Etching methods

Abstract

This application discloses an etching method, comprising: covering photoresist on a dielectric layer using a photolithography process to expose a target area; etching to a predetermined depth in the dielectric layer of the target area to form various types of trenches, including a first trench corresponding to an OVL mark; during the etching process, controlling the pressure of the reactive gas to flatten the bottom of the first trench; and removing the photoresist. This application solves the problem of a raised bottom in the first trench caused by micro-loading effects by controlling the pressure of the reactive gas to flatten the bottom of the first trench corresponding to the OVL mark during the etching process of the OVL mark and other areas. This avoids process problems caused by unclear OVL marks and improves device yield.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and specifically to an etching method. Background Technology

[0002] In photolithography, after the photoresist is patterned, the wafer undergoes overlay (OVL) measurement to ensure that the patterning parameters are within the allowable process range; otherwise, subsequent processes cannot proceed normally. During OVL measurement, it is crucial to ensure high clarity of the OVL marks; otherwise, OVL measurement will fail. Therefore, the etching of OVL marks is of paramount importance in photolithography.

[0003] refer to Figure 1 It shows a cross-sectional schematic diagram of an OVL mark etched using an etching method provided by related technologies; Reference Figure 2 This illustrates a cross-sectional schematic diagram of the subsequent formation of the metal layer. For example, such as... Figure 1 and Figure 2 As shown:

[0004] During the etching process of semiconductor devices, the trenches 101 corresponding to the OVL markings are also etched. Since the width of the trenches 101 is typically larger than that of the device... Figure 1 The width (not shown in the image) will, under the influence of macroloading, result in a raised morphology at the bottom of the trench 101 if the trench is shallow (e.g., ...). Figure 1 As shown by the dashed line, the OVL marking is unclear, which affects subsequent processes (such as...). Figure 2 As shown, the subsequent formation of the first metal layer 121 and the second metal layer 122 will have an impact. Summary of the Invention

[0005] This application provides an etching method that can solve the problem of bulging at the bottom of the OVL marking trench due to micro-loading effects in the etching methods provided in the related art. The method includes:

[0006] Photoresist is applied to the dielectric layer using photolithography to expose the target area;

[0007] Etching is performed to a predetermined depth in the dielectric layer of the target area to form various types of trenches, including a first trench, which is the trench corresponding to the OVL mark. During the etching process, the bottom of the first trench is flattened by controlling the pressure of the reactive gas.

[0008] Remove light resistance.

[0009] In some embodiments, the pressure of the reaction gas during the etching process is 20 to 40 millitors.

[0010] In some embodiments, the reaction gas in the etching process includes octafluorocyclobutane, or includes octafluorocyclobutane and oxygen.

[0011] In some embodiments, the dosage of octafluorocyclobutane during the etching process is 30 to 50 millicubic centimeters.

[0012] In some embodiments, the various types of grooves further include a second groove, which is a groove corresponding to a contact hole, and the width of the first groove is greater than the width of the second groove.

[0013] In some embodiments, after removing the photoresist, the method further includes:

[0014] A first metal layer is filled into the first trench and the second trench;

[0015] A second metal layer is formed on the first metal layer.

[0016] In some embodiments, the first metal layer is a tungsten layer and the second metal layer is an aluminum layer.

[0017] The technical solution of this application has at least the following advantages:

[0018] By controlling the gas pressure of the reactive gas during the etching process of the OVL mark and other areas, the bottom of the first trench corresponding to the OVL mark is made flat, which solves the problem of the bottom of the first trench protruding due to the micro-loading effect. This avoids the process problems caused by unclear OVL marks and improves the yield of the device. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a cross-sectional schematic diagram of an OVL mark formed by etching using an etching method provided by related technologies;

[0021] Figure 2 This is a cross-sectional schematic diagram of the metal layer subsequently formed in the related technology;

[0022] Figure 3 This is a flowchart of an etching method provided in an exemplary embodiment of this application;

[0023] Figure 4This is a schematic cross-sectional view of an OVL mark etched by an etching method provided in an exemplary embodiment of this application. Detailed Implementation

[0024] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0027] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0028] refer to Figure 3 The diagram illustrates a flowchart of an etching method provided in an exemplary embodiment of this application. This method can be applied to etching trenches corresponding to OVL marks and contact holes, such as... Figure 3 As shown, the method includes:

[0029] Step S1: Photoresist is applied to the dielectric layer using photolithography to expose the target area.

[0030] Step S2: Etching is performed to a predetermined depth in the dielectric layer of the target area to form various types of trenches. The various types of trenches include a first trench, which is the trench corresponding to the OVL mark. During the etching process, the bottom of the first trench is flattened by controlling the gas pressure of the reaction gas.

[0031] For example, the various types of grooves also include a second groove, which is a groove corresponding to a contact hole (via), and the width of the first groove is greater than the width of the second groove.

[0032] The reaction gas used in the etching process includes octafluorocyclobutane (C4F8), or octafluorocyclobutane and oxygen (O2). Optionally, the pressure of the reaction gas during etching is from 20 mTorr to 40 mTorr; and the dosage of octafluorocyclobutane during etching is from 30 m³ / cm³ to 50 m³ / cm³.

[0033] By setting the pressure of the reactant gas to 20 mTorr to 40 mTorr and the dosage of octafluorocyclobutane to 30 m³ to 50 m³, the bottom of the first trench can be made to have the flattest morphology.

[0034] Step S3: Remove photoresist.

[0035] like Figure 4 As shown, by controlling the gas pressure of the reactive gas and the dosage of octafluorocyclobutane during the etching process in step S2, the bottom of the first trench 401 formed in the dielectric layer 410 has a flat morphology (as shown). Figure 4 (As shown by the dashed line), it does not have protrusions. Among them, the dielectric layer 410 is an oxide layer (e.g., a silicon dioxide (SiO2) layer).

[0036] Following step S3, the process further includes: filling the first trench and the second trench with a first metal layer; and forming a second metal layer on the first metal layer. The first metal layer is a tungsten (W) layer, and the second metal layer is an aluminum (Al) layer. The first and second metal layers can be formed sequentially using a physical vapor deposition (PVD) process.

[0037] In summary, in this embodiment of the application, by controlling the gas pressure of the reaction gas during the etching process of the OVL mark and other areas to make the bottom of the first trench corresponding to the OVL mark flat, the phenomenon of the bottom of the first trench protruding due to the micro-loading effect is solved, thereby avoiding the process problems caused by unclear OVL marks and improving the yield of the device.

[0038] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. An etching method, characterized in that, include: Photoresist is applied to the dielectric layer using photolithography to expose the target area; Etching is performed to a predetermined depth in the dielectric layer of the target area to form various types of trenches, including a first trench, which is the trench corresponding to the OVL mark. During the etching process, the bottom of the first trench is flattened by controlling the pressure of the reactive gas. Remove light obstruction; The gas pressure of the reaction gas during the etching process is 20 mTorr to 40 mTorr, and the reaction gas during the etching process includes octafluorocyclobutane, or includes octafluorocyclobutane and oxygen. The dosage of octafluorocyclobutane during the etching process is 30 m³ to 50 m³.

2. The method according to claim 1, characterized in that, The various types of grooves also include a second groove, which is a groove corresponding to the contact hole, and the width of the first groove is greater than the width of the second groove.

3. The method according to claim 2, characterized in that, After removing the photoresist, the method further includes: A first metal layer is filled into the first trench and the second trench; A second metal layer is formed on the first metal layer.

4. The method according to claim 3, characterized in that, The first metal layer is a tungsten layer, and the second metal layer is an aluminum layer.

Images