Abstract: An interconnecting post for mounting a microelectronic device such as an integral circuit chip is fabricated with generally uniform cross-section, by forming a first layer of positive photoresist on a substrate, soft-baking that first layer and exposing it for a short time with a wide-apertured mask or simply a UV blank flood exposure. Without developing the first layer, a second layer of positive resist is then applied over the first layer, soft-baked, and then exposed with a narrow-apertured mask. During the soft-baking of the second layer, some of its activator in the photoresist compound diffuses into the exposed portion of the first layer and modifies its solubility in such a way that, when the layers are subsequently developed, the developer partially undercuts the unexposed portion of the first layer to form in the photoresist an opening of generally uniform cross-section. This opening can then be filled by plating to produce a strong, integral interconnect post.

Abstract: Methods of planarizing structures formed on the surfaces of substrates and wafers are disclosed. The methods form a planarizing layer over the surface and the structures, or the locations where the structures are to be formed, such that the top surface of the layer has low areas between the locations of the structures, and such that the low areas lie substantially within a plane which is below the tops of the structures. A polish-stop layer is then formed over the low areas of the planarizing layer, the polish-stop layer being more resistant to polishing than the planarizing layer and, preferably, the structures. The resulting surface is then polished. The polishing may be accomplished by, for example, standard mechanical polishing, and chemical-mechanical polishing.

Abstract: Methods of wet etching through a silicon substrate using composite etch-stop layers are disclosed. In one embodiment, the composite etch stop comprises a layer of silicon dioxide and a layer of polyimide.

Abstract: Novel structures for capacitors which are capable of withstanding heat treatments to at least 400.degree. C. while providing low defect densities and low electrical series resistance in its electrodes are disclosed. In one embodiment of the present invention, a capacitor structure includes a bottom capacitor electrode formed of a first sub-layer of aluminum, a second sub-layer of tantalum nitride, and a third sub-layer of tantalum. The capacitor structure further includes a sputtered dielectric layer of tantalum pentoxide over the tantalum sub-layer of the bottom electrode. The resulting structure is anodized such that the underlying tantalum layer is fully anodized, and preferably such that a portion of the tantalum nitride layer is converted to a tantalum oxy-nitride.

Abstract: An interposer substrate for mounting an integrated circuit chip to a substrate, and method of making the same, are shown. The interposer substrate comprises power supply paths and controlled impedance signal paths that are substantially isolated from each other. Power supply is routed though rigid segments and signals are routed though a thin film flexible connector that runs from the upper surface of the interposer substrate to the lower surface. Bypass capacitance is incorporated into the interposer substrate and connected to the power supply so that it is positioned very close to the integrated circuit chip. The interposer may be fabricated by forming a multilayered thin film structure including the signal paths over a rigid substrate having vias formed therein, removing the central portion of the substrate leaving the two end segments, and folding and joining the end segments such that the vias are connected.

Abstract: Methods of forming patterns in photo-sensitive resist layers with high aspect ratio features are described. The photosensitive layer is patterned exposed to actinic radiation and thereafter developed. For high aspect ratio patterns, the inventors have often observed a residue of resist material at the bottom of such features, and that this residue interferes with subsequent processing, such as filling the pattern with metal by a plating operation. To remove this residue, the patterned locations of the resist are exposed to a low dose of low-energy electron beam radiation, preferably having energy of less than 6 KeV and dosage of less than 200 .mu.C/cm.sup.2. After the electron beam exposure, the aperture is again exposed to a developer solution, which may be of the same composition as the developer initially used to develop the patterns.

Abstract: A multichip module substrate for use in a three-dimensional multichip module, and methods of making the same, are disclosed. The substrate comprises a thin film structure, for routing signals to and from integrated circuit chips, formed over a rigid support base. Apertures are formed in the support base exposing the underside of the thin film structure, thereby allowing high density connectors to be mounted on both surfaces of the thin film structure, greatly enhancing the ability to communicate signals between adjacent substrates in the chip module. This avoids the need to route the signals either through the rigid support base or to the edges of the thin film structure. Power and ground, which do not require a high connection density, are routed in low impedance paths through the support base. Preferably, the thin film structure is made of alternating layers of patterned metal, such as copper, and a low dielectric organic polymer, such as a polyimide.

Abstract: A power distribution structure for a multichip module and a method for fabricating the same are shown. According to the method of the present invention, a base plate is provided, a plurality of mesas arranged in a pattern are formed on the base plate, the mesas having electrically conductive upper surfaces which lie substantially in a single plane. A thin, conformal dielectric layer is then formed over the exposed surfaces of the mesas and the support base and a conductive material is deposited over the dielectric material filling the area between and surrounding the mesas. The resulting structure is then planarized, as by polishing, such that the upper surfaces of the mesas and the upper surface of the conductive material surrounding the mesas lie in substantially one plane and are electrically isolated from each other by the dielectric material.

Abstract: Methods of forming high-aspect ratio blind apertures and thereafter filling the apertures with a plating solution are disclosed. A layer of photosensitive material is pattern exposed to actinic radiation to define the apertures, and thereafter exposed to aqueous developer solution. The apertures are then rinsed with water and thereafter exposed to plating solution without drying the aperture of water or developer solution. This is contrary to conventional practice where photoresist layers are dried, and usually post-baked after the development step in order to improve dimensional integrity and reduce swelling of the photoresist material.

Abstract: An interconnecting post for mounting a microelectronic device such as an integral circuit chip is fabricated with generally uniform cross-section, by forming a first layer of positive photoresist on a substrate, soft-baking that first layer and exposing it for a short time with a wide-apertured mask or simply a UV blank flood exposure. Without developing the first layer, a second layer of positive resist is then applied over the first layer, soft-baked, and then exposed with a narrow-apertured mask. During the soft-baking of the second layer, some of its activator in the photoresist compound diffuses into the exposed portion of the first layer and modifies its solubility in such a way that, when the layers are subsequently developed, the developer partially undercuts the unexposed portion of the first layer to form in the photoresist an opening of generally uniform cross-section. This opening can then be filled by plating to produce a strong, integral interconnect post.

Abstract: Methods for pretreating patterned masks layers, such as photoresist masks, with electron-beam radiation for use in high temperature processes are disclosed. The electron-beam exposure deactivates compounds within the mask material which would ordinarily decompose and produce gasses within the photoresist layer. The gasses cause blistering in the untreated photoresist layer, which in turn degrades the dimensional integrity of the untreated layer.

Abstract: A multichip module substrate for use in a three-dimensional multichip module, and methods of making the same, are disclosed. The substrate comprises a thin film structure, for routing signals to and from integrated circuit chips, formed over a rigid support base. Apertures are formed in the support base exposing the underside of the thin film structure, thereby allowing high density connectors to be mounted on both surfaces of the thin film structure, greatly enhancing the ability to communicate signals between adjacent substrates in the chip module. This avoids the need to route the signals either through the rigid support base or to the edges of the thin film structure. Power and ground, which do not require a high connection density, are routed in low impedance paths through the support base. Preferably, the thin film structure is made of alternating layers of patterned metal, such as copper, and a low dielectric organic polymer, such as a polyimide.

Abstract: Methods of constructing a wire interconnect structure on a substrate are described. The methods broadly comprise the steps of depositing a spacer layer on a surface of the substrate, depositing a mask layer on the spacer layer, and removing a first portion of the mask layer overlying a desired area on the substrate surface to expose the spacer layer underlying the first portion of the mask layer. The methods further comprise the step of etching the structure such that a first portion of the spacer layer overlaying the desired area is removed and such that a portion of the desired area is exposed, and the step of depositing a first conductive material on the exposed portion of the desired area such that a conductive post is formed on the substrate surface and mounted to the desired area. Some of the disclosed methods comprise additional steps for forming an interconnect structure on the opposite surface of the substrate and providing an electrical interconnect means between the two interconnect structures.

Abstract: Interconnect carriers for coupling integrated circuit chips to major substrates and methods for making the same are disclosed. The interconnect carrier comprises a relatively thin resilient supporting layer, a plurality of electrically conductive vias formed through the surfaces of the supporting layer, and an outer frame disposed around the periphery of the supporting layer. The supporting layer preferably comprises an electrically insulating material. The flexibility of the supporting layer enables the layer to more readily conform to the warpages of the IC chip and supporting substrate, while the outer frame provides mechanical support and prevents the supporting layer from folding, twisting, and/or stretching. The thickness of the supporting layer may be substantially reduced over that of prior art interposers to enable methods for constructing smaller diameter vias.

Abstract: A high density through-hole interconnect with high aspect ratio vias is formed by sequentially forming layers of dielectric material on a previous dielectric layer. After each layer is formed, a plurality of through holes are etched through each layer and filled or metalized with an electrically conductive material having a coefficient of thermal expansion matching that of the dielectric layers and the integrated circuit that it will connect with. Preferably, the process of forming dielectric layers, forming through holes, and metalizing the through holes is repeated until the metalized through holes have an aspect ratio in the range of from 6 to 10. A support structure is constructed to interconnect with and support the metalized vias while the dielectric material is removed. A second dielectric material having the desired mechanical and electrical properties is poured into the support structure to fill the space between the metalized vias and allowed to solidify.

Abstract: A three dimensional thin-film interconnector is fabricated by depositing a dielectric layer onto the surface of a substrate, depositing a layer of conductive material onto the dielectric layer to form a signal plane, depositing a dielectric layer onto the surface of the signal plane, forming a plurality of through holes in the dielectric layer that extend to the signal plane, and filling the through holes with an electrically conductive material to form vias. The sequence of forming a signal plane, depositing a dielectric layer, forming a plurality of through holes, and filling the through holes is repeated until a predetermined number of signal planes and a predetermined arrangement of vias are obtained. The through holes are formed at locations in the dielectric layers corresponding to both predetermined electrical connections and the vias in a preceding dielectric layer. The signal planes are formed at different locations on the substrate.

Abstract: A thin-film bypass capacitor is fabricated by forming a plurality of through holes through the thickness of a nonconductive base substrate and filling the through holes with a conductive material to form ground vias and power vias. A sequence of back side metalization layers are applied to the back side surface of the base substrate. A sequence of bottom contact layers are applied to the front side surface of the base substrate. A bottom contact power terminal is formed and a bottom contact metalization layer is applied to the surface of the bottom contact layers. A portion of the metalization layer is removed and an insulating layer is formed on the surface of the bottom contact metalization layer. A ground metalization feedthrough and a power metalization feedthrough are formed at the surface of the insulating layer. A sequence of top contact layers are applied to the surface of the insulating layer and a front side ground terminal and front side power terminal are formed.

Abstract: A method of curing an organic dielectric layer, such as polyimide, used in a multichip module is disclosed. The method comprises heating the uncured polyimide layer to a temperature above its glass transition temperature, and irradiating the layer with a uniform flux of electrons, as in an e-beam apparatus. The process reduces deterioration at the interface between the dielectric films and the metal layers which when high temperature thermal curing is utilized, and reduces the stress of the resulting film. Multiple dielectric layers can be applied in this manner.

Abstract: An interconnect structure for connecting an integrated circuit (IC) chip to a supporting substrate is described. The supporting substrate serves to communicate signals between the IC chip and the "outside world," such as other IC chips. In one embodiment, the interconnect structure comprises an interconnect substrate having a first post disposed on one of its surfaces and a second post disposed on another of its surfaces. One post is for contacting the IC chip and the other is for contacting the major substrate. Each post comprises an elongated body having top and bottom ends, with the bottom end being mounted to one of the substrate surfaces and the top end having a substantially flat surface which is substantially co-planer with the substrate surface. The interconnect substrate further comprises a device for de-concentrating the mechanical stain present at one or both of the top and bottom ends of each post.

Abstract: A thin-film bypass capacitor is fabricated by forming a plurality of through holes through the thickness of a nonconductive base substrate and filling the through holes with a conductive material to form ground vias and power vias. A sequence of back side metalization layers are applied to the back side surface of the base substrate. A sequence of bottom contact layers are applied to the front side surface of the base substrate. A bottom contact power terminal is formed and a bottom contact metalization layer is applied to the surface of the bottom contact layers. A portion of the metalization layer is removed and an insulating layer is formed on the surface of the bottom contact metalization layer. A ground metalization feedthrough and a power metalization feedthrough are formed at the surface of the insulating layer. A sequence of top contact layers are applied to the surface of the insulating layer and a front side ground terminal and front side power terminal are formed.