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The Tempress diffusion system is a modular horizontal furnace designed to process silicon wafers as part of the manufacturing technology of semiconductor, optical, MEMS, and solar devices. LTO is formed by using a process called LPCVD, Low Pressure Chemical Vapor Deposition. Chemical vapor deposition forms thin films on the surface of a substrate by thermal decomposition and/or reaction of gaseous compounds. The desired material is deposited directly from the gas phase onto the surface of the wafer. The important factors are gas ratio, temperature, and pressure.

Tempress S1T2 - LTO 4"
Equipment Details
Technology LPCVD
Materials Restriction CMOS Clean
Sample Size 100mm
Gases Used N2, O2, SiH4
Equipment Manual
Overview System Overview
Operating Procedure SOP
Supported Processes LTO
Maintenance Maintenance



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System Overview

Hardware Details

  • N2 - Maximum flow 1 slpm
  • N2 - Maximum flow 10 slpm
  • O2 - Maximum flow 500 sccm
  • SiH4 - Maximum flow 100 sccm

Substrate Requirements

  • Silicon only
  • Can process up to 25, 100 mm (4") wafers
  • Wafer thickness, ~525um for 100mm (4")
All samples must go through the RCA Pre-Furnace clean procedure before being processed in the furnace

Material Restrictions

The Tempress S1T2 - LTO 4" is designated as a CMOS Clean class tool. Below is a list of approved materials for the tool. Approved means the material is allowed in the tool under normal circumstances. If a material is not listed, please create a helpdesk ticket or email for any material requests or questions.

Supported Processes

  • LTO - Low temperature oxide

Process Details

Characterization Data

Standard Operating Procedure

Checkout Procedure

  1. Create a Help desk Ticket requesting training.
  2. LNF staff will schedule a time for initial training. After completing training the user can attempt a checkout session. It may be necessary for some users to participate in more than one training session, prior to attempting check out.
  3. Schedule a checkout session with a tool engineer via the existing Helpdesk ticket. If this checkout is successful, the engineer will authorize you on the tool.


  • Maintenance is performed on the tool, after 30-40µm of accumulated deposition.
  • Maintenance consists of replacing the following quartz parts within the tube.
    • Cage
    • Twin rods
    • Bridge for twin rods
    • Thermocouple sheath
    • SiH4 injector
    • O2 injector
    • Dummy wafers
  • Tube is replaced at 100µm of accumulated deposition.