DE10131534B4 - Method for producing a mask for exposure - Google Patents

Abstract

A method for producing a mask for exposing a resist layer (10) of a semiconductor substrate to radiation, comprising the steps of:
Providing a material region (20a) for the mask (20) to be formed,
- structuring of the material region (20a) for the mask to be formed (20) and thereby
Forming the mask (20) with a desired structure,
- wherein the material region (20a) for the mask to be formed is structured by applying a structuring radiation field (50), thereby generating a distribution of optical properties of the material region (20a) for the mask (20) to be formed, by which the desired structure of the mask is produced .
Wherein the structuring radiation field (50) is produced by superposing at least two structuring individual radiation fields (50-1, 50-2) in a region of the material region (20a) for the mask (20) to be formed,
- Wherein radiation of Strukturierungsstrahlungsfeldes (50) electromagnetic radiation at a wavelength in the range of 160 nm to 10 nm is used, and
- where as material area ...

Description

The The invention relates to a method for producing a mask for Expose.

at the use of radiation fields for applying and exposing certain room areas or material areas often become like this used masks or mask areas. By the used Mask areas become a desired structure for the exposure radiation field imprinted and the room area to be acted upon or exposed or Material area supplied.

application find such concepts especially in manufacturing processes of semiconductor structures. There are certain substrates with radiation sensitive Materials covered, in turn, as a protective or etching mask should serve and in the context of a photolithographic process have to be pre-structured wherein corresponding mask areas or masks for the exposure of radiation-sensitive materials are used.

Frequently the mask areas or masks to be used are complex, so that their material realization, for example, under a Deposition process, consuming and costly. Furthermore, due to the desired Increased integration density in semiconductor technologies increased Radiation in the range of short wavelengths to the train to a higher spatial resolution to achieve in the formation of the semiconductor structures in the substrate. Especially in the short-wave range, especially in the extreme or EUV range, are masks or mask areas not simple Way inexpensive to create.

The publication DE 43 17 081 A1 describes a liquid crystalline medium on which a radiation field acts to represent certain images. A production method for a mask for exposing a resist layer of a semiconductor substrate to radiation is neither explicitly shown nor indirectly excited here.

In the DE 35 24 176 A1 discloses a method for producing a light mask, which light mask can also be used for the exposure of photosensitive layers in the manufacture of semiconductor devices. In the method described, electromagnetic radiation or particle radiation in the form of electron radiation or ion radiation is applied to a photoresist layer. This is explained in particular in steps 2 and 3 of the illustrated lithographic process. With regard to the applied radiation field, in the description of method steps 2 and 3 no special feature is mentioned.

The EP 718 691 A2 shows a method of forming photomasks. In this case, a mask template is provided with a masking layer. By ion bombardment with ion radiation irradiated areas are then formed in the mask template, resulting in modified areas. The radiation itself is described exclusively as ion radiation, whereby here too no composition of the total radiation field is important.

The publication US 5,105,215 A describes exclusively a method for the controlled exposure of a photoresist layer by means of a liquid crystal system. The preparation of an irradiation mask or exposure mask is neither shown nor stimulated.

The WO 02/06899 A2 relates to a system and a method for characterization optical systems using holographic masks. Besides are manufacturing processes for corresponding masks are described. In particular, there is an indication that two or more beams of optical radiation for training an interference volume, e.g. in a photoresist, to be used. there the geometry of the holographic mask to be generated is decisive defined by the geometry of the interference pattern.

Of the Invention is based on the object, a production process Specify through which mask areas particularly flexible and reliable realized are.

The Task is in a method for producing a mask according to the invention with the features of claim 1. Advantageous developments are the subject of the dependent subclaims.

A method is proposed for producing a mask for exposing a resist layer of a semiconductor substrate to radiation, with the steps of providing a material region 20a for the mask to be formed, structuring the material region for the mask to be formed and thereby forming the mask with a desired structure, wherein the material region for the mask to be formed is structured by applying a structuring radiation field and thereby producing a distribution of optical properties of the material region for the mask to be formed, by which the desired structure of the mask is generated, wherein the patterning radiation field is formed by superimposing at least two patterning individual radiation fields in a Be is used as the radiation of the patterning radiation field electromagnetic radiation at a wavelength in the range of 160 nm to 10 nm and wherein as the material region for the mask, a radiation refractive / -reflective crystal with or from one or more materials from the group formed by LiNbO ₃ , BaTiO ₃ , Bi ₁₂ SiO ₂₀ , BSO, Fe: LiNbO ₃ , Sr _x Ba _1-x Nb ₂ O ₆ , SBN, BGO, BTO, Ce: BaTiO ₃ , Rh: BaTiO ₃ , KNSBN, compounds, combinations and dopings thereof.

It is thus in the inventive method for making a mask area, etc. provided a material area to apply a structuring radiation field. By the Interaction of the structuring radiation field with the material of the material area for the mask area becomes optical properties in their spatial and / or temporal distribution in the area of the material accordingly a planned and desired Structure of the mask area adapted or generated. This leads to, that by a modulation of the optical parameters of the material area the mask structure is generated and represented. Instead of a direct material representation the mask, for example, on the surface of a structuring Substrate or the like can be obtained by a variation of the corresponding Structuring radiation field in an easy way the internal Structure of the modulation or distribution of the optical parameters changed the material of the mask area and adapted and thus a variable mask structure are generated. It can work to be remanent, partially remanent or temporary parameter modulations.

It is basically conceivable that by an appropriate optical process one off generates a structuring radiation field existing radiation field and the material region of the mask region to be formed is supplied. Particularly simple and flexible, the design of the corresponding structuring radiation field with regard to a desired structure of the mask area when generating a plurality of patterning individual radiation fields which is then superposed to form the structuring radiation field become. It may in particular be a superposition of at least two structuring individual radiation fields in the area of the material area for the Apprenticeship mask area will be thought.

It can basically any form of interaction between radiation and matter in the structuring of the material area for the mask area to be formed by application and / or exposure to the patterning radiation field be thought. It is specifically intended that as radiation or as radiation for structuring, in particular as the structuring radiation field and / or the structuring individual radiation fields particle radiation and / or electromagnetic radiation. In the Electromagnetic radiation may be radiation in particular in the visible range or in the UV range act. In particular, it is at the extreme ultraviolet range or EUV range, preferably a wavelength range is covered by about 160 nm to 10 nm. Especially in the last mentioned Area are material representations for mask areas only with very big Effort and not produced with sufficient reliability.

at For example, the particle radiation may be thought of electron beams become.

Of Furthermore, it is advantageous that as radiation and / or as radiation for structuring, in particular for structuring individual radiation fields, Radiations of the same type, energy, wavelength and / or The same is used, in particular identical radiations preferably coherent Radiation or laser radiation. These measures will be appropriate Interaction mechanisms between the individual radiation fields predictable and usefully applicable to the trainee mask area accordingly to be able to structure.

The optical properties of the material area, which the trainees Mask area is based on the applicable particle radiation and / or on electromagnetic radiation Respectively. It is thought of parameters such as the dielectric constant, the optical density, the spectral absorbance and / or like. These sizes will be spatially and / or by applying to the structuring radiation field in time, that is possibly temporarily, set and modulated.

In the simplest case, for example, a grating in materially deposited form with material lines and recesses provided therebetween would have its correspondence according to the invention in a material region for the mask region, which likewise has a line, for example regions with increased or reduced dielectric constants. In general, however, it can also be thought to form the desired structure of the mask area in less direct form, that is, in deviation from the principle of a shadow, for example, a structure of the distribution of the optical parameters, the structure for a ent speaking exposure radiation field generated when using the mask area only under fulfillment of a so-called Bragg condition.

Even though in principle all matter interacts with corresponding structuring radiation fields, it is preferred that a radiation-refractive especially photorefractive / -reflective, material is used. These materials have the property of interacting with them the structuring radiation field their local refractive index or change their reflectivity. So is then governed by the structure of the patterning radiation field in the material area for the mask region generates a corresponding structure for the refractive index or for the reflectivity. On this structure, which formed in the material area for the mask area is, then in the sense of a diffraction grating or the like an interaction with another radiation field, namely a Exposure radiation field, when using the mask area done.

Of the so-called photorefractive effect is based on that, in particular in certain crystals, through interaction with an external electromagnetic Field refractive index inhomogeneities in spatial Distribution in the material area for arise the mask area, which in particular by appropriate Structuring the Strukturierungsstrahlungsfeldes a so-called Form phase hologram or volume hologram. This effect can be especially when using two coherent light beams or light wave fields in a photorefractive crystal brings to overlay. Then arises namely an interference pattern, ie a spatial distribution of places higher and low intensity the electromagnetic fields. In the places of high intensity are going through Photoionization or the like charge carrier - optionally as electrons or holes - released. The each increased or decreased carrier density can by diffusion processes and / or by recombination at least be partly compensated again. The recombination arises in particular at impurities, for example, particles of dopants or impurities. It forms a corresponding charge carrier redistribution. These Ladungsträgerneuverteilung or redistribution usually has at least local electrical Field result. Accordingly, then arises due to the charge distribution modulation the electric field locally proportional refractive index change, So a refractive index modulation. By an appropriate choice the structuring radiation field, the formation of a corresponding Volumenholo gramms be enforced, the structure of the volume hologram just wanted Mask structure realized. The volume hologram thus forms a Kind of holographic grid.

requirement is but that the acted upon with the Strukturierungsstrahlungsfeld material area for the Mask area substantially volume-like and not purely layered is trained. The material area must therefore have a certain layer thickness have, so an extension in the propagation direction of each applied radiation field. In the interaction of an intended Exposure radiation field with the formed volume hologram, So with the mask area with appropriate structure, then due to the interaction, a so-called Bragg condition, if necessary Fulfills, so that the volume hologram thus provided the structure of the Mask area only by certain exposure radiation fields with corresponding properties and reconstructed to a corresponding can be formed to be structured material area.

For the material region of the mask region, a material comprising LiNbO ₃ , BaTiO ₃ , Bi ₁₂ SiO ₂₀ or BSO, Fe: LiNbO ₃ , Sr _x Ba _(1-x) Nb ₂ O ₆ or SBN, BGO, BTO, Ce is preferably used BaTiO ₃ , Rh: BaTiO ₃ , KNSBN and / or the like, and / or compounds, combinations, dopings thereof or consists thereof.

Of the Physical state of the material area for the mask area is always fixed liquid, gel-like or as gas selectable, as long as it is ensured that the respective material area in the application and then fixed in a fixed spatial area is why, in particular solid, preferably crystals, to offer.

Preferably the patterning radiation field is due to interference from at least generates two individual structuring radiation fields.

Further it is provided that the structuring radiation field and / or the structuring individual radiation fields by their generation and / or pre-structured by optical imaging or further processing become. This is necessary, for example, because the desired structure of the mask area to be formed by properties of the structuring radiation field represented in any form must become. Ultimately, this is a structuring of the structuring radiation field forming structuring individual radiation fields necessary.

In a particularly advantageous embodiment of the method according to the invention, it is provided that at least one volu by supplying the structuring radiation field hologram is generated in the material area for the mask area. Advantageously, several and possibly different volume holograms can also be formed in the material region for the mask region, so that a selection of different volume holograms in terms of differently structured mask regions can be selected on the basis of variously provided Bragg conditions.

Preferably is used to form the structuring radiation field and in particular for forming the patterning single radiation in substantially coherent Form used, preferably laser radiation.

At the Mask area, especially for a method for applying and / or exposing to radiation, a material area is provided, which has an intended spatial and / or temporal distribution of optical properties, which in turn has a specific and / or desired structure of the mask area corresponds and / or represents.

Of the Mask area is characterized in that the material area for the Mask area a radiation-refractive / -reflective, especially photorefractive / -reflective, Comprises or consists of material.

Especially it is a mask area, according to the inventive method or an embodiment is made thereof.

From It is particularly advantageous if the material area for the mask area, a crystal, a polymer and / or the like or consists thereof.

In an advantageous embodiment of the mask region, it is provided that the material region contains or consists of a material which comprises LiNbO ₃ , BaTiO ₃ , Bi ₁₂ SiO ₂₀ or BSO, Fe: LiNbO ₃ , Sr _x Ba _(1-x) Nb ₂ O ₆ or SBN, BGO, BTO, Ce: BaTiO ₃ , Rh: BaTiO ₃ , KNSBN and / or the like, and / or compounds, combinations, dopings thereof or consists thereof.

According to one further advantageous embodiment of the mask area, it is provided that optical properties with respect to particle radiation and / or electromagnetic radiation, in particular the dielectric constant, the optical density or the like, optionally locally and / or temporary are formed set.

at a further preferred embodiment of the mask area, it is provided that in the material area at least a volume hologram or the like is provided, through which the distribution of optical properties, in particular the dielectric constant, is trained.

As has already been explained above, there is another particular aspect of the present invention to apply the conceptions mentioned above, in methods and devices for applying and / or exposing with radiation during structuring of corresponding material areas.

at a method for applying and / or exposing a material area or Resistmaterialbereich or the like, it is provided that first a mask area is formed or provided, in particular in essentially direct spatial Neighborhood to the material area or resist material area to be exposed. The material region or resist material region is exposed to an exposure radiation field This will be an image of the structure of the mask area or the mask area itself in an area of the material area or resist material area formed.

It is provided that a material area of a radiation-refractive / -reflective, especially photorefractive / -reflective, material is used. Although the method is for applying and exposing with an exposure radiation field on material areas of low composition conceivable, however, a special aspect lies in the application of inventive conception in methods for applying and / or exposing resist material areas. It is therefore preferred that as to be acted upon and / or to exposing material area a region of a resist material, a photosensitive material area and / or the like is used becomes.

preferably, In the method, the mask area is before and / or during the Loading and / or exposure with the exposure radiation field structured, in particular the method according to the invention for creating a mask area.

According to one another preferred embodiment of the method, it is provided that a mask area is used as the mask area is used in the form described above.

In another preferred embodiment of the method, it is provided that particle radiation and / or electromagnetic radiation is used as radiation or as radiation for impinging and / or exposing the resist / material region to the exposure radiation field. The latter arises in particular the sichtba ren range, the UV range, preferably the extreme UV or EUV range and / or preferably at a wavelength of about 160 nm to 10 nm.

at another advantageous embodiment of the method, it is provided that as radiation and / or as Radiation for applying and / or exposing the resist / material area with the exposure radiation field and for applying and / or exposing of the mask area with the structuring radiation field radiations thereof Type and the same energy, wavelength and / or the like used be, in particular identical radiation, in particular substantially coherent Radiation, preferably laser radiation.

The Exposing the resist / material area can be done in several ways and ways using the mask area.

From It is particularly advantageous that the exposure of the resist / material area with the exposure radiation field is carried out by substantially transmitting in the mask area by irradiating the mask area with the Exposure radiation field from a resist / material area opposite side of the mask area forth. This essentially corresponds a kind of transmitted light method in which the structure of the mask area is geometric optically by Schattenwurf or wave optically by diffraction at the diffraction grating given by the structure of the mask area.

on the other hand it is advantageously provided that the exposure of the Resist / material area with the exposure radiation field is made by essentially reflecting on the mask area by means of irradiation of the mask area with the exposure radiation field of one Resist- / Materialbereich facing side of the mask area ago.

at the device for applying and / or exposing a resist / material region, in particular to carry out of the method according to the invention, has a mask area, which is a structured, and / or to be structured radiation-refractive / -reflective, especially photorefractive / -reflective Material comprises or is formed from it.

at a particularly preferred embodiment The device is currently provided an inventive mask area.

These and further aspects of the present invention are described below Remarks further explained.

For the evaluation of resist materials so-called gray wedge profiles are investigated, especially preferred exposure parameters during the application and / or exposing the resist materials to an exposure radiation field to find. The structuring process for such gray scale profiles as mask areas is very expensive. Statements about the Suitability of a corresponding resist system can only be out of that using grayscale profiles or mask areas read off generated structures. There is for the development of resist materials the recourse to a corre sponding exposure methodology with corresponding mask areas very important for creating the structures.

For the wavelength range in the EUV, however, there are no readily available mask areas or masks to disposal. By the present invention, this problem is defused by that an easily realizable method for generating masks, in particular for the EUV area.

traditionally, is the manipulation of the beam path in short-wave photons on a so-called Schwarzschild optics realized, which in particular elaborately reflective Mirror systems includes. At even shorter wavelengths, namely in Range of X-ray quanta find Fresnel zone plates application, which after a likewise complex Production process serve as a diffraction grating masks.

Fresnel Zone plates are produced electron lithographically. For the EUV sector (13 nm) between the 157 nm and the hard X-ray quanta represents the present Invention an easy to implement method for displaying an EUV mask before.

in the Be the area of optical data transmission Methods used to interfere in crystals through a dual-laser system to generate, which switch the beam path of a third laser can. The basic physical phenomenon is that in the places of interference in the crystal itself there locally the dielectric constant changes, whereby the switching laser waveform can be manipulated. In the overlay two flat waves creates a grating, on which an incoming third plane wavefront in the direction of the interference secondary maxima is bent as a plane wave. This is a switching between zeroth and first diffraction order.

The simplest way of imaging, by imaging a point, is possible only with a shadow mask, where the hole diameter must be in the range of the wavelength to a spherical wave which gives a Fresnel zone plate as an interference pattern when this spherical wave interferes with the reference beam of the second laser. From the plane incident wave of the first laser results after passing through a pinhole a spherical wave according to Huygen's principle, which results in superposition with the plane wave (reference wave), an annular phase grating system as an interference pattern.

The Refractive index variation in the crystal, so the resulting spatial Phase grating, is sinusoidal modulated, thereby ensuring that is disturbing Secondary maxima higher Order be suppressed. The induced Fresnel zone grid serves as imaging optics.

One The fundamental aspect of the present invention is therefore to that the use of a double laser system is a modulation of the Refractive index can be generated, the crystal used for the wavelength in principle is transparent and where the refractive index variation is sufficient, the exposure wavefront of the exposure radiation field such to bow, that under the figure at the mask area the corresponding desired Transfer structure to the resist / material area.

following the invention with reference to a schematic drawing on the Basis of preferred embodiments explained in more detail.

1A C show various intermediate states which, according to a preferred embodiment of the method according to the invention, are achieved when producing a mask region according to the invention.

2 shows a schematic sectional side view of a first embodiment of a device for exposure.

3 shows another preferred embodiment of a device for exposure.

In the 1A to 1D is a schematic and perspective view of a process sequence for an embodiment of the mask region manufacturing method of the present invention 20 explained by four different intermediate stages.

In the in 1A shown first intermediate step is first a material area 20a provided to the trainee mask area 20 underlying.

According to the 1B becomes the material area 20a then with a structuring radiation field 50 applied. This structuring radiation field 50 arises from superposition of two individual structuring radiation fields 50-1 and 50-2 at the location of the material area 20a , According to 1B This may be the structuring single radiation fields 50-1 and 50-2 For example, it involves two intersecting laser beams.

Due to the forming interference pattern by superposition of the two individual structuring radiation fields 50-1 . 50-2 becomes the material area 20a for the trainee mask area 20 with regard to the distribution of the values of certain optical parameters, for example the dielectric constant, modulated in such a way that different first regions 21 and second areas 22 in the material area 20a for the mask area 20 arise, and thus a structured mask area 20 is trained, like that in the 1C and 1D is shown.

The 2 and 3 show a schematic and sectional side view of the application of in 1D shown and completed mask area 20 in a device 1 for exposing.

In the embodiment of the 2 it is a so-called exposure in transmission. In immediate spatial proximity to a resist / material area to be structured 10 is an embodiment of a mask region according to the invention 20 arranged, which with first areas 21 and second areas 22 is structured for different values of certain optical parameters. The mask area 20 owns a resist / material area 20 facing side 25b and a side facing away from this 25a , On the of the resist / materials area 10 opposite side 25a of the mask area 20 is an exposure radiation source 40 provided by which a primary exposure radiation field 30 towards the mask area 20 emitted. By interaction of the primary exposure radiation field 30 with the different first and second areas 21 and 22 of the mask area 20 becomes a secondary exposure radiation field in transmission 30 ' generated and to the the resist / material area 10 facing side 25b delivered. The secondary exposure radiation field 30 ' reaches the resist / material area 10 and creates first areas there 11 and second areas 12 different radiation intensities.

In the embodiment of the 3 is worked in reflection instead of transmission. The exposure radiation source 40 in turn generates a primary exposure radiation field 30 , but this time the exposure radiation source 40 and the resist / material area 10 on the same, the Re SiSt / material area 10 facing side 25b of the mask area 20 are arranged such that only of this the resist / material area 10 facing side 25b Reflected or reflected portions of the primary exposure radiation field 30 the resist / material area 10 as a secondary exposure radiation field 30 ' to reach.

1

contraption for exposing

10

Resist / material area

11

first exposure range

12

second exposure range

20

Mask, mask area

20a

material area for the mask area

21

first Area

22

second Area

25a

facing away page

25b

facing page

30

Exposure radiation field, primary Exposure radiation field

30 '

secondary exposure radiation field

40

Exposure radiation source

50

Patterning radiation field

50-1

Structuring individual radiation field

50-2

Structuring individual radiation field

Claims (7)

Method for producing a mask for exposing a resist layer ( 10 ) of a semiconductor substrate with radiation, comprising the steps of: - providing a material region ( 20a ) for the trainee mask ( 20 ), - structuring the material area ( 20a ) for the trainee mask ( 20 ) and thereby - forming the mask ( 20 ) with a desired structure, - wherein the material region ( 20a ) for the mask to be formed by applying a patterning radiation field ( 50 ) and thereby distributes optical properties of the material region ( 20a ) for the trainee mask ( 20 ) is generated, by which the desired structure of the mask is generated, - wherein the structuring radiation field ( 50 ) by superposing at least two individual structuring radiation fields ( 50-1 . 50-2 ) in a region of the material region ( 20a ) for the trainee mask ( 20 ) is generated, - where as radiation of the structuring radiation field ( 50 ) electromagnetic radiation at a wavelength in the range of 160 nm to 10 nm is used and - being used as material area ( 20a ) for the mask ( 20 ) a radiation-refractive / -reflective crystal is used with or from one or more materials from the group formed by LiNbO ₃ , BaTiO ₃ , Bi ₁₂ SiO ₂₀ , BSO, Fe: LiNbO ₃ , Sr _x Ba _(1-x) Nb ₂ O ₆ , SBN, BGO, BTO, Ce: BaTiO ₃ , Rh: BaTiO ₃ , KNSBN, compounds, combinations and dopings thereof. Method according to claim 1, characterized in that as radiation for the structuring individual radiation fields ( 50-1 . 50-2 ) Radiations of the same type, the same energy, the same wavelength and / or identical radiations can be used. Method according to one of the preceding claims, characterized in that the local dielectric constant by the application of the structuring radiation field ( 50 ) is set. Method according to one of the preceding claims, characterized in that the patterning radiation field ( 50 ) by interference of the at least two structuring individual radiation fields ( 50-1 . 50-2 ) is produced. Method according to one of the preceding claims, characterized in that the patterning radiation field ( 50 ) and / or the structuring individual radiation fields ( 50-1 . 50-2 ) are structured by their generation and / or by optical imaging or further processing. Method according to one of the preceding claims, characterized in that by applying to the patterning radiation field ( 50 ) at least one volume hologram in the material area ( 20a ) for the mask ( 20 ) is produced. Method according to one of the preceding claims, characterized in that for forming the patterning radiation field ( 50 ), Laser radiation is used.