JP2006032596A - Method for manufacturing gate insulating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a gate insulating film of a high quality more quickly without increasing a cost. <P>SOLUTION: By an atomic layer growing method which repeats a cycle of the supply of a silicon material gas 121 to a purge, to a supply of an oxygen material gas 122, and to the purge; a silicon oxide layer 154 is formed. Thereafter, a mixed gas in which the silicon material gas 121 is mixed with the oxygen material gas 122 is supplied onto the silicon oxide layer 154. In this state, for instance, the insulating layer composed of silicon oxide is formed with a film thickness of about 55 nm as a whole thick enough to withstand a gate voltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a gate insulating film used for a low-temperature polysilicon TFT or the like.

  An active matrix liquid crystal display device using a TFT (Thin Film Transistor) formed on a glass substrate as a switching element has been developed as a high-quality flat display. Since the TFT used as the switching element is formed on a glass substrate having low heat resistance, for example, the gate insulating film is formed by a plasma CVD (Chemical Vapor Deposition) method that does not perform high-temperature processing. .

  However, a film formed by the CVD method has many crystal defects in the film, and is not very reliable because it is not dense enough. In addition, there is a problem that the interface between the semiconductor and the insulating film is damaged due to the influence of charged particles in the plasma when the film is formed. For example, when the interface is damaged by plasma, a trap is formed, which greatly reduces the performance. As described above, in the field effect transistor, when the gate insulating film is formed by the CVD method, the characteristics of the transistor are not so good, and there is a problem that the change with time is large.

  As a technique for solving such a problem, a technique for forming a gate insulating film by an atomic layer growth method has been proposed (see Patent Documents 1, 2, 3, and 4). The atomic layer growth method is a technique for forming a thin film in units of atomic layers by alternately supplying a raw material of each element constituting a film to be formed to a substrate. In the atomic layer growth method, only one layer or n layer is adsorbed on the surface while the raw materials for each element are being supplied, so that excess raw materials do not contribute to the growth. This is called self-stopping action of growth. Since the atomic layer growth method does not use plasma, a high-quality film can be formed.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
JP-A-1-179423 JP-A-5-160152 JP 2001-172767 A JP 2002-353154 A

  However, in the above-described atomic layer growth method, since a thin film is formed in units of atomic layers, there is a problem that a long time is required for forming the film. The gate insulating film of the TFT has a film thickness of about 100 nm, and requires a very long time if formed by the conventional atomic layer growth method, which is not realistic.

  An insulating film formed by atomic layer deposition is arranged as a buffer layer at the interface with the semiconductor, and an insulating film is formed on the insulating film at a higher speed by plasma CVD. There is also a technique for shortening the formation time. However, this technique has a problem in that the cost for manufacturing is increased because the raw material and apparatus for applying the atomic layer growth method are different from the raw material and apparatus for using the CVD method.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to allow a high-quality gate insulating film to be formed more quickly without causing an increase in cost.

In the method for manufacturing a gate insulating film according to the present invention, a first source gas composed of a compound of a first substance is supplied to a first substrate disposed inside a reaction vessel and heated to a predetermined temperature. A first step in which an adsorption layer in which a compound of a substance is adsorbed on a substrate is formed; and a second step of removing the first source gas from the inside of the reaction vessel after stopping the supply of the first source gas And supplying a second source gas containing a second substance composed of at least one of oxygen and nitrogen to the surface of the adsorption layer, thereby providing a first insulating layer made of a compound of the first substance and the second substance of the adsorption layer. A third step of forming a state formed on the substrate, a first source gas and a second source gas are supplied to the surface of the first insulating layer, and a second step comprising a compound of the first substance and the second substance. And at least a fourth step in which the insulating layer is formed on the surface of the first insulating layer, 1 insulating layer and the gate insulating film is composed of a second insulating layer is obtained by such a state of being formed on the substrate.
Therefore, the surface of the lower layer on which the first insulating layer is formed is not irradiated with plasma, and damage due to plasma irradiation is unlikely to occur between the gate insulating film and this lower layer.

In the above method for manufacturing a gate insulating film, a plurality of first insulating layers are formed by repeating a series of cycles including the first step, the second step, and the third step, and the plurality of first insulating layers are formed. The second insulating layer may be formed.
If the first material is silicon, a gate insulating film made of a silicon compound such as silicon oxide, silicon nitride, or silicon oxynitride can be formed. If the first material is hafnium, a gate insulating film made of hafnium oxide can be formed. If the first material is zirconium, a gate insulating film made of zirconium dioxide can be formed.

In another method of manufacturing a gate insulating film according to the present invention, a first source gas composed of a compound of a first substance is supplied onto a substrate disposed in a reaction vessel and heated to a predetermined temperature. A first step in which an adsorption layer in which a compound of the first substance is adsorbed on the substrate is formed; and after the supply of the first source gas is stopped, the first source gas is removed from the inside of the reaction vessel. A first compound composed of a compound of the first material and the second material in the adsorption layer by supplying a second source gas containing a second material comprising at least one of oxygen and nitrogen to the surface of the adsorption layer in two steps A third step of forming a layer on the substrate, a fourth step of removing the second source gas from the inside of the reaction vessel after stopping the supply of the second source gas, and a compound of the third substance Supplying a third source gas composed of the first material layer to the surface of the first compound layer; After the fifth step of forming the second compound layer made of the second substance and the compound of the third substance on the substrate, and after stopping the supply of the third source gas, the third step is performed from the inside of the reaction vessel. A sixth step of removing the source gas, and supplying a second source gas to the surface of the second compound layer to form a first insulating layer made of a compound of the first substance, the second substance, and the third substance on the substrate A seventh step of forming a state, a first source gas, a second source gas, and a third source gas are supplied to the surface of the first insulating layer, and the first material, the second material, and the third material At least an eighth step in which a second insulating layer made of a compound is formed on the surface of the first insulating layer, and a gate insulating film composed of the first insulating layer and the second insulating layer is formed on the substrate. It is set as the state formed in this.
Therefore, the surface of the lower layer on which the first insulating layer is formed is not irradiated with plasma, and damage due to plasma irradiation is unlikely to occur between the gate insulating film and this lower layer.

In the above method for manufacturing a gate insulating film, a plurality of first insulating layers are formed by repeating a series of cycles including the first step, the second step, and the third step, and the plurality of first insulating layers are formed. The second insulating layer may be formed.
The first material is hafnium and the second material is silicon. The first material is hafnium, and the second material is aluminum. The first material is zirconium, and the second material is silicon.

  As described above, according to the present invention, after the first insulating layer having a predetermined thickness is formed by the atomic layer growth method, each source gas of the elements constituting the film used in the atomic layer growth method is simultaneously supplied. Since the second insulating layer is laminated by the CVD method and the gate insulating film is produced by these, it is possible to form a high-quality gate insulating film more quickly without causing an increase in cost. Effect.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are process diagrams for explaining a method for manufacturing a gate insulating film according to an embodiment of the present invention. 1 and 2, the case where the method of the present invention is applied to a top gate type thin film transistor used in a liquid crystal display device or the like will be described.

  First, as shown in FIG. 1A, a source electrode 102 and a drain electrode 103 are formed on a glass substrate 101 at a predetermined interval. These can be formed, for example, by forming a predetermined metal film on the glass substrate 101 and then processing the metal film by a known photolithography technique and etching technique. A substrate made of a material other than glass may be used.

  Next, as shown in FIG. 1B, a polysilicon layer (low-temperature polysilicon layer) 104 is formed on the glass substrate 101 so as to extend over the source electrode 102 and the drain electrode 103. For example, after forming an amorphous Si film with a thickness of about 100 nm on the glass substrate 101, the polysilicon layer 104 is irradiated with a linear excimer laser so as to continuously overlap the substrate from one direction. Thus, amorphous Si can be polycrystallized, and the polycrystallized film can be formed by processing with a known photolithography technique and etching technique.

Next, the formed polysilicon layer 104 and the glass substrate 101 including each electrode are fixed inside a predetermined reaction vessel, and the pressure in the reaction vessel is set to a pressure of about 2 to 3 Pa by a predetermined exhaust mechanism. Next, the substrate temperature is set to 400 ° C., a silicon source gas 121 made of SiCl ₄ is introduced into the reaction vessel, and the silicon source gas 121 is supplied onto the polysilicon layer 104 as shown in FIG. State. The silicon source gas 121 is supplied for about 30 seconds. Thus, a state in which SiCl ₄ molecules layer SiCl ₄ molecules are adsorbed as a raw material on the polysilicon layer 104 (adsorption layer) 151 is formed.

Next, the introduction of the silicon source gas 121 into the reaction vessel is stopped, an inert gas such as nitrogen gas is introduced into the reaction vessel, the inside of the reaction vessel is purged with the inert gas, and the polysilicon layer 104 The surplus gas other than the one adsorbed on (SiCl ₄ molecular layer 151) is removed from the reaction vessel. The purge is performed for about 30 seconds. The inert gas is supplied vertically from directly above the substrate.

Next, an oxygen source gas 122 made of H ₂ O is introduced into the reaction vessel so that the oxygen source gas 122 is supplied to the surface of the SiCl ₄ molecular layer 151. The supply of the oxygen source gas 122 is performed for about 30 seconds. As a result, molecules adsorbed on the surface of the polysilicon layer 104 (SiCl ₄ molecular layer 151) are oxidized, and as shown in FIG. It is assumed that the silicon oxide layer 152 is formed. The substrate temperature is kept at 400 ° C.

Next, the inside of the reaction vessel is purged with an inert gas so that the inert gas is supplied onto the polysilicon layer 104 (silicon oxide layer 152), and the oxygen source gas is removed from above the silicon oxide layer 152. It is assumed that The purge is performed for about 30 seconds.
Next, as shown in FIG. 1 (e), a silicon source gas 121 made of SiCl ₄ is supplied onto the silicon oxide layer 152 corresponding to one atomic layer that has already been formed. It is assumed that a simple SiCl ₄ molecular layer 153 is formed.

Next, an oxygen source gas 122 made of H ₂ O is introduced into the reaction vessel so that the oxygen source gas 122 is supplied to the surface of the SiCl ₄ molecular layer 153. The supply of the oxygen source gas 122 is performed for about 30 seconds.
As a result, the molecules adsorbed on the surface of the silicon oxide layer 152 (SiCl ₄ molecular layer 153) are oxidized, and as shown in FIG. It is assumed that the silicon oxide layer 154 is formed.

  By repeating the process described with reference to FIGS. 1C to 1D 30 times, for example, 30 times, a silicon oxide film having a thickness of about 5 nm is formed. In the description of FIG. 1C to FIG. 1F, the above cycle is repeated twice. Note that the repetition of the cycle is not limited to 30 times, and may be 1 time or 20 times.

As described above, a thin silicon oxide film having a thickness of about 5 nm is formed on the polysilicon layer 104 by atomic layer growth, and then the silicon source gas made of SiCl ₄ and H ₂ O are formed inside the reaction vessel. Oxygen source gas is supplied, and the mixed gas 123 in which these are mixed is supplied onto the silicon oxide film, and silicon oxide is deposited to a thickness of about 50 nm, for example.
As a result, as shown in FIG. 2G, an insulating layer 105 having a thickness of about 55 nm is formed on the glass substrate 101 including the polysilicon layer 104. The insulating layer 105 functions as a gate insulating film (withstands gate voltage). Is obtained.

  As described above, first, after a thin silicon oxide film is formed by atomic layer growth, a predetermined method is applied by CVD using a gas in which a silicon source gas and an oxygen source gas used in the atomic layer growth method are mixed. After the insulating layer 105 is formed to a thickness, as shown in FIG. 2H, the gate electrode 106 made of, for example, aluminum is formed on the insulating layer 105 in a region sandwiched between the source electrode 102 and the drain electrode 103. Is formed.

  For example, an aluminum film having a thickness of about 100 nm is formed over the insulating layer 105, a resist pattern having a desired shape is formed on the formed aluminum film, and the aluminum film is selectively etched using the resist pattern as a mask. Thus, the gate electrode 106 can be formed.

  Next, the insulating layer 105 is selectively etched using the resist pattern used to form the gate electrode 106, so that the gate insulating film 107 is formed as shown in FIG. Further, by these processes, the polysilicon layer 104 in the regions on both sides of the gate electrode 106 is exposed.

  Next, by using the gate electrode 106 as a mask, for example, phosphorus is ion-implanted into the polysilicon layer 104 exposed on both sides of the gate electrode 106, so that a source 108 and a drain 109 are formed as shown in FIG. Is formed. As a result, a source 108 ohmically connected to the source electrode 102 and a drain 109 ohmically connected to the drain electrode 103 are formed.

  The region below the gate electrode 106 of the polysilicon layer 104 is not doped with ions and is non-doped and becomes a region where a channel is formed (channel region). Accordingly, the thin film transistor illustrated in FIG. 2J includes a source 108 and a drain 109 which are disposed so as to sandwich the channel region, a gate insulating film 107 formed over the channel region, and a gate insulating film 107. The gate electrode 106 is formed.

In the thin film transistor (field effect transistor) shown in FIG. 2J described above, the gate insulating film 107 is formed by processing the insulating layer 105 formed by the atomic layer growth method and the CVD method. Therefore, in this embodiment, the portion of the gate insulating film 107 in contact with the channel region of the polysilicon layer 104 is composed of an SiO ₂ film formed by atomic layer growth.

As a result, according to the field effect transistor according to the present embodiment, the interface between the channel region of the semiconductor layer and the gate insulating film is not exposed to plasma. The increase can be suppressed, and the deterioration of transistor characteristics can be suppressed.
In addition, since the silicon oxide film formed by the atomic layer growth method does not need to be formed as thick as about 5 nm, the present embodiment is compared with the case where the gate insulating film is formed only by the atomic layer growth method. According to the method of this embodiment, the gate insulating film can be manufactured in a shorter time.

  By the way, the above-described gate insulating film can be formed by, for example, the apparatus shown in FIG. The processing apparatus illustrated in FIG. 3 includes a film formation chamber 301 in which a film is grown in a gas phase, and a substrate table 302 provided with a heating mechanism disposed inside the film formation chamber 301. The film forming chamber 301 includes an exhaust mechanism 304 and gas supply mechanisms 305, 306, and 307.

  In the processing apparatus shown in FIG. 3, first, the substrate 303 to be processed is loaded onto the substrate table 302, the film formation chamber 301 is sealed, and then the substrate 303 is heated to 400 ° C. by the heating mechanism of the substrate table 302. Each of the above-described films can be formed by supplying a predetermined gas by the gas supply mechanisms 305, 306, and 307.

Next, characteristics of the gate insulating film in this embodiment described above will be described.
In this evaluation, a sample is prepared as follows. First, a gate insulating film is formed by the above-described method of the present invention on a substrate made of single crystal silicon having a (100) plane as a main surface, and electrodes are formed on the back surface and the gate insulating film of the substrate. A capacitor is formed. The formation of the gate insulating film is the same as the method described with reference to FIGS.
As a result of investigating the electrical characteristics of the sample manufactured as described above, the gate insulating film has an interface state density of 8 × 10 ¹⁰ cm ⁻² eV ⁻¹ , a fixed charge density of 3 × 10 ¹¹ cm ⁻² , and an insulating property. The breakdown voltage is 6 MV / cm. Thus, according to the present invention, a high-quality gate insulating film can be obtained.

  In the above description, the silicon oxide film is described as an example of the gate insulating film, but the present invention is not limited to this. For example, a gate insulating film made of silicon nitride can be formed by using a nitrogen source gas such as ammonia instead of the oxygen source gas. In the description using FIGS. 1C to 2A, if the oxygen source gas 122 is replaced with a nitrogen source gas, a gate insulating film made of high-quality silicon nitride can be obtained in the same manner as described above. Can be made.

  The case of silicon nitride will be described. First, the substrate to be treated is fixed inside a predetermined reaction vessel, the inside of the reaction vessel is evacuated to a pressure of about 4 Pa by a predetermined exhaust mechanism, and then the substrate temperature is set to 500 ° C. In this state, the silicon source gas made of dichlorosilane is introduced into the reaction vessel, and the silicon source gas is supplied onto the substrate. In the state where the silicon source gas is introduced, the internal pressure of the reaction vessel is set to about 66 Pa, and the time during which the silicon source gas is supplied onto the substrate is set to about 30 seconds. As a result, a dichlorosilane molecular layer (adsorption layer) is formed on the surface of the gate insulating film of the substrate.

Next, the introduction of the silicon source gas into the reaction vessel is stopped, an inert gas such as nitrogen gas is introduced into the reaction vessel, the inside of the reaction vessel is purged with the inert gas, and excess gas is removed from the reaction vessel. Removed. The purge is performed for about 30 seconds.
Next, a nitrogen source gas made of ammonia is introduced into the reaction vessel so that the nitrogen source gas is supplied to the surface of the dichlorosilane molecular layer. In the state where the nitrogen source gas is introduced, the internal pressure of the reaction vessel is set to about 66 Pa, and the supply of the nitrogen source gas is performed for about 30 seconds. As a result, the dichlorosilane molecular layer is nitrided, and a silicon nitride layer equivalent to one atomic layer of silicon is formed on the substrate. The substrate temperature is maintained at 500 ° C.

Next, the inside of the reaction vessel is purged with an inert gas so that the inert gas is supplied onto the silicon nitride, and the nitrogen source gas is removed from the silicon nitride layer. The purge is performed for about 30 seconds.
Next, a silicon source gas is supplied onto the silicon nitride layer for one atomic layer that has already been formed, so that a new dichlorosilane molecular layer is formed on the silicon nitride layer.
Next, a nitrogen source gas is introduced into the reaction vessel so that the nitrogen source gas is supplied to the surface of the dichlorosilane molecular layer. The nitrogen source gas is supplied for about 30 seconds.

As a result, the dichlorosilane molecular layer adsorbed on the surface of the silicon nitride layer is oxidized, and a silicon nitride layer corresponding to two silicon atomic layers is formed.
By repeating the silicon source gas supply → purge → nitrogen source gas supply → purge cycle described above, for example, 100 times, a silicon nitride film having a desired film thickness is formed.

  Next, the silicon source gas and the nitrogen source gas are supplied to the inside of the reaction vessel, and the mixed gas in which these are mixed is supplied onto the silicon nitride film, and silicon nitride is formed to a desired film thickness. accumulate. For example, a silicon source gas is supplied with a carrier gas having a flow rate of 15 sccm, a nitrogen source gas is supplied with a carrier gas having a flow rate of 60 sccm, the pressure in the reaction vessel is about 27 Pa, and the substrate temperature is about 600 ° C. , About 20 minutes. Note that sccm indicates “standard cc / min” and is a standardized flow rate per minute (cc) by atmospheric pressure or temperature.

As a result, a state is obtained in which an insulating layer made of silicon nitride (Si ₃ N ₄ ) having a thickness of about 30 nm is formed on the gate insulating film forming surface on the substrate.
When an insulating layer made of silicon nitride formed as described above is used as a gate insulating film, the electrical characteristics are as follows: interface state density is 3 × 10 ¹¹ cm ⁻² eV ⁻¹ , and fixed charge density is 5 × 10. ¹¹ cm ⁻² and the withstand voltage is 7 MV / cm. Thus, according to the present invention, a high-quality gate insulating film can be obtained.

It can also be applied to the production of a gate insulating film made of silicon oxynitride (SiO _x N _y ). For example, first, silicon source gas supply → purge → oxygen source gas supply → purge → silicon source gas supply → purge → nitrogen source gas supply → thin silicon oxynitridation by atomic layer growth method in which the purge cycle is repeated several times. Form a film of objects. Subsequently, the silicon source gas, the oxygen source gas, and the nitrogen source gas are supplied simultaneously, and the silicon oxynitride film is formed on the thin silicon oxynitride film to a desired thickness.

Further, the present invention is not limited to an insulating film made of silicon, but alumina (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ), zirconium dioxide (ZrO ₂ ), hafnium dioxide (HfO ₂ ), lanthanum dioxide (LaO ₂ ). Or oxides of binary alloys such as HfSiO ₂ , HfAlO ₂ , ZrSiO ₂ , aluminum nitride (AlN), titanium nitride (TiN), zirconium nitride (ZrN), hafnium nitride (HfN), lanthanum nitride (LaN), Alternatively, the present invention can be applied to the production of a gate insulating film made of a binary alloy nitride or the like.

  The case of hafnium oxide will be described. First, the substrate to be processed is fixed inside a predetermined reaction vessel, the reaction vessel is evacuated to a pressure of about 4 Pa by a predetermined exhaust mechanism, and then the substrate temperature is set to 350 ° C. In this state, a hafnium source gas made of tetrakisdiethylaminohafnium (TDEAH) is introduced into the reaction vessel, and the hafnium source gas is supplied onto the substrate. In the state where the hafnium source gas is introduced, the internal pressure of the reaction vessel is set to about 66 Pa, and the time during which the hafnium source gas is supplied onto the substrate is set to about 30 seconds. As a result, a TDEAH molecular layer (adsorption layer) is formed on the surface of the gate insulating film of the substrate.

Next, the introduction of the hafnium source gas into the reaction vessel is stopped, an inert gas such as nitrogen gas is introduced into the reaction vessel, and the inside of the reaction vessel is purged with the inert gas. Removed. The purge is performed for about 30 seconds.
Next, an oxygen source gas composed of H ₂ O is introduced into the reaction vessel so that the oxygen source gas is supplied to the surface of the TDEAH molecular layer. In a state where the oxygen source gas is introduced, the internal pressure of the reaction vessel is set to about 2700 Pa, and the oxygen source gas is supplied for about 30 seconds. As a result, the TDEAH molecular layer is oxidized, and a hafnium oxide layer corresponding to one atomic layer of hafnium is formed on the substrate. The substrate temperature is maintained at 350 ° C.

Next, the inside of the reaction vessel is purged with an inert gas so that the inert gas is supplied onto the hafnium oxide, and the oxygen source gas is removed from the hafnium oxide layer. The purge is performed for about 30 seconds.
Next, a hafnium source gas is supplied onto the already formed one atomic layer of hafnium oxide layer, and a new TDEAH molecular layer is formed on the hafnium oxide layer.
Next, an oxygen source gas is introduced into the reaction vessel so that the oxygen source gas is supplied to the surface of the TDEAH molecular layer. The oxygen source gas is supplied for about 30 seconds.

As a result, the TDEAH molecular layer adsorbed on the surface of the hafnium oxide layer is oxidized, and a hafnium oxide layer corresponding to a hafnium diatomic layer is formed.
The hafnium source gas supply → purge → oxygen source gas supply → purge cycle described above is repeated 100 times, for example, to form a hafnium oxide film having a desired film thickness.

  Next, the hafnium source gas and the oxygen source gas are supplied to the inside of the reaction vessel, and the mixed gas is supplied onto the hafnium oxide film, and hafnium oxide is formed in a desired film thickness. accumulate. For example, a hafnium source gas is supplied with a carrier gas with a flow rate of 20 sccm, an oxygen source gas is supplied with a carrier gas with a flow rate of 100 sccm, the pressure in the reaction vessel is about 135 Pa, and the substrate temperature is about 500 ° C. Perform for about 5 minutes.

As a result, a state is obtained in which an insulating layer made of hafnium oxide (HfO ₂ ) having a thickness of about 33 nm is formed on the surface of the gate insulating film formed on the substrate.
When an insulating layer made of hafnium oxide formed as described above is used as a gate insulating film, the electrical characteristics are as follows: interface state density is 1 × 10 ¹¹ cm ⁻² eV ⁻¹ , and fixed charge density is 2 × 10. ¹¹ cm ⁻² and the withstand voltage is 3 MV / cm. Thus, according to the present invention, a high-quality gate insulating film can be obtained.

Next, the case of zirconium dioxide will be described. First, the substrate to be processed is fixed inside a predetermined reaction vessel, the inside of the reaction vessel is evacuated to a pressure of about 4 Pa by a predetermined exhaust mechanism, and then the substrate temperature is set to 350 ° C. A zirconium source gas made of tetratertiary butoxyzirconium (ZTB: Zr (t-OC ₄ H ₉ ) ₄ ) is introduced, and the zirconium source gas is supplied onto the substrate. In the state where the zirconium source gas is introduced, the internal pressure of the reaction vessel is set to about 50 Pa, and the time during which the zirconium source gas is supplied onto the substrate is set to about 100 seconds. As a result, a ZTB molecular layer (adsorption layer) is formed on the surface of the gate insulating film of the substrate.

Next, the introduction of the zirconium raw material gas into the reaction vessel is stopped, an inert gas such as nitrogen gas is introduced into the reaction vessel, the inside of the reaction vessel is purged with the inert gas, and excess gas is removed from the reaction vessel. Removed. The purge is performed for about 30 seconds.
Next, an oxygen source gas composed of H ₂ O is introduced into the reaction vessel so that the oxygen source gas is supplied to the surface of the ZTB molecular layer. In the state where the oxygen source gas is introduced, the internal pressure of the reaction vessel is set to about 600 to 700 Pa, and the oxygen source gas is supplied for about 30 seconds. As a result, the ZTB molecular layer is oxidized, and a zirconium oxide layer corresponding to one atomic layer of zirconium is formed on the substrate. The substrate temperature is maintained at 350 ° C.

Next, the inside of the reaction vessel is purged with an inert gas so that the inert gas is supplied onto the zirconium oxide, and the oxygen source gas is removed from above the zirconium oxide layer. The purge is performed for about 30 seconds.
Next, a zirconium raw material gas is supplied onto the already formed zirconium oxide layer for one atomic layer, and a new ZTB molecular layer is formed on the zirconium oxide layer.
Next, an oxygen source gas is introduced into the reaction vessel so that the oxygen source gas is supplied to the surface of the ZTB molecular layer. The oxygen source gas is supplied for about 30 seconds.

As a result, the ZTB molecular layer adsorbed on the surface of the zirconium oxide layer is oxidized, and a zirconium oxide layer corresponding to two atomic layers of zirconium is formed.
The zirconium dioxide film having a desired film thickness is formed by repeating, for example, 30 cycles of the zirconium raw material gas supply → purge → oxygen raw material gas supply → purge described above.

  Next, the zirconium raw material gas and the oxygen raw material gas are supplied to the inside of the reaction vessel, and a mixed gas in which these are mixed is supplied onto the zirconium oxide film, and zirconium oxide is formed in a desired film thickness. accumulate. For example, a zirconium source gas is supplied with a carrier gas having a flow rate of 15 sccm, an oxygen source gas is supplied with a carrier gas having a flow rate of 60 sccm, the pressure in the reaction vessel is about 30 Pa, and the substrate temperature is about 400 ° C. Perform for about 10 minutes.

As a result, it is possible to obtain a state in which an insulating layer made of zirconium oxide (ZrO ₂ ) having a thickness of about 36 nm is formed on the gate insulating film forming surface on the substrate.
When an insulating layer made of zirconium dioxide formed as described above is used as a gate insulating film, the electrical properties are as follows: interface state density is 2 × 10 ¹¹ cm ⁻² eV ⁻¹ , and fixed charge density is 5 × 10. ¹¹ cm ⁻² and the withstand voltage is 4 MV / cm. Thus, according to the present invention, a high-quality gate insulating film can be obtained.

Next, the case of HfSiO ₂ which is an oxide of a binary alloy will be described. First, the substrate to be processed is fixed inside a predetermined reaction vessel, the inside of the reaction vessel is evacuated to a pressure of about 4 Pa by a predetermined exhaust mechanism, and then the substrate temperature is set to 350 ° C. A hafnium source gas made of tetrakisdiethylaminohafnium (TDEAH) is introduced, and the hafnium source gas is supplied onto the substrate. In the state where the hafnium source gas is introduced, the internal pressure of the reaction vessel is set to about 66 Pa, and the time during which the hafnium source gas is supplied onto the substrate is set to about 30 seconds. As a result, a TDEAH molecular layer (adsorption layer) is formed on the surface of the gate insulating film of the substrate.

Next, the introduction of the hafnium source gas into the reaction vessel is stopped, an inert gas such as nitrogen gas is introduced into the reaction vessel, and the inside of the reaction vessel is purged with the inert gas. Removed. The purge is performed for about 30 seconds.
Next, an oxygen source gas composed of H ₂ O is introduced into the reaction vessel so that the oxygen source gas is supplied to the surface of the TDEAH molecular layer. In a state where the oxygen source gas is introduced, the internal pressure of the reaction vessel is set to about 2700 Pa, and the oxygen source gas is supplied for about 30 seconds. As a result, the TDEAH molecular layer is oxidized, and a hafnium oxide layer corresponding to one atomic layer of hafnium is formed on the substrate. The substrate temperature is maintained at 350 ° C.

Next, the inside of the reaction vessel is purged with an inert gas so that the inert gas is supplied onto the hafnium oxide, and the oxygen source gas is removed from the hafnium oxide layer. The purge is performed for about 30 seconds.
Next, a silicon source gas composed of trisdimethylaminosilane (TDMAS: HSi [N (CH ₃ ) ₂ ] ₃ ) is introduced onto the already formed hafnium oxide layer for one atomic layer, and the above-mentioned material is introduced onto the substrate. The silicon source gas is supplied. In a state where the silicon source gas is introduced, the internal pressure of the reaction vessel is set to about 120 to 130 Pa, and the time during which the silicon source gas is supplied onto the substrate is set to about 30 seconds. As a result, a hafnium silicate molecular layer (adsorption layer) is formed on the surface of the gate insulating film of the substrate.

Next, the introduction of the silicon source gas into the reaction vessel is stopped, the inert gas is introduced into the reaction vessel, the inside of the reaction vessel is purged with the inert gas, and the excess gas is removed from the reaction vessel. And The purge is performed for about 30 seconds.
Next, an oxygen source gas composed of H ₂ O is introduced into the reaction vessel so that the oxygen source gas is supplied to the surface of the hafnium silicate molecular layer. In a state where the oxygen source gas is introduced, the internal pressure of the reaction vessel is set to about 2700 Pa, and the oxygen source gas is supplied for about 30 seconds. As a result, the hafnium silicate molecular layer is oxidized, and the HfSiO ₂ layer for one molecular layer is formed on the substrate. The substrate temperature is maintained at 350 ° C.

The above-described hafnium source gas supply → purge → oxygen source gas supply → purge → silicon source gas supply → purge → oxygen source gas supply → purge cycle is repeated 50 times, for example. It is assumed that the HfSiO ₂ film is formed.

Next, the hafnium source gas, the silicon source gas, and the oxygen source gas are supplied to the inside of the reaction vessel, and the mixed gas is supplied onto the hafnium oxide film to obtain a desired film thickness. HfSiO ₂ is deposited on the substrate. For example, a hafnium source gas is supplied with a carrier gas with a flow rate of 20 sccm, a silicon source gas is supplied with a carrier gas with a flow rate of 10 sccm, an oxygen source gas is supplied with a carrier gas with a flow rate of 100 sccm, and the pressure in the reaction vessel is And about 135 Pa, and the substrate temperature is about 500 ° C. for about 5 minutes.

As a result, a state is obtained in which an insulating layer made of HfSiO ₂ having a thickness of about 35 nm is formed on the gate insulating film forming surface on the substrate.
When an insulating layer made of HfSiO ₂ formed as described above is used as a gate insulating film, the electrical characteristics are as follows: interface state density is 1 × 10 ¹¹ cm ⁻² eV ⁻¹ , and fixed charge density is 4 × 10. ¹¹ cm ⁻² and the withstand voltage is 5 MV / cm. Thus, according to the present invention, a high-quality gate insulating film can be obtained.

Further, in the manufacturing process described above, an aluminum source gas made of trimethylaluminum (TMA: Al (CH ₃ ) ₃ ) is used in place of the TDMAS which is a silicon source gas, so that gate insulation made of HfAlO _{2 can} be obtained by the same process. A film can be formed.

It is process drawing for demonstrating the preparation methods of the gate insulating film in embodiment of this invention. It is process drawing for demonstrating the preparation methods of the gate insulating film in embodiment of this invention. It is a block diagram which shows roughly the structural example of the processing apparatus for producing the gate insulating film of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Glass substrate, 102 ... Source electrode, 103 ... Drain electrode, 104 ... Polysilicon layer (low-temperature polysilicon layer), 105 ... Insulating layer, 106 ... Gate electrode, 107 ... Gate insulating film, 108 ... Source, 109 ... Drain , 121 ... silicon source gas, 122 ... oxygen source gas, 123 ... mixed gas, 151 ... SiCl ₄ molecules layer (adsorption layer), 152 ... silicon oxide layer, 153 ... SiCl ₄ molecules layer, 154 ... silicon oxide layer.

Claims (10)

A first source gas composed of a compound of the first substance is supplied onto a substrate disposed inside the reaction vessel and heated to a predetermined temperature, and the compound of the first substance is adsorbed on the substrate. A first step in which an adsorption layer is formed;
A second step of removing the first source gas from the inside of the reaction vessel after stopping the supply of the first source gas;
Supplying a second source gas containing a second substance made of at least one of oxygen and nitrogen to the surface of the adsorption layer to form a first insulation composed of a compound of the first substance and the second substance of the adsorption layer; A third step in which a layer is formed on the substrate;
The first source gas and the second source gas are supplied to the surface of the first insulating layer, and the second insulating layer made of a compound of the first material and the second material is the surface of the first insulating layer. And at least a fourth step of forming a state formed in
A method for manufacturing a gate insulating film, comprising: forming a gate insulating film including the first insulating layer and the second insulating layer on the substrate. In the manufacturing method of the gate insulating film of Claim 1,
A plurality of first insulating layers are formed by repeating a series of cycles including the first step, the second step, and the third step;
After forming a plurality of first insulating layers, the second insulating layer is formed. A method for manufacturing a gate insulating film. In the manufacturing method of the gate insulating film of Claim 1 or 2,
The method for manufacturing a gate insulating film, wherein the first material is silicon. In the manufacturing method of the gate insulating film of Claim 1 or 2,
The method of manufacturing a gate insulating film, wherein the first material is hafnium. In the manufacturing method of the gate insulating film of Claim 1 or 2,
A method for manufacturing a gate insulating film, wherein the first material is zirconium. A first source gas composed of a compound of the first substance is supplied onto a substrate disposed inside the reaction vessel and heated to a predetermined temperature, and the compound of the first substance is adsorbed on the substrate. A first step in which an adsorption layer is formed;
A second step of removing the first source gas from the inside of the reaction vessel after stopping the supply of the first source gas;
A first compound comprising a compound of the first substance and the second substance of the adsorption layer by supplying a second source gas containing a second substance of at least one of oxygen and nitrogen to the surface of the adsorption layer; A third step in which a layer is formed on the substrate;
A fourth step of removing the second source gas from the inside of the reaction vessel after stopping the supply of the second source gas;
A third source gas composed of a compound of a third material is supplied to the surface of the first compound layer, and a second compound layer composed of the compound of the first material, the second material, and the third material is formed on the substrate. A fifth step of forming a state above,
A sixth step of removing the third source gas from the inside of the reaction vessel after stopping the supply of the third source gas;
A state in which a first insulating layer made of a compound of the first material, the second material, and the third material is formed on the substrate by supplying the second source gas to the surface of the second compound layer And the seventh step,
The first source gas, the second source gas, and the third source gas are supplied to the surface of the first insulating layer, and are formed of a compound of the first material, the second material, and the third material. And at least an eighth step in which two insulating layers are formed on the surface of the first insulating layer,
A method for manufacturing a gate insulating film, comprising: forming a gate insulating film including the first insulating layer and the second insulating layer on the substrate. In the manufacturing method of the gate insulating film of Claim 6,
A plurality of first insulating layers are formed by repeating a series of cycles including the first step, the second step, and the third step;
After forming a plurality of first insulating layers, the second insulating layer is formed. A method for manufacturing a gate insulating film. In the manufacturing method of the gate insulating film of Claim 6 or 7,
The method of manufacturing a gate insulating film, wherein the first material is hafnium and the second material is silicon. In the manufacturing method of the gate insulating film of Claim 6 or 7,
The method of manufacturing a gate insulating film, wherein the first material is hafnium and the second material is aluminum. In the manufacturing method of the gate insulating film of Claim 6 or 7,
The method of manufacturing a gate insulating film, wherein the first material is zirconium and the second material is silicon.

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