US 20060180895Al (19) United States (12) Patent Application Publication (10) Pub. No.: US 2006/0180895 A1 Chen et al. (43) Pub. Date: Aug. 17, 2006 (54) CAPACITOR DEVICE WITH VERTICALLY (21) Appl. No.: 11/055,933 ARRANGED CAPACITOR REGIONS OF VARIOUS KINDS (22) Filed: Feb. 11, 2005 (75) Inventors: Yueh-You Chen, Hsin-Chu City (TW); Publication Classi?cation Chung-Long Chang, Dou-Liu city (TW); Chih-Ping Chao, Chu-Dong (51) Int. Cl. Town (TW); Chun-Hong Chen, Jhubei H01L 29/93 (2006.01) City (TW) (52) U.S. Cl. .......................................... .. 257/595; 257/E2l Correspondence Address: (57) ABSTRACT DUANE MORRIS, LLP IP DEPARTMENT A capacitor device selectively combines MOM, MIM and 30 SOUTH 17TH STREET varactor regions in the same layout area of an IC. TWo or PHILADELPHIA, PA 19103-4196 (US) more types of capacitor regions arranged vertically on a substrate to form the capacitor device. This increase the (73) Assignee: Taiwan Semiconductor Manufacturing capacitance per unit of the capacitor device, Without occu Company, Ltd. pying an extra layout area. 100“ 168\A166\1::: 1:1 162 { 164C 1:: . 160 158, F I /_\~ ’/'_‘\ 130 Bi- - + - +--E6_,154 /\_ A/A\ 128 i. - + - +--?, 152 122 ' 134 . ,/—\ 142 126 \_/—'—~ . + .. +_-\_, 150 /\'_ ‘/_\ 4 124 i. + - +--—2, 148 120% 118/1- ] 116f 108 112 112 104 10s \ p — /_/ 106 _ m _ 114 l_/114 110 Patent Application Publication Aug. 17, 2006 Sheet 2 0f 2 US 2006/0180895 A1 200“ - + - + + - + - - + - + + - + - FIG. 2 300% 316% + ' + 314“ 312% + + 310v“ ' 308 “w - + - + 306\___ 304“ + + FIG. 3 US 2006/0180895 A1 Aug. 17,2006 CAPACITOR DEVICE WITH VERTICALLY SUMMARY ARRANGED CAPACITOR REGIONS OF VARIOUS KINDS [0007] In vieW of the foregoing, the folloWing provides a capacitor device selectively combining MOM, MIM and BACKGROUND varactor regions in the same layout area of an IC. In one [0001] The present invention relates generally to inte embodiment of the present invention, tWo or more types of grated circuit (IC) designs, and more particularly to a capacitor regions are arranged vertically on a substrate to capacitor device With a metal-insulator-metal (MIM) capaci form a capacitor device. This increase the capacitance per tor region, metal-oxide-metal (MOM) capacitor region, or unit of the capacitor device, Without occupying an extra varactor region vertically arranged on the same layout area. layout area. [0002] The construction of passive electronic circuit ele [0008] The construction and method of operation of the ments, such as capacitors, on an IC can be tedious, time invention, hoWever, together With additional objects and consuming, and costly. It is therefore important to assemble advantages thereof Will be best understood from the folloW such IC elements using the processes, materials, and designs ing description of speci?c embodiments When read in con that are relevant to the technology and that are already in nection With the accompanying draWings. production. BRIEF DESCRIPTION OF THE DRAWINGS [0003] Capacitors occur naturally, Whether intended, or not. Such capacitors can be useful. Active IC elements, such [0009] FIG. 1 illustrates a capacitor device, in accordance as bipolar and metal-oxide-semiconductor (MOS) transis With one embodiment of the present invention. tors, and some resistors contain electrical junctions With capacitance. A depletion region of an electrical junction is, [0010] FIG. 2 illustrates an alternative MOM capacitor by nature, a small parallel plate capacitor. That capacitor can region of the capacitor device, in accordance With the embodiment of the invention. be used as a ?xed-value capacitor, or it can be used as a variable capacitor, since its value changes as the voltage [0011] FIG. 3 illustrates another alternative MOM capaci applied to the junction changes. Passive IC elements, such as tor region of the capacitor device, in accordance With the polycrystalline silicon (polysilicon) and metal lines, have embodiment of the invention. inherent capacitance, With respect to each other and to any other conductors. DESCRIPTION [0004] The effort of a designer can be to use available [0012] The folloWing Will provide a detailed description of characteristics of IC elements. The dif?culty With such effort a capacitor device selectively combining MIM, MOM and is that the resulting structures exhibit capacitance values varactor regions in the same layout area of an IC. It is only on the order of femtofarads/micron squared. Achieving understood that different capacitor regions can be used in functional capacitance values in an IC element requires advantageous combinations in mixed signal and/or radio structures that typically are much larger than the active frequency (RF) circuits. elements, especially When used in mixed signal and/or radio frequency (RF) circuits. This imbalance is uneconomical, [0013] Several capacitor structures are in use in ICs. Each since it forces the circuit designer to dedicated space for one has a characteristic capacitance value per square micron capacitors and produce IC chips that are too large. The (u). A typical MIM capacitor offers about 0.5 femtofarad/p.2 designer can choose among several structural types of (fF/u2). Atypical MOM capacitor offers about 0.15 fF/p.2 per capacitors, but no one type offers a convenient balance of layer. A variable capacitor, or a varactor, offers about 1 to 6 performance and space economy. fF/u2. Different capacitor structures can be used in combi nations in mixed signal and/or RF circuits. This invention [0005] In one example, the voltage-variable capacitance of provides a capacitor device that includes tWo or more an electrical junction can be applied in the construction of a different types of capacitors, such as MIM capacitors, MOM variable capacitor, or a varactor. In another example, the capacitors and varactors, in a vertical arrangement in the dual-damascene techniques typically used With copper mul same layout area. This increases the capacitance value per tilevel interconnection metalliZation on ICs can be used to unit Without occupying layout areas more than a conven construct stacks of copper-?lled vias and trenches. TWo or tional MIM capacitor, MOM capacitor or varactor Would do. more such copper-?lled vias or trenches, separated by oxide dielectrics, form a capacitor, Which is called a MOM capaci [0014] FIG. 1 illustrates a capacitor device 100 in accor tor. This MOM capacitor requires a complex design, but the dance With one embodiment of the present invention. As Will form is ef?cient and the process steps required are usually be evident, the capacitor device 100 comprises three capaci already involved in the a standard semiconductor device tor regions, all of Which are understood to be constructed in fabrication process. In yet another example, simple horiZon the same layout area of an IC. It is noteworthy that While, in tal parallel plates of metal, separated by dielectrics, form a this embodiment, the capacitor device 100 includes three capacitor, Which is called a MIM capacitor. The horizontal capacitor regions, only tWo are able to increase the capaci form of this MIM capacitor occupies relatively more lateral tance per unit, according to the present invention. For layout space, but is simple to construct. example, a combination of the capacitor regions can be varactor and MOM capacitor regions, MOM and MIM [0006] Since a single type of capacitor does not alWays capacitor regions, or MIM and varactor capacitor regions. provide suf?cient capacitance per unit, it is desirable in the art of integrated circuit designs that additional devices are [0015] A semiconductor P-type substrate 102 is a host to provided to combine various types of capacitors in the same a varactor region 104 having at least one varactor. An active layout area for increasing the capacitance per unit of the area is enclosed by isolation structures 106, such as a same. shalloW trench isolation (STI) or local oxidation of silicon. US 2006/0180895 A1 Aug. 17,2006 A MOS gate 108 is deposited on a MOS gate dielectric layer [0018] Above the MOM capacitor region 122 is a dielec 110. The gate 108 may be made of poly-silicon or metal, tric layer 156, Which may be made from the same candidate including, but not limited to, W, Al, AlCu, Cu, Ti, TiSi2, Co, materials as the dielectric layer 120 or 116. Above the CoSi2, Ni, NiSi, TiN, TiW, or TaN. The gate dielectric layer dielectric layer 156 is a metal shielding layer 158 that acts 110 may be made of a material including, but not limited to, as a shield to separate any capacitor structure thereabove Si3N4, nitrided oxide, Hf oxide, A12O5, Ta2O5, metal oxide. from the capacitance of the MOM capacitor region 122 or TWo N+ regions 112, as a diffused source and drain, are any other semiconductor structures therebeloW. The metal disposed in the substrate 102, underneath the MOS gate 108 shielding layer 158 may be made of a material including, but and betWeen the isolation structures 106. Electrical junctions not limited to, Cu, AlCu, Ag, and Au. Above the metal 114, betWeen the N+ regions 112 and the P-type substrate shielding layer 158 is a dielectric layer 160, Which may be 102, have capacitance relative to the MOS gate 108. As the made from the same candidate materials as the dielectric bias on the electrical junctions 114 and the bias on the MOS layer 120, 116 or 156. Above the metal shielding layer 158 gate 108 change, the Width and area of the depletion region and the dielectric layer 160 is a MIM capacitor region 162. under the MOS gate 108 also changes, thereby further The MIM capacitor region 162 having one or more MIM changing the capacitance of the varactor region 104. It is capacitors is constructed of simple horizontal ?at patterned note Worthy that the above-described MOS capacitor is only metal plates 164 and 166 separated by a dielectric layer 168.