Last week, I calculated the Young’s modulus and residual stress of several different membranes using the pressure-displacement technique. The measurements were performed on at least three different geometries (square and rectangle) and the results were averaged. Wafer Thick. (nm) Por. (%) Anneal Res. Stress (MPa) Young’s modulus (GPa) 532 15 2.59 1000 sus 4.17 31.67…
In order to verify our measurement technique for the determination of Young’s modulus of pnc-Si, I decided to look at a PECVD silicon nitride membrane SiMPore is using for cell culture applications. The membrane window is 1 mm x 1 mm with 3 um holes. The Young’s modulus of silicon nitride thin films has been…
In my initial report on the Young’s modulus of pnc-Si, I used the generalized pressure-displacement equation to fit my experimental data to extract a Young’s modulus of around 100 GPa (Polysilicon is ~150 GPa). Unfortunately, there was quite a bit of variability in the residual stress in these experiments. I believe this variability was due…
I first reported the crystallization of free-standing amorphous silicon membranes in this post in January. The last experiment was done inside the susceptor (top and bottom piece). This week, I annealed a set of amorphous 15 nm and 30 nm with the susceptor top off. This allowed for the direct heating of the films. One…
As a follow up to my 15 nm post-Si deposition Ar sputter experiment, I fabricated a set of six wafers with 30 nm Si films this week: three with the Ar sputter process and three without. I annealed these at 1000, 1050 and 1100 C with a ramp rate of 100 C/s for 60 s….
Recently, I have been exploring the temperature dependence of post-Si deposition Ar sputtered films (15 nm thick). Below is a comparison of the average pore size, porosity, and density of pores of Ar and non-Ar sputtered films annealed between 800 C and 1100 C. It appears that Ar sputtering increases the avg. diameter and porosity…
A simple experiment that has never been done is to make a direct comparison between annealing inside and outside the susceptor. Intuitively, we would expect the morphologies to be quite different since the heating mechanism is different for both cases. Inside the susceptor, the film is heated through blackbody radiation from the susceptor. Without the…
Today I deposited two 30 nm thick Si films and annealed one at 1000 C for 1 min and the other at 1000 C for 5 min. My running hypothesis is that performing an Ar sputter after the silicon deposition creates “broken” bonds that seed crystallization. Therefore, the crystallization should nucleate at the interface and…
In a continuing study on how a post-silicon deposition Ar sputter affects morphology, I annealed three 15-nm films for 10 s, 60 s, and 300 s. If you recall in my first report, I found that the Ar sputter increases the porosity slightly for a 1000 C RTP and dramatically for a 900 C RTP….
I’ve always suspected that the pore formation process was very quick and to confirm this I looked at a wafer that was annealed for 10 s vs. 60 s. From the distributions, it would appear that the majority of pores nucleate and grow during the ramp and first few seconds of steady state. Next, I…