Method for controlling wet etching morphology
By using a patterned shielding layer to form a fast etching area during the wet etching process, combined with the wet etching process, the problem of difficult morphology control of wet etching is solved, and high-precision groove formation is achieved .
Patent Information
- Application Number
- CN202411568012.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-05
- Publication Date
- 2025-02-18
AI Technical Summary
The existing wet etching technology has difficulties in morphology control, especially because its isotropic characteristics make it difficult to control the high-precision pattern.
By forming a sequential first film layer and a second film layer on the substrate wafer, and forming a patterned shielding layer on the second film layer, ion implantation of preset energy, preset angle and preset dose is performed. to form a fast etching area. Then, the second film layer in the rapid etching area and its peripheral area is etched by a wet etching process to obtain a groove with a preset morphology.
The precise control of the wet etching morphology is achieved, and the preset aspect ratio and side wall inclination are obtained, which avoids the serious problem of lateral corrosion of wet etching. The process is simple and easy to implement.
Smart Images
Figure CN119480636A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of integrated circuit manufacturing and relates to a method for controlling wet etching morphology. Background Art
[0002] In the microelectronic chip manufacturing process, the etching of dielectric materials is a crucial link. Existing etching technologies are divided into wet etching and dry etching, each of which has its own advantages and limitations. Among them, dry etching is a technology that uses plasma or reactive gas to etch solid materials on the surface of the wafer, which can achieve high directionality, thereby obtaining vertical sidewalls and high aspect ratios. Although dry etching has precise control over the etching morphology, the technology has the problem of poor material selectivity, causing damage to the surface of the underlying substrate. Wet etching is a technology that uses liquid chemical solutions to etch solid materials on the surface of the wafer. Wet etching has excellent selectivity and can accurately etch the current film without damaging the film of other materials below. However, wet etching also has some disadvantages that cannot be ignored. Due to the isotropic characteristics of wet etching, the width of the lateral etching is close to the depth of the vertical etching. This etching characteristic makes it difficult to control the graphics with high precision, such as Figure 1 As shown, it is a SEM image of a groove formed by wet etching, including wafer 01, dielectric layer 02 and groove 021. It can be seen from the figure that the lateral corrosion of the groove is large and the morphology is poor.
[0003] Therefore, there is an urgent need to find a method for controlling the wet etching morphology that can control the wet etching morphology. Summary of the invention
[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method for controlling wet etching morphology, so as to solve the problem that the etching morphology is difficult to control during the wet etching process in the prior art.
[0005] To achieve the above object and other related objects, the present invention provides a method for controlling wet etching morphology, comprising the following steps:
[0006] Providing a substrate wafer, and forming a first film layer and a second film layer stacked in sequence on an upper surface of the substrate wafer;
[0007] Forming a patterned shielding layer on the upper surface of the second film layer, and performing ion implantation of preset energy, preset angle and preset dose on the exposed second film layer based on the shielding layer to obtain a fast etching area, and the ion implantation depth is less than the thickness of the second film layer;
[0008] The fast etching area and the second film layer around the fast etching area are etched based on the shielding layer by a wet etching process to obtain a groove with a preset morphology.
[0009] Optionally, a material of the first film layer includes SiN, SiO, SiON, TEOS, AlN, and Al2O3; a material of the second film layer includes SiN, SiO, SiON, TEOS, AlN, and Al2O3.
[0010] Optionally, the density of the first film layer is greater than the density of the second film layer.
[0011] Optionally, the material of the first film layer is the same as the material of the second film layer.
[0012] Optionally, the method for forming the first film layer includes low-pressure chemical vapor deposition; the method for forming the second film layer includes plasma enhanced chemical vapor deposition.
[0013] Optionally, the material of the shielding layer includes photoresist.
[0014] Optionally, the ions implanted into the second film layer based on the shielding layer include argon ions, hydrogen ions, and fluorine ions.
[0015] Optionally, the dose value of the preset dose decreases as the ion implantation depth increases.
[0016] Optionally, before performing ion implantation on the second film layer, the method further includes setting the preset angle and the preset energy.
[0017] Optionally, after forming the groove, the method further includes a step of removing the shielding layer.
[0018] As described above, the method for controlling the wet etching morphology of the present invention improves the wet etching process, firstly ion implantation is performed based on the patterned shielding layer to form the fast etching area, and the implantation depth during the ion implantation process is less than the thickness of the second film layer to avoid damaging the first film layer during the ion implantation process, and then wet etching is used to etch the fast etching area. Due to the lattice damage of the second film layer in the fast etching area, the reaction rate of the second film layer in the area with the etchant is greater than the reaction rate of the undamaged second film layer in the periphery with the etchant, and then the wet etching forms an etching rate difference in the longitudinal and transverse directions, thereby obtaining a groove with a preset depth-to-width ratio. In addition, by controlling the angle of ion implantation and the dose of ion implantation, the longitudinal etching rate of the fast etching area can be achieved, and then the ratio of the longitudinal and transverse etching rates during the etching process can be controlled to achieve the control of the inclination degree of the sidewall of the formed groove, thereby achieving the control of the etching morphology of wet etching, and the process is simple and easy to implement, with high industrial utilization value. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1SEM image showing the trenches formed by wet etching.
[0020] Figure 2 The process flow chart of the method for controlling wet etching morphology of the present invention is shown.
[0021] Figure 3 It is a schematic diagram of the cross-sectional structure after the second film layer is formed in the method for controlling the wet etching morphology of the present invention.
[0022] Figure 4 It is a schematic diagram of the cross-sectional structure after forming a patterned shielding layer in the method for controlling wet etching morphology of the present invention.
[0023] Figure 5 It is a schematic diagram of the cross-sectional structure after forming a fast etching area in the method for controlling wet etching morphology of the present invention.
[0024] Figure 6 It is a schematic diagram of the cross-sectional structure after the groove is formed according to the method for controlling the wet etching morphology of the present invention.
[0025] Figure 7 It is a schematic diagram of the cross-sectional structure after removing the shielding layer of the method for controlling the wet etching morphology of the present invention.
[0026] Description of Figure Numbers
[0027] 01 Wafer
[0028] 02 Dielectric layer
[0029] 021 Groove
[0030] 1 Substrate Wafer
[0031] 2 First film layer
[0032] 3 Second film layer
[0033] 31 Rapid etching area
[0034] 4 Shielding layer
[0035] 5 Grooves DETAILED DESCRIPTION
[0036] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.
[0037] See also Figures 2 to 7It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.
[0038] This embodiment provides a method for controlling the wet etching morphology. Figures 2 to 7 ,like Figure 2 As shown, it is a flow chart of the method for controlling the wet etching morphology, comprising the following steps:
[0039] S1: providing a substrate wafer, and forming a first film layer and a second film layer stacked in sequence on an upper surface of the substrate wafer;
[0040] S2: forming a patterned shielding layer on the upper surface of the second film layer, and performing ion implantation with a preset energy, a preset angle and a preset dose on the exposed second film layer based on the shielding layer to obtain a fast etching area, and the ion implantation depth is less than the thickness of the second film layer;
[0041] S3: etching the fast etching area and the second film layer around the fast etching area based on the shielding layer by a wet etching process to obtain a groove with a preset morphology.
[0042] See also Figures 3 to 5 , execute step S1 and step S2: provide a substrate wafer 1, and form a first film layer 2 and a second film layer 3 stacked in sequence on the upper surface of the substrate wafer 1; form a patterned shielding layer 4 on the upper surface of the second film layer 3, and perform ion implantation with preset energy, preset angle and preset dose on the exposed second film layer 3 based on the shielding layer 4 to obtain a fast etching area 31, and the ion implantation depth is less than the thickness of the second film layer 3.
[0043] Specifically, the substrate wafer 1 is a process platform for forming the first film layer 2. While ensuring the quality of the first film layer 2 formed subsequently, the size, thickness and shape of the substrate wafer 1 can be selected according to actual conditions and are no longer restricted here; the number of layers and structure of the film layer in the substrate wafer 1 can be selected according to actual conditions and are no longer restricted here.
[0044] Specifically, the substrate wafer 1 is made of silicon, gallium nitride, silicon carbide or other suitable semiconductor materials. Preferably, a gallium nitride wafer is used as the substrate wafer 1.
[0045] As an example, the density of the first film layer 2 is greater than the density of the second film layer 3 .
[0046] Specifically, under the condition of ensuring the performance of the devices in the substrate wafer 1 , the density of the first film layer 2 may also be less than or equal to the density of the second film layer 3 .
[0047] As an example, the method for forming the first film layer 2 includes low pressure chemical vapor deposition or other suitable methods. In this embodiment, the first film layer 2 is manufactured by low pressure chemical vapor deposition process.
[0048] Specifically, when the first film layer 2 is made by low-pressure chemical vapor deposition process, since the deposited reaction gas reacts at a lower pressure and a higher temperature, the formed film layer has better uniformity and higher density, that is, the quality of the obtained film layer is better.
[0049] As an example, the material of the first film layer 2 includes SiN, SiO, SiON, TEOS, AlN, Al2O3 or other suitable dielectric materials. In this embodiment, a SiN layer is used as the first film layer 2.
[0050] Specifically, under the condition of ensuring the performance of the devices in the substrate wafer 1, the thickness of the first film layer 2 can be selected according to actual conditions, and is not limited here.
[0051] As an example, Figure 3 , which is a schematic diagram of the cross-sectional structure after the second film layer 3 is formed. The method for forming the second film layer 3 includes plasma enhanced chemical vapor deposition or other suitable methods.
[0052] Specifically, plasma enhanced chemical vapor deposition is usually carried out at low temperatures, which can save energy and improve production. However, the film layer formed at low temperatures has a loose texture, low density, poor quality, and poor breakdown resistance.
[0053] As an example, the material of the second film layer 3 includes SiN, SiO, SiON, TEOS, AlN, Al2O3 or other suitable materials.
[0054] Specifically, the second film layer 3 is generally used to protect the first film layer 2. Under the condition of ensuring the performance of the device in the substrate wafer 1, the thickness of the second film layer 3 can be selected according to actual conditions and is not limited here. In this embodiment, the second film layer 3 is a passivation layer of the first film layer 2.
[0055] As an example, the material of the first film layer 2 is the same as the material of the second film layer 3. In this embodiment, the first film layer 2 and the second film layer 3 are both silicon nitride layers.
[0056] Specifically, under the condition of ensuring the performance of the device in the substrate wafer 1, the material of the first film layer 2 may be different from the material of the second film layer 3. For example, the first film layer 2 is a silicon oxide layer, and the second film layer 3 is a silicon nitride layer.
[0057] Specifically, the material of the shielding layer 4 includes photoresist or other suitable photoresist materials. Preferably, a positive photoresist layer is used as the shielding layer 4.
[0058] Specifically, the method for forming the shielding layer 4 is a method for forming photoresist commonly used in the photolithography process, which will not be described in detail here.
[0059] Specifically, Figure 4 FIG. 4 is a schematic diagram of a cross-sectional structure after forming the patterned shielding layer 4. The method for patterning the shielding layer 4 is a common photoresist exposure and development process. In this embodiment, ultraviolet lithography technology is used to expose the positive photoresist so that the photoresist layer in the exposed area forms a cross-linking reaction with the ultraviolet light, and then the developer is used to dissolve the photoresist area after the reaction to expose the second film layer 3.
[0060] Specifically, under the condition of ensuring the performance of the devices in the substrate wafer 1, the thickness of the shielding layer 4 can be selected according to actual conditions, and is not limited here.
[0061] As an example, Figure 5 As shown, it is a schematic diagram of the cross-sectional structure after the rapid etching area 31 is formed, and the ions injected into the exposed second film layer 3 based on the shielding layer 4 include argon ions, hydrogen ions, fluorine ions or other suitable ions. Preferably, argon ions are used as the ions for ion injection into the exposed second film layer 3.
[0062] Specifically, by performing ion implantation on the second film layer 3 based on the patterned shielding layer 4, the low-energy ions injected into the second film layer 3 can be used to destroy the crystal cell structure of the second film layer 3 in the area, breaking the chemical bonds between atoms, so that the reaction rate between the fast etching area 31 and the etchant is greater than the reaction rate between the non-fast etching area 31 in the second film layer 3 and the etchant, thereby achieving control of the longitudinal and lateral etching rates in the process of forming the groove.
[0063] As an example, before ion implantation is performed on the second film layer 3 , the step of setting the preset angle, the preset energy and the preset dose is also included.
[0064] Specifically, in actual production, based on the thickness of the second film layer 3 and the morphology of the groove to be etched, the preset energy and the preset angle required for ion implantation are estimated, and the preset angle and the preset energy are set in the ion implantation machine.
[0065] Specifically, during the process of ion implantation into the second film layer 3, it is necessary to ensure that the injected ions do not damage the first film layer 2 to ensure the quality of the first film layer 2. Therefore, the depth of ion implantation is less than the thickness of the second film layer 3, and the size of the preset energy affects the depth of ion implantation. Therefore, the depth of ion implantation into the second film layer 3 can be controlled by controlling the energy during the ion implantation process. While ensuring the performance of the device in the substrate wafer 1, the preset energy can be selected according to the thickness of the second film layer 3, and is no longer restricted here.
[0066] Specifically, the morphology of the rapid etching area 31 formed after ion implantation can be controlled by controlling the angle of ion implantation. While ensuring the device performance in the substrate wafer 1, the preset angle can be selected according to actual conditions and is no longer restricted here; the cross-sectional morphology of the rapid etching area 31 can be selected according to actual conditions and is no longer restricted here.
[0067] As an example, the dose value of the preset dose decreases as the ion implantation depth increases.
[0068] Specifically, by reducing the ion implantation dose along with the depth of ion implantation in the second film layer 3, it is possible to avoid scattering damage to the first film layer 2 caused by ions injected into the bottom layer of the second film layer 3 during the formation of the rapid etching area 31, thereby ensuring the quality of the first film layer 2.
[0069] Specifically, by controlling the dose of ion implantation that forms the fast etching area 31, the degree of damage to the crystal cell structure of the fast etching area 31 can be controlled, and the greater the dose, the more severe the damage to the crystal cell structure of the fast etching area 31, and the faster the reaction rate of this area with the etchant, thereby controlling the etching rate of the fast etching area 31 in the second film layer 3 to control the ratio of the longitudinal and lateral etching rates during the etching process, that is, controlling the aspect ratio and morphology of the groove after etching.
[0070] Please see again Figure 6 to Figure 7 , executing the step S3: etching the fast etching area 31 and the second film layer 3 around the fast etching area 31 based on the shielding layer 4 by a wet etching process to obtain a groove 5 with a preset morphology.
[0071] Specifically, the type of etchant used for wet etching to remove the fast etching area 31 can be selected according to the material of the second film layer 3, and is not limited here. For example, when the material of the second film layer 3 is silicon nitride or silicon oxide, a BOE (Buffered Oxide Etchant) solution can be used as an etchant for etching the second film layer 3.
[0072] Specifically, since the shielding layer 4 covers the exposed upper surface of the non-fast etching area 31 of the second film layer 3, the crystal cell structure of the fast etching area 31 formed by ion implantation of the second film layer 3 has been damaged, and the chemical bonds between atoms have been destroyed, resulting in a faster reaction between the wet etching etchant and the fast etching area 31, that is, a faster longitudinal etching rate, while the crystal cells of the second film layer 3 in the area where ion implantation is not performed are not damaged, and their reaction with the wet etching etchant is slower, that is, a slower lateral etching rate, which results in a difference between the longitudinal and lateral etching rates, thereby achieving control over the morphology of the groove 5 after wet etching.
[0073] Specifically, Figure 6 As shown, it is a schematic diagram of the cross-sectional structure after the groove 5 is formed. Under the condition of ensuring the performance of the device in the substrate wafer 1, the opening size and opening shape of the groove 5 can be selected according to actual conditions and are not limited here.
[0074] As an example, Figure 7 , which is a schematic diagram of the cross-sectional structure after the shielding layer 4 is removed. After the groove 5 is formed, the step of removing the shielding layer 4 is also included.
[0075] Specifically, by removing the shielding layer 4, the desired corrosion structure can be obtained.
[0076] Specifically, the method of removing the shielding layer 4 includes an ashing process or other suitable methods.
[0077] Specifically, since the shielding layer 4 is a photoresist, removing the shielding layer 4 through an ashing process can allow the photoresist to fully react with oxygen at high temperature to generate pollution-free gas, thereby reducing the environmental pollution caused by the process, and at the same time avoiding the residual photoresist on the surface of the second film layer 3 affecting the performance of the devices in the substrate wafer 1.
[0078] Specifically, ion implantation is performed on the second film layer 3 to destroy the crystal cell structure of the second film layer 3, thereby obtaining the fast etching area 31, so that the reaction between the second film layer 3 corresponding to the fast etching area 31 and the etchant is accelerated, and the reaction between the second film layer 3 and the etchant in the area where ion implantation is not performed is slower, thereby forming a difference in etching speed in the longitudinal and lateral directions during the etching process, thereby forming the groove 5 with a higher aspect ratio. By controlling the angle of ion implantation and the dose of ion implantation, the longitudinal etching rate can be controlled, and then the ratio of the longitudinal and lateral etching rates can be controlled, so that the sidewalls of the groove 5 formed by wet etching are at a preset angle, thereby realizing the control of the etching morphology of wet etching, and avoiding the problem of serious lateral corrosion by wet etching.
[0079] Specifically, the ion implantation depth in the process of forming the fast etching area 31 is smaller than the thickness of the second film layer 3 to avoid damaging the first film layer 2 during the ion implantation process. Since wet etching has a high etching selectivity, damage to the first film layer 2 can be avoided during the wet etching process, thereby ensuring the quality of the first film layer 2. There is no need to develop new process equipment, and the process is simple and easy to implement.
[0080] In summary, the method for controlling the wet etching morphology of the present invention improves the wet etching process. First, ions are implanted into the second film layer based on the patterned shielding layer to form a fast etching area. The depth of the ion implantation is less than the thickness of the second film layer to avoid damaging the first film layer during the ion implantation process. Then, the wet etching process is used to etch the fast etching area. Due to the lattice damage of the second film layer in the ion implantation area, the reaction rate of the second film layer in this area with the etchant is greater than the reaction rate of the undamaged second film layer with the etchant, and then the wet etching forms an etching rate difference in the longitudinal and transverse directions, which facilitates the acquisition of a groove with a preset depth-to-width ratio. In addition, by controlling the angle of ion implantation and the dose of ion implantation, the longitudinal etching rate of the fast etching area can be controlled, and then the ratio of the transverse to longitudinal etching rates can be controlled, thereby realizing the control of the etching morphology of wet etching. The process is simple and easy to implement. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.
[0081] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.
Claims
1. A method for controlling wet etching morphology, characterized in that: The following steps are involved: Providing a substrate wafer, and forming a first film layer and a second film layer stacked in sequence on an upper surface of the substrate wafer; Forming a patterned shielding layer on the upper surface of the second film layer, and performing ion implantation of preset energy, preset angle and preset dose on the exposed second film layer based on the shielding layer to obtain a fast etching area, and the ion implantation depth is less than the thickness of the second film layer; Based on the shielding layer, the fast etching area and the second film layer around the fast etching area are etched by a wet etching process to obtain a groove with a preset morphology.
2. The method for controlling wet etching morphology according to claim 1, characterized in that: The material of the first film layer includes SiN, SiO, SiON, TEOS, AlN, and Al2O3; the material of the second film layer includes SiN, SiO, SiON, TEOS, AlN, and Al2O3.
3. The method for controlling wet etching morphology according to claim 1, characterized in that: The density of the first film layer is greater than the density of the second film layer.
4. The method for controlling wet etching morphology according to claim 1, characterized in that: The method for forming the first film layer includes low pressure chemical vapor deposition; the method for forming the second film layer includes plasma enhanced chemical vapor deposition.
5. The method for controlling wet etching morphology according to claim 1, characterized in that: The material of the first film layer is the same as that of the second film layer.
6. The method for controlling wet etching morphology according to claim 1, characterized in that: The material of the shielding layer includes photoresist.
7. The method for controlling wet etching morphology according to claim 1, characterized in that: The ions implanted into the exposed second film layer based on the shielding layer include argon ions, hydrogen ions, and fluorine ions.
8. The method for controlling wet etching morphology according to claim 1, characterized in that: The dose value of the preset dose decreases as the ion implantation depth increases.
9. The method for controlling wet etching morphology according to claim 1, characterized in that: Before ion implantation is performed on the second film layer, the method further includes setting the preset angle and the preset energy.
10. The method for controlling wet etching morphology according to claim 1, characterized in that: After forming the groove, the method further includes removing the shielding layer.