Method of manufacturing a semiconductor structure and semiconductor structure
By depositing a diffusion barrier layer, an aluminum layer, and an anti-reflection layer on the trench surface of the aluminum pad substrate, and using a sputtering process to migrate the anti-reflection layer to the sidewall, depositing metallic titanium to form a titanium-aluminum compound and etching, the problem of sharp protrusions on the surface of the aluminum pad is solved, achieving surface smoothing and improved reliability of the aluminum pad, and reducing the risk of wafer damage.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NEXCHIP SEMICON CO LTD
- Filing Date
- 2025-12-25
- Publication Date
- 2026-06-09
AI Technical Summary
In traditional physical vapor deposition (PVD) processes, the crystallization characteristics of aluminum and the geometric constraints of the trench contours during the formation of aluminum pads result in sharp, "inverted horn"-like protrusions, which can cause plasma discharge and wafer damage. Furthermore, heat treatment methods may introduce aluminum whisker defects, affecting chip packaging yield and reliability.
A diffusion barrier layer, an aluminum layer, and an anti-reflection layer are sequentially deposited on the trench surface of an aluminum pad substrate. The anti-reflection layer is then migrated to the sidewall using a sputtering process. Metallic titanium is deposited to form a titanium-aluminum compound, and the protruding structure is removed by wet etching with hydrofluoric acid. The amount of titanium deposition is optimized by combining multiple deposition-etching cycles to form a continuous titanium-aluminum compound layer to smooth the bottom of the trench.
It effectively flattens the surface of aluminum pads, improves packaging yield, reduces wafer damage risk, enhances sidewall damage resistance, and improves the surface flatness and reliability of aluminum pads.
Smart Images
Figure CN121398647B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a method for manufacturing a semiconductor structure and a semiconductor structure. Background Technology
[0002] In semiconductor manufacturing processes, aluminum pads serve as a crucial interface connecting internal chip circuitry to external wires, and their surface morphology directly impacts device packaging yield and long-term reliability. During traditional physical vapor deposition (PVD) processes, the crystallinity of aluminum and the geometric constraints of the trench profile often result in sharp, "inverted horn"-like protrusions within the trenches. This non-ideal morphology not only triggers plasma arcing in subsequent chemical vapor deposition (CVD) processes, leading to severe surface defects, but can also damage the wafer due to concentrated local electric fields. While the industry has attempted to utilize aluminum's low melting point through heat treatment to achieve surface smoothing, the additional thermal budget can induce aluminum whisker defects, further exacerbating reliability risks. Summary of the Invention
[0003] In view of the above problems, the purpose of this application is to provide a method for manufacturing a semiconductor structure and a semiconductor structure, which aims to flatten the sharp, "inverted horn"-like protrusions in the trenches of the aluminum pad substrate, improve the surface flatness and reliability of the manufactured aluminum pad, thereby improving the chip packaging yield and reducing the risk of wafer damage.
[0004] According to a first aspect of the embodiments of this application, a method for manufacturing a semiconductor structure is provided, comprising:
[0005] A diffusion barrier layer, an aluminum layer, and an anti-reflection layer are sequentially deposited on the surface of a trench in an aluminum pad base, wherein the aluminum layer forms a raised structure in the trench.
[0006] The anti-reflective layer material located at the bottom of the trench is migrated to the sidewall of the trench using a sputtering process, so as to expose the aluminum layer at the bottom of the trench;
[0007] Metallic titanium is deposited on the exposed aluminum layer surface at the bottom of the trench to form a titanium-aluminum compound;
[0008] The titanium-aluminum compound was removed by a hydrofluoric acid wet etching process to smooth the protruding structure;
[0009] The anti-reflective layer material is redeposited on the surface of the aluminum layer at the bottom of the trench.
[0010] Optionally, the aluminum pad base includes a copper interconnect layer and a dielectric layer, with the copper interconnect layer exposed at the bottom of the trench.
[0011] Optionally, before sequentially depositing the diffusion barrier layer, the aluminum layer, and the anti-reflective layer on the trench surface in the aluminum pad substrate, the manufacturing method further includes:
[0012] The copper interconnect layer is formed on a semiconductor substrate;
[0013] The dielectric layer is formed on the copper interconnect layer, the dielectric layer comprising a passivation layer and a dielectric layer stacked sequentially from the bottom to the top of the trench;
[0014] The dielectric layer is etched to expose the copper interconnect layer, forming the trench.
[0015] Optionally, the diffusion barrier layer material includes tantalum nitride, and the antireflective layer material includes titanium nitride.
[0016] Alternatively, hydrofluoric acid can be used to etch titanium aluminum compounds at a higher rate than it can etch titanium nitride.
[0017] Optionally, prior to depositing metallic titanium on the exposed aluminum layer surface at the bottom of the trench to form a titanium-aluminum compound, the manufacturing method further includes:
[0018] During the process development phase:
[0019] A diffusion barrier layer, an aluminum layer, and an anti-reflection layer are sequentially deposited on the surface of a trench in an aluminum pad base of multiple test samples, wherein the aluminum layer forms a test protrusion structure in the trench;
[0020] The anti-reflective layer material at the bottom of the trench of the test sample is migrated to the sidewall of the trench using a sputtering process, so as to expose the aluminum layer at the bottom of the trench;
[0021] Multiple deposition-etching cycles were performed on the test sample to gradually smooth the test protrusion structure, and the total amount of titanium deposited in each cycle was accumulated.
[0022] Optionally, each deposition-etching cycle includes:
[0023] A quantitative amount of metallic titanium is deposited on the surface of the exposed aluminum layer at the bottom of the trench in the test sample to form a titanium-aluminum compound;
[0024] Hydrofluoric acid wet etching process was used to remove titanium-aluminum compounds;
[0025] Measure the angle between the highest and lowest points of the test protrusion structure;
[0026] When the included angle is detected to be less than a preset threshold, the total amount of titanium deposited in each cycle is accumulated.
[0027] Optionally, depositing metallic titanium on the exposed aluminum layer surface at the bottom of the trench to form a titanium-aluminum compound includes:
[0028] During mass production:
[0029] Based on the total deposition amount, metallic titanium of the total deposition amount is deposited in a single step on the exposed aluminum layer surface at the bottom of the trench of the mass-produced product to form a titanium-aluminum compound.
[0030] Optionally, the passivation layer material comprises silicon carbonitride, and the dielectric layer material comprises tetraethoxysilane.
[0031] According to a second aspect of the embodiments of this application, a semiconductor structure is provided, which is manufactured according to the manufacturing method described above.
[0032] The unexpected technical effect of this application is:
[0033] A diffusion barrier layer, an aluminum layer, and an anti-reflective layer are sequentially deposited on the surface of the trench in the aluminum pad substrate. The aluminum layer forms a sharp, "inverted horn"-like protrusion in the trench. The anti-reflective layer material located at the bottom of the trench is migrated to the trench sidewall using a sputtering process to expose the aluminum layer at the bottom. Metallic titanium is deposited on the exposed aluminum layer surface at the bottom of the trench to form a titanium-aluminum compound. A hydrofluoric acid wet etching process is used to remove the titanium-aluminum compound to smooth the protrusion structure. The anti-reflective layer material is then redeposited on the aluminum layer surface at the bottom of the trench. Thus, during the sputtering process, the pre-cleaned chamber is re-sputtered with argon gas. The re-sputter function precisely bombards the anti-reflective layer at the bottom of the trench with a high-energy argon ion beam, causing the titanium nitride material at the bottom of the trench to migrate directionally and redeposit on the trench sidewalls. This material redistribution process not only effectively exposes the aluminum layer surface at the bottom of the trench but also forms a dual protection mechanism by increasing the thickness of the anti-reflective layer on the sidewalls: it enhances the plasma damage resistance of the sidewalls and avoids the erosion of the sidewall dielectric layer during the hydrofluoric acid wet etching process. Subsequently, during the selective deposition of the titanium layer on the exposed aluminum surface at the bottom of the trench, the bias parameter is precisely controlled to allow titanium atoms to preferentially react with aluminum in the protruding structural regions, forming a titanium aluminum compound (TiAlx) with a gradient composition distribution. Taking advantage of the significant difference in etching rate of the titanium aluminum compound by hydrofluoric acid compared to titanium nitride and pure aluminum, the sharp, "inverted horn"-like protrusions can be directionally removed without damaging the sidewall protective layer. Through multi-step synergistic action, the controllable flatness of the aluminum layer at the bottom of the trench was achieved, which improved the surface flatness and reliability of the manufactured aluminum pad, thereby increasing the chip packaging yield and reducing the risk of wafer damage.
[0034] In addition, in this application, during the process development stage, multiple deposition-etching cycles are performed on the test samples to progressively smooth the protruding structure. The total amount of titanium deposited in each cycle is accumulated. Through multiple deposition-etching cycles, a quantitative relationship model is established between the total amount of titanium deposited and the degree of morphological improvement of the sharp, "inverted horn" protruding structure. Based on the accumulated total amount of deposition, in the mass production stage, a single deposition process can be directly used to precisely control the titanium layer thickness at this total amount of deposition, allowing titanium and aluminum to fully react at the interface to form a continuous titanium-aluminum compound layer. After being processed by hydrofluoric acid wet etching, an aluminum pad structure with ideal flatness can be obtained. This further facilitates the controllable flatness of the aluminum layer at the bottom of the trench, improves the surface flatness and reliability of the manufactured aluminum pad, thereby improving the chip packaging yield and reducing the risk of wafer damage. Attached Figure Description
[0035] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:
[0036] Figure 1A The image shown is a cross-sectional schematic diagram of a semiconductor structure in the related art;
[0037] Figure 1B The image shown is a cross-sectional schematic diagram of a semiconductor structure in the related art;
[0038] Figure 2 The diagram shown is a cross-sectional schematic of an exemplary semiconductor structure according to an embodiment of this application;
[0039] Figure 3 The diagram shown is a schematic flowchart of an exemplary semiconductor structure manufacturing method according to an embodiment of this application.
[0040] Figures 4A-4G The diagram shown is a cross-sectional schematic of different stages of an exemplary semiconductor structure manufacturing method according to an embodiment of this application;
[0041] Figure 5 The diagram shown is a cross-sectional schematic of different stages of an exemplary multiple deposition-etching cycle process according to an embodiment of this application.
[0042] Explanation of reference numerals in the attached figures: 110-Copper interconnect layer; 120-Dielectric layer; 130-Diffusion barrier layer; 140-Aluminum layer; 150-Antireflective layer; 101-First protrusion structure; 121-Passivation layer; 122-Dielectric layer; 260-Titanium metal; 261-Titanium aluminum compound; 201-Second protrusion structure; 501-Test protrusion structure. Detailed Implementation
[0043] The present application will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale. Furthermore, some well-known parts may not be shown.
[0044] This application may be presented in various forms, some of which will be described below.
[0045] It should be noted that, for ease of illustration, some film layers are omitted in the accompanying drawings of this application. The spacing and line width in the drawings are used to illustrate the corresponding components and the relative positional relationship between components; the actual spacing and line width shall conform to the process specifications.
[0046] Figure 1A and Figure 1B The image shows a cross-sectional schematic diagram of a semiconductor structure in related technologies. In the field of integrated circuit manufacturing, aluminum pads can be used as test terminals for probe card connections and soldering points for chip package pins during back-end testing. Aluminum pads play a crucial role in signal transmission and usage during product testing. For example... Figure 1A and Figure 1B As shown, in a conventional aluminum pad manufacturing process, an aluminum pad base is disposed on a semiconductor substrate. The aluminum pad base includes a copper interconnect layer 110 and a dielectric layer 120. The dielectric layer 120 includes a passivation layer 121 and a dielectric layer 122. By etching the dielectric layer 120 to expose the copper interconnect layer 110, a trench for depositing the aluminum pad is formed, with the copper interconnect layer 110 exposed at the bottom of the trench. For example, the trench depth is approximately 700 nm, the diameter at the bottom of the trench is approximately 2700 nm, and the diameter at the top of the trench is approximately 3000 nm. A diffusion barrier layer 130, an aluminum layer 140, and an anti-reflection layer 150 are sequentially deposited on the trench surface in the aluminum pad base. For example, the thickness of the aluminum layer 140 is approximately 1400 nm. During the formation of the aluminum pad, due to the combined effect of the crystallization characteristics of the aluminum material and the geometric constraints of the trench profile, a sharp, "inverted horn"-like first protrusion structure 101 is often formed in the trench. The angle θ between the highest point A and the lowest point B of the first protrusion structure 101 is relatively large, typically between 110° and 150°. This non-ideal sharp morphology can easily induce local electric field concentration during the subsequent deposition of the passivation layer 121 using plasma-enhanced chemical vapor deposition (PECVD), leading to micro-arc discharge, causing burns on the aluminum pad surface or breakdown of the dielectric layer, resulting in severe surface defects. It may also damage the wafer due to local electric field concentration. Although the industry has attempted to alleviate this morphology by reflowing aluminum at high temperatures (>400 °C), the additional thermal budget can induce aluminum whisker defects, which in turn exacerbates reliability risks.
[0047] Based on this, the present application proposes a new method for manufacturing a semiconductor structure and a semiconductor structure, which flattens the sharp, "inverted horn"-like protrusions in the trenches of the aluminum pad base, improves the surface flatness and reliability of the manufactured aluminum pad, thereby improving the chip packaging yield and reducing the risk of wafer damage.
[0048] Figure 2 The diagram shown is a cross-sectional schematic of an exemplary semiconductor structure according to an embodiment of this application. Figure 2 As shown, in the aluminum pad manufacturing process of this application embodiment, an aluminum pad base is disposed on a semiconductor substrate. The aluminum pad base includes a copper interconnect layer 110 and a dielectric layer 120. The dielectric layer 120 includes a passivation layer 121 and a dielectric layer 122. The passivation layer 121 is made of, for example, silicon carbonitride (SiCN), and the dielectric layer 122 is made of, for example, tetraethoxysilane (TEOS). By etching the dielectric layer 120 to expose the copper interconnect layer 110, a trench for depositing the aluminum pad is formed, with the bottom of the trench exposing the copper interconnect layer 110. For example, the depth of the trench is approximately 700 nm, the diameter of the bottom of the trench is approximately 2700 nm, and the diameter of the top of the trench is approximately 3000 nm. A diffusion barrier layer 130, an aluminum layer 140, and an anti-reflection layer 150 are sequentially deposited on the surface of the trench in the aluminum pad base. For example, the thickness of the aluminum layer 140 is approximately 1400 nm. The diffusion barrier layer 130 is made of materials such as tantalum nitride (TaN), and the anti-reflective layer 150 is made of materials such as titanium nitride (TiN). The aluminum layer 140 forms a sharp, "inverted horn"-like second protrusion structure 201 in the trench. In subsequent aluminum pad manufacturing processes, the anti-reflective layer material located at the bottom of the trench is migrated to the trench sidewalls via sputtering to expose the aluminum layer 140 at the bottom of the trench. Metallic titanium is deposited on the exposed aluminum layer surface at the bottom of the trench to form a titanium-aluminum compound (TiAlx). The titanium-aluminum compound is removed using a hydrofluoric acid wet etching process to planarize the second protrusion structure 201. Subsequently, the anti-reflective layer material is redeposited on the aluminum layer surface at the bottom of the trench. Compared to... Figure 1A and Figure 1B The angle θ between the highest point A and the lowest point B of the first protrusion structure 101 shown in the embodiment of this application, which is flattened, is reduced. For example, the angle θ can be adjusted to 0° by adjusting the process parameters.
[0049] Figure 3 The diagram shown is a schematic flowchart of an exemplary semiconductor structure manufacturing method according to an embodiment of this application. Figures 4A-4G The diagram shown is a cross-sectional schematic of different stages of an exemplary semiconductor structure manufacturing method according to an embodiment of this application. The following is in conjunction with... Figure 3 and Figures 4A-4G The manufacturing process of the aluminum pads in the embodiments of this application is described in detail. For example... Figure 3 As shown, the method for manufacturing a semiconductor structure includes:
[0050] In step S310, a diffusion barrier layer, an aluminum layer, and an anti-reflection layer are sequentially deposited on the surface of the trench in the aluminum pad base, wherein the aluminum layer forms a raised structure in the trench.
[0051] In some embodiments, such as Figure 4A As shown, an aluminum pad substrate is disposed on a semiconductor substrate. The aluminum pad substrate includes a copper interconnect layer 110 and a dielectric layer 120. The dielectric layer 120 includes a passivation layer 121 and a dielectric layer 122. The passivation layer 121 is made of, for example, silicon carbonitride (SiCN), and the dielectric layer 122 is made of, for example, tetraethoxysilane (TEOS). By etching the dielectric layer 120 to expose the copper interconnect layer 110, a trench for depositing the aluminum pad is formed, with the bottom of the trench exposing the copper interconnect layer 110. In some embodiments, prior to step S310, the semiconductor structure manufacturing method further includes: forming a copper interconnect layer 110 on a semiconductor substrate, forming a dielectric layer 120 on the copper interconnect layer 110, the dielectric layer 120 including a passivation layer 121 and a dielectric layer 120 sequentially stacked in the direction from the bottom to the top of the trench, and etching the dielectric layer 120 to expose the copper interconnect layer 110 to form a trench. For example, the trench depth is approximately 700 nm, the diameter at the bottom of the trench is approximately 2700 nm, and the diameter at the top of the trench is approximately 3000 nm. In some embodiments, a diffusion barrier layer 130, an aluminum layer 140, and an anti-reflective layer 150 are sequentially deposited on the trench surface in the aluminum pad substrate. For example, the thickness of the aluminum layer 140 is approximately 1400 nm. The diffusion barrier layer 130 is made of, for example, tantalum nitride (TaN), and the anti-reflective layer 150 is made of, for example, titanium nitride (TiN). The aluminum layer 140 forms a sharp, "inverted horn"-like second protrusion structure 201 in the trench. The angle θ between the highest point A and the lowest point B of the second protrusion structure 201 is relatively large, typically between 110° and 150°.
[0052] In step S320, the anti-reflective layer material located at the bottom of the trench is migrated to the sidewall of the trench by a sputtering process, so as to expose the aluminum layer at the bottom of the trench.
[0053] In some embodiments, such as Figure 4B and Figure 4CAs shown, the anti-reflective layer 150 at the bottom of the trench is directionally bombarded using a high-energy argon ion beam via the argon re-sputter function of the pre-cleaning chamber. This sputtering process causes physical migration of the bottom titanium nitride material, with some material redepositing onto the trench sidewalls, forming a thickened anti-reflective layer 150 on the sidewalls. This material redistribution process not only precisely exposes the aluminum layer surface at the bottom of the trench but also constructs a dual protective barrier through the thickened anti-reflective layer 150 on the sidewalls: on the one hand, it enhances the sidewalls' resistance to damage from subsequent plasma processes; on the other hand, it avoids the erosion of the sidewall dielectric layer during the hydrofluoric acid wet etching process. After sputtering, the aluminum layer surface at the bottom of the trench exhibits a regular exposed area, providing a controllable reaction interface for subsequent titanium deposition processes.
[0054] In step S330, metallic titanium is deposited on the exposed aluminum layer surface at the bottom of the trench to form a titanium-aluminum compound.
[0055] In some embodiments, such as Figure 4D and Figure 4E As shown, metallic titanium 260 is deposited on the exposed aluminum layer surface at the bottom of the trench to form a titanium-aluminum compound 261. Specifically, physical vapor deposition (PVD) or ionized metal plasma (IMP) PVD processes are used. By precisely controlling the bias power (preferably 500-1500 W), titanium atoms preferentially react with aluminum in the protruding structural region, forming a titanium-aluminum compound layer (TiAlx) with a gradient composition distribution. The thickness of this compound layer is positively correlated with the titanium deposition time, and the titanium-aluminum atomic ratio can be controllably adjusted within the range of 1:1 to 1:3 through process window optimization. During deposition, the reaction between titanium atoms and the aluminum layer exhibits self-limiting characteristics. Due to the surface energy difference, a continuous titanium-aluminum compound layer preferentially forms on the top of the second protruding structure 201, while the flat area maintains a titanium / aluminum bilayer structure. This selective reaction mechanism provides an ideal etching selectivity basis for subsequent etching processes, ensuring the directional removal of sharp morphologies.
[0056] In step S340, a hydrofluoric acid wet etching process is used to remove the titanium-aluminum compound in order to smooth the protruding structure.
[0057] In some embodiments, such as Figure 4FAs shown, a hydrofluoric acid wet etching process is used to remove the titanium-aluminum compound 261 to smooth the second protrusion structure 201. Specifically, a titanium-deposited wafer is immersed in a diluted hydrofluoric acid solution (e.g., with a concentration of 2%-5%) and selectively etched at room temperature. Since the etching rate of hydrofluoric acid on titanium-aluminum compounds (>8 Å / s) is significantly higher than that on titanium nitride (<0.05 Å / s) and pure aluminum (<2 Å / s), this process preferentially removes the titanium-aluminum compound layer formed in the protrusion structure region, while the anti-reflective layer 150 after trench sidewall migration experiences only minor loss. During etching, the sharp "inverted horn" morphology gradually becomes smoother as the titanium-aluminum compound is directionally removed, eventually forming a continuous and smooth aluminum layer surface at the bottom of the trench. Measurements show that the angle θ between the highest point A and the lowest point B of the treated second protrusion structure 201 can be reduced to the range of 5° to 15°, an improvement of over 80% compared to conventional processes. This etching process also has a self-terminating characteristic. When the exposed aluminum layer surface reaches the ideal flatness, the titanium-aluminum reaction interface disappears, causing the etching rate to drop sharply, thereby avoiding damage to the aluminum layer caused by excessive etching.
[0058] In step S350, the anti-reflective layer material is redeposited on the surface of the aluminum layer at the bottom of the trench.
[0059] In some embodiments, such as Figure 4G As shown, an anti-reflective layer material is redeposited on the surface of the aluminum layer at the bottom of the trench. Specifically, a new titanium nitride layer is formed on the planarized aluminum layer surface using physical vapor deposition (PVD). This layer not only restores the anti-reflective function to meet the requirements of subsequent photolithography processes but also reconstructs a complete dielectric protection barrier through uniform coverage. The redeposited anti-reflective layer material forms a continuous encapsulation structure with the thickened anti-reflective layer that migrates to the trench sidewalls. This step-by-step anti-reflective layer reconstruction scheme ensures the electrical performance of the aluminum pad while optimizing structural stability through material redistribution, ultimately resulting in a semiconductor aluminum pad structure with excellent flatness and reliability.
[0060] It should be noted that the thickness of the titanium-aluminum compound formed by depositing metallic titanium on the exposed aluminum layer surface at the bottom of the trench is positively correlated with the titanium deposition time. The longer the titanium deposition time, the greater the total amount of titanium deposited, the thicker the titanium-aluminum compound, and the smaller the angle θ between the highest point A and the lowest point B of the second protrusion structure 201 after the titanium-aluminum compound is removed by hydrofluoric acid wet etching. Therefore, during the process development stage, multiple deposition-etching cycles can be performed on the test samples to progressively smooth the test protrusion structure, accumulating the total amount of metallic titanium deposited in each cycle. Then, during the mass production stage, based on the accumulated total amount of deposition, the total amount of metallic titanium is deposited at once on the exposed aluminum layer surface at the bottom of the trench of the mass-produced product to form a titanium-aluminum compound, which is then removed by hydrofluoric acid wet etching, ultimately obtaining a semiconductor aluminum pad structure with excellent flatness and reliability.
[0061] Figure 5 The diagram shown is a cross-sectional schematic of different stages of an exemplary multiple deposition-etching cycle process according to an embodiment of this application.
[0062] In some embodiments, during the process development phase, a diffusion barrier layer 130, an aluminum layer 140, and an anti-reflective layer 150 are sequentially deposited on the surface of trenches in aluminum pad substrates of multiple test samples. The aluminum layer 140 forms a test protrusion structure 501 in the trench. The anti-reflective layer material at the bottom of the trench of the test sample is migrated to the trench sidewalls using a sputtering process to expose the aluminum layer 140 at the bottom of the trench. Multiple deposition-etching cycles are performed on the test samples to successively planarize the test protrusion structure 501, accumulating the total amount of titanium deposited in each cycle. Figure 5 As shown, n (n is a positive integer) deposition-etching cycles were performed on the test sample to successively smooth the test protrusion structure 501, and the total amount of titanium deposited in each cycle was accumulated. In each deposition-etching cycle, a fixed amount of titanium 260 was deposited on the exposed aluminum layer surface at the bottom of the trench of the test sample to form titanium-aluminum compound 261. The titanium-aluminum compound 261 was removed by a hydrofluoric acid wet etching process, and the angle θ between the highest point A and the lowest point B of the test protrusion structure 501 was measured. When the angle θ was found to be less than a preset threshold, the total amount of titanium deposited in each cycle was accumulated.
[0063] Understandably, during the process development phase, a quantitative model of the relationship between the total amount of titanium deposition and the degree of morphology improvement can be established by systematically adjusting the number of deposition-etching cycles. Specifically, a single deposition process is first performed on the test sample, followed by etching using a hydrofluoric acid wet etching process, and the change in the angle θ of the protrusion structure after treatment is measured. This process is repeated until the angle θ reaches a preset threshold, and the cumulative amount of titanium deposition in each cycle is the optimal parameter required for mass production. This experimental design method can accurately capture the reaction kinetics of the titanium / aluminum interface: in the initial cycle, titanium atoms preferentially react with aluminum at the top of the protrusion, forming discrete titanium-aluminum compound island structures; as the number of cycles increases, the cumulative effect of the total amount of titanium deposition causes the reaction interface to expand from the tip to the periphery, eventually forming a continuous titanium-aluminum compound layer at the bottom of the trench. By controlling the deposition thickness of titanium in each cycle, micron-level control of the morphology evolution process can be achieved, ensuring that the crystal structure integrity of the aluminum layer is maintained while eliminating sharp protrusions.
[0064] Understandably, based on the total deposition amount accumulated during the process development stage, the titanium layer thickness can be precisely controlled at this total deposition amount using a single deposition process during mass production. This allows titanium and aluminum to fully react at the interface to form a continuous titanium-aluminum compound layer. After being processed by hydrofluoric acid wet etching, an aluminum pad structure with ideal flatness can be obtained. This further facilitates the controllable flattening of the aluminum layer at the bottom of the trench, improves the surface flatness and reliability of the manufactured aluminum pad, thereby increasing the chip packaging yield and reducing the risk of wafer damage.
[0065] Finally, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The embodiments described above, as per the implementation of this application, do not exhaustively describe all details, nor do they limit the application to only the specific embodiments described. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this application, thereby enabling those skilled in the art to make good use of this application and modifications based on it. This application is limited only by the claims and their full scope and equivalents.
Claims
1. A method for manufacturing a semiconductor structure, comprising: A diffusion barrier layer, an aluminum layer, and an anti-reflection layer are sequentially deposited on the surface of a trench in an aluminum pad base, wherein the aluminum layer forms a raised structure at the bottom of the trench. The anti-reflective layer material located at the bottom of the trench is migrated to the sidewall of the trench using a sputtering process, so as to expose the aluminum layer at the bottom of the trench; Metallic titanium is deposited on the exposed aluminum layer surface at the bottom of the trench to form a titanium-aluminum compound; The titanium-aluminum compound was removed by a hydrofluoric acid wet etching process to smooth the protruding structure; The anti-reflective layer material is redeposited on the surface of the aluminum layer at the bottom of the trench.
2. The manufacturing method according to claim 1, wherein, The aluminum pad base includes a copper interconnect layer and a dielectric layer, with the copper interconnect layer exposed at the bottom of the trench.
3. The manufacturing method according to claim 2, wherein, Before sequentially depositing the diffusion barrier layer, the aluminum layer, and the anti-reflection layer on the trench surface in the aluminum pad substrate, the manufacturing method further includes: The copper interconnect layer is formed on a semiconductor substrate; The dielectric layer is formed on the copper interconnect layer, the dielectric layer comprising a passivation layer and a dielectric layer stacked sequentially from the bottom to the top of the trench; The dielectric layer is etched to expose the copper interconnect layer, forming the trench.
4. The manufacturing method according to claim 1, wherein, The diffusion barrier layer material includes tantalum nitride, and the antireflective layer material includes titanium nitride.
5. The manufacturing method according to claim 4, wherein, Hydrofluoric acid has a higher etching rate for titanium-aluminum compounds than for titanium nitride.
6. The manufacturing method according to claim 1, wherein, Prior to depositing metallic titanium on the exposed aluminum layer surface at the bottom of the trench to form a titanium-aluminum compound, the manufacturing method further includes: During the process development phase: A diffusion barrier layer, an aluminum layer, and an anti-reflection layer are sequentially deposited on the surface of a trench in an aluminum pad base of multiple test samples, wherein the aluminum layer forms a test protrusion structure in the trench; The anti-reflective layer material at the bottom of the trench of the test sample is migrated to the sidewall of the trench using a sputtering process, so as to expose the aluminum layer at the bottom of the trench; Multiple deposition-etching cycles are performed on the test sample to gradually smooth the test protrusion structure, and the total amount of titanium deposited in each cycle is accumulated. The deposition-etching cycle process includes alternating titanium deposition steps and titanium-aluminum compound etching steps.
7. The manufacturing method according to claim 6, wherein, Each deposition-etching cycle process includes: A quantitative amount of metallic titanium is deposited on the surface of the exposed aluminum layer at the bottom of the trench in the test sample to form a titanium-aluminum compound; Hydrofluoric acid wet etching process was used to remove titanium-aluminum compounds; Measure the angle between the highest and lowest points of the test protrusion structure; When the included angle is detected to be less than a preset threshold, the total amount of titanium deposited in each cycle is accumulated.
8. The manufacturing method according to claim 7, wherein, The deposition of metallic titanium on the exposed aluminum layer surface at the bottom of the trench to form a titanium-aluminum compound includes: During mass production: Based on the total deposition amount, metallic titanium of the total deposition amount is deposited in a single step on the exposed aluminum layer surface at the bottom of the trench of the mass-produced product to form a titanium-aluminum compound.
9. The manufacturing method according to claim 3, wherein, The passivation layer material includes silicon carbonitride, and the dielectric layer material includes tetraethoxysilane.
10. A semiconductor structure, said semiconductor structure being manufactured according to the manufacturing method according to any one of claims 1 to 9.