| 摘要 |
A method of forming contact holes in either a positive radiation sensitive layer, such as positive photoresist, or a negative radiation sensitive layer, such as negative photoresist, using three exposures is described. The sum of the three exposure doses is equal to that required to expose the entire radiation sensitive layer. The allowable contact hole locations are at the intersection of a first array of parallel regularly spaced lines and a second array of parallel regularly spaced lines. The lines are exposed in two separate exposures. For the positive radiation sensitive layer the contact holes are partially exposed by these exposures. For the negative radiation sensitive layer the contact holes remain unexposed by these exposures. The third exposure uses a pattern mask to either fully expose the contact holes in the positive radiation sensitive layer or leave them unexposed in the negative radiation sensitive layer. The radiation sensitive layer is then developed and the contact holes are formed.
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