A New Photolithography Technique with Antireflective Coating on Resist: ARCOR

Abstract

The multiple interference effect is one of the major causes of the fluctuation in critical dimension control (CD) and in mark detection for alignment. Suppressing this effect is critical for future photolithography. We propose a new photolithography technique called anti reflective coating on resist (ARCOR), which improves linewidth accuracy and overlay accuracy by suppressing multiple interference. ARCOR consists of relatively simple processes: A clear antireflective film is spun onto the resist prior to the mark detecting for alignment and exposure. The film is subsequently removed and the resist developed in the conventional way. ARCOR differs from ARC, which suppresses the reflection at the resist/substrate interface. ARCOR suppresses the reflection at the air/resist interface. ARCOR allows mark detection and exposure without light intensity-loss and multiple interference. The experiments mainly examine polysiloxane and perfluoroalkylpolyether as ARCOR materials. I t is shown that linewidth accuracy can be improved from 0.3 to 0.03 km. The signal-to-noise ratio of the alignment signal is drastically improved, and the overlay error is about half that of the conventional method. ARCOR is also effective for directly measuring the reflectivity at the resist/sub strate interface, which is a key parameter of the multiple interference effect and the halation. Using ARCOR and a thin resist film, the measured ratio of reflected light to incident light indicates the reflectivity at the resist/substrate interface. Because, the probe light does not reflect off the resist surface and the intensity-loss at the resist surface is suppressed. With perfluoroalkylpolyether film, the measurement error isl .5%.

Chemically amplified resist processing with top coats for deep-ultraviolet and e-beam applications

“…[1][2][3][4][5] As critical dimensions in semiconductor manufacturing are approaching 250 nm and below, deep ultraviolet ͑UV͒ exposure tools operating at 248 nm are replacing those operating at i line wavelengths. With the use of deep UV exposure tools, comes a requirement for a different class of photoresist.…”

Optimal design of antireflective layer for DUV lithography and experimental results

“…The diagram consists of the right hand part of the complex plane in which the optical admittance is plotted as I Csub Nsub expression of the admittance 1m is more complicated, however, since it depends on overall optical properties of the system except for those of the incident region. It is well-known from the thin-film theory that the characteristic matrix of the system is given by (4) where [ is the optical admittance of the substrate and M denotes the characteristic matrix of each LNb layer. For convenience, the product of the characteristic matrices of upper layers is denoted as Mupr and that of lower layers as Miower .…”

Improving resist performance by PROMOTE processing

“…Metal layers are well known for these problems, while (poly)silicon layers become increasingly reflective when going from g-line to i-line and Deep UV. The use of anti-reflection coatings below (3) or on top of the resist (4,5) can reduce these problems at the cost of adding various process steps. The use of dyed resist is another way to reduce reflection problems.…”