Micron Technology Inc. said its earnings surged as the memory-chip maker benefited from stronger sales and margins, as well as lower costs, during its quarter ended Dec. 4. Micron shares, however, fell 5.8% to $30.95 in recent after-hours trading as revenue missed analysts' expectations, though it was in line with company estimates. Through Tuesday's close, the shares have risen 59% in the past 12 months.