Adjacent film, film forming method, and film forming apparatus

Abstract

To provide an adjacent film for stabilizing the characteristics of an oxide semiconductor, and to provide a film deposition method and a film deposition apparatus.SOLUTION: An adjacent film of an oxide semiconductor formed by depositing a film containing silicon atoms on a substrate and performing post-processing after the deposition in a high-density plasma processing apparatus, the adjacent film comprising: Wherein the deposition process includes a process using plasma of a first process gas including a fluorine-free and hydrogen-free SiCl4 gas and an oxygen-containing gas, the post-process includes a process using plasma of a second process gas including the oxygen-containing gas, and the adjacent film is a silicon oxide film having a hydrogen concentration of 1.0 * 10 20 atoms / cm3 or less and a chlorine concentration of 3.0 * 10 20 atoms / cm3 or less in the film.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to adjacent films, a film formation method, and a film formation apparatus. [Background technology]

[0002] Patent Document 1 discloses a film formation method using plasma, in which plasma is generated from a processing gas and a film containing silicon atoms is formed on a tapered portion of an electronic device structure by the plasma, wherein the processing gas contains a first gas and a second gas, neither of which contains hydrogen atoms, the first gas contains silicon atoms and halogen atoms other than fluorine atoms, the interatomic bonding strength between the silicon atoms and the halogen atoms is smaller than the interatomic bonding strength between the silicon atoms and the fluorine atoms, and the second gas contains at least one of nitrogen atoms and oxygen atoms.

[0003] Patent Document 2 also discloses a film formation method including: a first film formation process in which plasma of a mixed gas containing an oxygen-containing gas, SiF4 gas, and SiCl4 gas, wherein the flow rate ratio of the SiCl4 gas to the SiF4 gas is a first flow rate ratio, is generated using a first high-frequency power; and a second film formation process in which plasma of a mixed gas containing an oxygen-containing gas, SiF4 gas, and SiCl4 gas, wherein the flow rate ratio of the SiCl4 gas to the SiF4 gas is a second flow rate ratio, is generated using a second high-frequency power; and a second silicon oxide film is formed on the first silicon oxide film using the generated plasma, wherein the first high-frequency power is lower than the second high-frequency power; and the first flow rate ratio is lower than the second flow rate ratio. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-11058 [Patent Document 2] Japanese Patent Publication No. 2020-25065 Summary of the Invention [Problem to be solved by the invention]

[0005] In one aspect, the present disclosure provides an adjacent film, a film formation method, and a film formation apparatus that stabilize the characteristics of an oxide semiconductor. [Means for solving the problem]

[0006] In order to achieve the above object, according to one aspect, a high-density plasma processing apparatus is provided that deposits a film containing silicon atoms on a substrate and performs post-processing after the deposition process to form an adjacent film of an oxide semiconductor, the deposition process including processing with plasma of a first process gas containing SiCl gas containing no fluorine or hydrogen and a gas containing oxygen, the post-processing including processing with plasma of a second process gas containing the gas containing oxygen, and the adjacent film has a hydrogen concentration of 1.0×10 20 [atoms / cm 3 ] or less, and the chlorine concentration in the film is 3.0 × 10 20 [atoms / cm 3 ] It is possible to provide an adjacent film of an oxide semiconductor, which is a silicon oxide film of the following: [Effects of the Invention]

[0007] According to one aspect, it is possible to provide an adjacent film, a film formation method, and a film formation apparatus that stabilize the characteristics of an oxide semiconductor. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a vertical cross-sectional view showing an example of a plasma processing apparatus. [Figure 2] 4 is a time chart showing an example of a film formation process of a silicon oxide film. [Figure 3] FIG. 1 is a cross-sectional view showing an example of a semiconductor device formed on a substrate. [Figure 4] FIG. 10 is a diagram showing an example of the results of secondary ion mass spectrometry. [Figure 5] FIG. 10 is a diagram showing an example of the results of secondary ion mass spectrometry. [Figure 6] 1 is a diagram illustrating an example of characteristics of a semiconductor device. [Figure 7] 1 is a diagram illustrating an example of characteristics of a semiconductor device. [Figure 8] 1 is a diagram illustrating an example of characteristics of a semiconductor device. [Figure 9] 1 is a diagram showing an example of a plasma electron density distribution. [Figure 10] 1 is a diagram showing an example of a plasma electron density distribution. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0010] [Plasma processing equipment] A plasma processing apparatus 101 (film forming apparatus, high-density plasma processing apparatus) will be described with reference to Fig. 1. Fig. 1 is a vertical cross-sectional view showing an example of the plasma processing apparatus 101.

[0011] The plasma processing apparatus 101 shown in FIG. 1 is an inductively coupled plasma (ICP) processing apparatus that performs various substrate processing methods on a rectangular substrate G (hereinafter simply referred to as "substrate") for a flat panel display (hereinafter referred to as "FPD") in a planar view. Specifically, the plasma processing apparatus 101 performs a film formation process of a silicon oxide film on the substrate G. The substrate is mainly made of glass, although silicon or transparent synthetic resin may also be used depending on the application. Here, the substrate processing includes a film formation process using a plasma CVD (Plasma Enhanced Chemical Vapor Deposition) method. Examples of FPDs include liquid crystal displays (LCDs), electroluminescence (EL), and plasma display panels (PDPs). The substrate may have a circuit patterned on its surface, as well as a supporting substrate. Furthermore, the planar dimensions of FPD substrates have become larger with each generation, and the planar dimensions of the substrate G processed by the plasma processing apparatus 101 range from, for example, approximately 1500 mm × 1800 mm for the sixth generation to approximately 3000 mm × 3400 mm for the 10.5th generation. The thickness of the substrate G is approximately 0.2 mm to several mm.

[0012] 1 includes a processing vessel 10 having a rectangular box shape, a substrate mounting table 60 having a rectangular outer shape in a plan view that is disposed in the processing vessel 10 and on which a substrate G is mounted, and a control unit 90. The processing vessel 10 may have a shape such as a cylindrical box or an elliptical cylindrical box, and in this configuration, the substrate mounting table 60 also has a circular or elliptical shape, and the substrate G mounted on the substrate mounting table 60 also has a circular or elliptical shape.

[0013] Processing vessel 10 is divided into two spaces, upper and lower, by metal window 11, with the upper space, antenna chamber A, being formed by upper chamber 12, and the lower space, processing chamber S, being formed by lower chamber 13. In processing vessel 10, a rectangular ring-shaped support frame 14 is disposed at the boundary between upper chamber 12 and lower chamber 13 so as to protrude into the inside of processing vessel 10, and metal window 11 is attached to support frame 14.

[0014] The upper chamber 12 forming the antenna chamber A is entirely made of a metal such as aluminum or an aluminum alloy. The lower chamber 13 having the processing chamber S therein is entirely made of a metal such as aluminum or an aluminum alloy. The processing vessel 10 is also grounded by a ground wire 13e.

[0015] The support frame 14 is made of a metal such as conductive aluminum or an aluminum alloy, and can also be called a metal frame.

[0016] A rectangular annular (endless) seal groove is formed at the upper end of the side wall 13a of the lower chamber 13, and a seal member 15 such as an O-ring is fitted into the seal groove, and the seal member 15 is held by the abutting surface of the support frame 14, thereby forming a seal structure between the lower chamber 13 and the support frame 14.

[0017] A loading / unloading port (not shown) is provided in a side wall 13a of the lower chamber 13 for loading / unloading the substrate G into / from the lower chamber 13, and the loading / unloading port is configured to be freely opened and closed by a gate valve (not shown). A transfer chamber (neither of which is shown) containing a transfer mechanism is adjacent to the lower chamber 13, and the substrate G is loaded / unloaded by the transfer mechanism through the loading / unloading port by controlling the opening and closing of the gate valve.

[0018] Furthermore, a plurality of exhaust ports 13d are provided in the bottom plate 13c of the lower chamber 13. In the lower chamber 13, the sidewall 13a of the processing vessel 10 that accommodates the substrate mounting table 60 is formed in a rectangular cylindrical shape. In other words, the processing vessel 10 has a rectangular horizontal cross section at least at the position of the lower chamber 13 that accommodates the substrate mounting table 60. Furthermore, the substrate mounting table 60 has a rectangular horizontal cross section when viewed from above. In other words, the substrate mounting table 60 has a rectangular horizontal cross section. A plurality of exhaust ports 13d are arranged on the bottom plate 13c of the processing vessel 10, surrounding the substrate mounting table 60. In other words, the exhaust ports 13d are arranged outside the substrate mounting table 60 and inside the sidewall 13a of the processing vessel 10 (lower chamber 13) when viewed from above.

[0019] Each exhaust port 13d is connected to an exhaust device 50. A pressure gauge (not shown) is installed at an appropriate position in the lower chamber 13, and information monitored by the pressure gauge is sent to the control unit 90.

[0020] The substrate mounting table 60 has a base 161a and a stem portion 161b. The stem portion 161b is formed in a cylindrical shape, and one end thereof is airtightly joined to the base 161a by welding or the like. The other end of the stem portion 161b may have a flange shape. One end of the bellows 184 has a flange shape, and a seal member (not shown) such as an O-ring is held between the flange and the bottom plate 13c of the lower chamber 13, thereby forming a seal structure between the bellows 184 and the lower chamber 13. A circular annular (endless) seal groove is formed on the other flange surface of the bellows 184, and a seal member 116 such as an O-ring is fitted into the seal groove, and the abutting surface of the other end of the stem portion 161b is held against the flange, thereby forming a seal structure between the substrate mounting table 60 and the bellows 184.

[0021] The base material 161a has a rectangular shape in a plan view, and has planar dimensions similar to those of the substrate G placed on the substrate placement table 60. The length of the long side of the base material 161a can be set to approximately 1800 mm to 3400 mm, and the length of the short side can be set to approximately 1500 mm to 3000 mm. For these planar dimensions, the thickness of the base material 161a can be, for example, approximately 50 mm to 100 mm. The diameter of the stem portion 161b can be set to approximately 100 mm to 400 mm, and the length can be set to approximately 500 mm to 1000 mm.

[0022] Furthermore, multiple resistance heating elements HTa and HTb, such as sheath heaters, are arranged on the base 161a, serpentine to cover the entire area of ​​the rectangular plane. Power feed lines 171a and 171b are connected to the resistance heating elements HTa and HTb, respectively, and pass through the cylindrical internal space of the stem portion 161b. The power feed lines 171a and 171b are connected to a power source 173, which serves as a heater power source, via a control unit 172 that performs ON / OFF control. Temperature monitor information from multiple thermocouples (not shown) and other devices inside the base 161a arranged near the resistance heating elements HTa and HTb is sent to the control unit 172, which controls ON / OFF switching to maintain the temperature of the base 161a at a set temperature, raise and lower the temperature of the substrate G placed on the substrate mounting table 60, and control the film formation temperature.

[0023] A pedestal 162 made of an insulating material is fixed on the bottom plate 13c of the lower chamber 13, and the substrate mounting table 60 is placed on the pedestal 162.

[0024] In addition, a plurality of lift pins 180 are arranged on the substrate mounting table 60 to rise above the mounting surface and lift up the substrate G. The lift pins 180 are connected to pin holders 181 guided by pin guides 182. The pin holders 181 are connected to a drive unit (not shown) and are capable of being inserted vertically into through-holes formed in the bottom plate 13c of the lower chamber 13 so as to intersect perpendicularly with the bottom plate 13c, i.e., in the vertical direction. Bellows 183 are provided between the bottom plate 13c and the flange surface of the pin holder 181, and bellows 184 are provided between the bottom plate 13c and the other end of the stem portion 161b. Sealing members (not shown) are provided between the bottom plate 13c and the bellows 183 and between the bellows 183 and the pin holder 181, respectively, providing an airtight connection.

[0025] The metal window 11 is formed by a plurality of divided metal windows 20. The number of divided metal windows 20 that form the metal window 11 can be set to various numbers, such as 12 or 24.

[0026] The divided metal window 20 also serves as a process gas outlet that discharges process gas into the process chamber S. The divided metal window 20 is made of a non-magnetic, electrically conductive, corrosion-resistant metal or a metal that has been subjected to a corrosion-resistant surface treatment, such as aluminum, an aluminum alloy, or stainless steel. Examples of the corrosion-resistant surface treatment include anodizing and ceramic spraying. The exposed surface of the divided metal window 20 facing the process chamber S may also be subjected to a plasma-resistant coating by anodizing or ceramic spraying. The divided metal window 20 is grounded via a ground wire (not shown).

[0027] Each divided metal window 20 constituting the metal window 11 is suspended from the top plate of the upper chamber 12 by a plurality of suspenders (not shown). A spacer (not shown) made of an insulating material is disposed above each divided metal window 20, and a radio-frequency antenna (inductively coupled antenna) 41 is disposed at a distance from the divided metal window 20 by the spacer. The radio-frequency antenna 41 contributes to plasma generation and is formed by winding an antenna wire made of a highly conductive metal such as copper in a circular or spiral shape. For example, multiple circular antenna wires may be disposed. The radio-frequency antenna 41 is disposed on the top surface of the divided metal window 20, and is therefore suspended from the top plate of the processing vessel 10 via the divided metal window 20. The radio-frequency antenna 41 is disposed in an antenna chamber A of the upper chamber 12, above the processing vessel 10.

[0028] The divided metal window 20 has a gas diffusion groove 21 formed therein, and a through-hole that connects the gas diffusion groove 21 to the upper end surface is provided therein. A gas introduction pipe 35 is embedded in this through-hole. The divided metal window 20 has a plurality of gas discharge holes 22 that connect the gas diffusion groove 21 to the processing chamber S.

[0029] Each divided metal window 20 is electrically insulated from the support frame 14 and the adjacent divided metal window 20 by an insulating member 25. Here, the insulating member 25 is made of a fluororesin such as PTFE (Polytetrafluoroethylene). A ceramic cover member (not shown) may be provided to cover the end face of the insulating member 25 on the processing chamber S side. This protects the insulating member 25 from plasma.

[0030] A power feeder 42 is connected to the high frequency antenna 41, and the power feeder 42 is connected to a high frequency power supply 44 via a matching box 43 that performs impedance matching.

[0031] When high frequency power, for example, 13.56 MHz, is applied to the high frequency antenna 41 from the high frequency power supply 44, an inductive electric field is formed in the lower chamber 13. This inductive electric field converts the processing gas supplied to the processing chamber S through the divided metal window 20 into plasma, generating inductively coupled plasma, and ions in the plasma are supplied to the substrate G.

[0032] As shown in FIG. 1, the gas introduction pipes 35 of the respective divided metal windows 20 are connected to process gas supply sources 31, 32, and 33 via gas supply pipes 34 that are airtightly joined. The process gas supply source 31 supplies a material gas as the process gas. The material gas may be a gas containing silicon (Si) but not containing fluorine (F) or hydrogen (H). Specifically, SiCl4 may be used as a material gas containing silicon (Si) but not containing fluorine (F) or hydrogen (H). The process gas supply source 32 supplies a gas containing oxygen (O) as the process gas. The gas containing oxygen (O) may be any of O2, N2O, etc. The process gas supply source 33 supplies a rare gas (Ar, He, etc.).

[0033] In plasma processing, processing gas is supplied from the processing gas supply unit 30 via the gas supply pipe 34 and the gas introduction pipe 35 to the gas diffusion grooves 21 of each divided metal window 20. Then, the processing gas is discharged from each gas diffusion groove 21 through the gas discharge holes 22 into the processing chamber S.

[0034] As described above, the plasma processing apparatus 101 includes a plasma generating unit that generates processing plasma for performing substrate processing (film formation processing, etching processing, etc.) on the substrate G. The plasma generating unit includes at least a metal window 11 and a high-frequency antenna 41. A high-frequency power supply 44 supplies high-frequency power to the high-frequency antenna 41, and a processing gas supply unit 30 supplies processing gas to the processing chamber S through the divided metal window 20 (processing gas discharge unit). The plasma generating unit forms an induction electric field within the processing chamber S, and generates plasma of the processing gas supplied into the processing chamber S by this induction electric field.

[0035] The control unit 90 controls the operation of each component of the plasma processing apparatus 101. The control unit 90 also has user interfaces such as input devices such as a keyboard and a mouse for inputting commands, a display device such as a display for visualizing and displaying the operating status of the plasma processing apparatus 101, and an output device such as a printer.

[0036] In addition, the control unit 90 is connected to a memory unit 91 that stores programs for realizing various processes performed in the plasma processing device 101 under the control of the control unit 90, as well as recipe data required to execute the programs.

[0037] The storage unit 91 stores, for example, a plurality of process recipes for executing process processing of substrates or wafers. The recipes contain control information for the plasma processing apparatus 101 relative to process conditions. The control information includes, for example, the gas flow rate, the pressure inside the processing vessel 10, the temperature inside the processing vessel 10, the temperature of the substrate 161a, and the process time. The storage unit 91 also stores, for example, the emission intensity, the maximum emission intensity value, and a threshold value, which will be described later.

[0038] [Film formation process] Next, an example of a silicon oxide film formation process will be described with reference to Fig. 2. Fig. 2 is a time chart showing an example of a silicon oxide film formation process. Here, the case where the process gas supply source 31 supplies SiCl4 gas and the process gas supply source 32 supplies O2 gas will be described as an example.

[0039] In step S101, the substrate G is heated to a predetermined film formation temperature. Here, the control unit 90 controls the transfer mechanism (not shown) to place the substrate G (base material 161a) on the substrate mounting table 60, which has been adjusted to a predetermined temperature by controlling the power supply to the resistance heating elements HTa and HTb using the heater control unit 172 that has received a command from the control unit 90. The control unit 90 then closes the gate valve. Next, the control unit 90 controls the process gas supply unit 30 to supply O2 gas as a gas for promoting heat transfer into the process chamber S. Even while the O2 gas is being supplied, the control unit 90 commands the heater control unit 172 to set the film formation temperature, and controls the power supply to the resistance heating elements HTa and HTb so that the substrate G (base material 161a) reaches the predetermined film formation temperature.

[0040] When the substrate G (base material 161a) reaches the film formation temperature, step S101 is completed, the supply of O2 gas is stopped, and as a preparation for the deposition process described later, the supply of a first process gas containing O2 gas and SiCl4 gas is started, and the process chamber S is adjusted to a predetermined pressure.

[0041] In step S102, the substrate G is subjected to a deposition process by plasma CVD. Here, the control unit 90 controls the process gas supply unit 30 to supply a first process gas containing O gas (a gas containing oxygen) and SiCl gas into the process chamber S. The control unit 90 also controls the high-frequency power supply 44 to supply RF power to the high-frequency antenna 41 to form a high-density inductively coupled plasma. This dissociates chlorine (Cl) from SiCl and causes it to react with activated species of oxygen (O), thereby depositing a silicon-containing film (silicon oxide film) on the substrate G. The silicon-containing film formed in step S102 is a film (silicon oxide film) containing silicon (Si) and oxygen (O). The first process gas supplied into the process chamber S may contain a rare gas (Ar, He, etc.).

[0042] The film formation temperature is preferably 220°C or higher and 350°C or lower. The flow rate ratio of the oxygen (O)-containing gas (O2) to the SiCl4 gas is preferably within a range of 3.3 or higher and 4.3 or lower. The pressure is preferably within a range of 10 mTorr or higher and 30 mTorr or lower. The high-frequency power is 1.4 W / cm2 with respect to the area of ​​the largest surface of the substrate G placed on the mounting surface of the substrate mounting table 60 that is exposed to plasma (hereinafter referred to as the area of ​​the substrate G). 2 More than 2.2W / cm 2 The following is preferred:

[0043] In step S103, the substrate G is subjected to post-processing. Here, the control unit 90 controls the process gas supply unit 30 to supply a second process gas containing O gas (a gas containing oxygen) into the process chamber S. In other words, the control unit 90 controls the process gas supply unit 30 to stop the supply of SiCl gas while maintaining a predetermined pressure, and supply a second process gas containing O gas (a gas containing oxygen) into the process chamber S. The process time for the post-processing is 10 seconds or more and 60 seconds or less. The control unit 90 also controls the high-frequency power supply 44 to supply RF power to the high-frequency antenna 41 to form a high-density inductively coupled plasma. This supplies oxygen (O) to oxygen defects in the silicon-containing film (silicon oxide film) formed on the substrate G, thereby forming a high-quality silicon oxide film without oxygen defects. The second process gas supplied into the process chamber S may contain a rare gas (Ar, He, etc.).

[0044] The film formation temperature is preferably 220°C or higher and 350°C or lower. The flow rate ratio of the oxygen (O)-containing gas (O2) supplied during post-treatment, based on the SiCl4 gas flow rate during deposition, is preferably within a range of 3.3 or higher and 4.3 or lower. The pressure is preferably within a range of 10 mTorr or higher and 30 mTorr or lower. The high-frequency power is 1.4 W / cm2 relative to the area of ​​the substrate G. 2 More than 2.2W / cm 2 The following is preferred:

[0045] When the process of step S103 is completed, the RF power is stopped, and the supply of O2 gas is stopped. Then, the control unit 90 controls the transfer mechanism (not shown) to transfer the substrate G from the substrate mounting table 60 to outside the processing chamber 10.

[0046] [Semiconductor Devices] Next, an example of a semiconductor device formed on a substrate G will be described with reference to FIG. 3. FIG. 3 is a cross-sectional view showing an example of a semiconductor device (TFT) formed on a substrate G. The substrate G has a base material 310, a buffer film 320, an oxide semiconductor 330, a gate insulating film 340, an interlayer insulating film 350, a gate electrode 361, a source electrode 362, and a drain electrode 363. FIG. 3 illustrates a top-gate TFT as an example. However, the semiconductor device is not limited to this and may be a bottom-gate TFT or the like.

[0047] The base material 310 is made of, for example, silicon, glass, synthetic resin, or the like.

[0048] The buffer film 320 is formed to cover the base material 310. The buffer film 320 is a silicon oxide film formed in the plasma processing apparatus 101 shown in FIG. 1 and is an example of an adjacent film disposed below the oxide semiconductor 330. The buffer film 320 is an adjacent film formed before the oxide semiconductor 330 is formed on the substrate G. The thickness of the buffer film 320 is preferably 100 nm or more and 300 nm or less.

[0049] The oxide semiconductor 330 is formed on the buffer film 320. The oxide semiconductor 330 is, for example, IGZO, and also includes high-mobility oxide semiconductors such as IGZTO and indium oxide.

[0050] The gate insulating film 340 is formed to cover the buffer film 320 and the oxide semiconductor 330. The gate insulating film 340 is a silicon oxide film formed in the plasma processing apparatus 101 shown in FIG. 1 and is an example of an adjacent film disposed on the oxide semiconductor 330. The gate insulating film 340 is an adjacent film formed after the oxide semiconductor 330 is formed on the substrate G. The thickness of the gate insulating film 340 is preferably 100 nm or more and 200 nm or less.

[0051] The interlayer insulating film 350 is formed to cover the gate electrode 361 and the gate insulating film 340 .

[0052] The gate electrode 361 is formed on the gate insulating film 340. The source electrode 362 penetrates the gate insulating film 340 and the interlayer insulating film 350 and is connected to the oxide semiconductor 330. The drain electrode 363 penetrates the gate insulating film 340 and the interlayer insulating film 350 and is connected to the oxide semiconductor 330.

[0053] Here, the oxide semiconductor 330 is susceptible to the influence of hydrogen (H), which may cause instability in the operation of the semiconductor device. For this reason, films with a low concentration of hydrogen (H) are required for the films adjacent to the oxide semiconductor 330 (the buffer film 320 and the gate insulating film 340). In particular, an oxide semiconductor 330 using a high-mobility material (such as IGZTO) is more sensitive to hydrogen (H), which may cause instability in the operation of the semiconductor device.

[0054] 2, the film formation method shown in FIG. 2 can form films adjacent to the oxide semiconductor 330 (the buffer film 320 and the gate insulating film 340) using a source gas (SiCl4) that does not contain hydrogen (H). This can reduce the hydrogen (H) concentration in the adjacent films (the buffer film 320 and the gate insulating film 340) and also suppress hydrogen (H) from diffusing into the oxide semiconductor 330.

[0055] Furthermore, the formation of the adjacent films (buffer film 320, gate insulating film 340) is performed using high-density inductively coupled plasma. The dissociation effect of the high-density plasma dissociates chlorine (Cl) from SiCl4, reducing the concentration of chlorine (Cl) remaining in the film, and forming a silicon oxide film with few impurities. Furthermore, the subsequent annealing treatment (heat treatment) can prevent chlorine (Cl) from diffusing into the oxide semiconductor 330.

[0056] Furthermore, by forming the silicon oxide film thus formed as the lower layer (buffer film 320) and / or the upper layer (gate insulating film 340) of the oxide semiconductor 330, the driving stability of the semiconductor device is improved.

[0057] Furthermore, when a silicon oxide film (gate insulating film 340) is formed after the oxide semiconductor 330 is formed, not using hydrogen as a processing gas can prevent damage to the oxide semiconductor 330 caused by activated hydrogen species during the formation of the silicon oxide film.

[0058] Furthermore, since a large amount of hydrogen (H) diffusion and oxygen (O) desorption, which would destabilize the operation of the oxide semiconductor 330, do not occur, a stable semiconductor device can be fabricated.

[0059] Next, the diffusion of hydrogen (H) from the silicon oxide film (buffer film 320, gate insulating film 340) to the oxide semiconductor 330 will be described with reference to FIGS. 4 and 5. FIGS. 4 and 5 are diagrams showing examples of the results of secondary ion mass spectrometry (SIMS). Note that the detection values ​​for H, N, Si, and Cl correspond to the vertical axis on the left side. For O, the vertical axis on the right side corresponds to the profile, and only the profile is shown.

[0060] In Fig. 4(a), IGZO (oxide semiconductor 330) was formed on a Si substrate (base material 310) by sputtering, followed by annealing.

[0061] In Figure 4(b), a silicon oxide film 325 was formed on a Si substrate (base material 310) using a plasma of SiH4 and NO gas, and then an IGZO (oxide semiconductor 330) was formed by sputtering. After that, an annealing process was performed. Specifically, the pressure was 13 mTorr, and the radio frequency power density (hereinafter referred to as radio frequency power density) relative to the area of ​​the substrate G was 1.12 W / cm. 2 A silicon oxide film was formed at a gas flow ratio of SiH4:N2O=1:14.33.

[0062] In Figure 4(c), a silicon oxide film (buffer film 320) was formed on a Si substrate (base material 310) using a plasma of SiCl4 and O2 gas, and then an IGZO (oxide semiconductor 330) was formed by sputtering. After that, an annealing process was performed. Specifically, the pressure was 13 mTorr and the radio frequency power density was 1.44 W / cm. 2 A silicon oxide film was formed at a gas flow ratio of SiCl4:O2=1:4.33.

[0063] In Figure 5(d), IGZO (oxide semiconductor 330) was formed on a Si substrate (base material 310) by sputtering, and then a silicon oxide film 345 was formed using a plasma of SiH4 and N2O gas. After that, an annealing process was performed. Specifically, the pressure was 13 [mTorr] and the radio frequency power density was 1.12 W / cm. 2 A silicon oxide film was formed at a gas flow ratio of SiH4:N2O=1:14.33.

[0064] In Figure 5(e), IGZO (oxide semiconductor 330) was formed on a Si substrate (base material 310) by sputtering, and then a silicon oxide film (gate insulating film 340) was formed using a plasma of SiCl4 and O2 gas. After that, an annealing process was performed. Specifically, the pressure was 13 [mTorr] and the radio frequency power density was 1.44 W / cm. 2 A silicon oxide film was formed at a gas flow ratio of SiCl4:O2=1:4.33.

[0065] As shown in (a), the IGZO (oxide semiconductor 330) formed by sputtering has a density of about 1.0 × 10 21 [atoms / cm 3] contains a hydrogen atom (H).

[0066] As shown in (b) and (d), the silicon oxide films 325 and 345 using SiH4 had a SiO2 concentration of approximately 1.0 × 10 21 [atoms / cm 3 ] contains a hydrogen atom (H).

[0067] On the other hand, as shown in (c) and (e), in the silicon oxide film (buffer film 320, gate insulating film 340) using SiCl, the hydrogen concentration in the film is 1.0×10 20 [atoms / cm 3 That is, compared to the case where SiH4 is used, the use of SiCl4 can reduce the concentration of hydrogen atoms (H) in the silicon oxide film (buffer film 320, gate insulating film 340).

[0068] Furthermore, as shown in (b) and (d), by forming silicon oxide films 325, 345 adjacent to the IGZO (oxide semiconductor 330) using a plasma of SiH4 and NO gas, the number of hydrogen atoms (H) in the IGZO (oxide semiconductor 330) in (b) and (d) increases compared to the IGZO (oxide semiconductor 330) in (a). This indicates that the hydrogen atoms (H) in the silicon oxide films 325, 345 are diffused into the IGZO (oxide semiconductor 330).

[0069] In contrast, as shown in (c) and (e), by forming a silicon oxide film (buffer film 320, gate insulating film 340) adjacent to the IGZO (oxide semiconductor 330) using a plasma of SiCl4 and O2 gas, the hydrogen atoms (H) in the IGZO (oxide semiconductor 330) in (c) and (e) are slightly reduced compared to the IGZO (oxide semiconductor 330) in (a). This indicates that the hydrogen atoms (H) in the silicon oxide film (gate insulating film 340) are not diffused into the IGZO (oxide semiconductor 330).

[0070] As shown in (c) and (e), in the silicon oxide film (buffer film 320, gate insulating film 340) using SiCl, the chlorine concentration in the film is 3.0×10 20 [atoms / cm 3 ] or less, which indicates that almost no chlorine atoms (Cl) are incorporated into the film. It also indicates that chlorine atoms (Cl) are not diffused into the IGZO (oxide semiconductor 330).

[0071] As described above, the silicon oxide film (buffer film 320, gate insulating film 340) using SiCl4 can reduce the concentration of hydrogen atoms (H) in the film. Furthermore, by using this silicon oxide film as a film adjacent to the oxide semiconductor 330, it is possible to prevent hydrogen (H) from diffusing into the oxide semiconductor 330.

[0072] Next, the characteristics of a semiconductor device using a silicon oxide film (buffer film 320, gate insulating film 340) using SiCl 4 as an adjacent film to the oxide semiconductor 330 will be described with reference to FIGS.

[0073] 6 is an example of a diagram showing the characteristics of a semiconductor device. Here, the oxide semiconductor 330 is a high mobility oxide semiconductor (HMOx: High Mobility Oxide), and the semiconductor devices shown in FIG. 3 were fabricated as prototypes, and a BTS test was performed under stress conditions of 70°C, Vg = ±30 V, Vd = 0 V, and 2 hours. The results of the BTS test when a positive bias was applied to the semiconductor device (PBTS), the results of the BTS test when a negative bias was applied to the semiconductor device (NBTS), and the results of the initial mobility characteristics are shown.

[0074] 6, the buffer films 320 are different. For "SiCl4", the buffer film 320 was formed using plasma of SiCl4 and O2 gas. Specifically, the pressure was 13 mTorr and the radio frequency power density was 1.44 W / cm. 2In the "SiCl+SiF" group, a silicon oxide film was formed at a gas flow ratio of SiCl:O = 1:4.33. In the "SiCl+SiF" group, a buffer film 320 was formed using plasma of SiCl, SiF, and O gases. Specifically, the pressure was 13 mTorr and the radio frequency power density was 1.44 W / cm. 2 The silicon oxide film was formed at a gas flow ratio of SiCl4:SiF4:O2=1:0.33:4.33. For "SiH4", the buffer film 320 was formed using plasma of SiH4 and N2O gas. Specifically, the pressure was 13 mTorr and the radio frequency power density was 1.12 W / cm 2 A silicon oxide film was formed at a gas flow ratio of SiH4:N2O=1:14.33.

[0075] As shown in Figure 6, by using SiCl4 to form the buffer film 320, the mobility can be suppressed to 1 V or less in both the PBTS and NBTS tests. Furthermore, while the mobility increases when SiH4 is used, the mobility can be suppressed by using SiCl4. In other words, when SiH4 is used, H in the buffer film diffuses, suggesting that the effective channel length changes, and the change in the effective channel length can be suppressed by using SiCl4.

[0076] 7 is an example of a graph showing the characteristics of a semiconductor device. Here, the semiconductor devices shown in FIG. 3 were fabricated using a high-mobility oxide semiconductor (HMOx) as the oxide semiconductor 330, and a BTS test was performed under stress conditions of 70°C, Vg = ±30 V, Vd = 0 V, and 2 hours. The results of the BTS test when a positive bias was applied to the semiconductor device (PBTS) and the results of the initial mobility characteristics are shown.

[0077] 7, the gate insulating film 340 is different for each material. For "SiCl4," the gate insulating film 340 was formed using plasma of SiCl4 and O2 gases. For "SiCl4+SiF4," the gate insulating film 340 was formed using plasma of SiCl4, SiF4, and O2 gases. For "SiH4," the gate insulating film 340 was formed using plasma of SiH4 and N2O gases.

[0078] 7, by using SiCl4 to form the gate insulating film 340, the PBTS can be suppressed to 1 V or less. Furthermore, while the mobility is increased when SiH4 is used, the mobility can be suppressed by using SiCl4. In other words, when SiH4 is used, H in the gate insulating film 340 diffuses, suggesting that the effective channel length changes, and the change in the effective channel length can be suppressed by using SiCl4.

[0079] Figure 8 is an example of a diagram showing the characteristics of a semiconductor device. Here, the semiconductor devices shown in Figure 3 were fabricated using IGZO as the oxide semiconductor 330, and a BTS test was performed under stress conditions of 70°C, Vg = ±30 V, Vd = 0 V, and 2 hours. The results of the BTS test when a positive bias was applied to the semiconductor device (PBTS) and the results of the BTS test when a negative bias was applied to the semiconductor device (NBTS) are shown.

[0080] 8, the gate insulating film 340 is different for each material. For "SiCl4," the gate insulating film 340 is formed using plasma of SiCl4 and O2 gas. For "SiH4," the gate insulating film 340 is formed using plasma of SiH4 and N2O gas.

[0081] As shown in FIG. 8, by using SiCl 4 to form the gate insulating film 340, the voltage can be suppressed to 1 V or less in both the PBTS and NBTS tests.

[0082] As described above, by using the silicon oxide film (buffer film 320, gate insulating film 340) using SiCl 4 as the film adjacent to the oxide semiconductor 330, the characteristics of the semiconductor device are improved.

[0083] Next, plasma electron density will be explained using Figure 9. Figure 9 is an example of a diagram showing the plasma electron density distribution measured using a 4.5th generation device (substrate size 700mm x 900mm). The horizontal axis represents the distance from the center of the substrate G in the direction parallel to the short side of the substrate G. The vertical axis represents the plasma electron density.

[0084] Although the plasma processing apparatus 101 has been described as being connected from the matching box 43 to the high-frequency antenna 41 via the feeder line 42, this is not limiting. The matching box 43 may also be connected to the metal window 11 via a variable capacitor (not shown). In this case, by setting the capacitance of the variable capacitor to a low value (VC1%), the current from the matching box 43 flows to the high-frequency antenna 41. This forms an ICP plasma (ICP mode). On the other hand, by setting the capacitance of the variable capacitor to a large value (VC100%), the current from the matching box 43 flows to the metal window 11. This forms a CCP plasma (CCP mode).

[0085] In Figure 9, the pressure was 20 mTorr, the processing gas was O2, 500 sccm, and the radio frequency power density was 0.74 W / cm 2 O2 gas plasma was generated.

[0086] As shown in Figure 9, at the low capacitance side (VC1%), current flows through the high-frequency antenna 41, generating a high-density inductively coupled plasma (ICP). In the ICP mode, the plasma electron density is 7.0 x 10 10 [cm -3 ] or more is preferable.

[0087] On the other hand, at the high-capacity side (VC 100%), current flows through the metal window 11, and a capacitively coupled plasma (CCP) is generated with the metal window 11 as the upper electrode and the side wall of the processing chamber 10 or the substrate stage (lower electrode) 60 as the counter electrode. In the CCP mode, the plasma electron density is 4.0×10 10 [cm -3 High density plasmas, inductively coupled plasma (ICP) and capacitively coupled plasma (CCP), can be distinguished by the difference in plasma electron density.

[0088] 10 is an example of a diagram showing the plasma electron density distribution measured using a sixth-generation device. The horizontal axis represents the distance from the center of the substrate G in the direction parallel to the short side of the substrate G. The vertical axis represents the plasma electron density.

[0089] In FIG. 10, plasma of SiF4 / N2 gas was generated at a pressure of 10 mTorr and a processing gas of SiF4 / N2 at 100 / 1500 sccm while changing the output of the high frequency power.

[0090] In this case, the high-density plasma corresponds to an inductively coupled plasma (ICP), and the plasma electron density is 1.0 x 10 11 [cm -3 ] or more, and the high frequency power density is 1.44 W / cm 2 By using the above output, the corresponding plasma electron density can be obtained.

[0091] The above describes embodiments of the plasma processing method, but the present disclosure is not limited to the above embodiments, and various modifications and improvements are possible within the scope of the gist of the present disclosure as described in the claims. [Explanation of symbols]

[0092] G board 101 Plasma processing equipment (film forming equipment, high density plasma processing equipment) 10 Processing container 11 Metal Windows 30 Processing gas supply unit 41 High frequency antenna (inductively coupled antenna) 44 High frequency power supply 50 Exhaust system 60 Board mounting table 90 Control Unit 310 Base material 320 Buffer Film 330 Oxide Semiconductors 340 Gate insulating film 350 Interlayer insulating film 361 Gate electrode 362 Source electrode 363 Drain electrode

Claims

1. In a high-density plasma processing apparatus, a film containing silicon atoms is deposited on a substrate, and a post-processing is performed after the deposition process, thereby forming an adjacent film of an oxide semiconductor, The deposition process is fluorine- and hydrogen-free SiCl ４ a treatment with a plasma of a first treatment gas having a gas and an oxygen-containing gas; the post-treatment includes treatment with plasma of a second treatment gas having the oxygen-containing gas; The adjacent membrane is The hydrogen concentration in the film is 1.0×10 ２０ [atoms / cm ３ ] or less, The chlorine concentration in the film is 3.0 x 10 ２０ [atoms / cm ３ ] is a silicon oxide film of the following: Adjacent films of oxide semiconductors.

2. the silicon oxide film is a buffer film and / or a gate insulating film; The contiguous membrane of claim 1 .

3. The thickness of the buffer film is 100 nm or more and 300 nm or less. The contiguous membrane of claim 2 .

4. The thickness of the gate insulating film is 100 nm or more and 200 nm or less. The contiguous membrane of claim 2 .

5. The oxide semiconductor is IGZO or a high-mobility oxide semiconductor.

5. The contiguous membrane of claim 1.

6. The high mobility oxide semiconductor is IGZTO or indium oxide. The contiguous membrane of claim 5 .

7. 1. A film formation method for forming an adjacent film of an oxide semiconductor by depositing a film containing silicon atoms on a substrate in a high-density plasma processing apparatus and performing post-processing after the deposition process, the method comprising: The deposition process comprises: Fluorine- and hydrogen-free SiCl ４ supplying a first process gas containing a gas and an oxygen-containing gas and adjusting the pressure to a predetermined level; supplying high frequency power to the high density plasma processing apparatus and depositing the film containing silicon atoms on the substrate by the plasma of the first processing gas generated on the substrate; The post-treatment step includes: While maintaining the predetermined pressure, ４ stopping the supply of gas and supplying a second process gas containing the oxygen-containing gas; continuing to supply the high-frequency power to the high-density plasma processing apparatus, and supplying oxygen to oxygen defects in the film containing silicon atoms by the plasma of the second processing gas generated on the substrate, The adjacent membrane is The hydrogen concentration in the film is 1.0×10 ２０ [atoms / cm ３ ] or less, The chlorine concentration in the film is 3.0 x 10 ２０ [atoms / cm ３ ] is a silicon oxide film of the following: Film formation method.

8. The step of depositing the film containing silicon atoms forms the film at a temperature of 220° C. or higher and 350° C. or lower. The film forming method according to claim 7 .

9. The oxygen-containing gas is O ２ or N ２ It is O. The film forming method according to claim 7 .

10. the first process gas and / or the second process gas further contain a rare gas, The rare gas is either Ar or He. The film forming method according to claim 7 .

11. The flow rate ratio of the first process gas is ４ the flow rate ratio of the oxygen-containing gas to the flow rate of the gas is 3.3 times or more and 4.3 times or less; The film forming method according to claim 7 .

12. The predetermined pressure is 10 mTorr or more and 30 mTorr or less. The film forming method according to claim 7 .

13. The high frequency power is 1.4 W / cm2 relative to the area of ​​the substrate. ２ Above, 2.2W / cm ２ Below is the The film forming method according to claim 7 .

14. The processing time of the post-processing is 10 seconds or more and 60 seconds or less. The film forming method according to claim 7 .

15. A processing vessel; a substrate mounting table provided in the processing chamber and configured to mount a substrate thereon; a processing gas supply unit that supplies a processing gas into the processing vessel; a plasma generating unit that generates high-density plasma in the processing vessel; a control unit, and a film forming apparatus for depositing a film containing silicon atoms on the substrate, performing post-processing after the deposition process, and forming an adjacent film of an oxide semiconductor, The control unit Fluorine- and hydrogen-free SiCl ４ supplying a first process gas containing a gas and an oxygen-containing gas and adjusting the pressure to a predetermined level; supplying high frequency power to the plasma generating unit to deposit a film containing silicon atoms on the substrate by plasma of the first processing gas generated on the substrate; While maintaining the predetermined pressure, ４ stopping the supply of gas and supplying a second process gas containing the oxygen-containing gas; and continuing to supply the high frequency power to the plasma generating unit, and supplying oxygen to oxygen defects in the film containing silicon atoms by the plasma of the second process gas generated on the substrate. Film deposition equipment.

16. The plasma generating unit generates an inductively coupled plasma. The film forming apparatus according to claim 15.

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