摘要:

A uniqueX‐Ystage has been developed for use in an electron‐beam lithography system. It is designed to accommodate wafer sizes up to 6 in. The stage uses conventional linear ways and ball bearings, but incorporates a unique capstan/swinging drive bar design to couple the servomotors to theXandYstage elements. Major components of the stage are made from titanium to achieve maximum stiffness to weight ratio. The capstan drive gives very rigid coupling between the servomotor and the stage. This drive stiffness permits rapid and precise positioning of the stage by the servosystem. The rotary capstan uses a ferrofluidic seal, permitting the servomotors to be outside the vacuum chamber without requiring bellows seals. A prototype of the stage has extremely low vibration levels, and can slew at velocities up to 10 cm per s. It can step 2 mm and settle to 10 μm in 52 ms, and achieve submicron position accuracy in 70 ms. Maximum acceleration capability is 0.8 g. Stage position is sensed by a laser interferometer and associated pulse‐counting circuitry. A microprocessor reads the position counters every 0.5 ms. The motor drive currents are computed from feedbacks proportional to position error and observed velocity, and from feedforwards proportional to desired velocity and acceleration. Stiffness at low frequency is enhanced by feedback derived from the integral of position error. Low harmonic excitation of the system in which the stage resides is guaranteed by smoothly varying preprogrammed trajectories derived by triple integration of jerk (acceleration rate) commands. A powerful high‐level control strategy has been developed in which sequences of traversal time and traversal distance of contiguous segments are converted to appropriate jerk commands for smooth continuous motion. The strategy includes, as an integral part, constraints for maximum velocity and acceleration. Trajectory commands are interpreted by the same microprocessor which computes the servomotor currents. Desired position, velocity, and acceleration are updated by the microprocessor every 0.5 ms in accord with the sequence of jerk commands provided by the control computer, in synchronization with pattern generator operation.

ISSN:1071-1023    

DOI:10.1116/1.583190

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A 50 keV nanometer e‐beam lithography system was fabricated using a Zr–W thermal field emitter. The system has a beam current ranging from 6×10−12to 1×10−9A, a minimum beam spot of 2.4 nm and a scanning field of 240×180 μm2. It was found that the total emission and the specimen current was stable with a fluctuation less than 0.5% for more than 3 h. To investigate nanometer pattern delineation characteristics, the effect of various exposure parameters on a delineated line width were measured and a line pattern with a width less than 20 nm was fabricated. A 40 nm wide one dimensional MOS structure was also fabricated using Ni liftoff and reactive sputter etching techniques.

ISSN:1071-1023    

DOI:10.1116/1.583191

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

An experimental variable shaped electron beam lithography system has been built to verify the theoretical design considerations and fundamental control method. The electron beam column consists of four magnetic lenses, two square apertures, two aligners, an angular aperture, a set of blanking plates, and a position deflection yoke. The size of the beam spot is varied by a set of electrostatic deflection plates. In order to maintain the current density in the spot constant, as the size of the beam spot varies, the center of the shaped deflection plates is placed to coincide with the image of the gun crossover, and the shaped deflection plates position can be electrically adjusted. The acceleration voltage is 20 kV. The field size is 2.5 mm square. The maximum spot size is 10 μm2. The maximum current density is 1 A/cm2. The system is controlled by an EG 3003 computer. The beam blanking switching time is 50 nS.

ISSN:1071-1023    

DOI:10.1116/1.583192

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A high‐voltage (100 kV) variable‐shaped electron beam lithography system has been developed. With this system it is possible to improve the edge resolution in variable‐shape lithography to better than 0.1 μm even at high beam currents. In addition the other advantages of high‐voltage lithography such as reduced proximity effect, improved line width control in lithography over steps in the substrate, and better profiles on thick resist overlayers are also obtained. Experimental results are compared with simulation from a Monte Carlo based model of the electron column which predicts the benefits of working at higher beam voltage than the conventional 20 kV. Results are presented which show current profiles and exposures in resist of patterns with sizes from 5 μm×5 μm to ∼1 μm×1 μm with sub 0.1 μm resolution at beam voltages of 70 kV and greater while maintaining a beam current of>3 μA.

ISSN:1071-1023    

DOI:10.1116/1.583193

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

The IBM EL‐3 e‐beam mask making system is a high performance and high throughput tool designed for lithography pattern exposure in manufacturing. The main system features and architecture, which include a high‐current, variable‐shaped spot and subfield deflection have been designed primarily for direct wafer exposure. Special engineering efforts have been made to identify and eliminate minor magnetic influences and structure flexures that introduce submicron tool character so that mask patterns can be accurately exposed. This evaluation of the tool overlay performance is the result of a close tool monitor operated to reflect a manufacturing mode. Overlay verification patterns in the kerf area are measured by a Nikonx‐yinterferometric measurement system. Analysis of the data indicates EL‐3 consistently delivers a level‐to‐level overlay accuracy of the order of 0.1 μm.

ISSN:1071-1023    

DOI:10.1116/1.583194

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A commercial electron beam machine has been used in conjunction with high contrast resists to define patterns with dimensions close to the minimum beam diameter of 0.1 μ on a range of solid substrates. This has required a detailed knowledge of the beam‐substrate interactions in order to control linewidth. The electron scattering profiles in thin resist layers have been experimentally determined for substrates of Si, GaAs, InP, and Au on Si, and for beam voltages between 10 and 50 kV. These experimental results have been correlated with empirical models of electron scattering. It has been found that the simple double Gaussian model is inadequate at these dimensions, and the addition of an exponential term is necessary to fit data adjacent to the primary beam. Exposures have been modeled using this three term approximation, and the resultant lithography predicted by taking account of resist contrast. Routine fabrication of asymmetric 0.46 μm period gratings on InGaAsP substrates, used in the manufacture of distributed feedback lasers, has been possible, while experimental nonperiodic structures of 0.1–0.2 μ dimensions have been made on Si and InP. The reduction of backscattering by a multilevel resist system on Si has been studied with planarizing layer thicknesses up to 2 μm, and beam voltages of 20 and 30 kV.

ISSN:1071-1023    

DOI:10.1116/1.583195

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

Electron‐beam proximity printing (EBP) is a promising candidate for submicron lithography because it meets the stringent requirements for resolution, throughput, and image fidelity (here defined as registration and overlay). Registration and level‐to‐level overlay capabilities of EBP are reported in this paper. Two levels of a chip were exposed and processed subsequently, these levels represented by two different patterns in the same mask. Distortions of both patterns relative to each other, amounting up to several hundred nanometers, were detected. These distortions could be automatically compensated for during exposure to yield an average overlay better than 50 nm. Together with the low data scatter of 3σ<170 nm, this indicates high performance of the EBP registration and distortion compensation procedure.

ISSN:1071-1023    

DOI:10.1116/1.583196

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

Electron‐beam proximity printing (EBP) is a step‐and‐repeat lithography technique which uses masks. Stringent requirement for submicron lithography is the capability to compensate for ever present linear and nonlinear mask distortions. We have demonstrated that a slight modification of the EBP system converts this into a high resolution mask metrology tool, i.e., enabled us to measure absolute distortions of our e‐beam transmission mask in the EBP lithography tool itself. Resolution of these measurements was ±50 nm. Relative mask distortion data as deduced from our results coincided with separate experimental results from overlay experiments.

ISSN:1071-1023    

DOI:10.1116/1.583197

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

In scanning beam microfabrication processes, including resist exposure, direct maskless ion implantation, and micromachining, ions and electrons have complementary roles. It is advantageous to have, within a single scanning beam machine, finely focused and precisely coregistered beams of both ions and electrons. The requirement for the ion beam and the electron beam to have a common axis and to be focused at the target by a high resolution lens with short working distance can be met both by solely electrostatic and by combined magnetic and electrostatic lenses. Such lenses, and complete probe‐forming systems incorporating them, are considered.

ISSN:1071-1023    

DOI:10.1116/1.583198

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

Proximity effect in electron‐beam lithography is studied with an emphasis on physical understanding. Computer simulation is used to explore correction schemes which specifically include the resist behavior and yet are theoretically manageable in formulating the pattern correction for mathematical analysis. Both energy density part way through the resist and relative importance of background on critical edge are investigated. It is shown that one‐third of the resist thickness from the substrate appears to be where the process parameters should be characterized, and that the total effective deposited energy at the nominal edge must be reduced as the background contribution increases. A mathematical model and design graphs are developed so that the impact of the background on the edge control is directly related to fundamental physics through the Monte Carlo calculation. The nominal edge is used as the critical aspect to be controlled and the constraint of constant bias can be applied.

ISSN:1071-1023    

DOI:10.1116/1.583199

出版商:American Vacuum Society    

年代:1985

数据来源: AIP