Rework methods for semiconductor structures and semiconductor structures with metal layer defects
By forming a protective layer in the semiconductor structure and performing a heat treatment process, the problem of aluminum mound protrusions caused by metal layer defects was solved, thereby improving yield and stabilizing the etching process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI HUAHONG GRACE SEMICON MFG CORP
- Filing Date
- 2026-02-27
- Publication Date
- 2026-05-26
AI Technical Summary
In metal layer operations, aluminum θ-Phase defects caused by heat treatment processes generate aluminum mound-like protrusion defects at high temperatures, affecting wafer yield and easily causing etching blockage in subsequent metal etching processes.
A protective layer is formed in the semiconductor structure to cover the hard mask layer. A thermal processing process is performed to eliminate type I defects in the metal layer. The metal layer is then protected by a dielectric anti-reflective coating to suppress the generation of type II defects.
Without adding extra steps, it effectively removes Type I defects and significantly reduces the generation of Type II defects, improving wafer yield and avoiding etching blockage.
Smart Images
Figure CN122094474A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of integrated circuit technology, and in particular to a semiconductor structure and a method for reworking a semiconductor structure with metal layer defects. Background Technology
[0002] In metal layer processing, if an alarm occurs and the wafer remains in the vacuum chamber, aluminum θ-phase may form. The aluminum θ-phase itself is hard and brittle. The continuous network of θ-phase at the grain boundaries significantly reduces the alloy's toughness and resistance to stress corrosion. During subsequent metal etching processes, block etch occurs, which is a localized "blockage" of etching, resulting in abnormal phenomena such as incomplete etching, residual metal, and uneven etching depth, thus affecting the wafer yield.
[0003] Figure 1 This is a schematic diagram of a protruding defect in a metal layer in the prior art. For wafers with Type I defects (aluminum θ-Phase defects) in the metal layer, rework is usually performed by heat treatment to eliminate the Type I defects in the metal layer and reduce the risk of low yield caused by the Type I defects. At the same time, due to the high process temperature during the heat treatment process, Type II defects 12a will be generated in the metal layer 12. The Type II defects are Hillock defects (mound-like protrusions). This will cause the upper adhesion layer 13 and hard mask layer 14 to bulge in sequence, which can easily cause etching blockage during subsequent metal etching processes, thereby affecting the wafer yield. Summary of the Invention
[0004] The purpose of this invention is to provide a semiconductor structure and a method for reworking a semiconductor structure with metal layer defects, in order to solve the problem that when the heat treatment process is used to eliminate aluminum θ-phase, the high temperature of the heat treatment process will cause aluminum hump-like protrusion defects in the metal layer.
[0005] To address the aforementioned technical problems, this invention provides a method for reworking a semiconductor structure with metal layer defects, comprising:
[0006] A semiconductor structure is provided, the semiconductor structure comprising a substrate, a metal layer and a hard mask layer stacked sequentially from bottom to top, wherein a first type of defect exists in the metal layer;
[0007] A protective layer is formed, which covers the hard mask layer;
[0008] A heat treatment process is performed to eliminate first-type defects within the metal layer, wherein the protective layer is used to protect the metal layer during the heat treatment process.
[0009] Optionally, the material of the metal layer includes aluminum.
[0010] Optionally, the first type of defect present in the metal layer includes the aluminum θ phase.
[0011] Optionally, the process temperature of the heat treatment process is 350°C to 450°C.
[0012] Optionally, the heat treatment process takes 60 to 180 seconds.
[0013] Optionally, the protective layer is a dielectric anti-reflective coating.
[0014] Optionally, the material of the hard mask layer includes titanium nitride.
[0015] Optionally, the protective layer is retained after the heat treatment process is performed; further comprising:
[0016] A photoresist layer is formed, which covers the protective layer;
[0017] Perform exposure and development processes to form a patterned photoresist layer;
[0018] An etching process is performed, using the patterned photoresist layer as a mask, to sequentially etch the protective layer, the hard mask layer, and the metal layer, with the remaining portion of the metal layer forming a metal interconnect structure.
[0019] Optionally, an adhesion layer may also be formed between the hard mask layer and the metal layer.
[0020] Based on the same inventive concept, the present invention also provides a semiconductor structure, wherein the rework method for a semiconductor structure with metal layer defects described in any of the preceding claims is employed, comprising:
[0021] Substrate;
[0022] A metal layer located on the substrate;
[0023] A hard mask layer, the hard mask layer being located on the metal layer;
[0024] A protective layer that covers the hard mask layer.
[0025] In the rework method for a semiconductor structure with metal layer defects provided by this invention, a semiconductor structure is provided, comprising a substrate, a metal layer, and a hard mask layer stacked sequentially from bottom to top. A first-type defect exists within the metal layer. A protective layer is formed, located on the hard mask layer. A thermal processing process is performed to eliminate the first-type defect within the metal layer. During the thermal processing, the protective layer protects the metal layer to suppress the formation of a second-type defect. This invention eliminates the first-type defect within the metal layer through a thermal processing process after the formation of the protective layer. The thermal processing temperature is relatively high. At high temperatures, aluminum is easily deformed by extrusion, generating protrusion defects (second-type defects), i.e., Hillock defects, in localized areas. The protective layer is less prone to deformation with increasing temperature; therefore, depositing the protective layer can suppress the formation of second-type defects in localized areas of the metal layer. The protective layer is a dielectric anti-reflective coating and does not need to be removed after the thermal processing. It is then used to form photoresist, serving as a dielectric anti-reflective coating in subsequent photolithography processes. The rework method for semiconductor structures with metal layer defects provided by this invention can remove the first type of metal layer defects while suppressing the generation of the second type of defects without adding extra steps, thereby reducing the risk of low yield caused by the second type of defects. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of a protruding defect in a metal layer in the prior art.
[0027] Figure 2 This is a flowchart of a rework method for a semiconductor structure with metal layer defects according to an embodiment of the present invention.
[0028] Figures 3 to 5 This is a schematic diagram illustrating the structural steps of a rework method for a semiconductor structure with metal layer defects according to an embodiment of the present invention. Wherein, Figure 3 This is a schematic diagram of the semiconductor structure after the hard mask layer is formed according to an embodiment of the present invention.
[0029] Figure 4 This is a schematic diagram of the semiconductor structure after the formation of the protective layer according to an embodiment of the present invention.
[0030] Figure 5 This is a schematic diagram of the semiconductor structure after the heat treatment process is performed according to an embodiment of the present invention.
[0031] Figure 1 In the middle: 12-metal layer; 12a-type second defect; 13-adhesion layer; 14-hard mask layer;
[0032] Figures 3 to 5In the middle: 20-substrate; 21-lower adhesion layer; 22-metal layer; 22a-second type defect; 22b-first type defect; 23-upper adhesion layer; 24-hard mask layer; 25-protective layer. Detailed Implementation
[0033] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the semiconductor structure proposed in this invention and the rework method for semiconductor structures with metal layer defects. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise scales, used only to facilitate and clarify the illustration of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structure. In particular, different figures may emphasize different aspects and sometimes use different scales.
[0034] Figure 2 This is a flowchart illustrating a rework method for a semiconductor structure with metal layer defects according to an embodiment of the present invention. Figure 2 As shown, this embodiment of the invention provides a rework method for a semiconductor structure with metal layer defects, comprising:
[0035] Step S10: A semiconductor structure is provided, the semiconductor structure comprising a substrate, a metal layer and a hard mask layer stacked sequentially from bottom to top, wherein there are first type defects in the metal layer;
[0036] Step S20: Form a protective layer that covers the hard mask layer;
[0037] Step S30: Perform a heat treatment process to eliminate first-type defects within the metal layer, wherein the protective layer is used to protect the metal layer during the heat treatment process.
[0038] Figures 3 to 5 This is a schematic diagram illustrating the structural steps of a rework method for a semiconductor structure with metal layer defects according to an embodiment of the present invention. To make the above-mentioned objectives, features, and beneficial effects of the present invention more apparent and understandable, the following description is provided in conjunction with the appendix to the specification. Figures 3 to 5 Specific embodiments of the present invention will be described in detail below.
[0039] Figure 3 This is a schematic diagram of the semiconductor structure after the formation of the hard mask layer according to an embodiment of the present invention. (Combined with...) Figure 3 Step S10 will be described below. Figure 3As shown, a semiconductor structure is provided, comprising a substrate 20. In some embodiments, the substrate 20 may be a semiconductor substrate made of any semiconductor material suitable for a semiconductor device. Specifically, the substrate 20 may be, for example, a bulk silicon substrate, a germanium substrate, a germanium-silicon substrate, an indium phosphide (InP) substrate, or a gallium arsenide (GaAs) substrate. In other embodiments, the substrate 20 may also be a silicon-on-insulator (SOI) substrate, a germanium-on-insulator substrate, or a germanium-silicon-on-insulator composite substrate. Those skilled in the art will understand that the substrate is not limited in any way, but can be selected according to the actual application. Various device (not limited to semiconductor device) components (not shown) may be formed in the substrate 20. The substrate 20 may also have other layers or components formed therein, such as shallow trench isolation structures, gate structures, contact holes, dielectric layers, metal interconnects, and vias, etc.
[0040] Please continue to refer to this. Figure 3 The semiconductor structure includes a metal layer 22 and a hard mask layer 24 stacked sequentially from bottom to top. A first-type defect 22b exists within the metal layer 22. A lower adhesion layer 21 is also formed between the substrate 10 and the metal layer 22. The material of the lower adhesion layer 21 is, for example, Ti (titanium). In some embodiments, a diffusion barrier layer is also formed between the lower adhesion layer 21 and the metal layer 22. The diffusion barrier layer is, for example, titanium nitride. An upper adhesion layer 23 is also formed between the metal layer 22 and the hard mask layer 24. The material of the hard mask layer 24 is, for example, titanium nitride, and it also functions as a diffusion barrier layer to prevent diffusion of the metal layer 22. The upper adhesion layer 23 and the hard mask layer 24 also have anti-reflection properties, reducing light reflection from the substrate during subsequent metal etching and photolithography processes to avoid standing wave effects and improve pattern accuracy. The material of the metal layer 22 is, for example, aluminum; therefore, the first-type defect 22b present within the metal layer 22 is, for example, an aluminum θ phase. The aluminum theta phase itself is hard and brittle; the continuous network of theta phase at the grain boundaries will significantly reduce the toughness and stress corrosion resistance of the alloy; during subsequent metal etching, block etch will occur. Block etch is a local etching that is "blocked", resulting in abnormal phenomena such as local incomplete etching, residual metal, and uneven etching depth, which will affect the yield of the device.
[0041] Figure 4 This is a schematic diagram of the semiconductor structure after the formation of the protective layer according to an embodiment of the present invention. (Combined with...) Figure 4 Step S20 will be described below. Figure 4As shown, a protective layer 25 is formed, which covers the hard mask layer 24; the protective layer 25 is a dielectric anti-reflective coating (DARC). The dielectric anti-reflective coating mainly includes polymer resin, light absorber, solvent and additives. At high temperatures, the protective layer 25 is not easily deformed with increasing temperature.
[0042] Figure 5 This is a schematic diagram of the semiconductor structure after undergoing a heat treatment process according to an embodiment of the present invention. (Combined with...) Figure 5 Step S30 will be described below. Figure 5 As shown, a heat treatment process is performed to eliminate the first type of defect 22b within the metal layer 22. In this heat treatment process, the protective layer 25 protects the metal layer 22 to suppress the formation of a second type of defect 22a, which is a protrusion defect. The process temperature of the heat treatment process is, for example, 350°C to 450°C. The process time of the heat treatment process is, for example, 60 seconds to 180 seconds. At high temperatures, aluminum is easily deformed by extrusion, resulting in protrusion defects (second type defects), i.e., Hillock defects, in localized areas. The protective layer 25 is less prone to deformation with increasing temperature; therefore, depositing the protective layer 25 can suppress the formation of second type defects in localized areas of the aluminum. In some embodiments, the second type defects may not be completely removed, but their severity is significantly reduced, by approximately 70% to 80%.
[0043] After the heat treatment process is performed, the protective layer 25 is retained; the process further includes: forming a photoresist layer that covers the protective layer 25; performing an exposure process and a development process to form a patterned photoresist layer; performing an etching process, using the patterned photoresist layer as a mask, sequentially etching the protective layer 25, the hard mask layer 24, the upper adhesion layer 24, the metal layer 22, and the lower adhesion layer 21, with the remaining portion of the metal layer 22 forming a metal interconnect structure.
[0044] In the exposure process of metal etching, the protective layer (DARC) also plays an important role as a dielectric anti-reflection layer, which helps to eliminate the standing wave effect in photolithography. That is, after the heat treatment process, there is no need to remove the protective layer 25; photoresist is formed on the protective layer 25 as a dielectric anti-reflection coating for subsequent photolithography processes. The rework method for semiconductor structures with metal layer defects provided in this embodiment can remove the aluminum θ phase while suppressing the formation of protrusion defects without adding extra steps, avoiding etching blockage during subsequent metal etching, and thus reducing the risk of low yield caused by protrusion defects. In other words, the rework method for semiconductor structures with metal layer defects provided in this embodiment can remove the first type of metal layer defects while suppressing the formation of the second type of defects without adding extra steps, thereby reducing the risk of low yield caused by the second type of defects.
[0045] Please continue to refer to this. Figure 5 This embodiment also provides a semiconductor structure, which is reworked using the rework method for a semiconductor structure with metal layer defects as described in any of the above claims, including:
[0046] Substrate 20;
[0047] Metal layer 22, the metal layer 22 being located on the substrate 20;
[0048] Hard mask layer 24, the hard mask layer 24 being located on the metal layer 22;
[0049] A protective layer 25 covers the hard mask layer 24.
[0050] Furthermore, it also includes:
[0051] A lower adhesion layer 21 is located on the substrate 20 and between the substrate 20 and the metal layer 22, and is used to adhere the substrate 20 and the metal layer 22.
[0052] An upper adhesion layer 23 is located on the metal layer 22 and between the metal layer 22 and the hard mask layer 24, and is used to adhere the metal layer 22 and the hard mask layer 24.
[0053] Furthermore, the hard mask layer 24 also serves as a diffusion barrier layer for the metal layer 22 and an anti-reflection layer in the metal etching process. The protective layer 25 also serves as a dielectric anti-reflection coating on the bottom of the photoresist in subsequent photolithography processes.
[0054] In summary, the rework method for a semiconductor structure with metal layer defects provided in this invention involves providing a semiconductor structure comprising a substrate, a metal layer, and a hard mask layer stacked sequentially from bottom to top. The metal layer contains a first-type defect. A protective layer is formed on the hard mask layer. A heat treatment process is performed to eliminate the first-type defect in the metal layer. During the heat treatment process, the protective layer protects the metal layer to suppress the formation of a second-type defect. This invention eliminates the first-type defect in the metal layer through heat treatment after the formation of the protective layer. The heat treatment process involves a high temperature, and aluminum is easily deformed under high temperatures, resulting in protrusion defects (second-type defects), i.e., Hillock defects, in localized areas. The protective layer is less prone to deformation with increasing temperature; therefore, depositing the protective layer can suppress the formation of second-type defects in localized areas of the metal layer. The protective layer is a dielectric anti-reflective coating and does not need to be removed after the heat treatment process. It is then used to form photoresist, serving as a dielectric anti-reflective coating in subsequent photolithography processes. The rework method for semiconductor structures with metal layer defects provided by this invention can remove the first type of metal layer defects while suppressing the generation of the second type of defects without adding extra steps, thereby reducing the risk of low yield caused by the second type of defects.
[0055] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to mutually. In addition, different parts between embodiments can also be combined with each other, and this invention does not limit this.
[0056] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.
Claims
1. A method for reworking a semiconductor structure with metal layer defects, characterized in that, include: A semiconductor structure is provided, the semiconductor structure comprising a substrate, a metal layer and a hard mask layer stacked sequentially from bottom to top, wherein a first type of defect exists in the metal layer; A protective layer is formed, which covers the hard mask layer; A heat treatment process is performed to eliminate first-type defects within the metal layer, wherein the protective layer is used to protect the metal layer during the heat treatment process.
2. The rework method for a semiconductor structure with metal layer defects as described in claim 1, characterized in that, The material of the metal layer includes aluminum.
3. The rework method for a semiconductor structure with metal layer defects as described in claim 2, characterized in that, The first type of defect present in the metal layer includes the aluminum θ phase.
4. The rework method for a semiconductor structure with metal layer defects as described in claim 1, characterized in that, The heat treatment process is carried out at a temperature of 350°C to 450°C.
5. The rework method for a semiconductor structure with metal layer defects as described in claim 1, characterized in that, The heat treatment process takes 60 to 180 seconds.
6. The rework method for a semiconductor structure with metal layer defects as described in claim 1, characterized in that, The protective layer is a dielectric anti-reflective coating.
7. The rework method for a semiconductor structure with metal layer defects as described in claim 1, characterized in that, The material of the hard mask layer includes titanium nitride.
8. The rework method for a semiconductor structure with metal layer defects as described in claim 1, characterized in that, The protective layer remains after the heat treatment process is performed; Also includes: A photoresist layer is formed, which covers the protective layer; Perform exposure and development processes to form a patterned photoresist layer; An etching process is performed, using the patterned photoresist layer as a mask, to sequentially etch the protective layer, the hard mask layer, and the metal layer, with the remaining portion of the metal layer forming a metal interconnect structure.
9. The rework method for a semiconductor structure with metal layer defects as described in claim 1, characterized in that, An adhesion layer is also formed between the hard mask layer and the metal layer.
10. A semiconductor structure, characterized in that, Reworking a semiconductor structure with metal layer defects using the reworking method described in any one of claims 1 to 9 includes: Substrate; A metal layer located on the substrate; A hard mask layer, the hard mask layer being located on the metal layer; A protective layer that covers the hard mask layer.