What is phase shift mask in lithography?

Phase-shift masks are photomasks that take advantage of the interference generated by phase differences to improve image resolution in photolithography. There exist alternating and attenuated phase shift masks.

How do phase shift masks work in photolithography?

Phase-shift masks (PSMs) work by adding phase information to the mask in addition to amplitude information. A binary chrome-on-glass mask encodes the information about where to position resist edges using chrome (with zero amplitude transmittance) and glass (with 100% amplitude transmittance).

What is a mask in optics?

[′äp·tə·kəl ′mask] (electronics) A thin sheet of metal or other substance containing an open pattern, used to suitably expose to light a photoresistive substance overlaid on a semiconductor or other surface to form an integrated circuit.

What is OPC in semiconductor?

Optical Proximity Correction (OPC) OPC is a technique used to compensate for image distortions that occur during sub-wavelength lithography: printing structures smaller than the wavelength of light being used.

What is amplitude mask?

In a coded aperture system, an amplitude mask is inserted at the aperture plane of the lens and is used to increase the DoF of conventional imaging. This mask is designed to be broadband, such that the effective focus blur kernel of the imaging system preserves high-frequency information.

What is dark field mask?

A mask is negative (or dark field) when the artwork to be developed is clear. Thus, for an etching process, a dark field mask can be used with a negative photoresist, or a clear field mask can be used with a positive photoresist.

What is OPC mask?

Optical proximity correction (OPC) is one of the prevailing resolution enhancement techniques (RETs) that can significantly improve mask printability. However, in advanced technology nodes, the mask optimization process consumes more and more computational resources.

What is a phase-shift mask?

A phase-shift mask relies on the fact that light passing through a transparent media will undergo a phase change as a function of its optical thickness.

How can phase-shift masking improve the resolution of 365 Mu lithography?

Phase-shift masking has been demonstrated for 365 mu and 248 mu lithography, allowing improvements in both resolution and focal depth. Through frequency doubling with alternating phase-shift masking, 0.20 micron resolution may be achieved at 193 am with focal depths greater than 2.tm . Figure 1 shows aerial image

What are alternating and attenuated phase shift masks?

There exist alternating and attenuated phase shift masks. A phase-shift mask relies on the fact that light passing through a transparent media will undergo a phase change as a function of its optical thickness.

What are the effects of transmission loss in phase-shift mask process?

The transmission loss is great enough to produce linewidth loss and a decrease in exposure latitude in a phase-shift mask process, which was investigated and will be presented. 2.3 Phase errors at 193 nm Errors in phase-shifter thickness scale with wavelength. At 365 urn, a 10° phase-shifter error translates to 212 A thickness (n =1.47).