Selective etching solution for SiO2 and IGZO

Abstract

The invention discloses a selective etching solution for SiO2 and IGZO. The selective etching solution comprises an organic solvent, a fluorine-containing substance, a pH regulator, a passivating agent and the balance of water. The etching liquid can selectively etch SiO2 and basically does not etch IGZO, the selection ratio of the liquid medicine to SiO2 and IGZO is larger than 500, and in addition, the composition has the long service life.

Description

Technical Field

[0001] The present invention relates to a composition of a selective etching solution for SiO 2 and IGZO, which is used to selectively remove SiO 2 without substantially corroding IGZO, achieving the purpose of selectively etching SiO 2 and IGZO. Background Art

[0002] IGZO (indium gallium zinc oxide) is the abbreviation of indium gallium zinc oxide, also known as metal oxide. Compared with the traditional amorphous silicon a-Si material, IGZO has a higher carrier mobility, about 10 cm 2 / Vs. The three-dimensional storage structure of IGZO 2T0C DRAM has successfully achieved characteristics such as high density, low power consumption, and high-speed data transmission. Using an IGZO silicon semiconductor FET with an asymmetric double-gate structure, charges are stored through the floating body effect (without the need for an external capacitor), effectively reducing the occupied space and standby power consumption of SRAM. Therefore, developing a selective etching solution for SiO 2 and IGZO is beneficial to meeting customer needs and promoting the development and progress of the semiconductor manufacturing process.

[0003] Currently, the ones that can quickly etch SiO 2 can only be under acidic conditions and contain a certain amount of fluoride ions. Under alkaline and fluorine-containing conditions, the etching rate of SiO 2 will be very slow because SiO 2 usually reacts with HF 2- ions, and it is difficult for HF 2- ions to exist in the system under alkaline conditions. For IGZO, it is an amphoteric oxide and will be severely corroded under acidic or alkaline conditions.

[0004] Therefore, developing an etching solution that can quickly remove SiO 2 without corroding IGZO helps to solve the current technical problems and promote scientific and technological progress. Summary of the Invention

[0005] The technical problem to be solved by the invention is to develop an etching solution composition for selectively etching SiO 2 and IGZO, and its selectivity ratio for SiO 2 and IGZO is greater than 500.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The present invention provides a SiO 2A selective etching solution composition for IGZO, which is prepared from the following raw materials. The raw materials include the following components by mass fraction: 65 - 75% organic solvent, 1% - 3% fluorine-containing substance, 0.1% - 5% pH regulator, 0.1% - 3% passivator, and the balance water. The mass fraction is the percentage of the mass of each component in the total mass of the raw materials.

[0008] The organic solvent is one or more of ethylene glycol, propylene glycol, glycerol, or tetrahydrofurfuryl alcohol.

[0009] The fluorine-containing substance is one or more of hydrofluoric acid, ammonium fluoride, or ammonium bifluoride.

[0010] The pH regulator may also optionally include a base or an acid to adjust the pH of the working composition. In the present invention, acetic acid or ammonia water is preferably used for pH adjustment, and the use of other substances with acid-base adjustment is also within the scope of protection of the present invention.

[0011] The passivator includes a class of biotin passivators, and the class of biotin passivators includes one or more combinations of D-biotin, D-biotin methyl ester, or N-succinimidyl D-biotin.

[0012] The passivator also includes another class of passivators which are compounds having the following structural general formula (I): Formula (I)

[0013]

[0014] Wherein the R1 and R3 groups are each independently selected from H, OH, COOH, or (CH 2 ) n OH, and the R2 group is selected from C 10 ~C 12 alkyl.

[0015] In some preferred cases, the passivator is one or more of 3,4,5-trihydroxydecylbenzene, 3,4,5-trihydroxyundecylbenzene, or 3,4,5-trihydroxydodecylbenzene.

[0016] The passivator needs to be used in combination (i.e., the combination of a class of biotin passivators and another class of passivators) to achieve a high selectivity ratio of SiO 2 and IGZO.

[0017] The pH of the composition is 3 - 6, preferably pH 4.5 - 5.5.

[0018] The present invention also provides a SiO 2Preparation method of selective etching liquid composition for SiO and IGZO, which comprises the following steps: in the mixing, preferably add the solid components in the raw material components to the liquid components, stir evenly, and then SiO 2 and the selective etching liquid composition for IGZO can be obtained.

[0019] The use temperature of the composition is 20 - 30 °C, preferably 25 °C, and the use time is 60s - 300s. The specific use temperature and time need to be reasonably adjusted according to the self-process.

[0020] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0021] The reagents and raw materials used in the present invention are all commercially available.

[0022] The positive and progressive effects of the present invention are as follows: the composition of the present invention can selectively etch SiO 2 and IGZO, and its selectivity ratio for SiO 2 and IGZO is greater than 500, and the service life of the composition > 24h. Description of the Drawings

[0023] Figure 1 It is the SEM images before and after etching the 230nm IGZO / 60nm SiO 2 laminated wafer in Example 1. Detailed Description of the Invention

[0024] The present invention will be further illustrated by the following examples, but the present invention is not limited to the scope of the examples. The experimental methods without specific conditions in the following examples are carried out according to the conventional methods and conditions, or selected according to the product specifications.

[0025] SiO 2 Preparation of the selective etching liquid composition for IGZO: The types of organic solvents, fluorine-containing substances, pH regulators and passivators are listed in Table 1 respectively. The water in the composition is ultrapure water, and the balance is made up with ultrapure water.

[0026] Table 1 Types of each raw material component of the selective etching liquid composition for SiO 2 and IGZO

[0027]

[0028]

[0029] Table 2 Contents of each substance of the selective etching liquid composition for SiO 2 and IGZO

[0030]

[0031] Cut the silicon wafers of SiO 2 (SiO film prepared by the PETEOS process 2 layer) and IGZO into 2 cm * 2 cm pieces.

[0032] Preparation before etching: Pretreat the sample to be detected with 200:1 DHF at room temperature for 30 s to remove the SiO 2 surface oxide layer or stains, then wash with deionized water and dry with nitrogen.

[0033] Preparation before etching: Pretreat the sample to be detected with 1% oxalic acid aqueous solution at room temperature for 30 s to remove the surface oxide layer or stains of IGZO, then wash with deionized water and dry with nitrogen.

[0034] Etching experiment: Etch the pretreated test sample with the etching solution composition at 25 °C for 300 s, then wash with deionized water and dry with nitrogen.

[0035] Method for measuring the etching rate : Detect the thickness of the sample before and after etching respectively. For SiO 2 and IGZO samples, the thickness is measured using an optical ellipsometer.

[0036] Method for measuring the service life: Heat the SiO 2 and IGZO selective etching solution composition at 25 °C. After 8 h, measure the etching rates of SiO 2 and IGZO, and calculate the selectivity ratio of SiO 2 and IGZO. Record the time when the selectivity ratio decays by 20% as the service life of the etching solution. The etching effect is shown in Table 3.

[0037] Table 3 Etching rates of SiO 2 and IGZO selective etching solution composition Selectivity ratio, service life and pH

[0038]

[0039]

[0040] From the data of the example compositions in Table 3, it can be seen that for the examples the etching rate of IGZO is SiO 2 and the selectivity ratio of IGZO is greater than 500, and the service life of both is greater than 24 h, indicating that the example compositions can quickly etch SiO 2Removed without etching IGZO. From the data of the comparative examples in Table 3, it can be seen that without adding passivators 1 and 2, the selectivity of the composition is only 5.4, while when adding passivator 1 or 2 alone, the selectivity is only around 10.4 - 12.4, indicating that only when passivators 1 and 2 are used in combination can the selectivity of the composition reach a relatively high level.

[0041] Table 4 SiO under different contents of organic solvents 2 Etching rates and selectivities of and IGZO

[0042]

[0043] From the data in Table 4, it can be seen that as the content of the organic solvent in the etching solution increases, the selectivity of SiO 2 and IGZO shows a trend of increasing first and then decreasing. When the content of the organic solvent is in the range of 65 - 75%, the selectivity of SiO 2 and IGZO is greater than 20, reaching the maximum etching selectivity. This is because as the proportion of the organic solvent becomes larger, the ratio of F to H 2 O decreases, reducing the activity of F in the etching solution and being able to improve the selectivity of SiO 2 and IGZO. When the content of the organic solvent is low, the activity of F is strong, and the etching rate of IGZO is relatively fast, so the selectivity is relatively low. Therefore, the content of the organic solvent in the composition needs to be controlled to make the selectivity of SiO 2 and IGZO reach a relatively high level.

[0044] Table 5 Adjusting the etching rates and selectivities of SiO 2 and IGZO at different pH values using a pH regulator (ammonia water) (the pH regulator is ammonia water)

[0045]

[0046] From the data of the comparative examples in Table 5, it can be seen that when the pH is 3.0, although the selectivity of SiO 2 and IGZO can reach 5.3, the etching rate of IGZO is relatively large. As the pH increases, the rates of SiO 2 and IGZO both decrease. When pH = 4.5, the rate of IGZO can decrease from to Continuing to decrease the pH will not significantly reduce the etching rate of IGZO, but will instead reduce the selectivity of SiO 2 and IGZO. Therefore, the pH needs to be controlled within the range of 4.5 - 5.5 to maintain good etching selectivity.

[0047] Based on the formulation of Example 1, different types and contents of inhibitors were added to prepare Comparative Examples 13 - 17.

[0048] Table 6 Etching Rates and Selectivity Ratios of the Etching Solution for SiO 2 and IGZO with Different Inhibitors Added

[0049]

[0050]

[0051] As can be seen from the data in Table 6, adding only one passivator alone cannot reduce the etching rate of IGZO to the following. Only by using the two in combination can the etching rate of IGZO be effectively reduced. From the data of Comparative Examples 15 and 16, it can be obtained that the passivator 3,4,5-trihydroxydecylbenzene with a long alkyl chain has an obvious inhibitory effect compared with pyrogallol without an alkyl group. The former can reduce the rate of IGZO by 50%, while pyrogallol has almost no inhibitory effect. This is due to the C 10 group of 3,4,5-trihydroxydecylbenzene being a hydrophobic group, which is beneficial to reducing the corrosion of IGZO by the etching solution.

[0052] The CN111902569B patent uses an organic phosphonic acid as a corrosion inhibitor for IGZO, which has a certain inhibitory effect and can reduce the etching rate of IGZO in this formulation to However, the selectivity ratio of SiO 2 and IGZO is much smaller than the selectivity ratio of the examples.

[0053] The foregoing descriptions of the embodiments and preferred embodiments should be regarded as illustrative rather than limiting the invention defined by the claims. It is readily understood that many variations and combinations of the features set forth above can be utilized without departing from the invention set forth in the claims. Such variations are not considered to depart from the spirit and scope of the invention, and all such variations are intended to be included within the scope of the following claims.

Claims

1. An etching solution composition, characterized in that: The invention is prepared from the following raw materials, which include the following components in mass fractions: 65-75% organic solvent, 1%-3% fluorine-containing substance, 0.1%-5% pH regulator, 0.1%-3% passivator and the balance water, wherein the mass fraction is the percentage of the mass of each component to the total mass of the raw materials.

2. The etching solution composition according to claim 1, characterized in that The organic solvent is one or more of ethylene glycol, propylene glycol, glycerol or tetrahydrofurfuryl alcohol.

3. The etching solution composition according to claim 1, characterized in that The fluorine-containing substance is one or more of hydrofluoric acid, ammonium fluoride or ammonium bifluoride.

4. The etching solution composition according to claim 1, characterized in that The pH adjuster includes alkali and / or acid and keeps the pH value between 3 and 6.

5. The etching solution composition according to claim 4, characterized in that The base is selected from ammonia water, tetramethylammonium hydroxide TMAH, organic alcohol amine or a mixture thereof; The acid includes sulfuric acid, phosphoric acid, hydrobromic acid, hydrochloric acid, acetic acid, amino acid, organic sulfonic acid or a mixture thereof, and the pH value is maintained at 4.5 to 5.

5.

6. The etching solution composition according to claim 1, characterized in that The passivating agent includes a class of biotin passivating agents, and the class of biotin passivating agents includes one or a combination of D-biotin, D-biotin methyl ester or N-succinimidyl D-biotin.

7. The etching solution composition according to claim 6, characterized in that The passivating agent also includes another type of passivating agent which is a compound having the following structural formula (I): Formula (I) Wherein R1 and R3 groups are each independently selected from H, OH, COOH or (CH2) n OH, R2 group is selected from C 10 ~C 12 of alkyl.

8. The etching solution composition according to claim 7, wherein the passivating agent is one or more of 3,4,5-trihydroxydecylbenzene, 3,4,5-trihydroxyundecylbenzene or 3,4,5-trihydroxydodecylbenzene.

9. A selective etching solution composition of SiO2 and IGZO, characterized in that: The composition is the composition according to any one of claims 1 to 8, and the composition is used in the selective etching of SiO2 and IGZO.

10. The selective etching solution composition of SiO2 and IGZO according to claim 9, characterized in that: The etching temperature of the selective etching solution composition is room temperature.

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