Method of manufacturing a flash memory device with an antidiffusion region between well regions

A method of manufacturing a flash memory device, comprising the steps of:

• providing a semiconductor substrate of a first type;
• forming a pair of spaced apart field oxides on the semiconductor substrate to thereby define a first region therebetween;
• forming a first photoresist pattern above the semiconductor substrate such that said first region is exposed;
• implanting a first ion in said first region to thereby form a first well region, the first ion being of a second type with a polarity opposite to a polarity of said first type;
• forming a second photoresist pattern above the semiconductor substrate such that at least a portion of said first region is exposed;
• implanting a second ion in said portion to form an anti-diffusion region above the first well region;
• implanting a third ion in said portion to thereby form a second well region, the third ion being of said first type;
• and
• performing a thermal process for activating impurities in said first well region, said anti-diffusion region and said second well region, thereby forming a triple-well structure having an anti-diffusion region separating said first and second well regions.

A method of manufacturing a flash memory device, comprising the steps of:

• forming a semiconductor substrate in which field oxide films are formed;
• forming a first photoresist pattern through which a portion of said semiconductor substrate in which a first well region will be formed is exposed, on said semiconductor substrate, and then implanting an impurity ion having an opposite type to said semiconductor substrate to form a first well region;
• after removing said first photoresist pattern, forming a second photoresist pattern through which a portion of said semiconductor substrate in which a second well region will be formed is exposed on said semiconductor substrate, and then implanting ions with an ion implantation process to form an anti-diffusion region;
• implanting an impurity ion of the same type as said semiconductor substrate, into said semiconductor substrate in which said second photoresist pattern is formed, thus forming a second well region;
• and
• performing a thermal process for activating impurities in said first well region, said anti-diffusion region and said second well region, wherein:
• the first photoresist pattern is different in size from the second photoresist pattern;
• and
• implanting ions with an ion implantation process to form an anti-diffusion region, and implanting an impurity ion of the same type as said semiconductor substrate, are both performed using the second photoresist pattern.

A method of manufacturing a flash memory device, comprising the steps of:

• providing a semiconductor substrate of a first type;
• forming a pair of spaced apart field oxides on the semiconductor substrate to thereby define a first region therebetween;
• forming a first photoresist pattern above the semiconductor substrate such that said first region is exposed;
• implanting a first ion in said first region to thereby form a first well region, the first ion being of a second type with a polarity opposite to a polarity of said first type;
• forming a second photoresist pattern above the semiconductor substrate such that at least a portion of said first region is exposed;
• implanting a second ion in said portion to form an anti-diffusion region above the first well region;
• implanting a third ion in said portion to thereby form a second well region, the third ion being of said first type;
• and
• performing a thermal process for activating impurities in said first well region, said anti-diffusion region and said second well region, wherein:
• the first photoresist pattern is different in size from the second photoresist pattern;
• and
• said steps of implanting a second ion and implanting a third ion are both performed using the second photoresist pattern.