JP2001015724A - Solid-state imaging device - Google Patents

Abstract

(57) [Problem] To provide a solid-state imaging device capable of improving sensitivity to light of a specific wavelength such as ultraviolet light and enabling high-sensitivity products to be manufactured with high yield. SOLUTION: A solid-state imaging device 1 in which an insulating film 11 for transmitting light having a specific wavelength λ1 is formed on a sensor unit 3 is constituted.
In addition, a first anti-reflection film 11 is provided on the semiconductor substrate 2 of the sensor unit 3, and a second anti-reflection film 12 or 13 is formed thereon with or without an interlayer film 6. Solid-state imaging device 2 having a specific wavelength light λ1 transmitted by anti-reflection film 11 and second anti-reflection film 12 or 13
1, 31, 41 are constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device suitable for use in, for example, detection of ultraviolet light reception.

[0002]

2. Description of the Related Art In general, a solid-state imaging device detects and detects visible light, and can detect and detect light in a wide wavelength range of a visible light region.

On the other hand, in a device such as a microscope or a semiconductor exposure device (so-called stepper), it has been considered to apply a solid-state image pickup device to a light-receiving device using ultraviolet light as a light source.

[0004]

However, in the conventional solid-state image pickup device for ultraviolet light, the sensitivity is easily affected by variations in the thickness of the interlayer insulating film and the like on the sensor portion, and as a result, the production yield is reduced. There was a problem of doing.

[0005] Light in a short wavelength region, such as ultraviolet light,
There is a problem that the reflectance on the surface of the silicon substrate is very large, and the sensitivity of light in the ultraviolet region is lower than that in the visible light region.

Further, since the conventionally used ultraviolet light source has a broad emission wavelength distribution, a very large antireflection effect can be obtained even when an antireflection film utilizing multiple reflection of an upper layer film is used. And it was difficult to raise the sensitivity.

In order to solve the above-mentioned problems, the present invention provides a solid-state imaging device capable of improving the sensitivity to light of a specific wavelength such as ultraviolet light and manufacturing high-sensitivity products with high yield. Is provided.

[0008]

According to the present invention, there is provided a solid-state imaging device comprising an insulating film for transmitting light of a specific wavelength formed on a sensor portion.

According to the configuration of the present invention described above, the insulating film formed on the sensor section is configured to transmit light of a specific wavelength, so that the sensitivity to the light of the specific wavelength can be improved.

The solid-state imaging device of the present invention has a first anti-reflection film on a semiconductor substrate of a sensor section, and a second anti-reflection film is formed thereon with or without an interlayer film. The first antireflection film and the second antireflection film allow light of a specific wavelength to pass therethrough.

According to the configuration of the present invention, since the first antireflection film and the second antireflection film are configured to transmit light of a specific wavelength, it is possible to improve sensitivity to the light of the specific wavelength. it can. In addition, since two antireflection films are used, the reflectance can be accurately controlled by adjusting the thickness of each film.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a solid-state imaging device in which an insulating film that transmits light of a specific wavelength is formed on a sensor unit.

Further, according to the present invention, in the solid-state imaging device, the specific wavelength light is light having a wavelength in an ultraviolet region.

According to the present invention, there is provided a semiconductor device comprising:
A second anti-reflection film is formed on the first anti-reflection film with or without an interlayer film,
The solid-state imaging device is configured to transmit light of a specific wavelength by using a first antireflection film and a second antireflection film.

Further, according to the present invention, in the solid-state imaging device, the specific wavelength light is light having a wavelength in an ultraviolet region.

FIG. 1 is a schematic configuration diagram (cross-sectional view) of a CCD solid-state imaging device according to an embodiment of the present invention. This CC
In the D solid-state imaging device 1, two impurity regions 3A and 3B constituting a light receiving unit (sensor unit) 3 are formed in a semiconductor substrate 2 made of, for example, a silicon substrate.
A and 3B form a photodiode.

A transfer electrode 5 made of, for example, polycrystalline silicon is formed on the semiconductor substrate 2 with an insulating film 4 interposed therebetween except for a portion above the sensor section 3, and an interlayer insulating film 6 is formed to cover the transfer electrode 5. Have been. A light-shielding film 7 such as an Al film is formed on the interlayer insulating film 6, and an opening is formed in a portion of the light-shielding film 7 on the light receiving section 3. Further, a passivation film 8 is formed entirely over the light shielding film 7, and a thick insulating layer 9 is formed thereon.

Incidentally, the surface of the insulating layer 9 is flattened as necessary to form an on-chip lens or the like.

In the CCD solid-state imaging device 1 according to the present embodiment, an antireflection film 11 made of an insulating film is formed on the sensor unit 3 in particular.
Is provided. In this case, an antireflection film 11 is formed between the insulating film 4 and the interlayer insulating film 6.

The antireflection film 11 is formed of an insulating film made of a material that transmits light of a specific wavelength such as light in an ultraviolet region used as a light source, for example, ultraviolet light having a wavelength of 266 nm. For example, a SiN-based insulating film can be used.

The thickness of the antireflection film 11 is set so that light of a specific wavelength used as a light source is sufficiently transmitted.
More specifically, as shown in FIG. 5, the wavelength at which the reflectance is minimized is made to substantially match the wavelength λ1 of the specific wavelength light used as the light source, as shown in FIG.

Thus, it is possible to prevent reflection of light of a specific wavelength used as a light source and increase the amount of incident light.
Sufficient sensitivity to this specific wavelength light, for example, light having a wavelength in the ultraviolet region (hereinafter referred to as ultraviolet light) can be ensured.

Next, as another embodiment of the present invention, CC
FIG. 2 shows a schematic configuration diagram (cross-sectional view) of the D solid-state imaging device.
This CCD solid-state image pickup device 21 is the same as the CC
Similar to the D solid-state imaging device 1, a first antireflection film 11 is provided between the insulating film 4 and the interlayer insulating film 6 on the sensor unit 3. Further, a second antireflection film 12 is provided between the passivation film 8 and the insulating layer 9 on the sensor unit 3. That is, the second antireflection film 12 is formed on the first antireflection film 11 via the interlayer insulating film 6 and the passivation film 8.

The first antireflection film 11 and the second antireflection film 12 are made of an insulating film of the same material, and the two antireflection films 11 and 12 pass light of a specific wavelength. Is done.

That is, the film thickness of the first and second anti-reflection films 11 and 12 is set so that light of a specific wavelength is transmitted by the two-layer anti-reflection films 11 and 12 or the two-layer anti-reflection film is used. Set the total of the film thicknesses.

The other configuration is the same as that of the CCD of the previous embodiment.
Since the configuration is the same as that of the solid-state imaging device 1, the same reference numerals are given and duplicate description is omitted.

According to the CCD solid-state imaging device 21 of the present embodiment, similarly to the above-described embodiment, reflection of light of a specific wavelength used as a light source is prevented, and sufficient sensitivity to the light of the specific wavelength, for example, ultraviolet light is achieved. Can be secured.

Further, in this embodiment, since two layers of antireflection films 11 and 12 are used, the reflectance can be controlled with high precision by adjusting the thickness of each film.

Next, as another embodiment of the present invention, CC
FIG. 3 shows a schematic configuration diagram (cross-sectional view) of the D solid-state imaging device.
This CCD solid-state imaging device 31 is the same as the CC
Similarly to the D solid-state imaging device 21, the insulating film 4 on the sensor unit 3
An antireflection film is provided between the insulating layer 9 and the interlayer insulating film 6 and between the passivation film 8 and the insulating layer 9 on the sensor unit 3.

However, in the CCD solid-state imaging device 31 of the present embodiment, the first antireflection film 11 provided between the insulating film 4 and the interlayer insulating film 6 on the sensor unit 3 and the sensor unit 3
The second antireflection film 13 provided between the upper passivation film 8 and the insulating layer 9 is made of different materials.

The first anti-reflection film 11 is made of an insulating film having a refractive index of n1, and the second anti-reflection film 13 is made of an insulating film having a refractive index of n2. Then, these two layers of antireflection films 11, 1
3 is configured to transmit light of a specific wavelength.

That is, each of the anti-reflection films 11, 1 is made to pass light of a specific wavelength by the two anti-reflection films 11, 13.
3, the material, that is, the refractive index, and each antireflection film 1
The film thicknesses 1 and 13 are set.

The other structure is the same as that of the above-described embodiment.
Since they are the same as those of the D solid-state imaging devices 1 and 21, the same reference numerals are given and duplicate explanations are omitted.

According to the CCD solid-state imaging device 31 of the present embodiment, similarly to the previous embodiment, the reflection of light of a specific wavelength used as a light source is prevented, and sufficient sensitivity to the light of the specific wavelength, for example, ultraviolet light is achieved. Can be secured.

Further, in the present embodiment, since two layers of antireflection films 11 and 13 are used, the control of the reflectance can be performed with high precision by selecting each material, that is, the refractive index, and adjusting each film thickness. It can be carried out.

In the embodiment shown in FIGS. 2 and 3, the second antireflection film 1 on the passivation film 8 is used.
Although 2 or 13 is formed only on the sensor section 3,
The second antireflection film 12 or 13 may be formed entirely over the passivation film 8.

Next, FIG. 4 shows a schematic configuration diagram (cross-sectional view) of a CCD solid-state imaging device as still another embodiment of the present invention. In the CCD solid-state imaging device 41, an antireflection film is provided between the insulating film 4 and the interlayer insulating film 6 on the sensor unit 3 as in the CCD solid-state imaging device 1 of the above embodiment.

However, in the CCD solid-state imaging device 41 of the present embodiment, the first anti-reflection film 11 made of an insulating film having a refractive index of n1 and the second anti-reflection film made of an insulating film having a refractive index of n2 are used. It has a laminated structure 14 with an anti-reflection film 13, that is, a laminated structure 14 with two layers of anti-reflection films 11 and 13 made of different materials. That is, the second antireflection film 13 is formed directly on the first antireflection film 11 without an interlayer film. The two layers of antireflection films 11 and 13 are configured to transmit light of a specific wavelength.

That is, each of the antireflection films 11, 1 and 1 is made to pass light of a specific wavelength by these two antireflection films 11, 13.
3, the material, that is, the refractive index, and each antireflection film 1
The film thicknesses 1 and 13 are set.

The other structure is the same as that of the CCD of the previous embodiment.
Since the configuration is the same as that of the solid-state imaging device 1, the same reference numerals are given and duplicate description is omitted.

According to the CCD solid-state imaging device 41 of the present embodiment, similarly to the previous embodiment, reflection of light of a specific wavelength used as a light source is prevented, and sufficient sensitivity to the light of the specific wavelength, for example, ultraviolet light is achieved. Can be secured.

Further, according to the present embodiment, since two layers of antireflection films 11 and 13 are used, the control of the reflectance is performed by selecting each material, that is, the refractive index, and adjusting each film thickness. It can be performed accurately.

By the way, in the manufacture of the solid-state imaging device,
When the thickness of each layer (for example, the interlayer insulating film 6 and the passivation film 8) on the sensor unit 3 varies, as described above, the sensitivity to light of a specific wavelength is affected and changes.

On the other hand, according to the configuration of the embodiment shown in FIGS. 2 and 3, the thickness of the antireflection film, particularly the thickness of the second antireflection film 12 or 13 is selected during the manufacturing process. By forming the layers, it is possible to reduce the influence of the sensitivity caused by the variation in the thickness of each layer such as the interlayer insulating film 6 and the passivation film 8.

Here, when the thickness of the antireflection film is changed,
Since the wavelength dependence of the reflectance changes, the sensitivity of light of a specific wavelength also changes. For example, in the graph of the wavelength dependence of the reflectance shown in FIG. 5, when the thickness of the antireflection film is changed, the position of the curve shifts in the left-right direction. When the thickness of the antireflection film is increased, the curve shifts to the right in FIG. 5, that is, the longer wavelength. Conversely, when the film thickness is reduced, it shifts to the left, that is, to the shorter wavelength.

Therefore, in the step of forming the antireflection film,
Measure the wavelength dependence of the reflectance before film formation, and select the thickness of the anti-reflection film based on the measurement result so that a low reflectance is obtained for light of a specific wavelength. I do.

This makes it possible to more effectively absorb the above-described variation in the thickness of each layer, so that the sensitivity to light of a specific wavelength can be accurately controlled. Therefore, it is possible to manufacture high-sensitivity products with high yield.

Next, a method for specifically selecting the thickness of the antireflection film will be described. First, each layer under the antireflection film, and in FIGS. 2 and 3, each layer up to the passivation film 8 are formed.

Then, the reflectance is measured in a clean room by using, for example, Ellipso. In particular,
Using monochromatic light of several wavelengths selected from the specific wavelength λ1 of the light source to be used and its vicinity, the reflectance for each monochromatic light is measured.

From the obtained measured value of the reflectance, the wavelength that gives the minimum value of the reflectance at that time, that is, the film thickness at the time of the measurement, can be obtained. At this time, as long as the wavelength giving the minimum value can be determined, the above-mentioned measurement point may or may not include the specific wavelength λ1 of the light source.

Next, a so-called feedforward is applied to the obtained measurement data using a preset calculation formula so that the wavelength giving the minimum value of the reflectance coincides with the specific wavelength λ1 to be used. Select the thickness of the anti-reflection film.

Thereafter, a second antireflection film 12 or 13 having a selected thickness is deposited on the passivation film 8.

After the second anti-reflection film 12 or 13 is formed, the reflectance is measured again to confirm whether the wavelength at which the reflectance is minimized substantially matches the wavelength λ1 to be used. Good.

If the wavelength giving the minimum value is shorter than the specific wavelength λ1 to be used from the measurement data of the reflectance, the thickness of the second antireflection film 12 or 13 on the passivation film 8 is By selecting and depositing, it is possible to lengthen the wavelength giving the minimum value and make it substantially coincide with the specific wavelength λ1 to be used.

On the other hand, when the wavelength giving the minimum value from the reflectance measurement data is longer than the specific wavelength λ1 to be used, the method for making the wavelength substantially coincide with the specific wavelength λ1 is slightly different. An example of the measured data of the reflectance in this case is shown in FIG.
Shown in The circles in the figure indicate the measured values of the reflectance, and from these measured values, a characteristic curve shown by a broken line is obtained, and the wavelength giving the minimum value is obtained from this curve. The wavelength giving the minimum value is slightly longer than the wavelength λ1 to be used.

As a first method in this case, for example, instead of forming an antireflection film, the thickness of the uppermost passivation film 8 is reduced to shorten the wavelength giving the minimum value. Specifically, for example, a part of the formed passivation film 8 is removed by etching or the like.

The CC obtained by the first method
The D solid-state imaging device does not have an anti-reflection film formed on the passivation film 8, and thus has a configuration shown in FIG. 1, that is, a configuration having only a lower anti-reflection film instead of the configuration shown in FIG. 2 or FIG.

Here, as a characteristic of the antireflection film made of an insulating film as used in the present invention, there are a plurality of wavelengths giving a minimum value of the reflectance as shown in FIG. Therefore, as a second method, the film thickness is selected such that the wavelength giving the next minimum value on the short wavelength side coincides with the wavelength λ1 used.
A second antireflection film 12 or 13 is deposited on the passivation film 8.

According to the selection method described above, the dispersion of the film thickness of each layer such as the passivation film 8 is absorbed to obtain the specific wavelength λ.
1 is improved, and a product with high sensitivity can be manufactured with a high yield.

Although the above-described selection method has been described as applied to the selection of the film thickness after the passivation film 8 is formed, the same method can be applied to other portions. For example, the following cases can be considered.

1) In the anti-reflection film of the laminated structure 14 having the structure shown in FIG. 4, the reflectance is measured after forming the first anti-reflection film 11, and the second anti-reflection film is formed based on the measured value. The thickness of the film 12 is selected. This is particularly effective when the first antireflection film 11 is formed thin and it is difficult to control the film thickness with high accuracy.

2) The reflectivity is measured once the antireflection film is formed, and the wavelength giving the minimum value is the characteristic wavelength λ1.
If it is deviated from the above, the correction amount of the film thickness of the antireflection film is selected so that the wavelength giving the minimum value substantially coincides with the characteristic wavelength λ1. Then, if the film thickness is insufficient, an anti-reflection film is continuously formed. When the film thickness is excessive, a part of the anti-reflection film is removed or the anti-reflection film is continuously formed so that the wavelength giving the minimum value on the short wavelength side substantially matches the characteristic wavelength λ1. Perform the membrane. When two or more antireflection films are provided, it is preferable to mainly correct the thickness of the uppermost antireflection film.

It is to be noted that a reflectivity measuring device may be provided in the film forming device, and by providing the device in the film forming device, the film formation of the antireflection film or the correction of the film thickness can be promptly performed based on the measurement result. It can be carried out.

It is to be noted that three or more antireflection films may be formed by combining, for example, the upper layer and the lower layer by combining the configurations of the above-described embodiments. In this case, since the degree of freedom of adjustment by selecting the refractive index, the film thickness, and the like is widened, there is an advantage that the sensitivity to specific wavelength light can be controlled more accurately. However, an increase in the number of antireflection films slightly increases the number of manufacturing steps.

In each of the above embodiments, the present invention is applied to a CCD solid-state imaging device. However, the present invention is similarly applied to other solid-state imaging devices, for example, a MOS type solid-state imaging device using MOS transistors for pixels. As a result, the sensitivity to the specific wavelength light can be improved.

The present invention is not limited to the above-described embodiment, but may take various other configurations without departing from the gist of the present invention.

[0067]

According to the present invention, the reflection of light of a specific wavelength can be suppressed to a very low level, and the sensitivity can be increased.

Therefore, according to the present invention, it is possible to constitute a solid-state imaging device suitable for application to a light receiving element in an apparatus such as a microscope or an exposure apparatus using monochromatic light of a specific wavelength as a light source.

Further, when the second anti-reflection film is formed on the first anti-reflection film via an interlayer film, it is possible to absorb variations in film thickness of each thin film by feed forward. The yield at the time can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram (cross-sectional view) of a solid-state imaging device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram (cross-sectional view) of a solid-state imaging device according to another embodiment of the present invention.

FIG. 3 is a schematic configuration diagram (cross-sectional view) of a solid-state imaging device according to another embodiment of the present invention.

FIG. 4 is a schematic configuration diagram (cross-sectional view) of a solid-state imaging device according to still another embodiment of the present invention.

FIG. 5 is a diagram showing the wavelength dependence of the reflectance of an antireflection film.

FIG. 6 is a diagram showing an example of reflectance measurement data.

[Explanation of symbols]

1, 21, 31, 41 CCD solid-state imaging device, 2 semiconductor substrate, 3 light receiving section (sensor section), 4 insulating film, 5 transfer electrode, 6 interlayer insulating film, 7 light shielding film, 8 passivation film, 9 insulating layer, 11 First antireflection film, 1
2,13 second antireflection film, 14 laminated structure

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M118 AA01 AB01 BA10 BA14 CA03 CA33 CA34 FA06 GB03 GB07 GB11 GC20 5C024 AA00 EA00 EA08 FA01 FA11 GA11 5F088 BA18 BB03 EA04 HA01 LA05

Claims (4)

[Claims] 1. A solid-state imaging device, wherein an insulating film that transmits light of a specific wavelength is formed on a sensor unit. 2. The solid-state imaging device according to claim 1, wherein the specific wavelength light is light having a wavelength in an ultraviolet region. 3. A first antireflection film is formed on a semiconductor substrate of the sensor section, and a second antireflection film is formed on the first antireflection film with or without an interlayer film. A solid-state imaging device characterized in that light of a specific wavelength is transmitted by the first antireflection film and the second antireflection film. 4. The solid-state imaging device according to claim 3, wherein the specific wavelength light is light having a wavelength in an ultraviolet region.