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EP-4735663-A1 - METHOD OF PROVIDING A PROCESS GAS FOR A CVD REACTOR AND CORRESPONDING APPARATUS

EP4735663A1EP 4735663 A1EP4735663 A1EP 4735663A1EP-4735663-A1

Abstract

The invention relates to an arrangement for provision of a process gas for a CVD reactor, having a first carrier gas feed with a first mass flow regulator having a small flow range and a second carrier gas feed with a second mass flow regulator having a large flow range, each of which is fed by a carrier gas source, wherein the carrier gas feed opens out in an evaporation device for evaporation of a solid or liquid starting material, from which there originates a process gas feed to the CVD reactor, wherein, disposed downstream of the second mass flow regulator in the second carrier gas feed with the second mass flow regulator, there is a valve arrangement that has an inlet and a first outlet having flow connection to the evaporation device and having a second outlet having flow connection to a bypass conduit that does not open into the evaporation device, wherein, by switching of the valve arrangement, the mass flow of carrier gas regulated by the mass flow regulator electively flows through or past the evaporation device, and to a method of operating such an arrangement.

Inventors

  • LAUFFER, PETER SEBALD

Assignees

  • Aixtron SE

Dates

Publication Date
20260506
Application Date
20240618

Claims (11)

  1. 1. Method for providing a process gas for a CVD reactor (1, 1', 1"), wherein a first carrier gas supply line (2) and a second carrier gas supply line (4) open into an evaporation device (6) for evaporating a solid or liquid starting material, wherein a process gas supply line (7) to the CVD reactor (1, T, 1") originates from the evaporation device (6), wherein a first mass flow controller (3) with a small flow range is arranged in the first carrier gas supply line (2) and a second mass flow controller (5, 5') with a large flow range is arranged in the second carrier gas supply line (4, 4'), wherein a solid or liquid starting material is evaporated in the evaporation device (6), wherein in a first method step a first mass flow of a carrier gas fed from a carrier gas source into the first carrier gas supply line (2) and a second mass flow controller (5, 5') regulated second mass flow of the carrier gas fed from the carrier gas source into the second carrier gas feed line (4, 4') flows through the evaporation device (6) into the process gas feed line (7), wherein in a second method step only the first mass flow regulated by the first mass flow (3) flows into the evaporation device (6) and the second mass flow is guided past the evaporation device (6) through a bypass line (12, 12') and conveyed into the process gas feed line (7), wherein the total carrier mass flow flowing through the evaporation device (6) in the first method step is greater than in the second method step.
  2. 2. Method according to claim 1, characterized in that when changing from the first method step to the second method step, a first valve (13, 13') arranged in the second carrier gas supply line (4, 4') is closed and a valve (13, 13') arranged in the second carrier gas supply line (4, 4') is a second valve (14, 14') arranged in the branched bypass line (12, 12') is closed.
  3. 3. Method according to one of the preceding claims, characterized in that the first valve (13, 13') and the second valve (14, 14') are switched with a time delay, wherein first the first valve (13, 13') is closed and subsequently the second valve (14, 14') is opened.
  4. 4. Method according to one of the preceding claims, characterized in that when switching from the second method step to the first method step, the second valve is first closed and subsequently the first valve (13, 13') is opened.
  5. 5. Method according to one of the preceding claims, characterized in that a variable cross-sectional constriction of a throttle opening in the valves (13, 13', 14, 14') prevents the first mass flow regulated by the first mass flow controller (3) from flowing into the bypass line (12, 12') when switching between the first and the second method step.
  6. 6. Device for carrying out a method according to one of the preceding claims with a first carrier gas supply line (2) with a first mass flow controller (3, 3') having a small flow range and with a second carrier gas supply line (4, 4') with a second mass flow controller (5, 5') having a large flow range, each of which is fed by a carrier gas source and controlled by a control device, wherein the carrier gas supply lines (2, 4, 4') are connected to an evaporation device (6) for evaporating a solid or liquid a process gas feed line (7) to a CVD reactor (1, 1', 1") originating from the evaporation device (6), a valve arrangement (8, 8') controlled by the control device being arranged in the second carrier gas feed line (4, 4') downstream of the second mass flow controller (5, 5'), which valve arrangement has an inlet (9, 9'), a first outlet (10, 10') fluidly connected to the evaporation device (6), and a second outlet (11, 11'), characterized in that the second outlet (11, 11') is fluidly connected to a bypass line (12, 12') which is guided past the evaporation device (6) and opens into the process gas feed line (7).
  7. 7. Device according to claim 6, characterized in that the control device is arranged to carry out a method according to one of claims 1 to 5.
  8. 8. Device according to claim 6 or 7, characterized in that the valve arrangement (8, 8') is a changeover valve that comprises a first valve (13, 13') arranged in the second carrier gas supply line (4, 4') and a second valve (14, 14') arranged in the bypass line (12, 12').
  9. 9. Device according to claim 6, 7 or 8, characterized in that the valves (13, 13', 14, 14') of the switching valve (8, 8') have throttle openings which are designed such that when the switching valve (8, 8') is switched, a positive pressure difference between an inlet pressure and an outlet pressure is obtained at the first valve (13, 13') or at the second valve (14, 14'), so that a carrier gas mass flow controlled by the first mass flow controller (3) is not guided past the evaporation device (6).
  10. 10. Device for carrying out a method according to one of claims 1 to 5, with a first carrier gas supply line (2) with a first mass flow regulator (3, 3') having a small flow range and with a second carrier gas supply line (4, 4') with a second mass flow regulator (5, 5') having a large flow range, wherein the carrier gas supply lines (2, 4, 4') open into an evaporation device (6) for evaporating a solid or liquid starting material, wherein a process gas supply line (7) to a CVD reactor (1, 1', 1") arises from the evaporation device (6), wherein in the second supply line (4, 4') downstream of the second mass flow regulator (5, 5') a valve arrangement (8, 8') controlled by a control device is arranged, which has an inlet (9, 9'), a first outlet flow-connected to the evaporation device (6) (10, 10') and a second outlet (11, 11'), wherein the second outlet (11, 11') is fluidly connected to a bypass line (12, 12') which is guided past the evaporation device (6) and opens into the process gas supply line (7), characterized in that the valves (13, 13', 14, 14') of the changeover valve (8, 8') have variably controllable throttle openings.
  11. 11. Method or device, characterized by one or more of the characterizing features of one of the preceding claims.

Description

Description Method for providing a process gas for a CVD reactor and related device field of technology [0001] The invention relates to a method for providing a process gas for a CVD reactor, each with a first carrier gas supply line fed by a carrier gas source with a first mass flow regulator having a small flow range and a second carrier gas supply line with a second mass flow regulator having a large flow range, wherein the carrier gas supply line opens into an evaporation device for evaporating a solid or liquid starting material which originates from a process gas supply line to the CVD reactor, wherein a valve is arranged in the second carrier gas supply line having the second mass flow regulator, which valve has an inlet and a first outlet fluidly connected to the evaporation device. The invention further relates to a device suitable for this purpose. State of the art [0002] DE 10 2021 117457 A1 describes an arrangement for providing a process gas for use in one or more CVD reactors. An evaporation device is provided which has a supply line through which a carrier gas can flow from a carrier gas source into a container of the evaporation device. The carrier gas supply line is connected to two mass flow controllers arranged parallel to one another, which can have different flow ranges from one another. In the supply line to the mass flow controller, which has a larger value range, a shut-off valve is arranged upstream of the mass flow controller. The mass flow controller can be selectively switched on by means of this shut-off valve. [0003] DE 10 2019117543 A1 discloses a gas mixing system of a substrate treatment device, in particular of a (MOCVD) reactor. The carrier gas supply line is connected to a mass flow controller. Downstream of the mass flow controller, a valve is arranged with which the supply line to the evaporation device can be closed. With a further valve, the mass flow controller can be brought into a flow connection with a bypass line for calibration, which opens into the gas outlet of the reactor. [0004] US 10,109,483 B2 discloses a MOCVD reactor system with an evaporation vessel of an evaporation device containing a liquid precursor. A carrier gas mass flow, regulated by a mass flow controller, flows from a gas source into the evaporation vessel through a carrier gas supply line. A valve is arranged downstream of the mass flow controller. When this valve is closed, the carrier gas can flow through a bypass line that is connected to the process gas supply line via a three-way valve. [0005] US 2014/0083512 A1 describes an evaporation source into which two supply lines open, through which nitrogen can be fed into an evaporation chamber. A process gas line emerges from the evaporation chamber, with which steam can be transported from the evaporation chamber to a process chamber of a CVD reactor. The two supply lines are each connected to the process gas line by a bypass line. [0006] US 2017/0362701 A1 describes an evaporation source with several evaporation chambers that are part of a central gas supply. A supply line leads into each of the evaporation chambers, which is connected via a bypass line can be connected to a drain if one of the evaporation chambers is to be changed. [0007] DE 10 2020 103822 A1 describes a device for vaporizing a powder, wherein two supply lines open into an evaporation chamber. One of the two supply lines has a valve arrangement with which a carrier gas flow fed into the evaporation chamber in a first operating position can be guided around the evaporation chamber in a second operating position. Summary of the Invention [0008] In order to realize several flow ranges for a carrier gas mass flow flowing through an evaporation vessel of an evaporation device of a CVD reactor, in the prior art a second mass flow controller covering a larger flow range is connected in parallel to a first mass flow controller covering a small flow range, whereby the second mass flow controller can be connected to it via a valve arranged upstream. In order to reduce the carrier gas mass flow and limit it again to the flow range of the first mass flow controller, the second mass flow controller is inactivated with the valve. For this purpose, the second mass flow controller is regulated to a minimum flow. The volume between the mass flow controller and the shut-off valve is kept at overpressure. Due to a dead volume that cannot be avoided as a result, a carrier gas mass flow that ebbs away over time flows into the evaporation vessel of an evaporation device even after inactivation, in addition to the carrier gas mass flow that flows through the first mass flow controller. This leads to a significant distortion of the gas feed into the evaporation vessel, especially at small carrier gas mass flows. [0009] The invention is based on the object of taking measures with which a short-term and precise switchover from a high carrier gas mass flow to a low carrier gas mass flow is possibl