Demand for chip equipment was flat in May, while the book-to-bill ratio fell slightly, according to an industry report.

Orders, or bookings, were $1.58 billion for the month, unchanged from April's level, but 77% higher than a year ago, according to Semiconductor Equipment and Materials International's monthly report.

The book-to-bill ratio fell to 1.11, lower than April's 1.13 rate and that of every other month except March in the last half year. Abook-to-bill of 1.11 means that $111 worth of orders were received for every$100 of product billed for the month.

Billings continued to rise, however, posting their 11th consecutive sequential gain to $1.42 billion, 2% higher than a month ago.

The SEMI book-to-bill is a ratio of three-month moving averages ofworldwide bookings and billings for North American-based semiconductor-equipment manufacturers.