Q：RC-Corner跟PVT怎么組合？
A：通常的組合：
Q：通常說的ttcorner指的是啥？
A：@孟時光 ttcorner是指管子在tt+RCtyp吧。
Typesof corners
When working in the schematic domain, weusually only work with frontend of line (FEOL) process corners as these corners willaffect the performance of devices. But there is an orthogonal set of processparameters that affect back endof line (BEOL) parasitics.
FEOL corners
One naming convention for process corners isto use two-letter designators, where the first letter refers to the N-channel MOSFET (NMOS) corner, and the second letter refers to the P channel (PMOS)corner. In this naming convention, three corners exist: typical, fast and slow. Fast and slow corners exhibit carrier mobilities that are higher and lower than normal,respectively. For example, a corner designated as FS denotes fast NFETs and slow PFETs.
There are therefore five possible corners:typical-typical (TT) (not really a corner of an n vs. p mobility graph, butcalled a corner, anyway), fast-fast (FF), slow-slow (SS), fast-slow (FS), andslow-fast (SF). The first three corners (TT, FF, SS) are called even corners,because both types of devices are affected evenly, and generally do notadversely affect the logical correctness of the circuit. The resulting devicescan function at slower or faster clock frequencies, and are often binned as such. The last two corners (FS, SF) are called "skewed"corners, and are cause for concern. This is because one type of FET will switchmuch faster than the other, and this form of imbalanced switching can cause oneedge of the output to have much less slew than the other edge. Latching devices may then record incorrect values in the logic chain.
BEOL corners
In addition to the FETs themselves, there are more on-chip variation (OCV) effects thatmanifest themselves at smaller technology nodes. These include process, voltageand temperature (PVT) variation effects on on-chip interconnect, as well as viastructures.
Extraction tools often have a nominal corner to reflect the nominal cross section of the process target.Then the corners cbest and cworst were created to model the smallest andlargest cross sections that are in the allowed process variation. A simplethought experiment shows that the smallest cross section with the largestvertical spacing will produce the smallest coupling capacitance. CMOS Digitalcircuits were more sensitive to capacitance than resistance so this variationwas initially acceptable. As processes evolved and resistance of wiring becamemore critical, the additional rcbest and rcworst werecreated to model the minimum and maximum cross sectional areas for resistance.But the one change is that cross sectional resistance is not dependent on oxidethickness (vertical spacing between wires) so for rcbest the largest is used and for rcworst the smallest is used.
Parameters
Mostimportantly, the corners of a process are designated by five parameters
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Mobility variation due to implantation of N+ and P+
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Vthvariation
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Resistance of the actives
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Bodycoefficient
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Oxidethickness
Otherparameters like the effective Length, effective width, Cjsw caps, Cj caps alsochange.
注：所以TT corner並不是一個需要sign-off的corner。
Q：dishing可以理解成過度刻蝕嘛？
A：@孟時光 不是刻蝕，意思差不多，就多啃掉了一塊
Q：為什么銅軟？
A：@孟時光 Cu相對氧化硅比較軟。大概是：刀子能划銅板，不能划玻璃。
Q：@LZH 有沒懂的大牛 scan 下這個問題可以autofix嗎？
A：@junbojia 最好不用Autofix， 如果D10 Vio比較多的話， autofix不知道會給你fix成什么樣子， autofix會對后端產生一些影響，比如timing,routing.
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建議1：分析一下電路， 看能否再RTL上休掉，如果rtl能修最好rtl修。
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建議2：不修，這類vio 容易造成mismatch，但是現在ATPG算法能夠處理這種情況，避免生成這類pattern。 可能會使patter count受影響。
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建議3：一般scan insertin都不建議開autofix， 如果要開autofix，插完鏈以后，report一下都插入了哪些autofix，分析一下合理不。關於autofix DRC，一般不建議開。 但是C家有一個feature， 通過autofix來加入提高coverage，和隔離x-source，具說很好用，但是要advance license。
Q：RTL難修怎么辦？
A：那就不修，交給atpg處理。
Q：不修，那對atpg影響是什么？
A：這類vio 容易造成mismatch， 但是現在ATPG算法能夠處理這種情況，避免生成這類pattern。 可能會使patter count受影響。
Q：@松泉石 問問C家timingsignoff tools，大家有使用的么？
A：Innovus+TSO應該 很多用 innovus 做16以下的項目的人都用過吧
Q：@松泉石 我今天遇到一個問題： sdf annotation completed, 0 Errors, 比較多的Warning，結果vcs 出現 Segmentation fault
A：@占少君 limit stacksize unlimited
Q：@Lauque 問一個問題，怎么理解eFUSE？
A：@wbefuse就是一次性燒入不可更改的rom，每個row有一個bit用來指示是否該row已被燒入，燒入前需要輸入一串固定的碼這個碼應該是efuse廠家提供的 匹配之后才能燒入。
@唐欣 EFUSE理解成保險絲，燒斷之前邏輯是1，燒斷之后邏輯是0