摘要:
A photolithography mask derivation process is provided for improving the overall planarity of interlevel dielectric deposited upon conductors formed by the derived photolithography mask. The photolithography mask is derived such that non-operational conductors are spaced a minimum distance from each other and from operational conductors to present a regular spaced arrangement of conductors upon which a dielectric layer can be deposited and readily planarized using, for example, chemical-mechanical polishing techniques. The resulting interlevel dielectric upper surface is globally planarized to an even elevational level across the entire semiconductor topography. The operational conductors are dissimilar from non-operational conductors in that the operational conductors are connected within a circuit path of an operational integrated circuit. Non-operational conductors are not connected within the integrated circuit path and generally are floating or are connected to a power supply. The non-operational conductors thereby do not contribute to the integrated circuit functionality other than to provide structural planarity to the overlying interlevel dielectric. The mask derivation process is applicable to either a metal interconnect photolithography mask or a polysilicon interconnect photolithography mask.
摘要:
A method for forming a multilevel interconnect structure having a globally planarized upper surface. Dielectrics are deposited upon a semiconductor to minimize pre-existing disparities in topographical height and to create an upper surface topography having a polish rate greater than that of lower regions. Subsequent chemical mechanical polishing produces a substantially planar surface.
摘要:
A dielectric material is provided having air gaps which form during dielectric deposition between interconnects. The dielectric is deposited in interconnect-spaced geometries which have certain aspect ratios and which are exposed at the bottom of the geometries to a hygroscopic dielectric. During deposition, the dielectric is forced along the sidewall of the spaced interconnects as a result of moisture ougasing from the hygroscopic dielectric. Over a period of time, a keyhole occurs with pile up accumulation (or cusping) at the corners of the spaced interconnects. By decreasing the deposition temperature in a subsequent step, outgasing is minimized, and deposition over the keyhole and upon the hygroscopic dielectric takes place. Keyhole coverage results in an air gap which is surrounded on all sides by the fill dielectric. Air gap between interconnects helps reduce permittivity of the overall dielectric structure, resulting in a lessening of the interconnect line-to-line capacitance.
摘要:
A dielectric material is provided having air gaps purposely formed within the dielectric. The dielectric is deposited, and air gaps formed, between respective interconnect lines. The geometries between interconnect lines is purposely controlled to achieve a large aspect ratio necessary to produce air gaps during CVD of the dielectric. Air gaps exist between interconnects to reduce the line-to-line capacitance, and thereby reduce the propagation delay associated with closely spaced interconnects.
摘要:
A subfield conductive layer is provided, wherein a conductive layer is implanted beneath and laterally adjacent a field dielectric. The subfield conductive layer is placed within the silicon substrate after the field dielectric is formed. The conductive layer represents a buried interconnect which resides between isolated devices. The buried interconnect, however, is formed using high energy ion implant through a field dielectric formed either by LOCOS or shallow trench isolation techniques. The buried interconnect, or conductive layer, resides and electrically connects source and drain regions of two isolated devices.
摘要:
An improved method for planarizing an interlevel dielectric comprising two chemical mechanical polish steps. After an interlevel dielectric containing a topographical valley between a pair of topographical peaks is formed, the dielectric is chemically-mechanically polished in a first polish step at a first force using a first polish pad having a first rigidity to round the sharp dielectric corners or edges that exist at the transition between the peaks and valleys. After the first polish step has rounded the edges, a second polish step is performed with a second polish pad of second rigidity. The second polish pad is more rigid than the first polish pad and the second force is greater than the first. The second polish steps uses a high viscosity slurry to reduce slurry turnover in the regions proximate to the dielectric valleys thereby reducing the chemical etching in the valleys and improving the planarization efficiency.
摘要:
An improved multilevel interconnect structure is provided. The interconnect structure includes pillars spaced from each other across a wafer. The pillars are placed between levels of interconnect or between an interconnect level and a semiconductor substrate. The pillars are spaced from each other by an air gap, such that each conductor within a level of interconnect is spaced by air from one another. Furthermore, each conductor within one level of interconnect is spaced by air from each conductor within another level of interconnect. Air gaps afford a smaller interlevel and intralevel capacitance within the multilevel interconnect structure, and a smaller parasitic capacitance value affords minimal propagation delay and cross-coupling noise of signals sent through the conductors. The air gaps are formed by dissolving a sacrificial dielectric, and the conductors are prevented from bending or warping in regions removed of sacrificial dielectric by employing anodization on not just the upper surfaces of each conductor, but the sidewalls as well. The upper and sidewall anodization provides a more rigid metal conductor structure than if merely the upper or sidewall surfaces were anodized. Accordingly, the pillars can be spaced further apart and yet provide all necessary support to the overlying conductors.
摘要:
A subfield conductive layer is provided, wherein a conductive layer is implanted beneath and laterally adjacent a field dielectric. The subfield conductive layer is placed within the silicon substrate after the field dielectric is formed. The conductive layer represents a buried interconnect which resides between isolated devices. The buried interconnect, however, is formed using high energy ion implant through a field dielectric formed either by LOCOS or shallow trench isolation techniques. The buried interconnect, or conductive layer, resides and electrically connects source and drain regions of two isolated devices.
摘要:
An isolation technique is provided for improving the overall planarity of isolation regions relative to adjacent active area silicon mesas. The isolation process results in a trench formed in field regions immediately adjacent the active regions. The trench, however, does not extend entirely across the field region. By preventing large area trenches, substantial dielectric fill material and the problems of subsequent planarization of that fill material is avoided. Accordingly, the present isolation technique does not require conventional fill dielectric normally associated with a shallow trench process. While it achieves the advantages of forming silicon mesas, the present process avoids having to rework dielectric surfaces in large area field regions using conventional sacrificial etchback, block masking and chemical-mechanical polishing. The improved isolation technique hereof utilizes trenches of minimal width etched into the silicon substrate at the periphery of field regions, leaving a field mesa. A field dielectric, preferably oxide, is formed upon the field mesa and fills trenches between the field mesa and active mesas, leaving a substantially planar field dielectric commensurate with the upper surface of adjacent active mesas.
摘要:
A interconnect structure is provided having a conductor with enhanced thickness. The conductor includes an upper portion and a lower portion, wherein the lower portion geometry is sufficient to increase the current-carrying capacity beyond that provided by the upper portion. The lower portion is formed by filling a trench within an upper dielectric region, and the upper portion is formed by selectively removing a conductive material from the upper dielectric surface except for regions directly above the lower portion. The upper and lower portions thereby form a conductor of enhanced cross-section which can be produced by modifying a via-etch mask, rather than having to reconfigure and/or move interconnect features formed by a metal mask.