CN103293875A

CN103293875A - Photolithography device and light-transmitting unit adopting octupole exposure mode and photolithography method

Info

Publication number: CN103293875A
Application number: CN2013102110711A
Authority: CN
Inventors: 毛智彪
Original assignee: Shanghai Huali Microelectronics Corp
Current assignee: Shanghai Huali Integrated Circuit Manufacturing Co Ltd
Priority date: 2013-05-31
Filing date: 2013-05-31
Publication date: 2013-09-11
Anticipated expiration: 2033-05-31
Also published as: CN103293875B

Abstract

The invention relates to a photolithography device adopting an octapole exposure method, a light transmission unit and a photolithography method. The lithography device includes: a light source, a light-passing unit with at least one group of octopole light-transmitting holes, a light-condensing lens, a photomask and a projection lens, which are arranged in sequence from top to bottom. Wherein, at least one light-transmitting hole in the above-mentioned light-passing unit contains a plurality of gray-scale areas, and the gray-scale differences of the multiple gray-scale areas are transitional differences or jumping differences. The photomask with diffraction function and the projection lens focus the diffracted light on the silicon substrate located below it. The present invention significantly improves the comprehensive resolution and process window of photolithographic patterns of different sizes, especially in the case of octopole arrangement of photolithographic patterns, balances the line width of different sizes of photolithographic patterns, and avoids the occurrence of multiple exposures at the same time. The process cost increases and the output decreases.

Description

Adopt the lithographic equipment of ends of the earth Exposure mode, logical light unit and photoetching method

Technical field

The present invention relates to semiconductor microactuator electron device manufacturing equipment field, relate in particular to a kind of lithographic equipment of ends of the earth Exposure mode, logical light unit and photoetching method of adopting.

Background technology

Semiconductor devices is made and is adopted the photolithographic exposure mode to form required figure usually, and its basic step is as follows: at first, and resist coating on silicon chip, subsequently, high light is radiated on the silicon substrate by a mask version that is carved with circuit pattern, and the photoresist that is irradiated to part takes place rotten, use the corrosive liquids cleaning silicon chip afterwards, remove rotten photoresist, inscribe and photomask same circuits pattern photoresist figure at silicon substrate, last, through curing and operation such as development, form product wafer.

In the process of whole photolithographic exposure, the performance of lithographic equipment directly has influence on the yield rate of wafer.See also Fig. 1 and Fig. 2, Fig. 1 is for adopting off-axis (Off-Axis) the photolithographic exposure system schematic of the logical light Exposure mode in traditional ends of the earth, and Fig. 2 is the vertical view of logical light unit 12, the ends of the earth shown in Figure 1.As shown in the figure, incident ray 11 forms diffraction along necessarily departing from by logical light unit 12, the ends of the earth and collector lens 13 with axis at photomask 14 figure places, and 0 grade and+1 order diffraction light are interfered on silicon substrate 16 surfaces through projecting lens 15 backs and formed component graphics.Wherein, coefficient of coherence σ is an important parameter describing the circular iris size, the degree that its expression projecting lens is occupied by light source, the aperture of the aperture/projecting lens of σ=collector lens, coefficient of coherence σ _InAnd σ _Out, opening angle α and relative direction angle β are the important parameters of describing ends of the earth light hole size and width, σ _InTo σ _OutDistance is the light hole width, and α determines the light hole size, and relative direction angle beta, gamma and θ determine light hole to arrange.

Ends of the earth exposure is a particular example of off-axis exposure, compares general off-axis exposure, has bigger contrast, higher resolution and better process tolerance at the figure of little live width size.But continue the progress along with manufacturing process, the exposure of the simple ends of the earth gradually can not satisfy technology to resolution requirements, and the figure that can not guarantee different size has enough resolution, cause a part of figure to be rasterized, form so-called spatial separation (Forbidden Pitch) zone of forbidding.See also Fig. 3, Fig. 3 is the influence of the logical light cell size in the ends of the earth to different spaces spacing figure live width size, and wherein more close to zero, finished product accuracy is more high for critical size (Critical Dimension is called for short CD), and technology is more advanced.As shown in the figure, the curve that shows among the figure is about 150nm in spatial separation, and it is bigger to depart from zero point, and critical size error maximum causes some or several interval video picture difficulties.

See also Fig. 4, Fig. 4 is a kind of existing improvement technology synoptic diagram, and it adopts two pairs along the method for photolithographic exposure of the ends of the earth light hole of printing opacity unit center γ.This method has reduced the live width size than the fluctuation in the large space pitch area effectively by outer ends of the earth light hole of arranging in two pairs, has reduced forming the risk of forbidding the spatial separation zone.

Yet above-mentioned two pairs of ends of the earth light holes still lacking dirigibility aspect the live width size of the various figures of balance and the process window, are difficult to the figure of different size is reached the optimised process balance.In sum, how to reach the live width size of various figures and the optimised process balance of process window, not only need the ends of the earth light hole of suitable dimension, and the exposure that need be complementary with the live width size of various figures.This is the target of the required pursuit of present industry.

Summary of the invention

Fundamental purpose of the present invention is to overcome the defective of prior art, by comprising the ends of the earth light hole illumination gray difference balance exposure that many gray scales make up, makes ends of the earth light hole illumination bring into play multi-functionals such as best resolution enhancing and process window balance.

For reaching above-mentioned purpose, technical scheme of the present invention is as follows:

A kind of lithographic equipment that adopts ends of the earth Exposure mode comprises: light source, have the logical light unit, the ends of the earth in pair of light-transmissive hole at least, collector lens, photomask and projecting lens are arranged from top to bottom successively.Wherein, comprise a plurality of gray areas during at least one light hole in the above-mentioned logical light unit is interior, collector lens is assembled source light and by photomask, the projecting lens with diffraction function diffraction light is focused on the silicon substrate that is positioned at its underpart.

Preferably, logical iuuminting hole, light unit, the described ends of the earth is one group, and it is shaped as one of part circular ring type section, fan-shaped, circular, oval, polygon or their combination, and evenly arranges with logical light unit center.

Preferably, comprise the quantity of gray area in the light hole of logical light unit, the ends of the earth and be the zone of two or more different gray scales, the gray difference of a plurality of gray areas is transition type difference, or is great-jump-forward difference.

Preferably, the gray area in the light hole is shaped as one of strip, circle, ring-type or their combination.

Preferably, the gray area in the light hole is arranged along logical light unit center rotational symmetry.

Preferably, when light hole is circular or oval, gray area be circular, annular or when oval, and the interior gray area of light hole is coaxial with light hole.

Preferably, the outer ring partial coherence factor sigma of light hole in the logical light unit, the described ends of the earth _OutScope be 0.7～0.9; Inner round portion coefficient of coherence σ _InScope be 0.3～0.5.

Preferably, the scope of the opening angle α in logical iuuminting hole, light unit, the described ends of the earth is 15 °～40 °.

Preferably, described source light wavelength is 436 nanometers, 365 nanometers, 248 nanometers or 193 nanometers.

For reaching above-mentioned purpose, the invention provides a kind of device, technical scheme is as follows:

A kind of logical light unit with ends of the earth light hole; Logical light unit has one group of ends of the earth light hole of evenly arranging along logical light unit center at least; At least one light hole comprises a plurality of gray areas.

Preferably, comprise the quantity of gray area in the light hole of the ends of the earth and be the zone of two or more different gray scales, the gray difference of described a plurality of gray areas is transition type difference, or is great-jump-forward difference.

For reaching above-mentioned purpose, the present invention also provides a kind of photoetching method, specifically comprises the steps:

Step S1: according to the litho pattern demand of arranging, choose the outer ring partial coherence factor sigma of group number and definite ends of the earth light hole of ends of the earth light hole _Out, inner round portion coefficient of coherence σ _InWith opening angle α, relative direction angle beta, gamma and θ and light hole shape and orientation;

Step S2: choose gray areas quantity and the combination of arranging in the light hole according to the litho pattern size demand of arranging, to adjust the incident ray exposure;

Step S3: incident ray forms diffracted ray through the photomask diffraction after leading to light unit and collector lens by the ends of the earth;

Step S4: diffracted ray is again through forming final required litho pattern in the photoresist on surface of silicon behind the projecting lens;

Step S5: silicon substrate is cured and develops.

From technique scheme as can be seen, the lithographic equipment of employing provided by the invention ends of the earth Exposure mode, it is by installing logical light unit, the ends of the earth with variable many gray scales additional, remedy the exposure matching problem with many gray features, balance the exposure of live width size of various figures, and has a dirigibility of process window aspect, just can satisfy at single exposure variable live width size (the various figures that namely have different size and direction) is carried out reaching the optimised process balance in the photoetching process, thereby avoid because the manufacturing cost that adopts method for multiple exposures with multiple to cause increases and produces output descends.

Description of drawings

Fig. 1 is the off-axis photoetching exposure system synoptic diagram of available technology adopting ends of the earth Exposure mode

Fig. 2 is the logical light unit schematic top plan view of the off-axis photoetching exposure system of available technology adopting shown in Figure 1 ends of the earth Exposure mode

Fig. 3 organizes ends of the earth exposure to the influence curve of the photolithographic process capability of different spaces spacing figure live width size for adopting the list in the system shown in Figure 1

The logical light unit schematic top plan view of the off-axis photoetching exposure system of the ends of the earth light hole that Fig. 4 evenly arranges for the logical light unit center in two pairs of edges of available technology adopting

Fig. 5 has the synoptic diagram of lithographic equipment one preferred embodiment of ends of the earth Exposure mode for the present invention

Fig. 6,7 have logical light unit schematic top plan view among the lithographic equipment embodiment of ends of the earth Exposure mode for the present invention

Fig. 8 has the schematic top plan view of leading to the light unit in lithographic equipment one preferred embodiment of ends of the earth Exposure mode for the present invention

Fig. 9 has many gray scales ends of the earth Exposure mode to the influence curve of the photolithographic process capability of different spaces spacing figure live width size for adopting in the embodiment of the invention

Figure 10 is the schematic flow sheet of photoetching method one specific embodiment of the present invention

Embodiment

Some exemplary embodiments that embody feature of the present invention and advantage will be described in detail in the explanation of back segment.Be understood that the present invention can have various variations in different examples, its neither departing from the scope of the present invention, and explanation wherein and be shown in the usefulness that ought explain in essence, but not in order to limit the present invention.

Above-mentioned and other technical characterictic and beneficial effect are that structure and the photoetching method of the off-axis photoetching exposure system of lighting system is elaborated with reaching accompanying drawing 5-9 in conjunction with the embodiments to the ends of the earth of the present invention light hole.

Need to prove, the light source that adopts in the lithographic equipment of the employing ends of the earth Exposure mode in the embodiment of the invention can be arranged on any position of light path system, as long as it is just passable to satisfy off-axis photoetching exposure device needs, this source light wavelength is not done any restriction, preferably, can be 436 nanometers, 365 nanometers, 248 nanometers or 193 nanometers.

See also Fig. 5, Fig. 5 is the synoptic diagram of off-axis light engraving device one preferred embodiment of the ends of the earth of the present invention Exposure mode.As shown in the figure, this off-axis light engraving device comprises logical light unit 52 with ends of the earth light hole, is positioned at collector lens 53 under the logical light unit 52, is positioned at the photomask 54 under the collector lens 53 and is positioned at projecting lens 55 under the photomask 54.Collector lens 53 is used for assembling the source light 51 that passes described logical light unit 52 light holes, and photomask 54 is used for the light that diffraction passes collector lens 53, and projecting lens focuses on the silicon substrate 56 that is positioned at its underpart for the diffraction light that will pass photomask.

That is to say that incident ray 51 forms diffraction along necessarily departing from by logical light unit 52, the ends of the earth and collector lens 53 with axis at photomask 54 figure places, 0 grade and+1 order diffraction light are interfered on silicon substrate 56 surfaces through projecting lens 55 backs and are formed component graphics.

Generally, the light hole in the logical light unit 52, the ends of the earth can be selected one group for use according to the litho pattern situation of arranging, and also can be chosen as rent more.Many group light holes can be along logical light unit center symmetry, also can be asymmetric.In an embodiment of the present invention, comprise a plurality of gray areas during at least one light hole in the logical light unit 52, the ends of the earth is interior, the gray difference of these a plurality of gray areas is transition type difference, or is great-jump-forward difference.Wherein, the cross sectional shape of light hole is one of part circular ring type section, fan-shaped, circular, oval, polygon or their combination; Preferably, light hole is evenly arranged along the center of logical light unit 52.Preferable, light hole relative direction angle beta, gamma and θ are 45 °.

See also Fig. 6, Fig. 6 adopts the schematic top plan view under one group of light hole situation among the lithographic equipment embodiment of ends of the earth exposure system for the present invention.As shown in the figure, if light hole is one group, so, can comprise a plurality of gray areas at least one light hole, and the gray area shape that is positioned at light hole can have any shape, for example bar shaped, one of circular, ring-type or their combination.Preferably, if gray area is made up of many gray areas that are arranged in parallel, many gray areas that are arranged in parallel at the two poles of the earth can also lead to light unit center rotational symmetry in the edge, as

light hole

61,63, and 65 and 67 and 64 and 68.Its ends of the earth light hole is arranged and can be arranged for 45 ° of sub-multiple angles, as shown in Figure 6, but also other any directions.If gray area is by a plurality of annulars or circular the composition, the gray area in this light hole can be coaxial with light hole, as

light hole

64 and 68.

See also Fig. 7, Fig. 7 has the schematic top plan view under one group of light hole situation among the lithographic equipment embodiment of ends of the earth Exposure mode for the present invention.The present embodiment characteristics are that its ends of the earth distribution relative direction angle beta, gamma or θ are not 45 °, make its have specific folk prescription to, can be directions X, Y-direction, XY direction or any direction, the reinforcement exposure effect is arranged.In the application of reality, the outer ring coefficient of coherence 0.7～0.9 of light hole and inner ring coefficient of coherence 0.3～0.5 can satisfy most of litho pattern demands, certainly, under extreme case, σ _InCan be made as zero, namely become a last ends of the earth photolithographic exposure by off-axis ends of the earth photolithographic exposure, also be operable.In theory, the opening angle α of ends of the earth light hole can be 0 ° to 45 °, but in actual applications, opening angle α is 15 ° to 40 ° and is common example.

If comprise many group light holes in the logical light unit 52, the ends of the earth, can in one group of light hole gray area be set therein as required, also can in every group of light hole, gray area be set.Gray area number, shape and the arrangement mode etc. of every group of light hole can with above-mentioned one group of light hole embodiment in identical, do not repeat them here.

Particularly, see also Fig. 8, Fig. 8 adopts the schematic top plan view of leading to light unit (comprising two groups of ends of the earth light holes) in lithographic equipment one preferred embodiment of ends of the earth Exposure mode for the present invention.As shown in the figure, comprise two groups of light holes (light hole group 81 and light hole group 82) in the logical light unit 52, the ends of the earth.Wherein, comprise the gray area that increases progressively of continuous gray scale from inside to outside in the light hole group 81, light hole group 82 comprises four grayscale bar (grayscale bar 821 with logical light unit center symmetry, grayscale bar 822, grayscale bar 823 and grayscale bar 824), grayscale bar 821 is that gray-scale value is 0.6 grayscale bar, grayscale bar 822 is that gray-scale value is that 0 grayscale bar is complete light transmission strip, grayscale bar 823 is that gray-scale value is that 1.0 grayscale bar is non-light transmission strip, and grayscale bar 824 is grayscale bar of gray-scale value 0.3.

See also Fig. 9, Fig. 9 is for adopting the influence to the photolithographic process capability of different spaces spacing figure live width size that has many gray scales ends of the earth Exposure mode in the embodiment of the invention.From figure curve as can be seen, it is less that the curve that shows among the figure departs from zero point in spatial separation, critical size error curve more shown in Figure 3 is much smaller, it has guaranteed that the specific regional video picture in some or several intervals is normal.

In an embodiment of the present invention, lithographic equipment is by installing logical light unit, the ends of the earth with variable many gray scales additional, remedy the exposure matching problem with many gray features, balance the exposure of live width size of various figures, and has a dirigibility of process window aspect, can just can satisfy at single exposure variable live width size (the various figures that namely have different size and direction) is carried out reaching in the photoetching process optimised process balance, the exposure that many gray scales ends of the earth exposure can provide the live width size with various figures to be complementary.

Need to prove that the present invention has the logical light unit in the lithographic equipment of ends of the earth Exposure mode, can with lithographic equipment in the locus of parts such as lens, can change, its replacement scheme includes in the scope of the embodiment of the invention.

Below by Figure 10 the technology that the lithographic equipment that adopts the present invention to have ends of the earth Exposure mode carries out photoetching is elaborated.See also Figure 10, Figure 10 is the process chart of photoetching method one specific embodiment of the present invention, and above-mentioned photoetching process can comprise the steps:

Step S1: according to the litho pattern demand of arranging, choose the group number of ends of the earth light hole, determine the outer ring partial coherence factor sigma of ends of the earth light hole _OutWith inner round portion coefficient of coherence σ _In, opening angle α, relative direction angle beta, gamma and θ, light hole shape and orientation; Wherein, in this step, can carry out according to the photolithographic exposure needs aperture light transmission being arranged and carry out initial option.

Step S2: choose gray areas quantity and the combination of arranging in the light hole according to the litho pattern size demand of arranging, and adjust the incident ray exposure; Wherein, in this step, can determine gray areas quantity and the combination of arranging in the light hole of the ends of the earth according to the some or several specific zones in the litho pattern, namely photolithographic exposure is needed the zone of lay special stress on or compensation, carry out the fine setting to the incident ray exposure.

Step S3: incident ray forms diffracted ray by after leading to light unit and collector lens through the photomask diffraction;

Step S5: silicon substrate is cured and develops.

Wherein, incident ray can be positioned at direct projection directly over the silicon substrate among the step S2, also can be positioned at other positions, direct projection, reflection or refraction.And in actual applications, the source light wavelength of litho machine is 436 nanometers, 365 nanometers, 248 nanometers or 193 nanometers.

Above-described only is embodiments of the invention; described embodiment is not in order to limit scope of patent protection of the present invention; therefore the equivalent structure done of every utilization instructions of the present invention and accompanying drawing content changes, and in like manner all should be included in protection scope of the present invention.

Claims

1. A photolithographic apparatus adopting an octapole exposure method, comprising:

light source;

A light-transmitting unit having at least one group of octopole light-transmitting holes;

A condensing lens, located under the light-passing unit, used to gather light from the light source passing through the light-passing hole in the light-passing unit;

a photomask, located under the condensing lens, for diffracting light passing through the condensing lens;

a projection lens, located under the photomask, for focusing the diffracted light passing through the photomask on the silicon substrate below it;

It is characterized in that at least one light transmission hole in the light transmission unit contains at least a plurality of gray scale areas, and the gray scale differences of the multiple gray scale areas are transitional differences or jumping differences.

2. The lithographic apparatus according to claim 1, wherein the shape of the light transmission hole is a partial circular segment, sector, circle, ellipse, polygon or one of their combinations, and is compatible with the The centers of the light-passing units are evenly arranged.

3. The photolithographic apparatus according to claim 1 or 2, wherein the shape of the gray-scale area in the light transmission hole is one of strip shape, circle shape, ring shape, or a combination thereof.

4 . The photolithographic apparatus according to claim 3 , wherein the gray scale areas in the light transmission hole are symmetrically arranged along the central axis of the light transmission unit.

5. The lithography apparatus according to claim 1, wherein the light transmission hole is circular or elliptical, the gray-scale area is circular, circular or elliptical, and the light transmission hole is The gray scale area is coaxial with the light transmission hole.

6. The lithography apparatus according to claim 1, wherein the coherence coefficient _σout of the outer circle of the light transmission hole is in the range of 0.7 to 0.9; the coherence coefficient σin of the inner circle of the light transmission hole _is The range is 0.3 ~ 0.5.

7 . The photolithography apparatus according to claim 1 , wherein the opening angle α of the light transmission hole ranges from 15° to 40°.

8 . The photolithography apparatus according to claim 1 , wherein the wavelength of light from the light source is 436 nanometers, 365 nanometers, 248 nanometers, or 193 nanometers.

9. A light-passing unit adopting an eight-pole exposure mode, characterized in that, in the described eight-pole light-passing unit, there is at least one set of eight-pole light-passing holes uniformly arranged along the center of the light-passing unit; The at least one light transmission hole at least includes a plurality of gray scale areas; the gray scale differences of the multiple gray scale areas are transitional differences, or jumping differences.

10. A photolithography method adopting the device according to claim 1, is characterized in that, specifically comprises the steps:

Step S1: Select the number of groups of the octopole light-transmitting holes according to the layout requirements of the lithography pattern, and determine the arrangement direction of the light-transmitting holes, the coherence coefficient σ _{out of} the outer ring part, and the coherence coefficient σ _in the inner ring part of the opening Angle α, relative direction angle β, γ and θ and the shape of the light-transmitting hole;

Step S2: Selecting the number and arrangement combination of the gray-scale areas in the light-transmitting hole according to the size and arrangement requirements of the lithography pattern, so as to adjust the exposure amount of the incident light;

Step S3: After the incident light passes through the light passing unit and the condenser lens, it is diffracted by the photomask to form diffracted light;

Step S4: the diffracted light passes through the projection lens to form a final required photolithographic pattern in the photoresist on the surface of the silicon substrate;

Step S5: Baking and developing the silicon substrate.