技术文摘：从对比最新芯片入手，解读NAND闪存区域两强争霸

SamSung and Toshiba show the NAND that puts manufacturer to dominating for a long time to grow quickly twice this keep the market. Among them SamSung belongs to the biggest player, adopt advanced technology measure ceaselessly, in order to maintain competitive dominant position. This period the design is uncovered basically will be opposite closely of these two companies newest shine put undertake comparative, at the same time also of the company such as give attention to two or morethings and Hynix, beautiful light and Intel prep according to. From the point of the history, samSung centers key of research and development in monolayer unit (on SLC) . In SLC framework every shine put unit to be able to store only the information of a bit. And Toshiba is in change advanced technology science and technology to the respect likewise active, nevertheless its competition advantage depends on multilayer and unit (MLC)NAND shows the design experience that keeps a field and ability. MLC shows presence every location stores the information of 2 bit, make Toshiba can store on the silicon chip that gives an area more bit information, reduce manufacturing cost below the circumstance with memory established dimension. Accordingly, although Toshiba lags behind possibly on craft science and technology at SamSung, but be in naked piece still be to get the person that run on density. The MLC of Toshiba shines put already counted era via all previous classics, the 8Gb that includes what release recently to use 70nm technology among them shines put. 2005, toshiba ever used the 73nm science and technology of 90nm science and technology and SamSung to spread out fight hand-to-hand. Toshiba 90nm MLC shows the bit density that put to be 29Mb/mm2, 73nm of far outclass SamSung shows the bit density of the 25.8Mb/mm2 that put. When packing density is secured, toshiba is had even smaller than SamSung naked a dimension. For example, the 4Gb NAND that Toshiba 90nm craft produces shines those who put is naked piece dimension is 138mmsupgt;2, compare to it, the 4Gb NAND that SamSung 73nm craft produces shines put dimension to be 156mmsupgt;2. This makes Toshiba has competition ability more in cost respect. Using at filestore respect, NAND shines put inevitable ground to face price war, we often also are heard, only price leader just can win IPod design to win the bid. Although MLC in some way is obtained,comparative approbate, but the wild demand that puts chip to shining nowadays blurred the line of sight of industry. Memory blocks manufacturer to need the chip with low price, but they also need to offer money steadily. Use at this reason just about, according to the report, kingston already bought SLC chip to undertake exchanging views as the 2nd supply of goods and SamSung last year. When they discuss this agreement, the cost that ignores MLC plan right-down wants than SLC low 30% . Long-term since, samSung is in advertise MLC of SLC and rather than NAND to shine put, mixed 2004 nevertheless this company referred congress of circuit of international solid state 2005 (the paper of MLC science and technology that submits on ISSCC) , indicate the viewpoint of this company produced change. Although go up to still do not have any concerned MLC to show the sale information that store in the website of SamSung, but this company already was produced really gave 4Gb MLC NAND to shine put chip. Although we already undertook an analysis to the sample of this chip, but it is very difficult that its sample should be found to remain the same in the market. Its are naked piece dimension is 156mm2, the MLC that uses 90nm technology with Toshiba 4Gb NAND shines put photograph comparing, big still 18mm2, because this wants can with Toshiba photograph compare, samSung issues science and technology of generation NAND MLC to go up to still need to improve in its. Besides SamSung, the other memory manufacturer such as Hynix also is shining to MLC put stride. Although Toshiba is depended on,the dominant position is held on MLC science and technology, the NAND of science and technology of MLC of Intel of capable also union and beautiful light shows the joint ventures IM Flash of Er of Dan Ying spy and beautiful optical science and technology put, shine in MLC NAND thereby put section swift and violent development. Ability is not MLC Shan Cunke to was not worth, actually, using advanced technology to produce MLC Shan Cunfang face difficulty is heavy. As the gradual progress of Shan Cunke ability, in float bar (the charge gross of the memory in Floating Gate) decreased, make detect the information of memory becomes more difficult, be opposite especially MLC chip, it needs to identify 4 voltage value, and rather than two. Nevertheless, according to the report, toshiba can assure to adopt plan of as same as 90nm science and technology code error correction in 70nm craft. This shows this company and shrink without science and technology of rein in MLC put pace, it is the least now. In addition, shine with SLC put photograph comparing, MLC shows existence of existence dependability respect to be not worth. Although to consumer, dependability is not the core problem that they pay close attention to, but the market is being consumed in other is a malpractice apparently however. SamSung provision rolls out the 4Gb SLC NAND that uses 65nm technology to shine put, its dimension is more compact than using the parts of an apparatus of 73nm craft to be a bit. The problem that causes from this is: Shrink in craft put an aspect whether already at the end of one's wits? If real case is such really, so the circumstance appears more advantageous to Toshiba, because at present it has produced the MLC of a 70nm craft,shine put. As expedient, samSung turns to the chip of 65nm craft to be able to be the same as the 90nm MLC competition of Toshiba immediately probably. But the science and technology of 70nm craft 8Gb MLC of Toshiba already gained great success, realized the bit density of 56.5Mb/mm2, the rated bit density that compares 31.3Mb/mm2 of SamSung 65nm craft wants tower above 80% . A few reports that are not out Toshiba company are alluded, this company will have crossed 65nm craft, turn to the 16Gb with 50-60nm broad line to shine directly put. Of course, come true in the success under the craft with 65nm broad line, still obstacle of a few science and technology remains to overcome. 12 3 of on one page issues one page

三星与东芝这两家闪存制造商长期统治着迅速增添的NAND闪存市场。其中三星属于最大的玩家，不竭采用前进前辈工艺尺寸，以维持竞争劣势。本期设计揭密将首要对这两家公司的最新闪存进行比较，同时也兼顾与Hynix、美光和英特尔等公司的对比。

从历史来看，三星将研发重点集中在了单层单元(SLC)上。SLC架构中每个闪存单元只能存储1个比特的信息。而东芝在转向前进前辈工艺科技方面同样积极，不外其竞争劣势在于多层单元(MLC)NAND闪存方面的设计经验和能力。MLC闪存在每个存储单元存储2个比特的信息，使得东芝可在给定面积的硅片上存储更多的比特信息，并在存储器尺寸既定的情况回升低出产本钱。是以，尽管东芝在工艺科技上可能落伍于三星，但在裸片密度上仍是领跑者。

东芝的MLC闪存已履历经数代，其中包括新近公布的采用70nm工艺的8Gb闪存。2005年，东芝曾采用90nm科技与三星的73nm科技睁开肉搏。东芝90nm MLC闪存的比特密度为29Mb/mm2，远远高于三星73nm闪存的25.8Mb/mm2的比特密度。

在存储密度固按时，东芝甚至领有比三星更小的裸片尺寸。例如，东芝90nm工艺出产的4Gb NAND闪存的裸片尺寸为138mmsupgt;2，与之比拟，三星73nm工艺出产的4Gb NAND闪存尺寸则为156mmsupgt;2。这使得东芝在本钱方面更具竞争力。在用于文件存储方面，NAND闪存不成避免地面临价钱战，咱们也经常听到，只有价钱带领者才会博得iPod设计中标。

当然MLC在某些方面获得相当的认可，但现在对闪存芯片的狂热需求朦胧了业界的视线。存储卡制造商需要价钱低廉的芯片，但他们也需要不乱的供货。恰是用于这个起因，据报道，客岁Kingston已就采办SLC芯片作为第二货源与三星进行了商谈。他们参议该和谈时，全然掉臂MLC方案的本钱比SLC要低30%。

长期以来，三星都在宣扬SLC而非MLC型NAND闪存，不外2004年和2005年该公司提交给国际固态电路大会(ISSCC)上提交的MLC科技论文，标记着该公司的概念发生了转变。当然在三星的网站上仍旧没有任何无关MLC闪存的营销信息，但该公司简直已出产出了4Gb MLC NAND闪存芯片。当然咱们已对该芯片的样品进行了分析，但要在市场中找到其样品仍旧很是困难。其裸片尺寸是156mm2，同东芝采用90nm工艺的MLC型4Gb NAND闪存比拟，仍是大了18mm2，是以要能与东芝相匹敌，三星在其下一代NAND MLC科技上还需要改良。

除了三星，Hynix等其他存储器制造商也在向MLC闪存迈进。当然东芝凭借多年的科技堆集而在MLC科技上占有劣势，但英特尔与美光科技的合伙企业IM Flash也有能力连系英特尔MLC科技与美光的NAND闪存，从而在MLC型NAND闪存区域迅猛成长。

MLC闪存科技并非没有不足，理论上，在采用前进前辈工艺出产MLC闪存方面困难重重。跟着闪存科技的演进，在浮动栅(floating gate)中存储的电荷总量削减了，使得检测存储的信息变得加倍困难，尤其是对MLC芯片而言，它需要识别四个电压值，而非两个。尽管如斯，据报道，东芝在70nm工艺中能够包管采用与90nm科技雷同的代码纠错方案。这显示该公司并没有加快MLC科技缩放的步调，起码是就此刻而言。

此外，与SLC闪存比拟，MLC闪存在靠得住性方面存在不足。当然对于生产者而言，靠得住性不是他们存眷的核心问题，但在其它生产市场却显然是一个短处。　　

三星正预备推出采用65nm工艺的4Gb SLC NAND闪存，其尺寸比采用73nm工艺的器件稍为紧凑。由此激发的问题是：在工艺缩放方面是否已经无能为力了？　　　

假如理论情况真的如斯，那么情况显得对东芝更为有利，因为今朝它已经出产出70nm工艺的MLC闪存。作为百年大计，三星转向65nm工艺的芯片也许能够立马同东芝的90nm MLC竞争。可是东芝的70nm工艺8Gb MLC科技已获得重大成就，实现了56.5Mb/mm2的比特密度，比三星65nm工艺31.3Mb/mm2的额外比特密度要横跨80%。一些并非出自东芝公司的报告暗示，该公司将会跨过65nm工艺，间接转到50-60nm线宽的16Gb闪存。当然，在顺利实现低于65nm线宽的工艺，仍有一些科技障碍有待克服。
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发布日期：2009-8-4　【返回】