SEMICONDUCTOR DEVICE HAVING SINGLE CRYSTAL SILICON REGION AND POLYCRYSTALLINE SILICON STRUCTURE AND METHOD FOR GENERATING CONTACT BETWEEN SINGLE CRYSTAL SILICON REGION AND POLYCRYSTALLINE SILICON STRUCTURE

PROBLEM TO BE SOLVED: To form a contact between a single crystal silicon region and a polycrystalline silicon structure in such a way that the contact may have only a slight contact resistance, and simultaneously generation or spreading of dislocation in the single crystalline silicon is prevented. SOLUTION: An amorphous or polycrystalline silicon structure and/or a single crystal silicon region 20 is doped with a dopant e.g. oxygen at a doping concentration exceeding the solubility limit in order to generate the contact between the polycrystalline silicon structure and the single crystal silicon region 20. Then, dopant precipitation is formed by the following heating treatment. This controls the crystal grain growth in the polycrystalline silicon 16 or to suppress propagation of crystal defect to a substrate in the single crystal silicon region. Such a contact is used for DRAM trench cell as a buried strap, for example.