In this post, two unique five-layer structures will be discussed. The first five-layer structure is nitride/oxide/silicon/oxide/nitride (NOSON) with the deposition order from bottom to top. In this structure, the silicon film is 25nm while the nitride and oxide are both 15nm. After etching the substrate, the membrane was RTP annealed at 1000C for 1 minute….
In this post, we’ll discuss a little bit about how would the deposition temperature affect the pore formation and pore morphology. I first show some previous results of the effect of deposition temperature on the porosity and pore size from Dave. From this plot, it shows that the relative low deposition temperature barely affects the…
In this post, I sum up all the NSN stacks with different Si thicknesses I have made so far. The nitride layer is 30nm thick for both the top and the bottom. The thickness for silicon film ranges from 7nm to 10nm, 15nm, 25nm, 50nm and 100nm. All the wafers were firstly etched and then…
From the past experiments we know that it is not easy to form pores in thicker silicon layer. It is mainly because that higher energy is required to form open holes in a thicker silicon film. Dave showed us less but bigger pores were formed in a 50nm thick silicon film after annealing. According to…
A few weeks ago, I did some RTP annealing of NSN and OSO stacks. The purpose of this annealing experiment was hoping to capture the onset of pore formation and see whether there is any different behavior between NSN and OSO stacks. The annealing temperature was set to 700C. The ramp rate was 50C/s all…
In this post, I’ll mainly focus on the furnace annealing results of OSO stacks. The structure of the OSO stack is also 30-25-30, which corresponding to 25nm thick silicon layer and 30nm thick oxide layers. The annealing temperature ranges from 600C to 1000C with a 100C interval. Each sample was annealed for 30 minutes. The…
I have done some furnace annealing (FA) on free-standing NSN and OSO stacks in last two weeks after the RTP was down. I’ll show the results in the following two posts. In order to compare the annealing result, I chose both NSN and OSO stacks with the same structure of 30-25-30, which corresponding to 25nm…
Last time I showed that the sample with multi-annealing yielded higher porosity and larger average pore diameter than the sample with direct annealing. In this post, I further investigate the multi-annealing of free standing OSO stack (20/15/10) by varying the pre-annealing time. The heat treatment process is illustrated in the following figure. Free standing OSO…
It is well believed that the pore formation is directly related to the silicon crystallization. In this post, I’m gonna further show that how does the crystallization process affect the pore formation. The crystallization process can be divided into two stages. The first one is the nucleation of silicon atoms. In this stage, crystal nuclei…
We have suspected that those non-open pores in the TEM image of pnc-Si are pits in the silicon membrane for a long time. Last week, I SEMed a sample, oxide (30nm)/Si(25nm)/oxide(30nm) annealed at 800C for 1min, to verify the pits features. The first figure is a TEM image which the majority feature looks like non-open…