ECE_5360_lab__6 - Lab # 6: Sputter Deposition, Patterning...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Lab # 6: Sputter Deposition, Patterning and Annealing the Al Contacts In this lab, you will receive your wafers back with 3 process steps added after Lab #5. Recall that after Lab # 5, the contact holes were opened through the gate oxide. In the first two added process steps, the TAs have performed a wafer descum step, followed by a buffered oxide etch dip to remove the native oxide from the exposed silicon in the contact holes. This is done immediately prior to loading the wafers in the metallization system. In the third added step, the wafers are blanket coated with 1 micron of aluminum (with 1 % silicon added to improve morphology after annealing). You will notice the difference in appearance of the top side of your wafer. The only place where the aluminum touches the silicon is through the contacts holes opened in Lab # 5. The aluminum metallization must be patterned to isolate the device contacts - otherwise all surface contacts would be shorted together! For thin metal layers (< 300nm), this is typically done with a liftoff process. However, your metal layer is much thicker – about 1 micron. For thick layers like this, the standard photolithography procedures we’ve been doing all semester, followed by a wet etch, are more practical. Thus, you will apply photoresist on top of your wafer and pattern the resist with the mask aligner. Now mask Level 4 must be aligned to the pattern the aluminum metal. A new set of alignment aids and verniers will be used for this purpose. Once developed, the resist pattern on a transistor will be examined in relationship previous 3 Levels. Finally, the Level 3 to 4 alignment error will be measured (at the wafers center) using the appropriate verniers on the masks. Lab Preparation:(prior to entering lab) 1. Anticipate what the microscope images (Level 3 contact pattern + Level 4 resist pattern) on the transistor will look like. 2. Locate the correct sets of verniers for Level 4 placement accuracy (see Figure 2 from Lab #5). The verniers and alignment aids to be examined are labeled CONTACT METAL on the mask. 3. Go to the website,
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/04/2009 for the course ECE 5360 taught by Professor Shealy during the Fall '07 term at Cornell University (Engineering School).

Page1 / 6

ECE_5360_lab__6 - Lab # 6: Sputter Deposition, Patterning...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online