JPH0969492A - Lighting method, exposure method and exposure system thereby - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an exposure system to start carrying out an exposure process just after a light emission start where a light pattern of spike is outputted so as to be improved in throughput and to elongate expendables in service life by a method wherein the characteristic of a light source is measured, the target value of exposure is adequately set up, and a discharge voltage applied onto an excimer laser is adequately controlled at light pulse emission. SOLUTION: A light exposure calculator 102 converts electrical signals photoelectrically converted by a light exposure detector A12 or a light exposure detector B15 into logical values, and the logical values are inputted into a main control system 104. The main control system 104 is possessed of a memory means which stores a required light exposure given through an input device 105, the intrinsic parameters of an exposure system, and light exposure data and the like measured by a light exposure detecting means, and parameters necessary for exposure are calculated basing on the data stored in the memory means provided to the main control system 104 and transmitted to a laser control system 103 and a stage control system 101. The laser control system 103 outputs a trigger signal 16 and a charge voltage signal 17 using the parameters and corresponding to a required light exposure, whereby the application of a discharge voltage to a light source 1 and the light emission timing of the light source 1 are controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination method, an exposure method, and an exposure apparatus using the same, and particularly to manufacture semiconductor devices such as IC and LSI, liquid crystal devices, imaging devices such as CCD, and devices such as magnetic heads. Among the steps, it is suitable for the lithography step.

[0002]

2. Description of the Related Art In recent years when high integration of LSI is required,
For example, 256M dynamic RAM requires a line width processing accuracy of 0.25μm. Then, in order to increase the resolution, a light source having a wavelength shorter than the i-line of a mercury lamp which has been conventionally used as exposure light has come to be used. An excimer laser light source is a typical example. However, although this type of laser has a high emission intensity, the emission is discontinuous, and the actual emission time is a pulse emission of several tens of nanoseconds with respect to the maximum emission interval of approximately 2.5 msec. It is a feature. The problem is that the variation of the emission intensity for each pulse emission is large with respect to the control amount given from the outside.

Further, a pulse laser such as an excimer laser has a property of showing a so-called spike-like output pattern in which the output of the laser is high at the start of pulse oscillation of the light source and then gradually decreases as shown in FIG.

Conventionally, since the portion showing the spike-like pattern changes depending on the oscillation stop time, the number of pulses, and the state of the gas / electrode, the unstable portion is restricted so as not to be used for exposure. Alternatively, during discharge, the discharge voltage is applied low immediately after the start of discharge as shown in FIG.
As shown in, the exposure pulse energy is controlled to be stabilized.

[0005]

Of the pulsed light emitted by the excimer laser light source, if the spiked portion of the output pattern is not used for exposure as described above, the gas of the excimer laser and the laser-related optical elements are consumed. It will shorten the life of the product.

Further, even if an attempt is made to control the exposure pulse energy by stabilizing the exposure pulse energy by applying a low discharge voltage immediately after the start of the discharge during the discharge, there is a relationship as shown in FIG. is there. Therefore, the lower the discharge voltage, the more unstable the discharge becomes, and the larger the variation in pulse energy becomes. As shown in FIG. 12, the pulse energy at the spike-shaped portion immediately after the start of oscillation cannot be made constant and varies.

According to the present invention, when a circuit pattern on a reticle is projected and exposed onto a wafer by pulsed light emission using a pulsed laser as a light source, the characteristics of the light source are measured and an exposure target value is set appropriately. , An exposure method and an exposure method for improving the throughput and extending the life of consumables by performing exposure immediately after the start of oscillation exhibiting a spike-shaped output pattern by appropriately controlling the discharge voltage applied to the excimer laser during pulsed light emission It is an object of the present invention to provide an exposure apparatus using.

[0008]

The illumination method according to the present invention is as follows: (1-1) An object is irradiated with a plurality of pulsed lights of a pulsed laser in which the energy of each pulsed light gradually decreases from the start of continuous pulse oscillation. In the lighting method for illuminating,
The pulse number from the start of oscillation. And the energy of each pulsed light from the start of oscillation are measured in advance, and when illuminating the object, the pulse N whose energy drops in the spike shape
o. Also in the above, the feature is that the target energy is determined based on the measured relationship.

Further, according to the exposure method of the present invention, (1-2) the first object is illuminated with a plurality of pulsed lights of a pulsed laser in which the energy of each pulsed light gradually decreases from the start of continuous pulse oscillation. Then, in the exposure method of exposing the image of the first object on the second object, the pulse No. And the energy of each pulsed light from the start of oscillation are measured in advance, and when the second object is exposed, the pulse N whose energy drops in the spike shape.
o. Also in the above, the feature is that the target energy is determined based on the measured relationship.

In particular, (1-2-1) the target energy of the next pulsed light is determined according to the integrated energy of each pulsed light from the start of exposure. (1-2-2) The target energy of the next pulsed light is determined by using the integrated energy of each pulsed light from the exposure start time and the target value of the integrated energy of the previous pulsed light or the next pulsed light. . (1-2-3) The target energy of the next pulsed light is determined using the energy of the previous pulsed light. (1-2-4) Pulse No. from the start of oscillation And the energy of each pulsed light from the start of oscillation are measured a plurality of times, and the target energy is determined using an average value of the measured values of the plurality of times. (1-2-5) When images of the first object are sequentially formed in a plurality of areas on the second object, an image of the first object is formed in an area of the plurality of areas The energy of the first pulsed light for performing the irradiation is determined by using the average value of the energies of the respective pulsed light used to expose another area before and the energy of the first pulsed light at that time. (1-2-6) The energy of the pulsed laser is determined by controlling the discharge voltage. It is characterized by

Further, the exposure apparatus of the present invention includes (1-3) a pulse laser in which the energy of each pulsed light gradually decreases in a spike shape from the start of continuous pulse oscillation, and a plurality of lasers oscillated from the pulse laser are provided. In an exposure apparatus that illuminates a first object with pulsed light and exposes an image of the first object on a second object, a pulse N from the start of oscillation
o. And a storage unit that stores a measurement result obtained by the measurement unit and a measurement unit that previously measures the relationship between the energy of each pulsed light from the start of oscillation, and the second object is exposed. The pulse No. in which the energy drops in the spike shape. Also in the above, the target energy is determined based on the measurement result stored in the storage means.

In particular, (1-3-1) the target energy of the next pulsed light is determined according to the integrated energy of each pulsed light from the start of exposure. (1-3-2) The target energy of the next pulsed light is determined by using the integrated energy of each pulsed light from the start of exposure and the target value of the integrated energy of the previous pulsed light or the next pulsed light. . (1-3-3) The target energy of the next pulsed light is determined using the energy of the previous pulsed light. (1-3-4) The pulse number from the start of oscillation by the measuring means. And the energy of each pulsed light from the start of oscillation are measured a plurality of times, and the target energy is determined using the average value of the measured values of the plurality of times. (1-3-5) When images of the first object are sequentially formed in a plurality of areas on the second object, an image of the first object is formed in an area of the plurality of areas. The energy of the first pulsed light is determined by using the average value of the energies of the respective pulsed light used to expose another area and the energy of the first pulsed light at that time. (1-3-6) A discharge voltage control unit that controls the discharge voltage of the pulse laser is provided, and the energy of the pulse laser is determined by controlling the discharge voltage. It is characterized by

The device manufacturing method of the present invention also includes any one of (1-4), (1-2) to (1-2-6).
Or the exposure method described in item (1-3) to (1-3-
It is characterized in that a device is manufactured using the exposure apparatus described in any one of 6).

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram of the configuration of a first embodiment of an exposure apparatus of the present invention. In this embodiment, a light flux emitted from a light source of an excimer laser is applied to a reticle through an illumination optical system, and a circuit pattern formed on the reticle is projected on a wafer coated with a photoconductor by a projection lens to be reduced and printed. This is an exposure system and is used when manufacturing semiconductor devices such as ICs and LSIs, imaging devices such as CCDs, and devices such as magnetic heads.

In the figure, 1 is a light source, which is composed of a pulse laser such as an excimer laser. The excimer laser emits light in a pulsed manner by applying a discharge voltage within a predetermined range. This is called pulsed light emission. The excimer laser can control the intensity of pulsed light emission by the discharge voltage.

Reference numeral 2 denotes a beam shaping optical system, which shapes the light beam from the light source 1 into a predetermined shape and makes it enter the light incident surface of the optical integrator 3. The optical integrator 3 is composed of a fly-eye lens or the like made up of a plurality of minute lenses, and forms a plurality of secondary light sources in the vicinity of its light exit surface. Reference numeral 4 denotes a condenser lens, which illuminates the masking blade 6 with Koehler illumination by a light beam from a secondary light source near the light exit surface of the optical integrator 3.

The light beam illuminating the masking blade 6 illuminates the reticle 9 via the imaging lens 7 and the mirror 8. However, the masking blade 6 and the reticle 9 are in an optically conjugate positional relationship, and The shape and size of the illumination area of the reticle 9 are defined by the shape of the opening. The illuminated area of the reticle 9 is usually rectangular. Also, 1
An exposure amount detector A 2 detects the light amount of a part of the illumination light of pulsed emission divided by the half mirror 5 and outputs a signal to the exposure amount calculator 102.

The beam shaping optical system 2, the optical integrator 3, the condenser lens 4, the masking blade 6, the imaging lens 7, the mirror 8 and the like constitute one element of the illumination optical system. Further, the illumination optical system has a light reducing means (not shown), which is configured to adjust the light amount of the light beam from the light source 1 in multiple stages.

The reticle 9 (object, first object) has a circuit pattern thereon and is held by the reticle stage 13. 10 is a projection lens, which is a reticle 9
The reduced circuit pattern is projected onto the wafer (second object) 11. A resist, which is a photoconductor, is applied to the surface of the wafer 11 to form a photoconductive surface, and the wafer 11 is mounted on a wafer stage 14 which is three-dimensionally displaced. Therefore, the surface of the wafer 11 is in a position conjugate with the masking blade 6.

An exposure amount detector B is provided on the wafer stage 14.
15, the exposure amount of the excimer laser can be monitored via the projection lens 10.

A stage drive control system 101 controls the reticle stage 13 and the wafer stage 14. The exposure amount calculator 102 converts the electric signal photoelectrically converted by the exposure amount detector A12 and the exposure amount detector B15 into a logical value and outputs it to the main control system 104. The exposure amount detector A
12 can measure the intensity even during exposure, and is used to estimate the exposure amount of the light with which the wafer 11 is irradiated. The exposure amount detector B15 detects the intensity of the light that passes through the projection lens 10 and irradiates the wafer at the beginning of the exposure process, and finds the correlation between this and the intensity of the light detected by the exposure amount detector A12. Exposure amount detector A1 for exposure by pulsed light emission
The value detected by 2 is corrected using the above correlation, and the exposure amount on the wafer is obtained. Therefore, the exposure amount detector B
No. 15 does not measure the exposure light intensity during exposure of the wafer. The exposure amount detector A12, the exposure amount detector B15,
The exposure amount calculator 102 and the like constitute one element of the exposure amount detecting means.

Reference numeral 103 denotes a laser control system, which outputs a trigger signal 16 and a charging voltage signal 17 according to a desired exposure amount to control the application of a discharge voltage to the light source 1 and the light emission timing. The laser control system 103 uses the trigger signal 1
6. When generating the charging voltage signal 17, the exposure amount calculator 1
02, the current position signal 107 of the stage from the stage drive control system 101, history information from the main control system 104, etc. are used as parameters.

A desired exposure amount (appropriate exposure amount) is input to the main control system 104 from the input device 105 which is a man-machine interface or a media interface. In addition, the results obtained from the exposure amount detector A12 and the exposure amount detector B15, the estimated value of the integrated exposure amount, and the like are displayed on the display unit 106.
Can be displayed on.

The main control system 104 has a storage means,
The desired exposure amount given from the input device 105, the parameters peculiar to the exposure device, and the later-described exposure amount data etc. measured by the exposure amount detecting means etc. are stored in the storage means, and a parameter group necessary for the exposure is calculated from this and laser is calculated. It is transmitted to the control system 103 and the stage control system 101. The main control system 104,
The laser control system 103 and the like constitute one element of laser control means. The laser control means constitutes one element of the discharge voltage control means.

The laser control means and the exposure amount detecting means constitute one element of the measuring means.

The present embodiment is a so-called stepper that prints a circuit pattern on the photosensitive surface of the wafer 11. However, since an excimer laser is used as a light source, at the time of exposure, a pulse emission of the excimer laser is applied to the same area on the photosensitive surface. The exposure is continuously repeated a predetermined number of times to form an image of the circuit pattern on the reticle 9 in the area.

FIG. 2 is an exposure control flowchart of the first embodiment. The flow of the exposure control of this embodiment will be described using this.

Step 101 : Prior to the exposure operation on the wafer, the laser is oscillated in advance, and the pulse No. n from the start of laser oscillation (at the start of pulse emission) and the exposure pulse energy (exposure amount) E received on the photosensitive surface at that time Seek a relationship with. This gives the diagram shown in Fig. 8, but this measurement is performed multiple times and the average value of the measured values for each pulse No. is obtained to obtain a smooth pulse No. n as shown in Fig. 3. A diagram of various exposure pulse energy (exposure amount) E is obtained. The exposure pulse energy E is the exposure amount detector A12.
However, in this step, the exposure amount detector B15 is also detected.
, The exposure pulse energy transmitted through the projection lens 10 is detected, and the detection value of the exposure amount detector A12 and the exposure amount detector B15 are detected.
The detection value of the exposure amount detector A12 is corrected and used after checking the correlation with the detection value of.

The pulse No. n and the exposure pulse energy E are measured under the conditions close to the subsequent exposure conditions (especially, it is desirable that the light emitting intervals are the same), and the laser discharge voltage V, which is a parameter, The number of light emission pulses N and the light emission stop time are changed and obtained. The relationship between the pulse No. n and the exposure pulse energy E obtained from these many parameters is stored in the main control system 104 as exposure amount data.

Step 102 : Input an appropriate exposure amount.

Step 103 : Determine exposure parameters. The exposure pulse number N, the reference discharge voltage V ₀ , the oscillation frequency f are determined and the dimming means is adjusted.

Of these, the number N of exposure pulses and the reference discharge voltage V ₀ are determined as follows. The discharge voltage V _k obtained in step 101 and the integrated exposure amount ΣE _j = P _kj when the laser is emitted at the discharge voltage are made into the following matrix.

[0033]

[Outside 1] Here, P _kj is the integrated exposure amount when j pulses are emitted at the k-th discharge voltage V _k . Then, from this data, the optimum discharge voltage V _k and pulse number j for the proper exposure amount
Are selected by searching, and the reference discharge voltage V ₀ and the exposure pulse number N are determined respectively. At this time, if the integrated exposure amount corresponding to the appropriate exposure amount can be selected with several discharge voltages, a condition with a high discharge voltage and a small number of exposure pulses is selected.
If the amount of data in the matrix is small and the optimum discharge voltage and exposure pulse number are missing, the reference discharge voltage V ₀ and the exposure pulse number N are determined by data interpolation.

The adjustment of the dimming means is performed as follows. If an appropriate amount of exposure is given by pulse exposure with a certain parameter, the number of exposure pulses may not be an integer. At that time, adjust the dimming means to change the intensity of the exposure light,
The number of exposure pulses should be an integer.

Further, based on the relationship (exposure amount data) between the pulse No. n and the exposure pulse energy E obtained in step 101, the target value of the integrated exposure amount to be given to the wafer when each pulse emission is finished ( Set the target integrated exposure dose) P _{1 to} P _N ,
Remember. (P ₁ = E ₁ , P ₂ = E ₁ + E ₂ ..., P
_{N = E 1 + E 2 +} ·· E N, but is E ₁ ~E _N step101
The value obtained in. When these points are connected, they are distributed on a curve as shown in FIG.

The arithmetic processing / memory of this step is performed by the main control system 10.
4 executes.

Step104 : The main control system 104 is the reticle 9,
The exposure position of the wafer 11 is determined.

Step 105 : The main control system 104 moves the wafer stage 14 via the stage drive control system 101 to align the reticle 9 and the wafer 11.

Step 106 : Set pulse No. i = 1.

Step 107 : The discharge voltage V _i is applied to perform pulse oscillation, and the circuit pattern on the reticle 9 is exposed on the wafer 11 with pulsed light. The first discharge voltage V
_{As 1} , the reference discharge voltage V ₀ is applied.

Step 108 : The exposure pulse energy (exposure amount) E _i is detected by the exposure amount detector A12.

Step109 : It is checked whether or not exposure for one shot (exposure to one area) is completed. If i <N, the number of exposure pulses has not reached N, so the process proceeds to step110, and if i = N, exposure is performed. Since the number of pulses has reached N, proceed to step 112.

Step 110 : discharge voltage V of the next exposure pulse
Determine _{i + 1} . The method is as follows. The integrated exposure amount (the integrated value of the exposure amount ΣE _j ) is calculated from the detected exposure pulse energy E _i , and the next discharge voltage V _{i + 1} is determined by the following equation (1) by comparison with the target integrated exposure amount P _i. To do.

[0044]

[Equation 1] Expression (1) is applied when the relationship between the discharge voltage V and the exposure pulse energy E _i is linear.

Normally, the discharge voltage V and the exposure pulse energy E
Has a non-linear portion as shown in FIG. Also, step
The relationship between the pulse No. n obtained at 101 and the exposure pulse energy E is as shown in FIG. Therefore, paying attention to the V-E relationship of the pulse No. portion corresponding to the pulse No. i in FIG. 3, the following target integrated exposure amount P _{i + 1} and the previous integrated exposure amount ΣE _j The discharge voltage V _{i + 1} for the next light emission in the equation (2)
May be derived.

[0046]

[Equation 2] step111 : Set i + 1 as pulse No. i.

Next, the process proceeds to step 107 and the processes of steps 107 to 109 are repeated.

Step 112 : It is checked whether or not all shots on one wafer are finished, and if not, step
Repeat the process from 103 to step112. If it is finished, the wafer 11 is unloaded and the next wafer is loaded.

When proceeding to the next shot in this step, for example, the average value (ΣV _i / n) of the reference discharge voltage (V ₀ ) _n and the applied discharge voltage in the immediately preceding shot.
The stability of the light source may be further checked, and if the light source is in a stable state, steps 104 to 112 may be performed as shown by the dotted line.

When the parameters are determined again in step 103, several kinds of target integrated exposure dose tables or functions are prepared as shown in FIG. 6 based on the exposure pulse number N and the stop time. Determine parameters such as the number of pulses.

In the present embodiment, the above processing is performed to use the target integrated exposure amount P _i of each pulse from the start of pulse oscillation, and the discharge voltage is feedback-controlled based on the integrated exposure amount ΣE _j to perform the next pulse emission. ing.

The effects of this embodiment will be described. Conventionally, when it was attempted to make the laser output constant from the start of oscillation, it was necessary to control the laser output at a low discharge voltage in order to remove spikes. However, when the discharge voltage of the excimer laser is low, there are large variations in the laser output, and it is difficult to stabilize the output constant. However, in the present embodiment, the average value of the spike-shaped output pattern is obtained and set as the target value, so that it is not necessary to control the laser at a low discharge voltage. Therefore, the integrated exposure amount can be stably achieved even when the number of exposure pulses is small.

Even if the discharge voltage is controlled in order to make the laser output constant, it is impossible to completely flatten the spike-shaped output pattern. Therefore, there are cases where the laser is shot blank without performing exposure until the laser output settles within a certain range. However, in this embodiment, the portion of the spike-shaped output pattern is used for the exposure as it is, so that it is not necessary to hit it blank, and the number of laser emission pulses required for the exposure can be reduced. This reduction in the number of exposure pulses leads to an improvement in throughput and a prolongation of the life of consumables, as compared with the case where exposure is performed after blanking.

FIG. 7 is an exposure control flowchart of the second embodiment. The configuration of the exposure apparatus of this embodiment is the same as that of the first embodiment, but the first embodiment is different from the target integrated exposure amounts P _{1 to} P _N.
However, the present embodiment is different in that feedback control is performed with respect to the target exposure amount for each shot. The exposure control flow of this embodiment will be described.

Step 201 : Prior to the exposure work on the wafer, the laser is oscillated in advance, and the pulse No. n from the start of laser oscillation (at the start of pulse emission) and the exposure pulse energy (exposure amount) E received by the photosensitive surface at that time Seek a relationship with. This gives the diagram shown in Fig. 8, but this measurement is performed multiple times and the average value of the measured values for each pulse No. is obtained to obtain a smooth pulse No. n as shown in Fig. 3. A diagram of various exposure pulse energy (exposure amount) E is obtained. The exposure pulse energy E is the exposure amount detector A12.
However, in this step, the exposure amount detector B15 is also detected.
, The exposure pulse energy transmitted through the projection lens 10 is detected, and the detection value of the exposure amount detector A12 and the exposure amount detector B15 are detected.
The detection value of the exposure amount detector A12 is corrected and used after checking the correlation with the detection value of.

The pulse No. n and the exposure pulse energy E are measured under the conditions close to the subsequent exposure conditions (especially, it is desirable that the light emission intervals are the same), and the laser discharge voltage V, which is a parameter, The number of light emission pulses N and the light emission stop time are changed and obtained. The relationship between the pulse No. n and the exposure pulse energy E obtained from these many parameters is stored in the main control system 104 as exposure amount data.

Step 202 : Input an appropriate exposure amount.

Step 203 : Determine exposure parameters. That is, the main control system 104 determines the exposure pulse number N and the reference discharge voltage V
₀ , the oscillation frequency f is determined and the dimming means is adjusted. The method is the same as in step 103 of the first embodiment.

Further, based on the relationship between the pulse No. n obtained in step 201 and the exposure pulse energy E, the target value (target exposure amount) Pt _{1 to} Pt _N of the exposure amount of each pulse emission is set. (P
_{t 1 = E 1, Pt 2} = E 2, Pt N = E N, where E ₁ ~
E _N is the value obtained in step 201).

Step 204 : The main control system 104 is the reticle 9,
The exposure position of the wafer 11 is determined.

Step 205 : The main control system 104 moves the wafer stage 14 via the stage drive control system 101 to align the reticle 9 and the wafer 11.

Step 206 : Set pulse No. i = 1.

Step 207 : The discharge voltage V _i is applied to perform pulse oscillation, and the circuit pattern on the reticle 9 is exposed on the wafer 11 with pulsed light.

Step 208 : The exposure pulse energy (exposure amount) E _i is detected by the exposure amount detector A 12.

Step 209 : It is checked whether or not the exposure for one shot is completed. If i <N, the number of exposure pulses has not reached N, so the process proceeds to step 211. If i = N, the number of exposure pulses reaches N. Yes, go to step 213.

Step 210 : Determine the discharge voltage V _{i + 1} of the exposure pulse. The method is as follows. Discharge voltage V for the next target exposure value from the detected exposure pulse energy E _i and the target exposure amount Pt _i by the following equation (3)
Determine _{i + 1} .

[0067]

(Equation 3) step211 : Set i + 1 as pulse No. i. Then
Go to step 207 and repeat the processing of steps 207 to 209.

Step 212 : Check whether all shots on one wafer are finished, and if all shots are not finished, step
Repeat the process from 203 to step212. If it is finished, the wafer 11 is unloaded and the next wafer is loaded.

When proceeding to the next shot in this step, for example, the average value (ΣV _i / n) of the reference discharge voltage (V ₀ ) _n and the applied discharge voltage in the immediately preceding shot.
The stability of the light source may be examined more, and if the light source is in a stable state, the steps 204 to 212 may be performed as shown by the dotted line.

In step 203, the exposure parameter is determined again based on the number of exposure pulses and the stop time.

[0071] Using the target exposure amount Pt _i of each pulse from the pulse oscillation start performing the above processing in the present embodiment, the discharge voltage and feedback control based on the integrated amount of exposure? En _j by performing the following pulse emission There is.

This embodiment provides the same effect as the first embodiment.

Next, a third embodiment will be described. In the first and second embodiments, the flow chart is based on the assumption that the relationship between the discharge voltage V and the exposure pulse energy E is stable, but in the case of a gas laser, the same discharge actually occurs due to deterioration of the gas, aging, etc. Even if the voltage V is set, the exposure pulse energy E gradually decreases. Therefore, the applied discharge voltage V _i must be higher than the reference discharge voltage V ₀ determined in step 103 or step 203.

However, since the application of the high discharge voltage is started after the second oscillation start of the laser oscillation, in the first pulse emission, the discharge voltage controlled by the deterioration of the gas is estimated as much as the estimated discharge voltage. The output does not increase and the error of the exposure amount becomes larger than the target exposure amount.

Therefore, the initially specified reference discharge voltage V ₀
It is only after a few shots that the exposure amount error in (1) can be canceled, and when the number of exposure pulses is small, the error with respect to the target integrated exposure amount becomes large.

The third embodiment deals with the fact that the relationship between the discharge voltage and the exposure pulse energy changes as the gas deteriorates.

In this embodiment, the reference discharge voltage V _0, which should ideally be constant in each shot as long as there is no variation in the pulse energy of the laser, is set to the immediately preceding shot in step 103 each time the shot changes. By correcting the reference discharge voltage V ₀ that is initially designated based on the discharge voltage applied in (3), it is possible to prevent the error from the target exposure amount from increasing at the start of exposure.

The correction method of the reference discharge voltage V _{0 in} this case is, for example, the discharge voltage V _0mtrix which gives the target integrated exposure amount P _kj once by the matrix as in the first embodiment.
Determining the reference discharge by the following equation multiplying the first ratio between the reference discharge voltage V ₀ 'which is initially specified by the pulse emission of the average value [sigma] v _i / n and the immediately preceding shot of the discharge voltage applied in the immediately preceding shot to The voltage V ₀ is determined.

[0079]

(Equation 4) In the present embodiment, when the images of the circuit pattern on the reticle 9 are sequentially formed in a plurality of regions on the photosensitive surface of one wafer, the discharge voltage of the first pulse emission for forming the images in one region. That is, the reference discharge voltage V ₀ is determined by using the average value of the discharge voltage applied immediately before the image is formed by pulse emission in another region and the discharge voltage of the first pulse emission at that time. This prevents a large error from the target exposure amount at the start of exposure.

In the third embodiment, the reference discharge voltage V ₀ is corrected by using the discharge voltage applied in the immediately preceding shot. Instead of this, the discharge voltage applied in each shot during the wafer exposure immediately before the wafer exchange is performed. Using the formula
It may be modified by (4).

Next, an embodiment of a method of manufacturing a semiconductor device using the exposure apparatus of FIG. 1 will be described.

FIG. 13 shows a manufacturing flow of semiconductor devices (semiconductor chips such as IC and LSI, liquid crystal panels and CCDs). In step 1 (circuit design), the circuit of the semiconductor device is designed. In step 2 (mask production), a mask (reticle 9) on which the designed circuit pattern is formed is produced. On the other hand, in step 3 (wafer manufacturing), a wafer (wafer 11) is manufactured using a material such as silicon. Step 4 (wafer process) is referred to as a preprocess, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. Next Step 5
(Assembly) is called a post-process, and is a process of forming a chip using the wafer created in step 4, and includes an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. Step 6
In (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 14 shows a detailed flow of the wafer process. In step 11 (oxidation), the wafer (wafer 1
The surface of 1) is oxidized. Step 12 (CVD) forms an insulating film on the surface of the wafer. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist processing), a resist (sensitive material) is applied to the wafer. In step 16 (exposure), the wafer is exposed with the image of the circuit pattern of the mask (reticle 9) by the exposure apparatus. Step 17 (development) develops the exposed wafer. In step 18 (etching), parts other than the developed resist are scraped off. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, a circuit pattern is formed on the wafer.

By using the manufacturing method of this embodiment, it becomes possible to manufacture a highly integrated semiconductor device, which has been difficult in the past.

[0085]

According to the present invention, when the circuit pattern on the reticle is projected and exposed on the wafer through the projection lens by pulsed light emission using the pulsed laser as a light source,
The characteristics of the light source are measured, the target value of exposure is set appropriately, and the discharge voltage applied to the excimer laser during pulsed light emission is appropriately controlled to perform exposure immediately after the start of oscillation that exhibits a spike-shaped output pattern. An illumination method and an exposure method that improve throughput and prolong the life of consumables, and an exposure apparatus using the same are achieved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of an exposure apparatus of the present invention.

FIG. 2 is an exposure control flowchart of the first embodiment.

[Figure 3] Relationship between pulse number and exposure pulse energy (average value)

FIG. 4 is an explanatory diagram of an integrated exposure amount target value according to the first embodiment.

FIG. 5 is a relationship diagram between the discharge voltage of the excimer laser and the exposure pulse energy.

FIG. 6 is an explanatory diagram of a cumulative exposure amount target value.

FIG. 7 is an exposure control flowchart of Embodiment 2 of the exposure apparatus of the present invention.

[Figure 8] Relationship between pulse number of excimer laser and exposure pulse energy

FIG. 9 is an explanatory diagram for changing the discharge voltage to keep the exposure pulse energy of the excimer laser constant.

FIG. 10: An example in which the exposure pulse energy is made substantially constant

FIG. 11 is a relational diagram of the discharge voltage of the excimer laser and the dispersion of the laser output.

FIG. 12 is an explanatory diagram of variations in the exposure pulse energy when the discharge voltage is controlled to make the exposure pulse energy substantially constant.

FIG. 13 is a diagram showing a manufacturing process of a semiconductor device.

FIG. 14 is a diagram showing details of the wafer process during the process of FIG. 13;

[Explanation of symbols]

 1 Light Source 6 Masking Blade 9 Reticle 10 Projection Lens 11 Wafer 12 Exposure Amount Detector A 13 Reticle Stage 14 Wafer Stage 15 Exposure Amount Detector B 101 Stage Drive Control System 102 Exposure Amount Calculator 103 Laser Control System 104 Main Control System

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunitaka Ozawa 53 Imaiuecho, Nakahara-ku, Kawasaki-shi, Kanagawa Canon Inc. Kosugi Plant

Claims (16)

[Claims] 1. An illumination method for illuminating an object with a plurality of pulsed lights of a pulsed laser, wherein the energy of each pulsed light gradually decreases in a spike shape from the start of continuous pulse oscillation. And the energy of each pulsed light from the start of oscillation are measured in advance, and when illuminating the object, the pulse N whose energy drops in the spike shape
o. In the above method, the target energy is determined based on the measured relationship. 2. A first object is illuminated by a plurality of pulsed lights of a pulsed laser in which the energy of each pulsed light gradually decreases in a spike shape from the start of continuous pulse oscillation, and an image of the first object is illuminated by a second image. In the exposure method in which the object is exposed, the pulse No. And the energy of each pulsed light from the start of oscillation are measured in advance, and when the second object is exposed, the pulse No. Also in the above, the exposure method is characterized in that the target energy is determined based on the measured relationship. 3. The exposure method according to claim 2, wherein the target energy of the next pulsed light is determined according to the integrated energy of each pulsed light from the start of the exposure. 4. The target energy of the next pulsed light is determined using the integrated energy of each pulsed light from the start of exposure and the target value of the integrated energy of the previous pulsed light or the next pulsed light. The exposure method according to claim 3, which is characterized in that. 5. The exposure method according to claim 2, wherein the target energy of the next pulsed light is determined by using the energy of the previous pulsed light. 6. A pulse No. from the start of oscillation. The measurement of the relationship between the pulse energy and the energy of each pulsed light from the start of oscillation is performed a plurality of times, and the target energy is determined using an average value of the measured values of the plurality of times. The exposure method according to item 1. 7. To form an image of the first object in an area of the plurality of areas when sequentially forming an image of the first object in the plurality of areas on the second object. The energy of the first pulsed light of is determined by using the average value of the energies of the respective pulsed light used to expose another area before and the energy of the first pulsed light at that time. The exposure method according to any one of claims 2 to 6. 8. The exposure method according to claim 2, wherein the energy of the pulse laser is determined by controlling a discharge voltage. 9. A pulsed laser in which the energy of each pulsed light gradually decreases in a spike shape from the start of continuous pulsed oscillation, and the first object is illuminated by a plurality of pulsed lights oscillated from the pulsed laser, In the exposure apparatus that exposes the image of the first object on the second object, the pulse No. And a storage unit that stores a measurement result obtained by the measurement unit and a measurement unit that previously measures the relationship between the energy of each pulsed light from the start of oscillation, and the second object is exposed. The pulse No. in which the energy drops in the spike shape. In the above, the exposure apparatus is also characterized in that the target energy is determined based on the measurement result stored in the storage means. 10. The exposure apparatus according to claim 9, wherein the target energy of the next pulsed light is determined according to the integrated energy of each pulsed light from the start of the exposure. 11. The target energy of the next pulsed light is determined using the integrated energy of each pulsed light from the start of exposure and the target value of the integrated energy of the previous pulsed light or the next pulsed light. The exposure apparatus according to claim 10, which is characterized in that. 12. The exposure apparatus according to claim 9, wherein the target energy of the next pulsed light is determined by using the energy of the previous pulsed light. 13. The pulse No. from the start of oscillation by the measuring means. And the energy of each pulsed light from the start of oscillation are measured a plurality of times, and the target energy is determined using an average value of the measured values of the plurality of times. The exposure apparatus according to item 1. 14. A method for forming an image of the first object in an area of the plurality of areas when sequentially forming images of the first object in the plurality of areas on the second object. The energy of the first pulsed light is characterized by being determined by using the average value of the energies of the respective pulsed light used to expose another area before and the energy of the first pulsed light at that time. The exposure apparatus according to any one of claims 9 to 13. 15. The discharge voltage control means for controlling the discharge voltage of the pulse laser is provided, and the energy of the pulse laser is determined by controlling the discharge voltage. The exposure apparatus according to item 1. 16. A device manufactured by using the exposure method according to any one of claims 2 to 8 or the exposure apparatus according to any one of claims 9 to 15. Production method.