Method of planar imaging on semiconductor chips using focused ion beam
View Patent ↗A method of planar imaging on semiconductor chips using focused ion beam includes the initial step of disposing at least a positioning symbol to designate a testing area. A metal membrane is positioned on the testing area. The testing chip is trimmed to form a first testing chip. A blind opening is cut proximate to the testing area on the first testing chip forms a second testing chip. The second testing chip is mounted on an inclinable platform. The mounted second testing chip is rotated with the inclinable platform. Ion beams are emitted into the opening at an angle of inclination. Ion beams are emitted in the direction of the incident ray to form planar images of different depths parallel to the metal membrane on the testing area.
1. A method of planar imaging on semiconductor chips using focused ion beam (FIB), comprising the steps of:
(A) disposing at least a positioning symbol on a semiconductor chip to designate a testing area thereon;
(B) disposing a metal membrane on the testing area;
(C) trimming the testing chip to form a first testing chip;
(D) cutting a blind opening proximate the testing area on the first testing chip along a border of the metal membrane to form a second testing chip, wherein the base surface of the opening is substantially planar, wherein the at least one positioning symbol is positioned proximate a border of the metal membrane away from the opening;
(E) erecting the second testing chip on an inclinable platform with the opening facing upward;
(F) rotating the erected second testing chip with the inclinable platform so that the normal vector of the metal membrane is perpendicular to the incident direction of the FIB, wherein a non-zero included angle is formed between the normal vector of the base surface of the opening and the incident direction of the FIB, thereby allowing ion beams from the FIB to emit into the opening in an angle of inclination; and
(G) emitting ion beams in the direction of the incident ray to form planar images of different depths parallel to the metal membrane on the testing area.
2. The method of claim 1 , wherein the method of designating a positioning symbol on the chip surface in step (A) includes using laser, FIB or other methods.
3. The method of claim 1 , wherein the metal membrane is made of platinum or chemical compounds thereof.
4. The method of claim 1 , wherein the step (C) includes using a dicing tool for trimming the chip.
5. The method according to claim 4 , wherein the width of the first testing chip in step (C) is four millimeters.
6. The method of claim 1 , wherein the step (D) includes using the FIB to cut the first testing chip to form the second testing chip.
7. The method according to claim 6 , wherein the FIB in the step (D) utilizes at least one positioning symbol to locate a position about to be cut.
8. The method of claim 1 , wherein the step (D) includes the base surface of the opening which adjoins the border of the metal membrane.
9. The method according to claim 8 , wherein the step (E) includes stabilizing the second testing chip on the inclinable platform by means of clamping or gluing.
10. The method of claim 1 , wherein the step (F) includes adjusting the angle of inclination to six to eight degree.