WO2023169041A1

WO2023169041A1 - Patterning method for film layer and preparation method for semiconductor device

Info

Publication number: WO2023169041A1
Application number: PCT/CN2022/140333
Authority: WO
Inventors: 李翔; 谢志平; 丛茂杰
Original assignee: 绍兴中芯集成电路制造股份有限公司
Priority date: 2022-03-10
Filing date: 2022-12-20
Publication date: 2023-09-14
Also published as: CN114334642A; CN114334642B

Abstract

Provided in the present invention are a patterning method for a film layer and a preparation method for a semiconductor device. In the patterning method for a film layer, plasma surface treatment is performed on a portion, which needs to be reserved, in a thin-film material layer by means of a mask in a photoresist layer, such that the top surface of the portion is passivated to form a passivation layer, and the formed passivation layer can be used for protecting thin-film material below the passivation layer from being removed, thereby achieving a patterning effect of the film layer. By using the patterning method provided in the present invention, the problem of photoresist residues can be effectively ameliorated, defects caused by a patterning process are reduced, the process is simple, and further optimization of the patterning process is realized.

Description

Patterning method of film layer and preparation method of semiconductor device

Technical field

The invention relates to the field of semiconductor technology, and in particular to a patterning method for a film layer and a method for preparing a semiconductor device.

Background technique

In semiconductor processing, the patterning process is used to achieve the preparation of specific pattern structures and is an essential and crucial processing step. An existing patterning method includes: first, forming a patterned photoresist layer on the thin film material layer to be patterned, so that the photoresist layer covers the parts that do not need to be removed; then, the thin film material layer is The portion of the film material layer that is not covered by the photoresist layer is removed, and the portion of the film material layer that is covered by the photoresist layer is retained to achieve patterning of the film layer, and finally the photoresist layer can be further removed. Another patterning method is achieved by using a lift-off process, that is, a patterned photoresist layer is first formed on the substrate, and the area where the film layer needs to be formed is exposed in the photoresist layer; then, deposition After that, the photoresist layer is peeled off to simultaneously remove the thin film material attached to the photoresist layer, so that the thin film material in the area where the film layer needs to be formed is retained, thereby forming a patterned film layer.

However, both of the above-mentioned patterning methods have certain process defects. For example, photoresist easily remains on the substrate, causing device defects. In addition, for the lift-off process, its process capability is also limited by the thickness of the photoresist layer, making it difficult to be used in the patterning process of larger thickness film layers.

Contents of the invention

The object of the present invention is to provide a patterning method for a film layer to optimize the patterning effect and reduce defects caused by the patterning process.

In order to solve the above technical problems, the present invention provides a method for patterning a film layer, which includes: forming a thin film material layer on a substrate; forming a patterned photoresist layer on the thin film material layer, and the patterning method The photoresist layer exposes part of the thin film material layer; the exposed part of the thin film material layer is subjected to plasma surface treatment to passivate the top of the exposed thin film material layer to form a passivation layer; and, remove all The photoresist layer, and remove the portion of the thin film material layer not covered with the passivation layer, wherein the erosion rate of the portion of the thin film material layer not covered with the passivation layer is higher than that of the passivation layer The erosion rate of the passivation layer is such that the portion of the thin film material layer covered with the passivation layer is retained.

Optionally, the plasma surface treatment is performed using oxygen-containing ions to form an oxide layer on top of the thin film material layer.

Optionally, the plasma surface treatment is performed using nitrogen-containing ions to form a nitride layer on top of the thin film material layer.

Optionally, after removing the photoresist layer, use a wet etching process and/or a dry etching process to etch the thin film material layer to remove the passivation layer not covered by the thin film material layer. layer part.

Optionally, the material of the thin film material layer includes nickel. Wherein, after using the photoresist stripping liquid to remove the photoresist layer, the photoresist stripping liquid can be used to erode the thin film material layer to remove the passivation layer not covered by the thin film material layer. layer part.

Optionally, the thin film material layer is a metal material layer. And, after removing the portion of the thin film material layer that is not covered with the passivation layer, a thermal annealing process may also be included.

Optionally, the substrate includes a silicon substrate or a silicon carbide substrate.

The present invention also provides a method for preparing a semiconductor device, including the patterning method of the film layer as described above.

In the patterning method of the film layer provided by the present invention, the photoresist layer is formed above the film material layer to be patterned, which avoids the photoresist layer from contacting the substrate surface and reduces the photoresist residue on the substrate. Bottom risk. After that, plasma surface treatment is performed on the portion of the thin film material layer that needs to be retained under the mask of the photoresist layer, so that the top surface of the portion is passivated to form a passivation layer, so that the formed passivation layer can be used The thin film material underneath is protected from being removed, and only the portion of the thin film material layer that is not covered by the passivation layer is removed to realize the patterning process of the film layer. That is, in the present invention, the patterned photoresist layer covers the portion of the thin film material layer that needs to be removed. Therefore, even if there is photoresist residue when the photoresist layer is peeled off, when the thin film material layer is subsequently etched The remaining photoresist will be further removed to prevent the photoresist residue from adhering to the substrate and making it difficult to remove. Therefore, the patterning method provided by the present invention effectively reduces the defects caused by the patterning process, and the process is simple, achieving further optimization of the patterning process.

Description of the drawings

FIG. 1 is a schematic flowchart of a method for patterning a film layer in an embodiment of the present invention.

2-5 are schematic structural diagrams of the film layer during the patterning process in one embodiment of the present invention.

Among them, the reference numbers are as follows: 100-substrate; 200-thin film material layer; 210-passivation layer; 300-photoresist layer.

Detailed ways

The core idea of the present invention is to provide a new film layer patterning method. For details, please refer to Figure 1. The patterning method in one embodiment of the present invention may include the following steps.

Step S100, forming a thin film material layer on a substrate.

Step S200: Form a patterned photoresist layer on the thin film material layer, and the patterned photoresist layer exposes part of the thin film material layer.

Step S300: Perform plasma surface treatment on the exposed portion of the thin film material layer to passivate the top of the exposed thin film material layer to form a passivation layer.

Step S400: Remove the photoresist layer and remove the portion of the thin film material layer that is not covered with the passivation layer.

That is, in the patterning method provided by the present invention, plasma surface treatment is performed on the portion of the thin film material layer that needs to be retained under the mask of the photoresist layer, so that the top surface of the portion is passivated to form a passivation layer. , so that the formed passivation layer can be used to protect the thin film material below it from being removed, and only the portion of the thin film material layer that is not covered by the passivation layer is removed to realize the patterning process of the thin film layer.

The film patterning method and the semiconductor device preparation method proposed by the present invention will be further described in detail below with reference to FIGS. 1 and 2 to 5 and specific embodiments. 1 is a schematic flowchart of a method for patterning a film layer in an embodiment of the present invention, and FIGS. 2 to 5 are schematic structural diagrams of a film layer in the patterning process in an embodiment of the present invention. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use imprecise proportions, and are only used to conveniently and clearly assist in explaining the embodiments of the present invention. It will be understood that relative terms such as "above", "below", "top", "bottom", "above" and "below" when used in the drawings may be used to describe various elements relative to each other. relation. These relative terms are intended to encompass different orientations of the elements in addition to the orientation depicted in the figures. For example, if the device is turned upside down relative to the view in the figures, an element described as "above" another element would now be oriented below that element.

In step S100, with specific reference to FIG. 2, a thin film material layer 200 is formed on a substrate 100.

The substrate 100 may be a silicon substrate, a silicon germanium substrate, a silicon carbide substrate, etc.; for example, in one example, the substrate 100 is a silicon carbide epitaxial wafer, and the thickness of the silicon carbide epitaxial wafer is, for example, 200um～500um.

Further, the material and thickness of the thin film material layer 200 can be selected based on actual conditions. For example, the thin film material layer 200 may be a conductive material layer, where the conductive material includes, for example, a metal material. In this embodiment, the thin film material layer 200 is a metal material layer as an example. The metal material may include nickel or titanium, or a combination of both, and the thickness of the metal material layer may be, for example, 50 nm- 600nm.

In step S200, with specific reference to FIG. 3, a patterned photoresist layer 300 is formed on the thin film material layer 200. The photoresist layer 300 covers the portion of the thin film material layer 200 that needs to be removed, and exposes the portion of the thin film material layer 200 that needs to be retained.

It should be appreciated that the photoresist layer 300 is formed above the thin film material layer 200 and does not contact the surface of the substrate 100 , so the photoresist does not remain on the surface of the substrate 100 .

In contrast, in the traditional lift-off process, a photoresist layer needs to be formed on the surface of the substrate, and the surface of the substrate where the metal layer needs to be formed is exposed through photolithography and development. Photoresist is likely to remain on the exposed substrate surface, and when the metal layer is subsequently formed, it will further cause poor contact between the metal layer and the substrate. In addition, the stripping process also has certain process limitations. For example, due to the thickness limit of the photoresist layer, it is difficult to realize the patterning process of a relatively thick metal layer.

It can be seen that compared with the patterning method of the stripping process, the patterning method provided in this embodiment can effectively avoid the problem of photoresist remaining on the surface of the substrate, especially when facing the patterning of the metal layer. Correspondingly, the problem of poor contact performance caused by photoresist residue between the formed metal layer and the substrate can be avoided. In addition, the patterning method provided by this implementation is also helpful to overcome the process limitations existing in the stripping process and reduce the difficulty of the patterning process.

In step S300 , with specific reference to FIG. 4 , plasma surface treatment is performed on the exposed portion of the thin film material layer 200 to passivate the top of the exposed thin film material layer 200 to form a passivation layer 210 .

Specifically, the properties of the film layer on the top of the thin film material layer 200 are changed by passivating the top of the thin film material layer 200, so that the top passivated portion and the unpassivated portion of the thin film material layer 200 can be used in the subsequent etching process. have different etching rates respectively, for example, the etching selectivity ratio of the unpassivated part and the top passivated part is greater than or equal to 10:1. That is, the passivation layer 210 in the thin film material layer and the unpassivated portion of the thin film material layer have different etching rates.

It should be noted that in this embodiment, plasma is used to perform surface treatment on the thin film material layer 200 . At this time, only the top surface of the thin film material layer 200 and a small portion close to the top surface will be passivated, and the surface treatment will not be carried out. The entire thickness of the thin film material layer 200 forms passivation. That is, the thin film material layer 200 after surface treatment still has an unpassivated portion below its top; for example, taking the metal material layer as an example, after surface treatment of the metal material layer, only the top of the metal material layer can be passivated. , while the lower part of the metal material layer is not passivated and still maintains its original properties (for example, conductive properties, etc.).

In an optional solution, oxygen-containing plasma can be used to perform plasma surface treatment. At this time, an oxide layer can be formed on the top of the exposed thin film material layer 200 in an oxygen atmosphere. The formed oxide layer is The passivation layer 210 is formed. Taking a metal material layer as an example, a metal oxide layer will be formed on the top of the metal material layer in an oxygen atmosphere, and the metal oxide layer will constitute the passivation layer 210. For example, for a nickel metal layer The top will be passivated to form nickel oxide.

In another optional solution, nitrogen-containing plasma can also be used to perform plasma surface treatment. At this time, the top of the exposed thin film material layer 200 can form a nitride layer in a nitrogen atmosphere. The formed nitrogen The passivation layer 210 is formed by the chemical layer. Taking the metal material layer as an example, a metal nitride layer will be formed on the top of the metal material layer in a nitrogen atmosphere. For example, for a nickel metal layer, the top of the metal material layer will be passivated to form nickel nitride.

In step S400, with specific reference to FIG. 5, the photoresist layer is removed, and the portion of the thin film material layer 200 that is not covered with the passivation layer 210 is removed. That is, the portion of the thin film material layer covered by the photoresist layer will continue to be removed.

Wherein, the photoresist layer can be removed using a photoresist stripping solution. It should be noted that since the portion of the thin film material layer 200 covered by the photoresist layer corresponds to the portion that needs to be removed subsequently, even if there is photoresist residue after the photoresist layer is peeled off, As the subsequent thin film material layer is further removed, the remaining photoresist on it will be removed at the same time, thereby preventing the photoresist from remaining on the substrate.

In contrast, in the traditional patterning process, the patterned photoresist layer needs to cover the parts of the thin film material layer that need to be retained, and expose the parts of the thin film material layer that do not need to be retained, and then based on the photoresist layer The thin film material layer is etched under a mask so that the portion of the thin film material layer covered by the photoresist layer is retained, and then the photoresist layer is removed. At this time, when the photoresist layer is removed, it is easy to cause The photoresist remains on the patterned film layer, and the photoresist residue in the stripping solution also easily adheres to the exposed substrate surface.

Compared with the traditional patterning process as described above, in the patterning method provided by this embodiment, when the photoresist layer is removed, the thin film material layer 200 still covers the surface of the substrate 100, so the light can be effectively avoided. The resist remains or adheres to the substrate surface; and with subsequent further etching of the thin film material layer 200, it is also beneficial to remove the remaining photoresist.

Specifically, after the photoresist layer is removed, the portion of the thin film material layer 200 that needs to be removed is exposed, and a wet etching process and/or a dry etching process can be used to etch the portion. The thin film material layer 200 is used to remove the portion of the thin film material layer 200 that is not covered by the passivation layer 210 . As mentioned above, the passivated portions of the passivation layer 210 and the thin film material layer 200 have different etching selectivity ratios. Therefore, the portions of the thin film material layer 200 that need to be retained can be added to the passivation layer 210 It will not be removed under protection, and the portion of the thin film material layer 200 that is not covered by the passivation layer will be etched.

In a specific solution, a corresponding etching method and etchant can be selected according to the material of the thin film material layer 200 . For example, for a metal material layer, a metal etching solution can be used to wet-etch the metal material layer. If the thin film material layer 200 is a nickel layer or a titanium layer, for example, a nickel metal etching solution or a titanium layer can be used. Metal etching liquid etches the thin film material layer 200 . In addition, for the nickel metal layer, the photoresist stripping solution can also be directly sampled to etch the thin film material layer 200, which is beneficial to simplifying the process and saving costs. Specifically, the photoresist layer can be removed using EKC stripping liquid, and then the exposed nickel metal layer can be removed using the EKC stripping liquid.

Referring to FIG. 5 , the portion of the thin film material layer not covered with the passivation layer 210 is removed, and the portion covered with the passivation layer 210 is retained to form a patterned thin film layer. It should be appreciated that in the patterned thin film layer, the top part is the passivation layer 210 formed after passivation, while the bottom part of the passivation layer 210 is still an unpassivated part. In an optional solution, the passivation layer 210 can be further removed.

In this embodiment, taking the thin film material layer as a metal material layer as an example, after patterning the metal material layer, it may also include: performing a thermal annealing process. Specifically, through the thermal annealing process, the metal in the metal material layer and the silicon in the substrate can react to generate metal silicide, forming an ohmic contact structure with low contact resistance.

In summary, this embodiment provides a method for patterning a film layer, which specifically involves performing plasma surface treatment on the portion of the thin film material layer that needs to be retained under the mask of the photoresist layer, so that the top surface of the portion is The surface is passivated to form a passivation layer, so that the formed passivation layer can be used to protect the film material below it from being removed, and only the part of the film material layer that is not covered with the passivation layer is removed to achieve the purpose of removing the passivation layer. Graphical process. In this way, the photoresist can be effectively prevented from contacting the substrate surface, reducing the risk of photoresist remaining on the substrate and reducing defects caused by the patterning process.

In addition, further applying the above-described film layer patterning method to a method of manufacturing a semiconductor device is also beneficial to improving the performance of the prepared semiconductor device. That is, in a method of manufacturing a semiconductor device, the patterning method as described above can be used to implement the patterning process. For example, the above-mentioned patterning method can be used to prepare an ohmic contact structure on a substrate, which has lower contact resistance between the prepared ohmic contact structure and the substrate and improves contact performance.

It should be noted that although the present invention has been disclosed above in preferred embodiments, the above embodiments are not intended to limit the present invention. For any person familiar with the art, without departing from the scope of the technical solution of the present invention, they can use the technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into equivalent changes. Example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

Furthermore, it should be appreciated that the terminology described herein is used only to describe particular embodiments and is not intended to limit the scope of the invention. It must be noted that, as used herein and in the appended claims, the singular forms "a", "an" and "an" include plural referents unless the context clearly dictates a contrary meaning. For example, a reference to "a step" or "a means" means a reference to one or more steps or means, and may include secondary steps as well as secondary means. All conjunctions used should be understood in their broadest sense. and, the word "or" shall be understood to have the definition of a logical "or" and not the definition of a logical "exclusive-or" unless the context clearly indicates the contrary.

Claims

A method for patterning a film layer, which is characterized by including:

forming a layer of thin film material on a substrate;

Form a patterned photoresist layer on the thin film material layer, and the patterned photoresist layer exposes part of the thin film material layer;

Perform plasma surface treatment on the exposed portion of the thin film material layer to passivate the top of the exposed thin film material layer to form a passivation layer; and,

Remove the photoresist layer, and remove the portion of the thin film material layer that is not covered with the passivation layer, wherein the erosion rate of the portion of the thin film material layer that is not covered with the passivation layer is high The erosion rate of the passivation layer is such that the portion of the thin film material layer covered with the passivation layer is retained.
The patterning method of a film layer according to claim 1, wherein the plasma surface treatment is performed using oxygen-containing ions to form an oxide layer on the top of the thin film material layer.
The patterning method of a film layer according to claim 1, wherein the plasma surface treatment is performed using nitrogen-containing ions to form a nitride layer on the top of the thin film material layer.
The patterning method of a film layer according to claim 1, characterized in that after removing the photoresist layer, a wet etching process and/or a dry etching process is used to etch the thin film material layer, so as to Remove the portion of the thin film material layer that is not covered with the passivation layer.
The patterning method of a film layer according to claim 1, wherein the material of the thin film material layer includes nickel.
The patterning method of a film layer according to claim 5, characterized in that after using a photoresist stripper to remove the photoresist layer, the photoresist stripper is continued to be used to erode the film material layer, so as to Remove the portion of the thin film material layer that is not covered with the passivation layer.
The patterning method of a film layer according to claim 1, wherein the film material layer is a metal material layer.
The patterning method of a film layer as claimed in claim 7, further comprising: a thermal annealing process after removing the portion of the film material layer that is not covered by the passivation layer.
The patterning method of a film layer according to claim 1, wherein the substrate includes a silicon substrate or a silicon carbide substrate.
A method for manufacturing a semiconductor device, characterized in that it includes the patterning method of a film layer according to any one of claims 1 to 9.