High-k gate-first 与High-k first, metal gate last比较

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Gate-last是用于制作金属栅极结构的一种工艺技术，这种技术的特点是在对硅片进行漏/源区离子注入操作以及随后的高温退火工步完成之后再形成金属栅极；与此相对的是Gate-first工艺，这种工艺的特点是在对硅片进行漏/源区离子注入操作以及随后的退火工步完成之前便生成金属栅极。
由于退火工步需要进行数千度的高温处理，而Gate-last工艺则可令金属栅极避开高温退火工步，因此相比Gate-first工艺而言，前者对用于制作金属栅极的金属材料要求更低，不过相应的工艺技术也更复杂，Intel便是Gate-last工艺的坚定支持者，而IBM/AMD则将采用Gate-first工艺制作32nm制程金属栅极。intel 的gate last 的工艺，虽然复杂了点，但是我想当初开发的时候，不可能没有想到，9 ，从三明治的角度来比喻，intel的gate因为侧面也保护起来，似乎更加能够防止漏电。
而且从图片来看，intel到从45nm开始，gate 做的越来越工整。就我个人的认知，Gate last整合比较方便，而且Vt失谐也有保证,Metal Gate避开了高温process,量产整体稳定性也是有保证的,唯一的问题还是在于成本.
  就Metal gate fill in而言,Intel用的是Al,大可以换成W, gap fill能力基本没大问题而且WCVD/WCMP是很成熟的process了,大不了阻值比Intel Al高一些,但是比IBM的metal/poly/NiSi低是肯定的
      所以目前而言,Foundry端,T跟U选的都是Gate last,最主要的考量还是稳定性,C跟S没什么好说的,给IBM上贡自然是Gate first.
      其实最重要的一点,Gate last Intel已经当过小白鼠了,至少证明是可以大规模量产的, T跟U选择gate last,不无这方面的考虑. IBM**烘烘烘,希望0.13um跌一跤拖惨U的故事不要重演,不然不知道拖多少人下水,边走边看吧.

elisha

看戏，IBM最近工艺好像遇到很大麻烦，连带整个阵营都出问题

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Members of IBM Corp.'s technology alliance, namely GlobalFoundries Inc. and Samsung Electronics Co. Ltd., dismissed a report that the group is struggling with its high-k/metal-gate technology.

High-k/metal-gate ''technology enables traditional scaling of the electrical gate dielectric and reduced standby power of transistor due to a reduction in gate leakage,''said Andrew Lu, an analyst with Barclays Bank, in a report.

''There has been a recent divergence in wafer processing technology to either choose 'gate-first' or 'gate-last' for (high-k/metal-gate),'' Lu said. ''Gate-first and gate-last are terms that refer to whether the metal gate electrode is deposited on wafer before or after the high-temperature activation anneals of flow processing.''

Intel Corp., Taiwan Semiconductor Manufacturing Co. Ltd. (TSMC) and others have moved towards ''gate-last'' technology. Intel has been shipping processors based on high-k since the 45-nm node. Intel has shipped two generations of high-k. TSMC has yet to ship its technology.  

In contrast, IBM's ''fab club'' is using a ''gate-first'' technology. But to date, IBM's technology partners have yet to ship high-k--at least in chips in mass volumes. Advanced Micro Devices Inc. is expected to ship its first processors based on high-k in the first part of 2011. AMD is using IBM's technology.

''The gate-first technology adopters (including Sematech and Fishkill Alliance technology  partners such as IBM, Infineon, NEC, Globalfoundries, Samsung, STMicroelectronics and Toshiba) have encountered some problems, we understand, related to thermal instability, threshold voltage shifts and re-growth in the gate stack, which is serious for pMOS (positive type metal oxide semiconductor) at scaled electrical oxide thickness,'' Lu said.

''We expect TSMC will be able to lead its competitors on the 28-nm migration using the gate-last high-k/metal-gate technology,'' Lu said.

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根據Barclays Bank 分析師Andrew Lu的一篇報告指出，由於可減少閘極漏電流，高介電/金屬閘極技術能降低電晶體的待機耗電，不過現在該領域出現了該採用「前閘極(gate-first)」或「後閘極(gate-last)」的爭議；所謂的前或後，指的是金屬閘極是在半導體製程中的高溫活化退火程序(high-temperature activation anneals)之前或之後，沉積到晶圓片上。


包括英特爾(Intel)、台積電(TSMC)等廠商是後閘極技術的支持者；其中英特爾是從45奈米節點開始生產高介電製程處理器，迄今已經推出兩代高介電製程產品。而IBM的晶圓廠聯盟則是採用前閘極技術，但到目前為止，該聯盟成員都尚未量產高介電製程晶片；採用IBM製程的AMD可望在2011推出第一代高介電處理器。


「具我們了解，前閘極技術支持者(包括Sematech以及IBM、Infineon、NEC、Globalfoundries、Samsung、ST與Toshiba)都面臨包括散熱不穩定(thermal instability)、閾值電壓飄移(threshold voltage shifts)，以及閘堆疊重新生長(re-growth in the gate stack)等等問題，這對微縮電氧化層厚度的pMOS元件來說是很嚴重的。」Lu表示。


此外Barclays Bank 的報告預期，台積電可望成為28奈米節點前閘極高介電/金屬閘極技術領域的領導者。