TWI297930B - Phase change memory cell with vacuum spacer - Google Patents

Description

-1297930 IX. Invention Description: [Party of Joint Research Contract] [0001] New York International Commercial Machinery Corporation, Taiwan Wanghong International Co., Ltd. and Infineon Technologies A.G. are parties to the joint research contract. TECHNICAL FIELD OF THE INVENTION [0(8)2] The present invention relates to non-volatile memory elements, and more particularly to such memory elements using one-phase variable memory elements. [Prior Art] [0003] Phase change-based memory materials have been widely used for reading and writing optical discs, and these materials have also been gradually used in computer memory elements. These materials have at least two solid phases, usually amorphous and generally crystalline. Laser pulses are used to read and write optical discs to switch between = states and to read the optical properties of the material after phase changes, while current pulses are used in the same way in computer memory components. [〇〇〇4] Phase change-based memory materials, such as Chalcogenide and its materials, can also be changed by applying a current suitable for operation of the integrated circuit. 2~苴This is usually amorphous The state has a higher resistance than the normally crystalline state, which can be used to quickly sense the data. This property is advantageous as a programmable resistance material for non-volatile volts and life circuits, which can read data in a random manner. ^ 〇5] The phase change from the amorphous state to the crystalline state is usually a lower current stay and the phase change from the crystalline state to the junction amorphous state, referred to herein as reset, 5 MXIC P940172 final . 1297930

After the I i ^ phased material is rapidly cooled, the phase change is changed for the phase change. The structure of the phase change can be stabilized in this amorphous state. Generally, the reset current of the healthy H crystal state is changed to the junction amorphous state is 2, and 4 is reduced by the mechanism of the shrinking Yang axis (4), the phase and the electric phase, and the phase change with the phase + Reset the required reset current value, so the gate ~4 X can be reached by means of a smaller current through this phase change material component

[0006] The direction of development has been to form fine pores in the integrated circuit structure and to fill the fine pores with J/li programmable resistance material. The patents for the development of small pores are: the blood is added to the tearing year ^ β η day is approved in the United States, Li 5,687,112, and the invention name is "multiple-bit single unit s-remembering elements with pointed contact windows" The patent of Zah〇rik et al. was approved on August 4, 1998 by US Patent No. 5,789,277, entitled "Method of Manufacturing Chalcogenide (IV) Memory Element", Doan et al. U.S. Patent No. 6,150,253, entitled "Controllable Bidirectional Phase Change Semiconductor Memory Element and Its Manufacturing Method", and Reinberg, in July 1999, obtained the US Patent No. 5,920,788 For example, chalcogenide memory cells with many chalcogenide electrodes'. [0007] When using conventional phase change memory structures, a particular heat transfer problem can occur in this traditional design. The prior art teaches the use of a metal electrode on both sides of the phase change memory cell, and the size of the metal electrode corresponds to the size of the phase change member. Such an electrode would constitute a thermal conductor. The high thermal conductivity of the metal will quickly change the tropics from this phase of the material. Because this phase change is caused by heat, this heat transfer effect will result in the need for higher currents to produce the desired phase. 6 MXIC Ρ 940172 final 1297930 [0008] A way to solve this heat conduction effect problem can be found in U.S. Patent No. 6,815,704, entitled "Automatic Alignment of Air Gap Thermal Insulation of Nanoscale Chalcogenide Electronic (NICE) Random Storage Taking memory (RAM), which reveals an insulating ^ memory cell. This structure and its manufacturing process are often complicated, but the minimum current flow in this sigma element cannot be achieved. [0009] Therefore, it is necessary To develop a memory cell structure with a small size and low reset current, this structure must solve the heat conduction problem, and its manufacturing method must meet the strict process variation requirements required for high-level memory components. More need to provide a structure And the manufacturing method thereof can be simultaneously applied to the manufacture of peripheral circuits in the same wafer. [Invention] [0010] The present invention An important object is to provide a memory device comprising a first electrode and a second electrical component that are separated from a substrate. A phase change element is separated from the first electrode and the second electrode component. This phase changes „two segments, each segment being in contact with one of the _ members. The positions of the two segments === are connected such that the connected position has a cross-sectional area smaller than that of the phase change portion. The electrode, the substrate and the phase change element define a gas chamber. [Embodiment] [0016] The following is a detailed description of the purpose of the section of the present description. t structured method. SUMMARY OF THE INVENTION The scope and advantages of the patents, embodiments, and features of the present invention will be fully understood by the following MXIC P940172 final 7 1297930. As shown in Fig. 1, there is shown a basic layout of memory elements in accordance with one phase of the present invention. As is well known in the art, a phase change random access memory (pCRAM) cell comprises a phase change element 20 comprised of a material having two solid phases. Preferably, this material can be changed from amorphous to crystalline under the application of a suitable current pulse and can be returned to amorphous. The general operating principles of this memory cell can be found in the references previously mentioned, and the details of the operation of the phase change material are detailed below. ^ [〇〇18] The structure and function of this memory cell will be described first, followed by a detailed description of its process. Preferably, the cells are formed on a dielectric layer or substrate 12, preferably containing ruthenium oxide or a conventional alternative such as a polymeric material, tantalum nitride or other dielectric filler material. In one embodiment, the dielectric layer includes a relatively good thermal and electrical insulating property to provide thermal and electrical insulation. The two electrodes 14 and 16, preferably formed of a heat resistant metal such as tungsten, are formed on the dielectric layer. Other heat resistant metals may also be used, including titanium (Ti), indium (M〇), ^ (A1), group (iv), copper (Cu), platinum (Pt), silver (ir), lanthanum (La), nickel ( Ni) and ruthenium (ru), as well as oxides or nitrides of these metals. The two electrode systems are slightly separated by a distance of between about 30 and 7 nanometers, preferably about 50 nanometers. It must be noted that the direction extends upward from the bottom of the drawing, the direction is called the vertical direction, and the direction of the two sides is called the lateral direction or the horizontal direction, for the convenience of explanation. It does not affect the actual direction of the actual component during manufacture or operation. [0019] Phase change element 20 is typically a phase change material comprising a strip of strips between the two electrodes and bridging the two electrodes. The width of this element is approximately between 10 and 3 nanometers ★, preferably 20 nanometers, and the thickness is approximately 1 nanometer. The dielectric fill material % (see Figure 4h) is located above the electrode and the phase change element. The dielectric filler MXICP940172 final 8 ‘1297930 is preferably the same material as the substrate 12, or is selected from a group similar thereto. This material should have a thermal conductivity lower than that of the oxidized stone, or less than the K*sec side. Such a dielectric filling material includes a low dielectric constant material thermal insulating material such as a combination of Shi Xi (Si), carbon (C), oxygen (0), fluorine (F) money (H) and the like. The thermal insulating material used as the dielectric filler material 26 includes, for example, sic〇H, polyamidamine, polyamine, and a compound. Other materials that can be used as dielectric fillers include oxyfluoride, silsesquioxane, p〇iyaryiene ether, parylene, fluoropolymer, Fluorinated amorphous carbon, diamond-like carbon, porous oxidized oxide, • Mesoporous (mes〇P〇r〇us) oxidized oxide, porous sesquioxane, porous polyimide and porosity Cycloalkenyl ether. The dielectric fill material fills a gap between the two electrodes, so that the two electrodes and the two dielectric layers define a vacuum sidewall between the two electrodes. [0020] This phase change element 20 can be selected from the group of groups that preferably comprise Chalcogenide materials. The chalcogenide material includes any one of the elements of the VI group of the four chemical periodic tables of oxygen (〇), sulfur (S), zeshi (Se) and yttrium (Te). Chalcogenides include chalcogenide groups and a plurality of compounds having a positively charged or substituted group. Chalcogenide alloys include combinations of chalcogenides with other materials such as transition metals. Chalcogenides typically comprise one or more other elements selected from the sixth block of the Periodic Table of the Elements, such as germanium (Ge) and tin (Sn). Generally, the chalcogenide alloy includes a combination of one or more of antimony (Sb), gallium (Ga), indium (In), and silver (Ag). Many memory materials based on phase change have been exposed in the technical literature, including Ga/sb.

In/Sb, In/Se, Sb/Te, Ge/Te, Ge/Sb/Te, In/Sb/Te, Ga/Se/Te, Sn/Sb/Te, In/Sb/Ge, Ag/In/ Sb/Te, Ge/Sn/Sb/Te, Ge/Sb/Se/Te and Te/Ge/Sb/S alloys. There are many alloy compositions that can be used in the Ge/Sb/Te alloy group. The composition is characterized by TeaGebSb1(KKa+b), where a and b represent atomic percentages of the total atomic number of constituent elements 9 MXIC P940172 final 1297930. The researchers have pointed out that the most useful alloy is that the average concentration of D6 in the already deposited material is well below 70%, typically below about 6% and generally as low as about 23°. It is as high as about 58% Te, and most preferably about 48% to 58% Te. The concentration of Ge exceeds about 5%, and the Ge concentration in the average material ranges from about 8% to about 3%, and generally remains below 50%. Most preferably, the concentration of Ge is from about 8% to about 4%. The remaining major constituent elements in the composition are Sb. (Ovshinsky '112 patent lo-u column). Alloys that are particularly recognized by other researchers include Ge2Sb2Te5, GeSb2Te4 and GeSb4Te7 (Noboru).

Yamada, "The possibility of Ge_Sb-Te phase change discs at high data speed records" Yang Zheng 13109|28-37 (1997). More generally, transition metals such as chromium (Cr) 'iron (Fe), Nickel (Ni), niobium (Ni), |e(Pd), turn (Pt) and mixtures or alloys can form a phase change alloy with Ge/Sb/Te that can be programmed with insulating properties. Specific examples of useful memory materials Please refer to 〇vshinky, 112, columns 11-13, which is incorporated herein by reference. [0021] The phase change material can be in the active channel region of the cell in accordance with its positional order. The first structural state of the crystalline state is switched between a second structural state that is a generally crystalline solid state. These phase change materials are at least bi-directionally stable (bis), which is referred to herein as a relatively unordered structure, Single crystals are more disorderly and have detectable characteristics, such as higher electrical insulation than crystalline states. Crystallinity, as used herein, refers to a fairly orderly structure that is more orderly than amorphous structures and has The characteristics of the detection are, for example, lower electrical insulation than the amorphous state. Typically, phase change materials can be electrically switched across different detectable states to span the spectrum between fully amorphous and meta-crystalline states. Other material characteristics affected by changes between amorphous and crystalline phases include atoms. Sequence, free electron density and activation energy. Materials can be converted to different solid phases or converted to two or more solid phases to provide a gray zone between completely amorphous and fully crystalline states. It can also be changed accordingly according to 10 MXIC P940172 final 1297930. [0022] The phase change material can be changed from one phase state to another phase by applying an electrical pulse. It has been observed that a shorter higher amplitude pulse tends to cause phase change. The material becomes generally amorphous and is generally referred to as a reset pulse. Longer, lower amplitude pulses tend to cause the phase change material to become a normally crystalline state, commonly referred to as a programmed pulse. The energy in the shorter, higher amplitude pulse is high enough to The bond of the crystalline structure breaks and is short enough to prevent the atoms from re-arranging into a crystalline state. The conditions suitable for the pulse can be based on experience. The law judges that without undue experimentation, it can find the conditions that apply to a particular phase change material _ and component structure. In the following description, the phase change material is called GST, and it should be understood that other types of phase change materials can also be used. The material used to implement the computer memory described herein is Ge2Sb2Te5. [0023] Other programmable resistive memory materials can also be used in other embodiments of the invention, including N-type doped phase change material (GST), GexSbb, Or other different crystal phase changes can be used to determine the resistance value; PrxCayMn〇3, PrSrMnO, ZrOx or other available electronic pulses to change the resistance state; TCQN, PCBM, TCNQ_PC: BM, Cu-TCNQ, Ag-TCNQ, C60-TCNQ, TCNQ is doped with other metals, or • Any other polymeric material has a two-phase stable or multi-directional stable resistance state that can be controlled by electronic pulses. [0024] Referring to FIG. 2, a more detailed illustration of the memory cells of the present invention shows that the phase change element actually comprises two segments 2〇a and 2〇b, each segment having a circular shape. End point. The two sections are connected above the vacuum side wall 24 such that the cross-sectional area of the contact area is less than the cross-sectional area of other areas of the phase change element. Regarding the formation of this element, this will be clarified in the description below. [0025] Referring to Figure 3, the operation of the memory cells of the present invention is shown. Shown in the figure, the operating current flowing from the electrode 14, indicated by the arrow j, follows the arrow into the MXIC P940172 final 11 1297930 phase change elements 20a and 20b, and finally flows out of the electrode 16. It must be noted that the direction of the electric grip is only arbitrarily selected for the sake of illustration, and may be the opposite direction in actual operation. P026] As shown in the figure, the electric field and current density in the two-phase change element are relatively low in the contact region 25 where the one-phase change element meets. Contact area = The smaller cross-sectional area produces higher current and electrical energy than other areas. As a result, more heat is generated in the contact area than in other areas of the phase change element, and phase changes occur only in this contact area (as in the dark areas in the figure). [〇〇2η In addition, the low thermal conductivity of the vacuum sidewalls 24 reduces the conduction of heat in the contact zone j, effectively increasing the heat generated by the unit surface of the machined material. The thermal insulation properties of this contact area allow the memory to be designed to require less current than the system, which also reduces the size of the memory cells themselves. [=8Bu how to make money according to this issue--The production of machined navigation parts ::Figure: Displayed from the 3rd picture. For the sake of brevity, 'only the phase piece and its related features are shown in the figure, and the electrode and its associated junction t in Figure 1 are not shown. The electrode structure and the phase change structure are combined. _本(四)份This memory person can lightly (4) how to apply the features taught by the present invention to traditional processes and techniques. Activity 1 ® (4) - phase change record 4: = t map 'shown in the ^ _ his diagram. The first step, at the beginning of the first step, is preferably to introduce the first substrate, such as two, and then to be initially patterned and _, preferably using industry-independent lithography techniques to reduce the central portion of the overall substrate. The factory degree of the upper element 13 body is only retained as shown in Figure 4b. MXIC P940172 final 12 1297930 [0029] These two electrode elements will be formed in the next two steps. The result is shown as depositing electrode material 15 (described above) on the substrate, the thickness of which is greater than the upper element 13 of the central portion of the substrate. The electrode material is then planarized, preferably using a chemical mechanical polishing (CMP) technique, until a thickness can cause the upper half of the upper element I) of the central portion of the substrate to be exposed, as shown in Fig. 4d. This | insect is engraved to form two electrodes 14 and 16. [0030] A selective etching process is used to remove the material of the upper element 13, leaving only the interelectrode space 23 as shown in Fig. 4e. Here, it is preferable to use a wet residue process, preferably buffered hydrofluoric acid, assuming that the dielectric substance is oxidized _ 矽 '. An alternative method is to use a dry name, such as a fluoride-based plasma button, which can also be used. It must be understood that different materials must use different residual formulations. The result of this step is the creation of two separate electrodes 14 and 16 over the substrate with interelectrode space therebetween. [0031] Figure 4f shows the deposition of this phase change element 20 to form this memory cell. This deposition is preferably carried out using a sputtering process. This makes it possible to form a central portion of a smaller cross-sectional area, as shown in the close view of Figure 4g, in which deposition is in progress. As is well known to those skilled in the art, a process of extruding or producing a surface edge bend as shown in the figure. Extra growth of the material will cause deposition from both sides until the last two sides are in contact above the center of the gap. The newly deposited material will bind to the previously deposited material, so the material will begin to deposit from both sides until both sides contact the center of the gap, as shown. The contact of the two sides causes the closing of the space 23 between the electrodes, thus defining the vacuum side wall 24. Finally, the phase change element 20 is tailored to a suitable size so that it does not exceed the width of the electrode and additional dielectric fill material 26 is deposited as shown in Figure 4h. This material encloses the vacuum side wall 24 such that the element remains a vacuum therebetween. 13 MXIC P940172 final 1297930 [0032] It must be understood that these illustrations are only illustrative of the ideal situation. Fig. 5 is a more realistic situation, showing that the edges of the electrodes 14 and 16 are not vertically upward, but that the side-cutting occurs when the upper element 13 is etched to form the vacuum side wall 24. In addition, there will be residual; some phase change elements are at the bottom of the vacuum sidewalls' but these small phase change elements do not affect the operation of this component. Although the present invention has been described with reference to the preferred embodiments, it is understood that the present invention is not limited by the detailed description. Alternatives and modifications are suggested in the first place, and other methods and modifications will be considered by those skilled in the art. In particular, according to the structure and method of the present invention, all of the embodiments having substantially the same as the present invention are substantially the same as the present invention. Therefore, all such alternatives and modifications are intended to be within the scope of the invention as defined by the appended claims and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing a phase change memory element according to an embodiment of the present invention; _2] Fig. 2 is a schematic sectional view showing a domain chemical fiber element according to the present invention; 2, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4 Figure 5 is a phase change memory element of the present invention as shown in Figure 1. MXIC P940172 final 14 1297930 [Key component symbol description] ίο : Memory cell 12 : Substrate 13 : Upper element 14, 16 : Electrode 20 , 20a , 20b : Phase change element 23 : Interelectrode space 24 : Vacuum side wall • 25 : Contact Area 26: Dielectric Filler

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Claims (1)

1297930 X. Patent application scope: 1. A memory component comprising: a first electrode and a second electrode member separated from a substrate; - a phase change element 'separating from the first electrode and the second electrode Space between the two, wherein: the phase change element comprises two segments, each segment being in contact with one of the electrode members, connected at a position between the electrodes, such that the connected position has a smaller than the phase change a cross-sectional area of the remainder of the element; and the electrode, the substrate, and the phase change element define a gas chamber. 2. For the purpose of applying for the core element described in Item 1 of the special design, the change element of the towel axis includes a combination of 锗 (Ge), 锑 (Sb), and pound (Te). 3. The memory component of claim 2, wherein the phase change element comprises two or more selected from the group consisting of germanium (Ge), germanium (sb), pound (Te), selenium, and indium. (In) > lt(Ti) ^ ^(〇a) ^ ^(Bi) > ^(Sn) > ^(Cu) ^ 4ε(Ρφ > Λ • Silver (Ag), sulfur (5), and *( Au) The material combination of the family and the sheep. 4. The memory element as described in the scope of the patent application, including the dielectric filler material in contact with the electrode member and the Wei_phase change element, is more enclosed a gas chamber defined by the electrode member and the phase change element. 5. A method of manufacturing a memory device, the method comprising: providing a substrate; and forming two electrodes on the substrate, the two electrodes By dividing the space between the electrodes MXICP940172 final 16 129793 ο ' I form a phase change memory element over the two electrodes, comprising the steps of: starting to deposit a phase change material over the two electrodes, such that the phase changes Material extending into the space between the electrodes; Μ continuing the deposition until the two materials deposited in the two are empty between the electrodes They are connected to each other to define a vacuum side wall. 6. The method of claim 5, wherein the phase comprises a combination of germanium (Ge), germanium (Sb), and recording (Te). The method of claim 5, wherein the phase change memory element comprises two or more selected from the group consisting of germanium (Ge), recorded (sb), recorded (Te), and ), marriage (10), titanium (9), gallium (Ga), transition, tin (Sn), copper (Cu), (4), wrong (four), silver _, sulfur (S) and gold (Au) combination. 8. The method of claim 5, further comprising depositing a dielectric filler material φ layer over the structure formed by the electrode and the phase change memory element. MXIC P940172 final 17