Showing papers on "Mask inspection published in 1991"

Phase-shift mask pattern accuracy requirements and inspection technology

Abstract: Computer simulations and i-line phase shift lithography experiments with programmed 5X phase shift reticle defects were used to investigate the effect of opaque and phase-shift layer defects on sub-half-micron lines. Both the simulations and the experiments show that defects in the phase shift layer print larger than corresponding opaque defects, with 0.3-0.4 micrometers defects affecting sub-half-micron critical dimensions by more than the allowable 10%. Inspection of programmed phase shift defects with a prototype mask inspection system confirmed that the system finds the 0.3-0.4 micrometers phase shift defects critical to sub-half-micron lithography.

Detection and printability of shifter defects in phase-shifting masks

Abstract: Because of the high printability of shifter defects in phase-shifting masks, it is worthwhile to characterize the inspection and printing of the shifter defects. The detectability and printability of shifter defects as a function of size and location have been investigated by experiments and simulation. A test mask with various programmed shifter defects was inspected by means of a die-to-die inspection system and printed in positive resist with an i-line stepper. Corner defects are difficult to detect and have low printability. A defect located in small features has high printability. We have also investigated the detectability and printability of the phase angle defects which have phase angles other than 180°. Defects with 120° to 180° phase angles have high printability. Defects with phase angles below 90° are not printed.

Requirements and performance of an electron‐beam column designed for x‐ray mask inspection

Abstract: Production viable inspection of x‐ray masks requires the resolution of a scanning electron microscope (SEM) at an imaging rate approximately 1000 times that of commercially available systems. This article analyzes the inspection task for x‐ray masks and compares the requirements for beam‐current density and imaging efficiency necessary to achieve reasonable throughput with technologies available on current SEM and electron‐beam lithography systems. The resulting specifications have been translated into an electron‐optical column with many novel features. The gun, which contains six thermal field‐emission sources mounted on a turret, produces a Gaussian profile beam that is scanned over a continuously moving substrate. Dual electrostatic icosapole deflectors provide high speed telecentric deflection. Secondary electrons are separated from the primary beam by a Wien filter and accelerated into a semiconductor electron detector. An analog optical‐fiber link is used to transmit the signal to the image compute...

Photomask inspection device

Abstract: PURPOSE:To shorten the length of time that a pattern flaw is detected by detecting semitransparent foreign matter being present on an area which becomes a transparent pattern by distinguishing an opaque flaw from transparent flaw. CONSTITUTION:A laser beam from a laser head 11 is bisected. While the same position of the chip patterns 2A and 2B on the photomask 1 are irradiated, their entire areas are simultaneously scanned. Rays of light transmitted through the patterns are received by the corresponding photodetectors 12A and 12B. Their outputs are compared with each other by a signal processing circuit 13. According to the degree of the difference, semitransparent foreign matter 23 in a transparent pattern 22 is decided by distinguishing an opaque flaw 21X in the pattern 22 from an transparent flaw 22X in a light-shielding pattern 21. If the flaw 21X or the flaw 22X is found, the photomask is reprepared or partially corrected. If only the foreign matter 23 is found, it is rewashed.

Mask inspecting method

Abstract: PURPOSE:To shorten the time required for mask inspection by scanning only a pattern part on a mask according to original drawing information and deciding whether or not there is a pattern form whether the output of a detector is large or small. CONSTITUTION:A scan 3 on only the pattern 6 of the mask 2 is made with an electron beam 1 according to the original drawing information. Consequently, the detector 4 generates a signal waveform 5 indicating only the part of a defect 7 and arithmetic operation for discriminating between the pattern 6 and defect 7 is not necessary. Thus, only the part of the pattern 6 on the mask 2 is scanned to shorten the scanning time and the defect decision arithmetic processing is not necessary, so the mask inspection time can be shortened.

Photomask and inspecting method thereof

Abstract: PURPOSE:To inspect the photomask with high accuracy at a high speed by forming patterns of the size at which the patterns are not resolved by a mask aligner on a mask dry plate and using the patterns as the patterns for alignment at the time of the mask inspection. CONSTITUTION:The patterns 1 having the resolution smaller than the resolution of the mask aligner are plotted by the pattern data of the same chip and exist together with the patterns in the other mask at the same points in a chip. The information relating to the position of the patterns 1 is obtd. from the pattern data and a stage is moved to bring the photomask 3 to the position of the substrates 1. After the spacing between right and left lenses 5 is set at a normal spacing, the alignment is executed while viewing the image on a monitor CRT 7 and a waveform monitor 9 displaying a differential signal. The photomask inspection which can make the high-speed alignment with a high accuracy is executed in this way.

Method and device for photomask inspection

Abstract: PURPOSE:To perform flaw inspection for a mask pattern with high accuracy by irradiating one area of a photomask with light from one surface side of the photomask formed by forming a repetitive pattern on one surface of a transparent substrate and forming a pattern image of the one area by its reflected light on the pattern area of another area of the photomask which has a pattern in the same shape with the pattern of the one area. CONSTITUTION:The one area of the photomask 5 is irradiated with the light from the one surface side of the photomask 5 obtained by forming the repetitive pattern on one surface of the transparent substrate and the pattern image of the one area by its reflected light is formed on the pattern surface of another area of the photomask 5 having the pattern in the same shape with the pattern of the one area. Then flaw of the mask pattern is inspected according to whether or not there is light passing through the other area. Consequently, flaw inspection for the mask pattern is performed with high accuracy.

Inspection of glass mask

Abstract: PURPOSE:To shorten the formation time of a glass wafer by a method wherein an opaque photosensitizer is used and only the photosensitizer is used as a nontransmissive property of a metal film. CONSTITUTION:A glass mask or a reticle to be inspected is exposed, by using an aligner, on a glass wafer coated with an opaque photosensitizer; a development treatment is executed. This glass wafer is inspected by using a transmission microscope. Alternately, it is inspected by using an automatic mask inspection apparatus of a transmitted light type; a defect, a dust particle or the like on the glass mask is detected; it is removed in order to prevent a defective product. Thereby, the mask inspection time and a mask inspection process can be reduced sharply.