Atomic layer etch systems for selectively etching with halogen-based compounds
A substrate processing system includes a processing chamber, a substrate support, a heat source, a gas delivery system and a controller. The substrate support is disposed in the processing chamber and supports a substrate. The heat source heats the substrate. The gas delivery system supplies a process gas to the processing chamber. The controller controls the gas delivery system and the heat source to iteratively perform an isotropic atomic layer etch process including: during an iteration of the isotropic atomic layer etch process, performing pretreatment, atomistic adsorption, and pulsed thermal annealing; during the atomistic adsorption, exposing a surface of the substrate to the process gas including a halogen species that is selectively adsorbed onto an exposed material of the substrate to form a modified material; and during the pulsed thermal annealing, pulsing the heat source multiple times within a predetermined period to expose and remove the modified material.
1 . A substrate processing system comprising:
a processing chamber;
a substrate support disposed in the processing chamber and configured to support a substrate;
a heat source configured to heat the substrate;
a gas delivery system configured to supply a first process gas to the processing chamber; and
a controller configured to control the gas delivery system and the heat source to iteratively perform an isotropic atomic layer etch process including
during an iteration of the isotropic atomic layer etch process, performing pretreatment, atomistic adsorption, and pulsed thermal annealing,
during the atomistic adsorption, exposing a surface of the substrate to the first process gas including a halogen species that is selectively adsorbed onto an exposed material of the substrate to form a modified material, wherein the halogen species comprises a halogen gas, and
during the pulsed thermal annealing, pulsing the heat source on and off a plurality of times within a predetermined period to expose and remove the modified material.
2 . The substrate processing system of claim 1 , wherein the controller is configured to, during iterations of the pulsed thermal annealing, allow the modified material to cool between consecutive ones of thermal energy pulses of the heat source.
3 . The substrate processing system of claim 1 , wherein the heat source includes a plurality of flash lamps.
4 . The substrate processing system of claim 3 , further comprising a capacitive discharge circuit configured to discharge power to the plurality of flash lamps for each of a plurality of thermal energy pulses of the heat source.
5 . The substrate processing system of claim 3 , wherein the heat source includes a reflector having parabolic reflective portions respectively for the plurality of flash lamps.
6 . The substrate processing system of claim 3 , wherein the plurality of flash lamps include respective cooling jackets.
7 . The substrate processing system of claim 3 , further comprising a reflector that is conical-shaped and directs thermal energy from the plurality of flash lamps at the substrate.
8 . The substrate processing system of claim 3 , wherein the controller is configured to pulse the plurality of flash lamps to be on for a pulse duration of less than 4 milliseconds during at least one iteration of the pulsed thermal annealing.
9 . The substrate processing system of claim 1 , wherein the controller is configured to, during at least some of the iterations of the pulsed thermal annealing and via the heat source, heat the modified material of the substrate such that the modified material of the substrate cools down to a temperature of less than 25° C. in less than 0.5 seconds after shutting off the heat source.
10 . The substrate processing system of claim 1 , wherein:
the heat source includes a laser; and
the laser is configured to generate a laser beam, which is directed at the substrate.
11 . The substrate processing system of claim 10 , further comprising:
a plurality of mirrors; and
a plurality of motors,
wherein the controller is configured, via the plurality of motors, to steer the laser beam by moving the mirrors to span across the substrate.
12 . The substrate processing system of claim 11 , wherein:
a diameter of the substrate is 300 mm;
the substrate includes a plurality of dies; and
the controller is configured to, within the predetermined period, span across and heat each of the plurality of dies.
13 . The substrate processing system of claim 12 , wherein:
the predetermined period is one second; and
the controller is configured to heat each of the plurality of dies individually and a second predetermined number of times.
14 . The substrate processing system of claim 10 , further comprising a lens circuit configured to shape and direct the laser beam.
15 . The substrate processing system of claim 14 , wherein the lens circuit includes beam-shaping optics to convert the laser beam from a round-shaped laser beam to a square-shaped laser beam.
16 . The substrate processing system of claim 14 , wherein the lens circuit comprises:
flat-top optics to convert the laser beam from a round-shaped laser beam to a flat-top shaped laser beam; and
diffractive optics to convert the flat-top shaped laser beam to a square-shaped laser beam.
17 . The substrate processing system of claim 10 , further comprising a mirror module comprising a first mirror, a second mirror, a first motor and a second motor,
wherein the controller is configured to move the first mirror and the second mirror via the first motor and the second motor to adjust a position of the laser beam on the substrate.
18 . The substrate processing system of claim 10 , further comprising a tele-centric lens assembly comprising a plurality of lenses and configured to direct the laser beam in a direction perpendicular to the surface of the substrate.
19 . The substrate processing system of claim 18 , further comprising a mirror module comprising a first mirror, a second mirror, a first motor and a second motor, wherein:
the laser beam is directed at the first mirror;
the laser beam is directed from the first mirror to the second mirror;
the laser beam is directed from the second mirror through the tele-centric lens assembly at the substrate; and
the controller is configured to move the first mirror and the second mirror via the first motor and the second motor to adjust a position of the laser beam on the substrate.
20 . The substrate processing system of claim 19 , wherein:
the processing chamber is an inductively coupled plasma chamber or a remote plasma source connected chamber; and
the tele-centric lens assembly is disposed above a dielectric window of the processing chamber.
21 . The substrate processing system of claim 10 , further comprising a beam size adjustment module configured to adjust a size of the laser beam prior to being received by the substrate.
22 . The substrate processing system of claim 1 , wherein the processing chamber is void of plasma during the pulsed thermal annealing.
23 . The substrate processing system of claim 1 , wherein the controller is configured to set a temperature of an interior of the processing chamber, during one or more iterations of the atomistic adsorption, to be less than or equal to 20° C. or equal to an ambient temperature.
24 . The substrate processing system of claim 1 , wherein the controller is configured to control the heat source to generate a plurality of thermal energy pulses to heat the modified material of the substrate without heating at least one of a base or a bulk portion of the substrate.
25 . The substrate processing system of claim 1 , wherein the controller is configured to supply the first process gas to the processing chamber to perform the atomistic adsorption on the exposed material of the substrate between each consecutive pair of thermal energy pulses of the heat source.
26 . The substrate processing system of claim 25 , wherein the controller is configured to modify, during the pretreatment, the substrate by subjecting the substrate to a second process gas.
27 . The substrate processing system of claim 1 , wherein the controller is configured to pulse the heat source to generate a plurality of thermal energy pulses within one second.
28 . The substrate processing system of claim 1 , wherein:
the pretreatment includes introduction of a second process gas;
the second process gas includes one or more of hydrogen and ammonia;
the halogen species includes one or more of oxygen, chlorine, iodine and fluorine;
the pulsed thermal annealing includes at least one of removal of a monolayer from the substrate or selectively removing silicon without removing germanium; and
the monolayer includes one or more of germanium, silicon, titanium and silicon dioxide.
29 . The substrate processing system of claim 1 , wherein the halogen gas comprises at least one of chlorine gas (Cl 2 ), iodine gas (I 2 ), fluorine gas (F 3 ), and bromine gas (Br 2 ).
30 . The substrate processing system of claim 1 , wherein the halogen gas comprises at least one of chlorine gas (Cl 2 ) and iodine gas (I 2 ).
31 . The substrate processing system of claim 1 , wherein the halogen gas comprises fluorine gas (F 3 ).
32 . The substrate processing system of claim 1 , wherein the pulsed thermal annealing includes selective removal of silicon and not removal of germanium.