Graded implantation of oxygen and/or nitrogen constituents to define buried isolation region in semiconductor devices
AssigneesSharp Kabushiki Kaisha, Sharp Microelectronics Technology, Inc.
InventorTatsuo Nakato
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Abstract
A graduated concentration profile is used defining a buried isolation region in a semiconductor device. Smaller concentrations of dielectric-defining particles are used for implantation at the deepest levels of the isolation region in order to reduce the defect density in an overlying epi layer.
Claims28
A method for creating a buried isolation region in a crystalline semiconductor substrate, the method comprising the steps of:
- implanting a first concentration C1 of insulation-forming particles to a first depth Z1 of the substrate using first energy E1, said first implanting directly producing first defects in the crystalline structure of the substrate, the number or size of the first defects being a first function f(C1.multidot.E1) of the product of the first concentration C1 and the first energy E1;
- implanting a second concentration C2 of insulation-forming particles to a second depth Z2 of the substrate using second energy E2, said second implanting directly producing second defects in the crystalline structure of the substrate, the number or size of the second defects being a second function f(C2.multidot.E2) of the product of the second concentration C2 and the second energy E2;
- and
- annealing the substrate between the first and second implant steps;
- where Z2>Z1, E2>E1 and C2 is substantially less than C1 so that the number or size of said second defects produced in the substrate above first depth Z1 by the second, more energetic implant step (E2.multidot.C2) is not substantially more than the number or size of said first defects produced by the first implant (El.multidot.C1).
A method for creating a buried isolation region in a crystalline semiconductor substrate, the method comprising the steps of:
- implanting respective first through nth concentrations, C1 to Cn of insulation-forming particles at respective first through nth successive depths, Z1 to Zn of the substrate using respective first through nth energy levels, E1 to En;
- wherein n is a number equal to 3 or more;
- wherein each of the first through nth implants contributes a number of non-curable, significant defects to the crystal structure of the semiconductor substrate, said number being for each given implant, a function f(Ci.multidot.Ei) of the product of the concentration Ci and energy Ei used in the given implant,
- wherein for each energy level Ei in the series of energy levels, E2 to En, Ei is substantially greater than E(i-1);
- wherein for each concentration Ci in the series of concentrations, C2 to Cn, ci is substantially less than C(i-1);
- and
- wherein respective concentration times energy products C1.multidot.E1 through Cn.multidot.En of the first through nth implants are selected so that the number of non-curable significant defects contributed by each ith implant do not substantially exceed the number of non-curable significant defects contributed by a next-lower, numbered (i-1)th implant.
A method for creating a buried isolation region in a crystalline semiconductor substrate, the method comprising the steps of:
- implanting respective first through nth concentrations, C1 to Cn of insulation-forming particles at respective first through nth depths, Z1 to Zn of the substrate using respective first through nth energy levels, E1 to En;
- wherein n is a number equal to 3 or more;
- wherein for each energy level Ei in the series of energy levels, E2 to En, Ei is substantially greater than E(i-1);
- wherein for each concentration Ci in the series of concentrations, C2 to Cn, Ci is substantially less than C(i-1);
- and
- wherein at least an ith one of respective concentrations C1 to Cn is selected so as to form a non-stoichiometric insulating composition at the corresponding depth, Zi.
Dependencies are inferred from the claim text.