TWI277176B - Method for preparing a deep trench - Google Patents

Abstract

A method for preparing a deep trench first forms a trench in a semiconductor substrate and a stacked structure in the trench, wherein the stacked structure includes at least one nitrogen-containing layer. A phosphor-containing oxide layer is then formed on the surface of the nitrogen-containing layer. The phosphor-containing oxide is transformed into an etchant in a steam atmosphere to remove the nitrogen-containing layer in the trench. The phosphor-containing oxide layer in the trench is then removed, and the nitrogen-containing layer can be effectively removed.

Description

1277176 IX. Description of the Invention: [Technical Field] The present invention relates to a method for preparing a deep trench, and more particularly to a method for preparing a deep trench which can be applied to a high-concentration dynamic random access memory. [Prior Art] Capacitors of the dynamic random access memory can be classified into a stacked type and a deep trench type. The stacked capacitors form the surface of the cut substrate, while the deep trench capacitors are formed inside the 7 substrate. In recent years, the degree of accumulation of dynamic random access memory has rapidly increased with the innovation of semiconductor process technology, and in order to achieve high integration (4), the size of transistors and capacitors must be reduced. Since the capacitance of the capacitor is proportional to the surface area of its electrode plate, reducing the size of the capacitor will result in a decrease in the capacitance value, which is not conducive to the judgment of storing data. Therefore, the researchers developed bottle-shaped deep trench capacitors that increase the surface area of the electrode plates formed in the deep trenches by increasing the surface area of the deep trenches in the germanium substrate, thereby increasing the capacitance. 1 to 5 illustrate a method of preparing a bottle-shaped deep trench wood 1 on a substrate 12 without conventional techniques. The method for preparing Baizhi first forms a trench 20 in the germanium substrate 2, and then sequentially forms a hafnium oxide layer 32, a tantalum nitride layer 34, an amorphous germanium layer 36, and a tantalum nitride layer 38. The surface of the substrate 12 and the inside of the trench 20. Thereafter, a photoresist layer (10) is formed on the germanium substrate 12, which fills the trench 20, as shown in FIG. Referring to FIG. 3, a planarization process is performed to remove the photoresist layer 4' on the surface of the germanium substrate 12, and then an etching process is performed to remove the light inside the trench 20.

100110.DOC 1277176 Resisting layer 40 to a predetermined depth 42. Thereafter, a wet etching process is performed, for example, by selectively buffering hydrofluoric acid (BHF) or dip to selectively remove % of the tantalum nitride layer inside the trench 20 and not covered by the photoresist layer 4?.

Referring to FIG. 4, a wet etching process is performed to remove the photoresist layer 4 in the trench 2, and then a thermal oxidation process is performed to expose the amorphous germanium layer in the trench 20 without being covered by the tantalum nitride layer 38. 36 is oxidized into a mask layer. Thereafter, a wet etching process is performed to remove the hafnium oxide layer 32, the hafnium nitride layer 34, the amorphous germanium layer 36, and the tantalum nitride layer % below the predetermined depth 42. Next, a wet etching process is performed to etch the ruthenium substrate 12 that is not covered by the mask layer in the trench 2 to form the vial deep trench 1 as shown in FIG. As described above, the prior art utilizes a wet etching process to remove the hafnium oxide layer 32, the tantalum nitride layer, the amorphous layer 81, and the nitrogen cut layer 38 inside the trench 2 and below the predetermined depth 42. . However, as the aperture of the trench 2() is reduced, the etching liquid is not easily transported to a predetermined depth 42 below the trench 2, resulting in a poor rate of the (4) process. That is, the rate of the (4) engraving process is limited by the reduced aperture and the depth of growth of the trench 2, and cannot be effectively improved. SUMMARY OF THE INVENTION The main object of the present invention is to provide a method for preparing a deep trench which can be applied to a high-concentration dynamic random access memory, which utilizes a liquid oxide formed by reacting an oxide layer with water vapor to remove - The nitrogen-containing layer at the bottom of the deep trench" thus solves the problem that the conventional (four) liquid is not easily transported to the bottom of the deep trench. To achieve the above object, the present invention discloses a method for preparing a deep trench.

J00110.DOC 1277176 The method for preparing the wood groove; firstly forming at least one trench in the half of the conductor substrate, and then forming a stacked structure on the inner wall of the trench, wherein the stacked structure comprises at least one nitrogen-containing layer. Thereafter, a phosphorus-containing oxide layer is formed on the surface of the nitrogen-containing layer. Then, converting the phosphorus-containing oxide layer in the trench into

An etchant to remove the nitrogen-containing layer in contact with the phosphorus-containing oxide layer. The method for converting the phosphorus-containing oxide layer located in the trench into an etching solution may be to place the semiconductor substrate in a water vapor environment at a temperature between 7 〇〇 1 〇〇〇〇 C. The layer will react with water vapor to form phosphoric acid which can etch the nitrogen containing layer. After forming the phosphorus-containing oxide layer on the surface of the nitrogen-containing layer, it may further comprise removing a phosphorus-containing oxide layer above the predetermined depth in the trench, and removing the nitrogen-containing layer to be below the predetermined depth. The removal of a phosphorus-containing oxide layer above a predetermined depth in the trench may employ a dry etching process comprising an argon gas, oxygen gas, and octafluorocyclopentene. In addition, removing a phosphorus-containing oxide layer above a predetermined depth in the trench may also first apply a photoresist layer on the surface of the phosphorus-containing oxide layer, and then perform a dry etching process to remove the photoresist layer above the predetermined depth. The gas of the surname engraved process includes oxygen, four gasified carbon, and nitrogen. Thereafter, i (four) system (4) is performed to remove the phosphorus-containing oxide layer above the predetermined depth, and the photoresist layer in the trench is removed. Conventional techniques must transport _ liquid from the opening of the trench to the bottom of the trench to be engraved on the nitrided hard layer at the bottom of the trench, so that the (iv) rate is limited to the aperture size of the trench. In contrast, the present invention removes the nitrogen-containing layer on the inner wall of the trench by using the liquid-containing oxide layer formed in the trench and reacts with the water vapor, and transports the water vapor from the opening of the trench to the bottom without Limited by the size of the aperture of the trench, the present invention can effectively solve -Ί -

100110.DOC 1277176 The problem faced by the prior art in the reduction of the aperture of the trench [Embodiment] Figs. 6 to 1 exemplify a method of preparing the bottle-shaped deep trench 50 of the first example of the present invention. The first method of the first embodiment of the present invention first forms at least one trench 60 in a semiconductor substrate μ, and then forms a stacked structure 54 into the trench.

Within 6 inches, the stack 54 includes an oxygen cut layer 56 and a nitrogen containing layer 58. Thereafter, a phosphorus-containing oxide layer is formed on the surface of the nitrogen-containing layer 58 by a chemical vapor deposition process as shown in FIG. Preferably, the nitrogen-containing layer 58 is a layer of nitrogen arsenide and the layer 4 contains a layer of oxide oxide 62, a layer of BPSG or a layer of broken glass (PSG). Since the trench 6G has a large aspect ratio, the deposition rate of the chemical vapor deposition process at the opening σ of the trench is much higher than that of the inner wall and the bottom of the trench, thereby forming a hole in the trench 6〇. . Referring to Fig. 8, a dry etching process is performed to remove a phosphorus-containing oxide layer 62 of a predetermined depth 64 or higher in the trench (9). Preferably, the etching process of the dry etching process comprises argon gas, oxygen gas, and octafluorocyclopentanyl (C5F8). Thereafter, the semiconductor substrate 52 is placed in a water vapor atmosphere between the temperature boundaries k7〇〇-1〇〇〇〇c for about 30 hours, and the oxide-containing layer 62 remaining in the trench 60 is converted into A liquid entrainment is applied to remove the nitrogen-containing layer 58 below the predetermined depth 64. In particular, the phosphorus element of the phosphorus-containing oxide layer 62 can react with water vapor to form a disk acid, which can leave the nitrogen-containing layer 58. After the etching reaction is completed, the phosphorus-containing oxide layer 62 in the trench 6 is completely removed by using an oxide buffer (for example, buffered hydrofluoric acid (BHF) or diluted hydrofluoric acid (DHF), as shown in FIG. The tea test chart 10 is subjected to a wet etching process to remove below the predetermined depth 64.

100110.DOC

(E 1277176 stack structure 54 (ie, removing yttrium oxide layer 56 below the predetermined depth 64) 'The rice shovel used to dilute hydrofluoric acid or buffered hydrofluoric acid. After that, another fisherman's engraving process is performed. And etching the inner wall of the trench 6〇 below the predetermined depth 64 using an etching solution containing ammonia water to form the bottle-shaped deep trench 5〇. However, the present invention is not limited to forming only a bottle-shaped deep trench, and the stack is considered to be Depending on the configuration of structure 54, the stack structure 54 may further comprise a ring insulating layer in the upper region of the trench 6 or the nitrogen-containing layer 58 of the stack 54 may comprise other discontinuities. The layer of material, at which point the surface of the portion of the nitrogen-containing layer 58 is exposed and can be contacted with the phosphorus-containing oxide layer 62, and the portion of the nitrogen-containing layer 58 that contacts the layer containing the anthracene oxide layer 62 is removed. 15 shows a method for preparing a bottle-shaped deep trench 7 of the second embodiment of the present invention. The preparation method of the second embodiment of the present invention first forms a structure as shown in FIG. 6, and then forms a phosphorus-containing oxidation by a chemical vapor deposition process. Layer 72 is on the surface of the niobium containing layer 58, as shown in Figure η. The trench 60 is closed compared to the phosphorus-containing oxide layer 62 shown in FIG. 6, and the phosphorus-containing oxide layer 72 shown in FIG. 5 is thinner and does not close the opening of the trench 60. Referring to FIG. Forming a photoresist layer 74 on the surface of the phosphorus-containing oxide layer 72 by a spin coating process, and performing a dry etching process to remove the photoresist layer 74 above the predetermined depth 64, wherein the dry etching process etching gas contains oxygen, Carbon tetrafluoride and nitrogen. Thereafter, a wet etching process is performed using an oxide etching buffer (for example, buffered hydrofluoric acid or dilute hydrofluoric acid) to remove the phosphorus-containing oxide layer 72 above the predetermined depth 64, and then The sulfuric acid etch J liquid is subjected to another wet etching process to completely remove the photoresist layer 74 in the trench, as shown in FIG.

100110.DOC

1277176 αα ' places the semiconductor substrate 52 at a temperature limit of 700-1_. For about (1) hours, the (IV) oxide layer 72 will be converted into a etchant to remove the nitrogen-containing layer below the apparent depth of 64. After the completion of the residual reaction, the oxide (tetra) buffer is removed. A phosphorus-containing oxide layer 72 in the trench 60. Thereafter, a (10) etching process is performed to remove the oxidized stone layer 56 below the predetermined depth 64, which is used to dilute hydrofluoric acid or buffer hydrogen acid. And performing an additional etching process, φ which etches the inner wall of the trench 60 below the predetermined depth 64 using an etching solution containing an ammonia meter to form the bottle-shaped deep trench 70, as shown in FIG. Conventional techniques must transport etchant from the opening of the trench to the bottom to etch a nitrogen-containing layer at the bottom of the trench, such that the etch rate is limited by the size of the trench. In contrast, the present invention removes the nitrogen-containing layer in the trench by using a surname formed by the reaction of the phosphorus-containing oxide layer in the trench with the water strip gas, and transports the water vapor from the opening of the trench to the bottom and It is not limited by the size of the aperture of the trench. In other words, the present invention only needs to place the semiconductor substrate in a water vapor environment, and the phosphorus-containing oxide layer in the trench can be converted into a > 1 insect engraving which can describe the nitrogen-containing layer. Therefore, the present invention does not need to transport the etchant of the nitrogen-containing layer from the opening of the trench to the bottom of the trench, and thus can be applied to a high-accumulation dynamic random access memory having a trench having a small opening. The technical contents and technical features of the present invention have been disclosed as above, and those skilled in the art can still make various substitutions and modifications without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should not be limited to the disclosed embodiments, but should include various embodiments without departing from the invention.

100110.DOC 1277176 is replaced and modified and is covered by the scope of the following patent application. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 5 illustrate a conventional method for preparing a bottle-shaped deep trench on a substrate; FIGS. 6 to 10 illustrate a method for preparing a bottle-shaped deep trench according to a first embodiment of the present invention; And FIGS. 11 to 15 illustrate a method of preparing a bottle-shaped deep trench according to a second embodiment of the present invention. [Main component symbol description] 10 深 deep trench 12 $ 夕 substrate 20 trench 32 tantalum nitride layer 34 yttrium oxide layer 36 amorphous germanium layer 38 tantalum nitride layer 40 photoresist layer 42 predetermined depth 44 mask layer 50 bottle shape Deep trench 52 semiconductor substrate 54 stack structure 56 yttrium oxide layer 58 nitrogen-containing layer 60 trench 62 containing yttrium oxide layer 64 predetermined depth 72 containing oxide layer 74 photoresist layer 100110.DOC - 11 -

Claims (1)

1277176 X. Patent Application Range: 1. A method for preparing an ice trench, comprising the steps of: forming at least _, 善, 巨, 沟, in a semiconductor substrate; forming a stack® structure in the trench, the stacked structure And comprising at least one nitrogen-containing layer; the melon adult contains an oxide layer on the surface of the nitrogen-containing layer; and the outer oxide layer is converted into an etching solution to remove the nitrogen-containing layer in the stacked structure. 2 The method for preparing a deep trench of claim 1, wherein the forming of the containing layer 1 comprises removing an oxygen-containing layer having a predetermined depth or more within the trench. According to the preparation method of the deep trench of the present invention, the nitrogen-containing layer is a nitrile layer and the phosphorus-containing oxide layer is a boron phosphide glass layer. 4. The method of preparing a deep trench according to claim 1, wherein the nitrogen-containing layer is a layer of nitrogen oxynitride, and the layer of phosphorus-containing oxide is a layer of (four) glass. The method for preparing a deep trench according to claim 1, wherein the phosphorus-containing oxide layer is converted into a - (four) liquid system, and the semiconductor substrate is placed in a water vapor environment. The preparation method of the deep trench according to the item 5 The reaction temperature for converting the phosphorus-containing oxide layer into a residual solution is between 700 and 10 °C. 7. The method of preparing the deep trench of claim 2, wherein removing the phosphorus-containing oxide layer above the predetermined depth in the trench is performed by a dry etching process. 8. The method of preparing a deep trench according to claim 7, wherein the etching gas of the dry etching process comprises argon gas, oxygen gas, and octafluorocyclopentene. 9. The method of preparing a deep trench according to claim 2, wherein removing the oxide layer containing more than 100110.DOC 1277176 in the trench comprises the following steps: coating a photoresist layer on the surface of the phosphorus oxide layer Performing a dry engraving process to remove the photoresist layer above the predetermined depth; performing a wet etching process to remove the phosphorus-containing oxide layer above the predetermined depth; and removing the photoresist layer in the trench. 1 . The method of preparing a deep trench according to claim 9, wherein the gas of the dry etching process comprises oxygen, carbon tetrafluoride, and nitrogen. 11. The method of preparing a deep trench according to claim 9, wherein the wet etching process is performed by diluting hydrofluoric acid or buffering hydrofluoric acid. 12. The method of preparing a deep trench according to claim 9, wherein the layering process in the trench is removed, and the etching solution used comprises sulfuric acid. • According to the molybdenum claim 1, the deep trench formation layer forms a scaly oxidation utilization chemical vapor deposition process in the nitrogen-containing reed m. 14. The gas preparation method according to the deep trench of claim 2, which further includes the following Step: removing the stack structure below the service depth; and the internal recording process, the trench 15 is below the predetermined depth, and the method for preparing the deep trench is used, wherein the stack structure is further packaged with a thin one S: removing the stack structure below the predetermined depth so that the second: release... or buffering the hydrofluoric acid to carry out the wet residue. 16· The deep groove tear etchant according to the claim 14 contains ammonia water. The etch process 100110.DOC 8 -2-