Top Corner Rounding etching method based on non-special Rounding etching machine
Through the Top Corner Rounding etching method based on non-dedicated Rounding etching machines, high-temperature oxidation process and dry etching technology, the electric field concentration problem caused by sharp angles in traditional trench etching processes is solved, and efficient and low-cost rounding treatment is achieved, which improves the reliability and performance of the device.
Patent Information
- Application Number
- CN202411811019.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-10
- Publication Date
- 2025-04-11
AI Technical Summary
While forming trench, traditional trench etching processes often create sharp corners at the bottom and top of the trench, resulting in concentrated electric field, increased leakage current, and reduced breakdown voltage, affecting the electrical performance and reliability of the device. The existing Top Corner Round process is too expensive.
The Top Corner Rounding etching method based on a non-dedicated Rounding etching machine is used to form an oxide medium as a hard mask through a high-temperature oxidation process. The combination of dry etching and reactive ion etching technology is used to realize the rounding treatment of the trench corners.
It effectively reduces production costs, improves device reliability and performance, improves trench filling performance, and has process flexibility and applicability.
Smart Images
Figure CN119811995A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of semiconductor chip manufacturing technology, and in particular relates to a Top Corner Rounding etching method based on a non-dedicated Rounding etcher. Background Art
[0002] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a TopCorner Rounding etching method based on a non-dedicated Rounding etcher. Trench etching is a crucial link in the manufacturing process of semiconductor devices. The process mainly uses dry etching technology to accurately form trenches on semiconductor substrate silicon or other materials, providing the necessary structural basis for the subsequent device manufacturing.
[0003] However, the traditional trench etching process often produces sharp corners at the bottom and top of the trench while forming the trench. The existence of these sharp corners brings many negative effects. First, electric field concentration is prone to occur at the sharp corners, which makes it easier for carriers to tunnel at the corners, thereby increasing the leakage current and affecting the electrical performance of the device. Secondly, the strong electric field may also make the dielectric layer at the corner more susceptible to breakdown, thereby reducing the breakdown voltage of the device and limiting the application range of the device in high-voltage environments. In addition, long-term electric field concentration may also cause the device performance to gradually decline, or even cause device failure, seriously affecting the reliability and service life of the device.
[0004] In order to solve the above problems, the industry usually uses the Top Corner Round process to round the corners of the trench. Rounding can effectively reduce the electric field concentration and improve the reliability and performance of the device. At the same time, it can also improve the filling performance of the trench, reduce the formation of voids and defects, and facilitate the smooth production of subsequent devices.
[0005] However, the existing Top Corner Round process has the problem of high cost. The traditional Top Corner Round process is usually carried out before trench dry etching, and requires the use of a dedicated rounding etcher with lateral etching capabilities. This dedicated etcher is not only expensive, but also in practical applications, its cost-effectiveness is not ideal for process technologies with larger line widths (such as Trench MOS, TMBS, etc.). Therefore, how to reduce production costs while ensuring the effect of rounded corners has become a technical problem that needs to be solved urgently in the field of semiconductor manufacturing. Summary of the invention
[0006] The present invention aims to provide a Top Corner Rounding etching method based on a non-dedicated Rounding etcher to overcome the shortcomings of the prior art and meet the urgent demand for low-cost and high-efficiency rounding processing technology in the semiconductor manufacturing field.
[0007] In order to achieve the above object, the technical solution provided by the present invention is as follows.
[0008] A Top Corner Rounding etching method based on a non-dedicated Rounding etcher specifically comprises the following steps: Step 1: Provide a wafer substrate silicon for carrying subsequent device structures.
[0009] Step 2: grow a hard mask on the silicon substrate. As a masking layer for subsequent etching, the selection of the hard mask is crucial. The present invention preferably uses an oxide medium formed by a high temperature oxidation process as the hard mask, which has good etching selectivity and stability.
[0010] Step 3: Apply photoresist and complete the target groove photolithography pattern, including development and other processes. This step transfers the pattern of the target groove to the photoresist through photolithography technology to provide an accurate masking pattern for subsequent etching.
[0011] Step 4: Etch the hard mask layer. Use an appropriate etching process to transfer the pattern on the photoresist to the hard mask to form an etching pattern corresponding to the target trench.
[0012] Step 5: Remove the mask photoresist of the hard mask layer. After the hard mask etching is completed, the photoresist mask needs to be removed to facilitate the subsequent trench etching.
[0013] Step 6: Perform trench dry etching. Using dry etching technology, the substrate silicon is etched under the protection of the hard mask through the action of etching gas and plasma to form a target trench structure.
[0014] Step 7: Perform lateral etching of the hard mask. This step is one of the key points of the present invention. The hard mask is laterally etched by using a dry etching ISO process or a wet DHF (hydrogen difluoride) or BOE (buffered oxide etchant) etching method, and the etching amount is equal to the required fillet radius. DHF etching is preferred because its etching rate is slow and the etching amount of the hard mask can be stably controlled.
[0015] Step 8: Etching with a reactive ion etcher. This step uses the vertical etching characteristics of the reactive ion etcher (RIE) to vertically etch the top silicon corners to achieve a rounded corner effect. At the same time, since the reactive ion etcher has excellent vertical etching capabilities, it can ensure that there is no lateral etching on the sidewalls of the trench and will not damage the trench morphology. It is preferred to etch in a carbon tetrafluoride plus oxygen atmosphere to obtain the best etching effect.
[0016] Step 9: Remove the hard mask layer to obtain the target groove morphology with top rounded corners. After completing the rounded corner etching, the remaining hard mask layer needs to be removed to facilitate the subsequent device manufacturing process. At this point, the top rounded corner etching technology provided by the present invention is fully completed.
[0017] Compared with the prior art, the present invention has the following beneficial effects: Reduce production costs: Traditional methods usually use a dedicated corner fillet etcher with lateral etching to complete the top corner fillet processing, but these devices are expensive and too costly for processes with larger line widths such as Trench MOS, TMBS, etc. The present invention, by utilizing existing reactive ion etcher and appropriate etching technology, realizes the corner fillet processing of the groove without using a dedicated corner fillet etcher, thereby significantly reducing the production cost.
[0018] Improve device reliability and performance: In the semiconductor manufacturing process, the sharp corners produced by trench etching may lead to electric field concentration, increase leakage current, reduce the breakdown voltage of the device, and even cause device performance degradation and failure. By rounding the groove corners, the electric field concentration phenomenon can be effectively reduced, thereby improving the reliability and performance of the device. The technical solution of the present invention can accurately control the size and shape of the fillet, thereby ensuring the stability and reliability of the device.
[0019] Improved trench filling performance: The presence of top fillets can also improve the trench filling performance and reduce the formation of voids and defects. This is crucial for subsequent device manufacturing processes, as voids and defects may cause device performance degradation or even failure. Through the technical solution of the present invention, a trench structure with good filling performance can be obtained, providing a solid foundation for subsequent device manufacturing.
[0020] Process flexibility and applicability: The technical solution of the present invention is not only applicable to specific semiconductor materials and process steps, but also can adapt to different needs and conditions by adjusting etching parameters and process steps. This flexibility and applicability makes the present invention have a wide range of application prospects in the field of semiconductor manufacturing.
[0021] In summary, the top fillet etching method based on a non-dedicated fillet etcher provided by the present invention has significant beneficial effects, which can not only reduce production costs, improve device reliability and performance, but also improve trench filling performance and have process flexibility and applicability. These advantages make the present invention have wide application value and prospects in the field of semiconductor manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a schematic diagram of the structure after step 2 of the present invention is completed.
[0023] Figure 2 This is a schematic diagram of the structure after step 3 of the present invention is completed.
[0024] Figure 3 This is a schematic diagram of the structure after step 4 of the present invention is completed.
[0025] Figure 4 This is a schematic diagram of the structure after step 6 of the present invention is completed.
[0026] Figure 5 This is a schematic diagram of the structure after step 7 of the present invention is completed.
[0027] Figure 6 This is a schematic diagram of the structure after step 8 of the present invention is completed.
[0028] Figure 7 This is a schematic diagram of the structure after step 9 of the present invention is completed.
[0029] Figure 8 This is a process diagram of an embodiment of the present invention.
[0030] Fig. 9 This is a diagram showing the effect of top rounding in an embodiment of the present invention. DETAILED DESCRIPTION
[0031] The present invention will be further described in detail below in conjunction with specific examples, but the implementation methods of the present invention include but are not limited to the scope represented by the following examples. Example
[0032] Step 1: Provide a silicon wafer substrate. In order to facilitate SEM slicing, an 8-inch wafer with a crystal orientation of N (100) substrate is selected; Step 2: A layer of oxide dielectric film is grown on the substrate silicon using a high temperature oxidation process as a hard mask layer for trench etching; the SIO2 thickness is selected to be 6500A±500A, and the oxidation process conditions are: 1100℃ 5'O2+65'H2 / O2+5'O2 Step 3: Transfer the wafer to the photolithography for trench photolithography, and complete the trench coating, exposure, development and other processes. The PR (photoresist) selected is I-LINE, thickness 12000A, photolithography machine model Nikon i10; trench pattern CD0.5um.
[0033] Step 4: Switch to etching for hardmask etching, select the E-MAX model etcher from AMAT, with an etching thickness of 6500A, an OE amount of 10%, and siloss ≤ 300A; Figure 8 shown.
[0034] Step 5: Next, proceed to PR remove operation. First, dry strip using plasma 1000 model degumming machine, and then proceed to SPM operation (wet sulfuric acid degumming); Step 6: The next step is to perform trench dry etching; select NWC508C etcher, trench depth 2.2±0.2um, trench sidewall angle 89 degrees, hardmask remaining 3500±500A, Step 7: Perform lateral etching of the hardmask, and the etching amount is equal to the corner round radius. In this example, the etching amount is 300A; the lateral etching of the hardmask can be done by dry ISO etching or wet DHF, BOE etching. This paper tests the two methods of ISO and DHF etching. Considering the cost and etching amount stability, DHF etching is the preferred solution. Dry ISO etcher conditions: lam4520i-ISO chamber completed, recipe: RF 100W / pressure 500mt / NF3 100sccm / HE 150 sccm; DHF etching conditions: PNC B200C cleaning machine, 1:100DHF etching tank, etching time 600 seconds; etching amount 300A; Step 8: Use a dry etcher to perform top rounding etching. This example uses a lam4520 (8-inch) etcher, which is relatively old and commonly used in simple processes such as PSV etching. Etching recipe: pressure 1000mt / RF 200w / CF4:100sccm / O2:50sccm / time20sec. Fig. 9 This is the effect after top rounding. Corner rounding effect is produced in the red box.
[0035] Step 9: Finally, the wafer is transferred to the OXIDE remove process, and the BOE etching process is completed for 300 seconds. After removing the hardmask layer, the target trench morphology with top corner round is obtained; In summary, the top corner fillet etching method based on a non-dedicated corner fillet etcher provided by the present invention successfully realizes efficient and accurate corner fillet processing of trench corners in semiconductor manufacturing without using expensive dedicated corner fillet etching equipment through ingenious process design and precise etching control. This method not only significantly reduces production costs and improves production efficiency, but also effectively improves the reliability and performance of the device, which is specifically manifested in: Significant cost-effectiveness: It avoids the use of dedicated fillet etcher, significantly reduces equipment investment and maintenance costs, and provides strong support for cost control in the semiconductor manufacturing industry.
[0036] Device performance optimization: By precisely controlling the size and shape of the fillet, the problem of electric field concentration is effectively alleviated, the breakdown voltage and stability of the device are improved, and the service life of the device is extended.
[0037] Improved filling performance: The formation of top fillet is conducive to the uniform filling of subsequent materials, reducing the generation of voids and defects, and laying a solid foundation for high-quality device manufacturing.
[0038] Strong process flexibility: This technical solution has good adaptability and adjustability, and can be adjusted according to different materials and process requirements to meet diverse production needs.
[0039] Therefore, the top fillet etching method of the present invention not only brings an economical and efficient new technology approach to the semiconductor manufacturing industry, but also makes important contributions to improving device performance and reliability and promoting the continuous progress of semiconductor technology. The implementation of this technical solution is expected to have a wide and far-reaching impact in the semiconductor field.
Claims
1. A Top Corner Rounding etching method based on a non-dedicated Rounding etcher, characterized in that: The specific steps include: Step 1: providing a silicon wafer substrate; Step 2: growing a hard mask layer on the substrate silicon; Step 3: Apply photoresist and complete the target groove photolithography pattern; Step 4: Etch the hard mask layer to transfer the pattern on the photoresist to the hard mask to form an etching pattern corresponding to the target groove; Step 5: removing the mask photoresist of the hard mask layer; Step 6: performing trench dry etching; Step 7: Perform lateral etching of the hard mask, with the etching amount equal to the required fillet radius; Step 8: Etch the top silicon corners using a reactive ion etcher to achieve a rounded corner effect; Step 9: Remove the hard mask layer to obtain the target trench morphology with top rounded corners; the top rounded corner etching technology is completed.
2. The Top Corner Rounding etching method based on a non-dedicated Rounding etcher according to claim 1, characterized in that: In step 2, the hard mask is formed using an oxide dielectric using a high temperature oxidation process.
3. The Top Corner Rounding etching method based on a non-dedicated Rounding etcher according to claim 1, characterized in that: Step 3 also includes a development process.
4. The Top Corner Rounding etching method based on a non-dedicated Rounding etcher according to claim 1, characterized in that: In step 6, the substrate silicon is etched under the protection of the hard mask by the action of etching gas and plasma to form a target trench structure.
5. The Top Corner Rounding etching method based on a non-dedicated Rounding etcher according to claim 1, characterized in that: In step 7, a dry etching ISO process or a wet DHF or BOE etching process is adopted.
6. The Top Corner Rounding etching method based on a non-dedicated Rounding etcher according to claim 1, characterized in that: In step 8, vertical etching is performed using the vertical etching characteristics of a reactive ion etcher.
7. The Top Corner Rounding etching method based on a non-dedicated Rounding etcher according to claim 1, characterized in that: In step 8, etching is performed in a carbon tetrafluoride plus oxygen atmosphere.