A method to improve hto thickness stability

Abstract

The invention discloses a method for improving HTO thickness stability. In the furnace tube HTO machine table normal technological process, when the accumulated film thickness reaches a certain numerical value, a new circulation cleaning form automatically runs, a high-low temperature / pressure simultaneous switching manner is adopted in the new circulation cleaning form, under the high pressure and high temperature condition, different vapor pressures are used for converting chlorine containing by-products into gaseous state matter to be brought out, and the effective removing effect is achieved. By means of the method, the by-products at the bottom of a technological cavity can be effectively removed, and the machine table film forming technological thickness stability is guaranteed.

Description

technical field [0001] The invention relates to the field of semiconductor integrated circuits, in particular to a method for improving the thickness stability of an HTO (low-pressure high-temperature silicon oxide deposition furnace). Background technique [0002] The process corresponding to the low-pressure furnace tube HTO machine belongs to the film forming process. With the increase of the accumulated film thickness, the internal environment of the furnace tube process chamber gradually becomes unstable, resulting in process fluctuations. combine figure 1 As shown, the main performance is that 6 by-products (chloride ions 7) accumulate continuously at the bottom of the process chamber, which affects the key parameter of the film forming process itself-film thickness, resulting in a gradual decrease in the thickness of the product silicon wafer at the bottom position, and gradually deviates from the When the target value is serious, the thickness will exceed the contro...

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Problems solved by technology

[0003] The existing cycle cleaning program is to take away the source of particles in the process chamber and on the wafer boat through multiple vacuuming methods in a high-temperature environment to improve the particle condition in the internal environment of the process chamber, and cannot solve the accumulation of by-products in a targeted manner Effect on Thickness

[0004] Due to the film-forming process corresponding to the low-pressure furnace tube HTO machine, with the increase of the cumulative film thickness, by-products (chloride ions) will inevitably accumulate at the bottom of the process chamber, which will cause fluctuations in the film-forming thickness at the bottom, resulting in product Wafer thickness gradually deviates from the target value

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