Advanced Cr dry etching process

The pattern size of the Logic devices and the Logic - embedded DRAM devices as well as the DRAM devices are reducing. For the photo mask accurate critical dimension (CD) and CD uniformity are needed. Therefore the Cr dry etching process has been studied. But it is well known that the CD loss is affected by pattern density. This phenomenon was called loading effect.(1234) This is a big issue to apply dry etching for advanced photo mask process such as 180 nm generation and later. For example, there was about 90 nm line width difference of a test mask (6 " AR-chrome with ZEP-7000) processed by magnetically enhanced reactive ion etching (MERIE) using Cl2+O2 gas mixture. In general, it is known that adding another gas is helpful for etching rate uniformity in dry etching. Effect of H2, HCl and NH3 as the adding gas in Cl2+O2, was investigated using a MERIE system (MEPS-6025) for improving line width difference between clearfield and darkfield. It was found that an adding gas including H had some effect for reduction of the difference. H2 and HCl was effective, and reduction of the difference was about 90 % to 67 %. With this condition the Cr dry etching rate increased. Therefore the all problem of Cr dry etching was solved. Using this dry etching process, the photo masks are supplied for 180 nm generation Logic - embedded DRAM devices.