Method of manufacturing a semiconductor imaging device having a refractive index matching layer

A semiconductor device includes a plurality of photoelectric conversion photodiodes provided on a silicon substrate, and a refractive index matching film provided on each of the photodiodes. The refractive index matching film is composed of an insulating compound layer represented by SiOxNy (0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the compound layer is 1:x:y. The oxygen content of the compound layer is the lowest at the silicon interface with each photodiode and the highest in an upper portion of the compound layer, and the nitrogen content is the highest at the silicon interface with each photodiode and the lowest in the upper portion of the compound layer. Therefore, multiple reflection can be decreased to improve light receiving sensitivity, as compared with a case in which a SiN single layer and a SiO2 single layer are laminated.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates a semiconductor device suitably used for a photoelectric transducer such as a photocoupler or the like, a solid-state imaging device or field-effect imaging device comprising a semiconductor image sensor which receives light incident on an on-chip lens formed on a color filter, a method of manufacturing the semiconductor device, and an apparatus for manufacturing a semiconductor.

More specifically, a refractive index matching film is provided on a photoelectric conversion light-receiving element, and a composition composed of silicon, oxygen and nitrogen which constitute the refractive index matching film is adjusted so that the refractive index of a compound layer constituting the refractive index matching film continuously changes from the refractive index of a silicon oxide film of 1.45 to the refractive index of a silicon nitride film of 2.0. As a result, reflection from the light receiving element can be minimized, and light receiving sensitivity can be improved.

2. Description of the Related Art

In recent years, a video camera and a digital still camera have been increasingly used in many schools, homes and broadcast stations. Such a camera requires a solid-state imaging device. The solid-state imaging device comprises CCD (Charge Coupled Device) imaging devices arranged as photoelectric transducers in a two-dimensional form. The CCD imaging device means a semiconductor device having a structure in which unit elements each comprising a photodiode and a MOS capacitor are regularly arranged. The solid-state imaging device has the function to move a group of charges stored in the surface of a semiconductor substrate along the array direction of electrodes of the MOS capacitors.

Namely, the solid-state imaging device comprises pluralities of photodiodes, MOS capacitors, vertical transfer registers, horizontal transfer registers, and charge detecting amplifiers, which are provided on the semiconductor substrate. When light is applied to a light receiving surface of the solid-state imaging device, the light is converted into signal charges by the photodiodes, and then stored in the MOS capacitors. The signal charges stored in the MOS capacitors are transferred by the vertical transfer registers (referred to as “vertical CCD sections” hereinafter) and horizontal transfer registers, and finally detected by the charge detecting amplifiers and read as analogue received signals.

FIG. 14is a sectional view showing an example of a configuration of a solid-state imaging device10of a first conventional example. As shown inFIG. 14, a semiconductor buried layer (P-WELL)1is formed on a N-type silicon substrate11, the P-WELL1comprising photodiodes PD each having a N-type impurity region (impurity diffused layer)2, and vertical CCD sections12each having a N-type impurity region (impurity diffused layer)3. The P-WELL1further comprises transfer gate sections13for reading out signal charges from the photodiodes PD to the vertical CCD sections12, to isolate the silicon substrate11.

The N-type impurity region2constituting each of the photodiodes PD is isolated from the N-type impurity region3constituting the corresponding vertical CCD section12by a channel stopper4comprising a P-type impurity region. Furthermore, a transfer electrode17is provided on each of the vertical CCD sections12through a gate insulating film (silicon oxide film)14.

The transfer electrodes17of the vertical CCD sections12are covered with a shielding film19composed of aluminum or tungsten through an interlayer insulating film18. The shielding film19has apertures formed above the photodiodes PD to define light-receiving windows21. The shielding film19is coated with a cover film22comprising a silicon oxide film of PSG or the like. Furthermore, a planarizing film23, a color filter24, and microlenses25are formed in order on the cover film22.

The material of the cover film22is not limited to the silicon oxide film, and an example using a silicon nitride film is also known. For example, the technical document, Japanese Unexamined Patent Application Publication No. 60-177778, discloses that a plasma silicon nitride film is formed on a transparent electrode composed of polycrystalline silicon. However, in such a structure in which a silicon nitride film is deposited, an increase in short-wavelength sensitivity is expected due to a multiple interference effect.

Therefore, in the structure shown inFIG. 14in which the silicon interfaces of the photodiodes PD are covered directly with the cover film22, a loss of incident light is increased due to surface reflection from the N-type silicon substrate11to fail to obtain sufficient light receiving sensitivity.

In addition, in the structure in which the plasma silicon nitride film is formed below the planarizing film23, ripple occurs in spectral transmittance due to an interference effect between a silicon nitride film serving as the interlayer insulating film18and a silicon nitride film serving as the gate insulating film14provided below the interlayer insulating film18. Therefore, the spectral characteristics of the color filter layer24easily vary.

In order to solve the above-described problem, for example, Patent Publication No. 3196727 discloses a technique for forming an anti-reflection film on photodiodes PD.FIG. 15is a sectional view showing an example of a construction of a solid-state imaging device10′ of a second conventional example.

The solid-state imaging device10′ shown inFIG. 15comprises a N-type silicon substrate11on a surface of which photodiodes PD are formed for obtaining signal charges. Each of the photodiodes PD comprises a N-type impurity region (impurity diffused region)2.

Furthermore, a silicon oxide thin film serving as a gate insulating film14is formed on the silicon substrate11, and a silicon nitride film serving as an anti-reflection thin film15having a refractive index higher than that of the silicon oxide film14and lower than that of the silicon substrate11is formed on the silicon oxide thin film14. The refractive index of the silicon oxide film14is about 1.45, and the refractive index of the silicon nitride film is about 2.0. Assuming that the refractive index is n, the thickness t of each of the silicon oxide film and the silicon nitride film is set to satisfy the relationship 350/(4n) nm≦t≦450/(4n) nm. These films14and15are formed for preventing a dark current.

When the thickness of each of the silicon oxide film and the silicon nitride film is set as described above, the anti-reflection film15having relatively flat reflection in the visible light region can be obtained. By appropriately setting the thickness of each of the silicon oxide film and the silicon nitride film, reflectance can be suppressed to an average of about 12 to 13%, and is thus suppressed to about ⅓ of the reflectance of the conventional silicon substrate11of about 40%.

Like in the first conventional example, transfer electrodes17are formed on the vertical CCD sections12through a silicon oxide film. Furthermore, a shielding film19composed of aluminum or tungsten is deposited through an interlayer insulating film18, the shielding film19having apertures respectively formed above the photodiodes PD.

A cover film22is formed on the shielding film19. The cover film22comprises a PSG film serving as a silicon-based passivation film, and has a refractive index of about 1.46. In addition, a planarizing layer23, a filter layer24, and microlenses25are formed on the cover film22. The refractive index of the color filter layer24is about 1.5 to 1.6, and is thus substantially the same as the passivation film.

However, the solid-state imaging device (simply referred to as the “semiconductor device” hereinafter)10′ of the second conventional example shown inFIG. 15has the following problems:

(1) The refractive index of the cover film22formed above the anti-reflection film (silicon nitride film)15is about 1.4 to 1.6, and is greatly different from the refractive index 2.0 of the silicon nitride film serving as the anti-reflection film15. Therefore, reflection occurs between the anti-reflection film15and the cover film22.

(2) The reflection between the anti-reflection film15and the cover film22is associated with reflection from the photodiodes (light receiving elements) PD, thereby causing a smear and inhibiting an improvement in light receiving sensitivity.

SUMMARY OF THE INVENTION

The present invention has been achieved for solving the above problems, and an object of the present invention is to provide a semiconductor device having a structure in which refractive index matching between upper and lower films is controlled so as to minimize reflection from a light receiving element and to improve light receiving sensitivity, a method of manufacturing the semiconductor device, and an apparatus for manufacturing a semiconductor.

In an aspect of the present invention, a semiconductor device comprises a substrate, and a compound layer provided on the substrate, wherein the compound layer is represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the compound layer is 1:x:y, the oxygen content is the lowest near the interface with the substrate and the highest in an upper portion of the compound layer, and the nitrogen content is the highest near the interface with the substrate and the lowest in the upper portion of the compound layer.

In another aspect of the present invention, a semiconductor device comprises a semiconductor substrate, and an insulating compound layer provided on the semiconductor substrate, wherein the insulating compound layer is represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer is 1:x:y, the oxygen content is the lowest at the interface with the semiconductor substrate and the highest in au upper portion of the insulating compound layer, and the nitrogen content is the highest at the interface with the semiconductor substrate and the lowest in the upper portion of the insulating compound layer.

In a further aspect of the present invention, a semiconductor device for photoelectrically converting received light to output a received light signal comprises a semiconductor substrate, a plurality of photoelectric conversion light receiving elements provided on the semiconductor substrate, and a refractive index matching film provided on the light receiving elements, wherein the refractive index matching film comprises an insulating compound layer represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the compound layer is 1:x:y, the oxygen content of the compound layer is the lowest at the interface with each light receiving element and the highest in au upper portion of the compound layer, and the nitrogen content of the compound layer is the highest at the interface with each light receiving element and the lowest in the upper portion of the compound layer.

In a still further aspect of the present invention, a method of manufacturing a semiconductor device for photoelectrically converting received light to output a received light signal comprises a step of forming a plurality of photoelectric conversion light receiving elements on a semiconductor substrate, and a step of forming a refractive index matching film on each of the light receiving elements formed on the semiconductor substrate, wherein the refractive index matching film comprises an insulating compound layer represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer is 1:x:y, the oxygen content of the compound layer is the lowest at the interface with each light receiving element and the highest in au upper portion of the compound layer, and the nitrogen content of the compound layer is the highest at the interface with each light receiving element and the lowest in the upper portion of the compound layer.

In a further aspect of the present invention, an apparatus for manufacturing a semiconductor device for photoelectrically converting received light to output a received light signal comprises a formation means for forming a plurality of photoelectric conversion light receiving elements on a semiconductor substrate, and a deposition means for depositing a refractive index matching film on each of the light receiving elements formed on the semiconductor substrate, wherein in depositing the refractive index matching film by the deposition means, an insulating compound layer represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer is 1:x:y is deposited so that the oxygen content of the compound layer is the lowest at the interface with each light receiving element and the highest in an upper portion of the compound layer, and the nitrogen content of the compound layer is the highest at the interface with each light receiving element and the lowest in the upper portion of the compound layer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A semiconductor device, a manufacturing method therefor, and a semiconductor manufacturing apparatus according to embodiments of the present invention will be described below with reference to the drawings.

First Embodiment

FIG. 1is a sectional view showing an example of a structure of a photoelectric transducer100according to a first embodiment of the present invention.

In this embodiment, a refractive index matching film is provided on each of photoelectric conversion light receiving elements, and the refractive index matching film comprises an insulating compound layer represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer is 1:x:y. In addition, the oxygen content of the compound layer is the lowest at the interface with each light receiving element and the highest in an upper portion of the compound layer, and the nitrogen content of the compound layer is the highest at the interface with each light receiving element and the lowest in the upper portion of the compound layer.

In this embodiment, the refractive index of the compound layer serving as the refractive index matching film is continuously changed from the refractive index of a silicon oxide film of 1.45 to the refractive index of a silicon nitride film of 2.0, to minimize reflection from each light receiving element and improve light receiving sensitivity.

The photoelectric transducer100shown inFIG. 1is an example of semiconductor devices for photoelectrically converting received light to output received light signals. The photoelectric transducer100is preferably applied to a photocoupler, a solid-state imaging device or field-effect imaging device comprising a solid-state imaging device which receives light incident from on-chip lenses provided on a color filter.

The photoelectric transducer100comprises a N-type silicon substrate (N-sub)11as an example of a semiconductor substrate. The silicon substrate11comprises a plurality of HAD (Hole Accumulated Diode) sensors (simply referred to as “photodiodes PD” hereinafter) as an example of photoelectric conversion light receiving elements. In this embodiment, the photodiode PD (charge coupled imaging device) of one pixel is described.

In the photoelectric transducer100, a P-type impurity buried layer (P-WELL)1is provided on the N-type silicon substrate11. The P-WELL1contains a photodiode PD comprising a N-type impurity region (layer)2, and a vertical CCD (vertical transfer register) section12comprising a N-type impurity region (layer)3. Furthermore, the photodiode PD is separated from the vertical CCD section12by a transfer gate13so as to read a signal charge from the photodiode PD to the vertical CCD section12.

Furthermore, a silicon oxide film (SiO2film) serving as a gate insulating film14having a predetermined thickness is provided above the interface of the silicon substrate11, and a silicon nitride film (Si3N4film) serving as an anti-reflection film15is provided on the gate insulating film14. The thickness t of each of the gate insulating film14and the anti-reflection film15is defined in the range of 10 nm≦t≦40 nm. The thickness of each of the two films is preferably set to about 25 to 35 nm. By selecting the thickness t within this range, no adverse effect of reflection occurs, and a dark current can be prevented to prevent stress in film formation.

Furthermore, a refractive index matching film16having a thickness of about 1.0 μm to 2.0 μm is provided on the surface of the anti-refection film (silicon nitride film)15including the portion above the photodiode PD. The gate insulating film14and the anti-reflection film15are sandwiched between the photodiode PD and the refractive index matching film16. The refractive index matching film16comprises an insulating compound layer represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer is 1:x:y. The oxygen content of the insulating compound layer is the lowest at the silicon interface with the photodiode PD and the highest in an upper portion of the compound layer, and the nitrogen content of the insulating compound layer is the highest at the silicon interface with the photodiode PD and the lowest in the upper portion of the compound layer.

The refractive index matching film16comprises the bottom composed of silicon nitride, and the top composed of silicon oxide. Although the insulating compound layer may comprise a plurality of insulating layers having a constant thickness, the insulating compound layer preferably comprises layers having thicknesses continuously varying to satisfy the above-described conditions of the nitrogen and oxygen contents. In this case, reflection within the layer can be minimized.

In the refractive index matching film16, the oxygen content of the compound layer is defined in the range of 0≦x<2 so that the oxygen content is the lowest at the silicon interface with the photodiode PD and the highest in the upper portion, and the nitrogen content of the compound layer is defined in the range of 0≦y<4/3 so that the nitrogen content is the highest at the silicon interface with the photodiode PD and the lowest in the upper portion.

Namely, in the compound layer, oxygen is continuously distributed based on the oxygen content condition of 0≦x<2 so that the oxygen content is the lowest at the silicon interface with the photodiode PD and the highest in the upper portion. Also, in the compound layer, nitrogen is continuously distributed based on the nitrogen content condition of 0≦y<4/3 so that the nitrogen content is the highest at the silicon interface with the photodiode PD and the lowest in the upper portion.

The insulating compound layer is preferably deposited by a low-pressure CVD apparatus. During deposition, an oxygen gas flow rate is controlled according to a continuous increasing function (including primary and secondary functions). At the same time, a nitrogen gas flow rate is controlled according to a decreasing function (including primary and secondary functions). In this embodiment, the compound layer represented by SiOxNysatisfies 4=2x+3y, and x increases from the bottom to the top.

Furthermore, a transfer electrode17is formed on the vertical CCD section12through the gate insulating film (silicon oxide film)14. The transfer electrode17is covered with a shielding film19composed of aluminum or tungsten through an interlayer insulating film18. The shielding film19has an aperture formed above the photodiode PD. The aperture functions as a light receiving window21. The shielding film19is coated with a cover film22comprising a silicon oxide film of PSG or the like.

FIG. 2is a conceptual diagram showing an example of a structure of an insulating compound layer16′ represented by SiOxNy(0≦x and y). InFIG. 2, the refractive index matching film16comprises the insulating compound layer16′ represented by SiOxNy(0≦x and y). The refractive index matching film16is formed by patterning the insulating compound layer16′, and comprises the bottom composed of silicon nitride (Si3N4). The refractive index of a silicon nitride film is about 2.0, and is higher than that of a silicon oxide film.

The silicon nitride film is generally formed by SiH4gas and ammonia gas used as raw material gases according to chemical reaction represented by the following formula (1):
3SiH4+4NH3→Si3N4+12H2(1)

The top of the refractive index matching film16comprises silicon oxide (SiO2). The refractive index of a silicon oxide film is about 1.45. The silicon oxide film is generally formed by SiH4gas and O2gas used as raw material gases according to chemical reaction represented by the following formula (2):
SiH4+2O2→SiO2+2H2O  (2)

In the insulating compound layer16′ represented by SiOxNy(0≦x and y), the film quality continuously (in analog) changes between the bottom composed of silicon nitride and the top composed of silicon oxide. The refractive index of the compound layer16′ continuously changes from the refractive index of the silicon oxide film of 1.45 to the refractive index of the silicon nitride film of 2.0. This is optimum for the refractive index matching film16.

FIG. 3is a conceptual diagram showing an example of the relationship between the oxygen and nitrogen contents of the insulating compound layer16′ represented by SiOxNy(0≦x and y). InFIG. 3, the oxygen (O2) and nitrogen (N2) contents (%) are shown on the ordinate, and the deposition position in the deposition direction and refractive index of the insulating compound layer16′ are shown on the abscissa.

The insulating compound layer16′ is preferably deposited by using a low-pressure CVD apparatus. During deposition, as shown inFIG. 3, an oxygen gas flow rate is controlled according to a continuous increasing function (including primary and secondary functions). At the same time, a nitrogen gas flow rate is controlled according to a decreasing function (including primary and secondary functions). In this embodiment, the compound layer16′ represented by SiOxNysatisfies 4=2x+3y, and x increases from the bottom to the top.

Therefore, in the photoelectric transducer100of the first embodiment of the present invention, the refractive index of the compound layer16′ serving as the refractive index matching film16can be continuously changed from the refractive index of the silicon oxide film of 1.45 to the refractive index of the silicon nitride film of 2.0, as compared with a case in which a silicon nitride single film and a silicon oxide single film are simply laminated. Therefore, a boundary between the silicon nitride film and the silicon oxide film can be removed, thereby minimizing reflection from the photodiode PD.

Therefore, multiple reflection is decreased to improve light receiving sensitivity, as compared with the case in which the silicon nitride single film and the silicon oxide single film are simply laminated. Furthermore, diffused reflection due to multiple reflection can be suppressed to improve a smear. The refractive index matching film16comprising the insulating compound layer16′ causes no stress, and thus causes less dark current.

Semiconductor Manufacturing Apparatus

FIG. 4is a block diagram showing an example of a configuration of a semiconductor manufacturing apparatus300according to an embodiment of the present invention.

The semiconductor manufacturing apparatus300shown inFIG. 4is an apparatus for manufacturing the photoelectric transducer100shown inFIG. 1, and the like. In the semiconductor manufacturing apparatus300, a plurality of photoelectric conversion photodiodes PD are previously formed on the silicon substrate11by a formation means41such as an ion implantation apparatus or the like. Then, the refractive index matching film16is deposited each the photodiode PD by a low-pressure CVD apparatus30as an example of deposition means.

The low-pressure CVD apparatus30comprises a chamber31in which a dispersion head32for discharging a raw material gas, and a susceptor33for mounting a wafer thereon are provided. Also, an exhaust treatment means34, a shutter35for inserting and discharging the wafer, raw material gas cylinders36A to36C, gas regulating valves37A to37C, and a control device38are provided outside the chamber31.

The shutter35is connected to the control device38so that the shutter35is controlled to be opened and closed for inserting and discharging the semiconductor wafer11′ into and from the chamber31. The exhaust treatment means34is also connected to the control device38so that the exhaust treatment means34is controlled to evacuate the chamber31and discharge exhaust gas. The semiconductor wafer11′ is mounted on the susceptor33, and the control device38is connected to the susceptor33so as to heat the semiconductor wafer11′ to a predetermined temperature and cool the semiconductor wafer11′. Also, the dispersion head32is provided above the susceptor33in the chamber31to emit raw material gases A, B and C. As the raw material gases A, B and C, SiH4, NH3, O2, and the like can be used.

A supply port of the dispersion head32is extended to the outside of the chamber31, and connected to the raw material gas cylinders36A to36C through the gas regulating valves37A to37C, respectively. The raw material gas cylinders36A,36B and36C are filled with the raw material gases A, B and C, respectively. The gas regulating valves37A to37C can be operated by the control device38by remote control. The control device38remote-controls the gas regulating valve37A to regulate a flow rate of the raw material gas A, remote-controls the gas regulating valve37B to regulate a flow rate of the raw material gas B, and remote-controls the gas regulating valve37C to regulate a flow rate of the raw material gas C.

In forming the refractive index matching film16shown inFIG. 1, the control device38controls the deposition of the insulating compound layer16′ represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer16′ is 1:x:y so that the oxygen content of the insulating compound layer16′ is the lowest at the silicon interface with the photodiode PD and the highest in an upper portion of the compound layer16′, and the nitrogen content of the insulating compound layer16′ is the highest at the silicon interface with the photodiode PD and the lowest in the upper portion of the compound layer16′.

In this embodiment, in order that the oxygen content of the compound layer16′ is the lowest at the silicon interface with the photodiode PD, and is the highest in the upper portion, the oxygen content of the compound layer16′ is previously set to 0≦x<2. Also, in order that the nitrogen content of the compound layer16′ is the highest at the silicon interface with the photodiode PD, and is the lowest in the upper portion, the nitrogen content of the compound layer16′ is previously set to 0≦y<4/3. The refractive index matching film16is deposited based on these settings.

Next, an example of an operation of the semiconductor manufacturing apparatus300will be described. In this example, a plurality of photoelectric conversion photodiodes PD are previously formed on the semiconductor wafer (silicon substrate)11′ by the formation means41such as the ion implantation apparatus. Then, the semiconductor wafer11′ is transferred from the formation means41to the low-pressure CVD apparatus30, and the refractive index matching film16is formed on each of the photodiodes PD formed on the semiconductor wafer11′.

On the assumption that the refractive index matching film16is deposited, the control device38controls the shutter35to open and close it, and the semiconductor wafer11′ is transferred into the chamber31and mounted on the susceptor33. Then, the control device38controls the exhaust treatment means34to exhaust air from the chamber31to form a vacuum in the chamber31. The temperature of the susceptor33is controlled by the control device38to, for example, heat the semiconductor wafer11′ to a predetermined temperature.

Then, the gas regulating valves37A to37C are remote-controlled by the control device38to emit the raw material gases A, B and C from the dispersion head32provided above the susceptor33in the chamber31. The raw material gases A, B and C include SiH4, NH3, O2, and the like.

In the chamber31, a vapor phase reaction I of the raw material gases A, B and C takes place, and a surface reaction II takes place on the semiconductor wafer11′ according to the above-described formulas (1) and (2). The exhaust gas is discharged to the outside by the exhaust treatment means34.

For example, when the molar ratio 1:x:y of silicon, oxygen and nitrogen, and the deposition time are set by the control device38, the gas regulating valve37C is controlled according to the continuous increasing function (including primary and secondary functions) shown inFIG. 3to regulate the flow rate of oxygen gas. At the same time, the gas regulating valve37B is controlled according to the continuous decreasing function (including primary and secondary functions) shown inFIG. 3to regulate the flow rate of nitrogen gas (NH3).

In this control operation, the oxygen content of the compound layer16′ is set to the lowest at the silicon interface with each photodiode PD, and the highest in the upper portion, and the oxygen flow rate is continuously regulated based on the oxygen content of 0≦x<2 in the compound layer16′. Also, the nitrogen content of the compound layer16′ is set to the highest at the silicon interface with each photodiode PD, and the lowest in the upper portion, and the nitrogen flow rate is continuously regulated based on the nitrogen content of 0≦y<4/3 in the compound layer16′.

Consequently, the insulating compound layer16′ represented by SiOxNy(0≦x and y) is deposited for the refractive index matching film16so that the oxygen content of the compound layer16′ is the lowest at the silicon interface with each photodiode PD and the highest in the upper portion of the compound layer16′, and the nitrogen content of the compound layer16′ is the highest at the silicon interface with each photodiode PD and the lowest in the upper portion of the compound layer16′.

In this way, the semiconductor manufacturing apparatus300of the present invention is capable of manufacturing a semiconductor device100with high reproducibility, in which the refractive index of the compound layer16′ serving as the refractive index matching film16is continuously changed from the refractive index of a silicon oxide film of 1.45 to the refractive index of a silicon nitride film of 2.0, as compared with the case in which a silicon nitride single film and a silicon oxide single film are simply laminated to form the semiconductor device100. Therefore, the semiconductor device100with high reliability can be manufactured.

Method of Manufacturing Semiconductor Device

FIGS. 5 to 8are drawings showing steps in an example of the formation of the photoelectric transducer100of the first embodiment of the present invention.

This embodiment is based on the condition that the photoelectric transducer100comprising the gate insulating film14, the anti-reflection film15and the refractive index matching film16shown inFIG. 1is manufactured. Under this manufacturing condition, the silicon substrate11(semiconductor wafer11′) having the transfer electrodes17, the photoelectric conversion photodiodes PD, the gate insulating film14and the anti-reflection film15shown inFIG. 5Ais first prepared. In the semiconductor wafer11′, a predetermined impurity is implanted into the N-type silicon substrate11shown inFIG. 5Ato form the P-type semiconductor buried layer (P-WELL)1in which the photodiodes PD each comprising the N-type impurity region (layer)2and the vertical CCD sections12each comprising the N-type impurity region (layer)3are formed.

In this structure, the transfer gate section13is formed as a region for reading a signal charge from each of the photodiodes PD to the corresponding vertical CCD section12. In this example, a silicon oxide film having a predetermined thickness is formed on each of the photodiodes PD before the refractive index matching film16is formed on each photodiode PD. The thickness t of the silicon oxide film is defined in the range of 10 nm≦t≦40 nm, and preferably set to 30 nm. By setting the thickness to this value, reflection and stress can be prevented. Furthermore, polysilicon is deposited over the entire surface of the gate insulating film14, and then selectively etched to form the transfer electrodes17.

Then, as shown inFIG. 5B, the semiconductor wafer11′ is re-oxidized to form the interlayer insulating film18comprising a silicon oxide film. The transfer electrodes17can be isolated by the interlayer insulating film18. Then, as shown inFIG. 6A, the insulating compound layer16′ is selectively formed over the entire surface of the semiconductor wafer11′ to form the refractive index matching films16. Since the thickness of the compound layer16′ must be strictly controlled, the compound layer16′ is formed by the low-pressure CVD apparatus30shown inFIG. 4. Each of the refractive index matching films16comprises the bottom composed of silicon nitride in contact with the silicon interface with each photodiode PD, and the top composed of silicon oxide.

Therefore, each of the refractive index matching films16comprises the insulating compound layer16′ represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer16′ is 1:x:y. In addition, the oxygen content of the compound layer16′ is the lowest at the silicon interface with each photodiode PD and the highest in the upper portion of the compound layer16′, and the nitrogen content of the compound layer16′ is the highest at the interface with each photodiode PD and the lowest in the upper portion of the compound layer16′.

In forming the refractive index matching films16, in order to set the oxygen content of the compound layer16′ to the lowest at the silicon interface with each photodiode PD and the highest in the upper portion of the compound layer16′, the oxygen content in the compound layer16′ is defined in the range of 0≦x<2. Similarly, in order to set the nitrogen content of the compound layer16′ to the highest at the interface with each photodiode PD and the lowest in the upper portion of the compound layer16′, the nitrogen content in the compound layer16′ is defined in the range of 0≦y<4/3.

In order to continuously change the oxygen and nitrogen contents of the compound layer16′, the nitrogen and oxygen flow rates in the low-pressure CVD apparatus30may be continuously changed during the formation of the film16. Namely, in order to set the oxygen content of the compound layer16′ to the lowest at the silicon interface with each photodiode PD and the highest in the upper portion of the compound layer16′, the oxygen flow rate is regulated to continuously distribute based on the oxygen content of 0≦x<2 in the compound layer16′.

In order to set the nitrogen content of the compound layer16′ to the highest at the silicon interface with each photodiode PD and the lowest in the upper portion of the compound layer16′, the nitrogen flow rate is regulated to continuously distribute based on the oxygen content of 0≦y<4/3 in the compound layer16′. In this example, the compound layer represented by SiOxNysatisfies 4=2x+3y, and x increases from the bottom to the top.

Then, as shown inFIG. 6A, a resist film42formed on the compound layer16′ is selectively patterned as follows. First, a resist material is coated over the entire surface of the compound layer16′, and then exposed and developed by using, as a mask, a reticle having a predetermined aperture pattern formed by baking. The aperture pattern has a shape for forming the light receiving windows21(not shown) above the photodiodes PD. Then, the excessive resist material is removed to pattern the resist film42.

Then, the compound layer16′ is selectively etched through the resist film42used as the mask. The etching may be wet etching or dry etching. The wet etching is performed with an etchant comprising diluted hydrofluoric acid or phosphoric acid. As a result, as shown inFIG. 6B, the compound layer16′ (film) can be left only above each of the photodiodes PD, to form the refractive index matching films16.

Then, as shown inFIG. 7A, aluminum or tungsten used as a material19′ for the shielding film19is deposited over the entire surface of the silicon substrate11by the same method as a conventional method. Then, as show inFIG. 7B, a resist film43formed on the shielding film material19′ is selectively patterned as follows.

First, a resist material is coated over the entire surface of the shielding film material19′, and then exposed and developed by using, as a mask, a reticle having a predetermined aperture pattern formed by baking. The aperture pattern has a shape for forming the light receiving windows21shown inFIG. 7Babove the photodiodes PD. Then, the excessive resist material is removed to pattern the resist film43.

Then, the shielding film material19′ is selectively etched through the resist film43used as the mask. The etching is anisotropic dry etching. As a result, as shown inFIG. 8A, the peripheries of the transfer electrodes17can be covered without contact with the refractive index matching films16above the photodiodes PD. The reason for preventing contact between the shielding film material19′ and the refractive index matching films16is to prevent a smear. When the shielding film material19′ is overlapped with the refractive index matching film16, a smear occurs.

Then, the cover film22comprising, for example, a BPSG film is formed over the entire surface of the silicon substrate11on which the shielding film19is formed. The BPSG film is used as the cover film22. In order to shape the BPSG film used as the cover film22, a reflow step is performed. In this step, a heat treatment temperature is about 800° C. In the reflow step, the BPSG film is made convex in the interfacial direction to form an original shape of a lens referred to as a layer lens. Then, as shown inFIG. 8B, the planarizing film23is formed over the entire surface of the silicon substrate11, and the color filter layer24and the microlenses25are formed. The forming step is finished to complete the photoelectric transducer100shown inFIG. 1.

The above-described method of manufacturing the photoelectric transducer100of the first embodiment of the present invention is capable of manufacturing the photoelectric transducer100with high reproducibility, in which the refractive index of the compound layer16′ serving as each refractive index matching film16is continuously changed from the refractive index of the silicon oxide film of 1.45 to the refractive index of the silicon nitride film of 2.0, as compared with the case in which a silicon nitride single film and a silicon oxide single film are simply laminated.

Therefore, the refractive index can be continuously changed in the order of the refractive index of the cover film22, the refractive index of the top of the refractive index matching film16, the refractive index of the bottom of the refractive index matching film16, and the refractive index of the anti-reflection film15, and the total refractive index can be changed in an analogue manner. Thus, the photoelectric transducer100having high reliability can be provided, as compared with a case in which films having different refractive indexes are laminated.

In this embodiment, the oxygen content of the compound layer is the lowest at the interface with each light receiving element and the highest in the upper portion of the compound layer, and the nitrogen content of the compound layer is the highest at the interface with each light receiving element and the lowest in the upper portion of the compound layer. However, the lowest oxygen content and the highest nitrogen content are not strictly at the interface with each light receiving element. Even when the oxygen and nitrogen contents are respectively the lowest and the highest near the interface with each light receiving element, the same effect as described above can be exhibited. Namely, the highest oxygen content may be set at a position above the position of the highest nitrogen content. Also, the oxygen and nitrogen contents are not necessarily continuously changed over the entire region of the compound layer, but the oxygen or nitrogen content may be constant in a region of the compound layer.

Second Embodiment

FIG. 9is a sectional view showing an example of a structure of a photoelectric transducer200according to a second embodiment of the present invention.

The photoelectric transducer200shown inFIG. 9is another example of semiconductor devices, in which a refractive index matching film16is formed directly on the silicon interface of each photodiode PD, and a silicon nitride single film and a gate insulating film14are omitted from the silicon interface so that the refractive index matching film16also performs the function as an anti-reflection film15, unlike in the photoelectric transducer100of the first embodiment.

The photoelectric transducer200is preferably applied to a photocoupler, a solid-state imaging device or field-effect imaging device comprising a solid-state imaging device which receives light incident from on-chip lenses provided on a color filter. The photoelectric transducer200comprises, for example, a N-type silicon substrate11. Like in the first embodiment, the silicon substrate11comprises a plurality of HAD (Hole Accumulated Diode) sensors (simply referred to as “photodiodes PD” hereinafter). In this embodiment, the photodiode PD (charge coupled imaging device) of one pixel is described.

In the photoelectric transducer200, a P-type impurity buried layer (P-WELL)1is provided on the N-type silicon substrate11. The P-WELL1contains the photodiode PD comprising a N-type impurity region (layer)2, and a vertical CCD section12comprising a N-type impurity region (layer)3. Furthermore, the photodiode PD is separated from the vertical CCD section12by a transfer gate13so as to read a signal charge from the photodiode PD to the vertical CCD section12.

Furthermore, a silicon oxide film (SiO2film) serving as a gate insulating film14having a predetermined thickness is provided on the interface of the silicon substrate11. However, unlike in the first embodiment, the single-layer gate insulating film14and silicon nitride film are not provided on the photodiode PD. Namely, the refractive index matching film16having a thickness of about 1.0 μm to 2.0 μm is provided directly on the photodiode PD. Namely, the bottom composed of silicon nitride in the refractive index matching film16functions as the anti-reflection film15.

Like in the first embodiment, the refractive index matching film16comprises an insulating compound layer16′ represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer16′ is 1:x:y. The oxygen content of the insulating compound layer16′ is the lowest at the silicon interface with the photodiode PD and the highest in au upper portion of the compound layer16′, and the nitrogen content of the insulating compound layer is the highest at the silicon interface with the photodiode PD and the lowest in the upper portion of the compound layer16′.

The refractive index matching film16comprises the bottom composed of silicon nitride, and the top composed of silicon oxide. Although the insulating compound layer16′ may comprise a plurality of insulating layers having a constant thickness, the insulating compound layer16′ preferably comprises layers having thicknesses continuously varying to satisfy the above-described conditions of the nitrogen and oxygen contents. In this case, reflection within the layer can be minimized.

In the refractive index matching film16, the oxygen content of the compound layer16′ is defined in the range of 0≦x<2 so that the oxygen content is the lowest at the silicon interface with the photodiode PD and the highest in the upper portion, and the nitrogen content of the compound layer16′ is defined in the range of 0≦y<4/3 so that the nitrogen content is the highest at the silicon interface with the photodiode PD and the lowest in the upper portion.

Namely, in the compound layer16′, oxygen is continuously distributed based on the oxygen content condition of 0≦x<2 so that the oxygen content is the lowest at the silicon interface with the photodiode PD and the highest in the upper portion. Also, in the compound layer16′, nitrogen is continuously distributed based on the nitrogen content condition 0≦y<4/3 so that the nitrogen content is the highest at the silicon interface with the photodiode PD and the lowest in the upper portion.

Like in the first embodiment, the insulating compound layer16′ is preferably deposited by the low-pressure CVD apparatus30. In the deposition, an oxygen gas flow rate is controlled according to a continuous increasing function (including primary and secondary functions). At the same time, a nitrogen gas flow rate is controlled according to a decreasing function (including primary and secondary functions). In this embodiment, the compound layer16′ represented by SiOxNysatisfies 4=2x+3y, and x increases from the bottom to the top.

Furthermore, like in the first embodiment, a transfer electrode17is formed on the vertical CCD section12through the silicon oxide film. The transfer electrode17is covered with a shielding film19composed of aluminum or tungsten through an interlayer insulating film18. The shielding film19has an aperture formed above the photodiode PD. The aperture functions as a light receiving window21. The shielding film19is coated with a cover film22comprising a silicon oxide film of PSG or the like.

In this way, in the photoelectric transducer200of the second embodiment of the present invention, the refractive index matching film16is provided directly on the silicon interface of the photodiode PD, and the refractive index of the compound layer16′ serving as the refractive index matching film16can be continuously changed from the refractive index of the silicon oxide film of 1.45 to the refractive index of the silicon nitride film of 2.0, as compared with a case in which a silicon nitride single film and a silicon oxide single film are simply laminated. Therefore, a boundary between the silicon nitride film and the silicon oxide film is absent, thereby minimizing reflection from the photodiode PD.

Therefore, multiple reflection is decreased to improve light receiving sensitivity, as compared with the case in which the silicon nitride single film and the silicon oxide single film are simply laminated. Furthermore, diffused reflection due to multiple reflection can be suppressed to improve a smear. The refractive index matching film16comprising the insulating compound layer16′ causes no stress, and thus causes less dark current.

Method of Manufacturing Semiconductor Device

FIGS. 10 to 13are drawings showing steps (first to fourth) in an example of the formation of the photoelectric transducer200of the second embodiment of the present invention.

This embodiment is based on the condition that the photoelectric transducer200shown inFIG. 9is manufactured. Under this manufacturing condition, the silicon substrate11(semiconductor wafer11′) having the transfer electrode17and the photoelectric conversion photodiode PD shown inFIG. 10Ais first prepared.

Referring toFIG. 10A, the gate insulating film14and the anti-reflection film15are not provided on the photodiodes PD. In the semiconductor wafer11′, a predetermined impurity is implanted into the N-type silicon substrate11shown inFIG. 10Ato form the P-type semiconductor buried layer (P-WELL)1in which the photodiode PD comprising the N-type impurity region (layer)2and the vertical CCD section12comprising the N-type impurity region (layer)3are formed.

In this structure, the transfer gate section13is formed as a region for reading a signal charge from the photodiode PD to the vertical CCD section12. Furthermore, polysilicon is deposited over the entire surface of the gate insulating film14, and then selectively etched to form the transfer electrode17.

Then, as shown inFIG. 10B, the semiconductor wafer11′ is re-oxidized to form the interlayer insulating film18comprising a silicon oxide film. In this step, the oxide film is completely removed from the silicon interface of the photodiode PD by a plurality of times of dry or wet etching. The transfer electrode17can be isolated by the interlayer insulating film18.

Then, as shown inFIG. 11A, the insulating compound layer16′ is selectively formed over the entire surface of the semiconductor wafer11′ to form the refractive index matching film16. Since the thickness of the compound layer16′ must be strictly controlled, the compound layer16′ is formed by the low-pressure CVD apparatus30shown inFIG. 4. The refractive index matching film16comprises the bottom composed of silicon nitride in contact with the silicon interface of the photodiode PD, and the top composed of silicon oxide.

Therefore, the refractive index matching film16comprises the insulating compound layer16′ represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer16′ is 1:x:y. In addition, the oxygen content of the compound layer16′ is the lowest at the silicon interface with the photodiode PD and the highest in the upper portion of the compound layer16′, and the nitrogen content of the compound layer16′ is the highest at the interface with the photodiode PD and the lowest in the upper portion of the compound layer16′.

In forming the refractive index matching film16, in order to set the oxygen content of the compound layer16′ to the lowest at the silicon interface with the photodiode PD and the highest in the upper portion of the compound layer16′, the oxygen content in the compound layer16′ is defined in the range of 0≦x<2. similarly, in order to set the nitrogen content of the compound layer16′ to the highest at the interface with the photodiode PD and the lowest in the upper portion of the compound layer16′, the nitrogen content in the compound layer16′ is defined in the range of 0≦y<4/3.

In order to continuously change the oxygen and nitrogen contents of the compound layer16′, the nitrogen and oxygen flow rates in the low-pressure CVD apparatus30may be continuously changed during the formation of the film16. Namely, in order to set the oxygen content of the compound layer16′ to the lowest at the silicon interface with the photodiode PD and the highest in the upper portion of the compound layer16′, the oxygen flow rate is regulated to continuously distribute based on the oxygen content of 0≦x<2 in the compound layer16′.

In order to set the nitrogen content of the compound layer16′ to the highest at the silicon interface with the photodiode PD and the lowest in the upper portion of the compound layer16′, the nitrogen flow rate is regulated to continuously distribute based on the oxygen content of 0≦y<4/3 in the compound layer16′. In this example, the compound layer represented by SiOxNysatisfies 4=2x+3y, and x increases from the bottom to the top.

Then, as shown inFIG. 11A, a resist film42formed on the compound layer16′ is selectively patterned as follows. First, a resist material is coated over the entire surface of the compound layer16′, and then exposed and developed by using, as a mask, a reticle having a predetermined aperture pattern formed by baking. The aperture pattern has a shape for forming the light receiving windows21above the photodiodes PD. Then, the excess resist material is removed to pattern the resist film42.

Then, the compound layer16′ is selectively etched through the resist film42used as the mask. The etching may be wet etching or dry etching. The wet etching is performed with an etchant comprising diluted hydrofluoric acid or phosphoric acid. As a result, as shown inFIG. 11B, the compound layer16′ (film) can be left only above the photodiode PD, to form the refractive index matching film16.

Then, as shown inFIG. 12A, aluminum or tungsten used as a material19′ for the shielding film19is deposited over the entire surface of the silicon substrate11by the same method as a conventional method. Then, as show inFIG. 12B, a resist film43formed on the shielding film material19′ is selectively patterned as follows.

First, a resist material is coated over the entire surface of the shielding film material19′, and then exposed and developed by using, as a mask, a reticle having a predetermined aperture pattern formed by baking. The aperture pattern has a shape slightly larger than a shape for forming the light receiving windows21above the photodiodes PD. Then, the excess resist material is removed to pattern the resist film43.

Then, the shielding film material19′ is selectively etched through the resist film43used as the mask. The etching is anisotropic dry etching. As a result, as shown inFIG. 13A, the peripheries of the transfer electrodes17can be covered without contact with the refractive index matching films16above the photodiodes PD. The reason for preventing contact between the shielding film material19′ and the refractive index matching film16is to prevent a smear. When the shielding film material19′ is overlapped with the refractive index matching film16, a smear occurs.

Then, the cover film22comprising, for example, a BPSG film, is formed over the entire surface of the silicon substrate11on which the shielding film19is formed. In order to shape the BPSG film, a reflow step is performed. In this step, a heat treatment temperature is about 800° C. In the reflow step, the BPSG film is made convex in the interfacial direction to form an original shape of a lens referred to as a layer lens. Then, as shown inFIG. 13B, the planarizing film23is formed over the entire surface of the silicon substrate11, the color filter24, and the microlenses25are formed. The forming step is finished to complete the photoelectric transducer200shown inFIG. 9.

The above-described method of manufacturing the photoelectric transducer200of the second embodiment of the present invention is capable of manufacturing the photoelectric transducer200with high reproducibility, in which the refractive index matching film is deposited directly on the silicon interface of the photodiode PD, and thus the refractive index of the compound layer16′ serving as the refractive index matching film16is continuously changed from the refractive index of the silicon oxide film of 1.45 to the refractive index of the silicon nitride film of 2.0, as compared with the case in which a silicon nitride single film and a silicon oxide single film are simply laminated.

Therefore, the refractive index can be continuously changed in the order of the refractive index of the cover film22, the refractive index of the top of the refractive index matching film16, the refractive index of the bottom of the refractive index matching film16, and the refractive index of the anti-reflection film15, and the total refractive index can be changed in an analogue manner. Thus, the photoelectric transducer200having high reliability can be provided, as compared with the case in which films having different refractive indexes are laminated.

In this embodiment, the oxygen content of the compound layer is the lowest at the interface with each light receiving element and the highest in the upper portion of the compound layer, and the nitrogen content of the compound layer is the highest at the interface with each light receiving element and the lowest in the upper portion of the compound layer. However, the lowest oxygen content and the highest nitrogen content are not strictly at the interface with each light receiving element. Even when the oxygen and nitrogen contents are respectively the lowest and the highest near the interface with each light receiving element, the same effect as described above can be exhibited. Namely, the highest oxygen content may be set at a position above the position of the highest nitrogen content. Also, the oxygen and nitrogen contents are not necessarily continuously changed over the entire region of the compound layer, but the oxygen or nitrogen content may be constant in a region of the compound layer.

As described above, in a semiconductor device of the first embodiment of the present invention, an insulating compound layer is provided on a semiconductor substrate, and the insulating compound layer is represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer is 1:x:y. The oxygen content of the insulating compound layer is the lowest at the interface with the semiconductor substrate and the highest in an upper portion of the compound layer, and the nitrogen content of the insulating compound layer is the highest at the interface with the semiconductor substrate and the lowest in the upper portion of the compound layer.

In this structure, the refractive index of the compound layer serving as a refractive index matching film can be continuously changed from the refractive index of a silicon oxide film of 1.45 to the refractive index of a silicon nitride film of 2.0, as compared with a case in which a silicon nitride single film and a silicon oxide single film are simply laminated. Therefore, a boundary between the silicon nitride film and the silicon oxide film can be removed, thereby minimizing reflection on the light receiving element.

In the semiconductor device of the second embodiment of the present invention, the insulating compound layer of the semiconductor device of the first embodiment is used as a refractive index matching film. Namely, the refractive index matching film is provided on the photoelectric conversion light receiving element, and the refractive index matching film comprises the insulating compound layer represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer is 1:x:y. The oxygen content of the insulating compound layer is the lowest at the interface with the light receiving element and the highest in au upper portion of the compound layer, and the nitrogen content of the insulating compound layer is the highest at the interface with the light receiving element and the lowest in the upper portion of the compound layer.

In this structure, the refractive index of the compound layer serving as the refractive index matching film can be continuously changed from the refractive index of a silicon oxide film of 1.45 to the refractive index of a silicon nitride film of 2.0, as compared with a case in which a silicon nitride single film and a silicon oxide single film are simply laminated. Therefore, a boundary between the silicon nitride film and the silicon oxide film can be removed, thereby minimizing reflection from the light receiving element. Therefore, multiple reflection is decreased to improve light receiving sensitivity, as compared with the case in which the silicon nitride single film and the silicon oxide single film are simply laminated. Furthermore, diffused reflection due to multiple reflection can be suppressed to improve a smear.

In the method of manufacturing the semiconductor device of the present invention, a plurality of photoelectric conversion light receiving elements are formed on the semiconductor substrate, and then the refractive index matching film is formed on the light receiving elements on the semiconductor substrate. The refractive index matching film comprises the insulating compound layer represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer is 1:x:y. The oxygen content of the insulating compound layer is the lowest at the interface with each light receiving element and the highest in au upper portion of the compound layer, and the nitrogen content of the insulating compound layer is the highest at the interface with each light receiving element and the lowest in the upper portion of the compound layer.

This method is capable of manufacturing the semiconductor device with high reproducibility in which the refractive index of the compound layer serving as the refractive index matching film can be continuously changed from the refractive index of a silicon oxide film of 1.45 to the refractive index of a silicon nitride film of 2.0, as compared with a case in which a silicon nitride single film and a silicon oxide single film are simply laminated. Therefore, the semiconductor device with high reliability can be provided.

The apparatus for manufacturing the semiconductor device of the present invention comprises deposition means for depositing the refractive index matching film on the light receiving elements formed on the semiconductor substrate. The refractive index matching film deposited by the deposition means comprises the insulating compound layer represented by SiOxNy(0≦x and y) assuming that the molar ratio of silicon, oxygen and nitrogen of the insulating compound layer is 1:x:y. The oxygen content of the insulating compound layer is the lowest at the interface with each light receiving element and the highest in au upper portion of the compound layer, and the nitrogen content of the insulating compound layer is the highest at the interface with each light receiving element and the lowest in the upper portion of the compound layer.

This apparatus is capable of manufacturing the semiconductor device with high reproducibility in which the refractive index of the compound layer serving as the refractive index matching film can be continuously changed from the refractive index of a silicon oxide film of 1.45 to the refractive index of a silicon nitride film of 2.0, as compared with a case in which a silicon nitride single film and a silicon oxide single film are simply laminated. Therefore, the semiconductor device with high reliability can be provided.

The present invention is preferably applied to a photoelectric conversion device such as a photocoupler or the like, a solid state imaging device or field effect imaging device comprising a semiconductor imaging device for receiving light incident from an on-chip lens provided on a color filter.