Category Archives: 3D Integration

Samsung announced today that it has begun mass producing the industry’s first three-dimensional (3D) Vertical NAND (V-NAND) flash memory, which breaks through the current scaling limit for existing NAND flash technology. Achieving gains in performance and area ratio, the new 3D V-NAND will be used for a wide range of consumer electronics and enterprise applications, including embedded NAND storage and solid state drives (SSDs).

Samsung 3D vertical NAND flash memory

Samsung’s new V-NAND offers a 128 gigabit (Gb) density in a single chip, utilizing the company’s proprietary vertical cell structure based on 3D Charge Trap Flash (CTF) technology and vertical interconnect process technology to link the 3D cell array. By applying both of these technologies, Samsung’s 3D V-NAND is able to provide over twice the scaling of 20nm-class planar NAND flash.

“The new 3D V-NAND flash technology is the result of our employees’ years of efforts to push beyond conventional ways of thinking and pursue much more innovative approaches in overcoming limitations in the design of memory semiconductor technology,” said Jeong-Hyuk Choi, senior vice president, flash product & technology, Samsung Electronics. “Following the world’s first mass production of 3D Vertical NAND, we will continue to introduce 3D V-NAND products with improved performance and higher density, which will contribute to further growth of the global memory industry.”

For the past 40 years, conventional flash memory has been based on planar structures that make use of floating gates. As manufacturing process technology has proceeded to the 10nm-class and beyond, concern for a scaling limit arose, due to the cell-to-cell interference that causes a trade-off in the reliability of NAND flash products. This also led to added development time and costs.

Samsung’s new V-NAND solves such technical challenges by achieving new levels of innovation in circuits, structure and the manufacturing process through which a vertical stacking of planar cell layers for a new 3D structure has been successfully developed. To do this, Samsung revamped its CTF architecture, which was first developed in 2006. In Samsung’s CTF-based NAND flash architecture, an electric charge is temporarily placed in a holding chamber of the non-conductive layer of flash that is composed of silicon nitride (SiN), instead of using a floating gate to prevent interference between neighboring cells.

By making this CTF layer three-dimensional, the reliability and speed of the NAND memory have improved sharply. The new 3D V-NAND shows not only an increase of a minimum of 2X to a maximum 10X higher reliability, but also twice the write performance over conventional 10nm-class floating gate NAND flash memory.

Also, one of the most important technological achievements of the new Samsung V-NAND is that the company’s proprietary vertical interconnect process technology can stack as many as 24 cell layers vertically, using special etching technology that connects the layers electronically by punching holes from the highest layer to the bottom. With the new vertical structure, Samsung can enable higher density NAND flash memory products by increasing the 3D cell layers without having to continue planar scaling, which has become incredibly difficult to achieve.

After nearly 10 years of research on 3D Vertical NAND, Samsung now has more than 300 patent-pending 3D memory technologies worldwide.

According to IHS iSuppli, the global NAND flash memory market is expected to reach approximately US $30.8 billion in revenues by the end of 2016, from approximately US $23.6 billion in 2013 with a CAGR of 11 percent, in leading growth of the entire memory industr

Zvi Or-Bach, President & CEO of MonolithIC 3D Inc. blogs about the appearance of 3D integration on several roadmaps.

At the recent CEA Leti day, that took place as part of Semicon West2013, Laurent Malier, Leti CEO, presented his “A look at the coming Decade.” Slide 15 of the presentation provides Leti’s vision for CMOS roadmap:

Monolithic 3D is presented on Leti’s roadmap as the technology to follow the 7nm process node.

Early this year we blogged IEDM 2012: The pivotal point for monolithic 3D ICs. It is now quite reassuring to see monolithic 3D now as part of the industry roadmap. We discussed then that memory vendors are already gearing up for volume production of the 3D NAND. And, indeed, just this summer, Toshiba has been reported to leverage the monolithic 3D cost reduction advantage (Toshiba to Build Fab for 3D NAND Flash). It only makes senses for the CMOS market to follow.

Doubters would ask why the industry would introduce a new dimension to the roadmap that has been extremely successful for over 40 years. The answer is very simple – because it is not so successful anymore. We are all aware that the escalating costs of lithography had diminished transistors cost reduction, as is illustrated in the following ASML chart:

Even if we ignore the cost issues we should remember IBM’s Bernie Meyerson caution that “atoms don’t scale.” We are quickly approaching these limit as is visible on the following Intel chart:

Accordingly, Mike Mayberry, director of component research at Intel, said at the recent IMEC Technology Forum that he“has looked down the highway of conventional silicon development and reckons things become foggy beyond about the 7-nm node.” In fact, in his March 2013 presentation “Pushing Past the frontiers of Technology” Mike Mayberry also presents monolithic 3D on his road map:

This transition was well captured in the title of 2011 IEDM keynote address by Mark Bohr, the Senior Fellow of Technology and Manufacturing Group and a Director of Process Architecture and Integration of Intel, “The Evolution of Scaling from the Homogenous Era to the Heterogeneous Era.”

Cascade Microtech, Inc. and imec today announced breakthroughs in probing stacked integrated circuits (3D-SICs), fueling an important growth engine for the semiconductor market. Through a Joint Development Agreement, Cascade Microtech partnered with imec to successfully probe 25µm-diameter micro-bumps on a wide I/O test wafer with its fully-automated CM300 probe solution utilizing an advanced version of Pyramid Probe technology. This achievement comes as part of imec’s 3D integration research program which includes other industry partners from the entire semiconductor value chain.

The 3D semiconductor market (including 3D-SIC, 2.5D interposer, and 3D WLCSP) is expected to represent nine percent of the total semiconductor value by 2017, according to Yole Développement. Logic 3D SoC/SiP (including interposer chips, APE, CPU, FPGA, wide I/O memory, etc.) will be the biggest industry using 3D platforms in the next few years. 3D applications will emerge in high-performance computing, and electronic markets such as nanotechnology and medical applications, which will benefit from the high-density integration that 3D technology offers.

The semiconductor industry is exploring new methods to increase the functionality of ICs at a smaller footprint, extending Moore’s Law. 3D-SICs offer a solution to the speed, power and density requirements demanded by future mobile electronics platforms. Through-silicon vias (TSV) used in 3D-SICs shorten interconnects between logic elements, thus reducing power while increasing performance. Within imec’s 3D integration research program, industry leaders are jointly developing design, manufacturing, and test solutions to bring this new technology to high-volume manufacturing.

Cascade Microtech’s CM300 flexible on-wafer measurement system was designed to deliver superior positioning accuracy and repeatable contact, offering a level of precision that supports both shrinking pad sizes and pitch roadmaps. The CM300 captures the true electrical performance of devices with high-performance capabilities that include low leakage and low noise. As a comprehensive probing solution employing the latest advances in Pyramid Probe technology, the CM300 has proven to meet the fine-pitch (40 µm area array), low-force (< 1gf/tip) advanced probing requirements of 3D-SICs.

“We are excited that our work with Cascade Microtech has resulted in such a breakthrough. I believe together we’ve achieved a first in the industry,” said Erik Jan Marinissen, Principal Scientist at imec in Leuven, Belgium. “We are able to hit 25 µm-diameter micro-bumps with a high level of accuracy due to the probe-to-pad alignment features of Cascade Microtech’s CM300. And advances in their Pyramid Probe technology have enabled us to probe micro-bumped wafers with 40/50 µm pitch according to the JEDEC Wide-I/O Mobile DRAM standard.”

“Cascade Microtech’s CM300 probe solution is designed to provide greater alignment accuracy to probe directly on small, fragile micro-bumps. In conjunction with a fine-pitch, low-force Pyramid Probe card, we have achieved consistent, accurate measurements on a wide I/O test wafer using a single-channel, wide I/O probe core with an array of 6 x 50 tips at 40/50 µm pitch, with the ability to shrink down to 20 µm pitches in the future,” said Steve Harris, Executive Vice President, Engineering, Cascade Microtech. “Together, imec and Cascade Microtech are enabling the ongoing future of CMOS technologies through this ground-breaking work. 3D integration will undoubtedly result in increased performance and yield while reducing overall costs.”

 

This Blog was prepared by Israel Beinglass, CTO of MonolithIC 3D Inc.

Like every Semicon West show in the past, where many experts are brought together for showing the latest and greatest semiconductor manufacturing equipment and bringing numerous seminar/panel discussions, this Semicon West of 2013 was no different. Two major issues were discussed, which on the face of it look unrelated, that caught my attention:

Progress in 3D –TSV technology, and EUV.

Obviously these two issues are very different, but they are quite similar in respect to the following:

1. As the advanced node progresses to smaller and smaller feature size we are getting closer to the “end of the roadmap” or the “end of Moore’s law”.

Going to EUV does alleviate some of the problems related to the current solution of double patterning (or quadruple in the future assuming, EUV doesn’t come to fruition soon enough).

As well, utilizing 3D devices with TSV has, in the grand scheme, a similar outcome; namely, advancing the integration via 3D structures rather than continued scaling. Though in the future, 3D devices and advanced nodes could go hand in hand.

2. The big miss of the roadmap. When one looks at some old roadmaps from a few years ago, one can ask how did we, the industry, miss by so much?

This actually reminds me of another miss from a few years ago-the low k inter-metal dielectric. Fig. 1 shows the low k dielectric roadmap trend of various ITRS published roadmaps and the prediction in 1999 that by 2004 we would be using k<2 !! Obviously we know what happened and even today 14 years later it is hard to breakthrough a k value of 2.5.

Figure 1: low k Dielectric roadmap

Figures 2 and 3 show the roadmap for EUV and TSV, respectively. Both are of 2009 vintage. In each case the prediction of the roadmap vs. actual is startling.

Figure 2: EUV roadmap

Figure 3: TSV roadmap

It is not the purpose of this blog to go over the reasons why the roadmaps of EUV and TSV missed the time table by miles, nor to blame anybody for it. There are many articles and discussions published on the subjects. Rather, I will touch on some of the highlights as well as try to make some conclusions regarding the pathway of the industry regarding these two important technologies.

EUV The EUV technology has so far gone through monumental achievements vis-à-vis the incredible tasks of developing the next generation stepper technology. The amount of engineering and resources poured into it is unprecedented in the short history of the semiconductor industry and maybe so for other industries.

It looks like as I write this blog that the only barrier for the technology from becoming a HVM tool is EUV source power that can provide a high enough throughput. Many experts doubt that it could ever be achieved; however, there are many other experts saying that it is within a reach.

TSV In this case I could see two totally unrelated issues:1) technology driven obstacles, and 2) logistics and supply chain issues.

In the case of the TSV it is one of the few cases where the “power point” presentation(s) of the TSV idea are so convincing that it is actually hard to oppose it. However, when it comes to the fine details of the technology development, there are many issues that still need to be addressed and resolved. I believe that it is just a matter of time before the technical obstacles will be resolved and a unified standardized solution emerges. However, on the other hand, I see a real problem from the point of view of logistics, cost and supply chain of the technology, and I have some doubts if it can ever be resolved. For further discussion on this issue, please refer to: 3D IC Supply Chain: Still Under Construction, and to a detailed comment in EE Time published blog and comments re. Semicon West 3D –IC TSV, provided here below.

In summary, I believe that the industry will come with a solution for EUV before TSV becomes a production technology.

Yet there is another alternative to TSV and to EUV – it is the Monolithic 3D methods. Moreover, it is very likely that monolithic 3D will reach volume production before EUV and TSV, as we already see the  NAND Flash vendors ramping up for production of 3D NAND.

Bit-growth slows while specialized stacking accelerates innovation in future memory solutions for communications, energy, and health-care. 

BY ED KORCZYNSKI, Senior Technical Editor 

By Ed Korczynski, Sr. Technical Editor

The future of 3D memory will be in application-specific packages and systems. That is how innovation continues when simple 2D scaling reaches atomic-limits, and deep work on applications is now part of what global research and development (R&D) consortium Imec does. Imec is now 30 years old, and the annual Imec Technology Forum held in the first week of June in Brussels, Belgium included fun birthday celebrations and very serious discussions of the detailed R&D needed to push nanoelectronics systems into health-care, energy, and communications markets.

3D memory will generally cost more than 2D memory, so generally a system must demand high speed or small size to mandate 3D. Communications devices and cloud servers need high speed memory. Mobile and portable personalized health monitors need low power memory. In most cases, the optimum solution does not necessarily need more bits, but perhaps faster bits or more reliable bits. This is why the Hybrid Memory Cube (HMC) provides >160Gb/sec data transfer with Through-Silicon Vias (TSV) through 3D stacked DRAM layers.

“We’re not adding 70-80% more bits like we used to per generation, or even the 40% recently,” explained Mark Durcan, chief executive officer of Micron Technology. “DRAM bits will only grow at the low to mid-20%.” With those numbers come hopes of more stability and less volatility in the DRAM business. Likewise, despite the bit growth rates of the recent past, NAND is moving to 30-40%  bit-increase per new ‘generation.’

“Moore’s Law is not over, it’s just slowing,” declared Durcan. “With NAND, we’re moving from planar to 3D, and the innovation is that there are different ways of doing 3D.” Figure 1 shows the six different options that Micron defines for 3D NAND. Micron plans for future success in the memory business to be not just about bit-growth, but about application-specific memory solutions.

Fig. 1: Different options for Vertical NAND (VNAND) Flash memory design, showing cell layouts and key specifications. (Source: Micron Technology)

E. S. Jung, executive vice president Samsung Electronics, presented an overview of how “Samsung’s Breaking the Limits of Semiconductor Technology for the Future” at the Imec forum. Samsung Semiconductor announced it’s first DRAM product in 1984, and has been improving it’s capabilities in design and manufacturing ever since. Samsung also sees the future of memory chips as part of application-specific systems, and suggests that all of the innovation in end-products we envision for the future cannot occur without semiconductor memory.

Samsung’s world leading 3D vertical-NAND (VNAND) chips are based on simultaneous innovation in three different aspects of materials and design:

1)    Material changed from floating-gate,

2)    Rotated structure from horizontal to vertical (and use Gate All Around), and

3)    Stacked layers.

To accomplish these results, partners were needed from OEM and specialty-materials suppliers during the R&D of the special new hard-mask process needed to be able to form 2.5B vias with extremely high aspect-ratios.

Rick Gottscho, executive vice president of the global products group Lam Research Corp., in an exclusive interview with SST/SemiMD, explained that with proper control of hardmask deposition and etch processes the inherent line-edge-roughness (LER) of photoresist (PR) can be reduced. This sort of integrated process module can be developed independently by an OEM like Lam Research, but proving it in a device structure with other complex materials interactions requires collaboration with other leading researchers, and so Lam Research is now part of a new ‘Supplier Hub’ relationship at Imec.

Luc Van den hove, president and chief executive officer of Imec, commented, “we have been working with equipment and materials suppliers form the beginning, but we’re upgrading into this new ‘Supplier Hub.’ In the past most of the development occurred at the suppliers’ facilities and then results moved to Imec. Last year we announced a new joint ‘patterning center’ with ASML, and they’re transferring about one hundred people from Leuven. Today we announced a major collaboration with Lam Research. This is not a new relationship, since we’ve been working with Lam for over 20 years, but we’re stepping it up to a new level.”

Commitment, competence, and compromise are all vital to functional collaboration according to Aart J. de Geus, chairman and co-chief executive officer of Synopsys. Since he has long lead a major electronic design automation (EDA) company, de Geus has seen electronics industry trends over the 30 years that Imec has been running. Today’s advanced systems designs require coordination among many different players within the electronics industry ecosystem (Figure 2), with EDA and manufacturing R&D holding the center of innovation.

Fig. 2: Semiconductor manufacturing and design drive technology innovation throughout the global electronics industry. (Source: Synopsys)

“The complexity of what is being built is so high that the guarantee that what has been built will work is a challenge,” cautioned de Geus. Complexity in systems is a multiplicative function of the number of components, not a simple summation. Consequently, design verification is the greatest challenge for complex System-on-Chips (SoC). Faster simulation has always been the way to speed up verification, and future hardware and software need co-optimization. “How do you debug this, because that is 70% of the design time today when working with SoCs containing re-used IP? This will be one of the limiters in terms of product schedules,” advised de Geus.

Whether HMC stacks of DRAM, VNAND, or newer memory technologies such as spintronics or Resistive RAM (RRAM), nanoscale electronic systems will use 3D memories to reduce volume and signal delays. “Today we’re investigating all of the technologies needed to advance IC manufacturing below 10nm,” said Van den hove. The future of 3D memories will be complex, but industry R&D collaboration is preparing the foundation to be able to build such complex structures.

DISCLAIMER:  Ed Korczynski has or had a consulting relationship with Lam Research.

This article originally appeared on SemiMD, part of the Solid State Technology network. 

Rudolph Technologies, Inc., a provider of process characterization, photolithography equipment and software for the semiconductor, FPD, LED and solar industries, today released three new application-specific configurations of its industry-leading NSX 320 Automated Macro Defect Inspection System. The suite includes specially-designed configurations for wafer level packaging, 2.5D (interposer) and 3DICs using through-silicon via (TSV) as interconnects. The first NSX 320 Metrology System for wafer level packaging shipped in June to a major outsourced assembly and test (OSAT) facility in Asia.

“These new application-specific configurations of our established NSX 320 System are designed to address the emerging need for fast, precise three-dimensional (3D) measurements in the rapidly growing advanced packaging market sector,” said Rajiv Roy, vice president of business development and director of back-end marketing at Rudolph Technologies. “We have completed the integration of 3D measurement sensors, recently acquired from Tamar Technology, into the NSX System. Tamar’s sensor technology is well recognized and widely used, and integrating it into the NSX 320 System adds critical capability required for enabling advanced packaging applications such as copper pillar bumping and TSV.”

The NSX 320 wafer level packaging configuration is designed to measure film thickness (polymers, photoresist, glass), thin remaining silicon thickness (RST), surface topography, copper pillar height and solder bump height. The advanced wafer level packaging configuration adds measurements of the wafer profile (warp and bow), total stack thickness and thick/thin RST (bonded wafer before and after grind). The 3DIC configuration is capable of all the above measurements plus via depth, trench depth, bonded wafer TTV and adhesive layers.

Roy stated, “3DIC device volume is forecasted to grow to $38.4B by 2017, according to Yole Développement. Rudolph is positioned to address the growth requirements for wafer level packaging, as well as 2.5D and other advanced packaging technologies, with industry-proven metrology tools that offer superior speed and measurement solutions.”

In 3D integration, wafers are thinned, stacked and connected to one another with through silicon vias (TSVs). The process of wafer thinning and TSV formation typically involves the use of a wafer bonding/debonding technology, where the wafers are bonded onto a carrier substrate – either silicon or glass – processed, and then debonded. The bonding/debonding step can be tricky because the bond has to be strong enough to withstand relatively high temperature processes and polishing steps, but not so strong as to make debonding difficult. It’s also critical that minimal stress be introduced to the device wafer during the debonding step (which can involve sliding or peeling), and that no residue remain. Room temperature debonding is also desirable.  

A variety of techniques and materials have been developed to successfully achieve bonding/debonding, but Tony Flaim, chief technology officer of Brewer Science (Rolla, MO) says they are still too complicated. Brewer Science introduced the ZoneBOND technology in the 2008/2009 timeframe, and it has been implemented by tool suppliers such as EVG and SUSS. In an interview at The ConFab in June, Flaim said: “This is one of the industry’s first methods for separating the carrier from the bonded pair under low stress, low temperature conditions. It can be done at room temperature. We’ve had customers adopt that technology and are using it for some low volume production.”

High volume manufacturing of 3D integration with TSVs might not occur for another two years. To date, TSVs have been primarily used in limited applications such as image sensors where back-to-front contact is required. The first true stacked, 3D integrated device to go into production will likely be the Hybrid Memory Cube sometime next year.

“The industry is at best in low volume production with things like high density interposers and a few stacked devices, but for the most part we really haven’t seen anyone going into high volume manufacturing with the technology,” Flaim said.  “What we’re trying to do, until that time arrives, is move on to a third generation of technology that will basically involve all the steps in the process and simplifying more than they are now.” He said that with ZoneBond and competing technologies, they have six basic process steps, but at a more detailed level, you can see as many as 20-25 steps. “Some of those steps are lengthy, they can be minutes or even up to hours in some cases to perform. We believe that for temporary wafer bonding technology and in fact for 2.5D and 3D integration to occur, we’re going to have to have a much simpler, more reliable, more cost-effective process. That’s really our goal for the next two years,” Flaim said.

In terms of ideal process temperature, Flaim said the bulk of their customers are working in the range of 250-260°C, but it’s clear that they want to go higher. Dielectric cure processes and deposition processes, for example, would yield better material properties when performed at a higher temperature.  “We’re trying to move our whole materials set to have thermal stability at 280, 300°C or maybe even beyond. But the trick is still getting them back apart. That’s where ZoneBond and some of the other release technologies that we’re working on now will really provide the advantage.  You decouple the thermal stability from how you separate from the stack. You can still be operating under a low stress, low temperature condition when you take the bonded structure apart, but the materials within the structure are surviving the high temperature.”

See the video interview of Tony Flaim at The ConFab by clicking here.

Engineering samples of The Hybrid Memory Cube (HMC) are expected this summer, with high volume manufacturing coming next year. It will be one of the first high volume devices employing 3D integration and through silicon vias (TSVs), employing a bottom logic layer and 4-8 stacked DRAM layers.

The HMC is the result of a consortium formed in late 2011 by Micron, Samsung, Altera, Xilinx and Open-Silicon to define an industry interface specification for developers, manufacturers and architects of high-performance memory technology. The consortium has grown to 110 members, including SK Hynix, IBM and ARM. Analysts are projecting the TSV-enabled 3D market to be a $40billion market by 2017, or roughly about 10% of the global chip business.

We caught up with Micron’s Scott Graham, General Manager, Hybrid Memory Cube, at Semicon West. “Today, we’re very close to delivering our engineering samples this summer to our lead customers that are taking the technology into their system designs,” Graham said.  The lead applications are in high performance computing, such as supercomputers, as well as the higher end networking space. “Those will be the early adopters. As we move forward in time, we’ll see that technology evolve as costs come down for TSVs and manufacturing technology, it will enter into future space where traditional DDR type of memory has resided. Beyond DDR4, we can certainly see this of memory technology being a mainstream memory,” Graham said.

Since the HMC is an open specification in terms of the architecture of the device, it will be up to each memory manufacturer to decide how it might be customized and manufactured. “The way it’s done today is we source the substrate, we source the logic layer and then we bring those in-house and we complete the finishing of those logic wafers as well as all the slicing, dicing, stacking, assembly and test,” Graham said. “What we end up providing for the customer is a known good cube, or known good piece of memory, just like we would if it was a DDR device or wide I/O device,” he said. He added that the HMC is designed so that it has not only the repair capability during manufacturing but also out in the field. “It’s very flexible and very robust, so reliability is very high with this device,” he said.

The consortium delivered its first specification earlier this year. “We’ve since extended the consortium to work on both future generations of the HMC technology in both the short-reach and ultra-short reach configurations,” Graham said.

The HMC was designed to get high density and high bandwidth in a relatively small package. The team adopted an off-the-shelf SERDES I/O and that’s based on IBM’s 32nm process. “With that, we can achieve 10 Gbps, 12.5 Gbps, or 15 Gbps for those SERDES links,” Graham said. “If you look at a 2 GByte or a 4GByte HMC device, those first devices will deliver a total aggregate bandwidth of 160GBytes/sec. I want to emphasize those are bytes not bits. It’s a very high bandwidth and low energy per bit device that is something that can be designed into a multitude of systems.”

The consortium has several generations of the HMC device planned (this summer’s engineering samples are Gen2). “As we move forward, you’ll see us moving into the 28 Gbps SERDES as far as the I/O goes,” Graham said. Bandwidths are going to be 320 Gigabytes/sec and higher, and the density will be in 4Gbyte and 8 Gbyte configurations.

Graham said one of the main challenges they had to overcome was the stacking. “We’re stacking a logic layer on top of a substrate and then four to eight DRAM on top of those logic layers,” he said. “We have over 2000 TSVs in this package and it was a challenge to stack these ultrathin die and make sure that what we end up with is a high performance and very reliable package.” Graham declined to comment on the exact TSV process flow used at Micron, saying only that it was leading edge. “We had to make sure our equipment partners were up to speed and could deliver us the technology that would allow us to manufacture this in high volume,” he said.  

Because customer can customize the HMC design, another challenge it to make sure that the design capabilities are available at the foundry for that logic layer, Graham said.  

Heat dissipation in the device is achieved through a metal lid, and through the TSVs which acts as chimneys (in addition to conducting electricity). The photo shows two Gen2 HMC devices. The larger one, in a 31mm x31 mm package, is a 4 link device that will achieve 160 Gig-bytes per second. The smaller one is a two link device capable of 120 Gigabytes/sec, measuring 16mm x 19.5 mm. “Both are being manufactured now in our plant and we’re doing the whole debug phase,” explained Aron Lunde, program manager, DRAM solutions group at Micron in Boise. He said the metal lid was in contact with not only the top layer, but different internal layers. “We call it an integrated heat spreader. It makes contact at more than one level and that’s what really helps,” he said.

Although manufacturers such as Micron, Samsung and SK Hynix must now handle the manufacturing, assembly and test process, Graham believes that it could eventually evolve to the point where select foundry partners would be able to provide volume manufacturing services for these HMC cubes.

Graham said DDR4 will likely be the last DDR device. “Beyond DDR4, you have to move to managed memory like HMC technology,” he said.  “We’re solving the memory wall problem with HMC-like architecture and what’s really going to be happening in the future is that you’ll be running into a CPU wall. That’s going to be the barrier to system progress as we move forward.”

Graham expects some challenges with scaling of conventional memory at sub-20nm process nodes. “We get into physical challenges of meeting the timing requirements and the 12 pages of JEDEC specifications to be able to yield properly and to be able to provide a cost-effective memory device moving forward,” he said.  

Although the HMC is now designed around DRAMs, Graham said it would be possible to use other types of memories, and even a mixed set of memories. He noted Micron is looking at alternatives to the conventional DRAM cell, such as spin torque and resistive memories. “Micron is investing heavily in research in those technologies and of course the HMC team here at Micron is looking at future technologies that we can take HMC architecture and be able to utilize different DRAM or even flash types of memory,” he said. “As the technology matures and it becomes lower cost, we can see this technology certainly evolving into more global applications and utilizing different memory types in that stack – and perhaps even multiple memory types in that stack.”

HMCs could eventually make their way into mobile devices, but Graham said that is likely to be three or four years away. Mobile applications presently employ low power DDR3 solutions, which will be used for several years. “We’ll see quite a few interesting designs start spinning when the mobile folks see they can differentiate with a managed memory solution. It’s not going to be HMC as we know it today, it will have to be optimized for mobile,” Graham said.

Leaders of research consortia from around the world sat down to share updates and insights with SEMICON West attendees on Wednesday morning. In a panel led by SEMI President Karen Sevala, four executives from SEMATECH, CNSE, CEA-Leti and imec discussed their companies’ focus and progress on lithography, 3D stacking and ICs, memory and logic and more.

Lithography was a huge project and priority to three out of the four consortia represented and was the first topic brought to the panel by Sevala.

“Lithography is one of the highest priorities of our industry,” said Luc Van den hove, CEO of imec.

Van den hove said that he was very positive about EUV, confident that it was going to be available very soon. Daniel Armbrust of SEMATECH echoed Van den hove’s sentiments, reinforcing the importance of EUV’s availability for the continuation of Moore’s law.

“EUV must happen,” Armbrust emphasized to the crowd. SEMATECH’s EUV program, he said, has been focused on taking the manufacturing technology and making sure it’s ready for high volume production.

“The technology is in relatively decent shape,” Armbrust said. The challenge, he explained, is defect performance.

3D stacking and TSVs were also a hot topic. Michael Liehr of CNSE said, while important, 3D has been slower to take off than expected.

“The cost and implementation are still a lot more extensive than typical packaging solutions,” Liehr said. “We hope that this technology will lead to a leap in performance.”

Van den hove shared that imec believes that 3D stacking and ICs are very important technologies, and that the consortia started their programs about ten years ago.

“One of the biggest challenges with this technology is that we have two worlds that need to meet,” said Van den hove, in an effort to encourage industry collaboration.

Concerning memory and logic, Armbrust said that SEMATECH has been moving to 3D structures and focusing on the 7nm node, which has inevitably led to changes in device structure.

“The most promising candidate,” said Armbrust, “is replacing silicon with a material that provides III-V compounds.”

 

Dow Corning announced Monday that it is among the newest member organizations to join imec, a leading research center for the advancement of nano-electronics. The announcement signals expanded opportunities for both organizations to combine their expertise toward the development and broader adoption of 3D integrated circuit (IC) packaging technologies, wherein IC chips are stacked in vertical 3D architectures.

“This move is a natural and strategic step for Dow Corning and imec, as we both believe collaborative innovation is as critical to industry leadership as native expertise,” said Andrew Ho, global industry director, Advanced Semiconductor Materials at Dow Corning. “Our access to imec’s world-class resources and expertise will not only help us further refine our unique temporary bonding solution, it will allow imec to leverage that solution to advance integration of the 3D IC packaging process that they’ve been developing for years.”

Yet, before 3D IC fabrication can see broader adoption, it will require innovative advances in materials and processing technologies.

One of the key challenges imec is tackling is the bonding of the device wafer to a carrier wafer, prior to wafer thinning, and the safe debonding of the thin wafer after completion of backside processing. This was Dow Corning’s goal when designing its Temporary Bonding Solution, aims at simple processing using a bi-layer concept comprising an adhesive and release layer. The technology also enables room-temperature bonding and debonding processes based on standard manufacturing methods.

Together with imec, Dow Corning will explore its temporary bonding CMOS-compatible solution for 3D Through-Silicon-Via (TSV) semiconductor packaging. The collaboration will aim to further expand the technology’s ability to achieve simple, cost-effective bonding-debonding techniques compatible with standard manufacturing processes.

“Imec’s precompetitive programs are an essential platform for industry leaders to share the risk and cost of advanced research. As one of the semiconductor industry’s most proven pioneers in advanced silicone-based solutions, Dow Corning brings valuable materials and processing expertise to imec’s global network of innovators – as well as a key enabling technology for TSV fabrication,” said Eric Beyne, program director 3D System Integration at imec. “We look forward to collaborating closely with our newest member organization as we drive the next stage of 3D integration, and help ensure compatiblity of the proposed thin wafer carrier solution with advanced, sub-10-nanometer CMOS device technologies.”

Imec exhibits at SEMICON West, July 9-11, 2013 at booth 1741, South hall.