Semiconductor device and a method of manufacturing the same

A semiconductor device, comprising:

• a first group of transistors formed on a semiconductor substrate;
• and
• a second group of transistors formed on the semiconductor substrate, each of which is lower in operating voltage than each of said transistors in said first group;
• wherein each of said transistors in said first group includes
• a first gate electrode formed on said semiconductor substrate through a first gate insulating film, and
• a silicide layer formed on said first gate electrode;
• each of said transistors in said second group includes
• a second gate electrode formed in a trench for gate formation, formed in an insulating film above said semiconductor substrate, through a second gate insulating film;
• each of said first gate electrodes of said first group of transistors is formed so as to be lower than each of said second gate electrodes of said second group of transistors;
• a protective film is formed so as to cover said silicide layers on each of said first gate electrodes of said first group of transistors;
• and
• a surface of said insulating film in a region in which said second group of transistors is formed, and a surface of said protective film are formed to have a flat surface-like shape.

A semiconductor device, comprising:

• a first group of transistors formed on a semiconductor substrate;
• and
• a second group of transistors formed on the semiconductor substrate, each of which is lower in operating voltage than each of said transistors in said first group;
• wherein each of said transistors in said first group includes
• a first gate electrode formed on said semiconductor substrate through a first gate insulating film, and
• a silicide layer formed on said first gate electrode;
• each of said transistors in said second group includes
• a second gate electrode formed in a trench for gate formation, formed in an insulating film above said semiconductor substrate, through a second gate insulating film;
• and
• a protective film is formed so as to cover each of said second gate electrodes of said second group of transistors.

A method of manufacturing a semiconductor device including a first region having a first group of transistors formed therein, and a second region having a second group of transistors formed therein, each of said transistors in said second group being lower in operating voltage than each of said transistors in said first group, said first group of transistors and said second group of transistors being formed on a semiconductor substrate, each of said transistors in said first group having a first gate electrode formed on said semiconductor substrate through corresponding one of first gate insulating films, and a silicide layer formed on corresponding one of said first gate electrodes, each of said transistors in said second group having a second gate electrode formed in a trench for gate formation, formed in an insulating film above said semiconductor substrate, through corresponding one of second gate insulating films, said manufacturing method, when said semiconductor device is manufactured, sequentially comprising the steps of:

• forming said first gate electrodes in said first region and said second region on said semiconductor substrate through the corresponding ones of said first gate insulating films, respectively;
• forming said insulating film for covering said first gate electrodes formed in said first region and said second region, respectively;
• forming said silicide layer on each of said first gate electrodes formed in said first region after each of said first gate electrodes formed in said first region is formed so as to be lower than each of said first gate electrodes formed in said second region by removing an upper portion of said insulating film and upper portions of said first gate formed in said first region;
• forming a protective film for covering said silicide layer so that a surface of said insulating film formed in said second region, and a surface of said protective film are formed to have a flat surface-like shape;
• and
• filling a conductive material in each of said trenches for gate formation by removing said protective film in said second region, and removing said first gate electrodes and said first gate insulating films formed in said second region through corresponding one of said second gate insulating films, so as to form said second gate electrode of said second group of transistors.