A method for improving the uniformity of a thin film

Abstract

An embodiment of the present application provides a method for improving film uniformity, including: determining a first implantation dose implanted into the first implantation surface of the wafer and a second implantation dose implanted into the second implantation surface of the wafer according to implantation parameters, implanting according to the first implantation dose into the first implantation surface of the wafer; implanting according to the second implantation dose into the second implantation surface of the wafer; implanting a third implantation dose into the first implantation surface of the wafer, and the third implantation dose is not greater than the critical implantation dose; if the total ion implantation dose implanted into the first implantation surface of the wafer reaches the target implantation dose, bonding the first implantation surface with the substrate layer to obtain a bonded body; heat-treating the bonded body to form a thin film layer on the substrate layer. The target implantation dose is implanted into the first implantation surface step by step, and at the same time, implantation into the second implantation surface is coordinated to offset the stress generated by the implantation of the first implantation surface, ensuring that the wafer does not warp during each implantation process, thereby ensuring that the implantation depth is consistent and obtaining a thin film with uniform thickness.

Description

Technical Field

[0001] This application belongs to the field of semiconductor device fabrication, and particularly relates to a method for improving film uniformity. Background Art

[0002] Ion implantation technology has been developed as a doping application for semiconductor materials and has been widely used in various fields such as optoelectronic integration, large-scale integrated circuits, and materials science. Its basic principle is that ions generated from an ion source are accelerated by a high-voltage electric field and injected into a material. The ion beam loses energy due to the obstruction of atoms or molecules in the material and is doped into the material. Since the incidence of the ion beam changes the structure in the material, and with the participation of the incident ions themselves, it causes changes in the surface composition, structure, and properties of the material.

[0003] In the thin film fabrication process, ion implantation technology is used to inject ions with a certain injection energy and a target injection dose into the injection surface of a wafer at one time. In this way, a damage layer composed of implanted ions and structural damage is formed under the injection surface of the wafer. Then, annealing treatment is used to promote the formation of bubbles by the implanted ions, and the thin film is disconnected from the damage layer to achieve the peeling of the thin film.

[0004] However, with the continuous injection of ions, the lattice constants of the injection surface and the non-injection surface of the wafer will change, resulting in lattice mismatch and wafer warping. As Figure 1 shown, due to the warping of wafer 01 during the ion implantation process, the ion implantation depth is inconsistent, resulting in non-uniform thickness of the finally obtained thin film. Summary of the Invention

[0005] To solve the problem in the prior art that the thickness of the thin film is non-uniform due to wafer warping.

[0006] An embodiment of this application provides a method for improving film uniformity, including:

[0007] Determine a first injection dose injected into the first injection surface of the wafer and a second injection dose injected into the second injection surface of the wafer according to the injection parameters, where the first injection dose is less than the target injection dose, and the first injection dose is not greater than the critical injection dose. The second injection dose is greater than or equal to 1 / 3 of the first injection dose, and the second injection dose is not greater than the critical injection dose. The critical injection dose refers to the maximum injection dose that does not cause warping during the process of injecting ions into the first injection surface of the wafer;

[0008] Inject into the first injection surface of the wafer according to the first injection dose;

[0009] Inject into the second injection surface of the wafer according to the second injection dose;

[0010] Inject a third implantation dose into the first implantation surface of the wafer, where the third implantation dose is not greater than the critical implantation dose;

[0011] If the total ion implantation dose injected into the first implantation surface of the wafer reaches the target implantation dose, bond the first implantation surface to the substrate layer to obtain a bonded body;

[0012] Heat-treat the bonded body to form a thin film layer on the substrate layer, where the thin film layer includes the first implantation surface.

[0013] Further, the method further includes: if, after injecting the third implantation dose into the first implantation surface of the wafer, the total ion implantation dose injected into the first implantation surface of the wafer does not reach the target implantation dose, inject a fourth implantation dose into the second implantation surface of the wafer, where the fourth implantation dose is greater than or equal to 1 / 3 of the third implantation dose and the fourth implantation dose is not greater than the critical implantation dose;

[0014] Inject a fifth implantation dose into the first implantation surface of the wafer, where the fifth implantation dose is not greater than the critical implantation dose;

[0015] If the total ion implantation dose injected into the first implantation surface of the wafer reaches the target implantation dose, bond the first implantation surface to the substrate layer to obtain a bonded body;

[0016] Heat-treat the bonded body to form a thin film layer on the substrate layer, where the thin film layer includes the first implantation surface.

[0017] Further, the first implantation dose, the third implantation dose, and the fifth implantation dose are the same, and the fourth implantation dose is greater than or equal to the second implantation dose.

[0018] Further, the second implantation dose is 1 / 3 - 1 times the first implantation dose, and the fourth implantation dose is 1 / 3 - 1 times the third implantation dose. 5. The method according to claim 2, wherein the fifth implantation dose is less than the third implantation dose, the third implantation dose is less than the first implantation dose, and the fourth implantation dose is equal to or less than the second implantation dose.

[0019] Further, the fifth implantation dose is greater than the third implantation dose, the third implantation dose is greater than the first implantation dose, and the fourth implantation dose is equal to or greater than the second implantation dose.

[0020] Further, the method further includes:

[0021] If, after injecting a fifth injection dose into the first injection surface of the wafer, the total ion injection dose injected into the first injection surface of the wafer does not reach the target injection dose, then a sixth injection dose is injected into the second injection surface of the wafer, where the sixth injection dose is greater than or equal to 1 / 3 of the fifth injection dose, and the sixth injection dose is not greater than the critical injection dose;

[0022] Inject a seventh injection dose into the first injection surface of the wafer, where the seventh injection dose is not greater than the critical injection dose;

[0023] If the total ion injection dose injected into the first injection surface of the wafer reaches the target injection dose, then bond the first injection surface to the substrate layer to obtain a bonded body;

[0024] Heat-treat the bonded body to form a thin film layer on the substrate layer, where the thin film layer includes the first injection surface.

[0025] Furthermore, the first injection dose, the third injection dose, the fifth injection dose, and the seventh injection dose are the same, the second injection dose, the fourth injection dose, and the sixth injection dose are the same, and the second injection dose is 1 / 3 - 1 times the first injection dose.

[0026] Furthermore, the first injection dose, the third injection dose, the fifth injection dose, and the seventh injection dose are the same, the sixth injection dose is greater than the fourth injection dose, the fourth injection dose is greater than the second injection dose, and the difference between the sixth injection dose and the fourth injection dose is equal to the difference between the fourth injection dose and the second injection dose.

[0027] Furthermore, the first injection dose is greater than the third injection dose, the third injection dose is greater than the fifth injection dose, the fifth injection dose is greater than the seventh injection dose, the second injection dose, the fourth injection dose, and the sixth injection dose are the same, and the differences between the first injection dose and the third injection dose, between the third injection dose and the fifth injection dose, and between the fifth injection dose and the seventh injection dose are all the same.

[0028] The method for improving film uniformity provided by the embodiments of the present application injects the target injection dose into the first injection surface of the wafer in multiple times (at least twice), and after completing the injection into the first injection surface of the wafer last time, injects into the second injection surface of the wafer to offset the stress that can cause the wafer to warp generated during the injection into the first injection surface last time, so as to ensure that the wafer does not warp during each injection into the first injection surface of the wafer, and a thin film with uniform thickness is obtained. Description of the Drawings

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 It is a schematic diagram of a warped wafer structure in the prior art.

[0031] Figure 2 It is a flowchart of a method for improving film uniformity provided by an embodiment of the present application.

[0032] Figure 3 It is a schematic diagram of the structure of a wafer after ion implantation provided by an embodiment of the present application.

[0033] Figure 4 It is a schematic diagram of the structure of a wafer after heat treatment of a bonded body provided by an embodiment of the present application.

[0034] Explanation of reference numerals

[0035] 01 - Wafer, 110 - First implantation surface, 120 - Second implantation surface, 130 - Substrate layer, 140 - Film layer, 111 - First ion implantation layer, 121 - Second ion implantation layer. Detailed implementation manners

[0036] In order to enable those skilled in the art of the present technology to better understand the solution of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0037] In the prior art, during ion implantation, ions with a target implantation dose are usually implanted into the wafer implantation surface at one time to form a damaged layer under the wafer implantation surface to achieve film peeling. However, with the continuous implantation of ions, the lattice constants of the wafer implantation surface and the non-implantation surface will change, resulting in lattice mismatch and wafer warping.

[0038] During the ion implantation process, in order to ensure a consistent implantation depth, there is a certain angle between the ion beam and the implantation surface of the wafer. When the wafer is not warped, the implantation surface of the wafer remains a flat surface, and the angle between the ion beam and the implantation surface of the wafer does not change. Therefore, a consistent ion implantation depth can be ensured. However, when the wafer is warped, the originally flat implantation surface of the wafer becomes a curved surface, while the injection direction of the ion beam does not change. Therefore, the angle between the ion beam and the implantation surface of the wafer changes, resulting in inconsistent ion implantation depths and ultimately uneven thickness of the prepared piezoelectric thin film.

[0039] In the prior art, to solve the problem of wafer warping, usually a target implantation dose is injected into the first implantation surface of the wafer at one time. After the first implantation surface of the wafer is warped, ions are injected into the second implantation surface of the wafer to restore the warped part. It can be seen that in the prior art, although the warping problem can be solved to ensure the normal progress of subsequent processes, however, since warping has occurred during the ion implantation process, even if the warping problem is solved, the finally obtained thin film is still a thin film with uneven thickness. To solve the problem of uneven thin film thickness caused by wafer warping in the prior art, the embodiments of the present application provide a method for improving the uniformity of the thin film.

[0040] See <{} Figure 2 , Figure 2 is a flowchart of a method for improving the uniformity of a thin film provided by an embodiment of the present application.

[0041] As Figure 2 shown, a method for improving the uniformity of a thin film provided by an embodiment of the present application includes the following steps:

[0042] Step 1, determine a first implantation dose injected into the first implantation surface 110 of the wafer and a second implantation dose injected into the second implantation surface 120 of the wafer according to the implantation parameters, where the first implantation dose is less than the target implantation dose, and the first implantation dose is not greater than the critical implantation dose. The second implantation dose is greater than 1 / 3 of the first implantation dose, and the second implantation dose is not greater than the critical implantation dose. The critical implantation dose refers to the maximum implantation dose that does not cause warping during the process of injecting ions into the first implantation surface 110 of the wafer.

[0043] First, it should be noted that the implantation parameters include implantation energy, implantation ion beam current, target implantation dose, wafer size, wafer material, the angle between the implantation ion beam and the wafer implantation surface, etc. The wafer implantation surface includes a first wafer implantation surface 110 and a second wafer implantation surface 120, and the first implantation surface 110 and the second implantation surface 120 are two opposite surfaces of the wafer. Among them, the implantation ion beam current refers to the implantation dose of ions implanted into the wafer implantation surface per unit time; the target implantation dose refers to the total implantation dose that needs to be implanted into the first wafer implantation surface 110.

[0044] The critical implantation doses corresponding to different implantation parameters may be different. It should be noted that the critical implantation dose in the embodiments of the present application refers to the maximum implantation dose that does not cause warping during the process of implanting ions into the first wafer implantation surface 110 under the current implantation parameter conditions, that is, the critical implantation dose at which the wafer is about to warp. It should also be noted that in the embodiments of the present application, with the same implantation parameters, ions are implanted into the first wafer implantation surface 110 and the second wafer implantation surface 120, that is, during the process of implanting ions into the first wafer implantation surface 110 and the second wafer implantation surface 120, the implantation dose can be changed, but other implantation parameters are not changed.

[0045] It should also be noted that the basis for implementing the method for improving film uniformity provided in the embodiments of the present application is that the thickness of the wafer can meet the implantation depths into the first and second wafer implantation surfaces. Among them, the thickness of the wafer is generally in millimeters (for example, a silicon wafer with a thickness of 0.25 mm), while the thickness of the fabricated thin film layer is generally in nanometers (for example, a thin film layer with a thickness of 100 - 1000 nm). Thus, it can be seen that the thickness of the wafer is generally much greater than the thickness of the fabricated thin film layer, and it can fully meet the conditions for implanting into the first and second wafer implantation surfaces in the implementation of the present application. If the thickness of the wafer is thinned to the nanometer level, the ion implantation method is generally not used to fabricate the thin film layer, but the grinding and polishing method is preferably used to fabricate the thin film layer. That is to say, the wafer in the embodiments of the present application refers to a wafer that can perform double-sided ion implantation.

[0046] The wafer described in the embodiments of the present application can be any material that warps during ion implantation. For example, the wafer can be lithium tantalate, lithium niobate, silicon, etc.

[0047] In the embodiment of the present application, in order to avoid warping of the wafer during the implantation process, the target implantation dose is implanted into the first implantation surface 110 of the wafer in multiple times (at least twice), and it is ensured that the wafer does not warp during each implantation into the first implantation surface 110 of the wafer. Therefore, the implantation dose implanted into the first implantation surface 110 of the wafer each time is less than the target implantation dose and not greater than the critical implantation dose. In addition, in order to ensure that the wafer does not warp after the next implantation into the first wafer implantation surface, in the embodiment of the present application, after the last implantation into the first wafer implantation surface is completed, it is necessary to implant into the second implantation surface 120 of the wafer to offset the stress (hereinafter referred to as stress) that can cause the wafer to warp generated during the implantation of the first implantation surface 110 last time. At the same time, it is necessary to ensure that there is no warping due to the implantation into the second implantation surface 120 of the wafer. Therefore, considering the above comprehensively, the second implantation dose is greater than or equal to 1 / 3 of the first implantation dose, and the second implantation dose is not greater than the critical implantation dose. If the second implantation dose is less than 1 / 3 of the first implantation dose, the stress generated by the first implantation surface 110 cannot be offset.

[0048] Based on the above analysis, in the embodiment of the present application, first, the first implantation dose and the second implantation dose need to be determined according to the implantation parameters. The first implantation dose is the dose implanted into the first implantation surface 110 of the wafer once, and the second implantation dose is the dose implanted into the second implantation surface 120 of the wafer once. Since the critical implantation doses corresponding to different implantation parameters are different, therefore, when the current implantation parameters are determined, the corresponding critical implantation dose is also confirmed. Therefore, the determined first implantation dose is not greater than the current critical implantation dose, that is to say, the first implantation dose can be less than or equal to the current critical implantation dose. And, in the embodiment of the present application, the target implantation dose is implanted into the first implantation surface 110 step by step. Therefore, the first implantation dose should be less than the target implantation dose, so that it can be ensured that the target implantation dose is implanted into the first implantation surface 110 at least twice.

[0049] The second implantation dose is implanted into the second implantation surface 120 of the wafer with the same implantation parameters. The purpose of implanting into the second implantation surface 120 is to offset the stress generated after the implantation of the first implantation surface 110. However, at the same time, it is also necessary to ensure that there is no warping after the implantation into the second implantation surface 120. Therefore, the second implantation dose is not greater than the critical implantation dose.

[0050] In a specific embodiment, the second implantation dose is 1 / 3 - 1 times of the first implantation dose. Since the function of the second implantation surface 120 is to offset the stress generated by the first implantation surface 110, rather than the process surface for forming a thin film layer, that is to say, the ions finally implanted into the second implantation surface 120 are useless. Therefore, in order not to waste too much ion implantation dose, the second implantation dose can be set to 1 / 3 - 1 times of the first implantation dose. Among them, the first implantation dose can be 1×1013 ions / cm 2 -1×10 16 ions / cm 2 , for example, the first implantation dose is 1×10 13 ions / cm 2 , and the second implantation dose is 5×10 12 ions / cm 2 ; and for another example, the first implantation dose is 1×10 16 ions / cm 2 , and the second implantation dose is 1×10 16 ions / cm 2 .

[0051] In one example, the first implantation dose is the critical implantation dose, and the second implantation dose is 1 / 3 of the first implantation dose. In this example, it can not only ensure that warping does not occur during the implantation process, but also improve the implantation efficiency, that is, it can inject the target implantation dose into the first implantation surface 110 as soon as possible.

[0052] Step 2: Inject according to the first implantation dose into the first implantation surface 110 of the wafer.

[0053] After determining the first implantation dose in step 1, inject the first implantation dose into the first implantation surface 110 of the wafer. After injection, since the first implantation dose is not greater than the critical implantation dose, the wafer will not warp, thus ensuring that the implantation depth of the first implantation dose ions is consistent.

[0054] Since the implanted ion beam current, that is, the implantation dose of ions injected into the wafer implantation surface (the first implantation surface 110 or the second implantation surface 120) per unit time is constant, and the product of the implantation time and the implanted ion beam current is equal to the implantation dose. Therefore, in the embodiments of the present application, according to the relationship between the implantation time and the implantation dose, the implantation dose can be converted into the corresponding implantation time, and during implantation, the implantation time can be directly controlled. For example, if the implantation time corresponding to the first implantation dose is 10 min, then in step 2, directly monitor the implantation time and inject into the first implantation surface 110 of the wafer for 10 min. In each step of the embodiments of the present application, the implantation dose can be controlled by the implantation time, or the implantation dose can be determined by other means, and the present application does not limit this.

[0055] Step 3: Inject according to the second implantation dose into the second implantation surface 120 of the wafer.

[0056] After the first injection is completed on the first injection surface, the wafer is turned over and a second injection dose is injected into the second injection surface 120 of the wafer. After the injection, since the second injection dose is greater than or equal to 1 / 3 of the first injection dose and the second injection dose is not greater than the critical injection dose, the wafer will not warp. At the same time, the injection of the second injection dose can offset the stress generated on the first injection surface 110 in step 2.

[0057] Step 4: injecting a third injection dose into the first injection surface 110 of the wafer, wherein the third injection dose is not greater than the critical injection dose.

[0058] The third implantation dose may be the same as or different from the first implantation dose, which is not limited in this application. However, the third implantation dose is still not greater than the critical implantation dose to ensure that no warping occurs after the implantation into the first implantation surface 110 of the wafer.

[0059] In one example, the third implantation dose is the same as the first implantation dose, both being equal to the critical implantation dose, and the second implantation dose is 1 / 3 to 1 times the first implantation dose.

[0060] In another example, the first implantation dose is equal to the critical implantation dose, the third implantation dose is less than the first implantation dose, and the second implantation dose is 1 / 3 to 1 times the first implantation dose.

[0061] If after the third injection dose is injected into the first injection surface 110 of the wafer, the total ion injection dose injected into the first injection surface 110 of the wafer reaches the target injection dose, there is no need to inject into the second injection surface 120 again, and step 5 can be directly executed; if after the third injection dose is injected into the first injection surface 110 of the wafer, the total ion injection dose injected into the first injection surface 110 of the wafer does not reach the target injection dose, it means that at least one injection into the first injection surface 110 is required. Therefore, after step 4, at least one step of injecting into the second injection surface 120 and injecting into the first injection surface 110 in sequence needs to be executed.

[0062] Step 5: If the total ion implantation dose implanted into the first implantation surface 110 of the wafer reaches the target implantation dose, the first implantation surface 110 is bonded to the substrate layer 130 to obtain a bonded body.

[0063] If the total ion implantation dose injected into the first implantation surface 110 of the wafer reaches the target implantation dose, the ion implantation is completed. Figure 3 As shown, since the wafer does not warp during the above-mentioned ion implantation process from the start of implantation to the completion of implantation, the ion implantation depth is kept consistent throughout the entire implantation process, forming two flat ion implantation layers in the wafer, namely the first ion implantation layer 111 and the second ion implantation layer 121.

[0064] Among them, the first implantation surface 110 is the process surface of the wafer, and the second implantation surface 120 is the implantation surface for improving the wafer warpage. Therefore, the first implantation surface 110 of the implanted wafer is bonded to the substrate layer 130 to obtain a bonded body.

[0065] Among them, the substrate layer 130 can be a single-layer substrate or a composite substrate, and the present application does not limit this.

[0066] The present application does not particularly limit the bonding method between the wafer and the substrate layer 130. Any bonding method between the wafer and the substrate layer 130 in the prior art can be adopted. For example, the bonding surface (the first implantation surface 110) of the wafer is surface-activated, the bonding surface of the substrate layer 130 is also surface-activated, and then the two activated surfaces are bonded to obtain a bonded body.

[0067] The present application does not particularly limit the method for surface-activating the bonding surface of the wafer. Any method for surface-activating the wafer in the prior art can be adopted, such as plasma activation and chemical solution activation, etc. Similarly, the present application does not particularly limit the method for surface-activating the bonding surface of the substrate layer 130. Any method that can be used to surface-activate the bonding surface of the substrate layer 130 in the prior art can be adopted, such as plasma activation.

[0068] Step 6, heat-treat the bonded body to form a thin film layer 140 on the substrate layer 130, and the thin film layer 140 includes the first implantation surface 110.

[0069] As Figure 4 shown, after heat-treating the bonded body, two parts are obtained. The first part includes the substrate layer 130 and the thin film layer 140 formed on the substrate layer 130. The thin film layer 140 is a thin film layer peeled from the wafer and includes the first implantation surface 110. The second part includes the remaining wafer substrate with the second implantation surface 120. Since the second implantation surface 120 is not bonded to the substrate layer 130 for supporting the thin film, after heat treatment, the wafer in the region between the second implantation surface 120 and the second ion implantation layer 121 in the remaining wafer substrate will be pulverized.

[0070] Since there is no wafer warpage during the implantation process, the depth of ion implantation into the first implantation surface 110 is consistent. After peeling from the wafer, the obtained thin film has a uniform thickness.

[0071] A method for improving film uniformity provided by an embodiment of the present application injects a target injection dose step by step into a first injection surface 110, and at the same time injects into a second injection surface 120 to offset the stress generated by the injection into the first injection surface 110, ensuring that the wafer does not warp during each injection process, thereby ensuring that the injection depth is consistent and obtaining a film with uniform thickness.

[0072] In another embodiment, if after injecting a third injection dose into the first injection surface 110 of the wafer, the total ion injection dose injected into the first injection surface 110 of the wafer does not reach the target injection dose, then continue to execute the steps of injecting into the second injection surface and injecting into the first injection surface, specifically as follows:

[0073] Step 101, inject a fourth injection dose into the second injection surface 120 of the wafer, the fourth injection dose is greater than or equal to 1 / 3 of the third injection dose, and the fourth injection dose is not greater than the critical injection dose.

[0074] Injecting a fourth injection dose into the second injection surface 120 of the wafer is used to offset the stress generated by the first injection surface 110 in step 4. Among them, the fourth injection dose can be the same as the second injection dose or different from the second injection dose, and the present application does not limit this.

[0075] If the third injection dose is the same as the first injection dose, preferably, the fourth injection dose can be greater than or equal to the second injection dose. Further, the second injection dose can be 1 / 3 - 1 times the first injection dose, and the fourth injection dose can be 1 / 3 - 1 times the third injection dose.

[0076] In one example, the third injection dose is the same as the first injection dose, both are the critical injection dose, the second injection dose is 1 / 3 of the first injection dose, and the fourth injection dose is 1 / 3 of the third injection dose.

[0077] In another example, the third injection dose is the same as the first injection dose, both are the critical injection dose, the second injection dose is 1 / 3 of the first injection dose, and the fourth injection dose is 2 / 3 of the third injection dose.

[0078] If the third injection dose is different from the first injection dose, for example, the third injection dose is greater than the first injection dose, then the corresponding fourth injection dose can be greater than or equal to the second injection dose; again, for example, the third injection dose is less than the first injection dose, then the corresponding fourth injection dose can be greater than, less than or equal to the second injection dose.

[0079] It can be seen from this that in the embodiments of the present application, the injection dose can be adjusted each time when injecting into the first injection surface 110 or the second injection surface 120 of the wafer, making the entire injection process more flexible; or the same injection dose can be injected into the first injection surface 110 of the wafer each time and / or the same injection dose can be injected into the second injection surface 120 of the wafer each time, making the entire injection process more standardized and easier to control.

[0080] Among them, the injection dose injected into the first injection surface 110 or the second injection surface 120 of the wafer each time can be pre-calculated and set, and then injected into the first injection surface 110 or the second injection surface 120 of the wafer according to the set injection sequence and injection dose respectively. When injecting, after injecting into the first injection surface 110 or the second injection surface 120 is completed, the wafer is turned over and the injection continues until the total injection dose injected into the first injection surface 110 reaches the target injection dose.

[0081] Step 102, inject a fifth injection dose into the first injection surface 110 of the wafer, and the fifth injection dose is not greater than the critical injection dose.

[0082] Since the total ion injection dose injected into the first injection surface 110 of the wafer does not reach the target injection dose after injecting the third injection dose into the first injection surface 110 of the wafer, it means that injection into the first injection surface 110 needs to continue to make the total ion injection dose injected into the first injection surface 110 of the wafer reach the target injection dose.

[0083] Similarly, in order to ensure that the wafer does not warp after injecting the fifth injection dose into the first injection surface 110 of the wafer, the fifth injection dose is not greater than the critical injection dose.

[0084] The fifth injection dose can be the same as the first injection dose and the third injection dose, or different from the first injection dose or the third injection dose, or different from both the first injection dose and the third injection dose. The present application does not limit this.

[0085] In one example, the first injection dose, the third injection dose, and the fifth injection dose are the same, and the fourth injection dose is greater than or equal to the second injection dose. For example, the first injection dose is equal to the critical injection dose, the second injection dose is 1 / 3 of the first injection dose, and the fourth injection dose is 2 / 3 of the first injection dose. Another example is that the first injection dose is equal to the critical injection dose, the second injection dose is 2 / 3 of the first injection dose, and the fourth injection dose is 2 / 3 of the first injection dose.

[0086] In another example, the fifth injection dose is less than the third injection dose, the third injection dose is less than the first injection dose, and the fourth injection dose is equal to or less than the second injection dose. For example, the first injection dose is equal to the critical injection dose, the third injection dose is 2 / 3 of the critical injection dose, the fifth injection dose is 1 / 3 of the critical injection dose, the corresponding second injection dose is 1 / 3 of the first injection dose, and the fourth injection dose is equal to the second injection dose. Another example is that the first injection dose is equal to the critical injection dose, the third injection dose is 2 / 3 of the critical injection dose, the fifth injection dose is 1 / 3 of the critical injection dose, the corresponding second injection dose is 1 / 3 of the first injection dose, and the fourth injection dose is equal to 1 / 3 of the third injection dose.

[0087] In yet another example, the fifth injection dose is greater than the third injection dose, the third injection dose is greater than the first injection dose, and the fourth injection dose is equal to or greater than the second injection dose. For example, the first injection dose is 1 / 3 of the critical injection dose, the third injection dose is 2 / 3 of the critical injection dose, the fifth injection dose is equal to the critical injection dose, the corresponding second injection dose is 1 / 3 of the first injection dose, and the fourth injection dose is equal to the second injection dose. Another example is that the first injection dose is 1 / 3 of the critical injection dose, the third injection dose is 2 / 3 of the critical injection dose, the fifth injection dose is equal to the critical injection dose, the corresponding second injection dose is 1 / 3 of the first injection dose, and the fourth injection dose is equal to 1 / 3 of the third injection dose.

[0088] Further, if after injecting the fifth injection dose into the first injection surface 110 of the wafer, the total ion injection dose injected into the first injection surface 110 of the wafer reaches the target injection dose, then steps 5 and 6 above are executed. If after injecting the fifth injection dose into the first injection surface 110 of the wafer, the total ion injection dose injected into the first injection surface 110 of the wafer does not reach the target injection dose, then continue to execute the steps of injecting into the second injection surface 120 and the first injection surface 110 of the wafer until the total ion injection dose injected into the first injection surface 110 reaches the target injection dose.

[0089] In another embodiment, if after injecting the fifth injection dose into the first injection surface 110 of the wafer, the total ion injection dose injected into the first injection surface 110 of the wafer does not reach the target injection dose, then the following steps are executed:

[0090] Step 103, inject a sixth injection dose into the second injection surface 120 of the wafer, where the sixth injection dose is greater than or equal to 1 / 3 of the fifth injection dose and the sixth injection dose is not greater than the critical injection dose.

[0091] Inject a sixth implantation dose into the second implantation surface 120 of the wafer to counteract the stress generated by the first implantation surface 110 in step 102.

[0092] Step 104, inject a seventh implantation dose into the first implantation surface 110 of the wafer, and the seventh implantation dose is not greater than the critical implantation dose.

[0093] Among them, the sixth implantation dose may be the same as or different from the fourth implantation dose, and the seventh implantation dose may be the same as or different from the fifth implantation dose. For specific details, reference can be made to the above description of steps 101-102, which will not be elaborated here.

[0094] In one example, the first implantation dose, the third implantation dose, the fifth implantation dose, and the seventh implantation dose are the same, the second implantation dose, the fourth implantation dose, and the sixth implantation dose are the same, and the second implantation dose is 1 / 3 - 1 times the first implantation dose. In this example, it is equivalent to determining the first implantation dose and the second implantation dose in step 1, and then alternately injecting into the first implantation surface 110 and the second implantation surface 120 according to the first implantation dose and the second implantation dose until the total ion implantation dose injected into the first implantation surface 110 of the wafer reaches the target implantation dose. That is to say, in this example, the implantation dose injected into the first implantation surface 110 each time is the same, and the implantation dose injected into the second implantation surface 120 each time is the same. Moreover, the second implantation dose injected into the second implantation surface 120 each time is 1 / 3 - 1 times the first implantation dose, which can counteract the stress generated by the first implantation surface 110 in the previous time without causing excessive waste of ions. For example, the first implantation dose, the third implantation dose, the fifth implantation dose, and the seventh implantation dose are all equal to the critical implantation dose, and the second implantation dose, the fourth implantation dose, and the sixth implantation dose are all 1 / 3 - 1 times the critical implantation dose.

[0095] In another specific example, the first injection dose, the third injection dose, the fifth injection dose, and the seventh injection dose are the same, the sixth injection dose is greater than the fourth injection dose, the fourth injection dose is greater than the second injection dose, and the difference between the sixth injection dose and the fourth injection dose is equal to the difference between the fourth injection dose and the second injection dose. In this example, it is equivalent to determining the first injection dose and the second injection dose in step 1, and then injecting into the first injection surface 110 with the same injection dose each time. Moreover, injecting into the second injection surface 120 in a manner of gradually increasing the injection dose until the total ion injection dose injected into the first injection surface 110 of the wafer reaches the target injection dose. Among them, the injection dose for any injection into the second injection surface 120 is not greater than the critical injection dose. More preferably, the injection dose for any injection into the second injection surface 120 is not greater than the first injection dose, that is, after the injection dose into the second injection surface 120 increases to the first injection dose, it will no longer increase, and subsequently, the first injection dose will be continuously injected into the second injection surface 120. In this example, if the second injection dose is less than the first injection dose, with the accumulation of the injection dose into the first injection surface 110, more stress may accumulate on the first injection surface 110. Therefore, to avoid warping of the wafer due to the accumulated stress on the first injection surface 110, in the embodiment of the present application, as the injection into the first injection surface 110 continues, the injection into the second injection surface 120 is carried out in a manner of increasing the injection dose equally to offset the accumulated stress on the first injection surface 110.

[0096] In yet another example, the first injection dose is greater than the third injection dose, the third injection dose is greater than the fifth injection dose, the fifth injection dose is greater than the seventh injection dose, the second injection dose, the fourth injection dose, and the sixth injection dose are the same, and the differences between the first injection dose and the third injection dose, between the third injection dose and the fifth injection dose, and between the fifth injection dose and the seventh injection dose are all the same. In this example, it is equivalent to determining the first injection dose and the second injection dose in step 1, and then injecting into the first injection surface 110 in a manner of equally decreasing the injection dose, and then injecting into the second injection surface 120 with the same injection dose each time. In this example, the injection dose for injecting into the first injection surface 110 gradually decreases, so excessive accumulated stress will not accumulate with the increase in the number of injections. Furthermore, maintaining the injection of the second injection dose into the second injection surface 120 each time can offset the stress generated on the first injection surface 110, ensuring that the wafer does not warp during the entire injection process.

[0097] If after injecting the seventh injection dose into the first injection surface 110 of the wafer, the total ion injection dose injected into the first injection surface 110 of the wafer reaches the target injection dose, then perform the above steps 5 and 6. If after injecting the seventh injection dose into the first injection surface 110 of the wafer, the total ion injection dose injected into the first injection surface 110 of the wafer does not reach the target injection dose, then continue to inject into the second injection surface 120 and the first injection surface 110 of the wafer until the total ion injection dose injected into the first injection surface 110 reaches the target injection dose.

[0098] It should be noted that if it is necessary to continue injecting into the second injection surface 120 and the first injection surface 110, for the injection dose injected into the second injection surface 120 and the first injection surface 110 each time, reference can be made to the description of any of the above embodiments, which will not be elaborated here.

[0099] The thickness of the thin film layer prepared in the embodiments of the present application can reach 100 - 1000 nm.

[0100] The present application has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limitations on the present application. Those skilled in the art understand that without departing from the spirit and scope of the present application, various equivalent substitutions, modifications or improvements can be made to the technical solutions and their implementation manners of the present application, and all of these fall within the scope of the present application. The protection scope of the present application is subject to the appended claims.

Claims

1. A method for improving the uniformity of a thin film, characterized in that, Including: Determine a first implantation dose implanted into the first implantation surface of the wafer and a second implantation dose implanted into the second implantation surface of the wafer according to the implantation parameters, where the first implantation dose is less than the target implantation dose, and the first implantation dose is not greater than the critical implantation dose. The second implantation dose is greater than or equal to 1 / 3 of the first implantation dose, and the second implantation dose is not greater than the critical implantation dose. The critical implantation dose refers to the maximum implantation dose that does not cause warping during the process of implanting ions into the first implantation surface of the wafer. The first implantation dose is the dose implanted into the first implantation surface of the wafer in a single implantation, and the second implantation dose is the dose implanted into the second implantation surface of the wafer in a single implantation; Implant into the first implantation surface of the wafer according to the first implantation dose; Implant into the second implantation surface of the wafer according to the second implantation dose; Implant a third implantation dose into the first implantation surface of the wafer, and the third implantation dose is not greater than the critical implantation dose; If the total implantation dose of ions implanted into the first implantation surface of the wafer reaches the target implantation dose, bond the first implantation surface to the substrate layer to obtain a bonded body; Heat-treat the bonded body to form a thin film layer on the substrate layer, and the thin film layer includes the first implantation surface.

2. The method according to claim 1, wherein The method further includes: If, after implanting the third implantation dose into the first implantation surface of the wafer, the total implantation dose of ions implanted into the first implantation surface of the wafer does not reach the target implantation dose, implant a fourth implantation dose into the second implantation surface of the wafer. The fourth implantation dose is greater than or equal to 1 / 3 of the third implantation dose, and the fourth implantation dose is not greater than the critical implantation dose; Implant a fifth implantation dose into the first implantation surface of the wafer, and the fifth implantation dose is not greater than the critical implantation dose; If the total implantation dose of ions implanted into the first implantation surface of the wafer reaches the target implantation dose, bond the first implantation surface to the substrate layer to obtain a bonded body; Heat-treat the bonded body to form a thin film layer on the substrate layer, and the thin film layer includes the first implantation surface.

3. The method according to claim 2, wherein The first implantation dose, the third implantation dose, and the fifth implantation dose are the same, and the fourth implantation dose is greater than or equal to the second implantation dose.

4. The method according to claim 3, characterized in that The second implantation dose is 1 / 3 - 1 times the first implantation dose, and the fourth implantation dose is 1 / 3 - 1 times the third implantation dose.

5. The method according to claim 2, wherein The fifth implantation dose is less than the third implantation dose, the third implantation dose is less than the first implantation dose, and the fourth implantation dose is equal to or less than the second implantation dose.

6. The method according to claim 2, wherein The fifth implantation dose is greater than the third implantation dose, the third implantation dose is greater than the first implantation dose, and the fourth implantation dose is equal to or greater than the second implantation dose.

7. The method according to claim 2, characterized in that The method further includes: If, after implanting the fifth implantation dose into the first implantation surface of the wafer, the total implantation dose of ions implanted into the first implantation surface of the wafer does not reach the target implantation dose, implant a sixth implantation dose into the second implantation surface of the wafer. The sixth implantation dose is greater than or equal to 1 / 3 of the fifth implantation dose, and the sixth implantation dose is not greater than the critical implantation dose; Inject a seventh implantation dose into the first implantation surface of the wafer, where the seventh implantation dose is not greater than the critical implantation dose; If the total ion implantation dose injected into the first implantation surface of the wafer reaches the target implantation dose, bond the first implantation surface to the substrate layer to obtain a bonded body; Heat-treat the bonded body to form a thin film layer on the substrate layer, where the thin film layer includes the first implantation surface.

8. The method according to claim 7, wherein The first implantation dose, the third implantation dose, the fifth implantation dose, and the seventh implantation dose are the same, the second implantation dose, the fourth implantation dose, and the sixth implantation dose are the same, and the second implantation dose is 1 / 3 - 1 times the first implantation dose.

9. The method according to claim 7, characterized in that, The first implantation dose, the third implantation dose, the fifth implantation dose, and the seventh implantation dose are the same, the sixth implantation dose is greater than the fourth implantation dose, the fourth implantation dose is greater than the second implantation dose, and the difference between the sixth implantation dose and the fourth implantation dose is equal to the difference between the fourth implantation dose and the second implantation dose.

10. The method according to claim 2, wherein The first implantation dose is greater than the third implantation dose, the third implantation dose is greater than the fifth implantation dose, the fifth implantation dose is greater than the seventh implantation dose, the second implantation dose, the fourth implantation dose, and the sixth implantation dose are the same, and the differences between the first implantation dose and the third implantation dose, between the third implantation dose and the fifth implantation dose, and between the fifth implantation dose and the seventh implantation dose are all the same.

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