CN101425524A - Solid-state imaging device and production method therefor - Google Patents

Solid-state imaging device and production method therefor Download PDF

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Publication number
CN101425524A
CN101425524A CNA2008101710233A CN200810171023A CN101425524A CN 101425524 A CN101425524 A CN 101425524A CN A2008101710233 A CNA2008101710233 A CN A2008101710233A CN 200810171023 A CN200810171023 A CN 200810171023A CN 101425524 A CN101425524 A CN 101425524A
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film
image pickup
waveguide
solid state
pickup device
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CNA2008101710233A
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CN101425524B (en
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菰口徹哉
榎本容幸
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Sony Corp
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Sony Corp
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Priority claimed from JP2002373745A external-priority patent/JP4117545B2/en
Priority claimed from JP2003320920A external-priority patent/JP4120543B2/en
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  • Transforming Light Signals Into Electric Signals (AREA)
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Abstract

By improving the embedding property of a light-transmissive material constituting a waveguide, light collection efficiency is improved, and reliability of a solid-state imaging device is ensured. In a solid-state imaging device including a light-receiving section ( 1 ) which performs photoelectric conversion in response to receipt of light and a waveguide ( 20 ) composed of a light-transmissive material formed in an insulating film 5 which covers a substrate provided with the light-receiving section ( 1 ), in which the waveguide ( 20 ) guides incident light from outside to the light-receiving section ( 1 ), the waveguide ( 20 ) is provided with a forward tapered portion in which the size of the planar shape viewed from the direction of incident light decreases from the light incident side surface toward the light-receiving section.

Description

Solid state image pickup device and manufacture method thereof
The application is dividing an application of the 200380109567.2nd (PCT/JP2003/015939) number application for a patent for invention.
Technical field
The present invention relates to a kind of method that has the solid state image pickup device of waveguiding structure and make this solid state image pickup device.
Background technology
Mos sensor is a kind of solid state image pickup device, in view of its characteristics, as is lower than the power consumption of ccd sensor, and obtains positive exploitation recently.In this mos sensor, different with ccd sensor, the electric charge that is stored in the light receiving part is not to read from imaging area by the inside of reading substrate, the electric charge of storage but read near the light receiving part holding wire as the signal of telecommunication, and export from imaging area through holding wire.Holding wire is known as output signal line, and is arranged on the substrate.Outside output signal line, on substrate, be set to read electrode similarly and supply with signal so that initially read the holding wire that is stored in the electric charge in the light receiving part, and the reset signal line that is provided for wiping the electric charge in the pixel.These holding wires are arranged on the graduation film that covers on the substrate such as the element that reads electrode.In addition, because the quantity of pixel increases in solid state image pickup device, so the light receiving part of each pixel and holding wire must be placed in the very little zone.Therefore, holding wire is formed on the graduation film in the multilayer mode, and in some cases, holding wire can be suspended on the light receiving part.
Figure 27 is the side cross-sectional view of the example of waveguiding structure in the expression routine techniques.As shown in figure 27, in the solid state image pickup device of routine, in order to prevent incident light, by being arranged on the waveguide 20 that covers in the graduation film 11 that reads electrode 15 with incident light direct light receiving unit 1 owing to read the deepening that erratic behavior caused (eclipse) that electrode causes.
But, in this structure, can not avoid the deepening that caused by the holding wire 7 that is arranged on the graduation film 11, and thereby weaken the advantage that waveguide 20 is set widely.In addition, because conventional waveguide 20 is arranged to be assemblied in the space of reading between the electrode 15, wherein read electrode 15 and substantially symmetrically be arranged on the both sides of light receiving part 1, so thereby can not regulate waveguide 20 and satisfy asymmetry or the suspension of holding wire 7 on light receiving part 1 of a plurality of holding wires 7 of being arranged on the graduation film 11 about light receiving part 1.
Summary of the invention
The invention provides a kind of method of conceiving to realize the solid state image pickup device of above-mentioned purpose and making this solid state image pickup device.
That is, in one aspect of the invention, solid state image pickup device comprises a plurality of light receiving parts, and these a plurality of light receiving parts are arranged in the substrate, and produces electric charge in response to incident light; Smoothing layer covers the predetermined element be arranged on the substrate to carry out graduation; Be arranged on the many signal line on the smoothing layer; With the waveguide of each light receiving part that incident light is led, this waveguide is by the space between many signal line.
In another aspect of the present invention, the method for making solid state image pickup device comprises these steps: form dielectric film being provided with on the substrate of light receiving part; Position corresponding to light receiving part in dielectric film forms opening; Form waveguide by in opening, embedding light transmitting material, make that waveguide can be with incident light from the external orientation light receiving part, wherein, in the step that forms opening, during the photoresist patterning is with the formation opening, form resist layer with the forward direction wedge-type shape, and during forming opening, shift the forward direction wedge-type shape by etching, make opening have the forward direction wedge-like portion, look from the incident light direction in this forward direction wedge-like portion, the size of flat shape is dwindled to light receiving part from the surface of light inlet side.
In another aspect of this invention, the method for making solid state image pickup device comprises step: form dielectric film being provided with on the substrate of light receiving part; Position corresponding to light receiving part in dielectric film forms opening; With form waveguide by in opening, embedding light transmitting material, make that waveguide can be with incident light from outer direct light receiving unit, wherein, in the step that forms opening, carry out etch process under etching condition, to form opening, form the forward direction wedge shape thereby pass through to suppress isotropic etching, and opening has the forward direction wedge-like portion thus, look from the incident light direction in this forward direction wedge-like portion, the size of flat shape reduces to light receiving part from the surface of light inlet side.
In another aspect of this invention, the method of making solid state image pickup device is provided, wherein this solid state image pickup device disposes the hole that is arranged on the light receiving part, this hole comprises low-index layer and the high refractive index layer that is embedded in the low-index layer, and this method comprises the steps: to form the low-index layer of covering surfaces; In low-index layer, form opening; With in opening, embed high refractive index layer, repeatedly repeat described step to form the hole.
In another aspect of this invention, provide a kind of method of making solid state image pickup device, wherein this solid state image pickup device comprises: be arranged on the photoelectric conversion section in the Semiconductor substrate; Be arranged in the Semiconductor substrate, between the upper layer film of gate insulating film is arranged; Be formed on the hole that extends to gate insulating film on the light receiving area of photoelectric conversion section from upper layer film; And being embedded in waveguide in the hole, this method comprises the steps: to embed first high-index material that comprises hydrogen and constitute the part of waveguide at least in the hole in being formed at upper layer film; With by first high-index material is heat-treated in the hydrogen environment, and discharge hydrogen to photoelectric conversion section from first high-index material.
Description of drawings
Fig. 1 is the side cross-sectional view of expression according to the topology example of solid state image pickup device of the present invention;
Fig. 2 is the interface side view according to the topology example of the solid state image pickup device of first embodiment of the invention (below be called " embodiment 1 ");
Fig. 3 is according to the concrete example of the flat shape of the forward direction wedge-like portion of solid state image pickup device of the present invention (part 1) explanatory view;
Fig. 4 is according to the concrete example of the flat shape of the forward direction wedge-like portion of solid state image pickup device of the present invention (part 2) explanatory view;
Fig. 5 is according to the concrete example of the flat shape of the forward direction wedge-like portion of solid state image pickup device of the present invention (part 3) explanatory view;
Fig. 6 is according to another example of the flat shape of the forward direction wedge-like portion of solid state image pickup device of the present invention (part 1) side cross-sectional view;
Fig. 7 is according to another example of the flat shape of the forward direction wedge-like portion of solid state image pickup device of the present invention (part 1) side cross-sectional view;
Fig. 8 is the side cross-sectional view (part 1) of the method for solid state image pickup device constructed in accordance;
Fig. 9 is the side cross-sectional view (part 2) of the method for solid state image pickup device constructed in accordance;
Figure 10 is the side cross-sectional view (part 3) of the method for solid state image pickup device constructed in accordance;
Figure 11 is the side cross-sectional view (part 4) of the method for solid state image pickup device constructed in accordance;
Figure 12 is the side cross-sectional view (part 5) of the method for solid state image pickup device constructed in accordance;
Figure 13 A～13K is a side cross-sectional view of making the method for solid state image pickup device according to the embodiment of the invention 2;
Figure 14 A～14K is a side cross-sectional view of making the method for solid state image pickup device according to the embodiment of the invention 3;
Figure 15 A～15K is a side cross-sectional view of making the method for solid state image pickup device according to the embodiment of the invention 4;
Figure 16 A～16K is a side cross-sectional view of making the method for solid state image pickup device according to the embodiment of the invention 5;
Figure 17 is the structural section figure according to the solid state image pickup device of the embodiment of the invention 6;
Figure 18 is the amplification sectional view of the problem that takes place between layer of expressing possibility;
Figure 19 is the explanatory view of the concrete diameter of two adjacent layers of expression;
Figure 20 is illustrated in the sectional view that the upper strata in the hole that forms in the structure shown in Figure 17 has the situation of wedge side wall;
Figure 21 is illustrated in the sectional view that structure mesopore shown in Figure 17 comprises three layers situation;
Figure 22 is illustrated in shown in Figure 17 the sectional view that two-layer hole in the structure forms the situation with wedge side wall;
Figure 23 A～23K is a side cross-sectional view of making the method for solid state image pickup device according to the embodiment of the invention 7;
Figure 24 is the sectional view according to the solid state image pickup device of the embodiment of the invention 8;
Figure 25 A and 25B are that expression light enters the reflection path explanatory view of the waveguide of solid state image pickup device shown in Figure 24;
Figure 26 A～26F is a sectional view of making the method for solid state image pickup device shown in Figure 24 according to the embodiment of the invention 9;
Figure 27 is the side cross-sectional view of the example of the conventional waveguiding structure of expression.
Embodiment
Below solid state image pickup device of the present invention and manufacture method thereof will be described with reference to the accompanying drawings.
Fig. 1 is the side cross-sectional view of expression according to the topology example of solid state image pickup device of the present invention.Shown in the example of Fig. 1, in having the solid state image pickup device of waveguiding structure, dielectric film 5 is set in the surface region on the substrate that disposes light receiving part 1, between its they gate insulating film 2 is arranged, element secluding film 3 and SiN backstop film (etch stop film) 4, light receiving part 1 plays the function of photodiode.
Dielectric film 5 comprises multilayer.Dielectric film 5 can comprise multiple different material.In the middle of the multilayer of dielectric film 5, by under layer by cover from light receiving part 1 read signal charge required read the function that grid 6 have the graduation upper surface.That is, should by under layer be the graduation film.In addition, holding wire 7 is arranged on the graduation film in the multilayer mode.Holding wire 7 is arranged on the periphery of light receiving part 1 and in the position that is suspended from the light receiving part 1.The conductor plug 8 that links to each other with holding wire 7 also is arranged in the dielectric film 5.Fig. 1 only shows a line, is illustrated in the dielectric film 5 to comprise multilayer.Though between each layer, there is other interface, save these interfaces in the accompanying drawings, because they are not required to describing the present invention.
In addition, the position corresponding to light receiving part 1 in dielectric film 5 is provided with waveguide 9, and waveguide 9 is the steric direction light receiving part 1 of incident light between multilayer signal line 7.Lens 13 are arranged on the dielectric film 5 on the chip, and passivating film 10, graduation film 11 and chromatic filter 12 are arranged between them.
For example, thereby to light receiving part 1, and the light transmitting material that embeds in opening such as silicon nitride (P-SiN) by plasma CVD (chemical vapour deposition (CVD)) technology forms waveguide 9 by form opening (hole) in dielectric film 5 from the spatial extension of light incident side between multilayer signal line 7.When the refractive index of light transmitting material is higher than dielectric film 5, waveguide 9 not only optics links light receiving part 1 lens 13 to the chip, but also the light that improves light receiving part 1 by the total reflection incident light compiles rate, and wherein the incident light of total reflection has a incidence angle greater than critical angle at the interface between waveguide 9 and dielectric film 5.
Because said structure, incident light can be by direct light receiving unit 1 expeditiously, even many signal line 7 asymmetricly are arranged on about light receiving part 1 on the periphery of light receiving part 1 and in the position that hangs on the light receiving part 1, also are like this.
Below will based on accompanying drawing describe according to solid state image pickup device of the present invention and manufacture method.
＜embodiment 1 〉
At first, description is according to the overall structure of solid state image pickup device of the present invention.Fig. 2 is the interface side view according to the topology example of the solid state image pickup device of first embodiment of the invention (below be called " embodiment 1 ").In Fig. 2, represent and conventional solid state image pickup device (referring to Figure 27) components identical with identical label.
As shown in Figure 2, in the solid state image pickup device in the present embodiment, dielectric film 5 is set on the substrate that disposes light receiving part 1, gate insulating film 2 is arranged between them, element secluding film 3 and SiN backstop film (etch stop film) 4, light receiving part 1 plays the effect of photodiode effect.Embedded in the dielectric film 5 from light receiving part 1 read signal charge required read grid 6, multilayer signal line 7 and the conductor plug 8 that links to each other with holding wire 7.In addition, the waveguide of being made up of light transmitting material 20 is arranged in the dielectric film 5 position corresponding to light receiving part 1.Lens 13 are arranged on the upper surface of dielectric film 5 on the chip, and passivating film 10, graduation film 11 and chromatic filter 12 are arranged between them.Waveguide 20 is made up of the light transmitting material that refractive index is higher than dielectric film 5.
In above-mentioned solid state image pickup device, the shape of waveguide 20 is different from the shape (referring to Figure 27) of waveguide in the conventional solid state image pickup device.That is, waveguiding structure is different from conventional situation.In the waveguiding structure according to present embodiment, waveguide has the forward direction wedge-like portion." forward direction wedge-like portion " this statement is meant the part with wedge-type shape, and wherein the size of seeing the plane shape from the incident light direction reduces to light receiving part 1 gradually from the light entrance face of dielectric film 5.
The forward direction wedge-like portion can be extended perforation waveguide 20, example as shown in Figure 2.But, be not always to need to form the forward direction wedge-like portion that connects waveguide 20, the forward direction wedge-like portion must be formed in the part of waveguide 20 at least, thereby extends to light receiving part 1 from the light incident surface of dielectric film 5.More particularly, the forward direction wedge-like portion can only be arranged on light incident one deck of holding wire 7, mainly be suspended in the multilayer signal line 7 on the light receiving part 1 (referring to the label A among Fig. 2), promptly only extend to the degree of depth of arriving signal line 7, and other parts can form with rectilinear form but not wedge-type shape from the light entrance face of dielectric film 5.
In addition, desirable situation is that the forward direction wedge-like portion has corresponding to the flat shape that is formed on the holding wire 7 in the dielectric film 5, specifically, have corresponding to the holding wire 7 that is suspended on the light receiving part 1, but not the flat shape of light receiving part 1.
The concrete example of flat shape of the forward direction wedge-like portion of waveguide 20 is described below.Fig. 3～5th, the concrete example explanatory view of the flat shape of expression forward direction wedge-like portion.
The flat shape of research light receiving part 1 is the example of rectangle shown in Fig. 3 below.In the case, the flat shape of waveguide 20 can be arranged to the rectangle corresponding to light receiving part 1.But if there is the holding wire 7 that is suspended on the light receiving part 1, then incident light is stopped by holding wire 7, and the surface (sensitive surface) that light arrives is reduced a certain amount of.
For the above reasons, when in waveguide 20, the forward direction wedge-like portion being set, as shown in Figure 4, even the opening shape of forward direction wedge-like portion light incident side is a rectangle, the shape of the opening 20b on light receiving part 1 one sides also can be arranged to corresponding to the flat shape that is suspended in the holding wire 7 on the light receiving part 1.In this way, the light that enters from opening 20a can accumulate on the opening 20b, consequently, allows incident light to arrive light receiving part 1 efficiently.
And the forward direction wedge-like portion differs and is decided to be the wedge shape that a cone angle is arranged, and for example, can be the wedge that two or more different cone angle are arranged.In the case, for example, as shown in Figure 5, the forward direction wedge-like portion on light receiving part 1 side forms as shown in Figure 4, and the forward direction wedge-like portion of light incident side forms the shape of the opening 20c that makes on light incident side greater than opening 20a.In this way, even the opening 20a of the forward direction wedge-like portion on light receiving part 1 one sides is very narrow, by the opening 20c of expansion light incident side forward direction wedge-like portion, also can be a large amount of photoconductions to light receiving part 1.
Fig. 6 and 7 is the side cross-sectional view according to other topology example of solid state image pickup device of the present invention, and wherein the forward direction wedge-like portion is the combination with wedge shape of two or more different cone angle.In the accompanying drawings, represent and above-mentioned solid state image pickup device (referring to Fig. 2) components identical with identical label.
As shown in Figure 6, the waveguide 20 of solid state image pickup device can be designed to have first gradient 20d, and the size that this gradient 20d is inclined to the flat shape that makes waveguide 20 reduces (referring to the label A Fig. 6) from light inlet side to holding wire 71 1 sides.Except that first gradient 20d, waveguide 20 has second gradient 20e, and this gradient 20e is to be different from the angle tilt of first gradient 20d.But, replacing second gradient 20e, waveguide 20 can not have the non-sloping portion (not shown) that fully.
First gradient 20d of waveguide 20 has the angle of inclination that conforms to at least two signal line 7a that overlap each other and the relation of the position between the 7b on the stacked direction (vertical direction).That is, stipulate the angle of inclination according to the end position of upper and lower holding wire 7a and 7b.For example, example as shown in Figure 6, in the following end of holding wire 7a is suspended in situation on the light receiving part 1 significantly, the end of last holding wire 7b is not suspended on the light receiving part 1, thereby between the end position of each holding wire, producing two dimensional differences, the angle of inclination of first gradient 20d is bigger with respect to the optical axis of incident light.
In addition, the angle of inclination of first gradient 20d needn't corresponding between the end of holding wire 7a and 7b in the angle of light receiving part 1 one sides, and must set according to the relation of the position between holding wire 7a and the 7b.
Even in the waveguide 20 with forward direction wedge-like portion, first gradient 20a and second gradient 20b (or non-sloping portion) make up as described above, by enlarging the opening of light incident side, and also can be a large amount of photoconductions to light receiving part 1.That is, in the waveguiding structure of routine (referring to figure A) because the amount of the light that is compiled reduces, thus can not be near light receiving part 1 signalization line 7.But if adopt the waveguiding structure of the waveguide 20 that includes first gradient 20d, the light that then can improve light receiving part 1 compiles efficient.Therefore, in imaging device, such as MOS (metal-oxide semiconductor (MOS)) imaging device (being cmos sensor etc.), holding wire 7 can be arranged on light receiving part 1 near.In addition, can overcome the lead that the area by the increase of light receiving part 1 area and image element circuit reduces to be caused limited problem is set.Particularly this phenomenon becomes particularly remarkable when the end of holding wire 7a is suspended on the light receiving part 1 significantly.
Again as shown in Figure 7, the waveguide 20 of solid state image pickup device can be designed so that its sidewall comprises the first side 20f and the second side 20g, and the flat shape of waveguide 20 reduces gradually by the first side 20f and the second side 20g.In the case, the first side 20f has the shape that is different from the second side 20g.At least the first side 20f has different gradient 20h in a plurality of angles of inclination and 20i.Gradient 20h and 20i can construct as first gradient 20d and second gradient 20e (or non-sloping portion).Promptly, at least one gradient 20h among gradient 20h and the 20i has the angle of inclination that conforms to at least two holding wire 7a that overlap each other and the relation of the position between the 7b on the stacked direction (vertical direction), and following holding wire 7a is arranged to its end and is suspended in significantly on the light receiving part 1.
Even in the waveguide 20 with forward direction wedge-like portion that the wherein first side 20f and the second side 20g make up as mentioned above, by enlarging the opening of light incident side, also can be with a large amount of photoconductions to light receiving part 1.That is, in the waveguiding structure of routine because compile light amount reduce, so cannot be near light receiving part 1 signalization line 7.But if adopt the waveguiding structure of the waveguide 20 that includes the first side 20f, the light that then can improve light receiving part 1 compiles efficient.In addition, can overcome because the lead that the area of light receiving part 1 increases and the area of image element circuit reduces to cause is provided with limited problem.Particularly when the end of holding wire 7a is suspended on the light receiving part 1 significantly.This phenomenon has become obviously.
The method of making the waveguide with said structure will be described below, i.e. the general introduction of the method for solid state image pickup device constructed in accordance.Fig. 8～12nd, the side cross-sectional view of the method for diagram solid state image pickup device constructed in accordance.This method of sentencing the solid state image pickup device shown in the shop drawings 2 is that example is described.
In order to make solid state image pickup device, at first, as shown in Figure 8, form light receiving part 1 and read grid 6, form SiN backstop film 4 then on light receiving part 1, gate insulating film 2 is arranged between them, SiN backstop film 4 is as the etch stop film in to the etching process of waveguide openings.Consider that to the selection rate in the etching process of waveguide openings SiN backstop film 4 utilizes SiN to form.Subsequently, on gate insulating film 2, form multilayer signal line 7, the conductor plug 8 that links to each other with holding wire 7 and the dielectric film 5 that is used to embed these elements.As dielectric film 5, can adopt oxide-film.So far in the stage, the fabrication schedule solid state image pickup device with routine basically is identical.
Subsequently, as shown in Figure 9, on the upper surface of dielectric film 5, carry out the patterning of photoresist film 21, to form the opening of waveguide 20.In this process,, form photoresist film 21 and make the opening that obtains by patterning have the forward direction wedge-type shape in order to produce waveguide 20 with forward direction wedge-like portion.The forward direction wedge-type shape can be by being generally used for forming the known technology generation of photoresist film 21.In addition, can be according to angle of the shape regulation forward direction wedge-like portion of the forward direction wedge-like portion that will form etc.
Form after the photoresist film 21, as shown in figure 10, form opening 22 by etching.Thus, the position (above light receiving part 1) corresponding to light receiving part 1 forms opening 22 in dielectric film 5.Because photoresist film 21 has the forward direction wedge-type shape, so when forming opening 22 by etching, the forward direction wedge-type shape of photoresist film 21 is transferred to opening 22.Therefore, the opening 22 that forms by etching has the forward direction wedge-like portion, sees that from the incident light direction size of plane shape reduces to light receiving part 1 from light entrance face in this part.
When forming opening 22 by etching, the condition in the etching process can be set, make the forward direction wedge-type shape form by suppressing isotropic etching.Specifically, in etching process, for example utilize to have higher deposition capability with the basic gas of the CF that suppresses isotropic etching, as C 4F 8Form the sidewall diaphragm, make the opening 22 of gained have the forward direction wedge shape.Except that the gas type that is adopted, by suitable selection and regulate the conditions of exposure of resist, flow velocity and pressure, the RF bias voltage etc. of etching gas, can suppress isotropic etching, thereby produce wedge-type shape.That is, by regulating the etching condition in the etching process, the opening 22 that forms by etching has the forward direction wedge-like portion.
As mentioned above, in dielectric film 5, form the opening 22 of waveguide 20, thereby by in the process of photoresist patterning, forming forward direction wedge shape resist layer, so that form the forward direction wedge-type shape by the isotropic etching that suppresses in the etching process, or the combination by these steps etc. has the forward direction wedge-like portion by etching condition is set.The angle of forward direction wedge-like portion, the degree of depth etc. can be provided with as required by regulating resist shape, etching condition etc.Because the shape of resist and etching condition etc. can utilize known technology to regulate, so will save its detailed description at this.
Form after the opening 22, as shown in figure 11, in opening 22, embed light transmitting material to form waveguide 20.Specifically, for example, form waveguide 20 such as P-SiN by utilizing high-density plasma CVD to embed light transmitting material.In this stage, opening 22 has the forward direction wedge-like portion.That is, because the forward direction wedge-like portion, the front end of opening 22 (top) is bigger.Therefore, when embedding light transmitting material, the supply of group in opening 22 quickened, and thereby light transmitting material be evenly distributed in the opening 22.And even when embedding light transmitting material near the front end of deposit attached to opening 22, front end can not be deposited thing yet to be stopped, because front end is bigger.Because above-mentioned reason in the opening 22 with front end wedge-like portion, even aspect ratio is very big, also can embed light transmitting material satisfactorily.After embedding light transmitting material formation waveguide 20 in opening 22, carry out whole graduation by etch back process or CMP (chemico-mechanical polishing) and handle.
Subsequently, as shown in figure 12, forming lens 13 on passivating film 10, graduation film 11, chromatic filter 12 and the chip on waveguide 20 and the dielectric film 5 successively by identical with making conventional solid state image pickup device basically process.Finish solid state image pickup device thus.
As mentioned above, in solid state image pickup device and manufacture method thereof according to present embodiment, waveguide 20 has the forward direction wedge-like portion.That is, the opening that waveguide 20 is formed has the forward direction wedge-like portion, reduces to light receiving part from light incident surface in the size of this part midplane shape.Therefore, when by embedding light transmitting material when forming waveguide 20 in opening 22, the character that embeds light transmitting material increases than routine techniques.In addition, the front end of opening 22 is not deposited thing and stops.Thereby light transmitting material can evenly embed in the opening 22 with high aspect ratio satisfactorily.As a result, in waveguide 20, can improve light and compile efficient, and can reduce the change of characteristic.
In addition, because can increase by incident light one side of forward direction wedge-like portion waveguide 20, light receiving part 1 one sides of waveguide 20 can reduce, so can form the waveguide with the shape that is suitable for most the solid-state imaging device interposed structure, improve the ability of compiling of light thus.That is, the very little increase of the light incident square chi of waveguide 20 can increase the light quantity that enters waveguide 20.Waveguide 20 light receiving part 1 side size reduce can absorb the light that enters waveguide 20 effectively, and for example in an inclined direction the emission light also be easy to be focused on the light receiving part 1.Thereby light is improved to the ability that light receiving part 1 compiles.
In addition, for example, even the flat shape of light receiving part 1 is owing to the increase of pixel quantity reduces, perhaps for example, when adopting holding wire 7 grades wherein to cover the structure in the space of light receiving part more than 1, the front end of opening 22 can increase by the forward direction wedge-like portion, avoids interference holding wire 7 etc. simultaneously.Promptly, because the distance between waveguide 20 and the holding wire 7 can increase by the forward direction wedge-like portion, be scratched during etching openings 22 so can prevent circuit, thereby can improve the reliability of solid state image pickup device, and can prevent owing to the product with holding wire 7 produces particle.
These features are especially very effective in having the solid state image pickup device of Miltilayer wiring structure, because increase for the increase along with the wiring number of plies and pixel quantity of the aspect ratio of the opening 22 that forms waveguide 20.
In addition, described in present embodiment, for example under the forward direction wedge-like portion only was arranged on situation on the light inlet side of the holding wire 7 that is suspended in significantly on the light receiving part 1, the forward direction wedge-like portion only was arranged on the necessary part.That is, other parts can have straight shape but not wedge-type shape, and this compiles aspect the efficient very suitable at the light that improves light receiving part 1.
In addition, described in present embodiment, under the forward direction wedge-like portion has situation corresponding to the flat shape that is formed on the holding wire 7 in the dielectric film 5, particularly, holding wire 7 is suspended under the situation on the light receiving part 1, because incident light is not stopped by holding wire 7, so the permission incident light arrives light receiving part 1 efficiently, so very be suitable for improving the efficient of compiling of light.In addition, during etching openings 22, be scratched, so improved the reliability of solid state image pickup device widely because can prevent circuit.
In addition, making according to present embodiment in the method for solid state image pickup device, by during the photoresist patterning, forming forward direction wedge shape resist layer, by etching condition is set so that by suppressing in the etching process isotropic etching forming the forward direction wedge-like portion, or prepare the forward direction wedge-like portion by the combination of these steps.Even when forming the forward direction wedge-like portion, also do not need to increase any special step etc., and can carry out formation at an easy rate therefore, to it.
In addition, forming under the situation of forward direction wedge-like portion, can during etching, change etching condition by regulating etching condition.Therefore, even work as the only partly setting of forward direction wedge-like portion, maybe when combination has the shape of two or more different cone angle, can only make this structure at an easy rate by an etching process.
In addition, solid state image pickup device described in the present embodiment and manufacture method thereof can be applied to the solid state image pickup device with waveguiding structure, the type of no matter installing how, no matter is CCD (charge coupled device) type or CMOS (complementary metal oxide semiconductors (CMOS)) type for example.
In this embodiment, with reference to preferred exemplary the present invention has been described.But should be appreciated that, the invention is not restricted to this embodiment.Specifically, the flat shape of described light receiving part 1, waveguide 20, Miltilayer wiring structure etc. are a kind of concrete example.
＜embodiment 2 〉
Next, the method for making solid state image pickup device according to second embodiment of the invention (below be called " embodiment 2 ") will be described.Figure 13 A～13K is a side cross-sectional view of making the method for solid state image pickup device according to the embodiment of the invention 2.For convenience of description, do not illustrate in the accompanying drawing and be arranged on as structures such as the isolated districts of the element region on the silicon substrate of substrate, element.
In embodiment 2, as shown in FIG. 13A, silicon substrate 111 is provided with the diode 112 of carrying out opto-electronic conversion, SiN film 113, film 114 between multilayer, first holding wire 116, the interlayer film 115 that is used for first holding wire, nonproliferation film 121 by copper (Cu) formation that is applied to first wiring, interlayer film 122 between first holding wire and secondary signal line, secondary signal line 123, by being applied to the nonproliferation film 131 that second Cu that connects up constitutes, interlayer film 132 between secondary signal line and the 3rd holding wire, the 3rd holding wire 133, by the nonproliferation film 141 that constitutes of Cu that is applied to the 3rd wiring, and in the 3rd wiring and interlayer film 142 between the holding wire on it is set.At first, shown in Figure 13 B,, carry out patterning to the resist layer 151 that is used as mask in order to form part by photoetching as waveguide.In this example, all interlayer films are by SiO 2Constitute.Film 114 has the thickness of 450nm between multilayer, the interlayer film 115 that is used for first holding wire has the thickness of 150nm, each has the thickness of 200nm respectively at the interlayer film 122 between first holding wire and the secondary signal line and the interlayer film between secondary signal line and the 3rd holding wire 132, and the interlayer film 142 in the 3rd wiring has the thickness of 300nm.Holding wire 116,123 and 133 constitutes by Cu, and the thickness of each is 200nm.Cu nonproliferation film 121 and 141 constitutes by SiC, and the thickness of each is 50nm.The SiN film 113 of bottom has the thickness of 50nm.
After to resist layer 151 patternings, shown in Figure 13 C, the interlayer film 142 on the last wiring layer is isotropically handled.In addition, shown in Figure 13 D, the interlayer film in being used to form the zone of waveguide is by the anisotropic etch processes, to form waveguide 152.
After forming waveguide 152, shown in Figure 13 E, remove employed resist layer 151 in the photoetching.Subsequently, shown in Figure 13 F, the thick metal film that is used to form the waveguide outer tube 153 of deposition 50nm, and then, shown in Figure 13 G,, make 153 of metal films that are used to form outer tube be retained on the side by the whole surface of etch-back metal film 153.In this example, make metal film 153 with aluminum.But, also can adopt cladding structure, wherein low refractive index film is used as sidewall, the inboard high refractive index film that embeds.
Subsequently, shown in Figure 13 H, by high-density plasma CVD embed insulating film 154 in waveguide 152.Dielectric film 154 is hyaline membranes of a kind of visible light transmissive.Specifically, adopt common SiO in this example 2Film.
After embed insulating film 154, shown in Figure 13 I, carry out graduation by CMP and be formed on dielectric film 154 in the zone except that waveguide with removal.
Wherein utilize high-density plasma CVD in waveguide 152, to embed the example of transparent insulating film 154 though more than described, also can embed transparent insulating film 154, for example adopt cladding process by other method.In the case, if realize graduation simultaneously, then can eliminate the graduation process of utilizing CMP by cladding process.
The method of making solid state image pickup device among the embodiment 2 has more than been described.In subsequent step, can form lens on the chip, so that allow the light of q.s to enter waveguide 152.That is, shown in Figure 13 J, can form SiN film 161 on the transparent insulating film 154 of graduation, lens 163 on chromatic filter 162 and the chip.
In above-mentioned example, embed transparent insulating film 154 by high-density plasma CVD, and carry out graduation by CMP then.But, shown in Figure 13 K, do not carry out graduation by CMP, be higher than the material of the dielectric film 154 of embedding by refractive index, for example the film 155 formed of SiN also can be formed thereon, subsequently, can pass through etch back process or CMP graduation film 155, make 155 of films be retained on the waveguide,, thereby allow light in waveguide, to assemble fully with the formation concavees lens.
In addition, in embodiment 2, directly formed metal film 153 examples after the opening, also can after forming dielectric film, be formed the metal film 153 that for example 50nm is thick though be used to form the part of waveguide in the example.In the case, be easy to guarantee dielectric strength between waveguide and the holding wire.
＜embodiment 3 〉
Next, method according to the manufacturing solid state image pickup device of third embodiment of the invention (hereinafter to be referred as " embodiment 3 ") will be described.Figure 14 A～14K is a side cross-sectional view of making the method for solid state image pickup device according to the embodiment of the invention 3.Herein, for convenience of description, the not shown structure that is arranged on as the element region on the silicon substrate of substrate, the isolated district of element etc. in the accompanying drawing.
In embodiment 3, silicon substrate 211 is provided with the diode 212 of carrying out opto-electronic conversion, SiN film 213, film 214 between multilayer, first holding wire 216, interlayer film 215 between first holding wire, nonproliferation film 221 by copper (Cu) formation that is applied to first wiring, interlayer film 222 between first holding wire and secondary signal line, secondary signal line 223, by being applied to the nonproliferation film 231 that second Cu that connects up constitutes, interlayer film 232 between secondary signal line and the 3rd holding wire, the 3rd holding wire 233, by the nonproliferation film 241 that constitutes of Cu that is applied to the 3rd wiring, and in the 3rd wiring and interlayer film 242 between the holding wire on it is set.At first, shown in Figure 14 A,, carry out patterning to the resist layer 251 that is used as mask in order to form part by photoetching as waveguide.Identical among the structure of interlayer film and wiring and the embodiment 2.
After to resist layer 251 patternings, as shown in Figure 14B, the interlayer film 242 in the processing on the wiring layer.Specifically, form opening in the interlayer film 242 on last wiring layer, thereby have the size that partially or completely covers holding wire 216,223 and 233.
Form after the opening, shown in Figure 14 C, form dielectric film 243, and shown in Figure 14 D, dielectric film 243 is carried out RIE (reactive ion etching), so that 243 sides that are retained in opening of dielectric film.In this example, as dielectric film 243, deposit thickness is the SiN film of 200nm.
Subsequently, shown in Figure 14 E, form waveguide by photoetching and RIE, thereby have the distance of guaranteeing to have enough dielectric strengths from holding wire 216,223 and 233.In Figure 14 E, label 252 is represented resist.
Form after the waveguide, shown in Figure 14 F, peel off resist 252, then, deposition 5nm thick such as the metal film 253 of aluminium to be used to form the waveguide outer tube.Subsequently, shown in Figure 14 G,, make 253 of metal films that are used to form the waveguide outer tube be retained in the side by the whole surface of etch-back metal film 253.Also can not adopt the aluminium film as metal film 253, and adopt cladding structure, wherein low refractive index film is used as sidewall, the inboard high refractive index film that embeds.
Subsequently, shown in Figure 14 H, by high-density plasma CVD embed insulating film 254 in waveguide.Dielectric film 254 is hyaline membranes of a kind of visible light transmissive.Specifically, adopt common SiO in this example 2Film.
After embed insulating film 254, shown in Figure 14 I, carry out graduation by CMP and be formed on dielectric film 254 in the zone except that waveguide with removal.
Utilize high-density plasma CVD in waveguide, to embed the example of transparent insulating film 254 though more than described, also can embed transparent insulating film 254, for example adopt cladding process by other method.In the case, if realize graduation simultaneously, then can eliminate the graduation process of utilizing CMP by cladding process.
The method of making solid state image pickup device among the embodiment 3 has more than been described.In subsequent step, can form lens on the chip, so that allow the light of q.s to enter waveguide.That is, shown in Figure 14 J, lens 263 on SiN film 261, chromatic filter 262 and the chip can formed on the transparent insulating film 254 of graduation.
In above-mentioned example, embed transparent insulating film 254 by high-density plasma CVD method, and carry out graduation by CMP then.But, shown in Figure 14 K, do not carry out the CMP graduation, be higher than the material of embed insulating film 254 by refractive index, for example the film 255 formed of SiN also can be formed thereon, subsequently, can pass through etch back process or CMP graduation film 255, make 255 of films be retained on the waveguide,, thereby allow light in waveguide, to be assembled fully with the formation concavees lens.
In addition, in embodiment 3,, also can after forming dielectric film, form the metal film 253 that for example 50nm is thick though described the example that after the part that is used for waveguide is by opening, directly forms metal film.In the case, be easy to guarantee dielectric strength between waveguide and the holding wire.
＜embodiment 4 〉
Next, will describe according to the present invention the 4th and execute the method that example (hereinafter to be referred as " embodiment 4 ") is made solid state image pickup device.Figure 15 A～15K is a side cross-sectional view of making the method for solid state image pickup device according to the embodiment of the invention 4.Herein, for convenience of description, the not shown structure that is arranged on as the element region on the silicon substrate of substrate, the isolated district of element etc. in the accompanying drawing.
In embodiment 4, shown in Figure 15 A, at first, on the silicon substrate 311 of diode 312 that is provided with the execution opto-electronic conversion and SiN film 313, in position, carry out the patterning of resist layer 313a by photoetching corresponding to the zone that will be formed on the convergent lens on the diode 312.Then by heat treatment sphering resist layer 313a, shown in Figure 15 B.Subsequently, by with identical rate of etch treatment S iN film 313 and resist layer 313a, on diode 312, form convergent lens, shown in Figure 15 C.
After forming convergent lens, form SiN film 313 as the interlayer film below wiring, formation contacts with diffusion layer and gate electrode (not shown), and be formed for the interlayer film 315 of first holding wire, first holding wire 316, by being applied to the nonproliferation film 321 that first Cu that connects up constitutes, interlayer film 322 between first holding wire and secondary signal line, secondary signal line 323, by being applied to the nonproliferation film 331 that second Cu that connects up constitutes, interlayer film 332 between secondary signal line and the 3rd holding wire, the 3rd holding wire 333, by the nonproliferation film 341 that constitutes of Cu that is applied to the 3rd wiring, and the interlayer film 342 between the 3rd wiring and holding wire disposed thereon.Obtain the structure shown in Figure 15 D thus.The structure of wiring and interlayer film is identical with embodiment's 2.
Shown in Figure 15 E,, on said structure, carry out patterning to the resist layer that is used as mask in order to form part by photoetching as waveguide.Subsequently, utilize resist layer 351, the interlayer film on the last wiring layer 342 is carried out isotropism handle.Interlayer film 342 for example has the thickness of 300nm.
In addition, shown in Figure 15 F, by the interlayer film of anisotropic etching processing in the zone that will form waveguide, to form waveguide.
Form after the waveguide, shown in Figure 15 G, remove employed resist layer 351 in the photoetching, and form the aluminium film that thickness is 50n then, as the metal film 353 that is used to form the waveguide outer tube.Subsequently, shown in Figure 15 H,, make 353 of metal films that are used to form the waveguide outer tube be retained in the side by the whole surface of etch-back metal film 353.As metal film 353, adopt aluminium in the present embodiment.Can not adopt the aluminium film as metal film 353, and adopt cladding structure, wherein low refractive index film is as sidewall, and inside embeds high refractive index film.
Subsequently, shown in Figure 15 I, by high-density plasma CVD embed insulating film 354 in waveguide.Dielectric film 354 is hyaline membranes of a kind of visible light transmissive.Specifically, adopt common SiO in this example 2
After embed insulating film 354, shown in Figure 15 J, carry out graduation by CMP and be formed on dielectric film 354 in the zone beyond the waveguide with removal.
Though more than described the example that in waveguide, embeds transparent insulating film 354 with high-density plasma CVD, also can embed transparent insulating film 354 by other method, for example adopt cladding process.In the case, if realize graduation simultaneously, then can eliminate the graduation process of utilizing CMP by cladding process.
The method of making solid state image pickup device among the embodiment 4 has below been described.In subsequent step, can form lens on the chip so that there is the light of q.s to enter waveguide.That is, shown in Figure 15 K, lens 363 on SiN film 361, chromatic filter 362 and the chip can formed on the transparent insulating film 354 of graduation.
In addition, though it is not shown, but it is the same with embodiment 2 and 3, the dielectric film that does not utilize the CMP graduation to embed by high-density plasma CVD, also can form thereon by refractive index and be higher than the film that the material of the dielectric film 354 of embedding is formed, and subsequently, this film only is retained on the waveguide, forms the concavees lens that to be combined thus.
In addition, in embodiment 4, though described the example that directly forms metal film 353 after the part that is used to form waveguide is by opening, also can for example forming after forming dielectric film, thickness be the metal film 253 of 50nm.In the case, be easy to guarantee dielectric strength between waveguide and the holding wire.
＜embodiment 5 〉
Next, manufacture method according to the solid state image pickup device of the 5th embodiment (below be called " embodiment 5 ") will be described.Figure 16 A～16K is a side cross-sectional view of making the method for solid state image pickup device according to the embodiment of the invention 5.Herein, for convenience of description, the not shown structure that is arranged on as the element region on the silicon substrate of substrate, the isolated district of element etc. in the accompanying drawing.
In embodiment 4, the topology example that convergent lens directly is set has been described on diode 312.Shown in Figure 16 A, convergent lens 454 can be provided with away from diode 412.In the case, can prevent that diode 412 is subjected to handling the influence of the damage that is caused during the convergent lens 454.In the case, ideal situation is that convergent lens 454 has the structure that has wherein made up convex lens and concavees lens, and this compares with hemispherical mirror, believes the convergence ability that has improved light.Therefore, a kind of like this method will be described in embodiment 5: comprise convergent lens 454 with the structure that has wherein made up convex lens and concavees lens.
In embodiment 5, at first, shown in Figure 16 B, be provided with element and element separation zone (not shown in the accompanying drawings), be provided with the diode 412 of carrying out opto-electronic conversion, between SiN film 413, multilayer on the silicon substrate 411 of film 414, carry out the patterning of resist layer 414a by photoetching, thereby corresponding to the lens area that is formed on the diode 412.Subsequently, shown in Figure 16 C, use resist layer 414a, handle isotropically that film 414 forms concavees lens between multilayer.Shown in Figure 16 D, the resist layer 414a that is used to form concavees lens is stripped from then, and shown in Figure 16 E, also forms SiN film 414b thereon.Be not defined as the SiN film though be used to form the material of lens, this material must have the refraction coefficient that is higher than film 414 between multilayer.Film is by SiO in the present embodiment between this multilayer 2Constitute.
After forming SiN film 414b, shown in Figure 16 F, by CMP to SiN film 414b planarization.Then, shown in Figure 16 G, by photoetching corresponding to the position in the zone that will form convergent lens patterning to resist layer 414c.Then by heat treatment sphering resist layer 414c, shown in Figure 16 H.Subsequently, by with identical rate of etch treatment S iN film 414b and resist layer 414c, on diode 412, form convergent lens 414b, shown in Figure 16 I.
Subsequently, shown in Figure 16 J, be formed for the interlayer film 415 of first holding wire.Owing to form the projection that lens produce, obtain to form first holding wire state before by the CMP graduation.Then, form the step and the step that forms the waveguide described in embodiment 2 or 3 of Cu circuit, produce the solid state image pickup device shown in Figure 16 A by using dual damascene process.
According to aforesaid embodiment 2 to 5,, and allow the light of q.s to enter light receiving part because the restriction to zone that waveguide is set that the signal line Butut is caused can be minimized.And, be arranged between waveguide and the light receiving part by assembling lens, can prevent that the light of lateral reflection under waveguide from leaking in the adjacent pixels.Therefore, can provide more high sensitive solid state image pickup device.
Though the above example that three layer signal lines have been described in embodiment 2-5, the present invention is not limited to three-layer routing.And, though illustrated that in embodiment 2-5 with the inclination of copper as wiring, the present invention is not limited to the Cu wiring certainly.
＜embodiment 6 〉
Next, manufacture method according to the solid state image pickup device of the 6th embodiment (below be called " embodiment 6 ") will be described.
Figure 17 shows the general structure of using solid state image pickup device of the present invention (cmos sensor).
In the example of Figure 17, show cross section corresponding to a pixel of solid state image pickup device.
In the solid state image pickup device 501 according to present embodiment, the light receiving part 504 that receives incident light is arranged in the presumptive area in the Semiconductor substrate 502, and this presumptive area is isolated by element separation zone 503.In the presumptive area on light receiving part 504, in dielectric film 508, be provided be connected to the following holding wire that will illustrate read grid 506 and conductor plug 507, gate insulating film 505 is arranged between them.
In the example of Figure 17, holding wire 509 forms (first holding wire 591 and secondary signal line 592) in two-layer mode, and holding wire 591 links to each other with conductor plug 507 with 592.On the holding wire in top layer, chromatic filter 512 is arranged on the dielectric film 508, and passivating film 510 and graduation film 511 are arranged betwixt, and lens 513 are arranged on the chromatic filter 512 position corresponding to light receiving part 504 on the chip.
Hole 514 extends to the bottom of passivating film 510 from light receiving part 504, thereby is connecting between the lens 513 on light receiving part 504 and the chip.High refractive index layer (for example, the plasma SiN film that is formed by high-density plasma CVD) 515 has the refractive index (n=2.0) higher than dielectric film 508, and it is embedded in the hole 514.Label 16 representatives are to dielectric film (for example, SiO 2Film) the 8 etch stop films (for example, SiN film) with high selectivity.
Made up solid state image pickup device 501 thus with structure of compiling the efficient raising.
In this embodiment, particularly, hole 514 comprises multilayer.
In this embodiment, for example, hole 514 for example comprises two-layer 514A and 514B.The upper surface of layer 514A is for example concordant with the graduation upper surface of the dielectric film 508 that is illustrated by the broken lines.The upper surface of layer 514B is for example concordant with the graduation upper surface of dielectric film 508 under the passivating film.
By using such structure, different with the conventional structure that high refractive index layer 544 embeds in the deep hole that forms hole 543, because hole 514 comprises multilayer 514A and 514B, its each all be embedded with the SiN film 515 of high refractive index layer, be improved so the embedding character of the plasma SiN film 515 in every layer of 514A and 514B is compared with the embedding character of conventional plasma SiN film.Therefore, can avoid producing hole at plasma SiN film 515.
Because hole 514 comprises multilayer 514A and 514B as mentioned above, so for example there is the problem that staggers between the layer.
For example, when the formation second layer, when promptly the Etching mask of layer 514B forms by photoetching, if do not aim at ground floor 514A, shown in the view that amplifies among Figure 18, the joint portion between layer 514A that vertically connects each other on the sidewall and 514B has formed step 521.
When the formation of the joint portion between layer 514A and 514B step 521,514 light that enter (representing with arrow x in the accompanying drawings) advance to dielectric film 508 from the plasma SiN film 515 that is embedded in wherein from the hole.According to incidence angle, light advances in the dielectric film 508 in step 521 refraction (to be represented with arrow y) in the accompanying drawings, perhaps the full emission in step 521 places with advance in hole 514 and from surface scattering to outside (representing with arrow z in the accompanying drawings).Possible is that light is being totally reflected in the hole 514 between hole 514 and upper strata (for example, passivating film 510) at the interface once more.
As mentioned above, owing to formed step 521, incident light has obviously been weakened the ability of compiling of light receiving part 504, causes light to compile efficient and reduces.
Therefore, in the present embodiment, adjacent layer 514A forms different diameters with 514B.That is, as shown in figure 19, upper strata 514B by under diameter Bd less than the 514A of lower floor by last diameter Ad.Therefore, can reduce the reduction that light compiles efficient.
In the case, though step appears at 520 places, joint portion, because joint portion 520 place lower floors are bigger by last diameter, so unnecessary reflection or refraction in the situation as shown in figure 18 can not occur.
Thereby for form upper strata 514B its by under diameter Bd less than the 514A of lower floor by last diameter Ad, the diameter of mask is reduced such amount.The maximum deviation that occurs in the photoetching method is about 0.1 μ m.Therefore, for example in forming the photoetching process of upper strata 514B, control is depended on last diameter Ad0.2 μ m (0.1 * 2) by diameter Bd down less than the 514A of lower floor.
Thus, can prevent that aforesaid step 521 from appearring in 520 places, knot joint portion between layer 514A and 514B.
In the solid state image pickup device 501 of present embodiment, different with conventional structure, high refractive index layer is not embedded in the deep hole.Hole 514 comprises multilayer 514A and 514B, and every layer of embedding is as the SiN film 515 of high refractive index layer.Thereby, the embedding character of the embeddability plasma SiN film in one deck 547 of routine of fine quality of the plasma SiN film 515 among every layer of 514A and the 514B.As a result, can provide a kind of solid state image pickup device, wherein in plasma SiN film 515, not produce hole with gratifying embedding character.
In addition because the interface between layer 514A and the 514B (knot joint portion 520) locate, upper strata 514B by under diameter Bd be provided with to such an extent that depend on last diameter Ad less than the 514A of lower floor, so 520 places unnecessary reflection or refraction can not occur in the joint portion.Thereby, can provide a kind of light to compile the undiminished solid state image pickup device of efficient.
In addition, in order to reduce the interface level in the light receiving part 504, or, for example supply with the hydrogen that is included in the plasma SiN film 515 to light receiving part 504 by annealing in process for by repairing the generation of eliminating hickie unusually in the lattice.In the case, because the plasma SiN film 515 in the hole 514 does not have hole, and have enough big volume, thus can supply with the hydrogen of q.s to light receiving part 504 from plasma SiN film 515, and can show the effect of eliminating the hickie generation satisfactorily.
In addition, when hole occurring in the hole, the covering power of high refractive index layer (coverage rate) can not be satisfactory in the hole, and high refractive index layer is easy to break away from.But in the present embodiment, because in hole 514, do not produce hole, so can improve the coverage rate of SiN film 515 these high refractive index layers in hole 514.
In above-mentioned example, constitute the layer 514A in hole 514 and at least one among the 514B and can have the structure that sidewall is a wedge-type shape.
For example, as shown in figure 20, in above-mentioned example, when the sidewall of the layer 514B that is formed on the top is wedge-type shape, for example compare with the structure shown in Figure 17, light can more easily enter in the hole 514.And the embedding character of plasma SiN film in layer 514B is further enhanced.
In above-mentioned example, hole 514 comprises two-layer 514A and 514B.As another example, hole 514 comprises that the structure of three layers of 514A, 514B and 514C is illustrated among Figure 21.
In this example, the upper surface of cambium layer 514A, 514B and 514C is concordant with the upper surface of the upper surface of the upper surface of the graduation dielectric film 508 that is illustrated by the broken lines with first holding wire, 591 belows respectively, graduation dielectric film 508 that secondary signal line 592 belows are illustrated by the broken lines and the graduation dielectric film 508 of passivating film below 510.That is, the upper surface of layer 514A, 514B and 514C forms concordantly with the upper surface of their mutually deserved graduation dielectric films 508.
Other parts are identical with structure shown in Figure 17.Represent and components identical shown in Figure 17 with identical label, save description of them at this.
In such structure, each has the degree of depth of minimizing layer 514B and 514C, is improved in the embedding character of layer 514B and the 514C plasma SiN film 515 in each.Therefore, the embedding character in the hole 514 is compared further raising with structure shown in Figure 17.
In addition, for example as shown in figure 22, each forms sidewall when having the structure of wedge-type shape as layer 514B and 514C, as shown in figure 21, except above-mentioned advantage, can also prevent that lens 513 form on the chip layer 514A, 514B and the diameter (by last diameter) of 514C from reducing gradually.In addition, the embedding character of layer 514B and 514C ionic medium SiN film 515 is enhanced, and the embedding character in the hole 514 is able to further raising.
＜embodiment 7 〉
Next, will example that make the method for solid state image pickup device according to seventh embodiment of the invention (below be called " embodiment 7 ") be described with reference to figure 23A～23J.
In this embodiment, will the manufacture method of solid state image pickup device shown in Figure 17 be described.In example shown in the drawings, show cross section, and represent element same as shown in Figure 17 with identical label corresponding to a pixel of solid state image pickup device.At first, shown in Figure 23 A, form the light receiving part 504 that receives incident light in the presumptive area of in Semiconductor substrate 502, being isolated, and on light receiving part 504, form gate insulating film 505 by the isolated district 503 of element.
Next, shown in Figure 23 B, forming on light receiving part 504 and read grid 506 and etch stop film 516, is gate insulating film 505 between them.
, adopt the SiN film herein as etch stop film 516, with guarantee subsequently when in the dielectric film on etch stop film 516 508 during formation opening 514 to SiO 2The dielectric film 508 that film constitutes has higher etching selection rate.The SiN film for example can utilize low pressure chemical vapor deposition to form.
Next, comprising formation dielectric film 508 on the whole surface of reading the isolated district 503 of grid 506, etch stop film 516 and element, and on dielectric film 508, also forming the resist film (not shown).By known photoetching method resist film is carried out patterning and be used to form the Etching mask of opening 541, and remove dielectric film 508 by anisotropic dry etching again by Etching mask with generation.
Then, by removing Etching mask, shown in Figure 23 C, obtain its split shed 541 and be formed on structure in the dielectric film 508.
Carry out the anisotropic dry etching with parallel-plate etching device, and for example use C 4F 8Gas, Ar gas or O 2Gas is as reacting gas.When adopting these reacting gass, can guarantee high selection rate between dielectric film 508 and the etch stop film 516.
As mentioned above, because can guarantee dielectric film 508 and be formed between the etch stop film 516 on the light receiving part 504 high selection rate is arranged, so when etching arrived etch stop film 516, to the etch-stop of dielectric film 508, thereby light receiving part 504 was surperficial unaffected.In addition, can not change the degree of depth 14Ah that each pixel ground evenly is provided with opening 541.
Because the formation of the holding wire 509 that the formation of opening 541 will be described prior to the back, thus with conventional situation in form and form opening again after all holding wires and compare, can reduce the degree of depth 14Ah of opening 541.That is, form opening 541 with very little aspect ratio.
Subsequently, shown in Figure 23 D, after for example removing the etch stop film 516 that is exposed in the opening 541 by the isotropism dry etching, on the whole surface of the dielectric film 508 that comprises opening 541, form SiN film 515, this film 515 is higher than the high refractive index layer of dielectric film 508 for refractive index, and for example SiN film (plasma SiN film) 15 forms by high-density plasma CVD.
As the isotropic etching of removing etch stop film 516, for example can adopt the chemical drying method etching that utilizes the plasma that flows downward.
As mentioned above, because the degree of depth 14Ah of opening 514 is very little, thus can in opening 541, embed plasma SiN film satisfactorily, and can not produce hole.
Subsequently, shown in Figure 23 E, for example utilize CMP or etch back process, remove plasma SiN film 515 by the surface that etches into dielectric film 508.
In this stage, must carry out by etched removal, make not residual plasma SiN film 515 on dielectric film 508.Reason for this reason is, if plasma SiN film 515 is stayed on the dielectric film 508, then incident light just may repeatedly be reflected eventually and enters in the neighbor at plasma SiN film 515, thereby influences them.
Herein, for example when plasma SiN film 515 was removed by utilizing the CMP etching, the upper surface of dielectric film 508 was not left plasma SiN film 515 by graduation.Thereby needn't for example in the subsequent step that forms holding wire, carry out graduation again.
Produce thus wherein to embed the layer of plasma SiN film 515 514A is arranged.
Subsequently, shown in Figure 23 F, form conductor plug 507 and holding wire 509.
At first, the precalculated position in dielectric film 508 forms conductor plug 507, and forms ground floor holding wire 591 on the dielectric film 508 of graduation.Comprise formation dielectric film 508 on the whole surface of holding wire 591 again, and carrying out graduation.Form conductor plug 507 then in the pre-position, on dielectric film 508, form second layer holding wire 592.Comprising formation dielectric film 508 on the whole surface of holding wire 592 again, and graduation dielectric film 508.Thus, produce double-deck line 509 (first holding wire 591 and secondary signal line 592).
In this embodiment, holding wire 509 has double-decker.For example, when the number of plies of holding wire 509 increases to three layers, four layers, five layers, six layers, seven layers or more for a long time, repeat above-mentioned steps.
Next, on dielectric film 508, form the resist film (not shown), and utilize photoetching resist film to be formed Etching mask with the pattern that is used to form opening.
In this stage, consider the deviation (being 0.2 μ m to the maximum) in the photoetching, be formed for forming the pattern of opening 542, make and to depend on last diameter 514Ad less than the under shed 541 of (referring to Figure 23 C) formation in the step in front by diameter 514B down.
Though have the difference of about 0.2 μ m in the diameter between opening 541 and 542, because this difference is that 0.2 μ m is very little, so can adopt the Etching mask pattern identical with being used to form opening 541.That is, can be only by in photoetching process, controlling the diameter of regulating opening.
Remove dielectric film 508 by anisotropic dry etching then by Etching mask.
Subsequently, remove Etching mask.Thus, shown in Figure 23 G, in dielectric film 508, form opening 542.
In this stage, the plasma SiN film 515 among the 514A of lower floor serves as the etch stop device.Its reason is by utilizing C 4F 8Gas, Ar gas or O 2Gas is as the reacting gas in the anisotropic etching, and is similar with said circumstances, can guarantee higher selection rate between plasma SiN film 515 among the layer 514A and etched dielectric film 508.Do not influence the surface of the plasma SiN film 515 among layer 514A like this.In addition, (520 places, joint portion) at the interface between the opening with upper shed 542 by under diameter be provided with less than under shed 541 by last diameter.Therefore, even between the Etching mask pattern that is used to form opening 542 and under shed 542, do not aim in the photoetching process, upper shed 542 by under diameter 514B also can be outstanding by last diameter 514A under shed 541, thereby prevented that dielectric film 508 is by partly etchings.
In addition, in this step, because layer 514A is formed in the step of front, so also the degree of depth 14Bh of opening 542 can be reduced certain amount.
Next, shown in Figure 23 H, on the whole surface of the dielectric film 508 that comprises opening 542, form the high refractive index layer that refractive index is higher than dielectric film 508.In this step, as the situation shown in Figure 23 D, for example SiN film (plasma SiN film) 515 forms by high-density plasma CVD.In this stage, because the degree of depth of opening 542 is less as mentioned above, so plasma SiN film can embed in the opening 542 satisfactorily.
Subsequently, shown in Figure 23 I, remove plasma SiN film 515 by the surface that utilizes CMP or etch back process to etch into dielectric film 508.The same with said circumstances, carry out graduation, make plasma SiN film 515 not remain on the dielectric film 508.
Herein, for example when utilizing CMP to remove plasma SiN film 515 by etching, the upper surface of dielectric film 508 is not left plasma SiN film 515 by graduation.Thereby, do not need in the subsequent step that forms holding wire, to carry out graduation again.
Produce the layer 514B that is embedded in the plasma SiN film 515 thus.Layer 514B and the following layer 514A that forms have earlier constituted hole 514.
Subsequently, shown in Figure 23 J, intactly form passivating film 510, on passivating film 510, form graduation film 511, and form chromatic filter 512 thereon to cover dielectric film 508 and the surface that is embedded in the plasma SiN film 515 in the hole 514.Form lens 513 on the chip in the position corresponding to the hole on the light receiving part 504 514 on the chromatic filter 512.
Make solid state image pickup device thus with structure shown in Figure 17.
According to the method for the manufacturing imaging device in the present embodiment, opening 541 and 542 is formed in the dielectric film 508, and plasma SiN film 515 is embedded in opening 541 and 542 in each.Form hole 514 by repeating repeatedly this step.Therefore, the degree of depth h of the opening that forms with a step with (form all holding wires after) in the conventional situation compares, and can reduce the degree of depth 14Ah and the 14Bh of opening 541 and 542.That is, compare the opening that can form low aspect ratio with routine techniques.
As a result, when utilizing plasma CVD in each opening 541 and 542, to embed the plasma SiN film 515 of high index of refraction, can carry out the embedding of plasma SiN film 515 satisfactorily.
In addition, with opening 542 by under diameter 514B be provided with less than the opening 541 that forms in the step in front by last diameter.Therefore, can prevent that unnecessary reflection or refraction from appearring in 520 places, joint portion between opening 541 and 542.
In the above-described embodiments, the sidewall of at least one opening can form wedge-type shape.
For example, when the sidewall of the opening 542 that is formed at the top forms wedge-type shape, in the step shown in Figure 23 G, for example by regulating conditions of exposure, utilize photoetching method to form the resist pattern of opening 542, be etched with and make the resist pattern have wedge-type shape.In this stage, if adopt C 4F 8Gas then owing to pass through the effect that CF base deposit forms the sidewall diaphragm, can be easy to form satisfactorily wedge-type shape.
In addition, as mentioned above, when by the plasma SiN film 515 on the removal dielectric films 508 such as CMP, can in a step, carry out the graduation of dielectric film 508 and plasma SiN film 505.
In the above-described embodiments, form hole 514 by two independent steps that form opening.According to the quantity that embeds characteristic, holding wire, the degree of depth etc., can form three or more independent step of opening.
When forming hole 514 by many steps, the embedding character of the SiN film 515 in each opening is further improved.
In the above-described embodiments, the situation that the present invention is applied to solid state image pickup device has been described.Should be appreciated that the present invention can also be applied to other solid state image pickup device, as the CCD solid state image pickup device.
The invention is not restricted to the foregoing description, in the scope that does not depart from essence of the present invention, can adopt various other structures.
＜embodiment 8 〉
Next, the eighth embodiment of the present invention (below be called " embodiment 8 ") will be described.Embodiments of the invention 8 provide a kind of solid state image pickup device and manufacture method thereof with waveguiding structure, wherein two kinds of transparent membranes have been made up by utilization, it is the waveguide of polyimide resin (second high-index material) and plasma nitrided silicon (first high-index material), improved the embedding characteristic of waveguide, prevented because metal spreads the increase of the hickie that is caused from polyimide resin, and can prevent that transistorized reliability from weakening.
Figure 24 is the sectional view according to the solid state image pickup device of the embodiment of the invention 8.
Figure 24 shows the example that wherein the present invention is applied to the CMOS image sensor.In the pixel regions that the isolated district 603 of the element of the substrate 620 that is made of the semi-conducting material such as Si isolates, be provided with the pixel transistor that comprises photodiode 1, reads grid 604 etc.
In addition, the conducting electrode (polysilicon electrode) that reads grid 604 is set on the upper surface of substrate 620, gate insulating film 602 is arranged between them, and etch stop film 605A is set thereon, dielectric film 621 is arranged betwixt.The silicon nitride film that etch stop film 605A is formed by low pressure chemical vapor deposition (LP-silicon nitride) constitutes.
Dielectric film 606 is set and as the multilayer line 608 of upper layer film on etch stop film 605A.Conductor plug 607 is arranged between each bar line 608 and between the contact zone of substrate 620, and the line in each layer 608 is connected.Dielectric film 606 is mainly by SiO 2Form.
Form passivating film 610 on upper nonconductive Film 606, lens 613 are arranged on the passivating film 610 on chromatic filter 612 and the chip, and graduation film 611 is arranged between them.
In dielectric film 606, form the hole 606A that extends to the gate insulating film 602 on the light receiving area of photodiode 601 from the upper space of dielectric film 606, and in the 606A of hole, embed waveguide 609.
Waveguide 609 comprises the core (waveguide) that contains the first waveguide 609A and the second waveguide 609B, the first waveguide 609A constitutes by being arranged on outside plasma nitrided silicon, and second waveguide is made of the polyimide resin in the hollow space that is embedded in the first waveguide 609A (PIQ).Though below will describe manufacture method, the top of the first waveguide 609A is opened, and by applying polyimide material on the first waveguide 609A, embeds the second waveguide 609B from the opening of the first waveguide 609A.
As below will describing in detail, polyimide resin has and is lower than plasma nitrided silicon but is higher than at its peripheral SiO 2Refractive index.
The advantage of this structure is, compares with the waveguide that is made of simple plasma nitrided silicon, can improve the embedding characteristic, and be, because higher caking property between plasma nitrided silicon and the polyimide resin, so can obtain good optical characteristics.
In addition, the first waveguide 609A has moderate thickness, and the second waveguide 609B and gate insulating film 602 are arranged on apart distance enough far away, makes that the foreign metal in the polyimides is kept to minimum to the diffusion of photodiode.
And in the present embodiment, after the first waveguide 609A is embedded into hole 604A, before embedding the second waveguide 609B, carry out hydrogen anneal process (heat treatment under the hydrogen environment), make the hydrogen that is included in a large number in the plasma nitrided silicon be diffused in the photodiode 601.As a result, crystal defect in the photodiode 601 reduces, and prevents the generation of the noise that caused by white defective thus.
That is, the first waveguide 609A (plasma nitrided silicon) comprises hydrogen, and by carry out annealing in process (handling 60 minutes down as 400 ℃) in the hydrogen environment, quickens the supply of hydrogen in photodiode 601.Therefore, the dangling bonds that crystal defect caused that is caused by the metal that spreads to photodiode 601 from the second waveguide 609B is by hydrogen termination, and reduces hickie thus.
In this stage, by increasing the first waveguide 609A, increased the effect of hydrogen supply, and because the second waveguide 609B increases at a distance of the distance of photodiode 601, the effect that reduces hickie is able to further enhancing with respect to the occupied space of the second waveguide 609B.In addition, because the first waveguide 609A has the refractive index that is higher than the second waveguide 609B,, also improves light so compiling power.
But,, then have the problem (that is, the second waveguide 609B can not be embedded into) that breaks away from and may produce hole owing to residual stress because the surface of waveguide is stopped by the first waveguide 609A if the percentage of the first waveguide 609A excessively increases.Therefore, the appropriate thickness of the first waveguide 609A for example is about 1,000nm.
In addition, as shown in figure 24, etch stop film 605A is a kind of silicon nitride film, plays the etch stop device when the hole 606A of the well structure that is formed for producing waveguide by etching.In this embodiment, by allowing etch stop film 605A to be retained in the zone except that the light receiving area of photodiode 601, also allow etch stop film 605A to play the hydrogen absorbing film, it prevents that hydrogen from entering the transistor in other zone etc. when hydrogen being diffused in the photodiode 601 by the hydrogen anneal process of utilizing plasma nitrided silicon.
That is,, if supply to the excess hydrogen in transistorized source/drain region, then quicken the drain avalanche effect, on the contrary to transistorized reliability unfavorable (hot carrier resistance) about hydrogen supply effect by the first waveguide 609A.
Because the silicon nitride film (LP-silicon nitride) of the formation etch stop film 605A that forms by low pressure chemical vapor deposition has the hydrogen of suction effect, so allow the LP silicon nitride film be retained in except that light receiving area other zone (particularly, the zone of covering transistor), in case the entering of hydrogen.
In this embodiment, be arranged on silicon nitride film in other zone except that light receiving area and be known as anti-hydrogen and enter film 605B, wherein silicon nitride film plays etch stop film 605A in the light receiving area.
Enter film 605B by this anti-hydrogen, prevented transistor characteristic because the decay that the diffusion of hydrogen causes, and kept suitable operating characteristic.
In transistorized contact zone, removed anti-hydrogen and entered film 605B.But, because the barrier metal layer that is made of Ti, TiN etc. is arranged in the plug, so the contact zone is subjected to the protection of the suction hydrogen effect of barrier metal layer.
On the other hand, in part,, fully remove etch stop film 605A in order in photodiode 601, to supply with hydrogen effectively corresponding to waveguide, and the plasma nitrided silicon of the first waveguide 609A is directly contacted with gate insulating film 602, obtain above-mentioned hydrogen supply effect thus.
In addition, can be provided with anti-hydrogen enter film 605B with covering be arranged on the Semiconductor substrate in a large number such as the All Rangeses of transistorized active element (not comprising the part that conductor plug etc. passes through), perhaps can be arranged to only cover specific transistor.
Particularly, in the present embodiment, be arranged in the transistor (like cellulose crystal pipe, as read grid) near the zone of the plasma nitrided silicon that is used for waveguide, it is very big that the possibility that hydrogen enters takes place.Therefore, play the silicon nitride film that anti-hydrogen enters film 605B effect by use and surround these zones, can absorb hydrogen effectively and prevent that hydrogen from entering transistor.Thus, can obtain significant effect.
In addition, in the CMOS image sensor, pixel region and peripheral circuit region are arranged on the same chip, and hydrogen might enter the transistor in the peripheral circuit region, though this possibility is compared less with the transistor in the pixel region.Therefore, can provide anti-hydrogen to enter film 605B to cover the transistor in the peripheral circuit region.In addition, etch stop film 605A and anti-hydrogen enter film 605B needn't be continuous in whole zone, and can be provided with discontinuously.Position that anti-hydrogen enters film 605B is set is not limited to read space between electrode 604A and the upper layer film, as shown in figure 24, and can be according to the position to be set directly on the gate insulating film.
Figure 25 A and 25B are the explanatory views that expression light enters the reflection path of waveguide.Figure 25 A represents that light enters the state of the first waveguide 609A, and Figure 25 B represents that light enters the state of the second waveguide 609B.
At first, the first waveguide 609A (plasma nitrided silicon fiml) has 2.0 refractive index n, and the second waveguide 609B has 1.7 refractive index n, and dielectric film 606 has 1.4 refractive index n.
From this index of refraction relationship, shown in Figure 25 A, enter and directly arrive the light at the interface between the first waveguide 609A and the dielectric film 606 for surface from the first waveguide 609A, as incidence angle θ 1, be angle θ 1 between the normal at incidence angle and interface when being equal to or greater than critical angle, incident light is in reflection at the interface.
Similarly, when the light at the interface between the arrival first waveguide 609A and the second waveguide 609B has the critical angle θ 2 that is equal to or greater than two media, total reflection takes place.
When comparing θ 1 and θ 2, satisfy Si Nieer (Snell) law of establish an equation down (1) herein:
na·sinθa＝nb·sinθb ......(1)
Wherein na is the refractive index of medium a, and sin θ a is the refraction angle of medium a, and nb is the refractive index of medium b, and sin θ b is the refraction angle of medium b.For example, as na〉during nb, the θ a when θ b surpasses 90 ° is corresponding to critical angle.
Therefore, from index of refraction relationship, because θ 2 is bigger, so if the light that enters from the first waveguide 609A has the incidence angle that is equal to or greater than θ 2, then it is being gone forward side by side into photodiode 601 with the total reflection at the interface of the dielectric film 606 and the second waveguide 609B.
Shown in Figure 25 B, the light that enters from the second waveguide 609B with being refracted at the interface of the first waveguide 609A, and move through the first waveguide 609A, total reflection at the interface between the first waveguide 609A and dielectric film 606, enter the second waveguide 609B through the first waveguide 609A, on opposite side with the refraction at the interface of the first waveguide 609A, and in the total reflection at the interface between the first waveguide 609A and dielectric film 606 on the opposite side.By repeating this process, light enters photodiode 601.
As the condition that above-mentioned light is propagated, according to snell law, the refractive index of the first waveguide 609A must be higher than the refractive index of the second waveguide 609B, and incidence angle must be equal to or greater than the critical angle θ 3 of the second waveguide 609B and dielectric film 606.
＜embodiment 9 〉
Next, the example of making the method for solid state image pickup device according to ninth embodiment of the invention (below be called " embodiment 9 ") will be described.
Figure 26 A～26F is the sectional view of the manufacturing step of embodiment 9.
At first, shown in Figure 26 A, in the manufacturing step of routine, be formed in the substrate 620 such as photodiode 601 and the various elements that read grid 604.In addition, gate insulating film 602, read electrode 604A, down dielectric film 621 etc. is formed on the substrate 620.
Fully form the silicon nitride film 605 that enters film 605B as etch stop film 605A and anti-hydrogen thereon.Consider etching selection rate in forming the hole process, use the silicon nitride film that forms by low pressure chemical vapor deposition as silicon nitride film 605.
Subsequently, shown in Figure 26 B,, form upper layer film (comprising dielectric film 606, conductor plug 607, circuit 608 etc.) as in conventional preparation process.In this process, optionally remove silicon nitride film 605 nonessential parts, the dry etching that uses in the step of the contact hole by being formed for conductor plug 607 for example, and form etch stop film 605A thus and anti-hydrogen enters film 605B.In silicon nitride film 605, used such as CH 2F 2Or CHF 2Hydrogeneous organic gas.
Form hole 606A by the etching upper layer film then.In this process, on upper layer film, carry out the resist patterning, and come open pore by using etch stop film 605A to carry out the anisotropic dry etching as backstop apparatus.Then, remove resist, etch stop film 605A is removed to appear gate insulating film 602 corresponding to the part of waveguide.
Subsequently, shown in Figure 26 C, the upper surface of upper layer film (dielectric film 606) is carried out plasma CVD forming plasma nitrided silicon fiml 609a, and the plasma nitrided silicon of part is embedded into the part that forms among the 606A of hole as the first waveguide 609A.In this stage, in hydrogen atmosphere, carry out annealing in process, for example, carried out 60 minutes at 400 ℃.Therefore, hydrogen is fed into photodiode 601.
Subsequently, shown in Figure 26 D, on plasma nitrided silicon fiml 609a, apply polyimide film 609b, and polyimides is embedded in the hollow space of silicon nitride film 609a, is used to form the second waveguide 609B.Polyimides is to apply by spin coating method, and with 3,000rmp carried out 30 seconds.
Subsequently,, in nitrogen or air atmosphere, carry out cure process, for example, carried out 60 minutes at 300 to 350 ℃ in order to ensure in the adhesiveness of lower floor's (oxide-film or nitride film).
Subsequently, shown in Figure 26 E, remove plasma nitrided silicon fiml 609a and the polyimide film 609b that remains in upper layer film (dielectric film 606) upper surface by the plasma etching that use flows downward, carry out the upper surface of whole graduation to upper layer film (dielectric film 606) by etch back process.Fluorine base gas is used for polyimide film 609b, CHF 2, Ar or O 2Be used for plasma nitrided silicon fiml 609a.
Subsequently, shown in Figure 26 F,, form lens 613 on passivating film 610, graduation film 611, chromatic filter 612 and the chip successively as in conventional preparation process.Finish solid state image pickup device thus.
In solid state image pickup device in this example and preparation method thereof, can obtain following advantage:
(1) by using polyimide resin to be used to constitute second waveguide of waveguide, can improve the embedding character of waveguide, improve light and compile ability, reduce the variation in the sensitivity characteristic.Particularly, in having the solid state image pickup device of Miltilayer wiring structure, along with the increase of the wiring number of plies and pixel quantity, the aspect ratio of waveguide increases.Therefore, obtained significant effect.
(2),, can prevent because from the increase of the hickie that metal diffusing caused of polyimide resin by using plasma nitrided silicon fiml as first waveguide with by carrying out hydrogen annealing even polyimide resin is used for second waveguide.
(3) supply with effect for hydrogen, on transistor area, absorbed hydrogen as the LP-silicon nitride film of the etch stop film that forms the hole, and the transistor in the lower floor has obtained protection as the hydrogen annealing of the plasma nitrided silicon fiml of first waveguide.Therefore, can prevent transistorized reliability (hot carrier resistance) variation.
Industrial applicibility
According to solid state image pickup device of the present invention and preparation method thereof, waveguide has the forward direction wedge-like portion. That is, The opening that is used to form waveguide has forward direction wedge shape proterties, and wherein, the size of flat shape is from light incident side The surface reduce to light receiving part. Therefore, the embedding character of the light transmitting material of formation waveguide can get To improving, and the light of light receiving part is compiled efficient also be improved. In addition, circuit can prevent Be scratched. Thus, guaranteed the reliability of solid state image pickup device.
According to another kind of solid state image pickup device of the present invention, can make up such hole, wherein satisfactory Embedded high refractive index layer. Therefore, compare the embeddability of the high refractive index layer in the hole with routine techniques But matter coating etc. is significantly improved. Therefore, can improve the solid-state imaging device of reliability improvement Put.
In addition, do not have non-essential reflection or refraction to take place in the joint portion, incident light can not leak ground Import to light receiving part. Therefore, can provide such solid state image pickup device, wherein with conventional method Compare, light compiles efficient and sensitivity characteristic is further enhanced.
In addition, one deck forms to have in the situation of wedge side wall at least in the multilayer in hole, allows incident Light easily enters in the hole. Therefore, light compiles efficient and has further improved.
Another prepares the method for solid state image pickup device according to the present invention, and the degree of depth in single hole is reduced, and High refractive index layer can embed in each opening satisfactorily. Therefore, can prepare and have high light and converge The solid state image pickup device of collection efficient.
In addition, when upper shed diameter on the lower is set to less than the top diameter of under shed, owing to do not have There is formation may cause the step of non-essential reflection or refraction, compiles efficient and quick so can prepare light The solid state image pickup device that the sense characteristic improves.
In addition, form in the situation of wedge-type shape at the sidewall of at least one opening, light can easily be included in the hole.Therefore, light compiles efficient and can further improve.
In addition, another solid state image pickup device and preparation method thereof according to the present invention is contained in the hydrogen in first high-index material that is provided with in the waveguide by release, obtained hydrogeneous electric conversion portion.Therefore, can reduce because metal increases from the hickie that diffusion caused of waveguide to photoelectric conversion section.Thereby can improve image quality.
In addition, by in the zone except that the light receiving area of photoelectric conversion section, forming the hole, prevented that hydrogen from entering the zone except that photoelectric conversion section with the etch stop film.Thereby, can prevent the decay of transistor characteristic.

Claims (19)

1. solid state image pickup device comprises:
A plurality of light receiving parts, described a plurality of light receiving parts are arranged in the substrate, and produce electric charge in response to incident light;
Smoothing layer covers the predetermined element be arranged on the described substrate to carry out graduation;
Be arranged on the many signal line on the described smoothing layer; With
With the lead waveguide of each described light receiving part of incident light, the space between described many signal line is passed in described waveguide;
Wherein, described waveguide comprises the multilayer with different-diameter, and in the adjacent two layers in described multilayer, the upper strata by under diameter be provided with less than lower floor by last diameter.
2. solid state image pickup device as claimed in claim 1, wherein, one deck at least of described multilayer has wedge side wall.
3. solid state image pickup device as claimed in claim 1, wherein, described waveguide comprises having light transmissive films, described light transmissive films is embedded in the hole that forms by the etching dielectric film, the refractive index of described light transmissive films is higher than the refractive index of described dielectric film, described light transmissive films comprises the first material part that comprises hydrogen at least, and described light receiving part comprises the hydrogen that discharges by the heat treatment under the hydrogen environment from described first material.
4. solid state image pickup device as claimed in claim 3, wherein, described first material partly comprises the silicon nitride that forms by PCVD.
5. solid state image pickup device as claimed in claim 3, wherein, the etch stop film that is used to form the hole is arranged on the upper surface of the gate insulating film on the described light receiving part, and described first material partly contacts with described gate insulating film by the opening of described etch stop film.
6. solid state image pickup device as claimed in claim 5, wherein, described etch stop film comprises by the formed silicon nitride of low-pressure chemical vapor deposition.
7. solid state image pickup device as claimed in claim 5, wherein, described etch stop film extends on the transistor area that is arranged in the light receiving part substrate on every side at least.
8. solid state image pickup device as claimed in claim 3, wherein, described first material part has opening at the top, is provided with the second material part in described opening, and the refractive index of described second material part is lower than the refractive index of described first material part.
9. solid state image pickup device as claimed in claim 8, wherein, described second material partly comprises the synthetic resin material.
10. solid state image pickup device as claimed in claim 9, wherein, described synthetic resin material is a polyimide resin.
11. a method of making solid state image pickup device, described solid state image pickup device comprises: be arranged on the photoelectric conversion section in the Semiconductor substrate; Be arranged on the described Semiconductor substrate, between the upper layer film of gate insulating film is arranged; Be formed on the light receiving area of described photoelectric conversion section to extend to the hole of described gate insulating film from described upper layer film; And being embedded in waveguide in the described hole, described method comprises the steps:
Embed first high-index material that comprises hydrogen and constitute a described waveguide part at least in the hole in being formed at described upper layer film, described first high index of refraction is higher than the refractive index of described upper layer film; With
By described first high-index material is heat-treated, and discharge hydrogen to described photoelectric conversion section from described first high-index material in the hydrogen environment.
12. the method for manufacturing solid state image pickup device as claimed in claim 11, wherein, the plasma chemical vapor deposition by silicon nitride forms described first high-index material.
13. the method for manufacturing solid state image pickup device as claimed in claim 11 also comprises the steps:
On the Semiconductor substrate that is provided with described photoelectric conversion section and described gate insulating film, form the etch stop film;
On described etch stop film, form upper layer film;
Form the hole by the described upper layer film of etching; With
Remove left etch stop film in bottom, described hole.
14. the method for manufacturing solid state image pickup device as claimed in claim 13, wherein, the low-pressure chemical vapor deposition by silicon nitride forms described etch stop film.
15. the method for manufacturing solid state image pickup device as claimed in claim 13 wherein, allows the silicon nitride film of the described etch stop film of formation left in the zone except that the light receiving area of described Semiconductor substrate.
16. the method for manufacturing solid state image pickup device as claimed in claim 13, wherein, being allowed to left silicon nitride film in the zone except that described light receiving area is allowed to left in covering a plurality of transistorized zone that at least partly or entirely is arranged in the described Semiconductor substrate.
17. the method for manufacturing solid state image pickup device as claimed in claim 16, wherein, describedly be allowed to left silicon nitride film in the zone except that described light receiving area and be allowed to left the covering and be arranged at transistorized zone around the described photoelectric conversion section to small part.
18. the method for manufacturing solid state image pickup device as claimed in claim 16, wherein, described be allowed to left silicon nitride film in the zone except that described light receiving area be arranged on described transistorized gate electrode and place on the described gate electrode the layer holding wire between.
19. the method for manufacturing solid state image pickup device as claimed in claim 11 also is included in the top of first high-index material of described waveguide and forms opening, and in described opening second high-index material is set;
Wherein, the refractive index of described first high-index material is higher than the refractive index of described second high-index material, and the refractive index of described second high-index material is higher than the refractive index of described upper layer film.
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