Temperature control method for semiconductor process

Abstract

This invention provides a temperature control method for semiconductor manufacturing processes, comprising the steps of: setting a first measurement point of a first point distribution in a first process equipment for measuring the temperature in the first process equipment; setting a second measurement point of a second point distribution in a second detection equipment for measuring target parameters; wherein the first point distribution comprises a concentric circular dot matrix with unequal radial spacing; and the second point distribution has a concentric circular dot matrix corresponding to the first point distribution. The method of this invention can monitor the process uniformity of the entire semiconductor workpiece and accurately compensate for process temperature.

Description

A Temperature Control Method for Semiconductor Processes The present invention relates to the field of semiconductor manufacturing, and particularly to a temperature control method for semiconductor processes. Semiconductor processes usually adopt rapid thermal annealing processes. Rapid thermal annealing equipment generally includes atmospheric annealing equipment and low-pressure annealing equipment. In semiconductor manufacturing, according to different applications, the temperature range of the thermal annealing process is usually between 200°C and 1250°C, belonging to high-temperature process equipment. Temperature is an important parameter in rapid thermal annealing equipment. Especially in advanced manufacturing processes, the temperature deviation is usually required to be less than 1°C. The present invention provides a temperature control method for semiconductor processes, which is used to monitor the process uniformity of the entire semiconductor workpiece and accurately compensate the process temperature. According to an aspect of the present invention, there is provided a temperature control method for semiconductor processes, including the steps of: setting first measurement points distributed at a first site in a first process equipment for measuring the temperature in the first process equipment; setting second measurement points distributed at a second site in a second detection equipment for measuring target parameters; wherein, the first site distribution includes a concentric circular dot matrix with unequal radial spacings; the second site distribution has a concentric circular dot matrix corresponding to the first site distribution. It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. The following describes exemplary embodiments of the present disclosure with reference to the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding, which should be considered merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope of the present disclosure. Similarly, for clarity and brevity, the description of known functions and structures is omitted below. In practical applications, as the number of wafers passing through the reaction chamber of the rapid thermal annealing equipment increases, the temperature sensors (such as pyrometers) of the equipment will shift or be contaminated, which will affect the accuracy of temperature measurement. On the other hand, the aging of the heating lamps in the rapid thermal annealing equipment will also affect the actual temperature in the reaction chamber. Therefore, in order to produce qualified wafers from the equipment, it is necessary to perform temperature compensation on the rapid thermal annealing equipment within the allowable temperature range, so as to keep the process temperature in the reaction chamber within a stable range (for example, the temperature deviation is less than 1°C). In a heat treatment process (i.e., a thermal annealing process), during the annealing process, the temperature inside the reaction chamber is usually detected by a sensor (such as a pyrometer) according to the heating zones in the heat treatment equipment. After the heat treatment process is completed, a semiconductor workpiece (such as a wafer) is transported into a detection station to detect the target parameters of the heat-treated semiconductor workpiece. According to the test results of the target parameters, it is determined whether parameter compensation needs to be performed on the heat treatment process machine. Regarding the detection of semiconductor workpieces in two different machines, since the radii of the concentric circles for measuring the sheet resistivity and the oxide film thickness on the wafer are inconsistent with the radius of the lamp tube control zone, the difference in the distribution of the measurement points of the two machines will cause inaccuracies in the temperature compensation calculation, and the temperature compensation value is prone to deviation. In practical applications, multiple repeated calculations are required to reduce the error of temperature compensation, which affects production efficiency. As shown in FIG. 1, in a heat treatment equipment, multiple heating elements are usually used for heating. For example, a top lamp group and a bottom lamp group are used to perform full-radiation heating on a semiconductor workpiece to be processed (such as a wafer). In the prior art, each lamp group can be divided into multiple regions centered on the central axis of the wafer, such as four regions Z1, Z2, Z3, and Z4, and these regions are controlled separately. By setting sensors, such as pyrometers, the temperatures T1 and T2 inside the reaction chamber are measured. As shown in FIG. 2, the measurement points of the prior art detection equipment (measurement station) are usually set as the central point and 5 concentric circles with equal intervals (29.4 mm) (3 mm is removed from the edge). For example, for the measurement during the manufacturing process of a 12-inch wafer, currently, the 49-point measurement or 121-point measurement method is usually adopted; the 49-point measurement object is the central point and 5 concentric circles with equal intervals, and the 121-point measurement object is the central point and 5 concentric circles with equal intervals. From the above descriptions of FIGS. 1 and 2, it can be seen that the regional division of the lamp group of the heat treatment equipment does not match the radius of the concentric circles of the measurement points of the measurement station. Therefore, the compensation data obtained based on the detection results of the measurement station cannot accurately correspond to the control process parameters of the heat treatment equipment (such as the power of the lamp tube), which will lead to compensation errors or an increase in the number of compensations, reducing the process efficiency. According to one aspect of the present invention, there is provided a temperature control method for a semiconductor process, including the steps of: setting a first measurement point with a first point distribution in a first process equipment for measuring the temperature in the first process equipment; setting a second measurement point with a second point distribution in a second detection equipment for measuring target parameters; wherein, the first point distribution includes a concentric circular dot matrix with unequal radial intervals; the second point distribution has a concentric circular dot matrix corresponding to the first point distribution. According to a specific embodiment, the temperature control method may further include the steps of: In the first process equipment, the process temperature of each site of the test semiconductor workpiece in the first site distribution under standard process conditions is obtained; In the second detection equipment, the target parameters corresponding to the process temperature of the test semiconductor workpiece are detected, and the corresponding relationship between the process temperature and the target parameters is determined; In the second detection equipment, the target parameters of the test semiconductor workpiece are detected, and the measured value of the target parameters of the test semiconductor workpiece is compared with the set standard range of the target parameters; If the measured value of the target parameters of the test semiconductor workpiece exceeds the set standard range, the deviation value of the target parameters is calculated; According to the correspondence between the process temperature and the target parameters, the temperature deviation value in each heating area is calculated from the deviation value of the target parameters; The correspondence between the process temperature and the target parameters means that the change rate is determined by the change amount of the corresponding target parameters measured in the second detection equipment when the process temperature in the first process equipment changes by 1°C. According to a specific embodiment, under the process conditions of standard rapid annealing, such as a low pressure of 1 to 760 Torr, a process temperature of 200 to 1200°C, in a process gas containing oxygen, nitrogen, oxygen and nitrogen or oxygen and hydrogen, the total gas flow rate is 1 to 60 SLM (Standard Liter per Minute). When detecting that the process temperature in the annealing machine changes by 1°C, the change in the sheet resistivity of the test wafer detected in the metrology machine is 2 Ω·cm -2 then the change rate is determined to be 2 Ω·cm -2 ·°C -1 . Among them, the reference value of the sheet resistivity of the wafer can be 160 Ω·cm -2 , after the test wafer undergoes rapid annealing treatment under set conditions in the annealing machine, the sheet resistivity of the wafer after annealing detected in the metrology machine is 170 Ω·cm -2 , then the temperature value to be compensated is calculated as follows: That is, a temperature compensation of 5°C is required. According to another embodiment, the change in the thickness of the oxide film on the wafer surface can also be detected in the metrology machine, and the change in thickness per unit temperature change is determined as the thickness change rate. The deviation value of the thickness of the oxide film on the surface of the test wafer relative to the set standard thickness value is tested and calculated, and this deviation value divided by the thickness change rate can obtain the temperature compensation value. Specifically, in a rapid thermal annealing device, the wafer rotates during the process. Especially for annealing devices for wafers larger than 12 inches, in order to maintain the uniformity of the wafer annealing temperature, it is necessary to control the heating tubes in zones. Each zone can independently control the power, so as to achieve the adjustment of temperature uniformity. Specifically, referring to FIGS. 3 and 4, the temperature control method according to the present invention may include a measurement site setting step, a step of determining the correspondence between the temperature of the first process device and the target parameters measured by the second detection device, and a parameter compensation step. Specifically, the measurement site setting step 100 may include setting a first site distribution in the first process device (such as a rapid thermal annealing device), and setting a second site distribution in the second detection device (such as a detection machine for detecting sheet resistivity or oxide film thickness). Among them, the center point of the first site distribution is on the same vertical line as the center point of the heating element (such as the top heating lamp group and the bottom heating lamp group) of the first process device. Further, according to the regional division of the heating element, the concentric circle radius distances of the site distribution are correspondingly set, so that the concentric circles of the site distribution respectively correspond to the corresponding regions of the heating element, that is, the concentric circle spacing of the site distribution in the first process device is not equal. According to an embodiment, as shown in FIG. 3, the semiconductor workpiece is a 12-inch wafer, and the heat treatment process is a rapid thermal annealing process. At this time, the rapid thermal annealing device includes a plurality of heating lamp groups (such as a top heating lamp group and a bottom heating lamp group), and includes a plurality of heating zones (such as 6 heating zones). According to the above temperature control method, the first site distribution is usually set to include a center point and 6 concentric circles with unequal spacings. Further, the spacing between adjacent concentric circles can be 25 mm, 35 mm, 20 mm, 30 mm, 10 mm, and 27 mm in sequence from the center point to the edge (that is, the radii are 25 mm, 60 mm, 80 mm, 110 mm, 120 mm, and 147 mm in sequence), with 3 mm removed at the edge. Correspondingly, the second site distribution in the detection machine can also be set to be the center point and 6 concentric circles with unequal spacings, and the spacing between adjacent concentric circles can be 25 mm, 35 mm, 20 mm, 30 mm, 10 mm, and 27 mm in sequence from the center point to the edge (that is, the radii are 25 mm, 60 mm, 80 mm, 110 mm, 120 mm, and 147 mm in sequence), with 3 mm removed at the edge. That is, the second site distribution completely corresponds to the first site distribution, so the measurement data of the detection machine can more accurately reflect the uniformity of the heat treatment process. According to another embodiment, in the rapid thermal annealing process of a wafer, the first process equipment (thermal annealing equipment) may include multiple heating elements, for example, it may include a top heating lamp group and a bottom heating lamp group, and the heating lamp group can be divided into 4 regions (see Figure 1 for example). The size of each region can be adjusted according to specific process conditions. Corresponding to the regional division of the heating lamp group, the first site distribution in the first process equipment may include a center point and 3 concentric circles. Correspondingly, on the wafer, the distances between adjacent concentric circles can be 60mm, 50mm, and 37mm in sequence from the center point to the edge (i.e., the radii are 60mm, 110mm, and 147mm in sequence), with 3mm removed from the edge. In this process equipment, the machine does not directly measure the process temperature, but senses current or voltage values through sensors and calculates the temperature value. With the use or contamination of the equipment, the sensed values of the sensors are prone to drift or have errors, making the temperature sensed by this process equipment inaccurate. In the second detection equipment, a second site distribution is carried out such that the measurement sites of the second site distribution correspond one-to-one with the first site distribution, that is, it includes a center point and multiple concentric circles with different spacings. The second detection equipment can be used to physically detect the sheet resistivity or the thickness of the oxide film of the semiconductor workpiece. Specifically, the average value of the parameter data measured at the measurement sites on the same concentric circle is the parameter measurement value of this region. According to one embodiment, for the rapid thermal annealing process of a 12-inch wafer, the positions of the four regions of the annealing equipment corresponding to the wafer are 0, 60mm, 110mm, and 147mm respectively; therefore, in the measurement, the radii of the concentric circles are adjusted to 60mm, 110mm, and 147mm, and by independently analyzing the data of these concentric circles and calculating, a preset compensation value for the temperature is obtained. The measurement values of other concentric circles can be appropriately adjusted according to needs to achieve the purpose of monitoring the process. Specifically, the number of sites on the same concentric circle of the above site distribution can be set according to process requirements, for example, it can be a 49-point array or a 121-point array. For example, when the semiconductor workpiece to be processed is a 12-inch wafer, the first site distribution includes a center point and a 49-point array or a 121-point array in the form of concentric circles with radial distances from the center point being 25mm, 60mm, 80mm, 110mm, 120mm, and 147mm respectively. The determination step 110 of the corresponding relationship may include determining the change rate by the change amount of the target parameter (such as sheet resistivity or oxide film thickness) measured in the second detection equipment when the process temperature in the first process equipment changes by 1°C. According to a specific embodiment, in a first process equipment (thermal annealing equipment), the process temperature (sensed by a standard sensor) of each site of a test semiconductor workpiece (test wafer) is obtained at the first site distribution (such as a center point and 3 concentric circles) under standard process conditions. Then, in a second detection equipment (i.e., a metrology tool), the target parameter (such as sheet resistivity or oxide film thickness) of the test semiconductor workpiece (test wafer) is detected at the measurement sites of a second site distribution corresponding to the aforementioned first site distribution, and the corresponding relationship between the process temperature and the target parameter is determined. The corresponding relationship is, as described above, determined by the change amount of the corresponding target parameter (i.e., sheet resistivity or oxide film thickness) measured in the second detection equipment when the process temperature in the first process equipment changes by 1°C to determine the change rate. According to an embodiment, in a rapid thermal annealing process, the above target parameter is the sheet resistivity of the wafer or the thickness of the surface oxide film, and its change rate relative to the process temperature in the first process equipment can be 2. Referring to FIG. 4, the above temperature control method further includes a step 120 of comparing the measured value of the target parameter with the set standard range of this parameter, and a step 130 of determining whether the measured value of the target parameter exceeds the set standard range. If the measured value exceeds the set standard range, then a step 140 of calculating the deviation value of the measured value of the target parameter relative to the standard range, calculating and setting the temperature compensation value of the corresponding heating area according to the calculated deviation value and the corresponding relationship obtained above, and performing temperature compensation on each heating area in step 150. If the measured value does not exceed the set standard range, then there is no need to perform temperature compensation, and continue with step 120 of detecting and comparing the target parameter of the wafer after thermal annealing. According to an embodiment, the above temperature compensation step is performed by adjusting the power of the heating elements of each heating area. The temperature control method provided by the present invention is a method of compensating the temperature of a heat treatment process machine that has not accurately measured the temperature by using the accurate test parameters of a subsequent detection machine through a pre-determined corresponding relationship, thereby improving the accuracy of temperature compensation. Specifically, the measurement sites of the detection machine of the method of the present invention are set to include a center point and concentric circles with unequal intervals, and these concentric circles correspond one-to-one with the heating areas of the process equipment, and can accurately reflect the changes in the process conditions, so that the process can be precisely adjusted. Taking a rapid thermal annealing equipment as an example, the heating lamp tubes are divided into four heating zones. During the process, the heating power of one or several zones can be adjusted independently to achieve uniform temperature distribution. For large-scale production equipment, within one equipment maintenance cycle, due to the aging of the lamp tubes and the drift of the accurate temperature at the temperature measurement points, preset temperature compensation values need to be set for each heating zone to achieve uniform temperature. The positions of the four zones corresponding to the wafer are 0mm, 60mm, 110mm, and 147mm respectively. Therefore, during measurement, the radii of the concentric circles for adjusting the measurement points are 60mm, 110mm, and 147mm. By independently analyzing the data of these concentric circles and calculating, preset temperature compensation values are obtained for the temperature. Further, measurement values of other concentric circles can also be set, which can be appropriately adjusted according to the process requirements to monitor the entire process, improve the stability of the process, and enhance production efficiency. It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and no limitation is imposed herein. The above specific embodiments do not constitute a limitation on the protection scope of this disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the principles of this disclosure should be included within the protection scope of this disclosure. T1: Temperature T2: Temperature Z1: Zone Z2: Zone Z3: Zone Z4: Zone 100: Steps of the temperature control method 110: Steps of the temperature control method 120: Steps of the temperature control method 130: Steps of the temperature control method 140: Steps of the temperature control method 150: Steps of the temperature control method The accompanying drawings are used to better understand this solution and do not constitute a limitation on the present invention. Among them: [Fig. 1] is a schematic diagram of the zoned heating lamp tubes and temperature detection areas in a heat treatment equipment. [Fig. 2] is a distribution diagram of measurement points of target parameters in a measurement machine tool according to the prior art. [Fig. 3] is a distribution diagram of measurement points according to an embodiment of the present invention. [Fig. 4] is a flowchart of a temperature control method according to an embodiment of the present invention.

Claims

1. A temperature control method for semiconductor manufacturing processes, comprising the steps of: setting a first measurement point with a first point distribution in a first process apparatus for measuring the temperature in the first process apparatus; setting a second measurement point with a second point distribution in a second detection apparatus for measuring a target parameter; wherein, The first site distribution comprises a lattice of concentric circles with unequal radial spacing, each concentric circle corresponding to a heating region of the first process equipment. The second site distribution has a lattice of concentric circles corresponding to the first site distribution, each concentric circle corresponding to a plurality of the heating regions. In the first process equipment, the process temperature of each site of the tested semiconductor workpiece in the first site distribution is measured under standard process conditions. In the second detection equipment, the target parameter of the tested semiconductor workpiece in the second site distribution corresponding to the process temperature is detected, and the correspondence between the process temperature and the target parameter is determined. In the second detection device, the target parameters of the semiconductor workpiece being tested in the second site distribution are detected, and the measured values ​​of the target parameters of the semiconductor workpiece are compared with the set standard range of the target parameters. If the measured values ​​of the target parameters of the semiconductor workpiece being tested exceed the set standard range, the deviation value of the target parameters is calculated. Based on the correspondence between the process temperature and the target parameters, the temperature deviation value of each heating zone is calculated from the deviation value of the target parameters. Temperature compensation is performed on each heating zone based on the temperature deviation value of each heating zone.

2. The temperature control method as described in claim 1, wherein, The temperature compensation is achieved by adjusting the power of the heating elements in each heating zone.

3. The temperature control method as described in claim 1 or 2, wherein, The target parameter is the sheet resistivity of the semiconductor workpiece or the thickness of the surface oxide film.

4. The temperature control method as described in claim 1 or 2, wherein, The first process equipment is a rapid thermal annealing equipment, and the semiconductor workpiece processed is a wafer.

5. The temperature control method as described in claim 4, wherein, The rapid thermal annealing equipment includes a plurality of heating lamp groups and a plurality of heating zones.

6. The temperature control method as described in claim 1, wherein, The correspondence between the process temperature and the target parameter is determined by the change rate of the target parameter measured in the second detection device when the process temperature in the first process equipment changes by 1°C.

7. The temperature control method as described in claim 6, wherein the target parameter is the sheet resistivity of the wafer or the thickness of the surface oxide film, and the rate of change of the process temperature relative to the process temperature in the first process equipment is 2.

8. The temperature control method as described in claim 1 or 2, wherein, When the semiconductor workpiece being processed is a 12-inch wafer, the first point distribution includes a center point and concentric 49-point or 121-point arrays extending radially outward from the center point at distances of 25 mm, 60 mm, 80 mm, 110 mm, 120 mm, and 147 mm, respectively.

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