Method, device system and computer readable storage medium for detecting stability of thermal donor on surface of silicon wafer

Abstract

The invention provides a silicon wafer surface thermal donor stability detection method and device system, and a computer readable storage medium, and the detection method comprises the steps: S1, presetting a plurality of detection points on the surface of a to-be-detected silicon wafer, and collecting the first resistivity rho 1 at the detection points; s2, activating and annealing the to-be-tested silicon wafer to obtain an activated silicon wafer; s3, retesting the same detection point on the activated silicon wafer to obtain a second resistivity rho 2; and S4, judging the thermal donor stability of the semiconductor device based on the first resistivity rho1 and the second resistivity rho2. The method can quantify the influence of the thermal donor on the electrical properties of the silicon wafer, and realizes the rapid judgment of the stability of the thermal donor through the change of the resistivity.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material testing technology, and relates to a method, apparatus system, and computer-readable storage medium for detecting the thermal donor stability of silicon wafer surfaces. Background Technology

[0002] The stability of silicon wafer resistivity is crucial for the yield of semiconductor devices. During heat treatment in the process temperature range of 350~550℃, oxygen-containing CZ / MCZ silicon wafers undergo a series of complex reactions due to interstitial oxygen accumulation, which easily generates microscopic defect groups—thermal donors (TDs). This leads to uncontrolled resistivity and drift, resulting in a decrease in resistivity and an increase in carrier concentration. Consequently, it affects the threshold and yield consistency of subsequent device processes and may also cause current leakage, thus degrading device performance.

[0003] The uneven distribution of thermal donors on the silicon wafer surface easily leads to the formation of surface channels and causes disordered vertical doping distribution. Semiconductor device fabrication processes involve multiple low-temperature steps, making the thermal donors on the silicon wafer unstable and severely complicating the control of device electrical performance. Therefore, the detection of thermal donor stability is essential. Since the formation of thermal donors is closely related to oxygen concentration, current methods for detecting thermal donor stability generally rely on estimating the oxygen content in the inter-wafer space. However, this method has high uncertainty and cannot be quantified, resulting in inaccurate detection results.

[0004] Therefore, how to quantify the electrical drift risk induced by TD at the incoming material stage and form a repeatable and comparable testing and evaluation system in the supply chain has become the key to controlling the consistency of semiconductor device manufacturing processes. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method, apparatus system, and computer-readable storage medium for detecting the thermal donor stability of silicon wafer surfaces, which is matched with the process temperature range and achieves rapid determination of the thermal donor stability of silicon wafers under typical thermal conditions of 450~550°C by measuring changes in resistivity.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for detecting the thermal donor stability of a silicon wafer surface, the method comprising: S1: pre-setting multiple detection points on the surface of the silicon wafer to be tested, and collecting the first resistivity ρ1 at the detection points; S2: performing activation annealing on the silicon wafer to be tested to obtain an activated silicon wafer; S3: re-testing the same detection points on the activated silicon wafer to obtain a second resistivity ρ2; S4: determining the thermal donor stability of the semiconductor device based on the first resistivity ρ1 and the second resistivity ρ2.

[0008] This invention uses the resistivity of semiconductor devices as an evaluation parameter. By comparing the changes in resistivity before and after activation annealing, it can intuitively quantify the impact of thermal donors on the electrical performance of semiconductor devices, thereby improving the accuracy of stability testing.

[0009] As a preferred technical solution of the present invention, in steps S1 and S3, the first resistivity ρ1 or the second resistivity ρ2 of each detection point is obtained by the four-probe test method.

[0010] In one embodiment of the present invention, a plurality of detection points are arranged in an array to form a measurement point array, the measurement point array covering at least the central area and the edge area of ​​the surface of the silicon wafer to be tested.

[0011] In one embodiment of the present invention, the distance from the outer boundary of the edge region to the outer edge of the silicon wafer to be tested is 3~5mm, and the central region is the area from the center of the surface of the silicon wafer to be tested to the inner boundary of the edge region.

[0012] The distance from the outer boundary of the edge region to the outer edge of the silicon wafer under test can be 3.0mm, 3.2mm, 3.5mm, 3.8mm, 4.0mm, 4.3mm, 4.5mm, 4.8mm or 5.0mm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] In one embodiment of the present invention, the number of detection points in the measuring point array is ≥49.

[0014] In one embodiment of the present invention, the measuring point array is distributed in a ring-shaped pattern or a checkerboard pattern.

[0015] As a preferred embodiment of the present invention, the detection method further includes: after the activation annealing is completed, performing enhanced annealing on the activated silicon wafer to determine the thermal donor stability under enhanced stress.

[0016] In one embodiment of the present invention, the activation annealing temperature is 350~550℃, for example, it can be 350℃, 400℃, 450℃, 500℃ or 550℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] In one embodiment of the present invention, the activation annealing time is 18 to 30 hours, for example, it can be 18 hours, 19 hours, 20 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 28 hours or 30 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] In one embodiment of the present invention, the heating rate and cooling rate during the activation annealing process are independently 5~10°C / min, for example, 5°C / min, 5.5°C / min, 6°C / min, 6.5°C / min, 7°C / min, 7.5°C / min, 8°C / min, 8.5°C / min, 9°C / min, 9.5°C / min or 10°C / min, but are not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0019] In one embodiment of the present invention, the activation annealing is performed under an inert atmosphere.

[0020] In one embodiment of the present invention, the inert atmosphere includes N2 or Ar.

[0021] In one embodiment of the present invention, the temperature of the enhanced annealing treatment is 450~550℃, for example, it can be 450℃, 480℃, 500℃, 520℃ or 550℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] In one embodiment of the present invention, the time for the enhanced annealing treatment is 3 to 8 hours, for example, it can be 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] As a preferred technical solution of the present invention, the judgment in step S4 includes: calculating the absolute value of the rate of change of resistivity P1 at each detection point based on the first resistivity ρ1 and the second resistivity ρ2, judging whether P1≤8% is satisfied, and analyzing the stability of the silicon wafer under test.

[0024] As a preferred technical solution of the present invention, the judgment further includes: calculating the standard deviation 3σ(P1) of the absolute value of the change rate P1 of multiple detection points on the same silicon wafer surface, and judging whether 3σ(P1) ≤ 5%.

[0025] As a preferred embodiment of the present invention, when there are multiple silicon wafers to be tested, the detection method further includes: calculating the average value μ0 of the absolute value of the rate of change P1 of each silicon wafer to be tested, and determining whether μ0 among multiple silicon wafers to be tested satisfies 3σ(μ0)≤6%.

[0026] This invention can calculate the standard deviation of the rate of change of multiple detection points on the surface of the same silicon wafer, realizing the stability detection of multiple sites within the wafer. It can also calculate the standard deviation of the rate of change of detection points on the surface of the same batch of silicon wafers, realizing the detection of resistivity fluctuations between batches.

[0027] As a preferred embodiment of the present invention, the detection method further includes edge sensitivity identification, wherein the edge sensitivity identification method includes: increasing the number of detection points in the edge region of the surface of the silicon wafer to be tested; obtaining the average value of the first resistivity μ1(Z) and the average value of the second resistivity μ2(Z) at multiple detection points in the central region of the silicon wafer to be tested before and after the activation annealing, and the average value of the first resistivity μ1(B) and the average value of the second resistivity μ2(B) at multiple detection points in the edge region of the silicon wafer to be tested before and after the activation annealing; calculating the absolute value of the rate of change of the average resistivity in the central region of the silicon wafer to be tested P1(Z) and the absolute value of the rate of change of the average resistivity in the edge region of the silicon wafer to be tested P1(B); determining whether P1(B)-P1(Z)≥2%, and thus evaluating the edge sensitivity of the silicon wafer.

[0028] This invention identifies edge stability by statistically analyzing the differences between the central and edge regions of the silicon wafer surface under test, thereby indicating potential risks related to radial oxygen distribution or stress in the crystal.

[0029] As a preferred embodiment of the present invention, the detection method further includes: acquiring the characteristic information of the silicon wafer to be tested, and confirming the type, size and orientation of the silicon wafer to be tested.

[0030] As one embodiment of the present invention, the feature information includes at least one of resistivity distribution map, interstitial oxygen content, carbon content and metal contamination.

[0031] As one embodiment of the present invention, the silicon wafer to be tested is an N-type silicon wafer. The resistivity of the silicon wafer to be tested is 5~200 Ω·cm, for example, it can be 5 Ω·cm, 10 Ω·cm, 20 Ω·cm, 30 Ω·cm, 50 Ω·cm, 80 Ω·cm, 100 Ω·cm, 120 Ω·cm, 150 Ω·cm, 160 Ω·cm, 180 Ω·cm or 200 Ω·cm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0032] The interstitial oxygen content of the silicon wafer to be tested is 3~10ppma, for example, it can be 3ppma, 4ppma, 5ppma, 6ppma, 7ppma, 8ppma, 9ppma or 10ppma, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] This invention can verify incoming materials to ensure that the type, size, and orientation of the silicon wafer under test meet the requirements. The detection method of this invention is applicable to the detection of thermal donor stability of different silicon wafers, and is particularly suitable for the detection of low-oxygen semiconductor devices with N-type, 300mm (device diameter), orientation <100>, and Oi (interstitial oxygen concentration) of 3~10ppma.

[0034] Secondly, the present invention provides a detection device system for the thermal donor stability of a silicon wafer surface, the detection device system comprising a resistivity detection device, an annealing device, and a control terminal; the annealing device is used to perform activation annealing on the silicon wafer to be tested; the resistivity detection device is used to acquire a first resistivity and a second resistivity at detection points on the silicon wafer to be tested before and after activation annealing, respectively; the control terminal is communicatively connected to the resistivity detection device and the annealing device, respectively, and is used to execute the detection method for the thermal donor stability of a silicon wafer surface as described in the first aspect.

[0035] Thirdly, the present invention provides a computer-readable storage medium storing a stability detection program, wherein when the stability detection program is executed by a processor, it implements the method for detecting the thermal donor stability of the silicon wafer surface as described in the first aspect, and automatically generates a judgment report and statistical indicators.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] This invention provides a method, device system, and computer-readable storage medium for detecting the thermal donor stability of silicon wafer surfaces. Based on the change in resistivity of semiconductor silicon wafers, it quantifies the actual impact of thermal donors on the electrical performance of devices and is consistent with the thermal history of the bonding process (450~550℃), which is consistent with the risks of mass production processes. It can be seamlessly connected with incoming material release and anomaly traceability, forming a repeatable detection system in the product supply chain. It can also achieve parallel statistics within the wafer and within the batch, and quickly identify inter-batch fluctuations. Attached Figure Description

[0038] Figure 1 The flowchart for thermal donor stability testing provided in Example 1 is shown.

[0039] Figure 2 This is a schematic diagram of the measuring point array in Example 1.

[0040] Figure 3 The box plot is the test result P1 of the thermal donor stability of the silicon wafer surface in Example 1.

[0041] Figure 4 The box plot is the test result P1 of the thermal donor stability of the silicon wafer surface in Example 2.

[0042] Figure 5 Box plots of μ1(Z), μ2(Z), μ1(B), and μ2(B) of the detection results of thermal donor stability on the silicon wafer surface in Example 3.

[0043] Figure 6 The box plot is the test result P1 of the thermal donor stability of the silicon wafer surface in Example 4. Detailed Implementation

[0044] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0045] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0046] In one specific embodiment, the present invention provides a method for detecting the thermal donor stability of a silicon wafer surface, the method comprising the following steps:

[0047] Step 1: Pre-set multiple detection points on the surface of the silicon wafer to be tested, and collect the first resistivity ρ1 at the detection points.

[0048] The detection method of this invention can be directly applied to the incoming material stage of semiconductor device manufacturing. Detection points can be preset according to the required silicon wafer size. In this invention, multiple detection points are arranged in an array to form a measurement point array. The measurement point array is preferably arranged in a ring-like or checkerboard pattern, with ≥49 detection points, such as 64, 81, 100, 121, 144, etc. Simultaneously, the measurement point array covers the central and edge areas of the silicon wafer surface under test. The distance from the outer boundary of the edge area to the outer edge of the silicon wafer under test is 3-5 mm, and the central area is the region from the center of the silicon wafer surface to the inner boundary of the edge area. This invention performs separate statistical analysis on the central and edge areas to facilitate edge sensitivity identification.

[0049] This invention seamlessly integrates with the incoming material release, evaluation, and anomaly tracing processes for semiconductor device manufacturing. It enables incoming material verification, specifically by acquiring characteristic information of the silicon wafer under test and confirming whether its type, size, and orientation meet requirements. This characteristic information includes at least one of resistivity distribution, interstitial oxygen content, carbon content, and metal contamination. The interstitial oxygen content and carbon content can be confirmed using the FTIR method. When inspecting batches of silicon wafers, incoming materials can be sampled to confirm their compliance with requirements. The detection method of this invention is applicable to the detection of N-type, low-oxygen semiconductor devices with a resistivity of 5–200 Ω·cm, a device diameter of 300 mm, an orientation <100>, and an Oi (interstitial oxygen concentration) of 3–10 ppma.

[0050] Step 2: Perform activation annealing on the silicon wafer to be tested to obtain an activated silicon wafer.

[0051] This invention can activate TD stress, wherein the activation annealing temperature is 350~550℃ and the time is 18~30h. The heating rate and cooling rate during the activation annealing process are each independently 5~10°C / min. Furthermore, the activation annealing is carried out under an inert atmosphere, which can be N2 or Ar.

[0052] In some embodiments, after the activation annealing is completed, the activated silicon wafer undergoes an enhanced annealing treatment to determine the thermal donor stability under enhanced stress. The enhanced annealing treatment is performed at a temperature of 450–550°C for 3–8 hours.

[0053] Step 3: Repeat the test on the same detection point on the activated silicon wafer to obtain the second resistivity ρ2.

[0054] In this invention, the resistivity detection in both step one and step three is performed using a four-probe test method to obtain the second resistivity ρ1 and second resistivity ρ2 at multiple detection points, so as to compare the resistivity before and after activation annealing. The measurement speed is fast and the data accuracy is high.

[0055] Step 4: Determine the thermal donor stability of the semiconductor device based on the first resistivity ρ1 and the second resistivity ρ2.

[0056] This invention analyzes the changes in surface resistivity of silicon wafers before and after activation annealing, which allows for a more accurate assessment of the stability of thermal donors.

[0057] The specific methods of judgment include:

[0058] Based on the first resistivity ρ1 and the second resistivity ρ2, calculate the absolute value of the rate of change of resistivity P1 at each detection point, determine whether P1≤8%, and output the first judgment result.

[0059] in, 。

[0060] When P1 satisfies P1 ≤ 8%, the detection is qualified; otherwise, it is unqualified. The detection results of the present invention can be output in the form of a heat map or a box plot.

[0061] In some embodiments, the determination method further includes: calculating the standard deviation 3σ(P1) of the absolute values of the change rates P1 of multiple detection points on the surface of the same silicon wafer to be measured, and determining whether 3σ(P1) ≤ 5% is satisfied to analyze the in-wafer thermal donor stability of the same silicon wafer to be measured.

[0062] Further, when the number of silicon wafers to be measured is multiple, that is, for a batch of silicon wafers, the detection method further includes: respectively calculating the average value μ0 of the absolute value of the change rate P1 of each silicon wafer to be measured, and determining whether μ0 among multiple silicon wafers to be measured satisfies 3σ(μ0) ≤ 6% to achieve parallel detection of the in-wafer resistivity change and the in-batch resistivity change, so as to analyze the volatility of the thermal donor stability of the batch of silicon wafers.

[0063] In some embodiments, the detection method further includes edge sensitivity identification.

[0064] The method of edge sensitivity identification includes the following steps:

[0065] S01 Increase the number of detection points in the edge area on the surface of the silicon wafer to be measured.

[0066] S02 Obtain the mean value μ1(Z) of the first resistivity and the mean value μ2(Z) of the second resistivity at multiple detection points in the central area of the silicon wafer to be measured before and after activation annealing, and the mean value μ1(B) of the first resistivity and the mean value μ2(B) of the second resistivity at multiple detection points in the edge area of the silicon wafer to be measured before and after activation annealing.

[0067] S03 Respectively calculate the absolute value of the change rate P1(Z) of the resistivity mean value in the central area of the silicon wafer to be measured and the absolute value of the change rate P1(B) of the resistivity mean value in the edge area of the silicon wafer to be measured.

[0068] Among them, , 。

[0069] S04 Determine whether P1(B) - P1(Z) ≥ 2% is satisfied. If so, the edge of the silicon wafer is not safe; otherwise, the edge sensitivity of the silicon wafer is relatively low.

[0070] In another specific embodiment, the present invention provides a detection device system for the thermal donor stability of a silicon wafer surface, including a resistivity detection device, an annealing device, and a control terminal. The annealing device is used to perform activation annealing on the silicon wafer under test; the resistivity detection device is used to acquire a first resistivity and a second resistivity at detection points on the silicon wafer under test before and after activation annealing, respectively. The control terminal is communicatively connected to both the resistivity detection device and the annealing device, and is used to execute the silicon wafer surface thermal donor stability detection method described in one specific embodiment, to calculate and analyze the thermal donor stability based on the first and second resistivity detected by the resistivity detection device, and to control the regulation and execution of the annealing device.

[0071] In another specific embodiment, the present invention provides a computer-readable storage medium storing a stability detection program thereon. When the stability detection program is executed by a processor, it implements a method for detecting the thermal donor stability of a silicon wafer surface as described in a specific embodiment, and automatically generates a judgment report and statistical indicators.

[0072] Example 1

[0073] This embodiment provides a method for testing the thermal donor stability of a 300mm diameter, N-type phosphorus-doped CZ / MCZ silicon wafer, with an orientation of <100>, interstitial oxygen content Oi = 3~10ppma, and resistivity ρ = 5~200Ω·cm. The testing procedure is as follows: Figure 1 As shown, the specific steps include the following:

[0074] (1) Obtain the resistivity distribution map and interstitial oxygen content of the silicon wafer to be tested, and confirm whether its size, orientation and type meet the above requirements.

[0075] (2) Pre-set an array of measurement points on the surface of the silicon wafer to be tested, such as... Figure 2 As shown, the measurement point array consists of 49 detection points arranged in a ring pattern, covering the central area (blue indicates detection points in the central area) and the edge area (orange indicates detection points in the edge area) of the silicon wafer surface under test. The distance from the outer boundary of the edge area to the outer edge of the silicon wafer under test is 4 mm. The central area is the region from the center of the silicon wafer surface under test to the inner boundary of the edge area. There are 33 detection points in the central area and 16 detection points in the edge area.

[0076] (3) The first resistivity ρ1 of each test point is obtained by using the four-probe test method.

[0077] (4) The silicon wafer to be tested was activated and annealed in an environment with N2 atmosphere and oxygen content ≤10ppm to obtain activated silicon wafer. The activation and annealing temperature was 450℃ and the time was 24h. The heating rate and cooling rate during the activation and annealing process were both 5°C / min.

[0078] (5) Repeat the same detection point on the activated silicon wafer using the method in step (3) to obtain the second resistivity ρ2.

[0079] (6) Calculate the absolute value of the rate of change of resistivity P1 at each detection point, and determine whether all detection points satisfy P1≤8%. If so, the test is qualified; otherwise, it is unqualified. Output the test results in the form of a box plot, such as... Figure 3 As shown.

[0080] Simultaneously, the standard deviation 3σ(P1) of the absolute value of the change rate P1 of multiple detection points on the surface of the same silicon wafer is calculated to determine whether 3σ(P1)≤5% is satisfied, so as to analyze the on-chip thermal donor stability of the same silicon wafer.

[0081] When the silicon wafer satisfies P1≤8% and 3σ(P1)≤5%, the silicon wafer is deemed to have passed the thermal donor stability test.

[0082] The sample in Example 1 satisfies P1<8% and 3σ(P1)=4.2%<5%, thus the thermal donor stability test of this silicon wafer is deemed qualified.

[0083] Example 2

[0084] This embodiment provides a method for testing the thermal donor stability of a 300mm diameter, N-type phosphorus-doped CZ / MCZ silicon wafer. The silicon wafer has an orientation of <100>, interstitial oxygen content Oi = 3~10ppma, and resistivity ρ = 5~200Ω·cm. The difference from Embodiment 1 is that after activation annealing, the activated silicon wafer undergoes enhanced annealing to determine its thermal donor stability under enhanced stress. The enhanced annealing temperature is 500℃, and the time is 4 hours.

[0085] In step (6), it is necessary to determine whether P1≤8% is satisfied. If P1≤8% is satisfied, the silicon wafer is deemed to have passed the thermal donor stability test under enhanced stress. The remaining steps are the same as in Example 1.

[0086] like Figure 4 As shown, the sample in Example 2 satisfies P1<8% and 3σ(P1)=3.2%<5%, thus the thermal donor stability test of this silicon wafer is deemed qualified.

[0087] Example 3

[0088] This embodiment provides a method for detecting the thermal donor stability of a 300mm diameter, N-type phosphorus-doped CZ / MCZ silicon wafer, with an orientation of <100>, interstitial oxygen content Oi = 3~10ppma, and resistivity ρ = 5~200Ω·cm. The difference from Embodiment 1 is that the detection method further includes statistically analyzing the resistivity data of the central and edge regions to identify the edge sensitivity of the silicon wafer. Specifically, the following steps are included:

[0089] S01 increases the number of detection points in the edge area of ​​the silicon wafer surface to be tested to 24.

[0090] S02 Calculate the mean value μ1(Z) of the first resistivity at the detection point located in the center area of ​​the silicon wafer under test before activation annealing, the mean value μ2(Z) of the first resistivity at the detection point located in the center area of ​​the silicon wafer under test after activation annealing, the mean value μ1(B) of the first resistivity at the detection point located in the edge area of ​​the silicon wafer under test before activation annealing, and the mean value μ2(B) of the second resistivity at the detection point located in the edge area of ​​the silicon wafer under test after activation annealing.

[0091] S03 calculates the absolute value of the rate of change of the average resistivity in the central region of the silicon wafer under test, P1(Z), using the following formula:

[0092] .

[0093] The absolute value of the rate of change of the average resistivity within the edge region of the silicon wafer under test, P1(B), is calculated using the following formula:

[0094] .

[0095] S04 determines whether P1(B)-P1(Z)≥2%. If so, the silicon wafer edge is unsafe, indicating risks related to radial oxygen distribution or stress in the crystal. Conversely, the silicon wafer edge sensitivity is low.

[0096] like Figure 5 As shown, the μ1(Z) of the sample in Example 3 is 109.618 ohm-cm; μ2(Z) is 105.886 ohm-cm; μ1(B) is 108.764 ohm-cm; μ2(B) is 106.323 ohm-cm.

[0097] Further calculations showed that P1(Z) = 3.4%; P1(B) = 2.2%; and P1(B) - P1(Z) = 1.2% < 2%, indicating that the silicon wafer edge sensitivity is low.

[0098] Example 4

[0099] This embodiment uses the detection method provided in Embodiment 1 to perform thermal donor stability testing on a batch of silicon wafers, specifically including the following steps:

[0100] (1) Five silicon wafers were selected from the batch for random sampling, namely silicon wafer 1, silicon wafer 2, silicon wafer 3, silicon wafer 4 and silicon wafer 5. The resistivity distribution map and interstitial oxygen content of the silicon wafers to be tested were obtained, and it was confirmed whether they met the requirements of thermal donor stability of N-type CZ / MCZ silicon wafers with a diameter of 300mm. The silicon wafers had an orientation of <100>, interstitial oxygen content Oi=3~10ppma, and resistivity ρ=5~200Ω·cm.

[0101] (2) A measurement point array is preset on the surface of each silicon wafer to be tested. The measurement point array consists of 64 detection points distributed in a checkerboard pattern, covering the central area and edge area of ​​the silicon wafer to be tested. The distance from the outer boundary of the edge area to the outer edge of the silicon wafer to be tested is 3~5mm. The central area is the area from the center of the silicon wafer to the inner boundary of the edge area. The number of detection points in the central area is 34, and the number of detection points in the edge area is 30.

[0102] (3) The first resistivity ρ1 of each test point is obtained by using the four-probe test method.

[0103] (4) The silicon wafer to be tested was activated and annealed in an environment with N2 atmosphere and oxygen content ≤10ppm to obtain activated silicon wafer. The activation and annealing temperature was 450℃ and the time was 24h. The heating rate and cooling rate during the activation and annealing process were both 10°C / min.

[0104] (5) Repeat the same detection point on the activated silicon wafer using the method in step (3) to obtain the second resistivity ρ2.

[0105] (6) Calculate the absolute value of the rate of change of resistivity P1 at each detection point, and determine whether P1≤8%. If yes, the test is qualified; otherwise, it is unqualified. Output the test results in the form of a box plot.

[0106] Simultaneously, the standard deviation 3σ(P1) of the absolute value of the change rate P1 of multiple detection points on the surface of the same silicon wafer is calculated to determine whether 3σ(P1)≤5% is satisfied, so as to analyze the on-chip thermal donor stability of the same silicon wafer.

[0107] In addition, the average value μ0 of the absolute value of the rate of change P1 of each silicon wafer under test is calculated to determine whether μ0 between multiple silicon wafers under test satisfies 3σ(μ0)≤6%, thereby realizing parallel detection of intra-wafer resistivity change and intra-batch resistivity change, so as to analyze the fluctuation of thermal donor stability of batch silicon wafers.

[0108] As shown in Table 1 and Figure 6As shown in Example 4, firstly, based on the box plot, it was determined that each silicon wafer met the condition that P1 ≤ 8%. Further calculations showed that the standard deviation 3σ(P1) of the absolute value of the rate of change P1 for each silicon wafer met the criterion of 3σ(P1) ≤ 5%. Finally, it was determined that the average value μ0 of the absolute value of the rate of change P1 for each tested silicon wafer had a 3σ(μ0) = 0.91%, satisfying 3σ(μ0) ≤ 6%. Ultimately, it was determined that the thermal donor stability of the batch of silicon wafers met the requirements.

[0109] Table 1

[0110]

[0111] This invention compares the resistivity of a silicon wafer before and after activation and deactivation using an internal measuring point array, with an absolute change rate of ≤5%, and provides on-wafer preferred batch-level 3σ statistics, which can more accurately determine the stability of thermal donors.

[0112] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for detecting the thermal donor stability of a silicon wafer surface, characterized in that, The detection method includes: S1: Multiple detection points are preset on the surface of the silicon wafer to be tested, and the first resistivity ρ1 at the detection points is collected; S2: Perform activation annealing on the silicon wafer to be tested to obtain an activated silicon wafer; S3: Repeat the same detection point on the activated silicon wafer to obtain the second resistivity ρ2; S4: Determine the thermal donor stability of the semiconductor device based on the first resistivity ρ1 and the second resistivity ρ2.

2. The detection method according to claim 1, characterized in that, In steps S1 and S3, the first resistivity ρ1 or the second resistivity ρ2 of each detection point is obtained by the four-probe test method. Preferably, the plurality of detection points are arranged in an array to form a measurement point array, and the measurement point array at least covers the central area and the edge area of ​​the surface of the silicon wafer to be tested; Preferably, the distance from the outer boundary of the edge region to the outer edge of the silicon wafer to be tested is 3~5mm, and the central region is the area from the center of the surface of the silicon wafer to be tested to the inner boundary of the edge region; Preferably, the number of detection points in the measuring point array is ≥49.

3. The detection method according to any one of claims 1-2, characterized in that, The detection method further includes: after the activation annealing is completed, the activated silicon wafer is subjected to enhanced annealing treatment to determine the thermal donor stability under enhanced stress; Preferably, the activation annealing temperature is 350~550℃; Preferably, the activation annealing time is 18-30 hours; Preferably, the heating rate and cooling rate during the activation annealing process are each independently 5~10°C / min; Preferably, the activation annealing is performed under an inert atmosphere; Preferably, the inert atmosphere includes N2 or Ar; Preferably, the temperature of the enhanced annealing treatment is 450~550℃; Preferably, the enhanced annealing treatment takes 3 to 8 hours.

4. The detection method according to any one of claims 1-3, characterized in that, In step S4, the determination includes: Based on the first resistivity ρ1 and the second resistivity ρ2, calculate the absolute value of the rate of change of resistivity P1 at each detection point, determine whether P1≤8%, and analyze the stability of the silicon wafer under test.

5. The detection method according to claim 1 or 4, characterized in that, The judgment also includes: calculating the standard deviation 3σ(P1) of the absolute value of the change rate P1 of multiple detection points on the same silicon wafer surface, and judging whether 3σ(P1) ≤ 5%.

6. The detection method according to claim 4 or 5, characterized in that, When there are multiple silicon wafers to be tested, the detection method further includes: calculating the average value μ0 of the absolute value of the rate of change P1 of each silicon wafer to be tested, and determining whether μ0 among multiple silicon wafers to be tested satisfies 3σ(μ0)≤6%.

7. The detection method according to claim 2, characterized in that, The detection method further includes edge sensitivity recognition, and the edge sensitivity recognition method includes: Increase the number of detection points in the edge region of the silicon wafer surface under test; The average value of the first resistivity μ1(Z) and the average value of the second resistivity μ2(Z) at multiple detection points in the central region of the silicon wafer under test before and after the activation annealing are obtained, as well as the average value of the first resistivity μ1(B) and the average value of the second resistivity μ2(B) at multiple detection points in the edge region of the silicon wafer under test before and after the activation annealing. Calculate the absolute value of the rate of change of the average resistivity in the central region of the silicon wafer under test, P1(Z), and the absolute value of the rate of change of the average resistivity in the edge region of the silicon wafer under test, P1(B). Determine whether P1(B)-P1(Z)≥2% is satisfied, and then assess the edge sensitivity of the silicon wafer.

8. The detection method according to any one of claims 1-7, characterized in that, The detection method further includes: acquiring the characteristic information of the silicon wafer to be tested, and confirming the type, size and orientation of the silicon wafer to be tested; Preferably, the feature information includes at least one of resistivity distribution map, interstitial oxygen content, carbon content, and metal contamination; Preferably, the silicon wafer to be tested is an N-type silicon wafer; the resistivity of the silicon wafer to be tested is 5~200Ω·cm; and the interstitial oxygen content of the silicon wafer to be tested is 3~10ppma.

9. A detection device system for the thermal donor stability of a silicon wafer surface, characterized in that, The aforementioned detection device system includes a resistivity detection device, an annealing device, and a control terminal; The annealing device is used to activate and anneal the silicon wafer to be tested. The resistivity detection device is used to acquire the first resistivity and the second resistivity of the silicon wafer under test at the detection point before and after activation annealing, respectively. The control terminal is communicatively connected to the resistivity detection device and the annealing device, respectively, and is used to execute the method for detecting the thermal donor stability of the silicon wafer surface as described in any one of claims 1-8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a stability detection program, which, when executed by a processor, implements the method for detecting the thermal donor stability of the silicon wafer surface as described in any one of claims 1-8, and automatically generates a judgment report and statistical indicators.

Images