CN115747751A - A kind of silicon oxide preparation method - Google Patents

Abstract

The present invention relates to the technical field of photovoltaic module preparation methods, and specifically discloses a silicon oxide preparation method, which includes preparing a tunneling silicon oxide layer on a cleaned silicon wafer according to steps S1 to S14, and then preparing a doped polysilicon layer; wherein , steps S1 to S14 are as follows: carrying the cleaned silicon wafer carrier boat into the process chamber; evacuating, and raising the temperature, the temperature is 200° C. to 300° C.; purging with nitrogen; evacuating; injecting inert gas, and turning on the microwave, Gas flow 100-500sccm, duration 30-150s; vacuuming; nitrogen purge; vacuuming; oxidizing gas, gas flow 50sccm-200sccm, duration 10s-100s; vacuuming; nitrogen purge; hydrogen, and open Microwave, gas flow rate 100-500sccm, duration 30-150s; vacuum; nitrogen purge. The method proposed by the invention optimizes the silicon oxide preparation process by the PECVD method, can ensure the cleanliness of the surface of the silicon wafer before growing the tunneling silicon oxide layer, can passivate the dangling bonds in the silicon oxide, and obtain a high-quality tunneling silicon oxide layer.

Description

A kind of silicon oxide preparation method

technical field

The invention relates to the technical field of photovoltaic module preparation methods, and more specifically relates to a silicon oxide preparation method.

Background technique

In the preparation process of N-type Topcon battery, the key technology is to prepare an ultra-thin tunneling silicon oxide layer and a thin layer of highly doped polysilicon on the back of the battery, which together form a passivation contact structure. One of the currently commonly used preparation methods is the PECVD method. The process steps are: entering the boat, feeding oxidizing gas to prepare silicon oxide, vacuuming, feeding gas to prepare doped polysilicon layer, taking out the boat, cleaning and vacuuming. One of the key steps in the above process steps is the preparation of the silicon oxide layer. The general method is that after the silicon wafer is cleaned, it is loaded into the carrier boat by the automatic manipulator, and the carrier boat carrying the cleaned silicon wafer enters the process chamber, and after vacuuming and heating up to the process temperature, the oxidizing gas is introduced. grow silicon oxide. After the silicon oxide growth process is completed, a subsequent doped polysilicon layer preparation process is performed.

In actual production, the silicon wafer cleaning process and the tunneling silicon oxide layer preparation and polysilicon layer doping process are two different processes, which are completed by different equipment. After the silicon wafer is cleaned, it needs to wait for a period of time in the air environment, which will cause contamination on the surface of the silicon wafer and produce a natural oxide layer with extremely poor quality on the surface of the silicon wafer. After entering the process chamber, the oxidizing gas is directly introduced to prepare the silicon oxide layer, which cannot avoid the contamination and natural oxide layer on the surface of the silicon wafer, which are the reasons for affecting the passivation effect of the silicon wafer and reducing the conversion efficiency of the battery; in addition, because When silicon oxide grows, some Si on the silicon-silicon dioxide interface is not combined with oxygen atoms, and these recombination centers will also affect the passivation effect and reduce the conversion efficiency of the battery.

Contents of the invention

In view of this, the present application provides a silicon oxide preparation method, the purpose of which is to solve the problem that the poor quality of silicon oxide affects the passivation effect and thus affects the conversion efficiency of the battery when preparing the tunneling silicon oxide layer of the N-type topcon battery by PECVD.

In order to achieve the above object, the present invention provides the following technical solutions:

A method for preparing silicon oxide, comprising preparing a tunneling silicon oxide layer on a cleaned silicon wafer according to steps S1 to S14, and then preparing a doped polysilicon layer; wherein, steps S1 to S14 are:

S1. Carrying the cleaned silicon wafer carrier boat into the process chamber;

S2. Vacuumize and heat up, the temperature is 200°C to 300°C;

S3. Nitrogen purging;

S4. Vacuuming;

S5. Pass in inert gas, and turn on the microwave, the gas flow rate is 100-500sccm, and the duration is 30-150s;

S6. Vacuuming;

S7. Nitrogen purging;

S8. Vacuuming;

S9. Introduce the oxidizing gas, the gas flow rate is 50sccm~200sccm, and the duration is 10s~100s;

S10. Vacuuming;

S11. Nitrogen purging;

S12. Inject hydrogen gas and turn on the microwave, the gas flow rate is 100-500sccm, and the duration is 30-150s;

S13. Vacuumizing;

S14. Nitrogen purging.

Optionally, the inert gas in step S5 is argon.

Optionally, the oxidizing gas in step S9 is oxygen or nitrous oxide.

Optionally, the temperature in step S2 is controlled at 220°C-270°C.

Optionally, the temperature in step S2 is controlled at 255°C.

Optionally, the gas flow in step S5 is 200-380 sccm, and the duration is 60-120 s.

Optionally, the gas flow rate in the step S9 is 80-150 sccm, and the duration is 55-85 s.

Optionally, the gas flow rate in the step S12 is 210-360 sccm, and the duration is 55-110 s.

Compared with the prior art, the silicon oxide preparation method proposed by the present invention optimizes the silicon oxide preparation process by the PECVD method. After the carrier boat carrying the cleaned silicon wafer enters the process chamber, the inert gas is first introduced, and the inert gas is absorbed. After ionization, atoms or ionic groups bombard the surface of the silicon wafer to remove the contamination and natural oxide layer on the surface of the silicon wafer, and then pass through the oxidizing gas. After one-step oxidation is completed, pass through hydrogen for passivation treatment. This method can ensure the cleanliness of the silicon wafer surface before growing the tunneling silicon oxide layer, and the subsequent hydrogen passivation treatment can passivate the dangling bonds in the silicon oxide, thereby obtaining a high-quality tunneling silicon oxide layer and ensuring a good passivation effect , thereby increasing the conversion efficiency of the battery.

Detailed ways

The invention provides a method for preparing silicon oxide.

The technical solutions of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Apparently, the described embodiments are only some of the embodiments of the present application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

Embodiment one:

Embodiment 1 of the present invention provides a silicon oxide preparation method, which includes preparing a tunneling silicon oxide layer on the cleaned silicon wafer according to steps S1 to S14, and then preparing a doped polysilicon layer; wherein, steps S1 to S14 for:

S1. Carrying the cleaned silicon wafer carrier boat into the process chamber;

S2. Vacuumize and heat up, the temperature is 200°C to 300°C;

S3. Nitrogen purging;

S4. Vacuuming;

S5. Pass in inert gas, and turn on the microwave, the gas flow rate is 100-500sccm, and the duration is 30-150s;

S6. Vacuuming;

S7. Nitrogen purging;

S8. Vacuuming;

S9. Introduce oxygen, the gas flow rate is 50sccm~200sccm, and the duration is 10s~100s;

S10. Vacuuming;

S11. Nitrogen purging;

S12. Inject hydrogen gas and turn on the microwave, the gas flow rate is 100-500sccm, and the duration is 30-150s;

S13. Vacuumizing;

S14. Nitrogen purging.

Embodiment two:

Embodiment 2 of the present invention also provides a silicon oxide preparation method, which includes preparing a tunneling silicon oxide layer according to steps S1 to S14 after cleaning the silicon wafer, and then preparing a doped polysilicon layer; wherein, steps S1 to S14 for:

S1. Carrying the cleaned silicon wafer carrier boat into the process chamber;

S2. Vacuumize and heat up, the temperature is 260°C;

S3. Nitrogen purging;

S4. Vacuuming;

S5. Introduce argon gas, and turn on the microwave, the gas flow rate is 235sccm, and the duration is 105s;

S6. Vacuuming;

S7. Nitrogen purging;

S8. Vacuuming;

S9. Inject nitrous oxide, the gas flow rate is 105sccm, and the duration is 70s;

S10. Vacuuming;

S11. Nitrogen purging;

S12. Introduce hydrogen, and turn on the microwave, the gas flow rate is 275sccm, and the duration is 85s;

S13. Vacuumizing;

S14. Nitrogen purging.

Working principle and technical effect of the embodiment of the present invention:

The ultimate purpose of the embodiments of the present invention is to improve the quality of the tunneling silicon oxide layer, improve the passivation effect, and thus increase the conversion efficiency of the cell. Specifically: after the carrier boat carrying the cleaned silicon wafer enters the process chamber, the process chamber is evacuated, and after the heating step, the inert gas is first introduced, and the inert gas is ionized to bombard the surface of the silicon wafer, and the silicon wafer The contamination on the surface and the natural oxide layer are cleaned; after that, the steps of vacuuming, nitrogen cleaning, and vacuuming are carried out again, and then an oxidizing gas is introduced for oxidation; after the oxidation is completed, hydrogen is injected to passivate the interface dangling bonds. After the above steps are completed, subsequent preparation of the doped polysilicon layer is carried out.

The embodiment of the present invention adds two main steps altogether:

Step 1: After the carrier boat carrying the cleaned silicon wafer enters the PECVD process chamber, the temperature is raised. After the pipeline is cleaned, the inert gas (argon) is first introduced, and the microwave is turned on. Under the action of microwave, the argon gas is ionized, and the ionized argon atoms bombard the surface of the silicon wafer, effectively removing the contamination attached to the surface of the silicon wafer and the growing natural oxide layer, and obtaining a clean silicon wafer surface.

Step 2: After the silicon oxide is prepared, hydrogen gas is introduced and the microwave is turned on. Under the action of microwaves, hydrogen is ionized, and after hydrogen ions/atomic groups pass through silicon oxide, the dangling bonds on the silicon-silicon oxide interface are passivated.

The first step removes the contamination on the surface of the silicon wafer and the natural oxide layer with high defect density; the second step is to passivate the dangling bonds at the silicon-silicon oxide interface. Using the two steps, a high-quality tunneling silicon oxide layer is obtained, the passivation effect is improved, and the cell conversion efficiency is improved.

In the description of this application, unless otherwise clearly specified and limited, the terms "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense, for example, it can be a fixed connection or a fixed connection. Disassembled connection, or integration; it can be mechanical connection or electrical connection; it can be direct connection or indirect connection through an intermediary, and it can be the internal communication of two components or the interaction relationship between two components.

The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the application. Thus, the present application is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The foregoing description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the application to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

The above is only a preferred embodiment of the application, and is not intended to limit the application. Any modifications, equivalent replacements, etc. made within the spirit and principles of the application shall be included in the protection scope of the application. within.

Claims (8)

1. A method for preparing silicon oxide, characterized in that, comprising preparing a tunneling silicon oxide layer on the cleaned silicon wafer according to steps S1 to S14, and then preparing a doped polysilicon layer; wherein, steps S1 to S14 are : S1. Carrying the cleaned silicon wafer carrier boat into the process chamber; S2. Vacuumize and heat up, the temperature is 200°C to 300°C; S3. Nitrogen purging; S4. Vacuuming; S5. Pass in inert gas, and turn on the microwave, the gas flow rate is 100-500sccm, and the duration is 30-150s; S6. Vacuuming; S7. Nitrogen purging; S8. Vacuuming; S9. Introduce the oxidizing gas, the gas flow rate is 50sccm~200sccm, and the duration is 10s~100s; S10. Vacuuming; S11. Nitrogen purging; S12. Inject hydrogen gas and turn on the microwave, the gas flow rate is 100-500sccm, and the duration is 30-150s; S13. Vacuumizing; S14. Nitrogen purging. 2. The silicon oxide preparation method according to claim 1, characterized in that, the inert gas in the step S5 is argon. 3 . The silicon oxide preparation method according to claim 1 , wherein the oxidizing gas in the step S9 is oxygen or nitrous oxide. 4 . 4. The silicon oxide preparation method according to claim 1, 2 or 3, characterized in that the temperature in the step S2 is controlled at 220°C-270°C. 5. The method for preparing silicon oxide according to claim 4, characterized in that the temperature in the step S2 is controlled at 255°C. 6 . The silicon oxide preparation method according to claim 4 , characterized in that, the gas flow rate in the step S5 is 200-380 sccm, and the duration is 60-120 s. 7 . The silicon oxide preparation method according to claim 4 , wherein the gas flow rate in the step S9 is 80-150 sccm, and the duration is 55-85 s. 8 . The silicon oxide preparation method according to claim 4 , characterized in that, the gas flow rate in the step S12 is 210-360 sccm, and the duration is 55-110 s.