Abstract: Multiple injections of molten solder are employed to form double solder bumps having outer layers that melt at lower temperatures than the inner portions thereof. During a flip chip assembly process, the reflow temperature is above the melting temperature of the outer layers and below the melting temperature of the inner portions of the solder bumps. As the inner portions of the solder bumps do not collapse during reflow, a flip chip assembly can be made at relatively low temperatures and have a high stand-off height. A structure having double solder bumps facilitates flip chip assembly.

Abstract: A process comprises manufacturing an electromigration-resistant under-bump metallization (UBM) flip chip structure comprising a Cu layer by applying to the Cu layer a metallic reaction barrier layer comprising NiFe. The solder employed in the flip chip structure comprise substantially lead-free tin. A structure comprises a product produced by this process. In another embodiment a process comprises manufacturing an electromigration-resistant UBM Sn-rich Pb-free solder bump flip chip structure wherein the electromigration-resistant UBM structure comprises a four-layer structure, or a three-layer structure, wherein the four layer structure is formed by providing 1) an adhesion layer, 2) a Cu seed layer for plating, 3) a reaction barrier layer, and 4) a wettable layer for joining to the solder, and the three-layer structure is formed by providing 1) an adhesion layer, 2) a reaction barrier layer, and 3) a wettable layer.

Abstract: Multiple injections of molten solder are employed to form double solder bumps having outer layers that melt at lower temperatures than the inner portions thereof. During a flip chip assembly process, the reflow temperature is above the melting temperature of the outer layers and below the melting temperature of the inner portions of the solder bumps. As the inner portions of the solder bumps do not collapse during reflow, a flip chip assembly can be made at relatively low temperatures and have a high stand-off height. A structure having double solder bumps facilitates flip chip assembly.

Abstract: Multiple injections of molten solder are employed to form double solder bumps having outer layers that melt at lower temperatures than the inner portions thereof. During a flip chip assembly process, the reflow temperature is above the melting temperature of the outer layers and below the melting temperature of the inner portions of the solder bumps. As the inner portions of the solder bumps do not collapse during reflow, a flip chip assembly can be made at relatively low temperatures and have a high stand-off height. A structure having double solder bumps facilitates flip chip assembly.

Abstract: A method is provided in which a substrate including various materials of different fracture toughness (KIc) can be spalled in a controlled manner. In particular, a surface step region is formed within a surface portion of the substrate prior to formation of a stressor layer. The presence of the surface step region within the surface portion of the substrate controls the depth and ease at which crack initiation occurs within the substrate.

Abstract: Methods for removing a material layer from a base substrate utilizing spalling in which mode III stress, i.e., the stress that is perpendicular to the fracture front created in the base substrate, during spalling is reduced. The substantial reduction of the mode III stress during spalling results in a spalling process in which the spalled material has less surface roughness at one of its' edges as compared to prior art spalling processes in which the mode III stress is present and competes with spalling.

Abstract: Multiple injections of molten solder are employed to form double solder bumps having outer layers that melt at lower temperatures than the inner portions thereof. During a flip chip assembly process, the reflow temperature is above the melting temperature of the outer layers and below the melting temperature of the inner portions of the solder bumps. As the inner portions of the solder bumps do not collapse during reflow, a flip chip assembly can be made at relatively low temperatures and have a high stand-off height. A structure having double solder bumps facilitates flip chip assembly.

Abstract: A spalling method is provided that includes depositing a stressor layer on surface of a base substrate, and contacting the stressor layer with a planar transfer. The planar transfer surface is then traversed along a plane that is parallel to and having a vertical offset from the upper surface of the base substrate. The planar transfer surface is traversed in a direction from a first edge of the base substrate to an opposing second edge of the base substrate to cleave the base substrate and transfer a spalled portion of the base substrate to the planar transfer surface. The vertical offset between the plane along which the planar transfer surface is traversed and the upper surface of the base substrate is a fixed distance. The fixed distance of the vertical offset provides a uniform spalling force. A spalling method is also provided that includes a transfer roller.

Abstract: An apparatus for transferring metal solidified in blind cavities is described incorporating a first flexible tape having blind cavities, a second flexible tape having adhesive regions, rollers for guiding respective tapes and means for moving respective tapes. Also a conveyor belt having blind or through cavities, rollers and a vibration transducer or pressurized gas is described to release solidified metal in the cavities.

Abstract: A stressor layer used in a controlled spalling method is removed through the use of a cleave layer that can be fractured or dissolved. The cleave layer is formed between a host semiconductor substrate and the metal stressor layer. A controlled spalling process separates a relatively thin residual host substrate layer from the host substrate. Following attachment of a handle substrate to the residual substrate layer or other layers subsequently formed thereon, the cleave layer is dissolved or otherwise compromised to facilitate removal of the stressor layer. Such removal allows the fabrication of a bifacial solar cell.

Abstract: Methods for removing a material layer from a base substrate utilizing spalling in which mode III stress, i.e., the stress that is perpendicular to the fracture front created in the base substrate, during spalling is reduced. The substantial reduction of the mode III stress during spalling results in a spalling process in which the spalled material has less surface roughness at one of its' edges as compared to prior art spalling processes in which the mode III stress is present and competes with spalling.

Abstract: Multiple injections of molten solder are employed to form double solder bumps having outer layers that melt at lower temperatures than the inner portions thereof. During a flip chip assembly process, the reflow temperature is above the melting temperature of the outer layers and below the melting temperature of the inner portions of the solder bumps. As the inner portions of the solder bumps do not collapse during reflow, a flip chip assembly can be made at relatively low temperatures and have a high stand-off height. A structure having double solder bumps facilitates flip chip assembly.

Abstract: A substrate holder assembly for use in a controlled spalling process is provided. The substrate holder assembly includes a base structure having a surface in which a base substrate or other work piece can be placed thereupon. A framing element is located above and spaced apart from the surface of the base structure. The framing element has a window which exposes an upper surface of the base substrate and defines an area of the upper surface of the base substrate in which another material can be applied thereto. A support structure containing at least one mechanical securing element is located on the framing element. The support structure mechanically constrains the base substrate within the substrate holder assembly. Each mechanical securing element contacts at least one surface of the support structure and, optionally, one surface of the base substrate.

Abstract: A substrate holder assembly for use in a controlled spalling process is provided. The substrate holder assembly includes a base structure having a surface in which a base substrate or other work piece can be placed thereupon. A framing element is located above and spaced apart from the surface of the base structure. The framing element has a window which exposes an upper surface of the base substrate and defines an area of the upper surface of the base substrate in which another material can be applied thereto. A support structure containing at least one mechanical securing element is located on the framing element. The support structure mechanically constrains the base substrate within the substrate holder assembly. Each mechanical securing element contacts at least one surface of the support structure and, optionally, one surface of the base substrate.

Abstract: The present disclosure provides a method for forming two device wafers starting from a single base substrate. The method includes first providing a structure which includes a base substrate with device layers located on, or within, a topmost surface and a bottommost surface of the base substrate. The base substrate may have double side polished surfaces. The structure including the device layers is spalled in a region within the base substrate that is between the device layers. The spalling provides a first device wafer including a portion of the base substrate and one of the device layers, and a second device wafer including another portion of the base substrate and the other of the device layer.

Abstract: A process and apparatus for forming and transferring metal arrays of balls and shapes is described incorporating molds, tape, injection molded metal such as solder, metal reflow and a mask on a substrate for shearing solidified metal of metal arrays into respective openings in the mask.

Abstract: A compliant material is formed between a base substrate and a support structure prior to performing a controlled spalling process. By positioning the compliant material between the base substrate and the support structure, the localized effects of surface perturbations (particles, wafer artifacts, etc.) on spalling mode fracture can be reduced. The method of the present disclosure thus leads to improved surface quality of the spalled material layer and the remaining base substrate. Moreover, the method of the present disclosure can reduce the density of cleaving artifacts.

Abstract: Multiple injections of molten solder are employed to form double solder bumps having outer layers that melt at lower temperatures than the inner portions thereof. During a flip chip assembly process, the reflow temperature is above the melting temperature of the outer layers and below the melting temperature of the inner portions of the solder bumps. As the inner portions of the solder bumps do not collapse during reflow, a flip chip assembly can be made at relatively low temperatures and have a high stand-off height. A structure having double solder bumps facilitates flip chip assembly.

Abstract: A method is provided in which a substrate including various materials of different fracture toughness (KIc) can be spalled in a controlled manner. In particular, a surface step region is formed within a surface portion of the substrate prior to formation of a stressor layer. The presence of the surface step region within the surface portion of the substrate controls the depth and ease at which crack initiation occurs within the substrate.

Abstract: A method to minimize edge-related substrate breakage during spalling using an edge-exclusion region where the stressor layer is either non-present (excluded either during deposition or removed afterwards) or present but significantly non-adhered to the substrate surface in the exclusion region is provided. In one embodiment, the method includes forming an edge exclusion material on an upper surface and near an edge of a base substrate. A stressor layer is then formed on exposed portions of the upper surface of the base substrate and atop the edge exclusion material, A portion of the base substrate that is located beneath the stressor layer and which is not covered by the edge exclusion material is then spalled.