| ??? 08/10/06 08:04 Read: times |
#121951 - early MOS technology Responding to: ???'s previous message |
The behaviour of MOS transistors depends most dramatically on the amount and character of impurities and defects on the Si/oxide interface (basically on the surface of the unprocessed wafer). This influences (above others) the threshold voltage. And, you want mainly enhancement mode ("normally-OFF") transistors in ICs. These impurities in early processes tended to be such that only PMOS transistors were "normally-OFF", so this was the "polarity of choice" despite of the lower majority carrier (here: holes) mobility (hence lower "speed").
One of the key elements in progress of semiconductor technology is in the purity of the used materials (and the processing environment, of course). Jan Waclawek |
| Topic | Author | Date |
| High or Low in keypad scanner? | 01/01/70 00:00 | |
| PNP? | 01/01/70 00:00 | |
| maybe with TTL, but what about CMOS? | 01/01/70 00:00 | |
| I would not, the user does | 01/01/70 00:00 | |
| that depends on how you scan the inputs | 01/01/70 00:00 | |
| physical/technological reasons | 01/01/70 00:00 | |
| What sorts of reasons? | 01/01/70 00:00 | |
| early MOS technology | 01/01/70 00:00 | |
| Maybe they did it... | 01/01/70 00:00 | |
| Oxymoron! | 01/01/70 00:00 | |
| you spoilt my joke now | 01/01/70 00:00 | |
| Jokes | 01/01/70 00:00 | |
| We are living in a TTL world... | 01/01/70 00:00 | |
| I don't know why this interests me, but ... | 01/01/70 00:00 | |
| a proverbial answer | 01/01/70 00:00 | |
| So you figure it's just a matter of preference? | 01/01/70 00:00 | |
| You really should get out more! | 01/01/70 00:00 | |
Yes, it's a second childhood ... or maybe a third | 01/01/70 00:00 |