| 摘要 |
PROBLEM TO BE SOLVED: To improve a heat sink in thermal conductivity as a whole by a method, wherein all the one surface of a metal board of comparatively satisfactory thermal conductivity is covered with a polycrystalline diamond layer of a specified thickness. SOLUTION: A semiconductor element 5, bonding wires 7 connected to the semiconductor element 5, and a lead frame 6 connected to the bonding wires 7 are provided inside a package 1. A metal board material 2, a polycrystalline diamond layer 3, a first intermediate bonding layer 8a, a second intermediate bonding layer 8b, and a metal bonding layer 4 are provided in this order starting from the bottom to serve as a base for the semiconductor element 5. At this point, a metal board material 2 (0.5 mm in thickness, 2 inches in diameter) is formed of a sintered nonmetallic element selected from among Si, AlN, SiC, Si3 N4 , or the like, and a polycrystalline diamond layer 3 is formed as thick as 50 μm on the metal board material 2 through a hot filament CVD method. The CVD method is carried out under the conditions, where material gas is composed of 1,500 sccm hydrogen and 30 sccm methane, gas pressure is set at 70 Torr, a W filament temperature is set at 2,000 to 2,100 deg.C, and the time is set at 45 hours. |
