A method for depositing a coating on a quartz boat to solve the problem of high points on the back side of polycrystalline

Abstract

The invention discloses a method for depositing a coating on a quartz boat to solve the problem of high points on the back side of polycrystalline. The method uses a low-pressure chemical vapor deposition method of a vertical LPCVD furnace to deposit silicon nitride under the conditions of a deposition temperature of 600-800°C, an ammonia (NH3) flow rate of 100-500 SCCM, a dichlorosilane (DCS) of 20-100 SCCM, a deposition pressure of 0.1-1 Torr, and a deposition rate of 10-30 angstroms / min. When depositing silicon nitride, a monitoring piece is simultaneously loaded on the quartz boat. The monitoring piece is subjected to a silicon nitride deposition process for a duration of greater than or equal to 100 minutes. The monitoring piece is deposited to a certain thickness of greater than or equal to 2000 angstroms. The method can solve the problem of high points on the back side of polycrystalline silicon wafers. The method can replace silicon carbide boats and break through the problem of the ban on the purchase of foreign silicon carbide boats in China.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method for depositing a coating on a quartz boat to solve the problem of high points on the back side of a polycrystalline. Background Art

[0002] After trench etching in the process flow of semiconductor power devices, a certain thickness of polycrystalline needs to be deposited to fill the trench according to the width and depth of the trench. There is a gap between the back of the silicon wafer and the contact point of the quartz boat teeth of the wafer carrier. During the deposition process, the gap between the two is filled with polycrystalline. After the process is completed, when the equipment robot takes the wafer, the polycrystalline adheres to the back of the contact point with the boat teeth to form a high point on the back (such as Figure 1 As shown in the figure, the thicker the deposition thickness, the more serious the problem of high polycrystalline points on the back side, and the flatness of the silicon wafer decreases, resulting in the inability to make wafers in the next process. The industry generally uses silicon carbide boat carriers, and there is no problem of high polycrystalline points on the back side during polycrystalline deposition. However, foreign countries restrict the sales of SIC products to domestic silicon wafer companies involved in military products, which seriously affects production. Summary of the invention

[0003] The purpose of the present invention is to provide a method for depositing a coating on a quartz boat to solve the problem of high points on the back side of polycrystalline. In order to break the limitation, under the existing conditions, the following invention method is proposed to solve the problem of high points on the back side of polycrystalline silicon wafers.

[0004] In order to achieve the above objectives, the following technical solutions are provided:

[0005] A method for depositing a coating on a quartz boat to solve the problem of high points on the back side of polycrystalline, the method comprising: using a vertical LPCVD furnace for low-pressure chemical vapor deposition to deposit silicon nitride at a certain deposition temperature, a certain ammonia (NH3) flow rate, a certain dichlorosilane (DCS), a certain deposition pressure and a certain deposition rate; while depositing silicon nitride, a monitoring sheet is simultaneously loaded on the quartz boat, and the silicon nitride deposition process is continued for a certain period of time to deposit a certain thickness on the monitoring sheet.

[0006] Preferably, the deposition temperature of the silicon nitride deposition process module is 600-800°C.

[0007] Preferably, the ammonia (NH 3 ) flow rate range is 100-500 SCCM.

[0008] Preferably, the dichlorosilane (DCS) is used in an amount of 20-100 SCCM.

[0009] Preferably, the deposition pressure is in the range of 0.1-1 Torr.

[0010] Preferably, the deposition rate ranges from 10 to 30 angstroms / min.

[0011] Preferably, the deposition time is greater than or equal to 100 min.

[0012] Preferably, the deposition thickness is greater than or equal to 2000 angstroms.

[0013] The beneficial effects of the present invention are:

[0014] The method of the invention can solve the problem of polycrystalline high points on the back of silicon wafers. By using this method, silicon carbide boats can be replaced, thus breaking through the problem of domestic purchase ban of foreign silicon carbide boats. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of a high point on the back side of a polycrystalline in the background technology of the present invention;

[0016] Figure 2 Detailed process step parameter table of an embodiment of the present invention;

[0017] Figure 3 A statistical summary data table of the boat deposition thickness corresponding to the back high points of the embodiment of the present invention;

[0018] The reference numerals shown in the figure are: 1-silicon wafer, 2-contact point. DETAILED DESCRIPTION

[0019] The following is a detailed description of this design scheme.

[0020] A method for depositing a coating on a quartz boat to solve the problem of high points on the back side of polycrystalline, the method comprising: using a vertical LPCVD furnace for low-pressure chemical vapor deposition, depositing silicon nitride under the conditions of a deposition temperature of 600-800°C, an ammonia (NH3) flow rate of 100-500 SCCM, a dichlorosilane (DCS) range of 20-100 SCCM, a deposition pressure range of 0.1-1 Torr, and a deposition rate range of 10-30 angstroms / min; while depositing silicon nitride, a monitoring sheet is simultaneously loaded on the quartz boat; the monitoring sheet is subjected to a silicon nitride deposition process for a duration of greater than or equal to 100 minutes, and a certain thickness greater than or equal to 2000 angstroms is deposited on the monitoring sheet.

[0021] Example

[0022] An 8-inch vertical LPCVD furnace was used for low-pressure chemical vapor deposition. A to I boats were equipped with monitoring samples to carry out polycrystalline deposition of 12,000 angstroms, the thickest process in the existing process. Silicon nitride deposition was carried out under the conditions of deposition temperature of 600-775°C, ammonia (NH3) flow rate of 200 SCCM, dichlorosilane (DCS) of 45 SCCM, deposition pressure of 0.15 Torr and deposition rate range of 10-30 angstroms / min. The deposition durations of A to I boats were 25 min, 50 min, 75 min, 100 min, 12 The monitoring piece was subjected to silicon nitride deposition process for 5min, 150min, 200min, 250min and 300min (see Table 1 for detailed process step parameters), a certain thickness was deposited on the monitoring piece, and the thickness of the monitoring piece was tested after the deposition was completed to confirm that the thickness of the quartz boat met the required thickness. After the deposition process was completed, the piece was taken out to observe the polycrystalline high points on the back of the monitoring sample (the statistical summary of the boat deposition thickness corresponding to the back high points is shown in Data Table 2). It was found that when the quartz boat deposited silicon nitride for 100min or more and the thickness was more than 2000 ng / cm3, there was no polycrystalline high point problem on the back of the corresponding monitoring sample.

Claims

1. A method for depositing a coating on a quartz boat to solve the problem of high points on the back side of polycrystalline, characterized in that: The method comprises: using a vertical LPCVD furnace to perform low-pressure chemical vapor deposition to deposit silicon nitride at a certain deposition temperature, a certain ammonia (NH3) flow rate, a certain dichlorosilane (DCS) flow rate, a certain deposition pressure and a certain deposition rate; a quartz boat is loaded with a monitoring sheet while depositing silicon nitride; the monitoring sheet is subjected to a silicon nitride deposition process for a certain period of time, and a certain thickness is deposited on the monitoring sheet; The deposition temperature of the silicon nitride deposition process module is 600-800° C.; The ammonia (NH3) flow rate range is 100-500 SCCM; The flow rate range of dichlorosilane (DCS) is 20-100 SCCM; The deposition pressure is used in the range of 0.1-1 Torr; The deposition rate range is 10-30 angstroms / min; The deposition time is 100-200 min; The required deposition thickness is 2000-4000 angstroms.

Images