Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
2002-01-23
2002-09-03
Tsai, H. Jey (Department: 2812)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S381000, C438S675000
Reexamination Certificate
active
06444517
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The invention relates to the fabrication of integrated circuit devices, and, more particularly, to a method for the creation of a high Q value spiral inductor by increasing the metal thickness of the inductor.
(2) Description of the Prior Art
Integrated Circuits (IC's) are typically formed in or on the surface of a semiconductor substrate whereby electrical circuit elements of the individual IC's are connected internally to the semiconductor surface on which the IC's are formed. IC's that are formed in or on the surface of a substrate are mostly active digital processing devices without therefrom however excluding analog processing devices. In addition, discrete passive components can be formed that ate functionally cooperative with active semiconductor devices and that may or may not have been formed using semiconductor devices technology techniques and equipment.
Semiconductor device performance improvements are largely achieved by reducing device dimensions. This trend of device miniaturization has progressed to where modern day devices are created with sub-micron device feature size. While this process has been a continuing trend for active semiconductor devices it has placed increased emphasis on miniaturization of discrete passive components that are required to function with the miniaturized active devices. To accommodate the requirements that are placed on further reductions of the dimensions of discrete passive components, the methods used and the designs of these components can be changed while another path of development has focused on using materials that provide improved performance of the discrete components. With respect to using more promising materials for the creation of discrete components in order to improve component performance, recent trends have focused on replacing conventional aluminum as the conductive medium with copper. As wire widths in integrated circuits continue to shrink, the electrical conductivity of the wiring material itself becomes increasingly more important. Thus, in this regard, aluminum, which has been the material of choice since the integrated circuit art began, is becoming less attractive than other better conductors such as copper, gold and silver. Copper does provide the advantages of improved conductivity and reliability but does as yet provide a challenge where a layer of copper must be etched using conventional methods of photolithography and reactive ion etching (RIE). This is due to the fact that copper does not readily form volatile species during the process of RIE. To circumvent these problems, other methods of creating interconnect lines using copper have been proposed such as depositing the copper patterns using methods of Chemical Vapor Deposition (CVD) of selective electroless plating. The composition of the deposited layer of metal, if the preferred element contained in the layer of metal is copper, can be changed by the addition of other metallic substances in order to improve deposition results. The use of copper has recently found increased application in the creation of discrete components, most notably of discrete inductors that are formed above the surface of a semiconductor substrate. Copper has only recently gained more attention as an interconnect metal. Copper is of relatively low cost and low resistivity. Copper however also has a relatively large diffusion coefficient into surrounding dielectrics such as silicon dioxide and silicon. Copper has the additional disadvantage of being readily oxidized at relatively low temperatures, conventional photoresist processing can therefore not be used for copper because the photoresist needs to be removed at the end of the process by heating it in a highly oxidized environment. Copper from an electrical interconnect may diffuse into the surrounding layer of dielectric (such as a layer of silicon dioxide), causing the dielectric to become conductive while at the same time decreasing the dielectric strength of the silicon dioxide layer. Copper interconnects are therefore typically encapsulated by at least one diffusion barrier layer in order to prevent diffusion into the surrounding silicon dioxide layer. Silicon nitride can serve as a diffusion barrier to copper, but the prior art teaches that the interconnects should not lie on a silicon nitride layer because it has a high dielectric constant compared with silicon dioxide. The high dielectric constant causes an undesired increase in capacitance between the interconnect and the substrate. Copper further has low adhesive strength to various insulating layers, and it is inherently difficult to mask and etch a blanket copper layer into intricate circuit structures. Copper is also more resistant than aluminum to electromigration, a quality that grows in importance as wire widths decrease.
The invention addresses the creation of an inductor on the surface of a semiconductor substrate using damascene processes. The application of the damascene process continues to gain wider attention for this application, most notably in the process of copper metalization due to the difficulty of copper deposition where a damascene plug penetrates deep into very small, sub-half micron, Ultra Large Scale Integrated (ULSI) devices. While copper has become important for the creation of multilevel interconnections, copper lines frequently show damage after CMP and clean. This in turn causes problems with planarization of subsequent layers that are deposited over the copper lines, since these layers may now be deposited on a surface of poor planarity. Isolated copper lines or copper lines that are adjacent to open fields are susceptible to damage. Poor copper gap fill together with subsequent problems of etching and planarization are suspected as the root causes for these damages. Where over-polish is required, the problem of damaged copper lines becomes even more severe.
One of the major challenges that must be faced in the creation of discrete passive components (using digital processing procedures and equipment) is that these components are potentially large in size and can therefore not readily be integrated into digital devices that typically have feature sizes approaching the sub-micron range. The main components that offer this challenge are capacitors and inductors, since both these components can be of considerable size.
Inductors can for instance be applied, concurrent with digital processing capabilities, in the field of modern mobile communication that makes use of compact high-frequency equipment. Continued improvements in the performance characteristics of this equipment has been achieved. Further improvements will place continued emphasis on lowering the power consumption of the equipment, on reducing the size of the equipment, on increasing the frequency of the applications and on creating low noise levels. One of the main applications of semiconductor devices in the field of mobile communication is the creation of Radio Frequency (RF) amplifiers. RF amplifiers contain a number of standard components, a major function of a typical RF amplifier is a tuned circuit that contains inductive and capacitive components. Tuned circuits form, dependent on and determined by the values of their inductive and capacitive components, an impedance that is frequency dependent. The tuned circuit typically presents either a high or a low impedance for signals of a certain frequency. The tuned circuit can therefore either reject or pass and further amplify components of an analog signal, based on the frequency of that component. The tuned circuit can in this manner be used as a filter to filter out or remove signals of certain frequencies or to remove noise from a circuit configuration that is aimed at processing analog signals. The tuned circuit can also be used to form a high electrical impedance by using the LC resonance of the circuit and to thereby counteract the effect of parasitic capacitances that are part of a circuit. One of the problems that is encountered when cr
Chen Chao-Cheng
Hsu Heng-Ming
Huang Liang-Kun
Ma Ssu-Pin
Tsai Chaochieh
Ackerman Stephen B.
Saile George O.
Taiwan Semiconductor Manufacturing Company
Tsai H. Jey
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