BPSG film, preparation process thereof and single-cavity multi-piece PECVD equipment

Abstract

The invention provides a BPSG film, a preparation process thereof and single-cavity multi-chip PECVD equipment, and belongs to the technical field of semiconductors. The preparation process comprises the following steps of: in single-cavity multi-wafer PECVD (Plasma Enhanced Chemical Vapor Deposition) equipment, placing a plurality of wafers on different carrying tables; introducing a precursor source into the cavity, and stabilizing the precursor source under a first condition; the precursor source comprises 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-deposition film; the second condition comprises 300sccm < QB2 < QB3, and 0 < t < 5s; main deposition: continuously depositing on the surface of the BPSG pre-deposited film under a third condition; and after the main deposition is finished, post-processing is carried out, and then the BPSG film obtained through deposition is taken out. According to the invention, the layering phenomenon of the BPSG film is avoided, and the yield of semiconductor devices and the competitiveness of single-cavity multi-chip PECVD equipment are greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor technology, and in particular relates to a BPSG film and a preparation process thereof and a single-cavity multi-chip PECVD device. Background Art

[0002] In PECVD (plasma enhanced chemical vapor deposition) technology, the reaction gas is introduced into a vacuum chamber, and then plasma is generated by radio frequency (RF) and other methods. The high-energy electrons in the plasma collide with the reaction gas molecules, causing the gas molecules to dissociate and excite, and generate a large number of active particles, such as atoms, ions and free radicals. These active particles react chemically 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 various semiconductor memory device films. For example, CN115287630A discloses a semiconductor device preparation device and preparation method, which includes a gas pipeline, a gas optimization system and a reaction chamber; the gas pipeline includes a plurality of gas inlet pipelines; the reaction chamber is provided with a radio frequency matcher, a gas distribution plate, a wafer tray and a gas exhaust part from top to bottom; a plurality of gas inlets are connected to the gas mixing optimization system; the gas optimization system is arranged outside the reaction chamber; the gas mixing optimization system includes a gas stirring device and a gas filtering device. Although this technology can achieve uniform distribution of multiple gases, thin film deposition can only be performed on one wafer at a time, and multi-line operation 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] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a process for preparing a BPSG film, the process comprising the following steps: In a single-chamber multi-wafer PECVD device, several wafers are placed independently on different carriers.

[0007] A precursor source is introduced into the cavity and stabilized at a first condition; wherein the precursor source includes a silicon source precursor, a boron source precursor and a phosphorus source precursor.

[0008] 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 B1 is the flow rate of the boron source precursor under the third condition.

[0009] Main deposition: under the third condition, deposition is continued on the surface of the BPSG pre-deposition film.

[0010] After the main deposition is completed, post-treatment is performed, and then the deposited BPSG film is taken out.

[0011] 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 phenomenon of the BPSG film, helping to improve the etching uniformity of the BPSG film, and effectively preventing the phenomenon of graphic distortion during the subsequent glue coating 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-wafer PECVD equipment.

[0012] In the present invention, it is defined that 300sccm<Q B2 <Q B3 , 0<t<5s. The purpose of this limitation is to avoid sudden stress concentration by means of gradient doping (from low boron to high boron), thereby preventing large thermal stress from being generated during post-processing and causing delamination. If deposition is performed directly under high boron conditions, the chemical bonding strength (such as Si-O bond) between BPSG and the underlying material may be reduced, the interface adhesion may deteriorate, and delamination may occur.

[0013] It should be noted that, “a number” means at least 2, for example, it can be 2, 4, 5, 6, 8 or 10, etc.

[0014] It should be noted that “several wafers are independently placed on different carriers” means that each wafer is placed on a different carrier for thin film deposition.

[0015] Preferably, the silicon source precursor includes SiH4.

[0016] Preferably, the boron source precursor includes B2H6.

[0017] Preferably, the phosphorus source precursor includes PH3.

[0018] 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.

[0019] Preferably, the first condition includes: The flow rate of the silicon source precursor is 150-250sccm, for example, it can be 150sccm, 160sccm, 170sccm, 180sccm, 190sccm, 200sccm, 210sccm, 220sccm, 230sccm, 240sccm or 250sccm, and the flow rate of the boron source precursor is 600-700sccm, for example, it can be 600sccm, 610sccm, 620sccm, 630sccm, 640sccm, 650sccm, 660sccm, 670sccm, 680sccm, 690sccm, 700sccm, 710sccm, 720sccm, 730sccm, 740sccm, 750sccm, 760sccm, 770sccm, 780sccm, 790sccm, 800sccm, 810sccm, 820sccm, 830sccm, 840sccm, 850sccm, 860sccm, 870sccm, 880sccm, 890sccm, 900sccm, 910sccm, 920sccm, 930sccm, 940sccm, 950sccm, 960sccm, 970sccm, 980sccm, 990sccm, 1000sccm, 1010sccm, 1010sccm, 1020sccm, 1030sccm, 1030sccm, 1040sccm The flow rate of the phosphorus source precursor is 300-400sccm, for example, it can be 300sccm, 310sccm, 320sccm, 330sccm, 340sccm, 350sccm, 330sccm, 370sccm, 380sccm, 390sccm or 400sccm, and the chamber pressure is 2-2.5torr, for example, it can be 2torr, 2.1torr, 2.2torr, 2.3torr, 2.4torr or 2.5torr, etc.

[0020] In the present invention, under the above-mentioned first condition, the purpose of introducing the precursor source into the cavity and stabilizing its flow rate at the above-mentioned flow rate is: 1) to avoid the reaction being fast or slow due to flow fluctuations, thereby ensuring the stability of the film growth process, which is beneficial to improving the quality and consistency of the film; 2) stable flow rate helps to accurately 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) stable flow rate helps to form a stable plasma area and intensity in the reaction chamber, laying the foundation for the subsequent full interaction between plasma and precursor.

[0021] It should be noted that as the precursor source is introduced into the chamber, the chamber pressure is increased from the vacuum pressure under the vacuum state to the above-mentioned pressure conditions, which helps to generate a stable plasma and helps to more accurately control the deposition rate and thickness of the film, thereby obtaining a uniform, dense and well-adhesive BPSG film.

[0022] Exemplarily, the present invention does not specifically limit the time required to achieve the first condition, and exemplary, for example, may be 10 seconds.

[0023] Preferably, the Q B2 The value range of is 400-500sccm, for example, it can be 400sccm, 410sccm, 420sccm, 430sccm, 440sccm, 450sccm, 460sccm, 470sccm, 480sccm, 490sccm or 500sccm, etc., 1.5s≤t≤2.5s, for example, it can be 1.5s, 1.6s, 1.7s, 1.8s, 1.9s, 2s, 2.1s, 2.2s, 2.3s, 2.4s or 2.5s.

[0024] In the present invention, Q is defined as B2 The value range of is 400-500sccm, 1.5s≤t≤2.5s. Within the above range, the stress distribution can be fully relaxed and sudden stress concentration can be avoided, so that the final BPSG film has no obvious stratification phenomenon, which is beneficial to improve the etching uniformity of the BPSG film, prevent pattern distortion, and ensure device stability.

[0025] Preferably, the thickness of the BPSG pre-deposited film is 150-300Å, for example, 150Å, 200Å, 250Å or 300Å.

[0026] In the present invention, the BPSG pre-deposited film with a suitable thickness can make the stress distribution smoother and avoid sudden stress concentration.

[0027] Preferably, the second condition includes: The flow rate of the silicon source precursor is 150-250sccm, for example, it can be 150sccm, 160sccm, 170sccm, 180sccm, 190sccm, 200sccm, 210sccm, 220sccm, 230sccm, 240sccm or 250sccm, etc. The flow rate of the phosphorus source precursor is 300-400sccm, for example, it can be 300sccm, 310sccm, 320sccm, 330sccm, 340sccm, 350sccm, etc. ccm, 330sccm, 370sccm, 380sccm, 390sccm or 400sccm, etc., the chamber pressure is 2-2.5torr, for example, it can be 2torr, 2.1torr, 2.2torr, 2.3torr, 2.4torr or 2.5torr, etc., the plasma power is 800-1200W, for example, it can be 800W, 850W, 900W, 950W, 1000W, 1050W, 1100W, 1150W or 1200W, etc.

[0028] In the pre-deposition process of the present invention, the use of a suitable range of plasma power can provide sufficient energy for the precursor source, so that the precursor source can be more effectively dissociated into active atoms or free radicals, and at the same time, the gas atoms can be excited to a higher energy level state, which can accelerate the subsequent deposition reaction and increase the deposition rate, thereby laying a foundation for forming a high-quality BPSG film on the wafer surface; the suitable plasma power is helpful to form uniform and dense crystal nuclei on the wafer surface, thereby ensuring the uniformity and density of the subsequent BPSG film growth, which is conducive to obtaining a high-quality BPSG film with stable performance.

[0029] Preferably, the third condition includes: The flow rate of the silicon source precursor is 150-250sccm, for example, it can be 150sccm, 160sccm, 170sccm, 180sccm, 190sccm, 200sccm, 210sccm, 220sccm, 230sccm, 240sccm or 250sccm, and the flow rate of the boron source precursor is 600-700sccm, for example, it can be 600sccm, 610sccm, 620sccm, 630sccm, The flow rate of the phosphorus source precursor is 300-400sccm, for example, 300sccm, 310sccm, 320sccm, 330sccm, 340sccm, 350sccm, 330sccm, 370sccm, 380sccm, 390sccm or 400sccm, etc.

[0030] In the present invention, the flow rate of the boron source precursor in the main deposition process is within an appropriate range, which can accelerate the reaction rate, promote the rapid growth of the BPSG film, and achieve the desired thickness. Secondly, increasing the flow rate of the boron source precursor in the main deposition stage can ensure that the BPSG film has a sufficient supply of boron elements during the growth process, thereby making the structure of the BPSG film denser and more uniform, reducing voids and defects, and thereby improving the quality and performance of the BPSG film.

[0031] Preferably, the third condition also includes: 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. 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.

[0032] Preferably, 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 the plurality of wafers are heated to 350-450°C (for example, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C or 450°C, etc.).

[0033] (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 the silicon source precursor of 150-250sccm, a flow rate of the boron source precursor of 600-700sccm, a flow rate of the phosphorus source precursor of 300-400sccm, and a chamber pressure of 2-2.5torr.

[0034] (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.

[0035] (4) Main deposition: under the third condition, continue to deposit on the surface of the BPSG pre-deposited film; wherein the third condition includes: a flow rate of the silicon source precursor of 150-250sccm, a flow rate of the boron source precursor of 600-700sccm, a flow rate of the phosphorus source precursor of 300-400sccm, a plasma power of 800-1200W, and a deposition time of 80-120s.

[0036] (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.

[0037] In a second aspect, the present invention provides a BPSG film, wherein the BPSG film is prepared by using the BPSG film preparation process as described in the first aspect.

[0038] The thickness of the BPSG film is ≥800 nm, for example, 800 nm, 900 nm or 1000 nm.

[0039] In a third aspect, the present invention provides a single-chamber multi-chip PECVD device, in which the BPSG film preparation process described in the first aspect is performed, and the single-chamber multi-chip PECVD device comprises: The cavity is used for BPSG thin film deposition, and a plurality of carriers are arranged in the cavity, and the plurality of carriers are used for carrying a plurality of wafers.

[0040] The gas distribution plate is used to evenly diffuse the precursor source into the cavity.

[0041] A radio frequency system is used to dissociate the precursor source into an ion state.

[0042] Preferably, the single-chamber multi-wafer PECVD equipment further comprises a heater for providing heat to the wafers. Exemplarily, the heater is made of aluminum.

[0043] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0044] Compared with the prior art, the present invention has the following beneficial effects: 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 phenomenon of the BPSG film, helping to improve the etching uniformity of the BPSG film, and effectively preventing the phenomenon of graphic distortion during the subsequent glue coating 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-wafer PECVD equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A process flow chart is provided in a specific embodiment of the present invention.

[0046] Figure 2 This is a cross-sectional scanning electron microscope image of any BPSG film prepared in Example 1 of the present invention.

[0047] Figure 3 This is a cross-sectional scanning electron microscope image of any BPSG film prepared in Comparative Example 1 of the present invention.

[0048] Figure 4 This is a cross-sectional scanning electron microscope image of any BPSG film prepared in Comparative Example 2 of the present invention.

[0049] Figure 5 This is a cross-sectional scanning electron microscope image of any BPSG film prepared in Comparative Example 3 of the present invention.

[0050] Figure 6 This is a cross-sectional scanning electron microscope image of any BPSG film prepared in Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0051] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0052] In one embodiment, the present invention provides a single-chamber multi-chip PECVD device, comprising: The cavity is used for BPSG thin film deposition, and a plurality of carriers are arranged in the cavity, and the plurality of carriers are used for carrying a plurality of wafers.

[0053] The gas distribution plate is used to evenly diffuse the precursor source into the cavity.

[0054] A radio frequency system is used to dissociate the precursor source into an ion state.

[0055] Aluminum heater used to provide heat to the wafer.

[0056] In another specific embodiment, the present invention provides a process for preparing a BPSG film, wherein the process for preparing the BPSG film is carried out in the above-mentioned single-chamber multi-chip PECVD device, and the process flow chart of the preparation process is as follows: Figure 1 As shown, the following steps are included: In a single-chamber multi-wafer PECVD device, several wafers are placed independently on different carriers.

[0057] A precursor source is introduced into the cavity and stabilized at a first condition; wherein the precursor source includes a silicon source precursor, a boron source precursor and a phosphorus source precursor.

[0058] 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 B1 , 0<t<5s, Q B2 is the flow rate of the boron source precursor under the second condition, Q B1 is the flow rate of the boron source precursor under the first condition.

[0059] Main deposition: Under the third condition, deposition is continued on the surface of the BPSG pre-deposition film.

[0060] After the main deposition is completed, post-treatment is performed and then the deposited BPSG film is taken out.

[0061] Example 1 This embodiment provides a preparation process of a BPSG film, and the preparation process includes the following steps: (1) In a single-chamber multi-wafer PECVD device, a plurality of wafers are independently placed on different carriers, and the plurality of wafers are heated to 400°C using a heater.

[0062] (2) A precursor source is introduced into the chamber by means of a gas distribution plate and stabilized at a first condition within 10 seconds, and the chamber pressure is increased from 20 mtorr to 2.2 torr; wherein the precursor source comprises 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 comprises: a flow rate of 198 sccm for the silicon source precursor, a flow rate of 645 sccm for the boron source precursor, and a flow rate of 340 sccm for the phosphorus source precursor.

[0063] (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 200Å; wherein the second condition includes: a flow rate of the silicon source precursor is 198sccm, a flow rate of the boron source precursor is 450sccm, a flow rate of the phosphorus source precursor is 340sccm, t=2s, a chamber pressure of 2.2torr, a plasma power of 1000W, and a radio frequency frequency of 13.56MHz.

[0064] (4) Main deposition: under the third condition, the deposition is continued on the surface of the BPSG pre-deposited film; wherein the third condition includes: a flow rate of 198 sccm for the silicon source precursor, a flow rate of 645 sccm for the boron source precursor, a flow rate of 340 sccm for the phosphorus source precursor, a plasma power of 1000 W, a radio frequency frequency of 13.56 MHz, and a deposition time of 100 s.

[0065] (5) After the main deposition is completed, nitrogen gas is introduced for purging, and then the residual gas in the cavity is evacuated through a vacuum device to restore the cavity to a vacuum state, and the deposited BPSG film is taken out, with a thickness of 1000 nm.

[0066] Example 2 This embodiment provides a preparation process of a BPSG film, and the preparation process includes the following steps: (1) In a single-chamber multi-wafer PECVD device, a plurality of wafers are independently placed on different carriers, and the plurality of wafers are heated to 350° C. using a heater.

[0067] (2) A precursor source is introduced into the chamber by means of a gas distribution plate and stabilized at a first condition within 10 seconds, and the chamber pressure is increased from 20 mtorr to 2 torr; wherein the precursor source comprises 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 comprises: a flow rate of 150 sccm for the silicon source precursor, a flow rate of 600 sccm for the boron source precursor, and a flow rate of 300 sccm for the phosphorus source precursor.

[0068] (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 187.5Å; wherein the second condition includes: a flow rate of the silicon source precursor is 150sccm, a flow rate of the boron source precursor is 400sccm, a flow rate of the phosphorus source precursor is 300sccm, t=2.5s, a chamber pressure of 2torr, a plasma power of 800W, and a radio frequency of 13.56MHz.

[0069] (4) Main deposition: under the third condition, the deposition is continued on the surface of the BPSG pre-deposited film; wherein the third condition includes: a flow rate of 150 sccm for the silicon source precursor, a flow rate of 600 sccm for the boron source precursor, a flow rate of 300 sccm for the phosphorus source precursor, a plasma power of 800 W, a radio frequency of 13.56 MHz, and a deposition time of 90 s.

[0070] (5) After the main deposition is completed, nitrogen gas is introduced for purging, and then the residual gas in the cavity is evacuated through a vacuum device to restore the cavity to a vacuum state, and the deposited BPSG film is taken out, with a thickness of 800 nm.

[0071] Example 3 This embodiment provides a preparation process of a BPSG film, and the preparation process includes the following steps: (1) In a single-chamber multi-wafer PECVD device, a plurality of wafers are independently placed on different carriers, and the plurality of wafers are heated to 450° C. using a heater.

[0072] (2) A precursor source is introduced into the chamber by means of a gas distribution plate and stabilized at the first condition within 10 seconds, and the chamber pressure is increased from 20 mtorr to 2.5 torr; wherein the precursor source comprises 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 comprises: a flow rate of 250 sccm for the silicon source precursor, a flow rate of 700 sccm for the boron source precursor, and a flow rate of 400 sccm for the phosphorus source precursor.

[0073] (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 187.5Å; wherein the second condition includes: a flow rate of the silicon source precursor is 250sccm, a flow rate of the boron source precursor is 500sccm, a flow rate of the phosphorus source precursor is 400sccm, t=1.5s, a chamber pressure of 2.5torr, a plasma power of 1200W, and a radio frequency frequency of 13.56MHz.

[0074] (4) Main deposition: under the third condition, continue to deposit on the surface of the BPSG pre-deposited film; wherein the third condition includes: a flow rate of 250 sccm for the silicon source precursor, a flow rate of 700 sccm for the boron source precursor, a flow rate of 400 ccm for the phosphorus source precursor, a plasma power of 1200 W, a radio frequency frequency of 13.56 MHz, and a deposition time of 120 s.

[0075] (5) After the main deposition is completed, nitrogen gas is introduced for purging, and then the residual gas in the cavity is evacuated through a vacuum device to restore the cavity to a vacuum state, and the deposited BPSG film is taken out, with a thickness of 1500 nm.

[0076] Example 4 The difference between this embodiment and embodiment 1 is that the flow rate of the boron source precursor in step (3) is 400 sccm, and t=2.5 s.

[0077] The rest of the preparation process and parameters were the same as those in Example 1.

[0078] Example 5 The difference between this embodiment and embodiment 1 is that the flow rate of the boron source precursor in step (3) is 500 sccm, and t=1.5 s.

[0079] The rest of the preparation process and parameters were the same as those in Example 1.

[0080] Example 6 The difference between this embodiment and embodiment 1 is that the flow rate of the boron source precursor in step (3) is 350 sccm.

[0081] The rest of the preparation process and parameters were the same as those in Example 1.

[0082] Example 7 The difference between this embodiment and embodiment 1 is that the flow rate of the boron source precursor in step (3) is 550 sccm.

[0083] The rest of the preparation process and parameters were the same as those in Example 1.

[0084] Example 8 The difference between this embodiment and embodiment 1 is that in step (3), t=1s.

[0085] The rest of the preparation process and parameters were the same as those in Example 1.

[0086] Example 9 The difference between this embodiment and embodiment 1 is that in step (3), t=3.5s.

[0087] The rest of the preparation process and parameters were the same as those in Example 1.

[0088] Example 10 The difference between this embodiment and embodiment 1 is that the flow rate of the silicon source precursor in step (3) is 100 sccm.

[0089] The rest of the preparation process and parameters were the same as those in Example 1.

[0090] Embodiment 11 The difference between this embodiment and embodiment 1 is that the flow rate of the phosphorus source precursor in step (3) is 200 sccm.

[0091] The rest of the preparation process and parameters were the same as those in Example 1.

[0092] Comparative Example 1 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.

[0093] The rest of the preparation process and parameters were the same as those in Example 1.

[0094] Comparative Example 2 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.

[0095] The rest of the preparation process and parameters were the same as those in Example 1.

[0096] Comparative Example 3 The difference between this comparative example and Example 1 is that in step (3), t=5s.

[0097] The rest of the preparation process and parameters were the same as those in Example 1.

[0098] Comparative Example 4 The difference between this comparative example and Example 1 is that step (3) is not performed.

[0099] The rest of the preparation process and parameters were the same as those in Example 1.

[0100] 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.

[0101] Comparative Example 5 The difference between this embodiment and embodiment 1 is that the flow rate of the boron source precursor in step (3) is 700 sccm.

[0102] The rest of the preparation process and parameters were the same as those in Example 1.

[0103] Comparative Example 6 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 remains consistent with the flow rate of the boron source precursor in the first condition.

[0104] The rest of the preparation process and parameters were the same as those in Example 1.

[0105] Comparative Example 7 The difference between this embodiment and embodiment 1 is that in step (3) in the second condition, the flow rate of the silicon source precursor is adjusted to 150 sccm, while the flow rate of the boron source precursor remains consistent with the flow rate of the boron source precursor in the first condition.

[0106] The rest of the preparation process and parameters were the same as those in Example 1.

[0107] Performance Testing 1. The reaction rates of the products obtained in the above-mentioned embodiments and comparative examples were tested. The reaction rate refers to the ratio of the deposited film thickness to the deposition time.

[0108] 2. A thickness uniformity test was performed on several products obtained in the above embodiments and comparative examples. The test steps included: removing 5 mm from the edge of the product, and then using an ellipsometer to test the thickness of 49 points on the surface of the film to calculate the thickness uniformity of the film, and taking the average value. The measured film thickness uniformity (U%) = thickness standard deviation / thickness average value × 100%.

[0109] 3. The B content in several BPSG films provided in the above embodiments and comparative examples is analyzed by secondary ion mass spectrometry, and the range between the maximum and minimum values ​​in the calculated curve is calculated as the range uniformity. If the range uniformity is ≤2%, it is recorded as small fluctuation. If the range uniformity is within the range of 2-5%, it is recorded as small fluctuation. If the range uniformity is within the range of 5-10%, it is recorded as large fluctuation. If the range uniformity is greater than 10%, it is recorded as large fluctuation.

[0110] The above test results are shown in Table 1.

[0111] Table 1 analyze: As can be seen from Table 1, 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 phenomenon of the BPSG film, helping to improve the etching uniformity of the BPSG film, and effectively preventing the phenomenon of graphic 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-wafer PECVD equipment.

[0112] By comparing Example 1 with Examples 6-7, it can be seen that a smaller or larger flow rate of the boron source precursor in step (3) will result in more obvious delamination in the obtained BPSG film, which is not conducive to subsequent etching and the stability of the semiconductor device.

[0113] By comparing Example 1 with Examples 8-9, it can be seen that a shorter or longer pre-deposition time in step (3) is not conducive to uniform deposition of element B, resulting in more obvious delamination in the obtained BPSG film, which is not conducive to subsequent etching and the stability of the semiconductor device.

[0114] By comparing Example 1 with Examples 10-11, it can be seen that if the flow rate of the silicon source precursor in step (3) is too small, the composition of the BPSG pre-deposition film will be unstable, which will easily lead to stratification in the BPSG film; if the flow rate of the phosphorus source precursor in step (3) is too small, the composition of the BPSG pre-deposition film will be unstable, which will easily lead to stratification in the BPSG film.

[0115] From the comparison between Example 1 and Comparative Example 2, it can be seen that 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 the B element in the BPSG film is uneven and a multilayer structure exists.

[0116] By comparing Example 1 with Comparative Example 3, it can be seen that 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 the B element in the BPSG film is uneven and a multi-layer structure exists.

[0117] By comparing Example 1 with Comparative Example 4, it can be seen that if step (3) is not performed, the secondary ion mass spectrometry analysis curve of the B content in the BPSG film fluctuates greatly, indicating that the distribution of the B element in the BPSG film is uneven and a multilayer structure exists.

[0118] By comparing Example 1 with Comparative Example 5, it can be seen that if the flow rate of the boron source precursor in step (3) is too large, it is not only not conducive to eliminating the stratification phenomenon of the BPSG film, but also makes the stratification phenomenon more obvious.

[0119] By comparing Example 1 with Comparative Examples 6-7, it can be seen that if, during the pre-deposition process, the flow rate of the phosphorus source precursor is reduced and the flow rate of the boron source precursor is kept consistent with the flow rate of the boron source precursor in the first condition, the boron content in the deposition process is not affected, so that the uneven distribution of the boron content cannot be improved, and stratification still exists; if, during the pre-deposition process, the flow rate of the silicon source precursor is reduced and the flow rate of the boron source precursor is kept consistent with the flow rate of the boron source precursor in the first condition, the boron content in the deposition process is not affected, so that the uneven distribution of the boron content cannot be improved, and stratification still exists.

[0120] It should be noted that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and 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.

Images