The Semiconductor Industry Assn. said it was the fifth consecutive month that industry business conditions showed improvement. Last month's bookings were 15.2% higher than the same figure a year ago, the association said. At $677.8 million, billings or shipments for February were 4.9% higher than the $645.9 million shipped during January. February's book-to-bill ratio increased to 1.13, meaning manufacturers received $113 worth of new orders from U.S. plants for each $100 worth of silicon chips shipped in the U.S. during the month.