Iftekhar Ibne Basith

Low-Contact Resistance Probe Card Using MEMS Technology

Multichannel die probing increases test speed and lowers the overall cost of testing. A new high-density wafer probe card based on MEMS technology is presented in this paper. MEMS-based microtest-channels have been designed to establish high-speed low-resistance connectivity between the die-under-test and the tester at the wafer level. The proposed test scheme can be used to probe fine pitch pads and interconnects of a new generation of 3-D integrated circuits. The proposed MEMS probe, which is fabricated with two masks, supports \(10^{6}\) lifetime touchdowns. Measurement results using a prototype indicate that the proposed architecture can be used to conduct manufacturing tests up to 38.6 GHz with less than -1-dB insertion loss while maintaining 11.4-m\(\Omega \) contact resistance. The measured return loss of the probe at 39.6 GHz is -12.05 dB.

A test probe for TSV using resonant inductive coupling

A contactless TSV probe based on the principle of resonant inductive coupling is presented in this work. The proposed scheme allows TSV data observation up to 2Gbps when the probe and TSV are 15μm apart.

Improved bus-shift coding for low-power I/O

In low-power VLSI design good amount of power can be saved by using coding scheme such as Bus-Invert (BI). Such a coding scheme looks at successive words on a data bus and applies transformation to minimize the number of transitions. In this paper we propose Bus-Shift (BS) coding scheme that circularly shifts the data to minimize transitions. Power saving of BI is poor on average cases, and even that deteriorates with wider bus width. In comparison the proposed BS scheme performs better in both maximum and average cases. For wide bus the savings from BS gets slightly worse, but still performs better than BI. Simulation results show a saving margin of 14% in average cases for a 32 bit bus. Comparison is also made with Shift-Invert (SINV), another reported coding scheme. An implementation of BS in Cadence is presented.

A MEMS based device interface board

At gigahertz frequency range, performance degradation of the device interface board increases the yield loss and the cost of manufacturing. In this poster a MEMS based solution is proposed to design a Device Interface Board (DIB) supporting high-speed connectivity between the device under test and the tester. Simulation results indicate that the proposed scheme can operate up to 50 GHz without considerable signal integrity degradation.

Contactless Test Access Mechanism for TSV-Based 3-D ICs Utilizing Capacitive Coupling

Through silicon via (TSV) is considered an enabling technology for 3-D integrated circuit (IC) integration. Testing 3-D ICs with multiple stacked dies is a challenging task. Probing a TSV for the purpose of testing with conventional wafer probes can undermine its physical integrity. In this paper, a contactless TSV probing method using capacitive coupling is presented. The proposed solution eliminates the risks of direct TSV probing and supports the high-density and fine-pitch requirements for TSV probing. 3-D full-wave simulations indicate that a strong electric field is formed between the probe and the TSV when the distance between them falls below 5 μm. The measurement results on a prototype fabricated with CMOS 65-nm technology show that the proposed TSV probing scheme presents a -55-dB insertion loss at 1-GHz frequency. The probe can be used up to a data rate of 5 Gbits/s while maintaining higher than 35-dB signal-to-noise ratio.

Built-In Self-Test for Capacitive MEMS Using a Charge Control Technique

A new Built-in Self-Test (BIST) method for capacitive Micro-Electrical-Mechanical System (MEMS) devices using charge-control method has been developed in which the Device Under Test (DUT) is stimulated through current sources. The DUT output signals are first converted to time domain intervals and then measured through a precision Time-to-Digital converter (TDC). The proposed BIST scheme supports self-calibration and produces robust results under process, supply and temperature variations. Simulation results indicate that this method can successfully detect minor structural defects altering the MEMS nominal capacitance by 70af.

Charge-Controlled Readout and BIST Circuit for MEMS Sensors

In this paper, we present a new readout circuit with an integrated built-in self-test (BIST) structure for capacitive microelectromechanical system (MEMS). In the proposed solution, instead of commonly used voltage control signals to test the device, charge-controlled stimuli are employed to cover a wider range of structural defects. The proposed test solution eliminates the risk of structural collapse in the test phase for gap-varying parallel-plate MEMS devices. Measurement results using a prototype fabricated in TSMC 65-nm CMOS technology indicate that the proposed BIST scheme can successfully detect minor structural defects altering MEMS nominal capacitance.

Comparative study on bus-coding schemes and improvement on SINV coding

Reducing the number of transitions between successive words is an efficient way to reduce the power consumption. Several coding schemes like Bus-Invert (BI), Bus-Shift (BS) and Shift-Invert (SINV) have been used in order to minimize power. In this paper, an improved Circular Shift-Invert (CSINV) coding scheme is proposed where the circular shifting of data is considered instead of just a 1-bit left or right shift. The proposed scheme in comparison to other reported schemes performs better in saving power and does not need additional control bits than BS. Simulation results in the Cadence environment show an average power saving of 5% in comparison with BI and regular SINV schemes for higher bus widths.

Contactless detection of faulty TSV in 3D IC via capacitive coupling

3D IC using Through Silicon Via (TSV) is a promising technology for next generation of integrated circuits. Manufacturing TSV defects like voids and pinholes have to be detected at the test phase to ensure fault free ICs. In this paper a contactless probe utilizing capacitive coupling is presented. The proposed method eliminates the impact of direct probing on TSV and supports the high-density and fine-pitch requirements for TSV probing. 3D full-wave simulations using HFSS and circuit level simulation using ADS show that common TSV defects such as voids and pinholes can be detected successfully.