Solar cell crystal silicon wafer phosphorus diffusion method

Abstract

The invention discloses a solar cell crystal silicon wafer phosphorus diffusion method. The method comprises the following steps: 1) a to-be-processed crystal silicon wafer is placed in a diffusion furnace, temperature is raised, and nitrogen carrying a phosphorus source, dry oxygen and large nitrogen are introduced, constant-source diffusion is carried out; 2) introduction of the nitrogen carrying the phosphorus source is stopped, temperature is raised, the dry oxygen and the large nitrogen are introduced to perform propelling; 3) the nitrogen carrying the phosphorus source and the dry oxygen are introduced, and low-temperature diffusion is carried out; 4) the introduction of the nitrogen carrying the phosphorus source is stopped, and constant-temperature propelling is carried out; 5) temperature is raised, the nitrogen carrying the phosphorus source and the dry oxygen are introduced, and constant-source diffusion is carried out; 6) the introduction of the nitrogen carrying the phosphorus source is stopped, and oxygen-existing limited-source diffusion is performed; 7) temperature is lowered, the nitrogen carrying the phosphorus source, the dry oxygen and the large nitrogen are introduced, and cooling diffusion is carried out; and 8) temperature is lowered, and the crystal silicon wafer is taken out from a boat. The phosphorus diffusion method is simple and is easy to do, and the phosphorus diffusion method is widely used; and photoelectric conversion efficiency of the silicon wafer can be effectively improved through adoption of the method, electric performance of a solar cell is improved, and the phosphorus diffusion method is suitable for promotion and application.

Description

technical field [0001] The invention relates to the field of solar cell diffusion and junction fabrication technology, in particular to a phosphorous diffusion method for solar cell crystalline silicon wafers. Background technique [0002] A solar cell is a device that directly converts light energy into electrical energy. Because it is clean, non-polluting, inexhaustible and inexhaustible, it has gradually become an important power generation method. The principle is to use the photovoltaic effect of the PN junction to convert light energy into electrical energy. At present, silicon solar cells are widely used, and its manufacturing process has also been standardized. The main steps are: chemical cleaning and surface structuring (texturing)—diffusion junction—etching cleaning—deposition of anti-reflection film—printing electrodes—sintering. Among them, the step of diffusion junction (usually phosphorus diffusion junction) is a key step, and the junction process has a cruci...

AI Technical Summary

Problems solved by technology

However, if the proportion of the source-carrying gas is too small, the mixing of the diffusion atmosphere will be insufficient and uneven, resulting in poor uniformity of sheet resistance and poor process controllability

[0004] In addition, for the tubular diffusion furnaces currently widely used in production, the main factors affecting the inhomogeneity between the plates are: unbalanced temperature distribution in the axial direction, mismatching of gas in and out, and serious heat dissipation at the furnace mouth; affecting the inhomogeneity in the plate The main reason is that there are differences in the atmosphere environment and temperature field along the radial direction

Therefore, in the case of insufficient and uneven mixing of the diffusion atmosphere, if only relying on the method of temperature compensation in different temperature zones, it is obviously far from being able to achieve an ideal uniform diffusion state, which will eventually affect the controllability of subsequent process parameters and the performance of solar cells. electrical properties