National University of Singapore

Jacob C H Phang

Daniel S H Chan

Yong Yu Liu

John Thong

Sivaramakrishna Kolachina

Chin Jiann Min

Wong Wai Kin

A mechanical scanning stage for high speed image acquisition in a focused beam system. The mechanical scanning stage preferably is a combination of four stages. A first stage provides linear motion. A second stage, above the first stage, provides rotational positioning. A third stage above the rotational stage is moveable in a first linear direction, and the fourth stage above the third stage is positionable in a second linear direction orthogonal to the first direction. The four stages are responsive to input from a controller programmed with a polar coordinate pixel addressing method, for positioning a specimen mounted on the mechanical stage to allow an applied static focus beam to irradiate selected areas of interest, thereby imaged by collecting signals from the specimen using a polar coordinate pixel addressing method.

Rotational stage for high speed, large area scanning in focused beam systems

Selective deposition of a particle beam based on charging characteristics of a sample

An improved method of performing optical beam induced current imaging of semiconductor junctions. According to the method, a single wired contact to an integrated circuit (for example through use of a conventional conductive probe) is made at a point that makes electrical contact to a first side of a junction to be analyzed. A first line connects the wired contact to an amplifier, and a second line carries return current from the amplifier to a ground connection. A capacitive return connection is then used to couple return current from a second side of the junction to ground. The actual value of capacitance in the return connection is not of fundamental importance in the practice of the invention, but generally larger capacitance values are preferred and allow increased induced current flow. An increase in the optical beam power also results in more induced current being generated. This causes a faster decay and results in a better signal-to-noise ratio at a higher scanning beam rate. With the connections described above to the amplifier and the processing circuitry, a pulsed particle or optical beam is applied to the junction. In response to the pulsed beam, the junction generates a corresponding pulse of induced current. Since the current in response to the pulsed beam has an alternating current component, it passes through the capacitive junction return connection as well as through the single wired contact to the amplifier. The amplifier outputs a magnified replica of the current which is then analyzed by the processing circuit to provide a useful form of data for analysis of the junction.

Pulsed single contact optical beam induced current analysis of integrated circuits

Growing community of inventors

Singapore, Singapore

Jacob C H Phang