Lam's New Products Deliver Critical Capability for Building 3D NAND Memory Devices

As reported today by Lam Research Corp. : Lam Research Corp. today unveiled its latest thin film deposition and plasma etch products for 3D NAND fabrication. As memory customers begin ramping production of these new devices, greater process control is needed for cost-effective manufacturing. Lam's new systems address this need for three of the most critical steps in forming 3D NAND memory cells: stack deposition (VECTOR® Q Strata(tm)), vertical channel etching (2300® Flex(tm) F Series), and tungsten wordline deposition (ALTUS® Max ICEFill(tm)).

The 3D NAND memory structures now moving to production involve numerous pairs of stacked films. Process variability on both the horizontal and vertical planes must be minimized for critical steps so that each memory cell in the final device delivers similar performance. Otherwise, variation in one step can be transferred and multiplied in subsequent steps, compounding errors and leading to poor device performance and low product yield. With 40 or more pairs of films in the stack, carefully managing even slight process fluctuations is essential. Lam's new products address these stringent control requirements.

As memory customers begin ramping production of these new devices, greater process control is needed for cost-effective manufacturing. Lam's new systems address this need for three of the most critical steps in forming 3D NAND memory cells: stack deposition (VECTOR® Q Strata™), vertical channel etching (2300® Flex™ F Series), and tungsten wordline deposition (ALTUS® Max ICEFill™).

The new VECTOR Q Strata PECVD (plasma enhanced chemical vapor deposition) system is used for depositing multilayer film stacks. For this critical 3D NAND process step, the system can perform both oxide/nitride (ONON) and oxide/polysilicon (OPOP) film stack deposition. To deposit the ultra-smooth, uniform films required to avoid compounding errors, the system's matched chambers deliver superior defectivity, film stress, and wafer bow performance. In addition, the VECTOR Q Strata also provides industry-leading productivity with the highest throughput per square meter of fab area available today. As the number of layers in these stacks continues to grow, high productivity is increasingly important for cost-effective production.

Once the stack of paired films is deposited, Lam's 2300 Flex F Series dielectric etch product is used to create a vertical channel through the stack. The new system can etch through high aspect ratio structures with minimal distortion or sidewall damage, while also tightly controlling etch profile uniformity across the wafer. This capability is critical since even small deviations can cause channel dimensions to differ from cell to cell, resulting in device performance variation. A proprietary high ion energy source with modulation of energies enables these results.

The latest in Lam's market-leading tungsten deposition product line, the ALTUS Max ICEFill system controls variability by providing void-free fill of the geometrically complex 3D NAND wordlines. Using a proprietary filling technique, the new system creates the tungsten wordlines with an inside-out atomic layer deposition (ALD) process. The ICEFill process completely fills the lateral (horizontal) lines without any voids, while at the same time minimizing deposition in the vertical channel area. As a result, both electrical performance and yield are enhanced.

"By focusing on collaboration at Lam Research, we are innovating faster and more effectively to deliver the enabling capabilities our customers need," said Rick Gottscho, executive vice president of Global Products. "With the support and expertise of our customers and research partners, Lam now offers three products -- VECTOR Q Strata, 2300 Flex F Series, and ALTUS Max ICEFill -- that are playing critical roles in the development and production ramp of 3D NAND memory devices."

ALE - Atomic Layer Etch emerges for 3D NAND, sub-20nm DRAMs and FinFETs

Atomic Layer Etch Finally Emerges - is a interesting blog post by Mark LaPedus (Executive Editor for manufacturing at Semiconductor Engineering) that you should really read if you want some insight into why we need ALE and why it has been difficult to develope this etch technique.

 

After nearly two decades of being confined to R&D labs, equipment makers are placing big bets on this next-gen plasma etch technology.

 

[...]

 

Lam’s Lill agrees that ALE will not replace RIE. “We will offer both technologies in one reactor,” Lill said. “We think they will be complementary for certain applications. But we are already seeing the transition (to ALE) in certain applications.”

 

ALE could be used for 3D NAND, sub-20nm DRAMs and finFETs, but there are still some challenges before ALE is running in the production fab. “There are still three grand challenges left,” Lill said. “One is that there are no secondary unintended reactions for ALE. For example, we don’t want extreme UV radiation in the reactor. Second, we want the unit steps to be discrete. And finally, we need self-limiting single unit steps. They are very difficult to find.”

 

Read more here and additional comments from experts from LAM Research, Applied Materials and Sematech : http://semiengineering.com/atomic-layer-etch-finally-emerges/ 

 

Illustration of the process steps in a plasma-enhanced ALE cycle for a silicon film etched by chlorine and argon. (Source Electroiq)

 

[please note that we used to know ALE as Atomic Layer Epitaxy until ALD - Atomic Layer Deposition took over]