DE102013208446A1 - Optical component for guiding radiation beam for facet mirror for illumination system of projection exposure apparatus, has application specific integrated circuits arranged offset to one another in direction of surface normal - Google Patents

Abstract

The component (19) has a control unit (21) controlling displacement of multiple individual mirrors (20), where the individual mirrors are movably controlled. The individual mirrors are provided with a reflective surface (23) that comprises a surface normal (24). The control unit comprises multiple application specific integrated circuits (ASICs) (25, 26). A portion of the ASICs is arranged offset to one another in a direction of the surface normal. The individual mirrors are provided with actuators (31). Independent claims are also included for the following: (1) a method for manufacturing an optical component (2) a method for manufacturing microstructured component.

Description

The invention relates to an optical assembly. The invention further relates to a method for producing an optical assembly. Furthermore, the invention relates to a facet mirror for an illumination optical unit of a projection exposure apparatus and an illumination optics, as well as to an illumination system for a projection exposure apparatus and a projection exposure apparatus. Finally, the invention relates to a method for producing structured components.

An optical assembly with a mirror comprising a plurality of actuatorically displaceable individual mirrors is known from US Pat DE 10 2009 034 502 A1 known.

An object of the present invention is to develop such an optical assembly.

This object is achieved by the assembly according to claim 1.

The essence of the invention is to use a control device with a plurality of application-specific integrated circuits (ASICs) for controlling the displacement of the individual mirrors, wherein at least a part of the ASICs are arranged offset to one another. The ASICs are offset from one another in particular in the direction of a surface normal of the individual mirrors. The ASICs are arranged in particular in the direction of the surface normals one behind the other. The module thus includes mirror-like ASICs and mirror-distant ASICs.

The individual mirrors are in particular micromirrors. In particular, these are mirrors for reflection of EUV radiation, in particular for the reflection of radiation having a wavelength in the range of less than 30 nm. For general details of the individual mirrors and their displaceability, see DE 10 2009 034 502 A1 which is hereby incorporated in its entirety as part of the present application.

In particular, the ASICs are arranged in at least two planes that are offset in the direction of the surface normal. They can also be arranged in three or more levels.

Due to the staggered arrangement of the ASICs, a particularly space-saving arrangement of the control electronics in a direction perpendicular to the surface normal is possible.

According to the invention, it has been recognized that the ASICs required to drive the micromirrors can be very complex. In particular, it may be necessary to accommodate in the ASICs each a damping controller with associated sensing for damping vibrations. Due to its complexity, such a damping controller leads to comparatively large ASICs. The attenuation control and in particular the sensing of the tilting angle speed of the individual mirrors must be arranged as directly as possible on the individual mirrors due to signal integrity. According to the invention, it has been recognized that it may be advantageous to integrate individual functions, such as such a damping control, into separate ASICs and to provide more than a single ASIC for controlling the displacement of an individual mirror, wherein the ASICs provided for driving an individual mirror are in the direction of the surface normal this single mirror in a row, d. H. offset, are arranged.

According to the invention it has been recognized that it is possible by such an arrangement, the contacting of the ASICs on the back of the individual mirror, d. H. on the reflection surface of the individual mirror opposite side to improve. In particular, it is possible to increase the space for contacting. In addition, the data and / or supply lines can be shortened.

While usually contacts of generic modules only on the outer sides of the same are possible, which leads to long supply and / or data lines, which in turn leads to high resistances and capacitances of the lines, the arrangement of the invention allows contacting in the area between two ASICs. In particular, a vertical contacting, i. H. an arrangement of data and / or supply lines in the direction of the surface normal of the individual mirror possible.

According to one aspect of the invention, at least a part of the individual mirrors is provided with actuators which are connected in a signal-transmitting manner with at least two ASICs offset in the direction of the surface normal. Preferably, each individual mirror is provided with such actuators. In particular, it is possible to connect the actuators with exactly one ASIC per level. It may be particularly advantageous to connect their respective actuators in each case with a mirror-like ASIC and in each case with a mirror-distant ASIC for controlling the individual mirror. In this case, the mirror-near and the mirror-distant ASICs can have different functions. In particular, a damping control can be integrated into the mirror-like ASICs.

The mirror-like ASICs are also referred to as low-level ASIC (LLASIC) due to their integrated functions.

According to one aspect of the invention, at least a portion of the ASICs are each arranged on a substrate which has a cross-sectional area which is smaller than the sum of the reflection surfaces of the individual mirrors associated with this ASIC. In particular, it is contemplated that the near-mirror ASICs, i. H. the ASICs, which are arranged closest to the mirror body of each controlled individual mirror to train accordingly.

For controlling the displacement of the individual mirrors, at least one part thereof, in particular each individual mirror, is assigned at least one, in particular at least two, ASICs. In order to control the displacement of the individual mirrors, a mirror-near ASIC and a mirror-distant ASIC are assigned in particular to each individual mirror.

According to one aspect of the invention, at least part of the ASICs, in particular all ASICs, are integrated into a substrate.

Preferably, the optical assembly has a modular design. In particular, it may be a microelectromechanical system (MEMS).

Another object of the invention is to improve a method of manufacturing an optical assembly.

This object is solved by the features of claim 5. The essence of the invention is first to produce a multi-mirror arrangement and an electronic module for controlling the individual mirrors and then assemble. The production of the optical components and the electronic module can be independent of each other. The optical components and the electronic module can be tested before assembly. In other words, it is possible to assemble only pre-tested optical and electronic components. This reduces the error rate.

Further objects of the invention are to improve a facet mirror for an illumination optics, an illumination optics and a lighting system for a projection exposure apparatus and a projection exposure apparatus. These objects are achieved by the features of claims 6 to 9. The advantages result from those of the optical assembly described above.

Another object of the invention is to improve a method for producing structured components.

This object is solved by the features of claim 10. The advantages result from the previously described.

In the following, embodiments of the invention will be explained in more detail with reference to the drawings. Show it:

1 FIG. 2 schematically, a projection exposure apparatus for microlithography with an illumination optical system shown in the meridional section and a projection optical system, FIG.

2 FIG. 2 schematically shows a cross section through an optical assembly with a plurality of individual mirrors, FIG.

3 schematically a view of the contacts of the circuits for controlling the displacement of the individual mirror of the assembly according to 2 .

4 a further schematic view of an optical assembly with a plurality of individual mirrors and

5 schematically process steps of a process sequence for producing an optical assembly.

1 schematically shows in a meridional section a projection exposure system 1 for microlithography. The projection exposure machine 1 includes a lighting system 2 with a radiation source 3 and an illumination optics 4 for the exposure of an object field 5 in an object plane 6 ,

The projection exposure machine 1 further includes a projection optics 7 for mapping the object field 5 in a picture field 8th in an image plane 9 ,

One is exposed in the object field 5 arranged and in the 1 not shown reticle, the one with the projection exposure system 1 contributes to the production of microstructured or nanostructured semiconductor devices to be projected structure. The structure on the reticle is determined by the projection optics 7 on a photosensitive layer in the area of the image field 8th with the picture plane 9 arranged wafer, which in the 1 not shown, projected.

The reticle is made by one in the 1 held reticle holder not shown. The wafer is made by one in the 1 Not shown wafer holder held. The reticle holder and the wafer holder can during operation of the projection exposure system 1 be moved synchronously to each other.

At the radiation source 3 it is in particular an EUV radiation source with an emitted useful radiation 10 in the wavelength range between 5 nm and 30 nm. For the useful radiation 10 this is therefore EUV radiation.

The EUV radiation emitted by the radiation source 3 emanating from a collector 11 bundled. A corresponding collector is for example from the EP 1 225 481 A known. After the collector 11 propagates the EUV radiation through an intermediate focus level 12 before moving to a field facet mirror 13 meets. The field facet mirror 13 is in a plane of illumination optics 4 arranged to the object level 6 is optically conjugated.

After the field facet mirror 13 becomes the EUV radiation 10 from a pupil facet mirror 14 reflected. The pupil facet mirror 14 lies either in the entrance pupil plane of the illumination optics 7 or in a plane optically conjugated thereto.

The field facet mirror 13 and the pupil facet mirror 14 are built from a variety of individual mirrors.

With the help of the pupil facet mirror 14 and an imaging optical assembly in the form of a transmission optics 15 with in the order of the beam path for the EUV radiation 10 designated mirrors 16 . 17 and 18 become the field facets of the field facet mirror 13 overlapping each other in the object field 5 displayed. The last mirror 18 the transmission optics 15 is especially in grazing incidence mirrors.

For more details of the general construction of the projection exposure machine 1 and its components are on the DE 10 2009 034 502 A1 directed.

The following is with reference to the 2 and 3 an optical assembly 19 described in more detail. The optical assembly 19 can be part of the field facet mirror 13 or the pupil facet mirror 14 be.

The optical assembly 19 can be designed modular. It is also called a building block or brick.

The optical assembly 19 includes a variety of controlled movable individual mirrors 20 and a controller 21 for the controlled displacement of the individual mirrors 20 , The arrangement of the individual mirrors 20 is also referred to as a multi-mirror array or multi-mirror array (MMA).

The individual mirrors 20 each comprise a mirror body 22 with a reflection surface 23 , The reflection surface 23 is preferably flat. It runs in particular perpendicular to a surface normal 24 , The reflection surface 23 may also be concave or convex. In this case, be below the surface normals 24 of the single mirror 20 one normal to the reflection surface 23 in a central point of the reflection surface 23 Understood.

Each of the individual mirrors 20 also includes an actuator pin 37 , The actuator pin 37 extends in the direction of the surface normal 24 , The reflection surface 23 has in particular a rectangular, preferably a square boundary. In other words, it is in particular rectangular, preferably square. Other forms of reflection surface 23 , in particular their formation as a triangle, in particular as an equilateral triangle, or as a hexagon, in particular as a regular hexagon, are in principle also possible.

The control device 21 includes a plurality of application specific integrated circuits (ASICs) 25 . 26 , According to the invention, at least part of the ASICs is provided 25 . 26 in the direction of the surface normals 24 offset to each other to arrange. In other words, mirror-like ASICs are possible 25 and mirror-less ASICs 26 differ.

According to the invention, provision is made in particular for controlling the displacement of one of the individual mirrors 20 provided ASIC in two or more sub-ASICs 25 . 26 divide. Here are the features that are close to the individual mirror 20 must be in the mirror-like ASIC 25 integrated. This ASIC 25 Also referred to as Low Level ASIC (LLASIC). In principle, other functions in the mirror-like ASIC 25 to get integrated. It can be provided in particular in the mirror-like ASIC 25 Control stages and / or sensing and / or damping electronics and / or an analog input for the tilt angle adjustment of the individual mirrors 20 and / or to integrate a sample-and-hold device. In this case, only supply lines, an analog signal and control signals for the sample-and-hold switches need each of the mirror-like ASICs 25 be supplied. Alternatively, there are other classifications, ie alternative integrations of functions in the near-mirror ASIC 25 possible. For example, the near-mirror ASICs 25 also have a digital damping control.

The mirror-like ASICs 25 have a cross-sectional area which is smaller than the reflection surface of the associated individual mirror 20 , In other words, the distance between adjacent mirror-like ASICs 25 in the direction perpendicular to the surface normal 24 greater than the distance of the mirror body 22 the one through these ASICs 25 controlled individual mirror 20 , The distance between adjacent mirror-like ASICs 25 is in particular at least 1.5 times as large, in particular at least 2 times as large, in particular at least 3 times as large, in particular at least 5 times as large as the distance of the mirror body 22 adjacent individual mirror 20 , Such a design of mirror-like ASICs 25 will ensure that between the mirror-like ASICs 25 enough space remains to vertical lines, ie lines, which in the direction of the surface normal 24 to be able to feed. In other words, this is the contacting of the ASICs 25 improved.

In the 3 is an example of a view of mirror-like ASICs 25 with the associated lines 27 shown. Like from the 3 As an example, the ASICs are 25 arranged such that between two adjacent ASICs 25 each sufficient space for the arrangement of lines 27 remains.

In addition, the control device comprises 21 contact elements 28 , in particular in the form of contact pins 29 , It also includes a circuit board 30 , in particular in the form of a printed circuit board (PCB).

For contacting between mirror-like ASICs 25 and actuator electrodes 31 are in particular so-called flip-chip contacts 32 intended.

In addition, the control device comprises 21 a data distributor (English: Data Dispatcher) 33 and a supply control 34 , The supply control 34 can be designed in particular as DC DC control.

In addition, blocking capacitors can 35 be provided. The blocking capacitors 35 are especially adjacent to supply pins 36 the ASICs 25 . 26 arranged.

From an electrical point of view, the spaced array of ASICs 25 with passage of the lines 27 in the spaces between the ASICs 25 advantageous. In this arrangement, however, the vertical contacting of the circuit board 30 for mirror assembly, for example via spring contact pins, difficult to implement. According to a particularly advantageous embodiment, it is therefore provided, the mirror-near low level ASICs 25 to integrate into a printed circuit board. The mirror-like ASICs 25 especially in a substrate 38 be integrated in ceramic. This allows a very advantageous packaging of the electronics. In particular, so-called "hidden dies" and / or "hidden discrete components" can be used. By "hidden dies" is meant integrated circuits embedded in the printed circuit board. "Hidden Discrete Components" refer to discrete electronic components embedded in the printed circuit board. The substrate 38 with the integrated ASICs 25 is part of an electronic module. Accordingly, the optical components form components of an optical module, which also serves as a multi-mirror module (multi-mirror array module, MMA module 40 ) referred to as.

A corresponding embodiment is shown schematically in the 4 shown. In the 4 is the supply control 34 , in particular the voltage stabilization, not shown. It can also be integrated into higher-level electronics.

Like from the 4 can be seen, the optical assembly 19 on their of the reflection surfaces 23 the individual mirror 20 side facing away from a contact matrix 39 exhibit. The contact matrix 39 may have a lower contact density. The contact matrix 39 In particular, about 80 contacts, which are evenly distributed over an area of 2.5 cm × 2.5 cm, have. This is a lower contact density compared to an arrangement in which all 80 contacts in the marginal 1 mm to 2 mm of the assembly 19 are arranged.

The contact with the mirror assembly can only via contacts, in particular flip-chip contacts 32 , on the substrate 38 and / or the circuit board be realized. In printed circuits, for example of ceramic, techniques are available which allow the production of substantially planar circuits and thus a good contact between the printed circuit and the electronic module 38 and the multi-mirror unit.

Another advantage is that on the back of the optical assembly 19 ie on the reflection surfaces 23 the individual mirror 20 remote side of the optical assembly 19 , no wiring, especially no metallic wiring, and no insulation is required. This will produce the optical assembly 19 , in particular the carrying out of etching steps, facilitated.

The ASICs 25 . 26 can also be completely in the substrate 38 be embedded.

Another advantage of the inventive arrangement of ASICs 25 . 26 is that the data distribution from the data distributor 33 and / or any higher-level unit does not have a chain of multiple ASICs 25 must be realized. In particular, it is possible to use any low level ASIC 25 directly to drive. Depending on the design of the system, the mirror-distant high-level ASIC 26 be designed as a DA converter.

The control of a sample and hold logic can also be done by the Data Dispatcher unit 33 be made. As a data dispatcher unit 33 may be, for example, a simple CPLD / FPGA die (CPLD = Field Programmable Logic Device).

It is also possible to have multiple individual mirrors 20 a common low level ASIC 25 assigned. It is possible, in particular, subgroups of 1 × 2 individual mirrors 20 or 2 × 2 individual mirrors 20 or 2 × 3 individual mirrors 20 or 3 × 3 individual mirrors 20 or other groupings of individual mirrors 20 each a common low-level ASIC 25 assigned.

The optical assembly 19 For example, a matrix of 32 × 32 individual mirrors 20 and 8x8 associated low level ASICs 25 exhibit. This can be six s / h logic signals and two error / test pins per ASIC 25 be provided. In particular, it is possible to assign a single digital-to-analogue converter (DA converter) to a plurality of actuators, thereby reducing the space requirement of the DA converters on the ASIC. In this case, it is provided in particular to use a "sample-and-hold" scheme in order to distribute the analog output signals of the DA converter. The analogue output signal is held in this case in particular in the form of capacitances in each actuator channel, that is to say the one analogue output of the DA converter successively charges the capacitances at the inputs of the actuator channels to the respective output voltage. The timing of the charging of the capacitances is achieved by proper control of switches connecting the output of the DA converter to the input capacitances of the actuator channels. The control of the holder via the said six s / H logic signals. With the six s / h control signals, 2 ⁶ = 64 switch positions can be represented to control the sample-and-hold switches in time. The error / test pins are used to exchange status and error information.

The optical assembly 19 thus has 64 × 8 pins = 512 logic pins in this case. An extreme reduction is possible if multiple ASICs 25 synchronously perform sample-and-hold.

Another advantage of the inventive arrangement of ASICs 25 is that no chaining of ASICs 25 must be made, and thus in case of failure of one of the ASICs 25 not an entire ASIC chain fails immediately.

• – drei bis vier Ansteuerungskontakte (zum MMA),
• – ein analog im (zum/vom DA-Wandler),
• – eins HV Versorgung in die gedruckte Schaltung (Versorgung),
• – ein AGND in die gedruckte Schaltung (Versorgung),
• – eine digitale Versorgung in die gedruckte Schaltung (Versorgung),
• – ein digital GND in die gedruckte Schaltung (Versorgung),
• – sechs digital in (für 48 Sample-and-Hold-Schalter zum Datenverteiler 33),
• – ein digital in „Test Enable” (zum Datenverteiler 33),
• – ein digital out „Error Flag” (zum Datenverteiler 33).

According to one embodiment of the description are in the low level ASIC 25 the HV drivers as well as optional local controllers with sensing and sample-and-hold capacitors and switches integrated. According to this embodiment, the interface of the low level ASIC comprises 25 at a low level ASIC 25 for controlling an array of 4 × 4 individual mirrors 20 each with three or four actuator electrodes 31 the following elements:

• - three to four control contacts (for MMA),
• - an analog in (to / from the DA converter),
• - one HV supply to the printed circuit (supply),
• An AGND in the printed circuit (supply),
• A digital supply to the printed circuit (supply),
• A digital GND in the printed circuit (supply),
• - six digital in (for 48 sample-and-hold switches to the data distributor 33 )
• - a digital in "Test Enable" (to the data distributor 33 )
• - a digital out "Error Flag" (to the data distributor 33 ).

All contacts and / or pads to the ASICs 25 are first connected to the printed circuit. In the further course, the lines are fed through the printed circuit to the corresponding further contacts. Up to the MMA, only the three or four drive voltages must be routed.

The above is a simplified talk of printed circuits. These can be integrated into any carriers, substrates or interposer-like carriers or designed as such components.

In the 4 The illustrated embodiment also provides advantages in the manufacture, assembly, integration, and testing of the components of the optical assembly 19 , In this embodiment, in particular, the MMA module is provided 40 and to manufacture the electronic module separately.

Due to the separate production, the MMA module 40 and the electronic module are tested separately. It is provided according to the invention, only pre-tested MMA modules 40 and to assemble electronic modules. This increases the effective yield (yield).

The following is a method of making the optical assembly 19 described. First, in a deployment step 42 ready-processed actuator wafers and mirror wafers provided. In this case, the mirror, spring and electrode clearances are not yet etched.

Then in an application step 43 an etch stop applied to the MMA back.

In a subsequent etching step 44 the mirror and electrode clearances are etched free.

In a subsequent bonding step 45 the entire electronic module is connected to the MMA for a brick. Here are exclusively before in a test step 46 tested modules used. For the bonding step 45 In particular, a so-called flip-chip bonding may be provided.

To prevent the bonding step 45 the individual mirrors 20 can be advantageously provided, between the MMA module 40 and the electronic module an interposer 47 contribute. Under such an interposer 47 In this case, a wafer is to be understood, which represents only a wiring, but serves as an etch stop and the MMA module 40 tightly sealed in the direction of the electronic module, in particular to shield it from the corrosive gas or the corrosive liquid. The bonding of the electronic module to the interposer 47 is compared to direct bonding of the electronic module to the MMA module 40 easier because of the MMA module 40 with the interposer 47 at the interposer 47 can be held, the interposer 47 provides additional stability and rigidity.

It is also possible to connect the electronic module with a connection technique to the MMA module 40 applying, which seals and at the same time the contacts to the MMA module 40 manufactures. In this case, the electronic module serves as an etch stop for the exposure of the individual mirror 20 ,

The ASICs 25 can be coated and / or potted in an advantageous variant. They can be protected against attack by the etching medium.

For producing structured components with the aid of a projection exposure apparatus according to the invention, the following method is provided: First, a wafer, to which at least partially a layer of a photosensitive material is applied, and a reticle having structures to be imaged are provided. Then, at least a portion of the reticle is applied to a portion of the layer of the wafer by means of the projection exposure apparatus 1 projected.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009034502 A1 [0002, 0006, 0038]
• EP 1225481A [0034]

Claims (10)

Optical assembly ( 19 ) for guiding a radiation beam with a. a plurality of controlled displaceable individual mirrors ( 20 ) and b. a control device ( 21 ) for the controlled displacement of the individual mirrors ( 20 c. where the individual mirrors ( 20 ) each have a reflection surface ( 23 ) with a surface normal ( 24 ), d. the control device ( 21 ) a plurality of application specific integrated circuits (ASICs) ( 25 . 26 ), and e. where at least part of the ASICs ( 25 . 26 ) in the direction of the surface normals ( 24 ) are offset from one another. Optical assembly ( 19 ) according to claim 1, characterized in that at least a part of the individual mirrors ( 20 ) with actuators ( 31 ) provided with at least two in the direction of the surface normal ( 24 ) staggered ASICs ( 25 . 26 ) are connected in a signal-transmitting manner. Optical assembly ( 19 ) according to claim 1 or 2, characterized in that at least a part of the ASICs ( 25 . 26 ), each on a substrate ( 38 ) are arranged, which has a cross-sectional area which is smaller than the sum of the reflection surfaces ( 23 ) of this ASIC ( 25 . 26 ) associated with individual mirror ( 20 ). Optical assembly ( 19 ) according to one of the preceding claims, characterized in that at least a part of the ASICs ( 25 . 26 ) into a substrate ( 38 ) are integrated. Method for producing an optical assembly ( 19 ) according to one of the preceding claims comprising the following steps: a. Production of a multi-mirror array (MMA) with a large number of individual mirrors ( 20 b. Production of an electronic module for controlling the individual mirrors ( 20 c. Assembly of MMA and electronic module. Facet mirror ( 13 . 14 ) for an illumination optics ( 4 ) of a projection exposure apparatus ( 1 ) with at least one optical assembly ( 19 ) according to one of claims 1 to 4. Illumination optics ( 4 ) for a projection exposure apparatus ( 1 ) with at least one optical assembly ( 19 ) according to one of claims 1 to 4. Lighting system ( 2 ) for a projection exposure apparatus ( 1 ) with a. at least one optical assembly ( 19 ) according to any one of claims 1 to 4 and b. a radiation source ( 3 ). Projection exposure apparatus ( 1 ) with a. an illumination optics ( 4 ) and b. a projection optics ( 7 ) for imaging in an object plane ( 6 ) present object field ( 5 ) in an image field ( 8th ) of an image plane ( 9 ). A method for producing structured components, comprising the following steps: providing a wafer, on which at least partially a layer of a photosensitive material is applied, providing a reticle having structures to be imaged, providing a projection exposure apparatus, 1 ) according to claim 9, - projecting at least a part of the reticle onto a region of the layer of the wafer with the aid of the projection exposure apparatus ( 1 ).

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