Abstract: Divots (35, 36) may particularly be a problem for isolation trenches (22, 24) that are shallow. These divots (35, 36) may have a negative impact on the performance of the integrated circuit (49). Densification heating may be used to reduce the size and/or depth of these divots (35, 36) during manufacturing. For example, densification heating may be done at a temperature of at least 1100 degrees Celsius for at least 10 minutes after filling the isolation trenches (22, 24) with dielectric material (30). This densification heating may improve the variation in threshold voltages of transistors (e.g. 48) on an integrated circuit (49), particularly SOI (silicon on insulator) devices. SRAM cells (50) in particular may benefit from this densification heating.