IC Knowledge - Glossary

Glossary of Integrated Circuit Terminology - T

Tape Automated Bonding (TAB) - metal conductors mounted to Mylar tape, bonded to gold bumps on die. The Mylar tape is held on reels and TAB bonded die may be automatically placed onto PC boards very efficiently.
Target - the metal source for a sputtering process. Targets are most commonly round-thick pieces of metal larger in diameter than the wafers on which the metal will be deposited. Targets are specially shaped to optimize deposition uniformity.
TCA - see Trichloroethane
TCE - see Trichloroethylene
Temporal Coherence - the relationship between the wavelength of a light source and the bandwidth of the light source. Temporal coherence is characterized by the coherence length.
Test Wafers - wafers that are processed through part or all of a fabrication sequence and then used to measure the results of the processing. Test wafers are discarded or reclaimed after use and not shipped.
TFT - see Thin Film Transistor.
Thin Film Transistor - transistors formed in polycrystalline or amorphous silicon layers. Thin film transistor have relatively poor performance compared to transistors fabricated in crystalline silicon. This film transistors are used in certain types of SRAMs.
Thermal Compression Bonding - wire bonds formed through a combination of pressure and temperature.
Thin films - films with thickness less than approximately 100 microns.
Three-Five Compound - III-V Compound - compound semiconductors made up of group III and group V elements.
Threshold - the minimum level to effect a change.
Threshold Limit Value (TLV) - the maximum permissible concentration of a substance typically expressed in ppm that a worker may be exposed to for 8 hours (sometimes 40 hours). TLV is a legally mandated safety limit.
Threshold Voltage - the voltage required to switch a MOSFET from a blocking state to a conducting state.
Throughput - the number of units completed through a process per unit time.
Thyristor - a type of semiconductor device where 4 layers form 3 PN junctions. Thyristors are very efficient devices for switching large AC signals but latch-on until the signal passes through zero making them unsuitable for DC switching.
Titanium Nitride - a compond of titanium metal and nitrogen gas (TiN), titanium nitride is very inert and serves as an excellent barrier metel. Titanium nitride has a resistivity of 21.7µohm-cm, a density of 5.43 g/cm³, a melting point of 2,930^oC, adheres well to diletrics, has poor wire bondability and is easy to pattern and etch.
TLV - see Threshold Limit Value
TO Package - Transistor Outline - a standard package for discrete transistors. There are a variety of different TO packages such as TO3, TO92, TO220, etc.
TOC - Total Organic Carbon - a measure of organic levels in ultrapure water. High TOC levels have been correlated with lower yields for semiconductors.
Torr - the pressure exerted by 1mm of mercury, Hg. Standard atmospheric pressure is 760 torr.
Toxic - a poisonous substance.
Trans LC - a more ozone friendly furnace cleaning chemical used as a replacement for TCA.
Transistor - a semiconductor device with three terminals where one terminal can be use to control the flow of current through the other two terminals.
Triac - a type of semiconductor device where 5 layers form 3 PN junctions in each of two directions. Triacs are equivalent to two thyristors in anti parallel.
Trichloroethane - chemical formula C₂H₃Cl₃, trichloroethane is a liquid at room temperature and was at one time widely used as a source of chlorine for furnace cleans. During the cleaning process, Nitrogen gas is bubbled through heated trichloroethane liquid. The nitrogen gas leaves the bubbler carrying vapor of trichloroethane into the furnace where it disassociates into carbon and chlorine. It is very important that sufficient oxygen is present during the cleaning process to suppress the formation of toxic phosgene gas. Trichloroethane vapor pressure ranges from approximately 30mm of Hg at 0^oC, 130mm of Hg at 25^oC to >350mm of Hg at 50^oC. The use of trichloroethane has now largely ended due to ozone depletion issues.
Trichloroethylene - chemical formula C₂HCl₃, trichloroethylene is a liquid at room temperature and was at one time widely used as a source of chlorine for furnace cleans. During the cleaning process, Nitrogen gas is bubbled through heated trichloroethylene liquid. The nitrogen gas leaves the bubbler carrying vapor of trichloroethylene into the furnace where it disassociates into carbon and chlorine. It is very important that sufficient oxygen is present during the cleaning process to suppress the formation of toxic phosgene gas. Trichloroethylene vapor pressure ranges from approximately 20mm of Hg at 0^oC, 75mm of Hg at 25^oC to 200mm of Hg at 50^oC. The use of trichloroethylene has essentially ceased due to the carcinogenic nature of trichloroethylene.
TSOP - Thin Small Outline Package - a common plastic package for IC's, particularly memory.
TTL - Transistor-Transistor Logic - a type of bipolar logic.
Tube - a quartz tube that fits into a furnace. The tube encloses the furnace boats and provides a controlled atmosphere for processing.
Twin Well - a process where two different types of wells are formed so that different types of devices may be fabricated. Typically one well will be N-type so that PMOS may be formed and one well will be P-type so that NMOS can be formed.
Two Step Diffusion - a diffusion where a pre deposition step is followed by a diffusion step. See Pre Deposition and see also Diffusion.
Type - type refers to whether silicon is N-type, having a majority of negative carriers, or P-type, having a majority of positive carriers.