CN115639730A - Electron beam lithography method, shallow trench isolation and method for forming electrode contact holes - Google Patents

Abstract

The invention relates to an electron beam photolithography method, a shallow trench isolation and a method for forming an electrode contact hole. The electron beam photolithography method comprises the following steps: coating electron beam glue on a substrate; forming an aluminum film on the electron beam glue; exposing the electron beam glue to electron beam; finally developing. The shallow trench isolation and electrode contact holes are formed by using the above method. The invention solves the problem of poor exposure effect caused by electron accumulation on the substrate surface.

Description

Electron beam lithography method, shallow trench isolation and method for forming electrode contact holes

technical field

The invention relates to the field of semiconductor manufacturing technology, in particular to an electron beam lithography method, a shallow trench isolation and a method for forming an electrode contact hole.

Background technique

Electron beam lithography (EBL) is the practice of scanning a focused beam of electrons to draw custom shapes on a surface covered by an electron-sensitive film called resist (exposure), also known as e-beam glue. The e-beam changes the solubility of the e-beam glue, and by immersing it in a solvent (developing), it is possible to selectively remove exposed or unexposed areas of the resist. During the electron beam exposure process, the electrons that hit the electron beam glue 2 on the substrate 1 need to be exported in time. If the substrate 1 is a non-conductive substrate, it will cause electrons to accumulate on the substrate surface (the accumulated electrons are shown in Figure 1 Shown), forming a potential, which will eventually prevent subsequent electron injection and affect the effect of electron beam exposure.

For this reason, the present invention is proposed.

Contents of the invention

The main purpose of the present invention is to provide an electron beam lithography method and its application in shallow trench isolation and electrode contact hole formation, which solves the problem of poor exposure effect caused by the accumulation of electrons on the substrate surface.

In order to achieve the above objectives, the present invention provides the following technical solutions.

A first aspect of the present invention provides an electron beam lithography method comprising the steps of:

Coating electron beam glue on the substrate;

forming an aluminum film on the electron beam glue;

Carrying out electron beam exposure to the electron beam glue;

Develop last.

Further, the thickness of the aluminum film reaches

Further, the thickness of the aluminum film reaches

Further, the aluminum film is formed by sputtering at 20-35°C.

Further, TMAH is used for the development.

Further, the substrate is a silicon substrate, a silicon carbide substrate, a silicon-on-insulator substrate, a germanium substrate or a germanium-on-insulator substrate.

Further, the ratio of the thickness of the electron beam glue to the thickness of the aluminum film is 3:1.

Further, before forming the aluminum film, the method further includes: firstly forming a hard mask layer on the electron beam glue.

The second aspect of the present invention provides a method for forming shallow trench isolation, which uses the above-mentioned electron beam lithography method to form shallow trench isolation on a semiconductor carrier.

A third aspect of the present invention provides a method for forming an electrode contact hole, which uses the above-mentioned electron beam lithography method to form the electrode contact hole.

Compared with the prior art, the present invention has achieved the following technical effects:

(1) Deposit a thin layer of aluminum film on the surface of the electron beam glue, which can prevent the properties of the electron beam glue from changing during the sputtering process, play a conductive role, and also allow most of the electrons to pass through the aluminum film during the exposure process. Electron beam glue, which makes the electron beam glue photosensitive; at the same time, aluminum can be absorbed by the developing solution together with the electron beam glue during the development process, eliminating the subsequent removal process.

(2) The aluminum film is sputtered at room temperature, and the thickness is controlled to a certain extent, which can further improve the effect of focusing the electron beam on the electron beam glue and improve the exposure effect.

(3) A hard mask layer can also be formed before the electron beam glue is formed, which can be used in processes such as multiple photolithography.

(4) The electron beam lithography method of the present invention can be used to form arbitrary patterns in semiconductor fabrication such as shallow trench isolation or electrode contact holes.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiment. The drawings are only for the purpose of illustrating a preferred embodiment and are not to be considered as limiting the invention.

1 is a schematic diagram of electron accumulation during electron beam exposure in the prior art;

Fig. 2 is the flowchart of electron beam lithography method provided by the present invention;

Reference signs:

1-substrate, 2-electron beam glue.

Detailed ways

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be understood, however, that these descriptions are exemplary only, and are not intended to limit the scope of the present disclosure. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the present disclosure.

Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. The figures are not drawn to scale, with certain details exaggerated and possibly omitted for clarity of presentation. The shapes of the various regions and layers shown in the figure, as well as their relative sizes and positional relationships are only exemplary, and may deviate due to manufacturing tolerances or technical limitations in practice, and those skilled in the art will Regions/layers with different shapes, sizes, and relative positions can be additionally designed as needed.

In the context of the present disclosure, when a layer/element is referred to as being "on" another layer/element, the layer/element may be directly on the other layer/element, or there may be intervening layers/elements in between. element. Additionally, if a layer/element is "on" another layer/element in one orientation, the layer/element can be located "below" the other layer/element when the orientation is reversed.

Electrons are waves with extremely short wavelengths, and the precision of electron beam exposure can reach the nanometer level, but the application on non-conductive substrates has the problem of poor exposure effect due to the accumulation of electrons on the surface.

The present invention finds that a thin aluminum film is formed on the surface of the electron beam glue before exposure, which can solve the above problems.

Specifically, in the process shown in FIG. 2 , electron beam glue is firstly coated on the substrate to be etched with a pattern. Electron beam glue can use positive electron beam photoresist or negative electron beam photoresist, polymethyl methacrylate, poly α-trifluoroethyl chloroacrylate, polybutylene sulfone, polyhydrogen silsesquisil Oxygen and other materials. The substrate of the present invention is not limited to a wafer, and may be a semiconductor carrier without a photoelectric structure, such as a silicon substrate, a silicon carbide substrate, a silicon-on-insulator substrate, a germanium substrate, a germanium-on-insulator substrate, a silicon-germanium substrate bottom, etc., or the carrier of the photoelectric structure is fabricated on the above substrate.

Next, an aluminum film is formed on the electron beam glue. The aluminum film can prevent the properties of the electron beam glue from being changed during the sputtering process and play a conductive role. It can also allow most of the electrons to pass through the aluminum film to reach the electron beam glue during the exposure process, making the electron beam glue photosensitive. In this step, by controlling the formation conditions and thickness of the aluminum film, the exposure effect can be improved to a greater extent, and the accumulation of electrons on the substrate surface can be reduced or eliminated.

左右，例如

范围内的任意厚度，

等，更优选

此处的常温指20～35℃。In some embodiments, the aluminum film is preferably formed by sputtering at room temperature, and the thickness is controlled at

left and right, for example

Any thickness within the range,

etc., more preferably

The normal temperature here means 20-35 degreeC.

In some embodiments, the ratio of the thickness of the electron beam glue to the thickness of the aluminum film is 3:1.

Afterwards, electron beam exposure can be performed on the electron beam glue, and the electron beam can pass through the aluminum film to reach the electron beam glue. At the same time, due to the conductivity of the aluminum film, electrons will not accumulate on the surface, so that the electron beam glue can be better exposed. The exposure path or pattern of the electron beam in this step depends on the pattern to be etched. For example, the method of the present invention can be used to form shallow trench isolation, form electrode contact holes, and divide gate stack layers.

Finally, developing is carried out, and the developer is preferably TMAH developer, which has good solubility to the aluminum film and the exposed or unexposed electron beam glue, so it can be removed together, eliminating the need for subsequent removal steps.

In the photolithography method described above, a hard mask layer may also be formed on the electron beam glue before forming the aluminum film. The hard mask layer is mainly used in the multiple photolithography process. First, the multiple photoresist images are transferred to the hard mask, and then the final pattern is etched and transferred to the substrate through the hard mask. TiN, SiN, SiO can be used ₂ and other materials.

The embodiments of the present disclosure have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the present disclosure, and these substitutions and modifications should all fall within the scope of the present disclosure.

Claims (9)

1. An electron beam lithography method, is characterized in that, comprises the following steps: Coating electron beam glue on the substrate; forming an aluminum film on the electron beam glue; Carrying out electron beam exposure to the electron beam glue; Develop last. 2. The electron beam lithography method according to claim 1, wherein the thickness of the aluminum film reaches

3. The electron beam lithography method according to claim 2, wherein the thickness of the aluminum film reaches

4. The electron beam lithography method according to any one of claims 1-3, characterized in that the aluminum film is formed by sputtering at a temperature of 20-35°C. 5. The electron beam lithography method according to claim 1, wherein said developing is performed using TMAH. 6 . The electron beam lithography method according to claim 1 , wherein the substrate is a silicon substrate, a silicon carbide substrate, a silicon-on-insulator substrate, a germanium substrate or a germanium-on-insulator substrate. 7. The electron beam lithography method according to claim 1, further comprising: forming a hard mask layer on the electron beam glue before forming the aluminum film. 8. A method for forming shallow trench isolation, characterized in that the shallow trench isolation is formed on a semiconductor carrier by using the electron beam lithography method according to any one of claims 1-7. 9. A method for forming an electrode contact hole, characterized in that the electrode contact hole is formed by using the electron beam lithography method according to any one of claims 1-7.

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