Dielectric layer etching method and etching equipment
By alternately setting the main dielectric sub-layer and the secondary dielectric sub-layer in the dielectric layer, the reflectance changes are monitored and the etching stop timing is accurately controlled, the problem of inaccurate position in the dielectric layer etching is solved, and the formation of multi-stage step-like grooves is achieved, meeting the electrode design needs in special scenarios.
Patent Information
- Application Number
- CN202510571478.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-06
- Publication Date
- 2025-09-05
AI Technical Summary
In prior art, in dielectric layer etching, it is difficult to accurately control the etching position, especially in dielectric layers of different materials, especially ultra-thin dielectric layers, which cannot accurately ensure the etching depth, and it is difficult to form multi-stage step-like grooves to meet the needs of special scenarios.
The main dielectric sub-layer and sub-dielectric sub-layer are arranged alternately in multiple periods. By monitoring the reflectivity change during the etching process, the etching stop time is controlled, and the multi-stage step-like groove is formed, and the etching position is accurately controlled using an optical detector and control module.
It realizes precise control of the etching position of the dielectric layer, can meet the needs of special scenarios, form multi-stage step-like grooves, and meet the electrode design needs in transistors and other scenarios.
Smart Images
Figure CN120600628A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of light-emitting devices, and in particular to a dielectric layer etching method and etching equipment. Background Art
[0002] Dielectric layers are widely used in semiconductor devices. In semiconductor technology, a process generally involves etching grooves in the dielectric layer and then disposing a metal layer in the grooves.
[0003] The related art provides a dielectric layer etching method, which sets a time and stops etching when the set time is reached.
[0004] Controlling the etching time to determine the stop position is not accurate enough, as different dielectric layers have different etching rates. Furthermore, this etching method can only form trapezoidal grooves, making it difficult to meet the needs of specific scenarios. Summary of the Invention
[0005] The embodiments of the present disclosure provide a dielectric layer etching method and etching equipment, which can ensure accurate etching position and meet the needs of special scenarios. The technical solution is as follows:
[0006] In one aspect, a dielectric layer etching method is provided, the method comprising:
[0007] Manufacturing a dielectric layer, wherein the dielectric layer comprises a plurality of main dielectric sublayers and auxiliary dielectric sublayers alternately arranged in a periodic manner, wherein the main dielectric sublayers and the auxiliary dielectric sublayers have different refractive indices;
[0008] performing a first etching on the dielectric layer to form a first groove;
[0009] performing a second etching on the dielectric layer in the first groove;
[0010] The above etching process is repeated to form multi-step-shaped grooves; during each etching process, the change in the reflectivity of the dielectric layer at the etching position is monitored, and the etching stop timing is controlled based on the change in the reflectivity.
[0011] Optionally, in the multi-stepped groove, the depth of each step is equal to the sum of the thicknesses of the main dielectric sublayer and the auxiliary dielectric sublayer in one period;
[0012] Controlling the stopping timing of the etching based on the change of the reflectivity includes:
[0013] When the reflectivity changes suddenly twice in succession, the etching is controlled to stop.
[0014] Optionally, in the multi-step stepped groove, the depth of each step is equal to the sum of the thicknesses of the main dielectric sublayer and the auxiliary dielectric sublayer in N periods, where N is a positive integer greater than 1;
[0015] Controlling the stopping timing of the etching based on the change of the reflectivity includes:
[0016] When the reflectivity changes suddenly 2N times continuously, the etching is controlled to stop.
[0017] Optionally, controlling the stopping timing of the etching based on the change in the reflectivity further includes:
[0018] calculating an etching rate based on the reflectivity;
[0019] The etching stopping timing is controlled based on the etching speed and the number of consecutive mutations of the reflectivity.
[0020] Optionally, the refractive index of the primary dielectric sublayer is greater than 1.2 times the refractive index of the secondary dielectric sublayer.
[0021] Optionally, the thickness of the main dielectric sublayer or the auxiliary dielectric sublayer in each period is not less than 5FR;
[0022] F is the sampling interval of the optical detector for monitoring the change in the reflectivity of the dielectric layer at the etching position;
[0023] R is the etching rate of the main dielectric sublayer or the auxiliary dielectric sublayer.
[0024] On the other hand, an etching device is provided, comprising: a reaction chamber, a spectroscope, a laser, an optical detector, and a control module;
[0025] The spectroscope is located between the reaction chamber and the optical detector and arranged in a straight line, and the laser is located on the side of the spectroscope;
[0026] The laser is used to generate a detection laser, and the detection laser is irradiated onto the dielectric layer in the reaction chamber through the spectroscope, wherein the dielectric layer includes a plurality of main dielectric sublayers and auxiliary dielectric sublayers arranged alternately in a periodic manner, and the main dielectric sublayers and the auxiliary dielectric sublayers have different refractive indices;
[0027] The optical detector is used to receive the reflected laser light generated by the dielectric layer based on the detection laser light;
[0028] The control module is electrically connected to the laser and the optical detector, and is used to control the etcher in the reaction chamber to perform a first etching on the dielectric layer to form a first groove; perform a second etching on the dielectric layer in the first groove; repeat the above etching process to form multi-step grooves; during each etching process, sample the reflected laser through the optical detector, monitor the change in the reflectivity of the dielectric layer at the etching position, and control the stopping time of etching based on the change in the reflectivity.
[0029] Optionally, the wavelength of the detection laser generated by the laser is 400-900 nm.
[0030] Optionally, in the multi-stepped groove, the depth of each step is equal to the sum of the thicknesses of the main dielectric sublayer and the auxiliary dielectric sublayer in one period;
[0031] The control module is used to control the etching to stop when the reflectivity changes suddenly twice in succession.
[0032] Optionally, in the multi-step stepped groove, the depth of each step is equal to the sum of the thicknesses of the main dielectric sublayer and the auxiliary dielectric sublayer in N periods, where N is a positive integer greater than 1;
[0033] The control module is used to control the etching to stop when the reflectivity changes suddenly 2N times continuously.
[0034] The technical solutions provided by the embodiments of the present disclosure have the following beneficial effects:
[0035] In the disclosed embodiment, the dielectric layer is formed by stacking multiple periods of main dielectric sublayers and auxiliary dielectric sublayers, and the main dielectric sublayers and the auxiliary dielectric sublayers have different refractive indices. This dielectric layer design can detect a sudden change in the reflectivity of the dielectric layer at the interface between the main and auxiliary dielectric layers during the etching process. The change in reflectivity can determine the timing of stopping etching and ensure accurate etching position. At the same time, because the dielectric layer is composed of multiple periods, a multi-level stepped groove can be formed by repeating the above etching process. The metal layer provided in the multi-level stepped groove can act as a field plate, thereby meeting the electrode design requirements in scenarios such as transistors. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.
[0037] Figure 1 This is a flow chart of a dielectric layer etching method provided by an embodiment of the present disclosure;
[0038] Figure 2 This is a flow chart of a dielectric layer etching method provided by an embodiment of the present disclosure;
[0039] Figure 3 is a graph showing the reflectivity corresponding to the auxiliary medium sub-layers with different refractive indices provided by the embodiment of the present disclosure;
[0040] Figure 4 is a structural diagram of a dielectric layer provided by an embodiment of the present disclosure;
[0041] Figure 5 is a graph of laser reflectivity at different wavelengths provided by an embodiment of the present disclosure;
[0042] Figure 6 is a graph of laser reflectivity at a laser wavelength of 900 nm provided by an embodiment of the present disclosure;
[0043] Figure 7 It is a structural schematic diagram of an etching device provided in an embodiment of the present disclosure.
[0044] The reference numerals are as follows:
[0045] 100: dielectric layer;
[0046] 101: main medium sublayer;
[0047] 102: secondary dielectric sublayer;
[0048] 1001: multi-stepped groove;
[0049] 200: substrate;
[0050] 300: reaction chamber;
[0051] 301: spectroscope;
[0052] 302: Laser;
[0053] 303: Optical detector;
[0054] 304: Control module. DETAILED DESCRIPTION
[0055] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.
[0056] In semiconductor processing, a large number of dielectric layer etching requirements are involved. During the etching process, etching often needs to be stopped at a certain position to meet the requirements of the device process. There are generally two types of etching cut-off methods in related technologies. One is to use a time mode, that is, to determine the etching rate through preliminary experiments, and then to determine the etching stop by calculating the time. However, this control method is greatly affected by the fluctuation of the etching rate and has high requirements for the uniformity of the etching rate. The other is endpoint detection technology, which often relies on the optical / mass spectrometry signal of the etching by-products. However, when etching needs to stop in the middle of the dielectric layer (not at the interface), there is a lack of effective detection marks. Especially for the middle (non-interface) stop when etching ultra-thin dielectric layers (<100nm), the two existing technologies cannot accurately guarantee the etching depth: the time mode cannot guarantee the consistency of the etching rate, especially at high etching rates (low thickness); endpoint technology optical mass spectrometry cannot play a role.
[0057] Figure 1 This is a flow chart of a dielectric layer etching method provided by an embodiment of the present disclosure. Figure 1 , the method steps include:
[0058] S11 . Manufacturing a dielectric layer 100 . The dielectric layer 100 includes a plurality of main dielectric sublayers 101 and auxiliary dielectric sublayers 102 that are alternately arranged in a periodic manner. The main dielectric sublayers 101 and the auxiliary dielectric sublayers 102 have different refractive indices.
[0059] Among them, the main dielectric sublayer 101 and the auxiliary dielectric sublayer 102 can be transparent insulating materials with similar properties, and the refractive indices of the main dielectric sublayer 101 and the auxiliary dielectric sublayer 102 are different. For example, the main dielectric sublayer 101 can be a SiN layer, and the auxiliary dielectric sublayer 102 can be a SiO2 layer.
[0060] S12 , performing a first etching on the dielectric layer 100 to form a first groove.
[0061] S13 , performing a second etching on the dielectric layer 100 in the first groove.
[0062] S14, repeating the above etching process to form a multi-step groove 1001; during each etching process, monitoring the change in the reflectivity of the dielectric layer 100 at the etching position, and controlling the etching stop timing based on the change in the reflectivity.
[0063] The etching position refers to the position where the multi-step-shaped groove is formed, such as the center of the multi-step-shaped groove.
[0064] That is, the process of S13 is repeated to form a second groove in the first groove by etching for the second time, and then a third groove is formed in the second groove by etching for the third time, and so on. After the above steps, the first groove, the second groove, the third groove, etc. together form a multi-level stepped groove 1001.
[0065] In the disclosed embodiment, the dielectric layer is formed by stacking multiple periods of main dielectric sublayers and auxiliary dielectric sublayers, and the main dielectric sublayers and the auxiliary dielectric sublayers have different refractive indices. This dielectric layer design can detect a sudden change in the reflectivity of the dielectric layer at the interface between the main and auxiliary dielectric layers during the etching process. The change in reflectivity can determine the timing of stopping etching and ensure accurate etching position. At the same time, because the dielectric layer is composed of multiple periods, a multi-level stepped groove can be formed by repeating the above etching process. The metal layer provided in the multi-level stepped groove can act as a field plate, thereby meeting the electrode design requirements in scenarios such as transistors.
[0066] Figure 2 This is a flow chart of a dielectric layer etching method provided by an embodiment of the present disclosure. Figure 2 , the method steps include:
[0067] S21 , determining the main dielectric sublayer 101 and the auxiliary dielectric sublayer 102 of the dielectric layer 100 .
[0068] For example, the main dielectric sub-layer 101 is usually made of dielectric layer material that is originally required to be used.
[0069] In order to use the method of the embodiment of the present disclosure, the original main dielectric material layer is replaced with a superlattice structure of multiple periods of main dielectric sub-layers 101 and auxiliary dielectric sub-layers 102 .
[0070] Therefore, the material of the secondary dielectric sub-layer 102 needs to be similar in properties to the material of the primary dielectric sub-layer 101 , for example, different compounds of the same element, such as oxide and nitride.
[0071] In the embodiment of the present disclosure, under the same etching conditions, the etching selectivity ratio of the main dielectric sub-layer 101 and the auxiliary dielectric sub-layer 102 is less than 1.2.
[0072] Etching selectivity refers to the ratio of the relative etching rates of one material to another under the same etching conditions.
[0073] In this implementation, the smaller the etching selectivity ratio of the main dielectric sublayer and the auxiliary dielectric sublayer, the closer the etching rates are, so that the etching depth can be controlled more accurately to avoid over-etching or under-etching.
[0074] In other embodiments, the etching selectivity ratio between the main dielectric sub-layer 101 and the secondary dielectric sub-layer 102 may be equal to or greater than 1.2.
[0075] In the embodiment of the present disclosure, both the main dielectric sub-layer 101 and the auxiliary dielectric sub-layer 102 are film layers formed of the same material.
[0076] In this implementation, using one material can better control the refractive index and etching selectivity of the main dielectric sublayer and the auxiliary dielectric sublayer, which is beneficial to the cutoff of the etching position.
[0077] In other embodiments, the main dielectric sub-layer 101 and the secondary dielectric sub-layer 102 may also be film layers formed of multiple materials.
[0078] In the embodiment of the present disclosure, the ratio of the refractive index of the primary dielectric sublayer 101 to the refractive index of the secondary dielectric sublayer 102 is greater than 1.2.
[0079] In this implementation, the ratio of the refractive index of the main dielectric sublayer 101 to the refractive index of the auxiliary dielectric sublayer 102 is greater than 1.2, which can ensure that the reflectivity curve changes significantly, facilitate determining the sudden change position of the curve, and make the etching cutoff more accurate.
[0080] Exemplarily, the refractive index of the primary dielectric sublayer 101 is 2, and the refractive index of the secondary dielectric sublayer 102 is 1.45.
[0081] In other embodiments, the refractive index of the primary dielectric sub-layer 101 may also be equal to or less than 1.2 times the refractive index of the secondary dielectric sub-layer 102 .
[0082] For example, the main dielectric sub-layer 101 may be a SiN layer, and the secondary dielectric sub-layer 102 may be a SiO 2 layer.
[0083] S22. Design the number of periods of the main dielectric sublayer 101 and the auxiliary dielectric sublayer 102 in the dielectric layer 100 and the thickness of the main dielectric sublayer 101 and the auxiliary dielectric sublayer 102 within each period.
[0084] During replacement, it is necessary to ensure that the properties of the replaced dielectric layer 100 are similar to those of the original main dielectric material layer.
[0085] For example, a main dielectric material layer with a thickness of A is replaced with a superlattice structure with a thickness of B. The properties of the two before and after the replacement are similar, such as the dielectric constant.
[0086] For example, it is necessary to ensure that the dielectric constant difference is smaller than a threshold, such as smaller than 10%.
[0087] In the embodiment of the present disclosure, the number of periods of the main dielectric sub-layer 101 and the secondary dielectric sub-layer 102 in the dielectric layer 100 is greater than 2.
[0088] In this implementation, the number of periods of the main dielectric sublayer and the auxiliary dielectric sublayer in the dielectric layer is greater than 2, thereby forming a multi-step structure.
[0089] Exemplarily, the number of periods of the main dielectric sub-layer 101 and the secondary dielectric sub-layer 102 in the dielectric layer 100 is three.
[0090] In the embodiment of the present disclosure, the thickness of the main dielectric sublayer 101 or the auxiliary dielectric sublayer 102 in each period is not less than 5FR;
[0091] F is the sampling interval of the optical detector for monitoring the change in the reflectivity of the dielectric layer 100 at the etching position, that is, the time interval between two adjacent samplings;
[0092] R is the etching rate of the main dielectric sub-layer 101 or the auxiliary dielectric sub-layer 102 .
[0093] That is, when calculating the thickness of the main dielectric sublayer 101, R in the formula is the etching rate of the main dielectric sublayer 101. When calculating the thickness of the auxiliary dielectric sublayer 102, R in the formula is the etching rate of the auxiliary dielectric sublayer 102.
[0094] In this implementation, the main dielectric sublayer and the auxiliary dielectric sublayer manufactured with the above-mentioned thickness are thick enough for the optical detector to perform sampling.
[0095] In addition, only the lower limit of the thickness of the main dielectric sublayer 101 and the auxiliary dielectric sublayer 102 is defined here, while the upper limit of the thickness of the main dielectric sublayer 101 and the auxiliary dielectric sublayer 102 can be determined according to the required height of each step of the groove.
[0096] The sum of the thicknesses of the primary dielectric sublayer 101 and the secondary dielectric sublayer 102 can be 1 / N of the step height, where N is a positive integer. That is, the sum of the thicknesses of one or more periods of the primary dielectric sublayer 101 and the secondary dielectric sublayer 102 is equal to the step height. This ensures that etching stops at the interface between the primary dielectric sublayer 101 and the secondary dielectric sublayer 102.
[0097] For example, the thickness of the main dielectric sub-layer 101 in each period is 35 nm, and the thickness of the secondary dielectric sub-layer 102 is 5 nm.
[0098] S23 , inputting the refractive index and thickness parameters of the dielectric layer 100 into the program of the etching equipment to obtain a curve showing how the reflectivity changes with the thickness of the thin film being etched.
[0099] In step S22 , a variety of secondary dielectric sub-layer materials may be selected, and simulation may be performed in step S23 to further select a more suitable secondary dielectric sub-layer material and thickness.
[0100] Figure 3 is a graph showing the reflectivity of the sub-medium layers with different refractive indices provided by the embodiment of the present disclosure. Figure 3 , the graph consists of 2 parts.
[0101] Figure 3 The upper part of the figure is the reflectivity curve of the superlattice structure formed by the main dielectric sublayer and the auxiliary dielectric sublayer. The horizontal axis is the dielectric layer thickness in nm, and the vertical axis is R, which represents the reflectivity.
[0102] The upper part shows the reflectivity curve of the superlattice formed by two auxiliary dielectric sublayers with different reflectivities. n1 is the refractive index of the main dielectric sublayer is 2; n2 is the refractive index of the auxiliary dielectric sublayer, the refractive index of the dotted line n2 is 1.45, and the refractive index of the solid line n2 is 1.9.
[0103] Figure 3 The lower half of the figure shows the reflectivity curve for the superlattice structure formed by the primary and secondary dielectric sublayers. This is also the reflectivity curve for the dielectric layer. The horizontal axis represents the dielectric layer thickness in nanometers, and the vertical axis, dR, represents the reflectivity. The reflectivity represents the difference in reflectivity between two adjacent acquisition points. T represents the number of periods, indicating that the dielectric layer comprises three periods of the superlattice, each 40 nm in length. The thickness of the primary dielectric sublayer, d1, is 35 nm, and the thickness of the secondary dielectric sublayer, d2, is 5 nm.
[0104] The lower part shows the reflection change rate curves after the two auxiliary dielectric sub-layers form superlattice structures with the main dielectric sub-layer.
[0105] Depend on Figure 3 It can be seen that the reflectivity change is more easily detected when the refractive index of the secondary dielectric sublayer is 1.45.
[0106] That is, the reflectivity change curve of the dielectric layer during etching is obtained in advance through simulation, which provides a reference for subsequent actual etching.
[0107] S24 , growing a dielectric layer 100 on the substrate 200 .
[0108] In the embodiment of the present disclosure, low pressure chemical vapor deposition (LPCVD) is used to grow the dielectric layer 100 .
[0109] Figure 4 is a structural diagram of the dielectric layer provided by the embodiment of the present disclosure. Figure 4 The dielectric layer 100 includes a main dielectric sublayer 101 and a secondary dielectric sublayer 102 stacked in sequence.
[0110] The period number of the main dielectric sublayer 101 and the secondary dielectric sublayer 102 is 3.
[0111] The number of periods of the main dielectric sub-layer 101 and the auxiliary dielectric sub-layer 102 being 3 is only an example. In other examples, the number of periods can be set according to the specific thickness of the multi-step groove 1001 to be etched.
[0112] S25 , etching the dielectric layer 100 using an etcher to obtain multi-step grooves 1001 .
[0113] In the embodiment of the present disclosure, an etcher is used to perform plasma etching on the dielectric layer 100 .
[0114] For example, an inductively coupled plasma (ICP) etcher is used for etching.
[0115] In one example, step S25 includes:
[0116] In the first step, a layer of photoresist is formed on the surface of the dielectric layer 100 .
[0117] In the embodiment of the present disclosure, the area of the dielectric layer 100 that needs to be etched is determined, and the photoresist does not cover the laser detection area.
[0118] In the second step, the dielectric layer 100 is etched for the first time to form a first groove.
[0119] Figure 5 is a graph showing the reflectivity of laser beams of different wavelengths provided by the embodiment of the present disclosure. Figure 5 , the graph consists of 2 parts.
[0120] The upper part shows the reflectivity curves of two wavelengths of laser on the dielectric layer, where the horizontal axis is the width of the dielectric layer, in nm; the vertical axis is R, which represents the reflectivity.
[0121] Figure 5 The lower half shows the reflectivity curves for two laser wavelengths on the dielectric layer. The horizontal axis represents the dielectric layer width (nm), and the vertical axis represents the reflectivity. The solid line is the curve for a laser with a wavelength of 900nm, and the dashed line is the curve for a laser with a wavelength of 400nm. T is the number of periods, indicating that the dielectric layer consists of a superlattice with three periods, each 40nm long. The thickness of the main dielectric sublayer d1 is 35nm, and the thickness of the secondary dielectric sublayer d2 is 5nm.
[0122] As can be seen from the figure, the lower the laser wavelength, the easier it is to detect the change in refractive index during the etching process. However, since the etching adopts plasma etching, the wavelength of the plasma will affect the collection of reflectivity and reflectivity conversion rate. The plasma commonly used for etching will affect the laser with a wavelength less than 850nm. Therefore, this embodiment considers using a laser with a wavelength of 900nm.
[0123] During the etching process, the change in the reflectivity of the dielectric layer 100 at the etching position is monitored, and the etching stop timing is controlled based on the change in the reflectivity.
[0124] For example, the reflectivity suddenly changes at 40 nm, and the first etching is stopped at this time; then the second etching is continued, and the reflectivity suddenly changes at 80 nm, and the second etching is stopped at this time.
[0125] Figure 6 is a graph showing the laser reflectivity at a wavelength of 900 nm provided by an embodiment of the present disclosure. Figure 6 , the graph consists of 2 parts.
[0126] Figure 6 The upper part of the figure is the reflectivity curve of the dielectric layer when the wavelength is 900nm. The horizontal axis is the thickness of the dielectric layer in nm, and the vertical axis is R, which represents the reflectivity.
[0127] The upper part shows the reflectivity curve of the dielectric layer at a wavelength of 900 nm. n1 is the refractive index of the primary dielectric sublayer, which is 2; n2 is the refractive index of the secondary dielectric sublayer, which is 1.45.
[0128] Figure 6 The lower half of the figure shows the reflectivity change curve of the dielectric layer at a wavelength of 900nm. The horizontal axis is the dielectric layer thickness in nm, and the vertical axis is dR, which represents the reflectivity change rate. λ is the laser wavelength, indicating that the laser wavelength used for detection is 900nm. T is the number of periods, indicating that the dielectric layer comprises a superlattice with 6 periods, each 20nm in thickness. The thickness of the primary dielectric sublayer d1 is 15nm, and the thickness of the secondary dielectric sublayer d2 is 5nm. As can be seen from the figure, the refractive index changes suddenly every 20nm of thickness. This allows the dynamic etching rate of each period to be calculated, and the cutoff etching time is determined by extrapolating the rate.
[0129] In the embodiment of the present disclosure, in the multi-stepped groove 1001 , the depth of each step is equal to the sum of the thicknesses of the primary dielectric sublayer 101 and the secondary dielectric sublayer 102 of one period;
[0130] Controlling the stop timing of etching based on changes in reflectivity includes:
[0131] When the reflectivity changes suddenly twice in succession, the etching is controlled to stop.
[0132] In this implementation, each step is equal to the sum of the thicknesses of the main dielectric sublayer and the auxiliary dielectric sublayer of one period, which is conducive to controlling the etching stop of the etcher and can produce a multi-step structure with equal step height.
[0133] In the embodiment of the present disclosure, in the multi-stepped groove 1001 , the depth of each step is equal to the sum of the thicknesses of the primary dielectric sublayer 101 and the secondary dielectric sublayer 102 in N periods, where N is a positive integer greater than 1.
[0134] Controlling the stop timing of etching based on changes in reflectivity includes:
[0135] When the reflectivity changes 2N times continuously, the etching is controlled to stop.
[0136] In this implementation, each step is equal to the sum of the thickness of the main dielectric sublayer and the auxiliary dielectric sublayer in N cycles, which is conducive to controlling the etching stop of the etcher. There are more mutation points in N cycles, which can make the etching control more precise.
[0137] In an embodiment of the present disclosure, controlling the stop timing of etching based on the change in reflectivity further includes:
[0138] Calculate etching rate based on reflectivity;
[0139] The etching stop timing is controlled based on the etching speed and the number of consecutive mutations of the reflectivity.
[0140] In this implementation, the approximate time when etching stops can be calculated in advance based on the etching speed. Within a certain range of this approximate time, the timing of stopping etching can be more accurately controlled by combining the number of continuous mutations in reflectivity, and the thickness of each step obtained is more accurate.
[0141] Optionally, the photoresist may be etched using O2 plasma, and the side etching of the plasma may be utilized to expand the area of the first groove.
[0142] Plasma side etching refers to the process in which, in addition to vertical etching, the sidewalls of the material will also be eroded to a certain extent during the plasma etching process, resulting in lateral expansion or lateral erosion of the etched area.
[0143] The third step is to remove the photoresist on the dielectric layer 100 .
[0144] In the disclosed embodiment, a stripping solution is used to remove the photoresist.
[0145] In the fourth step, a layer of photoresist is formed on the dielectric layer 100 .
[0146] In the fifth step, the dielectric layer 100 is etched for the second time in the first groove.
[0147] S26 , repeat step S25 to obtain a multi-step groove 1001 .
[0148] For example, the second groove is formed by etching the first groove for the second time, and then the third groove is formed by etching the second groove for the third time, and so on. After the above steps, the first groove, the second groove, the third groove, etc. together form the multi-level stepped groove 1001.
[0149] For example, the first etching is performed to 90 nm of the dielectric layer 100 , the second etching is performed to 60 nm of the dielectric layer 100 , and the third etching is performed to 30 nm of the dielectric layer 100 , thereby forming a multi-step groove 1001 with a step height of 30 nm.
[0150] Figure 7 is a structural diagram of an etching device provided by an embodiment of the present disclosure; see Figure 7 The etching device includes: a reaction chamber 300, a spectroscope 301, a laser 302, an optical detector 303 and a control module 304.
[0151] The spectrometer 301 is located between the reaction chamber 300 and the optical detector 303 and arranged in a straight line. The laser 302 is located on the side of the spectrometer 301 .
[0152] The laser 302 is used to generate a detection laser, which is irradiated onto the dielectric layer 100 in the reaction chamber 300 through the spectroscope 301. The dielectric layer 100 includes a plurality of main dielectric sublayers 101 and auxiliary dielectric sublayers 102 that are alternately arranged in a periodic manner. The main dielectric sublayers 101 and the auxiliary dielectric sublayers 102 have different refractive indices.
[0153] The optical detector 303 is used to receive the reflected laser light generated by the dielectric layer 100 based on the detection laser light.
[0154] The control module 304 is electrically connected to the laser 302 and the optical detector 303, and is used to control the etcher in the reaction chamber 300 to perform a first etching on the dielectric layer 100 to form a first groove; perform a second etching on the dielectric layer 100 in the first groove; repeat the above etching process to form a multi-step groove 1001; during each etching process, the reflected laser is sampled by the optical detector 303, the change in the reflectivity of the dielectric layer 100 at the etching position is monitored, and the stopping time of etching is controlled based on the change in reflectivity.
[0155] In this implementation, the dielectric layer is stacked by multiple periods of main dielectric sublayers and auxiliary dielectric sublayers, and the main dielectric sublayers and auxiliary dielectric sublayers have different refractive indices. With this dielectric layer design, during the etching process, the optical detector can detect the sudden change in the reflectivity of the dielectric layer at the interface between the main and auxiliary dielectric layers. The control module can determine the timing of stopping etching based on the change in reflectivity to ensure accurate etching position. At the same time, because the dielectric layer is composed of multiple periods, multi-level stepped grooves can be formed by repeating the above etching process. The metal layer set in the multi-level stepped grooves can act as a field plate, thereby meeting the electrode design requirements in scenarios such as transistors.
[0156] In the disclosed embodiment, the control module 304 obtains the reflectivity by comparing the light intensity sampled by the optical detector 303 with the light intensity emitted by the laser 302. The reflectivity change can be obtained based on the reflectivity difference between the two sampling points.
[0157] In the embodiment of the present disclosure, in the multi-stepped groove 1001 , the depth of each step is equal to the sum of the thicknesses of the primary dielectric sublayer 101 and the secondary dielectric sublayer 102 of one period;
[0158] The control module 304 is used to control the etching to stop when the reflectivity changes suddenly twice in succession.
[0159] In this implementation, each step is equal to the sum of the thicknesses of the main dielectric sublayer and the auxiliary dielectric sublayer of one period, which helps the control module to stop etching when the reflectivity changes twice in succession, and can produce a multi-step structure with equal step height.
[0160] In the embodiment of the present disclosure, in the multi-stepped groove 1001 , the depth of each step is equal to the sum of the thicknesses of the primary dielectric sublayer 101 and the secondary dielectric sublayer 102 in N periods, where N is a positive integer greater than 1.
[0161] The control module 304 is used to control the etching to stop when the reflectivity changes suddenly 2N times continuously.
[0162] In this implementation, each step is equal to the sum of the thickness of the main dielectric sublayer and the auxiliary dielectric sublayer in N cycles, which is conducive to controlling the etching stop of the etcher. There are more mutation points in N cycles, which can make the etching control more precise.
[0163] In the embodiment of the present disclosure, the reaction chamber 300 can be used to place the dielectric layer to be etched and provide a stable environment for etching reaction.
[0164] In the embodiment of the present disclosure, the reaction chamber 300 may be made of corrosion-resistant and high-temperature-resistant materials, such as quartz or ceramic.
[0165] Exemplarily, the reaction chamber 300 is made of quartz.
[0166] In the embodiment of the present disclosure, the spectroscope 301 is used to separate light of different wavelengths.
[0167] In the embodiment of the present disclosure, the beam splitter 301 is made of multi-layer coated optical glass and has the characteristics of high reflectivity and high transmittance.
[0168] In the embodiment of the present disclosure, the wavelength of the detection laser generated by the laser 302 may be 400-900 nm.
[0169] Exemplarily, the wavelength of the detection laser generated by the laser 302 is 900 nm.
[0170] In the embodiment of the present disclosure, using the wavelength in the above range makes it easier to detect the change in reflection, which is beneficial for determining the etching stop position.
[0171] In the embodiment of the present disclosure, the optical detector 303 is used to collect reflected laser signals during the etching process.
[0172] In the embodiment of the present disclosure, the control module 304 calculates the reflectivity change and the dynamic etching rate of each cycle during the etching process of the dielectric layer 100, determines the etching time, and controls the etching to stop.
[0173] The above description is merely an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.
Claims
1. A dielectric layer etching method, characterized in that: The method comprises: Producing a dielectric layer (100), the dielectric layer (100) comprising a plurality of periodically alternately arranged primary dielectric sublayers (101) and secondary dielectric sublayers (102), wherein the primary dielectric sublayers (101) and the secondary dielectric sublayers (102) have different refractive indices; Performing a first etching on the dielectric layer (100) to form a first groove; performing a second etching on the dielectric layer (100) in the first groove; The etching process is repeated to form multi-step stepped grooves (1001); during each etching process, the change in the reflectivity of the dielectric layer (100) at the etching position is monitored, and the etching stop timing is controlled based on the change in the reflectivity.
2. The dielectric layer etching method according to claim 1, characterized in that: In the multi-stepped groove (1001), the depth of each step is equal to the sum of the thicknesses of the main dielectric sublayer (101) and the auxiliary dielectric sublayer (102) in one period; Controlling the stopping timing of the etching based on the change of the reflectivity includes: When the reflectivity changes suddenly twice in succession, the etching is controlled to stop.
3. The dielectric layer etching method according to claim 1, wherein: In the multi-stepped groove (1001), the depth of each step is equal to the sum of the thicknesses of the main dielectric sublayer (101) and the auxiliary dielectric sublayer (102) in N periods, where N is a positive integer greater than 1; Controlling the stopping timing of the etching based on the change of the reflectivity includes: When the reflectivity changes suddenly 2N times continuously, the etching is controlled to stop.
4. The dielectric layer etching method according to claim 2 or 3, characterized in that: Controlling the stopping time of the etching based on the change of the reflectivity further includes: calculating an etching rate based on the reflectivity; The etching stopping timing is controlled based on the etching speed and the number of consecutive mutations of the reflectivity.
5. The dielectric layer etching method according to any one of claims 1 to 3, characterized in that: The refractive index of the main dielectric sublayer (101) is greater than 1.2 times the refractive index of the secondary dielectric sublayer (102).
6. The dielectric layer etching method according to any one of claims 1 to 3, characterized in that: The thickness of the main dielectric sublayer (101) or the auxiliary dielectric sublayer (102) in each period is not less than 5FR; F is a sampling interval of an optical detector for monitoring changes in the reflectivity of the dielectric layer (100) at the etching position; R is the etching rate of the main dielectric sublayer (101) or the auxiliary dielectric sublayer (102).
7. An etching device, characterized in that: The etching equipment comprises: a reaction chamber (300), a spectroscope (301), a laser (302), an optical detector (303) and a control module (304); The spectroscope (301) is located between the reaction chamber (300) and the optical detector (303) and is arranged in a straight line, and the laser (302) is located on the side of the spectroscope (301); The laser (302) is used to generate a detection laser, and the detection laser is irradiated onto the dielectric layer (100) in the reaction chamber (300) through the spectroscope (301), wherein the dielectric layer (100) comprises a plurality of main dielectric sublayers (101) and auxiliary dielectric sublayers (102) that are alternately arranged in a periodic manner, and the main dielectric sublayers (101) and the auxiliary dielectric sublayers (102) have different refractive indices; The optical detector (303) is used to receive the reflected laser light generated by the dielectric layer (100) based on the detection laser light; The control module (304) is electrically connected to the laser (302) and the optical detector (303), and is used to control the etcher in the reaction chamber (300) to perform a first etching on the dielectric layer (100) to form a first groove; perform a second etching on the dielectric layer (100) in the first groove; repeat the above etching process to form a multi-step groove (1001); during each etching process, the reflected laser is sampled by the optical detector (303), the change in the reflectivity of the dielectric layer (100) at the etching position is monitored, and the etching stop timing is controlled based on the change in the reflectivity.
8. The etching device according to claim 7, characterized in that: The wavelength of the detection laser generated by the laser (302) is 400-900 nm.
9. The etching device according to claim 7, characterized in that: In the multi-stepped groove (1001), the depth of each step is equal to the sum of the thicknesses of the main dielectric sublayer (101) and the auxiliary dielectric sublayer (102) in one period; The control module (304) is used to control etching to stop when the reflectivity changes suddenly twice in succession.
10. The etching equipment according to claim 7, characterized in that: In the multi-stepped groove (1001), the depth of each step is equal to the sum of the thicknesses of the main dielectric sublayer (101) and the auxiliary dielectric sublayer (102) in N periods, where N is a positive integer greater than 1; The control module (304) is used to control etching to stop when the reflectivity changes suddenly 2N times continuously.