JP2825966B2 - Solid-state imaging device with micro lens - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device with a microlens capable of greatly improving the light-receiving sensitivity of a solid-state imaging device.

2. Description of the Related Art In recent years, a solid-state imaging device has been used as a light-receiving element of a video movie, a still camera, and the like because of its excellent features such as small size, light weight, long life, low afterimage, and low power consumption.

In the conventional solid-state imaging device with microlenses, the light receiving sensitivity of the element has been improved by optimizing only the thickness of the microlens while keeping the thickness of the transparent filter film constant.

However, in such a conventional solid-state imaging device with microlenses, the thickness of the microlens is too large in order to optimize only the thickness of the microlens and improve the light receiving sensitivity of the element. There are problems that it is difficult to form a micro lens and that the light receiving sensitivity cannot be sufficiently improved.

The present invention solves the above-mentioned problem, and in a micro cell constituting a solid-state imaging device array, by optimizing both the thickness of the transparent filter film and the thickness of the micro lens, the device can be formed even if the thickness of the micro lens is small. To provide a solid-state imaging device with a microlens capable of sufficiently improving the light receiving sensitivity of the solid-state imaging device.

Means for Solving the Problems In order to achieve the above object, the present invention limits the thickness of the transparent film so that the microlens has a thickness of 3.7 μm.
m and a specific thickness optimized in the range of m or less.

Operation In the present invention, the thickness of the microlens can be designed to be thinner by the above configuration, the production thereof is facilitated, and the light receiving sensitivity is improved.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a solid-state imaging device with a microlens according to an embodiment of the present invention. In the figure, 1
Is a silicon substrate for forming a solid-state imaging device, 2 is a cell of a solid-state imaging device array forming a solid-state imaging device,
Reference numeral 3 denotes a photodiode for converting received light into an electric signal; 4, an aluminum light-shielding film for blocking transmitted light; 5, a transparent filter film for flattening a solid-state imaging device; Light to photodiode 3
This is a microlens for condensing light at

FIG. 2 shows that cell 2 has a horizontal width of 7.5 μm and a vertical width of 9.6 μm.
In the solid-state imaging device in which the cells 2 are arranged in 512 rows × 485 columns, the relationship between the microlens thickness and the aperture ratio is shown. The parameters A to E are set so that the thickness of the transparent filter film 5 is 2
The case where the thickness is changed from μm to 10 μm is shown. Here, the aperture ratio is represented by (light reception amount of photodiode / area of cell) × 100. In general, the higher the aperture ratio, the higher the light receiving sensitivity of the solid-state imaging device. Fig. 2 (a), (b), (c)
Indicates the case where the width and height of the micro lens are different.
The vertical widths are respectively 5.5 μm and 7.6 μm in FIG. 2 (a), 6.5 μm and 8.6 μm in FIG. 2 (b), and 7.5 μm and 9.6 μm in FIG. 2 (c).
The case of m is shown.

FIG. 3 shows the relationship between the thickness of the microlens 6 and the thickness of the transparent filter film 5 at which the highest light receiving sensitivity is obtained, based on the results of FIGS. 2 (a) to 2 (c). The parameters (a), (b), and (c) are (a), (b),
According to (c), the thickness of the transparent filter film 5 is set to 8 to 10 μm.
It can be seen that the thickness of the microlens for obtaining the highest sensitivity becomes thinner.

The solid-state imaging device configured as described above will be described.

In FIG. 1, a silicon substrate 1 has a width of 7.5 μm,
A cell array in which the cells 2 of the solid-state imaging device having a vertical width of 9.6 μm are arranged in 512 rows × 485 columns is formed. Next, the photodiode 3 is formed in an area smaller than the cell 2 of the solid-state imaging device. Next, an aluminum light-shielding film 4 having a thickness of 1.0 to 2.0 μm is formed on the silicon substrate 1, and an opening having a horizontal width of 5.9 μm and a vertical width of 3.5 μm is formed on the photodiode 3. next,
A transparent filter film 5 having a thickness of 8 to 10 μm is formed on the photodiode 3 and the aluminum light shielding film 4. Next, a micro lens 6 having a width of 5.5 to 7.5 μm, a vertical width of 7.6 to 9.6 μm, and a thickness of 1.9 to 3.7 μm is formed on the transparent filter film 5. At this time, the lens thickness of the microlens 6 is limited to one half or less of the lateral width, which is the short dimension of the lens.

As described above, according to the present embodiment, by limiting the thickness of the transparent filter film 5 to 8 to 10 μm as shown in FIG. 1, the lens of the micro lens 6 for obtaining the highest sensitivity as shown in FIG. The thickness can be reduced to 3.7 μm or less, which is the maximum lens thickness, so that microlenses can be easily formed and the light receiving sensitivity of the element can be improved.

In the example, the horizontal width of the cell is 7.5 μm and the vertical width is 9.6 μm.
m, the relationship between the thickness of the transparent filter film 5 and the thickness of the microlens 6 for obtaining the highest sensitivity was obtained for a solid-state imaging device in which the horizontal width of the opening of the photodiode was 5.9 μm and the vertical width was 3.5 μm. Is not limited to the above dimensions, and may be a solid-state imaging device of any dimensions. For example, as shown in FIGS. 4 (a) to (c) and FIG. 5, the cell has a width of 6.4 μm, a height of 7.5 μm, a width of a photodiode opening of 1.8 μm, and a height of 5.3 μm. In the solid-state imaging device, the thickness of the microlens can be suppressed to 3.1 μm or less by limiting the thickness of the transparent filter film 5 to 6 to 10 μm. As shown in FIGS. 6 (a) to 6 (c) and FIG. 7, the cell has a width of 5.6 μm and a height of 7.0 μm.
The width of the opening of the photodiode is 3.7μm and the height is
In a 4.0 μm solid-state imaging device, the thickness of the microlens can be suppressed to 2.7 μm or less by limiting the thickness of the transparent filter film 5 to 4 to 10 μm. Further, as shown in FIGS. 8 (a) to 8 (c) and FIG. 9, the cell has a width of 5.6 μm, a height of 4.8 μm, a photodiode having a width of 2.0 μm, and a height of 4.0 μm. In solid-state imaging devices,
By limiting the thickness of the transparent filter film 5 to 4 to 10 μm, the thickness of the micro lens can be suppressed to 2.3 μm or less. Further, in the embodiment, a cell array of 512 rows × 485 columns is used, but the cell array is not limited to the above number and may be any. For example, a cell array of 768 rows × 485 columns can be considered.

Effects of the Invention As is clear from the above embodiments, according to the present invention, in a solid-state imaging device having a cell having a short side of 7.5 μm or less, the thickness of a microlens is reduced to 3.7 μm or less by limiting the thickness of a transparent film. Optimizing for a constant value of
Provided is a solid-state imaging device with a microlens that achieves the highest sensitivity in a cell of the size described above with a microlens thickness of 3.7 μm or less, thus facilitating the creation of the microlens and improving the light receiving sensitivity. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a solid-state imaging device according to an embodiment of the present invention, and FIGS. 2 to 9 are diagrams showing the relationship between the thickness of a microlens capable of obtaining the highest light receiving sensitivity and the thickness of a transparent filter. 1 ... silicon substrate (semiconductor substrate), 3 ... photodiode (light receiving section), 4 ... aluminum light shielding film (light shielding section), 5 ... transparent filter film (transparent film), 6 ... microlens.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 27/14

Claims (1)

(57) [Claims] A light-receiving portion formed on one main surface of a semiconductor substrate; a light-shielding portion formed on the semiconductor substrate by providing an opening on the light-receiving portion; A transparent film formed on the
And a microlens formed at least on a portion corresponding to the upper part of the light-receiving portion on the transparent film, and the short side is 7.5 μm.
m, wherein the thickness of the microlens is 3.7 μm or less, and the thickness of the transparent film and the thickness of the microlens are within a range of 4 μm to 10 μm. A solid-state imaging device with a microlens, wherein both of the thicknesses are set to values that provide the maximum light receiving sensitivity.