Manufacturing method of deep trench isolation structure
By forming shallow trenches with different transverse lengths in the deep trench isolation structure, the problem of fence structure generated when STI is engraved on DTI is solved, and the process window and isolation reliability of DTI is improved.
Patent Information
- Application Number
- CN202510213682.2
- 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
In the prior art, when STI (shallow trench isolation) is engraved on DTI (deep trench isolation), a fence structure will be generated, resulting in a small process window of DTI, which is not conducive to the reliability of DTI isolation.
By forming a deep trench on the substrate, and forming a second oxide layer and a first fill layer thereon, after which a portion of the oxide layer and the fill layer are removed to form a first shallow trench, and then a second shallow trench is formed by isotropic etching, with the lateral length of the second shallow trench greater than the first shallow trench.
It solves the problem of fence structure when STI is engraved on DTI, improves the DTI process window and improves the reliability of DTI isolation.
Smart Images
Figure CN120015692A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for manufacturing a deep trench isolation structure. Background Art
[0002] When the feature size of integrated circuits reaches 0.18um, the BCD process technology uses the more advanced DTI (Deep Trench Isolation) for device isolation. Usually, a deep trench with a depth of 10-20um is etched first, and then a silicon dioxide layer is formed on the surface of the deep trench by thermal oxidation, and then filled with polycrystalline or silicon dioxide (such as O3-TEOS), and finally the excess filling material is removed by CMP;
[0003] Compared with PN junction isolation, DTI has the advantages of improving isolation effect, increasing breakdown voltage, reducing chip size, increasing IC density, and improving device reliability.
[0004] The prior art method for forming a deep trench isolation structure includes:
[0005] Step 1: A first oxide layer 102, an etch stop layer 103 and a first hard mask layer 104 are formed on a substrate 101 to form a Figure 1 The structure shown in FIG. 1 is formed by using photolithography and etching to open the first hard mask layer 104 and the etching stop layer 103 and the first oxide layer 102 thereunder, so that a portion of the substrate 101 is exposed to define the formation position of the deep trench, and the structure shown in FIG. Figure 2 Specifically, a photoresist layer 105 is formed on the first hard mask layer, the photoresist layer 105 is opened by photolithography to define the formation position of the deep trench, and then the deep trench is formed by etching, and the etching stops on the substrate 101, and finally the remaining photoresist layer 105 is removed. The photoresist layer can usually be removed by an ashing process and a wet cleaning method;
[0006] Step 2: Etch the exposed substrate 101 to form deep trenches, such as Figure 3 The structure shown in FIG. 1 is formed by using a thermal oxidation method to form a second oxide layer 106 on the deep trench to repair the damage caused by etching, and then a first filling layer 107 is formed to fill the deep trench, forming a structure as shown in FIG. Figure 4 The structure shown in FIG. 1 is formed by grinding the first filling layer 107 onto the etching stop layer 103 to form a Figure 5 The structure shown;
[0007] Step 3: remove part of the second oxide layer 106 and the first filling layer 107 on the upper side of the deep trench to form a first shallow trench with a cross-sectional morphology similar to a rectangle, forming a Figure 6 The structure shown;
[0008] Step 4: forming a second hard mask layer 108 on the first shallow trench and the etch stop layer 103 to form a Figure 7 The structure shown;
[0009] Step 5: Use photolithography and etching to form a second shallow trench on top of the deep trench to define the location of the active area. When STI (shallow trench isolation) is overlaid on DTI, a fence structure is generated, forming a Figure 8 The structure shown results in a smaller process window for DTI, which is not conducive to the reliability of DTI isolation;
[0010] Step 6: forming a second filling layer covering the second shallow trench, grinding the second filling layer to the etching stop layer 103, forming Fig. 9 The structure shown in FIG. 1 is then removed and the etching stop layer 103 is formed. Fig.10 The structure shown.
[0011] In order to solve the above problems, it is necessary to propose a novel method for manufacturing a deep trench isolation structure. Summary of the invention
[0012] In view of the shortcomings of the prior art described above, an object of the present invention is to provide a method for manufacturing a deep trench isolation structure, which is used to solve the problem in the prior art that a fence structure is generated when STI (shallow trench isolation) is overlaid on DTI, resulting in a smaller process window of DTI and affecting the reliability of DTI isolation.
[0013] To achieve the above objectives and other related objectives, the present invention provides a method for manufacturing a deep trench isolation structure, comprising:
[0014] Step 1: forming a first oxide layer, an etch stop layer and a first hard mask layer on the substrate, and opening the first hard mask layer and the etch stop layer and the first oxide layer thereunder by photolithography and etching, so that part of the substrate is exposed to define a formation position of a deep trench;
[0015] Step 2: etching the exposed substrate to form a deep trench, forming a second oxide layer on the deep trench by a thermal oxidation method, then forming a first filling layer to fill the deep trench, and grinding the first filling layer to the etch stop layer;
[0016] Step 3: removing a portion of the second oxide layer and the first filling layer on the upper side of the deep trench to form a first shallow trench with a cross-sectional morphology approximately rectangular, and then using isotropic etching to form a second shallow trench with a bottom cross-sectional morphology approximately circular arc-shaped, wherein the lateral length of the second shallow trench is greater than that of the first shallow trench;
[0017] Step 4: forming a second hard mask layer on the second shallow trench and the etch stop layer;
[0018] Step 5: forming a third shallow trench on the deep trench by photolithography and etching to define the position of the active area, so as to remove the exposed second hard mask layer;
[0019] Step six: forming a second filling layer covering the third shallow trench, grinding the second filling layer onto the etch stop layer, and then removing the etch stop layer.
[0020] Preferably, the material of the etch stop layer in step one is silicon nitride.
[0021] Preferably, the etching method in step one is dry etching.
[0022] Preferably, the substrate in step one is a silicon substrate.
[0023] Preferably, the material of the first hard mask layer in step 1 is silicate glass without impurities.
[0024] Preferably, the etching method in step 2 is dry etching.
[0025] Preferably, the depth of the deep groove in step 2 is greater than 20 microns.
[0026] Preferably, the material of the first filling layer in step 2 is a high-density plasma oxidation layer.
[0027] Preferably, the grinding method in step 2 is chemical mechanical planarization grinding.
[0028] Preferably, the thickness of the second oxide layer in step 2 is greater than 5000 angstroms.
[0029] Preferably, in step three, the first shallow trench is formed by wet etching.
[0030] Preferably, the material of the second hard mask layer in step 4 is silicon nitride.
[0031] Preferably, the etching method in step five is dry etching.
[0032] Preferably, the material of the second filling layer in step six is a high-density plasma oxidation layer.
[0033] Preferably, the grinding method in step six is chemical mechanical planarization grinding.
[0034] Preferably, in step six, the etch stop layer is removed by wet etching.
[0035] As described above, the method for manufacturing the deep trench isolation structure of the present invention has the following beneficial effects:
[0036] The present invention solves the problem of a fence structure generated when STI (shallow trench isolation) is overlaid on DTI (deep trench isolation), improves the DTI process window, and is beneficial to improving the reliability of DTI isolation. BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Figure 1 A schematic diagram showing a prior art method of forming a stacked layer on a substrate;
[0038] Figure 2 Shown is a schematic diagram of an open stack of prior art;
[0039] Figure 3 Shown is a schematic diagram of forming deep trenches in the prior art;
[0040] Figure 4 It is a schematic diagram showing the formation of a second oxide layer and a first filling layer in the prior art;
[0041] Figure 5 Shown is a schematic diagram of a prior art grinding filling layer;
[0042] Figure 6 It is a schematic diagram of forming a first shallow trench in the prior art;
[0043] Figure 7 A schematic diagram of forming a second hard mask layer in the prior art is shown;
[0044] Figure 8 It is a schematic diagram showing a method of forming a shallow trench defining an active area by etching in the prior art;
[0045] Fig. 9 Shown is a schematic diagram of a shallow trench isolation after grinding in the prior art;
[0046] Fig.10 Shown is a schematic diagram of removing an etch stop layer in the prior art;
[0047] Fig.11 Shown is a schematic diagram of the process flow of the present invention;
[0048] Fig.12 It is a schematic diagram showing the formation of a stacked layer on a substrate according to the present invention;
[0049] Fig.13 Shown is a schematic diagram of an open stack of the present invention;
[0050] Fig.14 It is a schematic diagram of forming a deep trench according to the present invention;
[0051] Fig.15It is a schematic diagram showing the formation of a second oxide layer and a first filling layer according to the present invention;
[0052] Fig.16 Shown is a schematic diagram of the grinding filling layer of the present invention;
[0053] Fig.17 It is a schematic diagram of forming a first shallow trench according to the present invention;
[0054] Fig.18 It is a schematic diagram of forming a second shallow trench according to the present invention;
[0055] Fig.19 It is a schematic diagram showing the formation of a second hard mask layer according to the present invention;
[0056] Fig. 20 It is a schematic diagram of forming a third shallow trench according to the present invention;
[0057] Fig.21 Shown is a schematic diagram of the grinding second filling layer of the present invention;
[0058] Fig. 22 It is a schematic diagram of removing the etch stop layer according to the present invention. DETAILED DESCRIPTION
[0059] 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.
[0060] See also Fig.11 The present invention provides a method for manufacturing a deep trench isolation structure, comprising:
[0061] Step 1: A first oxide layer 202, an etch stop layer 203 and a first hard mask layer 204 are formed on a substrate 201 to form a Fig.12 The structure shown in FIG. 1 is formed by using photolithography and etching methods to open the first hard mask layer 204 and the etching stop layer 203 and the first oxide layer 202 thereunder, so that a portion of the substrate 201 is exposed to define the formation position of the deep trench, forming a Fig.13 Specifically, a photoresist layer 205 is formed on the first hard mask layer, the photoresist layer 205 is opened by photolithography to define the formation position of the deep trench, and then the deep trench is formed by etching, and the etching stops on the substrate 201, and finally the remaining photoresist layer 205 is removed. The photoresist layer can usually be removed by an ashing process and a wet cleaning method;
[0062] In some embodiments, the material of the etch stop layer 203 in step 1 is silicon nitride.
[0063] In some embodiments, the etching method in step 1 is dry etching.
[0064] In some embodiments, the substrate 201 in step 1 is a silicon substrate.
[0065] In some embodiments, the material of the first hard mask layer 204 in step 1 is silicate glass without impurities.
[0066] Step 2: Etch the exposed substrate 201 to form deep grooves, such as Fig.14 The structure shown in FIG. 1 is formed by using a thermal oxidation method to form a second oxide layer 206 on the deep trench to repair the damage caused by etching, and then a first filling layer 207 is formed to fill the deep trench, forming a structure as shown in FIG. Fig.15 The structure shown in FIG. 1 is formed by grinding the first filling layer 207 onto the etching stop layer 203 to form a Fig.16 The structure shown;
[0067] In some embodiments, the etching method in step 2 is dry etching.
[0068] In some embodiments, to ensure deep trench isolation voltage, the depth of the deep trench in step 2 is greater than 20 microns.
[0069] In some embodiments, the material of the first filling layer 207 in step 2 is a high density plasma oxidation layer.
[0070] In some embodiments, the polishing method in step 2 is chemical mechanical planarization polishing.
[0071] In some embodiments, the thickness of the second oxide layer 206 in step 2 is greater than 5000 angstroms.
[0072] Step 3: remove part of the second oxide layer 206 and the first filling layer 207 on the upper side of the deep trench to form a first shallow trench with a cross-sectional morphology similar to a rectangle, forming a Fig.17 The structure shown in FIG. 1 is then formed by isotropic etching to form a second shallow trench having a bottom cross-sectional morphology similar to an arc shape, forming a structure as shown in FIG. Fig.18 In the structure shown, the lateral length of the second shallow trench is greater than that of the first shallow trench;
[0073] In some embodiments, in step three, a wet etching method is used to form the first shallow trench.
[0074] Step 4: forming a second hard mask layer 208 on the second shallow trench and the etch stop layer 203 to form a Fig.19 The structure shown;
[0075] In some embodiments, the material of the second hard mask layer 208 in step 4 is silicon nitride.
[0076] Step 5: Form a third shallow trench on the top of the deep trench by photolithography and etching to define the position of the active area, so that the exposed second hard mask layer 208 is removed; specifically, a photoresist layer is formed on the second hard mask layer 208, and the photoresist layer is opened by photolithography to define the formation position of the active area. The second shallow trench is included in the formation position of the active area, and then the third shallow trench is formed by etching. Since the second shallow trench is arc-shaped, the second hard mask layer 208 thereon is also a relatively smooth arc-shaped. Compared with the vertical morphology in the prior art, it is easy to remove during the etching process and will not form a fence structure. Finally, the remaining photoresist layer is removed. The photoresist layer can usually be removed by an ashing process and a wet cleaning method;
[0077] In some embodiments, the etching method in step five is dry etching.
[0078] Step 6: forming a second filling layer 209 covering the third shallow trench, grinding the second filling layer 209 onto the etch stop layer 203 , and then removing the etch stop layer 203 .
[0079] In some embodiments, the material of the second filling layer 209 in step six is a high density plasma oxidation layer.
[0080] In some embodiments, the polishing method in step six is chemical mechanical planarization polishing.
[0081] In some embodiments, in step six, the etch stop layer 203 is removed by wet etching.
[0082] 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.
[0083] In summary, the present invention solves the problem of fence structure generated when STI (shallow trench isolation) is overlaid on DTI (deep trench isolation), improves the DTI process window, and is conducive to improving the reliability of DTI isolation. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.
[0084] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.
Claims
1. A method for manufacturing a deep trench isolation structure, characterized in that: At least: Step 1: forming a first oxide layer, an etch stop layer and a first hard mask layer on the substrate, and opening the first hard mask layer and the etch stop layer and the first oxide layer thereunder by photolithography and etching, so that part of the substrate is exposed to define a formation position of a deep trench; Step 2: etching the exposed substrate to form a deep trench, forming a second oxide layer on the deep trench by a thermal oxidation method, then forming a first filling layer to fill the deep trench, and grinding the first filling layer to the etch stop layer; Step 3: removing a portion of the second oxide layer and the first filling layer on the upper side of the deep trench to form a first shallow trench with a cross-sectional morphology approximately rectangular, and then using isotropic etching to form a second shallow trench with a bottom cross-sectional morphology approximately circular arc-shaped, wherein the lateral length of the second shallow trench is greater than that of the first shallow trench; Step 4: forming a second hard mask layer on the second shallow trench and the etch stop layer; Step 5: forming a third shallow trench on the deep trench by photolithography and etching to define the position of the active area, so as to remove the exposed second hard mask layer; Step six: forming a second filling layer covering the third shallow trench, grinding the second filling layer onto the etch stop layer, and then removing the etch stop layer.
2. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The material of the etching stop layer in step 1 is silicon nitride.
3. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The etching method in step one is dry etching.
4. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The substrate in step one is a silicon substrate.
5. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The material of the first hard mask layer in step 1 is silicate glass without impurities.
6. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The etching method in step 2 is dry etching.
7. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The depth of the deep groove in step 2 is greater than 20 microns.
8. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The material of the first filling layer in step 2 is a high-density plasma oxidation layer.
9. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The grinding method in step 2 is chemical mechanical planarization grinding.
10. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The thickness of the second oxide layer in step 2 is greater than 5000 angstroms.
11. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: In step three, the first shallow trench is formed by wet etching.
12. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The material of the second hard mask layer in step 4 is silicon nitride.
13. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The etching method in step five is dry etching.
14. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The material of the second filling layer in step six is a high-density plasma oxidation layer.
15. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: The grinding method in step six is chemical mechanical planarization grinding.
16. The method for manufacturing a deep trench isolation structure according to claim 1, wherein: In step six, the etch stop layer is removed by wet etching.
Citation Information
Cited By
Method for preparing deep trench isolation structure
WO2026179077A1