Method for processing device wafer

1 . A method for processing a device wafer, in which a device layer, the device layer constituting devices, is stacked on a base material and the devices are formed, respectively, in regions defined by a plurality of intersecting streets on a front surface of the base material, the method comprising:

a first step of dividing the device layer along the streets, wherein metal structures are formed in each of the streets;

a second step of dividing the base material by plasma etching along the streets; and

a third step of, before performing at least the second step, forming half-cut grooves by a cutting blade or a laser beam in the base material along the streets, respectively, from one of a side of a front surface or a side of a back surface of the device wafer, wherein

the third step and the second step are performed from the side of the same surface of the device wafer.

2 . The method for processing a device wafer according to claim 1 , wherein

a mask is formed on the metal structures and the device layer,

in the first step, two grooves are formed along each street and through the mask, so that the two grooves divide the device layer and flank the metal structures, and

after the first step has been performed, the third step is performed, and the second step is then performed.

3 . The method for processing a device wafer according to claim 2 , wherein,

in the third step, the base material is removed along with the metal structures along each street from the side of the front surface of the device wafer, so that the half-cut groove is formed in the base material and a remaining portion of the base material is formed below the half-cut groove, and

in the second step, a plasma gas is supplied from the side of the front surface of the device wafer, so that plasma etching is performed on the remaining portion and processing debris occurred upon the formation of the half-cut groove in the third step is removed.

4 . The method for processing a device wafer according to claim 2 , wherein, in the third step, the half-cut groove is formed in the base material from the side of the back surface of the device wafer, and a remaining portion of the base material is formed below the half-cut portion, and

in the second step, a plasma gas is supplied from the side of the back surface of the device wafer, so that plasma etching is performed on the remaining portion and processing debris occurred upon the formation of the half-cut groove in the third step is removed.

5 . The method for processing a device wafer according to claim 1 , further comprising attaching each of the metal structures to a device portion of the device layer in each of the streets.

6 . A method for processing a device wafer, in which a device layer, the device layer constituting devices, is stacked on a base material and the devices are formed, respectively, in regions defined by a plurality of intersecting streets on a front surface of the base material, the method comprising:

a first step of dividing the device layer by plasma etching along the streets, wherein metal structures are formed in each of the streets;

a second step of dividing the base material by plasma etching along the streets; and

a third step of, before performing at least the second step, forming half-cut grooves by a cutting blade or a laser beam in the base material along the streets, respectively, from one of a side of a front surface or a side of a back surface of the device wafer, wherein

the third step and the second step are performed from the side of the same surface of the device wafer.

7 . The method for processing a device wafer according to claim 6 , wherein

metal structures are formed in each of the streets, wherein a mask is formed on the metal structures and the device layer,

in the first step, two grooves are formed along each street and through the mask, so that the two grooves divide the device layer and flank the metal structures, and

after the first step has been performed, the third step is performed, and the second step is then performed.

8 . The method for processing a device wafer according to claim 7 , wherein,

in the third step, the base material is removed along with the metal structures along each street from the side of the front surface of the device wafer, so that the half-cut groove is formed in the base material and a remaining portion of the base material is formed below the half-cut groove, and

in the second step, a plasma gas is supplied from the side of the front surface of the device wafer, so that plasma etching is performed on the remaining portion and processing debris occurred upon the formation of the half-cut groove in the third step is removed.

9 . The method for processing a device wafer according to claim 7 , wherein,

in the third step, the half-cut groove is formed in the base material from the side of the back surface of the device wafer, and a remaining portion of the base material is formed below the half-cut portion, and

in the second step, a plasma gas is supplied from the side of the back surface of the device wafer, so that plasma etching is performed on the remaining portion and processing debris occurred upon the formation of the half-cut groove in the third step is removed.

10 . The method for processing a device wafer according to claim 6 , further comprising attaching each of the metal structures to a device portion of the device layer in each of the streets.