Phison claims to have produced the earliest "USB flash removable disk," dubbed "Pen Drive," in May 2001. Phison is a member of the Open NAND Flash Interface Working Group, which aims to standardize the hardware interface to NAND flash chips.
In early October 2014, security researchers Adam Caudill and Brandon Wilson publicly released source code to a firmware attack against Phison USB controller ICs. This code implements the BadUSB exploit described in July 2014 at the Black Hat Briefings conference. At this time all USB devices using Phison controllers (NOT just Phison branded USB sticks, but including other brands as yet unidentified) should be considered a security threat.