Motor control for the production of masks for subminiaturised circuits

Claim 2

An electronic apparatus for the mass production of masks for integrated circuits, comprising a vacuum tight enclosure, and in said enclosure: a master mask, means for emitting diffuse ultraviolet radiations illuminating said mask, the unmasked parts thereof emitting electrons in response, a wafer covered with resin sensitive to electron bombardment located in a plane parallel to that of said master mask, means for producing an electric field and a magnetic field which are parallel to one another, and perpendicular to theplane of said master mask, in order to focus said electrons on said wafer, means being provided for maintaining said wafer at predetermined location, electrically controlled mechanical means to make it possible to adjust with a predetermined degree of accuracy, the position of said master mask in relation to said wafer, and to compensate the lock of the focussing of said electrons on said wafer; said electromechanical means comprising two pairs of identical indexation marks respectively carried by said wafer and said master mask, means being provided to illuminate the two marks of said master mask, thus producing in response emission of electron currents towards said marks of said wafer, said marks of said wafer being constituted of zones implanted on said wafer, said zones being made of a material capable under the impact of electrons of emitting radiation, transducer comprising photomultipliers being provided for transducing said radiations into electrical signals, optical means being provided to direct said radiations onto said photomultipliers.

Claim 3

An apparatus as claimed in claim 1, wherein said electromechanical means comprise a mask holder, a first, a second and a third bar, said bars being situated in the plane of said mask holder, said first bar directed along the straight line passing through said centers of said marks, said second and said third bar, being perpendicular to said first bar, and being respectively directed towards said centers of said marks, and respectively associated with said bars, piezoelectric elements, each having a control input, and means for connecting said control input to variable direct current voltage source, the variations in the voltage applied to element associated with the first bar resulting in a translation of said mask holder, whilst the variation in the voltage applied to the elements associated respectively with said first and third bars, produce rotations about the marks with which they are aligned, an automatic control device being provided to successively adjust the three voltages to obtain the maximum of amplitude of said signal.

Claim 4

An apparatus as claimed in claim 2, wherein the marks of said wafer are constituted by cathodoluminescent zones implated in the wafer.

Claim 5

An apparatus as claimed in claim 1, wherein that the marks of said wafer are constituted by metal zones capable of emiting x-rays in response to the electron current, said transducer means comprising a scintillator which receives said x-rays, a photomultiplier, and light conductors being used to connect said scintillator to said photo-multiplier.

Claim 6

An apparatus as claimed in claim 1, wherein said magnetic field producing means comprise an electromagnet having two polepieces, located outside said vacuum tight enclosure, displacement means being provided in order to displace the electromagnet in relation to said enclosure and enable the latter to be dismantled.

Claim 7

An apparatus as claimed in claim 5, wherein said enclosure has an entry airlock through which it can be supplied with wafers.

Claim 8

An apparatus as claimed in claim 6, wherein a slider is provided, said wafers being arranged upon said slider which is displaceable and guided by rollers in performing its displacEments.

Claim 9

An apparatus as claimed in claim 4, wherein said automatic control device comprises a programmer for insuring a sequential operation cycle.

Claim 10

An apparatus as claimed in claim 8, wherein the programmer of said automatic control circuit comprises two first outputs for the sequential operation of the illumination of the two marks of said wafer; an electronic circuit, comprising a counter in order to count the pulses coming from the two scintillators, said programmer having a first output to actuate a clock which starts said counter and stops it at the end of fixed duration, a register connected to said counter, in order to store in the register, the count recorded during said fixed duration time of the proceding sequence; a comparator having, two inputs connected respectively to the outputs of said register and said counter, and two first outputs respectively actuated, if the count recorded by said counter is greater or less than said count recorded by the register, and a third output connected to the programmer, said third output being actuated when the counts are identical; a count up, count down counter whose initial count is a coded form of the initial voltage applied to said elements associated with said bars, having an up input and a down input respectively controlled by said first and second outputs of said comparator, the programmer having an output connected to said up input of the count up, count down counter in order to sequentially supply it with trains of pulses whose number represents a coded form of said voltage increments, a switch controlled by said programmer and having one input which receives the current from said count up, count down counter, and three outputs, means comprising a register, a digital to analogue converter for connecting each output of said switch to said d.c. variable voltage source, connected to the control input of each element.