Siva Sivaram Halves Cost of Thin-Film Solar Cells

Siva Sivaram doesn’t want to compete with all those struggling solar cell producers; he wants to sell them his multimillion dollar proton accelerators so they can cut the cost of producing solar cells in half.

On Tuesday Sivaram’s Twin Creeks unveiled the Hyperion 3, a vacuum chamber in which proton beams bombard disks of crystalline silicon at a precise depth of 20 micrometers (microns — millionths of a meter). Those proton bubbles form tiny hydrogen bubbles when the wafers are heated in a furnace to 600 degrees Celsius. Eventually the bubbles cause the wafer to fracture laterally, causing a 20-micrometer layer of silicon to flake off in a process called proton-induced exfoliation. Once a reinforcing metal backing is applied to this flake, it becomes strong enough for use in making a solar cell.

Current solar-cell production techniques use ultra-thin wire saws to slice wafers to a thickness of 200 microns. That process wastes half of the expensive crystalline silicon cylinders from which the wafers are sawed.

“The way wafers are made is still like 18th century technology,” said Sivaram.

By producing thinner wafers without wasting silicon, Twin Creeks technology produces a 90% saving of silicon, which cuts by half the cost of making a finished solar cell — even after adding the depreciation of the Hyperion 3 proton accelerator.

Twin Creeks has kept the Hyperion 3 under wraps until now to avoid tipping off would-be competitors. The accelerator is 10 times as powerful as any other ion accelerator on the market, most of which are used for physics experiments. But now that it has secured $93 million in venture capital, San Jose-based Twin Creeks is ready to publicize its technology and begin producing the accelerators at its plants in Mississippi and Massachusetts.

“Once one of them uses this, the cost advantage is going to be so large that everybody will be forced to use the same technology,” says Sivaram.

Twin Creeks’ technology is compatible with existing production lines but for one step — the texturing to promote light absorption rather than reflection. The tiny pyramid-shaped nodes placed on the surface of silicon wafers are too tall for Twin Creeks’ wafers, so Sivaram has devised a different but equally-effective proprietary anti-reflection scheme.

Each Hyperion 3 unit will cost “several million dollars”, according to Sivaram who is reluctant to give a precise figure yet. Each can produce enough silicon flakes to make 1.5 million cells per year. No machines have yet been sold but Twin Creeks is in discussions with several solar cell producers in the US and China.

Siva Sivaram received a PhD from Rensselaer Polytechnic Institute. He then spent
14 years at Intel during which he ran a high-volume outsourced semiconductor manufacturing operation as general manager of the $1 billion IC Procurement and Enabling Division. In that position Sivaram was the world’s leading consumer of semiconductor foundry wafers.

In 1999 he joined Matrix Semiconductor as COO where he played a key role in developing and mass-producing the first monolithic 3-D memory card. He was appointed general manager of SanDisk’s Pre-recorded Content Division when it purchased Matrix in 2006. From 2004 until 2008 Sivaram was a board member at Nanosolar. He left SanDisk in August 2007 to found and manage Twin Creeks Technologies as CEO.

Sivaram’s book Chemical Vapor Deposition: Thermal and Plasma Deposition of Electronic Materials (Van Nostrand Reinhold, 1995) is used as a standard graduate-level text at many US universities.