SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD THEREOF
First Claim
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1. A semiconductor device comprising:
- a first semiconductor layer of a first conductivity type;
a second semiconductor layer of a second conductivity type formed in a surface portion of said first semiconductor layer on one thickness direction side;
a third semiconductor layer of the first conductivity type selectively formed in a surface portion of said second semiconductor layer on the one thickness direction side;
a gate electrode buried in a gate trench passing through said second and third semiconductor layers to reach said first semiconductor layer, with a gate insulating film interposed therebetween;
a fourth semiconductor layer of the second conductivity type formed in a portion of said second semiconductor layer that forms a bottom of a contact trench passing through said third semiconductor layer to reach said second semiconductor layer, said fourth semiconductor layer having a higher concentration of the second conductivity type impurity than said second semiconductor layer; and
a contact electrode buried in said contact trench and in contact with said third and fourth semiconductor layers,said gate electrode including;
an internal gate electrode buried in a part of said gate trench including its bottom; and
a low-resistance gate electrode buried in a remaining part of said gate trench and in contact with said internal gate electrode, said low-resistance gate electrode being lower resistant than said internal gate electrode, andsaid contact electrode including;
a first conductor layer buried in said contact trench; and
a second conductor layer that is in contact with said first conductor layer and covers said third semiconductor layer and said gate electrode with an interlayer insulating film interposed therebetween,said first conductor layer and said second conductor layer being made of different materials, andsaid low-resistance gate electrode and said first conductor layer being made of a same material.
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Abstract
An object is to provide a semiconductor device and its manufacturing method in which delay in switching and non-uniform operations are prevented and in which stresses occurring in trench regions are alleviated as much as possible. A gate electrode in a gate trench is formed of a polysilicon layer and a gate tungsten layer that is lower resistant than the polysilicon layer. Also, a source electrode is formed of source tungsten layers buried in source trenches and an AlSi layer in contact with the source tungsten layers and covering source layers and the gate electrodes with a thick insulating film interposed therebetween.
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Citations
6 Claims
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1. A semiconductor device comprising:
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a first semiconductor layer of a first conductivity type; a second semiconductor layer of a second conductivity type formed in a surface portion of said first semiconductor layer on one thickness direction side; a third semiconductor layer of the first conductivity type selectively formed in a surface portion of said second semiconductor layer on the one thickness direction side; a gate electrode buried in a gate trench passing through said second and third semiconductor layers to reach said first semiconductor layer, with a gate insulating film interposed therebetween; a fourth semiconductor layer of the second conductivity type formed in a portion of said second semiconductor layer that forms a bottom of a contact trench passing through said third semiconductor layer to reach said second semiconductor layer, said fourth semiconductor layer having a higher concentration of the second conductivity type impurity than said second semiconductor layer; and a contact electrode buried in said contact trench and in contact with said third and fourth semiconductor layers, said gate electrode including; an internal gate electrode buried in a part of said gate trench including its bottom; and a low-resistance gate electrode buried in a remaining part of said gate trench and in contact with said internal gate electrode, said low-resistance gate electrode being lower resistant than said internal gate electrode, and said contact electrode including; a first conductor layer buried in said contact trench; and a second conductor layer that is in contact with said first conductor layer and covers said third semiconductor layer and said gate electrode with an interlayer insulating film interposed therebetween, said first conductor layer and said second conductor layer being made of different materials, and said low-resistance gate electrode and said first conductor layer being made of a same material. - View Dependent Claims (2, 3, 4, 5)
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6. A semiconductor device manufacturing method comprising the steps of:
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(a) in a surface portion of a first semiconductor layer of a first conductivity type on one thickness direction side, forming a second semiconductor layer of a second conductivity type; (h) selectively forming a third semiconductor layer of the first conductivity type in a surface portion of said second semiconductor layer on the one thickness direction side; (c) forming a gate trench passing through said second and third semiconductor layers to reach said first semiconductor layer; (d) forming a gate electrode in said gate trench, with a gate insulating film interposed therebetween; (e) forming a contact trench passing through said third semiconductor layer to reach said second semiconductor layer; (f) forming a fourth semiconductor layer of the second conductivity type in a portion of said second semiconductor layer that forms a bottom of said contact trench such that said fourth semiconductor layer has a higher concentration of the second conductivity type impurity than said second semiconductor layer; and (g) forming a contact electrode in contact with said third and fourth semiconductor layers in said contact trench, said step (d) of forming said gate electrode comprising; (d-1) forming an internal gate electrode by filling a part of said gate trench including its bottom with a conductive material, with said gate insulating film interposed therebetween; and (d-2) forming a low-resistance gate electrode in contact with said internal gate electrode by filling a remaining part of said gate trench with a conductive material that is lower resistant than the conductive material of said internal gate electrode, with said gate insulating film interposed therebetween, and said step (g) of forming said contact electrode comprising; (g-1) forming a first conductor layer by filling said contact trench with the same conductive material as the conductive material forming said low-resistance gate electrode; and (g-2) forming a second conductor layer by using a conductive material that is different from the conductive material forming said first conductor layer such that said second conductor layer is in contact with said first conductor layer and covers said third semiconductor layer and said gate electrode, with an interlayer insulating film interposed therebetween.
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Specification