JP4451279B2 - Semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device using a high dielectric constant material.

In recent years, with the miniaturization of semiconductor devices, the gate length of a transistor is required to be 0.15 μm and the thickness of a gate insulating film is reduced to 2 nm or less when SiO ₂ is used. When the thickness of the insulating film is reduced to 2 nm or less, the tunnel current becomes so large that it cannot be ignored.

For this reason, it is considered to increase the physical film thickness while maintaining good dielectric properties by using an insulator material having a dielectric constant higher than that of SiO ₂ . For example, as described in Non-Patent Document 1, zirconium oxide or hafnium oxide is considered as a candidate for a high dielectric constant material that satisfies this requirement.

February 2000 issue of Nikkei Microdevices (pages 93-106)

  However, zirconium oxide and hafnium oxide are, for example, a lecture paper collection of “1999 IEEE (the Institute of Electrical and Electronics Engineers) International Electron Devices Meeting” (from page 99 to page 133, lecture number 6.1 and page 145 to page 148). As described in the lecture number 6.4), a reaction compound having a film thickness of about 1.5 nm to 2.5 nm is formed at the interface with the silicon substrate.

  This reactive compound is formed by diffusing oxygen from zirconium oxide or hafnium oxide and diffusing into the silicon substrate, which means that oxygen vacancies can be formed in zirconium oxide or hafnium oxide. This oxygen deficiency causes a decrease in characteristics of the semiconductor device, such as an increase in leakage current.

  In addition, oxygen may be diffused from the gate insulating film mainly composed of zirconium oxide or hafnium oxide to the gate electrode to cause oxygen vacancies, which also causes deterioration of the characteristics of the semiconductor device as described above. .

  The above-described problem of the reaction compound between the silicon substrate and zirconium oxide or the reaction compound between the silicon substrate and hafnium oxide also exists in a semiconductor device having a thin film transistor (referred to as a thin film transistor or TFT) structure.

  That is, the reaction compound of the polycrystalline silicon film and zirconium oxide, or the reaction compound of the polycrystalline silicon film and hafnium oxide was formed by diffusing oxygen from the zirconium oxide or hafnium oxide to the polycrystalline silicon film. It means that oxygen vacancies are formed in zirconium oxide or hafnium oxide.

  A first object of the present invention is to realize a highly reliable semiconductor device that can suppress deterioration of characteristics due to miniaturization.

  A second object of the present invention is to realize a semiconductor device that is miniaturized and has a high yield.

  A third object of the present invention is to realize a semiconductor device having a gate structure in which oxygen hardly diffuses at the interface between a silicon substrate and a gate insulating film.

  A fourth object of the present invention is to realize a semiconductor device having a thin film transistor structure in which oxygen hardly diffuses at the interface between a silicon film and a gate insulating film.

  The inventors of the present application have conducted extensive research to obtain a means for preventing oxygen from diffusing from an insulating film containing zirconium oxide or hafnium oxide as a main constituent element. It has been found that it is effective to use a silicon substrate having a (111) crystal face instead of a (001) crystal face.

  In addition, it has been found that it is effective to add hafnium or titanium to zirconium oxide, which is an insulating film, or to add titanium to hafnium oxide in order to further prevent oxygen diffusion.

  Furthermore, the inventors of the present application have found that an electrode material in which oxygen hardly diffuses at an interface with an insulating film containing zirconium oxide or hafnium oxide as a main constituent element is cobalt silicide and silicon. The (100) crystal plane and the (010) crystal plane are equivalent to the (001) crystal plane.

  Furthermore, it has been found that it is effective to use a polycrystalline silicon film having a (111) orientation for a semiconductor device having a thin film transistor structure.

In order to achieve the above object, the present invention is configured as follows.
(1) A silicon substrate, a gate insulating film made mainly of hafnium oxide formed in contact with one main surface of the silicon substrate, and a gate electrode film formed in contact with the gate insulating film in the semiconductor device having the above silicon one main surface of the substrate is a silicon (111) Ri parallel der crystal plane, the main constituent material of the gate electrode film is cobalt silicide or silicon, the gate insulating film is a titanium Contains at a concentration of 0.01 at.% To 15 at.% .

(2) Also, a silicon substrate, a gate insulating film made of hafnium oxide as a main constituent material in contact with one main surface of the silicon substrate, and a gate electrode film formed in contact with the gate insulating film A main surface of the silicon substrate is parallel to a (111) crystal plane of silicon, a main constituent material of the gate electrode film is cobalt silicide or silicon, and the gate insulating film is titanium. In a concentration of 0.03 at.% Or more and 10 at.% Or less.

(3) In the semiconductor device, a substrate, a first silicon film formed on one main surface side of the substrate, a gate insulating film formed in contact with the first silicon film, and the gate insulating film The first silicon film has a (111) orientation, the main constituent material of the gate insulating film is hafnium oxide, and the gate electrode film comprises: 111) a second silicon film having orientation, wherein the gate insulating film contains titanium at a concentration of 0.01 at.% To 15 at.%.

(4) In the semiconductor device, a substrate, a first silicon film formed on one main surface side of the substrate, a gate insulating film formed in contact with the first silicon film, and the gate insulating film The first silicon film has a (111) orientation, the main constituent material of the gate insulating film is hafnium oxide, and the gate electrode film comprises: 111) a second silicon film having orientation, wherein the gate insulating film contains titanium at a concentration of 0.03 at.% Or more and 10 at.% Or less.

  According to the present invention, a silicon substrate whose surface is a (111) crystal plane is used.

  Further, hafnium or titanium is added to zirconium oxide which is an insulating film, or titanium is added to hafnium oxide.

  In addition, cobalt silicide or silicon is used as an electrode material in which oxygen hardly diffuses at the interface with an insulating film containing zirconium oxide or hafnium oxide as a main constituent element.

  Furthermore, a polycrystalline silicon film having a (111) orientation is used for a semiconductor device having a thin film transistor structure.

  With the above structure, it is possible to realize a highly reliable semiconductor device in which deterioration of characteristics due to miniaturization can be suppressed.

  In addition, a miniaturized semiconductor device with high yield can be realized.

  In addition, a semiconductor device having a gate structure in which oxygen hardly diffuses at the interface between the silicon substrate and the gate insulating film can be realized.

  Furthermore, a semiconductor device having a thin film transistor structure in which oxygen is difficult to diffuse at the interface between the silicon film and the gate insulating film can be realized.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional structure diagram of the main part of the semiconductor device according to the first embodiment of the present invention.

  In the semiconductor device according to the first embodiment of the present invention, diffusion layers 2, 3, 4, and 5 are formed on a silicon substrate 1, as shown in FIG. The gate insulating films 6 and 7 and the gate electrodes 8 and 9 are formed on the diffusion layers 2, 3, 4, and 5 to constitute a MOS transistor.

  For the gate insulating films 6 and 7, zirconium oxide or hafnium oxide is used as a main constituent material in order to satisfy the demand for miniaturization and high functionality of the semiconductor device.

  These gate insulating films 6 and 7 are formed using, for example, chemical vapor deposition or sputtering.

  Here, a substrate having a (111) crystal plane is used for the silicon substrate 1 so that oxygen hardly diffuses into the silicon substrate 1 and the gate electrodes 8 and 9 during the heat treatment.

  When zirconium oxide is used as the main constituent material of the gate insulating films 6 and 7, it is more preferable to contain hafnium or titanium as an additive element of the gate insulating films 6 and 7.

  Further, when zirconium oxide is used as the main constituent material of the gate insulating films 6 and 7, it is more preferable to contain titanium as an additive element of the gate insulating films 6 and 7.

  Further, as the main constituent material of the gate electrodes 8 and 9, it is more preferable to use cobalt silicide or silicon as a material in which oxygen is difficult to diffuse from the gate insulating films 6 and 7 during heat treatment. The gate electrodes 8 and 9 are formed using, for example, chemical vapor deposition or sputtering.

  These MOS transistors are isolated by, for example, an element isolation film 10 made of a silicon oxide film. Insulating films 11 and 12 made of, for example, a silicon oxide film are formed on the top and side walls of the gate electrodes 8 and 9.

  Further, the entire upper surface of the MOS transistor is made of, for example, a BPSG (Boron-Doped Phospho Silicate Glass) film, an SOG (Spin On Glass) film, or a silicon oxide film or a nitride film formed by chemical vapor deposition or sputtering. An insulating film 13 is formed.

  The contact hole formed in the insulating film 13 is formed with a plug composed of a plurality of main conductor films 15 covered with adjacent conductor films (first conductor films) 14a and 14b for preventing diffusion. The plug 15 is connected to the diffusion layers 2, 3, 4, and 5.

  Connected to the plug 15 is a first laminated wiring composed of a main conductor film 17 covered with adjacent conductor films 16a and 16b for preventing diffusion.

  In the first laminated wiring, for example, the adjacent conductor film 16a is formed by sputtering or the like, then the main conductor film 17 is formed by sputtering or the like, and the adjacent conductor film 16b is formed thereon by sputtering or the like. It is obtained by forming a wiring pattern by etching after formation.

  On the first laminated wiring, a plug made of the main conductive film 20 covered with the adjacent conductive film 19 is formed in the contact hole formed in the insulating film 21, and this plug is connected to the first laminated wiring. Has been.

  The plug is connected to the second laminated wiring composed of the main conductor film 23 covered with the adjacent conductor films 22a and 22b. In the second laminated wiring, for example, the adjacent conductor film 22a is formed by sputtering or the like, then the main conductor film 23 is formed by sputtering or the like, and the adjacent conductor film 22b is formed thereon by sputtering or the like. Then, a wiring pattern is formed and formed by etching or the like.

Next, the effect of suppressing oxygen diffusion in the first embodiment of the present invention will be described below.
In order to explain the effect of the first embodiment of the present invention in detail, an analysis example by molecular dynamics simulation is shown. This molecular dynamics simulation is described in, for example, pages 4864 to 4878 of Journal of Applied Physics, Volume 54 (published in 1983).

  In other words, molecular dynamics simulation is a method of calculating the position of each atom at each time by calculating the force acting on each atom through the interatomic potential and solving Newton's equation of motion based on this force. .

  In the embodiment of the present invention, the relationship described later could be obtained by calculating the interaction between different elements by incorporating charge transfer into the molecular dynamics method.

  The main effect of the first embodiment of the present invention is that a silicon substrate whose surface is a (111) crystal face is used instead of a silicon substrate whose surface is a (001) crystal face, which is used in a normal semiconductor device. By using this, diffusion of oxygen from the gate insulating film to the silicon substrate is suppressed. As a result, it is possible to realize a semiconductor device in which the occurrence of leakage current or the like is suppressed and the characteristics are improved.

  Another effect is that the diffusion of oxygen from the gate insulating film to the silicon substrate is suppressed by adding an additive element to the gate insulating film.

  Furthermore, another effect of the first embodiment of the present invention is that the diffusion of oxygen from the gate insulating film to the gate electrode is suppressed by adding an additive element to the gate insulating film.

The operational effects of the first embodiment of the present invention can be analyzed by calculating the diffusion coefficient of oxygen and comparing this with the presence or absence of an additive element.
The method for calculating the diffusion coefficient by molecular dynamics simulation is described, for example, from page 5363 to page 5371 of Volume 29 (issued in 1984) of Physical Review B.

  First, both have a structure in which a gate insulating film with a thickness of 3 nm is formed on a silicon substrate with a thickness of 10 nm, and the surface has a (001) plane and the surface has a (111) plane. The structure is used as an analysis model, and calculation examples for oxygen diffusion of these structures are shown. Thus, an effect of the first embodiment of the present invention having a structure using a silicon substrate whose surface is a (111) crystal plane is shown.

  FIG. 2 is a graph showing the results of calculating the ratio of the oxygen diffusion coefficient D when oxygen in the zirconium oxide film (gate insulating film) diffuses into the silicon substrate at 300 ° C.

2, the diffusion coefficient when the surface is a silicon substrate is a (001) plane and D _R, showed the ratio of the diffusion coefficient D, which was used a surface of the silicon substrate is a (111) surface . As can be seen from FIG. 2, the diffusion coefficient D when the silicon substrate having the (111) plane is used is less than 1/100 of the diffusion coefficient when using the silicon substrate having the (001) plane. It is a coefficient and shows the effect of suppressing the diffusion of oxygen.

  Therefore, it can be understood that when a silicon substrate having a (111) surface is used, diffusion of oxygen from the gate insulating film to the silicon substrate is suppressed and oxygen vacancies are hardly formed in zirconium oxide.

  FIG. 3 is a graph showing calculation results similar to those in FIG. 2 when hafnium oxide is used instead of zirconium oxide as the gate insulating film.

In the example shown in FIG. 3, as in the case of the example of FIG. 2, the diffusion coefficient when the surface is a silicon substrate is a (001) plane and D _R, a silicon substrate is (111) plane The ratio with the diffusion coefficient D when using is shown.

  As can be understood from FIG. 3, the diffusion coefficient when the silicon substrate having the (111) surface is less than 1/1000 of the diffusion coefficient when the silicon substrate having the (001) surface is used. Thus, the effect of suppressing the diffusion of oxygen is shown.

  Therefore, it can be understood that the diffusion of oxygen from the gate insulating film to the silicon substrate is suppressed, and oxygen vacancies are hardly formed in hafnium oxide.

  Next, an embodiment of the present invention is shown by showing a calculation example using a structure in which a 3 nm-thick gate insulating film is formed on a 10 nm-thick silicon substrate whose surface is a (111) plane as an analysis model. The effect of adding an element to the gate insulating film due to the above will be described.

  4 and 5 are graphs showing the results of calculating the ratio of the oxygen diffusion coefficient D to the concentration of the additive element when oxygen in the zirconium oxide film (gate insulating film) diffuses into the silicon substrate.

D ₀ is the diffusion coefficient of oxygen when no additive element is included, and FIG. 4 shows the results of showing the dependency of D / D _{0 on} the concentration of addition in the low concentration region. FIG. 5 is a result showing the dependency of D / D _{0 on} the addition concentration in the high concentration region.

  From FIG. 4, the diffusion coefficient is reduced when hafnium is added to the zirconium oxide film in an amount of 0.01 at.% Or more compared to the case of no addition, but when 0.04 at.% Or more is added, the diffusion coefficient is not added. It can be seen that the remarkable effect of being reduced to about one-third of that in the case of is obtained.

  Further, when titanium is added to the zirconium oxide film in an amount of 0.005 at.% Or more, the diffusion coefficient is reduced as compared with the case of no addition, but when it is added in an amount of 0.02 at.% Or more, the diffusion coefficient is not added. It can be seen that a remarkable effect of being reduced to about 1/11 of the above can be obtained.

  Referring to FIG. 5, it can be understood that the effect of reducing the diffusion coefficient is effective up to the addition concentration of hafnium up to 15 at. Further, it can be seen that the effect of reducing the diffusion coefficient is effective up to the addition concentration of titanium up to 15 at.%, But the effect becomes weak when the concentration is 8 at.% Or more.

  Therefore, hafnium is added to a film containing zirconium oxide as a main constituent element at a concentration of 0.01 at.% To 15 at.%, Or titanium is added at a concentration of 0.005 at.% To 15 at.%. Therefore, oxygen diffusion can be reduced.

  Further, hafnium is added to the film containing zirconium oxide as a main constituent element at a concentration of 0.04 at.% To 12 at.%, Or titanium is added at a concentration of 0.02 at.% To 8 at.%. Thus, oxygen diffusion can be reduced more stably.

  The effects of the first embodiment of the present invention described above can be obtained in the same manner even when the calculation conditions such as the film thickness and temperature are changed.

  Next, FIGS. 6 and 7 show an oxygen diffusion coefficient D when oxygen in the hafnium oxide film (gate insulating film) diffuses into the silicon substrate in the same analysis model as the example shown in FIGS. It is a graph which shows the result of having calculated ratio.

6 and 7, D ₀ is the oxygen diffusion coefficient when no additive element is included, and FIG. 6 shows the results showing the dependence of D / D _{0 on} the addition concentration in the low concentration region. shows the results showed addition concentration dependence of D / D ₀ in the high concentration region.

  From FIG. 6, when 0.01 at.% Or more of titanium is added to the hafnium oxide film, the diffusion coefficient is reduced as compared with the case of no addition, but when 0.03 at.% Or more is added, the diffusion coefficient is not added. It can be seen that a remarkable effect of being reduced to about one-third of the case is obtained.

  Further, FIG. 7 shows that the effect of reducing the diffusion coefficient is effective up to the addition concentration of titanium up to 15 at.%, But it becomes weaker when the addition concentration of titanium exceeds 10 at.%.

  Therefore, the diffusion of oxygen can be reduced by adding titanium to the film containing hafnium oxide as a main constituent element at a concentration of 0.01 at.

  Furthermore, by adding titanium to a film containing hafnium oxide as a main constituent element at a concentration of 0.03 at.% Or more and 10 at.% Or less, oxygen diffusion can be stabilized and further reduced.

  The effects of the present invention described above can be obtained in the same manner even when the calculation conditions such as the film thickness and temperature are changed.

  Next, as another effect of the first embodiment of the present invention, a molecular dynamics analysis example shows that the diffusion of oxygen from the gate insulating film to the gate electrode is suppressed by the additive element. Here, an example is shown in which the diffusion coefficient of oxygen at 300 ° C. is calculated using a structure in which an electrode film having a thickness of 3 nm is formed on a gate insulating film having a thickness of 3 nm as an analysis model.

FIG. 8 and FIG. 9 are graphs showing examples of results using zirconium oxide as the gate insulating film and using a cobalt silicide film and a silicon film as the electrodes. 8 and 9, D ₀ is the diffusion coefficient of oxygen when no additive element is included, and FIG. 8 shows the result of showing the dependency of D / D _{0 on} the concentration of addition in the low concentration region. FIG. 9 is a result showing the dependency of D / D _{0 on} the addition concentration in the high concentration region.

  From FIG. 8, as in FIG. 4, when hafnium is added to the zirconium oxide film in an amount of 0.01 at.% Or more, the diffusion coefficient is reduced as compared with the case of no addition, but 0.04 at.% Or more. It can be seen that when added, the remarkable effect is obtained that the diffusion coefficient is reduced to about 1/13 or less of the value obtained without addition.

  Further, when titanium is added to the zirconium oxide film in an amount of 0.005 at.% Or more, the diffusion coefficient is reduced as compared with the case of no addition, but when 0.02 at.% Or more is added, the diffusion coefficient is not added. It turns out that the remarkable effect that it is reduced to about 1/12 or less of the value is obtained.

  Further, from FIG. 9, as in the case of FIG. 5, the effect of reducing the diffusion coefficient is considered to be effective up to the addition concentration of hafnium up to 15 at. Recognize.

  Further, it can be seen that the effect of reducing the diffusion coefficient is effective up to the addition concentration of titanium up to 15 at.%, But the effect becomes weak when the concentration is 8 at.% Or more.

  Therefore, hafnium is added to a film containing zirconium oxide as a main constituent element at a concentration of 0.01 at.% To 15 at.%, Or titanium is added at a concentration of 0.005 at.% To 15 at.%. Therefore, oxygen diffusion can be reduced.

  Further, hafnium is added to a film containing zirconium oxide as a main constituent element at a concentration of 0.04 at.% To 12 at.%, Or titanium is added at a concentration of 0.02 at.% To 8 at.%. Therefore, oxygen diffusion can be reduced.

  In addition, the above effect can be shown similarly even if calculation conditions, such as a film thickness and temperature, are changed.

  FIG. 10 and FIG. 11 are graphs showing an example of the result of using hafnium oxide as a gate insulating film and using a cobalt silicide film and a silicon film as electrodes in the same analysis model as described above.

10 and 11, D ₀ is the oxygen diffusion coefficient when no additive element is included, and FIG. 10 shows the result of the dependency of D / D _{0 on} the concentration of addition in the low concentration region. FIG. 11 is a result showing the dependency of D / D _{0 on} the addition concentration in the high concentration region.

  From FIG. 10, as in the case of FIG. 6, when titanium is added to the hafnium oxide film by 0.01 at.% Or more, the diffusion coefficient is reduced as compared with the case of no addition, but 0.03 at. Then, it turns out that the remarkable effect that a diffusion coefficient is reduced to about 1/13 or less of the value without addition is acquired.

  From FIG. 11, as in the case of FIG. 7, the effect of reducing the diffusion coefficient is effective when the titanium addition concentration is up to 15 at.%, But it becomes weak when the titanium addition concentration is 10 at.% Or more. I understand.

  Therefore, the diffusion of oxygen can be reduced by adding titanium to the film containing hafnium oxide as a main constituent element at a concentration of 0.01 at.

  Furthermore, by adding titanium to a film containing hafnium oxide as a main constituent element at a concentration of 0.03 at.% Or more and 10 at.% Or less, oxygen diffusion can be stabilized and further reduced.

  The above effects can be obtained in the same manner even if the calculation conditions such as the film thickness and temperature are changed.

  In the above calculation example, the cobalt silicide film and the silicon film are used as the electrodes, but the same effect can be obtained even if other materials are used. However, the fact that cobalt silicide and silicon are more preferable as electrode materials will be explained from the following calculation example.

  12 and 13 show the results of calculating oxygen diffusion coefficients for various electrode materials using a structure in which an electrode film having a thickness of 3 nm is formed on a gate insulating film having a thickness of 3 nm as an analysis model. It is a graph which shows.

  12 and 13 show the diffusion coefficient of oxygen at 300 ° C. when no additive element is included. FIG. 12 shows the result when the gate insulating film is a zirconium oxide film, and FIG. 13 shows the case where the gate insulating film is a hafnium oxide film. Is the result of the case.

  12 and 13, it can be seen that the diffusion coefficient using cobalt silicide and silicon as the electrode material is remarkably small as compared with the case of using other electrode materials.

  Therefore, it is more preferable to use cobalt silicide and silicon as electrode materials in terms of reducing oxygen diffusion.

Next, FIG. 14 shows a cross-sectional structure of the main part of the semiconductor device according to the second embodiment of the present invention.
The main difference between the second embodiment and the first embodiment is that the gate insulating film has a two-layer structure including the first gate insulating films 6a and 7a and the second gate insulating films 6b and 7b. It is. In the second gate insulating films 6b and 7b, zirconium oxide or hafnium oxide is used as a main constituent material in order to satisfy the demand for miniaturization and high functionality. For the first gate insulating films 6a and 7a, for example, a film containing silicon oxide, zirconia silicate, or hafnium silicate as a main constituent material is used.

  According to the second embodiment of the present invention, the same effect as that of the first embodiment can be obtained, and the effect of improving the thermal stability of the second gate insulating films 6b and 7b can be obtained.

  In addition, although the example mentioned above is an example at the time of making a gate insulating film into a two-layer structure, although not shown in a figure, the gate insulating film may have a structure of three or more layers.

FIG. 15 is a diagram showing a cross-sectional structure of the main part in the semiconductor device according to the third embodiment of the present invention.
The main difference between the third embodiment and the second embodiment described above is that the gate electrode film has a two-layer structure including the first gate electrode films 8a and 9a and the second gate electrode films 8b and 9b. The other configurations are the same as those of the second embodiment and the third embodiment.

  As the main constituent material of the first gate electrode films 8a and 9a, it is more preferable to use cobalt silicide or silicon as a material that hardly diffuses oxygen.

  For the second gate electrode films 8b and 9b, it is more preferable to use a film whose main constituent material is a metal such as tungsten or molybdenum to reduce the electrical resistance of the entire gate electrode.

  In this case, although not shown in the drawing, another conductive film may be provided between the first gate electrode films 8a and 9a and the second gate electrode films 8b and 9b. As the conductive film, for example, a film having an effect of preventing mutual diffusion between the first gate electrode films 8a and 9a and the second gate electrode films 8b and 9b, such as a TiN film and a WN film, is used. More preferred.

  As described above, according to the third embodiment of the present invention, the same effect as that of the second embodiment can be obtained, and the effect that the electric resistance of the gate electrode can be reduced can be obtained. it can.

FIG. 16 is a cross-sectional structure diagram of a memory cell in the semiconductor device according to the fourth embodiment of the present invention.
The main difference between the fourth embodiment and the first, second, and third embodiments described above is that the fourth embodiment has a conductive barrier film 114, a capacitor lower electrode 115, a high dielectric constant, and the like. The information storage capacitor element 103 has a structure in which an oxide film 116 having a dielectric constant or ferroelectricity and a capacitor upper electrode 117 are stacked.

  Here, it is known that the oxide film 116 having a high dielectric constant or ferroelectricity does not exhibit good characteristics unless it is subjected to heat treatment. Heat treatment at 700 ° C. or higher is required.

  During this heat treatment, the elements easily diffuse into the gate insulating film from the gate electrode film, so that in the case of a semiconductor memory using an oxide film having a high dielectric constant or ferroelectricity, this element is further increased. There is a high need to suppress diffusion.

Next, the main structure of the semiconductor device which is the 4th Embodiment of this invention is demonstrated below.
As shown in FIG. 16, the semiconductor device according to the fourth embodiment of the present invention includes a MOS (Metal Oxide Semiconductor) type transistor 102 formed in an active region on the main surface of a silicon substrate 101 and an upper portion thereof. The information storage capacitive element 103 is provided. Reference numeral 104 denotes an element isolation film, and 109 denotes an insulating film.

  The insulating film 112 is a film for element isolation. The MOS transistor 102 of the memory cell includes a gate electrode film 105, a gate insulating film 106, and diffusion layers 107 and 108. The gate insulating film 106 uses zirconium oxide or hafnium oxide as a main constituent material in order to satisfy the demand for miniaturization and high functionality.

  The gate insulating film 106 is formed by using, for example, chemical vapor deposition or sputtering. When zirconium oxide is used as the main constituent material of the gate insulating film so that oxygen hardly diffuses into the silicon substrate or the gate electrode during heat treatment, hafnium or titanium should be included as an additive element of the gate insulating film. Is more preferable.

  In addition, when zirconium oxide is used as the main constituent material of the gate insulating film, it is more preferable to contain titanium as an additive element of the gate insulating film. For example, the gate insulating film may have a structure of two or more layers as in the second and third embodiments.

  In addition, as a main constituent material of the gate electrode film 105, cobalt silicide or silicon is more preferably used as a material in which oxygen does not easily diffuse. Furthermore, the gate electrode may have a structure of two or more layers as in the third embodiment, for example. The gate electrode film 105 is formed by using, for example, chemical vapor deposition or sputtering.

  An insulating film 9 made of, for example, a silicon oxide film is formed on the top and side walls of the gate electrode film 105. A bit line 111 is connected to one diffusion layer 107 of the memory cell selection MOS transistor via a plug 110.

  Further, on the entire upper surface of the MOS transistor, for example, a BPSG (Boron-doped Phospho Silicate Glass) film, an SOG (Spin On Glass) film, a silicon oxide film or a nitride film formed by chemical vapor deposition or sputtering, etc. An insulating film 112 made of is formed.

  An information storage capacitive element 103 is formed on the insulating film 112 covering the MOS transistor. The information storage capacitive element 103 is connected to the other diffusion layer 108 of the memory cell selection MOS transistor via a plug 113 made of, for example, polycrystalline silicon.

  The information storage capacitor element 103 has a structure in which a conductive barrier film 114, a capacitor lower electrode 115, an oxide film 116 having a high dielectric constant, and a capacitor upper electrode 117 are stacked in this order from the lower layer. Further, the capacitor upper electrode 117 is covered with an insulating film 118. For example, zirconium oxide or hafnium oxide is used as a main constituent material of the oxide film 116.

  It is preferable to use a silicon film having (111) orientation as the capacitor upper electrode or the capacitor lower electrode so that oxygen does not easily diffuse into the capacitor upper electrode and the capacitor lower electrode during the heat treatment.

  In the case where zirconium oxide is used as the main constituent material of the oxide film 116, it is more preferable to contain hafnium or titanium as an additive element of the oxide film 116.

  In the case where zirconium oxide is used as the main constituent material of the oxide film 116, it is more preferable that titanium be contained as an additive element of the oxide film 116. Note that the information storage capacitor element 103 is covered with an insulating film 118.

As described above, according to the fourth embodiment of the present invention, an effect similar to that of the first embodiment can be obtained.
As another application example of the present invention, a system LSI in which a memory LSI as in the fourth embodiment and a logic LSI as in the first, second, and third embodiments are mounted on the same substrate. Can be considered.

FIG. 17 is a diagram showing a thin film transistor (TFT) structure in a semiconductor device according to the fifth embodiment of the present invention. As shown in FIG. 17, the semiconductor device according to the fifth embodiment of the present invention includes, for example, a conductive film (silicon film) 202 made of polycrystalline silicon and zirconium oxide or An insulating film (gate insulating film) 203 mainly composed of hafnium oxide, a conductive film (gate electrode film) 204 made of polycrystalline silicon, for example, an n-type silicon film 205, a drain electrode film 206, and a source It has a TFT structure in which an electrode film 207 and an insulating film 208 are formed. Here, in order to prevent oxygen from diffusing and escaping from the insulating film 203 containing zirconium oxide or hafnium oxide as a main constituent material, a conductive structure is used. A silicon film having (111) orientation is used as the film 202 or the conductive film 204.

  Thereby, also in the fifth embodiment of the present invention, it is possible to realize a semiconductor device having a TFT structure in which oxygen is prevented from diffusing and escape from the insulating film 203 and characteristics are improved.

It is sectional drawing of the principal part of the semiconductor device which is 1st Embodiment in this invention. It is the graph which compared the case of a (001) crystal plane and the case of a (111) crystal plane about the diffusion coefficient of oxygen when oxygen of a zirconium oxide film diffuses to a silicon substrate. It is the graph which compared the case of a (001) crystal face and the case of a (111) crystal face about the diffusion coefficient of oxygen when oxygen of a hafnium oxide film diffuses to a silicon substrate. It is the graph which showed the diffusion coefficient of oxygen at the time of the oxygen of a zirconium oxide film diffusing to a silicon substrate about the field where the addition concentration of an additive is low. It is the graph which showed the diffusion coefficient of oxygen at the time of the oxygen of a zirconium oxide film diffusing to a silicon substrate about the field where the additive concentration of an additive is high. It is the graph which showed the diffusion coefficient of oxygen at the time of the oxygen of a hafnium oxide film diffusing to a silicon substrate about the field where the addition concentration of an additive is low. It is the graph which showed the diffusion coefficient of oxygen at the time of the oxygen of a hafnium oxide film diffusing to a silicon substrate about the field where the addition concentration of an additive is high. 5 is a graph showing a region in which the concentration of oxygen added to a zirconium oxide film is low using a structure in which an electrode film is formed on a zirconium oxide film as an analysis model. It is the graph which used the structure in which the electrode film was formed on the zirconium oxide film as an analysis model, and showed the diffusion coefficient of oxygen about the field where the concentration of addition to the zirconium oxide film is high. FIG. 5 is a graph showing an oxygen diffusion coefficient in a region where the concentration of addition to the hafnium oxide film is low, using a structure in which an electrode film is formed on a hafnium oxide film as an analysis model. 5 is a graph showing a region in which the concentration of oxygen added to a hafnium oxide film is high, using a structure in which an electrode film is formed on a hafnium oxide film as an analysis model. It is the graph which showed the diffusion coefficient of oxygen with respect to various electrode materials using the structure in which the electrode film was formed on the zirconium oxide as an analysis model. It is the graph which showed the diffusion coefficient of oxygen with respect to various electrode materials using the structure in which the electrode film was formed on hafnium oxide as an analysis model. It is sectional drawing of the principal part of the semiconductor device which is the 2nd Embodiment in this invention. It is sectional drawing of the principal part of the semiconductor device which is the 3rd Embodiment in this invention. It is sectional drawing of the principal part of the semiconductor device which is the 4th Embodiment in this invention. It is sectional drawing of the TFT structure part of the semiconductor device which is the 5th Embodiment in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2, 3, 4, 5 Diffusion layer 6, 6a, 6b Gate insulating film 7, 7a, 7b Gate insulating film 8, 8a, 8b Gate electrode 9, 9a, 9b Gate electrode 10 Element isolation film 11, 12, 13, 18 Insulating film 21, 24, 25 Insulating film 14a, 14b, 16a Adjacent conductor film 16b, 19, 22a, 22b Adjacent conductor film 15, 17, 20, 23 Main conductor film 101 Silicon substrate 102 Transistor 103 Information Storage capacitor element 104 Element isolation film 105 Gate electrode 106 Gate insulating film 107, 108 Diffusion layer 109, 112 Insulating film 110, 113 Plug 111 Bit line 114, 202, 204 Conductive film 115 Capacitor lower electrode 116 Capacitor insulating film (oxide) Material film)
117 Capacitance upper electrode 118, 203, 208 Insulating film 201 Glass substrate 205 N-type silicon film 206 Drain electrode film 207 Source electrode film

Claims (4)

A semiconductor device comprising a silicon substrate, a gate insulating film made mainly of hafnium oxide formed in contact with one main surface of the silicon substrate, and a gate electrode film formed in contact with the gate insulating film In
The silicon one main surface of the substrate is a silicon (111) Ri parallel der crystal plane,
The main constituent material of the gate electrode film is cobalt silicide or silicon,
A semiconductor device characterized in that the gate insulating film contains titanium at a concentration of 0.01 at . A semiconductor device comprising a silicon substrate, a gate insulating film made mainly of hafnium oxide formed in contact with one main surface of the silicon substrate, and a gate electrode film formed in contact with the gate insulating film In
One principal surface of the silicon substrate is parallel to a (111) crystal plane of silicon;
The main constituent material of the gate electrode film is cobalt silicide or silicon,
A semiconductor device, wherein the gate insulating film contains titanium at a concentration of 0.03 at.% Or more and 10 at.% Or less . A substrate, a first silicon film formed on one main surface side of the substrate, a gate insulating film formed in contact with the first silicon film, and a gate electrode formed in contact with the gate insulating film With a membrane,
The first silicon film has (111) orientation, and the main constituent material of the gate insulating film is hafnium oxide;
The gate electrode film is a second silicon film having (111) orientation,
A semiconductor device characterized in that the gate insulating film contains titanium at a concentration of 0.01 at . A substrate, a first silicon film formed on one main surface side of the substrate, a gate insulating film formed in contact with the first silicon film, and a gate electrode formed in contact with the gate insulating film With a membrane,
The first silicon film has (111) orientation, and the main constituent material of the gate insulating film is hafnium oxide;
The gate electrode film is a second silicon film having (111) orientation,
A semiconductor device, wherein the gate insulating film contains titanium at a concentration of 0.03 at.% Or more and 10 at.% Or less .

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