Semiconductor device manufacturing: process – Introduction of conductivity modifying dopant into... – Ion implantation of dopant into semiconductor region
Patent
1998-08-27
1999-09-21
Niebling, John F.
Semiconductor device manufacturing: process
Introduction of conductivity modifying dopant into...
Ion implantation of dopant into semiconductor region
438522, 438952, H01L 21265
Patent
active
059566035
ABSTRACT:
A method for fabricating a plurality of shallow-junction metal oxide semiconductor field-effect transistors (MOSFETs) on a selected area of a silicon wafer, in the case in which the MOSFETs are spaced from one another by substantially transparent isolation elements. The method includes the step of flooding the entire selected area with laser radiation that is intended to effect the heating to a desired threshold temperature of only the selected depth of a surface layer of silicon that has been previously amorphized to this selected depth and then doped. This threshold temperature is sufficient to melt amorphized silicon but is insufficient to melt crystalline silicon. However, should the laser radiation be directly incident on both the substantially transparent isolation elements and the silicon surface, a variable portion of the energy of the incident radiation traveling through the substantially transparent isolation elements would be transferred to the silicon surfaces in contact with the isolation elements depending on the depth of the isolation elements thereby causing unpredictable additional heating of the silicon which would result in an unwanted shift in the fluence required to reach the melt threshold temperature in those silicon regions which reach the melt threshold temperature. To prevent this, a top layer stack of a dielectric and a highly radiation-absorbent material (e.g., silicon dioxide and tantalum nitride) is deposited over the selected area prior to the flooding of the entire selected area with laser radiation taking place. After, the melted silicon has cooled and recrystallized, the top layer of highly radiation-absorbent material is stripped.
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Talwar Somit
Weiner Kurt
Jones Allston L.
Lattin Christopher
Niebling John F.
Ultratech Stepper, Inc.
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