1. Field of the Invention
The present invention relates to a photoelectric converter device in which the wavelength characteristic is adjusted by means of a wavelength filter, and to a method for manufacturing the photoelectric converter device.
2. Description of the Related Art
In recent years, a chip size package (CSP) comprising wiring lines drawn out from a side surface of an element is widely used to miniaturize devices such as photoelectric converter devices which include photoelectric converter elements.
FIGS. 12A and 12B illustrate top and bottom external views, respectively, of a semiconductor integrated device configured as a CSP. The CSP is constituted by adhering an upper support member 14 and a lower support member 16 on upper and lower surfaces, respectively, of a semiconductor chip 10 by means of resin layers 12 composed of epoxy or the like. External wiring lines 18 are drawn out from side surfaces of the semiconductor chip 10 sealed between the upper support member 14 and the lower support member 16. The external wiring lines 18 are connected to ball-shaped terminals 20 provided on the bottom side of the CSP.
FIG. 13 shows a cross-sectional view of a conventional photoelectric converter device including photoelectric converter elements configured as a CSP. The semiconductor chip 10 is formed as a lamination of a semiconductor substrate 10a having photoelectric converter elements formed on its upper surface, color filters 10b and 10c disposed to at least partially cover the photoelectric converter elements for absorbing or reflecting light in predetermined wavelength regions, and a planarization film 10d for planarizing surface unevenness. The upper support member 14 is adhered to the upper side of the semiconductor chip 10 via a resin layer 12, while the lower support member 16 is adhered to the lower side of the semiconductor chip 10 via another resin layer 12. With this arrangement, by employing a light-transmitting substrate made of glass or the like as the upper support member 14, external light can be introduced into the photoelectric converter elements formed on the upper side of the semiconductor chip 10.
In the above-described arrangement, each of the color filters, which is a visible light filter for permitting transmission of visible light, is composed of a filter material which mainly permits transmission of red (R), green (G), or blue (B) wavelength region. FIG. 14 illustrates sensitivity characteristics of a photoelectric converter element obtained when using red (R), green (G), and blue (B) color filters that are typically employed. A typical color filter exhibits a relatively high transmittance in the infrared region exceeding 700 nm in addition to in a wavelength region of the corresponding color. Further, a silicon photoelectric converter element shows responses in the infrared region exceeding 700 nm. In FIG. 14, wavelengths of incident light into the filters are given on the horizontal axis, while sensitivity levels obtained at various wavelengths are given on the vertical axis. In FIG. 14, line A denotes a characteristic obtained when using a color filter corresponding to the red (R) wavelength region, line B denotes a characteristic obtained when using a color filter corresponding to the green (G) wavelength region, and line C denotes a characteristic obtained when using a color filter corresponding to the blue (B) wavelength region. Furthermore, line D denotes a typical example sensitivity characteristic, with respect to various wavelengths, of a photoelectric converter element (without color filters) formed on a silicon substrate.
As can be seen, when a color image is captured using these color filters, the obtained output signals for the respective colors are influenced by noise generated due to infrared components included in the incident light. Consequently, when those output signals are combined to produce an image, correct white balance of the image cannot be achieved.
In order to avoid the above-described problem, a structure as shown in FIG. 15 is conventionally used. In FIG. 15, an infrared cut-off filter 102 is arranged so as to cover the incident surface of a photoelectric converter device 100 configured as a CSP, while a lens 104 is provided to direct incident light into the photoelectric converter elements.
As can be seen in FIG. 15, the structure including the infrared cut-off filter 102 provided over the photoelectric converter device 100 is disadvantageous in that the overall device size becomes very large.
Another disadvantage is that the cost of the infrared cut-off filter 102 is very high because the filter 102 is fabricated by laminating many layers of infrared-absorbing materials having different characteristics on a glass substrate. Use of the infrared cut-off filter 102 is one significant factor which increases the fabrication costs of the photoelectric converter device 100. Furthermore, when employing a configuration in which the infrared-absorbing films are formed on the surface of the glass substrate, the infrared cut-off filter 102 often becomes damaged due to handling during the fabrication process. Moreover, the difference in contraction ratio between the glass substrate and the infrared-absorbing films may result in curving and partial peeling of the infrared cut-off filter 102.