David Lammers

Big Wafers, Big Prices
November 7, 2008

Dean Freeman, the Gartner semiconductor equipment analyst, threw out a zinger when he came to Austin for a SEMI market outlook gathering. The early 450 mm wafers will be in the $15-20,000 dollar range, Freeman said in a matter-of-fact tone. After his presentation, he said large wafer customers such as Intel Corp. may get a break, paying $10-15,000 in the early going when pilot 450 mm production is underway.

“To enable the 450 transition the wafer price will have to go down, but it will be that high at the beginning,” he said, adding that Intel is the only company “really committed” to 450 mm development. When an MPU die reaches 400 mm² the MPU makers will make the transition to 450 mm wafers, Freeman said. Using through silicon vias (TSVs) to vertically connect logic and memory die may give the MPU makers a way of postponing the need for the larger wafers by keeping die sizes below the 400 mm² threshold, he added.

Manufacturers worry about wafer costs partly because 300 mm wafers have been relatively expensive.The 300 mm wafers initially cost >$1000 for volume manufacturing and then dropped slowly to ~$250, with the reduction occurring more slowly than the curve for the 200 mm wafers, according to Gartner. For 200 mm fabs, the wafer cost is about half the materials cost. For a 300 mm manufacturer, the wafer accounts for about 64% of the total materials cost, making the issue of 450 mm wafer prices a critical question in their minds. 

One critic at a major DRAM manufacturer said the high cost of the 450 mm wafers will make it much harder to gain the promised reduction in manufacturing costs. Moving to the larger diameter would result in a 2.25× area increase, but if the wafer cost increases by 3-5×, the benefit is “neutralized,” he said.

At the recent ISMI Symposium on Manufacturing Effectiveness in Austin, Intel materials scientist (and half-time assignee to ISMI) Mike Goldstein said the Big 4 wafer manufacturers – ShinEtsu, Sumco, Wacker, and MEMC -- will start making 450 mm single crystal wafers next year. “They are setting up the equipment, developing the know-how. The market is not ready yet, it is too early, but they need to start next year,” Goldstein said, noting that Intel, Samsung Electronics, and TSMC plan to begin pilot line production in 2012. (Goldstein said he has several of the initial single-crystal 450 mm wafers in his office at Santa Clara, but declines to say which companies provided them.)

“They all have the technical capability. They are ready to grow the crystals. The questions they are asking are about the business drivers,” he said, acknowledging that not all of the wafer suppliers are moving their 450 mm programs at the same speed.

Next year, the ISMI Interoperability Test Bed expects to begin building a wafer bank of single-crystal 450 mm wafers. This year, ISMI loaned out ~110 of the sintered polycrystalline test wafers used to develop the wafer handling systems and carriers. ISMI engineers have spent a good bit of time figuring out how to support the larger wafers so that gravitational sag doesn’t exceed allowable limits. After spending this year working out the issues of wafer carriers, load ports, and handlers, the focus will shift next year to AMHS systems and early processing tools.

Goldstein said the biggest challenge for the wafer makers is that the ingots are heavy, weighing 700-1000 kg., or ~1 metric ton. “Handling the ingots is a challenge. They are expensive, so any failure is expensive,” he said.

Goldstein said the challenges of the 450 mm generation are not much different than in the early days when questions were raised about the 150 mm wafer transition. The wafer manufacturers have developed next-generation wafer polishing techniques that could be brought into play for the 450 mm wafers. The wafer growing and wafer polishing advances are being developed in parallel, Goldstein said, and enough progress is visible that he said is confident that 450 mm wafers can be made cost effectively.

“When times are bad, the wafer suppliers have no money. When times are very good, they have no time. There are always challenges, but we will solve them,” Goldstein said.

Posted by David Lammers on November 7, 2008 | Comments (1)