Low-pressure oxidation treatment method and device for semi-conductor workpiece

Abstract

To provide a low-pressure oxidation treatment method and a low-pressure oxidation treatment device.SOLUTION: The present invention provides a low-pressure oxidation treatment method for a semi-conductor workpiece, and a low-pressure oxidation treatment device. The low-pressure oxidation treatment method contains steps of: sucking a reaction chamber so that a pressure in the reaction chamber becomes less than 760 torr; implanting a processing gas containing a hydrogen gas and an oxygen gas into the reaction chamber; increasing a temperature in the reaction chamber to a temperature where an oxygen radical is generated from the processing gas; and exposing the semi-conductor workpiece to the oxygen radical so as to form an oxide film onto a front surface of the semi-conductor workpiece. According to the method of the present invention, by using the oxygen radical formed by the processing gas containing the hydrogen gas and the oxygen gas in a low pressure, the oxide film is formed by being reacted to the front surface of the semi-conductor workpiece; a uniformity of an oxide film layer is more increased; defects are more reduced; and an oxidation depth can be easily controlled.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to low pressure oxidation methods and apparatus for semiconductor workpieces, and more particularly to low pressure oxygen radical oxidation methods and apparatus. [Background technology]

[0002] Oxidation methods for semiconductor workpieces, especially silicon wafers, typically involve heat treatment in an atmosphere of O2, H2O / H2, H2O / O2, or O2 / H2. Conventional heat treatment processes may include methods such as melt furnace treatment, rapid thermal processing, and the like. These methods typically require temperatures in the oxidation system to exceed 700°C to provide the activation energy to grow an oxide on the surface of the silicon wafer. However, temperatures below 700°C may result in under-oxidation. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention provides a method and apparatus for low pressure oxidation processing for semiconductor workpieces. [Means for solving the problem]

[0004] In one aspect of the present invention, a low pressure oxidation processing method for a semiconductor workpiece is provided, the low pressure oxidation processing method comprising: evacuating the reaction chamber so that the pressure therein is less than 760 Torr; injecting a process gas comprising hydrogen gas and oxygen gas into the reaction chamber; raising the temperature in the reaction chamber to a temperature that generates oxygen radicals from the process gas; and exposing the semiconductor workpiece to oxygen radicals to form an oxide film on a surface of the semiconductor workpiece.

[0005] In another aspect of the present invention, a low pressure oxidation processing apparatus for a semiconductor workpiece is provided, the low pressure oxidation processing apparatus comprising a reaction chamber, at least one heating element, and a vacuum forming system.

[0006] According to the low-pressure oxidation treatment method of the present invention, the growth of the oxide film layer is promoted by utilizing oxygen radicals, thereby making it possible to improve the uniformity of the oxide film layer and reduce defects in the oxide film layer.

[0007] 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, nor are they used to limit the scope of the present invention. Other features of the present invention can be understood through the following specification.

[0008] The accompanying drawings are provided for a better understanding of the present invention and are not intended to limit the present invention. [Brief description of the drawings]

[0009] [Figure 1] 1 is a plan view of a low-pressure oxidation treatment apparatus according to an embodiment of the present invention; [Diagram 2] 1 is a right side view of a low-pressure oxidation treatment apparatus according to an embodiment of the present invention. [Diagram 3] 1 is a schematic diagram showing an oxidation process of a silicon wafer by oxygen gas. [Figure 4] 1 is a schematic diagram showing an oxidation process of a silicon wafer by oxygen radicals. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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.

[0011] Currently, semiconductor workpieces (e.g., silicon wafers) are typically treated with a remote plasma oxidation process, such as generating a plasma rich in oxygen radicals from a microwave plasma source, in a reaction chamber at atmospheric pressure and high temperature to react with silicon on the surface of the silicon wafer to produce a silica oxide film layer on the surface of the silicon wafer. In this atmospheric pressure and high temperature process, the accuracy of temperature control is particularly important for this remote plasma oxidation process.

[0012] Low pressure oxidation treatment equipment

[0013] A low pressure oxidation processing apparatus according to one embodiment of the present invention may include a workpiece support element, a reaction chamber, at least one gas source, at least one heating element, and a vacuum generation system.

[0014] Specifically, referring to Figures 1 and 2, a low-pressure oxidation processing apparatus according to a specific embodiment includes an upper lamp plate 3, a lower lamp plate 4, a reaction chamber defined by the upper lamp plate 3, the lower lamp plate 4, and a reaction chamber body 5, an upper lamp group 1 installed in the upper lamp plate 3, a lower lamp group 2 installed in the lower lamp plate 4, a wafer inlet / outlet 6 located on a side wall at one end of the reaction chamber, and at least two gas inlets located at one end opposite to the wafer inlet / outlet 6 of the reaction chamber and communicating with different gas sources.

[0015] In one embodiment, the workpiece support element located within the reaction chamber is configured to support a semiconductor workpiece to be processed and may have any shape, arrangement, and / or configuration suitable for supporting a semiconductor workpiece, and may include a rotating disk (e.g., a quartz disk) 14 and a number of support posts (e.g., quartz posts) 10 that can be raised and lowered above the rotating disk 14 for supporting and rotating the workpiece to be processed (i.e., a silicon wafer 9).

[0016] In one embodiment, the heating element may have two sets of lamps, one above the other, installed in a lamp plate to heat both sides of the semiconductor workpiece installed in the reaction chamber, thereby reducing the distortion of the wafer during the heating process, effectively improving the yield rate of the wafer, and increasing the heating rate by supplying a larger power, thereby improving the yield rate per unit time. The lamp plate may be a quartz plate.

[0017] The lamp group may have a lamp array installed in at least one region of the lamp plate. The lamps used in the present invention may be halogen lamps. The upper lamp group heats the upper surface of the wafer supported by the workpiece support element located between the upper and lower lamp plates, and the lower lamp group heats the lower surface of the wafer. Thus, the two sets of lamp groups, upper and lower, radiate and heat both sides of the wafer, thereby effectively avoiding the pattern effect and improving the stress on the wafer.

[0018] In one embodiment, the gas inlet may be provided on a side wall at one end of the reaction chamber body, on a top plate of the reaction chamber, or on a side wall at one end and on a top plate of the reaction chamber, so as to easily adjust the amount of gas injected based on the actual process and form a uniform gas flow in the reaction chamber.

[0019] In one embodiment, at least two gas inlets at one end of the reaction chamber may be connected to different gas sources (e.g., a hydrogen gas source and an oxygen gas source, which are process gases) via gas lines 7 and 8, respectively. In another specific embodiment, the gas lines may be further connected to a nitrogen source. In addition, a flow sensor (e.g., a flow meter) and / or a pressure control valve may be further installed in the gas lines 7 and 8. The flow sensor and the pressure control valve serve to accurately measure the flow rate of the gas injected into the reaction chamber and further accurately adjust the pressure in the reaction chamber to a low pressure.

[0020] In one embodiment, a vacuum generating system having a vacuum pump 13, a sensor 11, and a control valve 12, which are connected via a pipe, is installed in the lower part of the reaction chamber body at one end opposite to the gas inlet. Here, the sensor 11 and the control valve 12 are connected to communicate with a controller of the low-pressure oxidation treatment device. Specifically, the vacuum pump 13 is started to extract gas from the reaction chamber, thereby controlling the amount of gas in the reaction chamber and maintaining the pressure in the reaction chamber within a set range. The sensor 11 senses the pressure in the reaction chamber, feeds back the sensed pressure value to a controller (not shown) in the low-pressure oxidation treatment device, compares the measured pressure value with a preset value, and adjusts the opening of the control valve 12 based on the comparison result. That is, when the measured pressure value in the reaction chamber is greater than the set value, the opening of the control valve 12 is adjusted to be larger, thereby increasing the amount of extracted gas and thereby reducing the pressure in the reaction chamber, whereas when the measured pressure value in the reaction chamber is smaller than the set value, the opening of the control valve 12 is adjusted to be smaller, thereby decreasing the amount of extracted gas and thereby reducing the pressure in the reaction chamber.

[0021] In one embodiment, the pressure in the reaction chamber needs to be, for example, less than 760 Torr. Specifically, the low pressure is 1-20 Torr, preferably 2-15 Torr, and may be, for example, 3 Torr, 4 Torr, 6 Torr, 8 Torr, 10 Torr, or 12 Torr. In the present invention, the pressure control accuracy is within 0.1 Torr.

[0022] In one embodiment, the low pressure oxidation processing apparatus of the present invention can achieve a thickness of 15-130 angstroms, such as 50 angstroms, 70 angstroms, 90 angstroms, 105 angstroms, 120 angstroms, etc.

[0023] The low-pressure oxidation processing apparatus can oxidize the surface of a silicon wafer at a low pressure (preferably a pressure of 1 to 20 Torr) with high quality, thereby forming a silicon oxide film with high uniformity, few defects, and a large oxidation depth.

[0024] Low pressure oxidation treatment method

[0025] In one aspect of the present invention, a low pressure oxidation processing method for a semiconductor workpiece is provided, the low pressure oxidation processing method comprising: evacuating the reaction chamber so that the pressure therein is less than 760 Torr; injecting a process gas comprising hydrogen gas and oxygen gas into the reaction chamber; raising the temperature in the reaction chamber to a temperature that generates oxygen radicals from the process gas; and exposing the semiconductor workpiece to oxygen radicals to form an oxide film on a surface of the semiconductor workpiece.

[0026] In one embodiment, the low pressure oxidation process of the present invention is carried out at a low pressure of less than 760 Torr, specifically 1 to 20 Torr, preferably 2 to 15 Torr, for example, 3 Torr, 4 Torr, 6 Torr, 8 Torr, 10 Torr, 12 Torr.

[0027] In one embodiment, the generation of oxygen radicals by the process gas may be performed at 750 to 1100°C, preferably 800 to 1000°C, more preferably 850 to 950°C, for example, 880°C or 900°C.

[0028] In one embodiment, the process gas used in the low pressure oxidation treatment method includes hydrogen gas and oxygen gas, and preferably consists of hydrogen gas and oxygen gas. The total flow rate of the process gas may be 20-60 L / min, preferably 25-55 L / min, more preferably 30-50 L / min, for example, 35 L / min, 40 L / min, 45 L / min, 48 L / min. If the total flow rate is too high, it will affect the uniformity of the generated oxide film layer, and if it is too low, the pressure control will become unstable, which will result in defects in the generated oxide film layer or uneven thickness. Specifically, the flow rate percentage of hydrogen gas relative to the total flow rate of the process gas may be greater than 0 and less than or equal to 33%, preferably 1 to 28%, more preferably 5 to 25%, for example, 8%, 12%, 15%, 18%, 20%, or 23%, and the flow rate percentage of oxygen gas may be greater than or equal to 67% but not 100%, preferably 70 to 95%, more preferably 75 to 90%, for example, 80% or 85%.

[0029] In the low pressure oxygen treatment method of the present invention, the process gas contains hydrogen gas and oxygen gas, so that under the above-mentioned low pressure and high temperature conditions, the oxygen gas is cleaved to generate oxygen radicals. The presence of hydrogen gas extends the life time of the oxygen radicals, accelerates the oxidation rate, improves the oxidation treatment rate, and helps to increase the thickness of the formed oxide layer and accelerate the growth rate, but it is difficult to control the uniformity of the oxide layer. Therefore, it is necessary to complete the oxidation treatment with an appropriate hydrogen gas flow rate and process time.

[0030] Furthermore, from the viewpoint of process safety, hydrogen gas injection should be started only when the pressure in the reaction chamber is less than 20 Torr. The process gas may be injected from the side, top, or both sides of the reaction chamber to form a uniform gas flow on the surface of the wafer.

[0031] The low-pressure oxidation method of the present invention includes forming oxygen radicals using a process gas containing hydrogen gas and oxygen gas under low-pressure and high-temperature conditions, and then oxidizing silicon on the wafer surface to form a silicon oxide layer. Specifically, referring to FIG. 3, a schematic diagram of the process of oxidizing a silicon wafer using oxygen gas in a conventional method is shown. Here, under high-temperature conditions, oxygen gas first reacts with silicon on the silicon wafer surface to generate silicon oxide, and gradually forms a silicon oxide layer. If an oxide layer needs to be formed deeper, oxygen molecules need to pass through the formed silicon oxide layer, but the passage speed of oxygen molecules to the deep silicon is slowed down due to the blocking of the formed silicon oxide molecules. This slows down the oxidation speed and limits the uniformity of the oxide layer.

[0032] FIG. 4 shows a schematic diagram of the oxidation process of the low-pressure oxidation method according to the present invention. Here, under the above-mentioned low-pressure and high-temperature conditions, oxygen gas is cleaved to generate oxygen radicals. In contrast, the diameter of the oxygen molecule is about 0.346 nm, and the diameter of the oxygen radical is about 0.148 nm. That is, the oxygen radical has a significantly smaller diameter than the oxygen molecule. Therefore, in the presence of hydrogen gas, the oxygen radical first reacts with the silicon on the surface of the silicon wafer to generate silicon oxide, and gradually forms a silicon oxide layer. If it is necessary to form an oxide layer further in, the oxygen radical also needs to pass through the formed silicon oxide layer. Although there is still a blockage of the generated silicon oxide particles, due to their small diameter, the oxygen radical is easy to diffuse into the silicon layer of the wafer. This significantly increases the passage speed to the deep silicon, which is favorable for the growth of the oxide film layer. Therefore, according to the oxidation method of the present invention, it is possible to increase the oxidation rate, increase the uniformity of the oxide layer, reduce defects, and increase the quality of the film layer.

[0033] The low pressure in the reaction chamber required for the low pressure oxidation treatment method of the present invention must be realized by a pressure control system. In one embodiment, as shown in FIG. 1 and FIG. 2, this pressure control system may have a gas source communicating with a gas inlet and a vacuum generation system. In the present invention, the total flow rate of the process gas is controlled to 20 to 60 L / min and maintained constant by controlling the flow rate of the gas, for example, the process gas, to be injected into the reaction chamber. The flow rate of the injected gas is measured by a flow sensor (for example, a flow meter) and / or a pressure control valve installed in the gas pipes 7 and 8. In order to maintain the low pressure in the reaction chamber, a vacuum generation system having a vacuum pump 13, a sensor 11, and a control valve 12 is installed at one end opposite to the gas inlet, and the vacuum pump 13 is started to extract gas from the reaction chamber while maintaining the flow rate of the injected gas almost constant, thereby controlling the amount of gas in the reaction chamber and maintaining the pressure in the reaction chamber within a set range. Furthermore, the sensor 11 senses the pressure in the reaction chamber, feeds back the sensed pressure value to a controller (not shown) in the low-pressure oxidation treatment device, compares the measured pressure value with a preset value, and adjusts the opening of the control valve 12 based on the comparison result. That is, when the measured pressure value in the reaction chamber is greater than the set value, the opening of the control valve 12 is adjusted to be larger, increasing the amount of extracted gas and lowering the pressure in the reaction chamber, whereas when the measured pressure value in the reaction chamber is smaller than the set value, the opening of the control valve 12 is adjusted to be smaller, decreasing the amount of extracted gas and lowering the pressure in the reaction chamber.

[0034] Under the low pressure of 1 to 20 Torr required by the present invention, the amount of gas in the chamber is small, so accurate control of the pressure in the reaction chamber is important for the generation of oxygen radicals and the high quality and efficient progress of the oxidation reaction.

[0035] The low pressure oxidation processing method according to the present invention further includes filling the reaction chamber with nitrogen gas before the semiconductor workpiece (e.g., wafer) to be processed enters the reaction chamber and after the low pressure oxidation reaction is completed.

[0036] According to the low-pressure oxidation method of the present invention, oxygen radicals are generated from oxygen under low-pressure and high-temperature conditions, and the oxygen radicals have a longer survival time due to the promotion of hydrogen gas, which makes it easier for them to diffuse to deeper silicon layers. This leads to a larger oxidation depth and reduced defects in the oxide film layer, thereby resulting in a high-quality oxide film layer that can be used in various high-quality processes.

[0037] 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.

[0038] 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 low pressure oxidation processing method for a semiconductor workpiece, comprising: evacuating the reaction chamber so that the pressure therein is less than 760 Torr; injecting a process gas comprising hydrogen gas and oxygen gas into the reaction chamber; raising the temperature in the reaction chamber to a temperature that generates oxygen radicals from the process gas; exposing the semiconductor workpiece to the oxygen radicals to form an oxide film on a surface of the semiconductor workpiece. Low pressure oxidation treatment method.

2. generating oxygen radicals from the process gas at 750 to 1100°C; The low pressure oxidation treatment method according to claim 1.

3. the low pressure is between 1 and 20 Torr; The low pressure oxidation treatment method according to claim 1.

4. With respect to the total flow rate of the process gas, the flow rate percentage of hydrogen gas is greater than 0 and less than 33%, and the flow rate percentage of oxygen gas is less than 100% and greater than 67%. The low pressure oxidation treatment method according to claim 1.

5. begin injecting hydrogen gas after the pressure in the reaction chamber is less than 20 Torr. The low pressure oxidation treatment method according to claim 1.

6. The total flow rate of the process gas is 20 to 60 L / min; The low pressure oxidation treatment method according to claim 1.

7. The process gas is injected from the side, or the top, or both the side and the top of the reaction chamber. The low pressure oxidation treatment method according to any one of claims 1 to 6.

8. 1. A low pressure oxidation treatment apparatus for a semiconductor workpiece, comprising: comprising a reaction chamber, at least one heating element, and a vacuum generating system; Low pressure oxidation treatment equipment.

9. The vacuum generation system includes a vacuum pump, a sensor, and a control valve. The low pressure oxidation treatment apparatus according to claim 8.

10. at least one process gas inlet located in a sidewall at one end of the reaction chamber; The low pressure oxidation treatment apparatus according to claim 8.

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