Resistor Trimming Research Articles

A thermally optimizing method of thin film resistor trimming with machine learning

This paper proposes a novel trimming method of thin-film resistors dedicated to the power modules. Thin-film resistors are utilized for applications including snubber circuits which avoids unwanted ringing appearing in the output voltage of power transistors. Our previous works have revealed that the applicable voltage of a NiCr thin-film resistor is thermally limited, and then the indispensable trimming process affects the degree of temperature rise in use. In this paper, we first formulate the relationship between the target resistance value and the trim dimensions using machine learning. With the obtained equation, we propose a new trimming method, which enables the trimmed pattern to reduce the variability of the maximum temperature rise. The experimental results show that the proposed trimming method can suppress the estimated range of the maximum temperature from 619K to 179K.

Software Engineering of Resistive Elements Electrophysical Parameters Simulation in the Process of Laser Trimming

This study continues a series of papers covering the R&D of circuit simulators embedded into manufacturing equipment for the laser trimming of film and foil resistors intended to improve the final product’s performance and reduce process costs. Our paper describes the development of the ResModel laser trimming simulation software. Various types of trims and their features are presented for a circuit with a dynamic measurement DC source, and the optimal trim configurations are identified. The software can be used to estimate and display resistive element properties during the trimming such as its electrophysical parameters and their trends.

Circuit Simulation of Film Resistor Laser Trimming with a Measuring Voltage Source

This article continues the series of publications that describe in detail the process of development, research, and implementation of circuit modeling and machine vision mechanisms in industrial equipment for laser trimming of resistors in order to obtain products with better characteristics and increase the economic efficiency of the process. A circuit model of the process of laser trimming of film-resistive elements under the action of a measuring voltage source, as well as an algorithm for correcting this model during laser trimming, has been developed. The paper considers the principles of building a circuit model of film resistor cutting. The conductive resistive medium is defined with the component equations and the topology of the circuit model. A method of estimating the electric parameters of a resistor operating in the system with a measuring voltage source is shown. An equation system for the node voltages is defined, and the resistive layer parameters are analyzed as the circuit model structure changes during the cutting process.

Principles and Methods of Forming the Duration of a Pulse Packet for the Electrospark Trimming of Resistors

Principles and Methods of Forming the Duration of a Pulse Packet for the Electrospark Trimming of Resistors

Temperature-Compensated $\beta$ -Multiplier Current Reference Circuit

This brief presents the new simple schematic for the temperature stable current references based on the well-known $\boldsymbol {\beta }$ -multiplier circuit. The proposed reference utilizes only four MOS transistors and two lateral PNP transistors, which are usually available in standard CMOS technologies along with one well resistor. The temperature-compensation technique has a low process dependence and needs no trimming. However, resistor trimming can be used to precisely set the output current value. The circuit implementation of the proposed technique was fabricated in a standard 0.35- ${\mu }\text{m}$ CMOS process to source a 16- ${\mu }\text{A}$ current. The digital calibration circuit allows setting of the output current in 32 100 nA-steps. The proposed current reference achieves the supply sensitivity of several %/V without the use of the external bandgap voltage reference for the supply regulation. The measured temperature coefficient is 105 ppm/°C over the temperature range from 0 to 110 °C.

Effects of high voltage pulse trimming on structural properties of thick-film resistors

Nowadays, compact and reliable electronic devices including up-to-date ceramic micro-electro-mechanical systems require thick-film resistors with significantly reduced dimensions and stable and precise resistance values. For that reason, instead of standard laser trimming method, high voltage pulse trimming of thick-film resistors is being introduced. This method allows controlled and reliable resistance adjustment regardless of resistor position or dimensions and without the presence of cuts. However, it causes irreversible structural changes in the pseudorandom network formed during sintering causing the changes in conducting mechanisms. In this paper results of the experimental investigation of high voltage pulse trimming of thick-film resistors are presented. Obtained results are analyzed and correlations between resistance and low-frequency noise changes and changes in conducting mechanisms in resistors due to high voltage pulse trimming are observed. Sources of measured fluctuations are identified and it is shown that this type of trimming is a valid alternative trimming method to the dominant laser trimming.

Resistor trimming geometry; past, present and future

This paper explores the key developments in thin film resistive trimming geometry for use in the fabrication of discrete precision resistors. Firstly an introduction to the laser trimming process is given with respect to well established trim geometries such as the plunge, 'L' and serpentine cuts. The effect of these trim patterns on key electrical properties of resistance tolerance and temperature co-efficient of resistance (TCR) of the thin films is then discussed before the performance of more recent geometries such as the three-contact and random trim approaches are reviewed. In addition to the properties of the standard trim patterns, the concept of the heat affected zone (HAZ) and ablation energy and the effect of introducing a 'fine' trim in areas of low current density to improve device performance are also studied. It is shown how trimming geometry and laser parameters can be systematically controlled to produce thin film resistors of the required properties for varying applications such as high precision, long term stability and high power pulse performance.

From Laser Marking to Ultra‐Short Pulsed Lasers

AbstractMaterial processing with laser radiation has a long tradition at Bosch. As early as in 1976, the first laser process was established in serial production. The application at that time was trimming of resistors on ceramic multi‐layers. A few years later, in 1981, laser welding started with a first application. Today, it is the most popular welding technology at Bosch with more than 500 laser systems installed. In 1985, laser marking was established for the first time and has found its way into almost every production line today. In the field of laser micro processing, the next step was the introduction of laser soldering in mass production in 1992 (Fig.1). However, the number of installed laser systems is by far lower than in laser marking or welding.

Universal trimming of polymer thick film resistors

Purpose – The purpose of this paper is to study high-voltage interactions in polymer thick-film resistors, namely, polyvinyl chloride (PVC)-graphite thick-film resistors, and their applications in universal trimming of these resistors. Design/methodology/approach – The authors applied high voltages in the form of pulses and impulses of various pulse durations and with different amplitudes to polymer thick-film resistors and observed the variation of resistance of these resistors with high voltages. Findings – The paper finds that high voltages can be used for trimming of polymer thick-film resistors in both directions, i.e. upwards and downwards. Research limitations/implications – The research implication of this paper is that polymer thick-film resistors can be trimmed downwards or upwards practically using this method. Practical implications – The practical implications of this paper is that one can trim the polymer thick-film resistors, namely, PVC–graphite thick-film resistors, in both directions, i.e. upwards and downwards, by using this method. Originality/value – The value of the paper is in showing that high voltages can be used to trim downwards and also upwards in the case of polymer thick-film resistors. This type of trimming is called universal trimming, developed first time for polymer thick-film resistors.

Influence of Fabrication Process Parameters and Material Properties on Process Yield Performance on RF and Microwave Thin Film based Termination Resistors

Ever-rising pressure of improving frequency domain performance of RF and Microwave components to improve the signal integrity as well as to reduce component package size consistently challenge design engineers not only with signal integrity and size constraints, but also the power integrity and thermal constraints concurrently. To achieve excellent signal and power integrity performance for microwave frequency application, components need to have superior voltage standing wave ratio (VSWR) characteristics as well as outstanding power handling capability. Addition to the brilliant component performance, manufacturers need to achieve excellent fabrication yield performance to keep the project viable. Process engineers face many challenges on each fabrication steps, which could significantly degrade the fabrication yield. Few challenges could originate from material sets, while others could arise from the process variations. In this work, we extensively studied the influence of many different parameters that considerably diminish the fabrication yield performance. We analyzed different parameters to design RF and Microwave termination resistors using thin film materials. One of the essential parameters, which significantly reduce the fabrication yield, is the inconsistency of surface roughness throughout the wafer. We studied the variations of the thin film materials microstructure and the sensitivity of film resistivity in response to surface roughness inconsistency. We experimented anneal drift of the material and effects of the temperature compensation of resistor (TCR) due to substrate surface roughness and existence of powder contamination on the surface. We compared Lapped and As-Fired substrates roughness and researched the inconsistence roughness effects on the thin film material. We studied the deposition rate of sputtered copper over the life of the target, from machine to machine and across the pallet, and analyzed the effects on the thin film material component. We studied the moisture related long time drift based on electro migration effect and the temperature dependence drift based on the materials sheet resistance. We analyzed the alteration of current density due to thin film resistor trimming and yield loss due to resistor value tolerance and trim variation by studying the sensitivity of the resistor area variation through trimming process. By analyzing different fabrication factors and material parameter properties, we realized the fact that most sensitive parameter that degrades the process yield is the existence of inconsistent surface roughness throughout the substrate. Based on the research study, we developed high power RF and Microwave 50 ohm termination resistors with excellent fabrication process yield performance.

The effect of microwave radiation on polyvinyl chloride-graphite thick film resistors

Purpose – The purpose of this paper is to study the microwave interactions in polymer thick film resistors, namely, polyvinyl chloride (PVC)-graphite thick film resistors, and its applications in trimming of these resistors. Design/methodology/approach – We applied microwave radiation in the form of pulses of various pulse durations and with different powers to polymer thick film resistors and observed the variation of resistance of these resistors with microwave radiation. Findings – The paper finds that microwave radiation can be used for trimming of polymer thick film resistors. Research limitations/implications – The research implication of this paper is that polymer thick film resistors can be trimmed practically using this method. Practical implications – The practical implication of this paper is that we can trim the polymer thick film resistors, namely, PVC-graphite thick film resistor, by using this method. Originality/value – The value of the paper is in showing that microwave radiation can be used to trim downwards in the case of high-value resistors and trim upwards in the case of low-value resistors.

A HIGH-PRECISION ULTRA-LOW-POWER HYSTERETIC VOLTAGE DETECTOR USING CURRENT-BASED COMPARISON

This paper presented a high-precision, ultra-low-power hysteretic voltage detector (HVD) using current comparison to detect voltage default crossing moments for energy-harvesting systems (EHS) in wireless sensor network (WSN) applications. The HVD mainly consists of four parts: a specially designed voltage-to-current converter (VCC) with thermal stability improvement, a comparison core to make current-based comparison, a current pre-amplifier to improve its transient performance and a Schmitt inverter to provide the hysteresis characteristic. The prototype of this HVD has been implemented in SMIC 0.18 μm CMOS process and occupies 0.036 mm2 area without pads. The hysteresis window is about 120 mV wide. The temperature coefficient (TC) is about -170.2 ppm°C. The average variation to different process corners can be reduced to 1.4% by MOSFET and resistor trimming. The total power consumption is only 701.5 nW when VDD is around 1.8 V.

A high‐order curvature‐corrected CMOS bandgap voltage reference with constant current technique

SUMMARYA high‐order curvature‐corrected complementary metal–oxide–semiconductor (CMOS) bandgap voltage reference (BGR), utilizing the temperature‐dependent resistor and constant current technique, is presented. Considering the process variation, a resistor trimming network is introduced in this work. The circuit is implemented in a standard 0.35‐µm CMOS process. The measurement results have confirmed that the proposed BGR operates with a supply voltage of 1.8 V, consuming 45 μW at room temperature (25 °C), and the temperature coefficient of the output voltage reference is about 5.5 ppm/°C from −40 °C to 125 °C. The measured power supply rejection ratio is −38.8 dB at 1 kHz. The BGR is compatible with low‐voltage and low‐power circuit design when the structure of operational amplifiers and all the devices in the proposed bandgap reference are properly designed. Copyright © 2012 John Wiley & Sons, Ltd.

The Future of Maximum CAD/CAM Automation for Ceramic Hybrids

New concepts developed maximize CAD/CAM automation for all types of Ceramic Hybrids including Thick Film, Thin Film, LTCC and HTCC. Designs can go quickly from concept to manufactured product, which will fuel more progress to bring a largely manual process to maximum automation, to include automatic masks, panels and generation of 3D analysis models. Maximum automation results in expanded use of technologies that are now shrinking. Technologies that have complex and difficult to understand design and manufacturing steps have a hard time gaining wide acceptance. CDS is tackling this complex challenge and is designing and implementing the following processes to solve the most difficult CAD/CAM problems:1. Be a true CAM tool that reads in designs from any other EDA (layout) system. Y2. Run all possible DRC checks necessary for high fabrication and assembly yield. Y3. Make all manufacturing masks automatically from very basic designs by using settings in an automatically configurable table. Y4. Panelize all types of Ceramic designs in preparation for manufacturing. Y5. Generate documentation automatically through from stored configuration files. D6. In LTCC and HTCC, place cavity punches (nibbles and rubs) automatically and feed correct machine data to the punch machine. Y7. Export resistor trimming data directly to the laser trimming machine. F8. Feed flying probe test data directly to the flying probe tester. D9. Automatically make a 3D Image and export ACIS or STEP for thermal analysis. D10. Export data directly to all electrical analysis and thermal analysis tools. P11. Support circuit fabrication non-planar surfaces. F12. Make full 3D analysis models of circuits non-planar surfaces. FThe purpose of this paper is to define what is required for the Ceramic Hybrid industry to realize full automation in design, checking and output to manufacturing. Your ideas are welcome.

Focus on lasers and imaging

Focus on lasers and imaging

Laser-Induced Resistance Fine Tuning of Integrated Polysilicon Thin-Film Resistors

In this brief, we present a novel polysilicon resistor trimming technique using a pulsed focused nanosecond laser at a fluence slightly lower than the melting threshold for polysilicon. Using this technique, we were able to trim a 4 μm ×40 μm Taiwan Semiconductor Manufacturing Company 180-nm n-doped polysilicon resistors with a 200-ppm precision. Much better precision is possible by using larger structures. The method can be applied to any CMOS process without any extra layer deposition or specific design restriction beside the fact that the laser beam must be able to reach the polysilicon structure. The high repeatability of the process allows an open-loop calibration. A complete characterization of the trimmed devices, including transverse electromagnetic and atomic force microscopy imaging as well as Raman spectroscopy, has been conducted, leading to the conclusion that a material restructuration in the grain boundaries of polysilicon, following laser irradiation, is responsible for the thin-film resistivity lowering. The stability of the polysilicon thin film, as tested by heating the device at 150°C during 1000 h, is about 1.3%, which is slightly higher than the 0.7% resistance variation for untrimmed thin films.

285°C Resistor Drift and Failure Analysis

In order to improve the reliability of down-hole electronics, Quartzdyne Electronics has invested millions of device test hours in life testing circuits in both powered and un-powered modes. In addition to time at temperature, these tests include thermal cycling and high impact drop testing. Resistors drift has become a significant wear-out mechanism in these tests. Prior testing has shown that resistor material, substrate material, resistance range and trim method each play a significant role in resistor stability at elevated temperatures. Some resistance ranges tested had no acceptable performers. The purpose of this study is to expand the range of values, materials and package sizes in hopes of identifying reliable resistors for high temperature applications. This study will focus on a broad range of NiCr-on-silicon resistors, including larger package sizes than were previously tested. Additionally, we will be testing several precision foil-type resistors. Resistors will be mounted in hermetic packages and aged at 285°C for 1000 hours. The packages will be removed from the oven periodically and the resistance of the devices will be measured at ambient temperature. This study is being done in cooperation with resistor vendors who have supplied some of the devices for this test.

Trimming process and temperature variation in second-order bandgap voltage reference circuits

This paper presents the design and experimental performance of a second-order bandgap voltage reference integrated circuit (IC). Experimentally observed nominal reference voltage at room temperature is 1.150V with best temperature performance of 3mV variation over −40 to 120°C. A 5-bit resistor trimming is used to compensate the variation of reference voltage due to layout mismatch and process variation. A trimming methodology is described in this paper to optimize both the temperature performance and reduce the variation of the room temperature voltage over different samples. Even with best temperature performance trim-code, the absolute variation in reference voltage over 20 samples is 85mV which is trimmed to ±11mV (1.3%) using the proposed trimming methodology. The second-order bandgap circuit is designed in a 0.5μm BiCMOS process with less than 50μA current consumption.

Current-induced recrystallization of polycrystalline silicon nano thin films deposited at different temperatures and its influences on piezoresistive sensitivity and temperature coefficients

To improve the performance and yield of piezoresistive sensors based on polycrystalline silicon nano thin films (PNTFs), the 80 nm-thick PNTFs were deposited on silicon (1 1 1) substrates by LPCVD at different temperatures and fabricated into cantilever beams. The electrical trimming characteristics and the dependences of gauge factor, temperature coefficient of resistance (TCR) and temperature coefficient of gauge factor (TCGF) on resistor trim with different deposition temperatures were measured. Based on the interstitial-vacancy model, the electrical trimming is explained as the mobility increase caused by current-induced recrystallization of grain boundaries. The conclusions indicate that the changes in gauge factor, TCR and TCGF with resistor trim are due to the grain boundary state variation (including scattering center, grain boundary width, tunneling current, localized and extended state conductions). And the electrical trimming method is testified to be applicable for the resistor trimming of PNTF-based sensors after packaging.

The Future of Maximum CAD/CAM Automation for Ceramic Hybrids

New concepts recently developed maximize CAD/CAM automation for all types of Ceramic Hybrids including Thick Film, Thin Film, LTCC and HTCC. Designs can now go quickly from concept to manufactured product, which will fuel more progress to bring a largely manual process to maximum automation, to include automatic masks, panels and generation of 3D analysis models. Maximum automation results in expanded use of technologies that are now shrinking. Technologies that have complex and difficult to understand design and manufacturing steps have a hard time gaining wide acceptance. CDS is tackling this complex challenge and is designing and implementing the following processes to solve the most difficult CAD/CAM problems:Be a true CAM tool that reads in designs from any other EDA (layout) system. YRun all possible DRC checks necessary for high fabrication and assembly yield. YMake all manufacturing masks automatically from very basic designs by using settings in an automatically configurable table. YPanelize all types of Ceramic designs in preparation for manufacturing. YGenerate documentation automatically through from stored configuration files. DIn LTCC and HTCC, place cavity punches (nibbles and rubs) automatically and feed correct machine data to the punch machine. YExport resistor trimming data directly to the laser trimming machine. FFeed flying probe test data directly to the flying probe tester. DAutomatically make a 3D Image and export ACIS or STEP for thermal analysis. DExport data directly to all electrical analysis and thermal analysis tools. PSupport circuit fabrication on non-planar surfaces. FMake full 3D analysis models of circuits on non-planar surfaces.F The purpose of this paper is to define what is required for the Ceramic Hybrid Microelectronics industry to realize full automation in design, checking and output to manufacturing. Your ideas are welcome.