This Utility Patent Application claims priority to German Patent Application No. DE 10 2007 018 013.8-45 filed on Apr. 17, 2007, which is incorporated herein by reference.
The invention relates to an integrated circuit including a dielectric layer. The invention furthermore relates to a method for producing an integrated circuit including a dielectric layer.
Dielectric layers or dielectric elements are widely employed in electrical engineering. The dielectric layers, in conjunction with electrodes, are often used as capacitors or control electrodes. A capacitor may, for example, be embodied by two electrodes with a dielectric layer arranged in between, wherein the capacitance of the capacitor arises depending on the area of the electrodes, the distance between the electrodes and the dielectric constant of the dielectric layer. If the dielectric layer has a high dielectric constant, then the capacitance can be increased even with a small or limited electrode area.
It is hardly possible to imagine modern integrated circuits without dielectric layers, capacitances, control electrodes and related units. By way of example, capacitors are used as charge stores in electronic memory devices, such as in a dynamic random access memory for example. Furthermore, dielectric layers are likewise widely employed as part of a control electrode of a transistor, for example in the form of a gate electrode. A high and optimized dielectric constant of the dielectric layer is often desirable in this case.
The advancing miniaturization of the feature sizes of large scale integrated circuits has the effect that the available electrode areas and distances, and also the possible layer thicknesses, become smaller and smaller. In order to obtain a sufficiently high capacitance with small areas, therefore, the dielectric constant is often chosen to be as high as possible. Thus, high-k materials, which have a high dielectric constant, are employed for example in modern DRAM memory devices. Examples of high-k materials of this type are hafnium- or zirconium-containing oxides, transition metal oxides or barium strontium titanate.
The miniaturization of the feature sizes leads not only to a reduction of the available electrode sizes but also to a minimization of layer thicknesses. Although thin layers can permit an increase in the capacitance, disadvantageous effects can arise, such as the increase in leakage currents for example. A leakage current can disadvantageously short-circuit two electrodes via the dielectric material arranged in between, such that, by way of example, stored charge flows away in a disadvantageous manner.
Industrial and scientific methods for producing dielectric layers include sophisticated and readily reproducible methods such as, for example, layer depositions (atomic layer deposition, ALD), vapor deposition methods (physical vapor deposition—PVD, chemical vapor deposition—CVD) and other related methods.
These methods produce amorphous, crystalline, partly crystalline or polycrystalline layers having one or a plurality of interfaces with adjacent layers or between respectively two adjacent crystallites of the dielectric layer. In the context of interfaces between two crystallites of a polycrystalline material, they are also referred to as grain boundaries. At these interfaces, unsaturated bonds can lead to interface states which can lead to charge accumulation, on the one hand, and to charge transport, on the other hand. The charge accumulation and/or charge transport may be disadvantageous with regard to the dielectric constant and/or the leakage currents.
Conventional methods for producing modern dielectric layers therefore include a step of saturating the unsaturated bonds, for example by using an implantation of specific elements. However, implantation methods can considerably disrupt the structure of the irradiated materials and/or require thermal annealing, such that the implanted atoms diffuse to the interfaces in order to saturate the unsaturated bonds there. The disruption of the internal structure and/or the thermal after-treatment may be disadvantageous in the case of modern integrated circuits. Thus, by way of example, the production of modern integrated circuits is provided with only a limited thermal budget, and exceeding the latter can disadvantageously affect electronic units that have already been patterned.
The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.
In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.
It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other, unless specifically noted otherwise.
One or more embodiments provide an integrated circuit and method for producing an integrated circuit including a dielectric layer.
One embodiment provides a method for producing a dielectric layer on a substrate. The dielectric layer is deposited in a process atmosphere, wherein the process atmosphere includes a first starting component at a first point in time, a second starting component at a second point in time and a third starting component at a third point in time. The third starting component includes a halogen.
Another embodiment provides a dielectric layer on a substrate. The dielectric layer includes a first component, a second component and a third component. The third component includes a halogen.
The method is suitable for the deposition of the dielectric layer 10 with a curved topography, too, since the starting components in the process atmosphere cover the substrate surface, independently of the topography. Thus, the dielectric of a capacitor, for example of the trench capacitor in
In accordance with one embodiment, the volume region 110 of the dielectric layer 11 has the third component 50. The distribution of the third component 50 in the volume region 110 can be embodied homogeneously, or else inhomogeneously. A homogeneous distribution of the third component 50 shall be characterized by the fact that when the volume region 110 is divided into two partial volume regions of identical size, the number of third components 50 in a first partial region does not deviate more than 10% from the number of third component 50 in a second partial region. The volume region 110 can have less than 20%, less than 10% or less than 5% of the third component 50.
In accordance with one embodiment, the dielectric layer 12 has the third component 50 in the volume region 120 and at the interface 1200. The third component 50 can therefore saturate unsaturated states which may be arranged primarily along the interface 1200. An accumulation of charge at the interface 1200 and/or a leakage current through the dielectric layer 12, or along the interface 1200, can thus be effectively reduced or suppressed. The unsaturated bonds arranged at the interface 1200 may be represented by free orbitals of the first or second component or of a component of the substrate 23.
In accordance with one embodiment, the dielectric layer 13 has at least two volume regions, the volume region 130 and the further volume region 131. The volumes regions 130, 131 may be represented, for example, by crystallites of a polycrystalline dielectric layer 13. The interface 1310 is to be identified as a grain boundary in this case. In accordance with one embodiment, the dielectric layer 13 has the third component 50 both in the volume regions 130, 131 and at the interfaces 1300, 1311 with the substrate 23 and at the interface 1310 between the volume regions 130, 131. In accordance with one embodiment, unsaturated states at the interfaces 1310, 1300 and 1311 are saturated or passivated by the third component 50. In addition to the reduction or suppression of charge accumulation, it is also possible to form a significant reduction or suppression of a leakage current, primarily along the interface 1310. Precisely leakage currents along an interface which reaches from one side of the dielectric layer 13 to the other side of the dielectric layer 13 in the direction of an electrode normal, such as the interface 1310, for example, can have a disadvantageous effect since a current can arise between two opposite electrodes, respectively arranged at the two sides, and charge can flow away. The provision of the third component 50 in the volume regions 130, 131 and at the interfaces 1300, 1311, 1310 reduces or suppresses the formation of leakage currents. With regard to the components, substances or materials used and their distribution, reference should be made to the description of
In accordance with one embodiment, the dielectric layer 14 has at least two volume regions, the volume region 140 and the further volume region 141. The volume regions 140, 141 may be represented, for example, by crystallites of a polycrystalline dielectric layer 14. The interface 1410 is to be identified as a grain boundary in this case. In accordance with one embodiment, the dielectric layer 14 has the third component 50 both in the volume regions 140, 141 and at the interfaces 1400, 1401, 1410, 1411 and 1412 with the substrate 23, between the volume regions 140, 141 and with respect to further units. In accordance with one embodiment, unsaturated states at the interfaces 1400, 1401, 1410, 1411 and 1412 are saturated or passivated by the third component 50. With regard to advantages and properties of the components, substances or materials used and to their distribution, reference should be made to the description of
The concentrations of the third component 50 at the interfaces 1400 and 1411 with the substrate 23 or a possible electrode and the concentrations of the third component 50 at the interfaces 1401 and 1412 with a possible further electrode can be different, coordinated with one another or coordinated with the respective adjacent element, substrate or electrode or further electrode. The electrode and the further electrode may represent a bottom electrode and a top electrode.
In general, the first component and the third component can also be provided by a starting component. In this case, the starting component then includes the first component and the third component. Examples thereof are the metal-halogen compounds that are also presented below.
The process atmosphere is thereupon emptied S11. In a second introduction S12, the second starting component is then introduced into the process atmosphere. The second starting component can react with the first starting component and/or the third starting component on the substrate in order to deposit the dielectric layer in layer by layer fashion. Possible reaction products can be removed from the process atmosphere, for example by purging with a purge gas, during an emptying S11 or else during the introduction S10, S12. In a bifurcation S13, a decision is made as to whether a desired layer height of the dielectric layer has been reached. If the desired layer height has not yet been reached, the process atmosphere is once again emptied. This is followed by a new sequence S10, S11, S12 for depositing a further partial layer of the dielectric layer. If the desired layer height has been reached, the deposition is ended and further method steps can ensue, also in situ.
Examples of layer by layer deposition methods are atomic layer deposition, nano layer deposition, atomic layer epitaxy, atomic layer chemical vapor deposition, pseudo ALD, i-ALD, plasma enhanced ALD, plasma activated ALD, metal organic ALD, thermally activated ALD, rapid ALD or sequential flow deposition. What is common to all the layer by layer deposition methods mentioned above is that the process atmosphere does not simultaneously contain all the starting components that form the layer to be deposited.
Thus, by way of example, a first starting component can have hafnium, barium, strontium, titanium, silicon, zirconium, lead, tantalum, aluminum and/or a metal. A second starting component can have oxygen and/or nitrogen. In general, a third starting component can include a halogen, for example fluorine, chlorine, bromine, or iodine.
Examples of the third starting component in accordance with the present invention include gases or vapors of liquid or solid halogens or pseudo-halogens, F2, Cl2, Br2, I2, ClF, ClF3, ClF5, BrF, BrF3, BrF5, BrCl, IF3, IF5, IF7, ICl, ICL3, IBr, HF, LiF, NaF, KBr, HBr, LiBr, NaBr, KBr, HCl, LiCl, NaCl, KCl, HI, LiI, NaI, KI, metal halides, Ti(F, Cl, Br, I)2.4, Zr(F, Cl, Br, I)2.4, Hf(F, Cl, Br, I)2.4, Nb(F, Cl, Br, I)2.5, Ta(F, Cl, Br, I)2.5, lanthanide metal halides, Sc(F, Cl, Br, I)3, Y(F, Cl, Br, I)3, La(F, Cl, Br, I)2.3, silicon halides, germanium halides, SiF4, SiCl4, SiBr4, SiI4, GeF2, GeCl2, GeBr2, GeI2, GeF4, GeCl4, GeBr4, GeI4, fluoro-, chloro-, bromo- or iodo-silanes, halogenated methyl-silanes, gases or vapors of liquid or solid halogenated organometallic compounds, halogenated silicon alkylamides, halogenated metal alkylamides, halogenated cyclopentadienyls, halogenated metal cyclopentadienyls, halogenated metallocenes, ZPDRIZPDR2MR3(F, Cl, Br, I), ZPDRIZPDR2M(F, Cl, Br, I)2, where R denote hydrogen, a hydrocarbon group, a methyl group, an ethyl group, an alkoxy group, a methoxy group, an ethoxy group or an amide group, halogenated alkylamidinates, halogenated metal alkylamidinates, halogenated alkoxides, halogenated metal alkoxides. Furthermore, the abovementioned examples can be diluted, be present as precursors, be plasma activated, or be free radicals thereof. In general, plasma enhancement or plasma activation can be effected remote from the actual deposition location of the substrate (remote plasma). In this case, halogen atoms and/or halogen ions can be provided as third starting component.
During S11, the first starting component and the additional starting component are present in the process atmosphere. The respective precursors can react with the precursors of the second starting component in order for example to deposit a fluorine-containing hafnium oxide layer.
In a second introduction S22, the second starting component is then introduced into the process atmosphere. The second starting component can react with the first starting component and/or the third starting component on the substrate in order to deposit the dielectric layer in layer by layer fashion. Possible reaction products can be removed from the process atmosphere, for example by purging with a purge gas, during an emptying S21 or else during the introduction S20, S22.
In a bifurcation S23, a decision is made as to whether a desired layer height of the dielectric layer has been reached. If the desired layer height has not yet been reached, the process atmosphere is once again empty. The concentration of the additional component is set in a setting S24. During the different iterations, the concentration in the setting S24 can be effected in a manner corresponding to a linear concentration profile, a nonlinear concentration profile and/or a concentration profile having one or more maxima. This is followed by a new sequence S20, S21, S22 for depositing a further partial layer of the dielectric layer. If the desired layer height has been reached, the deposition is ended and further method steps can ensue, also in situ.
One characteristic of the method in accordance with one or more embodiments is that the first starting component, the second starting component and the third starting component are introduced simultaneously in the process atmosphere. The starting components can react in order to deposit the dielectric layer on a substrate. The precursors having the first component, the second component and the third component react and leave these in the deposited dielectric layer having first, second and third components. Process products having the first starting component, the second starting component and the third starting component with respect to the first component, the second component and the third component are removed from the process atmosphere progressively or continuously. This can be done by emptying the process atmosphere, pumping the process atmosphere or purging the process atmosphere. Examples of deposition methods in accordance with one embodiment are metal organic chemical vapor deposition, chemical vapor deposition, atomic vapor deposition, plasma enhanced chemical vapor deposition, plasma activated chemical vapor deposition, or pulsed chemical vapor deposition.
The methods can include conversion into a gaseous state of the third starting component proceeding from a liquid or solid state. A conversion of this type can also be effected for the first and second starting components. Generally, substantially the concentration of the third starting component in the process atmosphere during the deposition determines the concentration of the third component in the deposited layer. A further determining factor for the concentration of the third component in the deposited layer may also be given by a ratio to the concentration of the first and/or second starting component. Furthermore, in addition to a first starting component, at least one further first starting component can be provided in order, for example, to combine two different metals with a second component. The third starting component can be coordinated with this, i.e. be present, for example, only together with the first starting component or only together with the further first starting component in the process atmosphere, in order to deposit a partial layer of the dielectric layer.
In a deposition S200, a dielectric layer is deposited on the substrate. With regard to the methods, reference is made to the methods described in connection with
Optionally, a densifying S300 can be effected prior to a further processing S400, which can include parts of a CMOS process. The densifying S300 increases the density of the dielectric layer and can include activation and/or diffusion of the additional component in the dielectric layer. The densifying can be effected by heating. Diffusion can furthermore be effected in connection with a thermal annealing which can also serve for activating possible electronic units in the substrate.
In general, a dielectric layer is provided on a substrate. The dielectric layer is deposited in a process atmosphere, wherein the process atmosphere includes a first starting component at a first point in time, a second starting component at a second point in time and a third starting component at a third point in time. The third starting component includes a halogen.
Accordingly, the third starting component including a halogen is incorporated into the dielectric layer during the deposition of the dielectric layer. A subsequent implantation or diffusion, under certain circumstances at elevated temperatures, is thereby avoided and the thermal loading on the component is restricted to a minimum. This not only significantly increases the process economy, but also leads to a more reliable and increased yield of the production process.
It may be provided that the additional component includes at least one of the elements of the halogens fluorine, chlorine, bromine or iodine.
The layer can be deposited by a layer by layer deposition method. Such a layer by layer deposition method is atomic layer deposition or atomic layer epitaxy, for example. In this case, the dielectric layer is deposited layer by layer, wherein the process atmosphere has the first starting component and the third starting component at the first point in time. A first partial layer having at least parts of the first starting component, for example, the first component, and parts of the third starting component, for example, the second component, is therefore formed on the substrate.
The process atmosphere can thereupon be emptied, for example, by pumping out to a minimum vacuum or by purging with a purge gas. The purge gas can also have the third starting component in order thus to incorporate the third component into the dielectric layer. In this case, it is optional for the third starting component to be present together with the first and/or second starting component in the process atmosphere. The purging with a purge gas having the third starting component can also be effected selectively only for or between specific deposition cycles. Furthermore, the third component can also be incorporated into a metal electrode, for example, into metals, metal oxides, metal nitrides or related materials.
The second starting component can then be admitted into the emptied process atmosphere. However, it is also possible for the first starting component and the third starting component to be replaced by the second starting component, for example, by purging the process atmosphere with the second starting component. A next partial layer having at least parts of the second starting component, for example, the second component, is thus formed. Parts of the first partial layer, for example, the first and/or third starting component, may react with the second starting component in order to progressively deposit the dielectric layer in this way. Process products can be discharged from the process atmosphere continuously or at intervals by purging or pumping out. A substrate temperature of the substrate during the deposition of the dielectric layer can preferably be between 150° C. and 500° C.
The dielectric layer may be deposited by using a vapor deposition method. Known vapor deposition methods are for example chemical vapor deposition, physical vapor deposition, and the numerous variants thereof. In accordance with this embodiment, the process atmosphere can have the first starting component, the second starting component and the third starting component at the first point in time. These three starting components may react in order to deposit the dielectric layer on the substrate. Process products can be discharged from the process atmosphere continuously or at intervals by purging or pumping out. A substrate temperature of the substrate during the deposition can in this case be between 0° C. and 700° C., or else correspond to a room temperature of approximately 20° C.
It may be provided that the first starting component has at least one of the following substances: hafnium, barium, strontium, titanium, silicon, zirconium, lead, tantalum, aluminum and/or a metal. The second starting component can have oxygen and/or nitrogen. One example may include a combination of a first starting component having hafnium, a second starting component having oxygen, and a third starting component having fluorine.
The process atmosphere can have the first starting component at a fourth point in time, wherein the third starting component is substantially absent in the process atmosphere at the fourth point in time. The fact that the third starting component is substantially absent in the process atmosphere means that, for example, only a residual quantity of the third starting component is contained in the process atmosphere. The process atmosphere can be emptied beforehand by being pumped, for example. Furthermore, the process atmosphere can be emptied by purging the process atmosphere by using a purge gas. The previously contained starting components are thereby substantially removed from the process atmosphere, such that the concentration of a starting component contained as a residual quantity is less than 5%, less than 1% or less than 0.1%.
The process atmosphere can have the third starting component in a first concentration at the third point in time and the process atmosphere has the third starting component in a second concentration at the fifth point in time. By this means, during the deposition of the dielectric layer, it is possible to vary the concentration of the third starting component in the process atmosphere and thus the concentration of the third component in the deposited layer. It is thus possible to realize a well-defined profile of the concentration of the third component in the dielectric layer.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.
Number | Date | Country | Kind |
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10 2007 018 013-8 | Apr 2007 | DE | national |