Abstract: This present discloses a method for making a concave bottom oxide within a trench, the steps comprising: providing a semiconductor substrate; forming an insulating layer on the semiconductor substrate; defining the insulating layer to form an opening exposing the surface of the semiconductor substrate; dry-etching the exposed semiconductor substrate within the opening by using the first insulating layer as an etching mask to form a trench; depositing a first oxide layer conformably over the insulating layer, the side-walls and the bottom of the trench; depositing a second oxide layer on the first oxide layer and filling-up the trench surrounded by the first oxide layer; annealing to densify the first and second oxide layers; etching-back the first and second oxide layer to remove the portion overlying the first insulating layer, and forming a spacer consisting of the residual first oxide layer on the side-walls of the trench, and a concave bottom oxide consisting of the first and second oxide layers on the bo

Abstract: A method for determining a crack limit of a target film deposited on a wafer in production after a post annealing procedure is disclosed. The crack limit is determined by adopting and adjusting the thermal shrinkage rates of a plurality of target films deposited on bare wafers and annealed. The test results on bare wafers can be applied to the production wafers to prevent from film cracking and/or inspect instrumental conditions.

Abstract: A method for preventing a target film deposited on a wafer in production from cracking after a post annealing procedure is disclosed. The method is performed by previously determining a crack limit before the target film is deposited on the wafer in production. The crack limit is determined by adopting and adjusting the thermal shrinkage rates of a plurality of target films deposited on bare wafers and annealed. After the crack limit is determined, a system-adjusting step and a reconfirmation step are performed, if necessary, to make sure the system conditions determined by the test results on bare wafers are suitably applied to the production wafers to prevent from film cracking. Moreover, the instrumental conditions can be inspected and tuned accordingly.