# US 8,785,298 B2 · Method of singulating a thin semiconductor wafer

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- Number: US 8,785,298 B2
- Document ID: US8785298B2
- Status: Granted
- Kind: B2
- Application number: 13/796,384
- Filed: 2013-03-12
- Published: 2013-09-19
- Granted: 2014-07-22
- Earliest claimed: 2012-03-16
- Assignees: Asm Technology Singapore Pte Ltd
- Applicants: Advanced Laser SeparationInternational (ALSI) N.V.
- Inventors: Karel Maykel Richard Van der Stam; Rogier Evertsen; Guido Martinus Henricus Knippels
- Web page: https://patentgrep.com/patent/US8785298B2

## CPC

- H10P 54/00: Cutting or separating of wafers, substrates or parts of devices
- B23K 26/0624: {using ultrashort pulses, i.e. pulses of 1 ns or less}
- B23K 26/364: for making a groove or trench, e.g. for scribing a break initiation groove
- B23K 26/40: taking account of the properties of the material involved
- B23K 2101/40: Semiconductor devices
- B23K 2103/50: {Inorganic materials other than metals or composite materials}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM

## Abstract

A method of singulating a semiconductor wafer having two surfaces separated by a thickness T<200 μm includes partitioning it along a network of scribelines on one side. The other side is secured to an elastic foil, which is clamped to a wafer table. A radiative scribing tool is used to produce at least one laser beam having a pulse duration P≦75 ps, and causing the laser beam to scan along each of the scribelines so as to create a scribe with a depth D<T, thereby leaving the second surface intact. The foil is laterally stretched to sever the second major surface along the path of the scribes. In an embodiment, P<CPP, the Time Constant of phonon-phonon coupling in the wafer at the location of incidence of the laser beam.

## Claims

### Claim 1

A method of singulating a semiconductor wafer by partitioning it along a network of scribelines, the wafer having two substantially parallel major surfaces that are separated from one another by a thickness T<200 μm, said scribelines extending along a first of said major surfaces, comprising:
adhering the second major surface of the wafer to an elastic foil, which is clamped to a wafer table so as to present the first major surface to a radiative scribing tool;
using the radiative scribing tool to produce at least one pulsed laser beam having a pulse duration P≦75 ps;
causing said laser beam to scan along each of said scribelines so as to create a radiative scribe with a depth D<T, thereby leaving the second major surface intact; and
laterally stretching said foil so as to sever the second major surface along the path of said radiative scribes.

### Claim 2 (depends on 1)

A method according to claim 1, wherein P<CPP, in which CPP is the Time Constant of phonon-phonon coupling in the wafer at the location of incidence of the laser beam.

### Claim 3 (depends on 2)

A method according to claim 2, wherein P<CEP, in which CEP is the Time Constant of electron-phonon coupling in the wafer at the location of incidence of the laser beam.

### Claim 4 (depends on 1)

A method according to claim 1, wherein the difference F=T−D is in the range 5-50 μm.

### Claim 5 (depends on 4)

A method according to claim 4, wherein the difference F=T−D is in the range 10-30 μm.

### Claim 6 (depends on 1)

A method according to claim 1, wherein:
T is in the range 20-200 μm and P is in the range 0.1-55 ps.

### Claim 7 (depends on 6)

A method as in claim 6, wherein T is in the range 30-150 μm, and P is in the range 1-20 ps.

### Claim 8 (depends on 7)

A method as in claim 7, wherein T is in the range 40-100 μm, and P is in the range 5-15 ps.

### Claim 9 (depends on 1)

A method according to claim 1, wherein, for a given scribeline, said radiative scribe is created as a cumulative result of a plurality of process steps, each step entailing a single scan of the laser along said scribeline.

### Claim 10

A system for singulating a semiconductor wafer by partitioning it along a network of scribelines, the wafer having two substantially parallel major surfaces that are separated from one another by a thickness T<200 μm, said scribelines extending along a first of said major surfaces, the wafer being adhered to an elastic foil on a second of said major surfaces, comprising:
a radiative scribing tool including a laser configured and arranged to generate a pulsed laser beam having a pulse duration P≦75 ps;
a wafer table, constructed and arranged to hold the wafer such that the first major surface is exposed to the radiative scribing tool;
an actuator, configured and arranged to cause the laser beam to relatively scan along each of said scribelines so as to create a radiative scribe with a depth D<T, thereby leaving the second major surface intact; and
actuators constructed and arranged to laterally stretch said foil so as to sever the second major surface along the path of said radiative scribes.