Patent Application
20080282535
Demands imposed on large scale integrated circuits, such as electronic memory devices, micro-processors, signal-processors, and integrated logic devices, are constantly increasing. In the case of electronic memory devices, those demands mainly translate into enlarging storage capacity and into increasing access speed. As far as modern memory devices are concerned, the computer industry has established, amongst others, the so called DRAM (dynamic random access memory) as an economic means for high speed and high capacity data storage.
Although a DRAM requires continuous refreshing of stored information, speed and information density, combined with a relatively low-cost, have put the DRAM to a pivotal position in the field of information technology. Almost every type of computer system, ranging, for example, from PDAs over notebook computers and personal computers to high end servers, takes advantage of this economic and fast data storage technology. Nevertheless, the computer and electronic industry develops alternatives to the DRAM, such as phase change RAM (PC-RAM), conductive bridging RAM (CB-RAM) and magnetic resistive RAM (M-RAM). Other concepts include the so called flash RAM or static RAM (S-RAM), which have already found their established applications.
Since electronic data storage is so ubiquitous, intense industrial and scientific research and development is aimed at optimizing manufacturing processes, increasing process yield, and maximizing device reliability. As a result, there is a need to improve functional elements of integrated electronic devices to meet recent requirements, such as imposed by large scale mass production.
For these and other reasons, there is a need for the present invention.
The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments of the present invention and together with the description serve to explain the principles of the invention. Other embodiments of the present invention and many of the intended advantages of the present invention 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 of the present invention 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.
Various embodiments provide an improved method of fabricating an integrated device, including fabricating a functional layer.
One embodiment provides a method of making an integrated circuit including fabricating a functional layer on a substrate. The method includes providing a substrate in a process atmosphere. A first precursor and a second precursor are provided in the process atmosphere. The first precursor is removed from the process atmosphere. The second precursor is removed from the process atmosphere. A third precursor is provided in the process atmosphere.
One embodiment provides a method of fabricating a functional layer on a substrate. The method includes providing a substrate in a process atmosphere. A first precursor and a second precursor are provided in the process atmosphere. The first precursor is removed from the process atmosphere. A third precursor is provided in the process atmosphere.
These above recited features of the present invention will become clear from the following description, taken in conjunction with the accompanying drawings. It is to be noted, however, that the accompanying drawings illustrate only typical embodiments of the present invention and are, therefore, not to be considered limiting of the scope of the invention. The present invention may admit equally effective embodiments.
The material 49, such as a dopant, may be comprised by the first area 40 in order to electrically functionalize the first area 40. For example, this may be the case for a doped region of a transistor, an electrode, a diode, a resistor, and/or a light emitting or sensing device. The diffusion of the material 49 to the second area 41 may affect the properties of the second area 41 and/or the first area 40. Also, tiny variations in a doping concentration may alter the electrical and/or optical properties of an affected area in such a way that the involved entity, for example a transistor, is rendered useless.
Since integrated devices usually are subject to a certain thermal budget during manufacturing, it may be necessary to take certain measures, such as the provision of the functional layer 42, in order to prevent an undesired diffusion of material during manufacturing. Furthermore, diffusion may take place and may affect the functionality and the performance of the device also during regular operation. Therefore, it may be again necessary to provide a diffusion barrier, such as the functional layer 42.
The arrangement further includes a collar 58 above the trench capacitor 59. The collar 58 includes an insulation collar 53, and a top contact, the top contact having a functional layer 52 and an inner electrode material 51. The inner electrode 51 may include a metal or doped poly-silicon. The electrode 51 may contact a center electrode of the trench capacitor 59 and/or a terminal of a selection transistor. According to this embodiment, the functional layer 52 may act as a liner or a collar liner of the collar 58.
Adjacent to the substrate 100 there is a process atmosphere which includes a first precursor 111 and a second precursor 112. The process atmosphere may be provided by using a process chamber and additional means for controlling the contents of the process atmosphere. Those means may include pumps, valves, flow-meters, vaporizers, gas tanks, plasma-producers, heaters, coolers, vacuum chambers, and/or handling equipment.
The first precursor 111 and the second precursor 112 may react to form a first partial layer 101 of the functional layer. This may be effected during a so called chemical vapor deposition (CVD) or metal-organic chemical vapor deposition (MOCVD). In general, during the provision of the functional layer, a substrate temperature of the substrate 100 may be in the range of 200° C. to 700° C. in order to influence, to enhance, or to activate the deposition or provision. The pressure of the process atmosphere may be in a range of 0.1 Torr to 10 Torr.
The first precursor 111 may include titanium-tetra-chloride (TiCl4), titanium, titanium-chloride, zirconium, hafnium, niobium, tantalum, tungsten, fluorine, chlorine, bromine, iodine, a metal-alkyl-amide, a metal-organic (MO) precursor, and/or a metal halide. Metal-alkyl-amides may include a tantalum-alkyl-amide, such as TAIMATA, TBTEMT, TBTDET, IPTEMT, or PDMAT, a zirconium-alkyl-amide, such as TDMAZ, TEMAZ, or TDEAZ, or a hafnium-alkyl-amide, such as TDMAH, TEMAH, or TDEAH.
The second precursor 112 may include ammonia (NH3), hydrogen, and/or nitrogen.
Reaction products may be continuously removed from the process atmosphere, for example, by purging with an inert gas, such as helium, neon, argon, krypton, xenon, and/or nitrogen.
As an example the first precursor 111 may include titanium-tetra-chloride (TiCl4) and the second precursor 112 may include ammonia (NH3). Reaction products, which may include in this case, chlorine and/or hydrogen, such as HCl, may be continuously removed from the process atmosphere, for example, by purging with an inert gas, such as helium, neon, argon, krypton, xenon, and/or nitrogen. In the case of TiCl4 and NH3, or a first precursor 111 including titanium, and the second precursor 112 including nitrogen, the first partial layer 101 may include titanium-nitride (TiN)
Purging may be again effected by using an inert gas. Pumping the process atmosphere may be effected by providing a vacuum down to a residual pressure, the residual pressure being, for example, below 10−2 mbar. During this stage a residual concentration in the process atmosphere of the first precursor 111, or of any other substance, may be allowable, such as a residual concentration which is below 5%. During this stage, a preliminary second partial layer 1020 of the functional layer is formed. The preliminary second partial layer 1020 may include the second precursor 112, such as ammonia. This may be effected during an atomic layer deposition (ALD) or a metal-organic atomic layer deposition (MOALD). During this stage, parts of the second precursor 112, such as nitrogen, may be incorporated into the first partial layer 101.
The third precursor 113 may include silicon, silane, silicon-chloride, silicon-tetra-chloride (SiCl4), dichlorosilane, tetraethylorthosilicate, aluminum, titanium, zirconium, hafnium, niobium, tantalum, tungsten, fluorine, chlorine, bromine, iodine, a metal-alkyl-amide, an aluminum-alkyl-amide, silicon-alkyl-amide, tetrakis[dimethylamino]silane, tris[dimethylamino]silane, di[dimethylamino]silane, trimethylaluminum, TMA, and/or a metal-organic (MO) precursor. Metal-alkyl-amides may include a tantalum-alkyl-amide, such as TAIMATA, TBTEMT, TBTDET, IPTEMT, or PDMAT, a zirconium-alkyl-amide, such as TDMAZ, TEMAZ, or TDEAZ, a hafnium-alkyl-amide, such as TDMAH, TEMAH, or TDEAH, or an aluminium-alkyl-amide.
The provision of the third precursor 113 may be effected during an atomic layer deposition (ALD) or a metal-organic atomic layer deposition (MOALD), and the third precursor 113 may react with components of the preliminary second partial layer 1020 to form a second partial layer 102 of the functional layer. The second partial layer 102 may include a composite being formed by the second precursor 112 and the third precursor 113. In the case of ammonia and silicon-tetra-chloride, the second partial layer 102 may include silicon-nitride (SiN, Si3N4) and/or titanium-silicon-nitride (TiSiN). Reaction products, which may comprise, in this case, chlorine and/or hydrogen such as HCl, may be continuously removed from the process atmosphere, for example, by purging with an inert gas
After the provision of the second partial layer 102 or after the provision of the third partial layer 103, the method may be continued with the formation of a further preliminary partial layer, a further second partial layer, and/or a further third partial layer, this formation being effected as has already been described in conjunction with
According to one embodiment, a deposition of titanium nitride, using a chemical vapor deposition process, employing titanium-tetra-chloride and ammonia, may be combined with an atomic layer deposition of silicon nitride, employing silicon-tetra-chloride and ammonia. In this way, the morphology, i.e. the roughness, the crystallinity and/or the texture of a titanium-nitride layer may be controlled by changing the number of intermediate silicon-nitride-deposition cycles. The thermal stability of the attained nitride, i.e. against surface oxidation and/or diffusion of oxygen and/or chlorine, may be controlled by changing the number of intermediate silicon-nitride deposition cycles.
Furthermore, it may be possible to conformally grow titanium-nitride and/or titanium-silicon-nitride onto a three-dimensional or topological feature, such as a trench, a step, a stack, a groove, a hole, a whisker, and/or a pillar, while keeping an optimized throughput and processes yield. Furthermore, it may be possible, to control the ratio of titanium to silicon in order to cover high aspect ratio structures, such as deep trenches or lean pillars. In this way, three-dimensional structures and features with an aspect ratio higher than 3 and/or higher than 10, may be covered conformal by a functional layer.
In addition to this, the content of chloride in a functional layer may be reduced, while still allowing for the desired physical and metallic or dielectric properties of the functional layer. The reduction of chlorine and/or other halogens may be of advantage, since halogens and/or precursors which include halogens are potentially hazardous substances, and are, in view of environmental aspects of the manufacturing process, to be reduced.
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.
