拆解揭秘三星手机中的最新技术

拆解与分析咨询公司Chipworks最近为寻找PCM（相变存储器）芯片拆解了一些三星GT-E2550 GSM手机。这些手机在美国购得，原本应该销往欧亚市场。

Chipworks公司的Rajest Krishnamurthy在其技术博客上说他们在部分手机中发现了采用65纳米工艺制程、多芯片封装的512M PCM芯片。

PCM有潜力替代非易失性（Non-Volatile）闪存技术，这些三星GSM手机所采用的三星产PCM芯片是该技术目前已知的唯一商品化应用。由于闪存生产不断扩张，以及PCM缺少实际运用，PCM的发展已经遭到怀疑。

Chipworks的博文中写道：“几部GT-E2550手机的主PCB板上有一块多芯片封装（MCP）的NOR闪存芯片，封装标示为K5N1229ACD。不过出乎我们意料的是，有些同品牌、同标识手机的PCB板采用了PCM MCP芯片，单元封装标识为K571229ACM。而其它NOR闪存封装标示为K5N122ACD。”

这一发现印证了UBM Techinsights于2010年12月发布的报告（参阅电子工程专辑报道：UBM最新拆解：神秘手机惊现PCM）。

现已被美光收购的Numonyx公司曾在2008年推出过一款90纳米制程128M容量的PCM芯片。该产品在2010年4月加入Omneo并行、串行访问存储器产品线。但Numonyx从未宣布过任何设计选择或量产消息。Numonyx也曾表示将要开发45纳米工艺的1G PCM芯片，预计在2010年发布，但随后没有任何关于出样或量产的消息。

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Chipworks拆解了一些三星GT-E2550手机，和预想的一样，所有这些手机都有相同的主PCB板。部分GT-E2550手机的主PCB板上有一块MCP封装的NOR闪存芯片，封装标示为K5N1229ACD。但出乎意料的是部分同型号手机却采用了MCP封装的PCM存储芯片，标示为K571229ACM，其它手机则采用K5N122ACD闪存芯片。

图1.三星GT-E2550手机

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图2是来自两部三星GT-E2550手机的主电路板照片，分别采用NOR闪存和PCM MCP芯片。图中的NOR闪存和PCM MCP芯片都采用56球FBGA封装，尺寸同为9.2 mm（长）x 8.2 mm（宽） x 1.1 mm（高）。56球也采用相同的结合方式置于底部。如图3所示。

图2.来自两部三星GT-E2550手机的主电路板照片。上方采用NAND芯片，下方采用PCM芯片

图3.K5N1229ACD NOR闪存封装底部（左），K571229ACM PCM封装底部（右）

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图4展示了K5N1229ACD NOR闪存与K571229ACM PCM芯片封装的X光侧视图。图片显示出两块芯片朝向不同的方向。拆开之后我们发现PCM MCP芯片由一块512M PCM裸片与一块128M UTRAM（8Mx16）联合封装而成；而NOR MCP闪存则由一块512M NOR闪存裸片与一块256M（16Mx16）UTRAM联合封装而成。为什么NOR闪存需要的UTRAM容量两倍于PCM这个问题值得推测。512M PCM与NOR闪存的裸片面积均为相同的42.8 mm2。

图4.PCM与NOR闪存封装的X光侧视图

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图5和图6分别是KPS1215EZA PCM和K8S1215EZC NOR闪存裸片的照片。

该PCM裸片采用四层Al、65纳米BiCMOS工艺制程加工而成；NOR闪存裸片采用两层Al与单层Cu、65纳米工艺加工而成。

图5.KPS1215EZA PCM裸晶照片

图6.K8S1215EZC NOR闪存裸晶照片

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图7和图8分别展示了PCM裸片与NOR闪存裸片的SEM剖面图。对比二者的存储元件尺寸，PCM为0.026μm2，比NOR闪存的0.032μm2小19%。想必NOR闪存，PCM的结构更接近NAND闪存，应该便于未来扩大生产。

图7.KPS1215EZA PCM裸晶SEM剖面图

图8.K8S1215EZC NOR闪存裸晶的SEM剖面图

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点击参考原文：Chipworks tears down Samsung PCM phone

《电子工程专辑》网站版权所有，谢绝转载

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Chipworks tears down Samsung PCM phone

Peter Clarke

Reverse engineering and analysis consultancy Chipworks Inc. has torn down a few Samsung GT-E2550 GSM cell phones bought in the United States but intended for different geographic markets in Asia and Europe while on the hunt for phase-change memory ICs.

According to a technology blog by Rajest Krishnamurthy from Chipworks (Ottawa, Ontario) 512-Mbit phase-change memory (PCM) implanted in an approximately 65-nm manufacturing process was found in a multi-chip package in some of the phones.

The Samsung-produced PCM deployed in a Samsung GSM phone is the only known commercial deployment of a memory technology that had shown promise as a potential replacement for flash non-volatile memory technology. The continued scaling of flash memory and lack of uptake has cast doubt on the viability of PCM.

"The main PCB from a few of the GT-E2550 phones had a NOR flash multichip package (MCP) chip, with package marking K5N1229ACD. However, to our surprise, the PCB from some of the phones with specific branding name and with specific marks on the product label, used a PCM MCP memory chip with package marking K571229ACM, whereas others used a K5N122ACD NOR flash part," according to the Chipworks posting.

This confirms similar work by UBM Techinsights reported in December 2010.

Numonyx, subsequently acquired by Micron Technologies Inc., released a 90-nm 128-Mbit phase-change memory in 2008, which it formalized as the Omneo range of serial and parallel access memories in April 2010. But the company has not said anything about design wins or volume production. Numonyx was also said to be developing a 1-Gbit phase-change memory in a 45-nm process, but there has been no news of sampling or volume production for a device that was expected to appear in 2010.

The posting includes package shots, x-ray photographs of the multi-chip packages and die shots of the equivalent phase-change memory (identified on the die as KPS1215EZA) and NOR flash (identified on the die as K8S1215EZC).

Comparing Samsung NOR-Compatible PCM with Samsung NOR

Figure 1 Front-side image of Samsung GT-E2550

When some of the GT-E2550 phones were torn down, as expected, all the phones contained identical main printed circuit boards (PCBs). The main PCB from a few of the GT-E2550 phones had a NOR flash multichip package (MCP) chip, with package marking K5N1229ACD. However, to our surprise, the PCB from some of the phones with specific branding name and with specific marks on the product label, used a PCM MCP memory chip with package marking K571229ACM, whereas others used a K5N122ACD NOR flash part. Figure 2 is a photograph of the main circuit boards extracted from two different Samsung GT-E2550 cell phones that had the NOR flash and PCM MCP chips.

Figure 2 Main Circuit Boards Extracted From Two Different Samsung GT-E2550 GSM Cell Phones. At top is the NAND version and at bottom the PCM version

The NOR flash and PCM MCP packages are both 56 ball FBGA packages, have the same package dimensions of 9.2 mm (length) x 8.2 mm (width) x 1.1 mm (thick) and had ball bonds laid out identically on their back, as shown in Figure 3.

Figure 3 K5N1229ACD NOR flash (left) and K571229ACM PCM (right) Package Bottoms

Side View X-ray analysis of the K5N1229ACD NOR flash and K571229ACM PCM packages shown in Figure 4, reveals that we have two chips in each, but oriented in two different directions. When we de-capsulated the parts we found that the PCM MCP is a 512 Mbit PCM die co-packaged with a 128 Mbit UTRAM (8Mx16), while the NOR flash MCP package is a 512 Mbit NOR flash die co packaged with a 256 Mbit (16Mx16) UTRAM. One can speculate as to why the NOR flash would use UTRAM with double the memory capacity as opposed to the PCM.

Figure 4 Side View X-ray images of PCM and NOR Flash Package

Both the 512 Mbit PCM and the NOR flash die had identical die areas of 42.8 mm2 within the die seals. Figure 5 and Figure 6 show the die photographs of the KPS1215EZA PCM and K8S1215EZC NOR flash die, respectively.

Figure 5 KPS1215EZA PCM Die Photograph

Figure 6 K8S1215EZC NOR Flash Die Photograph

The PCM die is manufactured using 4 layers of Al, in a 65 nm BiCMOS process, while the NOR flash die is manufactured with 2 layers of Al and a single layer of Cu, in a 56 nm process. Figure 7 and Figure 8 show SEM overview cross sections of the PCM and NOR flash dies, respectively. Comparing the memory cell areas, the PCM has 19% smaller cell area of 0.026 μm2 compared to the 0.032 μm2 cell area for the NOR flash cell. The PCM has anarchitecture more like a NAND flash than NOR flash, which should facilitate future scaling.

Figure 7 SEM Cross Section Overview of KPS1215EZA PCM

Figure 8 SEM Cross Section Overview of K8S1215EZC NOR Flash Memory