Airflow controlling method to be used in air float cyclone operation of low pressure heat treatment apparatus

Abstract

To provide an airflow controlling method to be used in an air float cyclone operation of a low pressure heat treatment apparatus.SOLUTION: A method includes controlling the pressure of a process gas in a process chamber to 1 to 20 Torr by a pressure sensor installed in the process chamber of a low pressure heat treatment apparatus, controlling the flow rate of a cyclone gas to be conveyed toward the bottom surface of a tray of the low pressure heat treatment apparatus to 0.5 to 1.5 L / min while the flow rate control is performed with an accuracy of within ±0.2 L / min, and adjusting the flow rate of the cyclone gas such that the tray rotates together with a semiconductor workpiece on the upper surface of the tray. According to the airflow controlling method, the flow rate of the cyclone gas is accurately controlled such that the tray can rotate stably together with the semiconductor workpiece thereon.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This invention relates to the field of semiconductor manufacturing, and more particularly to an airflow control method used in air float cyclone operation of low pressure thermal processing equipment. [Background technology]

[0002] Rapid thermal annealing equipment is a necessary process in wafer manufacturing. The temperature of the annealing process is usually 200-1250℃, and the time of the annealing process is usually several tens of seconds. The uniformity of the temperature of each area on the whole wafer is extremely important. In practical application, the minute difference of the heating lamp function, the difference of the parallelism between the wafer and the lamp, the local difference inside the reaction chamber, etc. are easy to cause local temperature non-uniformity on the wafer. Therefore, in order to reach the uniformity of the annealing temperature on the whole wafer, the annealing equipment needs to rotate during the process. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention provides a method for controlling airflow in a low pressure environment for a tray of a thermal processing device to perform air float cyclone operation. [Means for solving the problem]

[0004] According to one aspect of the present invention, there is provided a method of controlling airflow for use in air float cyclone operation of a low pressure thermal processing device, the method comprising: controlling the pressure of the process gas in the process chamber to 1 to 20 Torr by a pressure sensor installed in the process chamber of the low pressure heat treatment device; By flow control, the flow rate of the cyclone gas conveyed toward the bottom surface of the tray of the low-pressure heat treatment device is controlled to 0.5 to 1.5 L / min, and the accuracy is controlled within ±0.2 L / min; and adjusting the flow rate of the cyclone gas so that the tray rotates together with the semiconductor workpieces placed on the upper surface of the tray.

[0005] According to the airflow control method of the present invention, the flow rate of the cyclone gas is accurately controlled, so that the tray can rotate stably together with the semiconductor workpieces thereon.

[0006] It should be understood that the contents described herein are not intended to describe key points or important features of the embodiments of the present invention, and are not to be used to limit the scope of the present invention. Other features of the present invention can be understood through the following specification. [Brief description of the drawings]

[0007] The accompanying drawings are provided for a better understanding of the present invention and are not intended to limit the present invention.

[0008] [Figure 1] FIG. 2 is a side view of an air float cyclone system structure inside a process chamber of a low pressure thermal processing apparatus according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view of an air float cyclone system structure inside a process chamber of a low pressure thermal processing apparatus according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings, and various details of the embodiments of the present disclosure will be included in the description to facilitate understanding, but these should be considered as merely illustrative. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, in the following description, descriptions of well-known functions and structures are omitted for clarity and conciseness.

[0010] Current annealing equipment is a normal pressure process, and gas is used to suspend the wafer during wafer rotation, and the gas rotates the wafer tray to rotate the wafer during the process. For the wafer tray rotation gas, real-time data collection, feedback and adjustments are performed during the process, and closed-loop control is performed to achieve the wafer rotation stability requirements.

[0011] Low-pressure annealing equipment, such as remote plasma oxidation equipment (RPO) or low-pressure radical oxidation equipment (LP), belongs to high-temperature annealing equipment. For the low-pressure annealing process, very high temperature uniformity is required, but the wafer needs to be rotated during the process to meet the process uniformity requirements, so a method for rotating the wafer under low-pressure conditions (1 to 20 Torr) needs to be developed.

[0012] The present invention provides an airflow control method for use in air float cyclone operation in low pressure heat treatment equipment, which precisely controls the flow rate of the cyclone gas and thereby controls the operation of the cyclone air float member.

[0013] According to one specific embodiment, there is provided a method for controlling airflow for use in air float cyclone operation of a low pressure thermal processing device, comprising: controlling the pressure of the process gas in the process chamber to 1 to 20 Torr by a pressure sensor installed in the process chamber of the low pressure heat treatment device; By flow rate control, the flow rate of the cyclone gas conveyed toward the bottom surface of the tray of the low-pressure heat treatment device is controlled to 0.5 to 1.5 L / min, and the control accuracy is controlled within ±0.2 L / min; and adjusting the flow rate of the cyclone gas so that the tray rotates together with the semiconductor workpieces placed on the upper surface of the tray.

[0014] According to one embodiment, the cyclone gas can be nitrogen, oxygen, or a mixture of hydrogen and oxygen.Preferably, when the cyclone gas is a mixture of hydrogen and oxygen, the flow rate of hydrogen is less than or equal to 33% and is not zero, and the flow rate of oxygen is greater than or equal to 67% and less than 100%.

[0015] In the low pressure heat treatment process, due to the low pressure in the process chamber, the process gas can contain hydrogen to promote the formation of oxygen radicals and extend the retention time of oxygen radicals. According to an embodiment, the process gas can be, for example, a mixed gas of hydrogen and oxygen, and more preferably, the flow rate ratio of hydrogen is 33% or less (e.g., 25% or less, 20% or less, 18% or less, 10% or less, 5% or less) and is not zero, and the flow rate ratio of oxygen is 67% or more (e.g., 75% or more, 80% or more, 87% or more, 95% or more) and is less than 100%. From the viewpoint of safety, the hydrogen component in the process gas needs to be introduced when the pressure in the process chamber is 20 Torr or less.

[0016] The cyclone gas preferably has the same composition as the process gas to avoid the introduction of extra gas.

[0017] According to one embodiment, when the low pressure thermal processing apparatus is a remote plasma oxidation processing apparatus, the pressure in the process chamber is controlled within a range of 1 to 8 Torr (e.g., 3 Torr, 5 Torr, 6 Torr, 7 Torr) by a pressure sensor, and the flow rate of the cyclone gas is controlled within a range of 0.5 to 1 L / min (e.g., 0.6 L / min, 0.7 L / min, 0.8 L / min, 0.9 L / min) by a flow controller, with a control accuracy within ±0.1 L / min.

[0018] According to another embodiment, when the low-pressure heat treatment apparatus is a low-pressure radical oxidation treatment apparatus, the pressure in the process chamber is controlled within a range of 5 to 15 Torr by a pressure sensor, the flow rate of the cyclone gas is controlled within a range of 0.5 to 1.5 L / min by a flow controller, and the control accuracy is within ±0.2 L / min.

[0019] Furthermore, the total flow rate of the process gas is within a range of 1 to 60 slm, preferably 5 to 50 slm, for example, 16 slm, 20 slm, 30 slm, or 45 slm.

[0020] Under the above-mentioned conditions of the process gas and cyclone gas, the rotation speed of the semiconductor workpiece can be 40 to 100 rpm, preferably 60 rpm.

[0021] According to one embodiment, in the airflow control method of the present invention, the cyclone gas transported toward the bottom surface of the tray of the low-pressure heat treatment device includes cyclone gas transported in one or both of a clockwise direction and a counterclockwise direction to accelerate or decelerate the air float rotation.

[0022] The flow rates and pressures of the above process gas and air float gas must meet the above ranges and precisions, if the flow rate of the process gas is too high, the pressure in the process chamber will be too high, which may pose a safety risk, while if the flow rate is too low, the amount of gas in the process chamber will be too low, which may reduce the process uniformity. If the flow rate of the air float gas is too high, the operation stability of the air float cyclone system will be reduced, and if it is too low, it will be difficult to rotate the tray or wafer efficiently.

[0023] Referring to Figures 1 and 2, the air float cyclone system used in the low-pressure heat treatment apparatus of the present invention includes a tray 3, optionally a plurality of support needles 2 located on the upper surface of the tray for supporting the back surface of the wafer 1, an air float gas pipe 4, an air float gas outlet 5 (which may include three or more), an accelerating air float gas pipe 6, an accelerating air float gas outlet 7, a decelerating air float gas pipe 8, and a decelerating air float gas outlet 9.

[0024] The air float gas is discharged through pipe 4 and outlet 5 onto the bottom of the tray, promoting the floating and rotation of the tray. The accelerating air float gas is discharged through pipe 6 and outlet 7, promoting the forward rotation of the tray (also called the first direction). The decelerating air float gas is discharged through pipe 8 and outlet 9, promoting the rotation of the tray in the reverse direction (also called the second direction opposite to the first direction), thereby slowing down the forward rotation.

[0025] The air float cyclone system includes an air float gas control valve for controlling the intake flow rate of the air float gas, which is located on the inlet line of the air float gas, and a detection element for detecting the motion state of the tray and the wafer.

[0026] Under the action of the air float cyclone system, the tray can float and rotate, and the wafers on it can move synchronously with the tray and always stay in close contact with the top surface of the tray. When the tray floats, rotates, and stops moving, the wafers also float, rotate, and stop moving in the same way. That is, during the entire moving process, the tray keeps a stationary state relative to the wafers.

[0027] From the above, the atmospheric pressure equipment (760 Torr) uses the air float cyclone wafer rotation method, and the air float cyclone wafer rotation method can meet the process requirements and also meet the process stability requirements. Specifically, the flow rate of the cyclone gas in the atmospheric pressure equipment is usually within the range of 8 to 15 L / min, and the cyclone gas usually adopts nitrogen gas or oxygen, and the cyclone gas cannot use hydrogen because the pressure is quite large. The pressure in the process chamber is 760 Torr, and there is no need to perform pressure control or install a pressure sensor.

[0028] Compared to normal pressure equipment (760 Torr), low pressure equipment (1-20 Torr) has a smaller amount of gas in the process chamber, so the pressure in the process chamber drops significantly. Therefore, it is a big challenge to maintain stable rotation and stable characteristics of the tray and wafer during rotational motion. The method of the present invention can ensure stable rotation of both the tray and wafer in a low pressure environment by simultaneously controlling the pressure in the process chamber and the pressure and composition of the cyclone gas.

[0029] It should be understood that various forms of the above process can be used by rearranging, adding, or deleting steps. For example, but not limited to, each step described in this disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved.

[0030] The above specific embodiments do not limit the scope of protection of the present disclosure. Those skilled in the art can understand that various modifications, combinations, subcombinations and substitutions are possible according to design requirements and other factors. Any modifications, equivalent substitutions, improvements, etc. made within the gist of the present disclosure are all intended to be included in the scope of protection of the present disclosure.

Claims

1. 1. A method for controlling airflow used in an air float cyclone operation of a low pressure heat treatment device, comprising: controlling the pressure of the process gas in the process chamber to 1 to 20 Torr by a pressure sensor installed in the process chamber of the low pressure heat treatment device; By controlling the flow rate, the flow rate of the cyclone gas conveyed toward the bottom surface of the tray of the low-pressure heat treatment device is controlled to 0.5 to 1.5 L / min, and the accuracy is controlled within ±0.2 L / min; and adjusting the flow rate of the cyclone gas so that the tray rotates together with the semiconductor workpiece on the upper surface of the tray. Airflow control method.

2. The cyclone gas is nitrogen, or oxygen, or a mixture of hydrogen and oxygen; The airflow control method according to claim 1 .

3. The cyclone gas is a mixture of hydrogen and oxygen and has the same composition as the process gas. The airflow control method according to claim 1 .

4. The flow rate ratio of hydrogen gas in the cyclone gas is 33% or less and is not zero; The airflow control method according to claim 3.

5. The low pressure heat treatment apparatus is a remote plasma oxidation treatment apparatus, the pressure in the process chamber is controlled within a range of 1 to 8 Torr by a pressure sensor, and the flow rate of the cyclone gas is controlled within a range of 0.5 to 1 L / min by a flow rate controller, with an accuracy of within ±0.1 L / min. The airflow control method according to claim 1 .

6. the low-pressure heat treatment apparatus is a low-pressure radical oxidation treatment apparatus, the pressure in the process chamber is controlled within a range of 5 to 15 Torr by a pressure sensor, the flow rate of the cyclone gas is controlled within a range of 0.5 to 1.5 L / min by a flow rate controller, and the accuracy is within ±0.2 L / min; The airflow control method according to claim 1 .

7. The rotation speed of the semiconductor workpiece is 40 to 100 rpm; The airflow control method according to any one of claims 1 to 4.

8. The rotation speed of the semiconductor workpiece is 60 rpm; The airflow control method according to claim 7.

9. The total flow rate of the process gas is 1 to 60 slm; The airflow control method according to any one of claims 1 to 6.

10. The cyclone gas transported toward the bottom surface of the tray of the low-pressure heat treatment device includes the cyclone gas transported in one or both of a clockwise direction and a counterclockwise direction. The airflow control method according to claim 1 .

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