Method for removing photoresist residue on side wall of polycrystalline silicon layer
By forming a photoresist layer on the side wall of the polysilicon layer and selectively etching to remove residual photoresist, the oxide fence problem caused by photoresist residue is solved, ensuring the smooth progress of polysilicon back etching and improving etching efficiency.
Patent Information
- Application Number
- CN202411204662.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-30
- Publication Date
- 2024-12-17
AI Technical Summary
During the polysilicon back etching process, the photoresist residue leads to the formation of an oxide fence, affecting the effect of the second step of polysilicon back etching.
By forming a photoresist layer on the sidewall of the polysilicon layer and removing the residual photoresist layer by selective dry etching to avoid affecting the etching of the remaining polysilicon layers, and then removing the exposed dielectric layer to complete the polysilicon back-etching .
Effectively remove photoresist residues on the side walls of polycrystalline silicon to ensure smooth subsequent etching, avoid the generation of oxide fences, and improve the efficiency of polycrystalline silicon back-etching.
Smart Images
Figure CN119153325A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of semiconductor technology, and in particular to a method for removing photoresist residues at the side wall of a polysilicon layer. Background Art
[0002] Because the Hipower platform has both BCD (bipolar-CMOS-DMOS device) and SGT (shallow trench gate device) regions, the polysilicon back etching needs to be separated into two separate etchings. Between the two etchings, an oxide layer needs to be grown on the remaining polysilicon surface, and then the oxide layer on the polysilicon sidewall is removed. At this time, if there is a photoresist blocking the wet process, an oxide fence will appear during the second step of polysilicon back etching (such as Figure 1 shown).
[0003] In order to solve the above problems, it is necessary to propose a new method for removing photoresist residues at the sidewalls of the polysilicon layer. Summary of the invention
[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a method for removing photoresist residues on the side walls of a polysilicon layer, so as to solve the problem in the prior art that if there is photoresist blocking the wet process during the two polysilicon back etchings, an oxide fence will appear during the second step of polysilicon back etching.
[0005] To achieve the above-mentioned object and other related objects, the present invention provides a method for removing photoresist residues at the sidewall of a polysilicon layer, comprising:
[0006] Step 1, providing a substrate, the substrate comprising adjacent first and second device regions, a trench structure needs to be formed on the second device region, a first dielectric layer is formed on the substrate, and a polysilicon layer is formed on the first dielectric layer;
[0007] Step 2: patterning the polysilicon layer by a first photolithography and a first polysilicon etch-back method so that it remains on the first device region, and forming a second dielectric layer on the surface of the remaining polysilicon layer;
[0008] Step 3, forming a photoresist layer covering the first and second dielectric layers, opening the photoresist layer on the first device region by a second photolithography, and the photoresist layer remains on the sidewall of the polysilicon layer after the photolithography;
[0009] Step 4: removing the photoresist layer on the sidewall of the polysilicon layer by selective etching;
[0010] Step 5: remove the exposed first and second dielectric layers, and remove the polysilicon layer on the first device region by performing a second polysilicon back etching method.
[0011] Preferably, in step 1, the first device region is a BCD device region, and the second device region is a SGT device region.
[0012] Preferably, the material of the first dielectric layer in step 1 is silicon dioxide.
[0013] Preferably, the first polysilicon etching back method in step 2 is dry etching.
[0014] Preferably, the material of the second dielectric layer in step 2 is silicon dioxide.
[0015] Preferably, in step 2, the second dielectric layer is formed by thermal oxidation.
[0016] Preferably, in step 4, the photoresist layer on the side wall of the polysilicon layer is selectively etched away using a dry etching method.
[0017] Preferably, the process conditions of the dry etching in step 4 include: the etching gas includes O2, the etching chamber pressure is 2-10mt, the source power is 500-1000w, and the bias power is 0-10w.
[0018] Preferably, in step five, the exposed first and second dielectric layers are removed by wet etching.
[0019] Preferably, the second polysilicon etching back method in step five is wet etching.
[0020] As described above, the method for removing the photoresist residue at the side wall of the polysilicon layer of the present invention has the following beneficial effects:
[0021] The present invention selectively removes the remaining photoresist layer at the polysilicon side wall without affecting the photoresist on the top of the remaining polysilicon layer, so that the subsequent etching can smoothly remove the second dielectric layer of all polysilicon side walls, and no fence will be generated during the second polysilicon back etching in the next step. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 A schematic diagram of an oxide fence of the prior art is shown;
[0023] Figure 2 Shown is a schematic diagram of the process flow of the present invention;
[0024] Figure 3 Shown is a schematic diagram of the first polysilicon etch back of the present invention;
[0025] Figure 4 It is a schematic diagram showing the formation of a second dielectric layer according to the present invention;
[0026] Figure 5 Shown is a schematic diagram of the second photolithography of the present invention;
[0027] Figure 6 It is a schematic diagram showing the method of removing the photoresist layer on the side wall of the polysilicon layer by selective etching according to the present invention;
[0028] Figure 7 It is a schematic diagram showing the removal of the exposed first and second dielectric layers according to the present invention;
[0029] Figure 8 Shown is a schematic diagram of the second polysilicon etch back of the present invention. DETAILED DESCRIPTION
[0030] 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.
[0031] See also Figure 2 The present invention provides a method for removing photoresist residues at the sidewall of a polysilicon layer, comprising:
[0032] Step 1, providing a substrate 101, the substrate 101 includes adjacent first and second device areas, a trench structure needs to be formed on the second device area A2, a first dielectric layer 102 is formed on the substrate 101, and a polysilicon layer 103 is formed on the first dielectric layer 102;
[0033] In some embodiments, the first device region A1 in step 1 is a BCD device region, and the second device region A2 is a SGT device region.
[0034] In some embodiments, the material of the first dielectric layer 102 in step 1 is silicon dioxide.
[0035] Step 2: The polysilicon layer 103 is patterned by the first photolithography and the first polysilicon back etching method. The sidewall of the polysilicon layer 103 will be recessed due to etching, so that it remains on the first device area A1, forming a Figure 3 The structure shown in FIG. 1 is formed by forming a second dielectric layer 104 on the surface of the remaining polysilicon layer 103 to form a Figure 4 The structure shown;
[0036] In some embodiments, the first polysilicon etch back in step 2 is performed by dry etching.
[0037] In some embodiments, the material of the second dielectric layer 104 in step 2 is silicon dioxide.
[0038] In some embodiments, the second dielectric layer 104 is formed by thermal oxidation in step 2. In other embodiments, chemical vapor deposition, atomic layer deposition, etc. may also be used.
[0039] Step 3: forming a photoresist layer 105 covering the first and second dielectric layers, and performing a second photolithography to open the photoresist layer 105 on the first device region A1. After the photolithography, the photoresist layer 105 remains on the sidewall of the polysilicon layer 103, forming a Figure 5 The structure shown; the mask used in the first and second photolithography has an overlapping area A3, so there is a certain distance between the photoresist layer 105 and the polysilicon layer 103.
[0040] Step 4: Remove the photoresist layer 105 on the sidewall of the polysilicon layer 103 by selective etching to form Figure 6 The structure shown;
[0041] In some embodiments, in step 4, the photoresist layer 105 on the sidewall of the polysilicon layer 103 is selectively etched away using a dry etching method. The remaining photoresist layer 105 on the polysilicon sidewall is selectively removed without affecting the photoresist on the top of the remaining polysilicon layer 103. Therefore, the subsequent etching can smoothly remove the second dielectric layer 104 on all polysilicon sidewalls, and no fence will be generated during the second polysilicon back etching in the next step.
[0042] In some embodiments, the process conditions of dry etching in step four include: the etching gas includes O2, the etching chamber pressure is 2-10mt, for example, 2mt, 4mt, 6mt, 8mt, 10mt, the source power is 500-1000w, for example, 500w, 600w, 700w, 800w, 900w, 1000w, and the bias power is 0-10w, for example, 0w, 2w, 4w, 6w, 8w, 10w.
[0043] Step 5: Remove the exposed first and second dielectric layers to form Figure 7 The structure shown in FIG. 1 is formed by removing the polysilicon layer 103 on the first device region A1 by a second polysilicon back etching method. Figure 8 The structure shown.
[0044] In some embodiments, in step five, the exposed first and second dielectric layers are removed by wet etching.
[0045] In some embodiments, the second polysilicon etch back method in step five is wet etching.
[0046] 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.
[0047] In summary, the present invention selectively removes the remaining photoresist layer at the polysilicon sidewall without affecting the photoresist on the top of the remaining polysilicon layer, so that the subsequent etching can smoothly remove the second dielectric layer of all polysilicon sidewalls, and no fence will be generated during the second polysilicon back etching in the next step. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.
[0048] 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 removing photoresist residues from the sidewall of a polysilicon layer, characterized in that: At least: Step 1, providing a substrate, the substrate comprising adjacent first and second device regions, a trench structure needs to be formed on the second device region, a first dielectric layer is formed on the substrate, and a polysilicon layer is formed on the first dielectric layer; Step 2: patterning the polysilicon layer by a first photolithography and a first polysilicon etch-back method so that it remains on the first device region, and forming a second dielectric layer on the surface of the remaining polysilicon layer; Step 3, forming a photoresist layer covering the first and second dielectric layers, opening the photoresist layer on the first device region by a second photolithography, and the photoresist layer remains on the sidewall of the polysilicon layer after the photolithography; Step 4: removing the photoresist layer on the sidewall of the polysilicon layer by selective etching; Step 5: remove the exposed first and second dielectric layers, and remove the polysilicon layer on the first device region by performing a second polysilicon back etching method.
2. The method for removing photoresist residues at the sidewall of a polysilicon layer according to claim 1, characterized in that: In step 1, the first device area is a BCD device area, and the second device area is a SGT device area.
3. The method for removing photoresist residues at the sidewall of a polysilicon layer according to claim 1, characterized in that: The material of the first dielectric layer in step 1 is silicon dioxide.
4. The method for removing photoresist residues at the sidewall of a polysilicon layer according to claim 1, characterized in that: The first polysilicon etching back method in step 2 is dry etching.
5. The method for removing photoresist residues at the sidewall of a polysilicon layer according to claim 1, characterized in that: The material of the second dielectric layer in step 2 is silicon dioxide.
6. The method for removing photoresist residues at the sidewall of a polysilicon layer according to claim 5, characterized in that: In step 2, the second dielectric layer is formed by thermal oxidation.
7. The method for removing photoresist residues at the sidewall of a polysilicon layer according to claim 1, characterized in that: In step 4, the photoresist layer on the side wall of the polysilicon layer is selectively etched away using a dry etching method.
8. The method for removing photoresist residues at the sidewall of a polysilicon layer according to claim 7, characterized in that: The process conditions of the dry etching in step 4 include: the etching gas includes O2, the etching chamber pressure is 2-10mt, the source power is 500-1000w, and the bias power is 0-10w.
9. The method for removing photoresist residues at the sidewall of a polysilicon layer according to claim 1, characterized in that: In step five, the exposed first and second dielectric layers are removed by wet etching.
10. The method for removing photoresist residues at the sidewall of a polysilicon layer according to claim 1, characterized in that: The second polysilicon etching back method in step five is wet etching.