Heat treatment device and method for manufacturing semiconductor substrate

Abstract

To suppress a decrease in yield and a decrease in production efficiency by accurately detecting the leakage of a cooling medium in the a treatment device.SOLUTION: A controller 70 controls a lamp voltage or a lamp current applied to multiple lamps 30 on the basis of the temperature of a semiconductor substrate W detected by a temperature detection unit 50, and calculates a differential effect amount (n) on the basis of the maximum lamp voltage or maximum lamp current applied to the multiple lamps, where n is a positive integer of 2 or more indicating the lot order of the semiconductor substrate to be processed, by using the differential effect amount (n)=(maximum lamp voltage or maximum lamp current (n)-maximum lamp voltage or maximum lamp current (n-1)) / standard deviation of the maximum lamp voltage or maximum lamp current in a specified lot range, and determines that an abnormality has occurred when the differential effect amount (n) exceeds a first threshold value.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a heat treatment apparatus and a method for manufacturing a semiconductor substrate, and more particularly to a heat treatment apparatus for heat treating a semiconductor substrate with thermal energy from a lamp and a method for manufacturing a semiconductor substrate using the heat treatment apparatus. [Background technology]

[0002] For example, silicon wafers used as substrates for semiconductor devices are required to form a defect-free layer free of void defects called crystal originated particles (COPs) on the surface and surface layer that will become the active region of the semiconductor device. Rapid thermal processing (RTP) is known as a technology that meets this requirement.

[0003] The heat treatment equipment that performs RTP (hereafter referred to as RTP equipment) can control the temperature of the wafer without variation when heating the wafer to a specified temperature. Also, in order to rapidly heat the silicon wafer to a temperature exceeding 1200°C, the equipment is designed to efficiently absorb the radiation from the lamp, which is the heat source, into the silicon wafer and minimize energy loss.

[0004] In addition, since the RTP equipment rapidly heats up to a maximum temperature exceeding 1200°C and then rapidly cools down, cooling water (refrigerant) is circulated inside the RTP equipment to cool the equipment temperature. For example, in Patent Document 1, an RTP device is configured such that a lamp, which is a heat source, is housed in a vertically oriented cylindrical lamp hole, and cooling water flows adjacent to the lamp hole, so that the RTP device can be immediately cooled by the cooling water after heating by the lamp has finished. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-156522 A Summary of the Invention [Problem to be solved by the invention]

[0006] In this way, in the RTP apparatus, cooling water (cooling medium) is circulated within the apparatus to rapidly cool the apparatus after heating is completed. However, when heat treatment is performed continuously using an RTP device, the heat load generated accumulates, which can cause damage (cracks) to the cooling water circulation path, leading to the risk of cooling water leaking into the device. Furthermore, if cooling water leaks into the equipment, the moisture that leaks into the chamber turns into water vapor during heat treatment, causing scattering of the radiation of thermal energy, resulting in the problem that silicon wafers with the desired performance cannot be obtained, resulting in a decrease in yield.

[0007] The present invention has been made under the above circumstances, and has an object to provide a heat treatment apparatus that can suppress a decrease in yield and a decrease in production efficiency by accurately detecting leakage of a cooling medium within the heat treatment apparatus, and a method for manufacturing a semiconductor substrate using the heat treatment apparatus. [Means for solving the problem]

[0008] The heat treatment apparatus according to the present invention, which has been made to solve the above-mentioned problems, is a heat treatment apparatus that performs heat treatment on a plurality of semiconductor substrates in succession on a lot-by-lot basis, and includes a plurality of lamps that heat the semiconductor substrates, a power source that applies a lamp voltage to the plurality of lamps, a temperature detection unit that detects the temperature of the semiconductor substrate, and a controller that controls the lamp voltage or lamp current applied to the plurality of lamps and detects an abnormality in the heat treatment apparatus, wherein the controller controls the lamp voltage or lamp current applied to the plurality of lamps based on the temperature of the semiconductor substrate detected by the temperature detection unit, calculates a differential effect amount (n) based on the maximum lamp voltage or maximum lamp current applied to the plurality of lamps, where n is a positive integer of 2 or more indicating the lot order of the semiconductor substrates to be processed, by calculating a differential effect amount (n)=(maximum lamp voltage or maximum lamp current (n)-maximum lamp voltage or maximum lamp current (n-1)) / standard deviation of the maximum lamp voltage or maximum lamp current in a specified lot range, and determines that an abnormality has occurred when the differential effect amount (n) exceeds a first threshold value. It is preferable that the heat treatment apparatus has a warning unit that warns of an abnormality in the heat treatment apparatus by display or sound, and that the warning unit issues a warning when the controller determines that an abnormality has occurred. Moreover, it is preferable that the first threshold value is equal to or greater than 1.2 and equal to or less than 3.0.

[0009] In this way, the occurrence of a cooling water leak is detected by comparing the difference effect amount obtained by dividing the difference obtained by subtracting the maximum lamp voltage or maximum lamp current (n) from the maximum lamp voltage or maximum lamp current (n-1) by the standard deviation σ of the maximum lamp voltage (or lamp current) in a specified lot range with the first threshold value. This makes it possible to eliminate sudden increases in lamp voltage that occur accidentally due to causes other than cooling water leakage, and makes it possible to detect cooling water leakage with high accuracy. As a result, by immediately taking measures such as stopping the heat treatment apparatus and repairing it, it is possible to suppress a decrease in yield and a decrease in productivity.

[0010] Further, a heat treatment apparatus according to the present invention, which has been made to solve the above-mentioned problems, is a heat treatment apparatus which performs heat treatment on a plurality of semiconductor substrates in succession on a lot-by-lot basis, and includes a plurality of lamps which heat the semiconductor substrates, a power source which applies a lamp voltage to the plurality of lamps, a temperature detection unit which detects the temperature of the semiconductor substrates, and a controller which controls the lamp voltage applied to the plurality of lamps and detects an abnormality in the heat treatment apparatus, wherein the controller controls the lamp voltage or lamp current applied to the plurality of lamps based on the temperature of the semiconductor substrate detected by the temperature detection unit, and calculates a differential efficiency based on a maximum lamp voltage or a maximum lamp current applied to the plurality of lamps when n is a positive integer of 2 or more which indicates the lot order of the semiconductor substrates to be treated. The differential effect amount (n) is calculated by: effect amount (n)=(maximum lamp voltage or maximum lamp current (n)-maximum lamp voltage or maximum lamp current (n-1)) / standard deviation of the maximum lamp voltage or maximum lamp current in a specified lot range; and a second-order differential effect amount (n) is calculated by: second-order differential effect amount (n)=differential effect amount (n)-differential effect amount (n-1), or by: (difference in maximum lamp voltage or maximum lamp current (n)-difference in maximum lamp voltage or maximum lamp current (n-1)) / standard deviation of the difference in maximum lamp voltage or maximum lamp current (n) in a specified lot range; and it is determined that an abnormality has occurred when the differential effect amount (n) exceeds a first threshold value and the second-order differential effect amount exceeds a second threshold value and is less than a third threshold value. It is preferable that the heat treatment apparatus has a warning unit that warns of an abnormality in the heat treatment apparatus by display or sound, and that the warning unit issues a warning when the controller determines that an abnormality has occurred. It is also preferable that the first threshold value is equal to or greater than 1.2 and equal to or less than 3.0, the second threshold value is equal to or greater than -1.5 and equal to or less than -0.7, and the third threshold value is equal to or greater than 0.7 and equal to or less than 1.5.

[0011] In this way, the occurrence of a cooling water leak is detected using a differential effect amount d(n) obtained by dividing the difference obtained by subtracting the maximum lamp voltage V(n-1) in lot (n-1) from the maximum lamp voltage V(n) in lot (n) by the standard deviation σ of the maximum lamp voltage in a specified lot range, and a second-order differential effect amount D(n), which is the difference between the differential effect amount d(n) and the differential effect amount d(n-1). In other words, by using not only the differential effect amount d(n) but also the second differential effect amount D(n), it is possible to distinguish between accidental fluctuations in the maximum lamp voltage V(n) and systematic fluctuations due to leaks, and it is possible to detect cooling water leaks with greater accuracy. As a result, by immediately taking measures such as stopping the heat treatment apparatus and repairing it, it is possible to suppress a decrease in yield and a decrease in productivity.

[0012] In addition, a semiconductor substrate manufacturing method according to the present invention, which has been made to solve the above problem, is a semiconductor substrate manufacturing method using the heat treatment apparatus that performs continuous heat treatment on a plurality of semiconductor substrates in lot units, and is characterized in that the method includes the steps of controlling the lamp voltage or lamp current applied to the plurality of lamps by the controller and heating the semiconductor substrate by the plurality of lamps, detecting the temperature of the semiconductor substrate by the temperature detection unit and controlling the lamp voltage or lamp current applied to the plurality of lamps based on the temperature of the semiconductor substrate, and calculating a differential effect amount (n) based on the maximum lamp voltage or maximum lamp current applied to the plurality of lamps, where n is a positive integer of 2 or more indicating the lot order, by using a differential effect amount (n) = (maximum lamp voltage or maximum lamp current (n) - maximum lamp voltage or maximum lamp current (n-1)) / standard deviation of the maximum lamp voltage or maximum lamp current in a specified lot range, and determining that an abnormality has occurred when the differential effect amount (n) exceeds a first threshold value. When the controller determines that an abnormality has occurred, it is preferable that a warning unit warns the user of the abnormality in the heat treatment device by displaying or sounding the abnormality. Moreover, it is preferable that the first threshold value is equal to or greater than 1.2 and equal to or less than 3.0.

[0013] According to this method, the occurrence of a cooling water leak is detected by comparing the difference effect obtained by subtracting the maximum lamp voltage or current (n-1) from the maximum lamp voltage or current (n) and dividing the difference by the standard deviation σ of the maximum lamp voltage (or maximum lamp current) in a specified lot range with a first threshold value. This makes it possible to eliminate any sudden increase in maximum lamp voltage that occurs accidentally due to causes other than cooling water leakage, and makes it possible to detect cooling water leakage with high accuracy. As a result, by immediately taking measures such as stopping the heat treatment apparatus and repairing it, it is possible to suppress a decrease in yield and a decrease in productivity.

[0014] Further, a method for manufacturing a semiconductor substrate according to the present invention, which has been made to solve the above-mentioned problems, is a method for manufacturing a semiconductor substrate using the heat treatment apparatus which performs continuous operation of heat treatment on a lot basis consisting of a plurality of semiconductor substrates, comprising the steps of: controlling lamp voltages applied to the plurality of lamps by the controller, and heating the semiconductor substrate by the plurality of lamps; detecting a temperature of the semiconductor substrate by the temperature detection unit, and controlling the lamp voltages applied to the plurality of lamps based on the temperature of the semiconductor substrate; and calculating a differential effect amount (n)=(maximum lamp voltage or maximum lamp current) based on a maximum lamp voltage or maximum lamp current applied to the plurality of lamps, where n is a positive integer of 2 or more indicating a lot order. calculates a differential effect amount (n) by (maximum lamp current (n) - maximum lamp voltage or maximum lamp current (n-1)) / standard deviation of the maximum lamp voltage or maximum lamp current in a specified lot range, and further calculates a second-order differential effect amount (n) by (second-order differential effect amount (n) = differential effect amount (n) - differential effect amount (n-1), or by (difference between maximum lamp voltage or maximum lamp current (n) - difference between maximum lamp voltage or maximum lamp current (n-1)) / standard deviation of the difference between the maximum lamp voltage or maximum lamp current in a specified lot range, and determines that an abnormality has occurred when the differential effect amount (n) exceeds a first threshold value and the second-order differential effect amount exceeds a second threshold value and is less than a third threshold value. When the controller determines that an abnormality has occurred, it is preferable that a warning unit warns the user of the abnormality in the heat treatment device by displaying or sounding the abnormality. It is also preferable that the first threshold value is equal to or greater than 1.2 and equal to or less than 3.0, the second threshold value is equal to or greater than -1.5 and equal to or less than -0.7, and the third threshold value is equal to or greater than 0.7 and equal to or less than 1.5.

[0015] According to this method, the occurrence of a cooling water leak is detected using a differential effect amount d(n) obtained by dividing the difference obtained by subtracting the maximum lamp voltage V(n) in lot (n-1) from the maximum lamp voltage V(n-1) in lot (n) by the standard deviation σ of the lamp voltages, and a second-order differential effect amount D(n), which is the difference between the differential effect amount d(n) and the differential effect amount d(n-1). In other words, by using not only the differential effect amount d(n) but also the second differential effect amount D(n), it is possible to distinguish between accidental fluctuations in the maximum lamp voltage V(n) and systematic fluctuations due to leaks, and it is possible to detect cooling water leaks with greater accuracy. As a result, by immediately taking measures such as stopping the heat treatment apparatus and repairing it, it is possible to suppress a decrease in yield and a decrease in productivity. Effect of the Invention

[0016] According to the present invention, a decrease in yield and a decrease in production efficiency can be suppressed by accurately detecting a cooling medium leak in a heat treatment apparatus. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view that illustrates a schematic configuration of an RTP apparatus (thermal treatment apparatus) according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a halogen lamp provided in the RTP device of FIG. [Diagram 3] FIG. 3 is a flow diagram showing a first embodiment of a method for manufacturing a semiconductor substrate according to the present invention. [Figure 4]FIG. 4 is a flow diagram showing a second embodiment of a method for manufacturing a semiconductor substrate according to the present invention. [Diagram 5] FIG. 5 is a graph showing the results of Experiment 1 of the embodiment. [Figure 6] FIG. 6 is another graph showing the results of Experiment 1 of the embodiment. [Figure 7] FIG. 7 is another graph showing the results of Experiment 1 of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The embodiment of the present invention will be described by taking as an example an RTP apparatus (thermal processing apparatus) that uses a lamp (eg, a high voltage tungsten halogen lamp) disposed within a lamp sleeve as a heat source. 1 is a cross-sectional view showing a schematic diagram of an RTP apparatus (heat treatment apparatus) 100 according to an embodiment of the present invention. The RTP apparatus 100 includes a chamber 20 having a chamber sidewall 2, a chamber bottom 4 coupled to the chamber sidewall 2, and a quartz window 6 disposed over the chamber sidewall 2.

[0019] The chamber 20 is made up of a chamber sidewall 2, a chamber bottom 4, and a quartz window 6, which form a reaction space 25 for processing a silicon wafer W (semiconductor substrate) therein. The RTP apparatus 100 is provided with a slit valve door (not shown) penetrating the chamber sidewall 2 in order to transfer the silicon wafer W into the reaction space 25.

[0020] The RTP apparatus 100 also includes a gas inlet 20a formed in the chamber sidewall 2, which is connected to a gas source 18 configured to provide one or more process gases to the reaction space 25. The RTP apparatus 100 also includes a gas outlet 20b formed in the chamber sidewall 2, which is connected to a vacuum pump 21 for evacuating the reaction space 25. The RTP apparatus 100 also includes a substrate support 40 that supports the silicon wafer W in the reaction space 25 in the chamber 20. In addition, the RTP apparatus 100 also includes a rotation means (not shown) that rotates the silicon wafer W around its central axis at a predetermined speed.

[0021] The substrate support 40 includes an annular susceptor 40a that supports the outer periphery of the silicon wafer W, and a stage 40b that supports the susceptor 40a. Moreover, the temperature of the silicon wafer W in this RTP apparatus 100 is controlled using a plurality of radiation thermometers 50 (temperature detection units) embedded in the stage 40b of the substrate support unit 40. The radiation thermometers 50 are connected to a controller 70, which is a computer, and the controller 70 controls the temperature of the silicon wafer W based on temperature information of the silicon wafer W acquired by the radiation thermometers 50.

[0022] That is, the controller 70 measures the temperature at multiple points (e.g., nine points) within the substrate surface in the radial direction of the lower part of the silicon wafer W using the radiation thermometer 50, and controls the multiple halogen lamps 30 (individual ON-OFF control of each lamp, increase / decrease control of the power supply, control of the emission intensity of the emitted light, etc.) based on the measured temperatures.

[0023] The plurality of halogen lamps 30 are disposed above the quartz window 6 and configured to transmit thermal energy through the quartz window 6 toward the silicon wafer W. The plurality of halogen lamps 30 are arranged, for example, in a hexagonal pattern in a plan view. Each of the plurality of halogen lamps 30 is connected to the heating assembly base 17 for electrical connection to a power source 60.

[0024] Each halogen lamp 30 is configured, for example, as shown in Fig. 2. The halogen lamp 30 shown in Fig. 2 has a tungsten filament coil 32 disposed in lamp glass 31 made of quartz glass, and gas including halogen gas is sealed in the lamp glass 31.

[0025] The lamp glass 31 is surrounded by a cylindrical lamp sleeve 33, and the inner wall 33a of the lamp sleeve 33 is inclined so that the thermal energy emitted from the lamp glass 31 is directed downward toward the silicon wafer W. The inner wall 33a of the lamp sleeve 33 is preferably Au-plated. This is because Au plating has high heat resistance, high reflectance, and also high acid resistance. A lamp voltage is applied to each halogen lamp 30 from a power source 60. The value of this lamp voltage is controlled by a controller 70.

[0026] 1, cooling water passages 55 are provided around the multiple halogen lamps 30 for circulating cooling water (cooling medium) for rapidly cooling the heat of the halogen lamps 30 after heat treatment. Furthermore, a cooling water passage 56 is provided in the stage 40b of the substrate support part 40, so that the stage 40b and the silicon wafer W thereon can be rapidly cooled after heat treatment.

[0027] The RTP device 100 according to this embodiment also includes a warning unit 80 for warning of the occurrence of leakage of cooling water from the cooling water passages 55, 56, for example, by a screen display or a warning sound (audio). Specifically, when performing continuous operation of silicon wafers W in units of lots (e.g., 25 wafers), if the effect amount (called the differential effect amount) calculated by the following formula 1 exceeds a first threshold value (e.g., 1.2), the controller 70 issues a warning via the warning unit 80. The heat treatment apparatus according to the present invention is not limited to issuing a warning as in this embodiment, and may be configured to automatically stop the heat treatment apparatus without issuing a warning.

[0028] This first threshold is determined, for example, by setting a voltage threshold value for each of a plurality of heat treatment recipes at which a sudden increase in maximum lamp voltage results in NG, and identifying a region of differential effect amount in which there are many lots that result in NG for each recipe (i.e., lots with a maximum lamp voltage that exceeds the voltage threshold value). 7, for example, when the differential effect amount exceeds 1.2, there are many NGs, and when it is less than 1.2, there are no NGs, so the first threshold can be set to 1.2. Alternatively, when the differential effect amount is in the range of 1.2 to 3.0, there are lots that are not NG, so the first threshold can be set appropriately within the range of 1.2 to 3.0. However, in the present invention, values ​​exceeding 3.0 are not necessarily excluded as the first threshold.

[0029] Differential effect d(n) = (maximum lamp voltage V(n) - maximum lamp voltage V(n-1)) / standard deviation σ (Equation 1) The differential effect amount d(n) calculated by this formula 1 is the difference between the maximum lamp voltage (or maximum lamp current) in the nth lot (n: n is a positive integer greater than or equal to 2) and the maximum lamp voltage (or maximum lamp current) in the previous lot (n-1), divided by the standard deviation σ of the maximum lamp voltage (or maximum lamp current) in a specified lot range (for example, the standard deviation of the most recent 25 silicon wafers W, i.e., the most recent 5 lots, when one lot is 5 wafers). It is preferable to set one lot in the range of 1 to 50 sheets. If the number of sheets in one lot exceeds 50 sheets, early detection of cooling water leaks may be delayed, but a number exceeding 50 sheets is not necessarily excluded. Moreover, the predetermined lot range is preferably set to 2 to 30 lots of the immediately preceding lot of the same recipe, but the range can be set without being limited to this range. Furthermore, the maximum lamp voltage (or maximum lamp current) in a predetermined lot range may be the maximum value or the average value of the maximum lamp voltage in one lot range.

[0030] More preferably, the second-order differential effect size D(n) is calculated using the following formula 2, and if the differential effect size d(n) exceeds a first threshold (e.g., 1.2) and is within a range of exceeding the second threshold and less than a third threshold (e.g., exceeding -0.7 and less than 0.7), it is determined to be abnormal, and a warning is issued by the warning unit 80.

[0031] The second and third thresholds, like the first threshold, are determined by setting a voltage threshold for each of a plurality of heat treatment recipes at which a sudden increase in maximum lamp voltage results in an NG result, and identifying a region of the second-order differential effect amount in which there are many lots that result in an NG result for each recipe (i.e., lots with a maximum lamp voltage that exceeds the voltage threshold). Specifically, in the example shown in FIG. 7, there are many NGs in the region where the second-order difference effect amount is greater than -0.7 and less than 0.7, whereas there are few NGs in other regions. Therefore, the second threshold can be set to -0.7 and the third threshold can be set to 0.7. Alternatively, the second threshold may be set in the range of -1.5 to -0.7, and the third threshold may be set in the range of 0.7 to 1.5. This is because there are lots that are not NG even when the second-order differential effect size is in the range of -1.5 to -0.7, and there are lots that are not NG even when the second-order differential effect size is in the range of 0.7 to 1.5.

[0032] Second-order differential effect size D(n) = differential effect size d(n) - differential effect size d(n-1) (Equation 2) The second differential effect size D(n) calculated by Equation 2 is the difference between the maximum effect size in the nth lot (n) and the differential effect size in the previous lot (n-1).

[0033] Next, a first embodiment of a method for manufacturing a semiconductor substrate using a heat treatment apparatus according to the present invention will be described with reference to the flow chart of FIG. 1, heat treatment is continuously performed on a plurality of lots (e.g., 25 wafers per lot). The heat treatment on the silicon wafers W of the nth (n is a positive integer of 2 or more) lot is performed as follows (step S1 in FIG. 3). That is, in the heat treatment of each silicon wafer W, the silicon wafer W is first placed in the chamber 20 maintained at a desired initial temperature. After the silicon wafer is placed, oxygen (O 2A gas mixture of Ar gas and an inert gas is introduced at a predetermined flow rate. Examples of the inert gas include Ar gas and nitrogen gas.

[0034] For example, when a silicon wafer W is heat-treated at a target temperature of 1300° C., the controller 70 determines a lamp voltage (initial setting voltage) to be applied to the corresponding halogen lamps 30, and applies the lamp voltage to each halogen lamp 30 via the power supply 60. Each halogen lamp 30 radiates thermal energy according to the supplied lamp voltage toward the silicon wafer W. This starts heating the silicon wafer W.

[0035] While the silicon wafer W is being heated, the radiation thermometer 50 measures the temperature at multiple points (e.g., nine points) in the radial direction of the lower part of the silicon wafer W. The controller 70 controls the voltage applied to the halogen lamp 30 based on the measured temperature of the silicon wafer W.

[0036] In the event that a cooling water leak occurs in the RTP apparatus 100, for example, water vapor will be generated to block the radiation of thermal energy, causing the temperature of the silicon wafer W to drop, and the controller 70 will control the voltage applied to the halogen lamps 30 to increase.

[0037] Then, the substrate temperature reaches a target temperature (for example, 1300° C.) by applying a voltage to the halogen lamps 30, and when a predetermined time has elapsed at that temperature, the heat treatment of the silicon wafer W is completed.

[0038] Next, after all heat treatments for the nth (n is a positive integer of 2 or more) lot (e.g., 25) of silicon wafers W are completed, the differential effect amount d(n) is calculated based on the following formula 1 (step S2 in FIG. 3). Differential effect amount d(n) = (maximum lamp voltage V(n) - maximum lamp voltage V(n-1)) / standard deviation σ of maximum lamp voltage V in a given lot range (Equation 1)

[0039] When the differential effect amount d(n) is obtained, the controller 70 determines whether or not the differential effect amount d(n) exceeds a first threshold value (for example, 1.2) (step S3 in FIG. 3). If the differential effect amount d(n) does not exceed the first threshold value, the process returns to step S1 to perform heat treatment on the next lot (n+1). On the other hand, if the differential effect amount d(n) exceeds the first threshold value, the controller 70 determines that an abnormality (a coolant leak) has occurred, and the warning unit 80 issues a warning on a screen or by sound that a coolant leak has occurred (step S4 in FIG. 3). When the warning unit 80 issues a warning, the worker stops the operation of the RTP device 100, checks and repairs the location of the abnormality, and then resumes the operation of the RTP device 100. Furthermore, in step S3, if the controller 70 determines that an abnormality has occurred in the RTP device 100, the controller 70 may perform control so as to automatically stop the operation of the RTP device 100.

[0040] As described above, according to the first embodiment of the semiconductor substrate manufacturing method of the present invention, the occurrence of a cooling water leak is detected by comparing the difference effect amount obtained by subtracting the maximum lamp voltage V(n-1) from the maximum lamp voltage V(n) and dividing the difference by the standard deviation σ of the lamp voltage (or current) with the first threshold value. This makes it possible to eliminate sudden increases in lamp voltage that occur accidentally due to causes other than cooling water leakage, and to accurately detect cooling water leakage. As a result, by taking corrective action such as repairs immediately, it is possible to suppress a decrease in yield and a decrease in production efficiency.

[0041] Next, a second embodiment of the method for manufacturing a semiconductor substrate using a heat treatment apparatus according to the present invention will be described with reference to the flow chart of FIG. 1, heat treatment is continuously performed on a plurality of lots (e.g., 25 wafers per lot). The heat treatment on the silicon wafers W of the nth (n is a positive integer of 2 or more) lot is performed as follows (step St1 in FIG. 4). That is, in the heat treatment of each silicon wafer W, the silicon wafer W is first placed in the chamber 20 maintained at a desired initial temperature. After the silicon wafer is placed, oxygen (O 2 A gas mixture of Ar gas and an inert gas is introduced at a predetermined flow rate. Examples of the inert gas include Ar gas and nitrogen gas.

[0042] For example, when a silicon wafer W is heat-treated at a target temperature of 1300° C., the controller 70 determines a lamp voltage (initial setting voltage) to be applied to the corresponding halogen lamps 30, and applies the lamp voltage to each halogen lamp 30 via the power supply 60. Each halogen lamp 30 radiates thermal energy according to the supplied lamp voltage toward the silicon wafer W. This starts heating the silicon wafer W.

[0043] While the silicon wafer W is being heated, the radiation thermometer 50 measures the temperature at multiple points (e.g., nine points) in the radial direction of the lower part of the silicon wafer W. The controller 70 controls the voltage applied to the halogen lamp 30 based on the measured temperature of the silicon wafer W.

[0044] In the event that a cooling water leak occurs in the RTP apparatus 100, for example, water vapor will be generated to block the radiation of thermal energy, causing the temperature of the silicon wafer W to drop, and the controller 70 will control the voltage applied to the halogen lamps 30 to increase.

[0045] Then, the substrate temperature reaches a target temperature (for example, 1300° C.) by applying a voltage to the halogen lamps 30, and when a predetermined time has elapsed at that temperature, the heat treatment of the silicon wafer W is completed.

[0046] Next, after the heat treatment of the nth (n is a positive integer greater than or equal to 2) lot (e.g., 25) of silicon wafers W is completed, the differential effect amount d(n) and the second-order differential effect amount D(n) are calculated based on the following equations 1 and 2 (step St2 in FIG. 4).

[0047] Differential effect amount d(n) = (maximum lamp voltage V(n) - maximum lamp voltage V(n-1)) / standard deviation σ of maximum lamp voltage V in a given lot range (Equation 1)

[0048] Second-order differential effect size D(n) = differential effect size d(n) - differential effect size d(n-1) (Equation 2) The second-order differential effect size D(n) may be calculated using the following formula 3. Second-order difference effect D(n) = (maximum lamp voltage difference v(n) - maximum lamp voltage difference v(n-1)) / standard deviation σ of the maximum lamp voltage difference V(n) in a given lot range (Equation 3) In Equation 3, the difference v(n) in the maximum lamp voltage is the difference between the maximum lamp voltage V in lot (n) and the previously processed lot (n-1).

[0049] Once the differential effect size d(n) and the second differential effect size D(n) are obtained, the controller 70 determines whether the differential effect size d(n) exceeds a first threshold value (e.g., 1.2) and whether the second differential effect size D(n) exceeds a second threshold value and is within a range less than a third threshold value (e.g., greater than -0.7 and less than 0.7) (step St3 in FIG. 4). Here, if the differential effect amount d(n) does not exceed the first threshold, or if the differential effect amount d(n) exceeds the first threshold but the second differential effect amount D(n) is not within the range of exceeding the second threshold and less than the third threshold (for example, exceeding -0.7 and less than 0.7), the process returns to step St1 and the heat treatment of the next lot (n+1) is performed.

[0050] On the other hand, if the differential effect amount d(n) exceeds the first threshold value (e.g., 1.2) and the second differential effect amount D(n) exceeds the second threshold value and is within a range less than the third threshold value (e.g., greater than -0.7 and less than 0.7), the controller 70 determines that an abnormality (a coolant leak) has occurred, and issues a warning by the warning unit 80, such as by displaying a warning on a screen or by sound, that a coolant leak has occurred (step St4 in FIG. 4). When the warning unit 80 issues a warning, the worker stops the operation of the RTP device 100, checks and repairs the location of the abnormality, and then resumes the operation of the RTP device 100. Furthermore, in step St3, if the controller 70 determines that an abnormality has occurred in the RTP device 100, the controller 70 may perform control so as to automatically stop the operation of the RTP device 100.

[0051] As described above, according to the second embodiment of the detection method of the present invention, the occurrence of a cooling water leak is detected using the differential effect amount d(n) obtained by dividing the difference obtained by subtracting the maximum lamp voltage V(n) in lot (n-1) from the maximum lamp voltage V(n-1) in lot (n) by the standard deviation σ of the lamp voltages, and the second-order differential effect amount D(n), which is the difference between the differential effect amount d(n) and the differential effect amount d(n-1). In other words, by using not only the differential effect amount d(n) but also the second differential effect amount D(n), it is possible to distinguish between accidental fluctuations in the maximum lamp voltage V(n) and systematic fluctuations due to leaks, and it is possible to detect cooling water leaks with greater accuracy. As a result, by taking corrective action such as repairs immediately, it is possible to suppress a decrease in yield and a decrease in production efficiency.

[0052] In the first and second embodiments, the differential effect amount and the second differential effect amount are calculated using the maximum lamp voltage applied to the halogen lamp 30. However, the present invention is not limited to this example, and the differential effect amount and the second differential effect amount may be calculated using the maximum lamp current applied to the halogen lamp 30. In that case, the maximum lamp voltage in the above (Equation 1), (Equation 2), and (Equation 3) should be replaced with the maximum lamp current.

[0053] In the first and second embodiments, a silicon wafer is used as an example of the semiconductor substrate. However, the semiconductor substrate is not limited to this, and a SiC wafer, a GaN wafer, a device-processed wafer, or the like can be used as the semiconductor substrate. EXAMPLES

[0054] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples.

[0055] (Experiment 1) In experiment 1, the RTP device was operated continuously in batches and the change in maximum lamp voltage was measured to verify the thresholds (first, second, and third thresholds) of the differential effect size and the second differential effect size. First, two different recipes were used to continuously operate the heat treatment process on semiconductor silicon wafers in an RTP device, with recipe A at a heating temperature of 1300°C for 40 seconds, and recipe B at a heating temperature of 1350°C for 35 seconds. For both recipes A and B, 25 silicon wafers were used in one lot, and 39 lots were continuously heat treated.

[0056] The graph in FIG. 5 shows the relationship between the maximum lamp voltage V (vertical axis) and the lot order (horizontal axis) for each lot for recipes A and B. For each plot data of recipes A and B, a cooling water leak occurred at a lamp voltage exceeding threshold A and threshold B, respectively.

[0057] Next, from the data shown in the graph in Figure 5, the differential effect size was calculated based on the following formula 1, and the second-order differential effect size was calculated based on the following formula 2, and a graph was created showing the correlation between the differential effect size and the second-order differential effect size. Differential effect amount d(n) = (Maximum lamp voltage during RTP processing V(n) - Maximum lamp voltage V(n-1)) / Standard deviation of maximum lamp voltage V in a given lot range σ (Equation 1) Second-order differential effect size D(n) = differential effect size d(n) - differential effect size d(n-1) (Equation 2)

[0058] Figure 6(a) shows a graph of the correlation between the differential effect size and the second-order differential effect size for recipe A, and Figure 6(b) shows a graph of the correlation between the differential effect size and the second-order differential effect size for recipe B. In Figures 6(a) and (b), the vertical axis is the second-order differential effect size, and the horizontal axis is the differential effect size.

[0059] Next, as shown in FIG. 7, FIGS. 6(a) and (b) were overlaid on the same graph to identify the area in which there were many lots with maximum lamp voltages higher than thresholds A and B (i.e., NG) shown in FIG. 5. As a result, the differential effect amount exceeded the threshold value of 1.2 in many cases, resulting in the maximum lamp voltage at which cooling water leakage occurred. Therefore, it was confirmed that it is preferable to issue a warning in the RTP device when the differential effect amount exceeds the threshold value of 1.2 under the conditions of Experiment 1. Alternatively, since there were lots that were not NG when the differential effect amount was in the range of 1.2 to 3.0, it was confirmed that it would be sufficient to set the first threshold appropriately in the range of 1.2 to 3.0.

[0060] In addition, when the differential effect amount exceeds the threshold value of 1.2 and the second-order differential effect amount is in the range of more than -0.7 and less than 0.7, the maximum lamp voltage that causes leakage of cooling water is reached. Therefore, it was confirmed that it is more preferable to issue a warning in the RTP device when the differential effect size exceeds 1.2 (first threshold) and the second differential effect size is within the range of greater than -0.7 (second threshold) and less than 0.7 (third threshold), as in the second embodiment. Alternatively, there were lots that were not NG even when the second-order difference effect size was in the range of -1.5 to -0.7, and there were lots that were not NG even when the second-order difference effect size was in the range of 0.7 to 1.5, so it was confirmed that the second threshold could be set appropriately in the range of -1.5 to -0.7, and the third threshold could be set appropriately in the range of 0.7 to 1.5. [Explanation of symbols]

[0061] 20 Chambers 20a Gas inlet 20b Gas outlet 25 Reaction Space 30 Halogen lamp (lamp) 40 Substrate support 40a Susceptor 50 Radiation thermometer (temperature detection part) 60 power supply 70 Controller 80 Warning section W Silicon wafer (semiconductor substrate)

Claims

1. A heat treatment apparatus for continuously performing heat treatment on a plurality of semiconductor substrates in a lot unit, a plurality of lamps for heating the semiconductor substrate; a power source that applies a lamp voltage to the plurality of lamps; a temperature detection unit for detecting a temperature of the semiconductor substrate; a controller that controls a lamp voltage or a lamp current applied to the plurality of lamps and detects an abnormality in the heat treatment device; Equipped with The controller: controlling a lamp voltage or a lamp current applied to the plurality of lamps based on the temperature of the semiconductor substrate detected by the temperature detection unit; When n is a positive integer of 2 or more indicating the lot order of the semiconductor substrates to be processed, Based on a maximum lamp voltage or a maximum lamp current applied to the plurality of lamps, Differential effect size (n) = (maximum lamp voltage or maximum lamp current (n) - maximum lamp voltage or maximum lamp current (n-1)) / standard deviation of maximum lamp voltage or maximum lamp current in a given lot range The differential effect size (n) was calculated by The heat treatment apparatus is characterized in that, when the differential effect amount (n) exceeds a first threshold value, it is determined that an abnormality has occurred.

2. a warning unit that warns of an abnormality in the heat treatment device by display or sound; 2. The heat treatment apparatus according to claim 1, wherein when the controller determines that an abnormality has occurred, the warning unit issues a warning.

3. 2. The heat treatment apparatus according to claim 1, wherein the first threshold value is equal to or greater than 1.2 and equal to or less than 3.

0.

4. A heat treatment apparatus for continuously performing heat treatment on a plurality of semiconductor substrates in a lot unit, a plurality of lamps for heating the semiconductor substrate; a power source that applies a lamp voltage to the plurality of lamps; a temperature detection unit for detecting a temperature of the semiconductor substrate; a controller that controls lamp voltages applied to the plurality of lamps and detects an abnormality in the heat treatment device; Equipped with The controller: controlling a lamp voltage or a lamp current applied to the plurality of lamps based on the temperature of the semiconductor substrate detected by the temperature detection unit; When n is a positive integer of 2 or more indicating the lot order of the semiconductor substrates to be processed, Based on a maximum lamp voltage or a maximum lamp current applied to the plurality of lamps, Differential effect size (n) = (maximum lamp voltage or maximum lamp current (n) - maximum lamp voltage or maximum lamp current (n-1)) / standard deviation of maximum lamp voltage or maximum lamp current in a given lot range The differential effect size (n) was calculated by: Second-order differential effect size (n) = differential effect size (n) - differential effect size (n-1), or (maximum lamp voltage or maximum lamp current difference (n) - maximum lamp voltage or maximum lamp current difference (n-1)) / standard deviation of maximum lamp voltage or maximum lamp current difference (n) in a given lot range The second-order difference effect size (n) was calculated by The heat treatment apparatus is characterized in that it determines that an abnormality has occurred when the differential effect amount (n) exceeds a first threshold value and the second differential effect amount exceeds a second threshold value and is less than a third threshold value.

5. a warning unit that warns of an abnormality in the heat treatment device by display or sound; 5. The heat treatment apparatus according to claim 4, wherein when the controller determines that an abnormality has occurred, the warning unit issues a warning.

6. 5. The heat treatment apparatus according to claim 4, wherein the first threshold value is 1.2 or more and 3.0 or less, the second threshold value is -1.5 or more and -0.7 or less, and the third threshold value is 0.7 or more and 1.5 or less.

7. A method for manufacturing semiconductor substrates using the heat treatment apparatus according to claim 1, in which a plurality of semiconductor substrates are continuously heat-treated in a batch unit, The controller a step of controlling a lamp voltage or a lamp current applied to the plurality of lamps and heating a semiconductor substrate by the plurality of lamps; detecting a temperature of the semiconductor substrate by the temperature detection unit, and controlling a lamp voltage or a lamp current applied to the plurality of lamps based on the temperature of the semiconductor substrate; When n is a positive integer of 2 or more indicating the lot order, Based on a maximum lamp voltage or a maximum lamp current applied to the plurality of lamps, Differential effect size (n) = (maximum lamp voltage or maximum lamp current (n) - maximum lamp voltage or maximum lamp current (n-1)) / standard deviation of maximum lamp voltage or maximum lamp current in a given lot range The differential effect size (n) was calculated by A method for manufacturing a semiconductor substrate, comprising: determining that an abnormality has occurred when the differential effect amount (n) exceeds a first threshold value.

8. 8. The method for manufacturing a semiconductor substrate according to claim 7, wherein when the controller judges that an abnormality has occurred, a warning unit that warns of the abnormality in the heat treatment apparatus by display or sound is used.

9. 8. The method for manufacturing a semiconductor substrate according to claim 7, wherein the first threshold value is equal to or greater than 1.2 and equal to or less than 3.

0.

10. A method for manufacturing semiconductor substrates using the heat treatment apparatus according to claim 4, which performs continuous heat treatment on a lot-by-lot basis consisting of a plurality of semiconductor substrates, The controller controlling lamp voltages applied to the plurality of lamps and heating the semiconductor substrate with the plurality of lamps; detecting a temperature of the semiconductor substrate by the temperature detection unit, and controlling lamp voltages applied to the plurality of lamps based on the temperature of the semiconductor substrate; When n is a positive integer of 2 or more indicating the lot order, Based on a maximum lamp voltage or a maximum lamp current applied to the plurality of lamps, Differential effect size (n) = (maximum lamp voltage or maximum lamp current (n) - maximum lamp voltage or maximum lamp current (n-1)) / standard deviation of maximum lamp voltage or maximum lamp current in a given lot range The differential effect size (n) was calculated by: Second-order differential effect size (n) = differential effect size (n) - differential effect size (n-1), or (maximum lamp voltage or maximum lamp current difference (n) - maximum lamp voltage or maximum lamp current difference (n-1)) / standard deviation of maximum lamp voltage or maximum lamp current difference (n) in a given lot range The second-order difference effect size (n) was calculated by a second differential effect amount exceeding a second threshold and less than a third threshold, the second differential effect amount being in a range from a second threshold to a third threshold;

11. 11. The method for manufacturing a semiconductor substrate according to claim 10, wherein when the controller determines that an abnormality has occurred, a warning unit that warns of the abnormality in the heat treatment apparatus by display or sound is used.

12. 11. The method for manufacturing a semiconductor substrate according to claim 10, wherein the first threshold is 1.2 or more and 3.0 or less, the second threshold is -1.5 or more and -0.7 or less, and the third threshold is 0.7 or more and 1.5 or less.

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