[0026] As described in the background art, the prior art method for removing the photoresist layer does not completely remove the photoresist layer. Please continue to refer Figure 1 ~ Figure 2 After research, the inventor found that in the prior art, the photoresist layer 105 is used as a mask to implant ions 105 into the substrate 100. On the one hand, when ions are implanted into the substrate 100, the ions 105 bombard the photoresist layer 101 so that all The photoresist layer 101 becomes hard; on the other hand, when ions are injected into the substrate 100, a part of the ions 105 stay in the photoresist layer 101; on the other hand, when ions are injected into the substrate 100, the substrate 100 Under the bombardment of the ions 105, a part of the silicon atoms inevitably splash into the photoresist layer 101; and when the photoresist layer 101 is etched to form an ion implantation window, the etching gas and the substrate 100 or light Part of the by-products produced by the reaction of the resist layer will also remain in the photoresist layer. All of the above factors will affect the removal of the photoresist layer 101.
[0027] After research, the inventor found that the ashing process was first used to remove most of the photoresist layer, and then used to include H 2 SO 4 And H 2 O 2 The effect of removing the remaining photoresist layer with the chemical reagents is not ideal, even at the temperature higher than 150 ℃, the use of H 2 SO 4 And H 2 O 2 Chemical reagents to remove the remaining photoresist layer; or use H 2 SO 4 And ozone (O 3 The effect of removing the remaining photoresist layer by the chemical reagent of) is also not ideal.
[0028] After further research, the inventor found that the ozone in the above chemical reagents is highly oxidizing, and most of the photoresist layer and the doped ions staying in the photoresist layer can be oxidized and removed. However, ozone will also The silicon atoms in the photoresist layer are oxidized to silicon dioxide (SiO 2 ), the texture of the silicon dioxide is relatively hard, and it will form a hard shell on the surface of the photoresist that has not been removed, blocking the removal of the photoresist layer; the inventor found that diluted hydrofluoric acid (HF) can be removed Silicon dioxide can therefore be used in the process of removing the photoresist layer.
[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0030] In the following description, many specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein, so the present invention is not limited by the specific embodiments disclosed below.
[0031] Please refer to image 3 , The method for removing the photoresist layer of the embodiment of the present invention includes:
[0032] Step S201, providing a substrate; a photoresist layer is formed on the surface of the substrate; doping the substrate with the photoresist layer as a mask;
[0033] Step S203, after the doping is finished, use an ashing process to remove most of the photoresist layer;
[0034] Step S205, using ozone water to remove the remaining photoresist layer and the doped ions staying in the remaining photoresist layer during doping; using diluted hydrofluoric acid to remove other substances in the remaining photoresist layer .
[0035] Figure 4 ~ Figure 8 It is a schematic cross-sectional structure diagram of a method for removing a photoresist layer according to an embodiment of the present invention.
[0036] Please refer to Figure 4 , A substrate 300 is provided; a photoresist layer 301 is formed on the surface of the substrate 300; and the substrate 300 is doped with the photoresist layer 301 as a mask.
[0037] The substrate 300 is used to provide a platform for subsequent processes. The material of the substrate 300 is a semiconductor material, such as silicon.
[0038] The photoresist layer 301 is used as a mask for the subsequent doping process; the photoresist layer 301 includes an opening 306 that is used as a subsequent implantation window for doped ions; the photoresist layer The materials of 301 include photosensitive resin, sensitizer and so on.
[0039] The doping includes light doping and heavy doping. Among them, the injection dose is greater than 1E15/cm 2 The doping process is heavy doping. In the embodiment of the present invention, using the photoresist layer 301 as a mask, the substrate 300 is lightly doped and heavily doped in sequence, and the doping ions 305 in the doping process include Ge, P , As, N and F ions, etc. The specific steps of the doping include: when the energy is 30 keV, the implant dose in the substrate 300 is 5E14/cm 2 Ge ions; when the energy is 20kev, the implantation dose in the substrate 300 is 8E13/cm 2 的P ions; when the energy is 20kev, the implantation dose in the substrate 300 is 3.5E15/cm 2 As ions; when the energy is 4keV, the implantation dose in the substrate 300 is 2E15/cm 2 的P ions; when the energy is 1keV, the implantation dose in the substrate 300 is 4E15/cm 2 的 N ions; when the energy is 8keV, the implantation dose in the substrate 300 is 4E15/cm 2 的F ion.
[0040] After the doping is completed, the substrate 300 directly under the opening 306 is doped with doping ions 305. The photoresist layer 301 hardens under the bombardment of ions, and a part of the doped ions 305, such as a part of Ge, P, As, N, and F ions, stay in the photoresist layer during doping. The inventor also found that when the substrate 300 is doped, a part of the silicon atoms 307 in the substrate 300 will inevitably splash into the photoresist layer 301 under the bombardment of the doping ions 305.
[0041] It should be noted that, in other embodiments of the present invention, the doping ions in the doping process may also be one or more combinations of Ge, P, As, N, and F ions; and during etching When the photoresist layer 301 forms the opening 306, part of the by-products produced by the reaction of the etching gas with the substrate 300 or the photoresist layer 301 will also remain in the photoresist layer 301.
[0042] Please refer to Figure 5 After the doping is completed, an ashing process is used to remove most of the photoresist layer 301.
[0043] In order to save the process time for removing the photoresist layer 301, an ashing process may be used to remove most of the photoresist layer. The steps of the ashing process include: placing the substrate 300 with the photoresist layer 301 in a stripper (not shown), and under the action of the energy of the radio frequency voltage, the ashing gas is dissociated into plasma gas The plasma reacts with the photoresist layer 301 to remove most of the photoresist layer 301, but a small part of the photoresist layer 301 remains on the surface of the substrate 300, and the small part of the photoresist layer 301 remains The adhesive layer 301 will affect the semiconductor process and the performance of the formed semiconductor device.
[0044] In an embodiment of the present invention, the ashing gas introduced in the ashing process includes O 2 , N 2 And H 2. Where O 2 The flow rate is 1~8L/min, N 2 And H 2 The flow rate is 0.8~1.2L/min. After the ashing process, a part of the photoresist layer 301 remains on the surface of the substrate 300, and the remaining photoresist layer 301 contains doped ions 305 and silicon atoms 307.
[0045] It should be noted that in other embodiments of the present invention, the ashing process may not be adopted, and the photoresist layer may be directly removed by a wet etching process including at least the first reagent and the second reagent.
[0046] Please refer to Figure 6 ~ Figure 8 , Using ozone water to remove the remaining photoresist layer 301 and doping ions staying in the remaining photoresist layer 301 during doping; using diluted hydrofluoric acid to remove the remaining photoresist layer Other substances.
[0047] The inventor found that the remaining photoresist layer 301 mainly includes some doped ions 305 and silicon atoms 307 splashed from the substrate into the photoresist layer 301 during the doping process. In an embodiment of the present invention, the other substances at least include silicon atoms and/or silicon oxides. After research, the inventor found that the remaining photoresist layer 301 can be removed by a wet etching process including at least a first reagent and a second reagent. Wherein, the first reagent is ozone water, which is used to remove the remaining photoresist layer 301 and the doping ions staying in the remaining photoresist layer 301 during doping, and to remove the remaining photoresist layer 301 The silicon atoms 307 in the adhesive layer 301 are oxidized into silicon dioxide 309; the second reagent is diluted hydrofluoric acid for removing the silicon dioxide 309 in the photoresist layer 301.
[0048] In an embodiment of the present invention, the step of removing the remaining photoresist layer 301 includes:
[0049] First, please refer to Image 6 , Ozone water is used to remove the remaining photoresist layer 301 and the doped ions 305 doped in the remaining photoresist layer 301. Due to the strong oxidizing property of ozone water, on the one hand, the ozone water can oxidize the remaining photoresist layer 301 and the doped ions 305 staying in the remaining photoresist layer 301 into a gas or a substance easily soluble in water To remove, and to avoid introducing new impurities, deionized water is usually used to clean the photoresist layer; on the other hand, the ozone water will also oxidize the silicon atoms splashed into the remaining photoresist layer 301 Since the texture of the silicon dioxide 309 is relatively hard, the surface layer of the photoresist layer that has not been removed will become harder, which prevents subsequent removal of the photoresist layer. Therefore, under normal circumstances, the remaining photoresist layer 301 cannot be completely removed by using ozone water for the first time, and a very small part of the photoresist layer 301 will remain on the surface of the substrate 300.
[0050] In the embodiment of the present invention, the process conditions for using ozone water to remove the remaining photoresist layer 301 and the doped ions 305 doped in the remaining photoresist layer 301 are: ozone water The concentration is 20-50ppm, the temperature of wet etching is 20-35°C, and the time of wet etching is 0.5-2min.
[0051] Then, please refer to Figure 7 , Using diluted hydrofluoric acid as a chemical reagent to remove other substances in the remaining photoresist layer 301. The other substances include at least silica formed after being oxidized by ozone water. In the examples of the present invention, the inventor found that at room temperature, HF:H 2 When hydrofluoric acid with a ratio of O of 1:300 to 1:500 is applied to the surface of the remaining photoresist layer 301 for 5 to 15 seconds, the time for removing the silicon atoms and/or silicon oxide is 5 In ~15s, the silicon atoms and/or silicon dioxide in the photoresist layer 301 can be effectively removed without causing damage to the substrate 300.
[0052] It should be noted that in other embodiments of the present invention, the diluted hydrofluoric acid can also be used to remove part of the by-products produced by the reaction of the etching gas with the substrate 300 or the photoresist layer 301.
[0053] Finally, please refer to Figure 8 , And then use ozone water to completely remove the remaining photoresist layer 301. After the silicon dioxide in the photoresist layer is removed by hydrofluoric acid, a very small part of the photoresist layer 301 may still remain on the surface of the substrate 300. In order to completely remove the remaining very small part of the photoresist layer 301, you can Using ozone water with a concentration of 20-50ppm again, wet etch the very small part of the photoresist layer for 0.5-2min at a temperature of 20-35°C, and remove the photoresist layer after the wet etching. The surface of the substrate 300 is rinsed with ionized water, and the remaining photoresist layer on the surface of the substrate 300 is completely removed.
[0054] It should be noted that in order to completely remove the photoresist layer on the surface of the substrate 300, diluted hydrofluoric acid can be used repeatedly to remove other impurities in the photoresist layer 301, such as silicon dioxide, and then ozone water is used. The remaining photoresist layer 301 is removed until the photoresist layer 301 on the surface of the substrate 300 is completely removed.
[0055] In summary, according to the method for removing the photoresist layer of the embodiment of the present invention, the chemical reagent used in the wet etching process at least includes a first reagent and a second reagent, and the first reagent is used to remove doped ions. The second reagent is used to remove silicon atoms and/or silicon oxide in the photoresist layer. The photoresist layer of the embodiment of the present invention is removed completely.
[0056] Further, the first reagent in the embodiment of the present invention is ozone water. The first reagent can not only remove the photoresist layer containing doped ions, but also oxidize the silicon atoms in the photoresist layer to form silicon dioxide. ; The second reagent of the embodiment of the present invention is diluted hydrofluoric acid, such as HF: H 2 Hydrofluoric acid with an O ratio of 1:300 to 1:500 can remove silicon atoms and/or silicon dioxide formed by oxidation of silicon atoms in the photoresist layer. The method for removing the photoresist layer of the embodiment of the present invention can simply and effectively completely remove the photoresist layer on the surface of the substrate.
[0057] Furthermore, in the method for removing the photoresist layer of the embodiment of the present invention, a part of the photoresist layer is first removed by an ashing process; then a first reagent is used to remove the remaining part of the photoresist layer containing doped ions, and at the same time The first reagent oxidizes the remaining silicon atoms in the photoresist layer to silicon dioxide; then the second reagent is used to remove the silicon dioxide in the photoresist layer; finally, the first reagent is used to remove the remaining doped ions The photoresist layer is completely removed. The method for removing the photoresist layer of the embodiment of the present invention is simple and effective, and the photoresist layer is completely removed.
[0058] Although the embodiments of the present invention have been disclosed as above in preferred embodiments, they are not intended to limit the embodiments of the present invention. Any person skilled in the art can use the foregoing without departing from the spirit and scope of the embodiments of the present invention. The disclosed methods and technical content make possible changes and modifications to the technical solutions of the embodiments of the present invention. Therefore, any content that does not depart from the technical solutions of the embodiments of the present invention is based on the technical essence of the embodiments of the present invention. Any simple modification, equivalent change and modification belong to the protection scope of the technical solution of the embodiment of the present invention.
