JP2000036590A - Solid-state image pickup element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture a small-sized and weight reduced solid-state image pickup element, having improved characteristic, efficiency and productivity, at low cost. SOLUTION: A charge coupling element, having an n-type photoelectric conversion region 4, which is locally provided in the vicinity of the surface of a p-type p- region 2 on a silicon substrate 1 and a charge transfer region 6, is contained in the solid-state image pickup element. A gate insulating film 8, which is provided on the surface of the silicon substrate 1 covering the photoelectric conversion region 4 and the charge transfer region 6, a plurality of charge transfer electrodes 9, having light shielding property, which is provided in the region containing the part right above the charge transfer region 6 on the gate insulating film 8, a charge transfer electrode 10, having different quality of material, provided above the charge transfer electrode 9, and a light shielding substance 12, provided on the circumference of the electrode containing the part between the adjacently located charge transfer electrodes 9 and 10 on the gate insulating film 8, are provided. As a result, the occurrence of smear can be suppressed without providing a light shielding film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device such as a CCD type and the like, which is fine and highly sensitive, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as this type of solid-state imaging device,
For example, those having a configuration as shown in FIGS. However, FIG. 3A is related to a local plan view of the solid-state imaging device, and FIG.
(C) relating to a side sectional view in the A 'direction
FIG. 4A relates to a side sectional view in the BB ′ direction of FIG. 5A, and FIG. 5D relates to a side sectional view in the CC ′ direction of FIG.

In this solid-state image pickup device, a charge transfer electrode 9 and another charge transfer electrode 10 made of a material different from the charge transfer electrode 9 are provided in parallel on a gate insulating film 8, and these charge transfer electrode 9 and another charge transfer electrode 10 are provided. Gate insulating film 8 so as to cover the surface of
An insulating film 11 is formed thereon, and the periphery of the insulating film 11 covering the charge transfer electrode 9 and another charge transfer electrode 10 is covered with a light shielding film 15.
It is a configuration covered with.

FIG. 12 is a cross-sectional view showing a manufacturing process of the solid-state imaging device in the order of steps in the direction DD ′ (portion sandwiched between upper and lower photodiodes) in FIG. FIG. 11A relates to the initial process, FIG. 10B relates to the middle process, and FIG. 10C relates to the latter process.

First, in an initial step, as shown in FIG. 12A, a charge transfer electrode 9 and another charge transfer electrode 10 are arranged on a gate insulating film 8, and then these charge transfer electrodes 9 are formed.
An insulating film 11 is formed on the gate insulating film 8 so as to cover the surface of another charge transfer electrode 10.

Next, in the middle stage process, as shown in FIG. 12B, a metal such as aluminum or tungsten is formed so that the periphery of the insulating film 11 covering the charge transfer electrode 9 and another charge transfer electrode 10 is included. Cover the gate insulating film 8 with a light shielding film 15.

Further, in a later step, as shown in FIG. 12C, patterning is performed using a photoresist as a mask to remove an extra portion of the light shielding film 15. In this way, a solid-state imaging device having a configuration in which the light-shielding film 15 is provided on the insulating film 11 covering the charge transfer electrode 9 and another charge-transfer electrode 10 is obtained. In addition, a step is formed at a place where the insulating film 11 between the other charge transfer electrodes 10 is adjacent.

Incidentally, as a known technique relating to such a solid-state image pickup device and its manufacture, for example, Japanese Patent Laid-Open No.
The solid-state imaging device disclosed in Japanese Patent Application Laid-Open No. 161973, the solid-state imaging device disclosed in Japanese Patent Application Laid-Open No. 8-125166 and its manufacturing method, the solid-state imaging device disclosed in Japanese Patent Application Laid-Open No. 9-92213 and its manufacturing method, Kaihei 9-2705
No. 06, a solid-state imaging device and a method for manufacturing the same.

[0009]

In the case of the solid-state imaging device described above, a light-shielding film is separately provided on an insulating film covering the charge transfer electrode and another charge transfer electrode. Since the step of the light-shielding film formed at the place where the insulating film between the charge transfer electrodes is adjacent becomes large, the characteristics and performance such as high speed, low power consumption, and high integration are improved, and the size and weight are reduced. There is a problem that it is difficult to measure.

In addition, in such a configuration, the number of steps at the time of manufacturing is increased, so that the yield is deteriorated and the productivity is not improved.
As a result, there is also a problem that the cost is increased and the reliability of the product is not improved.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and its technical problems are to improve the characteristics, performance and productivity, and to reduce the size and size of the device which can be easily manufactured at low cost. An object of the present invention is to provide a light-weight solid-state imaging device and a method for manufacturing the same.

[0012]

According to the present invention, there is provided a solid-state imaging device including a charge-coupled device having a photoelectric conversion region and a charge transfer region locally provided near a surface of a semiconductor substrate. A gate insulating film made of an insulator provided on the surface of the semiconductor substrate so as to cover the charge transfer region; and a plurality of light-shielding members provided in a region on the gate insulating film including a portion directly above the charge transfer region. A solid-state imaging device having a charge transfer electrode and a light-blocking substance provided around the electrode including at least a plurality of charge transfer electrodes adjacent to each other on the gate insulating film is obtained.

In this solid-state imaging device, an insulating film is provided between the side surfaces of the plurality of charge transfer electrodes and the light shielding material, and another charge transfer electrode of a different material is provided on the plurality of charge transfer electrodes. In addition, the insulating film is formed continuously on the gate insulating film so as to cover the surface of another charge transfer electrode, and the light-shielding substance buryes a groove formed between adjacent ones in the insulating film. And a second portion including a portion provided near the side wall of the charge transfer electrode and another charge transfer electrode facing the groove in the first portion and the insulating film. It is preferable that the cross section of the side wall portion is formed in a curved line so that the charge transfer electrode and the insulating film cannot be seen through the charge transfer region.

Further, in any one of these solid-state imaging devices, the light-shielding substance has an original shape and an additional portion selectively added to the original shape. A contact opening is provided at a predetermined position on another charge transfer electrode in the film, and a light-shielding material electrically connected to the charge transfer electrode through another charge transfer electrode in the contact opening on the insulating film on the insulating film. It is preferable that the wiring according to (1) is arranged, and the wiring is divided into two or more and arranged.

On the other hand, according to the present invention, the first
An element forming step of locally forming a second conductivity type photoelectric conversion region and a charge transfer region near the surface of the conductivity type region to obtain a charge coupled device; and a surface of the semiconductor substrate covering the photoelectric conversion region and the charge transfer region. A gate insulating film forming step of forming a gate insulating film made of an insulator thereon, and a charge transfer electrode for forming a plurality of light-shielding charge transfer electrodes in a region including a portion directly above the charge transfer region on the gate insulating film A method for manufacturing a solid-state imaging device including a forming step and a light-shielding substance forming step of burying a light-shielding substance around electrodes including at least a plurality of charge transfer electrodes adjacent to each other on the gate insulating film is obtained. .

On the other hand, according to the present invention, the first
An element forming step of locally forming a second conductivity type photoelectric conversion region and a charge transfer region near the surface of the conductivity type region to obtain a charge coupled device; and a surface of the semiconductor substrate covering the photoelectric conversion region and the charge transfer region. A gate insulating film forming step of forming a gate insulating film made of an insulator thereon, and a charge transfer electrode for forming a plurality of light-shielding charge transfer electrodes in a region including a portion directly above the charge transfer region on the gate insulating film A forming step, an insulating film forming step of covering the plurality of charge transfer electrodes with the insulating film, and a light-shielding substance forming step of burying the light-shielding substance in a portion of the insulating film around the electrodes including at least between adjacent ones. Thus, a method for manufacturing a solid-state imaging device having the same is obtained.

In the method for manufacturing a solid-state imaging device, the step of forming a charge transfer electrode includes a step of forming an electrode double layer for forming another charge transfer electrode having a different material on a plurality of charge transfer electrodes; In the step, it is preferable to continuously form an insulating film on the gate insulating film so as to cover the surface of another charge transfer electrode.

In any one of these methods for manufacturing a solid-state imaging device, in the step of forming a charge transfer electrode, the side etching property of the etching condition is switched during the patterning of the charge transfer electrode and another charge transfer electrode. Forming a concave and convex partly on the surface of the groove formed between adjacent ones of the transfer electrode and the other charge transfer electrode to make the cross section of the groove a curve, or in the charge transfer electrode forming step, Forming a groove between adjacent ones of the charge transfer electrode and another charge transfer electrode by making the electrode and another charge transfer electrode different shapes, and forming a groove between the charge transfer electrode and another charge transfer electrode. A groove etching step of forming at least one of them side-etching to partially form irregularities on the surface of the groove and making the cross section of the groove a curve. The preferable.

Further, in any one of these methods of manufacturing a solid-state imaging device, in the light-shielding substance forming step, the light-shielding substance is formed as a preliminary step to form an original form, and then as a subsequent step, selectively with respect to the original form. In the step of forming a light-shielding substance, a contact opening is formed at a predetermined position on another charge transfer electrode in the insulating film, and then the contact opening is formed on the insulating film. It is preferable to provide a wiring made of a light-shielding substance that is electrically connected to the charge transfer electrode through the charge transfer electrode.

[0020]

In the solid-state imaging device according to one example of the present invention, since the light-shielding substance is provided around the charge transfer electrodes having light-shielding properties, including between adjacent ones, light is transferred from the gap to the charge-coupled device. The occurrence of smear due to leakage into the charge transfer region is reduced. As a result, since there is no need to separately provide a light-shielding film on the charge transfer electrode and another charge transfer electrode, the number of manufacturing steps can be reduced, the manufacturing can be easily performed, and the flatness of the structure can be ensured.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The solid-state imaging device of the present invention and a method for manufacturing the same will be described in detail with reference to the drawings.

FIG. 1 shows the basic configuration of a solid-state imaging device according to a first embodiment of the present invention. FIG. 1 (a) relates to a local plan view thereof, and FIG. A) AA
(C) relates to a side cross-sectional view in the direction BB 'in FIG. (A), and FIG. (D) relates to a CC-direction in FIG. (A). (E) is a side sectional view of FIG.
It relates to a side sectional view in the -D 'direction.

[0023] p of the solid-state imaging device, the first conductivity type in the silicon substrate 1 is a semiconductor substrate (p-type) ^- region 2
It includes a charge-coupled device having a second conductivity type (n-type) photoelectric conversion region 4 and a charge transfer region 6 provided locally near the surface, and covers the photoelectric conversion region 4 and the charge transfer region 6 with silicon. A gate insulating film formed of an insulator provided on a surface of the substrate, and a plurality of charge transfer electrodes provided in a region including a portion directly above the charge transfer region on the gate insulating film and having a light shielding property; 9 and the charge transfer electrode 9
Another charge transfer electrode 10 having a different material provided thereon;
The light-shielding substance 12 is provided on the gate insulating film 8 around the charge transfer electrodes 9 and 10 including between adjacent ones of the charge transfer electrodes 9 and 10. In the charge coupled device,
A p-type region 5 is formed immediately below the charge transfer region 6, and ap ⁺ region 7 is formed immediately above the photoelectric conversion region 4, between the p-type region 5 and the charge transfer region 6 and the photoelectric conversion region 4 and the p ⁺ region 7. Is formed with ap ⁺ element isolation region 3.

In this solid-state imaging device, when the incident light hν is incident, charges are generated in the photoelectric conversion region 4, and the charges are transferred to the charge transfer region 6 by applying a positive voltage to the charge transfer electrode 9. Further, the operation is performed so as to perform the charge transfer by changing the voltage applied to each charge transfer electrode 9.

When manufacturing such a solid-state imaging device,
An element forming step of locally forming a second conductivity type (n-type) photoelectric conversion region 4 and a charge transfer region 6 near the surface of the first conductivity type (p-type) region of the silicon substrate 1 to obtain a charge-coupled device A gate insulating film forming step of forming a gate insulating film 8 made of an insulator on the surface of the silicon substrate 1 so as to cover the photoelectric conversion region 4 and the charge transfer region 6; A charge transfer electrode forming step of forming a plurality of charge transfer electrodes having light shielding properties in a region including a portion directly above, and forming at least a plurality of charge transfer electrodes on the gate insulating film between adjacent ones of the plurality of charge transfer electrodes; A light-shielding substance forming step of embedding the light-shielding substance 12 around the electrode including the grooved portion. However, in the charge transfer electrode forming step, an electrode two-layer forming step of forming another charge transfer electrode 10 having a different material on the plurality of charge transfer electrodes 9 is performed. In this case, in the light-shielding substance forming step, as described above, the light-shielding substance 12 is provided on the gate insulating film 8 at least around the charge transfer electrodes 9 and 10 including between adjacent ones.

More specifically, when manufacturing a base diffusion region in the silicon substrate 1 in the charge-coupled device formed in the device forming step, a p-type impurity such as boron is introduced into the surface of the n-type silicon substrate 1. After the formation of the p ⁻ region 2, the n-type photoelectric conversion region 4, the p ⁺ element isolation region 3, the n-type charge transfer region 6, the p-type region 5, and the p ⁺ region 7 are sequentially formed. . Each region may be formed by appropriately combining ion implantation using a photoresist as a mask, gas diffusion, solid diffusion, and the like, and may be appropriately selected according to a known technique. It should be noted that, besides those described here, there are also various types of solid-state image sensing devices disclosed by various companies and research institutes. The configuration is applicable.

Next, in a gate insulating film forming step, a gate insulating film 8 made of an insulator is formed on the surface of the silicon substrate 1 so as to cover the photoelectric conversion region 4 and the charge transfer region 6. A single-layer or multilayer insulator such as silicon oxide or silicon nitride may be used as the insulator by a thermal oxidation method, a chemical vapor deposition method (CVD method), or the like.

Further, in the step of forming the charge transfer electrode, a plurality of light-shielding charge transfer electrodes 9 are formed in a region including the portion directly above the charge transfer region 6 on the gate insulating film 8. For example, a single layer such as polycrystalline silicon, metal silicide of silicon, a metal film, or a multilayer of a combination of a plurality of single layers may be used. If the charge transfer electrode 9 has a low light-shielding property, light passes through the charge transfer electrode 9 and leaks into the charge transfer region 6 to generate smear.
It is necessary to have a light-shielding performance that satisfies the smear performance required for a solid-state imaging device.

Further, another charge transfer electrode 10 of a different material is formed on the charge transfer electrode 9 in the electrode two-layer forming step. For example, a polycrystalline polysilicon film having a thickness of 100 to 500 nm is formed on the charge transfer electrode 9. The charge transfer electrode 10 has a thickness of 1
A case where a tungsten film having a thickness of 00 to 500 nm is used to form a two-layer structure can be exemplified. The impurities contained in the polycrystalline polysilicon film of the charge transfer electrode 9 include phosphorus, but may be arsenic, boron, antimony, or the like, and may have a concentration of about 1E16 atm / cm ^{3 to} 5E20 atm / cm ^{3 and} a channel potential. It may be determined in consideration of electrical characteristics such as the above. Other examples of the material of the charge transfer electrode 10 include metal silicide such as titanium, platinum, and cobalt, aluminum, copper, and other metals alone or a combination of alloys. The selection may be made in consideration of the electrical characteristics and the like of the imaging element.

Subsequently, in the light-shielding substance forming step, the light-shielding substance 12 is formed around the electrodes including the grooves (inter-electrode gaps) formed between the adjacent ones of the charge transfer electrodes 9 and 10 on the gate insulating film 8. Buried.

FIG. 2 is a side cross-sectional view showing a main part manufacturing process (light-shielding substance forming process) of the solid-state imaging device in the DD ′ direction (portion sandwiched between upper and lower photodiodes) in FIG. FIG. 7A shows an initial process, FIG. 7B shows a middle process, and FIG. 7C shows a late process.

In the initial step, as shown in FIG. 2A, the two layers of the charge transfer electrodes 9 and 10 are patterned by etching using the photoresist 13 as a mask. However, instead of this, another film may be patterned using the photoresist 13 as a mask, and the charge transfer electrodes 9 and 10 may be etched using this as a mask. In the middle-stage process, as shown in FIG. 2B, after the photoresist 13 is removed, the insulating light-shielding substance 12 is covered with the gate insulating film 8 so as to include the periphery of the charge transfer electrodes 9 and 10.
Formed over the entire surface of the substrate. As the light-shielding substance 12, for example, a resin containing a dye or a pigment may be used. In the latter step, as shown in FIG. 2C, the light-shielding substance 12 other than the area around the charge transfer electrodes 9 and 10 is removed by an anisotropic etch-back method.

Thus, the solid-state imaging device according to the first embodiment is completed. However, if light shielding is not required around the electrodes other than the grooves formed between the adjacent charge transfer electrodes 9 and 10, a middle stage process is required. After the light-shielding substance 12 is formed on the entire surface of the gate insulating film 8 in this step, an isotropic etch may be performed in a later step, and in such a case, the state is as shown in FIG.

That is, the light-shielding substance 12 in the solid-state image pickup device of the first embodiment embeds a groove formed between adjacent ones of the charge transfer electrodes 9, 10, and the groove and the charge transfer electrode opposed thereto. The present invention can be applied to both the case where it is provided near the side walls of 9 and 10 (around the electrodes).

FIG. 4 shows the basic configuration of a solid-state imaging device according to Embodiment 2 of the present invention. FIG. 4A is related to a local plan view, and FIG. A) AA
(C) relates to a side cross-sectional view in the direction BB 'in FIG. (A), and FIG. (D) relates to a CC-direction in FIG. (A). It relates to a side sectional view in FIG.

This solid-state imaging device is different from that of the first embodiment in that the insulating film 11 is formed on the entire surface of the gate insulating film 8 so as to be interposed between the charge transfer electrodes 9 and 10 and the light-shielding substance 12.
Is provided. That is, the insulating film 11 here is continuously formed on the gate insulating film 8 so as to cover the surfaces of the charge transfer electrodes 9 and 10 (more precisely, the side surfaces of the charge transfer electrodes 9 and 10 and the surface of the charge transfer electrode 10). Have been.

In the case of this solid-state imaging device, the surfaces of the charge transfer electrodes 9 and 10 are covered with an insulating film 11 and the adjacent ones of the charge transfer electrodes 9 and 10 are insulated by the insulating film 11. The light-shielding substance 12 is not limited to an insulating one, and for example, a metal having a high light-shielding property can be used.

In the case of manufacturing such a solid-state imaging device,
An element forming step of locally forming a second conductivity type (n-type) photoelectric conversion region 4 and a charge transfer region 6 near the surface of the first conductivity type (p-type) region of the silicon substrate 1 to obtain a charge-coupled device A gate insulating film forming step of forming a gate insulating film 8 made of an insulator on the surface of the silicon substrate 1 so as to cover the photoelectric conversion region 4 and the charge transfer region 6; A charge transfer electrode forming step of forming a plurality of charge transfer electrodes 9 having light shielding properties in a region including a portion directly above, an insulating film forming step of covering the plurality of charge transfer electrodes 9 with an insulating film 11, And a light-shielding substance forming step of burying the light-shielding substance 12 around the electrode including the groove formed between the adjacent ones. However, in the charge transfer electrode forming step, an electrode two-layer forming step of forming another charge transfer electrode 10 having a different material on the plurality of charge transfer electrodes 9 is performed. In this case, in the light-shielding substance forming step, the light-shielding substance 12 is provided at least around the electrode including the groove formed between adjacent ones of the insulating film 11.

More specifically, the steps from the process of manufacturing the underlying diffusion region in the silicon substrate 1 in the charge coupled device formed in the device forming process to the process of forming the charge transfer electrode are performed in the same manner as in the first embodiment. , Followed by photoresist 1
3 is removed, the charge transfer electrodes 9 and 10 are covered with an insulating film 11 having a thickness of about 30 to 100 nm as an insulating film forming step, and at least between adjacent ones of the insulating film 11 as a light shielding material forming step. The light-shielding substance 12 is buried around the electrode including the formed groove.

FIG. 5 shows a process of manufacturing a main part of this solid-state imaging device (an insulating film forming process and a light shielding material forming process).
(A) is a side sectional view in the DD ′ direction (portion sandwiched between upper and lower photodiodes), and is shown in the order of steps, in which (a) relates to an initial step, and (b) shows a middle step. FIG. 4C relates to the latter stage process.

In the initial step (insulating film forming step), as shown in FIG. 5A, the surfaces of the charge transfer electrodes 9 and 10 and the gate insulating film 8 are covered with the insulating film 11, The film thickness of 11 needs to be such that the light-shielding substance 12 can enter there between the charge transfer electrodes 9 and 10 even after they are formed between adjacent ones. In the middle step (the first step of the light-shielding substance forming step), the gate insulating film 8 is covered with the light-shielding substance 12 as shown in FIG. As the light-shielding substance 12, for example, a material having an excellent light-shielding property such as aluminum or tungsten is used, and a groove formed between adjacent ones of the insulating film 11 is formed by a method having an excellent coverage such as a low pressure CVD method. Buried. In the latter step (later step of the light-shielding substance forming step), as shown in FIG. 5C, the light-shielding substance 12 other than around the charge transfer electrodes 9 and 10 is removed by an anisotropic etch-back method.

Thus, the solid-state imaging device according to the second embodiment is completed. In this solid-state imaging device, the insulating film 11 between the light-shielding substance 12 and the charge transfer electrode 10 is a vertical plane, but the thickness of the insulating film 11 is much smaller than the light wavelength of 350 to 80 nm. , The light passing here is small,
The effect of smear is small.

The light-shielding substance 12 in the solid-state imaging device of the second embodiment is also buried in a groove formed between adjacent ones of the insulating film 11 and when the groove in the insulating film 11 and the charge transfer opposing the groove are formed. The present invention can be applied to both cases where it is provided near the side walls of the electrodes 9 and 10 (around the electrodes).

FIG. 6 is a local plan view showing a basic configuration of a solid-state imaging device according to Embodiment 3 of the present invention. This solid-state imaging device is different from that of the second embodiment in that the cross section of the side wall portion is formed in a curved line so that the charge transfer electrode 10 and the insulating film 11 cannot see through the charge transfer region 6. . That is, in this solid-state imaging device, the charge transfer electrodes 9 and 10
The charge transfer region 6 cannot be seen through the insulating film 11 on the side wall portions of the charge transfer electrodes 9 and 10 because the cross section of the insulating film 11 on the side surface portion is curved. This can reduce smear occurring from directly above the charge transfer region 6 through the insulating film 11.

When manufacturing such a solid-state imaging device,
The patterning may be performed so that at least the side wall of the charge transfer electrode 10 (both may include the charge transfer electrode 9 may be a target) is not linear. At the time of patterning, the side etch condition of etching is changed to form a step on the side wall. For example, there is a case in which a layer that easily enters side etching is formed in a part of the charge transfer electrode 10 and side etching is performed in this layer.

That is, in the former method, when the charge transfer electrodes 9 and 10 are patterned in the step of forming the charge transfer electrodes, the side etching property of the etching conditions is switched in the middle so that adjacent ones of the charge transfer electrodes 9 and 10 can be connected to each other. Irregularities are formed partially on the surface of the groove formed between them (formed between the charge transfer electrodes 10), so that the cross section of the groove is curved. In the latter method, charge transfer is performed in the charge transfer electrode forming step. Forming a groove between adjacent ones of the charge transfer electrodes 9 and 10 by forming the electrodes 9 and 10 in different shapes; and forming a groove between the adjacent charge transfer electrodes 9 and 10 by partially etching the charge transfer electrode 10 to partially uneven the surface of the groove. And a groove etching step of making the cross section of the groove a curve.

FIG. 7 shows the main steps of manufacturing the solid-state imaging device (charge transfer electrode forming step, insulating film forming step, and light shielding material forming step) in the case of adopting the former method.
(A) is a side sectional view in the ′ direction (portion sandwiched between the upper and lower photodiodes), which is shown in the order of steps.
FIG. 4B relates to the first half of the etching step in the charge transfer electrode forming step, FIG. 6B relates to the second half of the etching step in the charge transfer electrode forming step, FIG. 6C relates to the insulating film forming step, and FIG. ) Relates to the first step of the light-shielding substance forming step, and FIG. 10E relates to the second step of the light-shielding substance forming step.

First, in the pre-etching step, as shown in FIG. 7A, the gate insulating film 8 having the diffusion region formed thereon is formed.
With the photoresist 13 serving as a mask in the state where the charge transfer electrodes 9 and 10 are deposited, etching is performed while changing the anisotropy on the way, and the upper portion of the charge transfer electrode 10 is etched. Thereafter, in the later stage of the etching, as shown in FIG. 7B, the remaining portion is etched while changing the anisotropy. In the insulating film forming step, as shown in FIG. 7C, the insulating film 11 is continuously formed on the gate insulating film 8 so that the surfaces of the charge transfer electrodes 9 and 10 are covered with the photoresist 13 removed. Formed. Thereafter, in the first step of the light-shielding substance forming step, the gate insulating film 8 is covered with the light-shielding substance 12 as shown in FIG. Further, as shown in FIG. 7E, the charge transfer electrodes 9, 10 are formed by an anisotropic etch-back method in a later step of the light-shielding substance forming step.
The light-shielding substance 12 other than around the electrode is removed.

Here, the case where the shape of the insulating film 11 is curved by changing the etching conditions in the middle has been described. Instead, the charge transfer electrode 10 is formed by two or more different types of multilayers, and the different layers are formed. The shape of the side wall portion of the groove may be made curved by utilizing the difference in side etching rates of the above.

In the case of this solid-state image pickup device, the insulating film 11 has a curved surface, so that no light passes through the light-shielding substance 12 buried in the groove without passing through the light, and the smear characteristic is improved.

That is, in the solid-state imaging device here, since the insulating film 11 is bent along the side surfaces of the charge transfer electrodes 9 and 10, the light is transferred to the charge transfer electrodes 9 and 1 sandwiching the insulating film 11.
The light is reflected several times by the light-blocking material 12 and the light-shielding substance 12, and is attenuated every time the light is reflected. In this case, if the radius of curvature of the side surfaces of the charge transfer electrodes 9 and 10 is as small as possible, light reaching the charge transfer region 6 can be further reduced. Further, it is preferable that the charge transfer electrodes 9, 10 and the light-shielding substance 12 are substances having a low surface reflectance. Further, a dedicated anti-reflection film for preventing reflection may be formed between the insulating film 11 and the charge transfer electrodes 9, 10 and the light-shielding substance 12.

FIG. 8 is a local plan view showing a basic configuration of a solid-state imaging device according to Embodiment 4 of the present invention. This solid-state imaging device has an additional portion of the light-shielding substance 12 ′ selectively added to the original form, except that the light-shielding substance 12 is formed as an original form as compared with that of the second embodiment. Are different.

When manufacturing such a solid-state imaging device,
Except for the light-shielding substance forming step, the same procedure as in Example 2 is carried out. In the light-shielding substance forming step, the light-shielding substance 12 as the original form is formed as a preliminary step, and then the light-shielding substance 12 in the original form is formed as a subsequent step. Selective light-shielding substance 1
2 'may be additionally formed.

FIG. 9 is a side sectional view in the DD ′ direction (portion sandwiched between upper and lower photodiodes) of FIG. FIG. 3A shows the first stage of the light-shielding material forming step, and FIG. 2B shows the second stage of the light-shielding material forming step.

As shown in FIG. 9A, in the first step of the light-shielding substance forming step, as in the case of the second embodiment, the light-shielding substance 12 other than around the charge transfer electrodes 9 and 10 is formed.
The light-shielding substance 12 of the original form is obtained by removing the material, and a portion exposed on the surface of the light-shielding substance 12 of the original form as shown in FIG. The light shielding material 12 'as an additional portion is additionally formed so that the groove is completely covered. As a result, the entirety of the insulating film 11 on the side wall portion of the groove becomes the light-shielding substance 1.
2 and 12 ′, and light passes through the insulating film 11.
To the charge transfer region 6 can be sufficiently prevented.

When the solid-state image pickup device of the fourth embodiment is applied to the solid-state image pickup device of the third embodiment for manufacturing, the charge transfer electrode 10 is a multilayer film in which the etch rate of the middle layer is higher than that of the upper and lower layers. Then, a recess may be provided on the side wall of the charge transfer electrode 10 by side etching. There are many combinations of the multilayer film and the etching conditions that satisfy such conditions. For example, when the charge transfer electrode 10 has a three-layer structure, the lowermost layer is, for example, 1E1
8 atm / cm ³ low phosphorus concentration polysilicon, an intermediate layer made of, for example, 3E20 atm / cm ³ high phosphorus concentration polysilicon, an uppermost layer made of a tungsten film, and patterning these, followed by side etching with a dilute nitric acid solution or the like. . At this time, since the high-phosphorus-concentration polysilicon of the intermediate layer is etched at the fastest rate, a depression is formed in the side wall. Next, the insulating film 11 and the light-shielding substance 12 are formed in the same manner as in the third embodiment, and finally, an additional portion of the light-shielding substance 12 ′ as shown in FIG. 9B may be formed.

Here, as in the case of the second embodiment, the light-shielding substances 12 and 12 'in the solid-state imaging device are also different from those in the case where the groove formed between adjacent ones in the insulating film 11 is buried. The present invention can be applied to both the case where it is provided in a portion near the side wall (around the electrode) of the groove portion of the film 11 and the charge transfer electrodes 9 and 10 facing the groove portion.

In the solid-state imaging devices of the first to fourth embodiments described above, the light-shielding substances 12, 12 'can be formed in a self-aligned manner around the charge transfer electrodes 9, 10, so that the area of the photodiode can be increased. As a result, sensitivity can be increased and smear can be reduced.
Further, there is no need to separately form a light-shielding film on the charge transfer electrodes 9 and 10, whereby each solid-state imaging device can be manufactured at low cost while reducing the number of steps with a structure having few steps.

FIGS. 10A and 10B show a basic configuration of a solid-state image pickup device according to Embodiment 5 of the present invention, where FIG. 10A is related to a local plan view, and FIG. 10B is AA 'of FIG. It relates to a side sectional view in the direction. In the solid-state imaging device, a contact opening 14 is provided at a predetermined position on the charge transfer electrode 10 in the insulating film 11 as compared with the solid-state imaging device of the second embodiment. 1 in that a wiring 16 divided into two or more lines electrically connected to the charge transfer electrode 9 via the charge transfer electrode 10 is provided.

When manufacturing such a solid-state imaging device,
In the light-shielding material forming step, a contact opening 14 is provided at a predetermined position on the charge transfer electrode 10 in the insulating film 11, and then the contact opening 14 is electrically connected to the charge transfer electrode 9 via the charge transfer electrode 10 on the insulating film 11. Two or more wirings 16 as light-shielding substances that are electrically connected may be provided on the charge transfer electrode 10. That is, at the time of manufacturing, the wiring 16 made of the same material as the light-shielding substance 12 is provided by forming the insulating film 11 and depositing and patterning the light-shielding film basically in the same manner as in the second embodiment. Become.

In general, in the case of a sequential transfer type CCD, 1
Since three or four charge transfer electrodes are required for one pixel, a wiring 16 to be connected to the outside like the charge transfer electrode 10 here is required. Wiring 16 on charge transfer electrode 10
When the wiring 16 also functions as a light-shielding film, light leaks from the gap between the wirings 16 into the charge transfer region 6 to generate smear if the wiring 16 also functions as a light-shielding film. In the structure 5, light is shielded by the charge transfer electrode 10 and the light-shielding substance 12, so that providing two or more wirings 16 on the charge transfer electrode 10 does not affect smear.

Incidentally, the end of the charge transfer electrode 10 shown in FIG. 10A has a configuration in which the wiring 16 is used as a light-shielding film.
It is also possible to adopt a configuration in which light is shielded by another light-shielding substance such as 2 '.

[0063]

As described above, according to the solid-state imaging device of the present invention, since the light-shielding substance is formed in a self-aligned manner around the charge transfer electrode, the area of the photodiode is increased. As a result, sensitivity can be increased and smear can be reduced. Further, since there is no need to separately form a light-shielding film on the charge transfer electrode, the number of steps can be reduced and the number of manufacturing steps can be reduced. Therefore, a solid-state imaging device with improved characteristics, performance, and productivity, which can be easily manufactured at low cost, and which is reduced in size and weight, and a method for manufacturing the same are realized.

[Brief description of the drawings]

FIGS. 1A and 1B show a basic configuration of a solid-state imaging device according to a first embodiment of the present invention, in which FIG. 1A is related to a local plan view and FIG. 1B is a side view in the AA ′ direction of FIG. (C) relates to a side cross-sectional view in the BB ′ direction of (a), (d) relates to a side cross-sectional view in the CC ′ direction of (a), and (e) relates to ( a) is a side sectional view in the DD ′ direction.

FIG. 2 is a side cross-sectional view illustrating a main part manufacturing process (light-shielding substance forming process) of the solid-state imaging device illustrated in FIG. 1 in a DD ′ direction (portion sandwiched between upper and lower photodiodes) in FIG. In the order of steps, (a) relates to the initial step, (b) relates to the middle step, and (c) relates to the latter step.

FIG. 3 is a side sectional view showing a case where the form of etching in a later step of FIG. 2C is changed.

4A and 4B show a basic configuration of a solid-state imaging device according to a second embodiment of the present invention, where FIG. 4A is related to a local plan view and FIG. 4B is a side view in the AA ′ direction of FIG. (C) relates to a side sectional view in the BB 'direction of (a), and (d) relates to a side sectional view in the CC' direction of (a).

5A to 5D show a main part manufacturing process (insulating film forming process and light shielding material forming process) of the solid-state imaging device shown in FIG.
(A) is a side cross-sectional view in the -D ′ direction (portion sandwiched between upper and lower photodiodes), and is shown in the order of steps,
Is related to the initial process, (b) is related to the middle process, and (c) is related to the latter process.

FIG. 6 is a local plan view showing a basic configuration of a solid-state imaging device according to Embodiment 3 of the present invention.

FIG. 7 is a flow chart showing a main part manufacturing process of the solid-state imaging device shown in FIG. 6;
Are shown in the order of steps by side sectional views in the DD ′ direction (portion sandwiched between upper and lower photodiodes).
(A) relates to the first half of the etching step in the charge transfer electrode formation step, (b) relates to the second half of the etching step in the charge transfer electrode formation step, (c) relates to the insulating film formation step, and (d) shields the light. (E) relates to the latter step of the shading material forming step.

FIG. 8 is a local plan view showing a basic configuration of a solid-state imaging device according to Embodiment 4 of the present invention.

FIG. 9 is a flow chart showing a main part manufacturing process of the solid-state imaging device shown in FIG. 8;
Are shown in the order of steps by side sectional views in the DD ′ direction (portion sandwiched between upper and lower photodiodes).
(A) relates to the first step of the light-shielding substance forming step,
(B) relates to the latter step of the light-shielding substance forming step.

10A and 10B show a basic configuration of a solid-state imaging device according to a fifth embodiment of the present invention, in which FIG. 10A is related to a local plan view, and FIG. 10B is a side view in the AA ′ direction of FIG. It relates to a sectional view.

11A and 11B show a basic configuration of a conventional solid-state imaging device, in which FIG. 11A is related to a local plan view, FIG. 11B is related to a side sectional view in the AA ′ direction of FIG. (c) relates to a side sectional view in the BB 'direction of (a), and (d) relates to a side sectional view in the CC' direction of (a).

12A to 12D show a manufacturing process of the solid-state imaging device shown in FIG. 11 in the order of steps by a cross-sectional view taken along the line DD ′ of FIG. 11A, in which FIG.
(B) relates to the middle-stage process, and (c) relates to the latter-stage process.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 silicon substrate 2 p ^- region 3 p ⁺ element isolation region 4 photoelectric conversion region 5 p-type region 6 charge transfer region 7 p ⁺ region 8 gate insulating film 9 charge transfer electrode 10 metal film 11 insulating film 12, 12 'light-shielding substance 13 Photoresist 14 Contact opening 15 Light shielding film 16 Wiring

Claims (16)

[Claims] 1. A solid-state imaging device including a charge-coupled device having a photoelectric conversion region and a charge transfer region locally provided near a surface of a semiconductor substrate, wherein the semiconductor covers the photoelectric conversion region and the charge transfer region. A gate insulating film made of an insulator provided on the surface of the substrate, and a plurality of charge transfer electrodes provided in a region including the portion directly above the charge transfer region on the gate insulating film and having a light shielding property, A solid-state imaging device comprising: a light-shielding substance provided on the gate insulating film at least around the electrodes including between adjacent ones of the plurality of charge transfer electrodes. 2. The solid-state imaging device according to claim 1, wherein
An insulating film is provided between the side surfaces of the plurality of charge transfer electrodes and the light-shielding substance. 3. The solid-state imaging device according to claim 2, wherein
Another charge transfer electrode of a different material is provided on the plurality of charge transfer electrodes, and the insulating film covers the surface of the another charge transfer electrode and is formed continuously on the gate insulating film. Characteristic solid-state imaging device. 4. The solid-state imaging device according to claim 2, wherein the light-shielding substance is formed by burying a groove formed between adjacent ones of the insulating film; A first portion and a second portion including a portion provided in a portion near a side wall of the charge transfer electrode and the another charge transfer electrode facing the groove in the insulating film; A solid-state imaging device characterized by the above-mentioned. 5. The solid-state imaging device according to claim 4, wherein
The solid-state imaging device according to claim 1, wherein a cross section of a side wall portion of the another charge transfer electrode and the insulating film is formed in a curved shape so that the charge transfer region cannot be seen through. 6. The solid-state imaging device according to claim 1, wherein the light-shielding substance is formed as an original form and selectively added to the original form. A solid-state imaging device comprising: 7. The solid-state imaging device according to claim 3, wherein a contact opening is provided at a predetermined position on the another charge transfer electrode in the insulating film,
A solid-state imaging device, wherein a wiring made of the light-blocking material is provided on the insulating film and electrically connected to the charge transfer electrode via the another charge transfer electrode at the contact opening. 8. The solid-state imaging device according to claim 7, wherein
The solid-state imaging device, wherein the wiring is divided into two or more wires. 9. An element forming step of locally forming a second conductivity type photoelectric conversion region and a charge transfer region near a surface of a first conductivity type region of a semiconductor substrate to obtain a charge-coupled device; A gate insulating film forming step of forming a gate insulating film made of an insulator on the surface of the semiconductor substrate over the charge transfer region; and forming a gate insulating film on the gate insulating film, the region including a portion directly above the charge transfer region. A charge transfer electrode forming step of forming a plurality of charge transfer electrodes having a light blocking property, and burying a light blocking material around the electrodes including at least between adjacent ones of the plurality of charge transfer electrodes on the gate insulating film. A method for manufacturing a solid-state imaging device, comprising: a light-shielding substance forming step. 10. An element forming step of locally forming a second conductivity type photoelectric conversion region and a charge transfer region near a surface of a first conductivity type region of a semiconductor substrate to obtain a charge coupled device, and said photoelectric conversion region. A gate insulating film forming step of forming a gate insulating film made of an insulator on the surface of the semiconductor substrate over the charge transfer region; and forming a gate insulating film on the gate insulating film, the region including a portion directly above the charge transfer region. A charge transfer electrode forming step of forming a plurality of charge transfer electrodes having a light shielding property, an insulating film forming step of covering the plurality of charge transfer electrodes with an insulating film, and an electrode including at least a portion between the adjacent ones of the insulating film And forming a light-shielding material around the light-shielding material. 11. The method for manufacturing a solid-state imaging device according to claim 9, wherein the charge transfer electrode forming step includes forming two charge transfer electrodes of different materials on the plurality of charge transfer electrodes. A method for manufacturing a solid-state imaging device, comprising a forming step. 12. The method for manufacturing a solid-state imaging device according to claim 11, wherein in the insulating film forming step, the insulating film is formed continuously on the gate insulating film so as to cover a surface of the another charge transfer electrode. A method for manufacturing a solid-state imaging device, comprising: 13. The method for manufacturing a solid-state imaging device according to claim 11, wherein, in the step of forming the charge transfer electrode, a side etch property of an etching condition is changed during patterning of the charge transfer electrode and the another charge transfer electrode. By switching in the above manner, irregularities are partially formed on the surface of a groove formed between adjacent ones of the charge transfer electrode and the another charge transfer electrode, and the cross section of the groove is curved. A method for manufacturing a solid-state imaging device. 14. The method for manufacturing a solid-state imaging device according to claim 11, wherein in the charge transfer electrode forming step, the charge transfer electrode and the another charge transfer electrode are formed in different shapes. A groove forming step of forming a groove between adjacent ones of another charge transfer electrode, and at least one of the charge transfer electrode and the another charge transfer electrode is side-etched to partially cover the groove surface. And a groove etching step of forming irregularities to make the cross section of the groove a curve. 15. The method of manufacturing a solid-state imaging device according to claim 10, wherein in the light-shielding material forming step, the light-shielding material is used as a precedent, and then a prototype is formed. A method for manufacturing a solid-state imaging device, characterized in that an additional portion is selectively added to the original form as a step. 16. The method for manufacturing a solid-state imaging device according to claim 11, wherein in the light-shielding material forming step, a contact is made with a predetermined location on the another charge transfer electrode in the insulating film. After the opening is provided, a wiring made of the light-shielding substance electrically connected to the charge transfer electrode through the another charge transfer electrode in the contact opening at the contact opening is provided on the insulating film. A method for manufacturing a solid-state imaging device.