Method for electrically conductive connection using flip-chip technology

摘要

Semiconductor device mounting on a substrate is by gold-gold thermocompression of gold contact bumps applied by electroplating onto at least one of the joint partners. The novelty comprises the use of (i) a constantly agitated sulphitic gold bath which contains 1.5-3.5 mg/l grain refiner and which has a deposition rate of less than 0.2 microns/min.; (ii) a joint partner having contacting faces with a gold layer of at least 200 nm thickness and max. 50 nm roughness; and (iii) thermocompression at below 350 deg.C and less than 30 MPa thermode pressure. A bath for electroplating gold contact bumps on semiconductor devices or substrates contains 30-42 g/l sulphite, 25-35 g/l sulphate, 9-11 g/l gold. 2.5-5 g/l chloride and 1.5-3.5 mg/l grain refiner and is used under the conditions of 0.25-0.3 A/sq.dm current density, 40-50 deg.C. 1:3.5-4.5 anode:cathode surface area ratio, constant thorough mixing of the bath and bath pH 8.5-9.5. A joint partner for the above process is also claimed. USE/ADVANTAGE - Esp. for chip-on-chip mounting of a III-V semiconductor (usually optoelectronic) device onto a Si-IC by the flip-chip mounting process. The process provides high quality bonding of sensitive semiconductor devices onto a substrate in a space-saving manner.