deposition (ALD) method of a second cycle period including at least one second silicon (Si) gas supply step, a second oxygen (O) gas supply step, and a second nitrogen (N) gas supply step; the third silicon oxynitride thin film forming step is performed by repeatedly executing an atomic layer deposition (ALD) method of a third cycle period including at least one third silicon (Si) gas supply step, a third oxygen (O) gas supply step, and a third nitrogen (N) gas supply step.

[0015] In some embodiments of the thin film forming method of the present invention, the first process conditions, the second process conditions and the third process conditions are oxygen-containing (O) gas types, the first oxygen-containing (O) gas is nitrous oxide (N2O), the second oxygen-containing (O) gas is oxygen (O2), and the third oxygen-containing (O) gas may be at least one of a mixed gas of oxygen (O2) and hydrogen (H2) and oxygen (O2).

[0016] In some embodiments of the thin film forming method of the present invention, the first process conditions, the second process conditions and the third process conditions can be adjusted so that the nitrogen (N) content in the first silicon oxynitride thin film is 20 - 40%, the nitrogen (N) content in the second silicon oxynitride thin film is 10 - 20%, and the nitrogen (N) content in the third silicon oxynitride thin film is below 10%.

[0017] In some embodiments of the thin film forming method of the present invention, the step of forming the silicon oxide thin film can be performed by Atomic Layer Deposition (ALD).

[0018] In some embodiments of the thin film forming method of the present invention, after the step of forming the second silicon oxynitride thin film, a step of heat-treating the thin film may further be included.

[0019] In some embodiments of the thin film forming method of the present invention, the heat-treating step can be performed in an environment of at least one gas among nitrogen (N2), nitrous oxide (N2O), nitric oxide (NO), hydrogen (H2), and ammonia (NH3).

[0020] In some embodiments of the thin film forming method of the present invention, the steps of forming the silicon oxide thin film, the first silicon oxynitride thin film, the second silicon oxynitride thin film, the third silicon oxynitride thin film, and the heat-treating step can be performed in-situ.

[0021] In some embodiments of the thin film forming method of the present invention, the oxygen (O)-containing gas may include at least one of oxygen (O2), ozone (O3), nitrous oxide (N2O), nitric oxide (NO), and a mixed gas of oxygen (O2) and hydrogen (H2).

[0022] In some embodiments of the thin film forming method of the present invention, the nitrogen (N)-containing gas may include ammonia (NH3).

[0023] In some embodiments of the thin film forming method of the present invention, the silicon (Si)-containing gas may include at least one of silane-based gases and siloxane-based gases.

[0024] In some embodiments of the thin film forming method of the present invention, after the step of forming the silicon oxide thin film, a step of heat-treating the silicon oxide thin film with a mixed gas of oxygen (O2) and hydrogen (H2) may further be included.

[0025] In some embodiments of the thin film forming method of the present invention, the first process condition, the second process condition, and the third process condition are the number of times of the oxygen (O)-containing gas supply steps included in one cycle; the first cycle is to perform the first nitrogen (N)-containing gas supply step after repeating the first silicon (Si)-containing gas supply step and the first oxygen (O)-containing gas supply step n (n is a natural number) times; the second cycle is to perform the second nitrogen (N)-containing gas supply step after repeating the second silicon (Si)-containing gas supply step and the second oxygen (O)-containing gas supply step m (m is a natural number) times; the third cycle is to perform the third nitrogen (N)-containing gas supply step after repeating the third silicon (Si)-containing gas supply step and the third oxygen (O)-containing gas supply step l (l is a natural number) times; it may be that l > m > n.

[0026] In some embodiments of the thin film forming method of the present invention, the first process condition, the second process condition, and the third process condition may be at least one of the oxygen (O)-containing gas supply time, the pressure of the supplied oxygen (O)-containing gas, the flow rate of the supplied oxygen (O)-containing gas, the nitrogen (N)-containing gas supply time, the pressure of the supplied nitrogen (N)-containing gas, the flow rate of the supplied nitrogen (N)-containing gas, the number of nitrogen (N)-containing gas supply steps included in one cycle, and the process temperature.

[0027] In some embodiments of the thin film forming method of the present invention, the thin film may be a gate oxide film.

[0028] An embodiment of the thin film forming apparatus of the present invention for solving the above problems is an apparatus for forming a thin film on a silicon substrate, and the thin film is formed by the thin film forming method described above.

[0029] Effects of the Invention

[0030] According to the present invention, the formation of a silicon oxide film, the formation of a silicon oxynitride film, and the heat treatment process can all be performed in-situ, thus improving productivity. That is, it is possible to more easily form a gate oxide film including a silicon oxynitride film with an adjusted dielectric constant. In addition, when both the silicon oxide film and the silicon oxynitride film are formed by deposition as in the present invention, the phenomenon of nitrogen accumulation at the substrate and oxide film interface can be minimized, thus improving electrical characteristics. Description of the Drawings

[0031] Figure 1 It is a diagram schematically showing the nitrogen concentration in a gate oxide film in the case of forming a gate oxide film by a conventional method.

[0032] Figure 2 It is a diagram schematically showing an example of an apparatus for performing the thin film forming method of the present invention.

[0033] Figure 3 is a flowchart schematically showing the execution process of an embodiment of the thin film forming method of the present invention.

[0034] Figures 4 to 7 is for explaining in Figure 3 a diagram showing the execution process of the illustrated embodiment.

[0035] Figure 8 and Figure 9 is a diagram for explaining the schematic gas supply sequence for forming a silicon oxynitride film in the thin film forming method of the present invention.

[0036] Figure 10 is a diagram showing the nitrogen concentration in the thin film formed by the thin film forming method of the present invention. Detailed Description of the Preferred Embodiments

[0037] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention are provided to more completely explain the present invention to those having ordinary knowledge in the technical field to which the present invention pertains. The following embodiments can be modified into various forms, and the scope of the present invention is not limited to the following embodiments. Instead, these embodiments are provided to more truly and completely disclose and to convey the idea of the present invention to those skilled in the art.

[0038] In the drawings, for example, deformations of the illustrated shapes can be predicted according to manufacturing techniques and / or tolerances. Thus, the embodiments of the present invention should not be construed as being limited to the specific shapes of the regions shown in this specification, but should include, for example, shape deformations caused by manufacturing. The same reference numerals always refer to the same components. Furthermore, various components and regions are roughly drawn in the drawings. Therefore, the present invention is not limited to the relative sizes or spacings shown in the drawings.

[0039] Figure 2 is a diagram schematically showing an example of a device for performing the thin film forming method of the present invention. In Figure 2 the illustrated device is a vertical batch type substrate processing device and is an example of a substrate processing device for implementing the oxide film forming method of the present invention. The device for performing the oxide film forming method of the present invention is not limited to the substrate processing device shown in Figure 2 the illustrated substrate processing device, and of course, other substrate processing devices applicable to the technical idea of the present invention can be used, and for this purpose, structural additions and changes that are obvious to those skilled in the art can be made.

[0040] Refer to Figure 2, An example 100 of an apparatus for performing the thin film forming method of the present invention includes reaction vessels 110, 120, a manifold 160, a susceptor 140, a lid flange 150, and a heater 130.

[0041] The reaction vessels 110, 120 are composed of an inner tube 120 and an outer tube 110, and may be made of a heat-resistant material such as quartz. The outer tube 110 is formed in a cylindrical shape with an open bottom, and a receiving portion is formed inside. The inner tube 120 is disposed in the inner receiving portion of the outer tube 110, is formed in a cylindrical shape with an open bottom, and can accommodate the susceptor 140 inside. Further, a substrate processing space for performing substrate processing is provided inside the inner tube 120. An exhaust port 122 for discharging the gas in the inner tube 120 is formed on the side wall of the inner tube 120. An exhaust port 111 for exhausting the inside of the outer tube 110 is formed on the lower side surface of the outer tube 110, and the exhaust port 111 is connected to a pump (not shown) having a pumping ability. A profile temperature sensor is disposed inside a temperature sensor protection tube 183 extending in the vertical direction inside the inner tube 120.

[0042] The outer tube 110 is located above the manifold 160, and the outer tube 110 is fixed above the manifold 160 by being fixed by an outer tube fixing flange 115 through an outer tube protruding portion 113 protruding from the outer peripheral side of the lower end of the outer tube 110. An inner tube protruding portion 125 protruding from the outer peripheral side of the lower end of the inner tube 120 is also located above the manifold 160.

[0043] A plurality of gas supply ports 165 for supplying gas to the inner tube 120 are provided in the manifold 160. The plurality of gas supply ports 165 can be connected to a silicon-containing gas supply tool 192, an oxygen-containing gas supply tool 194, a nitrogen-containing gas supply tool 196, and a purge gas supply tool 197 for forming a silicon oxide film or a silicon oxynitride film. Further, the gas supply port 165 can be connected to a processing gas supply tool 198 for heat-treating a silicon oxide film or an oxide film. The plurality of gas supply ports 165 are respectively combined with gas nozzles 162 inside the manifold 160. The plurality of gas nozzles 162 extend upward inside the inner tube 120 to supply a silicon-containing gas, an oxygen-containing gas, a nitrogen-containing gas, a purge gas, and a heat treatment gas. The gas nozzles 162 are formed to extend upward to the upper part of the inner tube 120, are configured in a jet hole shape capable of horizontally jetting gas, and can be respectively jetted onto substrates stacked in the vertical direction.

[0044] The silicon-containing gas supply tool 192 supplies a silicon (Si)-containing gas onto the substrate. For example, it can supply silane-based gases such as SiH4, Si2H6, HCDS (Hexachlorodisilane), or siloxane-based gases such as HCDSO (Hexachlorodisiloxane). The oxygen-containing gas supply tool 194 supplies an oxygen (O)-containing gas onto the substrate. For example, it can supply gases such as oxygen (O2), ozone (O3), nitrous oxide (N2O), nitric oxide (NO), or a mixed gas of oxygen (O2) and hydrogen (H2). The mixed gas of oxygen (O2) and hydrogen (H2) can be separately supplied into the inner tube 120 through a separate oxygen (O2) gas supply tool and hydrogen (H2) gas supply tool. The nitrogen-containing gas supply tool 196 supplies a nitrogen (N)-containing gas onto the substrate. For example, it can supply gases such as ammonia (NH3). The purge gas supply tool 197 supplies a purge gas onto the substrate and can supply an inert gas such as nitrogen (N2). The heat treatment gas supply tool 198 is for creating a heat treatment environment and can supply gases such as oxygen (O2), hydrogen (H2), nitrogen (N2), nitrous oxide (N2O), nitric oxide (NO), ammonia (NH3), etc. When the same gas is used in the gas supply tools 192, 194, 196, 197, 198, one gas supply tool can be utilized for two or more purposes. For example, when both the purge gas and the heat treatment gas use nitrogen (N2), only one purge gas supply tool 197 and one heat treatment gas supply tool 198 may be provided; when both the oxygen-containing gas and the heat treatment gas use nitrous oxide (N2O), only one oxygen-containing gas supply tool 194 and one heat treatment gas supply tool 198 may be provided.

[0045] The gas supply tools 192, 194, 196, 197, 198 can each have a gas storage container or vaporizer, a gas pipeline, a flow regulator, etc., and receive a control signal. They can supply or block the gas through a flow regulator or a gas valve, etc., and can adjust the flow rate of the supplied gas.

[0046] A cover flange 150 is disposed below the reaction vessels 110 and 120, and the cover flange 150 is in the shape of a disk that can open and close the lower opening of the reaction vessels 110 and 120. The cover flange 150 is connected to a lifting tool (not shown) to be lifted and lowered. The cover flange 150 disposed below the reaction vessels 110 and 120 rises to seal with the manifold 160 disposed at the lower part of the reaction vessels 110 and 120, thereby sealing the lower opening of the reaction vessels 110 and 120. Then, the cover flange 150 descends, spacing the manifold 160 and the cover flange 150, thereby opening the lower opening of the reaction vessels 110 and 120. A sealing component (not shown) is disposed on the cover flange 150. When the cover flange 150 rises to seal with the manifold 160, the sealing component intervenes between the cover flange 150 and the manifold 160, thereby sealing between the cover flange 150 and the manifold 160.

[0047] The wafer boat 140 is arranged on the cover flange 150, and is composed of a substrate loading part 142 and a heat insulating part 144 for placing a plurality of substrates in the vertical direction. The heat insulating part 144 supports the substrate loading part 142, and has a structure and material that makes it difficult for the heat transferred to the inside of the reaction vessels 110 and 120 to be transferred to the cover flange 150. The substrate loading part 142 is configured to be able to place a plurality of substrates at intervals in the vertical direction. The substrate loading part 142 has a plurality of pillars 141, which are formed into a strip elongated in the vertical direction and have a structure in which a plurality of slots are formed vertically and side by side, thereby being able to support the substrate. In order to stably support the substrate, an auxiliary pillar (not shown) may be configured in addition to the pillars 141. The wafer boat 140 rotates through a rotating shaft 155 provided through the cover flange 150, and as the wafer boat 140 rotates, the substrates arranged on the wafer boat 140 also rotate accordingly.

[0048] The heater 130 is supported by being disposed on a heater base 135, and surrounds the outer tube 110 to heat the reaction vessels 110 and 120, thereby heating the substrates disposed in the wafer boat 140 loaded in the inner tube 120. The heater 130 is composed of an insulating wall and a heat pipe (not shown) located on the inner circumference of the insulating wall, and a cooling channel (not shown) having a cylindrical space is formed inside the insulating wall of the heater 130. Gas for rapid cooling is supplied to the cooling channel.

[0049] Figure 3 This is a flowchart schematically showing an execution process of one embodiment of a thin film forming method of the present invention. Figures 4 to 7 It is used to illustrate Figure 3 FIG. 1 is a diagram showing the execution process of an embodiment of the present invention. Figure 3 One embodiment of the thin film forming method of the present invention can be used in Figure 2 The apparatus shown performs, but is not limited to, such.

[0050] Refer toFigure 3 and Figures 4 to 7 , an embodiment of the thin film forming method of the present invention is, as Figure 4 shown, first, a silicon oxide thin film 320 is formed on a substrate 310 (S210). The silicon oxide thin film 320 can be formed by a deposition method, and there is no particular limitation on the deposition method. Atomic Layer Deposition (ALD) can be used for deposition. As the silicon (Si)-containing gas, a silane-based gas such as HCDS can be used, and as the oxygen (O)-containing gas, a mixed gas of hydrogen (H2) and oxygen (O2) can be used.

[0051] After performing step S210, the silicon oxide thin film 320 can be heat-treated. At this time, the heat treatment can be performed by a radical oxidation method performed in a mixed gas environment of oxygen (O2) and hydrogen (H2). Thus, if the silicon oxide thin film 320 is subjected to radical oxidation, the physical properties of the silicon oxide thin film 320 are improved.

[0052] Then, as Figure 5 shown, a third silicon oxynitride thin film 330 is formed on the silicon oxide thin film 320 (S220). Then, as Figure 6 shown, a first silicon oxynitride thin film 340 is formed on the third silicon oxynitride thin film 330 (S230). Then, as Figure 7 shown, a second silicon oxynitride thin film 350 is formed on the first silicon oxynitride thin film 340 (S240).

[0053] The step S230 of forming the first silicon oxynitride thin film 340 is performed including first process conditions that can adjust the nitrogen (N) content in the first silicon oxynitride thin film 340; the step S240 of forming the second silicon oxynitride thin film 350 includes second process conditions that can adjust the nitrogen (N) content in the second silicon oxynitride thin film 350; the step S220 of forming the third silicon oxynitride thin film 330 includes third process conditions that can adjust the nitrogen (N) content in the third silicon oxynitride thin film 330. At this time, the first process conditions, the second process conditions, and the third process conditions are adjusted so that the nitrogen (N) content in the first silicon oxynitride thin film 340 is the highest, the nitrogen (N) content in the third silicon oxynitride thin film 330 is the lowest, and the nitrogen (N) content in the second silicon oxynitride thin film 350 is in the middle to perform steps S220 to S250. For example, the first process conditions are adjusted so that the nitrogen (N) content in the first silicon oxynitride thin film 340 reaches about 20 to 40% to perform step S230, the second process conditions are adjusted so that the nitrogen (N) content in the second silicon oxynitride thin film 350 reaches about 10 to 20% to perform step S240, and the third process conditions are adjusted so that the nitrogen (N) content in the third silicon oxynitride thin film 330 is below 10% to perform step S220.

[0054] The silicon oxynitride films 330, 340, and 350 can all be formed by a deposition method. There is no particular limitation on the deposition method, and atomic layer deposition can be used for deposition. The silicon oxide film 320 and the silicon oxynitride films 330, 340, and 350 can all be deposited by atomic layer deposition, and can be in-situ deposited in the same equipment shown in Figure 2 Figure.

[0055] Specifically, the step S230 of forming the first silicon oxynitride film 340 can be carried out by repeatedly performing an atomic layer deposition (ALD) method that includes at least one first cycle period of a first silicon (Si) gas supply step, a first oxygen (O) gas supply step, and a first nitrogen (N) gas supply step; the step S240 of forming the second silicon oxynitride film 350 can be carried out by repeatedly performing an atomic layer deposition method of at least one second cycle period that includes a second silicon (Si) gas supply step, a second oxygen (O) gas supply step, and a second nitrogen (N) gas supply step; the step S220 of forming the third silicon oxynitride film 330 is carried out by repeatedly performing an atomic layer deposition method of at least one third cycle period that includes a third silicon (Si) gas supply step, a third oxygen (O) gas supply step, and a third nitrogen (N) gas supply step. As the silicon (Si) gas, a silane-based gas such as HCDS or a siloxane-based gas such as HCDSO can be used; as the oxygen (O) gas, oxygen (O2), ozone (O3), nitrous oxide (N2O), nitric oxide (NO), a mixed gas of oxygen (O2) and hydrogen (H2), or a combination of these can be used; as the nitrogen (N) gas, a gas such as ammonia (NH3) can be used.

[0056] A first embodiment of the first process condition, the second process condition, and the third process condition for adjusting the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 is that using mutually different types of oxygen (O) gases for the type of oxygen (O) gas can adjust the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350. For example, in the step S230 of forming the first silicon oxynitride film 340, nitrous oxide (N2O) is used as the first oxygen (O) gas, in the step S240 of forming the second silicon oxynitride film 350, oxygen (O2) is used as the second oxygen (O) gas, and in the step S220 of forming the third silicon oxynitride film 330, a mixed gas of oxygen (O2) and hydrogen (H2) can be used as the third oxygen (O) gas. Among the first process condition, the second process condition, and the third process condition for adjusting the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350, the process condition that can cause the largest change in the nitrogen (N) content is to change the type of oxygen (O) gas.

[0057] The following are the first process condition, the second process condition, and the third process condition for adjusting the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350, as compared to the case of changing the type of oxygen (O)-containing gas, within a small range.

[0058] A second embodiment of the first process condition, the second process condition, and the third process condition for adjusting the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 is that the supply time of the oxygen (O)-containing gas can adjust the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 when the oxygen (O)-containing gas is supplied at mutually different times. For example, the supply time of the first oxygen (O)-containing gas in the first silicon oxynitride film 340 forming step S230 is the shortest, the supply time of the second oxygen (O)-containing gas in the second silicon oxynitride film 350 forming step S240 is in the middle, and the supply time of the third oxygen (O)-containing gas in the third silicon oxynitride film 330 forming step S220 can be the longest.

[0059] A third embodiment of the first process condition, the second process condition, and the third process condition for adjusting the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 is that the pressure of the supplied oxygen (O)-containing gas can adjust the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 when the oxygen (O)-containing gas is supplied at mutually different pressures. For example, the pressure of the first oxygen (O)-containing gas supplied in the first silicon oxynitride film 340 forming step S230 is the smallest, the pressure of the second oxygen (O)-containing gas supplied in the second silicon oxynitride film 350 forming step S240 is in the middle, and the supply pressure of the third oxygen (O)-containing gas supplied in the third silicon oxynitride film 330 forming step S220 can be the largest.

[0060] A fourth embodiment of the first process condition, the second process condition, and the third process condition for adjusting the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 is that the flow rate of the supplied oxygen (O)-containing gas can adjust the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 when the oxygen (O)-containing gas is supplied at mutually different flow rates. For example, the flow rate of the first oxygen (O)-containing gas supplied in the first silicon oxynitride film 340 forming step S230 is the smallest, the flow rate of the second oxygen (O)-containing gas supplied in the second silicon oxynitride film 350 forming step S240 is in the middle, and the supply flow rate of the third oxygen (O)-containing gas supplied in the third silicon oxynitride film 330 forming step S220 can be the largest.

[0061] The fifth embodiment of the first process condition, the second process condition, and the third process condition for adjusting the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 is that for the number of oxygen (O)-containing gas supply steps included in one cycle period, the number of oxygen (O)-containing gas supply steps is different in each cycle period, and thus the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 can be adjusted. For example, in the first silicon oxynitride film 340 forming step S230, the number of the first oxygen (O)-containing gas supply steps in each first cycle period is the least, in the second silicon oxynitride film 350 forming step S240, the number of the second oxygen (O)-containing gas supply steps in each second cycle period is in the middle, and in the third silicon oxynitride film 330 forming step S220, the number of the third oxygen (O)-containing gas supply steps in each third cycle period can be the most.

[0062] More specifically, in the first cycle period of the first silicon oxynitride film 340 forming step S230, the first silicon (Si)-containing gas supply step and the first oxygen (O)-containing gas supply step are repeated n (n is a natural number) times, and then the first nitrogen (N)-containing gas supply step is executed; in the second cycle period of the second silicon oxynitride film 350 forming step S240, the second silicon (Si)-containing gas supply step and the second oxygen (O)-containing gas supply step are repeated m (m is a natural number) times, and then the second nitrogen (N)-containing gas supply step is executed; in the third cycle period of the third silicon oxynitride film 330 forming step S220, the third silicon (Si)-containing gas supply step and the third oxygen (O)-containing gas supply step are repeated l (l is a natural number) times, and then the third nitrogen (N)-containing gas supply step can be executed. At this time, the steps S220 to S240 can be executed with l > m > n.

[0063] The general gas supply sequence as described above is in Figure 8 and Figure 9 shown.

[0064] As Figure 8 shown, the atomic layer deposition method can be executed in the order of a silicon (Si)-containing gas, a purge gas, an oxygen (O)-containing gas, a purge gas, a nitrogen (N)-containing gas, and a purge gas as one cycle period. At this time, by changing the supply time of the oxygen-containing gas or the nitrogen-containing gas, etc., the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 can be adjusted.

[0065] Then, as Figure 9As shown, atomic layer deposition can be performed in a cycle by supplying a silicon (Si)-containing gas, a purge gas, an oxygen (O)-containing gas, a purge gas, a silicon (Si)-containing gas, a purge gas, an oxygen (O)-containing gas, a purge gas, a silicon (Si)-containing gas, a purge gas, an oxygen (O)-containing gas, a purge gas, a nitrogen (N)-containing gas, and a purge gas in this order.

[0066] If the gas is supplied in the gas supply order as Figure 9 shown, the oxygen (O)-containing gas is supplied three times per cycle; if the gas is supplied in the gas supply order as Figure 8 shown, the oxygen (O)-containing gas is supplied once per cycle. Accordingly, if the gas is supplied in the gas supply order as Figure 8 shown to form a silicon oxynitride film, the nitrogen (N) content is increased compared to the case where the gas is supplied in the gas supply order as Figure 9 shown to form a silicon oxynitride film. Thus, the first silicon oxynitride film 340 forming step S230 supplies the gas in the gas supply order as Figure 8 shown, and the second silicon oxynitride film 350 forming step S240 can supply the gas in the gas supply order as Figure 9 shown.

[0067] In addition, the first process condition, the second process condition, and the third process condition for adjusting the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 can be at least one of the nitrogen (N)-containing gas supply time, the pressure of the supplied nitrogen (N)-containing gas, the flow rate of the supplied nitrogen (N)-containing gas, the number of nitrogen (N)-containing gas supply steps included in one cycle, and the process temperature.

[0068] To increase the nitrogen content in the silicon oxynitride films 330, 340, and 350, increase the nitrogen (N)-containing gas supply time, or increase the pressure of the supplied nitrogen (N)-containing gas, increase the flow rate of the supplied nitrogen (N)-containing gas, and increase the number of nitrogen (N)-containing gas supply times per cycle.

[0069] Then, when the activation energy of the oxidation reaction upon supplying the oxygen (O)-containing gas is greater than the activation energy of the nitridation reaction upon supplying the nitrogen (N)-containing gas, the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 increases when the process temperature is lowered; when the activation energy of the oxidation reaction upon supplying the oxygen (O)-containing gas is less than the activation energy of the nitridation reaction upon supplying the nitrogen (N)-containing gas, the nitrogen (N) content in the silicon oxynitride films 330, 340, and 350 increases when the process temperature is raised.

[0070] In contrast, in order to reduce the nitrogen (N) content in the silicon oxynitride films 330, 340, 350, the supply time of the nitrogen (N)-containing gas is reduced, or the pressure of the supplied nitrogen (N)-containing gas is decreased, the flow rate of the supplied nitrogen (N)-containing gas is reduced, or the number of times of supplying the nitrogen (N)-containing gas per cycle is reduced.

[0071] Then, when the activation energy of the oxidation reaction during the supply of the oxygen (O)-containing gas is greater than the activation energy of the nitridation reaction during the supply of the nitrogen (N)-containing gas, the nitrogen (N) content in the silicon oxynitride films 330, 340, 350 decreases when the process temperature is increased; when the activation energy of the oxidation reaction during the supply of the oxygen (O)-containing gas is less than the activation energy of the nitridation reaction during the supply of the nitrogen (N)-containing gas, the nitrogen (N) content in the silicon oxynitride films 330, 340, 350 increases when the process temperature is decreased.

[0072] As described above, if the first process condition, the second process condition, and the third process condition are adjusted to perform steps S220, S230, and S240, the nitrogen (N) content in the silicon oxynitride films 330, 340, 350 is adjusted so that the nitrogen (N) content in the first silicon oxynitride film 340 is the highest, followed by the nitrogen (N) content in the second silicon oxynitride film 350, and the nitrogen (N) content in the third silicon oxynitride film 330 is the lowest. Thus, as Figure 10 shown, the nitrogen (N) concentration in the oxide film can be adjusted. If the silicon oxide film 320 and the silicon oxynitride films 330, 340, 350 are formed by a deposition method as in the present invention, they can be formed in situ in the Figure 2 shown apparatus. Moreover, the accumulation of nitrogen (N) at the interface between the silicon oxide film 320 and the substrate 310 can be minimized.

[0073] Then, all of the films 320, 330, 340, 350 are heat-treated (S250). By step S250, the densification of all of the films 320, 330, 340, 350 is increased or the nitrogen (N) content on the surfaces of all of the films 320, 330, 340, 350 can be adjusted. For this purpose, step S250 can be performed in an environment of nitrogen (N2), nitrous oxide (N2O), nitric oxide (NO), hydrogen (H2), and ammonia (NH3). Then, step S250 can also be performed in situ with steps S210 to S240. That is, all of steps S210 to S250 can be performed in situ using the Figure 2 shown apparatus. The films 320, 330, 340, 350 formed in this way can be used as gate oxide films.

[0074] As described above, according to the present invention, the formation of the silicon oxide film, the formation of the silicon oxynitride film, and the heat treatment process can all be performed in-situ, thus improving productivity. That is, it is possible to more easily form a gate oxide film including a silicon oxynitride film with an adjusted dielectric constant. In addition, when both the silicon oxide film and the silicon oxynitride film are formed by deposition as in the present invention, the phenomenon of nitrogen accumulation at the interface between the substrate 310 and the silicon oxide film 320 can be minimized, improving electrical characteristics, and thus it is suitable for use as a gate oxide film.

[0075] As mentioned above, embodiments of the present invention have been shown and described, but the present invention is not limited to the specific embodiments described above. Rather, anyone with ordinary knowledge in the technical field to which the present invention pertains can, without departing from the gist of the present invention claimed in the claims, of course make various modifications and implementations, and such changes are all within the scope of the claims.

Claims

1. A thin film forming method for forming a silicon oxynitride thin film having a nitrogen concentration gradient, characterized in that, Comprising: A silicon oxide film forming step of forming a silicon oxide film on a substrate; A third silicon oxynitride film forming step of forming a third silicon oxynitride film on the silicon oxide film, and further including a third process condition for adjusting the nitrogen content in the third silicon oxynitride film to form the third silicon oxynitride film; A first silicon oxynitride film forming step of forming a first silicon oxynitride film on the third silicon oxynitride film, and further including a first process condition for adjusting the nitrogen content in the first silicon oxynitride film to form the first silicon oxynitride film; A second silicon oxynitride film forming step of forming a second silicon oxynitride film on the first silicon oxynitride film, and further including a second process condition for adjusting the nitrogen content in the second silicon oxynitride film to form the second silicon oxynitride film; Wherein, the first process condition, the second process condition and the third process condition are adjusted so that the nitrogen content in the first silicon oxynitride film is greater than the nitrogen content in the second silicon oxynitride film, and the nitrogen content in the third silicon oxynitride film is less than the nitrogen content in the second silicon oxynitride film.

2. A thin film forming method for forming a silicon oxynitride thin film having a nitrogen concentration gradient, characterized in that, Comprising: A silicon oxide film forming step of forming a silicon oxide film on a substrate; A first silicon oxynitride film forming step of forming a first silicon oxynitride film on the silicon oxide film, and further including a first process condition for adjusting the nitrogen content in the first silicon oxynitride film to form the first silicon oxynitride film; A second silicon oxynitride film forming step of forming a second silicon oxynitride film on the first silicon oxynitride film, and further including a second process condition for adjusting the nitrogen content in the second silicon oxynitride film to form the second silicon oxynitride film; Wherein, the first process condition and the second process condition are adjusted so that the nitrogen content in the first silicon oxynitride film is greater than the nitrogen content in the second silicon oxynitride film; The first silicon oxynitride film forming step is performed by an atomic layer deposition method that repeatedly executes a first cycle period including at least one first silicon-containing gas supply step, a first oxygen-containing gas supply step, and a first nitrogen-containing gas supply step; The second silicon oxynitride film forming step is performed by an atomic layer deposition method that repeatedly executes a second cycle period including at least one second silicon-containing gas supply step, a second oxygen-containing gas supply step, and a second nitrogen-containing gas supply step.

3. The film forming method according to claim 2, wherein The first process condition and the second process condition are the types of oxygen-containing gases, The first oxygen-containing gas supplied in the first silicon oxynitride film forming step and the second oxygen-containing gas supplied in the second silicon oxynitride film forming step are gases of different types from each other.

4. The film forming method according to claim 3, wherein The first oxygen-containing gas is nitrous oxide, The second oxygen-containing gas is oxygen.

5. The film forming method according to claim 2, wherein Between the silicon oxide thin film forming step and the first silicon oxynitride thin film forming step, there is also a third silicon oxynitride thin film forming step of forming a third silicon oxynitride thin film on the silicon oxide thin film, and there are also third process conditions for adjusting the nitrogen content in the third silicon oxynitride thin film to form the third silicon oxynitride thin film; Adjust the first process conditions, the second process conditions and the third process conditions so that the nitrogen content in the third silicon oxynitride thin film is less than the nitrogen content in the second silicon oxynitride thin film; The third silicon oxynitride thin film forming step is performed by atomic layer deposition that repeatedly executes at least one third cycle including a third silicon-containing gas supply step, a third oxygen-containing gas supply step and a third nitrogen-containing gas supply step.

6. The thin film forming method according to claim 5, wherein The first process conditions, the second process conditions and the third process conditions are types of oxygen-containing gases, The first oxygen-containing gas is dinitrogen monoxide, The second oxygen-containing gas is oxygen, The third oxygen-containing gas is at least one of a mixed gas of oxygen and hydrogen and oxygen.

7. The thin film forming method according to claim 5, wherein Adjust the first process conditions, the second process conditions and the third process conditions, So that the nitrogen content in the first silicon oxynitride thin film is 20 - 40%, The nitrogen content in the second silicon oxynitride thin film is 10 - 20%, The nitrogen content in the third silicon oxynitride thin film is below 10%.

8. The thin film forming method according to claim 5, wherein The silicon oxide thin film forming step is performed by atomic layer deposition.

9. The thin film forming method according to any one of claims 5 to 8, wherein After the second silicon oxynitride thin film forming step, there is also a step of heat-treating the thin film.

10. The thin film forming method according to claim 9, wherein The heat treatment step is performed in an environment of at least one gas among nitrogen, dinitrogen monoxide, nitric oxide, hydrogen and ammonia.

11. The thin film forming method according to claim 9, wherein The silicon oxide thin film forming step, the first silicon oxynitride thin film forming step, the second silicon oxynitride thin film forming step, the third silicon oxynitride thin film forming step and the heat treatment step are performed in situ.

12. The thin film forming method according to any one of claims 2 to 8, wherein The oxygen-containing gas includes at least one of oxygen, ozone, dinitrogen monoxide, nitric oxide and a mixed gas of oxygen and hydrogen.

13. The thin film forming method according to any one of claims 2 to 8, wherein The nitrogen-containing gas includes ammonia.

14. The thin film forming method according to any one of claims 2 to 8, wherein The silicon-containing gas includes at least one of silane-based gases and siloxane-based gases.

15. The thin film forming method according to any one of claims 1 to 8, wherein After the step of forming the silicon oxide film, a step of heat-treating the silicon oxide film with a mixed gas of oxygen and hydrogen is further included.

16. The film forming method according to any one of claims 5 to 8, characterized in that the first process condition, the second process condition and the third process condition are the number of times of the oxygen-containing gas supply steps included in one cycle; the first cycle is to perform the first nitrogen-containing gas supply step after repeating the first silicon-containing gas supply step and the first oxygen-containing gas supply step n times, where n is a natural number; the second cycle is to perform the second nitrogen-containing gas supply step after repeating the second silicon-containing gas supply step and the second oxygen-containing gas supply step m times, where m is a natural number; the third cycle is to perform the third nitrogen-containing gas supply step after repeating the third silicon-containing gas supply step and the third oxygen-containing gas supply step l times, where l is a natural number; l > m > n.

17. The film forming method according to any one of claims 5 to 8, characterized in that the first process condition, the second process condition and the third process condition are at least one of the oxygen-containing gas supply time, the pressure of the supplied oxygen-containing gas, the flow rate of the supplied oxygen-containing gas, the nitrogen-containing gas supply time, the pressure of the supplied nitrogen-containing gas, the flow rate of the supplied nitrogen-containing gas, the number of nitrogen-containing gas supply steps included in one cycle, and the process temperature.

18. The film forming method according to any one of claims 1 to 8, characterized in that the film is a gate oxide film.

19. A film forming apparatus, as an apparatus for forming a film on a silicon substrate, characterized in that the film is formed by the film forming method described in any one of claims 1 to 8.

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