NDG-7000R & NDG-5000 – used successfully for the planarization of 200mm (8″) MEMS process.  “The hole filling ability of your SOG is quite good, and the surface roughness after spin coating of SOG is also low enough to our spec of Ra < 0.2 nm.  If the planarization process is the final step I think NDG 7000R can be used in our fabrication process”

 

NDG-2000 is being used in LCD (Liquid Crystal Display) processing for a indexing layer to reduce the spectral reflectance of the indium tin-oxide (ITO) electrodes as well as an environmental protection for ITO pads.  The SOG in the cell interior affects the specular reflectance of the LCD display products. It has also been shown that SOG  can also serve as an insulating or planarization layer.

 

B-1000 is being used in single junction solar cells processing as a carrier of the dopant of the p¯ and n¯ type regions of the solar cell device.  Using an n¯ type silicon wafer, the p¯ doping is for the emitter and the n¯ for the the n÷÷ contact to the base.

 

NDG-5000 used as a coating for a masking layer on on side of a wafer.

 

NDG-5000 is being used as a dielectric layer for transmission lines.

 

ZN-640 used in a QWIP (quantum well IR photo-detector) device for commercial applications.

 

SN-365 successfully used as a doping method in processing of MOSFETs devices on Ga2O3 substrates for source/drain effectiveness.  The SOG doping provided a simple, low cost (no ion implanter needed) effective way to make ohmic contact to lower doped Ga2O3 channel. Improved peak current density and peak trans-conductance is achieved with this method for a 2.0µm device.  The devices also showed large ON/OFF ratio and maintained a high breakdown voltage even after high temperature dopant drive in the anneal step.

 

NDG-5000/7000 used as a overcoat layer on PECVD SiO2 waive-guides to smooth out surface topography and act as a moisture barrier.  The measured optical throughput also improves vs. un-coated with SOG material. Refer to Optical Society of America Technical Digest 2015, paper jTH2A.29/CLEO Conference-2015, “Silicate Spin-On-Glass (SOG) as an Overcoat Layer for SiO2 Ridge Waveguides”


SOG Customer Application Questions & Answers

We would like to use your SOD as a source for dopants, we are currently interested in sources for B, P and As, and have some questions regarding that process:

1. Being a research facility, using the same tools for various processes we are cautious when introducing new materials in the clean-room. Therefore I would like to verify it is OK to use your SODs in the same spinner used for photoresists (with metal chuck and PP drain tubes). Particularly:
a. What (solvent?) can be used for spinner cleaning (IPA? we can’t use diluted HF). If utilized quickly, IPA or denatured alcohol can clean off SOG materials. Once dry however, dilute HF can be used but attacks metal surfaces and is not recommended.
b. Is that process a source of particulates. SOG is formed in an alkoxide reaction that occurs faster at higher temperatures or when exposed to air. For research purposed we utilize one dropper for each wafer. If dropper is used repeatedly for multiple wafers, particles will form on the sidewalls of the dropper which will get into the SOG material. As long as dispensing equipment is kept clean, particulates are not a problem.

2. How sensitive is the process to temperature, humidity and time variations between applying the SOD and starting the spin? If SOG is refrigerated when not in use, most materials will last over 1 year. For best coating consistancy, allow the SOG to come up to room temperature before dipensing. The heavier doped SOG materials are more sensitive to humidity and we recommend low humidity conditions for these materials. If moisture is absorbed onto the SOG film and fogs the film, this can translate to damage during the diffusion process. We generally flood the wafer 80% with SOG and then immediately spin at high acceleration for best film results.

3. Can you provide a reference process for each dopant, which is robust, repeatable and with proved uniformity (within wafer and wafer-to-wafer)?
Including all the parameters (Spin RPM, time bake temperature, predep time and Temp. and so on) for a shallow (deep) layer, from which we can start in order to achieve the profile we need. Yes, we have a process outline for each of our SOG materials.

4. Is the final distribution is Gaussian? It can be depending upon the diffusion conditions. There is a process modeling program that can be of immense use to you. The modeling link is: Fabweb.ece.uiuc.edu This will come up as ECEIllinois-ece444: Theory and Fabrication of Integrated………….Click on this to enter the modeling site, then click on the sub category “Calculators”. This will then give you several modeling options.

5. Do you have experience using RTP for predep? Our customers utilize both open tube diffusion and RTP processing. We would be happy to assist you with either process.

6. What material is used for masking, when want to apply SOD only to defined areas (is SiO2 / Si3N4 suitable for all dopants)? Typically thermal oxide is used for masking oxide for most semiconductor applications. However some designs/processes can utilize other masking materials including undoped SOG, PECVD or LPCVD materials.

7. Do you recommend PECVD SiO2 / Si3N4 layer to prevent out diffusion? (assuming the mask layer is thermal – LPCVD) If you are reffering to a capping layer over the SOG, it is not generally required. If you are referring to backside pretection to prevent a heavily doped backside outdiffusion or prevent SOG dopant outgassing to and affecting the back side, then a capping layer such as undoped SOG on the backside may be utilized.

8. Can you please send MSDS for your SODs (P/B/As)? Yes, a Desert Silicon representative will send the new SDS formatted guides to you today.

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