Measurement monitoring method for eliminating time influence

Abstract

The invention provides a measurement monitoring method for eliminating time influence. The method comprises the following steps: collecting measurement data at different measurement times; judging whether the measurement data is related to the measurement time or not, if not, directly outputting the measurement data, and if yes, establishing a relation model of the measurement time and the measurement data; calculating the measurement data after the time influence is compensated according to the relation between the measurement time and the measurement data in the relation model; and outputting the compensated actual measurement data. According to the invention, by calculating the measurement data after the time influence is compensated, the influence of the time factor on the measurement result can be eliminated, and the accuracy of the measurement result and the precise monitoring of the machine can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor integrated circuits, and in particular to a measurement and monitoring method that eliminates time influence. Background Art

[0002] Metrology is the "eyes" of the fabrication facility (FAB) and is essential to the semiconductor manufacturing process. On the one hand, it monitors process equipment to ensure its normal operation. On the other hand, metrology also covers all real-time monitoring of process flow items, including film thickness, critical dimensions, dosage, and resistance. However, some measurement stations are affected by time, and the results obtained at different times can vary, which poses significant challenges.

[0003] For example, after ion implantation, the wafer undergoes lattice self-repair. During thermal wave (TMW) measurement, the TMW value decays over time, resulting in significant variations in TMW values ​​measured at different times, making it impossible to accurately monitor other variables. Thin films such as gate oxides oxidize over time, resulting in varying thicknesses at different times, making it impossible to accurately measure the thickness of the film during the process. Oxide layers are relatively stable, and thickness measurement equipment typically uses oxide-layer wafers as monitoring wafers. However, oxide layers oxidize over time, and over time, the monitoring chart exhibits an upward trend, making it impossible to precisely define the chart's specifications.

[0004] The above issues are all due to time constraints. Eliminating this factor is crucial for achieving accurate measurement, effectively controlling specifications, and accurately monitoring machine stability. Currently, eliminating the impact of time on measurement values ​​is commonly achieved through time control, requiring measurement to be completed within a short period of time after exiting the process machine. However, this approach is labor-intensive and costly, and is subject to numerous uncertainties. For example, each batch must exit the process machine and arrive at the measurement machine at the same time, and the measurement machine must be operating normally and idle, making it extremely challenging to achieve. Summary of the Invention

[0005] The object of the present invention is to provide a measurement and monitoring method that eliminates the influence of time factors on measurement results, thereby improving the accuracy of measurement results and accurately monitoring the machine.

[0006] To solve the above technical problems, the present invention provides a measurement and monitoring method that eliminates the influence of time, comprising the following steps:

[0007] Collect measurement data at different measurement times;

[0008] Determine whether the measurement data is correlated with the measurement time. If not, directly output the measurement data. If so, establish a relationship model between the measurement time and the measurement data.

[0009] Calculating the measurement data after compensating for the time effect according to the relationship between the measurement time and the measurement data in the relationship model; and

[0010] Output the actual measured data after compensation.

[0011] Optionally, the relationship model includes a relationship curve between measurement time and measurement data.

[0012] Optionally, the method of establishing a relationship model between measurement time and measurement data includes:

[0013] Draw a scatter plot based on measurement time and measurement data;

[0014] The relationship curve between the measurement time and the measurement data is obtained by fitting the scatter plot.

[0015] Optionally, the relationship curve is Y=f(t)+C, where t is the measurement time and C is a constant; the original measurement data is recorded as A, and the actual measurement data after compensation is recorded as B, then the relationship between the measurement time and the measurement data is B=Af(t).

[0016] Optionally, the measurement data includes thermal wave measurement data and film thickness measurement data.

[0017] Optionally, when the measurement data is thermal wave measurement data, the measurement time is the time from when the wafer is transferred from the host machine to when it is measured.

[0018] Optionally, the main machine is an ion implantation machine.

[0019] Optionally, when the measurement data is film thickness measurement data, the measurement data is measurement values ​​of the same wafer at different measurement times, and the measurement time is the time from the first measurement of the wafer to the current measurement.

[0020] Optionally, MES is used to collect measurement data at different measurement times, and the relationship model is set in MES, and the MES display value is the actual measurement data after compensating for the time effect.

[0021] Optionally, the specifications of the monitoring chart are set according to the actual measurement data.

[0022] In summary, the measurement and monitoring method for eliminating time effects provided by the present invention first collects measurement data at different measurement times. A determination is then made as to whether the measurement data and the measurement time are correlated. If not, the measurement data is directly output. If so, a relationship model is established between the measurement time and the measurement data. Based on the relationship between the measurement time and the measurement data in the relationship model, the measurement data is then calculated after compensating for the time effect, and the actual compensated measurement data is output. By calculating the measurement data after time effects are compensated, the present invention eliminates the influence of time factors on measurement results, improving the accuracy of measurement results and enabling precise monitoring of equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0024] Figure 1 4 is a flow chart of a measurement and monitoring method for eliminating time influence provided by an embodiment of the present invention.

[0025] Figure 2 Schematic diagram of the relationship between measurement data and measurement time in thermal wave measurement provided by the first embodiment of the present invention.

[0026] Figure 3 1 is a schematic diagram showing the relationship between measurement data and measurement time after compensating for time effects in thermal wave measurement provided by the first embodiment of the present invention.

[0027] Figure 4 Schematic diagram of the relationship between measurement data and measurement time in film thickness measurement provided by the second embodiment of the present invention.

[0028] Figure 5 1 is a schematic diagram showing the relationship between measurement data and measurement time after compensating for time influence in film thickness measurement provided by the second embodiment of the present invention. DETAILED DESCRIPTION

[0029] To make the objects, advantages, and features of the present invention more clearly apparent, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale. They are only used to conveniently and clearly assist in illustrating the purposes of the embodiments of the present invention. In addition, the structures shown in the drawings are often part of the actual structure. In particular, different drawings may need to illustrate different focuses and sometimes use different scales.

[0030] As used in the present invention, the singular forms "a", "an" and "the" include plural objects, unless the content clearly indicates otherwise. As used in the present invention, the term "or" is generally used in a sense including "and / or", unless the content clearly indicates otherwise. As used in the present invention, the term "several" is generally used in a sense including "at least one", unless the content clearly indicates otherwise. As used in the present invention, the term "at least two" is generally used in a sense including "two or more", unless the content clearly indicates otherwise. In addition, the terms "first", "second" and "third" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" and "third" may explicitly or implicitly include one or at least two of the features.

[0031] Figure 1 This is a flow chart of a measurement and monitoring method that eliminates time effects provided by an embodiment of the present invention. Figure 1 As shown, the measurement and monitoring method for eliminating time influence provided in this embodiment includes the following steps:

[0032] S1: Collect measurement data at different measurement times;

[0033] S2: Determine whether the measurement data is correlated with the measurement time. If not, directly output the measurement data. If so, establish a relationship model between the measurement time and the measurement data.

[0034] S3: calculating the measurement data after compensating for the time influence according to the relationship between the measurement time and the measurement data in the relationship model; and

[0035] S4: Output the actual measurement data after compensation.

[0036] The present invention can obtain true measurement data by calculating the measurement data after compensating the time effect, thereby eliminating the influence of the time factor on the measurement result, improving the accuracy of the measurement result and the precise monitoring of the machine.

[0037] In step S1, measurement data at different measurement times are collected. In this embodiment, the measurement data at different measurement times are collected using an MES (Manufacturing Execution System).

[0038] In one embodiment of the present invention, existing measurement data in the MES can be collected. For example, when measuring film thickness, previously measured data and the corresponding measurement time can be collected. In another embodiment of the present invention, measurement data can also be collected by re-measurement. For example, when measuring thermal wave, measurement values ​​of the same wafer at different measurement times can be used as measurement data.

[0039] In step S2, it is determined whether the measurement data is correlated with the measurement time. If not, the measurement data is directly output. If so, a relationship model between the measurement time and the measurement data is established.

[0040] If the measured data is not related to the measurement time, then, under the premise of no other influencing factors, the difference in the measured data at different measurement times is within the error range. If the measured data is related to the measurement time, then as the measurement time increases, the measured data may increase or decrease regularly.

[0041] If the measurement data is not related to the measurement time, there is no need to eliminate the influence of time, and the measured measurement data can be directly output. If the measurement data is related to the measurement time, a relationship model between the measurement time and the measurement data is established.

[0042] In this embodiment, the relationship model includes a relationship curve between the measurement time and the measurement data, but is not limited thereto. For example, a scatter plot is drawn based on the measurement time and the measurement data, and then the relationship curve between the measurement time and the measurement data is obtained by fitting the scatter plot.

[0043] In step S3 , the measurement data after compensating for the time effect is calculated according to the relationship between the measurement time and the measurement data in the relationship model.

[0044] For example, the relationship curve is Y = f(t) + C, where t is the measurement time and C is a constant. Let the original measurement data be A and the actual measurement data after compensation be B, then B = Af(t). The actual measurement data B is calculated based on the measurement time t and the original measurement data A (i.e., the measurement data directly measured at the measurement time t).

[0045] In step S4, the compensated actual measurement data is output.

[0046] The relationship model is set in MES, and the value displayed by MES is the actual measurement data after compensating for the time effect.

[0047] The measurement data includes thermal wave measurement data and film thickness measurement data, but is not limited thereto.

[0048] The following describes the invention through specific examples.

[0049] [Example 1] Thermal Wave Measurement

[0050] In step S1 , the MES is used to collect measurement data at different measurement times during thermal wave measurement.

[0051] In step S2, it is determined whether the measurement data is correlated with the measurement time. The thermal wave value of the wafer measured after IMP decays with time, and the measurement data is correlated with the measurement time.

[0052] In step S3 , a scatter plot is drawn between the measurement time and the thermal wave measurement value, and a linear model is obtained by fitting. Figure 2 This is a diagram showing the relationship between the measurement data and the measurement time in the thermal wave measurement provided by the first embodiment of the present invention. Figure 2 As shown, the measurement time and thermal wave measurement value exhibit a logarithmic relationship, resulting in a fitting model: y = -8.672ln(x) + 848.47. The original thermal wave measurement data (i.e., directly measured data) is denoted as A, the actual measurement data after compensation is denoted as B, and t is the measurement time, which is the time it takes for the wafer to be measured from the main station. The relationship between measurement time and measurement data is B = 8.672ln(t) + A. After obtaining the original measurement data A during thermal wave measurement, substitute the original measurement data A and its corresponding measurement time into the relationship to calculate the measurement data after time compensation, i.e., the actual measurement data B.

[0053] Figure 3 This is a diagram showing the relationship between the measured data and the measurement time after compensating for the time effect in the thermal wave measurement provided by the first embodiment of the present invention. Figure 3 As shown, after time compensation, the influence of time factors on the measurement data is eliminated, and actual measurement data can be obtained, thereby improving the accuracy of the measurement results and accurately monitoring the machine.

[0054] In this embodiment, the measurement time is the time from when the wafer is transferred from the main machine to when it is measured. The main machine is an ion implantation machine, and ions are implanted into the wafer using the ion implantation machine. After the ion implantation is completed, the wafer is transferred from the ion implantation machine. The timing starts from the time of transfer, and the time to when the thermal wave is measured is the measurement time t. The measured data is the original measurement data A. The actual measurement data B is calculated based on the measurement time t and the original measurement data value A.

[0055] In step S4, the compensated actual measurement data is output.

[0056] By setting the above relationship model in MES, the MES display value is the actual measurement data after compensating for the influence of time, so that the specifications of the monitoring chart can be tightened, facilitating accurate monitoring of the stability of the measuring machine.

[0057] [Example 2] Film Thickness Measurement

[0058] Inline sites measure the thickness of thin films such as TiN. To ensure measurement accuracy and stability, wafers deposited with TiN are used as monitor wafers for the thickness measurement equipment and measured every two days. TiN, like an oxide layer, oxidizes, and the film thickness increases over time. If the specifications are too tight, OOC (Out of Control) levels will soon trigger shutdowns and false alarms, necessitating frequent retargeting. However, if the specifications are too loose, tool anomalies may not be detected promptly.

[0059] The TiN film thickness is monitored by the measurement and monitoring method for eliminating the time influence of the present invention.

[0060] In step S1, MES is used to collect measurement data at different measurement times. For example, the measurement data are measurement values ​​of the same wafer at different measurement times, and the measurement time is the time from the first measurement of the wafer to the current measurement.

[0061] In step S2 , it is determined whether the measurement data is correlated with the measurement time. The correlation between the TiN film thickness and the measurement time is significant.

[0062] In step S3 , a scatter plot is drawn between the measurement time and the film thickness measurement data, and a linear model is obtained by fitting. Figure 4 This is a schematic diagram of the relationship between the measurement data and the measurement time in the film thickness measurement provided by the second embodiment of the present invention. Please refer to Figure 4 As shown, the relationship curve between measurement time and film thickness data is: y = 0.0034x + 11.572. The original film thickness measurement data (i.e., the data obtained directly from measurement) is denoted as A, the actual measurement data after compensation is denoted as B, and t is the measurement time, which is the time from the first wafer measurement to the current measurement, in days. The relationship between measurement time and film thickness data is B = A - 0.0034t. After obtaining the original measurement data A during TiN film thickness measurement, the original measurement data A and the corresponding measurement time are substituted into the relationship to calculate the measurement data after time compensation, i.e., the actual measurement data B.

[0063] Figure 5 This is a diagram showing the relationship between the measured data and the measurement time after compensating for the time effect in the film thickness measurement provided by the second embodiment of the present invention. Figure 5 As shown, after time compensation, the influence of time factors on the measurement data is eliminated, and actual measurement data can be obtained, thereby improving the accuracy of the measurement results and accurately monitoring the machine.

[0064] In this embodiment, the measurement time is the time from the first measurement of the wafer to the current measurement. The main machine is, for example, a CVD machine. The CVD machine is used to form a TiN film layer on the wafer, and then the TiN film layer is measured using a film thickness measurement machine. The time from the first measurement to the current measurement is the measurement time t. The measured data is the original measurement data A. The actual measurement data B is calculated based on the measurement time t and the original measurement data A.

[0065] In step S4, the compensated actual measurement data is output.

[0066] By setting the above relationship model in the MES, the MES display value is the actual measurement data after compensating for the influence of time, so as to strictly adhere to the specifications of the monitoring chart, avoid false alarms caused by wafer oxidation, and more accurately capture machine anomalies, facilitating accurate monitoring of the stability of the measurement machine.

[0067] Of course, the film thickness measurement in this embodiment is not limited to TiN; it can also be used for materials such as oxide layers whose thickness changes over time. This embodiment is also not limited to thermal wave measurement and film thickness measurement. Any measurement whose measurement data changes over time can be measured and monitored using the measurement and monitoring method described in this invention that eliminates the influence of time.

[0068] In summary, the measurement and monitoring method for eliminating time effects provided by the present invention first collects measurement data at different measurement times. A determination is then made as to whether the measurement data and the measurement time are correlated. If not, the measurement data is directly output. If so, a relationship model is established between the measurement time and the measurement data. Based on the relationship between the measurement time and the measurement data in the relationship model, the measurement data is then calculated after compensating for the time effect, and the actual compensated measurement data is output. By calculating the measurement data after time effects are compensated, the present invention eliminates the influence of time factors on measurement results, improving the accuracy of measurement results and enabling precise monitoring of equipment.

[0069] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A measurement and monitoring method that eliminates the influence of time, characterized in that: The following steps are involved: Collect measurement data at different measurement times; Determine whether the measurement data is correlated with the measurement time. If not, directly output the measurement data. If so, establish a relationship model between the measurement time and the measurement data. Calculating the measurement data after compensating for the time influence according to the relationship between the measurement time and the measurement data in the relationship model; as well as Output the actual measured data after compensation.

2. The measurement and monitoring method for eliminating time influence according to claim 1, characterized in that: The relationship model includes a relationship curve between measurement time and measurement data.

3. The measurement and monitoring method for eliminating time influence according to claim 2, characterized in that: Methods for establishing a relationship model between measurement time and measurement data include: Draw a scatter plot based on measurement time and measurement data; The relationship curve between the measurement time and the measurement data is obtained by fitting the scatter plot.

4. The measurement and monitoring method for eliminating time influence according to claim 3, characterized in that: The relationship curve is Y=f(t)+C, where t is the measurement time and C is a constant. The original measurement data is recorded as A and the actual measurement data after compensation is recorded as B. Then, the relationship between the measurement time and the measurement data is B=Af(t).

5. The measurement and monitoring method for eliminating time influence according to claim 1, characterized in that: The measurement data includes thermal wave measurement data and film thickness measurement data.

6. The measurement and monitoring method for eliminating time influence according to claim 5, characterized in that: When the measurement data is thermal wave measurement data, the measurement time is the time from when the wafer is transferred from the host machine to when it is measured.

7. The measurement and monitoring method for eliminating time influence according to claim 6, characterized in that: The main machine is an ion implantation machine.

8. The measurement and monitoring method for eliminating time influence according to claim 5, characterized in that: When the measurement data is film thickness measurement data, the measurement data is measurement values ​​of the same wafer at different measurement times, and the measurement time is the time from the first measurement of the wafer to the current measurement.

9. The measurement and monitoring method for eliminating time influence according to any one of claims 1 to 8, characterized in that: The measurement data of different measurement times are collected by MES, the relationship model is set in MES, and the MES display value is the actual measurement data after compensating for the time influence.

10. The measurement and monitoring method for eliminating time influence according to claim 9, characterized in that: The specifications of the monitoring chart are set according to the actual measurement data.

Images