Multi-layer registration and dimensional test mark for scatterometrical measurement
A layered test pattern for measuring registration and critical dimension (CD) for multi-layer semiconductor integrated circuits is disclosed. A first layer includes a first pattern having vertical and horizontal portions. A second layer is formed over the first layer and includes a second pattern having vertical and horizontal portions having nominal vertical and horizontal phase shifts with respect to the vertical and horizontal portions, respectively, of the first pattern. The vertical and horizontal portions include periodically repeating vertical lines and horizontal lines, respectively. The nominal phase shifts may be half of the period of the vertical and horizontal lines. A scatterometry tool measures the width of the lines and the phase shift of the first pattern relative to the second pattern. The width of the lines corresponds to CD, whereas the difference between the measured phase shift and the nominal phase shift indicates variation in registration.
1. A layered pattern for evaluating layer properties, the layered pattern comprising:
a base layer;
a first layer deposited directly on the base layer, the first layer comprising a first pattern;
a second layer deposited over the first layer, the second layer comprising a second pattern having a phase shift relative to the first pattern and being substantially identical to the first pattern; and
wherein the first and second patterns each comprise a first vertical portion and a first horizontal portion; and
wherein the phase shift of the first vertical portion of the second pattern is in a horizontal direction relative to the first vertical portion of the first pattern, and wherein the phase shift of the first horizontal portion of the second pattern is in a vertical direction relative to the first horizontal portion of the first pattern.
2. The pattern of claim 1 , wherein the first vertical portion comprises periodically disposed vertical lines and wherein the first horizontal portion comprises periodically disposed horizontal lines.
3. The pattern of claim 1 , wherein the first and second patterns each further comprise a second vertical portion and a second horizontal portion.
4. The pattern of claim 3 , wherein the first and second vertical and horizontal portions of the first and second patterns are each disposed at the corners of a square.
5. The pattern of claim 4 , wherein the first and second vertical portions of the first and second patterns are disposed at adjacent corners of the square.
6. The pattern of claim 1 , wherein the base layer is a semiconductor wafer.
7. The pattern of claim 1 , wherein the first and second layers comprise a metal.