Semiconductor device

1. A semiconductor device comprising:

a first memory chip including a first interconnect which conducts a signal between a top surface and a back surface of the first memory chip;

a first bump provided on the top surface of the first memory chip and electrically connected to the first interconnect at the top surface side;

a second bump provided on the back surface of the first memory chip and electrically connected to the first interconnect at the back surface side; and

an interface chip stacked with the first memory chip and electrically connected to the first memory chip via the second bump,

wherein the interface chip includes:

a first FIFO receiving data from the first memory chip via the second bump;

second to fifth FIFOs receiving the data from the first FIFO; and

first to fourth pads outputting the data from the second to fifth FIFOs, respectively, and

wherein in the interface chip,

the second FIFO and the third FIFO are provided along a first direction,

the fourth FIFO and the fifth FIFO are provided along the first direction, and

the first FIFO is provided between a set of the second FIFO and the third FIFO and a set of the fourth FIFO and the fifth FIFO, in a second direction different from the first direction.

2. The device according to claim 1 , wherein

the first pad and the second pad are provided along the first direction on a first edge portion of a top surface of the interface chip,

the third pad and the fourth pad are provided along the first direction on a second edge portion of the top surface of the interface chip, and

the first edge portion faces the second edge portion in the second direction.

3. The device according to claim 1 , wherein the first to fourth pads are located on a top surface of the interface chip in the vicinity of the second to fifth FIFOs, respectively.

4. The device according to claim 3 , wherein

the first pad and the second pad are provided along the first direction on the interface chip,

the third pad and the fourth pad are provided along the first direction the top surface of the interface chip, and

the first to fifth FIFOs are provided between a set of the first pad and the second pad and a set of the third pad and the fourth pad, in the second direction.

5. The device according to claim 3 , wherein a first distance between the second FIFO and the first pad is smaller in physical layout than a distance between the second FIFO and the second pad, a distance between the second FIFO and the third pad, and a distance between the second FIFO and the fourth pad.

6. The device according to claim 5 , wherein

a second distance between the third FIFO and the second pad is smaller in physical layout than a distance between the third FIFO and the first pad, a distance between the third FIFO and the third pad, and a distance between the third FIFO and the fourth pad,

a third distance between the fourth FIFO and the third pad is smaller in physical layout than a distance between the fourth FIFO and the first pad, a distance between the fourth FIFO and the second pad, and a distance between the fourth FIFO and the fourth pad, and

a fourth distance between the fifth FIFO and the fourth pad is smaller in physical layout than a distance between the fifth FIFO and the first pad, a distance between the fifth FIFO and the second pad, and a distance between the fifth FIFO and the third pad.

7. The device according to claim 1 , wherein the first FIFO is provided at a center portion in the interface chip.

8. The device according to claim 1 , wherein the first FIFO receives the data from the first memory chip and outputs the data in synchronism with a first clock.

9. The device according to claim 8 , wherein

data output from one of the first to fourth pads is synchronized with a second clock signal, and

the semiconductor device further comprises a frequency division circuit frequency-dividing the second clock signal and generating the first clock signal.

10. The device according to claim 9 , further comprising a multiplexer disposed between the first FIFO and the one of the first to fourth pads, the multiplexer outputting the data at the rise and fall of the second clock signal.

11. The device according to claim 8 , further comprising a second memory chip which is disposed on the first memory chip and includes a second interconnect which conducts a signal between a top surface and a back surface of the second memory chip, the second interconnect being connected to the first interconnect by the first bump, wherein

data outputted from the second memory chip is inputted to the first FIFO disposed on the interface chip through the second interconnect, the first bump, the first interconnect, and the second bump, and

the first FIFO receives the data from the second memory chip and outputs the data in synchronism with the first clock.

12. The device according to claim 11 , wherein a bus width between the second memory chip and the interface chip is the same as a bus width between the second bump and the first FIFO in the interface chip.

13. The device according to claim 1 , further comprising a second memory chip which is disposed on the first memory chip and includes a second interconnect which conducts a signal between a top surface and a back surface of the second memory chip, the second interconnect being connected to the first interconnect by the first bump, wherein

data outputted from the second memory chip is inputted to the first FIFO disposed on the interface chip through the second interconnect, the first bump, the first interconnect, and the second bump, and

the first FIFO receives the data from the second memory chip and outputs the data in synchronism with a first clock.

14. The device according to claim 1 , wherein a bus width between the first memory chip and the interface chip is the same as a bus width between the second bump and the first FIFO in the interface chip.

15. The semiconductor device according to claim 1 , wherein the first memory chip includes a memory circuit which outputs the data.