| 摘要 |
<p>PURPOSE:To cut down the time required for completion of a vertical ROM by a method wherein, after previously composing all memory cells in depletion type, selected cells are changed into enhancement type etc., to write data therein. CONSTITUTION:Overall surface of the active region of a semiconductor substrate 1 is channel-doped with n-type impurity to form N<->type layer 4 thus data 1 are written in all cells of a memorial array. Later, word lines W1-W3, source, drain region 5 comprising a gate electrode are formed to form a depletion type MISFET. Then, after forming an interlayer insulating film 6 and a data line 7, a channel part of memory cell to write the data 1 therein e.g. FETQ2 is doped with p type impurity to change the n-type of said impurity layer 4 into a p-type impurity layer 9. Through these procedures, after forming the data line 7 etc., the channel part can be composed in enhancement type or mild depletion type to write the data 1 therein so that the turnaround time required for the completion of ROM may be cut down.</p> |
