JPH0983057A - Quantity of energy controller and exposing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for controlling the quantity of energy highly accurately in a short time. SOLUTION: The controller for controlling the quantity of pulse energy by regulating the parameters (e.g. the voltage to be applied to an energy generation source) determining the quantity of pulse energy being oscillated from a pulse energy generation source 1 comprises means 7 for storing the relationship between the parameters and the quantity of pulse energy being oscillated from the pulse energy generation source 1 under that parameters while varying with time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy amount control device, and more particularly to an energy amount control device suitable for energy amount control of an exposure device using an excimer laser as a light source.

[0002]

2. Description of the Related Art An excimer laser used as a light source for an exposure apparatus or the like has a variation in the amount of energy of about ± 10% for each oscillating pulse light (pulse energy), and the energy of the oscillating pulse light is large. There are short-term and long-term declines in quantity. This decrease in the amount of energy is
An active substance (eg KrF,
This is due to deterioration of a mixed gas of ArF, etc.). Generally, there is a predetermined relationship as described below between the applied voltage to the pulsed laser light source (or the charging voltage at the time of pulsed light oscillation) and the amount of energy of pulsed light oscillated under the applied voltage, The amount of energy oscillated is uniquely determined by determining the applied voltage. However, if this relationship changes over time (for example, in a gas laser such as an excimer laser, deterioration of a mixed gas of active substances), the applied voltage corresponding to the amount of energy to be emitted next from the above relationship is generated. , The desired amount of energy cannot be obtained. Therefore, based on the measured value of the applied voltage and the measured value of the energy amount, the information on the relationship described above is updated every predetermined unit pulse number or every unit time, and the short-term energy amount of the oscillated pulsed light is updated. The energy amount control considering the long-term decrease is known.

This energy amount control will be described using equations.

The relationship between the applied voltage and the amount of energy oscillated under the applied voltage is expressed by equation (1). Equation (1)
However, since the term representing the change over time is lacking, the information on the change over time is calculated by using equations (2) and (3) from the data measured during actual operation to obtain the equation (1). The coefficients a, b and c of are updated.

P = a + bv + cv ² (1)

[0006]

[Outside 1] Here, p is the amount of energy and v is the applied voltage. Subscript i
Indicates the freshness of the data, and becomes older as it gets larger. Further, γ is a so-called forgetting coefficient, which is 1
It is a smaller positive real number.

[0007]

However, in such a method, the equations (2) and (3) are used to update the information.
Requires complex arithmetic processing. Therefore, when updating information in a short cycle to maintain high control accuracy, a time required for a certain amount of calculation is required each time, which may be a factor of lowering throughput in the exposure apparatus.

In order to solve the above-mentioned problems, the present invention sets a basic equation in consideration of changes with time in applied voltage (or charging voltage) in an energy generating source and energy amount of oscillated pulse energy. Then, it aims at providing the energy amount control apparatus which can achieve highly accurate energy amount control in a short time.

[0009]

In order to achieve the above object, the first invention of the present application has a pulse energy generating source which oscillates pulse energy accompanied by fluctuation of energy amount for each oscillation, and the energy amount of the pulse energy. In the energy amount control device for controlling the energy amount of the pulse energy by adjusting the control parameter for the pulse energy generating source, the control parameter and the pulse energy generating source oscillate under the control parameter. It is characterized by having a storage means for storing a relational expression of the pulse energy and the amount of energy that changes with time.

The second invention of the present application has a pulse energy generation source that oscillates pulse energy accompanied by fluctuations in energy amount for each oscillation, and adjusts a control parameter for the pulse energy generation source that determines the energy amount of the pulse energy. In the energy amount control device for controlling the energy amount of the pulse energy by the, the control parameter,
It is characterized by further comprising storage means for storing a relational expression between an energy amount of pulse energy oscillated by the pulse energy generation source under the control parameter and an oscillation history of the pulse energy generation source.

A third invention of the present application is an exposure apparatus which has the energy amount control apparatus of the first and second inventions of the present application and which transfers the transfer pattern formed on the mask to the wafer by using the energy amount control apparatus.

A fourth invention of the present application is a device manufacturing method characterized by manufacturing a device using the exposure apparatus of the third invention of the present application.

[0013]

1 is a block diagram showing a schematic configuration of an energy amount control apparatus according to a first embodiment of the present invention. Here, in order to have the simplest and basic configuration, pulse energy oscillated from the pulse oscillation type energy generation source 1 such as an excimer laser is applied to the irradiation target object 3 according to a predetermined oscillation condition input from the input / output device 8. It is configured to irradiate.

In FIG. 1, the applied voltage control unit 11 controls the high-voltage discharge power source (corresponding to the applied voltage) of the pulse oscillation type energy generating source 1 to correspond to the energy amount of the pulse energy to be irradiated next. The applied voltage (control parameter) is applied to the energy generating source 1 to adjust the energy amount for each pulse. The trigger control unit 10 sends an external trigger pulse to the energy generation source 1 after the charging time required by the energy generation source 1 has elapsed, and controls its oscillation (pulse number, oscillation interval, etc.). Here, both the trigger control unit 10 and the applied voltage control unit 11 operate according to a command signal output from the main control system 9 (described later). The pulse energy oscillated from the energy generation source 1 is coherent laser light, incoherent pulse light, or pulse energy other than light such as an electron beam.

The energy beam EB emitted from the energy generating source 1 is split by the beam splitter 2, and most of the energy beam EB passes through the beam splitter EB and irradiates the object 3 to be irradiated. On the other hand, a part of the energy beam EB reflected by the beam splitter 2 is part of the energy monitor element 4
(For example, in the case of an excimer laser, it is incident on a pyroelectric power meter, a PIN photodiode, etc.), and a signal corresponding to the amount of energy is accurately output. The output signal from the monitor element 4 is input to the energy amount monitor unit 5, where it is converted into an energy amount for each pulse energy. Therefore, the monitor element 4 and the energy amount monitor unit 5 constitute the energy amount measuring means of the present invention, and are associated with the energy beam with which the irradiation object 3 is irradiated in a predetermined relationship, that is, the optical performance of the beam splitter 2. The energy amount of the energy beam that is uniquely determined by is measured.

The actual measurement value measured by the energy amount monitor unit 5 (a value corresponding to the actually measured energy amount, not the energy amount itself) is sent to the calculator 6.
Here, the energy amount for each pulse energy is sequentially integrated, and the applied voltage to the energy generation source 1 corresponding to the energy amount of the pulse energy to be emitted next is output (details will be described later).

The monitor element 4 has a relation between the actual energy amount of the energy beam and the sensitivity of the monitor element 4 which is previously obtained by a power meter and is stored in the memory 7.
Further, instead of calculating the integrated energy amount by the calculator 6,
The energy amount monitor unit may sequentially integrate the energy amount for each pulse, and in this case, the oscillation energy amount for each pulse and the integrated energy amount are output to the calculator 6.

The computing unit 6 is well known (for example, disclosed in Japanese Patent Laid-Open No. 5-62876) based on the energy amount detected by the energy amount monitor unit 5 or the integrated energy amount obtained by sequentially integrating each pulse. Then, the energy amount of the pulse energy to be irradiated next is obtained. Then, the calculator 6 determines the applied voltage corresponding to the amount of energy to be irradiated next, and sends it to the main control system 9.

The main control system 9 outputs a command signal of the applied voltage and the oscillation trigger pulse determined by the calculator 6 to each of the applied voltage control unit 11 and the trigger control unit 10. The input / output device 8 accepts various parameters required for oscillation from the operator and informs the operator of the energy amount of the final pulse energy as necessary. Further, the memory 7 stores the oscillation operation input from the input / output device 8, various parameters (constants) necessary for calculation, a table, and the like.

Here, in FIG. 1, the charging voltage between the two electrodes at the time of energy oscillation in the energy generating source 1 (which uniquely corresponds to the applied voltage applied to the energy generating source 1) is detected. Means (charging voltage measuring means of the present invention) is not shown, and in this embodiment, the case where there is no charging voltage measuring means will be described. In the case where the energy generation source 1 is provided with the charging voltage measuring means, it suffices to take the measurement result of the charging voltage measuring means into the computing means and update the charging voltage instead of the applied voltage. Omit it.

Next, the formula representing the relationship between the applied voltage (or charging voltage) and the amount of energy oscillated, which forms the core of the present invention, will be described in detail.

In order to explain the difference between the short-term temporal change and the long-term temporal change in the oscillated pulse energy, FIG.
FIG. 2 shows a pulse train of a plurality of trains (k trains in FIG. 2) composed of pulse energies and a period of oscillation pause between each pulse train. What is a short-term change over time?
It refers to the phenomenon that the energy amount of the pulse energy of n times of each pulse train is sharply reduced.
This is a phenomenon in which the average pulse energy amount of each pulse train gradually decreases.

Of these, the long-term change over time can be predicted by the equation (4) obtained by experiments conducted in advance.

Po (s) = qpoo / (s + q) (4) Here, po (s) corresponds to the pulse energy amount offset value of the first pulse of the k-th pulse train, and poo and q are obtained in advance by experiments or the like. Is a constant and s is the number of pulses from a predetermined time point.

FIG. 3 is a diagram showing an example of a short-term temporal change in the relationship between the applied voltage and the energy amount of pulse energy oscillated in the same pulse train. In FIG. 3, the energy amount with respect to the applied voltage has a high-order function type, but when the setting range of the applied voltage is narrow, it can be approximated with a linear function type.

Thus, the n-th pulse energy amount pn in an arbitrary pulse train is the oscillation pulse energy amount pi traced back to m in the past and the applied voltage vi (subscript i is the ordinal number of the pulse in each pulse train, 1). (Ignored if less than), and from the applied voltage charging voltage vn of this time, equation (5)
Predicted in.

[0027]

[Outside 2] Note that e, f, and g are constants obtained in advance by experiments,
po (s) is the pulse energy amount offset value of the first pulse obtained by the equation (4).

From this, if the applied voltage or the charging voltage vn is solved from the equation (5), it can be expressed as follows.

[0029]

[Outside 3] Therefore, the applied voltage vn corresponding to the energy amount pn of the pulse energy to be oscillated next time can be obtained from the equation (6).

Next, a second embodiment of the present invention will be described.

The device configuration of the second embodiment is the same as that of the first embodiment, but in order to cope with the case where more precise pulse energy control is required, a long-term temporal change of the oscillation pulse energy is performed in advance. It is predicted by the equation (7) obtained by the experiment etc.

[0032]

[Outside 4] Here, po (s) corresponds to the pulse energy amount offset value of the first pulse of the k-th pulse train, and qi and Qi are n and n-1 constants obtained in advance by experiments or the like (n is 1 Larger integer), s is the number of pulses from a given point in time.

Next, a third embodiment of the present invention will be described.

The device configuration of the third embodiment is also the same as that of the first embodiment, but in order to cope with the case where more precise pulse energy control is required, a short-term temporal change of the oscillation pulse energy is performed in advance. It is predicted by the equation (8) obtained by the experiment etc.

At this time, the injection pulse energy amount has a higher-order function form (here, k
Next, the nth pulse energy amount in an arbitrary pulse train is predicted by the equation (8).

[0036]

[Outside 5] Here, pn is the predicted value of the pulse energy amount of each pulse train, and pi (subscript i is the ordinal number of the pulse in each pulse train is ignored when less than 1) is the pulse energy amount measured by the energy amount measuring means. Where vi is a past applied voltage or charging voltage, e, f, and g are constants obtained in advance by experiments or the like, and po (s) is the first obtained by Equation (4) or Equation (7). It is the pulse energy amount offset value of the pulse.

Therefore, from the equation (8), the applied voltage or the charging voltage v corresponding to the desired next pulse oscillation energy amount pn is obtained.
n can be obtained more precisely.

The energy control devices shown in the first to third embodiments enable high-speed and highly accurate energy control.

Next, an example in which the energy control apparatus of the present invention is applied to an exposure apparatus will be shown.

FIG. 4 shows an exposure apparatus used when manufacturing semiconductor devices such as ICs and LSIs, liquid crystal devices, image pickup devices such as CCDs, and devices such as magnetic heads. A light beam emitted from a light source 101 (a pulse type energy generating source shown in FIG. 1) such as an excimer laser is shaped into a desired shape by a beam shaping optical system 102, and is incident on a light incident surface of an optical integrator 103 such as a fly-eye lens. Be oriented. The fly-eye lens is composed of a collection of a plurality of minute lenses, and a plurality of secondary light sources are formed near the light exit surface thereof. The condenser lens 104 Koehler illuminates the masking blade 106 with the light flux from the secondary light source of the optical integrator 103.
Part of the pulsed light split by the half mirror 105 (the beam splitter 2 shown in FIG. 1) is detected by the light quantity detector 11
2 (energy monitor element 4 and energy monitor unit 5 shown in FIG. 1). The masking blade 106 and the reticle 109 are arranged in a conjugate relationship by the imaging lens 107 and the mirror 108, and the shape and size of the illumination area on the reticle 109 are defined by the shape of the opening of the masking blade 106. Reference numeral 110 denotes a projection optical system, which applies the circuit pattern drawn on the reticle 109 to the wafer 1
The reduced projection is made on 11.

Reference numeral 113 denotes a light quantity calculator (calculator 6 shown in FIG. 1), which calculates an exposure amount based on a signal from the light quantity detector 112. Laser control system 114 (main control system 9, trigger control unit 10, applied voltage control unit 11 shown in FIG. 1)
Outputs a trigger signal and an applied voltage signal to the light source 101 according to a desired exposure amount, and controls the laser output and the light emission interval.

By applying the energy control device of the present invention to an exposure device, high-speed and highly-accurate energy control (exposure amount control) becomes possible and throughput can be improved.

In the present embodiment, the projection type exposure apparatus for projecting the pattern of the reticle by the projection optical system has been described. However, if the exposure apparatus uses a pulse energy generation source such as an excimer laser as a light source, a contact method, It is applicable to various exposure apparatuses such as the proximity method and the slit scan method.

Next, an embodiment of a method of manufacturing a semiconductor device using the above-mentioned exposure apparatus will be described.

FIG. 5 shows a manufacturing flow of semiconductor devices (semiconductor chips such as IC and LSI, liquid crystal panels and CCDs). In step 11 (circuit design), the circuit of the semiconductor device is designed. In step 12 (mask production), a mask (reticle 109) on which the designed circuit pattern is formed is produced. On the other hand, in step 13 (wafer manufacturing), a wafer (wafer 111) is manufactured using a material such as silicon. Step 14 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the lithography technique using the mask and the wafer prepared above.
The next step 15 (assembly) is called a post-process, and is a process of forming a chip using the wafer prepared in step 14, and includes an assembly process (dicing, bonding), a packaging process (chip encapsulation) and the like. Including. In step 16 (inspection), the semiconductor device manufactured in step 15 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, a semiconductor device is completed and shipped (step 17).

FIG. 6 shows a detailed flow of the wafer process. In step 21 (oxidation), a wafer (wafer 11
The surface of 1) is oxidized. In step 22 (CVD), an insulating film is formed on the surface of the wafer. In step 23 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 24 (ion implantation), ions are implanted in the wafer. In step 25 (resist processing), a resist (photosensitive material) is applied to the wafer. In step 26 (exposure), the exposure apparatus exposes the wafer with an image of the circuit pattern of the mask (reticle 109). Step 27 (Development)
Then, the exposed wafer is developed. In step 28 (etching), parts other than the developed resist are removed. In step 29 (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.

[0048]

As described above, according to the present invention,
It is possible to provide an energy amount control device capable of achieving highly accurate energy amount control in a short time, and if the energy amount control device of the present invention is used for an exposure apparatus, throughput is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an energy amount control device of the present invention.

FIG. 2 is a diagram showing a difference between a short-term temporal change and a long-term temporal change of an oscillated energy amount.

FIG. 3 is a diagram showing an example of a short-term temporal change in the relationship between the applied voltage and the energy amount of pulse energy oscillated in the same pulse train.

FIG. 4 is a schematic view of an exposure apparatus using the energy amount control device of the present invention.

FIG. 5 is a flowchart showing a semiconductor device manufacturing process.

6 is a flowchart showing details of a wafer process in the process of FIG.

[Explanation of symbols]

 1 Pulse Oscillation Type Energy Source 2 Beam Splitter 3 Irradiated Object 4 Monitor Element 5 Energy Amount Monitor Section 6 Calculator 7 Memory 8 Input / Output Device 9 Main Control System 10 Trigger Control Section 11 Applied Voltage Control Section

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01S 3/225 H01L 21/30 516D H01S 3/223 E

Claims (12)

[Claims] 1. A pulse energy generation source that oscillates pulse energy with fluctuations in energy amount for each oscillation, and the pulse is obtained by adjusting a control parameter for the pulse energy generation source that determines the energy amount of the pulse energy. An energy amount control device for controlling an energy amount of energy stores a relational expression between the control parameter and an energy amount of pulse energy oscillated by the pulse energy generation source under the control parameter, which changes over time. An energy amount control device comprising storage means. 2. A pulse energy generation source that oscillates pulse energy with fluctuations in energy amount for each oscillation, and the pulse is adjusted by adjusting a control parameter for the pulse energy generation source that determines the energy amount of the pulse energy. In an energy amount control device for controlling the energy amount of energy, the control parameter, the energy amount of pulse energy oscillated by the pulse energy generation source under the control parameter, and the oscillation history of the pulse energy generation source An energy amount control device having storage means for storing a relational expression. 3. The energy amount control apparatus according to claim 2, wherein the oscillation history of the pulse energy generation source is the number of pulse energies oscillated by the pulse energy generation source from a certain point in time. 4. The energy amount control device according to claim 2, wherein the oscillation history of the pulse energy generation source is an energy amount of pulse energy oscillated by the pulse energy generation source from a certain time point. 5. The oscillation history of the pulse energy generation source is the control parameter that oscillates the pulse energy generation source from a certain point of time.
The energy amount control device according to any one of claims 1 to 4. 6. A determination means for determining the control parameter for the pulse energy generation source corresponding to the energy amount of the pulse energy to be oscillated next time by using a relational expression stored in the storage means. The energy amount control device according to any one of claims 1 to 5, wherein: 7. An energy amount measuring means for measuring an energy amount of pulse energy oscillating the energy generating source, and the relational expression is derived from a result measured by the energy amount measuring means. Claims 1 to 6
The energy amount control device described. 8. The control parameter is a voltage applied to the energy generating source.
7. The energy amount control device according to 7 above. 9. The energy amount control device according to claim 1, wherein the control parameter is a charging voltage when the pulse energy in the energy generation source is oscillated. 10. The energy amount control apparatus according to claim 1, wherein the energy generation source is an excimer laser. 11. An exposure apparatus comprising the energy amount control device according to claim 1 and transferring a transfer pattern formed on a mask onto a wafer by using the energy amount control device. 12. A device manufacturing method comprising manufacturing a device using the exposure apparatus according to claim 11.