A method to improve the deposition of SiO on InGaAs surface 2 Method of shedding

Abstract

The present invention discloses a method for improving the shedding of SiO2 deposited on the surface of InGaAs, comprising the following steps: (1) after the epitaxial structure growth of the wafer is completed, the surface INP material is first corroded with hydrochloric acid, and then placed in an ammonium fluoride solution to corrode the exposed InGaAs for 3 minutes, and then rinsed with water and dried with a nitrogen gun, and dried to ensure that the wafer is completely dry; (2) by adding nitrous oxide cleaning in the pre-cleaning stage of depositing SiO2, and appropriately increasing the cleaning flow and radio frequency power. The method of the present invention solves the problem of PECVD depositing SiO2 on the surface of InGaAs, pre-treats the surface of the InGaAs substrate, optimizes the recipe for growing SiO2, makes the SiO2 film adhere better to the InGaAs on the wafer, and reduces the occurrence of other SiO2 film abnormalities.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor chip manufacturing, and in particular relates to a method for improving the shedding of SiO2 deposited on the surface of InGaAs. Background Art

[0002] At present, the deposition of SiO2 on the surface of InGaAs mainly uses pure hydrochloric acid etching liquid to etch the INP material on the surface of the wafer for a few seconds to expose the InGaAs material, rinse it with water and blow it dry with a nitrogen gun, and then prepare to send it to the PECVD chamber for SiO2 film deposition. This layer serves as a mask protection layer before ridge etching, but the existing technology has the following problems: when the ridge etching process is completed, a large amount of SiO2 used as the surface mask layer will fall off, mainly distributed on the edges of both sides of the ridge groove; the above SiO2 shedding phenomenon will cause the etching liquid to enter the surface material on the ridge, causing corrosion to varying degrees, affecting the performance and even reliability of chip manufacturing. Summary of the invention

[0003] The reason for the SiO2 shedding phenomenon is probably due to the poor interface adhesion of InGaAs / SiO2; at the same time, the setting of the SiO2 recipe in PECVD is unreasonable; finally, it is also related to the surface characteristics of InGaAs. In order to solve the deficiencies in the above-mentioned technology, the purpose of the present invention is to provide a method for improving the shedding of SiO2 deposited on the InGaAs surface. Before depositing SiO2, the surface material of the wafer is respectively corroded with hydrochloric acid and ammonium fluoride to remove the exposed InGaAs (the presence of Ga2O3 and As2O3 will reduce the adhesion between InGaAs and SiO2), and after drying with a nitrogen gun, it is placed in a baking tray at 115°C and baked for 2 minutes to ensure that the wafer is completely dry, and then the PECVD SiO2 growth program is optimized to effectively prevent the subsequent SiO2 shedding phenomenon.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A method for improving the shedding of SiO2 deposited on the InGaAs surface comprises the following steps:

[0006] Step 1: Wafer pretreatment:

[0007] After the epitaxial structure growth of the wafer is completed, the INP material on the surface is first corroded with hydrochloric acid, and then placed in an ammonium fluoride solution to corrode the exposed InGaAs for 3 minutes. Afterwards, it is rinsed clean with water and blown dry with a nitrogen gun and dried to ensure that the wafer is completely dry.

[0008] Step 2: Deposition of SiO2:

[0009] (1) N2 was introduced into the chamber at a flow rate of 700 sccm and a chamber pressure of 1400 mTorr for 60 s.

[0010] (2) Pre-cleaning stage 1: N2 flow rate is 500-1000sccm, chamber pressure is 1000-1500mTorr, RF power is 50-120w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700-1000sccm, chamber pressure is 1300-1500mTorr, and duration is 60s;

[0011] (2) Pre-cleaning second stage: N2O flow rate is 500-1000sccm, chamber pressure is 1000-1500mTorr, RF power is 50-120w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700-1000sccm, chamber pressure is 1300-1500mTorr, and duration is 60s;

[0012] (3) Pre-cleaning third stage: N2 flow rate is filled into the chamber at 500-1000sccm, NH3 flow rate is filled into the chamber at 10-30sccm, chamber pressure is 1000-1500mTorr, RF power is 50-120w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700-1000sccm, chamber pressure is 1300-1500mTorr, and duration is 60s;

[0013] (4) SiO2 film deposition preparation stage: N2 flow rate is 700 sccm, SiH4 flow rate is 100 sccm, N2O flow rate is 700-800 sccm, chamber pressure is 1300-1500 mTorr, and duration is 60 s;

[0014] (5) SiO2 thin film deposition: N2 flow rate is 700-1000sccm, SiH4 flow rate is 90-110sccm, N2O flow rate is 700-800sccm, chamber pressure is 1300-1500 mTorr, RF power is 50-70w, and the duration is determined by the film thickness.

[0015] Furthermore, the drying in step 1 is specifically to place the wafer in a baking tray at 115° C. and bake for 2 minutes.

[0016] Furthermore, the deposition of SiO2 in step 2 is specifically as follows:

[0017] (1) N2 was introduced into the chamber at a flow rate of 700 sccm and a chamber pressure of 1400 mTorr for 60 s.

[0018] (2) Pre-cleaning stage 1: N2 flow rate is 700sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s;

[0019] (2) Pre-cleaning stage 2: N2O flow rate is 700sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s;

[0020] (3) Pre-cleaning third stage: N2 flow rate is filled into the chamber at 700sccm, NH3 flow rate is filled into the chamber at 10sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s;

[0021] (4) Preparation stage for SiO2 film deposition: N2 flow rate is 700 sccm, SiH4 flow rate is 100 sccm, N2O flow rate is 710 sccm, chamber pressure is 1200 mTorr, and duration is 60 s;

[0022] (5) SiO2 thin film deposition: N2 flow rate is 700 sccm, SiH4 flow rate is 100 sccm, N2O flow rate is 710 sccm, chamber pressure is 1200 mTorr, RF power is 50 W, duration is determined by film thickness, and deposition rate is about 780 A / min.

[0023] Beneficial effects of the present invention:

[0024] (1) The surface property of InGaAs is that the surface contamination introduced by Purge before the epitaxial growth of INP affects the adhesion between SiO2 and InGaAs. The presence of Ga2O3 and As2O3 will reduce the adhesion between InGaAs and SiO2. The InGaAs surface can be cleaned by ammonium fluoride etching.

[0025] (2) Parameter setting of SiO2 deposition program. Appropriately increasing the N2 flow rate and chamber pressure in the pre-cleaning step helps to clean the chamber more thoroughly. Nitrogen is also introduced after each pre-cleaning step to purge some particles after the previous reaction and remove the by-products produced by the previous reaction step, thereby restoring the environmental atmosphere in the chamber.

[0026] (3) Pre-cleaning is divided into three steps, namely nitrogen, nitrous oxide, and ammonia + nitrogen. Compared with the existing technology, nitrous oxide cleaning is added, and the cleaning flow rate and RF power are appropriately increased. N2O plasma treatment is introduced to reduce the power of RF treatment, avoid damage to the surface InGaAs material caused by over-treatment, and play a role in protecting the base material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a picture showing the SiO2 peeling off on the wafer surface after the ridge waveguide process in Example 1 (magnified 20 times by microscope);

[0028] Figure 2 This is a picture of SiO2 falling off on the wafer surface after the ridge waveguide process of comparative example 1 (microscope magnification 20 times). DETAILED DESCRIPTION

[0029] In order to make the above features and advantages of the present invention more clearly understood, the following embodiments are given for detailed description. The methods of the present invention are all conventional methods in the art unless otherwise specified. Example 1

[0030] A method for improving the shedding of SiO2 deposited on the InGaAs surface comprises the following steps:

[0031] Step 1: Wafer pretreatment:

[0032] After the wafer has completed epitaxial structure growth, the INP material on the surface is first corroded with hydrochloric acid, and then placed in ammonium fluoride solution to corrode the exposed InGaAs for 3 minutes. Afterwards, it is rinsed clean with water and blown dry with a nitrogen gun, and then placed in a baking tray at 115°C for 2 minutes to ensure that the wafer is completely dry.

[0033] Step 2: Deposition of SiO2 (1500A):

[0034] (1) N2 was introduced into the chamber at a flow rate of 700 sccm and a chamber pressure of 1400 mTorr for 60 s.

[0035] (2) Pre-cleaning stage 1: N2 flow rate is 700sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s;

[0036] (2) Pre-cleaning stage 2: N2O flow rate is 700sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s;

[0037] (3) Pre-cleaning third stage: N2 flow rate is filled into the chamber at 700sccm, NH3 flow rate is filled into the chamber at 10sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s;

[0038] (4) Preparation stage for SiO2 film deposition: N2 flow rate is 700 sccm, SiH4 flow rate is 100 sccm, N2O flow rate is 710 sccm, chamber pressure is 1200 mTorr, and duration is 60 s;

[0039] (5) SiO2 thin film deposition: N2 flow rate 700 sccm, SiH4 flow rate 100 sccm, N2O flow rate 710 sccm, chamber pressure 1200 mTorr, RF power 50 W, duration 120 s.

[0040] Step 3: Perform ridge waveguide process, after etching out the ridge morphology, confirm whether there is SiO2 shedding on the wafer surface.

[0041] Depend on Figure 1 It can be seen that there is no SiO2 shedding on the entire wafer surface.

[0042] Table 1 is the process parameters of Example 1

[0043]

[0044] Comparative Example 1

[0045] Step 1: Wafer pretreatment:

[0046] After the wafer has completed the epitaxial structure growth, pure hydrochloric acid is used to corrode the INP material on the surface to expose the InGaAs material. After flushing with water, it is blown dry with a nitrogen gun and is ready to be sent to the PECVD chamber for SiO2 film deposition.

[0047] Step 2: Deposition of SiO2 (1500A):

[0048] (1) Pre-cleaning stage 1: N2 flow rate 500sccm, chamber pressure 1200mTorr, RF power 50w, duration 120s before breaking;

[0049] (2) Pre-cleaning stage 3: N2 flow rate is 500sccm, NH3 flow rate is 10sccm, chamber pressure is 1200mTorr, RF power is 50w, and the chamber is broken after 120s;

[0050] (4) SiO2 film deposition preparation stage: SiH4 flow rate is 100 sccm, N2O flow rate is 710 sccm, chamber pressure is 1200 mTorr, and duration is 60 s;

[0051] (5) SiO2 thin film deposition: SiH4 flow rate is 100 sccm, N2O flow rate is 710 sccm, chamber pressure is 1200 mTorr, RF power is 50 W, and duration is 120 s.

[0052] Step 3: Perform ridge waveguide process, after etching out the ridge morphology, confirm whether there is SiO2 shedding on the wafer surface.

[0053] Depend on Figure 2 It can be seen that the ridges on the entire wafer surface are 100% debonded, and the debonding on both sides of the groove is 10-15%, distributed at the edge.

[0054] Table 2 is the process parameters of Comparative Example 1

[0055]

[0056] Comparative Example 2

[0057] Step 1: Wafer pretreatment:

[0058] After the wafer has completed the epitaxial structure growth, pure hydrochloric acid is used to corrode the INP material on the surface to expose the InGaAs material. After flushing with water, it is blown dry with a nitrogen gun and is ready to be sent to the PECVD chamber for SiO2 film deposition.

[0059] Step 2: Deposition of SiO2 (1500A):

[0060] (1) N2 was introduced into the chamber at a flow rate of 700 sccm and a chamber pressure of 1400 mTorr for 60 s.

[0061] (2) Pre-cleaning stage 1: N2 flow rate is 700sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s;

[0062] (2) Pre-cleaning stage 2: N2O flow rate is 700sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s;

[0063] (3) Pre-cleaning third stage: N2 flow rate is filled into the chamber at 700sccm, NH3 flow rate is filled into the chamber at 10sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s;

[0064] (4) Preparation stage for SiO2 film deposition: N2 flow rate is 700 sccm, SiH4 flow rate is 100 sccm, N2O flow rate is 710 sccm, chamber pressure is 1200 mTorr, and duration is 60 s;

[0065] (5) SiO2 thin film deposition: N2 flow rate 700 sccm, SiH4 flow rate 100 sccm, N2O flow rate 710 sccm, chamber pressure 1200 mTorr, RF power 50 W, duration 120 s.

[0066] Step 3: Perform ridge waveguide process, after etching out the ridge morphology, confirm whether there is SiO2 shedding on the wafer surface. Comparative Example 3

[0067] Step 1: Wafer pretreatment:

[0068] After the wafer has completed epitaxial structure growth, the INP material on the surface is first corroded with hydrochloric acid, and then placed in ammonium fluoride solution to corrode the exposed InGaAs for 3 minutes. Afterwards, it is rinsed clean with water and blown dry with a nitrogen gun, and then placed in a baking tray at 115°C for 2 minutes to ensure that the wafer is completely dry.

[0069] Step 2: Deposition of SiO2 (1500A):

[0070] (1) Pre-cleaning stage 1: N2 flow rate 500sccm, chamber pressure 1200mTorr, RF power 50w, duration 120s before breaking;

[0071] (2) Pre-cleaning stage 3: N2 flow rate is 500sccm, NH3 flow rate is 10sccm, chamber pressure is 1200mTorr, RF power is 50w, and the chamber is broken after 120s;

[0072] (4) SiO2 film deposition preparation stage: SiH4 flow rate is 100 sccm, N2O flow rate is 710 sccm, chamber pressure is 1200 mTorr, and duration is 60 s;

[0073] (5) SiO2 thin film deposition: SiH4 flow rate is 100 sccm, N2O flow rate is 710 sccm, chamber pressure is 1200 mTorr, RF power is 50 W, and duration is 120 s.

[0074] Step 3: Perform ridge waveguide process, after etching out the ridge morphology, confirm whether there is SiO2 shedding on the wafer surface.

[0075] Table 3 shows the SiO2 shedding conditions of Example 1 and Comparative Examples 1-3

[0076]

[0077] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for improving the shedding of SiO2 deposited on the surface of InGaAs, characterized in that: The following steps are involved: Step 1: Wafer pretreatment: After the epitaxial structure growth of the wafer is completed, the INP material on the surface is first corroded with hydrochloric acid, and then placed in an ammonium fluoride solution to corrode the exposed InGaAs for 3 minutes. Afterwards, it is rinsed clean with water and blown dry with a nitrogen gun and dried to ensure that the wafer is completely dry. Step 2: Deposition of SiO2: (1) N2 was introduced into the chamber at a flow rate of 700 sccm and a chamber pressure of 1400 mTorr for 60 s. (2) Pre-cleaning stage 1: N2 flow rate is 500-1000sccm, chamber pressure is 1000-1500mTorr, RF power is 50-120w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700-1000sccm, chamber pressure is 1300-1500mTorr, and duration is 60s; (2) Pre-cleaning second stage: N2O flow rate is 500-1000sccm, chamber pressure is 1000-1500mTorr, RF power is 50-120w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700-1000sccm, chamber pressure is 1300-1500mTorr, and duration is 60s; (3) Pre-cleaning third stage: N2 flow rate is filled into the chamber at 500-1000sccm, NH3 flow rate is filled into the chamber at 10-30sccm, chamber pressure is 1000-1500mTorr, RF power is 50-120w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700-1000sccm, chamber pressure is 1300-1500mTorr, and duration is 60s; (4) SiO2 film deposition preparation stage: N2 flow rate is 700 sccm, SiH4 flow rate is 100 sccm, N2O flow rate is 700-800 sccm, chamber pressure is 1200 mTorr, and duration is 60 s; (5) SiO2 thin film deposition: N2 flow rate is 700-1000sccm, SiH4 flow rate is 90-110sccm, N2O flow rate is 700-800sccm, chamber pressure is 1200 mTorr, RF power is 50-70w, and duration is determined by film thickness.

2. The method for improving the shedding of SiO2 deposited on the InGaAs surface according to claim 1, characterized in that: The drying in step 1 is specifically to place the wafer in a baking tray at 115° C. and bake for 2 minutes.

3. The method for improving the shedding of SiO2 deposited on the InGaAs surface according to claim 1, characterized in that: The specific steps of depositing SiO2 in step 2 are as follows: (1) N2 was introduced into the chamber at a flow rate of 700 sccm and a chamber pressure of 1400 mTorr for 60 s. (2) Pre-cleaning stage 1: N2 flow rate is 700sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s; (2) Pre-cleaning stage 2: N2O flow rate is 700sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s; (3) Pre-cleaning third stage: N2 flow rate is filled into the chamber at 700sccm, NH3 flow rate is filled into the chamber at 10sccm, chamber pressure is 1400mTorr, RF power is 100w, and duration is 30s; after cleaning, N2 is introduced into the chamber at a flow rate of 700sccm, chamber pressure is 1400mTorr, and duration is 60s; (4) Preparation stage for SiO2 film deposition: N2 flow rate is 700 sccm, SiH4 flow rate is 100 sccm, N2O flow rate is 710 sccm, chamber pressure is 1200 mTorr, and duration is 60 s; (5) SiO2 thin film deposition: N2 flow rate is 700 sccm, SiH4 flow rate is 100 sccm, N2O flow rate is 710 sccm, chamber pressure is 1200 mTorr, RF power is 50 W, and the duration is determined by the film thickness.

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