| 摘要 |
<p>PURPOSE:To shorten a product developing term and to make cost down, by making possible to do changeover of the option with the same mask as that used in writing of data, in a mask ROM which writes data using selective ion implantation or an LSI including the mask ROM. CONSTITUTION:Between an input terminal 1 and an output terminal 2, an inverter 3 and a switching MOSFETQs1 are connected in series and a second switching MOSFETQs2 is connected in parallel with them. The MOSFETs Qs1 and Qs2 are of the same N-channel type as MOSFET memory devices constituting a memory array of mask ROMs, and a channel of any one of them is ion-implanted at the same time when writing data, using the same mask as an mask for implanting ions into memory device channels to be employed in data- writing. The MOSFET, which has been ion-implanted, has a low threshold value and changes into a depletion type.</p> |
