1st Gen ASICs (2012 - beginning of 2013): 150nm - 55nm. Vendors that still are selling those: BitFury, AsicMiner, AntMiner, BFL (not anymore), Avalon (not anymore)
2nd Gen ASICs (2013-beginning of 2014): 28-40nm. Vendors: KNCMiner (28nm Jupiter, Saturn. However not selling those anymore. Building for themselves. Will use those for selling Cloud hashing), Cointerra (28nm TerraMiner IV). ASICMiner announced it will build hundreds of PH from 40nm ASICs. It is old technology, but if produced cheap enough then i guess its ok.
3rd Gen ASICs (2014): 20nm.
Announced only by KNCMiner (Neptunes). Mass delivery starts probably in 2-3 months. There are no smaller tech available. Intel is trying to get into 14nm with no success. Then it will take still few years until there are better ASICs than 20nm.
There are few marketing tricks done by vendors of old tech asics. By overclocking an ASIC, you can make it work 2x faster (then you can market their old tech ASICs as faster than newer tech ASICS). The downside is that electricity consumption goes 3x.
Another trick is to underclock it. Hashing power goes to 1/3rd, but electricity goes to 1/5th. Then they can market their ASICs as giving better GH per Watts compared to newer tech ASICs. The downside of it is that you need PC size miner to get 100GH. Same size hardware with 28nm asics normally clocked would give you 20 times more hashing power for marginally more electricity per GH. ASICMiner, BitFury market their new products (old tech asics) by downclocking those.
Another bit of info. There are very few factories that can produce 28nm technology, and their capacity is limited. That is why 28nm ASICs are sold by very few vendors and with limited batches. There are thousands of factories (cheap electronics factories) that can produce 40nm-155nm asics with unlimited capacity. That is why it is hard to keep track of all vendors that have products with old tech asics. ASICMiner in their pressrelease announced that their were outsourcing to those electronics shops the production of their 400 PH worth of 40nm asics.
Last bit of info: Future of bitcoin mining is not anymore in buying hardware. Higher difficulty makes every new hardware to require more TH, and consume more electricity and produce tons of heat. KNC Neptunes are in the electricity limits that can be run in a household. That is why vendors are building datacenters in the north pole (cheap refrigeration) for hosting the newer generation miners. Miners big enough to not be able to run in a household.
Check out KNC News Letter about their first plans about a 10 PH datacenter made out of 28nm asics.Hope it helped.
Libitum
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