A kind of multiplayer films in EUV and preparation method thereof
Technical field
The present invention relates to multiplayer films in EUV fields, more particularly to multiplayer films in EUV with infrared spectroscopy function is set
Meter and preparation.
Background technique
In recent years, extreme ultraviolet photolithographic (EUV Lithograph, EUVL) technology is widely developed.EUVL is used
13.5nm wavelength light source can be realized the lithographic line width of more than ten nanometers or even several nanometers as service band, and then greatly increase
The integrated level for adding integrated circuit develops miniaturization, the low-power consumption of electronic equipment and is extremely important.
Extreme ultraviolet photolithographic equipment is generally made of EUV light source, lighting system and projection objective.Wherein, EUV light source
Extreme ultraviolet radiation needed for providing photolithographic exposure.It is to realize extreme ultraviolet with high-power and high-purity spectrum EUV light source
The precondition of photoetching volume production, and one of the difficult point of extreme ultraviolet lithography at present.
Currently, extreme ultraviolet radiation can be generated by synchrotron radiation and high-temperature high-density plasma radiation.In Practical Project
In, the EUV light source based on high-temperature high-density plasma radiation more has practical value.According to the difference excitation of plasma
Principle, EUV light source can be divided into discharge plasma (Discharge Produced Plasma, DPP) light source and laser again
Plasma (Laser Produced Plasma, LPP) light source two types.The former is excited using interelectrode electrion
Plasma, but since plasma distance electrode is closer, thermal damage inevitably is generated to electrode and fragment is hit, limit
The application of DPP light source is made.The latter excites plasma using driving laser bombardment target, can be realized high-power, stable
Extreme ultraviolet output, in recent years by extensive research and application.LPP light source applied to extreme ultraviolet lithography is generally by driving
Light source, target system and collection system are constituted.Wherein, driving light source generally selects the gas laser that can be realized high-power output
Device, such as CO2 laser;Target system is made of target and target transmission mechanism, and common target has Sn droplet target, Xe gas
Target etc.;Collection system is the extreme ultraviolet light beam collecting plasma resonance and going out, and is converged to intermediate focus
The device of (Intermediate Focus, IF) generally collects mirror using the ellipsoid for being coated with extreme ultraviolet reflectance coating to realize
This function.Meanwhile in order to reduce damage of the fragment to lighting system in extreme ultraviolet photolithographic equipment, the spectroscopic pure of emergent light is improved
Degree, can also be arranged in LPP light source and remove fragment system and spectrum purification system etc..In LPP light source, mirror is collected through ellipsoid and is collected
Light include extreme ultraviolet, deep ultraviolet light (Deep Ultraviolet, DUV) and from driving light source infrared light
(Infrared, IR).Wherein, the fuel factor that infrared light generates can cause the face deformation of reflecting mirror in optical system, greatly
Image quality is influenced, meanwhile, thermal damage caused by infrared light also will be greatly shortened the service life of system.In this regard, researcher
Propose a variety of solutions.
2009, a kind of multiplayer films in EUV structure for covering balzed grating, of Dutch FOM lab design can be realized
The light splitting of infrared light and extreme ultraviolet, and then realize the purifying of light source light spectrum.
Summary of the invention
The present invention is directed to overcome the defect of existing technology, in order to not influence MoSi multilayer film to service band (13.5nm)
The reflectivity of infrared band is reduced while reflectivity, the present invention provides a kind of extreme ultraviolet multilayers with infrared spectroscopy function
Film.
To achieve the above object, the invention adopts the following technical scheme:
On the one hand, the present invention provides a kind of multiplayer films in EUV, wherein the multilayer film successively includes: substrate, multiple
Si/Mo layer, zigzag array structure layer and the infrared reflecting layer in period.The invention proposes introduce in MoSi multilayer film upper surface
Zigzag array structure layer can effectively realize the light splitting of infrared light and extreme ultraviolet, and then realize the light of EUV light source
Spectrum purifying.EUV is different from reflectance mechanism of the IR on multilayer film, and EUV reflection is based on the folded of periodic multilayer membrane interface reflection
Add effect, IR reflection is the high reflectance based on metal (such as Mo) to IR wave band.When there are one layers and multilayer film for multi-layer film surface
When the not parallel infrared reflecting layer in interface, EUV will be reflected according to multilayer membrane interface, and IR will be reflected according to infrared reflecting layer.For example,
When infrared reflecting layer and multilayer membrane interface are there are when the angle of a degree (0 < a < 90), for the EUV and IR of equidirectional incidence, instead
2a degree will be separated by penetrating light.In addition, constituting structure sheaf using Si material, absorption of the surface structure to EUV can also be reduced.As a result,
The invention proposes zigzag array structure layer is introduced in MoSi multilayer film upper surface, the spectrum purifying of EUV light source is realized.
Yet another aspect, the present invention also provides a kind of preparation methods of multiplayer films in EUV, comprising steps of S1, preparation
Substrate;S2, the Si/Mo layer for preparing multiple periods on the substrate;S3, zigzag array junctions are prepared on the Si/Mo layer
Structure layer;S4, infrared reflecting layer is deposited on the zigzag array structure layer.
The beneficial effects of the present invention are: multiplayer films in EUV provided by the present invention can effectively realize infrared light and
The light splitting of extreme ultraviolet, and then realize the spectrum purifying of EUV light source.Moreover, multiplayer films in EUV knot provided by the present invention
Influence of the structure to the reflectivity of operation wavelength is smaller.
Detailed description of the invention
Fig. 1 is the structural schematic diagram according to the multiplayer films in EUV of one embodiment of the invention.
Fig. 2 is the structural schematic diagram according to the class triangular array of the multiplayer films in EUV of one embodiment of the invention.
Fig. 3 is the reflectivity according to the embodiment of the present invention 1-7 and the multiplayer films in EUV of comparative example 1 in extreme ultraviolet waveband
Schematic diagram.
Fig. 4 is the reflection according to the embodiment of the present invention 1-7 and the multiplayer films in EUV of comparative example 1 to 10.6 μm of infrared lights
The schematic diagram of rate.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, below in conjunction with attached drawing and specific implementation
Example, the present invention will be described in further detail.It should be appreciated that specific embodiment described herein is only to explain this hair
It is bright, but not to limit the present invention.
On the one hand, as shown in attached drawing 1 of the present invention, multiplayer films in EUV provided by the present invention successively includes substrate 1, multiple
The Si/Mo layer 2 in period, zigzag array structure layer 3 and infrared reflecting layer 4.Si/ of the reflection of extreme ultraviolet based on multiple periods
2 interface of Mo layer, and basic principle of the reflection of infrared light based on infrared reflecting layer 4.When infrared reflecting layer 4 and multiple periods
Si/Mo layer 2 can realize the light splitting of infrared light and extreme ultraviolet there are when angle.So the invention proposes in multiple periods
The layer upper surface Si/Mo introduce zigzag array structure layer, the light splitting of infrared light and extreme ultraviolet can be effectively realized, in turn
Realize the spectrum purifying of EUV light source;Moreover, reflection of the multiplayer films in EUV structure provided by the present invention to operation wavelength
The influence of rate is smaller.Point of Si and Mo out-of-order in Si/Mo layers of the present invention, can be Si/Mo layers or Mo/Si layers, two
Kind material is alternately stacked.Preferably, the surface of Si/Mo layer multi-layer film of the present invention is Mo, prepares sawtooth on it later
Shape array structure layer.
In some embodiments, the substrate is one of silicon wafer, fused quartz, devitrified glass, super-low expansion quartz glass
Or it is a variety of.Wherein, super-low expansion quartz glass, ULE (ultra-low expansion), i.e. ultra-low thermal expansion glass.
In some embodiments, the multilayer film has the Si/Mo layer in 40-50 period.In above-mentioned technical proposal, the week
Phase property multilayer film is the periodic multilayer film for having two kinds of materials of Mo and Si to constitute.Specifically, each period Si/Mo layers of thickness can
It is determined by operation wavelength and operating angle, preferably 6.5nm-7.3nm, further preferably 7nm.Described Si/Mo layers can be by magnetic
The film plating process such as control sputtering or the sputtering of ion beamlet are realized.
In some embodiments, the Si/Mo layer in each period with a thickness of 6.5nm-7.3nm, and the Si/ in each period
The thickness of Mo material described in Mo layers accounts for the 35%-45% of the Si/Mo thickness degree, further, the thickness of the Mo material
40% or so of Si/Mo layers of periodic thickness is accounted for, i.e. γ value is 0.4 or so.
In some embodiments, the zigzag array structure layer can be class triangular array structure and/or waveform battle array
Array structure.Fig. 1 shows the structure of the class triangular array of the multiplayer films in EUV in one embodiment according to the present invention.
In some embodiments, the zigzag array structure layer is zigzag oldered array structure or zigzag disordered array
Structure.
In some embodiments, the zigzag oldered array structure is by photoetching, glancing angle deposition technology, nano impression or gold
Hard rock cutting process is realized.Wherein, the oldered array structure can also be realized by glancing angle deposition technology, but need to assist other
Technology, such as pre- glove.
In some embodiments, the zigzag disordered array structure by photoetching, glancing angle deposition technology, nano impression or
Diamond cutting cutting method is realized.
In some embodiments, the zigzag array structure layer is made of Si material, the zigzag array structure layer with
The angle at Si/Mo layers of the inclination angle is 10 ° -80 °, and the height of the zigzag array structure layer is 45nm-55nm.Into
One step, the thickness of the zigzag array structure layer is with a thickness of 50nm.The zigzag array structure layer is at Si/Mo layers
Surface forms the inclined-plane array with uniform tilt angle, so that multiplayer films in EUV of the invention can be realized infrared light
It is purified with the spectrum of the light splitting of extreme ultraviolet, and then realization EUV light source, and multiplayer films in EUV structure is to operation wavelength
Reflectivity influence it is smaller.Zigzag array structure layer described above and the angular range at Si/Mo layers of the inclination angle are not
Only being able to satisfy can open infrared light with EUV points in certain distance, and easy to operate.Zigzag array structure layer described above
If thickness thickness more than 55nm, it is excessive to will lead to EUV absorption loss;If being less than 45nm, microstructure unit density is big,
Spectrophotometric result is relatively weak.Under thickness certain condition, inclination angle is larger, then zigzag cellular construction is too small, and distribution density is big, adds
Work relative difficulty, and the reflectivity of EUV is influenced big;Inclination angle is excessive, and incident light is almost glancing incidence, or even negative incidence occurs
Angle, infrared reflectivity reduce.
In some embodiments, the infrared reflecting layer is made of one of Mo, Ru, Ti or Zr or a variety of, and described outer
Red reflex layer with a thickness of 4.5nm-5.5nm.Preferably, the infrared reflecting layer is made of Mo.Periodic multilayer film is to realize
The basis of EUV reflection, but there is stronger reflection to infrared light simultaneously, pass through the zigzag array structure layer micro-structure energy on surface
Enough realize that EUV is different from infrared reflection direction.If using Ru as infrared reflecting layer, multiplayer films in EUV provided by the invention
Also there is certain oxidation resistance.
On the other hand, the present invention also provides a kind of preparation methods of multiplayer films in EUV, comprising steps of S1, preparation base
Bottom;S2, the Si/Mo layer for preparing multiple periods on the substrate using magnetron sputtering method;S3, it is prepared on Si/Mo layers described
Zigzag array structure layer;S4, infrared reflecting layer is deposited on the zigzag array structure layer using magnetron sputtering method.
Specifically, in one embodiment, the preparation method of multiplayer films in EUV of the present invention may include step, step
1, prepare fused quartz substrate 1, roughness 0.2nm;Step 2 prepares 40 period Mo/Si layers 2, period 7nm, γ using magnetron sputtering
Value 0.4;Step 3, using glancing angle deposition technology, in multi-layer film surface deposition there is the Si nano wire at 30 ° of inclinations angle to form class
Triangular array structure 3, as shown in Figure 2;Step 4 deposits Mo metal using magnetron sputtering in class triangular array structure 3
Layer, thickness 5nm.
In some embodiments, the step S3 includes the silicon nanowires shape that deposition has inclination angle on the Si/Mo layer
At zigzag array structure layer.The specific range at above-mentioned inclination angle is related with specific deposition operation, for example, selection glancing angle deposition
When method is deposited, the inclination angle is then related with the glancing angle used when glancing angle deposition, further specifically, the step
S3 may include that there is graze deposition the silicon nanowires at 30 ° of inclinations angle to form zigzag array structure layer on the Si/Mo layer.
In some embodiments, the zigzag array structure layer can be class triangular array structure and/or waveform battle array
The angle at array structure, the zigzag array structure layer and Si/Mo layers of the inclination angle is 10 ° -80 °, and the zigzag
The thickness of array structure layer is with a thickness of 45nm-55nm.
In some embodiments, the zigzag array structure layer is zigzag oldered array structure or zigzag disordered array
Structure, the zigzag oldered array structure are realized that the zigzag is unordered by photoetching, nano impression or diamond cutting cutting method
Array structure is realized by photoetching, glancing angle deposition technology, nano impression or diamond cutting cutting method.
In some embodiments, the substrate be one of silicon wafer, fused quartz, devitrified glass, super-low expansion quartz glass,
The substrate with a thickness of 100mm-300mm, and the step S1 further includes by the surface of the substrate by design
Processing.To guarantee that the face shape of reflecting mirror does not change, the thickness of the substrate is preferably 100mm-300mm;Or the substrate
It can be designed as plane mirror, substrate thickness is selected in 10mm or so, the specific thickness of substrate in combination with actual application environment.
According to some embodiments of the present invention, it is preferable that the substrate surface high frequency roughness is less than 0.2nm, can be thrown by machinery
The methods of light, ion beam polishing or magnetic fluid polishing are realized.
Embodiment 1-7
Multiplayer films in EUV with infrared spectroscopy function successively includes substrate 1, the Si/Mo in multiple periods from bottom to up
Layer 2, zigzag array structure layer 3 and infrared reflecting layer 4.The material and thickness that embodiment 1-7 is used are as shown in table 1.
Comparative example 1
A kind of multilayer film comprising substrate, multicycle SiMo layer, the substrate select fused quartz, roughness 0.2nm;Institute
The Si/Mo layer for stating multiple periods was 50 periods, and periodic thickness 7nm, γ value is 0.4, the surface layer of the Si/Mo layer in multiple period
For Si.
Table 1 is the material and thickness in the multiplayer films in EUV of embodiment 1-7.
Table 1
Table 2 is the calculated result of embodiment 1-7 and comparative example 1.
Table 2
Above with respect to the convention in the calculation basis test of extreme ultraviolet reflectivity, using 6 ° of incidence angles, i.e., incident light with
Multilayer film interface normal angular separation is 6 °.Spectrophotometric result described in table 2 refers to the angle that infrared light and extreme ultraviolet separate.To reality
The calculated result of a 1-7 and comparative example 1 is applied as shown in table 2, Fig. 3-4.
By the visible laciniation layer height of embodiment 1-3, in 50nm, multiplayer films in EUV designed by the present invention has
There is higher reflectivity.Increase with laciniation layer height, multilayer film decays to the reflectivity of extreme ultraviolet in oscillatory type, works as saw
When the height of dentalation layer is 50nm, multilayer film of the present invention is relatively high to the reflectivity of extreme ultraviolet.For thinner
Laciniation layer, multilayer film can increased the reflectivity of extreme ultraviolet, but due to the requirement at inclination angle, laciniation layer
Distribution density increases, and also will increase to processing bring difficulty.
It being had a significant effect by the inclination angle of embodiment 1,4 visible laciniation layers to spectrophotometric result, inclination angle is too small,
Spectrophotometric result is relatively weak;Inclination angle is excessive, and reflecting effect is relatively weak, but infrared spectroscopy effect can be achieved.
Embodiment 1,6,7 as it can be seen that infrared reflecting layer thickness on the functional influence of multilayer film, excessively thin infrared reflecting layer pair
Infrared reflectivity is lower, and blocked up infrared reflecting layer is lower to ultraviolet reflectivity.
Spectral absorption layer (or spectral absorption layer structure) is introduced on periodical MoSi multilayer film, can reduce multilayer film pair
The reflection of deep ultraviolet light improves the photoresist exposure problems as caused by deep ultraviolet light.The present invention is in periodical MoSi multilayer film
The upper structure sheaf that introduces realizes the function of infrared spectroscopy.It is learnt according to embodiment result, triangular array structure is to infrared light
Reflection has specific direction, and the light splitting energy of structure can be illustrated by the spacing of infrared light at fixed range and extreme ultraviolet
Power.Multiplayer films in EUV provided by the present invention can effectively realize the light splitting of infrared light and extreme ultraviolet, and then realize pole
The spectrum of ultraviolet source purifies.Moreover, shadow of the multiplayer films in EUV structure provided by the present invention to the reflectivity of operation wavelength
Sound is smaller.And multiplayer films in EUV provided by comparative example 1 does not have infrared spectroscopy effect.
The above described specific embodiments of the present invention are not intended to limit the scope of the present invention..Any basis
Any other various changes and modifications made by technical concept of the invention should be included in the guarantor of the claims in the present invention
It protects in range.
In the description of this specification, reference term " one embodiment ", " some embodiments ", " example ", " specifically show
The description of example " or " some examples " etc. means specific features, structure, material or spy described in conjunction with this embodiment or example
Point is included at least one embodiment or example of the invention.In the present specification, schematic expression of the above terms are not
Centainly refer to identical embodiment or example.Moreover, particular features, structures, materials, or characteristics described can be any
One or more embodiment or examples in can be combined in any suitable manner.
Although the embodiments of the present invention has been shown and described above, it is to be understood that above-described embodiment is example
Property, it is not considered as limiting the invention, those skilled in the art are not departing from the principle of the present invention and objective
In the case where can make changes, modifications, alterations, and variations to the above described embodiments within the scope of the invention.