CN-121985798-A - Gap filling method

Abstract

The application discloses a gap filling method. The gap filling method comprises the steps of placing a substrate with a gap in a deposition chamber, introducing mixed first carrier gas and reaction gas into the deposition chamber in a first deposition step to deposit an oxide film on the surface of the substrate, and introducing mixed second carrier gas and reaction gas into the deposition chamber in a second deposition step to continuously deposit the oxide film on the surface of the substrate, wherein the molecular weight of the first carrier gas is smaller than that of the second carrier gas. By alternately using two carrier gases, the filling efficiency is improved, meanwhile, the cracks of the film can be reduced, and the filling effect is obviously improved.

Inventors

• Xue Xianqiang
• TAN HAO
• FU CHENCHENG
• WU JIAN
• YAO JINGWEN

Assignees

• 江苏首芯半导体科技有限公司

Dates

Publication Date

20260505

Application Date

20260206

Claims (10)

1. 1. A gap filling method, comprising: Placing a substrate having a gap in a deposition chamber; introducing mixed first carrier gas and reaction gas into the deposition chamber in a first deposition step to deposit an oxide film on the surface of the substrate; introducing mixed second carrier gas and reaction gas into the deposition chamber in a second deposition step to continuously deposit the oxide film on the surface of the substrate, Wherein the molecular weight of the first carrier gas is smaller than the molecular weight of the second carrier gas.
2. 2. The gap filling method according to claim 1, wherein, The flow rates of the first carrier gas and the second carrier gas are the same, The reaction gases in each deposition step comprise an oxidant and a precursor, and the flow rate of the precursor in the first deposition step is the same as that in the second deposition step.
3. 3. The gap filling method according to claim 2, wherein a deposition time of the first deposition step is longer than a deposition time of the second deposition step.
4. 4. The gap filling method according to claim 3, wherein a deposition thickness of the oxide thin film in the second deposition step is less than/equal to 1.5 times a deposition thickness in the first deposition step.
5. 5. The gap filling method according to claim 4, wherein the first carrier gas is helium, the second carrier gas is argon, the oxidizing agent is oxygen, and the precursor is tetraethyl orthosilicate.
6. 6. The gap filling method according to claim 5, wherein, The flow rates of the first carrier gas and the second carrier gas are 2-8 standard liters per minute, The flow rate of the tetraethyl orthosilicate is 0.2-1 g/min, The flow rate of the oxidant mixed with the first carrier gas is 2-8 standard liters per minute, The flow rate of the oxidant mixed with the second carrier gas is 3-7 standard liters per minute.
7. 7. The gap filling method according to claim 5, wherein, The deposition time for a single said first deposition step is 250 seconds, The deposition time of a single said second deposition step is 200 seconds, In the single deposition step, the deposition thickness of the oxide film is 1-3 microns.
8. 8. The gap filling method according to any one of claims 1 to 7, wherein the gap filling method further comprises repeating the first deposition step and the second deposition step until gap filling is completed.
9. 9. The gap filling method according to any one of claims 1 to 7, wherein at least one of the first deposition step and the second deposition step comprises: removing the substrate after depositing the oxide film; cleaning the deposition chamber, and The substrate is repositioned in the deposition chamber.
10. 10. The gap filling method of claim 9, wherein each time the substrate is placed in the deposition chamber, the gap filling method further comprises preheating the substrate.

Description

Gap filling method Technical Field The application relates to the technical field of semiconductor manufacturing, in particular to a gap filling method. Background PECVD (PLASMA ENHANCE CHEMICAL Vapour Deposition, plasma enhanced chemical vapor deposition) is a low temperature thin film deposition technique combining plasma with conventional CVD (Chemical Vapour Deposition, chemical vapor deposition) to achieve high quality thin film growth by providing reactive activation energy by the plasma. PECVD technology is widely used in the fields of semiconductors, etc., and is one of the core processes of modern microelectronic fabrication. In semiconductor manufacturing processes, a PECVD technique is often used to perform gap filling (gap fill) of the substrate. In the gap filling process, the film contact of the side walls at the two sides of the gap is closed in advance due to the fact that the deposition rates of the bottom end and the side walls of the gap are different, and therefore follow-up particles are prevented from entering the gap. In the prior art, the problem of voids is often alleviated by either reducing the deposition rate or introducing a separate etching step, but the former sacrifices process efficiency and the latter is prone to wafer warpage and cavity contamination. Disclosure of Invention In view of the above problems, an object of the present application is to provide a gap filling method, which can improve the filling effect while ensuring the process efficiency. According to one aspect of the invention, a gap filling method is provided, wherein the gap filling method comprises the steps of placing a substrate with a gap in a deposition chamber, introducing mixed first carrier gas and reactive gas into the deposition chamber in a first deposition step to deposit an oxide film on the surface of the substrate, and introducing mixed second carrier gas and reactive gas into the deposition chamber in a second deposition step to continuously deposit the oxide film on the surface of the substrate, wherein the molecular weight of the first carrier gas is smaller than that of the second carrier gas. Optionally, the flow rates of the first carrier gas and the second carrier gas are the same, and the reactive gases in each deposition step comprise an oxidant and a precursor, and the flow rate of the precursor in the first deposition step is the same as the flow rate in the second deposition step. Optionally, the deposition time of the first deposition step is greater than the deposition time of the second deposition step. Optionally, the oxide film has a deposition thickness in the second deposition step of less than/equal to 1.5 times the deposition thickness in the first deposition step. Optionally, the first carrier gas is helium, the second carrier gas is argon, the oxidant is oxygen, and the precursor is tetraethyl orthosilicate. Optionally, the flow rates of the first carrier gas and the second carrier gas are both 2-8 standard liters per minute, the flow rate of the tetraethyl orthosilicate is 0.2-1 gram per minute, the flow rate of the oxidant mixed with the first carrier gas is 2-8 standard liters per minute, and the flow rate of the oxidant mixed with the second carrier gas is 3-7 standard liters per minute. Optionally, the deposition time of the single first deposition step is 250 seconds, the deposition time of the single second deposition step is 200 seconds, and the deposition thickness of the oxide film in the single deposition step is 1-3 micrometers. Optionally, the gap filling method further comprises repeating the first deposition step and the second deposition step until gap filling is completed. Optionally, at least one of the first deposition step and the second deposition step includes removing the substrate after depositing the oxide film, cleaning the deposition chamber, and repositioning the substrate in the deposition chamber. Optionally, the gap filling method further comprises preheating the substrate after each placement of the substrate in the deposition chamber. According to the gap filling method provided by the application, the first carrier gas has smaller molecular weight, the influence on the internal stress of the film is smaller, and the deposited film has fewer cracks. The second carrier gas has larger molecular weight, and a sputtering effect is generated in the deposition process, so that the problem of sealing in advance is effectively reduced. The second carrier gas with large molecular weight also has better longitudinal selectivity, and is more beneficial to improving the filling efficiency. In the process of alternately using two carrier gases, the dynamic trimming of the side wall of the gap can be realized without setting a separate etching step, the cavity defect caused by overgrowth of the side wall is avoided, the filling efficiency is improved, meanwhile, the cracks of the film can be reduced, and the filling effect is obviously improved. Draw