SiC substrate with SiC epitaxial film

A method of manufacturing a 4H-SiC epiwafer comprising an epitaxial SiC filer on a single-crystal 4H-SiC substrate, the method comprising:

• a. loading the single-crystal 4H-SiC substrate onto a susceptor in a reaction cell of a warm wall CVD system;
• b. heating the system by controlling a temperature of the susceptor in the reaction cell to a range from 1500° C. to 1620° C.;
• and
• c. executing a manufacturing run to produce the 4H-SiC epiwafer, the manufacturing run comprising supplying a gas flow parallel to a surface of the single-crystal 4H-SiC substrate, such that a total gas velocity is in a range from 120 to 250 cm/sec and controlling a pressure inside the reaction cell to a range from 100 to 150 mbar, wherein the gas flow comprises a mixture of hydrogen gas, silicon gas, and carbon gas, in order to produce the epitaxial SiC film on the single-crystal 4H-SiC substrate;
• and,
• further comprising:
• d. measuring performance metrics of the 4H-SiC epiwafer;
• and
• e. removing the used reaction cell when the measured performance metrics of the 4H-SiC epiwafer fall below acceptable threshold limits.

A method of manufacturing a 4H-SiC epiwafer comprising an epitaxial SiC film on a single-crystal 4H-SiC substrate, the method comprising:

• a. loading the single-crystal 4H-SiC substrate onto a susceptor in a reaction cell of a warm wall CVD system:
• b. heating the system by controlling a temperature of the susceptor in the reaction cell to a range from 1500° C. to 1620° C.;
• and
• c. executing a manufacturing run to produce the 4H-SiC epiwafer, the manufacturing run comprising supplying a gas flow parallel to a surface of the single-crystal 4H-SiC substrate, such that a total gas velocity is in a range from 120 to 250 cm/sec and controlling a pressure inside the reaction cell to a range from 100 to 150 mbar, wherein the gas flow comprises a mixture of hydrogen gas, silicon gas, and carbon gas, in order to produce the epitaxial SiC film on the single-crystal 4H-SiC substrate;
• wherein step (a) is preceded by pre-treating the reaction cell, the pre-treating comprising:
• a. loading a sacrificial substrate onto the susceptor in the reaction cell;
• b. sealing and evacuating the reaction cell;
• c. purging the reaction cell using inert and hydrogen gases;
• d. baking the reaction cell at a temperature in the range 1400° C. to 1700° C. while flowing hydrogen gas mixed with 1% to 10% hydrocarbon gas;
• e. performing a CVD deposition process so as to deposit an SiC film on the sidewall and ceiling of the reaction cell;
• and
• f. removing the sacrificial substrate from the reaction cell.

A method of manufacturing a 4H-SiC epiwafer comprising an epitaxial SiC film on a single-crystal 4H-SiC substrate, the method comprising:

• a, loading the single-crystal 4H-SiC substrate onto a susceptor in a reaction cell of a warm wall CVD system;
• b. heating the system by controlling a temperature of the susceptor in the reaction cell to a range from 1500° C. to 1620° C.;
• and
• c. executing a manufacturing run to produce the 4H-SiC epiwafer, the manufacturing run comprising supplying a gas flow parallel to a surface of the single-crystal 4H-SiC substrate, such that a total gas velocity is in a range from 120 to 250 cm/sec and controlling a pressure inside the reaction cell to a range from 100 to 150 mbar, wherein the gas flow comprises a mixture of hydrogen gas, silicon gas, and carbon gas, in order to produce the epitaxial SiC film on the single-crystal 4H-SiC substrate;
• wherein step (c) comprises:
• a. placing the single-crystal 4H-SiC substrate on the susceptor in the reaction cell of the warm wall CVD system;
• b. evacuating the reaction cell and then purging the reaction cell with argon;
• c. terminating the argon flow and initiating hydrogen gas flow into the reaction cell;
• d. establishing the temperature gradient from the surface of the epiwafer to a ceiling of the reaction cell in the range from 25° C./cm to 80° C./cm;
• e. flowing parallel to the surface of the epiwafer a gas mixture of hydrogen, silicon and carbon gases, at a total gas velocity of 120 to 250 cm/sec;
• f. maintaining the process conditions to achieve a total deposit of from 3 to 120 μm of film on the single-crystal 4H-SiC substrate in order to produce the epitaxial SiC film on the single-crystal 4H-SiC substrate;
• g. cooling the system to a temperature less than 300° C.;
• and
• h. removing the single-crystal 4H-SiC substrate.

A method of manufacturing a 4H-SiC epiwafer comprising an epitaxial SiC film on a single-crystal 4H-SiC substrate, the method comprising:

• a. loading the single-crystal 4H-SiC substrate onto a susceptor in a reaction cell of a warm wall CVD system;
• b. heating the system by controlling a temperature of the susceptor in the reaction cell to a range from 1500° C. to 1620° C.;
• and
• c. executing a manufacturing run to produce the 4H-SiC epiwafer, the manufacturing run comprising supplying a gas flow parallel to a surface of the single-crystal 4H-SiC substrate, such that a total gas velocity is in a range from 120 to 250 cm/sec and controlling a pressure inside the reaction cell to a range from 100 to 150 mbar, wherein the gas flow comprises a mixture of hydrogen gas, silicon gas, and carbon gas, in order to produce the epitaxial SiC film on the single-crystal 4H-SiC substrate;
• wherein the reaction cell comprises a graphite reaction cell, and further comprises coating the reaction cell's graphite components with pyrocarbon or tantalum carbide films prior to assembling the cell for use in CVD epitaxy.

A single-crystal 4H-SiC substrate with epitaxial SiC film produced by the method comprising:

• a. loading the sing1e-crystal 4H-SiC substrate a e onto a susceptor in a reaction cell of a warm wall CVD system;
• b. heating the system by controlling a temperature of the susceptor in the reaction cell to a range from 1500′C. to 1620° C.;
• and
• c. executing a manufacturing run to produce the 4H-SiC epiwafer, the manufacturing run comprising supplying a gas flow parallel to a surface of the single-crystal 4H-SiC substrate, such that a total gas velocity is in a range from 120 to 250 cm/sec and controlling a pressure inside the reaction cell to a range from 100 to 150 mbar, wherein the gas flow comprises a mixture of hydrogen gas, silicon gas, and carbon gas, in order to produce the epitaxial SiC film on the single-crystal 4H-SiC substrate;
• wherein,
• a. a within wafer total thickness variation of the epitaxial SiC film is from 2 to 12%, inclusive;
• b. a within wafer dopant concentration variation of the epitaxial SiC film is from 5 to 40%, inclusive;
• c. a top surface of the epitaxial SiC film has an RMS roughness value of 0.2 to 2 nm;
• inclusive;
• and
• d. a density of surface defects on the epitaxial SiC film is from 0.25 to 2.0/cm2, inclusive.

A method of forming a 4H-SiC epiwafer comprising an epitaxial SiC film on a single-crystal 4H-SiC substrate positioned on a susceptor in a warm wall CVD system, the warm wall CVD system having a reaction cell comprising the susceptor positioned at a bottom, a sidewall, and a ceiling, wherein the susceptor is actively heated, and the ceiling and sidewall are not actively heated, but are allowed to be indirectly heated by the susceptor, the method comprising:

• a. inserting an unused reaction cell assembly into a CVD epitaxy system;
• b. a first process for treatment of the reaction cell preparation;
• and
• c. a second process for epitaxial film growth;
• wherein:
• the first process for treatment of the reaction cell preparation comprises the steps:
• i. loading the susceptor with a sacrificial substrate;
• ii. sealing and evacuating the reaction cell;
• iii. purging the reaction cell using argon and hydrogen gases;
• iv. baking the reaction cell in a mixture of hydrogen and hydrocarbon gas;
• and
• v. performing a CVD deposition process so as to deposit an SiC film on the sidewall and ceiling of the reaction cell;
• and
• the second process for epitaxial film growth comprises the steps:
• vi. allowing the reaction cell to cool;
• vii. placing the single-crystal 4H-SiC substrate on the susceptor;
• viii. evacuating and then purging the reaction cell with argon gas;
• ix. heating the susceptor to a temperature of 1200° C. to 1400° C., inclusive;
• x. terminating the argon flow and initiating hydrogen gas flow into the reaction cell;
• xi. flowing parallel to the surface of the wafers a gas mixture of hydrogen, silicon and carbon gases, at a total gas velocity of 120 to 250 cm/sec;
• xii. maintaining a temperature of the susceptor at 1500° C. to 1620° C.;
• and
• xiii. controlling a pressure inside the reaction cell at from 100 to 150 mbar, inclusive, to achieve a total deposit of 3 to 120 μm of film on the substrate.