Reducing Radioactive Species in Evaporated Aluminum Films by Shutting off the Initial Vapor Stream
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11
Aluminum has been found to have alpha particle radioactivity. This can cause "soft errors" in integrated circuitry. As the density of integrated semiconductor circuits is increased, the device size decreases, and the charge level that distinguishes a "1" bit from a "0" bit is reduced. This makes the circuits more vulnerable to extraneous charge introduction that might convert a "1" bit into a "0", or vice versa, such as that generated by electron-hole production from absorption of alpha particle radiation. Alpha particle radiation from the uranium and thorium radioactive decay chains produces this undesirable effect. Uranium and thorium are found in aluminum, and aluminum is used extensively in the interconnection metallurgy in semiconductor integrated circuit manufacture.