Several thermal treatments in the temperature range from 270⁰C to 320⁰C (each of 10 min) were tested as a final preparation procedure of LiF:Mg,Cu,Si to improve the protocol of TL readout with less residual signal for the LiF:Mg,Cu, Si TLD. This high sensitivity LiF:Mg,Cu,Si TLD exhibited thermal stability much better than that of the well known LiF:Mg,Cu, P. For LiF:Mg,Cu, Si, a readout temperature up to 300⁰C did not affect the TL sensitivity and glow curve structure for 12 cycles of exposure and readout following an initial thermal treatment at 295 ⁰C for 10 min. The residual TL signal also remained negligible.