摘要:

Maskless ion beam assisted etching of GaAs and Si has been investigated. Focused Ga+ion beam was irradiated on GaAs and Si in chlorine and xenon difluoride gas atmosphere, respectively. It was found that an optimum gas pressure existed to improve the etching rate. The etching rate showed a maximum at a bombarding angle of 60°–70°. The simulation of the etching profile was in reasonable agreement with the observed profiles. It was also found that redeposition effect is absent for ion beam assisted etching.

ISSN:1071-1023    

DOI:10.1116/1.583293

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A 30 kV fine focused ion beam machining system was constructed in which a Ga ion beam extracted from a needle‐type liquid metal source is focused into a submicron spot by a three‐electrode electrostatic lens and deflected by an octapole deflector. Vacuum rate at the work stage is 10−7–10−8Torr. With blanking electrodes, the machined area can be confined to any rectangular area determined by the cursol lines on the scanning ion microscopic display. Probe current is higher than 0.3 nA for a 0.3 μm diam spot and current density is over 0.71 A/cm2. At a scanning speed of 100 μm/s, grooves 0.2 μm wide are made in a gold film 0.1 μm thick. By scanning repeatedly, a groove is produced in a (100)Si wafer yielding a cross section having a very sharp V shape with an aspect ratio of 8:1. Two‐dimensional scanning removal is performed under various conditions at the same dose of 1.9×1018ion/cm2, resulting in very different hole shapes. Removal at a scanning speed of 1 mm/s with 200 repetitions produces a uniform shallow hole shape, while removal at 5 μm/s with one repetition results in an inclined deep hole shape. Observation of the cross section shows that this inclined area protrudes from the side wall of the hole, formed through the redeposition of sputtered silicon. These results show the importance of the redeposition process in removal utilizing fine focused ion beams. Also, the differing results of two scanning methods appear to demonstrate the nonlinear sputter effect in fine focused ion beam machining.

ISSN:1071-1023    

DOI:10.1116/1.583294

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

An electrostatic optical system has been designed to produce a high resolution (10–100 nm) ion beam probe based on a very high brightness H+2field ionization source developed in our laboratory.1The system described here includes two electrostatic lenses, postlens octupole and quadrupole deflectors, beam blanker, stigmation and alignment deflectors. Since the resolution of this system is limited by the aberrations of the optics, a systematic approach is employed to minimize these aberrations. First, individual lenses were designed by many trial evaluations using appropriately constructed figures of merit. The scales and magnifications of both lenses then were determined simultaneously to minimize the axial aberrations of the combined lens. The deflectors were also optimized using analytical expressions of deflection aberration coefficients to achieve small deflection aberrations. The beam blanker at the beam crossover point can also give reasonably high blanking rates (10–300 MHz) for H+2ions with small spurious deflection. This optical system is to be used in an ion beam lithography machine currently under construction. In this system, a 2 mrad beam acceptance half‐angle will produce a probe size of 10 nm with a current density of 100 A/cm2at 50 keV energy when used with the H+2field ion source which produces a typical angular current density of 10 μA/sr.

ISSN:1071-1023    

DOI:10.1116/1.583295

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

An experimental focused H+2ion beam system being developed for use in a focused ion beam lithography application is described. The system uses a gaseous field ionization ion source operated at cyrogenic temperatures with a 〈100〉 thermal field built‐up tungsten emitter tip to confine the ion emission. A five element cylinder electrode lens is designed to focus the hydrogen ion beam. Modeling results show a 120 Å probe could be scanned over a 0.2 mm square field at 30 keV utilizing the high resolution ion optics that the gaseous field ion source permits. Initial ion optical results from this system are presented.

ISSN:1071-1023    

DOI:10.1116/1.583296

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A scanning ion beam lithography system has been used for the rework of chromium‐on‐glass mask plates to repair defects in the VLSI circuit pattern. By using submicrometer diameter beams of gallium and of gold ions to sputter selected areas of the mask, both clear and opaque areas have been generated on the substrate.

ISSN:1071-1023    

DOI:10.1116/1.583297

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A focused ion beam (FIB) has been used for Si submicron device fabrication.p‐njunctions and two terminal resistors were fabricated using a 60 keV Ga+ion beam of diameter as small as 0.2 μm. Typical resistor dimensions were 50–160 μm in length and 0.2–0.5 μm in width. The Ga+dose ranged from 5E13 to 5E14 Ga/cm2.I–Vmeasurements showed the correct dependence of resistance on resistor length, width, and impurity concentration. We have studied the broadening of lines implanted in Si and SiO2using a fixed ion beam diameter as a function of dose level. Selective etch (H3PO3at 180 °C for Si and HF for SiO2) and SEM analysis showed an increase of 50%–75% in linewidth as the dose was increased by an order of magnitude.

ISSN:1071-1023    

DOI:10.1116/1.583298

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A variably shaped electron beam lithography system HL‐600 has been developed for use in a semiconductor factory. HL‐600 was for high throughput. It is capable of direct wafer writing at high speed and also capable of mask writing at high accuracy. A very high speed beam control circuit has been developed. The pattern data were decomposed through the pipeline digital circuit. The settling time of the DA converter was shortened to 100 ns at full scale. An automated loader and wafer prealigner have been developed minimizing operator intervention. The specially designed computer and software system allow background processing pattern data during exposure. One of the most distinctive features of HL‐600 is the mode changing function. The large deflection mode guarantees writing of ten 4‐in. wafers per hour and the small deflection mode can accurately write submicron patterns. The mode change can be carried out immediately without special adjustment. This paper describes the system configuration in detail.

ISSN:1071-1023    

DOI:10.1116/1.583299

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A variably shaped electron beam exposure system HL‐600 has been developed for both direct wafer writing and mask making. It was designed as a high‐throughput tool to cover lithography requirements down to a 0.5 μm linewidth. To achieve this high‐throughput capability, many newly developed techniques were adopted in the electron optics and in the control electronic circuits. The simplified electron beam column consists of only four magnetic lenses. The magnetic deflection for main field scanning was enlarged so as to reach up to 6.5 mm sq in order to reduce the overhead time associated with work stage movement. In addition, the design of an objective lens system with a small aberration, and an algorithm for deflection aberration correction were developed. Automatic measurement of defocusing and astigmatism aberrations at a number of sample points were performed by taking through focusing, and the third order polynomial correction function of deflection was determined. As a result, the edge resolution for the 2 μm sq beam was less than 0.2 μm over a 6.5 mm sq field. The column uses a flat‐top‐type LaB6electron gun with high brightness and large emittance. Although the maximum beam size and current density were limited by Coulomb blurring, the gun realizes a 6.4 μm sq size and 10 A/cm2density at the same time. It typically has a 5000 h lifetime. This HL‐600 is capable of writing more than ten 4 in. wafers per hour on the average. In addition to a summary of the HL‐600 system, this paper describes details concerning the novel techniques in optics and some exposure results.

ISSN:1071-1023    

DOI:10.1116/1.583300

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

Overhead time associated with a work stage is an important factor determining the throughput of step‐and‐repeat‐type electron‐beam lithography systems. In addition to increasing stage speed, utilization of large field electron optics contributes to reduction of such overhead time. However, when using large field optics, the stage is required to have minimal yaw to prevent field stitching error. Accordingly, a high‐speed, high‐precision work stage with a piezodrive yaw correction function has been developed for construction of high‐throughput e‐beam systems. To avoid leakage, magnetic field variation, and vacuum contamination, only the work table is located in the vacuum chamber. The table is driven byX,Y‐drive mechanisms located outside the chamber. To achieve high speed positioning, a unique, light‐weightX‐Ytable structure using a PTFE slide bearing has been incorporated. To correct yaw error at the stage, the work table can be rotated ±8 arcsec with a piezoactuator. Positioning and yaw correction for the table are carried out with a closed‐loop control system that utilizes three‐axis (X,Y, and yaw) laser interferometers. A maximum velocity of 100 mm/s, ±2 μm positioning accuracy, 130 ms movement time including vibration settling for a 6.5 mm step, and a yaw of less than ±0.3 arcsec has been achieved.

ISSN:1071-1023    

DOI:10.1116/1.583188

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A direct write electron beam lithography system has been constructed which is capable of writing 0.5 μm VHSIC patterns at a rate of 4 to 25 four−inch wafer levels per hour. The several key subsystems which permit this increase in performance over existing systems are (1) A variable shaped beam which exposes rectangular or triangular shapes from 0.5 to 2.0 μm in size at a current density up to 200 A/cm2; (2) an all digital, 100 MHz pattern generator with optical couplers for high speed, low noise data processing; (3) a unique deflection system with specially designed 18 bit digital to analog converters and ultralinear amplifiers; (4) a mechnaical state capable of 10 cm/s speed and 0.8 g acceleration, under microprocessor control, providing write‐while‐moving capability and synchronization with the pattern generator; and (5) a wafer handler system for cassette‐to‐cassette input/output; and (6) a complimentary software package which constructs files with the necessary data compaction for rapid transmission and proximity correction for proper exposure.

ISSN:1071-1023    

DOI:10.1116/1.583189

出版商:American Vacuum Society    

年代:1985

数据来源: AIP