JP2004087733A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently form a high dielectric material film on the surface of a silicon substrate in order to minimize the thickness in terms of oxide film obtained. <P>SOLUTION: After the process to remove an oxide film from the surface of the silicon substrate, the surface of silicon substrate from which the oxide film is removed is processed with the aqueous solution of nitric acid. After formation of a chemical oxide film, a high dielectric material film is formed with the CVD method. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a semiconductor device, and more particularly to a method for manufacturing a semiconductor device having a high dielectric film.
[0002]
2. Description of the Related Art In a high-speed semiconductor integrated circuit device such as a CMOS-LSI that requires an ultra-high-speed operation, a field-effect transistor (MOSFET or MISFET) constituting the semiconductor integrated circuit device is required to have a very short gate length. For this reason, great efforts have been made to miniaturize transistors.
[0003]
In such a highly miniaturized field-effect transistor, the thickness of the gate insulating film is also limited due to the requirement of the scaling law. It is required to reduce it to about 2.5 nm or less.
[0004]
Conventionally, a silicon oxide film generally having good leakage current characteristics and a low interface state density has been used as a gate insulating film. However, in a conventional gate insulating film made of a silicon oxide film, the tunnel current increases directly with a decrease in the physical thickness of the gate insulating film. If the value further decreases than the value of, an increase in the gate leak current due to the tunnel current becomes a serious problem. When the gate leak current increases, for example, a substantial leak current occurs when the gate is turned off, which causes a problem that a circuit of the semiconductor device does not operate normally or an increase in power consumption of the semiconductor device.
[0005]
In order to solve the above problem, HfO having a high dielectric constant is used as a material of the gate insulating film. ₂ And ZrO ₂ Metal oxide such as ZrSiO ₄ And HfSiO ₄ The use of a so-called high dielectric film such as a metal silicate has been studied. By using a high dielectric film, it is possible to reduce the electrical film thickness of the gate insulating film while maintaining the physical film thickness at a relatively large value that does not substantially cause carrier tunneling. . When a high dielectric film is applied to a capacitor, a large capacitance can be realized. Therefore, application to a memory cell capacitor in a miniaturized DRAM or the like is being studied.
[0006]
[Prior art]
In general, in a high-speed semiconductor device having a high-dielectric gate insulating film, the high-dielectric film forming the gate insulating film minimizes damage to a base forming the channel layer and reduces the process temperature as much as possible. Therefore, metal compounds such as metal chlorides and H ₂ It is generally formed by a CVD method using a reaction with an oxidizing agent such as O.
[0007]
By the way, when such a high dielectric film is formed on the surface of a silicon substrate by the CVD method, a pretreatment for removing a natural oxide film on the surface of the substrate is required. Such pre-processing is generally performed using HF.
[0008]
When the surface of the silicon substrate is subjected to HF treatment, water (H ₂ A step of rinsing using O) to remove F ions from the substrate surface is necessary. ₂ As a result of rinsing with O, the surface of the silicon substrate from which the natural oxide film has been removed and the Si atomic surface has been exposed is in a state in which dangling bonds are terminated with hydrogen as shown in FIG. However, in FIG. 1, the silicon substrate is indicated by reference numeral 11.
[0009]
The state shown in FIG. 1 in which the Si atomic plane on the surface of the silicon substrate 11 is terminated with hydrogen is very stable, and even when a gaseous source material such as a metal chloride is supplied by the CVD method, the gaseous source material remains on the substrate surface. Are not trapped by these atoms, causing island-like growth or a continuous film not being formed on the substrate surface.
[0010]
In particular, when the high dielectric film is a gate insulating film, such island-like growth causes a change in film thickness, and has a fatal effect on the operation characteristics of the semiconductor device.
[0011]
For this reason, conventionally, when performing such a pretreatment for removing a natural oxide film by using HF, a so-called SC2 cleaning using a mixed aqueous solution of hydrochloric acid and hydrogen peroxide is subsequently performed to terminate the silicon substrate surface with OH groups. Has been done.
[0012]
[Problems to be solved by the invention]
FIG. 2 shows SC2 cleaning of the surface of the silicon substrate 11.
[0013]
Referring to FIG. 2, the surface of the silicon substrate 11 is initially terminated with hydrogen shown in FIG. 1, but as a result of SC2 cleaning, a chemical oxide film 12 having a thickness of about 1 nm is formed. The surface of the chemical oxide film 12 is terminated not by hydrogen but by an OH group.
[0014]
Therefore, the silicon substrate on which such a chemical oxide film 12 is formed is kept at a substrate temperature of, for example, 300 ° C., and HfCl 2 is formed on the silicon substrate as shown in FIG. ₄ When a process of forming a high dielectric film by supplying molecules as a gaseous source material is performed, hydrogen in OH groups terminating the surface of the chemical oxide film 12 becomes HfCl 2 as shown in FIG. ₄ Reacts with chlorine in the molecule and is removed out of the system in the form of HCl. As a result, the chemical oxide film 12 has HfO ₂ Cl ₂ The intermediate structure joins.
[0015]
Further, as shown in FIG. ₂ HfO in which O molecules are adsorbed on the chemical oxide film 12 ₂ Cl ₂ Reacts with chlorine in the intermediate structure, and the intermediate structure is HfO ₂ OH ₂ Is further converted to HfO on the chemical oxide film 12. ₂ The film 13 grows. At this time, the HfO formed ₂ Since the surface of the film 13 is terminated with an OH group, HfO ₂ Growth of the film 13 can be continued as needed.
[0016]
On the silicon substrate on which the chemical oxide film 12 has been formed as described above, HfO ₂ When a high dielectric film 13 is formed and a gate electrode 14 is further formed as shown in FIG. 6, a capacitor C having a large dielectric constant due to the high dielectric film 13 as shown in FIG. ₁ The capacitor C formed by the chemical oxide film 12 having a low dielectric constant ₂ Are connected in series, and the effect of using the high-dielectric film 13 is the effect of the capacitor C having a small capacitance due to the chemical oxide film 12. ₂ Will be offset by As a result, in the gate insulating film having such a structure, the equivalent oxide film thickness increases, and it becomes difficult to reduce the effective film thickness of the gate insulating film by the scaling law.
[0017]
Accordingly, it is a general object of the present invention to provide a new and useful semiconductor device which solves the above-mentioned problems, and a manufacturing process thereof.
[0018]
A more specific object of the present invention is to provide, in a semiconductor device having a high dielectric gate insulating film or a high dielectric capacitor, an oxide film equivalent of the entire insulating film including an oxide film or a chemical oxide film accompanying the high dielectric film. An object of the present invention is to provide a manufacturing method capable of minimizing a film thickness.
[0019]
[Means for Solving the Problems]
The present invention solves the above problems by removing an oxide film from a silicon layer surface, treating the silicon layer surface from which the oxide film has been removed with a nitric acid aqueous solution to form a chemical oxide film, The problem is solved by a method for manufacturing a semiconductor device, comprising: a step of forming a high dielectric film thereon; and a step of forming an electrode on the high dielectric film.
[0020]
According to the present invention, hydrogen that forms a stable bond by bonding to the surface of the silicon layer as the oxide film is removed from the surface of the silicon layer is removed by performing the nitric acid aqueous solution treatment, and OH that easily reacts is removed. A very thin chemical oxide film having groups on the surface is formed. Such a chemical oxide film has a somewhat higher density than a chemical oxide film obtained when a silicon substrate surface is treated with a mixed aqueous solution of hydrochloric acid and hydrogen peroxide, and as a result, a desired high dielectric film is formed on the chemical oxide film. Can be formed quickly without causing island growth or the like, and in such a manner that the equivalent oxide film thickness of the entire chemical oxide film and high dielectric film is minimized.
[0021]
The present invention also solves the above problems, a step of removing an oxide film from a silicon layer surface, a step of removing hydrogen bonded to the silicon layer surface from the silicon layer surface from which the oxide film has been removed, The problem is solved by a method for manufacturing a semiconductor device, comprising a step of forming a high dielectric film on the surface of a silicon layer from which hydrogen has been removed, and a step of forming an electrode on the high dielectric film.
[0022]
According to the present invention, the hydrogen that forms a stable bond with the surface of the silicon layer is removed as the oxide film is removed from the surface of the silicon layer. Can be formed quickly without causing island-like growth while minimizing the formation of a low dielectric constant oxide film between the high dielectric film and the base film.
[0023]
The present invention also provides the above-mentioned objects, wherein a step of forming an insulating film on a silicon layer surface, a step of performing a plasma treatment on the insulating film surface, and a step of removing atoms bonded to the insulating film surface, and the step of performing the plasma treatment The problem is solved by a method for manufacturing a semiconductor device, comprising: a step of forming a high dielectric film on a surface of an insulating film; and a step of forming an electrode on the high dielectric film.
[0024]
According to the present invention, the surface of an oxide film, an oxynitride film, or a nitride film formed on the surface of a silicon layer is subjected to plasma treatment to remove atoms bonded to the film surface, thereby obtaining a desired high dielectric substance. A film can be formed quickly on the surface of the insulating film without causing island growth or the like while minimizing the increase in the thickness of the insulating film.
[0025]
According to the present invention, a semiconductor device having a high dielectric gate insulating film or a semiconductor device having a high dielectric capacitor can be easily formed.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
[First embodiment]
FIGS. 8A to 8C show a substrate processing step and a high dielectric film forming step according to the first embodiment of the present invention. However, in the figure, the parts described above are denoted by the same reference numerals, and description thereof will be omitted.
[0027]
Referring to FIG. 8A, first, in a silicon substrate 11 having a (100) plane orientation, a native oxide film on the substrate is first removed by HF treatment as in FIG. ₂ By rinsing with O, F ions remaining on the substrate surface are removed. As a result, a state in which hydrogen terminates dangling bonds on the surface of the silicon substrate appears. As described above, this state is stable, so that it is difficult to form a film on the structure of FIG.
[0028]
Therefore, in this embodiment, in the step of FIG. 8B, the structure of FIG. ₃ ) Aqueous solution, eg 61 & concentration HNO ₃ It is immersed in an aqueous solution for about 5 minutes, and as a result, a chemical oxide film 22 is formed on the surface of the silicon substrate 11 to a thickness of about 1 to 1.2 nm. The density of the chemical oxide film 22 formed as described above measured by GIXR (grating incision X-ray reflectometry) is the density (2.07 g / cm) of the chemical oxide film 12 formed by the SC2 cleaning described above. ³ 2.16 g / cm ³ (Sugita Y., et al., Jpn. J. Appl. Phys. Vol. 35, (1996), pp. 5437-5443). On the surface of the chemical oxide film 22 thus formed, the dangling bonds are terminated by OH groups, as in the case of the chemical oxide film 12.
[0029]
Further, in the step of FIG. 8C, the same CVD step as that described above with reference to FIGS. ₂ The film 13 is formed to a thickness of about 3 nm.
[0030]
In the present embodiment, the HfO thus formed in the step of FIG. ₂ A Pt electrode 24 was further formed on the film 13 to form a MIS capacitor.
[0031]
FIG. 9 shows the results of measuring the leakage current density and the equivalent oxide film thickness of the capacitor insulating film for the MIS capacitor thus formed. However, the capacitor insulating film is formed by the chemical oxide film 22 and HfO ₂ It has a laminated structure with the film 13. FIG. 9 further shows the same MIS capacitor as a capacitor insulating film, and a chemical oxide film 12 formed by SC2 cleaning using hydrochloric acid and hydrogen peroxide as described above and HfO. ₂ The result when the laminated structure with the film 13 is used is shown. In this embodiment, the chemical oxide film 22 has a value of 1 to 1.2 nm as described above, whereas the chemical oxide film 12 has a thickness of 0.7 to 0.9 nm. .
[0032]
Referring to FIG. 9, in both the present example and the case where SC2 cleaning was performed, the equivalent oxide film thickness of the capacitor insulating film was about 1.5 nm, which was smaller than the value of the physical film thickness (about 4 nm). Although it is greatly reduced, especially when the chemical oxide film 22 formed by the pretreatment in nitric acid shown in FIG. 8B is used, the equivalent oxide film thickness is further reduced, and 1.3 to 1. It can be seen that a value of about 4 nm has been realized. Further, in the case of the present embodiment, it can be seen that the leak current density is reduced by about one digit as compared with the case where the SC2 cleaning is performed.
[0033]
In FIG. 9, HfO ₂ Since the thickness of the film 13 is about 3 nm in any of the experiments, the difference shown in FIG. 9 is considered to be mainly due to the difference between the chemical oxide films 12 and 22. Since the thickness of the chemical oxide film 22 is 1 to 1.2 nm as described above and is larger than the thickness of the chemical oxide film 12, the equivalent oxide film thickness is reduced by using the chemical oxide film 22. Although the result of FIG. 9 is unexpected, the density of the chemical oxide film 22 is 2.16 nm, which is slightly larger than the density of the chemical oxide film 12. This is interpreted as being related to the difference in film thickness. In this embodiment, since the surface of the chemical oxide film 22 is terminated with an OH group, the deposition immediately occurs when the CVD process of the high dielectric film shown in FIGS. Since the surface of the chemical oxide film is terminated with hydrogen, the actual start of deposition of the high dielectric film is slightly delayed. Therefore, the problem of increasing the thickness of the chemical oxide film 22 before the start of the deposition of the high dielectric film in the initial stage of the CVD process is minimized. Can be
[0034]
In any case, the result of FIG. 9 shows that the native oxide film is removed by HF treatment and then the treatment in nitric acid reduces the equivalent oxide film thickness of the high dielectric film including the formed chemical oxide film. And at the same time, the leakage current density can be reduced.
[0035]
In this embodiment, the high dielectric film is HfO ₂ Not limited to a film, ₂ Film and TiO ₂ Metal oxide film such as a film, or HfSiO ₄ Film and ZrSiO ₄ It may be a silicate film such as a film.
[Second embodiment]
FIGS. 10A to 10C show a substrate processing step and a high dielectric film forming step according to a second embodiment of the present invention. However, in the figure, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof will be omitted.
[0036]
Referring to FIG. 10A, the natural oxide film is removed from the Si substrate 11 by the HF treatment, and the subsequent H ₂ The Si atomic plane exposed by the O-rinsing step is terminated by hydrogen.
[0037]
Next, in the process of FIG. 10B, the structure of FIG. ⁴ The substrate is kept in a reduced-pressure inert atmosphere of Pa or less and treated at a temperature of 700 ° C. or more for 1 minute to remove hydrogen that has terminated the substrate surface. As a result, in the step of FIG. 10B, a very active Si atomic plane is exposed on the substrate surface.
[0038]
Next, in the step of FIG. 10C, the CVD step described above with reference to FIGS. 3 to 5 is directly performed on the structure of FIG. 10B, and HfO is directly formed on the active Si atomic plane. ₂ A high dielectric film 13 is formed. However, even in such a process, an extremely thin oxide film 12a having a thickness of less than 1 nm is generally formed at the interface between the Si substrate 11 and the high dielectric film 13. As a result of the formation of the oxide film 12a, diffusion of the metal element such as Hf in the high dielectric film 13 into the silicon substrate 11 is suppressed.
[0039]
According to this embodiment, the surface of the silicon substrate 11 is activated by the process of FIG. 10B, and the high dielectric film 13 is uniformly and quickly formed. That is, in the step of FIG. ₂ A gaseous source material containing O is supplied. However, since the surface of the silicon substrate 11 is very active, HfO ₂ Is immediately started, and the surface of the silicon substrate 11 becomes HfO ₂ Before deposition of H ₂ It is considered that the problem of being oxidized by O to form a low dielectric constant oxide film or increase the thickness of such an oxide film is avoided.
[0040]
As a result, the thickness of the oxide film 12a formed at the interface between the silicon substrate 11 and the high dielectric film 13 is minimized. Since the oxide film 12a thus formed has a thickness of 1 nm or less, the equivalent oxide film thickness of the high dielectric film 13 including the oxide film 12a is further reduced, and the gate length of the high-speed semiconductor device is reduced. Contribute to reduction.
[0041]
In this embodiment, the high dielectric film is HfO ₂ Not limited to a film, ₂ Film and TiO ₂ Metal oxide film such as a film, or HfSiO ₄ Film and ZrSiO ₄ It may be a silicate film such as a film.
[Third embodiment]
FIGS. 11A to 11D show a substrate processing step and a high dielectric film forming step according to a third embodiment of the present invention.
[0042]
Referring to FIG. 11A, in this embodiment, an insulating film 32 such as an oxide film, an oxynitride film, or a nitride film is thermally oxidized on the silicon substrate 11 of FIG. 11A in the process of FIG. The insulating film 32 is formed by a treatment or a plasma oxidation treatment, a nitridation treatment, or an oxynitridation treatment, and the surface of the insulating film 32 is irradiated with plasma in the step of FIG. For example, a rare gas plasma such as Ar or Ne is formed under a pressure of 133 Pa with a plasma power of 200 W, and the surface of the insulating film 32 is treated with the plasma for a short time, for example, 60 seconds, so that the surface of the insulating film 32 is bonded to the insulating film surface. It is possible to remove the hydrogen or OH groups that have been used. As a result of such plasma treatment, in the step of FIG. 11C, hydrogen and OH groups terminating on the surface of the insulating film are released, and atoms constituting the uppermost surface of the insulating film are exposed.
[0043]
Therefore, in the present embodiment, in the step of FIG. 11D, the high dielectric film 13 is formed on the surface of the insulating film 32 by the same CVD process as described above with reference to FIGS.
[0044]
According to the present embodiment, even on a silicon substrate carrying an insulating film, by activating the surface of the insulating film, the high dielectric film can be efficiently formed without increasing the insulating film. Can be deposited on top. Further, by using an oxynitride film or a nitride film having a large relative dielectric constant as the insulating film, the equivalent oxide film thickness of the high dielectric film including the insulating film can be further reduced.
[0045]
In this embodiment, the high dielectric film is HfO ₂ Not limited to a film, ₂ Film and TiO ₂ Metal oxide film such as a film, or HfSiO ₄ Film and ZrSiO ₄ It may be a silicate film such as a film.
[Fourth embodiment]
FIGS. 12A to 13E show a method of manufacturing a semiconductor device according to a fourth embodiment of the present invention.
[0046]
Referring to FIG. 12A, an element region 41A is defined on a silicon substrate 41 by a field oxide film 42 forming an STI structure, and in the process of FIG. A high dielectric gate insulating film 43 is formed on the structure by the same steps as those shown in FIGS. 8A to 8C.
[0047]
That is, after the structure of FIG. 12A is subjected to HF treatment for a short time, it is rinsed with water to obtain a structure in which the surface of the silicon substrate 41 shown in FIG. 8A is terminated with hydrogen.
[0048]
Next, such a structure is called HNO ₃ A chemical oxide film whose surface is terminated with OH is formed on the surface of the silicon substrate 41 corresponding to the chemical oxide film 22 by immersion in an aqueous solution, and further on the chemical oxide film thus formed. HfO ₂ A high-dielectric film 43 is formed to a thickness of about 3 nm corresponding to the high-dielectric film 13. In FIG. 12B, only the high dielectric film 43 is shown, and the chemical oxide film thereunder is omitted.
[0049]
Next, in the step of FIG. 12C, a polysilicon film is deposited on the structure of FIG. 12B, and is patterned to form a gate electrode 44 on the high dielectric film 43. Further, in the step of FIG. 12C, ion implantation of an n-type or p-type impurity element is performed in the silicon substrate 41 using the gate electrode 44 as a self-alignment mask, and the silicon substrate 41 is formed on both sides of the gate electrode 44 in the silicon substrate 41. An n-type or p-type source extension or drain extension region 41a or 41b is formed.
[0050]
Further, in the step of FIG. 13D, SiO 2 is added on the structure of FIG. ₂ An insulating film such as a film is formed so as to cover the gate electrode 44 by a CVD method, and is further etched back to form a sidewall insulating film 44S on both side walls of the gate electrode 44. In addition, the high dielectric film 43 is also patterned in accordance with the etch back process, and a gate insulating film 43A is formed.
[0051]
Further, in the step of FIG. 13E, ion implantation of an n-type or p-type impurity element is performed in the silicon substrate 11 using the gate electrode 44 and the side wall insulating film 44S as a mask. The n + type or p + type source or drain diffusion regions 41c and 41d are formed outside the insulating film 44S.
[0052]
Although not shown, after the step of FIG. 13E, a low-resistance silicide layer is formed on the upper surface of the gate electrode 44 and the surfaces of the diffusion regions 41c and 41d by a salicide process.
[0053]
According to this embodiment, since the surface of the silicon substrate 41 is covered with a chemical oxide film having a thickness of about 1 nm terminated with OH groups in the step of FIG. And the uniform deposition can be achieved, the problem of the increase of the chemical oxide film due to the delay of the deposition is minimized, and as a result, the high dielectric gate insulating film 43A including the chemical oxide film can be formed. It is possible to reduce the equivalent oxide film thickness. Moreover, the chemical oxide film formed by the treatment in the nitric acid aqueous solution in this way has a slightly higher density than the chemical oxide film formed by the treatment in the hydrochloric acid and hydrogen peroxide water, and therefore passes through the gate insulating film 43A. It is possible to minimize the leak current and the equivalent oxide film thickness.
[0054]
In the step of FIG. 12B, the high dielectric film 43 can be formed by the steps of FIGS. In this case, the equivalent oxide film thickness of the high dielectric constant gate insulating film 43A is as shown in FIG. 9 because the thickness of the interface oxide film formed at the interface between the high dielectric film 43 and the silicon substrate 41 is very small. It is further reduced than described. Accordingly, it is possible to further reduce the gate length of the gate electrode 44 and to improve the operation speed of the semiconductor device while satisfying the scaling rule.
[0055]
In the step of FIG. 12B, the high dielectric film 43 is formed into an oxide film, a nitride film, or a laminated structure of an oxynitride film and a high dielectric film by the steps shown in FIGS. It is also possible to form. In particular, by forming the insulating film below the high dielectric film 43 with an oxynitride film or a nitride film, the relative dielectric constant of the insulating film is increased, and the high dielectric gate insulating film 43A including such an insulating film is formed. The equivalent oxide film thickness can be reduced. Accordingly, it is possible to further reduce the gate length of the gate electrode 44 and to improve the operation speed of the semiconductor device while satisfying the scaling rule.
[0056]
In this embodiment, the high dielectric film is HfO ₂ Not limited to a film, ₂ Film and TiO ₂ Metal oxide film such as a film, or HfSiO ₄ Film and ZrSiO ₄ It may be a silicate film such as a film.
[Fifth embodiment]
FIGS. 14A to 16G show a process of manufacturing a DRAM having a high dielectric capacitor according to a fifth embodiment of the present invention.
[0057]
Referring to FIG. 14A, an element region is formed on a silicon substrate 51 by an STI type field oxide film 52, and a gate electrode 54 is formed in the element region via a gate insulating film 53. In the silicon substrate 51, diffusion regions 51a and 51b having an LDD structure are formed on both sides of the gate electrode 54, and source regions 51c and 51d are formed outside thereof. In the step of FIG. 14A, the SiO.sub.2 is formed on the substrate 51 so as to cover the gate electrode. ₂ An interlayer insulating film 55 is formed. The gate electrode 54 includes a polysilicon gate electrode 54a and a silicide layer 54b thereon, and is covered with an insulating film 54A.
[0058]
Next, in the step of FIG. 14B, a contact hole is formed in the interlayer insulating film 55 so as to expose the drain region 51d, and the contact hole is filled with a conductor plug 56 such as W.
[0059]
Next, in the step of FIG. 14C, a conductive adhesion film 57 in which a Ti film and a TiN film are laminated on the interlayer insulating film 55 and a polysilicon film 58 are sequentially deposited. The surface is treated with nitric acid in the step of FIG. 8B to form a chemical oxide film having a thickness of about 1 nm. However, FIG. 14C does not show such a chemical oxide film.
[0060]
Alternatively, in the step of FIG. 14C, the step of FIG. 10B described above may be performed to remove atoms or groups bonded to the surface of the polysilicon film 58.
[0061]
Alternatively, in the step of FIG. 14C, the step of forming the insulating film 32 previously described with reference to FIG. 11B on the surface of the polysilicon film 58 is performed, and the surface of the formed insulating film 32 is Plasma processing may be performed by the process described in (C). However, the insulating film 32 is not shown in FIG.
[0062]
As a result of this processing, the surface of the polysilicon film 58 or the chemical oxide film or the insulating film formed on the polysilicon film is activated, and the surface of the activated polysilicon film is activated in the step of FIG. Then, HfO is formed by the CVD process described above with reference to FIGS. ₂ A high dielectric film 59 is formed.
[0063]
Further, in the step of FIG. 15E, a polysilicon film 60 is formed as an upper electrode on the structure of FIG. 15D, and by further patterning the film 57-60 in the step of FIG. A dielectric memory cell capacitor 61 is formed.
[0064]
Finally, in the step of FIG. 16 (G), another interlayer insulating film 62 is deposited on the structure of FIG. 15 (F) so as to cover the memory cell capacitor 61, and penetrates through the interlayer insulating films 62 and 55, and An opening exposing the source region 51c is formed, and a conductive plug 63 such as W is formed in the opening. Further, a bit line 64 is formed on the interlayer insulating film 62 corresponding to the conductive plug 63.
[0065]
In the present embodiment, as described above, in the step of FIG. 14C, the underlying surface of the high dielectric film 59 deposited in the step of FIG. 15D is activated. Deposition of the body film 59 occurs promptly, and the problem that the surface of the polysilicon film 58 is oxidized to form a low dielectric constant oxide film in the step of FIG. Also, depending on the activation process, an insulating film having a high relative dielectric constant such as SiN or SiON is formed on the surface of the polysilicon film 58, and a low dielectric constant film at the interface between the high dielectric film 59 and the polysilicon film 58 is formed. The problem of a decrease in the capacitance of the high dielectric capacitor 61 due to the formation is reduced.
[0066]
As described above, the present invention has been described with respect to the preferred embodiments. However, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the claims.
[0067]
(Supplementary Note 1) a step of removing an oxide film from the silicon layer surface;
Treating the silicon layer surface from which the oxide film has been removed with a nitric acid aqueous solution to form a chemical oxide film;
Forming a high dielectric film on the chemical oxide film;
Forming an electrode on the high dielectric film.
[0068]
(Supplementary note 2) The method for manufacturing a semiconductor device according to supplementary note 1, wherein the step of forming the chemical oxide film includes a step of immersing the silicon layer in an aqueous nitric acid solution.
[0069]
(Supplementary Note 3) a step of removing an oxide film from the surface of the silicon layer;
Removing hydrogen bonded to the silicon layer surface from the silicon layer surface from which the oxide film has been removed;
Forming a high dielectric film on the silicon layer surface from which the hydrogen has been removed,
Forming an electrode on the high dielectric film.
[0070]
(Supplementary Note 4) The method according to Supplementary Note 3, wherein the step of removing hydrogen includes a step of performing a heat treatment in a vacuum on the surface of the silicon layer from which the oxide film has been removed.
[0071]
(Supplementary note 5) The method of Supplementary note 3 or 4, wherein the step of forming the high dielectric film is performed directly on the surface of the silicon layer from which the hydrogen has been removed.
[0072]
(Supplementary Note 6) The step of removing the oxide film from the surface of the silicon layer includes the step of treating the surface of the silicon layer with HF and the step of treating the surface of the silicon layer treated with HF with H. ₂ 6. The method for manufacturing a semiconductor device according to any one of supplementary notes 1 to 5, further comprising a step of rinsing with O.
[0073]
(Supplementary Note 7) a step of forming an insulating film on the surface of the silicon layer;
Performing a plasma treatment on the insulating film surface to remove atoms bonded to the insulating film surface;
Forming a high dielectric film on the surface of the insulating film subjected to the plasma treatment;
Forming an electrode on the high dielectric film.
[0074]
(Supplementary Note 8) The method of Supplementary Note 7, wherein the insulating film is any one of an oxide film, an oxynitride film, and a nitride film.
[0075]
(Supplementary Note 9) The method for manufacturing a semiconductor device according to any one of Supplementary Notes 1 to 8, wherein the high dielectric film is any one of zirconium oxide, hafnium oxide, and titanium oxide. .
[0076]
(Supplementary Note 10) The step of forming the high dielectric film includes a step of supplying a metal chloride and an oxidizing agent constituting the high dielectric film to the surface of the chemical oxide film in the form of a vapor-phase raw material. 10. The method for manufacturing a semiconductor device according to any one of supplementary notes 1 to 9, wherein
[0077]
(Supplementary Note 11) The semiconductor device according to Supplementary Note 1, wherein the silicon layer is a silicon substrate, and the step of forming the electrode includes a step of forming a gate electrode on the high dielectric film. Production method.
[0078]
(Supplementary Note 12) The manufacturing of the semiconductor device according to Supplementary Note 3, wherein the step of forming the electrode includes a step of forming a gate electrode on the high dielectric film. Method.
[0079]
(Supplementary Note 13) The manufacturing of the semiconductor device according to Supplementary Note 7, wherein the step of forming the electrode includes a step of forming a gate electrode on the high dielectric film. Method.
[0080]
(Supplementary Note 14) The silicon layer is a silicon film forming a capacitor lower electrode, and the step of forming the electrode includes a step of forming a capacitor upper electrode on the high dielectric film. The manufacturing method of the semiconductor device described in the above.
[0081]
(Supplementary Note 15) The silicon layer is a silicon film constituting a capacitor lower electrode, and the step of forming the electrode includes a step of forming a capacitor upper electrode on the high dielectric film. The manufacturing method of the semiconductor device described in the above.
[0082]
(Supplementary Note 16) The silicon layer is a silicon film forming a capacitor lower electrode, and the step of forming the electrode includes a step of forming a capacitor upper electrode on the high dielectric film. The manufacturing method of the semiconductor device described in the above.
[0083]
【The invention's effect】
According to the present invention, a step of removing an oxide film from a silicon layer surface, a step of treating the silicon layer surface from which the oxide film has been removed with a nitric acid aqueous solution to form a chemical oxide film, Forming a high-dielectric film, and forming an electrode on the high-dielectric film by a method for manufacturing a semiconductor device, comprising: removing an oxide film from a silicon layer surface; Hydrogen bonded to the surface of the silicon layer and forming a stable bond is removed by performing the nitric acid aqueous solution treatment, and a very thin chemical oxide film having an easily reactive OH group on the surface is formed. Such a chemical oxide film has a somewhat higher density than a chemical oxide film formed when a silicon substrate surface is treated with hydrochloric acid and hydrogen peroxide. As a result, a desired high dielectric film is formed on the chemical oxide film. It is possible to form the film quickly without causing island growth or the like and to minimize the equivalent oxide film thickness of the chemical oxide film and the high dielectric film.
[0084]
Further, according to the present invention, a step of removing an oxide film from a silicon layer surface, a step of removing hydrogen bonded to the silicon layer surface from the silicon layer surface from which the oxide film has been removed, Forming a high dielectric film on the surface of the removed silicon layer; and forming an electrode on the high dielectric film. The hydrogen that forms a stable bond with the surface of the silicon layer is removed as the silicon is removed, so that a desired high dielectric film can be quickly formed on the surface of the silicon layer without causing island-like growth or the like. It is possible to form the low dielectric constant oxide film at the interface between the high dielectric film and the base while minimizing the formation.
[0085]
Further, according to the invention, a step of forming an insulating film on the surface of the silicon layer, a step of performing a plasma treatment on the surface of the insulating film to remove atoms bonded to the surface of the insulating film, Forming a high-dielectric film on the surface; and forming an electrode on the high-dielectric film. By subjecting the surface of the oxynitride film or the nitride film to plasma treatment and removing the atoms bonded to the film surface, the desired high dielectric film can be formed on the surface of the insulating film without causing island-like growth or the like. It is possible to quickly form the insulating film while minimizing the increase in the thickness of the insulating film.
[0086]
According to the present invention, a semiconductor device having a high dielectric gate insulating film or a semiconductor device having a high dielectric capacitor can be easily formed.
[Brief description of the drawings]
FIG. 1 is a view schematically showing a state of a substrate surface cleaned in a conventional substrate cleaning step using HF.
FIG. 2 is a diagram showing a state of a substrate surface cleaned in hydrochloric acid and a hydrogen peroxide solution following HF cleaning.
FIG. 3 shows HfO formed by CVD. ₂ FIG. 3 is a diagram (part 1) illustrating a film forming process.
FIG. 4 shows HfO formed by CVD. ₂ FIG. 9 is a diagram (part 2) illustrating a film forming process.
FIG. 5: HfO by CVD method ₂ FIG. 9 is a diagram (part 3) illustrating a process of forming a film.
FIG. 6 is a diagram showing a configuration of a conventional high dielectric gate insulating film.
7 is a diagram showing an equivalent circuit of the high dielectric gate insulating film of FIG.
FIGS. 8A to 8C are views showing a substrate processing step and a high dielectric film forming step according to the first embodiment of the present invention.
FIG. 9 is a diagram showing a leakage current characteristic of a high dielectric film formed according to the first embodiment of the present invention.
FIGS. 10A to 10C are views showing a substrate processing step and a high dielectric film forming step according to a second embodiment of the present invention.
FIGS. 11A to 11D are views showing a substrate processing step and a high dielectric film forming step according to a third embodiment of the present invention.
FIGS. 12A to 12C are diagrams (part 1) illustrating a process for manufacturing a semiconductor device according to a fourth embodiment of the present invention;
FIGS. 13D to 13C are views (Part 2) illustrating the steps of manufacturing the semiconductor device according to the fourth embodiment of the present invention;
FIGS. 14A to 14C are diagrams (part 1) illustrating a process for manufacturing a semiconductor device according to a fifth embodiment of the present invention;
FIGS. 15 (D) to (E) are diagrams (part 2) illustrating a process for manufacturing the semiconductor device according to the fifth embodiment of the present invention; FIGS.
FIG. 16G is a view (No. 3) showing a step of manufacturing the semiconductor device according to the fifth embodiment of the present invention;
[Explanation of symbols]
11,41,51 Silicon substrate
12,22 Chemical oxide film
12a oxide film
13 High dielectric film
14,24 electrodes
32 insulating film
41A element area
41a, 41b, 41c, 41d, 51a, 51b, 51c, 51d Diffusion regions 42, 52 Element isolation structure
43 High dielectric film
43A High dielectric gate insulating film
44,54 Gate electrode
44S Side wall insulation film
53 Gate insulating film
55, 62 interlayer insulating film
56, 63 conductor plug
57 conductive adhesion layer
58 polysilicon lower electrode
59 High dielectric capacitor insulating film
60 Polysilicon upper electrode
61 Capacitor
64 bit line

Claims (8)

Removing an oxide film from the silicon layer surface;
Treating the silicon layer surface from which the oxide film has been removed with a nitric acid aqueous solution to form a chemical oxide film;
Forming a high dielectric film on the chemical oxide film;
Forming an electrode on the high dielectric film. 2. The method according to claim 1, wherein the step of forming a chemical oxide film includes a step of immersing the silicon layer in a nitric acid aqueous solution. Removing an oxide film from the silicon layer surface;
Removing hydrogen bonded to the silicon layer surface from the silicon layer surface from which the oxide film has been removed;
Forming a high dielectric film on the silicon layer surface from which the hydrogen has been removed,
Forming an electrode on the high dielectric film. 4. The method according to claim 3, wherein the step of removing hydrogen includes a step of performing a heat treatment in a vacuum on a surface of the silicon layer from which the oxide film has been removed. 5. The method according to claim 3, wherein the step of forming the high dielectric film is performed directly on a surface of the silicon layer from which the hydrogen has been removed. The step of removing the oxide film from the surface of the silicon layer includes a step of treating the surface of the silicon layer with HF and a step of rinsing the surface of the silicon layer treated with the HF with H ₂ O. A method for manufacturing a semiconductor device according to claim 1. Forming an insulating film on the surface of the silicon layer;
Performing a plasma treatment on the insulating film surface to remove atoms bonded to the insulating film surface;
Forming a high dielectric film on the surface of the insulating film subjected to the plasma treatment;
Forming an electrode on the high dielectric film. Removing the oxide film from the silicon substrate surface;
Treating the silicon substrate surface from which the oxide film has been removed with a nitric acid aqueous solution to form a chemical oxide film;
Forming a high dielectric film on the chemical oxide film;
Forming a gate electrode on the high dielectric film. A method for manufacturing a semiconductor device having a high dielectric gate insulating film.

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