JP2009188068A - Solid-state imaging device, manufacturing method thereof, and electronic information device - Google Patents

Abstract

An object of the present invention is to satisfactorily reduce the dark voltage on the surface of a pixel portion without impairing the moisture, and without impairing the reliability with respect to the temporal variation of threshold values of a fine transistor in a peripheral circuit portion around the pixel portion.
A passivation film 8 serving as a hydrogen supply source is set to have different residual hydrogen amounts on a pixel portion 11A and a peripheral circuit portion 11B (film thickness and / or film quality, film quality is deposited and then removed by etching). Therefore, it is constant on the pixel portion 11A and the peripheral circuit portion 11B). Accordingly, the amount of hydrogen supplied from the passivation film 8 to the semiconductor surface portion can be controlled separately in the pixel portion 11A and the peripheral circuit portion 11B by the sintering process in which heat is applied.
[Selection] Figure 1

Description

  The present invention relates to a solid-state imaging device configured by a semiconductor element that photoelectrically converts image light from a subject to image and a manufacturing method thereof, for example, a digital video camera using the solid-state imaging device as an image input device in an imaging unit, and The present invention relates to an electronic information device such as a digital camera such as a digital still camera, an image input camera such as a video phone camera, a security camera and a vehicle-mounted camera, a scanner, a facsimile, a camera-equipped mobile phone device and a personal digital assistant (PDA).

  In the above-described conventional solid-state imaging device, it is important to reduce the dark voltage on the surface of the semiconductor substrate, which is a factor that degrades the image quality in a CCD or CMOS imager. One of the causes of dark voltage is an increase in the interface state of the semiconductor substrate due to plasma damage (plasma processing such as CVD or dry etching) or plasma damage such as UV irradiation in the manufacturing process of the solid-state imaging device. ing. As a method of reducing this dark voltage, that is, a method of lowering the interface state, a passivation film (SiN film) deposited on a metal wiring desorbs hydrogen by a heat treatment in a later process, and the desorbed hydrogen is Utilizing the bonding with dangling bonds on the surface of the semiconductor substrate, and further, the P-SiN film quality is formed in a state with a higher hydrogen content to improve the bonding efficiency of the dangling bonds. This is shown in FIG. 10 for a conventional CCD solid-state imaging device.

  FIG. 10 is a longitudinal sectional view showing an example of the configuration of the main part of a conventional CCD solid-state imaging device disclosed in Patent Document 1. In FIG.

  In FIG. 10, a conventional CCD type solid-state imaging device is provided with a light receiving element 102, a readout gate portion 103 and a vertical register 104 adjacent to each other in this order along the substrate surface of the semiconductor substrate 101. A vertical transfer electrode 106 is provided via the upper silicon oxide film 105, and the first and second layers of polysilicon are sequentially provided as the vertical transfer electrode 106 so as to cross over each other.

  A silicon oxide film 105 is also provided on the vertical transfer electrode 106. On the silicon oxide film 105, a PSG film 107, a light shielding film 108 made of aluminum opening on the light receiving element 102, the light shielding film 108 and the light receiving element. A plasma silicon nitride film 109 is formed in this order as a passivation film covering 102. The plasma silicon nitride film 109 has a composition ratio of silicon to nitrogen smaller than a stoichiometrically stable value 0.75, a composition ratio of, for example, 0.6 to 0.65, and is made nitrogen-rich. ing.

  Since the plasma silicon nitride film 109 is thus rich in nitrogen, the number of N—H bonds inevitably increases, and the plasma silicon nitride film 109 is removed from the plasma silicon nitride film 109 during annealing after the plasma silicon nitride film 109 is formed. The number of hydrogens that terminate the dangling bonds on the surface of the light receiving element 102 of the semiconductor substrate increases. Therefore, the interface state on the surface of the light receiving element 102 is lowered, and as a result, noise due to dark current on the light receiving surface is reduced, and the performance of the solid-state imaging element is improved.

  Further, the nitrogen-rich plasma silicon nitride film 109 has a lower refractive index than the stoichiometrically stable plasma silicon nitride film. Then, the angle at which the light passing through the plasma silicon nitride film 109 is refracted becomes smaller by the smaller refractive index, and is reflected between the light shielding film 108 and the semiconductor substrate 101 as shown by a two-dot chain line in FIG. Light that enters the vertical transfer register 104 is less likely to enter. If the refractive index is large, it is easy to enter the register 104 side as indicated by a two-dot chain line. Therefore, according to this conventional solid-state imaging device, smear is inevitably reduced.

  The above is the case of the CCD type solid-state imaging device, but FIG. 11 shows the case of the CMOS type solid-state imaging device.

  FIG. 11 is a longitudinal sectional view showing an example of the configuration of the main part of a conventional CMOS type solid-state imaging device.

  In FIG. 11, in the conventional CMOS type solid-state imaging device, a driver as a peripheral circuit unit 200B for reading an imaging signal from each pixel (light receiving unit) around a pixel unit 200A provided with a plurality of pixels (light receiving units). A circuit, a logic circuit, and a memory such as an SRAM are provided. In the pixel portion 200A, a photodiode 202 as a photoelectric conversion portion (light receiving portion) is formed as a surface layer of the semiconductor substrate 201. Adjacent to the photodiode 202, a charge transfer portion 203 of a charge transfer transistor for transferring signal charges to the floating diffusion portion FD is provided. On the charge transfer portion 203, a gate electrode 205A as an extraction electrode is provided via a gate insulating film 204. Furthermore, a signal charge transferred to the floating diffusion portion FD for each photodiode 202 is converted into a voltage, amplified in accordance with the converted voltage, and read out as an imaging signal for each pixel portion (not shown). )have. On the other hand, on the surface side of the semiconductor substrate 201 of the peripheral circuit portion 200B, a large number of fine transistor gate electrodes 205B constituting the above-described driver circuit, logic circuit, and memory such as SRAM are provided.

  Above the gate electrode 205A of the pixel portion 200A, a first insulating film 206a is formed as a circuit wiring portion of the readout circuit, a first wiring 207a is formed thereon, and a second insulating film 206b is formed thereon. The second wiring 207b is formed thereon, and similarly, the third insulating film 206c and the third wiring 207c are sequentially formed thereon in this order to form a three-layer wiring. On the other hand, on the gate electrode 205B of the fine transistor in the peripheral circuit portion 200B, a fourth insulating film 206d and a fourth wiring 207d are sequentially formed in this order on the three-layer wiring to form a four-layer wiring. In order to form a circuit, a conductive material is used between the wiring layer 207 (207a to 207d) and the semiconductor substrate 201 (not shown), between the wiring layer 207 and the gate electrodes 205A and 205B, and between each wiring layer 207. A contact plug (not shown) is formed.

  Further, a fifth insulating layer 206e is provided thereon, and a passivation film 208 (SiN film) is provided on the fifth insulating layer 206e. After the passivation film 208 (SiN film) is formed, heat is applied to perform an annealing process so that hydrogen is desorbed from the passivation film 208 (SiN film) and the surface of the photodiode 202 which is a light receiving element of the semiconductor substrate 201. In combination with the dangling bonds, the dark current on the surface of the semiconductor substrate 201 is reduced.

Further, color filters 209 of each color of R, G, and B arranged for each light receiving unit 202 are formed on the passivation film 208 (SiN film), and further, for condensing to the light receiving unit 202. The microlens 210 is formed.
JP-A-6-112453

  However, in any of the above conventional configurations, hydrogen is supplied to the entire semiconductor substrate including the pixel portion and its peripheral circuit portion. Therefore, in a CCD or CMOS imager having a peripheral circuit using a thin film transistor, the pixel portion If an attempt is made to secure the hydrogen supply amount at the above, the hydrogen supply amount to the fine transistor in the peripheral circuit portion becomes excessive, and hydrogen remains on the semiconductor substrate surface side, and the threshold value of the fine thin film transistor fluctuates ( There is a problem in that NBTI (Negative Bias Temperature Instability) degradation occurs that the response speed is affected if the threshold value shifts with time.

  The present invention solves the above-mentioned conventional problem, and ensures dark voltage on the surface of the pixel portion without impairing moisture, and without impairing the reliability with respect to the temporal variation of the threshold value of the fine transistor in the peripheral circuit portion around the pixel portion. An object of the present invention is to provide a solid-state imaging device that can be satisfactorily reduced, a manufacturing method thereof, and an electronic information device that uses the solid-state imaging device as an image input device in an imaging unit.

  The solid-state imaging device of the present invention is a solid-state imaging device having a peripheral circuit unit using a fine transistor around a pixel unit provided with a plurality of light-receiving units that photoelectrically convert image light from a subject. The passivation film serving as a supply source is set to have different residual hydrogen amounts on the pixel portion and the peripheral circuit portion, thereby achieving the above object.

  Preferably, the different residual hydrogen amounts in the solid-state imaging device of the present invention differ between the pixel portion and the peripheral circuit portion depending on the film formation conditions of the passivation film.

Further preferably, as a film formation condition of the passivation film in the solid-state imaging device of the present invention, the gas type is SiH ₄ or NH ₃ , N ₂ , H ₂ , and the gas flow rate, temperature, pressure, and The residual hydrogen amount is controlled by RF power.

  Further, preferably, different residual hydrogen amounts in the solid-state imaging device of the present invention differ between the pixel portion and the peripheral circuit portion depending on the thickness of the passivation film.

  Further preferably, the thickness of the passivation film in the solid-state imaging device of the present invention is set to 200 to 500 nm on the pixel portion, and is set to 30 to 150 nm on the peripheral circuit portion.

  Further preferably, the passivation film in the solid-state imaging device of the present invention is a SiN film formed by plasma CVD.

  Further preferably, the passivation film in the solid-state imaging device of the present invention is a laminated film of a SiN film and a SiON film on the pixel portion, and is a SiON film on the peripheral circuit portion.

  Further preferably, the passivation film in the solid-state imaging device of the present invention is a SiN film on the pixel portion and a SiON film on the peripheral circuit portion.

  Further preferably, the passivation film in the solid-state imaging device of the present invention is set to a film thickness for suppressing dark voltage on a semiconductor surface in the pixel portion.

  Further preferably, in the passivation film in the solid-state imaging device of the present invention, in the peripheral circuit portion, the hydrogen supply amount to the fine transistor is set to a film thickness for suppressing a threshold aging variation.

  Further preferably, the passivation film in the solid-state imaging device of the present invention is set to a film thickness having a passivation function for blocking moisture.

  Further preferably, the passivation film in the solid-state imaging device according to the present invention has a film thickness in the peripheral circuit portion that is smaller than a film thickness in the pixel portion.

  Further, preferably, the fine transistor in the solid-state imaging device of the present invention is a fine transistor having a thin gate film thickness, which can cause a change with time in threshold when the amount of hydrogen supplied from the passivation film increases.

  The method for manufacturing a solid-state imaging device according to the present invention includes a solid-state imaging device having a peripheral circuit unit using a fine transistor around a pixel unit provided with a plurality of light-receiving units that photoelectrically convert image light from a subject. In this manufacturing method, both the pixel portion and the peripheral circuit portion include a passivation film forming step for forming a passivation film serving as a hydrogen supply source with a predetermined thickness, and only the passivation film in the peripheral circuit portion is removed by etching. A passivation film forming step for forming a predetermined film thickness, whereby the above-mentioned object is achieved.

  The solid-state imaging device manufacturing method according to the present invention also includes a solid-state image sensor that includes a peripheral circuit unit using fine transistors around a pixel unit provided with a plurality of light-receiving units that photoelectrically convert image light from a subject. In the image pickup device manufacturing method, a first passivation film forming step for forming a passivation film serving as a hydrogen supply source in a predetermined film thickness in both the pixel portion and the peripheral circuit portion, and only the pixel portion on the passivation film. And a second passivation film forming step of forming a passivation film that is the same as or different from the passivation film to a predetermined film thickness, thereby achieving the above object.

  Furthermore, the method for manufacturing a solid-state imaging device according to the present invention includes a solid-state image sensor having a peripheral circuit unit using a fine transistor around a pixel unit provided with a plurality of light-receiving units that photoelectrically convert image light from a subject. In the imaging device manufacturing method, a first passivation film forming step for forming a passivation film serving as a hydrogen supply source on the pixel portion to a predetermined thickness, and a residual hydrogen amount in the peripheral circuit portion as compared with the passivation film. And a third passivation film forming step for forming a passivation film with a small thickness to a predetermined film thickness, whereby the above object is achieved.

  Further preferably, in the method for manufacturing a solid-state imaging device according to the present invention, a sintering process for supplying hydrogen to the pixel unit and the peripheral circuit unit by desorbing residual hydrogen from the passivation film by heat treatment after the passivation film forming step. It further has a sintering process step for performing the process.

  Further preferably, in the method for manufacturing a solid-state imaging device according to the present invention, after the second passivation film forming step or the third passivation film forming step, residual hydrogen is desorbed from the passivation film by heat treatment, and the pixel And a sintering process for performing a sintering process for supplying hydrogen to the peripheral circuit unit and the peripheral circuit unit.

  Further preferably, in the passivation film forming step in the method of manufacturing a solid-state imaging device according to the present invention, the passivation film of the peripheral circuit portion is formed so as to have a film thickness that can ensure the reliability of the threshold transistor over time of the fine transistor. A predetermined film thickness is formed by lithography and dry etching or wet etching.

  Further preferably, in the method for manufacturing a solid-state imaging device according to the present invention, the second passivation film forming step includes not only the passivation film of the pixel portion but also the pixel portion in addition to the film thickness by the first passivation film forming step. Is set to a film thickness for suppressing dark voltage on the semiconductor surface.

  The electronic information apparatus according to the present invention uses the solid-state imaging device according to the present invention as an image input device in an imaging unit, and thereby achieves the above object.

  With the above configuration, the operation of the present invention will be described below.

  In the present invention, the passivation film serving as the hydrogen supply source during the sintering process is set to have different residual hydrogen amounts on the pixel portion and the peripheral circuit portion. This makes it possible to separately control the hydrogen supply amounts to the pixel portion and the peripheral circuit portion by performing heat treatment. For this reason, while ensuring a passivation function that blocks moisture in order to prevent rusting of the internal metal wiring, reliability is ensured with respect to threshold aging of the transistor in the peripheral circuit section, and dark voltage on the surface of the pixel section is reduced. It becomes possible to reduce favorably.

  This different amount of residual hydrogen can be controlled to be different between the pixel portion and the peripheral circuit portion depending on the film formation condition of the passivation film and / or the film thickness of the passivation film.

  As described above, according to the present invention, the passivation film serving as the hydrogen supply source is set to have different residual hydrogen amounts on the pixel unit and the peripheral circuit unit, so that the pixel unit and the peripheral region are subjected to the sintering process in which heat is applied. The amount of hydrogen supplied to the circuit unit can be controlled separately, ensuring the passivation function to block moisture, ensuring the reliability with respect to the threshold aging of the fine transistor in the peripheral circuit unit, and the dark voltage on the surface of the pixel unit Can be reduced satisfactorily.

Hereinafter, a case where the solid-state imaging device of the present invention and the manufacturing method thereof are applied to a CMOS type solid-state imaging device is referred to as Embodiment 1, and a case where the solid-state imaging device of the present invention and the manufacturing method thereof are applied to a CCD type solid-state imaging device. An electronic information device that uses Embodiment 2 and Embodiments 1 and 2 as an image input device in an imaging unit will be described as Embodiment 3 in detail with reference to the drawings.
(Embodiment 1)
FIG. 1 is a longitudinal sectional view schematically showing a configuration example of a main part of a pixel portion and its peripheral circuit portion in a CMOS type solid-state imaging device according to Embodiment 1 of the present invention, and FIG. 2 is a CMOS type of FIG. It is a top view which shows typically the arrangement | positioning relationship of the pixel part and its peripheral circuit part in a solid-state image sensor. FIG. 2 shows an example in the case of a driver circuit as the peripheral circuit portion.

  1 and 2, the CMOS solid-state imaging device 20 according to the first embodiment captures images from each pixel (light receiving unit) around a pixel unit 11A in which a plurality of pixels (light receiving units) are provided in a matrix. A driver circuit, a logic circuit, and a memory such as an SRAM are provided as a peripheral circuit unit 11B for driving a reading circuit (not shown) for reading a signal. In the pixel portion 11A, a photodiode 2 as a photoelectric conversion portion (light receiving portion) is formed as a surface layer of the semiconductor substrate 1. Adjacent to the photodiode 2 is provided a charge transfer portion 3 of a charge transfer transistor for transferring signal charges to the floating diffusion portion FD. On the charge transfer portion 3, a gate electrode 5 </ b> A that is an extraction electrode is provided via a gate insulating film 4. Further, the signal charge transferred to the floating diffusion portion FD for each photodiode 2 is subjected to voltage conversion, amplified in accordance with the converted voltage, and read out as an imaging signal for each pixel portion (see FIG. Not shown). On the other hand, on the surface side of the semiconductor substrate 1 of the peripheral circuit portion 11B, in addition to the driver circuit described above, a gate electrode 5B of a large number of thin-film transistors constituting a logic circuit and a memory such as an SRAM is provided. Also good.

  Above the gate electrode 5A of the pixel portion 11A, a first insulating film 6a is formed as a circuit wiring portion such as a readout circuit, a first wiring 7a is formed thereon, and a second insulating film is formed thereon. 6b is formed, and a second wiring 7b is formed thereon. Similarly, a third insulating film 6c and a third wiring 7c are sequentially formed thereon in this order to form a three-layer wiring (even in other multiple wiring layers). It is good). On the other hand, on the gate electrode 5B of the fine transistor in the peripheral circuit portion 11B, a fourth insulating film 6d and a fourth wiring 7d are further formed in this order on the above-described three-layer wiring to form a four-layer wiring (another plurality of wirings). It may be a wiring layer). For circuit formation, a conductive material is used between the wiring layer 7 (7a to 7d) and the semiconductor substrate 1 (not shown), between the wiring layer 7 and the gate electrodes 5A and 5B, and between each wiring layer 7. A contact plug (not shown) is formed.

  Further, a fifth insulating layer 6e is provided thereon, and a passivation film 8 (SiN film) serving as a hydrogen supply source is provided on the fifth insulating layer 6e by heat treatment. The passivation film 8 (SiN film) serving as the hydrogen supply source has different thicknesses of the passivation film 8 formed on the pixel portion 11A and the peripheral circuit portion 11B. Further, the passivation film 8 (SiN film) serving as a hydrogen supply source is deposited by plasma CVD with a film thickness necessary for suppressing dark voltage on the substrate surface of the pixel portion 11A, and the fine transistor of the peripheral circuit portion 11B. Etching is removed (eroded) by photolithography and dry etching or wet etching so as to obtain a film thickness with no problem in reliability with respect to the threshold variation with time. Therefore, the passivation film 8 (SiN film) serving as a hydrogen supply source is formed with a thinner film thickness in the peripheral circuit portion 11B than in the pixel portion 11A. In this case, in order to prevent moisture from being supplied to the wiring layer 7 and rusting the wiring layer 7, the passivation film 8 (SiN film) needs to have a certain thickness. In short, the passivation film 8 (SiN film) serving as a hydrogen supply source is set to have different residual hydrogen amounts depending on the film thickness and / or film quality on the pixel portion 11A and the peripheral circuit portion 11B. Here, the amount of residual hydrogen differs between the pixel portion 11A and the peripheral circuit portion 11B depending on the thickness of the passivation film 8 with the film formation condition (film quality) of the passivation film 8 being constant.

  In this manner, the passivation film 8 (SiN film) is deposited to a predetermined thickness, and only the passivation film 8 (SiN film) of the peripheral circuit portion 11B is eroded to reduce the thickness, and then the passivation is performed by heat treatment (annealing). Residual hydrogen is desorbed from the film 8 (SiN film) and combined with dangling bonds on the surface of the photodiode 2 which is the light receiving element of the semiconductor substrate 1 to reduce the dark current on the semiconductor surface.

  Further, on the passivation film 8 (SiN film), color filters 9 of R, G, and B colors arranged for each photodiode 2 (light receiving part) are formed, and further, each light receiving part 2 is formed thereon. A condensing microlens 10 is formed.

  Therefore, in the first embodiment, the residual hydrogen amount of the passivation film 8 (SiN film) is separately controlled by the pixel unit 11A and the peripheral circuit unit 11B according to the film thickness and / or film quality (constant in the first embodiment). is doing. The passivation film 8 (SiN film) is thinned by the peripheral circuit portion 11B. For this reason, while ensuring a passivation function that does not allow moisture to pass through, the amount of hydrogen supplied to the fine transistors in the peripheral circuit portion 11B becomes appropriate, so that conventional NBTI degradation can be avoided, and a large amount of hydrogen is contained in the pixel portion 11A. Given the supply amount, the dark voltage on the semiconductor surface can be reduced. As described above, even if a sintering process is performed in which heat is applied to remove residual hydrogen and hydrogen is supplied to the semiconductor surface, the reliability of the peripheral circuit portion 11B regarding the threshold aging of the thin transistor that operates at high speed is impaired. In addition, the dark voltage of the pixel portion 11A can be favorably reduced.

  Below, the manufacturing method of the CMOS type solid-state image sensor 20 of this Embodiment 1 of the said structure is demonstrated.

  As shown in the pixel region / transistor formation step in FIG. 3, impurity diffusion layers such as the light receiving portion 2 and the floating diffusion portion FD are formed in the pixel portion 11A on the semiconductor substrate 1 by ion implantation. A gate electrode 5A is formed between the floating diffusion portions FD via the gate insulating film 4. Further, the source region and the drain region of the fine transistor of the peripheral circuit portion 11B are formed by ion implantation, and the gate electrode 5B is formed between the source region and the drain region via the thin gate insulating film 4. Here, polysilicon electrodes are used for both the gate electrodes 5A and 5B, and other details are omitted here.

  As shown in the metal wiring formation step of FIG. 4, metal layer wirings 7a to 7d are formed in the pixel portion 11A and its peripheral circuit portion 11B. Here, the pixel portion 11A in the pixel region uses a three-layer wiring, and the peripheral circuit 11B uses a four-layer wiring. As wiring materials for the wirings 7a to 7d, an AlCu film, a Ti film, and a TiN film are used. It has a laminated structure. The interlayer insulating films 6a to 6e are planarized by depositing an oxide film by plasma CVD and polishing by CMP. Other details such as the via hole of the contact portion are omitted here.

As shown in the passivation film formation step of FIG. 5, a passivation film 8a is deposited on the entire surface in order to protect the wiring material of the wirings 7a to 7d from moisture. At this time, a p-SiN film formed by plasma CVD is used as a passivation film 8a to be formed so that a large amount of hydrogen can be supplied by a heat treatment in a later process (the SiN film is also used as a hydrogen supply source, but functions as a passivation film). For example, a SiON film may be used. As the conditions for forming the passivation film, the gas species are SiH ₄ , NH ₃ , N ₂ , H _2, etc., and the hydrogen content (residual hydrogen amount) depends on the gas flow rate, temperature, pressure, RF power, etc. of each gas species. Can be controlled. In order to reduce the dark voltage on the surface of the silicon substrate, it is preferable to form a SiN film having a higher hydrogen content. Further, the larger the film thickness, the larger the hydrogen supply amount, and the film thickness of the passivation film 8 is set to 200 to 500 nm (here, 300 nm). If the thickness of the passivation film 8 is 200 nm, the amount of hydrogen supplied in the pixel portion 11A is sufficient. If the thickness is 500 nm or more, the film formation takes time and is wasteful, so it is set to 500 nm or less.

  As shown in the passivation film formation step of FIG. 6, only the passivation film 8a of the peripheral circuit portion 11B is made to have a predetermined thickness by photolithography and dry etching or wet etching (fluorine-based gas) on the passivation film 8a. Erosion is removed by etching. At this time, the remaining film (predetermined film thickness) as the passivation film 8 is set to a film thickness that provides a hydrogen supply amount that does not affect the reliability of the fine transistor of the peripheral circuit unit 11B with respect to the threshold aging. Here, the predetermined film thickness as the passivation film 8 is set to 30 to 150 nm. Here, the thickness of the passivation film 8 is set to 30 nm or more in consideration of water supply prevention as a passivation function, and the amount of hydrogen supplied to the fine transistor in a thin film is considered in consideration of the reliability with respect to the threshold aging of the fine transistor. 150 nm or less.

  Subsequently, heat treatment (annealing treatment) is performed in order to desorb residual hydrogen from the passivation film 8 (SiN film). In this case, using a diffusion furnace, the temperature is, for example, 440 degrees Celsius (400 to 460 degrees Celsius; less than 400 degrees Celsius), and desorption of residual hydrogen does not proceed. For example, it is maintained for 1 hour (10 minutes to 3 hours or 3 hours or more, stress migration is likely to occur in the wiring). Although the desorption of residual hydrogen from the passivation film 8 (SiN film) increases as the temperature increases and the time increases, the quality of the wiring material of the wiring layers 7a to 7d (rust) is prevented from occurring. The desorbed hydrogen is combined with dangling bonds on the surface of the silicon substrate of the pixel portion 11A and the peripheral circuit portion 11B. The amount of hydrogen supplied to the pixel portion 11A and the peripheral circuit portion 11B (or on and around the pixel portion 11A) The residual hydrogen amount of the passivation film 8 (SiN film) on the circuit portion 11B) is different from that of the pixel portion 11A depending on the film thickness and film quality of the passivation film 8 (SiN film) (film formation conditions; constant in the first embodiment). The peripheral circuit unit 11B is controlled differently.

  Thereafter, as shown in the color filter / microlens formation step of FIG. 7, the color filters 9 of the respective colors correspond to the light-receiving portions on the pixel portion 11A and the peripheral circuit portion 11B on the passivation film 8 (SiN film). The microlens 10 for condensing each light receiving part 2 is formed thereon. Description of other details is omitted here.

  As described above, according to the first embodiment, the passivation film 8 serving as a hydrogen supply source is set to have different residual hydrogen amounts on the pixel portion 11A and the peripheral circuit portion 11B (the film thickness and / or film quality and film quality are not changed). Since the film is removed after etching, it is constant on the pixel portion 11A and the peripheral circuit portion 11B. Accordingly, since the amount of hydrogen supplied from the passivation film 8 to the semiconductor surface portion can be controlled separately in the pixel portion 11A and the peripheral circuit portion 11B by the sintering process in which heat is applied, the peripheral circuit is secured while ensuring a passivation function for blocking moisture. As well as ensuring the reliability of the fine transistor in the portion 11B with respect to the threshold aging, the dark voltage on the surface of the pixel portion 11A can be satisfactorily reduced.

  In the first embodiment, the case of a CMOS solid-state imaging device has been described. As a readout circuit (not shown) provided in the periphery of each light receiving unit, a charge transfer transistor, a reset transistor, and an amplification transistor ( However, these transistors are not thin transistors (thickness of the gate insulating film) and are provided in the periphery of a plurality of light receiving portions (imaging region; pixel portion 11A). The peripheral circuit portion 11B includes a driver circuit for driving and controlling the readout circuit, a logic circuit, and a memory such as an SRAM. The memory such as the driver circuit, the logic circuit, and the SRAM has a number of thin film transistors. . By optimizing the thickness of the passivation film 8 (SiN film) according to the first embodiment, it is possible to ensure the reliability with respect to the variation with time of the threshold value of the fine transistors constituting the driver circuit, the logic circuit, and the memory such as the SRAM.

  Here, this fine transistor means a transistor in which the gate insulating film 4 is thin and the threshold aging can occur when the amount of hydrogen supplied from the passivation film 8 increases. As described above, transistors such as a reset transistor and an amplifying transistor that constitute a reading circuit (not shown) are not fine transistors described here, and are relatively for suppressing dark voltage on the semiconductor surface from the passivation film 8. Transistors that are less susceptible to threshold aging with respect to the hydrogen supply amount are used.

  In the first embodiment, the passivation film 8 (SiN film) is formed to a predetermined thickness in both the pixel portion 11A and the peripheral circuit portion 11B, and the passivation film 8 (SiN film) is etched and removed only in the peripheral circuit portion 11B. However, the present invention is not limited to this, and the passivation film 8 (SiN film) is formed in a predetermined film thickness in both the pixel portion 11A and the peripheral circuit portion 11B, and then the passivation film 8 only in the pixel portion 11A. (SiN film) may be formed to a predetermined thickness. In the former case, in the peripheral circuit portion 11B of the first embodiment, the film formation (deposition) and etching errors affect the film thickness. In the latter case, the error of only the film formation (deposition) is present. Since the film thickness is affected, the thickness of the passivation film 8 (SiN film) can be formed with high accuracy. In this case, the supply amount of hydrogen can be controlled more accurately.

  That is, in the method for manufacturing the solid-state imaging device 20 according to the first embodiment, a peripheral circuit using fine transistors around the pixel unit 11A provided with a plurality of light-receiving units that photoelectrically convert image light from a subject to capture an image. In the method of manufacturing the solid-state imaging device having the portion 11B, both the pixel portion 11A and the peripheral circuit portion 11B include a passivation film forming step for forming the passivation film 8 serving as a hydrogen supply source to a predetermined thickness, and the peripheral circuit portion 11B. And a passivation film forming step of removing only the passivation film 8 to a predetermined film thickness by etching. In the modification of the manufacturing method of the solid-state imaging device 20 according to the first embodiment, a peripheral using a fine transistor is provided around the pixel unit 11A provided with a plurality of light receiving units that photoelectrically convert image light from a subject to capture an image. In the manufacturing method of the solid-state imaging device having the circuit portion 11B, the pixel portion 11A and the peripheral circuit portion 11B both include a first passivation film forming step for forming a passivation film 8 serving as a hydrogen supply source in a predetermined film thickness, and a pixel portion 11A includes a second passivation film forming step in which the passivation film 8 is formed on the passivation film 8 by the first passivation film forming step so as to overlap the predetermined film thickness. Thereafter, a sintering process for performing a sintering process for desorbing residual hydrogen from the passivation film 8 by heat treatment is further provided.

Further, in the first embodiment, the thickness of the passivation film 8 (SiN film) in the peripheral circuit portion 11B is configured to be smaller than the thickness of the passivation film 8 (SiN film) in the pixel portion 11A. On the peripheral circuit part 11B side, considering the life of the wiring layer 7, a thin film of a SiON film may be formed instead of eliminating or further thinning the passivation film 8 (SiN film). In this case, the passivation film 8 may be a laminated film of a SiN film and a SiON film on the pixel portion 11A, a SiON film on the peripheral circuit portion 11B, or a SiN film on the pixel portion 11A. There may be a SiON film on the peripheral circuit portion 11B.
(Embodiment 2)
In the second embodiment, a case where the solid-state imaging device of the present invention and the manufacturing method thereof are applied to a CCD solid-state imaging device will be described.

  FIG. 8 is a plan view schematically showing the arrangement relationship between the pixel portion and its peripheral circuit portion in the CCD solid-state imaging device according to Embodiment 2 of the present invention.

  As shown in FIG. 8, the CCD solid-state imaging device 30 according to the second embodiment has a plurality of light receiving portions 31 that photoelectrically convert incident light and generate signal charges as light receiving elements in a matrix in the matrix direction. In addition, adjacent to each light receiving portion 31 in the column direction, a charge transfer portion for transferring the signal charges from each light receiving portion 31 and a charge transfer electrode 32 for controlling the charge transfer thereon are arranged thereon. ing. A large number of the charge transfer electrodes 32 are arranged in the column direction to form each vertical transfer path 33. The signal charges are transferred in the vertical direction through the vertical transfer paths 33 of each column, and the signal charges are sequentially transferred in the horizontal direction through the horizontal transfer paths 34. The signal charge transferred through the horizontal transfer path 34 is amplified by the output transistor 35 of the charge detection unit and output as an imaging signal. The output transistor 35 is a thin fine transistor, and a region corresponding to the output transistor 35 is a peripheral circuit portion 41B.

  In addition, the peripheral circuit portion 41B and the pixel portion 41A including the vertical transfer path 33, the horizontal transfer path 34, and the plurality of light receiving portions 31 reduce the residual hydrogen amount of the passivation film 8 (SiN film) serving as the hydrogen supply source. Depending on the film thickness and / or film quality (deposition conditions; constant in the second embodiment). That is, the passivation film 8 (SiN film) serving as a hydrogen supply source differs between the pixel portion 41A and the peripheral circuit portion 41B depending on the film thickness and / or film quality (deposition conditions; constant in the second embodiment). The amount of residual hydrogen is set. The passivation film 8 (SiN film) is deposited by plasma CVD with a film thickness and film quality necessary for suppressing the dark voltage on the substrate surface of the pixel portion 41A, and the peripheral circuit portion 41B, driver circuit, logic circuit and Etching and removal by photolithography and dry etching or wet etching so as to obtain a film thickness and film quality (deposition conditions; constant in the second embodiment) that do not cause a problem with reliability regarding threshold fluctuation of a thin transistor such as an SRAM. (Erosion) to a predetermined film thickness. Therefore, the passivation film 8 (SiN film) is formed with a smaller film thickness in the peripheral circuit portion 41B and the memory such as the driver circuit, logic circuit, and SRAM than in the pixel portion 41A. In this case, in order to prevent moisture from being supplied to the metal wiring layer and rusting, the film thickness of the passivation film 8 (SiN film) is also required to some extent.

  In short, in the first embodiment, the peripheral circuit unit 11B has a large number of fine transistors around the pixel unit 11A. However, in the second embodiment, only one output transistor 35 is used as the peripheral circuit unit 41B. I only have it.

  Here, general characteristics of the CMOS solid-state image sensor 20 and the CCD solid-state image sensor 30 will be briefly described.

  Like the CCD solid-state imaging device 30, the CMOS solid-state imaging device 20 transfers the signal charges from the respective light receiving units 31 through the vertical transfer paths 33 and the signal charges from the vertical transfer paths 33 to the horizontal transfer paths 34. The signal charge is read out from the light-receiving unit for each pixel and converted into a voltage by a selection control line composed of aluminum wiring or the like as in a memory device without using a CCD that transfers charges in the horizontal direction. The image pickup signal amplified in response to the signal is sequentially read out from the selected pixel. Furthermore, since a CCD-specific manufacturing process is used for manufacturing the CCD solid-state imaging device 30, it is difficult to apply a manufacturing process generally used in a CMOS circuit as it is. On the other hand, the CMOS type solid-state imaging device 20 uses a manufacturing process generally used in a CMOS circuit. Therefore, a display control driver circuit, a logic circuit, an SRAM, and other memories, and an imaging control A logic circuit, an analog circuit, an analog-digital conversion circuit, etc. are simultaneously formed as peripheral circuits by a CMOS process frequently used in the manufacture of driver circuits, logic circuits and memories such as SRAM, semiconductor memories such as DRAM, and logic circuits. Can end up. A large number of fine transistors are used here. That is, the CMOS solid-state imaging device 20 is formed on the same semiconductor chip as a semiconductor memory, a display control driver circuit, a logic circuit and a memory such as an SRAM, and an imaging control driver circuit, a logic circuit and a memory such as an SRAM. In addition, it is easy to share a production line with a semiconductor memory, a driver circuit for display control, a logic circuit, a memory such as an SRAM, and a driver circuit for imaging control. it can.

As described above, according to the second embodiment, it is necessary to reduce the dark voltage on the surface of the silicon substrate in the pixel portion 41A in the CCD solid-state image pickup device 30 as in the case of the CMOS solid-state image pickup device 20 by the above method. A predetermined supply amount of hydrogen from the passivation film 8 (SiN film) can be optimally obtained by setting the film quality and film thickness of the SiN film, and is supplied to the output transistor 35 which is a fine transistor of the peripheral circuit portion 41B. By optimizing the hydrogen supply amount by setting the film quality and film thickness of the SiN film, it is possible to ensure the reliability regarding the threshold aging variation of the fine transistor.
(Embodiment 3)
FIG. 9 is a block diagram illustrating a schematic configuration example of an electronic information device using a solid-state imaging device including the solid-state imaging device 20 or 30 of the first or second embodiment as an imaging unit as the third embodiment of the present invention.

  In FIG. 9, an electronic information device 90 according to the third embodiment includes a solid-state imaging device 91 that obtains a color image signal by performing various signal processing on the imaging signal from the solid-state imaging device 20 or 30 according to the first or second embodiment. A memory unit 92 such as a recording medium capable of recording data after processing a color image signal from the solid-state imaging device 91 for recording, and a predetermined signal for displaying the color image signal from the solid-state imaging device 91 The display means 93 such as a liquid crystal display device that can be displayed on a display screen such as a liquid crystal display screen after processing, and the color image signal from the solid-state imaging device 91 can be subjected to communication processing after predetermined signal processing for communication. An image to be printed out after performing predetermined signal processing on the color image signal from the solid-state imaging device 91 and the communication means 94 such as a transmission / reception device And a force device 95. The electronic information device 90 is not limited to this, and in addition to the solid-state imaging device 91, at least one of a memory unit 92, a display unit 93, a communication unit 94, and an image output device 95 such as a printer. You may have.

  As described above, the electronic information device 90 includes, for example, a digital camera such as a digital video camera and a digital still camera, an in-vehicle camera such as a surveillance camera, a door phone camera, and an in-vehicle rear surveillance camera, and a video phone camera. An electronic device having an image input device such as an image input camera, a scanner, a facsimile, a camera-equipped mobile phone device and a personal digital assistant (PDA) is conceivable.

  Therefore, according to the third embodiment, based on the color image signal from the solid-state imaging device 91, it is displayed on the display screen, or is printed out on the paper by the image output device 95. (Printing), communicating this as communication data in a wired or wireless manner, performing a predetermined data compression process in the memory unit 92 and storing it in a good manner, or performing various data processings satisfactorily Can do.

  In the first and second embodiments, the peripheral circuit unit 11B or 41B using a fine transistor is provided around the pixel unit 11A or 41A provided with a plurality of light receiving units that photoelectrically convert image light from a subject. In the solid-state imaging device 20 or 30 having the above, the passivation film 8 serving as a hydrogen supply source is set to have different residual hydrogen amounts on the pixel portion 11A or 41A and the peripheral circuit portion 11B or 41B. Is configured such that the film formation conditions of the passivation film 8 are constant and the film thickness of the passivation film 8 is different between the pixel portion 11A or 41A and the peripheral circuit portion 11B or 41B. On the passivation film 8 having a small residual hydrogen amount, only the pixel portion 11A or 41A has a passivation film having a large residual hydrogen amount. Alternatively, the passivation film 8 on the pixel portion 11A or 41A may be a passivation film 8 having a large amount of residual hydrogen, and the passivation film 8 on the peripheral circuit portion 11B or 41B has a small amount of residual hydrogen. You may form into a film so that it may become the passivation film 8. FIG.

  That is, as a manufacturing method thereof, a peripheral circuit section 11B or 41B using a fine transistor is provided around a pixel section 11A or 41A provided with a plurality of light receiving sections that photoelectrically convert image light from a subject. In the solid-state imaging device manufacturing method, the pixel portion 11A or 41A and the peripheral circuit portion 11B or 41B both include a first passivation film forming step for forming a passivation film serving as a hydrogen supply source in a predetermined thickness, and the pixel portion 11A. Alternatively, only 41A includes a second passivation film forming step of forming a passivation film having the same thickness as or different from the passivation film on the passivation film formed by the first passivation film forming step. Alternatively, as a manufacturing method thereof, a first passivation film forming step of forming a passivation film serving as a hydrogen supply source in a predetermined film thickness in the pixel portion 11A or 41A, and a first passivation film forming step in the peripheral circuit portion 11B or 41B. And a third passivation film forming step for forming a passivation film having a smaller amount of residual hydrogen than the passivation film formed in the passivation film forming step to a predetermined thickness.

  As mentioned above, although this invention has been illustrated using preferable Embodiment 1-3 of this invention, this invention should not be limited and limited to this Embodiment 1-3. It is understood that the scope of the present invention should be construed only by the claims. It is understood that those skilled in the art can implement an equivalent range based on the description of the present invention and the common general technical knowledge from the description of specific preferred embodiments 1 to 3 of the present invention. Patents, patent applications, and documents cited herein should be incorporated by reference in their entirety, as if the contents themselves were specifically described herein. Understood.

  The present invention relates to a solid-state imaging device configured by a semiconductor element that photoelectrically converts image light from a subject to image and a manufacturing method thereof, for example, a digital video camera using the solid-state imaging device as an image input device in an imaging unit, and In the field of electronic information equipment such as digital cameras such as digital still cameras, image input cameras, scanners, facsimiles, and camera-equipped mobile phone devices, a passivation film serving as a hydrogen supply source is formed on the pixel portion and the peripheral circuit portion. By setting different residual hydrogen amounts, the hydrogen supply amount to the pixel unit and peripheral circuit unit can be controlled separately by the sintering process that applies heat, so that the peripheral circuit unit is secured while ensuring the passivation function to block moisture As well as ensuring the reliability of the fine transistor threshold over time, the dark current on the pixel surface It can be favorably reduced.

It is a longitudinal cross-sectional view which shows typically the example of a principal part structure of the pixel part and its peripheral circuit part in the CMOS type solid-state image sensor which concerns on Embodiment 1 of this invention. FIG. 2 is a plan view schematically showing the arrangement relationship between a pixel portion and its peripheral circuit portion in the CMOS solid-state imaging device of FIG. 1. FIG. 2 is a main part longitudinal cross-sectional view schematically showing a pixel region / transistor forming process of a pixel portion and its peripheral circuit portion in the CMOS solid-state imaging device of FIG. 1. FIG. 2 is a main part longitudinal cross-sectional view schematically showing a metal wiring forming process of a pixel portion and its peripheral circuit portion in the CMOS type solid-state imaging device of FIG. 1. FIG. 2 is a main part longitudinal cross-sectional view schematically showing a passivation film forming step of a pixel portion and its peripheral circuit portion in the CMOS type solid-state imaging device of FIG. 1. FIG. 2 is a main part longitudinal cross-sectional view schematically showing a passivation film forming step of a pixel portion and its peripheral circuit portion in the CMOS type solid-state imaging device of FIG. 1. FIG. 2 is a vertical cross-sectional view of a main part schematically showing a color filter / microlens forming process of a pixel part and its peripheral circuit part in the CMOS solid-state imaging device of FIG. 1. It is a top view which shows typically the arrangement | positioning relationship of the pixel part and its peripheral circuit part in the CCD type solid-state image sensor which concerns on Embodiment 2 of this invention. It is a block diagram which shows the schematic structural example of the electronic information apparatus which used the solid-state imaging device containing the solid-state image sensor of the said Embodiment 1 or 2 as an imaging part as Embodiment 3 of this invention. It is a longitudinal cross-sectional view which shows the principal part structural example of the conventional CCD type solid-state image sensor currently disclosed by patent document 1. FIG. It is a longitudinal cross-sectional view which shows the example of a principal part structure of the conventional CMOS type solid-state image sensor.

Explanation of symbols

1 Semiconductor substrate (silicon substrate)
2 Photodiode (light receiving part)
3 Charge Transfer Section 4 Gate Insulating Film 5A, 5B Gate Electrode 6a First Insulating Film 6b Second Insulating Film 6c Third Insulating Film 6d Fourth Insulating Film 6e Fifth Insulating Layer 7 Wiring Layer 7a First Wiring 7b Second Wiring 7c 3rd wiring 7d 4th wiring 8, 8a Passivation film 9 Color filter 10 Micro lens 11A Pixel part 11B Peripheral circuit part 20 CMOS type solid-state image sensor 30 CCD type solid-state image sensor 31 Light-receiving part 32 Charge transfer electrode 33 Vertical transfer path 34 Horizontal Transfer path 35 Output transistor FD Floating diffusion part

Claims (21)

  In a solid-state imaging device having a peripheral circuit unit using a fine transistor around a pixel unit provided with a plurality of light-receiving units that photoelectrically convert image light from a subject, a passivation film serving as a hydrogen supply source is provided. A solid-state imaging device that is set to have different residual hydrogen amounts on the pixel portion and the peripheral circuit portion.   2. The solid-state imaging device according to claim 1, wherein the different residual hydrogen amounts are different between the pixel unit and the peripheral circuit unit depending on a film forming condition of the passivation film. As the conditions for forming the passivation film, the gas type is SiH ₄ or NH ₃ , N ₂ , H ₂ , and the residual hydrogen amount is controlled by the gas flow rate, temperature, pressure, and RF power of each gas type. The solid-state imaging device according to claim 2.   3. The solid-state imaging device according to claim 1, wherein the different residual hydrogen amounts are different between the pixel portion and the peripheral circuit portion depending on a thickness of the passivation film.   5. The solid-state imaging device according to claim 4, wherein a thickness of the passivation film is set to 200 to 500 nm on the pixel portion and set to 30 to 150 nm on the peripheral circuit portion.   The solid-state imaging device according to claim 1, wherein the passivation film is a SiN film formed by plasma CVD.   2. The solid-state imaging device according to claim 1, wherein the passivation film is a stacked film of a SiN film and a SiON film on the pixel portion, and is a SiON film on the peripheral circuit portion.   2. The solid-state imaging device according to claim 1, wherein the passivation film is a SiN film on the pixel portion and a SiON film on the peripheral circuit portion.   The solid-state imaging device according to claim 1, wherein the passivation film is set to a film thickness for suppressing dark voltage on a semiconductor surface in the pixel portion.   10. The solid-state imaging device according to claim 1, wherein the passivation film is configured such that a hydrogen supply amount to the fine transistor is set to a film thickness for suppressing threshold aging variation in the peripheral circuit portion.   The solid-state imaging device according to claim 1, wherein the passivation film is set to a film thickness having a passivation function for blocking moisture.   3. The solid-state imaging device according to claim 1, wherein the passivation film has a film thickness in the peripheral circuit portion that is smaller than a film thickness in the pixel portion.   11. The solid-state imaging device according to claim 1, wherein the fine transistor is a fine transistor having a thin gate film thickness and capable of causing a change with time in a threshold value when an amount of hydrogen supplied from the passivation film is increased. In a manufacturing method of a solid-state imaging device having a peripheral circuit unit using a fine transistor around a pixel unit provided with a plurality of light receiving units that photoelectrically convert image light from a subject and image it,
A passivation film forming step for forming a passivation film serving as a hydrogen supply source in a predetermined film thickness in both the pixel portion and the peripheral circuit portion;
A method of manufacturing a solid-state imaging device, including a passivation film forming step of etching only the passivation film of the peripheral circuit portion to a predetermined thickness. In a manufacturing method of a solid-state imaging device having a peripheral circuit unit using a fine transistor around a pixel unit provided with a plurality of light receiving units that photoelectrically convert image light from a subject and image it,
A first passivation film forming step for forming a passivation film serving as a hydrogen supply source in a predetermined film thickness in both the pixel portion and the peripheral circuit portion;
A method for manufacturing a solid-state imaging device, which includes a second passivation film forming step of forming a passivation film having the same thickness as or different from the passivation film on the passivation film only in the pixel portion. In a manufacturing method of a solid-state imaging device having a peripheral circuit unit using a fine transistor around a pixel unit provided with a plurality of light receiving units that photoelectrically convert image light from a subject and image it,
A first passivation film forming step of forming a passivation film serving as a hydrogen supply source in a predetermined thickness on the pixel portion;
A method for manufacturing a solid-state imaging device, comprising: a third passivation film forming step for forming a passivation film having a residual hydrogen amount smaller than that of the passivation film in a predetermined film thickness in the peripheral circuit portion.   The solid processing according to claim 14, further comprising a sintering process step of performing a sintering process for desorbing residual hydrogen from the passivation film by heat treatment and supplying hydrogen to the pixel portion and the peripheral circuit portion after the passivation film forming step. Manufacturing method of imaging device.   After the second passivation film formation step or the third passivation film formation step, a sintering process is performed to remove residual hydrogen from the passivation film by heat treatment and supply hydrogen to the pixel portion and the peripheral circuit portion. The method for manufacturing a solid-state imaging device according to claim 15, further comprising a processing step.   In the passivation film forming step, the passivation film of the peripheral circuit portion is formed to have a predetermined film thickness by photolithography and dry etching or wet etching so as to have a film thickness that can ensure the reliability of the threshold variation with time of the fine transistor. The manufacturing method of the solid-state image sensor of Claim 14.   In the second passivation film formation step, only the passivation film of the pixel portion has a film thickness for suppressing dark voltage on the semiconductor surface in the pixel portion in addition to the film thickness of the first passivation film formation step. The manufacturing method of the solid-state image sensor of Claim 15 set to.   An electronic information device using the solid-state imaging device according to claim 1 as an image input device in an imaging unit.

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