Device for regulating quantity of light

[Detailed Description of the Invention]

It carries out and is industrial use field Co. those with The which require the present invention for the light volume adjustment device of the device using the light source which carries out pulse radiation, and a metaphor are related with the suitable light volume adjustment device for the exposure device which projects the mask pattern to a semiconductor wafer top using an excimer laser.

[Description of the Prior Art] Conventionally, in the reduction projection type exposure device used like integrated circuit manufacture paste Sogererahye, and what is called a stepper, it is used in the ultra-high pressure mercury lamp as a light source for exposure. Although this ultra-high pressure mercury lamp outputs the light of a plurality of wavelengths, as for the wavelength of the light used with improvement in the resolution needed for lithography, light with a wavelength of 365 nm is also increasingly used without Take care with a wavelength of 436 nm in short Nuclear. On the wavelength not more than a place and this, only the quantity of the Energy- or the lithography with a very low throughput which becomes small is realizable. As that with which such a problem is compensated, it is A Lord carried out in the excimer laser these days. if an excimer laser is used -- the wavelength of 308 nm, and 249 nm The, such as 193 nm, -- a strong light is obtained and this is made. This laser is time width 10 thru/or 20 n5ec, and the shape of a pulse has character in which an oscillation output is carried out. Drawing 2 is made to carry out the fixed partition repetition oscillation of the excimer laser mostly in the conventional exposure device, and the case where open and close a shutter and a light exposure is controlled is shown in it. First, as the output of an excimer laser is shown in the figure (8), a metaphor is outputted with a constant period in the shape of a pulse. On the other hand, opening and closing of a shutter take fixed time. For this reason, it is E about the amount of energy of the pulse which passes a shutter in the state where it opened completely. If carrying out it, as for the passage amount of energy in the middle of shutter opening and closing, below Eo will become. It borrows from time T1 at time T2, Opening operation of a shutter is performed in the Drawing CB, and the shutter penetration pulse in closed operation of a shutter or the case of being carried out is shown in it from time T3 to time T4. In this figure, the total amount of energy of the pulse which passes a shutter during a series of opening-and-closing operations becomes the sum of the energy (product of pulse width and light intensity) of each pulse. It is shown in the figure (C) from time t1 to time t2 in Opening operation of a shutter, or the shutter penetration pulse in the case of being carried out and carried out in closed operation of a shutter from time t3 to time t4. This example differs delta in the time of opening Start of work as compared with the case of the figure (B). The figure (D) displays the graph of the above (B) and (C) in piles.

In the method of [Problem(s) to be Solved by the Invention], however the light volume control by the above shutter opening and closing, since there are few pulses contained in within a time [ of shutter Open ], there is inconvenience that light volume control cannot be performed satisfactorily. Reference of Drawing 2 (D) will change clearly the total light volume which passes a shutter by the slight difference of the timing of a standup. If it explains in full detail, the difference of the light volume of deltaP1 will produce the very first pulse P1 The that passes a shutter. Similarly, at second pulse P2, raw is carried out and it is [ the spectacle difference of deltaP2, or ] To. The same may be said of the time of closed operation of a shutter. Therefore, light volume difference deltaP as the whole is set to delta P=delta P1+deltaP2+deltaP3-deltaP4-deltaP5-deltaP6. As mentioned above, it is E about appearance crab Nel key per pulse temporarily. Even if it controls uniformly, the inconvenience that shutter passage energy shows variation arises by gap of a pulse output and the timing of shutter opening and closing. The present invention is made in view of this point, and sets it as the purpose to provide the light volume adjustment device which can control To deal and the good light volume of good reproducibility to the temporal response of a lightwave pulse and shutter operation.

[Means for Solving the Problem] A thing which is characterized by that the present invention comprises the following and which is made into the technical main point. Output capability of a pulsed light source, Addition light volume which a subject needs, A calculating means which determines timing of a Optical path closed operation start of the shutter means while determining light volume per pulse with which the subject is irradiated based on the opening-and-closing operating characteristic of a shutter means, The first control means that performs light volume control of each pulse according to light volume per [ which was determined ] pulse, and the second control means that performs Optical path closed motion control of a shutter means synchronizing with luminescence timing of the pulsed light source based on timing of the determined Optical path closed operation start. If an example of basic composition of this invention is shown notionally, it will become as it is shown in Drawing 1, for example. A lightwave pulse outputted from pulsed light source BA penetrates shutter means BB, and subject BC is irradiated with it. On the other hand, an operation result of calculating means BD is connected so that human power may be respectively carried out to the first and second control means BE and BF. The first control means BE has the function to perform light volume control of each pulse based on human power. The second control means BF has the function to perform closed motion control of shutter means BB synchronizing with luminescence timing of pulsed light source BA, based on human power.

[Function] In this invention, the Optical path closed operation timing of the output timing of a lightwave pulse and a shutter means is synchronized, and it is carried out in Optical path closed operation of the shutter means. the light volume per pulse with which subject BC is first irradiated in the device of Drawing 1 based on the output capability of pulsed light source BA, the light volume (proper light exposure) which subject BC needs, and the operating characteristic of shutter means BB, and the timing of a closed operation start of shutter means BB -- it is determined respectively. On the other hand, the pulse outputs of pulsed light source BA are after Opening operation of shutter means BB, and suitable timing To be done. Human power of the light volume per [ which was determined / above-mentioned ] pulse is carried out to the first control means BE. And it is controlled by this first control means BE in the light volume of each lightwave pulse with which subject BC is irradiated. On the other hand, the timing of a closed operation start is inputted into the second control means BF. And closed operation of shutter means BB is controlled by this second control means BF. The above amounts of pulsed light and the light volume with which subject BC is irradiated by control of shutter closed operation are adjusted to necessary quantity.

[Example] Hereinafter, the example of the present invention is described in detail, referring to an accompanying drawing. It is shown in Drawing 3 in the composition of one example of this invention. In this figure, laser light source 10 is a light source which emits light in the shape of [ whose metaphor is / like an excimer laser ] a pulse. This laser beam '# and the output pulse of 10 penetrate first illumination-light study system 12, and enter into shutter 14. This first illumination-light study system 12 has a function which transforms the inputted pulse laser beam so that it may become required beam section intensity distribution and the emission (or Astigmatism) characteristic, and is outputted to shutter 14. As for shutter 14, the rotation control drive of opening and closing is performed, for example in the direction of arrow FA of a figure by shutter driver 16. The example of the temporal response of opening-and-closing operation of this shutter 14 is shown in Drawing 4 (8). In this figure, a horizontal axis expresses time and a vertical axis expresses the grade of an opened state. Kai's instructions are performed at time TA, it is started in Opening operation from time TB, a laser beam bunch begins to penetrate, it will be in the state of full open at time TC, and a laser beam bunch will pass completely. Instructions of Closed are performed at time TD, closed operation is started from time TE, shutter 14 begins to start a laser beam bunch, it will be in the state of perfect Closed at time TF, and a laser beam bunch will be intercepted completely. Delay time ta after Open command is performed in opening-and-closing operation of the above shutters 14 until Opening operation is started, The end from time tb of Until which becomes full open from Open command, delay time td from closed instructions to a closed operation start, and closed instructions -- time te of Until which becomes fully closed -- this example -- as the characteristic on an equipment configuration -- oh -- a Azalea decision is made -- Hub -- it is fixed. Time tc is the time of opening End of work to closed operation start Until. Next, the pulsed light which passed this shutter 14 penetrates second illumination-light study system 18, and enters into Reticle R. This second illumination-light study system 18 has a uniform function made for With intensity distribution ON to put for incidence Bals heme only to the required circuit pattern field on Reticle R. It has an optical integrator, a capacitor lens, etc. which make the optical system and a plurality of secondary light source images for reducing a speckle peculiar to a laser beam especially. It is formed in ReticleR in the circuit pattern which should be projected on wafer W. The pulsed light which penetrated Reticle R, i.e., exposure light, enters into wafer W via projection optical system 20, and it is performed in projection of the circuit pattern of Reticle R. Next, it is connected to laser light source 10 mentioned above in control exposure 22. Shutter control part 24 is connected between this control exposure 22 and shutter driver 16 mentioned above. Considerable in the bottom, human power is respectively carried out to control exposure 22 in light exposure signal S dose from an external host computer (not shown) etc. among more than at exposure start signal 5exp and a proper light exposure. While this control exposure 22 outputs energy command signal Se and luminescence trigger signal St to laser light source 10 based on exposure start signal S exp by which human power is carried out, and a light exposure signal S dose signal, It has a function which outputs the number signal Sn of pulses to shutter control part 24 with luminescence Tori Karr signal St. Energy command signal Se sets up the amount of energy per pulse among these signals. Luminescence trigger signal St directs the luminescence timing of laser light source 10. Next, the number signal Sn of pulses shows the number of pulses passed in the state of shutter 14 full open. Next, luminescence trigger signal St with which human power of the shutter control part 24 was carried out, Based on the information (refer to Drawing 4 (A)) about the number signal Sn of pulses, and the opening-and-closing time of shutter 14, it has a function which outputs driving control signal Ss for performing drive control of shutter 14 by shutter driver 16. Open command and closed instructions are included in this driving control signal Ss. next, One ~ explains [ inside ] to overall operation of the above-mentioned example with reference to flow Chart of Drawing 5. As shown in Drawing 4 (B), output control of the laser pulse of laser light source 10 shall be carried out by TP at a constant interval [ Hub ] after Opening operation of shutter 14. the relation between I will, opening-and-closing operation of shutter 14 shown in Drawing 4 (A), and the output timing of the laser pulse shown in the Drawing CB is explained. The end from time ta as mentioned above, after the time interval of opening-and-closing operation of shutter 14, i.e., Open command, is performed until it is started in Opening operation, time tb until it becomes full open from Open command, time td from closed instructions to a closed operation start, and closed instructions -- time te of Until which becomes fully closed is about 1 law. On the other hand, instructions of shutter opening and closing can be performed to arbitrary timing. Therefore, it is Be able to to define the timing of closed instruction time TD so that a laser pulse may be outputted in time t=TC, the timing of Open command time TA may be defined and a laser pulse may be outputted in time t=TE. By the way, the exposure amount of energy which enters into the Lesys 1~layer on wafer W from an exposure start to an end is proportional to the amount of energy addition which passed shutter 14. Therefore, control To is made [ controlling a light exposure / as opposed to the regist layer on wafer W for the addition amount of energy which passes shutter 14 /, or ]. First, as mentioned above, the light exposure with which the regist layer on wafer W should be irradiated is directed from an external device by light exposure signal S dose (refer to 5th [ The ] figure step 100). It is specified in addition amount-of-energy E does of shutter 14 passage by this light exposure signal S dose. When addition amount-of-energy E dose is given as for this light exposure signal S dose and another To say, the following operations are performed and control exposure 22 The is energy JtE per Lou Sabah Luce. And the total number of exposure pulses is determined (refer to Step 102). In Drawing 4 of the above, a detailed explanation will set [ the number of pulses to TB<t<TC ] the number of pulses of 02 TE<t<TF Until to n3 for the number of pulses of nI TC<t<TE Until. First, in pulse repetition interval TP and each pulse, it is stable, and is determined and fixed under the conditions from which the energy more than needed is obtained. Next, if it is made to perform a pulse output according to Opening operation of shutter 14 mentioned above, it will be determined in 01 pulses. Next, since the inclination at the time of Opening operation and closed operation is respectively constant, rl and r7 are made into a constant, and as for addition energy E1 of TB<t<TC, addition energy E2 of TC<t<TE is E2=l'12Eo. ..................... (2) It becomes addition energy E3 of TE<t<TF. Therefore, E dose= E+ +E 2 It is set to +E 3. in this (4) type -- it can also creep -- it is a known value. Therefore, , is obtained from (4) types. Here, amount-of-energy [ per pulse ] E. It closes, and if maximum EOmax which the capability of laser light source 10 permits is used, a next door and this will be determined in n2. Next, it is E by Si who substitutes for (4) types which mentioned this above using n2 obtained from (6) types as mentioned above. It Decided. Amount-of-energy [ per / which was determined as mentioned above / pulse ] E. It To respond, is outputted from energy command signal Se or control exposure 22 to laser light source 10, and is carried out in control of the output light intensity (refer to Step 104). On the other hand, it Response to n2 pulses determined as mentioned above, is determined in the number signal Sn of pulses, and is outputted from control exposure 22 to shutter control part 24. Next, at shutter control part 24, they are this number signal Sn of pulses, opening-and-closing operating time ta of shutter 14 stored beforehand, tb, and td. Based on te, time TD of closed instructions is relatively called for from the timing of the pulse output of laser light source 10 (refer to Step 106). in addition -- time TA of Open command receives the timing of the pulse output of laser light source 10 -- oh -- caulking -- suitably -- window To be. When it explains in full detail, the number signal Sn of pulses shows first in 02 pulses contained by TE from time TC. On the other hand, since it is set in pulse repetition interval TP as it mentioned above, the length of time tc can be found with the value of these 02 pulses and pulse repetition interval TP. Since time TC The is certainly performed in a pulse output, it can search for the difference of the timing of Open command, and the output timing of luminescence trigger signal St using known time tb. First, corresponding to the human power of luminescence trigger signal St, Open command will be performed to shutter driver 16 from shutter control part 24 by this (refer to Step 108), and will be started in Opening operation of shutter 14. And based on exposure start signal S exp by which human power was carried out to control exposure 22, it will be outputted to luminescence Tori Karr signal St or laser light source 10 (Step+10), a laser pulse will be outputted, and it will be started in exposure (refer to Step 112). The laser pulse which passed shutter 14 penetrates the second illumination-light study system 18, enters into Reticle R, and is performed in exposure of the circuit pattern of Reticle R to wafer W. During continuation of the above exposure operations, it is carried out in the time check of whether the time of Open command of shutter 14 came (refer to Step 114). and a time check -- closed instructions are performed by shutter control part 24 after an end (refer to Step 116). If it explains in full detail, after the time which deducted known time td from known time tb and the above-mentioned time tc passes, closed instructions of shutter 14 will be performed after the above-mentioned Open command. Based on these instructions, closed operation of shutter 14 will be performed and the exposure operation to wafer W will be completed (refer to Step 118). In the above-mentioned example, it is easy to stabilize luminescence trigger signal St in the direction by which the definite-periods-of-time partition output is always carried out, and the energy of each output pulse of laser light source 10, it is blended, and is preferred. however -- if laser light source 10 is continuously made to emit light when not exposing Reticle R -- the light source 10 -- especially -- the life of the part -- short -- Nuclear -- Is called -- Is inconvenient? it is. For this reason, it is good in the way to which it begins to apply a laser beam and which outputted luminescence Tori Karr signal St only when exposing, or so that luminescence operation of laser light source 10 may be performed from before for a while. It was made better [ start / exposure / to emit light from before for a while ], since the light volume of the first output pulse may become larger than a desired value when it begun to separate luminescence from the state which is not emitting light at all in laser light source 10 between definite periods of time. however -- since that necessity does not exist like this example in opening gradually and becoming large gradually in transmissivity, shutter 14 or -- in this case -- a small portion of exposure starts -- it is not necessary to perform luminescence from before As mentioned above, it is while performing Opening operation of shutter 14 to timing fixed irrespective of a proper light exposure according to this example, Since the relation between the timing of closed operation of shutter 14 and the timing of the luminescence output of laser light source 10 and the light volume of each pulse of laser light source 10 are controlled so that the proper light exposure which wafer W needs is obtained, The exposure energy in each exposure process swings, thru/or it is effective in the ability to prevent generating of variation satisfactorily. a pulse laser -- it uses -- Listen -- To deal, and a proper light exposure or between Toru for exposure -- also when it differs in small quantities, it can respond satisfactorily. Since shutter 14 is provided and a laser output is controlled in addition to control of the laser emission in laser light source 10, there is also malfunction of a laser luminescence trigger system or an advantage that an unnecessary laser output is not performed even if it carries out raw. It cannot be overemphasized that the present invention is not limited to the above-mentioned example at all, and a metaphor can be applied also to the lighting installation using other pulsed light sources other than an excimer laser. The amount of energy per pulse is controlled by the above-mentioned example by controlling a laser light source directly. In the case of an excimer laser, discharge voltage can be controlled and the amount of energy per pulse can be controlled. However, in the light source exterior, that the amount of energy for every pulse becomes unstable, or when it is and this control needs to be performed frequently, since such control has the good energy stability between pulses, it is more advantageous [ the mode which carries out attenuation adjustment by an optical attenuator etc. ]. In the above-mentioned example, although the penetrated type shutter was used, a reflected type shutter may be used. In this case, opening-and-closing operation of a shutter and irradiation of a pulse serve as a reverse relation. That is, if it will be reflected in a pulse and a subject will be irradiated, if a shutter is closed, and a shutter is opened, a pulse will penetrate the shutter and a subject will no longer be irradiated with it. Also in this case, this invention contains. A thing of a mode [ like ] with a Optical path closing Tsukude stage of a lightwave pulse to a subject may be used. Although it is an example to which this invention is applied to an exposure device, the above-mentioned example is not limited to this and can be applied also to other devices.

[Effect of the Invention] it explained above -- as -- this invention -- getting twisted -- the relation of the timing of Optical path closed operation and the timing of the luminescence output of a pulsed light source by a shutter, And since it presupposed the light volume per pulse of the light source that the required amount of energy for irradiation is An introduction(ed), and setting control is carried out, it is effective in the ability to perform light volume adjustment with good sufficient reproducibility.

[Brief Description of the Drawings]

Shutter opening-and-closing operation [ in / in the block diagram in which Drawing 1 shows the example of fundamental composition of the present invention, the explanatory view in which Drawing 2 shows the operation of conventional technology, the lineblock diagram in which Drawing 3 shows one example of this invention, and Drawing 4 / this example ], The explanatory view showing the relation of the luminescence timing of a laser light source and Drawing 5 are flow charts which show operation of an example.

the explanations of letters or numerals of [main part -- Co 10 ... laser light source, 14 ... shutter, 16 ... a shutter driver and 22 tip control part, 24 ... shutter control part. N1 figure