JP2988556B2 - Microlens manufacturing method and semiconductor device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a microlens for forming a microlens on a substrate and a method of manufacturing a semiconductor device having a microlens on a surface.

[0002]

2. Description of the Related Art In recent years, many problems have arisen in the manufacturing process and the performance in accordance with the high integration and miniaturization of semiconductor devices. Thus, there is a problem that the sensitivity and the S / N ratio are reduced due to the reduction in the area of the photoelectric conversion unit. Therefore, a solid-state imaging device having a microlens on a photoelectric conversion unit has been used.

Hereinafter, a conventional method of manufacturing a microlens will be described with reference to an example of a solid-state imaging device. FIG. 3 is a sectional view of a main part of a conventional solid-state imaging device. In FIG. 3, 1
Is a semiconductor substrate made of silicon single crystal, 2 is a photoelectric conversion section made of a photodiode, 3 is a transfer section for transferring charges from the photoelectric conversion section 2, 4 is a light shielding section made of a metal film, and 5 is an organic transparent film A flattening layer, 6 is a color filter layer made of an organic film dyed in a desired color, 7 is an intermediate layer made of an organic transparent film, and 8 is a microlens made of an organic transparent material and formed in a convex shape.

[0004] The operation of the solid-state imaging device formed as described above will be described below. First, light that has entered above the photoelectric conversion unit 2 and the light shielding unit 4 is collected by the microlens 8, and reaches the photoelectric conversion unit 2 through the intermediate layer 7, the color filter layer 6, and the flattening layer 5. The light that has reached the photoelectric conversion unit 2 is converted into a charge, and the charge is transferred by the transfer unit 3 and output as a signal.

Next, a conventional method for manufacturing a microlens will be described. FIG. 4 is a cross-sectional view for explaining a first step in the conventional method of manufacturing a microlens, FIG. 5 is a cross-sectional view for explaining a second step in the same manufacturing method, and FIG. 6 is a cross-section for explaining a third step in the same manufacturing method. FIG . 7 is a cross-sectional view for explaining a fourth step in the manufacturing method. First, as shown in FIG. 4, a planarizing layer 5, a color filter layer 6, and an intermediate layer 7 are formed on a semiconductor substrate 1 on which a photoelectric conversion unit 2, a transfer unit 3, a light shielding unit 4, and the like are formed. A lens resin material to be the lens 8 is spin-coated to form a transparent layer 8a. Next, as shown in FIG. 5, the transparent layer 8a is exposed by irradiating ultraviolet rays 10 using a mask 9 for determining the shape of the microlens 8. FIG. 5 shows a case where the transparent layer 8a is of a positive type, and the exposed area 11 is removed by development.
As shown in FIG. 6, the pattern of the transparent layer 8a is divided by the interval 12. Next, as shown in FIG. 7, the transparent layer 8a is uniformly heated and melted to form the microlenses 8 at intervals 12, and then cured by heating.

Next, the shapes of the transparent layer 8a before and after forming the microlenses 8 will be described. FIG. 8A is a plan view of the pattern of the transparent layer after exposure and development, and FIG. 8B is a plan view of the microlens after heating. As shown in FIG. 8 (a), a transparent layer 8a is formed by spin-coating a lens resin material, and immediately after exposure and development, a rectangular pattern is formed faithfully on the mask 9, and the interval 12 is also as designed. However, after the transparent layer 8a is heated and melted, generally, FIG.
Each side swells outward as shown in FIG.

[0007]

However, in the above-mentioned conventional structure, the distance 12 is required when the pattern of the transparent layer 8a is formed.
When the width is reduced, the adjacent transparent layer 8a comes into contact when heated and melted, and the completed microlens 9 is deformed.

In order to solve this problem, the interval 12 in FIG. 8A must be widened in consideration of the expansion of the transparent layer 8a during heating and melting. FIG. 9 is a diagram illustrating the relationship between the distance between adjacent microlenses and the relative light sensitivity of the solid-state imaging device. As the distance 12 decreases, the area occupied by the microlenses 9 increases, the amount of light condensed on the photoelectric conversion unit 2 increases, and the relative light sensitivity improves. However, when the interval 12 between the microlenses 9 is reduced to improve the relative light sensitivity, the transparent layer 8a is deformed, and the lens resin materials that have flowed out come into contact with each other and are mixed, so that a desired lens shape cannot be obtained. . When the state further progresses, the lens loses its shape and becomes flat, and the relative light sensitivity rapidly decreases. Such a state is shown in FIGS.

FIG. 10 (a) is a plan view of a transparent layer pattern after exposure and development, FIG. 10 (b) is a cross-sectional view of the transparent layer pattern, and FIG. FIG. 11B is a cross-sectional view of the microlens. Even if the pattern of the transparent layer 8a formed by applying, developing, and exposing the lens resin material shown in FIG. 10A and the cross section shown in FIG. As shown in FIG. 11A, the center of the side of the pattern of the transparent layer 8a swells and the transparent layer 8a
Are in contact with each other, and the shape of the microlens 8 is broken as shown in FIG.

If the distance between the microlenses 9 is increased in order to prevent this phenomenon, the relative light sensitivity cannot be sufficiently increased as shown by point A in FIG.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method for manufacturing a microlens in which a formed microlens is not deformed because an adjacent transparent layer does not contact even if the distance is reduced. .

[0012]

Means for Solving the Problems The method of manufacturing a microlens of the present invention to achieve this object, transparent substrate
Step of forming a layer , and using a mask to convert the transparent layer into a polygon
In addition, the transparent layer has an edge inside the line connecting the adjacent vertices.
It includes a step of processing the turn, and forming a lens the transparent layer pattern by thermally melting, the transparent layer pattern
The shape formed by the line connecting the adjacent vertices and the side is a triangle
And features.

[0013]

According to this structure, when a transparent layer made of a lens resin material is heated and melted to form a microlens, each side of the pattern of the transparent layer is inside the line connecting the adjacent vertices, so that the pattern is adjacent during the melting. There is no contact of the transparent layer. That is, when applied to a solid-state imaging device, the microphone lens is made smaller and performance is sacrificed as in the prior art (see FIG. 9A).
Point) Since it is not necessary to increase the interval, the relative light sensitivity indicated by the point B in FIG. 9 can be obtained.

[0014]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a plan view illustrating a first half of a method of manufacturing a microlens according to an embodiment of the present invention, FIG. 1B is a cross-sectional view illustrating a first half of a method of manufacturing the microlens, and FIG. FIG. 2B is a plan view illustrating a latter half of the manufacturing method, and FIG. 2B is a cross-sectional view illustrating the latter half of the manufacturing method. Each of the substrates illustrates an example of a solid-state imaging device. In these figures, the same parts as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted. The manufacturing process of the solid-state imaging device is basically the same as the manufacturing process shown in FIGS. 4 to 7, except that a mask used for forming a pattern of the lens resin material 8a is different.

First, as shown in FIG. 1A, a transparent layer 8a is formed by spin-coating a lens resin material on an intermediate layer 7 which is the uppermost layer of a semiconductor substrate on which a solid-state imaging device is formed.
Exposure is performed using a mask. The pattern of the transparent layer 8a is exposed using a mask whose vertices are d, e, f, and g, and each side is designed inside a line connecting the adjacent vertices. In this case, an example of a polygonal pattern in which the intermediate point 8b of each side is inside is shown. The cross-sectional shape is as shown in FIG. 1B, and the interval 12 between the transparent layers 8a indicates the interval between the apex of one pattern and the apex of an adjacent pattern. The transparent layer 8a thus formed is heated and melted to form the microlenses 8.

Next, as shown in FIG. 2A, the transparent layer 8a
Is melted and heated, each side spreads to a line connecting each vertex of the pattern. By taking this spread amount into consideration at the time of designing the mask, the interval 12 at the time of completion can be easily controlled. That is, as shown in FIG. 2B, since the interval 12 is secured as designed, the microlens 8 is formed without deformation.

In this embodiment, in the pattern of the transparent layer 8a, an example is shown in which the intermediate point 8b of each side is inside the straight line connecting the adjacent vertices and is octagonal, but is concave in an arc shape. Alternatively, the vicinity of the intermediate point 8b may be a straight line and that part may be dented. Further, the pattern shape of the transparent layer 8a may be a polygon instead of a substantially rectangular shape.

Although the present embodiment has been described with reference to an example in which the substrate is a semiconductor substrate on which a solid-state imaging device is formed, the microlens 8 can be formed in exactly the same manner using a one-dimensional line sensor or a glass substrate.

In this embodiment, an example is described in which all four sides of the pattern of the transparent layer 8a are dented, but the same effect can be obtained by denting only the necessary sides.

[0020]

As described above, the present invention provides a transparent layer pattern
Since the shape formed by the line and the side connecting the adjacent vertices is a triangle, the adjacent transparent layer pattern does not come into contact when melted by heat, so the completed micro lens It is possible to realize an excellent method of manufacturing a microlens in which the shape of the microlens is not deformed and the interval between the microlenses can be narrowed as compared with the related art.

When the method of manufacturing a microlens according to the present invention is applied to a solid-state imaging device, the microlens can be made larger than before, so that more light can be collected and the relative light sensitivity can be improved.

[Brief description of the drawings]

FIG. 1A is a plan view illustrating a first half of a method of manufacturing a microlens according to an embodiment of the present invention. FIG. 1B is a cross-sectional view illustrating a first half of a method of manufacturing the microlens.

2A is a plan view illustrating a latter half of the manufacturing method, and FIG. 2B is a cross-sectional view illustrating a latter half of the manufacturing method.

FIG. 3 is a sectional view of a main part of a conventional solid-state imaging device.

FIG. 4 shows a first example of a conventional microlens manufacturing method.
Sectional view explaining process

FIG. 5 shows a second example of a conventional microlens manufacturing method.
Sectional view explaining process

FIG. 6 shows a third example of a conventional microlens manufacturing method.
Sectional view explaining process

FIG. 7 shows a fourth example of a conventional microlens manufacturing method.
Sectional view explaining process

8A is a plan view of a pattern of a transparent layer after exposure and development, and FIG. 8B is a plan view of a microlens after heating.

FIG. 9 is a diagram illustrating the relationship between the distance between adjacent microlenses and the relative light sensitivity of a solid-state imaging device.

10A is a plan view of a pattern of a transparent layer after exposure and development, and FIG. 10B is a cross-sectional view of the pattern of the transparent layer.

11A is a plan view of a microlens formed by heating and melting a transparent layer, and FIG. 11B is a cross-sectional view of the microlens.

[Explanation of symbols]

 8a Transparent layer 8b Midpoint (at least part of side) d, e, f, g Vertex

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 27/14 G02B 3/00 H04N 5/335

Claims (2)

(57) [Claims] And 1. A process of forming a transparent layer on the substrate, the mass
Connect the transparent layer with a polygon and adjacent vertices
Process of processing into a transparent layer pattern with sides inside the line
When, the transparent layer pattern and forming a lens by thermal melting, the adjacent vertices of the transparent layer pattern
A method for manufacturing a microlens , wherein a shape formed by a connecting line and the side is a triangle. 2. at least, a step of forming a transparent layer on a semiconductor substrate and is formed transfer section for transferring charges generated in the photoelectric conversion portion and the photoelectric conversion unit, a mask
Use the transparent layer as a line connecting polygons and adjacent vertices.
Process into a transparent layer pattern with sides inside
The transparent layer pattern and forming a lens by thermal melting, connecting the adjacent vertices of the transparent layer pattern
A method for manufacturing a semiconductor device, wherein a shape formed by a line and the side is a triangle .