Stabilization of dopant concentration in semiconductor device having epitaxially-filled trench

A method for manufacturing a semiconductor device, the method comprising:

• forming one layer out of a first conductivity type drift layer and a second conductivity type layer on a first conductivity type semiconductor substrate, which forms a drain region;
• forming first trenches in a surface of the one layer;
• heating the one layer having the first trenches in a non-oxidizing and non-nitridizing atmosphere containing a dopant or a compound that includes the dopant in order to smooth surfaces of the first trenches and to maintain a dopant concentration in the one layer to be a predetermined concentration before the heating is treated, wherein the conductivity type of the dopant is the same as that of a dopant contained in the one layer;
• forming the other layer out of the first conductivity type drift layer and the second conductivity type layer to fill the first trenches by epitaxial growth in order to form an alternate arrangement of first conductivity type drift regions and second conductivity type first semiconductor regions;
• forming first conductivity type second semiconductor regions on the first conductivity type drift regions;
• forming a second conductivity type base layer on the first semiconductor regions and the second semiconductor regions;
• forming second trenches that extend through the base layer to reach the second semiconductor regions;
• forming gate insulating films on surfaces of the second trenches;
• and
• forming gate electrodes on the gate insulating films.

A method for manufacturing a semiconductor device, the method comprising:

• forming a trench in a predetermined layer of a semiconductor substrate;
• heating the substrate having the trench in a non-oxidizing and non-nitridizing atmosphere containing a dopant or a compound that includes the dopant in order to smooth surfaces of the trench and to diffuse the dopant contained in the non-oxidizing and non-nitridizing atmosphere into the predetermined layer and partially increase a dopant concentration in the predetermined layer to be a predetermined concentration higher than that before the heating is treated;
• and
• forming an epitaxially grown film to fill the trench.

A method for manufacturing a semiconductor device, the method comprising:

• Preparing a first conductivity type semiconductor substrate, which forms a drain region;
• forming a semiconductor layer on the semiconductor substrate;
• forming first trenches in a surface of the semiconductor layer;
• heating the semiconductor layer having the first trenches in a non-oxidizing and non-nitridizing atmosphere containing a dopant or a compound that includes the dopant in order to smooth surfaces defining the first trenches and to diffuse the dopant contained in the non-oxidizing and non-nitridizing atmosphere into the semiconductor layer and partially increase a dopant concentration in the semiconductor layer to form one layer out of a first conductivity type drift layer and a second conductivity type layer on the semiconductor substrate that have a predetermined dopant concentration;
• forming the other layer out of the first conductivity type drift layer and the second conductivity type layer to fill the first trenches by epitaxial growth in order to form an alternate arrangement of first conductivity type drift regions and second conductivity type first semiconductor regions;
• forming first conductivity type second semiconductor regions on the first conductivity type drift regions;
• forming a second conductivity type base layer on the first semiconductor regions and the second semiconductor regions;
• forming second trenches that extend through the base layer to reach the second semiconductor regions;
• forming gate insulating films on surfaces defining the second trenches;
• and
• forming gate electrodes on the gate insulating films.

A semiconductor device comprising:

• a first conductivity type semiconductor substrate, which forms a drain region;
• first conductivity type drift regions;
• second conductivity type first semiconductor regions, wherein the drift regions and the first semiconductor regions are in alternate contact with each other-to laterally form an alternately arranged area;
• first conductivity type second semiconductor regions, which are located on the drift regions;
• second conductivity type base regions, which are located on the first semiconductor regions and the second semiconductor regions;
• second trenches, which extend through the base regions to reach the second semiconductor regions;
• gate insulating films, which are located on surfaces of the second trenches;
• forming gate electrodes, which are located on the gate insulating films;
• and
• a low dopant concentration region, which is adjacently located outside the alternately arranged area, which is made of the drift regions and the first semiconductor regions, wherein the low dopant concentration region has a dopant concentration lower than those of the drift regions and the first semiconductor regions.