JP6232219B2 - Method for forming multilayer protective film - Google Patents

Description

The present invention relates to the formation how a multilayer protective film for protecting an oxide semiconductor.

  Conventionally, a liquid crystal element is used as a light emitting element in an FPD (Flat Panel Display), but a thin transistor (TFT) is applied to the liquid crystal element in order to realize a thin FPD.

  In recent years, the use of organic EL (Electrouminescence) elements is progressing in order to realize sheet displays and next-generation thin televisions. An organic EL element is a self-luminous light-emitting element, and unlike a liquid crystal element, does not require a backlight, so that a thinner display can be realized.

  An organic EL element is a current-driven element, and it is necessary to realize a high-speed switching operation in a TFT applied to the organic EL element. At present, however, the electron mobility of amorphous silicon mainly used as a channel constituent material Since it is not so high, amorphous silicon is not suitable as a channel constituting material for organic EL.

Therefore, a TFT using an oxide semiconductor that can obtain high electron mobility for a channel has been proposed. As an oxide semiconductor used in such a TFT, for example, IGZO made of an oxide of indium (In), gallium (Ga), and zinc (Zn) is known (see, for example, Non-Patent Document 1). IGZO has a relatively high electron mobility (for example, 10 cm ² / (V · s) or more) even in an amorphous state. Therefore, when an oxide semiconductor such as IGZO is used for a TFT channel, high-speed switching operation is achieved. Can be realized.

In the TFT, the channel protective film is constituted by a plurality of films, for example, a silicon nitride (SiN) film and a silicon oxide (SiO ₂ ) film in order to reliably protect the channel from external ions and moisture (for example, patents). Reference 1). By the way, for example, when a silicon nitride film is formed by plasma CVD (Chemical Vapor Deposition), silane (SiH ₄ ) is often used as a silicon source and ammonia (NH ₃ ) is often used as a nitrogen source. When a silicon nitride film is formed from silane and ammonia, hydrogen radicals or hydrogen ions may enter the defects of the silicon nitride film as hydrogen atoms. That is, the protective film may contain hydrogen atoms.

  Since hydrogen atoms contained in the protective film change the characteristics of the IGZO by desorbing oxygen atoms from the oxide semiconductor, for example, IGZO, and changing the characteristics of the IGZO, after forming the protective film of the channel, to the protective film It is necessary to perform a dehydrogenation step in which hydrogen atoms are actively desorbed from the protective film by applying heat treatment.

Japanese Patent No. 3148183

"Oxide semiconductor TFT for realizing light and thin sheet display", Kentaro Miura et al., Toshiba Review Vol. 67 No. 1 (2012)

  However, since the dehydrogenation process requires time, there is a problem that throughput is reduced. In addition, as described above, heat treatment is applied to the protective film in the dehydrogenation process. However, when the organic EL element is applied to a sheet display, the substrate of the sheet display is formed of resin, so that the substrate is deformed and altered by heat. There is also a problem.

An object of the present invention is to provide a form how the multilayer protective film can be eliminated the need to perform the dehydrogenation step.

In order to achieve the above object, according to the method for forming a multilayer protective film according to claim 1, there is provided a method for forming a multilayer protective film that is in contact with an oxide semiconductor and includes at least a silicon nitride film and a silicon oxide film. A silicon oxide film forming step of forming a silicon oxide film by generating plasma using silicon chloride (SiCl ₄ ) gas or silicon fluoride (SiF ₄ ) gas and an oxygen-containing gas not containing hydrogen atoms; A silicon nitride film forming step of forming a silicon nitride film by generating plasma using the silicon chloride gas or the silicon fluoride gas and a nitrogen-containing gas not containing hydrogen atoms, and the silicon oxide film When switching from the film forming step to the silicon nitride film forming step, or when switching from the silicon nitride film forming step to the silicon oxide film forming step,
The supply of the nitrogen-containing gas is started after the supply of the oxygen-containing gas is stopped while the supply of the silicon chloride gas or the silicon fluoride gas is continued and the plasma is maintained, or the supply of the nitrogen-containing gas And the supply of the oxygen-containing gas is started .

The multilayer protective film forming method according to claim 2 is the multilayer protective film forming method according to claim 1 , wherein the silicon oxide film forming step is switched to the silicon nitride film forming step, or the silicon nitride film is formed. When the film forming step is switched to the silicon oxide film forming step, the temperature of the substrate over which the oxide semiconductor is formed is once lowered.

The method for forming a multilayer protective film according to claim 3 is the method for forming a multilayer protective film according to claim 1 or 2 , characterized in that the nitrogen-containing gas not containing hydrogen atoms is nitrogen gas.

The method for forming a multilayer protective film according to claim 4 is the method for forming a multilayer protective film according to any one of claims 1 to 3 , wherein the oxygen-containing gas not containing hydrogen atoms is oxygen gas. Features.

The method for forming a multilayer protective film according to claim 5 , wherein the oxide semiconductor includes an oxide of indium, gallium, and zinc in the method for forming a multilayer protective film according to any one of claims 1 to 4. It is characterized by that.

The method for forming a multilayer protective film according to claim 6 is the method for forming a multilayer protective film according to any one of claims 1 to 5 , wherein the multilayer protective film includes an undercoat layer and a gate protective film in a transistor structure. And at least one of a stopper layer and a passivation layer.

In order to achieve the above object, a method for forming a multilayer protective film according to claim 7 is a method for forming a multilayer protective film comprising a film containing at least nitrogen and silicon and a film containing oxygen and silicon while contacting the oxide semiconductor. A forming method comprising oxidizing a silicon chloride (SiCl ₄ ) gas or a silicon fluoride (SiF ₄ ) gas and at least one of an oxygen-containing gas containing no hydrogen atom and a nitrogen-containing gas containing no hydrogen atom. A multilayer protective film composed of at least two of a silicon film, a silicon nitride film, and a silicon oxynitride film is formed, and the at least two films constituting the multilayer protective film are one of the two films. When switching from one film forming step to the other film forming step, the supply of the oxygen-containing gas is stopped while the supply of the silicon chloride gas or the silicon fluoride gas is continued to maintain the plasma. The film is formed by performing a continuous film forming process in which the supply of the nitrogen-containing gas is started after stopping or the supply of the oxygen-containing gas is started after the supply of the nitrogen-containing gas is stopped. Features.

  According to the present invention, silicon chloride gas or silicon fluoride gas and an oxygen-containing gas not containing hydrogen atoms are used to form a silicon oxide film, and silicon chloride gas or silicon fluoride gas and hydrogen are used to form a silicon nitride film. Since a nitrogen-containing gas containing no atoms is used, hydrogen atoms do not enter defects in the silicon oxide film or the silicon nitride film, and the multilayer protective film does not contain hydrogen atoms. As a result, the need to perform a dehydrogenation step can be eliminated. In addition, since the silicon oxide film and the silicon nitride film are continuously formed, it is possible to prevent unnecessary components from being mixed into the multilayer protective film.

It is sectional drawing which shows schematically the structure of the plasma CVD film-forming apparatus as a multilayer protective film forming apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the bottom gate TFT formed by applying the formation method of the multilayer protective film which concerns on this Embodiment. It is a flowchart which shows the formation method of the multilayer protective film which concerns on this Embodiment. FIG. 3 is an enlarged cross-sectional view illustrating a stacked structure of a gate protective film in FIG. 2. It is sectional drawing which shows the structure of the modification of the bottom gate type TFT formed by applying the formation method of the multilayer protective film which concerns on this Embodiment. It is sectional drawing which shows the structure of the top gate type TFT formed by applying the formation method of the multilayer protective film which concerns on this Embodiment. It is sectional drawing which shows the structure of the modification of the top gate type TFT formed by applying the formation method of the multilayer protective film which concerns on this Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, a multilayer protective film forming apparatus according to an embodiment of the present invention will be described.

  FIG. 1 is a cross-sectional view schematically showing a configuration of a plasma CVD film forming apparatus as a multilayer protective film forming apparatus according to the present embodiment.

  In FIG. 1, a plasma CVD film forming apparatus 10 includes, for example, a substantially casing-shaped chamber 11 that accommodates a substrate (hereinafter simply referred to as “substrate”) S for an FPD or a sheet display, and a bottom portion of the chamber 11. A mounting table 12 that is disposed and mounts the substrate S on the upper surface, an ICP antenna 13 that is disposed outside the chamber 11 so as to face the mounting table 12 inside the chamber 11, and a ceiling portion of the chamber 11 are configured. A window member 14 interposed between the mounting table 12 and the ICP antenna 13.

  The chamber 11 has an exhaust device (not shown). The exhaust device evacuates the chamber 11 to decompress the inside of the chamber 11. The window member 14 of the chamber 11 is made of a dielectric and partitions the inside and the outside of the chamber 11.

  The window member 14 is supported on the side wall of the chamber 11 via an insulating member (not shown), and the window member 14 and the chamber 11 are not in direct contact and are not electrically connected. The window member 14 has a size that can cover at least the entire surface of the substrate S placed on the mounting table 12. The window member 14 may be composed of a plurality of divided pieces.

  Three gas introduction ports 15, 16, and 17 are provided on the side wall of the chamber 11, and the gas introduction port 15 is connected to a silicon-containing gas supply unit 18 disposed outside the chamber 11 through a gas introduction pipe 22. The gas introduction port 16 is connected to an oxygen-containing gas supply unit 19 and a nitrogen-containing gas supply unit 20 disposed outside the chamber 11 via a gas introduction tube 23, and the gas introduction port 17 is connected to the chamber via a gas introduction tube 24. 11 is connected to a noble gas supply unit 21 disposed outside.

The silicon-containing gas supply unit 18 supplies a silicon-containing gas, for example, silicon chloride (SiCl ₄ ) gas, into the chamber 11 through the gas inlet 15, and the oxygen-containing gas supply unit 19 passes through the gas inlet 16. Then, an oxygen-containing gas that does not contain hydrogen atoms, for example, oxygen gas, is supplied into the chamber 11, and the nitrogen-containing gas supply unit 20 is also supplied with nitrogen that does not contain hydrogen atoms into the chamber 11 through the gas inlet 16. A contained gas, for example, nitrogen gas is supplied, and the rare gas supply unit 21 supplies a rare gas, for example, argon gas, to the inside of the chamber 11 through the gas inlet 17.

  Each gas introduction pipe 22, 23, 24 has a mass flow controller and a valve (both not shown), and adjusts the flow rate of each gas supplied from the gas introduction ports 15, 16, and 17. In particular, the gas introduction pipe 23 has a three-way valve (not shown) and switches the gas supplied from the gas introduction port 16 to either oxygen gas or nitrogen gas.

  The ICP antenna 13 is formed of an annular conducting wire disposed along the upper surface of the window member 14, and is connected to a high frequency power supply 26 through a matching unit 25. The high frequency current from the high frequency power supply 26 flows through the ICP antenna 13, and the high frequency current causes the ICP antenna 13 to generate a magnetic field inside the chamber 11 through the window member 14. Since the magnetic field is generated due to the high-frequency current and changes with time, the time-changed magnetic field generates an induced electric field, and electrons accelerated by the induced electric field are introduced into the chamber 11. Inductively coupled plasma is generated by collision with gas molecules and atoms.

  In the plasma CVD film forming apparatus 10, cations and radicals are generated from silicon chloride gas, oxygen gas and argon gas supplied into the chamber 11 by inductively coupled plasma, and a silicon oxide film is formed on the substrate S by CVD. At the same time, cations and radicals are generated from the silicon chloride gas, nitrogen gas, and argon gas supplied into the chamber 11, and a silicon nitride film is formed on the substrate S by CVD, so that the silicon oxide film and the nitride are formed. A multilayer protective film made of a silicon film is formed. Note that argon gas is not a material gas that directly constitutes a silicon oxide film or a silicon nitride film, but an appropriate amount of silicon chloride gas, oxygen gas, and nitrogen gas, which are material gases that directly constitute a silicon oxide film or a silicon nitride film. It plays an auxiliary role in the film-forming process, such as adjusting the concentration and facilitating discharge for generating inductively coupled plasma.

  The plasma CVD film forming apparatus 10 further includes a controller 27 that controls the operation of each component of the plasma CVD film forming apparatus 10.

  FIG. 2 is a cross-sectional view showing a configuration of a bottom-gate TFT formed by applying the multilayer protective film forming method according to the present embodiment.

  In FIG. 2, the TFT 28 covers the undercoat layer 29 formed on the substrate S, the gate electrode 30 partially formed on the undercoat layer 29, and the undercoat layer 29 and the gate electrode 30. A gate protective film 31 formed of a multilayer protective film, a channel 32 formed on the gate protective film 31 so as to be disposed immediately above the gate electrode 30, and a channel 32 formed on the gate protective film 31. A source electrode 33 and a drain electrode 34 formed on both sides, and a passivation layer 35 made of a multilayer protective film formed so as to cover the channel 32, the source electrode 33 and the drain electrode 34 are provided.

  In the TFT 28, the channel 32 is made of IGZO, the gate protective film 31 has a silicon nitride film 31a and a silicon oxide film 31b laminated from below in the figure, and a passivation layer 35 is laminated from below in the figure. And a silicon nitride film 35b. In the gate protection film 31, the silicon oxide film 31 b is in contact with the channel 32, and in the passivation layer 35, the silicon oxide film 35 a is in contact with the channel 32.

  Here, since all of the silicon oxide film 31b, the silicon oxide film 35a, and the channel 32 are made of oxide and are easily compatible with each other, the gate protective film 31 is brought into contact with the channel 32 by bringing the silicon oxide film 31b or the silicon oxide film 35a into contact with the channel 32. Further, mutual peeling between the channel 32 and the passivation layer 35 can be suppressed.

  Note that the stacked form of the gate protective film 31 and the passivation layer 35 is not limited to that shown in FIG. 2. For example, in the gate protective film 31, a silicon oxide film 31 b and a silicon nitride film 31 a are stacked in this order from the bottom in the figure. The silicon film 31a may be brought into contact with the channel 32, or the silicon nitride film 35b and the silicon oxide film 35a may be laminated in this order from the lower side in the drawing in the passivation layer 35, and the silicon nitride film 35b may be brought into contact with the channel 32.

  FIG. 3 is a flowchart showing a method for forming a multilayer protective film according to the present embodiment.

  The flowchart of FIG. 3 is executed by the controller 27 controlling the operation of each component of the plasma CVD film forming apparatus 10 according to a predetermined program.

  First, the substrate S on which the undercoat layer 29 is formed and the gate electrode 30 is formed is carried into the chamber 11 of the plasma CVD film forming apparatus 10 and placed on the mounting table 12.

  Next, after reducing the pressure inside the chamber 11 and the degree of vacuum inside the chamber 11 reaches a predetermined value, silicon chloride gas, nitrogen gas and argon gas are supplied into the chamber 11 from the gas inlets 15, 16 and 17. The ICP antenna 13 forms an induction electric field inside the chamber 11 to generate inductively coupled plasma, and cations and radicals are generated from the silicon chloride gas, nitrogen gas and argon gas, and the silicon nitride film 31a is formed by CVD. Is formed so as to cover the undercoat layer 29 and the gate electrode 30 (step S31) (silicon nitride film forming step).

  Next, the supply of the nitrogen gas is stopped while continuing the supply of the silicon chloride gas and the argon gas and the generation of the induction electric field, and then the supply of the oxygen gas is started and the silicon oxide film 31b is formed by the CVD by the silicon nitride. A film is formed so as to cover the film 31a (step S32) (silicon oxide film forming step).

  Thereby, the gate protective film 31 having the silicon nitride film 31a and the silicon oxide film 31b is formed. When the process is switched from the formation of the silicon nitride film 31a to the formation of the silicon oxide film 31b and oxygen gas is supplied, generation of an induction electric field is continued, and there is some nitrogen gas. There is a period in which both cations and radicals generated from the gas are present. As a result, as shown in FIG. 4, an extremely thin silicon oxynitride film 31c is formed between the silicon nitride film 31a and the silicon oxide film 31b in the gate protection film 31, and the silicon oxynitride film 31c is formed of silicon oxide. Since the film 31b and the silicon nitride film 31a are harmonized with each other, layer separation of the silicon nitride film 31a and the silicon oxide film 31b in the gate protective film 31 can be suppressed.

  Next, the substrate S is unloaded from the plasma CVD film forming apparatus 10, and the channel 32, the source electrode 33, and the drain electrode 34 are formed in another film forming apparatus (not shown) (step S33).

  Next, after the substrate S is carried back into the chamber 11 of the plasma CVD film forming apparatus 10 and placed on the mounting table 12, the inside of the chamber 11 is depressurized, and the degree of vacuum inside the chamber 11 reaches a predetermined value. Silicon chloride gas, oxygen gas, and argon gas are supplied into the chamber 11 from the gas inlets 15, 16, 17, inductively coupled plasma is generated inside the chamber 11, and the silicon chloride gas, oxygen gas, and argon gas are used. By generating cations and radicals, a silicon oxide film 35a is formed by CVD so as to cover the channel 32, the source electrode 33 and the drain electrode 34 (step S34) (silicon oxide film forming step).

  Next, the supply of the silicon chloride gas and the argon gas and the generation of the induction electric field are continued, the supply of the oxygen gas is stopped, and then the supply of the nitrogen gas is started, and the silicon nitride film 35b is formed by silicon dioxide by CVD. A film is formed so as to cover the film 35a (step S35) (silicon nitride film forming step).

Thereby, the passivation layer 35 having the silicon oxide film 35a and the silicon nitride film 35b is formed. When the process is switched from the formation of the silicon oxide film 35a to the formation of the silicon nitride film 35b and nitrogen gas is supplied, the induction electric field continues to be generated and some oxygen gas is present. There is a period in which both cations and radicals generated from oxygen gas and nitrogen gas exist. As a result, an extremely thin silicon oxynitride film (not shown) is formed between the silicon oxide film 35a and the silicon nitride film 35b in the passivation layer 35. Therefore, the silicon oxide film 35a and the silicon nitride film 35b are also formed in the passivation layer 35. Layer separation can be suppressed.

  Next, after the formation of the passivation layer 35, the present method is terminated.

  According to the method for forming a multilayer protective film in accordance with the present embodiment, silicon chloride gas and oxygen gas not containing hydrogen atoms are used for forming silicon oxide films 31b and 35a, and silicon nitride films 31a and 35b are formed. Since silicon chloride gas and nitrogen gas not containing hydrogen atoms are used, the gate protective film that contacts the channel 32 made of IGZO without causing hydrogen atoms to enter the defects of the silicon oxide films 31b and 35a and the silicon nitride films 31a and 35b. 31 and the passivation layer 35 do not contain hydrogen atoms. As a result, it is possible to eliminate the need to perform a dehydrogenation step in forming the gate protective film 31 and the passivation layer 35.

  In the multilayer protective film forming method described above, the silicon nitride film 31a and the silicon oxide film can be obtained by switching the nitrogen gas to the oxygen gas or switching the oxygen gas to the nitrogen gas without carrying the substrate S out of the chamber 11. Since the film formation of 31b and the film formation of the silicon oxide film 35a and the silicon nitride film 35b are continuously performed, it is possible to prevent unnecessary components from being mixed in the gate protection film 31 and the passivation layer 35. In both cases, the throughput can be shortened.

  Furthermore, in the method for forming the multilayer protective film described above, when the process switches from the formation of the silicon nitride film 31a to the formation of the silicon oxide film 31b, and the process changes from the formation of the silicon oxide film 35a to the silicon nitride film 35b. When switching to film formation, the supply of the silicon chloride gas and the argon gas is continued and the silicon-containing gas and the rare gas are not switched, so that the throughput can be further shortened.

  In the multilayer protective film formation method described above, the generation of the induction electric field is continued, so that the inductively coupled plasma is not extinguished or regenerated, so that the generation of particles accompanying the extinction or regeneration of the plasma can be suppressed.

  Further, in the above-described method for forming a multilayer protective film, cations and radicals are generated from silicon chloride gas, oxygen gas and nitrogen gas by inductively coupled plasma, and silicon oxide films 31b and 35a and silicon nitride films 31a and 35b are formed by CVD. Form a film. Since the density of inductively coupled plasma is high and the cationization and radicalization of silicon chloride gas, oxygen gas and nitrogen gas are promoted, silicon oxide at a relatively low temperature, for example, 200 ° C. or less, more preferably 150 ° C. or less. Films 31b and 35a and silicon nitride films 31a and 35b can be formed. As a result, when the TFT 28 is applied to the organic EL, the sheet display substrate S can be prevented from being deformed or altered by heat.

In the above-described method for forming the multilayer protective film, silicon chloride gas is used as the silicon-containing gas. However, the silicon-containing gas is not limited to this. For example, silicon fluoride (SiF ₄ ) gas, silicon bromide (SiBr ₄ ) gas Alternatively, silicon iodide (SiI ₄ ) gas may be used. Moreover, although oxygen gas was used as oxygen-containing gas, oxygen-containing gas is not restricted to this, For example, you may use ozone gas.

Further, although nitrogen gas is used as the nitrogen-containing gas, the nitrogen-containing gas is not limited to this. For example, nitrogen monoxide gas, nitrous oxide (N ₂ O) gas, nitrogen trifluoride (NF ₃ ) gas, three Nitrogen bromide (NBr ₃ ) gas or nitrogen trichloride (NCl ₃ ) gas may be used. Moreover, although argon gas was used as a noble gas, a noble gas is not restricted to this, For example, you may use neon gas, xenon gas, and krypton gas.

  The silicon oxide films 31b and 35a and the silicon nitride films 31a and 35b can be formed by a plasma CVD apparatus using a plasma other than inductively coupled plasma, but silicon chloride gas, silicon fluoride gas, odor In the case where the film formation process is performed using silicon nitride gas or silicon iodide gas and nitrogen gas, a more excellent film formation process can be performed by using inductively coupled plasma capable of generating high-density plasma. In this embodiment, an inductively coupled plasma CVD film forming apparatus using a dielectric is used for the window member 14, but inductively coupled plasma CVD using a metal window composed of a plurality of divided pieces as a window member is used. A membrane device may be used, and in that case, the form of the ICP antenna 13 is not limited to an annular shape, and may be another form, for example, a straight line, as long as the form traverses each divided piece.

  In the above-described method for forming a multilayer protective film, the channel 32 is made of IGZO, but the channel 32 may be made of another oxide semiconductor. For example, in the case of an oxide semiconductor in which characteristics are changed by desorption of oxygen atoms due to mixed hydrogen atoms, by applying the present invention, an effect similar to that in the case of forming the channel 32 with IGZO can be obtained. In the above-described method for forming a multilayer protective film, the gate protective film 31 and the passivation layer 35 have a two-layer structure including a silicon nitride film and a silicon oxide film, but the multilayer protective film such as the gate protective film 31 and the passivation layer 35 is used. The structure is not limited to a two-layer structure, and may be a structure of three or more layers, all of which do not contain hydrogen atoms.

  Furthermore, although the gate protective film 31 and the passivation layer 35 that are in contact with the channel 32 do not contain hydrogen atoms, both films do not contain hydrogen atoms in the process of forming the gate protective film 31 and the passivation layer 35. If it is difficult to achieve this, at least one of the gate protective film 31 and the passivation layer 35 should not contain hydrogen atoms. Even in this case, desorption of oxygen atoms from IGZO can be suppressed to some extent.

  In the present embodiment, when forming the gate protection film 31 and the passivation layer 35, a silicon oxynitride film may be formed instead of the silicon oxide films 31b and 35a, and the silicon nitride films 31a and 35b are also formed. Instead of this, a silicon oxynitride film may be formed.

  In the multilayer protective film formation method described above, when the process switches from the formation of the silicon nitride film 31a to the formation of the silicon oxide film 31b, or the process changes from the formation of the silicon oxide film 35a to the silicon nitride film 35b. When switching to film formation, the temperature of the substrate S may be once lowered, or the supply of silicon chloride gas may be stopped. Furthermore, in an environment where the generation of particles during generation and extinction of plasma is extremely small, the inductively coupled plasma may be once extinguished when the processing is switched. Thereby, the film formation reaction after the formation of the silicon nitride film 31a can be suppressed until the formation of the silicon oxide film 31b, or the film formation reaction after the formation of the silicon oxide film 35a can be suppressed. Film formation can be suppressed, and formation of a film other than the silicon oxide film and the silicon nitride film between the silicon oxide films 31b and 35a and the silicon nitride films 31a and 35b can be suppressed.

  Although the present invention has been described above by using the embodiment, the present invention is not limited to the above-described embodiment.

  For example, the above-described method for forming a multilayer protective film can be applied not only to the TFT 28 of FIG. 2 but also to the formation of a multilayer protective film in TFTs having other configurations.

  FIG. 5 is a cross-sectional view showing a configuration of a modified example of a bottom gate type TFT formed by applying the method for forming a multilayer protective film according to the present embodiment.

  In FIG. 5, the TFT 36 includes an undercoat layer 29, a gate electrode 30, a gate protective film 31, a channel 32, a source electrode 33 and a drain electrode 34, and a multilayer protective film formed so as to cover the channel 32. An etching stopper layer 37, and a passivation layer 38 formed to cover the etching stopper layer 37, the source electrode 33, and the drain electrode 34.

  In the TFT 36, the etching stopper layer 37 has a silicon oxide film 37 a and a silicon nitride film 37 b stacked from below in the figure, and in the etching stopper layer 37, the silicon oxide film 37 a contacts the channel 32. Thereby, mutual peeling of the channel 32 and the etching stopper layer 37 can be suppressed.

  In addition, in the etching stopper layer 37, a silicon nitride film 37b and a silicon oxide film 37a may be stacked in this order from the lower side in the drawing, and the silicon nitride film 37b may be in contact with the channel 32.

  In the TFT 36, steps S31 and S32 of FIG. 3 are applied to the formation of the gate protective film 31, and the same processing as steps S34 and S35 of FIG. 3 is applied to the formation of the etching stopper layer 37. Thus, silicon chloride gas and oxygen gas that do not contain hydrogen atoms are used to form the silicon oxide films 31b and 37a, and silicon chloride gas and nitrogen gas that do not contain hydrogen atoms are used to form the silicon nitride films 31a and 37b. Therefore, hydrogen atoms do not enter defects in the silicon oxide films 31b and 37a and the silicon nitride films 31a and 37b, and oxygen atoms can be prevented from desorbing from the channel 32.

  FIG. 6 is a cross-sectional view showing a configuration of a top gate type TFT formed by applying the multilayer protective film forming method according to the present embodiment.

  In FIG. 6, the TFT 38 includes an undercoat layer 39 made of a multilayer protective film formed on the substrate S, a channel 40 partially formed on the undercoat layer 39, and the undercoat layer 39. A source electrode 41 and a drain electrode 42 formed on both sides of the channel 40; a gate protective film 43 made of a multilayer protective film formed so as to cover the channel 40, the source electrode 41 and the drain electrode 42; And a passivation layer 45 formed so as to cover the gate electrode 44 and the gate protective film 43.

  In the TFT 38, the channel 40 is made of IGZO, the undercoat layer 39 has a silicon nitride film 39a and a silicon oxide film 39b stacked from below in the figure, and a gate oxide film 43 is stacked from below in the figure. 43a and a silicon nitride film 43b. In the undercoat layer 39, the silicon oxide film 39 b is in contact with the channel 40, and in the gate protection film 43, the silicon oxide film 43 a is in contact with the channel 40. Thereby, mutual peeling of the channel 40, the undercoat layer 39, and the gate protective film 43 can be suppressed.

  In the undercoat layer 39, the silicon oxide film 39b and the silicon nitride film 39a may be stacked in this order from the lower side in the figure, and the silicon nitride film 39a may be in contact with the channel 40, and the gate protective film 43 is nitrided from the lower side in the figure. The silicon nitride film 43b may be stacked in this order to bring the silicon nitride film 43b into contact with the channel 40.

  In the TFT 38, the same processing as in steps S31 and S32 in FIG. 3 is applied to the formation of the undercoat layer 39, and the same processing as in steps S34 and S35 in FIG. 3 is applied to the formation of the gate protective film 43. Thus, silicon chloride gas and oxygen gas that do not contain hydrogen atoms are used to form the silicon oxide films 39b and 43a, and silicon chloride gas and nitrogen gas that do not contain hydrogen atoms are used to form the silicon nitride films 39a and 43b. Therefore, hydrogen atoms do not enter the defects of the silicon oxide films 39b and 43a and the silicon nitride films 39a and 43b, and oxygen atoms can be prevented from desorbing from the channel 40.

  FIG. 7 is a cross-sectional view showing a configuration of a modified example of a top gate type TFT formed by applying the method for forming a multilayer protective film according to the present embodiment.

  In FIG. 7, the TFT 46 includes an undercoat layer 39 made of a multilayer protective film formed on the substrate S, a channel 40 partially formed on the undercoat layer 39, and a source connected to the channel 40. The electrode 47 and the drain electrode 48, the gate protective film 43 formed so as to cover the undercoat layer 39 and the channel 40, and the gate electrode formed so as to be disposed on the channel 40 on the gate protective film 43 44, an interlayer insulating film 49 formed so as to cover the gate electrode 44 and the gate protective film 43, and a passivation layer 50 formed so as to cover the interlayer insulating film 49, the source electrode 47 and the drain electrode 48.

  In the TFT 46 as well as the TFT 38, the silicon oxide film 39 b is in contact with the channel 40 in the undercoat layer 39, and the silicon oxide film 43 a is in contact with the channel 40 in the gate protection film 43. Thereby, mutual peeling of the channel 40, the undercoat layer 39, and the gate protective film 43 can be suppressed.

  Similar to TFT 38, silicon nitride film 39 a may be in contact with channel 40 in undercoat layer 39, and silicon nitride film 43 b may be in contact with channel 40 in gate protection film 43.

  In the TFT 46, similarly to the TFT 38, the same processing as in steps S31 and S32 in FIG. 3 is applied to the formation of the undercoat layer 39, and the same processing as in steps S34 and S35 in FIG. 3 is applied to the formation of the gate protective film 43. To do. Thereby, hydrogen atoms do not enter the defects of the silicon oxide films 39b and 43a and the silicon nitride films 39a and 43b, and the oxygen atoms can be prevented from desorbing from the channel 40.

  Another object of the present invention is to supply a computer, for example, the controller 27, with a storage medium storing software program codes for realizing the functions of the above-described embodiments, and the CPU of the controller 27 is stored in the storage medium. It is also achieved by reading and executing the program code.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Examples of the storage medium for supplying the program code include RAM, NV-RAM, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD (DVD). -ROM, DVD-RAM, DVD-RW, DVD + RW) and other optical disks, magnetic tapes, non-volatile memory cards, other ROMs, etc., as long as they can store the program code. Alternatively, the program code may be supplied to the controller 27 by downloading from another computer or database (not shown) connected to the Internet, a commercial network, a local area network, or the like.

  Further, by executing the program code read by the controller 27, not only the functions of the above-described embodiments are realized, but also an OS (operating system) running on the CPU based on the instruction of the program code, etc. Includes a case where part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing.

  Further, after the program code read from the storage medium is written in the memory provided in the function expansion board inserted in the controller 27 or the function expansion unit connected to the controller 27, the program code is read based on the instruction of the program code. A case where the CPU of the function expansion board or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing is also included.

  The form of the program code may include an object code, a program code executed by an interpreter, script data supplied to the OS, and the like.

S substrate 10 plasma CVD film forming apparatus 13 ICP antenna 18 silicon-containing gas supply unit 19 oxygen-containing gas supply unit 20 nitrogen-containing gas supply unit 28, 36, 38, 46 TFT
31, 43 Gate protection film 31a, 35b, 37b, 39a, 43b Silicon nitride film 31b, 35a, 37a, 39b, 43a Silicon oxide film 31c Silicon oxynitride film 32, 40 Channel 35 Passivation layer 37 Etching stopper layer 39 Undercoat layer

Claims (7)

A method for forming a multilayer protective film that is in contact with an oxide semiconductor and includes at least a silicon nitride film and a silicon oxide film,
Forming a silicon oxide film by generating plasma using a silicon chloride (SiCl ₄ ) gas or a silicon fluoride (SiF ₄ ) gas and an oxygen-containing gas not containing hydrogen atoms;
A silicon nitride film forming step of forming the silicon nitride film by generating plasma using the silicon chloride gas or the silicon fluoride gas and a nitrogen-containing gas not containing hydrogen atoms,
When switching from the silicon oxide film formation step to the silicon nitride film formation step, or when switching from the silicon nitride film formation step to the silicon oxide film formation step,
While maintaining the plasma by continuously supplying the silicon chloride gas or the silicon fluoride gas,
The multilayer protective film is characterized in that the supply of the nitrogen-containing gas is started after the supply of the oxygen-containing gas is stopped, or the supply of the oxygen-containing gas is started after the supply of the nitrogen-containing gas is stopped . Forming method. When the silicon oxide film formation step is switched to the silicon nitride film formation step , or when the silicon nitride film formation step is switched to the silicon oxide film formation step, the substrate on which the oxide semiconductor is once formed method for forming a multilayer protective film of claim 1, wherein reducing the temperature. 3. The method for forming a multilayer protective film according to claim 1, wherein the nitrogen-containing gas not containing hydrogen atoms is nitrogen gas. The method for forming a multilayer protective film according to any one of claims 1 to 3 , wherein the oxygen-containing gas not containing hydrogen atoms is oxygen gas. The oxide semiconductor is indium, the method of forming the multilayer protective film according to any one of claims 1 to 4, characterized in that it comprises an oxide of gallium and zinc. It said multilayer protective film, the undercoat layer in the transistor structure, a gate protective film, the multilayer protective film according to any one of claims 1 to 5, characterized in that at least one of the stopper layer and a passivation layer Forming method. A method for forming a multilayer protective film that is in contact with an oxide semiconductor and includes a film containing at least nitrogen and silicon and a film containing oxygen and silicon,
Using a silicon chloride (SiCl ₄ ) gas or a silicon fluoride (SiF ₄ ) gas and at least one of an oxygen-containing gas not containing hydrogen atoms and a nitrogen-containing gas not containing hydrogen atoms, a silicon oxide film and a silicon nitride film And a multilayer protective film comprising at least two of the silicon oxynitride films,
The at least two films constituting the multilayer protective film are formed of the silicon chloride gas or the silicon fluoride gas when the film forming step of one of the two films is switched to the film forming step of the other film. While maintaining the plasma while continuing the supply, the supply of the oxygen-containing gas is started after the supply of the oxygen-containing gas is stopped, or the supply of the oxygen-containing gas is stopped after the supply of the nitrogen-containing gas is stopped. A method for forming a multilayer protective film, wherein the film is formed by executing a continuous film forming process to be started .

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