Process of making pad structure for solder ball limiting metallurgy having reduced edge stress
December 31, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesMethod of forming a solder interconnection capable of sustained high power levels between a semiconductor device and a supporting substrate Solder mound formation on substrates Compressively stresses titanium metallurgy for contacting passivated semiconductor devices Semiconductor integrated circuit device in which a semiconductor chip is mounted with solder bumps for mounting to a wiring substrate Method of forming metal contact pads and terminals on semiconductor chips Etching processes for avoiding edge stress in semiconductor chip solder bumps Method of manufacturing semiconductor device terminal having a gold bump electrode Patent #: 5298459 InventorAssigneeApplicationNo. 998982 filed on 12/31/1992US Classes:438/614, Plural conductive layers216/100, Substrate contains elemental metal, alloy thereof, or metal compound257/737, Bump leads257/738, Ball shaped257/780, Ball or nail head type contact, lead, or bond257/E21.508, Forming solder bumps (EPO)438/615Including fusion of conductorExaminersPrimary: Chaudhuri, OlikAssistant: Pham, Long Attorney, Agent or FirmForeign Patent References
International ClassH01L 021/44AbstractA two-step masking process is disclosed for forming a ball limiting metallurgy (BLM) pad structure for a solder joint interconnection used between a support substrate and a semiconductor chip. A solder non-wettable layer and a solder wettable layer are deposited on the surface of a support substrate or semiconductor chip which are to be connected. A phased transition layer is deposited between the wettable and non-wettable layers. A thin photo-resist mask defines an area of the solder wettable and phased layers which are etched to form a raised, wettable frustum cone portion. A second mask is deposited on the surface of the support substrate or semiconductor chip, and has an opening concentrically positioned about the frustum cone. Solder is deposited in the opening and covers the frustum cone and the area about its periphery. When solidified, the solder, acting as a mask, is used to sub-etch the underlying solder non-wettable layer thereby defining the BLM pad. When reflowed, the solder beads away from the surface of the solder non-wettable layer to form a ball which securely adheres about the frustum cone. | |
