阅读说明：本技术 应力调整膜层的形成方法以及应力调整膜层 (Method for forming stress adjustment film layer and stress adjustment film layer ) 是由 徐文浩 宋月 陈松超 马春龙 张高升 于 2019-09-30 设计创作，主要内容包括：本发明实施例公开了一种应力调整膜层的形成方法以及应力调整膜层,其中,所述方法包括：在晶圆上沉积应力调整子膜层,所述应力调整子膜层为部分厚度的所述应力调整膜层；采用紫外光照射沉积的所述应力调整子膜层,以提高所述应力调整子膜层的张应力。(The embodiment of the invention discloses a forming method of a stress adjusting film layer and the stress adjusting film layer, wherein the method comprises the following steps: depositing a stress adjustment sub-film layer on the wafer, wherein the stress adjustment sub-film layer is the stress adjustment film layer with partial thickness; and irradiating the deposited stress adjusting sub-film layer by adopting ultraviolet light so as to improve the tensile stress of the stress adjusting sub-film layer.)

1. A method for forming a stress adjustment film, the method comprising:

depositing a stress adjustment sub-film layer on the wafer, wherein the stress adjustment sub-film layer is the stress adjustment film layer with partial thickness;

and irradiating the deposited stress adjusting sub-film layer by adopting ultraviolet light so as to improve the tensile stress of the stress adjusting sub-film layer.

2. The method of claim 1, wherein the steps of depositing the stress adjusting sub-film layer and irradiating with the ultraviolet light are performed alternately and repeatedly to form the stress adjusting film layer on the wafer.

3. The method of claim 2, wherein the steps of depositing the stress adjusting sub-film layer and irradiating with ultraviolet light are repeated 2-20 times.

4. The method according to claim 1, wherein the duration of the irradiation with ultraviolet light is in the range of 0.5-2 min.

5. The method according to claim 1, wherein the irradiation intensity of the ultraviolet light is in the range of 0.07-50mW/cm²。

6. The method according to claim 1, wherein the irradiating the deposited stress adjusting sub-film layer with ultraviolet light comprises:

when the thickness of the stress adjustment sub-film layer deposited on the wafer is

7. The method of claim 1, wherein the stress adjusting sub-film layer comprises a silicon nitride layer.

8. The method of claim 1, wherein the stress adjusting film layer is formed on a backside of the wafer.

9. A stress adjustment film formed by the method of any one of claims 1 to 8.

Technical Field

The present invention relates to the field of semiconductor technology, and in particular, to a method for forming a stress adjustment film and a stress adjustment film.

Background

In a semiconductor manufacturing process, the flatness of a wafer substrate is critical to deposition, photolithography, and other processes. In order to control the warpage amount (bow value) of the wafer, it is common to deposit a silicon nitride (SiN) film on the back side (back side) of the wafer in actual production and process development to balance the warpage of the wafer. In the related art, a high-stress SiN film is often prepared at a relatively low temperature, and the SiN film has a problem of low stress after deposition, so that the bow value of a wafer cannot be effectively improved. At present, the main method for improving the stress of the SiN film on the back surface of the wafer is to carry out high-temperature thermal treatment after deposition to enable hydrogen elements of reaction residues in the SiN film to escape, so that the compactness of the SiN film and the bonding amount of silicon nitrogen are improved, and the stress of the SiN film is improved.

However, the high temperature heat treatment process is performed after the SiN film is deposited on the back surface of the wafer, and the SiN film is easily peeled and dropped off from the back surface of the wafer due to a large change in stress of the SiN film during the heat treatment. Therefore, how to avoid the peeling and peeling problem while increasing the stress of the SiN film becomes one of the technical problems that needs to be solved in the art at the present stage.

Disclosure of Invention

In view of the foregoing, the present invention provides a method for forming a stress adjustment film and a stress adjustment film.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

the embodiment of the invention provides a method for forming a stress adjustment film layer, which comprises the following steps:

depositing a stress adjustment sub-film layer on the wafer, wherein the stress adjustment sub-film layer is the stress adjustment film layer with partial thickness;

and irradiating the deposited stress adjusting sub-film layer by adopting ultraviolet light so as to improve the tensile stress of the stress adjusting sub-film layer.

In the above scheme, the step of depositing the stress adjustment sub-film layer and the step of irradiating with ultraviolet light are alternately performed repeatedly to form the stress adjustment film layer on the wafer.

In the above scheme, the repetition times of the step of depositing the stress adjustment sub-film layer and the step of irradiating with ultraviolet light are 2 to 20 times.

In the scheme, the duration range of the ultraviolet irradiation is 0.5-2 min.

In the above scheme, the radiation intensity range irradiated by ultraviolet light is 0.07-50mW/cm²。

In the foregoing solution, the step of irradiating the deposited stress adjustment sub-film layer with ultraviolet light specifically includes:

when the thickness of the stress adjustment sub-film layer deposited on the wafer isAnd irradiating the deposited stress adjusting sub-film layer by using ultraviolet light.

In the above scheme, the stress adjustment sub-film layer includes a silicon nitride layer.

In the above scheme, the stress adjustment film layer is formed on the back surface of the wafer.

The embodiment of the invention also provides a stress adjustment film layer, which is prepared by the method in any one of the schemes.

The stress adjustment film layer and the forming method thereof provided by the embodiment of the invention have the following steps: depositing a stress adjustment sub-film layer on the wafer, wherein the stress adjustment sub-film layer is the stress adjustment film layer with partial thickness; and irradiating the deposited stress adjusting sub-film layer by adopting ultraviolet light so as to improve the tensile stress of the stress adjusting sub-film layer. Therefore, the stress of the stress adjusting sub-film layer is improved by irradiating the stress adjusting sub-film layer deposited on the wafer by ultraviolet light, and the bow value of the wafer is effectively improved; because the ultraviolet light irradiation method can improve the stress of the film layer in the forming process of the stress adjusting film layer, when the stress adjusting film layer with partial thickness is deposited (namely the stress adjusting sub-film layer is formed), the ultraviolet light irradiation process can be executed, the influence of the temperature condition on the stress adjusting film layer is reduced when the film layer is subjected to high-temperature heat treatment after being manufactured, and the stripping and falling risks of the stress adjusting film layer are reduced.

Drawings

Fig. 1 is a schematic flow chart illustrating a method for forming a stress adjustment film according to an embodiment of the invention;

fig. 2 is a schematic cross-sectional view of a device structure in a process of forming a stress adjustment film according to an embodiment of the invention.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the present invention; that is, not all features of an actual embodiment are described herein, and well-known functions and structures are not described in detail.

In the drawings, the size of layers, regions, elements, and relative sizes may be exaggerated for clarity. Like reference numerals refer to like elements throughout.

It will be understood that when an element or layer is referred to as being "on" … …, "adjacent to … …," "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on … …," "directly adjacent to … …," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. And the discussion of a second element, component, region, layer or section does not necessarily imply that a first element, component, region, layer or section is present in the invention.

Spatial relationship terms such as "under … …", "under … …", "below", "under … …", "above … …", "above", and the like, may be used herein for ease of description to describe the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below … …" and "below … …" can encompass both an orientation of up and down. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The following detailed description of the preferred embodiments of the invention, however, the invention is capable of other embodiments in addition to those detailed.

The embodiment of the invention provides a method for forming a stress adjustment film layer; please refer to fig. 1. As shown, the method comprises the steps of:

step 101, depositing a stress adjustment sub-film layer on a wafer, wherein the stress adjustment sub-film layer is the stress adjustment film layer with partial thickness;

and 102, irradiating the deposited stress adjusting sub-film layer by using ultraviolet light so as to improve the tensile stress of the stress adjusting sub-film layer.

It can be understood that, in the method provided by the embodiment of the present invention, the stress adjustment sub-film layer deposited on the wafer is irradiated by the ultraviolet light, so that the stress of the stress adjustment sub-film layer is increased, and the bow value of the wafer is effectively improved; because the ultraviolet light irradiation method can improve the stress of the film layer in the forming process of the stress adjusting film layer, when the stress adjusting film layer with partial thickness is deposited (namely the stress adjusting sub-film layer is formed), the ultraviolet light irradiation process can be executed, the influence of the temperature condition on the stress adjusting film layer is avoided when the film layer is subjected to high-temperature heat treatment after being manufactured, and the stripping and falling risks of the stress adjusting film layer are reduced.

Here, the stress adjustment film layer is formed on the back surface of the wafer, for example. The back surface of the wafer is relative to the front surface of the wafer; generally, a wafer has a front side for forming semiconductor devices (e.g., 3D NAND memory) and a back side; when the steps in the method provided in this embodiment are executed, the wafer may be a wafer that is not processed by any process, or may be a semi-finished wafer that has been processed by multiple semiconductor processing processes (e.g., plating, photolithography, deposition, grinding, etc.); the back side is a surface of the wafer opposite the front side. It should be understood that the formation location of the stress adjustment film layer is not limited thereto, and in other embodiments of the present application, the stress adjustment film layer may also be formed on the front surface of the wafer to adjust the stress at the predetermined location on the front surface of the wafer.

The material of the wafer may include at least one of: silicon (Si), Germanium (Ge), Silicon Germanium (SiGe), Silicon On Insulator (SOI), Germanium On Insulator (Germanium On Insulator), and the like; in one embodiment, the wafer is a single crystal silicon wafer.

In one embodiment, the step of depositing the stress adjustment sub-film and the step of irradiating with ultraviolet light are performed alternately and repeatedly to form the stress adjustment film on the wafer. FIG. 2 is a cross-sectional view of a device structure during the formation of a stress adjustment film according to an embodiment of the present invention; as shown in the figure, the preparation of the stress adjusting film layer with high tensile stress is realized through deposition and ultraviolet irradiation circulation.

Of course, the embodiment of the present application is not limited thereto, and the stress adjustment film layer in the embodiment of the present application may be formed by at least two deposition steps, in other words, the stress adjustment film layer includes at least two stress adjustment sub-film layers; and the forming process of the stress adjustment film layer comprises at least one step of irradiating the deposited stress adjustment sub-film layer by using ultraviolet light after the deposition step.

The stress adjustment sub-film layer irradiated with ultraviolet light may be any part of the stress adjustment film layer. For example, in one embodiment, the method comprises: depositing a first stress adjustment sub-film layer on the wafer; irradiating the deposited first stress adjusting sub-film layer with ultraviolet light; depositing a second stress adjusting sub-film layer on the first stress adjusting sub-film layer; performing any one of the following on the second stress adjustment sub-film layer: without any treatment, adopting ultraviolet irradiation to improve the tensile stress, adopting heat treatment to improve the tensile stress, adopting ultraviolet irradiation and heat treatment to improve the tensile stress; in another embodiment, the method may comprise: depositing a first stress adjustment sub-film layer on the wafer; improving the tensile stress of the first stress adjustment sub-film layer by adopting heat treatment; depositing a second stress adjusting sub-film layer on the first stress adjusting sub-film layer; and irradiating the deposited second stress adjustment sub-film layer by using ultraviolet light. The first and second stress adjustment sub-film layers are only for illustration, and other stress adjustment sub-film layers may be deposited on the wafer before the first stress adjustment sub-film layer is deposited, and the method may further include a step of depositing other stress adjustment sub-film layers after the second stress adjustment sub-film layer is deposited.

The deposition process of the stress adjusting film layer or the stress adjusting sub-film layer can be a chemical vapor deposition process; in one embodiment, the stress adjusting sub-film layer is deposited on the back surface of the wafer by a Plasma Enhanced Chemical Vapor Deposition (PECVD) process. Specifically, as shown in fig. 2, a wafer on which a stress adjustment film layer is to be formed is placed in a reaction chamber; the step of depositing the stress adjustment sub-film layer is as shown in the left figure, forming a gas containing film component atoms into Plasma (Plasma), and depositing the stress adjustment sub-film layer on the back surface of the wafer by utilizing the activity of the Plasma; the step of irradiating with ultraviolet light is shown in the right diagram, and ultraviolet light (UV) irradiation is performed on the back surface of the wafer on which the partial stress adjustment film layer (i.e., the stress adjustment sub-film layer) is deposited, so as to improve the tensile stress of the stress adjustment sub-film layer.

It should be understood that the step of depositing the stress adjusting sub-film layer and the step of irradiating with ultraviolet light may be performed in different apparatuses; however, in a preferred embodiment of the present application, the step of depositing the stress adjusting sub-film layer and the step of irradiating with ultraviolet light are performed in different chambers of the same apparatus, or at different positions of the same apparatus.

The repetition times of the step of depositing the stress adjustment sub-film layer and the step of irradiating with ultraviolet light are 2-20 times. In other words, the process of forming the stress adjustment film layer on the back of the wafer by one deposition in the related art is divided into 2-20 times, and after a part of the stress adjustment film layer is deposited, one ultraviolet irradiation is performed until the required stress adjustment film layer is completely formed.

The duration range of the ultraviolet irradiation is 0.5-2 min. In the complete forming process of the stress adjustment film layer, the total duration of ultraviolet irradiation is in the range of 1-40 min.

The radiation intensity range irradiated by the ultraviolet light is 0.07-50mW/cm²(ii) a The power range is for example 1000W-20000W.

The stress adjustment sub-film layer deposited by ultraviolet irradiation specifically comprises: when the thickness of the stress adjustment sub-film layer deposited on the wafer is

(angstrom), the deposited stress adjusting sub-film layer is irradiated with ultraviolet light.

The material of the stress adjusting sub-film layer can be selected from materials commonly used in the art and having the function of balancing and adjusting the wafer stress. In one embodiment, the stress adjustment sub-film layer includes a silicon nitride layer. In other embodiments, the stress adjustment sub-film layer may also include a silicon oxynitride layer, etc.

On this basis, the embodiment of the invention also provides a stress adjustment film layer, which is prepared by the method in any one of the above schemes.

In one embodiment, the tensile stress of the stress adjustment sub-film layer formed by ultraviolet irradiation can reach 1200MPa, which is much higher than the tensile stress (about 600MPa) of the stress adjustment film layer deposited in the related art; in the related art, the high-temperature heat treatment process is adopted to increase the tensile stress of the deposited stress adjustment film layer, and although the tensile stress can also be increased to a preset requirement (such as 1200MPa), the stress adjustment film layer is easy to peel off or fall off from the back surface of the wafer due to the huge change of the stress; the stress adjusting film layer formed by the method provided by the embodiment of the application has the advantages that the tensile stress is improved, the property of the film layer tends to be stable, and the stress cannot be changed greatly, so that the influence of the temperature condition on the stress adjusting film layer can be reduced when the film layer is subjected to high-temperature heat treatment after being manufactured, and the stripping and falling risks are reduced.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, and any modifications, equivalents, improvements, etc. that are within the spirit and principle of the present invention should be included in the present invention.