Method for preparing deep trench isolation structure
Patent Information
- Application Number
- PCT/CN2025/113755
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-25
- Filing Date
- 2025-08-11
- Publication Date
- 2026-09-03
Smart Images
Figure CN2025113755_03092026_PF_FP_ABST
Abstract
Description
Manufacturing method of deep trench isolation structure Technical Field
[0001] This invention relates to the field of semiconductor technology, and in particular to a method for manufacturing a deep trench isolation structure. Background Technology
[0002] When the feature size of integrated circuits reached 0.18µm, the BCD process technology adopted the more advanced DTI (Deep Trench Isolation) for device isolation. Typically, a deep trench of 10-20µm is first etched, then a silicon dioxide layer is formed on the surface of the trench using thermal oxidation, followed by filling with polysilicon or silicon dioxide (such as O3-TEOS), and finally, excess filler material is removed using CMP.
[0003] Compared to PN junction isolation, DTI has advantages such as improved isolation performance, increased breakdown voltage, reduced chip size, increased IC density, and improved device reliability.
[0004] Existing methods for forming deep trench isolation structures include:
[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, forming the structure shown in Figure 1. The first hard mask layer 104 and the etch stop layer 103 and the first oxide layer 102 below it are opened by photolithography and etching, so that part of the substrate 101 is exposed to define the formation position of the deep trench, forming the structure shown in 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. Then, the deep trench is formed by etching, and the etching stops on the substrate 101. Finally, the remaining photoresist layer 105 is removed. The photoresist layer can usually be removed by ashing process and wet cleaning.
[0006] Step 2: Etch the exposed substrate 101 to form a deep trench, forming the structure shown in Figure 3. Use thermal oxidation to form a second oxide layer 106 on the deep trench, which can repair the damage caused by etching. Then, form a first filling layer 107 to fill the deep trench, forming the structure shown in Figure 4. Polish the first filling layer 107 onto the etching stop layer 103 to form the structure shown in Figure 5.
[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 approximately rectangular, forming the structure shown in Figure 6;
[0008] Step 4: Form a second hard mask layer 108 on the first shallow trench and the etching stop layer 103 to form the structure shown in Figure 7;
[0009] Step 5: Using photolithography and etching, a second shallow trench is formed above the deep trench to define the location of the active region. When the STI (shallow trench isolation) is overlaid on the DTI, a fence structure is generated, forming the structure shown in Figure 8. This results in a smaller process window for the DTI, which is not conducive to the reliability of the DTI isolation.
[0010] Step 6: Form a second filling layer covering the second shallow trench, grind the second filling layer onto the etch stop layer 103 to form the structure shown in Figure 9, and then remove the etch stop layer 103 to form the structure shown in Figure 10.
[0011] To solve the above problems, a novel manufacturing method for deep trench isolation structures is needed. Summary of the Invention
[0012] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for manufacturing a deep trench isolation structure to solve the problem that when STI (shallow trench isolation) is overlaid onto DTI, a fence structure is generated, resulting in a small process window for DTI and which is detrimental to the reliability of DTI isolation.
[0013] To achieve the above and other related objectives, the present invention provides a method for manufacturing a deep trench isolation structure, comprising:
[0014] Step 1: A first oxide layer, an etch stop layer, and a first hard mask layer are formed on the substrate. The first hard mask layer and the etch stop layer and the first oxide layer below it are opened by photolithography and etching, so that part of the substrate is exposed to define the formation location of the deep trench.
[0015] Step 2: Etch the exposed substrate to form deep trenches, form a second oxide layer on the deep trenches using thermal oxidation, then form a first fill layer to fill the deep trenches, and grind the first fill layer onto the etching stop layer;
[0016] Step 3: Remove part 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 shape approximately rectangular. Then, use isotropic etching to form a second shallow trench with a bottom cross-sectional shape approximately arc-shaped. The lateral length of the second shallow trench is greater than that of the first shallow trench.
[0017] Step 4: Form a second hard mask layer on the second shallow trench and the etching stop layer;
[0018] Step 5: Using photolithography and etching, a third shallow trench is formed above the deep trench to define the location of the active region, thereby removing the exposed second hard mask layer.
[0019] Step 6: Form a second filler layer covering the third shallow trench, grind the second filler layer onto the etch stop layer, and then remove the etch stop layer.
[0020] Preferably, the material of the etching 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 one is silicate glass without any impurities.
[0024] Preferably, the etching method in step two is dry etching.
[0025] Preferably, the depth of the deep trench in step two is greater than 20 micrometers.
[0026] Preferably, the material of the first filling layer in step two is a high-density plasma oxide layer.
[0027] Preferably, the grinding method in step two is chemical mechanical planarization grinding.
[0028] Preferably, the thickness of the second oxide layer in step two is greater than 5000 angstroms.
[0029] Preferably, the first shallow trench is formed in step three using a wet etching method.
[0030] Preferably, the material of the second hard mask layer in step four 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 oxide layer.
[0033] Preferably, the grinding method in step six is chemical mechanical planarization grinding.
[0034] Preferably, in step six, the etching stop layer is removed using a wet etching method.
[0035] As described above, the manufacturing method of the deep trench isolation structure of the present invention has the following beneficial effects:
[0036] This invention solves the problem of fence structure formation when STI (shallow trench isolation) is overlaid onto DTI (deep trench isolation), improves the DTI process window, and helps improve the reliability of DTI isolation. Attached Figure Description
[0037] Figure 1 shows a schematic diagram of the prior art for forming a stack on a substrate;
[0038] Figure 2 shows a schematic diagram of the open stacking technology in the prior art;
[0039] Figure 3 shows a schematic diagram of the formation of deep trenches using existing technology;
[0040] Figure 4 shows a schematic diagram of the formation of the second oxide layer and the first filler layer in the prior art;
[0041] Figure 5 shows a schematic diagram of the grinding filler layer in the prior art;
[0042] Figure 6 shows a schematic diagram of the formation of the first shallow trench in the prior art;
[0043] Figure 7 shows a schematic diagram of the formation of the second hard mask layer using existing technology;
[0044] Figure 8 shows a schematic diagram of shallow trenches defining active regions using etching in the prior art.
[0045] Figure 9 shows a schematic diagram of shallow trench isolation grinding in the prior art;
[0046] Figure 10 shows a schematic diagram of the removal of the etch stop layer in the prior art;
[0047] Figure 11 shows a schematic diagram of the process flow of the present invention;
[0048] Figure 12 shows a schematic diagram of the formation of a stack on a substrate according to the present invention;
[0049] Figure 13 shows a schematic diagram of the open stacking of the present invention;
[0050] Figure 14 shows a schematic diagram of the formation of deep trenches according to the present invention;
[0051] Figure 15 shows a schematic diagram of the formation of the second oxide layer and the first filler layer according to the present invention;
[0052] Figure 16 shows a schematic diagram of the grinding filler layer of the present invention;
[0053] Figure 17 shows a schematic diagram of the formation of the first shallow trench according to the present invention;
[0054] Figure 18 shows a schematic diagram of the formation of the second shallow trench according to the present invention;
[0055] Figure 19 shows a schematic diagram of the formation of the second hard mask layer according to the present invention;
[0056] Figure 20 shows a schematic diagram of the formation of the third shallow trench according to the present invention;
[0057] Figure 21 shows a schematic diagram of the grinding second filler layer of the present invention;
[0058] Figure 22 shows a schematic diagram of the removal of the etch stop layer according to the present invention. Detailed Implementation
[0059] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0060] Please refer to Figure 11. This 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, forming the structure shown in Figure 12. The first hard mask layer 204 and the etch stop layer 203 and the first oxide layer 202 below it are opened by photolithography and etching, so that part of the substrate 201 is exposed to define the formation position of the deep trench, forming the structure shown in Figure 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. Then, the deep trench is formed by etching, and the etching stops on the substrate 201. Finally, the remaining photoresist layer 205 is removed. The photoresist layer can usually be removed by ashing process and wet cleaning.
[0062] In some embodiments, the material of the etch stop layer 203 in step one is silicon nitride.
[0063] In some embodiments, the etching method in step one is dry etching.
[0064] In some embodiments, the substrate 201 in step one is a silicon substrate.
[0065] In some embodiments, the material of the first hard mask layer 204 in step one is silicate glass without any doped impurities.
[0066] Step 2: Etch the exposed substrate 201 to form a deep trench, forming the structure shown in Figure 14. Use thermal oxidation to form a second oxide layer 206 on the deep trench, which can repair the damage caused by etching. Then, form a first filling layer 207 to fill the deep trench, forming the structure shown in Figure 15. Polish the first filling layer 207 onto the etching stop layer 203 to form the structure shown in Figure 16.
[0067] In some embodiments, the etching method in step two is dry etching.
[0068] In some embodiments, to ensure the deep trench isolation voltage, the depth of the deep trench in step two is greater than 20 micrometers.
[0069] In some embodiments, the material of the first filling layer 207 in step two is a high-density plasma oxide layer.
[0070] In some embodiments, the grinding method in step two is chemical mechanical planarization grinding.
[0071] In some embodiments, the thickness of the second oxide layer 206 in step two 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 shape approximately rectangular, forming the structure shown in Figure 17. Then, use isotropic etching to form a second shallow trench with a bottom cross-sectional shape approximately arc-shaped, forming the structure shown in Figure 18. The lateral length of the second shallow trench is greater than that of the first shallow trench.
[0073] In some embodiments, the first shallow trench is formed in step three using a wet etching method.
[0074] Step 4: Form a second hard mask layer 208 on the second shallow trench and the etch stop layer 203 to form the structure shown in Figure 19;
[0075] In some embodiments, the material of the second hard mask layer 208 in step four is silicon nitride.
[0076] Step 5: Using photolithography and etching, a third shallow trench is formed above the deep trench to define the location of the active region, thereby removing the exposed second hard mask layer 208. Specifically, a photoresist layer is formed on the second hard mask layer 208, and photolithography is used to open the photoresist layer to define the formation location of the active region. The second shallow trench is included in the formation location of the active region. Then, the third shallow trench is formed by etching. Since the second shallow trench is arc-shaped, the second hard mask layer 208 on it is also a relatively smooth arc-shaped layer. 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 ashing process and wet cleaning.
[0077] In some embodiments, the etching method in step five is dry etching.
[0078] Step 6: Form a second filling layer 209 covering the third shallow trench, grind the second filling layer 209 onto the etch stop layer 203, and then remove 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 oxide layer.
[0080] In some embodiments, the grinding method in step six is chemical mechanical planarization grinding.
[0081] In some embodiments, step six involves removing the etching stop layer 203 using a wet etching method.
[0082] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0083] In summary, this invention solves the problem of fence structures that occur when STI (Shallow Trench Isolation) is overlaid onto DTI (Deep Trench Isolation), improves the DTI process window, and enhances the reliability of DTI isolation. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.
[0084] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can 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 those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should 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 including: Step 1: A first oxide layer, an etch stop layer, and a first hard mask layer are formed on the substrate. The first hard mask layer and the etch stop layer and the first oxide layer below it are opened by photolithography and etching, so that part of the substrate is exposed to define the formation location of the deep trench. Step 2: Etch the exposed substrate to form deep trenches, form a second oxide layer on the deep trenches using thermal oxidation, then form a first fill layer to fill the deep trenches, and grind the first fill layer onto the etching stop layer; Step 3: Remove part 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 shape approximately rectangular. Then, use isotropic etching to form a second shallow trench with a bottom cross-sectional shape approximately arc-shaped. The lateral length of the second shallow trench is greater than that of the first shallow trench. Step 4: Form a second hard mask layer on the second shallow trench and the etching stop layer; Step 5: Using photolithography and etching, a third shallow trench is formed above the deep trench to define the location of the active region, thereby removing the exposed second hard mask layer. Step 6: Form a second filler layer covering the third shallow trench, grind the second filler layer onto the etch stop layer, and then remove the etch stop layer.
2. The manufacturing method of the deep trench isolation structure according to claim 1, characterized in that: The material of the etching stop layer in step one is silicon nitride.
3. The manufacturing method of the deep trench isolation structure according to claim 1, characterized in that: The etching method described in step one is dry etching.
4. The manufacturing method of the deep trench isolation structure according to claim 1, characterized in that: The substrate mentioned in step one is a silicon substrate.
5. The manufacturing method of the deep trench isolation structure according to claim 1, characterized in that: The material of the first hard mask layer in step one is silicate glass without any impurities.
6. The manufacturing method of the deep trench isolation structure according to claim 1, characterized in that: The etching method described in step two is dry etching.
7. The manufacturing method of the deep trench isolation structure according to claim 1, characterized in that: The depth of the deep trench in step two is greater than 20 micrometers.
8. The method for manufacturing the deep trench isolation structure according to claim 1, characterized in that: The material of the first filling layer in step two is a high-density plasma oxide layer.
9. The method for manufacturing the deep trench isolation structure according to claim 1, characterized in that: The grinding method described in step two is chemical mechanical planarization grinding.
10. The method for manufacturing the deep trench isolation structure according to claim 1, characterized in that: The thickness of the second oxide layer in step two is greater than 5000 angstroms.
11. The method for manufacturing the deep trench isolation structure according to claim 1, characterized in that: In step three, the first shallow trench is formed using a wet etching method.
12. The manufacturing method of the deep trench isolation structure according to claim 1, characterized in that: The material of the second hard mask layer in step four is silicon nitride.
13. The method for manufacturing the deep trench isolation structure according to claim 1, characterized in that: The etching method described in step five is dry etching.
14. The method for manufacturing the deep trench isolation structure according to claim 1, characterized in that: The material of the second filling layer in step six is a high-density plasma oxide layer.
15. The method for manufacturing the deep trench isolation structure according to claim 1, characterized in that: The grinding method described in step six is chemical mechanical planarization grinding.
16. The method for manufacturing the deep trench isolation structure according to claim 1, characterized in that: In step six, the etching stop layer is removed using a wet etching method.