A BPSG thin film, its preparation process and a single-chamber multi-wafer PECVD device

Abstract

The present invention provides a BPSG thin film, a preparation process thereof, and a single-chamber multi-wafer PECVD device, belonging to the field of semiconductor technology. The preparation process includes the following steps: in a single-chamber multi-wafer PECVD device, placing a plurality of wafers on different carriers; introducing a precursor source into the chamber and stabilizing it under a first condition; the precursor source includes a silicon source precursor, a boron source precursor, and a phosphorus source precursor; pre-deposition: performing pre-deposition on the surface of the wafer under a second condition to form a BPSG pre-deposited thin film; the second condition includes: 300 sccm < Q B2 < Q B3 , 0 < t < 5 s; main deposition: continuing to deposit on the surface of the BPSG pre-deposited thin film under a third condition; after the main deposition is completed, post-treatment is performed, and then the deposited BPSG thin film is taken out. The present invention avoids the delamination phenomenon of the BPSG thin film, greatly improves the yield of semiconductor devices and the competitiveness of the single-chamber multi-wafer PECVD device.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and particularly relates to a BPSG thin film, a preparation process thereof, and a single-chamber multi-wafer PECVD device. Background Art

[0002] In PECVD (Plasma Enhanced Chemical Vapor Deposition) technology, reaction gases are introduced into a vacuum chamber, and then plasmas are generated by means such as radio frequency (RF). High-energy electrons in the plasmas collide with reaction gas molecules, causing the gas molecules to dissociate and be excited, generating a large number of active particles such as atoms, ions, and free radicals. These active particles undergo chemical reactions on the surface of the substrate to form a thin film. The PECVD process is widely used in the field of semiconductor manufacturing, mainly for depositing thin films of various semiconductor memory devices. For example, CN115287630A discloses a semiconductor device manufacturing apparatus and a manufacturing method. The apparatus includes a gas pipeline, a gas optimization system, and a reaction chamber; the gas pipeline includes a plurality of gas inlet pipelines; a radio frequency matcher, a gas distribution plate, a wafer tray, and a gas discharge part are arranged in the reaction chamber from top to bottom; a plurality of gas inlets are connected to the gas mixing and optimization system; the gas optimization system is arranged outside the reaction chamber; the gas mixing and optimization system includes a gas stirring device and a gas filtering device. Although this technology can achieve uniform distribution of multiple paths of gases, only one wafer can be deposited with a thin film at a time, and multi-line operations cannot be performed simultaneously.

[0003] In a single-chamber multi-wafer PECVD (plasma enhanced chemical vapor deposition) device, multiple substrates can be processed at the same time, and multiple BPSG (boron phospho-silicate glass) films can be prepared in one operation. Compared with a single-chamber single-wafer PECVD device, more products can be produced per unit time, which effectively improves production efficiency, meets the needs of large-scale production, and reduces equipment investment and costs. For example, patent CN102560422A discloses a multi-chip remote plasma enhanced atomic layer deposition chamber, including a vacuum chamber, wherein a sample rack capable of placing multiple samples is installed in the vacuum chamber, a heating ring is provided on the periphery of the sample rack in the vacuum chamber, and a heat reflecting plate is connected to the side of the heating ring close to the chamber wall; an air inlet pipe is provided between the sample rack and the heating ring in the vacuum chamber, and the air inlet pipe is provided with an air outlet section at the same spatial height as the sample rack; an air uniforming ring is provided on the periphery of the heat reflecting plate in the vacuum chamber, and an air exhaust port is opened on the bottom of the vacuum chamber between the air uniforming ring and its side wall, and the air exhaust port and the air inlet pipe are arranged on both sides of the sample rack; a remote pulse plasma generating system is connected to the vacuum chamber, and the remote pulse plasma generating system includes a quartz tube connected to the bottom of the vacuum chamber, an induction coil is wound around the quartz tube, and a pulsed radio frequency power supply and an impedance matching system are connected to the induction coil in sequence. This patent can grow thin films on multiple substrates. However, due to differences in gas concentration, flow rate, etc. at different substrate locations, the plasma density and energy distribution in the chamber are uneven, resulting in different degrees of plasma bombardment on wafers on different substrates. This leads to different growth rates of the thin films, which makes it easy for stratification to occur during multiple film formation processes, and in turn leads to inconsistent etching rates of the thin films. In subsequent photolithography processes, severe distortion of the graphics may even occur, affecting yield performance.

[0004] Therefore, how to optimize the preparation process of BPSG films in single-chamber multi-wafer PECVD equipment to reduce stratification, thereby improving the yield of semiconductor devices and the competitiveness of single-chamber multi-wafer PECVD equipment, is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a BPSG film and a preparation process thereof and a single-cavity multi-chip PECVD device. The present invention performs pre-deposition on the wafer surface before the main deposition, and sets the pre-deposition parameters to meet specific conditions, thereby greatly avoiding the delamination of the BPSG film, helping to improve the etching uniformity of the BPSG film, and effectively preventing the phenomenon of pattern distortion during the subsequent photolithography process, thereby ensuring the stability of the semiconductor device, thereby greatly improving the yield of the semiconductor device and the competitiveness of the single-cavity multi-chip PECVD device.

[0006] To achieve the object of the present invention, the following technical solutions are adopted in the present invention:

[0007] In a first aspect, the present invention provides a preparation process for a BPSG thin film, and the preparation process includes the following steps:

[0008] In a single-chamber multi-wafer PECVD device, a plurality of wafers are independently placed on different carriers.

[0009] A precursor source is introduced into the chamber and stabilized under a first condition; wherein, the precursor source includes a silicon source precursor, a boron source precursor, and a phosphorus source precursor.

[0010] Pre-deposition: Under a second condition, pre-deposition is performed on the surface of the wafer to form a BPSG pre-deposited thin film; wherein, the second condition includes: 300 sccm < Q B2 < Q B3 , 0 < t < 5 s, Q B2 is the flow rate of the boron source precursor under the second condition, and Q B1 is the flow rate of the boron source precursor under the third condition.

[0011] Main deposition: Under a third condition, continuous deposition is performed on the surface of the BPSG pre-deposited thin film.

[0012] After the main deposition is completed, post-treatment is performed, and then the deposited BPSG thin film is taken out.

[0013] By pre-depositing on the wafer surface before the main deposition and setting the parameters of the pre-deposition to meet specific conditions, the present invention greatly avoids the delamination phenomenon of the BPSG thin film, helps to improve the etching uniformity of the BPSG thin film, effectively prevents phenomena such as pattern distortion during the subsequent photoresist coating and lithography processes, ensures the stability of semiconductor devices, and thus greatly improves the yield of semiconductor devices and the competitiveness of single-chamber multi-wafer PECVD devices.

[0014] In the present invention, it is defined that 300 sccm < Q B2 < Q B3 , 0 < t < 5 s during the pre-deposition process. The purpose of this limitation is to avoid sudden stress concentration by means of gradient doping (from low boron to high boron), thereby preventing the generation of large thermal stress during the post-treatment process and causing delamination. If the deposition is directly carried out under high boron conditions, it may lead to a decrease in the bond strength of the chemical bond between the BPSG and the underlying material (such as the Si-O bond), and the interface adhesion becomes poor, resulting in delamination.

[0015] It should be noted that the meaning of a plurality of is at least 2, for example, it can be 2, 4, 5, 6, 8, 10, etc.

[0016] It should be noted that "placing a plurality of wafers independently on different carriers" means that each wafer is placed on a different carrier for film deposition.

[0017] Preferably, the silicon source precursor includes SiH4.

[0018] Preferably, the boron source precursor includes B2H6.

[0019] Preferably, the phosphorus source precursor includes PH3.

[0020] Preferably, the first condition includes: Q B1 > Q B2 , where Q B1 is the flow rate of the boron source precursor under the first condition.

[0021] Preferably, the first condition includes:

[0022] The flow rate of the silicon source precursor is 150 - 250 sccm, for example, it can be 150 sccm, 160 sccm, 170 sccm, 180 sccm, 190 sccm, 200 sccm, 210 sccm, 220 sccm, 230 sccm, 240 sccm or 250 sccm, etc.; the flow rate of the boron source precursor is 600 - 700 sccm, for example, it can be 600 sccm, 610 sccm, 620 sccm, 630 sccm, 640 sccm, 650 sccm, 660 sccm, 670 sccm, 680 sccm, 690 sccm or 700 sccm, etc.; the flow rate of the phosphorus source precursor is 300 - 400 sccm, for example, it can be 300 sccm, 310 sccm, 320 sccm, 330 sccm, 340 sccm, 350 sccm, 330 sccm, 370 sccm, 380 sccm, 390 sccm or 400 sccm, etc.; the chamber pressure is 2 - 2.5 torr, for example, it can be 2 torr, 2.1 torr, 2.2 torr, 2.3 torr, 2.4 torr or 2.5 torr, etc.

[0023] In the present invention, under the above first condition, the purpose of introducing the precursor source into the chamber and stabilizing its flow rate at the above flow rate is as follows: 1) To avoid the reaction speed from being fast and slow due to flow rate fluctuations, thereby ensuring the stability of the film growth process, which is beneficial to improving the quality and consistency of the film; 2) The stable flow rate helps to precisely control the deposition process, and then accurately control the composition ratio and growth thickness of the film to meet specific process requirements; 3) It is beneficial to quality control and process optimization in large-scale production; 4) The stable flow rate helps to form a stable plasma region and intensity in the reaction chamber, laying a foundation for the subsequent full interaction between the plasma and the precursor.

[0024] It should be noted that as the precursor source is introduced into the cavity, the cavity pressure is also increased from the vacuum pressure in the vacuum state to the above pressure conditions, which helps to generate a stable plasma, helps to more precisely control the deposition rate and thickness of the thin film, and thus obtain a uniform, dense and well-adhering BPSG thin film.

[0025] Exemplarily, the present invention does not specifically limit the time required to reach the first condition. Exemplarily, for example, it can be 10 s or the like.

[0026] Preferably, the Q B2 has a value range of 400 - 500 sccm. For example, it can be 400 sccm, 410 sccm, 420 sccm, 430 sccm, 440 sccm, 450 sccm, 460 sccm, 470 sccm, 480 sccm, 490 sccm or 500 sccm, etc., and 1.5 s ≤ t ≤ 2.5 s. For example, it can be 1.5 s, 1.6 s, 1.7 s, 1.8 s, 1.9 s, 2 s, 2.1 s, 2.2 s, 2.3 s, 2.4 s or 2.5 s.

[0027] In the present invention, the value range of Q B2 is limited to 400 - 500 sccm, and 1.5 s ≤ t ≤ 2.5 s. Within the above range, the stress distribution can be fully relieved, and sudden stress concentration can be avoided, so that the finally obtained BPSG thin film has no obvious delamination phenomenon, which is beneficial to improving the etching uniformity of the BPSG thin film, preventing pattern distortion, and ensuring device stability.

[0028] Preferably, the thickness of the BPSG pre-deposited thin film is 150 - 300 Å. For example, it can be 150 Å, 200 Å, 250 Å or 300 Å, etc.

[0029] In the present invention, a BPSG pre-deposited thin film with an appropriate thickness can make the stress distribution smoother and avoid sudden stress concentration.

[0030] Preferably, the second condition includes:

[0031] The flow rate of the silicon source precursor is 150 - 250 sccm, for example, it can be 150 sccm, 160 sccm, 170 sccm, 180 sccm, 190 sccm, 200 sccm, 210 sccm, 220 sccm, 230 sccm, 240 sccm or 250 sccm, etc. The flow rate of the phosphorus source precursor is 300 - 400 sccm, for example, it can be 300 sccm, 310 sccm, 320 sccm, 330 sccm, 340 sccm, 350 sccm, 330 sccm, 370 sccm, 380 sccm, 390 sccm or 400 sccm, etc. The chamber pressure is 2 - 2.5 torr, for example, it can be 2 torr, 2.1 torr, 2.2 torr, 2.3 torr, 2.4 torr or 2.5 torr, etc. The plasma power is 800 - 1200 W, for example, it can be 800 W, 850 W, 900 W, 950 W, 1000 W, 1050 W, 1100 W, 1150 W or 1200 W, etc.

[0032] In the pre - deposition process of the present invention, using a plasma power within an appropriate range can provide sufficient energy for the precursor source, enabling the precursor source to be more effectively dissociated into active atoms or free radicals. At the same time, it can excite gas atoms to a higher energy level state, which can accelerate the subsequent deposition reaction, improve the deposition rate, and lay a foundation for forming a high - quality BPSG thin film on the wafer surface. The appropriate plasma power helps to form uniform and dense crystal nuclei on the wafer surface, thereby ensuring the uniformity and denseness of the subsequent growth of the BPSG thin film, and is conducive to obtaining a high - quality and stable - performance BPSG thin film.

[0033] Preferably, the third condition includes:

[0034] The flow rate of the silicon source precursor is 150 - 250 sccm, for example, it can be 150 sccm, 160 sccm, 170 sccm, 180 sccm, 190 sccm, 200 sccm, 210 sccm, 220 sccm, 230 sccm, 240 sccm or 250 sccm, etc. The flow rate of the boron source precursor is 600 - 700 sccm, for example, it can be 600 sccm, 610 sccm, 620 sccm, 630 sccm, 640 sccm, 650 sccm, 660 sccm, 670 sccm, 680 sccm, 690 sccm or 700 sccm, etc. The flow rate of the phosphorus source precursor is 300 - 400 sccm, for example, it can be 300 sccm, 310 sccm, 320 sccm, 330 sccm, 340 sccm, 350 sccm, 330 sccm, 370 sccm, 380 sccm, 390 sccm or 400 sccm, etc.

[0035] In the present invention, during the main deposition process, the flow rate of the boron source precursor is within an appropriate range, which can accelerate the reaction rate, promote the rapid growth of the BPSG thin film, and reach the required thickness. Secondly, increasing the flow rate of the boron source precursor in the main deposition stage can ensure sufficient supply of boron elements during the growth of the BPSG thin film, thereby making the structure of the BPSG thin film more dense and uniform, reducing voids and defects, and further improving the quality and performance of the BPSG thin film.

[0036] Preferably, the third condition further includes:

[0037] The plasma power is 800 - 1200 W, for example, it can be 800 W, 850 W, 900 W, 950 W, 1000 W, 1050 W, 1100 W, 1150 W or 1200 W, etc., and the deposition time is 80 - 120 s, for example, it can be 80 s, 85 s, 90 s, 95 s, 100 s, 105 s, 110 s, 115 s or 120 s, etc.

[0038] Preferably, the preparation process includes the following steps:

[0039] (1) In a single - chamber multi - wafer PECVD device, several wafers are independently placed on different carriers, and the several wafers are heated to 350 - 450 °C (for example, it can be 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, 410 °C, 420 °C, 430 °C, 440 °C or 450 °C, etc.).

[0040] (2) The precursor sources are introduced into the chamber and stabilized under the first condition; wherein, the precursor sources include a silicon source precursor, a boron source precursor and a phosphorus source precursor, and the first condition includes: the flow rate of the silicon source precursor is 150 - 250 sccm, the flow rate of the boron source precursor is 600 - 700 sccm, the flow rate of the phosphorus source precursor is 300 - 400 sccm, and the chamber pressure is 2 - 2.5 torr.

[0041] (3) Pre - deposition: Under the second condition, pre - deposition is carried out on the surface of the wafer to form a BPSG pre - deposition thin film with a thickness of 150 - 300 Å; wherein, the second condition includes: the flow rate of the silicon source precursor is 150 - 250 sccm, the flow rate of the boron source precursor is 400 - 500 sccm, the flow rate of the phosphorus source precursor is 300 - 400 sccm, 1.5 s ≤ t ≤ 2.5 s, the chamber pressure is 2 - 2.5 torr, and the plasma power is 800 - 1200 W.

[0042] (4) Main deposition: Continuing deposition on the surface of the BPSG pre-deposited film under the third condition; wherein, the third condition includes: the flow rate of the silicon source precursor is 150 - 250 sccm, the flow rate of the boron source precursor is 600 - 700 sccm, the flow rate of the phosphorus source precursor is 300 - 400 sccm, the plasma power is 800 - 1200 W, and the deposition time is 80 - 120 s.

[0043] (5) After the main deposition is completed, purge and evacuation are carried out to restore the vacuum state of the chamber, and the deposited BPSG film is taken out.

[0044] In a second aspect, the present invention provides a BPSG film, and the BPSG film is prepared by using the preparation process of the BPSG film as described in the first aspect.

[0045] The thickness of the BPSG film ≥ 800 nm, for example, it can be 800 nm, 900 nm, 1000 nm, etc.

[0046] In a third aspect, the present invention provides a single-chamber multi-wafer PECVD device, and the preparation process of the BPSG film as described in the first aspect is carried out in the single-chamber multi-wafer PECVD device. The single-chamber multi-wafer PECVD device includes:

[0047] A chamber for depositing the BPSG film, and a plurality of carriers are arranged in the chamber, and the plurality of carriers are used for carrying a plurality of wafers.

[0048] A gas distributor for uniformly diffusing the precursor source into the chamber.

[0049] A radio frequency system for dissociating the precursor source into an ionic state.

[0050] Preferably, the single-chamber multi-wafer PECVD device further includes a heater for providing heat to the wafers. Exemplarily, the material of the heater is aluminum.

[0051] The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above numerical ranges not listed. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the ranges.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The present invention pre - deposits on the wafer surface before the main deposition, and sets the parameters of the pre - deposition to meet specific conditions, thereby greatly avoiding the delamination phenomenon of the BPSG film, helping to improve the etching uniformity of the BPSG film. During the subsequent photoresist coating and lithography processes, it effectively prevents phenomena such as pattern distortion, ensures the stability of semiconductor devices, and thus greatly improves the yield of semiconductor devices and the competitiveness of single - chamber multi - wafer PECVD equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a process flow chart provided in a specific embodiment of the present invention.

[0055] Figure 2 It is a cross - sectional scanning electron microscope image of any BPSG film prepared in Example 1 of the present invention.

[0056] Figure 3 It is a cross - sectional scanning electron microscope image of any BPSG film prepared in Comparative Example 1 of the present invention.

[0057] Figure 4 It is a cross - sectional scanning electron microscope image of any BPSG film prepared in Comparative Example 2 of the present invention.

[0058] Figure 5 It is a cross - sectional scanning electron microscope image of any BPSG film prepared in Comparative Example 3 of the present invention.

[0059] Figure 6 It is a cross - sectional scanning electron microscope image of any BPSG film prepared in Comparative Example 4 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0060] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0061] In a specific embodiment, the present invention provides a single - chamber multi - wafer PECVD equipment, including:

[0062] A chamber for depositing the BPSG film, and several carriers are arranged in the chamber, and the several carriers are used to carry several wafers.

[0063] A gas - distributing plate for uniformly diffusing the precursor source into the chamber.

[0064] A radio - frequency system for dissociating the precursor source into an ionic state.

[0065] An aluminum heater for providing heat to the wafers.

[0066] In another specific embodiment, the present invention provides a preparation process for a BPSG thin film. The preparation process for the BPSG thin film is carried out in the above-mentioned single-chamber multi-wafer PECVD equipment. The process flow chart of the preparation process is as Figure 1 shown and includes the following steps:

[0067] In the single-chamber multi-wafer PECVD equipment, a plurality of wafers are independently placed on different carriers.

[0068] Introduce the precursor sources into the chamber and stabilize them under the first conditions; wherein, the precursor sources include a silicon source precursor, a boron source precursor, and a phosphorus source precursor.

[0069] Pre-deposition: Under the second conditions, pre-deposit on the surface of the wafer to form a BPSG pre-deposited thin film; wherein, the second conditions include: 300 sccm < Q B2 < Q B1 , 0 < t < 5 s, Q B2 is the flow rate of the boron source precursor under the second conditions, and Q B1 is the flow rate of the boron source precursor under the first conditions.

[0070] Main deposition: Under the third conditions, continue to deposit on the surface of the BPSG pre-deposited thin film.

[0071] After the main deposition is completed, perform post-treatment, and then take out the deposited BPSG thin film.

[0072] Example 1

[0073] This example provides a preparation process for a BPSG thin film. The preparation process includes the following steps:

[0074] (1) In the single-chamber multi-wafer PECVD equipment, a plurality of wafers are independently placed on different carriers, and the plurality of wafers are heated to 400 °C using a heater.

[0075] (2) Use a gas distributor to introduce the precursor sources into the chamber and stabilize them under the first conditions within 10 s, and the chamber pressure is increased from 20 mtorr to 2.2 torr; wherein, the precursor sources include a silicon source precursor, a boron source precursor, and a phosphorus source precursor. The silicon source precursor is SiH4, the boron source precursor is B2H6, and the phosphorus source precursor is PH3; the first conditions include: the flow rate of the silicon source precursor is 198 sccm, the flow rate of the boron source precursor is 645 sccm, and the flow rate of the phosphorus source precursor is 340 sccm.

[0076] (3) Pre - deposition: Under the second condition, pre - deposition is carried out on the surface of the wafer to form a BPSG pre - deposition film with a thickness of 200 Å; wherein, the second condition includes: the flow rate of the silicon source precursor is 198 sccm, the flow rate of the boron source precursor is 450 sccm, the flow rate of the phosphorus source precursor is 340 sccm, t = 2 s, the chamber pressure is 2.2 torr, the plasma power is 1000 W, and the radio - frequency frequency is 13.56 MHz.

[0077] (4) Main deposition: Under the third condition, continue to deposit on the surface of the BPSG pre - deposition film; wherein, the third condition includes: the flow rate of the silicon source precursor is 198 sccm, the flow rate of the boron source precursor is 645 sccm, the flow rate of the phosphorus source precursor is 340 sccm, the plasma power is 1000 W, the radio - frequency frequency is 13.56 MHz, and the deposition time is 100 s.

[0078] (5) After the main deposition is completed, nitrogen is introduced for purging, and then the residual gas in the chamber is pumped out by a pumping device to restore the chamber to a vacuum state, and the deposited BPSG film with a thickness of 1000 nm is taken out.

[0079] Example 2

[0080] This example provides a preparation process of a BPSG film, and the preparation process includes the following steps:

[0081] (1) In a single - chamber multi - wafer PECVD device, several wafers are independently placed on different carriers, and the several wafers are heated to 350 °C by a heater.

[0082] (2) The precursor sources are introduced into the chamber by a gas - distributing disk and stabilized within 10 s under the first condition, and the chamber pressure is increased from 20 mtorr to 2 torr; wherein, the precursor sources include a silicon source precursor, a boron source precursor, and a phosphorus source precursor, the silicon source precursor is SiH4, the boron source precursor is B2H6, and the phosphorus source precursor is PH3; the first condition includes: the flow rate of the silicon source precursor is 150 sccm, the flow rate of the boron source precursor is 600 sccm, and the flow rate of the phosphorus source precursor is 300 sccm.

[0083] (3) Pre - deposition: Under the second condition, pre - deposition is carried out on the surface of the wafer to form a BPSG pre - deposition film with a thickness of 187.5 Å; wherein, the second condition includes: the flow rate of the silicon source precursor is 150 sccm, the flow rate of the boron source precursor is 400 sccm, the flow rate of the phosphorus source precursor is 300 sccm, t = 2.5 s, the chamber pressure is 2 torr, the plasma power is 800 W, and the radio - frequency frequency is 13.56 MHz.

[0084] (4) Main deposition: Continuing deposition on the surface of the BPSG pre-deposited film under the third condition; wherein, the third condition includes: the flow rate of the silicon source precursor is 150 sccm, the flow rate of the boron source precursor is 600 sccm, the flow rate of the phosphorus source precursor is 300 sccm, the plasma power is 800 W, the radio frequency is 13.56 MHz, and the deposition time is 90 s.

[0085] (5) After the main deposition is completed, nitrogen is introduced for purging, and then the residual gas in the cavity is pumped out through a pumping device to restore the vacuum state of the cavity, and the deposited BPSG film is taken out, and its thickness is 800 nm.

[0086] Example 3

[0087] This example provides a preparation process for a BPSG film, and the preparation process includes the following steps:

[0088] (1) In a single-chamber multi-wafer PECVD device, several wafers are independently placed on different carriers, and the several wafers are heated to 450 °C by a heater.

[0089] (2) The precursor source is introduced into the cavity by a gas distributor and stabilized at the first condition within 10 s, and the cavity pressure is increased from 20 mtorr to 2.5 torr; wherein, the precursor source includes a silicon source precursor, a boron source precursor, and a phosphorus source precursor, the silicon source precursor is SiH4, the boron source precursor is B2H6, and the phosphorus source precursor is PH3; the first condition includes: the flow rate of the silicon source precursor is 250 sccm, the flow rate of the boron source precursor is 700 sccm, and the flow rate of the phosphorus source precursor is 400 sccm.

[0090] (3) Pre-deposition: Under the second condition, pre-deposition is carried out on the surface of the wafer to form a BPSG pre-deposited film with a thickness of 187.5 Å; wherein, the second condition includes: the flow rate of the silicon source precursor is 250 sccm, the flow rate of the boron source precursor is 500 sccm, the flow rate of the phosphorus source precursor is 400 sccm, t = 1.5 s, the cavity pressure is 2.5 torr, the plasma power is 1200 W, and the radio frequency is 13.56 MHz.

[0091] (4) Main deposition: Continuing deposition on the surface of the BPSG pre-deposited film under the third condition; wherein, the third condition includes: the flow rate of the silicon source precursor is 250 sccm, the flow rate of the boron source precursor is 700 sccm, the flow rate of the phosphorus source precursor is 400 ccm, the plasma power is 1200 W, the radio frequency is 13.56 MHz, and the deposition time is 120 s.

[0092] After the main deposition is completed, nitrogen is introduced for purging, and then the residual gas in the chamber is pumped out by a pumping device to restore the chamber to a vacuum state. The deposited BPSG film is taken out, and its thickness is 1500 nm.

[0093] Example 4

[0094] The difference between this example and Example 1 is that the flow rate of the boron source precursor in step (3) is 400 sccm, and t = 2.5 s.

[0095] The remaining preparation processes and parameters are the same as those in Example 1.

[0096] Example 5

[0097] The difference between this example and Example 1 is that the flow rate of the boron source precursor in step (3) is 500 sccm, and t = 1.5 s.

[0098] The remaining preparation processes and parameters are the same as those in Example 1.

[0099] Example 6

[0100] The difference between this example and Example 1 is that the flow rate of the boron source precursor in step (3) is 350 sccm.

[0101] The remaining preparation processes and parameters are the same as those in Example 1.

[0102] Example 7

[0103] The difference between this example and Example 1 is that the flow rate of the boron source precursor in step (3) is 550 sccm.

[0104] The remaining preparation processes and parameters are the same as those in Example 1.

[0105] Example 8

[0106] The difference between this example and Example 1 is that in step (3), t = 1 s.

[0107] The remaining preparation processes and parameters are the same as those in Example 1.

[0108] Example 9

[0109] The difference between this example and Example 1 is that in step (3), t = 3.5 s.

[0110] The remaining preparation processes and parameters are the same as those in Example 1.

[0111] Example 10

[0112] The difference between this embodiment and embodiment 1 is that the flow rate of the silicon source precursor in step (3) is 100 sccm.

[0113] The rest of the preparation process and parameters were the same as those in Example 1.

[0114] Embodiment 11

[0115] The difference between this embodiment and embodiment 1 is that the flow rate of the phosphorus source precursor in step (3) is 200 sccm.

[0116] The rest of the preparation process and parameters were the same as those in Example 1.

[0117] Comparative Example 1

[0118] The difference between this comparative example and Example 1 is that the flow rate of the boron source precursor in step (3) is 258 sccm, and t=5 s.

[0119] The rest of the preparation process and parameters were the same as those in Example 1.

[0120] Comparative Example 2

[0121] The difference between this comparative example and Example 1 is that the flow rate of the boron source precursor in step (3) is 258 sccm.

[0122] The rest of the preparation process and parameters were the same as those in Example 1.

[0123] Comparative Example 3

[0124] The difference between this comparative example and Example 1 is that in step (3), t=5s.

[0125] The rest of the preparation process and parameters were the same as those in Example 1.

[0126] Comparative Example 4

[0127] The difference between this comparative example and Example 1 is that step (3) is not performed.

[0128] The rest of the preparation process and parameters were the same as those in Example 1.

[0129] Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 The cross-sectional scanning electron microscope images of any BPSG film prepared in Example 1 and Comparative Examples 1-4 are shown respectively. From the comparison of the images, it can be seen that the BPSG films prepared in Comparative Examples 1-4 all have obvious stratification, while the BPSG film prepared in Example 1 has no stratification.

[0130] Comparative Example 5

[0131] The difference between this embodiment and Embodiment 1 is that the flow rate of the boron source precursor in step (3) is 700 sccm.

[0132] The remaining preparation processes and parameters are the same as those in Embodiment 1.

[0133] Comparative Example 6

[0134] The difference between this embodiment and Embodiment 1 is that in the second condition of step (3), the flow rate of the phosphorus source precursor is adjusted to 300 sccm, while the flow rate of the boron source precursor is the same as that of the boron source precursor in the first condition.

[0135] The remaining preparation processes and parameters are the same as those in Embodiment 1.

[0136] Comparative Example 7

[0137] The difference between this embodiment and Embodiment 1 is that in the second condition of step (3), the flow rate of the silicon source precursor is adjusted to 150 sccm, while the flow rate of the boron source precursor is the same as that of the boron source precursor in the first condition.

[0138] The remaining preparation processes and parameters are the same as those in Embodiment 1.

[0139] Performance Test

[0140] I. Test the reaction rate of the products prepared in the above embodiments and comparative examples. The reaction rate refers to the ratio of the deposited film thickness to the deposition time.

[0141] II. Conduct a thickness uniformity test on several products prepared in the above embodiments and comparative examples. The test steps include: removing 5 mm from the edge of the product, and then using an ellipsometer to measure the thickness of 49 points on the film surface to calculate the film thickness uniformity and take the average value. The measured film thickness uniformity (U%) = thickness standard deviation / thickness average value × 100%.

[0142] III. Conduct secondary ion mass spectrometry analysis on the B content in several BPSG films provided in the above embodiments and comparative examples, and calculate the range between the maximum value and the minimum value in the obtained curve as the range uniformity. If the range uniformity ≤ 2%, it is recorded as small fluctuation. If the range uniformity is in the range of 2 - 5%, it is recorded as relatively small fluctuation. If the range uniformity is in the range of 5 - 10%, it is recorded as relatively large fluctuation. If the range uniformity is greater than 10%, it is recorded as large fluctuation.

[0143] The above test results are shown in Table 1.

[0144] Table 1

[0145]

[0146] Analysis:

[0147] As can be seen from Table 1, in the present invention, pre - deposition is first carried out on the wafer surface before the main deposition, and at the same time, the parameters of the pre - deposition are set to meet specific conditions, thus greatly avoiding the delamination phenomenon of the BPSG film, which helps to improve the etching uniformity of the BPSG film. During the subsequent photoresist coating and lithography processes, it effectively prevents phenomena such as pattern distortion, ensuring the stability of semiconductor devices. Therefore, the yield of semiconductor devices and the competitiveness of single - chamber multi - wafer PECVD equipment are greatly improved.

[0148] As can be seen from the comparison between Example 1 and Examples 6 - 7, when the flow rate of the boron source precursor in step (3) is too small or too large, the delamination phenomenon in the prepared BPSG film is more obvious, which is not conducive to subsequent etching and the stability of semiconductor devices.

[0149] As can be seen from the comparison between Example 1 and Examples 8 - 9, when the pre - deposition time in step (3) is too short or too long, it is not conducive to the uniform deposition of B element, resulting in a more obvious delamination phenomenon in the prepared BPSG film, which is not conducive to subsequent etching and the stability of semiconductor devices.

[0150] As can be seen from the comparison between Example 1 and Examples 10 - 11, if the flow rate of the silicon source precursor in step (3) is too small, it will lead to the instability of the composition of the BPSG pre - deposited film, resulting in an easy delamination phenomenon in the BPSG film; if the flow rate of the phosphorus source precursor in step (3) is too small, it will lead to the instability of the composition of the BPSG pre - deposited film, resulting in an easy delamination phenomenon in the BPSG film.

[0151] As can be seen from the comparison between Example 1 and Comparative Example 2, if the flow rate of the boron source precursor is too small, the secondary ion mass spectrometry analysis curve of the B content in the BPSG film fluctuates greatly, indicating that the distribution of B element in the BPSG film is uneven and there is a multi - layer structure.

[0152] As can be seen from the comparison between Example 1 and Comparative Example 3, if the pre - deposition time in step (3) is too long, the secondary ion mass spectrometry analysis curve of the B content in the BPSG film fluctuates greatly, indicating that the distribution of B element in the BPSG film is uneven and there is a multi - layer structure.

[0153] As can be seen from the comparison between Example 1 and Comparative Example 4, if step (3) is not carried out, the secondary ion mass spectrometry analysis curve of the B content in the BPSG film fluctuates greatly, indicating that the distribution of B element in the BPSG film is uneven and there is a multi - layer structure.

[0154] As can be seen from the comparison between Example 1 and Comparative Example 5, if the flow rate of the boron source precursor in step (3) is too large, it is not only not conducive to eliminating the delamination phenomenon of the BPSG film, but also the delamination phenomenon is more obvious.

[0155] It can be seen from the comparison between Example 1 and Comparative Examples 6-7 that if the flow rate of the phosphorus source precursor is reduced during the pre-deposition process and the flow rate of the boron source precursor is kept the same as that in the first condition, it does not affect the boron content during the deposition process, so the uneven distribution of boron content cannot be improved and the delamination still exists; if the flow rate of the silicon source precursor is reduced during the pre-deposition process and the flow rate of the boron source precursor is kept the same as that in the first condition, it does not affect the boron content during the deposition process, so the uneven distribution of boron content cannot be improved and the delamination still exists.

[0156] It should be noted that the process method of the present invention is illustrated by the above-mentioned embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of the raw materials selected for the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A process for preparing a BPSG film, characterized in that: The preparation process comprises the following steps: In a single-chamber multi-wafer PECVD device, several wafers are placed independently on different carriers; Passing a precursor source into the chamber and stabilizing it at a first condition; wherein the precursor source includes a silicon source precursor, a boron source precursor and a phosphorus source precursor; Pre-deposition: Pre-deposition is performed on the surface of the wafer under the second condition to form a BPSG pre-deposition film; wherein the second condition includes: 300sccm<Q B2 <Q B3 , 0<t<5s, Q B2 is the flow rate of the boron source precursor under the second condition, Q B3 is the flow rate of the boron source precursor under the third condition; Main deposition: continuing deposition on the surface of the BPSG pre-deposition film under the third condition; After the main deposition is completed, post-treatment is performed, and then the deposited BPSG film is taken out.

2. The process for preparing the BPSG film according to claim 1, characterized in that: The silicon source precursor includes SiH4; The boron source precursor includes B2H6; The phosphorus source precursor includes PH3.

3. The process for preparing the BPSG film according to claim 1, characterized in that: The first condition includes: B1 >Q B2 , where Q B1 is the flow rate of the boron source precursor under the first condition; And / or, the first condition includes: The flow rate of the silicon source precursor is 150-250sccm, the flow rate of the boron source precursor is 600-700sccm, the flow rate of the phosphorus source precursor is 300-400sccm, and the chamber pressure is 2-2.5torr.

4. The process for preparing the BPSG film according to claim 1, characterized in that: The Q B2 The value range of is 400-500sccm, 1.5s≤t≤2.5s.

5. The process for preparing the BPSG film according to claim 1, characterized in that: The thickness of the BPSG pre-deposition film is 150-300Å.

6. The process for preparing the BPSG film according to claim 1, characterized in that: The second condition includes: The flow rate of the silicon source precursor is 150-250sccm, the flow rate of the phosphorus source precursor is 300-400sccm, the chamber pressure is 2-2.5torr, and the plasma power is 800-1200W.

7. The process for preparing the BPSG film according to claim 1, characterized in that: The third condition includes: The flow rate of silicon source precursor is 150-250sccm, the flow rate of boron source precursor is 600-700sccm, and the flow rate of phosphorus source precursor is 300-400sccm; And / or, the third condition also includes: Plasma power 800-1200W, deposition time 80-120s.

8. The process for preparing the BPSG film according to any one of claims 1 to 7, characterized in that: The preparation process comprises the following steps: (1) In a single-chamber multi-wafer PECVD device, a plurality of wafers are independently placed on different carriers and heated to 350-450°C; (2) introducing a precursor source into the chamber and stabilizing it at a first condition; wherein the precursor source includes a silicon source precursor, a boron source precursor and a phosphorus source precursor, and the first condition includes: a flow rate of 150-250 sccm for the silicon source precursor, a flow rate of 600-700 sccm for the boron source precursor, a flow rate of 300-400 sccm for the phosphorus source precursor, and a chamber pressure of 2-2.5 torr; (3) Pre-deposition: Under the second condition, pre-deposition is performed on the surface of the wafer to form a BPSG pre-deposition film with a thickness of 150-300Å; wherein the second condition includes: a flow rate of the silicon source precursor of 150-250sccm, a flow rate of the boron source precursor of 400-500sccm, a flow rate of the phosphorus source precursor of 300-400sccm, 1.5s≤t≤2.5s, a chamber pressure of 2-2.5torr, and a plasma power of 800-1200W; (4) Main deposition: continuing deposition on the surface of the BPSG pre-deposited film under the third condition; wherein the third condition includes: a flow rate of the silicon source precursor of 150-250 sccm, a flow rate of the boron source precursor of 600-700 sccm, a flow rate of the phosphorus source precursor of 300-400 sccm, a plasma power of 800-1200 W, and a deposition time of 80-120 s; (5) After the main deposition is completed, the chamber is purged and evacuated to restore the vacuum state, and the deposited BPSG film is taken out.

9. A BPSG film, characterized in that: The BPSG film is prepared by the BPSG film preparation process according to any one of claims 1 to 8; The thickness of the BPSG film is ≥800nm.

10. A single-chamber multi-chip PECVD device, characterized in that: The single-cavity multi-chip PECVD device is used to prepare the BPSG film according to any one of claims 1 to 8, and the single-cavity multi-chip PECVD device comprises: A chamber, used for BPSG thin film deposition, wherein a plurality of carriers are arranged in the chamber, and the plurality of carriers are used for carrying a plurality of wafers; A gas distribution plate, used to evenly diffuse the precursor source into the cavity; A radio frequency system is used to dissociate the precursor source into an ion state.

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