A wafer-scale assembly apparatus for integrated circuits and method for forming the wafer-scale assembly. A semiconductor wafer including a plurality of circuits is provided with a plurality of metal contact pads as electrical entry and exit ports. A first wafer-scale patterned polymer film carrying solder balls for each of the contact pads on the wafer is positioned opposite the wafer, and the wafer and the film are aligned. The film is brought into contact with the wafer. Radiant energy in the near infrared spectrum is applied to the backside of the wafer, heating the wafer uniformly and rapidly without moving the semiconductor wafer. Thermal energy is transferred through the wafer to the surface of the wafer and into the solder balls, which reflow onto the contact pads, while the thermal stretching of the polymer film is mechanically compensated. The uniformity of the height of the liquid solder balls is controlled either by mechanical stoppers or by the precision linear motion of motors. After cooling, the solder balls solidify and the first polymer film is removed.