Manufacturing method of inclined microporous structure
Through a two-step etching and dielectric layer deposition process, the manufacturing difficulties of small-linewidth micropore structures in existing technologies have been solved, precise control and yield improvement of high aspect ratio inclined micropores have been achieved, the process flow has been simplified and costs have been reduced.
Patent Information
- Application Number
- CN202510779110.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-12
- Publication Date
- 2025-09-05
AI Technical Summary
Existing technologies make it difficult to accurately manufacture micropore structures with inclined characteristics under small line width conditions. Especially in the case of high aspect ratio, the etching angle is difficult to control, the pore wall roughness is high and the etching uniformity is poor, which easily leads to the formation of bottom residues.
A two-step etching and dielectric deposition process is used. First, vertical micropores are etched on the first dielectric layer, and then a second dielectric layer is deposited on its inner wall. The second dielectric layer is etched at a high etching rate to form an inclined micropore structure.
It achieves precise manufacturing of small line width and high aspect ratio inclined micro-holes, simplifies the process flow, reduces costs, improves device yield, and is compatible with existing semiconductor manufacturing equipment.
Smart Images
Figure CN120600692A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a method for manufacturing an inclined microporous structure. Background Art
[0002] In the field of semiconductor manufacturing, inclined micropore structures are crucial for technologies such as 3D NAND flash memory chips, through-silicon via (TSV) interconnects, and organic microdisplays (OLEDs). Although traditional dry etching methods such as reactive ion etching (RIE) and deep reactive ion etching (DRIE) can achieve vertical micropores with high aspect ratios, it is difficult for them to directly form the required inclined micropore structures through a single etching step. On the other hand, although wet etching can produce structures with inclined sidewalls, its inability to effectively control lateral corrosion is particularly prominent when dealing with fine structures with small line widths of less than 100 nanometers. The main reasons for this situation are: the preparation process of inclined micropores is complex and the process window is narrow, the precise control of the etching angle faces challenges, and it is easy to cause the roughness of the pore wall to increase. In addition, in the case of high aspect ratios, the etching uniformity is poor, which may lead to the formation of bottom residues.
[0003] In the prior art, dry etching is used to form microporous structures in one step, and a combination of dry etching and wet etching is used to form inclined micropores, such as Figure 1 As shown, Figure 1 a is a single-step dry etching method, in which dry etching is performed directly on the first dielectric layer 1 to etch out inclined microholes 2 with a relatively low inclination angle; Figure 1 b is to first wet-etch to form an opening on the first dielectric layer 1, and then dry-etch downwards. Although the inclined micropores 2 can be formed with an inclined morphology, which is beneficial to the subsequent filling to a certain extent, the overall morphology is not good and cannot meet product requirements.
[0004] Therefore, in order to meet the requirements under small line width conditions, a new method is urgently needed to accurately manufacture micropore structures with inclined characteristics. Summary of the Invention
[0005] The present invention provides a method for manufacturing an inclined micropore structure, which realizes the precise manufacturing of inclined micropores with small line width and high aspect ratio through a two-step etching and dielectric deposition process.
[0006] Other purposes and advantages of the present invention can be further understood from the technical features disclosed in the present invention.
[0007] To achieve one, part, or all of the above-mentioned objectives or other objectives, a technical solution of the present invention provides a method for manufacturing an inclined micropore structure, comprising etching a vertical micropore on a first dielectric layer, depositing a second dielectric layer made of a material different from that of the first dielectric layer on the inner wall of the formed vertical micropore and the surface of the first dielectric layer; etching the second dielectric layer using an etching process in which the etching rate of the second dielectric layer is greater than the etching rate of the first dielectric layer, removing the second dielectric layer from the surface of the first dielectric layer and the bottom of the vertical micropore, and leaving the inclined second dielectric layer in the vertical micropore, so that the vertical micropore and the second dielectric layer in the vertical micropore together form the desired inclined micropore structure.
[0008] The first dielectric layer is any one of silicon oxide, silicon nitride, gallium nitride or aluminum oxide grown by LPCVD process or PECVD process.
[0009] The thickness of the first dielectric layer is 10 nm-5 um.
[0010] The method for forming the vertical microholes on the first dielectric layer includes spin coating photoresist on the surface of the first dielectric layer, photoetching the positions of the vertical microholes, and etching the first dielectric layer using a dry etching method.
[0011] After the vertical micropores are formed, the photoresist on the surface of the first dielectric layer is removed, and then the second dielectric layer is deposited.
[0012] The second dielectric layer is any one of silicon oxide, silicon nitride, gallium nitride or aluminum oxide grown by LPCVD process or PECVD process.
[0013] The thickness of the second dielectric layer is 7nm-3.5um.
[0014] The thickness of the second dielectric layer is 50%-90% of the thickness of the first dielectric layer.
[0015] The second dielectric layer is etched using a dry etching process, and the ratio of the etching rate of the second dielectric layer to the etching rate of the first dielectric layer is at least greater than 5.
[0016] The tilt angle of the second dielectric layer in the vertical micropore is achieved by controlling the over-etching amount. As the over-etching amount increases, the tilt angle of the second dielectric layer in the vertical micropore decreases.
[0017] Compared with the prior art, the beneficial effects of the present invention mainly include: 1. The manufacturing method of the inclined micropore structure of the present invention includes a vertical micropore etching step, a second dielectric layer deposition step and an inclined micropore etching step. Through two-step etching and dielectric layer deposition, precise control of small line width inclined micropores can be achieved.
[0018] 2. The inclined micropore manufacturing method of the present invention is compatible with existing semiconductor manufacturing equipment without the need for additional investment. At the same time, the inclination angle of the inclined micropore of the present invention can be adjusted to meet different filling process requirements.
[0019] 3. The present invention can effectively simplify the process flow, reduce process difficulty and cost, and improve the yield of the device.
[0020] In order to make the above and other objects, features and advantages of the present invention more clearly understood, preferred embodiments are given below with reference to the accompanying drawings for detailed description. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, 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 invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0022] Figure 1 Schematic diagram of the manufacturing process of inclined microholes in the prior art.
[0023] Figure 2 Schematic diagram of the manufacturing process of the inclined microholes of the present invention.
[0024] Figure 3 This is an SEM image of the inclined microporous structure formed in the present invention.
[0025] In the figure, 1 is the first dielectric layer; 2 is the inclined micropores; 3 is the second dielectric layer; 4 is the vertical micropores. DETAILED DESCRIPTION
[0026] The foregoing and other technical aspects, features, and functions of the present invention are clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. Directional terms such as up, down, left, right, front, and back, used in the following embodiments, are intended solely to refer to the directions in the accompanying drawings. Therefore, the directional terms used are for illustrative purposes only and are not intended to limit the present invention.
[0027] Example 1
[0028] Example 1 provides a method for manufacturing an inclined microporous structure. Figure 2As shown, the process includes etching a vertical micropore 4 on a first dielectric layer 1, depositing a second dielectric layer 3 made of a material different from that of the first dielectric layer 1 on the inner wall of the formed vertical micropore 4 and on the surface of the first dielectric layer 1; etching the second dielectric layer 3 using an etching process in which the etching rate of the second dielectric layer 3 is greater than the etching rate of the first dielectric layer 1, removing the second dielectric layer 3 on the surface of the first dielectric layer 1 and the bottom of the vertical micropore 4, and leaving an inclined second dielectric layer 3 in the vertical micropore 4. The vertical micropore 4 and the second dielectric layer 3 in the vertical micropore 4 together form the required inclined micropore 2.
[0029] See also Figure 2 A method for manufacturing an inclined microporous structure of the present invention comprises the following steps:
[0030] Step 1: Provide a first dielectric layer 1.
[0031] In this embodiment, the first dielectric layer 1 is any one of silicon oxide, silicon nitride, gallium nitride or aluminum oxide grown by LPCVD or PECVD process. The first dielectric layer 1 can be grown on a desired substrate.
[0032] Specifically, silicon oxide growth: When using the LPCVD process to grow silicon oxide, silane SiH4 and oxygen (or tetraethyl orthosilicate TEOS) are used as precursor gases, and the silicon oxide film is deposited in an environment with a temperature of 600°C-800°C and a pressure of 0.1-1 Torr. When using the PECVD process to grow silicon oxide, SiH4 and N2O (or oxygen) are used as precursors, and the silicon oxide film is grown in an environment with an auxiliary plasma enhancement at 200°C-400°C.
[0033] Growing silicon nitride films: When growing silicon nitride using the LPCVD process, dichlorosilane SiH2Cl2 and ammonia are used as precursor gases, and the temperature is maintained at 700°C-800°C and the pressure is maintained at 0.3-1 Torr for silicon nitride film deposition. When growing silicon nitride using the PECVD process, SiH4 and NH3 (or nitrogen) are used as precursor gases, and the temperature is maintained at 300°C-400°C, with plasma enhancement to assist in the formation of silicon nitride films.
[0034] Growing gallium nitride (GaN) thin films: When growing gallium nitride using the LPCVD process, gallium source trimethyl gallium (TMGa) (or triethyl gallium TEGa) and ammonia NH3 are used at 800°C-1100°C, maintaining a pressure of 50-300 Torr to generate polycrystalline GaN. The TMGa (or TEGa) gas flow rate is 10-100 sccm, and the ammonia flow rate is 1000-5000 sccm. After deposition is completed, the supply of precursors is stopped and the film is cooled to room temperature in an ammonia atmosphere. The formed polycrystalline GaN is annealed at a temperature of 1000°C-1200°C with ammonia as the atmosphere gas for 30 minutes to 60 minutes. When growing GaN using the PECVD process, amorphous GaN thin films are formed using TMGa or gallium halide (GaCl3) as the gallium source, ammonia, and a plasma source RF power of 50W-500W at temperatures of 200°C-500°C and pressures of 0.1-10 Torr. The ratio of ammonia to gallium source gas is at least greater than 80:1, and the resulting amorphous GaN film is annealed at 800°C-100°C with ammonia as the ambient gas for 10-60 seconds.
[0035] Aluminum oxide film growth: When using the LPCVD process to grow aluminum oxide, trimethylaluminum (TMA) and oxygen (or H2O) are used as precursor gases to deposit aluminum oxide films at 400°C-600°C. When using the PECVD process to grow aluminum oxide, trimethylaluminum (TMA) and oxygen (or H2O) plasma are used to deposit aluminum oxide films at temperatures below 300°C.
[0036] The thickness of the first dielectric layer 1 is 10 nm to 5 μm, and is determined by the device performance requirements.
[0037] In other embodiments, the substrate may also directly serve as the first dielectric layer 1 .
[0038] Step 2-1: Etching vertical microholes 4.
[0039] Photoresist is spin-coated on the first dielectric layer 1, and the vertical micropore positions are photoetched. The vertical micropores are etched using a dry etching method. When the first dielectric layer 1 is silicon oxide or silicon nitride, one or more mixed gases of CF4 and CHF3 are used as reaction gases for dry etching; when the first dielectric layer 1 is gallium nitride or aluminum oxide, one or more mixed gases of Cl2 and BCl3 are used as reaction gases for dry etching.
[0040] Step 2-2: After the vertical microholes 4 are formed, the photoresist on the surface of the first dielectric layer 1 is removed.
[0041] Step 3: Deposit the second dielectric layer 3. The structure after the second dielectric layer 3 is deposited is as follows: Figure 2As shown in part b.
[0042] A second dielectric layer 3 is deposited on the first dielectric layer 1. The second dielectric layer 3 is grown using an LPCVD or PECVD process and is made of any of silicon oxide, silicon nitride, gallium nitride, or aluminum oxide. The second dielectric layer 3 covers the surface of the first dielectric layer 1 and the inner surfaces of the vertical micropores 4. The deposition method for the second dielectric layer 3 is the same as that for the first dielectric layer 1, except that the material of the deposited second dielectric layer 3 must be different from that of the first dielectric layer 1. For example, if the first dielectric layer 1 is silicon oxide, the second dielectric layer 3 can be made of any of silicon nitride, gallium nitride, or aluminum oxide. The specific growth method is the same as in step 1 and can be selected based on the materials of the first and second dielectric layers. The specific growth method for the second dielectric layer 3 is not detailed here.
[0043] The thickness of the second dielectric layer 3 is controlled within a range of 7nm-3.5um. The specific thickness of the second dielectric layer 3 is determined by the device performance requirements. Assuming the thickness of the second dielectric layer 3 meets the requirements, the thickness of the second dielectric layer 3 is selected to be 50%-90% of the thickness of the first dielectric layer 1. This range facilitates the filling of the vertical micropores 4 and the subsequent formation of the inclined micropores 2.
[0044] Step 4: Etching the second dielectric layer 3 to form an inclined micropore 2 structure.
[0045] The second dielectric layer 3 is etched using an etching process in which the etching rate of the second dielectric layer 3 is greater than the etching rate of the first dielectric layer 1, removing the second dielectric layer 3 on the surface of the first dielectric layer 1 and the bottom wall of the vertical micropore 4, and leaving the inclined second dielectric layer 3 on the inner wall of the vertical micropore 4. The vertical micropore 4 and the second dielectric layer 3 in the vertical micropore 4 together form the required inclined micropore 2 structure.
[0046] Specifically, the second dielectric layer 3 is etched using a dry etching process, and the ratio of the etching rate of the second dielectric layer 3 to the etching rate of the first dielectric layer 1 is at least greater than 5, as follows:
[0047] When the first dielectric layer 1 and the second dielectric layer 3 are respectively silicon oxide and silicon nitride: use CHF3 (or CH2F2 / CH3F) and oxygen mixed gas for etching, and the etching rate of silicon oxide can be adjusted by controlling the proportion of oxygen to improve the selectivity of silicon nitride.
[0048] When the first dielectric layer 1 and the second dielectric layer 3 are respectively silicon oxide or gallium nitride: If the second dielectric layer 3 is gallium nitride, a gas mixture of 90% chlorine and 10% BCl3 is selected at a pressure of 7mTorr-10mTorr, an RF ICP source power of 400W-450W, and a bias power of 150W-200W. In this case, the etching selectivity ratio for gallium nitride / silicon oxide can be greater than 10:1. When the second dielectric layer 3 is silicon oxide, a gas mixture of 80% CF4, 10% oxygen, and 10% argon is selected at a pressure of 20mTorr-30mTorr, an RF ICP source power of 250W-300W, and a bias power of 80W-100W. In this case, the etching selectivity ratio for silicon oxide / gallium nitride can be greater than 5:1.
[0049] When the first dielectric layer 1 and the second dielectric layer 3 are either silicon oxide or aluminum oxide: If the second dielectric layer 3 is silicon oxide, the etching gas is a mixture of CF4, CHF3, and oxygen. Increasing the CF4 ratio (CF4 ratio greater than 70%) can achieve higher selectivity for silicon oxide and suppress the reaction of aluminum oxide. If the second dielectric layer 3 is aluminum oxide, a mixture of chlorine, BCl3, and argon is used for dry etching. Increasing the chlorine ratio (for example, to 70%-90%) while maintaining a low etching gas pressure (5mTorr-15mTorr) can increase the aluminum oxide etch rate.
[0050] When the first dielectric layer 1 and the second dielectric layer 3 are one of silicon nitride and gallium nitride: when the second dielectric layer 3 is gallium nitride, the etching gas is selected as a mixture of chlorine, BCl3 and argon, the plasma ICP power is 400W-500W, the bias power is 150W-200W, the temperature is 25℃-150℃, the etching gas pressure is maintained at low pressure (5mTorr-15mTorr), the ratio of chlorine, BCl3 and argon is 8:1:1, and the etching selectivity ratio of gallium nitride / silicon nitride is greater than 10:1. When the second dielectric layer 3 is silicon nitride, the etching gas is a mixture of CF4, CHF3 and oxygen, the plasma ICP power is 200W-300W, the bias power is 100W-150W, the temperature is 10℃-50℃, the etching gas pressure is maintained at 20mTorr-30mTorr, and the gas ratio of CF4, CHF3 and oxygen is 7:2:1, which can achieve an etching selectivity ratio of silicon nitride / gallium nitride greater than 8:1.
[0051] When the first dielectric layer 1 and the second dielectric layer 3 are either silicon nitride or aluminum oxide: When the second dielectric layer 3 is aluminum oxide, the etching gas is a mixture of CF4, NF3, O2, and N2. CF4 and NF3 provide fluorine atoms that react with aluminum oxide to form volatile AlF3. Silicon nitride forms a passivation layer in an oxygen and nitrogen environment to inhibit etching. The ratio of CF4, NF3, O2, and N2 is 5:2:2:1. The gas pressure is maintained at 5mTorr-15mTorr, the plasma ICP power is 300W-400W, the bias power is 100W-150W, and the temperature is 80°C-110°C. When the second dielectric layer 3 is silicon nitride, the etching gas is a mixture of Cl2, BCl3, SF6, and O2. Cl2 or BCl3 reacts with silicon nitride to form volatile SiCl4 and NH3. Al2O3 forms a surface passivation layer in an oxygen environment to inhibit the reaction. The ratio of etching gases Cl2, BCl3, SF6 and O2 is: 6:2:1:1, the plasma ICP power is 400W-500W, the bias power is 200W-250W, the temperature is 10℃-50℃, and the etching gas pressure is maintained at medium (20mTorr-30mTorr), which can achieve an etching selectivity of silicon nitride / aluminum oxide exceeding 10:1.
[0052] When the first dielectric layer 1 and the second dielectric layer 3 are either gallium nitride or aluminum oxide: When the second dielectric layer 3 is aluminum oxide, the etching gas is a mixture of CF4, NF3, and oxygen. CF4 and NF3 provide fluorine atoms that react with aluminum oxide to form volatile AlF3. However, the surface of gallium nitride is passivated in an oxygen environment, inhibiting the reaction. The ratio of CF4, NF3, and oxygen is 6:2:2, the plasma ICP power is 300W-400W, the bias power is 100W-150W, the temperature is 10°C-50°C, and the etching gas pressure is maintained at 5mTorr-15mTorr. This achieves an aluminum oxide / gallium nitride etching selectivity greater than 10:1. When the second dielectric layer 3 is gallium nitride, the etching gas is a mixture of Cl2, BCl3, and argon. Cl2 and BCl3 react with gallium nitride to form volatile GaCl3. Aluminum oxide is chemically stable in chlorine. The ratio of Cl2, BCl3 and argon is 7:2:1, the plasma ICP power is 400W-500W, the bias power is 200W-250W, the temperature is 25℃-150℃, and the etching gas low pressure is maintained at 5mTorr-15mTorr, which can achieve a gallium nitride / aluminum oxide etching selectivity greater than 15:1.
[0053] Based on the above description, different etching methods can be selected based on the material differences between the first dielectric layer 1 and the second dielectric layer 3 to control the etching selectivity of the first dielectric layer 1 and the second dielectric layer 3. In the present invention, the etching selectivity of the second dielectric layer 3 to the first dielectric layer 1 is at least greater than 5. A high etching selectivity is beneficial for preserving the first dielectric layer 1 and protecting the walls of the vertical micropores 4.
[0054] The present invention controls the etching selectivity and etching time to control the etching range of the second dielectric layer 3. The present invention can control the over-etching amount (after the second dielectric layer 3 outside the vertical micropore 4 is completely etched, due to the high etching selectivity, the first dielectric layer 1 outside the vertical micropore 4 is etched very slowly, and only the second dielectric layer 3 inside the vertical micropore 4 is etched significantly. The etching of the second dielectric layer 3 inside the vertical micropore 4 is called "over-etching"), thereby controlling the tilt angle of the second dielectric layer inside the vertical micropore. When the over-etching amount increases (the second dielectric layer 3 inside the vertical micropore 4 is over-etched), the tilt angle of the second dielectric layer 3 inside the vertical micropore 4 becomes smaller and closer to vertical, and vice versa.
[0055] The structure of the inclined micropore 2 after etching in step 4 is as follows Figure 2 As shown in c, the SEM image of the inclined micropore 2 structure is as follows Figure 3 As shown, it can be seen that the inclined micropore 2 structure manufactured by the micropore structure manufacturing method of the present invention has a better inclination angle.
[0056] The above describes in detail the method for manufacturing an inclined microporous structure provided by the present invention. Specific examples are used herein to illustrate the structure and operating principles of the present invention. The description of the above embodiments is intended only to facilitate understanding of the method and core concept of the present invention. It should be noted that those skilled in the art may make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications fall within the scope of protection of the claims of the present invention.
Claims
1. A method for manufacturing an inclined microporous structure, characterized in that: The method comprises etching vertical micropores on a first dielectric layer, and depositing a second dielectric layer made of a material different from that of the first dielectric layer on the inner wall of the vertical micropore and the surface of the first dielectric layer; The second dielectric layer is etched using an etching process in which the etching rate of the second dielectric layer is greater than the etching rate of the first dielectric layer, thereby removing the second dielectric layer on the surface of the first dielectric layer and at the bottom of the vertical micropore, and leaving the inclined second dielectric layer in the vertical micropore. The vertical micropore and the second dielectric layer in the vertical micropore together form the desired inclined micropore structure.
2. The method for manufacturing an inclined microporous structure according to claim 1, characterized in that: The first dielectric layer is any one of silicon oxide, silicon nitride, gallium nitride or aluminum oxide grown by LPCVD process or PECVD process.
3. The method for manufacturing an inclined microporous structure according to claim 2, characterized in that: The thickness of the first dielectric layer is 10 nm-5 um.
4. The method for manufacturing an inclined microporous structure according to claim 1, characterized in that: The method for forming the vertical microholes on the first dielectric layer includes spin coating photoresist on the surface of the first dielectric layer, photoetching the positions of the vertical microholes, and etching the first dielectric layer using a dry etching method.
5. The method for manufacturing an inclined microporous structure according to claim 4, characterized in that: After the vertical micropores are formed, the photoresist on the surface of the first dielectric layer is removed, and then the second dielectric layer is deposited.
6. The method for manufacturing an inclined microporous structure according to claim 1, characterized in that: The second dielectric layer is any one of silicon oxide, silicon nitride, gallium nitride or aluminum oxide grown by LPCVD process or PECVD process.
7. The method for manufacturing an inclined microporous structure according to claim 6, characterized in that: The thickness of the second dielectric layer is 7nm-3.5um.
8. The method for manufacturing an inclined microporous structure according to claim 1, characterized in that: The thickness of the second dielectric layer is 50%-90% of the thickness of the first dielectric layer.
9. The method for manufacturing an inclined microporous structure according to claim 1, characterized in that: The second dielectric layer is etched using a dry etching process, and the ratio of the etching rate of the second dielectric layer to the etching rate of the first dielectric layer is at least greater than 5.
10. The method for manufacturing an inclined microporous structure according to claim 1, characterized in that: The tilt angle of the second dielectric layer in the vertical micropore is achieved by controlling the over-etching amount. As the over-etching amount increases, the tilt angle of the second dielectric layer in the vertical micropore decreases.