CN105242500A - Photoetching system based on ultraviolet broad-spectrum Talbot self-imaging - Google Patents

Abstract

The invention relates to a photoetching system based on ultraviolet broad-spectrum Talbot self-imaging. Based on the optical Talbot effect self-imaging principle, when non-monochromatic ultraviolet light is adopted for illuminating a periodic mask, self-imaging light fields of different spectrums and different levels are mutually staggered and incoherently stacked, and a continuous imageable area is formed at the position a certain distance away from the lower portion of the mask. Compared with a self-imaging photoetching system adopting single-wavelength illumination, the imageable area for ultraviolet broad-spectrum self-imaging can be expanded to the scale of millimeters and even centimeters; self-imaging light field distribution and phase-shifting self-imaging light field distribution with approximately equal intensity can be obtained when a silicon wafer is placed at any position of the continuous imageable area, so that periodic frequency multiplication is obtained, and the resolving ability of a manufactured periodic micro-nano structure is improved; meanwhile, no complex optical lens system is needed when the periodic micro-nano structure is manufactured based on the principle, so that the manufacturing cost is greatly lowered.

Description

A kind of based on the etching system of ultraviolet wide spectral Taibo from imaging

Technical field

The invention belongs to microelectronic device and micro processing field, be specifically related to a kind of based on the etching system of ultraviolet wide spectral Taibo from imaging, for improving the resolution of fabrication cycle micro-nano structure, reducing cost of manufacture.

Background technology

21 century is not only epoch of information explosion, is also that the mankind are constantly to the material time node of Exploring Substructure of Matter.Micro-nano structure is as important " bridge " that connect the mankind and microworld, and its technology of preparing also progressively develops into the heat subject of current scientific and technological circle research.European and American developed countries and Japan are novel in research, the micro-nano structure technology of preparing of high-resolution live width, having high output ratio has dropped into a large amount of financial resource and material resource, and achieve the achievement in research attracted people's attention, and walk the prostatitis in the world.

Meanwhile, along with the production technology constantly progress that commercial measurement, Aero-Space, display lighting, biologic medical etc. are closely bound up with national development, with grating, array of orifices etc. for representative periodically micro-nano structure to have at multiple key areas and apply very widely, the market demand is huge.On the other hand, because development in science and technology is maked rapid progress, people are also increasingly harsh to the requirement of periodic micro/nano structure, need that it meets large area, high precision simultaneously, pattern is complicated, manufacturing cycle is short, yields high condition.

Principle at present for fabrication cycle micro-nano structure has: (1) is close to & contact photolithography method.For making the micro-nano structure of lower accuracy, principle is simple, and technical threshold is low, cost is lower, but by the restriction of equipment, masking process, most rests on a millimeter magnitude close to & contact photolithography resolution, can not adapt to the development of future technology.(2) nano-imprint method.As a kind of emerging micro-nano technology means, advantage is to realize large area, high-precision periodic micro/nano structure makes.But the manufacture difficulty of high precision impression block is high, some problems are comparatively seriously waited to have to be solved by template restriction.(3) interference light lithography.The most typical technological means of present stage manufacturing cycle micro-nano structure the most, can realize large area, mask, the processing of high precision micro-nano graph.On the other hand, for different lithographic pattern structures, interference lithography needs to carry out accurate adjustment to optical interference circuit, operates more difficult control; And interference lithography can graphics processing single, dirigibility is poor, is not suitable for processing and has the periodic micro/nano structure of complex pattern.

Since the self-imaging of micro-nano structure is found, the research preparing high precision periodic micro/nano structure based on this principle just starts development.But most from imaging and photo-etching principle, be all based on proximity lithography method, and utilize the fixed light field distribution of periodic structure mask, realize by the gap accurately controlled between substrate and mask the processing that large area sends out periodic micro/nano structure assorted.These class methods can be referred to as " positioning exposure type is from imaging photolithography ", and the feature of its self-imaging is, square being directly proportional of depth of focus and micro-nano structure cycle, therefore when the figure cycle to be exposed reduces, its depth of focus has shortening.Simultaneously, for ensureing exposure figure quality, the method has strict demand to flatness of substrate, photoresist thickness etc., and needs to carry out nanoscale control to the absolute interstitial between mask and substrate, in actual micro-nano preparation process, extremely difficult realization, is difficult to really be applied.

Existing from all deficiency of imaging and photo-etching from imaging means in order to overcome, invention describes a kind of based on the photoetching method of ultraviolet wide spectral Taibo from image-forming principle, can effectively reduce from the requirement of imaging photolithography to silicon chip pattern and positioning precision.

Summary of the invention

The present invention proposes a kind of based on the etching system of ultraviolet wide spectral Taibo from image-forming principle, can effectively reduce from the requirement of imaging photolithography to silicon chip pattern and positioning precision.

The technical solution used in the present invention is: a kind of based on the etching system of ultraviolet wide spectral Taibo from imaging, this etching system is made up of light source, beam collimation extender lens, mask plate and silicon chip; Produced the ultraviolet light of certain spectrum width by light source, be irradiated on mask plate through beam collimation extender lens, the Taibo that mask plate rear is formed from imaging light field region, Taibo be divided into from imaging light field region mask plate from imaging and phase shift from imaging region; Due to employing is broad spectrum light source, therefore at Taibo in imaging region, the Taibo that can form very long distance from imaging region, to the requirement of silicon chip pattern and precise positioning when greatly reducing photolithographic exposure, and achieve cycle frequency multiplication, improve the resolution of fabrication cycle type micro-nano structure.

Wherein, this etching system course of work is: when wide spectral ultraviolet lighting is mapped to mask plate, according to Taibo from imaging principle formula: d is the cycle, and λ is different, can be formed different Taibo image distances from, thus widened Taibo from imaging region; When silicon chip being placed in the optional position in region, all can obtain intensity approximately equalised from imaging and phase shift from imaging optical field distribution, thus performance period frequency multiplication, improve the resolution of imaging.

Wherein, this etching system uses high-pressure sodium lamp light source, and spectrum comprises: ultraviolet light, visible ray and infrared spectrum, and by repeatedly filtering, remaining ultraviolet spectrum, by light beam collimation lens realization to the even light of spectrum and collimating effect.

The present invention's advantage is compared with prior art:

(1), ultraviolet wide spectral of the present invention, can be produced by mercury lamp, compared to other from the photolithographic light source of imaging, be easier to obtain, and low price.

(2), the present invention can work close under photolithographicallpatterned, can realize large area micro-nano photoetching, have good Technological adaptability.

(3), the present invention adopts wide spectral lighting system, and can greatly expand can patterned area, i.e. overlength depth of focus.

(4), the present invention adopts fixed exposure mode, simplifies experiment mechanism, to record from imaging and phase shift from imaging simultaneously, realize the cycle frequency multiplication relative to mask.

(5), intensity control of the present invention is simple, effectively can reduce half, and resolving power can reach or close to diffraction limit.

Accompanying drawing explanation

Fig. 1 is of the present invention a kind of based on the structure principle chart of ultraviolet wide spectral Taibo from the etching system of imaging.

Fig. 2 is the curve of spectrum adopting light source during the present invention tests.

Fig. 3 is the Taibo that records during the present invention the tests spectrum information from imaging light field, and as can be seen from the figure, this principle can realize the cycle frequency multiplication of photoengraving pattern, thus improves photolithography resolution.

Embodiment

In order to understand technical scheme of the present invention better, be described in further detail below in conjunction with accompanying drawing.

The present invention is a kind of based on the etching system of ultraviolet wide spectral Taibo from imaging, and as shown in Figure 1, this system is made up of light source 1, beam collimation extender lens 2, mask plate 3 and silicon chip 6 principle.Produced the ultraviolet light of certain spectrum width by light source 1, be irradiated on mask plate 3 through beam collimation extender lens 2, the Taibo that mask plate rear is formed is from imaging light field region.Now, silicon chip is placed in the continuous imageable areas of this light field, in this region, all can obtain intensity approximately equalised from imaging 4 and phase shift from imaging 5 optical field distribution, thus performance period frequency multiplication.

According to Taibo from imaging theory, the complex amplitude transmitance for One Dimension Periodic object can be expressed as:

$t\left(x_0\right)=\underset{-\mathrm{\∞}}{\overset{\mathrm{\∞}}{\Σ}}{C}_n\exp \left(\frac{i2{\mathrm{\πnx}}_0}{d}\right)$

Wherein, d is the cycle, and n is integer, C _nfor Fourier series, x ₀for lateral coordinates, its spatial frequency spectrum is:

$T\left(f\right)=\underset{-\mathrm{\∞}}{\overset{\mathrm{\∞}}{\Σ}}{C}_n\mathrm{\δ}(f_x-\frac{n}{d})$

Wherein, f _xfor spatial frequency.

In fresnel diffraction, system transter is:

H(f _x)＝exp(-iπλzf _x ²)exp(-ikz)

Wherein, z is image space distance.

Frequency spectrum sightingpiston obtaining optical field distribution is:

$T^{\′}\left(f_x\right)=\underset{-\mathrm{\∞}}{\overset{\mathrm{\∞}}{\Σ}}{C}_n\mathrm{\δ}(f_x-\frac{n}{d})\exp (-i\mathrm{\π}\mathrm{\λ}z\frac{n^2}{d^2})\exp (-ikz)$

Obviously, when when N is integer, above formula can be expressed as,

$T^{\′}\left(f_x\right)=\underset{-\mathrm{\∞}}{\overset{\mathrm{\∞}}{\Σ}}{C}_n\mathrm{\δ}(f_x-\frac{n}{d})\exp (-ikz)$

Namely diffraction intensity distribution is identical with object | t'(x ₀) | ²=| t (x ₀) | ², that is exist distance on, the picture of object can be observed, just be called talbot distance.Talbot distance is relevant with wavelength X, therefore, and the light talbot distance that correspondence is different when imaging of different wave length.

When utilizing ultraviolet broad spectrum light source illumination period mask, different spectrum, secondary, coherence stack interlaced from imaging optical field distribution not at the same level, below mask, certain rear forms continuous imageable areas.Compared to Single wavelength illumination from imaging optical field distribution, the imageable areas of ultraviolet wide spectral imaging can be expanded to several millimeters, even centimetres, when silicon chip being placed in the optional position of continuous imageable areas, all can obtain intensity approximately equalised from imaging and phase shift from imaging optical field distribution, thus frequency multiplication performance period (as Fig. 3), improve the resolution of photoetching.

Generally, of the present invention based on the etching system of ultraviolet wide spectral Taibo from imaging, have good Technological adaptability, cost low, large area micro-nano photoetching can be realized and there is higher photolithography resolution, the requirement of high-level efficiency, high precision fabrication cycle type micro-nano structure can be met.The new application that the present invention does not elaborate belongs to the known technology of art of the present invention.

Claims (3)

1. one kind based on the etching system of ultraviolet wide spectral Taibo from imaging, it is characterized in that: this etching system is by light source (1), beam collimation extender lens (2), mask plate (3) and silicon chip (6) composition, the ultraviolet light of certain spectrum width is produced by light source (1), be irradiated on mask plate (3) through beam collimation extender lens (2), mask plate rear forms Taibo from imaging light field region, Taibo be divided into from imaging light field region mask plate from imaging (4) and phase shift from imaging region (5), due to employing is broad spectrum light source, therefore at Taibo in imaging region, the Taibo of very long distance can be formed from imaging region, to the requirement of silicon chip pattern and precise positioning when greatly reducing photolithographic exposure, and achieve cycle frequency multiplication, improve the resolution of fabrication cycle type micro-nano structure.

2. according to claim 1 based on ultraviolet wide spectral Taibo from the etching system of imaging, it is characterized in that: in this etching system course of work, when wide spectral ultraviolet lighting is mapped to mask plate, according to Taibo from imaging principle formula: d is the cycle, and λ is different, can be formed different Taibo image distances from, thus widened Taibo from imaging region; When silicon chip being placed in the optional position in region, all can obtain intensity approximately equalised from imaging and phase shift from imaging optical field distribution, thus performance period frequency multiplication, improve the resolution of imaging.

3. according to claim 1 based on the etching system of ultraviolet wide spectral Taibo from imaging, it is characterized in that: this etching system uses high-pressure sodium lamp light source, spectrum comprises: ultraviolet light, visible ray and infrared spectrum, by repeatedly filtering, remaining ultraviolet spectrum, by light beam collimation lens realization to the even light of spectrum and collimating effect.