Quartet of testers said to improve accuracy, yields -- Schlumberger takes on RDRAM test challenge
Stan Runyon
San Jose, Calif. - With the expected huge leap in Rambus DRAM shipments next year, memory manufacturers are under pressure to find new ways to test these gigabit-data-rate chips. Schlumberger ATE says it has solved the problem and is already shipping testers carrying the solution.
Testers in the RDX2200 series boast plus/minus 50-ps multisite edge-placement accuracy, a 1-Gbit/ second data rate and new software that accommodates the RDRAM's requirements for packet-data generation. Chris Mack, director of product marketing at Schlumberger, maintained that the testers were the first to meet Rambus speed and accuracy specs across eight sites.
"As tester edge-placement improves, yields increase, significantly impacting profitability," said Jackie Tubis, president of Schlumberger ATE. "Using our RDRAM products, a company producing 10 million units valued at $15 a unit could potentially realize $9 million a year in yield increases from a 30-ps improvement in edge-placement accuracy."
Those two factors-accuracy and yield-"are the most critical issues facing RDRAM test and volume production today," said Dan Hutcheson, president of VLSI Research Inc. Schlumberger also claims its tester slashes months off the RDRAM development cycle.
Shipments swelling
According to estimates from Dataquest Inc. here, Rambus DRAM production should account for 5 percent of the total DRAM capacity shipped this year, swelling to about 31 percent next year. Indeed, 15 of the top memory makers-supplying more than 96 percent of the world market-have signed license agreements to produce RDRAM devices.
"The evolution of RDRAM technology is radically changing the way devices are tested," said Schlumberger's Tubis. "It requires totally new test methodology, tools and skill sets to produce the necessary volume of chips to fulfill industry demand at a reasonable cost per unit."
Tubis said Schlumberger spent the last year working with a world leader in memory devices to perfect a solution. "For the first time," he said, "memory manufacturers have to deal with integrating high-performance logic capabilities within a memory device, resulting in the need for a new level of highly accurate, flexible and robust test solutions."
Drawing on its expertise in logic testing, Schlumberger is rolling out four fully compatible members of a new family, the RDX2200 series, intended to significantly shrink time-to-volume while boosting yields. The products are also designed to accommodate evolving test methodologies-important because RDRAMs are still a work in progress.
The four new systems in the RDX2200 product line provide a seamless transition from design validation to device characterization and production, the company said: No correlation steps are necessary.
All feature the company's patented Sequencer Per Function timing architecture and proprietary liquid-cooling technology to reduce pattern-dependent error. This ensures the plus/minus 50-ps edge-placement accuracy-pattern to pattern, device site to device site, and tester to tester, worldwide.
Digital and hierarchical calibration to the device under test further reduce error throughout the entire timing path and ensure repeatability, according to Schlumberger.
The RDX2200dv is a complete RDRAM debug and verification system. With this fully integrated e-beam and tester solution, users can directly probe internal RDRAM nodes at speed.
Features include non-contact, no-load measurements for internal signal probing, easy setup and automated CAD navigation for fast signal identification, high-resolution ac timing measurements with 1-ps resolution, and greater than 8-GHz bandwidth.
The RDX2200cs is a high-performance characterization system that tests RDRAMs at the widest operating range available. To simplify pattern programming, a packet generator provides fully automatic RDRAM pattern generation. A suite of programming and characterization tools is designed to help move new RDRAM designs into production faster.
Real-time thermal control
Next in the family is the RDX2200tc, an advanced test and thermal-characterization cell designed for RDRAM product development. By combining a fast, accurate temperature-forcing system with the test system, Schlumberger has produced an at-speed tester offering high precision and real-time thermal control.
According to the company, the system features the industry's fastest temperature change across the complete range of -35 degrees to 125 degrees C. The unit also synchronizes test-vector execution with temperature control and features automatic dynamic temperature analysis and data collection.
Finally, the RDX2200 brings advanced calibration, a 1-ps time-measurement unit and full liquid cooling for junction-temperature control. It comes equipped with Schlumberger's TruEdge accuracy-validation software, the Packet Generator, handler interfaces, a graphical test environment called ASAP and production debug tools.
In pricing, the RDX2200 series comes in between $1 million and $2.5 million. The company is also offering RDRAM services from its Saber (Schlumberger Advanced Business Engineering Systems) unit. Additional information is available on the Web at www.slb.com/ate. |
