JPH01152727A - Electron beam lithography - Google Patents

Abstract

PURPOSE:To prevent the accuracy of a pattern from deteriorating due to the deformation of a mask and also to cope with the case that the size of the mask is increased or the accuracy of the pattern is improved by correcting a mask substrate formed in advance with a conductive film on its rear face by an electrostatic chuck plate, and by conducting drawing on the substrate in the corrected state. CONSTITUTION:Metal is thinly deposited on the rear face of a mask substrate 21, thereby allowing an electrostatic chuck 37 to operate, and the thickness of the metal is sufficiently reduced so that the transmissibility of a light when it is used as a mask does not decrease by 10% or more. In order to minimize a variation in a lithography position in the direction of an optical axis due to the irregular thickness of the substrate 21, the upper face of the mask is pressed on a reference face 38. The lithography is conducted in a state that the substrate 21 is corrected by the chuck 37. Thus, the pattern formed by the lithography on the flattened substrate is not deteriorated in the accuracy of the pattern due to the deflection, warpage of the mask, and a high accuracy is expected.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) (Prior Art) Conventionally, when mask drawing is performed using an electron beam, a mask cassette that mechanically fixes a sufficiently thick mask substrate is used. Drawing was done while wearing it. However, the mask size is 9.
When making a reticle for a 0.5 μs device that is larger than 1 inch, deterioration of pattern accuracy due to mask deformation has become a problem.

On the other hand, when drawing on a semiconductor substrate such as a Si wafer, it is common to correct the wafer using a chuck before drawing. However, since the mask substrate is an insulator except for the surface, there was a problem that an electrostatic chuck could not be used.

(Problems to be Solved by the Invention) An object of the present invention is to provide an electron beam lithography method that can be used even when the mask size is increased or the pattern accuracy is improved.

[Structure of the invention]

(Means and actions for solving the problem) A transparent electrode is attached to the back side of the mask by vapor deposition, or a thin metal film is attached to the back side of the mask.
It is thin enough to cause only a slight decrease in light transmittance, and by attaching it, the warpage of the mask can be corrected using an electrostatic chuck. Therefore, a pattern drawn on a flattened substrate can be expected to have high accuracy without deterioration in pattern accuracy due to mask deflection or warpage. Further, if the mask substrate is thick, a large voltage is required for correction, so it is preferable that the mask substrate has a thickness of 2 m or less.

(Example) The drawing is a configuration diagram of a lithography apparatus used in the electron beam lithography method of the present invention. 20 is a sample chamber, 21 is a mask substrate, 22 is a sample stage, 23 is a stage drive circuit, 24 is a length measuring needle 25 that uses laser interference, is a blanking circuit, 26 is a scanning deflection circuit, 27 is a control computer, and 28 is a blanking circuit. interface, 2
9 is a power supply, 30 is an electron optical lens barrel 31 is an electron gun, 32, 3
3.34 is a condenser lens, 35 is a blanking deflector, 36 is a scanning deflector, 37 is an electrostatic chuck substrate, 3
Reference numeral 8 indicates a mask pressing substrate.

Drawing is performed on the mask substrate 21 while being corrected by the electrostatic chuck substrate 37. The electrostatic chuck has a structure in which a high voltage of 100 OV is supplied from a power source 29.

The mask substrate 21 has a thin layer of metal deposited on its back surface to enable the operation of an electrostatic chuck. Furthermore, the thickness of this metal was made sufficiently thin so that the light transmittance would not drop by more than 10% when used as a mask.

In addition, in order to minimize fluctuations in the drawing position in the optical axis direction due to uneven thickness of the mask substrate, the upper surface of the mask is aligned with the reference plane 38.
It has a structure that allows it to be pressed against.

〔Effect of the invention〕

The pattern accuracy was improved because the vertical fluctuation of the drawing surface was suppressed to ±3p or less. Various correction functions to correct vertical movement of the drawing surface (dynamic focus, deflection sensitivity correction, etc.)
is no longer necessary, and reliability has been improved through simplification.

The accuracy measured using the built-in dimension measuring function of the EB device and the accuracy determined using a dimension measuring device using a laser or the like are now in good agreement. Furthermore, the accuracy when actually transferred is higher than when there is deflection.

[Brief explanation of the drawing]

The drawing is a configuration diagram of a lithography apparatus used in the electron beam lithography method of the present invention. 20... Sample chamber 21... Mask substrate 22... Sample stage 23... Stage drive circuit 24... Length measuring needle 25 using laser interference...
・Blanking circuit 26...Scanning deflection circuit 27
... Control computer 28 ... Interface 29 ... Power supply 30 ... Electron optical lens barrel 31 ... Electron gun 32, 33. 34.
...Condenser lens 35...Blanking deflector
36... Scanning deflector 37... Electrostatic chuck substrate
38...Mask pressing board agent Patent attorney Nori Chika Ken Yudo Mitsuyuki Matsuyama

Claims (3)

[Claims] (1) An electron beam drawing method characterized in that a mask substrate on which a conductive film is previously formed on the back surface is corrected using an electrostatic chuck plate, and drawing is performed on the mask substrate in this corrected state. (2) The electron beam lithography method according to claim 1, wherein the mask substrate has a thickness of 2 mm or less. (3) The electron beam lithography method according to claim 1, wherein the conductive film is a transparent electrode.