By Dr. Phil Garrou, Contributing Editor

Samsung announces 4GB HBM2 DRAM

Samsung Electronics announced that it has begun mass producing the industry’s first 4-gigabyte (GB) DRAM package based on the second-generation High Bandwidth Memory (HBM2) interface, for use in high performance computing (HPC), advanced graphics and network systems, and enterprise servers. [link]

The newly introduced 4GB HBM2 DRAM, uses Samsung’s 20nm process technology and is reportedly more than seven times faster than the current DRAM.

The 4GB HBM2 package is created by stacking a buffer die at the bottom and four 8-gigabit (Gb) core dies on top. These are then vertically interconnected by TSV holes and microbumps. A single 8Gb HBM2 die contains > 5,000 TSV holes, which is more than 36 times that of a 8Gb TSV DDR4 die, offering a dramatic improvement in data transmission performance compared to typical wire-bonding based packages.

Samsung’s new DRAM package features 256 GBps of bandwidth, which is double that of a HBM1 DRAM package. This is equivalent to a more than seven-fold increase over the 36GBps bandwidth of a 4Gb GDDR5 DRAM chip, which has the fastest data speed per pin (9Gbps) among currently manufactured DRAM chips. Samsung’s 4GB HBM2 also enables enhanced power efficiency by doubling the bandwidth per watt over a 4Gb-GDDR5-based solution, and embeds ECC (error-correcting code) functionality to offer high reliability.

Samsung also plans to produce an 8GB HBM2 DRAM package in the next 12 months. Offering designers a 95 percent space savings vs GDDR5 DRAM.

Samsung announced that production volume of HBM2 DRAM will increase over the remainder of the year.

The second-generation HBM (HBM2) technology is outlined by the JESD235A standard. It uses 128-bit DDR interface, 1024-bit I/O, 1.2 V I/O and core. Just like HBM1, HBM2 supports two, four or eight DRAM devices on a base logic die (2Hi, 4Hi, 8Hi stacks). HBM Gen 2 expands capacity of DRAM devices within a stack to 8 Gb and increases supported data-rates up to 1.6 Gb/s or even to 2 Gb/s per pin.

Continuing our look at the 2015 3D ASIP Conference…

Prismark

Brandon Prior of Prismark addressed the “Status of 2.5/3D and other high density packaging technologies”.

2.5D / Silicon Interposer is an effective fine-pitch solution to provide >10,000 die-to-die connection. Currently used for:

– ASIC/FPGA die partition

– GPU/CPU/ASIC + memory

– For L/S <2μm and vias <5μm, Si interposer is the only available approach

• Several notable production developments with 2.5 and 3D technology in 2015

– All major DRAM players with production capability of TSV memory stacks; but focus remains on “near memory” requiring extremely high bandwidth

– Si Interposer adoption by AMD for “gaming enthusiast” GPU

– Continued work with TSV for Image and other sensors for backside access

• Increased adoption of 2.5 and 3D TSV dependant on cost and alternatives

– Si Interposer most relevant to server/telecom CPU and ASIC products

– TSV for portable processors still under review, but LPDDR5 is more likely

• Companies such as Sony, Toshiba, Aptina, ST have been shipping image sensors with TSV for back side access since 2009/2010
• Sony is first to ship using die stacking “hybrid” approach in 2012/2013; economical only for 8 – 13MP designs

ADVANCED PACKAGE SUBSTRATE DESIGN RULES

• Substrate technologies continue to progress

– 10-12μm L/S in HVM for MPU

– 8μm L/S capabilities in process at Kyocera, Ibiden, Shinko and others

• Sub-5μm on organic is a challenge

– RDL technologies used in FO-WLP or Si Interposer are looking to displace build-up substrates

• Ibiden and Shinko working on “organic interposer”

– Internal qualification now down to 2μm L/S and vias 10-25μm

– Yield remains a challenge, so Si Interposer remains compelling alternative

FO-WLP MARKET STATUS

• Expectation is that Apple will proceed with TSMC InFO FO-WLP for A10 in 2016

– Tool orders and capacity seen in supply chain

– Speculation on second location/source being required

• OSATs see uptick in interest for products outside application processor

– OSATs: JCET/STATS, ASE, SPIL, Amkor, Nanium, PTI, DECA and Inotera

– Possible Customers: Marvell, Qualcomm, Mediatek, Dialog, Renesas, Infineon,

Freescale, Avago, Analog, Spreadtrum, Maxim, HiSilicon

• Most focus on smaller die/packages: 3×3 to 8x8mm

– “Large die FO-WLP remain too expensive and yield challenged”

– Expect 1 and 2 die packages with hundreds of I/O in 2016 from multiple applications and companies

– Most production of FO-WLP focused on 1-3 layer RDL at 5-15μm L/S.

– 300mm reconfigured wafers remains dominant approach for now

• Intel and Samsung remain skeptical of FO-WLP

– At this time, neither have plans to install fan out capacity

– Not seen as cost effective means to make a thinner package

Northrup Grumman / DARPA DAHI Program

After DARPA program Manager Dan Green gave an introductory presentation on the DARPA goals for DAHI (Diverse Accessible Heterogeneous Integration) [see IFTLE 206, “COSMOS and DAHI Herald the Era of 3D Heterogeneous Integration” ] Augusto Gutierrez-Aitken detailed DAHI activity in NGAS.

DAHI seeks to create circuits from various CMOS nodes with SiGe, GaN and/or InP.

They have developed a basic foundry infrastructure allowing external design teams to generate multiple technology heterogeneously integrated circuits

• Developed a process to integrate multiple compound semiconductor technologies to CMOS wafers
• Demonstrated three-technology integration between IBM 65nm CMOS, NGAS TF4 InP HBT, and NGAS GaN20 HEMT
• Demonstrated integration of third-party technology

A typical NGAS DAHI flow is shown below.

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