TWI384263B - Color filter by copper and silver film and method for making same - Google Patents

Description

Copper-silver film color filter and preparation method

The invention relates to a copper silver thin film color filter and a preparation method thereof.

Color filters are components required for color image processing, such as those used in image sensors. The prior art produces color filters from a photoresist-like material coating. In the application publication of U.S. Patent No. 2006/0180886, a color filter made of a silver film according to the Fabry-Perot resonance mode is disclosed. The so-called Fabry-Perot resonance system is shown in Fig. 1. Between the two layers of good reflectors, the incident light will continuously reflect, and only a specific resonant frequency can penetrate, thus having a filtering effect. However, the silver deposition process has not yet been integrated into the general semiconductor wafer process. The silver film structure described in the US Patent No. 2006/0180886 is still difficult to implement in actual production.

The present invention provides a novel color filter structure and method for making a Fabry-Perot resonant color filter fabricated in a general semiconductor wafer process.

A first object of the present invention is to provide a copper silver thin film color filter.

A second object of the present invention is to provide a method for producing the above-described copper-silver film color filter.

In order to achieve the above object, in one aspect of the present invention, a copper-silver film color filter comprising: a lower copper layer; a lower silver layer deposited on the lower copper layer; and a lower silver layer deposited thereon is provided. a medium; an upper copper layer deposited on the medium; and an upper silver layer deposited on the upper copper layer.

In another aspect, the present invention provides a method for preparing a copper-silver film color filter comprising: providing a lower copper layer as a seed layer; depositing a lower silver layer on the lower copper layer by electroplating; depositing on the lower silver layer a medium; depositing an upper copper layer on the medium as a seed layer; and depositing an upper silver layer on the upper copper layer by electroplating. The copper seed layer can be formed, for example, by PVD evaporation.

In the above copper-silver film color filter and method, the dielectric material may be, for example, tantalum nitride, hafnium oxynitride, or tantalum carbide.

In the above copper-silver film color filter and method, the preferred thickness range of the copper layer is: 0 nm < copper layer thickness .

In the above copper-silver film color filter and the preparation method, the thickness of the silver layer is preferably less than 30 nm.

The purpose, technical content, features and effects achieved by the present invention will be more readily understood by the detailed description of the embodiments.

The drawings in the present invention are schematic and are mainly intended to represent the process steps and the relationship between the layers, and the shapes, thicknesses, and widths are not drawn to scale.

Figure 2 illustrates a first embodiment of the present invention. One of the features of the present invention is that a copper layer 11 is provided first, and a silver layer 12 is deposited on the copper layer 11. The copper layer 11 can be an extremely thin layer of seed, even without being very dense. The method of forming the copper seed layer is, for example, PVD evaporation, which is a mature standard technology in the current semiconductor process in which copper is an interconnect. After the copper seed layer is formed, a silver layer 12 can be deposited on the copper layer 11 using electroplating techniques. The deposition of the silver layer 12 can be carried out by electroplating in a suitable electrolyte (for example, an aqueous solution of nitric acid) using the silver rod 21 as an anode and the wafer 22 as a cathode as shown in FIG.

The medium 13 between the lower silver layer 12 and the upper copper layer 11 can be selected in accordance with a semiconductor process, and is preferably a material having a barrier function to copper, such as tantalum nitride, hafnium oxynitride, or tantalum carbide. . The deposition processes for these materials are currently mature technologies such as CVD chemical vapor deposition.

The Fabry-Perot color filter consisting of "the lower copper layer 11 + the lower silver layer 12 + the medium 13 + the upper copper layer 11 + the upper silver layer 12 " can be fabricated separately into components or fabricated in a semiconductor or MEMS wafer. position. When it is fabricated in a wafer, as shown, it can be fabricated between the upper and lower structural layers 14 in accordance with a process, such as tantalum nitride, hafnium oxynitride, or tantalum carbide.

Figure 4 shows the effect of the thickness of the copper layer on the transmittance of the composite copper-silver film composed of "copper layer + silver layer". Preferably, the thickness of the silver layer is preferably less than 30 nanometers (nm). This figure shows the light transmittance of the overall composite copper-silver film when the thickness of the silver layer is fixed to 28 nm and the thickness of the copper layer is 0 nm, 10 nm, and 20 nm, respectively. It can be clearly seen from the figure that the lower the thickness of the copper layer, the better, but as mentioned above, the pure silver layer cannot be integrated into the current semiconductor wafer process, so the thickness of the copper layer is not suitable to be zero, and the range thereof is preferably 0 nm<copper layer thickness .

Figure 5 shows a composite copper-silver film composed of "copper layer + silver layer", the total thickness of which is fixed to 28 nm, and the thickness of the copper layer is 0 nm, 5 nm, 10 nm, 15 nm, and 20 nm, respectively. Penetration rate. As can be seen from the figure, the lower the thickness of the copper layer, the better.

The present invention has been described with reference to the preferred embodiments thereof, and the present invention is not intended to limit the scope of the present invention. For those skilled in the art, various equivalent changes can be immediately considered within the spirit of the invention. For example, other materials may be added between the structural layers shown without affecting the basic spirit of the present invention. For example, the medium 13 may also be a composite layer of two or more materials. Equivalent changes or modifications of the concept and spirit of the invention are intended to be included within the scope of the invention.

11. . . Copper layer

12. . . Silver layer

13. . . medium

14. . . Structural layer

twenty one. . . Silver rod

twenty two. . . Wafer

Figure 1 shows a cross-sectional structure of the prior art.

Figure 2 shows an embodiment of the invention.

Figure 3 shows the deposition of silver.

Figures 4 and 5 show the light transmittance of a composite copper-silver film.

11. . . Copper layer

12. . . Silver layer

13. . . medium

14. . . Structural layer

Claims (7)

A copper-silver film color filter comprising: a lower copper layer, which is substantially composed of copper, and the thickness of the lower copper layer ranges from 0 nm to the thickness of the copper layer 20 nm; a lower silver layer deposited on the underlying copper layer, consisting essentially of silver; a medium deposited on the underlying silver layer, wherein the dielectric material is tantalum nitride, hafnium oxynitride, or tantalum carbide; deposited in the medium The upper copper layer is substantially composed of copper, and the thickness of the upper copper layer ranges from 0 nm to the thickness of the copper layer. 20 nm; and an upper silver layer deposited on the upper copper layer, which consists essentially of silver. The copper-silver film color filter according to claim 1, further comprising a structural layer under the lower copper layer, the structural layer material being tantalum nitride, hafnium oxynitride, or tantalum carbide. The copper-silver film color filter according to claim 1, further comprising a structural layer on the upper silver layer, the structural layer material being tantalum nitride, hafnium oxynitride, or tantalum carbide. The copper-silver film color filter of claim 1, wherein the thickness of the lower silver layer is less than 30 nm; and the thickness of the upper silver layer is less than 30 nm. A method for preparing a copper-silver film color filter, comprising: providing a lower copper layer, which is substantially composed of copper, and the thickness of the lower copper layer ranges from 0 nm to the thickness of the copper layer 20 nm, as a seed layer; depositing a lower silver layer on the underlying copper layer by electroplating, which consists essentially of silver; depositing a medium on the underlying silver layer, wherein the dielectric material is tantalum nitride, hafnium oxynitride, or carbonization矽; depositing an upper copper layer on the medium, which is substantially composed of copper, and the thickness of the upper copper layer ranges from 0 nm to the thickness of the copper layer 20 nm as a seed layer; and an upper silver layer deposited on the upper copper layer by electroplating, which consists essentially of silver. The method for producing a copper-silver film color filter according to claim 5, wherein the lower copper layer and the upper copper layer are formed by PVD evaporation. The method for preparing a copper-silver film color filter according to claim 5, wherein the thickness of the lower silver layer is less than 30 nm; and the thickness of the upper silver layer is less than 30 nm.