CN111880378A

CN111880378A - Method for improving electron beam direct writing exposure proximity effect

Info

Publication number: CN111880378A
Application number: CN202010614295.7A
Authority: CN
Inventors: 顾晓文; 郁鑫鑫; 周建军; 钱广
Original assignee: CETC 55 Research Institute
Current assignee: CETC 55 Research Institute
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2020-11-03

Abstract

The invention relates to a method for improving the proximity effect of electron beam direct writing exposure, which comprises the following steps: processing a designed initial layout, layering layout layers subjected to one-step direct writing exposure according to dose experience of electron beam exposure, wherein the columns with the same dose are a layer, each graph is divided into 3 layers, and adjacent graphs are divided into two groups of independent 3 layers; coating an adhesive, an electron beam photoresist and a conductive adhesive on a substrate material in sequence; adopting a layered layout to perform electron beam direct writing programming and performing direct writing exposure; and (3) preparing a mask pattern of the electron beam glue by developing to realize accurate processing of the pattern. The invention adopts a simple Boolean operation method to realize the layered processing of the layout, and adopts different doses to carry out the direct writing exposure of the electron beam, thereby realizing the accurate processing of the graph; a layer of conductive adhesive is added on the adhesive coating aiming at the electron beam process, so that the problem of poor conductivity of the substrate material is effectively solved, and the charge effect in the direct writing process is reduced.

Description

Method for improving electron beam direct writing exposure proximity effect

Technical Field

The invention belongs to the technical field of semiconductor nano processing, and particularly relates to a method for improving electron beam direct writing exposure proximity effect.

Background

The development of semiconductor and nano device technologies depends on the continuous progress of micro-nano processing technology to a great extent, and the microelectronic processing technology is promoted to a 7nm node at present. For the leading-edge innovation research field, the commonly adopted micro-nano processing technology is an electron beam exposure technology, and the pattern processing capacity of the micro-nano processing technology reaches the magnitude of 10 nanometers. The electron beam exposure does not need a mask plate, a processing graph with any shape can be designed through layout software, the use is convenient, the layout design and change are more flexible, and the iteration is quicker.

The greatest advantage of electron beam direct writing exposure is its highest resolution, and the most advanced electron beam lithography system can reach below 10 nm, and the electron beam direct writing technology is required in the mask plate manufacturing of the technical node above 0.18 micron. An important factor affecting the resolution of electron beam exposure is the proximity effect, which is an effect of exposing non-target areas of a pattern due to scattering of high-energy incident electrons in the electron beam resist and back scattering on the substrate, and which blurs the exposed pattern, especially when making fine patterns. The proximity effect can be divided into an inner proximity effect and a mutual proximity effect according to different generation principles and consequences, wherein the inner proximity effect is mainly expressed by the expansion of the edge of a large pattern to an outer region, and the mutual proximity effect is mainly expressed by the distortion deformation of patterns in a dense pattern region or a large pattern proximity region during exposure.

At present, a correction method is mainly adopted to solve the problem of figure distortion caused by proximity effect, one is a figure correction method, and a layout is reversely modified according to the figure deformation trend caused by the proximity effect; one is a GHOST method, which is used for carrying out low-dose exposure on a complementary graph on the basis of the original exposure, and the energy of the two exposures is superposed to realize energy distribution balance; still another approach is to use a monte carlo simulation technique to adjust the exposure dose for the entire pattern. The correction method generally requires correction software and has extremely high requirements on model parameters.

Disclosure of Invention

The invention aims to provide a method for improving the proximity effect of electron beam direct writing exposure, which solves the problem of overlarge proximity effect of electron beam exposure in processing of fine patterns, large-size patterns and the like, and overcomes the defect that complicated and expensive proximity effect correction is needed when the patterns are processed.

The technical solution for realizing the purpose of the invention is as follows: a method for improving proximity effect of electron beam direct write exposure, comprising the steps of:

1) processing a designed initial layout, layering layout layers subjected to one-step direct writing exposure according to dose experience of electron beam exposure, wherein the columns with the same dose are a layer, each graph is divided into 3 layers, and adjacent graphs are divided into two groups of independent 3 layers;

2) coating an adhesive, an electron beam photoresist and a conductive adhesive on a substrate material in sequence;

3) adopting a layered layout to perform electron beam direct writing programming and performing direct writing exposure;

4) and (3) preparing a mask pattern of the electron beam glue by developing to realize accurate processing of the pattern.

Compared with the prior art, the invention has the beneficial effects that:

1) the invention adopts a simple Boolean operation method to realize the layered processing of the layout, and adopts different doses to carry out the direct writing exposure of the electron beam, thereby realizing the accurate processing of the graph;

2) according to the invention, a layer of conductive adhesive is added on the adhesive coating aiming at the electron beam process, so that the problem of poor conductivity of the substrate material is effectively solved, and the charge effect in the direct writing process is reduced;

3) the invention provides a simple layout preprocessing and layered exposure method, which is suitable for accurately processing graphs and is suitable for various substrate materials including monocrystalline silicon, silicon on an insulator, indium phosphide, gallium arsenide, silicon-based thin film lithium niobate and the like.

Drawings

FIG. 1 is a schematic diagram of the layout hierarchy of the present invention.

Fig. 2 is a schematic view of the gluing of a backing material.

FIG. 3 is a schematic view of a high-precision pattern mask upon completion of fabrication.

Detailed Description

A method for improving proximity effect of electron beam direct write exposure, comprising the steps of:

1) processing a designed initial layout, layering layout layers of the same step of direct writing exposure according to dose experience of electron beam exposure, dividing each graph into 3 layers, and dividing adjacent graphs into two groups of independent 3 layers

Further, in the step 1), the layout layering is realized by a boolean operation method, and common layout drawing software, such as L-edge, Cadence and klayout, has a boolean operation function.

The line width of each group of 3 layers is gradual, the line width at the outermost side is the smallest, and the line width at the middle side is the largest and the line width at the innermost side is the largest.

Further, in the step 3), the 6 image layers are subjected to direct-write exposure at the same step, and are subjected to direct-write exposure sequentially, wherein the exposure doses are different, the exposure dose of the outermost image layer is the largest, and the dose of the innermost image layer is the smallest in the middle.

The technical scheme of the invention is further explained by combining the attached drawings and the embodiment

Examples

As shown in FIG. 1, a layout layering method for improving electron beam direct writing proximity effect is to divide an original pattern 1 into three layers with different line widths, and to divide adjacent patterns into two groups, 2, 3, 4, 5, 6, and 7, wherein the

layers

4 and 7 are outermost layers with a line width of 50-100 nm, the

layers

3 and 6 are middle layers with a line width of 100-200 nm, and the

layers

2 and 5 are layers with the largest line width.

The original layout layers can be graphs in various shapes, including rectangles, triangles, circles and the like, the graph 1 is only schematic, the six layers are exposed in the same step during electron beam exposure, the used doses are different, the larger the line width is, the smaller the dose is, and the

layers

2, 3, 4, 5, 6 and 7 are sequentially exposed in a direct writing exposure sequence.

The preparation process specifically comprises the following steps:

1) an adhesive, an electron beam resist, and a conductive paste are sequentially coated on the substrate material, as shown in fig. 2. The adhesive adopts HMDS or AR 300-80, the electron beam photoresist can adopt ZEP 520A, UV135, AR-P6200, PMMA, AR-N7520, HSQ and the like, and the conductive adhesive adopts AR-PC 5090 or AR-PC 5091;

2) adopting a layered layout to perform electron beam direct writing programming and performing direct writing exposure;

3) the mask pattern of the electron beam resist is prepared by using a developing technology, and the precise processing of the pattern is realized, as shown in fig. 3.

Claims

1. A method for improving proximity effect of electron beam direct write exposure, comprising the steps of:

2. The method according to claim 1, wherein the layer division is performed by boolean operation, and the line widths of each group of 3 layers are gradually increased, the outermost line width is the smallest, and the middle is the second innermost line width is the largest.

3. The method as claimed in claim 2, wherein the line width of the outermost layer is 50-100 nm, the line width of the middle layer is 100-200 nm, and the inner layer is the layer with the largest line width.

4. A method for improving proximity effect of electron beam direct write exposure according to claim 1, 2 or 3, wherein 6 layers of adjacent patterns are directly write exposed in the same step and sequentially in different exposure doses, the exposure dose of the outermost layer is the largest and the dose of the middle and innermost layer is the smallest.

5. The method of claim 1, wherein the adhesive is HMDS or AR 300-80.

6. The method for improving proximity effect of electron beam direct write exposure according to claim 1, wherein said electron beam resist is ZEP 520A, UV135, AR-P6200, PMMA, AR-N7520 or HSQ.

7. The method of claim 1, wherein the conductive paste is AR-PC 5090 or AR-PC 5091.