Not long ago, Qualcomm announced its future integrated 5G baseband Snapdragon chips will be based on Samsung's 7nm manufacturing, specifically 7nm LPP, using EUV (extreme ultraviolet) technology.
Then, Samsung broke ground in Huacheng a new 7nm EUV process manufacturing plant, to be put into operation by 2020.
Seemingly in full swing, but in fact 7nm EUV still faces many technical problems.
According to EETimes disclosure, at a recent chip maker conference, some vendors made a sharp statement.
For example, George Gomba, GlobalFoundries Research Vice President, said: The only available cash product NXE-3400 from ASML (Asbestos) capable of doing 250-watt EUV lithography still does not meet the standard , They advised suppliers to inspect the EUV reticle system well and improve the photoresist.
Lithography here to do something simple science.
Lithography is the process of etching the pattern that forms the chip onto the silicon wafer The wafer is coated with a photosensitive material called a photoresist and then the wafer is exposed to bright light through a mask.The area covered by the mask will retain its photoresist layer and be directly exposed to ultraviolet light Those will fall off.
The wafer is then etched (plasma) using a plasma or acid During the etch, the portion of the wafer covered by the photoresist is protected, leaving the silicon oxide; the other is etched away.
Obviously, The light of small wavelengths can create finer details , Such as narrower circuits and smaller transistors, but not in the current 14nm manufacturing, but with multiple pattern exposures (multiple masks and exposure stations).
However, the more steps, the longer the manufacturing time and the higher the defect rate, so the shorter UV light has to be promoted to the technical schedule.
The chip industry has considered the use of 13.5 nm EUV lithography (UV wavelength range 10-400 nm) from the beginning of the 1990s to replace the current 193 nm EUV itself has limitations, such as easy to be absorbed by the air and lens materials to generate high-intensity EUV is also difficult.Industry consensus is, EUV commercial light source power of at least 250 watts, Intel also said that they need is at least 1000 watts.
At the conference, researchers at Samsung / TSMC revealed that there are two tricky problems with lithography on the NXE-3400, or the lack of an etched area results in a short circuit, or an overdue area, resulting in tearing.
At the moment, the EUV lithography machine is acceptable for defect sizes above 20nm, but it is still difficult to deal with.
