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US 12,044,585 B1Granted
On-chip integrated silicon carbide pressure and temperature sensors
AssigneeUnited States Government Administrator of NASA
InventorRobert S. Okojie
Life of this patent
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Abstract
An integration of silicon carbide (SiC) pressure sensor and a temperature sensor on a single SiC substrate to facilitate the simultaneous measurement of pressure and temperature at temperature, and a method of fabricating the same.
Claims17
A method for fabricating an integrated pressure sensor and temperature sensor on a single silicon carbide (SiC) substrate, comprising:
- obtaining an n-type 4H-SiC epilayer on semi-insulating 4H-SiC substrate;
- depositing aluminum on the 4H-SiC epilayer;
- performing reactive ion etching, by using an aluminum mask, into the 4H-SiC epilayer and semi-insulating the substrate;
- stripping the aluminum and depositing another layer of aluminum;
- depositing a metallization stack into a trench and on a surface of the substrate;
- depositing a first oxide onto the metallization stack;
- depositing a nickel seed layer on a backside of the metallization stack;
- performing reactive ion etching to etch into the backside to form a diaphragm with a predefined diaphragm thickness;
- creating ohmic contacts in the first oxide;
- depositing ohmic contact metallization and performing self-aligned rapid thermal anneal;
- creating ohmic contact patterns and cleaning the substrate in solvents;
- depositing a second oxide, opening diffusion barrier vias, depositing diffusion barrier metallization, annealing diffusion barrier metallization by blanket rapid thermal anneal, depositing a third oxide layer and annealing;
- creating bond pads vias in the third oxide and cleaning the substrate in acetone;
- depositing bond pad metallization and performing a rapid thermal anneal;
- and
- using standard photolithography and applying etching to the ohmic contact pattern, and etching pressure sensor bond pads to create the SiC substrate.
13 more elements
A method for fabricating an integrated pressure sensor and temperature sensor on a single silicon carbide (SiC) substrate, comprising:
- obtaining an n-type 4H-SiC epilayer on semi-insulating 4H-SiC substrate;
- creating piezoresistive patterns and structures in the epilayer;
- growing or depositing silicon dioxide on the patterned piezoresistors;
- depositing a Ti90:Ni10 seed layer on a backside of a wafer;
- and electroplating nickel to form a mask;
- using nickel as the mask, reactive ion etching the backside of the wafer to form a diaphragm with a predefined diaphragm thickness;
- creating, by using standard lithography and reactive ion etching, ohmic contact vias in an oxide to a SiC surface and cleaning the wafer in piranha clean;
- depositing ohmic contact metallization and performing self-aligned thermal anneal;
- creating ohmic contact patterns and cleaning the wafer in an acetone and isopropanol solvents;
- depositing a second oxide, opening diffusion barrier vias, depositing diffusion barrier metallization, performing blanket rapid thermal anneal diffusion barrier metallization, performing pattern and etch diffusion barrier metallization, and depositing a third oxide layer;
- depositing a metallization stack;
- applying a spin-on-glass (SOG) over wafer and performing curing;
- performing standard photolithography and applying etching to open bond pad vias in the SOG and the third oxide layers;
- depositing a bond pad metallization on the wafer;
- applying standard photolithography and etching to pattern and etch the pressure sensor bond pads;
- and
- depositing gold followed by pattern and etching to create the SiC substrate.
14 more elements
Dependencies are inferred from the claim text.