Thin film transistor performance enhancement by water plasma treatment
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsShou-Gwo Wuu, Cheng-Yeh Shih, Kan-Yuan Lee
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Abstract
A process is provided in which silicon thin film transistors fabricated with polycrystalline silicon, silicon oxide, and silicon conductive layers are exposed to microwave plasmas containing water vapor and to subsequent annealing steps to bring about an improvement in the ratio of device drain current in the conductive state to that in the non-conductive state, and a lower device subthreshold voltage swing.
Claims17
A method for the fabrication of silicon-gate thin film field effect transistors with optimized device electrical parameters comprising:
- depositing a polycrystalline silicon gate layer on an insulating substrate;
- depositing a silicon oxide gate insulation layer on the silicon gate layer;
- depositing a silicon conductive layer on the gate insulation layer;
- forming of higher-conductivity regions by ion implantation into the conductive silicon layer to form the source and drain regions which define the device channel dimensions;
- passivating already-deposited layers by covering them with a glass passivation layer;
- etching of electrical contact holes through the glass passivation layer;
- depositing and defining a pattern of conductive metal layer to form gate, source, and drain electrical contacts and interconnections;
- exposing devices to electrical plasmas in a water vapor gaseous environment;
- and
- annealing.
A process for improving the electrical parameters of silicon-gate thin film transistor devices comprising:
- fabricating said devices on an insulating substrate by successive deposition of silicon gate, silicon oxide gate insulation, and conductive silicon layers, annealing at between about 500.degree. to 700.degree. C. for between about 10 to 24 hours;
- ion implanting, passivating, contact hole opening, and forming a metal pattern to produce complete devices;
- exposing said devices to a first plasma passivation step in a water vapor environment, wherein said first plasma passivation step exposes said devices to a plasma process comprising:
- maintaining said devices in a reactor chamber at a device holder temperature of between about 200.degree. to 240.degree. C.;
- sustaining an electrical plasma therein in said water vapor environment comprising water vapor at a gas flow rate of between about 400 to 600 standard cubic centimeters per second and a total gas pressure of about 1.5 to 2.5 Torr;
- supplying microwave power at between about 1200 to 1600 watts to the reactor at a frequency of 2.45 GHz to sustain the plasma;
- and
- exposing said devices to said plasma for about 10 to 30 seconds;
- exposing said devices to a second plasma stripping step in a water vapor environment;
- and
- annealing of said devices.
A method for the fabrication of silicon-gate thin film field effect transistors with optimized device electrical parameters comprising:
- depositing a polycrystalline silicon gate layer on an insulating substrate;
- depositing a silicon oxide gate insulation layer on the silicon gate layer;
- depositing a silicon conductive layer on the gate insulation layer;
- forming of higher-conductivity regions by ion implantation into the conductive silicon layer to form the source and drain regions which define the device channel dimensions;
- passivating already-deposited layers by covering them with a glass passivation layer;
- etching of electrical contact holes through the glass passivation layer;
- depositing and defining a pattern of conductive metal layer to form gate, source, and drain electrical contacts and interconnections;
- exposing devices to electrical plasmas, comprising a first passivation step and a second stripping step, wherein the first passivation step comprises:
- maintaining devices in a reactor chamber at a holder temperature of between about 200.degree. to 240.degree. C.;
- sustaining an electrical plasma therein in a water vapor gaseous environment at a pressure of between about 1.5 and 2.5 Torr and a gas flow rate of between about 400 to 600 standard cubic centimeters per second;
- supplying microwave power to sustain said plasma at between about 1200 to 1600 watts at a frequency of 2.45 GEv;
- and
- exposing devices to said plasma for between about 10 to 30 seconds;
- and
- annealing.
Dependencies are inferred from the claim text.