JP2002231930A - Backlight image pickup device and method of manufacturing the same, measuring equipment, and aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variations in the manufacture of a backlight image pickup device by providing a structure, etc., for lowering the influence of the manufacturing requirements for a semiconductor substrate on variations in the characteristics of the entire image pickup device. SOLUTION: The backlight image pickup device comprises a semiconductor substrate of the first conductivity; electric charge accumulating section of the second conductivity for accumulating signal charges pixel by pixel on the second surface of the semiconductor substrate; electric charge transfer section which is formed on the first surface of the semiconductor substrate opposite to the electrode charge accumulating section, and transfers and reads the signal charges; electric charge transfer means for transferring the signal charges accumulated in the electric charge accumulating section to the electric charge transfer section; and barrier region which is formed at least in a part of a transfer path for the signal charges formed between the electric charge accumulating section and the electric charge transfer section, and which blocks the movement of the signal charges at the time of not transferring the electric charges by generating a potential barrier, while guaranteeing the complete transfer of the signal charges at the time of transferring the electric charges by removing the potential barrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for receiving energy rays (visible light, ultraviolet rays, soft X-rays, electron beams, etc.) on one surface side (second surface side) of a semiconductor, and converting photoelectrically converted signal charges. Is transferred to the charge transfer section on the other surface side (first surface side) and read out. The present invention also relates to a method for manufacturing the imaging device, and a measuring device and an exposure device including the imaging device.

[0002]

2. Description of the Related Art FIG. 19 is a view showing a conventional back-illuminated type imaging device 101. As shown in FIG. In FIG. 19, a semiconductor substrate 102 made of a P-type epitaxial layer is formed to a thickness of about 10 μm. On the first surface side of the semiconductor substrate 102, an N-type CCD diffusion layer 103 is provided in a long shape for charge transfer. On the CCD diffusion layer 103, a multi-layer transfer electrode 105 is arranged via a gate oxide film 104. The semiconductor substrate 102 is provided with an antireflection film 109, a support substrate 111, and the like.

The imaging device 101 having such a configuration is irradiated with energy rays from the second surface side. An electron-hole pair is generated on the second surface side of the semiconductor substrate 102 by the energy beam. Some of these electrons are
After moving through the area 2, the charge reaches the potential well of the CCD diffusion layer 103 and is accumulated as signal charges. This CCD
The signal charges in the diffusion layer 103 are transferred by the voltage applied to the transfer electrode 105 and are sequentially read out.

[0004]

By the way, in the above-described image pickup apparatus 101, a phenomenon occurs in which electrons moving through the semiconductor substrate 102 recombine with holes and disappear, and the efficiency of energy ray detection decreases. The frequency of such recombination is affected by the impurity concentration and thickness of the semiconductor substrate 102. Therefore, if the impurity concentration and the thickness of the semiconductor substrate 102 vary at the time of manufacturing, the efficiency of detecting energy rays varies.

[0005] In addition, electrons moving in the semiconductor substrate 102 are mixed between adjacent pixels to generate smear. The degree of occurrence of such smear is also affected by the impurity concentration and thickness of the semiconductor substrate 102. Therefore, if the impurity concentration and thickness of the semiconductor substrate 102 vary during manufacturing, the degree of smearing also varies.

As described above, in manufacturing a back-illuminated imaging device, the manufacturing conditions (eg, epitaxial growth conditions) of a semiconductor substrate must be strictly controlled, which is a major cause of a reduction in manufacturing yield. Was.

In particular, the occurrence of smear as described above becomes more remarkable as the pixel pitch of the image pickup device is reduced. Therefore, in order to increase the number of pixels of the imaging device, it has been strongly required to reduce the occurrence of smear.

Further, in the above-described image pickup apparatus 101, C
The signal charges newly generated on the second surface side are mixed with the signal charges being transferred through the CD diffusion layer 103. Therefore, a mechanical shutter must be provided to shield the second surface from light.
There is also a problem that the structure of the imaging device is complicated.

In view of the above, according to the first to twelfth aspects of the present invention, it is possible to reduce the influence of the impurity concentration and thickness of the semiconductor substrate on the characteristic variation of the image pickup device and to suppress the manufacturing variation of the back-illuminated type image pickup device. With the goal. In particular, in the inventions according to claims 9 to 12, in addition to the above-mentioned objects, it is an object to provide an imaging device that facilitates increasing the number of pixels. Another object of the present invention is to provide a measuring apparatus equipped with the back-illuminated imaging device according to any one of the first to fifth and ninth to twelfth aspects. Another object of the present invention is to provide an exposure apparatus equipped with the measuring apparatus according to the present invention.

[0010]

Means for solving the problems will be described below for each claim. Note that the description here is for illustration or reference, and does not limit the present invention.

(1) The imaging device according to the above (1), wherein the semiconductor substrate of the first conductivity type is arranged on the second surface side opposite to the first surface of the semiconductor substrate, and light is incident from the second surface side. A second conductivity type charge accumulating portion for accumulating signal charges generated by energy rays generated in a pixel unit, and a charge provided on the first surface side of the semiconductor substrate opposite to the charge accumulating portion to transfer and read signal charges A transfer unit; a charge transfer unit configured to transfer the signal charges stored in the charge storage unit to the charge transfer unit; and a transfer unit configured to transfer the signal charges stored in the charge storage unit to the charge transfer unit. When a non-charge is transferred, a peak of a potential barrier is formed (a point where the potential is maximum when viewed from the polarity of the signal charge is called a peak) to block the movement of the signal charge. Guarantees complete transfer of signal charge Characterized by comprising a that barrier region.

According to a preferred aspect of the present invention, the charge storage portion is arranged on the second surface side of the semiconductor substrate. This charge storage section
It has a function of collecting signal charges generated on the second surface side in pixel units. The charge transfer means transfers this signal charge to the charge transfer unit. The charge transfer unit sequentially transfers and reads the transferred signal charges. As described above, the charge accumulation portion in the semiconductor substrate can block unnecessary charges mixed in the charge transfer portion. Therefore, there is no need to provide a mechanical shutter to shield the imaging device from light. Further, the charge storage section and the charge transfer section are arranged in the thickness direction of the semiconductor substrate. Therefore, as compared with a frame transfer type imaging device in which a light-shielded charge accumulation unit and a charge transfer unit are arranged in a plane,
It is easy to reduce the chip size and enlarge the light receiving area. By thus increasing the area of the light receiving portion, the efficiency of detecting the energy rays can be reliably improved.

[0013] Further, the signal accumulating section once collects the signal charges for each pixel, thereby reducing the frequency of mixing of the signal charges between adjacent pixels in the semiconductor substrate, and reducing the influence of manufacturing variations of the semiconductor substrate on the occurrence of smear. can do.

Further, according to a preferred aspect of the present invention, a barrier region is formed between the charge storage section and the charge transfer section. In this case, the threshold condition of the charge transfer can be controlled by the peak of the potential barrier generated in the barrier region. Therefore, it is possible to reduce the influence of the manufacturing variation of the semiconductor substrate on the charge transfer threshold condition.

With the above-described operation, it is possible to reduce the influence of the manufacturing variation of the semiconductor substrate on the characteristics of the back-illuminated imaging device. More preferably, it is possible to clearly separate the charge accumulating portion and the charge transfer portion by the peak of the potential barrier generated in the barrier region. In this case, the risk of signal charges entering the charge transfer section during charge transfer is further reduced, and the mechanical shutter can be omitted.

In a second aspect of the present invention, in the imaging device according to the first aspect, the barrier region is a region formed by introducing a first conductivity type impurity into the semiconductor substrate. There is a feature.

(Claim 3) In the image pickup device according to claim 3, in the image pickup device according to claim 2, the impurity concentration introduced into the barrier region is set higher than the impurity concentration of the semiconductor substrate. It is characterized by. In a preferred aspect of the present invention, the impurity concentration of the semiconductor substrate is set low in advance, and the impurity is further introduced into the semiconductor substrate to form the barrier region. In this case, since the impurity concentration of the semiconductor substrate is relatively low, manufacturing defects such as "irregularity in transfer of signal charges" and "defective pixels" are extremely reduced due to unevenness or variation in manufacturing conditions of the semiconductor substrate. The manufacturing yield of the back-illuminated imaging device can be improved.

According to a fourth aspect of the present invention, in the imaging device according to the first aspect, the barrier region is provided in contact with the charge transfer unit. It is characterized by. In a preferred aspect of the present invention, the barrier region is arranged in contact with the charge transfer section. In this case, it is possible to reliably and accurately control the potential of the peak of the potential barrier from the charge transfer unit side (for example, a transfer electrode provided in the charge transfer unit).

(5) In the imaging device according to the fifth aspect, in the imaging device according to any one of the first to fourth aspects, the barrier region has a potential barrier at the time of non-charge transfer. It is characterized in that it is set lower than the potential barrier generated between the adjacent charge accumulating portions in view of the polarity of the signal charge. According to a preferred aspect of the present invention, the charge transfer section can function as an overflow drain. That is, the signal charge overflowing from the charge storage portion due to the excessive exposure (hereinafter referred to as “excess charge”) flows out of the barrier region to the charge transfer portion before crossing the high potential barrier between adjacent charge storage portions. As a result, it is possible to improve blooming (bleeding of a captured image due to excessive charge) between adjacent pixels. In this case, it is more preferable that the charge transfer unit transfers the excess charge. By such an operation, it is possible to quickly transfer (ie, discharge) the excess charge without staying in the charge transfer unit.

<Claim 6> In a manufacturing method according to a sixth aspect, an epitaxial layer of a first conductivity type is formed on a first surface side of a substrate, and a first conductive type epitaxial layer is formed on the first surface side of the epitaxial layer.
A step of forming a barrier region by introducing an impurity of a conductivity type; and a step of introducing a second conductivity type impurity different from the first conductivity type into the epitaxial layer to form a first region shallower than the barrier region when viewed from the first surface side. Forming a charge transfer portion in a region on the surface side, removing at least a part of the substrate to reduce the thickness of a second surface side opposite to the first surface, and forming a second conductive layer from the second surface side Forming a charge accumulation portion arranged in a pixel unit by introducing a type impurity. According to the above manufacturing method, it is possible to reliably manufacture a back-illuminated imaging device having a charge storage portion and a barrier region.

<Claim 7> In a manufacturing method according to a seventh aspect, a step of forming a first epitaxial layer of a first conductivity type on a first surface side of a substrate; and a step of forming a first epitaxial layer on the first surface side of the first epitaxial layer. Introducing an impurity of a second conductivity type different from the first conductivity type to form charge storage portions arranged in pixel units; and a step of being shallower than the charge storage portions of the first epitaxial layer when viewed from the first surface side. A step of introducing a first conductivity type impurity into a region on the first surface side to form a barrier region and a step of forming a first conductivity type second epitaxial layer on the first surface side of the first epitaxial layer Forming a charge transfer portion by introducing impurities of the second conductivity type to the first surface side of the second epitaxial layer; removing at least a portion of the substrate to form a charge transfer portion opposite to the first surface side; Thinning the two surfaces. According to the above manufacturing method, it is possible to reliably manufacture a back-illuminated imaging device having a charge storage portion and a barrier region.

In a preferred embodiment of the present invention, a first conductive type first epitaxial layer is formed on the first surface side of the substrate, and the first epitaxial layer is formed from the first surface side of the first epitaxial layer. Introducing an impurity of a second conductivity type different from the first conductivity type to form a charge storage portion arranged in pixel units; and providing a first conductivity type first impurity layer on the first surface side of the first epitaxial layer. (2) a step of forming an epitaxial layer; a step of introducing a first conductivity type impurity into a first surface of the second epitaxial layer to form a barrier region; and a step of forming a charge in the second epitaxial layer as viewed from the first surface. A step of introducing a second conductivity type impurity into a region on the first surface side shallower than the accumulation portion to form a charge transfer portion; and removing at least a part of the substrate to form a charge transfer portion opposite to the first surface side. Thinning the two surfaces. According to the above manufacturing method, it is possible to reliably manufacture a back-illuminated imaging device having a charge storage portion and a barrier region.

In a ninth aspect, in the imaging device according to the ninth aspect, the semiconductor substrate of the first conductivity type is arranged on the second surface side of the semiconductor substrate opposite to the first surface, and the light is incident from the second surface side. A second-conductivity-type charge accumulating portion for accumulating signal charges generated by an energy beam generated on a pixel-by-pixel basis and a first surface side of the semiconductor substrate opposed to the charge accumulating portion for transferring and reading out signal charges And a transfer electrode for applying a transfer voltage to the charge transfer path. The transfer electrode substantially corresponds to one charge storage portion along the charge transfer direction of the charge transfer path. It is characterized by being periodically arranged at a rate equal to or less than the number of pieces.

According to a preferred aspect of the present invention, substantially one charge storage portion is disposed so as to face two transfer electrodes or less.
In this case, as compared with the case where one charge storage unit is arranged for each phase interval (generally, an interval of 3 to 4 transfer electrodes),
It is possible to arrange the charge storage portions densely. Therefore, it is possible to reliably increase the number of pixels of the back-illuminated imaging device.

Further, in this case, once the signal charges are collected in the charge accumulating unit for each pixel, the frequency of mixing of the signal charges between adjacent pixels in the semiconductor substrate is reduced, and the manufacturing variation of the semiconductor substrate causes smear. The effect can be reduced.

(Claim 10) In the imaging device according to the ninth aspect, in the imaging device according to the ninth aspect, the transfer is performed for one charge storage unit along the charge transfer direction of the charge transfer path. It is characterized in that the electrodes are periodically arranged at a rate of substantially two electrodes.

According to a preferred aspect of the present invention, the transfer electrode 2 is provided.
The charge storage units are disposed substantially one by one so as to face each other. In this case, the charge storage units can be densely arranged as compared with the case where one charge storage unit is provided for each phase interval (usually, an interval of 3 to 4 transfer electrodes). Therefore, it is possible to easily increase the number of pixels of the back-illuminated imaging device.

Further, in this case, once the signal charges are collected in the charge accumulating unit for each pixel, the frequency of mixing of the signal charges between adjacent pixels in the semiconductor substrate is reduced, and the manufacturing variation of the semiconductor substrate causes smear. The effect can be reduced.

[Claim 11] In the imaging device according to the eleventh aspect, in the imaging device according to the ninth or tenth aspect, a phase interval between transfer electrodes (the same voltage waveform is applied during multi-phase driving). Split transfer means for transferring the signal charge from the charge storage portion to the charge transfer path at every (transfer electrode interval), and transferring the signal charge for one screen in a plurality of times while shifting the phase of the transfer position of the signal charge; Each time the signal transfer is transferred to the charge transfer path by the split transfer means, the transfer electrode is driven in a multi-phase manner and divided transfer means for reading out the signal charges for one screen in a plurality of times is provided. . Claim 11
In a preferred embodiment, the signal charge is transferred from the charge storage unit to the charge transfer unit at every phase interval. As described above, the signal charges are not transferred at one time, and the signal charges are transferred with a space between them, whereby the occurrence of smear can be reduced.

In a twelfth aspect of the present invention, in the imaging device of the twelfth aspect, the density change of the impurity concentration periodically changes in the charge transfer path at every electrode interval of the transfer electrode. The signal charges are formed and progressively transferred by two-phase driving of the transfer electrodes. According to a preferred aspect of the present invention, the signal charges are progressively transferred by two-phase driving. In this case, a periodic potential gradient occurs in the charge transfer path due to the change in the impurity concentration, so that the signal charges can be transferred in one direction.

<Claim 13> The measuring device according to claim 13 is the measuring device according to any one of claims 1 to 5 and 9 to 12
And a measurement unit that performs at least one of aberration measurement and position measurement of the test object based on a captured image of the test object by the image pickup device. In a preferred aspect of the thirteenth aspect, the imaging device according to any one of the first to fifth aspects and the ninth to twelfth aspects is mounted on a measuring device. In this case, the measuring device can obtain a high-quality captured image with little variation from the imaging device. As a result, aberration measurement or position measurement of the test object can be performed with high accuracy.

In a fourteenth aspect, an exposure apparatus projects an exposure pattern onto an exposure target, the measurement apparatus according to the thirteenth aspect, and an exposure unit based on a measurement output of the measurement apparatus. And a controller that performs at least one of aberration correction and position control of an exposure position. According to a preferred aspect of the present invention, the measuring apparatus according to the present invention is mounted on an exposure apparatus. In this case, the exposure apparatus can obtain a highly accurate aberration measurement or position measurement result from the measurement apparatus. As a result, the exposure apparatus can perform aberration correction of the exposure unit or positioning of the exposure pattern with higher accuracy.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

<< First Embodiment >> A first embodiment is an embodiment of an imaging apparatus according to the first to eighth aspects of the present invention.

[Configuration of Imaging Apparatus] FIG. 1 is a diagram showing an imaging apparatus 11 according to the first embodiment. FIG. 2 shows FIG.
It is a figure which shows the cross-section of BB 'shown in the inside. FIG.
FIG. 3 is a diagram showing a net impurity concentration at a position AA ′ shown in FIG. 2. Hereinafter, the configuration of the imaging device 11 will be described with reference to FIGS. First, the imaging device 11 has P
A semiconductor substrate 12 comprising a mold epitaxial layer is provided. On the first surface side of the semiconductor substrate 12, an N-type CC
The D diffusion layer 13 is embedded in a unit of a pixel column. This CC
A transfer electrode 15 is arranged near the D diffusion layer 13 via a gate oxide film 14. These transfer electrodes 15 are connected every fourth electrode and are grouped into four terminals φV1 to φV4. These terminals φV1 to φV4 are connected to the vertical transfer unit 16. Each end of the CCD diffusion layer 13 has a horizontal C
A CD unit 24 is provided.

On the other hand, facing the CCD diffusion layer 13,
On the second surface side of the semiconductor substrate 12, an N-type charge storage portion 17 is embedded in pixel units. Adjacent portions of these charge storage portions 17 are electrically isolated through a P + type buried channel stop 17a. Further on the second surface side of the charge storage section 17, a P-type depletion prevention layer 18 is provided. The depletion prevention layer 18 is set to a thickness that allows the energy beam to be detected to sufficiently pass therethrough, and has an impurity concentration sufficient to prevent surface depletion of the charge storage unit 17.

The charge storage section 17 and the CCD diffusion layer 13
The barrier region 19 is arranged between the two to block the charge transfer path. The barrier region 19 is a region having a P-type impurity concentration distribution as shown in FIG. The P-type impurity concentration of semiconductor substrate 12 is set to be lower than the P-type impurity concentration of barrier region 19 in advance. In addition, the imaging device 11 is provided with a bonding pad 20, a support substrate 21, and the like.

[Correspondence between the present invention and the first embodiment]
Hereinafter, the correspondence between the present invention and the first embodiment will be described. Regarding the correspondence between the inventions described in claims 1 to 5 and the first embodiment, the semiconductor substrate corresponds to the semiconductor substrate 12, and the charge transfer section corresponds to the CCD diffusion layer 13, the gate oxide film 14 and the transfer electrode 15. The charge storage unit corresponds to the charge storage unit 17, and the charge transfer means “controls the voltage of the transfer electrode 15 to reduce the signal charge of the charge storage unit 17 to C.
Transfer Function to CD Diffusion Layer 13 ".

[First Manufacturing Method] FIGS. 4 and 5 are views for explaining a first manufacturing method of the imaging device 11. Hereinafter, a first manufacturing method of the imaging device 11 will be described with reference to FIGS. Here, the description of the photolithography step and other known steps will be omitted. First,
For a P + type substrate 30 having a concentration of about 1E18 / cm ³ ,
A P− type epitaxial layer 31 having a concentration of 5E14 / cm ³ and a thickness of about 12 μm is vapor-phase grown (corresponding to the epitaxial layer forming step according to claim 6). The P − type epitaxial layer 31 is a region that becomes the semiconductor substrate 12.

After forming a protection oxide film of about 500 ° on the P− type epitaxial layer 31, B + ions are implanted under the conditions of an acceleration voltage of 340 KeV and a dose of 4E11 / cm ² . The semiconductor substrate in this state is driven in under a condition of (1150 ° C., 360 minutes) in a nitrogen atmosphere to obtain the barrier region 19 (corresponding to the barrier region forming step according to claim 6). In this way,
The semiconductor substrate shown in FIG. 4A is obtained.

Next, the buried CCD diffusion 13, gate oxide film 14, transfer electrode 15, N +, P + diffusion and the like are formed by the same procedure as that of a normal frame transfer type CCD. ). After that, a planarization process, an AL wiring, a bonding pad, a passivation film, and the like are formed. Through the steps so far, the semiconductor substrate shown in FIG. 4B is obtained.

Further, the first surface side of this semiconductor substrate is
After flattening by G (Spin On Glass) processing, the support substrate 21 is bonded via an adhesive layer 43. Thus, the semiconductor substrate shown in FIG. 4C is obtained. Next, hydrofluoric acid 1: nitric acid 3:
Etching is performed in a solution of acetic acid 8, and the P + type substrate 30 is etched.
Is removed (corresponding to the thinning step according to claim 6). Here, the etching rate of P + silicon is P
Control the etching by taking advantage of the fact that it is faster than silicon. Note that a part of the P + substrate may be removed by mechanical polishing or the like before etching. Thus, a semiconductor substrate 12 having a thickness of about 10 μm is obtained.

After forming a protection oxide film on the second surface side of the semiconductor substrate 12, As ions are implanted under the conditions of an acceleration voltage of 340 KeV and a dose of 1E12 / cm ² ,
The ++ type charge storage section 17 is formed (corresponding to the charge storage section forming step according to claim 6). Further, B ions are implanted under the conditions of an acceleration voltage of 50 KeV and a dose of 3E12 / cm ² to form a channel stop 17a.

Further, an acceleration voltage of 10 KeV and a dose of 1
Ion implantation of boron fluoride under the condition of E15 / cm ² ,
The depletion prevention layer 18 is formed. The impurity region thus formed is locally annealed with a laser or the like so that the AL wiring and the like are not exposed to a high temperature. The state so far is shown in FIG. 5D. Next, after forming an antireflection film or the like by a sputtering method, the bonding pad 2 is formed from the second surface side.
Etching is performed by adjusting the position to 0, etc., and FIG.
Get the state of. Finally, through processes such as dicing and packaging, the imaging device 11 is completed.

[Second Manufacturing Method] FIGS. 6 and 7 illustrate a second manufacturing method according to the present invention. Hereinafter, the second manufacturing method will be described with reference to FIGS. Here, the description of the photolithography step and other known steps will be omitted. First, the concentration 1E18 /
For a P + type substrate 30 of about cm ³ , a concentration of 5E14 /
A P- type first epitaxial layer 12a of cm ³ and a thickness of about 6 μm is vapor-phase grown (corresponding to the step of forming the first epitaxial layer according to claim 7).

After forming a protection oxide film on the first epitaxial layer 12a, an acceleration voltage of 340K
As ions are implanted under the conditions of eV and a dose amount of 4E12 / cm ² to form the charge storage portion 17 (corresponding to the charge storage portion forming step according to claim 7). Further, B ions are implanted under the conditions of an acceleration voltage of 60 KeV and a dose of 1E12 / cm ² to form a region serving as a channel stop 17a.

Next, an acceleration voltage of 30 KeV and a dose of 6
B ions are implanted under the condition of E11 / cm ² to form a region to be the barrier region 19 (corresponding to the barrier region forming step according to claim 7). Thereafter, an annealing process (1000 ° C., 30 minutes) is performed in a nitrogen atmosphere to remove the protection oxide film, thereby obtaining the state shown in FIG. 6A.

Next, a P- type second epitaxial layer 12b having a concentration of 5E14 / cm ³ and a thickness of about 6 μm is vapor-phase grown on the surface of the first epitaxial layer 12a (the second epitaxial layer according to claim 7). (Corresponds to the layer forming step). Next, the CCD diffusion layer 13, the gate oxide film 14, the transfer electrode 15, and the like are transferred to a frame transfer type CCD.
(Corresponding to the step of forming the charge transfer section according to claim 7).

Thereafter, a semiconductor substrate shown in FIG. 6B is obtained through a flattening step, a process for forming an AL wiring, a passivation film, and the like. Next, SOG (Spin On Gl
ass) processing. If necessary, CMP (C
Performs flattening processing such as chemical mechanical polishing or mechanical polishing. Thereafter, a low-concentration silicon substrate serving as the support substrate 21 is attached to obtain a state shown in FIG. 6C.

Next, etching is performed in a solution of hydrofluoric acid 1: nitric acid 3: acetic acid 8 to remove the P + type substrate 30 (corresponding to a thinning step according to claim 7). Here, P +
The etching is controlled by utilizing the fact that the etching rate of silicon is faster than that of P-silicon. At this time, a layer region of about 1E17 / cm ^{3 where} the etching rate is slowed down remains at the interface of the first epitaxial layer 12a and becomes the depletion preventing layer 18. FIG. 7D shows the state up to this point.
The depletion preventing layer 18 may be formed by ion implantation and laser annealing. Thereafter, the silicon in the pad portion is opened by dry etching or the like, and the processes of dicing and packaging are performed, thereby completing the imaging device shown in FIG. 7E.

[Third Manufacturing Method] FIG. 20 is a view for explaining a third manufacturing method according to the present invention. Hereinafter, FIG.
The third manufacturing method will be described with reference to FIG. Here, the description of the photolithography step and other known steps will be omitted. First, P + with a concentration of about 1E18 / cm ³
Concentration 5E14 / cm ³ , thickness 5μ
A m-type P-type first epitaxial layer 12a is vapor-phase grown (corresponding to the step of forming the first epitaxial layer according to claim 8).

A protection oxide film having a thickness of about 500 ° is formed on the first epitaxial layer 12a. This first
An acceleration voltage of 340 Ke is applied to the epitaxial layer 12a.
As ions are implanted under the conditions of V and a dose of 4E12 / cm ² to form the charge accumulating portion 17 (corresponding to the charge accumulating portion forming step according to claim 8). Furthermore, the acceleration voltage 6
B ions are implanted under the conditions of 0 KeV and a dose of 1E13 / cm ² to form a region serving as a channel stop 17a.

Thereafter, annealing is performed in a nitrogen atmosphere to recover crystal defects. Through the steps so far, the state shown in FIG. 20A is obtained. Next, on the surface of the first epitaxial layer 12a, a P− type second epitaxial layer 12b having a concentration of 5E14 / cm ³ and a thickness of about 5 μm is vapor-phase grown (formation of the second epitaxial layer according to claim 8). Corresponding to the process).

After forming a protection oxide film having a thickness of about 500 ° on the first surface side of the second epitaxial layer 12b, the acceleration voltage is 340 KeV and the dose is 6E11 / cm ^2.
B ions are implanted under the conditions described above to form a region to be the barrier region 519 (corresponding to the barrier region forming step according to claim 8). Thereafter, an annealing process (1150 ° C., 360 minutes) is performed in a nitrogen atmosphere. Through the steps so far, the state shown in FIG. 20B is obtained.

Next, the CCD diffusion layer 13, the gate oxide film 1
The transfer electrodes 4 and the transfer electrodes 15 are formed in the same procedure as that of the frame transfer type CCD (corresponding to the step of forming the charge transfer section according to claim 8). After that, a flattening step,
An AL wiring, a passivation film, and the like are formed. Next, SOG (Spin On Glass) processing or the like is performed on the wafer. If necessary, CMP (Chemical Mecha)
nical polishing or mechanical polishing. Thereafter, a low-concentration silicon substrate serving as the support substrate 21 is attached to obtain a state shown in FIG. 20C.

Next, etching is performed in a solution of hydrofluoric acid 1: nitric acid 3: acetic acid 8 to remove the P + type substrate 30 (corresponding to the thinning step according to claim 8). Here, P +
The etching is controlled by utilizing the fact that the etching rate of silicon is faster than that of P-silicon. Next, after forming a protection oxide film on the second surface side of the first epitaxial layer 12a, the acceleration voltage is 100 KeV and the dose is 1E1.
BF ions are implanted under the condition of 5 / cm ² . Furthermore, A
The BF ion implanted layer is annealed with a laser or the like to prevent the L wiring and the like from being exposed to a high temperature, thereby completing the depletion prevention layer 18. Thereafter, the silicon in the pad portion is opened by dry etching or the like, and the image pickup device 11 is completed through processes such as dicing and packaging.

[Explanation of Operation of Imaging Apparatus 11] FIGS.
6 is a potential diagram for explaining the operation of the imaging device 11. FIG. Hereinafter, the operation of the imaging device 11 will be described with reference to these potential diagrams. First, as shown in FIG. 8, most of the energy rays reach the charge accumulating portion 17 and generate electron-hole pairs. The electrons generated at this time are attracted and stored in the potential well of the charge storage unit 17, and become signal charges.

In this state, the charge accumulation section 17 and the CCD diffusion layer 13 are electrically separated by the peak of the potential barrier formed by the barrier region 19. If the charge accumulation time is extended in detecting weak light, the CCD diffusion layer 13
The dark current accumulated at the time cannot be ignored. Therefore, during the charge accumulation period, the vertical transfer section 16 sequentially applies a transfer voltage (−5 V / + 5 V) to the transfer electrode 15 to discharge the invalid charges in the CCD diffusion layer 13 and suppress the dark current as much as possible. .

The vertical transfer section 16 fixes the transfer electrode 15 to a negative voltage and makes the surface potential of the CCD diffusion layer 13 close to the substrate potential with respect to the CCD diffusion layer 13 from which the invalid charges have been discharged. By such an operation, holes are gathered on the first surface side of the CCD diffusion layer 13, and the surface depletion of the CCD diffusion layer 13 is prevented. As a result, as shown in FIG. 8, it is possible to greatly suppress the dark current that enters the CCD diffusion layer 13 from the first surface side during the period in which the negative voltage is applied.

The synergistic effect of these actions makes it possible to suppress the dark current sufficiently low even when faint light is accumulated for a long time. On the other hand, when strong light is applied, the potential well of the charge storage unit 17 is saturated, and excess charges overflow. At this time, since the potential barrier of the barrier region 19 is lower than the potential barrier between the adjacent pixels, the overflowed excess charges are:
As shown in FIG. 9, overflow occurs preferentially to the CCD diffusion layer 13 side. The excess charge is discharged to the outside together with the dark current by the discharging operation of the CCD diffusion layer 13 described above. As a result, the blooming phenomenon in the back-illuminated imaging device 11 is improved.

As described above, when the charge accumulation time ends, the vertical transfer section 16 transfers the transfer electrode 1 as shown in FIG.
5 is applied with a positive voltage of about 15V. Then, the peak of the potential barrier due to the barrier region 19 is removed, and the charge accumulation portion 17 is removed.
Is transferred to the CCD diffusion layer 13 side. Subsequently, as shown in FIG. 10, the vertical transfer unit 16 sequentially applies a transfer voltage of about ± 5 V to the transfer electrode 15 and sequentially transfers the signal charges in the CCD diffusion layer 13.

[Effects of First Embodiment, etc.] In the above-described first embodiment, the charge accumulation section 17 and the CCD diffusion layer 13
And a barrier region 19 is arranged between them to generate a potential barrier peak. Therefore, the threshold voltage when transferring charges from the charge storage unit 17 to the CCD diffusion layer 13 is
Of the potential barrier (i.e., the manufacturing conditions of the barrier region 19) can be mainly controlled by the impurity concentration or the thickness of the barrier region. As a result, the characteristics of the imaging device 11 are not significantly affected by the epitaxial growth conditions of the semiconductor substrate 12, and the manufacturing yield of the imaging device 11 can be reliably improved.

In the first embodiment described above, the CC
A charge storage section 17 is provided on the second surface side facing the D diffusion layer 13. Therefore, the moving distance of the signal charges on the second surface side is substantially shortened, and it becomes possible to improve the energy ray detection efficiency and the smear generation. As a result, the variation in detection efficiency and the occurrence of smear due to the variation in the manufacturing of the semiconductor substrate 12 are reduced, and from that point, the manufacturing yield of the imaging device 11 can be improved.

In particular, when the moving distance of the signal charge on the second surface side is long (when the signal charge is generated in an extremely shallow region of the second surface such as when ultraviolet rays or other short-wave energy rays are incident), The improvement effect appears remarkably. In addition, due to the potential barrier peak generated in the barrier region 19, the charge storage portion 17
And the CCD diffusion layer 13 are electrically separated. Therefore, during the charge transfer of the CCD diffusion layer 13, there is much less possibility that signal charges are mixed in from the charge storage unit 17, and a mechanical shutter for shielding the second surface from light is not required.

In particular, in the above-described first manufacturing method, the barrier region 19 is formed in contact with the CCD diffusion layer 13 (FIG. 4).
B). In this case, the CCD diffusion layer 13 can be reliably separated from the semiconductor substrate 12 by covering it with the well-shaped barrier region 19. As a result, it becomes possible to extremely reduce a dark current and the like mixed into the CCD diffusion layer 13 from the semiconductor substrate 12 side.

In addition to such a dark current countermeasure, in the first embodiment, noise countermeasures such as a depletion prevention layer 18, discharge of dark current, and prevention of surface depletion of the CCD diffusion layer 13 are further implemented. Due to these synergistic effects, noise mixed into the captured image is significantly reduced, so that good imaging quality can be obtained even under severe conditions such as detection of weak light.

In the first embodiment, the barrier region 1
9 is set lower than the potential barrier between adjacent charge storage units 17. Therefore, the charge storage unit 17
Is discharged preferentially to the CCD diffusion layer 13 side. As a result, there is little possibility that excess charges are mixed in adjacent pixels, and the blooming phenomenon can be suppressed.
Further, in the above-described first manufacturing method, the barrier region 19
Is formed in contact with the CCD diffusion layer 13. Therefore,
From the transfer electrode 15 of the CCD diffusion layer 13 to the barrier region 19
Of the potential barrier can be reliably controlled.

In the first embodiment described above, a voltage is applied to the transfer electrode 15 and the charge
The charge transfer to the diffusion layer 13 is realized. However, it is not limited to this. For example, as shown in FIG. 11, charge transfer may be realized by controlling the substrate potential. Alternatively, both the transfer electrode 15 and the substrate potential may be controlled to transfer the charge in the charge storage unit 17 to the CCD diffusion layer 13. By controlling both in this way, it is possible to reliably transfer charges to the charge storage section 17 having a large saturated charge amount. Next, another embodiment will be described.

<< Second Embodiment >> The second embodiment is an embodiment corresponding to the first to eleventh aspects of the present invention.
FIG. 12 is a diagram illustrating an imaging device 51 according to the second embodiment. The features of the configuration in the second embodiment are as follows.
Two transfer electrodes 1 are arranged in the CCD diffusion layer 13 so as to face the charge storage portions 17 one by one along the charge transfer direction.
5 is arranged. For other configurations, refer to
This is the same as the configuration of the embodiment (FIGS. 1 and 2). Therefore, description of the configuration is omitted here, and the following description will be made using the same reference numerals as in the first embodiment. The manufacturing method according to the second embodiment is the same as the manufacturing method according to the first embodiment (FIGS. 4 to 7, and FIG. 20) except that the pixel pitch of the charge storage unit 17 is different. Therefore, description of the manufacturing method is omitted here.

[Correspondence between the present invention and the second embodiment]
Hereinafter, the correspondence between the present invention and the second embodiment will be described. Regarding the correspondence between the first to fifth aspects of the present invention and the second embodiment, the semiconductor substrate corresponds to the semiconductor substrate 12, and the charge transfer portion corresponds to the CCD diffusion layer 13, the gate oxide film 14, and the transfer electrode 15. The charge storage unit corresponds to the charge storage unit 17, and the charge transfer means “controls the voltage of the transfer electrode 15 to reduce the signal charge of the charge storage unit 17 to C.
Transfer Function to CD Diffusion Layer 13 ". Regarding the correspondence between the inventions described in claims 9 to 11 and the second embodiment, in addition to the correspondence described above, the charge transfer path corresponds to the CCD diffusion layer 13 and the transfer electrode corresponds to the transfer electrode 15.
In response to the above, the divided transfer means operates the charge transfer section 17 by controlling the voltage of the transfer electrode 15 by the vertical transfer section 16.
The transfer function corresponds to the function of transferring the signal charge to the CCD diffusion layer 13 at every phase interval. The vertical transfer unit 16 provides the four-phase drive pulse to the transfer electrode 15 to interlace transfer the signal charge. Function ”.

[Explanation of Operation of Second Embodiment] FIG.
FIG. 11 is a diagram illustrating a charge reading operation of the imaging device 51 according to the second embodiment. First, as shown in FIG. 13A,
The vertical transfer section 16 applies a voltage of about +15 V to the transfer electrodes 15 facing the charge storage sections 17 in the odd rows.
Then, the signal charges stored in the charge storage unit 17 are transferred to the CCD diffusion layer 13 at every phase interval (here, it corresponds to an interval of four electrodes for four-phase driving). In this state, the vertical transfer unit 16 sequentially applies four-phase drive pulses to the transfer electrodes 15 to transfer the signal charges of the CCD diffusion layer 13. The signal charges of the odd-numbered rows transferred in this manner are the horizontal C
The data is sequentially read out to the outside via the CD 24. Thus, the image reading of the odd field is completed.

Next, as shown in FIG. 13B, the vertical transfer section 16 includes the transfer electrode 1 facing the charge storage section 17 in the even-numbered row.
A voltage of about +15 V to 5 is applied. Then, the signal charges stored in the charge storage unit 17 are transferred to the CCD diffusion layer 13 at every phase interval (here, it corresponds to an interval of four electrodes for four-phase driving). In this state, the vertical transfer unit 16 sequentially applies four-phase drive pulses to the transfer electrodes 15 to transfer the signal charges of the CCD diffusion layer 13. The signal charges of the even-numbered rows transferred in this manner are sequentially read out to the outside via the horizontal CCD 24. Thus, the image reading of the even field is completed.

[Effects of Second Embodiment, etc.] With the above-described configuration, the same effects as those of the first embodiment can be obtained in the second embodiment. Further, in the second embodiment, the pitch of the pixel columns of the charge storage unit 17 can be reduced to half of that in the first embodiment. Therefore, it is possible to easily realize a multi-pixel configuration of the back-illuminated imaging device 51.

In the second embodiment, the signal charges are transferred from the charge storage section 17 to the CCD diffusion layer 13 at intervals every other row. Therefore, signal charges are less likely to be mixed during charge transfer, and it is possible to suppress the occurrence of smear even if the pixel pitch is reduced. In the above-described second embodiment, two transfer electrodes 15 are arranged to face one charge storage unit 17. However, the present invention is not limited to this. For example, one transfer electrode 15 may be arranged corresponding to one charge storage unit 17. In this case, if the transfer electrodes 15 are for four-phase driving, one screen can be read out four times. If the transfer electrodes 15 are for three-phase driving, one screen can be read out three times.
Further, with the transfer electrode 15 for two-phase driving, one screen can be read out twice. Next, another embodiment will be described.

<< Third Embodiment >> A third embodiment is an embodiment corresponding to the first to tenth and twelfth aspects of the present invention. FIG. 14 illustrates an imaging device 52 according to the third embodiment.
FIG. The feature of the configuration in the third embodiment is that the injection region 5 of the same conductivity type as the semiconductor substrate 12 is provided in the CCD diffusion layer 13 at a period for each electrode interval of the transfer electrode 15.
3 is arranged. Other configurations are the same as those of the second embodiment. Therefore, description of the configuration is omitted here, and the same reference numerals as in the second embodiment are used. The manufacturing method according to the third embodiment is the same as the manufacturing method according to the first embodiment (FIG. 4) except that the pixel pitch of the charge storage unit 17 is different and the injection region 53 is formed by introducing impurities. 7 to 20). Therefore, description of the manufacturing method here is also omitted.

[Correspondence between the present invention and the third embodiment]
Hereinafter, the correspondence between the present invention and the third embodiment will be described. Regarding the correspondence between the first to fifth aspects of the present invention and the third embodiment, the semiconductor substrate corresponds to the semiconductor substrate 12, and the charge transfer portion corresponds to the CCD diffusion layer 13, the gate oxide film 14, and the transfer electrode 15. The charge storage unit corresponds to the charge storage unit 17, and the charge transfer means “controls the voltage of the transfer electrode 15 to reduce the signal charge of the charge storage unit 17 to C.
Transfer Function to CD Diffusion Layer 13 ". Further, regarding the correspondence between the inventions according to the ninth, tenth and twelfth aspects and the third embodiment, in addition to the correspondence described above, the charge transfer path corresponds to the CCD diffusion layer 13 and the transfer electrode corresponds to the transfer electrode. Corresponding to the electrode 15, the change in the density of the impurity
3 corresponds to the shading change.

[Explanation of Operation of Third Embodiment] FIG.
FIG. 11 is a diagram illustrating a charge readout operation of an imaging device according to a third embodiment. First, as shown in FIG. 15A,
The vertical transfer unit 16 applies + to the even-numbered transfer electrodes 15.
A voltage of about 15 V is applied. Then, the charge storage unit 17
The signal charges for one screen stored in the LCD are collectively transferred to the CCD diffusion layer 13.

Next, as shown in FIGS. 15B to 15E, the vertical transfer section 16 sequentially applies two-phase drive pulses to the transfer electrodes 15. At this time, the implantation region 53 causes a periodic potential gradient in the CCD diffusion layer 13 (FIG. 15C, FIG. 1).
5E). Since the signal charges move under the influence of the potential gradient, the moving direction of the signal charges is uniquely determined. As a result, two-phase progressive transfer is realized. The transferred signal charges of each row are sequentially read out to the outside via the horizontal CCD 24. In this way, image reading for one screen is completed.

[Effects of Third Embodiment, etc.] With the above-described configuration, the same effects as those of the first embodiment can be obtained in the third embodiment. Further, in the third embodiment, the pitch of the pixel columns of the charge storage unit 17 can be reduced to half of that in the first embodiment. Therefore, it is possible to easily realize the increase in the number of pixels of the back-illuminated imaging device 52.

In the third embodiment, a change in the impurity concentration (here, the implantation region 5) is formed in the CCD diffusion layer 13.
Provision of 3) makes it possible to realize progressive transfer by two-phase driving. In particular, since the signal charges in the CCD diffusion layer 13 are separated by the injection region 53, the signal charges are less likely to be mixed during the charge transfer, and the occurrence of smear can be further reduced.
Next, another embodiment will be described.

<< Fourth Embodiment >> A fourth embodiment is an embodiment of an exposure apparatus (including a measuring apparatus) according to the thirteenth and fourteenth aspects of the present invention. FIG. 16 is a diagram illustrating an exposure apparatus 60 according to the fourth embodiment. 16, a semiconductor wafer 62 is arranged on a wafer stage 61 as a substrate to be exposed. Above the semiconductor wafer 62, a reticle 63a and a reticle stage 63b are arranged via a projection optical system of the exposure unit 63. Through the projection optical system and the reticle 63a, a so-called TTR is set at a position where the mark on the reticle 63a and the alignment mark on the wafer stage 61 are imaged.
(Through the reticle) type imaging device 64a-b
Is arranged. In addition, so-called TTL (through-the-lens) type imaging devices 64c to 64d are arranged at positions where the alignment marks on the wafer stage 61 are imaged via the projection optical system. Further, an off-axis type imaging device 64e is provided at a position where the alignment mark on the wafer stage 61 side is directly imaged without using a projection optical system.
To f are arranged. Note that such imaging devices 64a to 64a
The arrangement position of f is described in, for example, JP-A-6-97031.
It is known in the publication.

The image information picked up by these image pickup devices 64a to 64f is given to the position detecting section 65. The position detector 65 detects the position of the semiconductor wafer 62 or a reference mark plate (not shown) based on the image information. The position control unit 66 controls the wafer stage 6 based on the position detection result.
1 to control the position of the semiconductor wafer 62.
The exposure unit 63 projects a predetermined semiconductor circuit pattern via the reticle 63a onto the semiconductor wafer 62 positioned as described above.

The exposure device 60 includes an image pickup device 64
The imaging device according to any one of claims 1 to 5 and 9 to 12 is mounted as a to f.

[Correspondence between the present invention and the fourth embodiment]
Hereinafter, the correspondence between the present invention and the fourth embodiment will be described. Regarding the correspondence between the invention described in claim 13 and the fourth embodiment, the imaging device corresponds to the imaging devices 64a to 64f, and the measurement unit corresponds to the position detection unit 65. Claim 1
4, the exposure unit corresponds to the exposure unit 63, the measurement device corresponds to the imaging devices 64 a to f and the position detection unit 65, and the control unit controls the position control. This corresponds to the unit 66.

[Effects of the Fourth Embodiment] In the fourth embodiment, the imaging devices 64a to 64f are described as claims 1 to 5,
The imaging device according to any one of 9 to 12, is mounted.
Therefore, it is possible to obtain good captured images with little variation from the imaging devices 64a to 64f. As a result, the measurement accuracy of the position detection is improved, and the positioning accuracy of the exposure device 60 can be further improved. next,
Another embodiment will be described.

<< Fifth Embodiment >> A fifth embodiment is an embodiment of an exposure apparatus (including a measuring apparatus) according to the present invention. In the fifth embodiment, the above-described imaging devices 11, 51, and 52 (CCD and the like) are connected to optical characteristics (for example, coma, astigmatism, and the like) of a test optical system (projection optical system PL (63) in this example). This is an example applied to measurement of wavefront aberration information such as spherical aberration).

Hereinafter, a fifth embodiment will be described with reference to FIG. FIG. 17 is a diagram showing an outline of the exposure apparatus 70. Exposure light generated from the light source 1 illuminates a reticle (mask) R via a mirror 9 and a condenser lens 10. Reticle R is mounted on reticle stage 10a, and reticle stage 10a is controlled by reticle stage control unit 6. A wafer holder 4 is provided on the wafer stage 3 (XY stage 3a, Z and leveling stage 3b), and a wafer W (not shown)
Are chucked on the wafer holder 4. The drive and position of the wafer stage 3 are controlled by the wafer stage controller 5. The main control unit 2 is electrically connected to the light source 1, the reticle stage control unit 6, and the wafer stage control unit 5, and is configured to control them collectively. The main control unit 2 includes a lens control unit LC (to be described later) for adjusting the projection optical system PL and an arithmetic processing unit PC (to be described later) that calculates the aberration of the optical system based on the measurement result by the aberration measurement unit UT described below. ) Are also electrically connected, and these are also collectively controlled.

An aberration measuring unit UT is detachably attached to the side surface of the wafer stage 3 via an attaching / detaching mechanism D. The aberration measurement unit UT has a collimator lens CL
, A two-dimensional lens array in which a plurality of lens elements L are two-dimensionally arranged, and a condensing position detection unit DET.
The image pickup device 1 described above is provided inside the light condensing position detection unit DET.
1, 51, 52, and a plurality of lens elements L
Are condensed on the imaging plane IP of the imaging devices 11, 51, and 52.

Note that the aberration measuring unit UT is connected to the detachable mechanism D.
Mechanically connected to the exposure apparatus 70 (side surface of the stage 3) via the
C is also electrically connected, so that both can communicate with each other. In this embodiment, the arithmetic processing unit P
Although C is provided on the exposure apparatus 70 side, the present invention is not limited to this, and the arithmetic processing unit PC is provided in the aberration measurement unit UT.
When the unit UT is connected to the exposure apparatus 70, the arithmetic processing unit PC may be configured to be in a state where it can communicate with the exposure apparatus 70 side.

[Correspondence between the present invention and the fifth embodiment]
Hereinafter, the correspondence between the present invention and the fifth embodiment will be described. Regarding the correspondence between the invention described in claim 13 and the fifth embodiment, the image pickup apparatus includes a light-condensing position detection unit DE.
The measurement unit corresponds to the arithmetic processing unit PC, corresponding to the imaging devices 11, 51, 52 incorporated in T. Regarding the correspondence between the invention described in claim 14 and the fifth embodiment,
The exposure unit corresponds to the projection optical system PL, the measurement device corresponds to the aberration measurement unit UT, and the control unit corresponds to the lens control unit LC.

[Explanation of Operation of Fifth Embodiment] Next, a procedure for measuring the wavefront aberration of the projection optical system (projection lens) PL and correcting the aberration will be described. When measuring the wavefront of the projection lens PL, light having a wavefront of a spherical wave is incident on the projection lens PL as a light beam for measuring the wavefront aberration. This spherical wave light is generated from the pinhole pattern PH by disposing a reticle R (FIG. 17) having a pinhole pattern PH at a position where the reticle is disposed, and illuminating the reticle R with light from the light source 1. Can be done. The invention is not limited to this (pinhole pattern reticle), and a pinhole may be formed on the reticle stage 10a to illuminate it, or a point light source may be used. Or on reticle R or reticle stage 1
A region (so-called lemon skin state) where light from the light source 1 is diffused and transmitted is provided on 0a, and the light transmitted through this lemon skin region may be used as a light source for measuring wavefront aberration.

Reticle stage 10a and reticle R
However, it is desirable to have one of the pinhole and the lemon skin region described above. More preferably,
A plurality of pinholes having different sizes are provided, and it is desirable that the pinhole can be appropriately selected according to the purpose of measurement. When the wavefront aberration measuring light is generated using the reticle R, the reticle R constitutes an aberration measuring optical system. This constitutes an optical system.

The projection lens PL is irradiated with the light of the spherical wave formed as described above. The wafer stage control unit 5 drives and controls the wafer stage 3 so that the transmitted wavefront from the projection lens PL is incident on the aberration measurement unit UT which is detachably provided on the side surface of the stage 3 via the attachment / detachment mechanism D. The light transmitted through the projection optical system PL is converted into parallel light by the collimator lens CL. And the minute lens L
Are two-dimensionally arranged.
If the test wavefront of the incident light has a deviation from the ideal wavefront, that is, the wavefront when the projection lens has no aberration, the deviation is reflected on the light-converging position detection unit DET by the ideal wavefront. The condensing position of the wavefront to be detected appears as a position shift with respect to the position. The arithmetic processing unit PC includes individual lenses L of a two-dimensional lens array.
The wavefront aberration of the projection lens PL is calculated based on the positional shift of the converging point.

As described above, at one point on the image plane formed by the projection lens PL, the displacement of each measurement point on the wavefront to be measured with respect to each converging point on the ideal wavefront is measured, so that the aberration of the projection lens PL is calculated. , Spherical aberration and astigmatic difference can be obtained. Also, the unit UT is the projection lens PL
The wafer stage controller 5 drives the wafer stage 3 so as to move to a plurality of points on the image plane. Then, at each of a plurality of points in the image plane of the projection lens PL, the position deviation of each measurement point of the test wavefront with respect to each of the converging points of the ideal wavefront is measured, and the aberration of the projection lens PL is calculated from the measurement results. Can be obtained as coma aberration, curvature of field, distortion, and astigmatism.

Then, the obtained wavefront aberration information of the projection lens PL such as coma, curvature of field, distortion, and astigmatism is fed back to the lens controller LC. The lens control unit LC adjusts the distance between the lens elements constituting the projection lens PL based on the wavefront aberration information and the pressure of the air at the distance to set the amount of aberration of the wavefront transmitted through the projection lens PL within a predetermined range. Keep within.

[Effects of Fifth Embodiment] In the fifth embodiment, the imaging device 11 and the
51 and 52 are mounted. Therefore, the imaging devices 11 and 5
In the methods 1 and 52, it is possible to obtain a good captured image for aberration measurement, and it is possible to further improve the aberration correction accuracy of the exposure apparatus 70.

The unit UT may be detachably provided on the wafer holder 4 or the wafer stage 3, or may be built in the wafer stage 3 or may be provided near the wafer stage 3. May be. In addition, it is preferable to improve the measurement accuracy of the aberration of the projection lens PL by increasing the measurement resolution of the focusing position detection unit DET and the position control accuracy of the wafer stage 3. For example, if the detection resolution of the focusing position detection unit DET is 10
In the case of ２０20 μm, it is preferable to control the wafer stage 3 at a 1 mm pitch in an exposure apparatus that exposes a 5 mm × 5 mm area.

In the present embodiment, the wavefront aberration measuring device UT is configured to be detachable from the wafer stage 3. However, as the attachment / detachment mechanism, a notch is provided in the wafer stage 3, and the notch is engaged with the notch. The engaging portion may be provided on the measuring device so as to be detachable. Further, when making the measuring device UT detachable from the wafer stage 3, a part of the measuring device UT, for example, the collimator lens CL and the lens L is made detachable instead of the entire measuring device UT, and the detection unit DET is fixed to the wafer stage 3. Is also good. Conversely, for example, a collimator lens C
L and the lens L are fixed to the wafer stage 3, and the detection unit DE
T may be made detachable. Alternatively, all of the collimator lens CL, the lens L, and the detection unit DET may be fixed to the wafer stage 3.

In the present embodiment, the wavefront aberration of the projection lens PL is measured in a state of being incorporated in the exposure apparatus, but may be measured before being incorporated in the exposure apparatus. The timing of measuring the wavefront aberration may be any time of wafer exchange, every reticle exchange, or every predetermined time, or any other timing. The measurement accuracy at that time can be selected as described above. In the present embodiment, the projection optical system PL mounted on the exposure apparatus 70
The case where the aberration information is measured will be described. However, the present invention is not limited to this. Imaging is performed when measuring the optical characteristics of an optical system mounted on various inspection devices and measuring devices as an optical system to be measured. Of course, the devices 11, 51, 52 may be used.

<< Supplementary Items of the Embodiment >> In the above-described embodiment, the image pickup apparatus 1 has
1, 51, 52 are reinforced. However, the present invention is not limited to this. For example, as in an imaging device 81 shown in FIG. 18, the mechanical strength of the chip may be increased by leaving the chip peripheral portion 45 at the time of etching.

In the above-described embodiment, the semiconductor substrate 12 is thinned by chemical etching. However, the present invention is not limited to this. For example, the thickness may be reduced by mechanical polishing or anisotropic etching.

Further, in the above-described embodiment, the P-type is the first conductivity type and the N-type is the second conductivity type. However, the present invention is not limited to this. The N-type may be the first conductivity type and the P-type may be the second conductivity type.

The exposure apparatus according to the fourth and fifth embodiments is replaced with a scanning exposure apparatus (for example, USP547) for exposing a reticle pattern by synchronously moving a reticle and a substrate.
3410).

The exposure apparatus according to the fourth and fifth embodiments is a step-and-repeat type exposure apparatus that exposes a reticle pattern while the reticle and the substrate are stationary and sequentially moves the substrate. Is also good.

The exposure apparatus of the fourth and fifth embodiments may be a proximity exposure apparatus that exposes a reticle pattern by bringing a reticle and a substrate into close contact without using a projection optical system.

The application of the exposure apparatus is not limited to an exposure apparatus for manufacturing a semiconductor, but may be, for example, an exposure apparatus for a liquid crystal for exposing a liquid crystal display element pattern on a glass plate or a thin film magnetic head. Widely applicable to the exposure apparatus.

The light sources of the exposure apparatuses in the fourth and fifth embodiments are g-line (436 nm) and i-line (365
nm), KrF excimer laser (248 nm), ArF
Excimer laser (193nm), F2 laser (157n)
m), a harmonic of a metal vapor laser or a YAG laser may be used. Further, a charged particle beam such as an X-ray or an electron beam may be used. For example, when an electron beam is used, a thermionic emission type lanthanum hexaborite (LaB) is used as an electron gun.
6), tantalum (Ta) can be used.

The projection magnification of the exposure apparatus may be not only a reduction system but also an equal magnification system or an enlargement system.

When far ultraviolet rays such as an excimer laser are used as the projection optical system, a material that transmits far ultraviolet rays such as quartz or fluorite is used as a glass material, and an F2 laser or X
When a line is used, a catadioptric or refractive optical system is used (a reticle of a reflective type is used). When an electron beam is used, an electron optical system including an electron lens and a deflector is used as the optical system. It may be used. It goes without saying that the optical path through which the electron beam passes is in a vacuum state.

Further, a linear motor (US Pat. No. 5,623,853 or USP5) is mounted on the wafer stage or reticle stage.
528118), any of an air levitation type using an air bearing and a magnetic levitation type using Lorentz force or reactance force may be used. The stage may be of a type that moves along a guide or a guideless type that does not have a guide.

As the stage driving device, a planar motor that drives a stage by electromagnetic force with a magnet unit having two-dimensionally arranged magnets and an armature unit having two-dimensionally arranged coils facing each other is used. Is also good. In this case, one of the magnet unit and the armature unit may be connected to the stage, and the other of the magnet unit and the armature unit may be provided on the moving surface side of the stage.

The reaction force generated by the movement of the wafer stage is disclosed in Japanese Patent Application Laid-Open No. 8-166475 (US Pat.
28118), a frame member may be used to mechanically escape to the floor (ground). Note that the reaction force generated by the movement of the reticle stage is disclosed in
As described in US Pat. No. 3,330,224 (US S / N 08/416558), a frame member may be used to mechanically escape to the floor (ground).

In the exposure apparatus of this embodiment, the illumination optical system and the projection optical system are incorporated in the exposure apparatus main body to perform optical adjustment, and a reticle stage or a wafer stage composed of a number of mechanical parts is attached to the exposure apparatus main body. To connect wiring and piping, and to make comprehensive adjustments (electrical adjustment, operation check, etc.)
Can be produced. More preferably, the manufacture of the exposure apparatus is desirably performed in a clean room where the temperature, cleanliness, etc. are controlled.

In the case of a micro device such as a semiconductor device, a step for designing the function and performance of the device, a step for producing a reticle based on the design step, a step for producing a wafer from a silicon material, It is manufactured through a step of exposing a reticle pattern on a wafer by an apparatus, a step of assembling a device (including a dicing step, a bonding step, and a package step), an inspection step, and the like. Further, the imaging device of the present invention is applicable not only to the use of the exposure device and the measurement device but also to all systems including the imaging device.

[0115]

According to the first aspect of the present invention, a barrier region is provided in a semiconductor substrate to generate a potential barrier peak. Therefore, it is possible to control the threshold condition when the charge is transferred from the charge storage unit to the charge transfer unit by the peak of the potential barrier, and it is possible to reduce the influence of the semiconductor substrate. As a result, the manufacturing tolerance of the variation in the impurity concentration and the thickness of the semiconductor substrate is widened, and the manufacturing yield of the imaging device can be improved.

In the imaging device according to the second aspect, the barrier region is formed by introducing the first conductivity type impurity into the semiconductor substrate. Therefore, by introducing impurities at the time of manufacturing, it is possible to accurately control the potential barrier peak in the barrier region.

In the imaging device according to the third aspect, the impurity concentration of the semiconductor substrate is set lower than the impurity concentration of the barrier region. Therefore, even if unevenness or variation occurs in the semiconductor substrate during manufacturing, the influence on the characteristics of the entire imaging device can be suppressed to a low level.

In the imaging device according to the fourth aspect, since the barrier region is close to the charge transfer portion, the potential of the potential barrier can be accurately adjusted from the charge transfer portion side.

In the imaging device according to the fifth aspect, since the charge transfer section can be used as an overflow drain, the blooming phenomenon at the time of overexposure can be improved.

According to the manufacturing method of the sixth aspect, it is possible to manufacture a back-illuminated imaging device having a charge storage portion and a barrier region. In particular, in this manufacturing method, the barrier region can be manufactured so as to be in contact with the charge transfer region.
A manufacturing method suitable for manufacturing the imaging device according to claim 4.

According to the manufacturing method of the seventh aspect, it is possible to manufacture a back-illuminated imaging device having a charge storage portion and a barrier region.

According to the manufacturing method of the present invention, it is possible to manufacture a back-illuminated imaging device having a charge storage portion and a barrier region.

In the image pickup apparatus according to the ninth aspect, the signal charge is once collected by the charge storage section in pixel units. Therefore,
The degree of mixing of signal charges between adjacent pixels in the semiconductor substrate is reduced, and the influence of the impurity concentration and thickness of the semiconductor substrate on smear can be reduced. As a result, the manufacturing tolerance of the variation in the impurity concentration and the thickness of the semiconductor substrate is widened, and the manufacturing yield of the imaging device can be improved. In particular, in the image pickup device according to the ninth aspect, substantially one charge storage portion is arranged corresponding to two transfer electrodes or less. Therefore, it is possible to densely arrange the charge storage units, and it is possible to easily realize an increase in the number of pixels of the back-illuminated imaging device (or downsizing of the chip).

In the image pickup device according to the tenth aspect, substantially one charge storage portion is arranged corresponding to two transfer electrodes. Therefore, it is possible to densely arrange the charge storage units, and it is possible to easily realize an increase in the number of pixels of the back-illuminated imaging device (or downsizing of the chip).

In the image pickup apparatus according to the eleventh aspect, since the signal charges are transferred from the charge storage section at every phase interval, there is little possibility that the signal charges are mixed during the charge transfer. Therefore, even if the pixel pitch is smaller than the phase interval, it is possible to sufficiently reduce the occurrence of smear.

In the imaging device according to the twelfth aspect, by providing the charge transfer path with a change in the density of the impurity, it is possible to transfer the signal charge progressively. Further, in this case, by giving a potential gradient in the charge transfer path due to a change in density of the impurity concentration, it is possible to suppress problems such as mixing of signal charges in the charge transfer path.

The measuring device according to the thirteenth aspect uses the imaging device according to any one of the first to fifth and ninth to twelfth aspects. Therefore, it is possible to obtain a high-quality captured image with little variation, and it is possible to measure the aberration or the position of the test object with high accuracy.

The exposure apparatus according to the fourteenth aspect uses the measuring apparatus according to the thirteenth aspect. Therefore, the aberration measurement accuracy or the position measurement accuracy is improved, and the aberration correction or positioning of the exposure pattern can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an imaging device viewed from a second surface side.

FIG. 2 is a diagram showing a cross-sectional structure taken along a line BB ′ shown in FIG.

FIG. 3 is a diagram showing a net impurity concentration at a position AA ′ shown in FIG. 2;

FIG. 4 is a diagram (1/2) illustrating a first manufacturing method.

FIG. 5 is a diagram (2/2) for explaining the first manufacturing method.

FIG. 6 is a diagram (1/2) illustrating a second manufacturing method.

FIG. 7 is a diagram (2/2) for explaining the second manufacturing method.

FIG. 8 is a potential diagram illustrating a charge accumulation operation and a charge transfer operation.

FIG. 9 is a potential diagram illustrating a discharge operation at the time of overflow.

FIG. 10 is a potential diagram illustrating a transfer read operation of a signal charge.

FIG. 11 is a potential diagram illustrating a signal charge transfer read operation.

FIG. 12 is a diagram illustrating an imaging device 51 according to a second embodiment.

FIG. 13 is a diagram illustrating a charge reading operation of the imaging device 51 according to the second embodiment.

FIG. 14 is a diagram illustrating an imaging device 52 according to a third embodiment.

FIG. 15 is a diagram illustrating a transfer read operation of the imaging device 52 according to the third embodiment.

FIG. 16 is a view showing an exposure apparatus 60 according to a fourth embodiment.

FIG. 17 is a view showing an exposure apparatus 70 according to a fifth embodiment.

FIG. 18 is a diagram illustrating another reinforcing structure of the imaging device.

FIG. 19 is a diagram showing a conventional example of a back-illuminated imaging device.

FIG. 20 is a diagram illustrating a third manufacturing method.

[Explanation of symbols]

 11, 51, 52, 64a-b Imaging device 12 Semiconductor substrate 12a First epitaxial layer 13 CCD diffusion layer 14 Gate oxide film 15 Transfer electrode 16 Vertical transfer unit 17 Charge storage unit 17a Buried channel stop 18 Depletion prevention layer 19 Barrier region Reference Signs List 20 bonding pad 21 support substrate 24 horizontal CCD section 30 P + type substrate 31 P− type epitaxial layer 53 implantation area 60, 70 exposure apparatus 61 wafer stage 62 semiconductor wafer 63 exposure section 63a reticle 63b reticle stage 65 position detection section 66 position control section 102 Semiconductor substrate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M118 AA05 AB01 BA12 DB01 DB03 DB06 DB08 EA01 FA06 FA21 FA26 FA32 FA38 GA02 HA30 5C024 AX01 AX11 AX16 CX13 CY47 EX25 GY06 JX21

Claims (14)

[Claims] 1. A semiconductor substrate of a first conductivity type, arranged on a second surface side of the semiconductor substrate opposite to the first surface,
A charge accumulation unit of a second conductivity type different from the first conductivity type, for accumulating signal charges generated by energy rays incident from the second surface side in pixel units; and the semiconductor facing the charge accumulation unit. A charge transfer unit provided on the first surface side of the base for transferring and reading the signal charge; charge transfer means for transferring the signal charge stored in the charge storage unit to the charge transfer unit; A transfer path for the signal charge formed between an accumulation unit and the charge transfer unit is provided at least in part of the transfer path. An image pickup device comprising a barrier region for ensuring the complete transfer of the signal charge by removing peaks of the potential barrier sometimes by the charge transfer means. 2. The imaging device according to claim 1, wherein the barrier region is a region formed by introducing the first conductivity type impurity into the semiconductor substrate. 3. The imaging device according to claim 2, wherein an impurity concentration introduced into the barrier region is set higher than an impurity concentration of the semiconductor substrate. 4. The imaging device according to claim 1, wherein the barrier region is provided in contact with the charge transfer unit. 5. The imaging device according to claim 1, wherein the barrier region is configured such that the potential barrier at the time of non-charge transfer is generated between adjacent charge accumulation units. than,
An imaging apparatus characterized by being set low in view of the polarity of signal charges. 6. A step of forming a first conductivity type epitaxial layer on a first surface side of a substrate, and introducing the first conductivity type impurity from the first surface side of the epitaxial layer to form a barrier region. And a second step different from the first conductivity type in the epitaxial layer.
Introducing a conductivity type impurity, forming a charge transfer portion in a region on the first surface side shallower than the barrier region when viewed from the first surface side, and removing at least a part of the substrate; Thinning the second surface side opposite to the first surface; introducing the second conductivity type impurity from the second surface side;
Forming a charge storage portion arranged in pixel units. 7. A step of forming a first epitaxial layer of a first conductivity type on a first surface side of a substrate; and forming a second epitaxial layer different from the first conductivity type from the first surface side of the first epitaxial layer. Forming a charge accumulation portion arranged in pixel units by introducing a conductivity type impurity; and a region on the first surface side of the first epitaxial layer which is shallower than the charge accumulation portion when viewed from the first surface side. And the first
Forming a barrier region by introducing a conductivity type impurity; and forming the first epitaxial layer on the first surface side of the first epitaxial layer.
Forming a conductive type second epitaxial layer; and forming the second epitaxial layer on the first surface side of the second epitaxial layer.
Forming a charge transfer portion by introducing a conductive type impurity; and removing at least a part of the substrate to reduce the thickness of a second surface side opposite to the first surface side. A method for manufacturing an imaging device, which is characterized by the following. 8. A manufacturing method for manufacturing a back-illuminated imaging device having a barrier region, comprising: forming a first epitaxial layer of a first conductivity type on a first surface side of a substrate; A step of introducing an impurity of a second conductivity type different from the first conductivity type from the first surface side of the layer to form a charge storage portion arranged in pixel units; On one side, the first
Forming a conductive type second epitaxial layer; and forming the first epitaxial layer on the first surface side of the second epitaxial layer.
Forming a barrier region by introducing impurities of a conductivity type; and forming the second region in the second epitaxial layer on the first surface side shallower than the charge storage portion when viewed from the first surface side.
Forming a charge transfer portion by introducing a conductive type impurity; and removing at least a part of the substrate to reduce the thickness of a second surface side opposite to the first surface side. A method for manufacturing an imaging device, which is characterized by the following. 9. A semiconductor substrate of a first conductivity type, arranged on a second surface side of the semiconductor substrate opposite to the first surface,
A charge accumulation unit of a second conductivity type different from the first conductivity type for accumulating signal charges generated by energy rays incident from the second surface side in pixel units; and the semiconductor substrate facing the charge accumulation unit A charge transfer path that is formed on the first surface side of the device and is a path for transferring and reading out the signal charges; and a transfer electrode that applies a transfer voltage to the charge transfer path. An imaging apparatus, wherein the transfer electrodes are periodically arranged at a rate of substantially two or less with respect to one charge accumulation unit along a direction. 10. The image pickup device according to claim 9, wherein the transfer electrodes are periodically cycled at a ratio of substantially two transfer electrodes to one charge storage portion along the charge transfer direction of the charge transfer path. An imaging device, comprising: 11. The imaging device according to claim 9, wherein the signal charge is transferred from the charge storage unit to the charge transfer path at every phase interval of the transfer electrode, and a phase of a transfer position of the signal charge is transferred. Division transfer means for transferring the signal charges for one screen in a plurality of times while shifting, and each time the signal charges are transferred to the charge transfer path by the division transfer means, the transfer electrode is multi-phase driven, An image pickup apparatus comprising: a division transfer unit that reads out signal charges for one screen in a plurality of times. 12. The imaging device according to claim 10, wherein the charge transfer path is formed such that a change in density of an impurity concentration is periodically formed for each electrode interval of the transfer electrode, and the charge transfer path is driven by two-phase driving of the transfer electrode. An image pickup device for progressively transferring a signal charge. 13. An imaging apparatus according to claim 1, further comprising: an aberration measurement unit configured to measure an aberration of the object based on an image of the object captured by the imaging apparatus. A measuring unit that performs at least one of position measurement. 14. An exposure unit for projecting an exposure pattern onto an exposure target, a measuring device according to claim 13, and correction of aberration of the exposure unit and position control of an exposure position based on a measurement output of the measuring device. An exposure apparatus comprising: a control unit that performs at least one of the steps.