TW460965B - Cleaning method and device for silicon substrate - Google Patents

Abstract

The present invention discloses a cleaning method for silicon substrate which includes the following steps: first, using deionized water for fast cleaning; then, conducting oxidant immersion to form a silicon oxide layer on the silicon substrate as a passivation for preventing the erosion on the surface of the silicon substrate by ammonia water in the subsequent processes; after conducting the SC-1 cleaning process, using the deionized water for fast cleaning; then, after conducting SC-2 cleaning process, again conducting fast cleaning; in which, the oxidant is hydrogen dioxide, ozone, or any other chemical which can oxidize the silicon substrate.

Description

460965 V. Description of the invention (1) Detailed description: Technical field:

In particular, the present invention relates to a method for cleaning a silicon substrate and a method and device for cleaning a silicon substrate. Background of the Invention: In order to pursue a faster operation rate and a larger integrated circuit, the research unit and the manufacturer's product [Brawl] 蒹 Those who have worked hard to design and manufacture components with smaller critical dimensions (CDs) and thinner silicon oxide layers. The cleanliness of Shi Xi substrates has been an important issue for semiconductor companies during the two or three decades of integrated circuit development. In particular, after the process of bulk circuit enters the field of deep sub-micron, with many technical challenges, the cleanliness of the silicon substrate has a very important impact on the yield of the process. 1 In semiconductor manufacturing processes, the main pollutants are particles, metals, organics, microroughness, and native oxide. The particles mainly come from the machine, the environment, deionized water, or chemicals, etc., which can easily cause the breakdown voltage of the silicon oxide layer to decrease, the polycrystalline silicon wire or the metal interconnects to bridge and short-circuit, etc .; metal pollution mainly comes from the machine Platform, environment, reactive ion etching (RI E), or chemicals, which can easily cause the breakdown voltage of the silicon oxide layer to decrease, interface leakage current to increase, initial voltage shift, etc .; organic matter usually comes from residues

460965 V. Description of the invention (2)-Photoresistance, storage container, or chemicals will cause bridging and short-circuiting of spar wires or metal interconnects, etc. " Changes to the 'recovered silicon substrate are available 'Part of the pickling solution will make it 1, micro: 2 is the original stone layer due to environmental moisture and deionized water, will reduce the uniformity of oxidative strength and film thickness, and increase the contact window's two: : All kinds of pollutants will greatly affect the yield of the process. Therefore, the use of a washing process to reduce the above-mentioned pollutants has become a problem reported by the semiconductor industry. Kwu

In the semiconductor manufacturing process, a cleaning step is usually performed to remove the above-mentioned contamination before the wafer is sent into a furnace tube for an oxidation process or a deposition process. The current cleaning process commonly used in the industry is called the RCA wet cleaning process, which was developed by Kern and Puotine η in the 1960s. It contains two consecutive steps' respectively called SC-1 (S.tandard C 1 eaning 1) and SC-2. Among them, the main formula of SC-1 is ammonia water-hydrogen peroxide-water, the ratio of which is between 1: 1: 5 to 1: 2: 7; 3 (:-2's main formula is hydrogen chloride-hydrogen peroxide-water, the proportion of which Between 1: 1: 6 to 1: 2: 8, the reaction temperature is between 70 ° C and 80 ° C. In a solution with a higher pH value, SC-1 can effectively remove organic matter and particles In a solution with a lower pp value, S C-2 can effectively remove metal contaminants. Next, we will explain the process of the conventional cleaning process with reference to FIG. 1, where FIG. 1 is used in the conventional technology to perform the cleaning process. Schematic diagram of the structure of the washing tank 'which contains a hydrofluoric acid tank (HF Tank) 12, a first water washing tank 13,

460965 V. Description of the invention (3) A SC-1 washing tank 14, a second water washing tank 15, a SC-2 washing tank 16, and a third water washing tank 17. After the cleaning process of the silicon substrate 11 is started, a hydrofluoric acid immersion (HF di p) is first performed in the hydrofluoric acid tank 12. Next, the first rapid washing operation was performed with deionized water in the first water washing tank 13 and then the SC-1 washing process was performed in the SC-1 washing tank 14. Next, a second rapid washing with deionized water is performed in a second water washing tank 15 and a SC-2 washing process is performed in a sc-2 washing tank 16. Finally, a third rapid washing with deionized water is performed in the third water washing tank 17 to complete the cleaning process of the silicon substrate 11. However, when the sc-i cleaning process is performed, 'the ammonia water vapor will corrode and damage the Shixi substrate', which will cause defects on the surface of the Shixi substrate. In addition to reducing the performance of the device, it will also make the process more Yield drops. Therefore, the development of a new cleaning process so that it will not erode the silicon substrate while cleaning the surface of the silicon substrate has become an important issue for integrated circuit industry. SUMMARY OF THE INVENTION The main object of the present invention is to provide a method for cleaning a silicon substrate. A secondary object of the present invention is to provide a cleaning method which does not attack the silicon substrate. _ Another object of the present invention is to provide a cleaning that does not erode the silicon substrate.

460965

V. Description of the Invention (4) Equipment. The invention discloses a method for cleaning a silicon substrate. The steps are as follows: first, deionized water is used for rapid washing ’followed by oxidizing agent soaking, A # ☆

A silicon oxide layer is formed on the r / J substrate as a protective layer. After the SC-1 washing process is performed, it is washed quickly with deionized water. Next, after the SC-2 cleaning process, a quick wash is performed again. The oxidant is hydrogen peroxide or ozone or any other chemical that can oxidize the silicon substrate. Preferably, the structural package of the cleaning tank used in the cleaning process of the present invention. R contains: a first water cleaning tank for rapid washing, and an oxidant tank '' for forming on the surface of the silicon substrate A silicon oxide layer, a SC-1 washing tank, a second water washing tank for fast washing, a SC-2 washing tank, and a third water washing tank for fast washing. Preferably, the structure of the washing tank used in the cleaning process of the present invention includes: a first water washing tank for fast washing, and includes at least one throttle valve connected to the pipeline for transmitting the oxidant, so that the oxidant can be borrowed Controlled by a throttle valve and transferred to the first water washing tank, an sc-i washing tank; a second water washing tank for fast washing, an SC-2 washing tank, and (a third water washing tank For fast washing.

460965 V. Description of the invention (5) 11-Hair base material 1 2-Acid tank for hydrofluoric acid 13-First water washing tank 14-SC-1 Cleaning tank 15-Second water washing tank 17-Third water washing tank 16-SC -2 Cleaning tank 3 1-Broken substrate 3 2- Hydrofluoric acid tank 33-First water tank 3 4-Oxidizer tank 35-SC-1 cleaning tank 3 6-Second water tank 37-SC-2 cleaning Tank 3 8-Third water washing tank 41-Second substrate 4 2-Hydrofluoric acid acid tank 43-First water washing tank 44-SC-1 Cleaning tank 4 5-Second water washing tank 47-Third water washing tank 46- SC-2 cleaning tank The present invention relates to a method for cleaning a silicon substrate, and more particularly to a method for cleaning a silicon substrate. The invention can be applied to the cleaning of various processes using silicon as a material, including semiconductor processes, thin film transistor-liquid crystal displays (TFT-LCD), and the like. Please refer to FIG. 2 for the process flow chart of the present invention. When the cleaning process is started 11, a hydrofluoric acid immersion (HF dip) 22 is performed first. After the first rapid washing with deionized water 2 3, a oxidant (ο X i d a n t) soak is performed for 2 4 13 and then the SC 1 cleaning process 25 is performed. Next, perform a second rapid wash 26 with deionized water, then perform a SC-2 cleaning process 27, and then perform a third rapid wash 2 8 to complete the silicon substrate.

Page 8 460965 V. Cleaning process of invention description (6) 29. The cleaning process of the embodiment is used in the first embodiment, which contains a monohydroxide-oxidant tank 34, a SC-2 cleaning tank 37, and after the process starts, it is first acid immersed, mainly used to remove Must, but in the formation of the gate oxidation tank 3 3 with deionized water

Next, the cleaning tank matched with the first of the present invention will be described with reference to FIG. 3, wherein FIG. 3 is a schematic structural diagram of the cleaning tank of the present invention for the cleaning process. The acid tank (HF Tank) 32 and a first water cleaning tank 33 SC-1 are cleaned. The tank 35, a second water washing tank 36, and a third water washing tank 38. When the silicon substrate 3 is cleaned, a hydrogen depletion is performed in an acid tank 32 of a hydrofluoric acid to remove the original silicon oxide layer. This step is not absolutely necessary before the silicon layer is particularly important. The second fast wash was performed in the first water wash.

The following is the key point of the present invention. The silicon substrate 3 is placed in the oxidant tank 34 and the reaction temperature is between 25 and 5 seconds. (: To 8 ° C to 5 ° C) to form a silicon oxide layer on the surface of the silicon substrate 31, the thickness of which is between 5 angstroms and 20 angstroms. The formed silicon oxide layer is used as a protection Layer 'to avoid subsequent erosion of the silicon substrate 3 丨 by the ammonia water vapor during the sc_ 丨 cleaning process. The oxidant tank 34 is filled with hydrogen peroxide plus deionized water or ozone plus deionized water. The surface of the substrate 3 is oxidized into a silicon dioxide layer. In addition, other chemicals having the ability to oxidize the silicon substrate can also be used. Then, the SC-1 cleaning process is performed in the SC-1 cleaning tank 35, Main

Page 9 46 096 5 V. Description of the invention σ) ^, the formula is ammonia water-hydrogen peroxide-water, the ratio is between +: 7, and the reaction temperature is between _. As previously mentioned, the surface of Shi Xi substrate 31 has a layer of oxidized oxide as a layer to protect it. ® In this step, ammonia water will not cause intrusion and damage to silicon substrate 31. Significantly improve the yield of the process. In the town > the second fast washing with deionized water in the water washing tank 36, and the SC_2 process in the SC-2 washing tank 37, its main formula is hydrogen chloride-hydrogen peroxide-water, the proportion of which is On the sign: mask n ^^^ i〇 ^^^ 70〇c ^ 80〇c ^; a'0 38 for the third rapid washing with deionized water ... into the substrate cleaning process. In the washing process and the example, the second water washing for hydrofluoric acid and the conventional thorium throttling, the second section is connected to the odorous oxidant, and the following is illustrated in Figure 4 to explain the matching of the second embodiment of the present invention. The cleaning tank, of which FIG. 4 is a structural schematic diagram of the cleaning tank for cleaning and moving according to the present invention, "^ 3 an acid tank 42, a t washing tank 43, a SC-1 cleaning tank 44, a tank 45, and a SC-2 cleaning The tank 46 and a third water washing tank 47. The difference is that the first water washing tank 43 of the present invention is further connected to three valves, wherein the third throttle valve 4 3 1 is connected to the pipeline flow valve 4 of deionized water 3 2 pipes connected with multiple hydrogen peroxide water '3 throttling valve 4 3 3 pipes. Of course, if more types of oxygen are needed in the process, more throttles and pipes can be added.

Page 10 460965 V. Description of the invention (8) After the cleaning process of the silicon substrate 41 is started, first a hydrofluoric acid immersion in a hydrofluoric acid bath 42 is used to remove the original oxidation second layer . The same 'this step is not absolutely necessary, but it is particularly important before the gate silicon oxide layer is formed. The following is the key point of the present invention. First, the first rapid washing with deionized water in the first water washing tank 4 3 is performed. Then, the throttle valves 4 3 1 and 4 3 2 are opened, and the deionized water and the hydrogen peroxide are sprayed at the same time. Spilled on the silicon substrate 4 丨, wherein the flow rate of deionized water is between 1 Osccm and 2 0 0 seem, and the flow rate of hydrogen peroxide water is between 1 Osccm and 2 0 0 seem. The spray spray lasted between 10 seconds and 300 seconds, and the reaction temperature was between 25 ° C. and 5 ° C., so as to form a layer of oxidized stone on the surface of the stone substrate 41, and its thickness Between 5 Angstroms and 20 Angstroms. The formed silicon oxide layer also functions as a protective layer to prevent the silicon substrate 41 from being attacked by ammonia water vapor during the subsequent SC-1 cleaning process. The effect can be achieved by opening the throttle valves 4 3 1 and 43 3, so that the deionized water and ozone are sprayed on the silicon substrate 41 at the same time, wherein the flow rate of the deionized water is between 10 sccm to 2 0 0 0 sccm. The ozone flow rate is between 10 sccm and 200 seem. The spraying lasts between 10 seconds and 300 seconds and the reaction temperature is between 25 ° C and 50 ° C. A silicon oxide layer is formed on the surface of the Shixi substrate 41, and its thickness is between 5 angstroms and 20 angstroms. In addition, the oxidant can also enter the water washing tank through the throttle valve through a transmission pipeline. The same effect can be achieved by adding water in the water washing tank. Next, the SC-1 cleaning process is performed in the SC-1 cleaning tank 44, which mainly

Page 11 4 6 096 5 V. Description of the invention (9) The formula is ammonia water-hydrogen peroxide-water, and the ratio is between the reaction temperature between 70 ° C and 80 ° C: 1: 5 to 1: 2: Between 7, As mentioned above, protection and damage can greatly improve the surface. Ϊ́ = layer as a protective layer. Because the ammonia water will not cause invasion of the silicon substrate 41 in the process, the yield rate of the silicon substrate 41 is next. The second rapid washing is performed, and the sc_2 washing process is performed in the sc_2 washing tank 46. Its main formula is hydrogen chloride-hydrogen peroxide-water, and its ratio is between 1: 丨: 6 to 丨: 2.8 and its f should be the temperature Between 70t and 8 叱. Finally, in the third water washing tank, a = < ion water for a third rapid washing to complete the scope of the present invention of the Shixi substrate 41, and the present invention will be described in detail with reference to the embodiments, but not limited to a slight Those skilled in the art of changing and tuning this technology can also understand that it is still appropriate to keep the essence of the invention without departing from the scope of the invention, as well as the scope and scope of the invention.

Page 12 460965 Simple description of 圊 style The drawings are explained in the following: Figure 1 is a schematic diagram of the structure of a cleaning tank used in the conventional technology to perform the cleaning process. FIG. 2 is a process flow chart of the cleaning process according to the present invention. FIG. 3 is a schematic structural diagram of a cleaning tank for performing a cleaning process in the first embodiment of the present invention. FIG. 4 is a schematic structural diagram of a cleaning tank used for a cleaning process in the second embodiment of the present invention.

Page 13

Claims (1)

460965 6. Scope of patent application Patent scope: 1. A method for cleaning Shi Xi substrates, including a SC-1 cleaning process; characterized in that before the SC-1 cleaning process, a oxidant is added to the stone Step of oxidizing the substrate. 2. The method for cleaning a silicon substrate according to item 1 of the scope of patent application, wherein the oxidant is hydrogen peroxide. 3. The method for cleaning a silicon substrate according to item 1 of the scope of patent application, wherein the oxidant is ozone. 4. The method for cleaning a silicon substrate according to item 1 of the scope of patent application, wherein the oxidant is located in an oxidant tank. 5. — A method for cleaning Shi Xi substrates, including a rapid washing process in a water washing tank and an SC-1 cleaning process; characterized in that between the rapid washing process and the SC-1 cleaning process, A step of oxidizing the Shixi substrate with an oxidant is added. 6. The method for cleaning a silicon substrate according to item 5 of the scope of the patent application, wherein the oxidant is hydrogen peroxide. 7. The method for cleaning a silicon substrate according to item 5 of the scope of patent application, wherein the oxidant is ozone. Page 14 460965 6. Scope of patent application 8. The method for cleaning the silicon substrate according to item 5 of the scope of patent application, wherein the oxidant is located in an oxidant tank. 9. The method for cleaning a silicon substrate according to item 5 of the scope of the patent application, wherein the oxidant is entered into the water washing tank through a throttle valve through a delivery pipe, and is added to the water in the water washing tank. 10. The method for cleaning a silicon substrate according to item 5 of the scope of the patent application, wherein the oxidant enters a water washing tank through a throttle valve through a conveying pipe, and after the rapid washing process is completed, the oxidant is washed. The oxidant is sprayed on the Shixi substrate. 11. A method for cleaning a silicon substrate, comprising the steps of: a. Rapid washing with deionized water; b. Immersing in an oxidant; and c. Performing an S C-1 cleaning process. 1 2. According to the method for cleaning the silicon substrate described in item 11 of the scope of the patent application, after the SC-1 cleaning process is performed, the method further includes the following steps: a. Rapid washing with deionized water; b. Performing SC- 2 washing process; c. Fast washing. Page 15 460965 6. Scope of patent application 1 3. The method for cleaning the silicon substrate according to item 11 of the scope of patent application, wherein the oxidant is hydrogen peroxide. 1 4. The method for cleaning a silicon substrate according to item 11 of the scope of patent application, wherein the oxidant is ozone. 15. The method for cleaning a silicon substrate according to item 11 of the scope of the patent application, wherein the oxidant is located in an oxidant tank. The description of the material base washed by the French party II Fan Li specially requested to apply for the cleaning of the silicon substrate described in Item 16 of the scope of the patent application. Wherein, the oxidant enters the water washing tank through a throttle valve through a delivery pipe, and is added to the water in the water washing tank. 1 8. The method for cleaning a silicon substrate according to item 16 of the scope of the patent application, wherein the oxidant enters the water washing tank through a throttle valve through a delivery pipe, and when the rapid washing process is completed After that, the oxidant is sprayed on the dream substrate. 1 9. A cleaning tank for cleaning the silicon substrate, the structure of which includes: a first water cleaning tank for rapid washing; Page 16 460965 VI. Patent application scope An oxidant tank is used to form a silicon oxide layer on the surface of the silicon substrate; a SC-1 cleaning tank; a second water cleaning tank is used for rapid washing; SC-2 washing tank; and a third water washing tank for fast washing. 2 0. A cleaning tank for cleaning the silicon substrate, the structure includes: a first water cleaning tank for fast washing, and includes at least one throttle valve connected to the pipeline for transmitting oxidant So that the oxidant can be transferred to the first water washing tank by the control of a throttle valve; a SC-1 cleaning tank; a second water washing tank for fast washing; a SC-2 cleaning tank; and A third water washing tank for fast washing. Page 17