U.S. Philips Corporation

Hewson Nicholas King

Derek Washington

Pieter Schagen

Pamela May Stubberfield

James P Beasley

Daphne L Lamport

John R Mansell

Roger Pook

Julian P Scott

When an electron beam is used to effect a process at two adjacent surface areas of a target, such as a semiconductor wafer coated with an electron sensitive resist, various alignment errors can occur, such as where the wafer becomes distorted. The provision of a reference marker, for example a square-etched depression, at the surface of the target between the areas of the target enables the detection of any such distortion. After carrying out the process at one of the areas, an electron beam with a rectangular-shaped spot is directed, in turn, toward the predetermined positions of two mutually transverse sides of the reference marker. In the absence of any alignment error, the beam spot overlies the side in question in order to overlap the marker and the area of the target in the immediate vicinity. Back-scattered electrons can then be detected to give a signal representative of any deviation between the actual position and the predetermined position of the marker so that the electron beam can be correctly aligned when effecting the process of the second of the two areas. For increased accuracy of alignment, a plurality of markers may be provided between the adjacent surface areas.

Method of using an electron beam

When an electron beam is used to effect a process at two adjacent surface areas of a target, such as a semiconductor wafer coated with an electron sensitive resist, various alignment errors can occur including wafer distortion. The provision of a reference marker, for example a square-etched depression, at the surface of the target between the adjacent surface areas enables detection of any misalignment. Thus, after effecting the process at one of the areas, an electron beam having substantially the same size and shape as the reference marker is directed toward the predetermined position of the reference marker. Back-scattered electrons are then detected to give a signal representative of any deviation between the actual position and the predetermined position of the reference marker so that the electron beam can be correctly aligned before carrying out the process at the second of the two surface areas. For increased accuracy of alignment, an array of reference markers may be provided between the two adjacent areas.

A channel plate electron multiplier of the discrete dynode type formed from conductive sheets which are stacked in closely spaced relation. Each sheet is perforated with apertures which are aligned to form electron multiplying channels. The apertures in each sheet have input and output and cross sections which are approximately the same size and a concave shaped inner surface profile which causes a majority of electrons to strike the inner surface close to the output end, whereby the gain of the multiplier is increased.

Electron multipliers

An electron image projection mask consisting of an optical mask comprising a transparent substrate, bearing an opaque mask pattern disposed on the substrate, a transparent coating extending over the mask pattern and the areas of the substrate exposed through the apertures in the opaque mask pattern, and a metal image extending over the transparent coating. The metal image has a pattern corresponding to the apertures in the opaque mask pattern, the optical density of the metal image being such as to reduce the average light transmission through the apertures in the mask to a value between 25 and 80% of the average light transmission of the apertures in the absence of the metal image. Also, a method of producing the electron image projection mask.

Electron image projection masks

A color cathode ray tube having a screen with concentric phosphor ring patterns and an electron multiplying channel plate between the screen and the electron gun, the channel plate including a focusing control electrode having a constant focusing action.

Color tube having concentric phosphor ring pattern and electron

A channel plate with color selection electrodes and color phosphors for use as an image display screen in a color television tube. This is a division, of application Ser. No. 288,597, filed Sept. 13, 1972, now U.S. Pat. No. 3,860,849, Jan. 14, 1975.

Channel plate with color selection electrodes and color phosphors

Electron beam apparatus comprising a channel plate which emits electrons in the form of hollow electron beams, a focusing control electrode for controlling the diameter of the hollow beams and a target having a pattern of concentric areas aligned with each hollow beam, said pattern having at least two different areas which respond differently to electron bombardment and may be selectively bombarded under control of said electrode.

Color tube having channel electron multiplier and screen pattern of

A channel plate with color selection electrodes and color phosphors for use an an image display screen in a color television tube.

Cathode ray tube having channel multiplier and electron reflecting

A channel plate electron multiplier having channels which rapidly decrease in cross-section away from the input aperture and a conductive structure extending across the input aperture to flatten any fringing electrostatic field, resulting in an electrostatic field configuration which causes secondary emitted electrons to collide with the same side of the channel.

Growing community of inventors

Salfords, near Redhill, United Kingdom

Hewson Nicholas King