Method of manufacturing a semiconductor device
View Patent ↗A semiconductor device in which a semiconductor layer is formed on an insulating substrate with a front-end insulating layer interposed between the semiconductor layer and the insulating substrate is provided which is capable of preventing action of an impurity contained in the insulating substrate on the semiconductor layer and of improving reliability of the semiconductor device. In a TFT (Thin Film Transistor), boron is made to be contained in a region located about 100 nm or less apart from a surface of the insulating substrate so that boron concentration decreases at an average rate being about 1/1000-fold per 1 nm from the surface of the insulating substrate toward the semiconductor layer.
1. A semiconductor device comprising:
a semiconductor layer formed on an insulating substrate with a front-end insulating layer being interposed between said semiconductor layer and said insulating substrate, boron or aluminum being contained as an impurity in said front-end insulating layer, wherein impurity concentration is set to be about 1×10 22 (atom/cm 3 ) or less on a surface of said insulating substrate, wherein said impurity concentration in a region of said front-end insulating layer located about 100 nm or more apart from said surface of said insulating substrate is set to be about 10 19 (atom/cm 3 ) or less, and wherein said impurity concentration gradually decreases from said surface of said insulating substrate toward said semiconductor layer.
2. The semiconductor device according to claim 1 , wherein said impurity concentration in a region of said front-end insulating layer located about 100 nm apart from said surface of said insulating substrate is set to be 1/100000-fold or less in reference to that on said surface of said insulating substrate.
3. The semiconductor device according to claim 1 , wherein said region of said front-end insulating layer where said impurity concentration gradually decreases from said surface of said insulating substrate toward said semiconductor layer is formed at least under a gate electrode.
4. A method for manufacturing a semiconductor device in which a semiconductor layer is formed on an insulating substrate with a front-end insulating layer being interposed between said semiconductor layer and said insulating substrate, boron or aluminum being contained as an impurity in said front-end insulating layer, the method comprising:
setting impurity concentration to be about 1×10 22 (atom/cm 3 ) or less on a surface of said insulating substrate,
setting said impurity concentration in a region of said front-end insulating layer located about 100 nm or more apart from said surface of said insulating substrate to be about 10 19 (atom/cm 3 ) or less, in such a manner that said impurity concentration gradually decreases from said surface of said insulating substrate toward said semiconductor layer.
5. The method for manufacturing the semiconductor device according to claim 4 , wherein said impurity concentration in a region of said front-end insulating layer located about 100 nm apart from said surface of said insulating substrate is set to be 1/100000-fold or less in reference to that on said surface of said insulating substrate.
6. The method for manufacturing the semiconductor device according to claim 4 , wherein said region of said front-end insulating layer where said impurity concentration gradually decreases from said surface of said insulating substrate toward said semiconductor layer is formed at least under a gate electrode.