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To: FJB who wrote (699)	11/26/1997 12:23:00 AM
From: Yousef	Respond to of 1305

Bob, Re: "Is OPC technology universally used for 0.25 and under photolithography?" Yes, OPC is used on a number of mask layers for .25um process (Trench, Gate, Metal 1 & Metal 2 ... for example). Many companies have their own software to generate the OPC features/"serifs". This is particularly true of companies that have "in-house" mask making. The commercial software can be difficult to utilize due to the need to tune the OPC structures to the process and to be confident that no inadvertent changes occur to the design. BTW, I wouldn't use MicroUnity. Yousef

To: FJB who wrote (699)	11/26/1997 2:02:00 PM
From: TheSpecialist	Read Replies (1) \| Respond to of 1305

RE: Is OPC technology universally used for 0.25 and under photolithography? If not,why? There are three levels of OPC. The first is line size biasing, used to correct for linewidth differences between isolated and dense geometries. The second is mild structural changes to the designed geometry to correct for corner rounding, line end shortening and linewidth differences (this is the type of correction shown on the MicroUnity home page). The third level is very aggressive structural changes to design to further the correction capabilities of level 2. The use of OPC is determined by the capability of lithography equipment and processes. For example, a high numerical aperture DUV stepper/scanner coupled with a high contrast resist would probably use only minor line biasing (level 1 OPC) to meet the requirements of a 0.25um process. However, if a fab is attempting to meet the same requirements with a lower NA stepper/scanner and lower contrast resist, then they might be forced to more agressively utilize higher levels of OPC. I think it is safe to say that level 1 OPC is used for all 0.25um technologies and that the more aggressive levels will be used on a case by case basis. It is also important to note that fabricating masks and inspecting them with higher levels of OPC is a new and difficult technology and this is being asked of an industry (mask) that is having difficulty just making standard geometry masks. Also, FYI, MicroUnity and a handful of other companies that sell software to generate the OPC designs work only in the level 2 and 3 OPCs. Level 1 OPC is easily accomplished by the mask shops with a standard chip design. Hope this helps. TS