Structure for improving trench MIM capacitor interface leakage weakness and manufacturing method thereof
By replacing the CMP step in the MIM capacitor process, the etching step is used to define the MIM capacitor region and form a T-shaped structure, the problem of leakage in the trench MIM capacitor interface is solved, and the breakdown voltage and capacitance performance is improved.
Patent Information
- Application Number
- CN202510213530.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-25
- Publication Date
- 2025-05-16
AI Technical Summary
The existing trench MIM capacitor process is prone to leakage at the interface after CMP, resulting in a smaller breakdown voltage.
After the MIM capacitor is deposited, the CMP step is not used, but the MIM capacitor region is defined again through the etching step, forming a T-shaped structure, and forming a cap layer and a through hole thereon to avoid the occurrence of leakage channels at the capacitor interface.
It effectively avoids the occurrence of leakage channels at the capacitor interface, improves the breakdown voltage, and improves the performance of the trench MIM capacitor.
Smart Images
Figure CN120018523A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and in particular to a structure for improving the interface leakage weakness of a trench MIM capacitor and a manufacturing method thereof. Background Art
[0002] The trench MIM process can effectively increase the capacitance due to the larger contact area of the electrode plate, but the dielectric layer of the deep trench filling is generally thin due to the limitation of the ALD (atomic layer deposition) process. The weakness of the trench MIM process for W-electrode plates in some specific occasions often occurs at the interface after CMP (chemical mechanical planarization), resulting in leakage and a small BV (breakdown voltage).
[0003] For example, see Figure 1 , which shows a trench MIM capacitor structure of the prior art, comprising:
[0004] A substrate, a first metal layer 201 is formed on the substrate, and an etching stop layer 202 and a first interlayer dielectric layer 203 are formed on the first metal layer 201;
[0005] A groove is formed on the first interlayer dielectric layer 203 and the etching stop layer 202 thereunder, so that the first metal layer 201 at the bottom of the groove is exposed;
[0006] A second metal layer 204 is formed on the groove surface and the substrate, the first and second metal layers serve as the lower plate of the MIM capacitor, a dielectric layer 205 is formed on the second metal layer 204, a third metal layer 206 is formed on the dielectric layer 205, and a fourth metal layer 207 filling the groove and covering the third metal layer 206 is formed, and the third and fourth metal layers serve as the upper plate of the MIM capacitor;
[0007] The capacitor structure located in the trench is formed by grinding the second to fourth metal layers and the dielectric layer 205; the MIM capacitor CMP (chemical mechanical planarization polishing) step appears as follows Figure 1 The capacitor interface leakage path is shown by the dashed circle.
[0008] An anti-reflection coating 208 is formed on the first interlayer dielectric layer 203 and the capacitor structure;
[0009] A second interlayer dielectric layer 209 covers the anti-reflection coating layer 208 , and a through hole 220 electrically connected to the fourth metal layer 207 is formed on the second interlayer dielectric layer 209 .
[0010] In order to solve the above problems, it is necessary to propose a new structure and a manufacturing method for improving the interface leakage weakness of the trench MIM capacitor. Summary of the invention
[0011] In view of the shortcomings of the prior art described above, the object of the present invention is to provide a structure and a manufacturing method for improving the interface leakage weakness of the trench MIM capacitor, so as to solve the problem that the trench MIM process weakness in the prior art often occurs at the interface after CMP (chemical mechanical planarization polishing), resulting in leakage and low breakdown voltage.
[0012] To achieve the above-mentioned and other related purposes, the present invention provides a structure for improving the interface leakage weakness of a trench MIM capacitor, comprising:
[0013] A substrate, a first metal layer is formed on the substrate, and an etch stop layer and a first interlayer dielectric layer are formed on the first metal layer;
[0014] A groove is formed on the first interlayer dielectric layer and the etching stop layer thereunder, so that the first metal layer at the bottom of the groove is exposed;
[0015] A second metal layer is formed on the surface of the groove and the substrate, the first and second metal layers serve as the lower plate of the MIM capacitor, a dielectric layer is formed on the second metal layer, a third metal layer is formed on the dielectric layer, a fourth metal layer fills the groove and covers the third metal layer, and the third and fourth metal layers serve as the upper plate of the MIM capacitor;
[0016] A T-shaped structure formed by patterning the second to fourth metal layers and the dielectric layer;
[0017] A cap layer is formed on the first interlayer dielectric layer and the T-shaped structure;
[0018] A second interlayer dielectric layer covers the cap layer, and a through hole electrically connected to the fourth metal layer is formed on the second interlayer dielectric layer.
[0019] Preferably, an anti-reflection coating is formed between the fourth metal layer and the cap layer.
[0020] The present invention also provides a method for manufacturing the structure for improving the interface leakage weakness of the trench MIM capacitor, comprising:
[0021] Step 1: providing a substrate, forming a first metal layer on the substrate, and forming an etch stop layer and a first interlayer dielectric layer on the first metal layer;
[0022] Step 2: forming a groove on the first interlayer dielectric layer and the etching stop layer thereunder, so that the first metal layer at the bottom of the groove is exposed;
[0023] Step 3, forming a second metal layer on the surface of the groove and the substrate, the first and second metal layers serve as the lower plate of the MIM capacitor, then forming a dielectric layer on the second metal layer, forming a third metal layer on the dielectric layer, and then forming a fourth metal layer filling the groove and covering the third metal layer, the third and fourth metal layers serve as the upper plate of the MIM capacitor;
[0024] Step 4: patterning the second to fourth metal layers and the dielectric layer to form a T-shaped structure;
[0025] Step 5: forming a cap layer on the first interlayer dielectric layer and the T-shaped structure, forming a second interlayer dielectric layer covering the cap layer, and then forming a through hole electrically connected to the fourth metal layer on the second interlayer dielectric layer.
[0026] Preferably, the material of the first metal layer in step 1 is copper.
[0027] Preferably, the material of the first interlayer dielectric layer in step 1 is undoped silicate glass.
[0028] Preferably, the material of the etch stop layer in step 1 is SiCN.
[0029] Preferably, the method for forming the groove in step 2 includes: forming a first photoresist layer on the first interlayer dielectric layer, opening the first photoresist layer by photolithography to define a formation position of the groove, forming the groove by etching, and removing the remaining first photoresist layer.
[0030] Preferably, the materials of the second and third metal layers in step three are both WN.
[0031] Preferably, the material of the dielectric layer in step three is Al2O3.
[0032] Preferably, the material of the fourth metal layer in step three is tungsten.
[0033] Preferably, the method for forming the T-shaped structure in step four includes: forming an anti-reflective coating for a through hole on the fourth metal layer, forming a second photoresist layer on the anti-reflective coating, photolithographically opening the second photoresist layer so that the retained second photoresist layer remains above the groove and a lateral spacing is formed between an edge portion and the groove, etching the exposed anti-reflective coating and the fourth metal layer and the MIM capacitor stack thereunder to form the T-shaped structure, and then removing the second photoresist layer.
[0034] Preferably, the material of the anti-reflection coating in step 4 is SION.
[0035] Preferably, the material of the cap layer in step five is SiCN.
[0036] Preferably, the material of the second interlayer dielectric layer in step five is undoped silicate glass.
[0037] Preferably, the method for forming the through hole in step five includes: forming a third photoresist layer on the second interlayer dielectric layer, photolithographically opening the third photoresist layer to define the formation position of the through hole, forming the through hole by etching, and forming a conductive metal filling the through hole.
[0038] As described above, the structure and manufacturing method of the present invention for improving the interface leakage weakness of the trench MIM capacitor have the following beneficial effects:
[0039] After the MIM capacitor is deposited, the present invention does not use a CMP (chemical mechanical planarization and polishing) step, and the MIM capacitor area is redefined through an etching step to avoid the appearance of a capacitor interface leakage channel. BRIEF DESCRIPTION OF THE DRAWINGS
[0040] Figure 1 Shown is a schematic diagram of the leakage weakness of the trench MIM capacitor interface in the prior art;
[0041] Figure 2 Shown is a schematic diagram of the process flow of the present invention;
[0042] Figure 3 It is a schematic diagram showing the formation of the second and third metal layers and the dielectric layer in the trench according to the present invention;
[0043] Figure 4 It is a schematic diagram showing the formation of an anti-reflective coating and a photoresist layer on the fourth metal layer according to the present invention;
[0044] Figure 5 It is a schematic diagram of a T-shaped structure of the present invention;
[0045] Figure 6 It is a schematic diagram of forming a through hole according to the present invention. DETAILED DESCRIPTION
[0046] 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.
[0047] See also Figure 6 The present invention provides a structure for improving the interface leakage weakness of a trench MIM capacitor, comprising:
[0048] A substrate, a first metal layer 101 is formed on the substrate, and an etching stop layer 102 and a first interlayer dielectric layer 103 are formed on the first metal layer 101;
[0049] In some embodiments, the material of the first metal layer 101 in step 1 is copper.
[0050] In some embodiments, the material of the first interlayer dielectric layer 103 in step 1 is undoped silicate glass.
[0051] In some embodiments, the material of the etch stop layer 102 in step 1 is SiCN.
[0052] A trench is formed on the first interlayer dielectric layer 103 and the etching stop layer 102 thereunder, so that the first metal layer 101 at the bottom of the trench is exposed;
[0053] A second metal layer 104 is formed on the groove surface and the substrate, the first and second metal layers serve as the lower plate of the MIM capacitor, a dielectric layer 105 is formed on the second metal layer 104, a third metal layer 106 is formed on the dielectric layer 105, and a fourth metal layer 107 filling the groove and covering the third metal layer 106 is formed, and the third and fourth metal layers serve as the upper plate of the MIM capacitor;
[0054] In some embodiments, the materials of the second and third metal layers in step three are both WN.
[0055] In some embodiments, the material of the dielectric layer 105 in step three is Al 2 O 3 .
[0056] In some embodiments, the material of the fourth metal layer 107 in step three is tungsten.
[0057] The T-shaped structure is formed by patterning the second to fourth metal layers and the dielectric layer 105; compared with the prior art, the MIM capacitor extends from the trench to the first interlayer dielectric layer 103 on both sides of the trench, and does not use the CMP (chemical mechanical planarization polishing) step. The MIM capacitor area is redefined through the etching step to avoid the following Figure 1 Capacitor interface leakage path shown.
[0058] A cap layer 110 is formed on the first interlayer dielectric layer 103 and the T-shaped structure;
[0059] In some embodiments, the material of the cap layer 110 in step five is SiCN.
[0060] A second interlayer dielectric layer 111 covers the cap layer 110 , and a through hole 112 electrically connected to the fourth metal layer 107 is formed on the second interlayer dielectric layer 111 .
[0061] In some embodiments, the material of the second interlayer dielectric layer 111 in step five is undoped silicate glass.
[0062] In some embodiments, an anti-reflective coating 108 is formed between the fourth metal layer 107 and the cap layer 110 .
[0063] In some embodiments, the material of the anti-reflection coating 108 in step 4 is SION.
[0064] See also Figure 2 The present invention also provides a method for manufacturing the structure for improving the interface leakage weakness of the trench MIM capacitor, comprising:
[0065] Step 1: providing a substrate, forming a first metal layer 101 on the substrate, and forming an etching stop layer 102 and a first interlayer dielectric layer 103 on the first metal layer 101;
[0066] In some embodiments, the material of the first metal layer 101 in step 1 is copper.
[0067] In some embodiments, the material of the first interlayer dielectric layer 103 in step 1 is undoped silicate glass.
[0068] In some embodiments, the material of the etch stop layer 102 in step 1 is SiCN.
[0069] Step 2: forming a groove on the first interlayer dielectric layer 103 and the etching stop layer 102 thereunder, so that the first metal layer 101 at the bottom of the groove is exposed;
[0070] In some embodiments, the method for forming the groove in step 2 includes: forming a first photoresist layer on the first interlayer dielectric layer 103, opening the first photoresist layer by photolithography to define the formation position of the groove, forming the groove by etching, and removing the remaining first photoresist layer.
[0071] Step 3: Form a second metal layer 104 on the groove surface and the substrate. The first and second metal layers serve as the lower plate of the MIM capacitor. Then, a dielectric layer 105 is formed on the second metal layer 104. A third metal layer 106 is formed on the dielectric layer 105. Figure 3 The structure shown in FIG. 1 is then followed by forming a fourth metal layer 107 filling the trench and covering the third metal layer 106 . The third and fourth metal layers serve as the upper plates of the MIM capacitor.
[0072] In some embodiments, the materials of the second and third metal layers in step three are both WN.
[0073] In some embodiments, the material of the dielectric layer 105 in step three is Al 2 O 3 .
[0074] In some embodiments, the material of the fourth metal layer 107 in step three is tungsten.
[0075] Step 4: patterning the second to fourth metal layers and the dielectric layer 105 to form a T-shaped structure;
[0076] Compared with the prior art, after the MIM capacitor is deposited, the CMP (chemical mechanical planarization) step is not used, and the MIM capacitor area is redefined by an etching step to avoid the following problems: Figure 1 Capacitor interface leakage path shown.
[0077] In some embodiments, the method of forming the T-shaped structure in step 4 includes: forming an anti-reflective coating 108 of the through hole 111 on the fourth metal layer 107, forming a second photoresist layer 109 on the anti-reflective coating 108, and forming Figure 4 The structure shown in FIG. 1 is formed by photolithography, opening the second photoresist layer 109 so that the second photoresist layer 109 is retained above the groove and a lateral spacing is formed between the edge portion and the groove, etching the exposed anti-reflective coating 108 and the fourth metal layer 107 and the MIM capacitor stack below to form a T-shaped structure, and then removing the second photoresist layer 109 to form a structure as shown in FIG. Figure 5 The structure shown.
[0078] In some embodiments, the material of the anti-reflection coating 108 in step 4 is SION.
[0079] Step 5: forming a cap layer 110 on the first interlayer dielectric layer 103 and the T-shaped structure, forming a second interlayer dielectric layer 111 covering the cap layer 110, and then forming a through hole 111 electrically connected to the fourth metal layer 107 on the second interlayer dielectric layer 111, so as to form Figure 6 The structure shown.
[0080] In some embodiments, the material of the cap layer 110 in step five is SiCN.
[0081] In some embodiments, the material of the second interlayer dielectric layer 111 in step five is undoped silicate glass.
[0082] In some embodiments, the method for forming the through hole 112 in step five includes: forming a third photoresist layer on the second interlayer dielectric layer 111, photolithographically opening the third photoresist layer to define the formation position of the through hole 112, forming the through hole 112 by etching, and forming a conductive metal filling the through hole 112.
[0083] It 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. Therefore, 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.
[0084] In summary, the present invention does not use the CMP (chemical mechanical planarization) step after the MIM capacitor is deposited, and the MIM capacitor area is redefined through an etching step to avoid the appearance of a capacitor interface leakage channel. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.
[0085] 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 structure for improving the interface leakage weakness of a trench MIM capacitor, characterized in that: include: A substrate, a first metal layer is formed on the substrate, and an etch stop layer and a first interlayer dielectric layer are formed on the first metal layer; A groove is formed on the first interlayer dielectric layer and the etching stop layer thereunder, so that the first metal layer at the bottom of the groove is exposed; A second metal layer is formed on the surface of the groove and the substrate, the first and second metal layers serve as the lower plate of the MIM capacitor, a dielectric layer is formed on the second metal layer, a third metal layer is formed on the dielectric layer, a fourth metal layer fills the groove and covers the third metal layer, and the third and fourth metal layers serve as the upper plate of the MIM capacitor; A T-shaped structure formed by patterning the second to fourth metal layers and the dielectric layer; A cap layer is formed on the first interlayer dielectric layer and the T-shaped structure; A second interlayer dielectric layer covers the cap layer, and a through hole electrically connected to the fourth metal layer is formed on the second interlayer dielectric layer.
2. The structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 1, characterized in that: An anti-reflection coating is formed between the fourth metal layer and the cap layer.
3. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 1 or 2, comprising at least: Step 1: providing a substrate, forming a first metal layer on the substrate, and forming an etch stop layer and a first interlayer dielectric layer on the first metal layer; Step 2: forming a groove on the first interlayer dielectric layer and the etching stop layer thereunder, so that the first metal layer at the bottom of the groove is exposed; Step 3, forming a second metal layer on the surface of the groove and the substrate, the first and second metal layers serve as the lower plate of the MIM capacitor, then forming a dielectric layer on the second metal layer, forming a third metal layer on the dielectric layer, and then forming a fourth metal layer filling the groove and covering the third metal layer, the third and fourth metal layers serve as the upper plate of the MIM capacitor; Step 4: patterning the second to fourth metal layers and the dielectric layer to form a T-shaped structure; Step 5: forming a cap layer on the first interlayer dielectric layer and the T-shaped structure, forming a second interlayer dielectric layer covering the cap layer, and then forming a through hole electrically connected to the fourth metal layer on the second interlayer dielectric layer.
4. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 3, characterized in that: The material of the first metal layer in step 1 is copper.
5. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 3, characterized in that: The material of the first interlayer dielectric layer in step 1 is undoped silicate glass.
6. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 3, characterized in that: The material of the etching stop layer in step 1 is SiCN.
7. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 3, characterized in that: The method for forming the groove in step 2 includes: forming a first photoresist layer on the first interlayer dielectric layer, opening the first photoresist layer by photolithography to define a formation position of the groove, forming the groove by etching, and removing the remaining first photoresist layer.
8. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 3, characterized in that: The materials of the second and third metal layers in step three are both WN.
9. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 3, characterized in that: The material of the dielectric layer in step three is Al2O3.
10. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 3, characterized in that: The material of the fourth metal layer in step three is tungsten.
11. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 3, characterized in that: The method for forming the T-shaped structure in step 4 includes: forming an anti-reflective coating for a through hole on the fourth metal layer, forming a second photoresist layer on the anti-reflective coating, photolithographically opening the second photoresist layer so that the retained second photoresist layer remains above the groove and a lateral spacing is formed between the edge portion and the groove, etching the exposed anti-reflective coating and the fourth metal layer and the MIM capacitor stack thereunder to form the T-shaped structure, and then removing the second photoresist layer.
12. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 11, characterized in that: The material of the anti-reflection coating in step 4 is SION.
13. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 3, characterized in that: The material of the cap layer in step five is SiCN.
14. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 3, characterized in that: The material of the second interlayer dielectric layer in step five is undoped silicate glass.
15. The method for manufacturing a structure for improving the interface leakage weakness of a trench MIM capacitor according to claim 11, characterized in that: The method for forming the through hole in step five includes: forming a third photoresist layer on the second interlayer dielectric layer, opening the third photoresist layer by photolithography to define the formation position of the through hole, forming the through hole by etching, and forming a conductive metal filling the through hole.