SEMI reports that the three-month average of worldwide bookings in December 2015 was $1.34 billion. The bookings figure is 8.6 percent higher than the final November 2015 level of $1.24 billion, and is 2.8 percent lower than the December 2014 order level of $1.38 billion.

The three-month average of worldwide billings in December 2015 was $1.35 billion. The billings figure is 4.9 percent higher than the final November 2015 level of $1.29 billion, and is 3.2 percent lower than the December 2014 billings level of $1.40 billion.

"Both semiconductor equipment bookings and billings improved in December," said Denny McGuirk, president and CEO of SEMI. “Despite softness in the equipment market in the fourth quarter, both annual bookings and billings in 2015 of North American equipment suppliers remained above 2014 levels."

The SEMI book-to-bill is a ratio of three-month moving averages of worldwide bookings and billings for North American-based semiconductor equipment manufacturers. Billings and bookings figures are in millions of U.S. dollars.