The reduced power consumption also addresses a key need for Intel, which is the dominant maker of chips for personal computers but has been weak in the growing markets for chips used in smart phones and tablet computers. Intel’s current chips use too much power for it to be competitive in those markets, and the 3-D chips could help it become more of a player.

Transistors are microscopic, but their performance is felt with every click of a mouse, tap on a smart phone, or download from a website. The faster they twitch, the faster a computer “thinks”—and sucks up power.

They need to get smaller without leaking too much power, a worrisome issue as the materials reach the atomic scale and get worse at blocking current from escaping.

Intel’s advance does not add a complete third dimension to chip-making—that is, the company can’t add an entire second layer of transistors to a chip, or start stacking layers into a cube. That remains a distant but hotly pursued goal of the industry, as cubic chips could be much faster that flat ones while consuming less power.

And the technological advance Intel has achieved won’t guarantee success, as Intel has learned in repeated attempts at cracking the mobile market. The performance expectations and power requirements for phones and tablet computers are not as high as those for PCs.

Other chip makers, such as Qualcomm Inc. and Texas Instruments Inc., have entrenched partnerships with cell-phone makers that Hutcheson, the industry watcher with VLSI Research, said will be tough to overcome.

“When it comes to the mobile market, they have their work cut out for them,” he said. But “this gives you the transistors to build the next great system.”