CN101396764A

CN101396764A - Laser machining device

Info

Publication number: CN101396764A
Application number: CNA2008101498409A
Authority: CN
Inventors: 江田幸夫; 安达贞志; 栗田典夫; 筬岛哲也
Original assignee: Hamamatsu Photonics KK; Olympus Corp
Current assignee: Hamamatsu Photonics KK; Olympus Corp
Priority date: 2004-04-28
Filing date: 2005-04-27
Publication date: 2009-04-01
Anticipated expiration: 2025-04-27
Also published as: JP2005316069A; CN101396765B; JP4681821B2; CN100485446C; CN101396765A; CN1906522A; CN101396764B

Abstract

A laser condensing optical system of the present invention includes a laser beam source which emits a laser beam, a condensing optical system which is arranged between the laser beam source and a medium and condenses the laser beam in the medium, and a laser divergence point moving unit which can move the position of a laser divergence point of the laser beam along an optical axis of the laser beam in accordance with the refractive index of the medium in which the laser beam is desired to be condensed and the distance from a surface of the medium to a position where the beam is desired to be condensed.

Description

Laser machining device

The application is that the original bill application number is 200580001727.0 application for a patent for invention (international application no: PCT/JP2005/008003, the applying date: on April 27th, 2005, denomination of invention: dividing an application laser machining device).

Technical field

The present invention relates to laser beam is focused at the laser convergence optical system and the laser machining device at the diverse location place in the medium.

The invention still further relates to laser machining device, it can change the position of electron gun, keeps being incident on the constant intensity and the intensity distributions of the light on the pupil plane of optical system simultaneously.The invention particularly relates to a kind of desirable laser machining device that laser beam can be focused at the position of the different depth in the medium, perhaps relate to a kind of laser machining device that is suitable for changing converged position.

Background technology

Current, laser beam is used to various fields, and is developing the various types of devices that use laser beam.An example is to use laser beam to come the treating apparatus of cutting process target (as semiconductor wafer or glass).This treating apparatus comprises convergence optical system, and this convergence optical system produces modified layer etc., thereby cuts this medium by to assembling from laser beam sources emitted laser Shu Jinhang in medium.When cutting,,, but must be focused at different thickness places according to the thickness of processing target so laser beam always is not focused at same degree of depth place because processing target has all thickness.That is, there is the demand that laser beam is converged at the section of the different depth in the medium.

Yet, owing to the amount of spherical aberration difference of locating at different depth (thickness), so the convergence performance may change (deterioration).

As mentioned above, although exist, tend to produce spherical aberration in this case with the demand on the cross section of the different depth of beam convergence in medium.For example, in field of biology, use glass to cover sample usually and prepare microobject, wherein sample is placed on the slide and with the glass cover sealing, when the sample of the glass cover that has different-thickness by microscopic examination, can produce spherical aberration.The glass that is used for LCD has different thickness, therefore may produce spherical aberration when observing by substrate.When amount of spherical aberration changes along with the difference of thickness (degree of depth), exist to assemble the change problem of (deterioration) of performance.

Therefore, use various routine techniques that light is converged at (as mentioned above) on the different-thickness cross section, changes of properties is assembled in correcting spherical aberration and inhibition simultaneously.

For example, in a kind of such technology, locate removably to engage polylith parallel-plate glass at the end (as object lens) of convergence optical system with different-thickness.

Also have a kind of so conventional object lens, it has and is used for microscopical corrector loop, and this corrector loop has successfully been proofreaied and correct the aberration on the super wide field, and these object lens have the multiplication factor of about 40 refractive power and 0.93 NA (numerical aperture) (for example, referring to patent documentation 1).

Also have a kind of like this optical system, it comes correcting spherical aberration (for example, referring to patent documentation 2) by move the spherical aberration correction optical system of no refractive power lens along optical axis direction.

In addition, Figure 20 shows a kind of like this microscopie unit, wherein, by arranging sa correction lens 232 and move this sa correction lens 232 along optical axis between object lens 230 and light source 231, comes correcting spherical aberration (for example, referring to patent documentation 3).

Patent documentation 1: Japanese Unexamined Patent Application, communique H05-119263 number (Fig. 1 etc.) for the first time

Patent documentation 2: Japanese Unexamined Patent Application, communique 2003-175497 number (Fig. 1 etc.) for the first time

Patent documentation 3: Japanese Unexamined Patent Application, communique 2001-83428 number (Fig. 1 etc.) for the first time

Yet, when stating parallel-plate glass in the use and coming correcting spherical aberration, because the inclination of parallel-plate glass etc. cause performance degradation very big.Therefore the framework that is used for the keeping parallelism plate needs high accuracy, and this frame fixation is also needed high accuracy in the mode of parallel-plate; Its cost is very high.In addition, need in making spacing (WD), the unskilled labourer manually change; This is the operation that extremely bothers.Realize that continuous variable is also very difficult.

The object lens of describing in patent documentation 1 that have corrector loop are high-precision, and are therefore very expensive, make and can not reduce cost.The difficulty of automatically regulating amount of spherical aberration according to converged position makes these lens be not suitable for carrying out automation.

In the optical system of in patent documentation 2, describing, owing to come the correction group complex focus by no refractive power lens, so even proofreaied and correct spherical aberration, converged position can not change yet.In the process on attempting light is converged at the different cross section of medium, WD changes inevitably, makes to come aberration correction by constant WD.Because require the spherical aberration correction optical system to be positioned at position except that beam expander, complexity and component count increase so its structure becomes, feasiblely be difficult to reduce cost.

In the microscopie unit of in patent documentation 3, describing, although can be as illustrated in fig. 20 by coming correcting spherical aberration along optical axis direction moving sphere aberration correction lens 232, the diameter that is incident on the bundle on the object lens 230 changes along with moving of sa correction lens 232.

That is, the stent of light beam can change.As a result, as shown in figure 21, its light intensity can change, so the lip-deep brightness of sample also can change.If be provided with image extraction unit, then can use it to come the brightness of image is detected and changes according to this brightness the power of light source.Although can brightness be kept constant by carrying out control etc., have the problem that increases such as the apparatus structure complexity in image end.

When in pupil plane, having light distribution, the danger that exists this light distribution also can change.This variation of light distribution may influence the convergence performance.In addition, owing to come moving sphere aberration correction lens according to the signal of telecommunication from image capturing unit, so this method is very consuming time.

Summary of the invention

In view of the foregoing realized the present invention, the present invention aims to provide a kind of laser convergence optical system and a kind of laser machining device, and it has simple structure and correcting spherical aberration and not consuming time easily.

In order to realize above purpose, the present invention has used with lower device.

A kind of laser convergence optical system of the present invention comprises: laser beam sources, and it launches laser beam; Convergence optical system, it is arranged between described laser beam sources and the medium, and described laser beam is focused in the described medium; And laser divergence point mobile unit, its can according to hope described laser beam is converged to the refractive index of described medium wherein and from the surface of described medium to hope with described beam convergence to the distance of converged position, come along the position that the optical axis of described laser beam moves the laser divergence point of described laser beam.

According to this laser convergence optical system, described convergence optical system can with from the beam convergence of described laser beam sources emitted laser medium.At this moment, described laser beam is incident on the described convergence optical system by divergent state (non-parallel state).Promptly, launch described laser beam from described laser beam sources by divergent state, perhaps launch described laser beam by parastate, before on the described convergence optical system, convert it to divergent state at described laser beam incident then by the optical system of forming by various lens etc. from described laser beam sources.The point that described laser beam becomes divergent state is exactly described divergence point.When according to hope described laser beam is converged to the refractive index of described medium wherein and from the surface of described medium when the distance of the converged position of hope is assembled described laser beam, described laser divergence point mobile unit moves described laser divergence point along the optical axis of described laser beam, even make the position that described laser beam is focused at the different depth place in the described medium, also can be suppressed at the amount of spherical aberration that the position produces significantly.Therefore, described laser beam can be focused at effectively the hope degree of depth place in the described medium, and can strengthen the convergence performance.

Particularly, owing to only move a described laser divergence point, thus correcting spherical aberration easily, and be unlike in the usual manner consuming time like that.In addition, because need not be such as the special optical system of conventional object lens, so designs simplification is reduced cost simultaneously with corrector loop.In addition, owing to only need mobile laser divergence point, thus realize continuous changeability and easy adjustment structure easily, to carry out automation.

Described laser divergence point mobile unit can be provided with the position of described laser divergence point based on the wave front data of the described convergence optical system that records in advance.

In the case, since described laser divergence point mobile unit the wave front data of considering the described convergence optical system that records in advance (as the wave front data of the object lens of the part of convergence optical system as described in forming and the wave front data of whole convergence optical system) afterwards to as described in the position of laser divergence point be provided with, so can further strengthen the convergence performance of described laser beam and observe performance.

Can viewing optical system be set with matching with described convergence optical system, described viewing optical system keeps from the bottom surface of described convergence optical system to the preset distance on the surface of described medium.This viewing optical system can comprise automatic focus detecting unit or autofocus mechanism.

In the case, since for example when the relatively mobile described convergence optics of along continuous straight runs is unified described medium (, when scanning) described viewing optical system can remain on the preset distance between the surface of the bottom surface of described convergence optical system and described medium, so can when will assembling the laser beam of wishing degree of depth place to remain on same position, carry out scanning.Therefore, described laser beam can be focused on the whole medium, the different depth place that is suppressed at significantly simultaneously in the medium produces spherical aberration.

Relative distance along optical axis direction between the surface of described convergence optical system and described medium can be constant.

In the case, even wish described laser beam has been converged to the change in depth in the described medium, because the relative distance along optical axis direction (that is, is constant WD), so also can make designs simplification between the surface of described convergence optical system and described medium.

Can also accept to use the laser machining device that comprises described convergence optical system.

In the case, described laser beam can be focused at effectively the different depth place in the described medium, suppress the generation of spherical aberration simultaneously significantly.Therefore, can carry out laser treatment exactly, and cut crystal etc. accurately.

Laser machining device according to first aspect present invention comprises: laser beam sources, and it launches laser beam; The collimation unit, it will be collimated into parallel rays from the light of described laser beam sources emitted laser bundle; Convergence optical system, its described parallel rays with described laser beam is focused in the medium; First set of lenses, it is arranged in the parallel rays between described collimation unit and the described convergence optical system, and can move along the optical axis direction of described parallel rays, and first set of lenses comprises one or more lens; Second set of lenses, it firmly is arranged in the parallel rays between first set of lenses and the described convergence optical system, and comprises one or more lens; And mobile unit, its according to hope described laser beam is converged to the refractive index of described medium wherein and from the surface of described medium to the distance of the position that hope converges to described laser beam, move first set of lenses.The rear side focal length of second set of lenses be arranged at least described convergence optical system the entrance pupil position near.

According to this laser machining device, become parallel rays from the described laser beam of described laser beam sources emission by described collimation cell translation, and before on being incident on the described convergence optical system that it is focused in the described medium by first set of lenses and the refraction of second set of lenses.At this moment, described mobile unit moves first set of lenses along optical axis direction, can move described beam source position along optical axis direction thus.That is, can change the position of the electron gun of seeing from second set of lenses, and also can change the physical location of the electron gun of seeing from described convergence optical system by moving first set of lenses.

Owing to move first set of lenses according to refractive index that described laser beam is converged to described medium wherein and distance from the surface of described medium to the position that described laser beam is converged to, so can change the position of the electron gun of seeing from described convergence optical system, and the position (degree of depth) that described laser beam can be focused at hope is located, and suppresses the generation of spherical aberration simultaneously significantly.Therefore, can carry out laser treatment exactly, and cut crystal etc. accurately.

In addition, second set of lenses is arranged to, and makes its rear side focal length and the described entrance pupil position of described convergence optical system be complementary.Even first set of lenses moves along optical axis, position regardless of first set of lenses, the described parallel rays that is incident on first set of lenses also has identical diameter in the described entrance pupil position of described convergence optical system all the time, and is assembled by described convergence optical system and can not blur.This feasible Strength Changes that can reduce at the converged position place, and, owing to the intensity distributions on the described entrance pupil face of described convergence optical system can not change, so can suppress to assemble the deterioration of performance.

In addition, owing to can only change the position of electron gun by moving first set of lenses, so needn't be in the usual way along optical axis direction mobile convergence optical system, pedestal etc.Therefore, can make designs simplification, and correcting spherical aberration and do not have operation consuming time easily.In addition, owing to need so can make designs simplification, not reduce cost simultaneously such as the special optical system of the object lens that have corrector loop.

In the case, since for example when the relatively mobile described convergence optics of along continuous straight runs is unified described medium (, when scanning) described viewing optical system can remain on the preset distance between the surface of the bottom surface of described convergence optical system and described medium, so can when will assembling the laser beam of wishing degree of depth place to remain on same position, carry out scanning.

In the case, owing between the surface of described convergence optical system and described medium, (that is, be constant WD),, and make it not expensive so the structure of described autofocus mechanism is further simplified along the relative distance of optical axis direction.

When | when f| was the combined focal length of first set of lenses and second set of lenses, described mobile unit can move to first set of lenses position of satisfying following formula:

1/|f|<0.01。

When f2 was the focal length of second set of lenses, second set of lenses can satisfy following formula:

f2>0。

When f1 is the focal length of first set of lenses and f2 when being the focal length of second set of lenses, first set of lenses and second set of lenses can satisfy following formula:

f1<0，

And 1≤| f1/f2|≤5.

f1>0，

And 0.5≤| f1/f2|≤2.

Laser machining device according to second aspect present invention comprises: laser beam sources, and it launches laser beam; Convergence optical system, it is focused at described laser beam in the medium; And laser convergence optical system, wherein, according to hope described laser beam is converged to the refractive index of described medium wherein and from the surface of described medium to the distance of the position that hope converges to described laser beam, a plurality of lens that satisfy following formula ad hoc are inserted on the light path of the divergent rays of described convergence optical system and/or converging ray or and remove from this light path:

2(d ²+l×f-l×d)NA＝f×a

Wherein, d be from the entrance pupil position of convergence optical system to the distance of described a plurality of lens,

L be from the described entrance pupil position of described convergence optical system to the distance of described beam source position,

F is the focal length of described a plurality of lens,

NA is the numerical aperture (numerical aperture of seeing from convergent lens) of described electron gun, and

A is the entrance pupil diameter of described convergence optical system.

A kind of laser machining device according to third aspect present invention comprises: laser beam sources, and its emission is parallel to the laser beam of optical axis; Optical system, it is focused at described laser beam in the medium;

And laser convergence optical system, wherein, according to hope described laser beam is converged to the refractive index of described medium wherein and from the surface of described medium to the distance of the position that hope converges to described laser beam, a plurality of lens that satisfy following formula ad hoc are inserted in the described laser beam or from described laser beam remove:

b(f-d)/f＝a

Wherein, b is the diameter from the collimatied beam of described electron gun,

D be from the entrance pupil position of convergence optical system to the distance of described a plurality of lens,

F is the focal length of described a plurality of lens, and

A is the entrance pupil diameter of described convergence optical system.

Beneficial effect of the present invention is, laser convergence optical system according to the present invention, laser divergence point mobile unit according to hope laser beam is converged to the refractive index of medium wherein and from the surface of described medium to the distance of assembling the position, optical axis along laser beam moves the laser divergence point, thus the amount of spherical aberration that the feasible position that can be suppressed at the different depth in the described medium significantly produces.Therefore, described laser beam can be focused at effectively the hope degree of depth place in the described medium, and can strengthen the convergence performance.

Particularly, owing to only move a described laser divergence point, thus correcting spherical aberration easily, and be unlike in the usual manner consuming time like that.In addition, owing to do not need the special optical system, so designs simplification is reduced cost simultaneously.

According to a kind of laser machining device that comprises described laser convergence optical system, laser beam can be focused at effectively the different depth place in the medium, suppress spherical aberration simultaneously significantly and produce, make and can carry out laser treatment exactly.

Arrive the laser machining device of the third aspect according to a first aspect of the invention, according to hope with described beam convergence to the refractive index of wherein described medium and from the surface of described medium to hope with described beam convergence to the distance of position move first set of lenses, thereby move the position of described laser beam incident on second set of lenses, that is the position of the described laser beam of seeing from described convergence optical system.This makes the degree of depth (position) that described laser beam can be focused at hope locate, and suppresses the amount of spherical aberration that is produced simultaneously significantly.Therefore, can carry out laser treatment accurately.

In addition, because the rear side focal position of second set of lenses and the described entrance pupil position of described convergence optical system are complementary, can not change so be incident on the diameter of the light on the described entrance pupil of described convergence optical system.This makes incident intensity and intensity distributions in described pupil plane keep constant, has suppressed the convergence changes of properties.

Owing to can be only change the position of described electron gun by moving first set of lenses, thus can make designs simplification, and correcting spherical aberration and do not have operation consuming time easily.

Description of drawings

Fig. 1 shows the structure chart according to the laser machining device of first embodiment of the invention and laser convergence optical system.

Fig. 2 is the example of the flow chart when using same laser convergence optical system that laser beam is radiated at a plurality of position apart from the different depth place of wafer surface.

Fig. 3 uses same laser convergence optical system to come the example of the flow chart of illuminating laser beam after the wave front data of having considered convergence optical system.

Fig. 4 is the figure according to the structure of the laser convergence optical system of second embodiment of the invention.

Fig. 5 is the example of the flow chart when using same laser convergence optical system that laser beam is radiated at a plurality of position apart from the wafer surface different depth.

Fig. 6 is the figure according to the structure of the laser convergence optical system of third embodiment of the invention, and it is the example of the flow chart when a plurality of position of laser beam being radiated at apart from the wafer surface different depth.

Fig. 7 shows the figure of the state when according to same flow chart laser beam being radiated at a plurality of position apart from the wafer surface different depth.

Fig. 8 shows the figure according to the structure of the laser convergence optical system of fourth embodiment of the invention.

Fig. 9 is the example of the flow chart when using same laser convergence optical system that laser beam is shone a plurality of position apart from the wafer surface different depth.

Figure 10 is the figure that illustrates according to the structure of the laser machining device of fifth embodiment of the invention.

Figure 11 is the example of the flow chart when using same laser machining device that laser beam is focused at hope degree of depth place in the wafer.

Figure 12 is the illustrative flow according to the laser machining device of sixth embodiment of the invention, and it is the example of the flow chart when laser beam being focused at hope degree of depth place in the wafer and keeping constant WD simultaneously.

Figure 13 is the figure according to the structure of the laser convergence optical system of seventh embodiment of the invention.

Figure 14 is the figure according to the structure of the laser convergence optical system of eighth embodiment of the invention.

Figure 15 shows the figure according to the structure of the laser convergence optical system of ninth embodiment of the invention.

Figure 16 is a kind of figure of laser machining device, in this laser machining device, is furnished with a plurality of convex lens on the light path of divergent rays, and these convex lens can be inserted in this light path or from this light path and remove.

Figure 17 is a kind of figure of laser machining device, in this laser machining device, is furnished with a plurality of convex lens on the light path of converging ray, and these convex lens can be inserted in this light path or from this light path and remove.

Figure 18 is a kind of figure of laser machining device, in this laser machining device, is furnished with a plurality of concavees lens on the light path of parallel rays, and these concavees lens can be inserted in this light path or from this light path and remove.

Figure 19 is a kind of figure of laser machining device, in this laser machining device, convert parallel rays to divergent rays by convex lens, and on these divergent rays, be furnished with a plurality of concavees lens, and these concavees lens can be inserted on this light or from this light and remove.

Figure 20 is the key diagram of conventional spherical aberration correction, and it can be along the example of the optical system of optical axis direction moving sphere aberration correction lens for making.

Figure 21 is the figure that the light intensity of the entrance pupil position in the optical system of Figure 20 changes.

Brief description to reference symbol

A wafer (medium)

The L laser beam

1 laser convergence optical system

2,103 convergence optical systems

3 laser divergence points

4 laser divergence point mobile units

10 viewing optical systems

101 laser machining devices

104 first lens (first set of lenses)

105 second lens (second set of lenses)

106 mobile units

107 viewing optical systems

120 second set of lenses

125 first set of lenses

The specific embodiment

Followingly laser convergence optical system and laser machining device according to first embodiment of the invention are described with reference to Fig. 1 and 2.

Laser machining device of the present invention can scanning flatly be in the laser beam L of converged state in wafer (medium) A, and carries out laser treatment, and this wafer A is cut into given size, and comprises laser convergence optical system 1 shown in Figure 1.The laser machining device of present embodiment also comprise can mobile horizontally and vertically wafer A the pedestal (not shown).

Laser convergence optical system 1 comprises: the laser beam sources (not shown), and it presses the state emission laser beam L of parallel rays; Convergence optical system 2, it comprises and places between laser beam sources and the wafer A and laser beam L is focused at object lens of wafer A etc.; And laser divergence point mobile unit 4, its can according to the hope refractive index that is used for convergent laser bundle L and from the surface of wafer A to the distance of wishing converged position, move the position of the laser divergence point 3 of laser beam L along the optical axis of laser beam L.

In the present embodiment, laser divergence point 3 is will change over the position of divergent rays (non-parallel state) from the parallel rays of laser beam sources emitted laser bundle L by the predetermined optical system.When laser beam sources being arranged so that it can launch laser beam by non-parallel state, be laser divergence point 3 from the position that laser beam sources is launched.

Laser divergence point mobile unit 4 is connected to the controller (not shown), and at mobile laser divergence point 3 after this controller receives signal.This controller comprises and can import the input block of predetermined information and the calculator that the amount of movement of laser divergence point 3 is calculated based on the various information that are input to input block (input data) to it.According to the result who is calculated, controller sends signal to laser divergence point mobile unit 4, makes it move laser divergence point 3.

Except laser divergence point mobile unit 4 was controlled, controller was also controlled laser beam sources simultaneously, made it launch laser beam L after laser divergence point 3 moves.

Below such example is described, wherein, use the laser convergence optical system 1 that constitutes as described above that laser beam L is focused at apart from the different depth place on the surface of wafer A, and cut it by wafer A is scanned.In the present embodiment, will the example of the position of the degree of depth of 50 μ m, 75 μ m and 100 μ m describes to for example wherein laser beam being focused at apart from the surface.

In Fig. 2, for laser beam L being focused at apart from the position of the degree of depth of the surface 50 μ m of wafer A, to the refractive index of the input block of controller input wafer A, from the surface of wafer A to the distance (that is 50 μ m) of assembling the position and the numerical aperture (NA) (step S1) of convergence optical system 2.Based on these input data, (that is, the distance between laser divergence point 3 and the convergence optical system 2, and the distance between the surface of convergence optical system 2 and wafer A promptly, WD) are calculated (step S2) to calculator to the amount of movement of laser divergence point 3.After having carried out calculating, based on the result who is calculated, controller is controlled laser divergence point mobile unit 4, to move laser beam L along optical axis direction, thereby the position of laser divergence point 3 is moved to the precalculated position, and change the distance W D (step S3) between convergence optical system 2 and the wafer A.

At mobile laser divergence point 3 and after changing WD, controller sends signal to laser beam sources, makes it launch laser beam L (step S4).The emitted laser bundle L of institute becomes in the position of laser divergence point 3 (moving to the precalculated position by laser divergence point mobile unit 4) and to disperse, and is focused at apart from the position of the surface 50 μ m of wafer A by convergence optical system 2 then.

At this moment, owing to regulate the position of laser divergence point 3 according to the degree of depth of 50 μ m as described above, thus can suppress the amount of spherical aberration that produced significantly, and laser beam L can be focused at effectively the position of 50 μ m.

For laser beam L being focused at apart from the position of the degree of depth of the surface 75 μ m of wafer A and 100 μ m, by mode same as described above to the refractive index of input block input wafer A, from wafer A to the distance (that is, 75 μ m and 100 μ m) of assembling the position and the NA of convergence optical system 2.Carried out calculating by calculator after, based on the result who is calculated, controller is controlled laser divergence point mobile unit 4, move it with optical axis direction along laser beam L, thereby move to as (b) among Fig. 1 the position of laser divergence point 3 and the precalculated position (c), and change WD.Then, emission laser beam L, and convergence optical system 2 is focused at it apart from the surface 75 μ m of wafer A and the position of 100 μ m.

Owing to regulate the position of laser divergence point 3 according to the degree of depth of 75 μ m and 100 μ m by mode same as described above, so can be suppressed at the amount of spherical aberration that these degree of depth places produce significantly, and laser beam L can be focused at effectively the position of 75 μ m and 100 μ m.

When being focused at laser beam L among the wafer A, energy is focused at a point (convergent point) and goes up and produce the crack.Particularly, suppress spherical aberration significantly, so can produce the crack in the position of hope exactly owing to laser beam L can be focused at the position of different depth (50 μ m, 75 μ m and 100 μ m).

When laser beam L is focused at the desired depth place, by being carried out horizontal sweep, pedestal carries out laser treatment, and adjacent crack can be coupled together, thereby wafer A is cut into given size, for example, be cut to sheet.

As mentioned above, laser machining device and laser convergence optical system according to present embodiment, when laser beam L being focused at different depth 3a (50 μ m, 75 μ m and 100 μ m) when locating apart from the surface of wafer A, laser divergence point mobile unit 4 according to the refractive index of wafer A and from the surface of wafer A to the distance of each converged position, move laser divergence point 3 along optical axis.This has suppressed the amount of spherical aberration that is produced significantly, and effectively laser beam L is focused at each degree of depth place by desirable state.By scanning at each degree of depth place, can carry out laser treatment more accurately, make cutting process more accurate.

Particularly, because the only mobile laser divergence point 3 of this structure, thus correcting spherical aberration easily, and be unlike in the usual manner consuming time like that.Because need not be such as the special optical system of object lens, so designs simplification is reduced cost simultaneously with corrector loop.In addition, because mobile laser divergence point 3 only, thus realize continuous changeability and adjustment structure easily easily, to carry out automation.

Although in first embodiment, to input block imported the refractive index of wafer A, from the surface of wafer A to the distance of assembling the position and the NA of convergence optical system 2, so that the position of laser divergence point 3 is calculated, the present invention is not limited to this.For example, except that these input data, can also accept to import the wave front data that records from convergence optical system 2 in advance, and the position of laser divergence point 3 be calculated based on these data.

As shown in Figure 3, when when input block is imported various data (above step S1), imported the refractive index of wafer A, from the surface of wafer A to distance, the NA of convergence optical system 2 and the wave front data of convergence optical system 2 of assembling the position.

This feasible correcting spherical aberration accurately, and the convergence performance of enhancing laser beam L.

The wave front data of convergence optical system 2 can be made up of the wave front data of the object lens of a part that forms convergence optical system 2 or the wave front data of whole convergence optical system 2.

Subsequently, with reference to Figure 4 and 5 the convergence optical system according to second embodiment of the invention is described.In a second embodiment, by identical label represent with first embodiment in the identical element of element, and these elements of not repeat specification.

The difference of second embodiment and first embodiment is: in first embodiment, and a traveling platform in scanning process, and in a second embodiment, carry out scanning in the constant distance between the surface that keeps convergence optical system 2 and wafer A.

As shown in Figure 4, the convergence optical system 2 of present embodiment comprises the viewing optical system 10 that is provided with convergence optical system 2 with matching, and keeps constant distance between the surface of the bottom surface of convergence optical system 2 and wafer A.Viewing optical system 10 comprises autofocus mechanism.

Viewing optical system 10 comprises: electron gun 11, and it launches the semiconductor laser beam L ' of polarization linearly; First lens 12, it makes the semiconductor laser beam L ' that launches from electron gun 11 be collimated into parastate; The polarization beam apparatus 13 that is adjacent to arrange with first lens 12; Second lens 14, it is assembled the semiconductor laser beam L ' that sees through polarization beam apparatus 13; The 3rd lens 15, it makes the semiconductor laser beam L ' that is assembled by second lens 14 be collimated into parastate once more; Quarter wave plate 16, it will convert circularly polarized light to through the linearly polarized light of the semiconductor laser beam L ' of the 3rd lens 15; Dichronic mirror 17, the semiconductor laser beam L ' of its reflecting ﹠ transmitting quarter wave plate 16 makes the direction of its optical axis change 90 degree, and this light is incident on the convergence optical system 2; The 4th lens 19, it is being incident on the cylindrical lens 18 light that returns from convergence optical system 2 once more through quarter wave plate 16 and after by polarization beam apparatus 13 reflections; And the photodiode 20 that places the rear side of cylindrical lens 18.

Dichronic mirror 17 is arranged so that the light of its reflective semiconductor laser beam L ' and other wavelength of transmission, for example, from laser beam sources emitted laser bundle L.

For linearly polarized light, for example, polarization beam apparatus 13 transmissions are parallel to the linearly polarized light of the oscillating component P of the plane of incidence, and reflection is perpendicular to the light of the oscillating component S of the plane of incidence.Controller utilizes based on the feedback of detection signal (as the focus error signal that receives from photodiode 20) pedestal is controlled, and (optical axis direction) traveling platform vertically.That is, it serves as autofocus.Thus, semiconductor laser beam L ' is adjusted to all the time the lip-deep focus that is positioned at wafer A.

When the 2 couples of wafer A of laser convergence optical system that use this structure scan, from electron gun 11 illuminated line polarization semiconductor laser beam L '.First lens 12 make the semiconductor laser beam L ' that is shone parallel, and semiconductor laser beam L ' is incident on the polarization beam apparatus 13 then.The linear polarization oscillating component P that is parallel to the plane of incidence is assembled by second lens 14, disperses then.Make this diverging light parallel once more by the 3rd lens 15, this diverging light is incident on the quarter wave plate 16 then.At this moment, the width of parallel beam is corresponding to the width of convergence optical system 2.After seeing through quarter wave plate 16, semiconductor laser beam L ' becomes circularly polarized.It is reflected by dichronic mirror 17 and is incident on the convergence optical system 2 then.The bundle that is incident on the convergence optical system 2 shines on the surface of wafer A.

Subsequently, the light that reflects from the surface of wafer A is assembled by convergence optical system 2, by dichronic mirror 17 reflections, and is incident on the quarter wave plate 16, and this light becomes the oscillating component S perpendicular to the plane of incidence thus.These light transmission the 3rd lens 15 and second lens 14 are incident on the polarization beam apparatus 13, and to 19 reflections of the 4th lens.After being assembled by the 4th lens 19, it sees through cylindrical lens 18 and form image on photodiode 20.Formed image is converted into the detection signal such as focus error signal, and is sent to controller (step S5).Controller calculates (step S6) based on the detection signal that it receives, and vertically (optical axis direction) is moved further pedestal, makes the surface of the focus of semiconductor laser beam L ' and wafer A be complementary (step S7).That is, form the image on the surface of wafer A all the time by carrying out automatic focus.

Therefore, can when between the surface of convergence optical system 2 and wafer A, keeping constant distance all the time, carry out scanning.Therefore, even even some errors of mobile existence of pedestal slight curvature or pedestal also can be focused at laser beam L the degree of depth place of hope exactly.This makes and can scan laser beam L when the converged position on the surface of distance wafer A is controlled more accurately, and makes and can carry out laser treatment more accurately.

When in scanning process, having changed the position that laser beam L assembled, after the side-play amount of having calculated autofocus, carry out scanning (step S8).For example, scan when laser beam L assembles the degree of depth place of 50 μ m if scan then when laser beam L is focused at the degree of depth place of 100 μ m, except that mobile laser divergence point, also WD must be changed to perfect condition, that is, it is set to ideal value.When changing this WD value, must make autofocus skew scheduled volume.In other words, proofread and correct the WD value by the skew of calculating autofocus.After having carried out skew, carry out scanning as described above at the different depth place.

Subsequently, with reference to Fig. 6 and Fig. 7 the convergence optical system according to third embodiment of the invention is described.In the 3rd embodiment, by identical label represent with first embodiment in the identical element of element, these elements of not repeat specification.

The difference of the 3rd embodiment and first embodiment is: in first embodiment, relative distance along optical axis direction between the surface of convergence optical system 2 and wafer A (that is is not constant WD), in contrast,, in the 3rd embodiment, WD is constant.

That is, preestablish pedestal and the position of convergence optical system 2 on optical axis direction, hold them in then on the identical position.As shown in Figure 6, from the various data (above step S1) that input to input block, got rid of the WD value, that is, the input data include only the refractive index of wafer A, from the surface of wafer A to the NA of distance of wishing converged position and convergence optical system 2.

As shown in Figure 7, when keeping constant WD, laser divergence point mobile unit 4 is along the only mobile laser divergence point 3 of optical axis direction.This makes can come correcting spherical aberration by simpler structure.

Subsequently, describe with reference to Fig. 8 and 9 pairs of convergence optical systems according to fourth embodiment of the invention.In the 4th embodiment, by identical label represent with second embodiment in the identical element of element, these elements of not repeat specification.

The difference of the 4th embodiment and second embodiment is: in a second embodiment, relative distance along optical axis direction between the surface of convergence optical system 2 and wafer A (that is is not constant WD), in contrast,, in the 4th embodiment, WD is constant.

As shown in Figure 8, the convergence optical system 2 of present embodiment can scan when being offset according to constant WD by the mode identical with the 3rd embodiment.Therefore, as shown in Figure 9,, be offset the required time so can shorten, thereby improved treating capacity owing to after initially having set autofocus, do not need to recomputate its skew.

In addition, can also reduce deterioration owing to the precision that is offset the autofocus that causes.

Technical scope of the present invention is not limited to above-mentioned a plurality of embodiment, can carry out various modifications under the situation that does not break away from spirit of the present invention.

For example, although in above each embodiment, laser beam is focused in the wafer, its structure is not limited to wafer, and can be with beam convergence in medium.Focusing distance apart from the surface of wafer is not limited to aforesaid 50 μ m, 75 μ m and 100 μ m, but it can at random be set.Although change between the surface of convergence optical system and wafer along the relative distance of optical axis direction by traveling platform, the present invention is not limited to this structure.For example, can use piezoelectric element to wait the mobile convergence optical system, to change this relative distance.

Although controller is described as laser divergence point mobile unit is controlled automatically, can change the position of laser divergence point based on the result of calculation that obtains by controller by mobile laser divergence point mobile unit.

The viewing optical system of describing in the 3rd embodiment only is an example, and, just can accept combination as long as can keep to the distance on the surface of wafer such as any optical system of lens from the bottom surface of convergence optical system.

Below, describe with reference to Figure 10 and 11 pairs of laser treatment optical systems according to fifth embodiment of the invention.

As shown in figure 10, the laser machining device 101 of present embodiment comprises: unshowned lasing light emitter, its emission laser beam L; By the collimation unit that unshowned lens etc. are formed, it makes from laser beam sources emitted laser bundle L and is collimated into parallel rays; Convergence optical system 103, it comprises that the parallel rays that will restraint L is focused at the object lens 102 in the medium; First lens (first set of lenses) 104, it is arranged in the parallel rays that collimates between unit and the object lens 102, and can move along the optical axis direction of parallel rays; Second lens (second set of lenses) 105, it is fixed in the parallel rays between first set of lenses 104 and the object lens 102; Mobile unit 106, its according to the refractive index of wafer (medium) A that will converge to laser beam L and from the surface of wafer A to the distance of assembling the position, move first set of lenses 104; And the viewing optical system 107 that is provided with convergence optical system 103, it keeps from the bottom surface of object lens 102 to the constant distance on the surface of wafer A. with matching

Point out that in passing wafer A is installed on the unshowned pedestal that can move along the XY direction.

First lens 104 are made up of the biconcave lens that is fixed in unshowned lens frame.Mobile unit 106 is connected to this lens frame, and can move first lens 104 by this lens frame.Mobile unit 106 is also connected to unshowned controller, and operates based on the signal that receives from this controller.

Controller comprises the input block that can import predetermined information to it, with based on the input information that is input to this input block (input data) to the calculator that the amount of movement of first lens 104 calculates, according to the result who is calculated mobile unit 106 is moved scheduled volume.Except mobile unit 106 was controlled, controller was also controlled laser beam sources simultaneously, made it move first lens 104 transmitted beam L afterwards.

Second lens 105 are convex lens, and its planar side is to first lens, 104 sides, that is, its convex side is in the face of object lens 102, and the rear side focal position that is arranged such that it be positioned at least object lens 102 the entrance pupil position near.

Viewing optical system 107 comprises: electron gun 110, and it shines the semiconductor laser beam L ' of polarization linearly; First lens 111, it makes from the semiconductor laser beam L ' of electron gun 110 irradiations and is collimated into parastate; The polarization beam apparatus 112 that is adjacent to arrange with first lens 111; Second lens 113, it is assembled the semiconductor laser beam L ' that sees through polarization beam apparatus 112; The 3rd lens 114, it makes the semiconductor laser beam L ' that is assembled by second lens 113 be collimated into parastate once more; Quarter wave plate 115, it will convert circularly polarized light to through the linearly polarized light of the semiconductor laser beam L ' of the 3rd lens 114; Dichronic mirror 116, the semiconductor laser beam L ' of its reflecting ﹠ transmitting quarter wave plate 115 makes the direction of its optical axis change 90 degree, and this light is incident on the object lens 102; The 4th lens 118, it is being incident on the cylindrical lens 117 light that returns from object lens 102 once more through quarter wave plate 115 and after by polarization beam apparatus 112 reflections; And the photodiode 119 that places the rear side of cylindrical lens 117.

Dichronic mirror 116 is arranged so that the light of its reflective semiconductor laser beam L ' and other wavelength of transmission, as from laser beam sources emitted laser bundle L.

For linearly polarized light, for example, polarization beam apparatus 112 transmissions are parallel to the linearly polarized light of the oscillating component P of the plane of incidence, and reflection is perpendicular to the light of the oscillating component S of the plane of incidence.Controller utilizes based on the feedback of detection signal (as the focus error signal that receives from photodiode 119) pedestal is controlled, and (optical axis direction) traveling platform vertically.That is, it serves as autofocus.Therefore, semiconductor laser beam L ' is adjusted to all the time the lip-deep focus place that is positioned at wafer A.

The following describes laser processing system 101 that use constitutes as described above will restraint L and be focused at apart from the example at the different depth place on the surface of wafer A.

As shown in figure 11, the refractive index of the wafer A that records in advance to the input of the input block of controller, to the distance of wishing converged position (for example from the surface of wafer A, 50 μ m), the distance on the NA of object lens 102, the surface from object lens 102 to wafer A (that is, WD) and the wave front data (step S1A) relevant with object lens 102.Based on these input data, calculator calculates (step S2A) to the amount of movement of first lens 104.After having carried out this calculating, based on the result who is calculated, controller is controlled mobile unit 106, thereby moves mobile unit 106 along the optical axis direction of bundle L, so that first lens 104 are moved to precalculated position (step S3A).

After having moved first lens 104, controller sends signal and makes its transmitted beam L (step S4) to laser beam sources.The collimated cell translation of bundle L of being launched becomes parastate, and is incident on first lens 104.Laser beam L is by the refraction of first lens 104, and becomes before being incident on second lens 105 and disperse.That is, changed the divergence point position of bundle L on optical axis direction by moving first lens 104.The divergent rays of bundle L by 105 refractions of second lens, is incident on the object lens 102 once more, and the hope degree of depth (50 μ m) that is focused at then apart from the surface of wafer A is located.

As mentioned above, because according to wishing that the degree of depth regulates the position of divergence point by the position of moving first lens 104 along optical axis direction, thus can suppress the amount of spherical aberration that produced significantly, and laser beam L can be focused at effectively the position of hope.

In the time will restrainting L and be focused at the position different (that is, different degree of depth places), comprise apart from the data of the new distance on the surface of wafer A to the input block input by mode same as described above with above-mentioned converged position.Based on the result that calculator calculates, controller is operated mobile unit 106 and along optical axis direction first lens 104 is moved to reposition.Therefore, the light of bundle L reflects in the position different with above-mentioned position, and disperses before being incident on second lens 105.Even first lens 104 have moved along optical axis, as long as be constant apart from the distance that is incident on the optical axis of the light on first lens 104, the angle (q) of light after seeing through first lens 104 just can not change (they keeping parallelisms).The angle of laser beam L does not change the some place (be bound to by this point) of ray convergence on the rear side focal plane of second lens (second set of lenses) of (parallel).Owing to become to make them to be complementary with the entrance pupil location arrangements of convergence optical system 103 the rear side focal position of second lens 105, so position regardless of first lens 104, the parallel rays that is incident on first lens 104 can have identical diameter in the entrance pupil position of convergence optical system 103 all the time, and can assemble in convergence optical system 103 and can not fog.Can not change owing to be incident on the diameter of the light on the convergence optical system 103, so can suppress the general issues of the Strength Changes and the intensity distribution variation on the pupil plane of converged position.

When laser beam L was focused among the wafer A, energy was focused at a point (convergent point) and locates and produce the crack.Particularly, owing to can when suppressing spherical aberration significantly, laser beam L be focused at the position of different depth, can produce the crack in the position of hope exactly.By when laser beam L is focused at the desired depth place, pedestal is carried out horizontal sweep and carries out laser treatment, adjacent crack can be coupled together, wafer A is cut into given size, for example, sheet.

Particularly, because present embodiment comprises communication interface 107, so execution scans when can keep constant distance between the surface of the apical pore (top punch) of object lens 102 and bottom outlet (bottom punch) and wafer A.

In scanning process, electron gun line of departure polarization semiconductor laser beam L '.The semiconductor laser beam L ' that is launched is collimated into parastate by first lens 111, and is incident on the polarization beam apparatus 112.The linear polarization oscillating component P that is parallel to the plane of incidence is assembled by second lens 113, then disperses.The 3rd lens 114 make this diverging light parallel once more, and this light is incident on the quarter wave plate 115 then.At this moment, the width of this collimatied beam is corresponding to object lens 102.After seeing through quarter wave plate 115, semiconductor laser beam L ' becomes circularly polarized.It is reflected by dichronic mirror 116 and is incident on the object lens 102 then.The bundle that is incident on the object lens 102 shines on the surface of wafer A.

Subsequently, the light that reflects from the surface of wafer A is assembled by object lens 102, by dichronic mirror 116 reflections, is incident on then on the quarter wave plate 115, and this light becomes the oscillating component S perpendicular to the plane of incidence thus.These light transmission the 3rd lens 114 and second lens 113 are incident on the polarization beam apparatus 112, and to 118 reflections of the 4th lens.After being assembled by the 4th lens 118, it sees through cylindrical lens 117 and form image on photodiode 119.The light that forms this image is converted into the detection signal such as focus error signal, and is sent to controller (step S5A).Controller is carried out based on the skew that is calculated by calculator and detection signal and is calculated (step S6A), and vertically (optical axis direction) is moved further pedestal, makes the surface of the focus of semiconductor laser beam L ' and wafer A be complementary (step S7).That is, be controlled at the distance between the surface of convergence optical system 103 and wafer A by automatic focus, it is constant to make it remain.

Therefore, can when between the surface of object lens 102 and wafer A, keeping constant distance all the time, carry out scanning to laser beam L.Therefore, even even some errors of mobile existence of pedestal slight curvature or pedestal also can be focused at laser beam L the degree of depth place of hope exactly.This makes and can scan when the converged position on the surface of distance wafer A is controlled more accurately, can carry out laser treatment more accurately thus.

When in scanning process, having changed the position of laser beam L convergence, carry out scanning afterwards in the side-play amount of having calculated autofocus (step S8).For example, scan, except that mobile laser divergence point, also WD must be arranged to ideal value if when laser beam L is focused at the degree of depth place of 100 μ m, scan when laser beam L then is focused at the degree of depth place of 50 μ m.When changing this WD value, must make autofocus skew scheduled volume.In other words, proofread and correct the WD value by the skew of calculating autofocus.After having carried out skew, carry out scanning as described above at the different depth place.

Subsequently, with reference to Figure 12 the laser machining device according to sixth embodiment of the invention is described.In the 6th embodiment, by identical label represent with the 5th embodiment in the identical element of element, these elements of not repeat specification.

The difference of the 6th embodiment and the 5th embodiment is: in the 5th embodiment, the relative distance along optical axis direction between the surface of object lens 102 and wafer A (that is be not constant WD), and in the 6th embodiment, WD is constant.

That is, preestablish pedestal and the position of object lens 102 on optical axis direction, then they are remained on the identical position.Therefore, as shown in figure 12,, be offset the required time, to improve treating capacity so can shorten owing to after initially having set autofocus, needn't recomputate its skew.

Subsequently, with reference to Figure 13 the laser machining device according to seventh embodiment of the invention is described.In the 7th embodiment, by identical label represent with the 5th embodiment in the identical element of element, these elements of not repeat specification.

The difference of the 7th embodiment and the 5th embodiment is: in the 5th embodiment, first lens 104 comprise biconcave lens, and in the laser machining device of the 7th embodiment, first lens 104 are convex lens, and the planar side that is arranged such that it is to second lens, 105 sides.

In the present embodiment, with the same in the 5th embodiment, regardless of the position of first lens 104, the parallel rays of incident beam reflected by identical state before being incident on second lens 105 all the time.Therefore the laser machining device of present embodiment realized with the 5th embodiment in identical effect.

Subsequently, with reference to Figure 14 the optical system according to eighth embodiment of the invention is described.In the 8th embodiment, by identical label represent with the 7th embodiment in the identical element of element, these elements of not repeat specification.

The difference of the 8th embodiment and the 7th embodiment is: in the 7th embodiment, second set of lenses is made up of single concavees lens (that is, second lens 105), and in the 8th embodiment, second set of lenses 120 is made up of two

lens

121 and 122.

As shown in figure 14, second set of lenses 120 of present embodiment comprises the biconcave lens 121 that is arranged in first set of lenses (first lens 104) side and arranges adjacent to the biconvex lens 122 of this biconcave lens 121.The rear side focal position of whole second set of lenses 120 be positioned at object lens 102 the entrance pupil position near.

The laser machining device of present embodiment can obtain with the 7th embodiment in identical effect.In addition, can increase the interval (distance) between second set of lenses 120 and the object lens 102, make and between them, to arrange another observing system etc., thereby increase the free degree of design.

Subsequently, with reference to Figure 15 the optical system according to ninth embodiment of the invention is described.In the 9th embodiment, by identical label represent with the 5th embodiment in the identical element of element, these elements of not repeat specification.

The difference of the 9th embodiment and the 5th embodiment is: in the 5th embodiment, first set of lenses comprises single biconcave lens (that is, first lens 104), and first set of lenses 125 of the 9th embodiment comprises two

lens

126 and 127.

That is, as shown in figure 15, first set of lenses 125 of present embodiment is made up of following lens: convex lens 126, and its protuberance that is arranged such that it is in the face of laser beam sources and collimation cell side; With biconcave lens 127, it is positioned to adjacent to convex lens 126.Second set of lenses of present embodiment is made up of a biconvex lens 128.

In the present embodiment, with the same in the 5th embodiment, regardless of the position of first set of lenses 125, the parallel rays of incident beam reflected by identical state before being incident on second lens 128 all the time.

Therefore the laser machining device of present embodiment obtained with the 5th embodiment in identical effect.

Should be understood that the present invention is not limited to above-mentioned the 5th embodiment to the nine embodiment, and can under the situation that does not break away from the spirit or scope of the present invention, carry out various modifications.For example, first set of lenses and second set of lenses can be as being made up of single lens among the 5th embodiment, perhaps as being made up of above lens among the 7th and the 8th embodiment.Lens type is not limited to for example convex lens, concavees lens or biconvex lens, and can make up freely and design.

Particularly, in the 5th embodiment to the nine embodiment, mobile unit 106 should be arranged to first set of lenses is moved, make and satisfy following formula:

1/|f|<0.01

Wherein | f| is the combined focal length of first set of lenses and second set of lenses.This makes and can add burnt section far away.

In the 5th embodiment to the nine embodiment, second set of lenses should be arranged to satisfy following formula.

f2>0

Wherein f2 is the focal length of second set of lenses.

The entrance pupil position of convergence optical system is inner at convergence optical system itself usually.Even the entrance pupil position of convergence optical system 103 in this optical system inside, also can make the position of rear side focus of second set of lenses and the entrance pupil position of convergence optical system 103 be complementary.

In the 5th embodiment to the nine embodiment, first set of lenses and second set of lenses should be arranged so that their satisfied following formula:

f1<0

And 1≤| f2/f1|≤5

Wherein f1 is the focal length of first set of lenses, and f2 is the focal length of second set of lenses.

By first set of lenses being given negative refractive power (concavees lens), and give positive refractive power (convex lens), can make more compact structure second set of lenses.In addition, because 1≤f2/f1, so can simplify the structure of first set of lenses.This not only makes it not expensive, and has suppressed performance degradation.In addition, because f2/f1≤5, so can design this optical system compactly.

To the setting of first set of lenses and second set of lenses be not limited to aforesaid f1＜0 and 1≤| f2/f1|≤5.For example, in the 5th embodiment to the nine embodiment, they can be arranged to satisfy following formula:

f1>0

And 0.5≤| f1/f2|≤2

This makes that the focal length of two set of lenses all can be positive, simplifies the structure and has realized the relaying of multiplication factors such as approaching.

Although in the 5th embodiment to the nine embodiment, controller is controlled automatically to mobile unit, can operate feasible position of moving first set of lenses to mobile unit based on the calculating of being undertaken by controller.

Optical system of the present invention can be incorporated into all aberration correction optical systems 140 as shown in figure 16, and use it for correcting spherical aberration.140 couples of laser beam L from unshowned electron gun of aberration correction optical system assemble, and comprise a plurality of lens 141,142 and 143, these lens ad hoc can be inserted on the light path or from light path and remove, and they satisfy following formula:

2(d ²+l×f-l×d)NA＝f×a

Wherein, d is to the distance of a plurality of lens 141,142 and 143 from the entrance pupil position of the convergence optical system 103 that comprises object lens 102, l is to the distance of beam source position from the entrance pupil position of convergence optical system 103, f is the focal length of described a plurality of lens 141,142 and 143, NA is the NA (NA that sees from convergent lens) of electron gun, and a is the entrance pupil diameter of convergence optical system 103.Light is dispersed, and described a plurality of lens 141,142 and 143 are convex lens.

In the aberration correction optical system 140 of this structure, disperse the part that electron gun is observed the different depth place among (convergence) wafer A even attempt to use, also can when suppressing the amount of spherical aberration that produces with constant intensity on the pupil plane and constant intensity distribution, carry out and observe (convergence).In addition, needn't carry out following routine operation: as the object lens of a plurality of costlinesses object lens of corrector loop (as have) are combined, and change glass with different-thickness.

Although aberration correction optical system 140 shown in Figure 16 is arranged in described a plurality of lens 141,142 and 143 in the divergent rays, instead also described a plurality of lens 141,142 and 143 can be arranged in the converging ray as illustrated in fig. 17.In the case, described a plurality of lens 141,142 and 143 should be concavees lens.

Can as illustrated in fig. 18 described a plurality of concavees lens 141,142 and 143 be arranged in the parallel rays.

In addition, as shown in figure 19, described a plurality of concavees lens 141,142 and 143 can be arranged in after the convex lens, these convex lens temporarily convert parallel rays to divergent rays.

Although in the 5th to the 9th embodiment, laser beam is focused in the wafer, the present invention is not limited to this, and can be with beam convergence in medium.Focusing distance apart from the surface of wafer is not limited to aforesaid 50 μ m, 75 μ m and 100 μ m, and it can at random be set.Although change by traveling platform between the surface of convergence optical system and wafer along the relative distance of optical axis direction, the present invention is not limited to this structure.For example, can wait mobile object lens by using piezoelectric element, to change this relative distance.

In addition, the viewing optical system of describing in the 5th embodiment only is an example, and, just the various optical systems such as lens can be combined to the constant distance on the surface of wafer as long as can keep from the bottom surface of object lens.

The present invention also comprises following remarks:

[remarks 1]

A kind of laser machining device, it comprises:

Laser beam sources, it launches laser beam;

The collimation unit, it will be collimated into parallel rays from the light of described laser beam sources emitted laser bundle;

Convergence optical system, it is focused at described parallel rays in the medium;

First set of lenses, it is arranged in the parallel rays between described collimation unit and the described convergence optical system, and can move along the optical axis direction of described parallel rays, and first set of lenses comprises one or more lens;

Second set of lenses, it is fixedly placed in the parallel rays between first set of lenses and the described convergence optical system, and comprises one or more lens; And

Mobile unit, it converges to the refractive index of described medium wherein according to hope with described laser beam and the distance of the converged position that described laser beam converged to hope from the surface of described medium, moves first set of lenses, wherein

The rear side focal length of second set of lenses be arranged at least described convergence optical system the entrance pupil position near.

[remarks 2]

According to remarks 1 described laser machining device, also comprise:

Viewing optical system is provided with described convergence optical system with matching, and keeps from the bottom surface of described convergence optical system to the constant distance on the surface of described medium, wherein

Described viewing optical system comprises focus detection unit or autofocus mechanism.

[remarks 3]

According to

remarks

1 or 2 described laser machining devices, wherein

Relative distance between the surface of described convergence optical system and described medium is constant.

[remarks 4]

According to a described laser machining device in the remarks 1 to 3, wherein

When | when f| was the combined focal length of first set of lenses and second set of lenses, described mobile unit moved to first set of lenses position of satisfying following formula:

1/|f|<0.01

[remarks 5]

According to a described laser machining device in the remarks 1 to 4, wherein

When f2 was the focal length of second set of lenses, second set of lenses satisfied following formula:

f2>0

[remarks 6]

According to a described laser machining device in the remarks 1 to 5, wherein

When f1 is the focal length of first set of lenses and f2 when being the focal length of second set of lenses, first set of lenses and second set of lenses satisfy following formula:

f1<0

And 1≤| f1/f2|≤5

[remarks 7]

According to a described laser machining device in the remarks 1 to 5, wherein

f1>0

And 0.5≤| f1/f2|≤2

[remarks 8]

A kind of laser machining device, it comprises:

Laser beam sources, it launches laser beam;

Convergence optical system, it is focused at described laser beam in the medium; And

The laser convergence optical system, wherein, described laser beam is converged to the refractive index of described medium wherein and the distance of the converged position that described laser beam converged to hope from the surface of described medium according to hope, a plurality of lens that satisfy following formula ad hoc is inserted on the light path of the divergent rays of described convergence optical system and/or converging ray or and removes from this light path:

2(d ²+l×f-l×d)NA＝f×a

F is the focal length of described a plurality of lens,

A is the entrance pupil diameter of described convergence optical system.

[remarks 9]

A kind of laser machining device, it comprises:

Laser beam sources, its emission is parallel to the laser beam of optical axis;

Optical system, it is focused at described laser beam in the medium; And

The laser convergence optical system, wherein, according to hope described laser beam is converged to the refractive index of described medium wherein and from the surface of described medium to the distance of the position that hope converges to described laser beam, a plurality of lens that satisfy following formula are ad hoc inserted in the described laser beam or from described laser beam remove:

b(f-d)/f＝a

Wherein, b is the diameter from the collimatied beam of described electron gun,

F is the focal length of described a plurality of lens, and

A is the entrance pupil diameter of described convergence optical system.

According to laser convergence optical system of the present invention, laser divergence point mobile unit according to hope with beam convergence to the refractive index of wherein medium and from the surface of medium to the distance of assembling the position, optical axis along laser beam moves the laser divergence point, thus the amount of spherical aberration that the feasible position that can be suppressed at the different depth of medium significantly produces.Therefore, laser beam can be focused at effectively the hope degree of depth place in the medium, and can strengthen the convergence performance.

Particularly, because mobile laser divergence point only, so the generation of correcting spherical aberration easily, and be unlike in the usual manner consuming time like that.In addition, because this structure does not need the special optical system, so designs simplification is reduced cost simultaneously.

According to the laser machining device that comprises above-mentioned laser convergence optical system,, suppress the generation of spherical aberration significantly simultaneously, so can carry out laser treatment exactly owing to the different depth place that laser beam can be focused at effectively in the medium.

According to the first aspect of laser machining device of the present invention to the third aspect, because can be by beam convergence being moved first set of lenses to the refractive index of wherein medium and the distance from the surface of medium to the convergence position according to hope, change be incident on the laser beam on second set of lenses the position (promptly, the position of the electron gun of seeing from convergence optical system), so laser beam can be focused at the converged position place, be suppressed at the amount of spherical aberration that this position produces simultaneously significantly.Therefore, can accurately carry out laser treatment.

In addition, the rear side focal length of second set of lenses and the entrance pupil position of convergence optical system are complementary, the diameter that is incident on the light on the entrance pupil of convergence optical system thus can not change, and makes incident light intensity on the pupil plane and intensity distributions to be kept constant.Therefore, can suppress to assemble changes of properties.

In addition, owing to only just can change beam source position by moving first set of lenses, thus can make designs simplification, and correcting spherical aberration and not consuming time easily.

The application is incorporated into this with its content by reference based on TOHKEMY 2004-132995 number and 2004-132997 number.

Claims

1, a kind of laser machining device, it comprises:

Laser beam sources, it launches laser beam;

Convergence optical system, its described parallel rays with described laser beam is focused in the medium;

Mobile unit, its according to hope described laser beam is converged to the refractive index of described medium wherein and from the surface of described medium to the distance of the position that hope converges to described laser beam, move first set of lenses, wherein

2, laser machining device according to claim 1 also comprises:

Viewing optical system is provided with described convergence optical system with matching, and keeps from the bottom surface of described convergence optical system to the preset distance on the surface of described medium, wherein

Described viewing optical system comprises automatic focus detecting unit or autofocus mechanism.

3, laser machining device according to claim 2, wherein

Relative distance along optical axis direction between the surface of described convergence optical system and described medium is constant.

4, laser machining device according to claim 1, wherein

1/|f|<0.01。

5, laser machining device according to claim 1, wherein

f2>0。

6, laser machining device according to claim 1, wherein

When f1 is the focal length of first set of lenses, and f2 is when being the focal length of second set of lenses, and first set of lenses and second set of lenses satisfy following formula:

f1<0，

And 1≤| f1/f2|≤5.

7, laser machining device according to claim 1, wherein

f1>0，

And 0.5≤| f1/f2|≤2.