Digging Into 'DIGIC 4' Image Processor (2)
Continued from Digging Into 'DIGIC 4' Image Processor (1).
After tearing down the Ixy Digital 920IS, Canon's digital camera equipped with the DIGIC 4 image processor, we started to examine the processor. The actual examination was carried out by Van Partners Corp.
The DIGIC 4 has a structure called "PoP," which is composed of two stacked semiconductor packages. We looked inside the packages using an X-ray machine and discovered that there were two chips in the upper package.
So, we removed the upper package with a chemical solution and exposed the chips.
There were two types of memory manufactured by Samsung Electronics Co Ltd. The upper chip was 64-Mbit NOR flash memory, the "K8P6415UQB," which measured 6,040 x 3,910 x 80μm. The lower one was 512-Mbit SDRAM, the "K4X51323PE," whose dimensions were 8,220 x 7,545 x 110μm.
Next, we started to remove the lower package of the PoP. The package, which can be regarded as the main unit of the DIGIC 4, contained a chip measuring 7,980 x 6,370 x 105μm.
We took out exposed wiring layers and examined the circuit block.
The number of gates in the logic block was approximately 18 million.
The total amount of memory was approximately 2.96 Mbits.
We also checked the total number of wiring layers and the gate length using a scanning electron microscope (SEM). The wiring on the seventh (highest) layer was made of aluminum (Al), and the first to sixth layers were made of copper (Cu).
As a result of the measurement of gate length, a rumor in the camera industry was proven true. The DIGIC 4 was designed using 65nm process technology.
In the next article, we will summarize the physical specifications of the DIGIC 4 and compare them with those of the previous version, the DIGIC 3.