Method and system for monitoring ion implantation energy

Abstract

The invention relates to a method and system for monitoring ion implantation energy, and the method comprises the following steps: carrying out the ion implantation of a semiconductor substrate, and forming an amorphous layer; measuring the thickness of the amorphous layer; and judging whether ion implantation energy is abnormal or not according to the thickness of the amorphous layer. In experiments, the inventor finds that when ion implantation energy fluctuates, obvious changes can be brought to the thickness of the amorphous layer, and the ion implantation dose can influence the ion concentration and cannot influence the thickness of the amorphous layer, so that the thickness of the amorphous layer can be measured by performing ion implantation on the semiconductor substrate to form the amorphous layer and then measuring the thickness of the amorphous layer. The ion implantation energy is monitored according to the thickness of the amorphous layer, and the method can effectively monitor the implantation energy deviation caused by an ion implantation machine, thereby reducing the quality fluctuation brought to a device, and providing a new feasible method for monitoring the ion implantation energy.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a method and system for monitoring ion implantation energy. Background Art

[0002] Ion implantation technology is a material surface modification technology that has flourished and been widely used internationally in the past 30 years. It is also one of the essential key processes in the field of semiconductor manufacturing. It is defined as: ionized atoms are injected into the surface of the target material under the acceleration of a strong electric field to change the physical or chemical properties of the target material surface.

[0003] There are two key process parameters for ion implantation: implantation energy and implantation dose. In general wafer manufacturing plants, the daily monitoring method for ion implantation is to implant ions with a certain energy and dose on the bare silicon wafer, perform lattice loss repair and ion activation through rapid thermal annealing, and finally measure the sheet resistance with a sheet resistance meter. Due to different doses and different energy doping, the degree of improvement in the electrical properties of the wafer is also different, thus achieving the purpose of monitoring the ion implantation dose and energy.

[0004] However, in reality, the deviation of injection energy will not have a significant effect on the block resistance. The traditional method can only effectively monitor the deviation of ion injection dose. There is currently a lack of an efficient and feasible monitoring method for injection energy. Summary of the invention

[0005] Based on this, it is necessary to provide an effective and feasible monitoring method and system for ion implantation energy.

[0006] A method for monitoring ion implantation energy comprises the following steps:

[0007] Performing ion implantation on a semiconductor substrate to form an amorphous layer, wherein the semiconductor substrate has a crystalline structure;

[0008] measuring the thickness of the amorphous layer;

[0009] Whether the ion implantation energy is abnormal is determined according to the thickness of the amorphous layer.

[0010] In some embodiments, it also includes:

[0011] obtaining a plurality of standard semiconductor substrates;

[0012] Performing ion implantation on the standard semiconductor substrate with different standard ion implantation energies to obtain a plurality of standard amorphous layers;

[0013] measuring the thickness of each of the standard amorphous layers;

[0014] According to the standard ion implantation energy and the thickness of the standard amorphous layer, a relationship between the standard ion implantation energy and the thickness of the standard amorphous layer is established, which is recorded as a standard relationship;

[0015] In the step of judging whether the ion implantation energy is abnormal according to the thickness of the amorphous layer, judging whether the ion implantation energy is abnormal is based on the standard relationship and the thickness of the amorphous layer.

[0016] In some embodiments, in the step of performing ion implantation on the semiconductor substrate, ion implantation is performed with two different ion implantation energies to form the two amorphous layers;

[0017] The step of judging whether the ion implantation energy is abnormal according to the thickness of the amorphous layer comprises: obtaining a change value of the thickness of the amorphous layer under a unit ion implantation energy according to the two thicknesses of the amorphous layer and the two ion implantation energies, and recording it as a change value to be measured;

[0018] Determine whether the measured change value is within a set range, and the set range is obtained by the following steps:

[0019] According to the thickness of the standard amorphous layer obtained under any two of the standard ion implantation energies, a change value of the thickness of the standard amorphous layer under a unit standard ion implantation energy is obtained, which is recorded as a standard change value;

[0020] The setting range is obtained according to the maximum value and the minimum value of the standard variation value.

[0021] In some of the embodiments, in the step of measuring the thickness of the amorphous layer, the thickness of the amorphous layer is measured using a transmission electron microscope and an ellipsometer, respectively, and the ellipsometer is calibrated according to the thickness measured by the transmission electron microscope.

[0022] In some embodiments, the ion implantation dose is 5E14atoms / cm 2 ~1E16atoms / cm 2 The energy of the ion implantation is 1KeV to 60KeV.

[0023] In some embodiments, during the ion implantation process, a neutral gas is used as an ion source.

[0024] In some of the embodiments, the method further includes: performing rapid thermal annealing on the semiconductor substrate to eliminate the amorphous layer, wherein the temperature of the rapid thermal annealing is 900° C. to 1050° C., and the annealing time is at least 1 minute.

[0025] In some of the embodiments, before the step of performing ion implantation on the semiconductor substrate, the method further includes: cleaning the semiconductor substrate.

[0026] In some embodiments, the semiconductor substrate is cleaned with a hydrofluoric acid aqueous solution, an SC1 solution, and an SC2 solution in sequence.

[0027] In some embodiments, the semiconductor substrate includes a silicon substrate.

[0028] A system for monitoring ion implantation energy, used for monitoring whether the ion implantation energy is abnormal, comprising:

[0029] Ion implantation equipment for implanting ions into a semiconductor substrate to form an amorphous layer; and

[0030] A thickness measuring device is used to measure the thickness of the amorphous layer.

[0031] In some of these embodiments, the thickness measurement equipment includes an ellipsometer and optionally a transmission electron microscope.

[0032] In some of the embodiments, the system for monitoring ion implantation energy further includes at least one of a cleaning device and an annealing device, wherein the cleaning device is used to clean the semiconductor substrate, and the annealing device is used to anneal the semiconductor substrate.

[0033] The inventors discovered in experiments that when the ion implantation energy fluctuates, the thickness of the amorphous layer will change significantly, and the ion implantation dose will affect the ion concentration but will not affect the thickness of the amorphous layer. Therefore, by implanting ions into a semiconductor substrate with a crystalline structure, high-energy ions bombard the surface of the semiconductor substrate to damage the lattice structure, and an amorphous layer is formed in the semiconductor substrate. The thickness of the amorphous layer is then measured, and the ion implantation energy is monitored based on the thickness of the amorphous layer. This method can effectively monitor the implantation energy deviation caused by the ion implantation machine, thereby reducing the quality fluctuations caused to the device, and provides a new and feasible method for monitoring ion implantation energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A process flow chart of a method for monitoring ion implantation energy in some embodiments of the present invention;

[0035] Figure 2 At 1E16atoms / cm 2 The relationship between the ion implantation energy and the thickness of the amorphous layer measured by the ellipsometer under the implantation dose condition;

[0036] Figure 3 At 1E16atoms / cm 2 TEM images of the amorphous layer formed under different ion implantation energies under implantation dose conditions. DETAILED DESCRIPTION

[0037] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below in conjunction with the specific embodiments. Preferred embodiments of the present invention are provided in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0039] Unless otherwise specified or there is a contradiction, the terms or phrases used in this invention have the following meanings:

[0040] In the present invention, "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0041] In the description of the present invention, “plurality” means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0042] In the present invention, "at least one" refers to any one, any two, or any two or more of the listed items.

[0043] In the present invention, the percentage concentration involved, unless otherwise specified, refers to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of the component.

[0044] The words "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that may provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0045] When a numerical range is disclosed in the present invention, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed in the present invention should be understood to include any and all subranges included therein.

[0046] In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0047] The terms "including" and "having" and any variations thereof in the embodiments of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or components that are inherent to these processes, methods, products, or devices.

[0048] Reference to "embodiments" in the present invention means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present invention may be combined with other embodiments.

[0049] Traditional methods of monitoring the ion implantation process are all through measuring the block resistance value, but the injection energy deviation will not have a significant change in the block resistance. Currently, there is a lack of an efficient, feasible and low-cost monitoring method for the implantation energy.

[0050] Based on this, the first aspect of the present invention provides a method for effectively monitoring ion implantation energy, see Figure 1 , including the following steps:

[0051] Step S110: cleaning the semiconductor substrate.

[0052] In some embodiments, the semiconductor substrate has a crystalline structure.

[0053] In some embodiments, the semiconductor substrate includes silicon. It is understood that the semiconductor substrate is not limited to silicon, and may also be other commonly used semiconductor substrates, such as germanium, silicon germanium, gallium arsenide, or silicon germanium semiconductor.

[0054] The surface of the semiconductor substrate usually has a natural oxide layer, so the semiconductor substrate needs to be cleaned, specifically, by a wet cleaning method.

[0055] In some embodiments, the semiconductor substrate is silicon, and the steps of cleaning the semiconductor substrate include: first cleaning with dilute hydrofluoric acid (DHF) having a volume ratio of hydrofluoric acid to water of 1:100, then cleaning with SC1 cleaning solution, and finally cleaning with SC2 cleaning solution. Dilute hydrofluoric acid has strong corrosiveness and can effectively remove the natural oxide layer on the surface of silicon, and at the same time, it undergoes redox reaction with the metal elements in the oxide layer to form metal ions and be removed. SC1 is NH 3 ·H 2 O and H 2 O 2 and H 2 O is mixed in a volume ratio of 1:1:5, and the thin layer of silicon atoms on the surface of the silicon wafer is covered with NH 3 ·H 2 O corrodes and peels off, and the granular impurities on the surface of the silicon wafer fall off and enter the cleaning solution, thereby effectively removing the granular impurities. SC2 is HCl and H 2 O 2 and H 2 O is mixed in a volume ratio of 1:1:5. The metal and its compounds on the surface of the silicon wafer undergo redox reactions to form metal ions that enter the cleaning solution, thereby effectively removing metal impurities.

[0056] In a specific example, the cleaning time of dilute hydrofluoric acid (DHF) with a volume ratio of hydrofluoric acid to water of 1:100 is 10 seconds, the cleaning time of SC1 cleaning solution is 5 minutes, and the cleaning time of SC2 cleaning solution is 5 minutes.

[0057] By cleaning the semiconductor substrate in the above manner, the natural oxide layer, surface particles and metal impurities on the surface of the semiconductor substrate can be effectively removed. It is understood that the cleaning method is not limited to this, and can also be other methods commonly used in the art, or adjusted according to different semiconductor substrates.

[0058] Step S120: performing ion implantation on the semiconductor substrate to form an amorphous layer.

[0059] Before ion implantation, the semiconductor substrate is in a crystalline state. After ion implantation, high-energy ions bombard the surface of the semiconductor substrate to damage the lattice structure, thereby forming an amorphous structure in the semiconductor substrate to obtain an amorphous layer.

[0060] In some embodiments, ion implantation is performed using a neutral gas as an ion source. Specifically, the neutral gas includes but is not limited to Ar, N 2 Neutral gases such as ions. Using neutral gases as ion sources has the advantages of high safety and low cost. It is understood that the ion source for ion implantation is not limited to neutral gases, but can also be other ion sources commonly used in the art.

[0061] In some embodiments, the ion implantation dose is 5E14 atoms / cm 2 ~1E16atoms / cm 2 For example, the implantation dose may be, but is not limited to, 5E14 atoms / cm 2 、6E14atoms / cm 2 、8E14atoms / cm 2 、1E15atoms / cm 2 、2E15atoms / cm 2 、4E15atoms / cm 2 、6E15atoms / cm 2 、8E15atoms / cm 2 、1E16atoms / cm 2 Or a range consisting of any two of these values. If the ion implantation dose is too small, an amorphous layer cannot be formed. If the ion implantation dose is large, the semiconductor substrate has insufficient tolerance, and the implantation time is long, which is not conducive to monitoring. Therefore, in this embodiment, preferably, the ion implantation dose is 5E14atoms / cm 2 ~1E16atoms / cm 2 .

[0062] In some embodiments, the ion implantation energy is 1 KeV to 60 KeV. For example, the ion implantation energy may be, but is not limited to, 1 KeV, 5 KeV, 10 KeV, 15 KeV, 20 KeV, 25 KeV, 30 KeV, 35 KeV, 40 KeV, 45 KeV, 50 KeV, 55 KeV, 60 KeV, or a range consisting of any two of these values.

[0063] Optionally, a high current ion implanter is used to perform ion implantation on the semiconductor substrate.

[0064] Step S130: measuring the thickness of the amorphous layer.

[0065] In some embodiments, the thickness of the amorphous layer is measured using an ellipsometer. Since the refractive index of the amorphous layer and the semiconductor substrate without ion implantation is different, an ellipsometer can be used to measure the thickness of the amorphous layer. The ellipsometer can measure very thin films with high accuracy.

[0066] In some embodiments, the thickness of the amorphous layer is measured using a TEM (transmission electron microscope) and an ellipsometer, respectively, and the ellipsometer is calibrated for thickness measurement based on the thickness measured by the TEM. Through the above method, the thickness measurement accuracy of the ellipsometer is guaranteed, and the ellipsometer can be directly used for measurement in subsequent measurement processes.

[0067] Step S140: judging whether the ion implantation energy is abnormal according to the thickness of the amorphous layer.

[0068] The inventors discovered in experiments that the doping depth is determined by the energy and mass of the injected impurity ions. When the ion injection energy fluctuates, the thickness of the amorphous layer will change significantly, while the ion injection dose will affect the ion concentration but will not affect the thickness of the amorphous layer. Therefore, in this embodiment, the ion injection energy is monitored by the thickness of the amorphous layer.

[0069] In some embodiments, it also includes:

[0070] obtaining a plurality of standard semiconductor substrates;

[0071] Ion implantation is performed on a standard semiconductor substrate at different standard ion implantation energies to obtain a plurality of standard amorphous layers;

[0072] Measuring the thickness of each standard amorphous layer;

[0073] According to the standard ion implantation energy and the standard thickness of the amorphous layer, a relationship between the standard ion implantation energy and the standard thickness of the amorphous layer is established, which is recorded as a standard relationship.

[0074] In step S140 , it is determined whether the ion implantation energy is abnormal based on the standard relationship and the thickness of the amorphous layer.

[0075] In some embodiments, there are five standard ion implantation energies, which are 20KeV, 30KeV, 40KeV, 50KeV, and 60KeV, respectively. It can be understood that the number and value of the standard ion implantation energies are not limited to the above values, and can also be adjusted according to actual conditions and the ion implantation energy range to be monitored.

[0076] It can be understood that the standard semiconductor substrate also needs to be cleaned before ion implantation to remove the natural oxide layer and surface particles, metal impurities, etc. on the surface. The specific cleaning method is the same as before and will not be repeated here.

[0077] In addition, during the ion implantation process of the standard semiconductor substrate, other conditions except the ion implantation energy are the same as those of the semiconductor substrate to be tested. And the ion implantation difference between the multiple standard semiconductor substrates is only the ion implantation energy. Through the above settings, the measurement error is reduced and the accuracy is improved.

[0078] Further preferably, in the step of performing ion implantation on the semiconductor substrate, ion implantation is performed with two different ion implantation energies to form two amorphous layers;

[0079] The step of monitoring the ion implantation energy according to the thickness of the amorphous layer comprises: obtaining a change value of the thickness of the amorphous layer under a unit implantation energy according to the thickness of the two amorphous layers and the two ion implantation energies, and recording it as a change value to be measured;

[0080] Determine whether the measured change value is within the set range. The set range is obtained by the following steps:

[0081] According to the thickness of the standard amorphous layer obtained under any two standard ion implantation energies, a change value of the thickness of the standard amorphous layer under a unit standard ion implantation energy is obtained, which is recorded as a standard change value;

[0082] The setting range is obtained based on the maximum and minimum values ​​of the standard variation value.

[0083] Since the ion implantation energy and the thickness of the amorphous layer are not in a strict linear relationship, there will be a certain error in judging whether the amorphous layer thickness obtained by only one ion implantation is within the standard relationship. Therefore, in this embodiment, preferably, two ion implantations are performed on the semiconductor substrate to be tested, and the change values ​​of the amorphous layer thickness under the two ion implantation energies are obtained. The set range is determined according to the standard change value. If the change value to be tested is within the set range, the ion implantation energy is stable. If the change value to be tested is not within the set range, the ion implantation energy fluctuates and needs to be stopped for inspection.

[0084] Step S150: annealing the semiconductor substrate to remove the amorphous layer.

[0085] In some embodiments, in the step of annealing the semiconductor substrate, rapid thermal annealing is used at a temperature of 900°C to 1050°C. Time>1min. For example, the annealing temperature may be, but is not limited to, 900°C, 920°C, 950°C, 980°C, 1000°C, 1020°C, 1050°C or a range consisting of any two of these values. Through rapid thermal annealing, the purpose of eliminating ion implantation losses and reusing semiconductor substrates is achieved. It can be understood that in the actual process, general annealing equipment can also be used, but the use of rapid thermal annealing can save time and single-chip costs compared to ordinary annealing. Therefore, in this embodiment, rapid thermal annealing is preferably used.

[0086] The above method for monitoring ion implantation energy has at least the following advantages:

[0087] The above method for monitoring ion implantation energy first cleans the surface of the semiconductor substrate to remove the natural oxide layer, surface particles and metal impurities on the surface, and then performs ion implantation. Under certain implantation energy and implantation dose conditions, an amorphous layer of a certain depth is formed, and then the depth of the amorphous layer is measured by an ellipsometer. According to the measured data, it is possible to analyze whether the implantation energy is within the target value range. This method can effectively monitor whether the implantation energy of ion implantation deviates, and it is low in cost and high in efficiency. In addition, the completed semiconductor substrate is subjected to rapid thermal annealing under certain conditions to eliminate the amorphous layer, thereby achieving the purpose of reusing the semiconductor substrate.

[0088] A second aspect of the present invention provides a system for monitoring ion implantation energy, which is used to monitor whether the ion implantation energy is abnormal, and comprises:

[0089] Ion implantation equipment, used for implanting ions into a semiconductor substrate to form an amorphous layer;

[0090] Thickness measuring equipment for measuring the thickness of amorphous layers.

[0091] In some embodiments, the semiconductor substrate has a crystalline structure.

[0092] In some embodiments, the semiconductor substrate includes silicon. It is understood that the semiconductor substrate is not limited to silicon, and may also be other commonly used semiconductor substrates, such as germanium, silicon germanium, gallium arsenide, or silicon germanium semiconductor.

[0093] In some embodiments, the ion implantation equipment may be commonly used in the art, for example, the ion implantation equipment may be, but is not limited to, a high current ion implantation machine. Specifically, the implantation energy of the ion implantation equipment is 1KeV to 60KeV, and the implantation dose is 5E14atoms / cm 2 ~1E16atoms / cm 2 .

[0094] In some embodiments, the thickness measuring device includes an ellipsometer. Further, the thickness measuring device also includes a transmission electron microscope. The ellipsometer is calibrated using the transmission electron microscope to improve the accuracy of the ellipsometer in measuring the thickness of the amorphous layer.

[0095] In some embodiments, the system for monitoring ion implantation energy further includes an annealing device for annealing the semiconductor substrate. In one embodiment, the annealing device may be, but is not limited to, a rapid thermal annealing machine. By performing rapid thermal annealing on the semiconductor substrate, ion implantation loss is eliminated, so that the semiconductor substrate can be reused.

[0096] In some embodiments, the system for monitoring ion implantation energy further includes a cleaning device for cleaning the semiconductor substrate. The surface of the semiconductor substrate usually has a natural oxide layer, metal impurities, surface particles, etc., so the semiconductor substrate needs to be cleaned.

[0097] The above-mentioned system for monitoring ion implantation energy implants ions into a semiconductor substrate through an ion implantation device to form an amorphous layer, and measures the thickness of the formed amorphous layer through a thickness measuring device. According to the thickness of the amorphous layer, it is possible to effectively monitor whether the ion implantation energy deviates.

[0098] In order to make the purpose and advantages of the present invention clearer, the method for monitoring ion implantation energy of the present invention and its effect are further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and shall not be used to limit the present invention. The following embodiments do not include other components except inevitable impurities unless otherwise specified. The drugs and instruments used in the embodiments are conventionally selected in the art unless otherwise specified. The experimental methods for which specific conditions are not specified in the embodiments are implemented according to conventional conditions, such as the conditions described in the literature and books or the methods recommended by the manufacturer.

[0099] Example 1

[0100] This embodiment provides a method for obtaining the relationship between the thickness of an amorphous layer and the ion implantation energy, comprising the following steps:

[0101] (1) Provide five substrates, the material of the substrates is 12-inch silicon wafers.

[0102] (2) performing wet surface cleaning on the substrate, the steps comprising: first, soaking and cleaning with dilute hydrofluoric acid having a volume ratio of hydrofluoric acid to water of 1:100 for 10 seconds, then cleaning with SC1 cleaning solution for 5 minutes, and finally cleaning with SC2 cleaning solution for 5 minutes to obtain a cleaned substrate.

[0103] (3) Ion implantation is performed on the cleaned substrate using an ion implanter. Ar gas is used as the ion source and the implantation dose is 1E16 atoms / cm 2 The energies are 20KeV, 30KeV, 40KeV, 50KeV and 60KeV respectively.

[0104] (4) The thickness of the amorphous layer was measured using a calibrated ellipsometer, and the thickness difference of the amorphous layer under the ion implantation energy difference was obtained. The results are shown in Table 1 below.

[0105] (5) According to the thickness of the amorphous layer and the ion implantation energy, the following is obtained: Figure 2 The shown value is 1E16atoms / cm 2The relationship between the implantation energy and the amorphous layer thickness measured by the ellipsometer under the implantation dose condition. It can be seen from the figure that the implantation energy and the amorphous layer depth measured by the ellipsometer have a good linear relationship.

[0106] At the same time, TEM was used to measure the thickness of the amorphous layer obtained under the above different ion implantation energies, and the results were as follows: Figure 3 As shown. Figure 3 In the formula, Ar / 60K / 1E16 means that the ion source is argon, the ion implantation energy is 60KeV, and the ion implantation dose is 1E16atoms / cm 2 , other Ar / 50K / 1E16, Ar / 40K / 1E16, Ar / 30K / 1E16, Ar / 20K / 1E16 have similar meanings, the difference is the ion implantation energy. 20.52nm means that the thickness of the amorphous layer obtained under the Ar / 60K / 1E16 process condition is 20.52nm thicker than that under the Ar / 50K / 1E16 process condition, which is basically consistent with the thickness difference measured by the ellipsometer. Similarly, 19.62nm means that the thickness of the amorphous layer obtained under the Ar / 50K / 1E16 process is 19.62nm thicker than that under the Ar / 40K / 1E16 process, 20.18nm means that the thickness of the amorphous layer obtained under the Ar / 40K / 1E16 process is 20.18nm thicker than that under the Ar / 30K / 1E16 process, and 19.74nm means that the thickness of the amorphous layer obtained under the Ar / 30K / 1E16 process is 19.74nm thicker than that under the Ar / 20K / 1E16 process. Figure 3 It can be seen that the thickness difference of the amorphous layer under different conditions measured by TEM is consistent with the data measured by the ellipsometer. It can be shown that the thickness of the amorphous layer can be measured by the ellipsometer.

[0107] Table 1 Thickness difference of amorphous layer under different ion implantation energies measured by ellipsometer

[0108] Two ion implantation energies / KeV Amorphous layer thickness difference / A 30、20 207.6 40、30 199.9 50、40 198.82 60、50 191.17

[0109] In addition, in Example 1, tests on the thickness of the amorphous layer under multiple other injection energies were carried out to obtain the change value of the thickness of the amorphous layer under unit ion implantation energy, that is, the sensitivity, based on multiple implantation energies and amorphous layer thicknesses. The sensitivity is about 15A~25A / 1KeV, that is, when the implantation energy changes by 1KeV, the thickness of the amorphous layer changes by 15A~25A. The energy of ion implantation can be effectively monitored by the thickness of the amorphous layer.

[0110] Example 2

[0111] This embodiment provides a method for monitoring ion implantation energy, comprising the following steps:

[0112] (1) Provide two substrates, the substrate material is 12-inch silicon wafer.

[0113] (2) performing wet surface cleaning on the substrate, the steps comprising: first, soaking and cleaning with dilute hydrofluoric acid having a volume ratio of hydrofluoric acid to water of 1:100 for 10 seconds, then cleaning with SC1 cleaning solution for 5 minutes, and finally cleaning with SC2 cleaning solution for 5 minutes to obtain a cleaned substrate.

[0114] (3) Ion implantation is performed on the cleaned substrate using an ion implanter. Ar gas is used as the ion source and the implantation dose is 1E16 atoms / cm 2 , energies are 55KeV and 60KeV respectively.

[0115] (4) The thickness of the amorphous layer was measured using a calibrated ellipsometer. The thickness difference of the amorphous layer under ion implantation energies of 55 KeV and 60 KeV was 95.58 A. The thickness change of the amorphous layer under unit ion implantation energy was 19.116 A / KeV, which was within the sensitivity range measured in the above Example 1 and met the expected difference.

[0116] (5) Performing rapid thermal annealing on the substrate to eliminate the amorphous layer and reuse the substrate.

[0117] Example 3

[0118] This embodiment provides a method for monitoring ion implantation energy, comprising the following steps:

[0119] (1) Provide two substrates, the substrate material is 12-inch silicon wafer.

[0120] (2) performing wet surface cleaning on the substrate, the steps comprising: first, soaking and cleaning with dilute hydrofluoric acid having a volume ratio of hydrofluoric acid to water of 1:100 for 10 seconds, then cleaning with SC1 cleaning solution for 5 minutes, and finally cleaning with SC2 cleaning solution for 5 minutes to obtain a cleaned substrate.

[0121] (3) Ion implantation is performed on the cleaned substrate using an ion implanter. Ar gas is used as the ion source. The implantation dose is 1E16 atoms / cm2 and the energies are 45KeV and 50KeV respectively.

[0122] (4) The thickness of the amorphous layer was measured using a calibrated ellipsometer. The thickness difference of the amorphous layer under ion implantation energies of 45 KeV and 50 KeV was 94.4 A. The thickness change of the amorphous layer under unit ion implantation energy was 18.88 A / KeV, which was within the sensitivity range measured in the above Example 1 and met the expected difference.

[0123] (5) Performing rapid thermal annealing on the substrate to eliminate the amorphous layer and reuse the substrate.

[0124] Example 4

[0125] This embodiment provides a method for monitoring ion implantation energy, comprising the following steps:

[0126] (1) Provide two substrates, the substrate material is 12-inch silicon wafer.

[0127] (2) performing wet surface cleaning on the substrate, the steps comprising: first, soaking and cleaning with dilute hydrofluoric acid having a volume ratio of hydrofluoric acid to water of 1:100 for 10 seconds, then cleaning with SC1 cleaning solution for 5 minutes, and finally cleaning with SC2 cleaning solution for 5 minutes to obtain a cleaned substrate.

[0128] (3) Ion implantation is performed on the cleaned substrate using an ion implanter. Ar gas is used as the ion source and the implantation dose is 1E16 atoms / cm 2 , the energies are 30KeV and 35KeV respectively.

[0129] (4) The thickness of the amorphous layer was measured using a calibrated ellipsometer. The difference in thickness of the amorphous layer at ion implantation energies of 30 KeV and 35 KeV was 113.8 A. The thickness change of the amorphous layer at unit ion implantation energy was 22.76 A / KeV, which was within the sensitivity range measured in Example 1 above and was consistent with the expected difference.

[0130] (5) Rapid thermal annealing is performed on the substrate to remove the amorphous layer and reuse it.

[0131] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0132] The above-described embodiments only express several implementation methods of the present invention, which is convenient for understanding the technical solutions of the present invention in detail, but cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present invention are all within the protection scope of the claims attached to the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the contents of the attached claims, and the description and drawings can be used to interpret the contents of the claims.

Claims

1. A method for monitoring ion implantation energy, characterized in that: The steps include: Performing ion implantation on a semiconductor substrate to form an amorphous layer, wherein the semiconductor substrate has a crystalline structure; measuring the thickness of the amorphous layer; Whether the ion implantation energy is abnormal is determined according to the thickness of the amorphous layer.

2. The method for monitoring ion implantation energy according to claim 1, characterized in that: Also includes: obtaining a plurality of standard semiconductor substrates; Performing ion implantation on the standard semiconductor substrate with different standard ion implantation energies to obtain a plurality of standard amorphous layers; measuring the thickness of each of the standard amorphous layers; According to the standard ion implantation energy and the thickness of the standard amorphous layer, a relationship between the standard ion implantation energy and the thickness of the standard amorphous layer is established, which is recorded as a standard relationship; In the step of judging whether the ion implantation energy is abnormal according to the thickness of the amorphous layer, judging whether the ion implantation energy is abnormal is based on the standard relationship and the thickness of the amorphous layer.

3. The method for monitoring ion implantation energy according to claim 2, characterized in that: In the step of performing ion implantation on the semiconductor substrate, ion implantation is performed with two different ion implantation energies to form two amorphous layers; The step of judging whether the ion implantation energy is abnormal according to the thickness of the amorphous layer comprises: obtaining a change value of the thickness of the amorphous layer under a unit ion implantation energy according to the two thicknesses of the amorphous layer and the two ion implantation energies, and recording it as a change value to be measured; Determine whether the measured change value is within a set range, and the set range is obtained by the following steps: According to the thickness of the standard amorphous layer obtained under any two of the standard ion implantation energies, a change value of the thickness of the standard amorphous layer under a unit standard ion implantation energy is obtained, which is recorded as a standard change value; The setting range is obtained according to the maximum value and the minimum value of the standard variation value.

4. The method for monitoring ion implantation energy according to any one of claims 1 to 3, characterized in that: In the step of measuring the thickness of the amorphous layer, the thickness of the amorphous layer is measured using a transmission electron microscope and an ellipsometer respectively, and the ellipsometer is calibrated according to the thickness measured by the transmission electron microscope.

5. The method for monitoring ion implantation energy according to any one of claims 1 to 3, characterized in that: The step of ion implantation into the semiconductor substrate satisfies any one or more of the following conditions: (1) The ion implantation dose is 5E14 atoms / cm 2 ~1E16atoms / cm 2 , the energy of the ion implantation is 1KeV to 60KeV; (2) During the ion implantation process, a neutral gas is used as an ion source.

6. The method for monitoring ion implantation energy according to claim 1, characterized in that: Also includes: The semiconductor substrate is subjected to rapid thermal annealing to eliminate the amorphous layer. The temperature of the rapid thermal annealing is 900° C. to 1050° C., and the annealing time is at least 1 minute.

7. The method for monitoring ion implantation energy according to claim 1, characterized in that: Before the step of performing ion implantation on the semiconductor substrate, the method further includes: cleaning the semiconductor substrate; Optionally, the semiconductor substrate is cleaned with a hydrofluoric acid aqueous solution, an SC1 solution and an SC2 solution in sequence.

8. The method for monitoring ion implantation energy according to claim 1, characterized in that: The semiconductor substrate includes a silicon substrate.

9. A system for monitoring ion implantation energy, characterized in that: Used to monitor whether the ion implantation energy is abnormal, including: Ion implantation equipment for implanting ions into a semiconductor substrate to form an amorphous layer; and A thickness measuring device is used to measure the thickness of the amorphous layer.

10. The system for monitoring ion implantation energy according to claim 9, characterized in that: The thickness measurement equipment comprises an ellipsometer and optionally a transmission electron microscope; and / or, The system for monitoring ion implantation energy further includes at least one of a cleaning device and an annealing device, wherein the cleaning device is used to clean the semiconductor substrate, and the annealing device is used to anneal the semiconductor substrate.

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