Method of manufacturing semiconductor device wherein silicon substrates are bonded together

摘要

A method of manufacturing a semiconductor device, wherein a semiconductor wafer having a first impurity-doped layer and a second impurity-doped layer having a higher impurity concentration than that of the first impurity-doped layer is formed. A first silicon substrate, having a first impurity-doped layer and a third impurity-doped layer which has a higher impurity concentration than that of the first impurity- doped layer and the same conductivity type as that of the second impurity- doped layer, and whose surface is mirror-polished, is brought into contact with a second silicon substrate which has a higher impurity concentration than that of the first impurity-doped layer and the same conductivity type as that of the second impurity-doped layer, and whose surface is mirror-polished, so that the mirror-polished surfaces thereof are in contact with each other. The contacting substrates are then placed in a clean atmosphere so that virtually no foreign substances are present therebetween, and annealed at a temperature of not less than 200° C. so as to bond them together, thereby forming the second impurity-doped layer consisting of the third impurity doped layer and the second silicon substrate.