Method for improving thickness uniformity of thin film

Abstract

The invention relates to the technical field of semiconductor manufacturing, and provides a method for improving the thickness uniformity of a film, which comprises the following steps of: S1, placing crystal boats loaded with wafers in a furnace tube according to a set arrangement sequence; s2, executing a deposition growth process of the thin film layer; s3, after the deposition growth process is completed, detecting whether the first inter-wafer thickness uniformity of all wafers is smaller than an inter-wafer thickness uniformity threshold value or not; if the thickness is smaller than the inter-sheet thickness uniformity threshold value, the process is ended; if the thickness is not smaller than the inter-sheet thickness uniformity threshold value, continuing to execute; and S4, the arrangement sequence of the crystal boats is adjusted, the crystal boats are placed in the furnace tube again, and the step S2 is executed. According to the configuration, when each deposition growth process is carried out, the arrangement positions of the wafers in the furnace body are subjected to sequence adjustment, so that the uniformity of the inter-wafer thickness of each wafer can be unified, the in-wafer thickness uniformity of the deposition process can be improved, and the process stability and yield of the device can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a method for improving the uniformity of film thickness. Background Art

[0002] Thin film deposition is an important part of semiconductor manufacturing technology. Through appropriate variable control, a thin film layer (such as an oxide layer) is formed on a semiconductor device, and the thin film layer has high quality, stable and expected dielectric properties. Due to these properties, the thin film layer is crucial. For example, for the gate structure in the MOS (oxide) process, the thin film layer can be used as a dielectric material, such as an isolation device, an implanted oxide shield, a stress relief oxide (pad oxide), and a nitride and polysilicon surface reoxidation for photoresist adhesion and stress release.

[0003] The deposition and growth of thin film layers require furnace tubes. Existing furnace tubes are usually vertical structures. A batch of wafers are arranged in the furnace tube along the vertical direction of the furnace tube. The heating device heats the furnace tube, and the reaction gas is introduced from the top or bottom to form a thin film layer on the surface of the wafer. Since the temperature field and gas concentration field formed in the furnace tube change with the height of the furnace body, the uniformity of the thin film layer of a batch of wafers after production eventually changes with the furnace height gauge, which results in poor thickness uniformity of the thin film layer of a batch of wafers.

[0004] For the improvement of thickness uniformity, the existing technology focuses on improving the furnace structure, which is inevitably limited by technology or hardware. In addition, when the thickness uniformity of the thin film layer of most wafers in the furnace meets the requirements, the cost of improving the entire furnace to meet the uniformity parameters of a small number of wafers is not negligible, and there is a phenomenon of performance overflow.

[0005] To this end, the present invention provides a method for improving the uniformity of film thickness, which improves the uniformity of thickness between sheets without changing the furnace structure. Summary of the invention

[0006] The object of the present invention is to provide a method for improving the uniformity of film thickness, so as to improve the uniformity of the film thickness of a wafer without changing the furnace structure.

[0007] The present invention provides a method for improving the uniformity of film thickness, comprising the following steps:

[0008] S1: placing the wafer boats carrying the wafers in the furnace tube according to the set arrangement order;

[0009] S2: performing a deposition growth process of a thin film layer;

[0010] S3: After the deposition growth process is completed, detect whether the first inter-wafer thickness uniformity of all wafers is less than the inter-wafer thickness uniformity threshold; if it is less than the inter-wafer thickness uniformity threshold, end the process; if it is not less than the inter-wafer thickness uniformity threshold, continue to execute;

[0011] S4: adjusting the arrangement order of each of the wafer boats, and re-placing each of the wafer boats in the furnace tube according to the adjusted arrangement order, and executing step S2.

[0012] Optionally, in the step S4, before re-placing each wafer boat in the furnace tube according to the adjusted arrangement sequence, the step further includes: adjusting the arrangement sequence of each wafer in each wafer boat.

[0013] Optionally, the arrangement order of the wafers in the wafer boat is adjusted by the following steps:

[0014] The wafers are rearranged in the reverse order of their existing sequence.

[0015] Optionally, the adjusting the arrangement sequence of each wafer boat includes a first sequence adjustment method and a second sequence adjustment method;

[0016] In the first sequencing method, the adjustment is performed based on the second inter-wafer thickness uniformity of the wafers in each wafer boat;

[0017] In the second sequencing method, the positions of at least a portion of the wafer boats are designated to remain unchanged.

[0018] Optionally, the first sequencing method includes:

[0019] Step S4-1: calculating the second inter-wafer thickness uniformity of the wafers in each wafer boat, and arranging the wafer boats in the order of the second inter-wafer thickness uniformity, in the order of U1, U2...Un, where Un is the second inter-wafer thickness uniformity of the wafer boat, and n is the number of wafer boats;

[0020] Step S4-2: Replace the order of the wafer boats corresponding to the second wafer-to-wafer thickness uniformity of Ux and Un+1-x, where x is a positive integer less than or equal to n.

[0021] Optionally, the second sequencing method includes:

[0022] Step S4-1': Calculate the second inter-wafer thickness uniformity of the wafers in each wafer boat, the wafer boat positions corresponding to the smallest m second inter-wafer thickness uniformities remain unchanged in each deposition growth process, and the remaining wafer boats are arranged in the order of the size of the second inter-wafer thickness uniformity, and the arrangement order is Um+1, Um+2...Un, Un is the second inter-wafer thickness uniformity of the wafer boat, and n is the number of wafer boats;

[0023] Step S4-2': replace the order of the wafer boats corresponding to the second inter-wafer thickness uniformity of Um+y and Un+1-y, where y is a positive integer less than or equal to nm.

[0024] Optionally, before adjusting the arrangement order of each wafer boat, the method further includes the following steps:

[0025] A sequencing method is determined between the first sequencing method and the second sequencing method to adjust the arrangement order of the wafer boats.

[0026] Optionally, before the wafer boats are re-placed in the furnace tube according to the adjusted arrangement order in step S4, the following steps are further included:

[0027] Calculate the intra-wafer thickness uniformity of each wafer in the two wafer boats that are replaced with each other, and sort all the wafers in the two wafer boats in the order of the same intra-wafer thickness uniformity. If the arrangement order of the wafers in the two wafer boats is not opposite, rearrange the wafers in the two wafer boats in the reverse order of the existing order.

[0028] Optionally, before executing step S2 in step S4, the following steps are further included:

[0029] The number of deposition growth processes executed is calculated; if the number of deposition growth processes is equal to a process number threshold, the process is terminated; if the number of deposition growth processes is less than the process number threshold, the process is continued.

[0030] Optionally, the process number threshold is less than or equal to 3.

[0031] In summary, the present invention provides a method for improving the uniformity of thin film thickness, comprising the following steps: S1: placing each wafer boat carrying wafers in a furnace tube according to a set arrangement order; S2: executing a deposition growth process of a thin film layer; S3: after the deposition growth process is completed, detecting whether the first inter-wafer thickness uniformity of all wafers is less than an inter-wafer thickness uniformity threshold; if it is less than the inter-wafer thickness uniformity threshold, terminating the process; if it is not less than the inter-wafer thickness uniformity threshold, continuing to execute; S4: adjusting the arrangement order of each wafer boat, re-placing each wafer boat in the furnace tube according to the adjusted arrangement order, and executing step S2.

[0032] With such configuration, when performing each deposition growth process, by adjusting the placement position of the wafer boat in the furnace, and then adjusting the placement order of the wafers, it is helpful to unify the thickness uniformity between each wafer, and it is also helpful to improve the thickness uniformity within the wafer of the deposition process, and improve the device process stability and yield. Compared with the existing method of improving thickness uniformity through technological innovation or hardware upgrade, the improvement method of the present invention does not need to rely on hardware upgrade to achieve improvement of uniformity, which helps to reduce the improvement cost when improving uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of an existing furnace tube;

[0034] Figure 2 It is a schematic diagram of the sequencing structure of the present invention;

[0035] Figure 3 The present invention is a flow chart of sequencing;

[0036] Figure 4 It is a comparison diagram of the uniformity parameter curve fitting between the sequence adjustment and the non-sequence adjustment;

[0037] Figure 5 A comparison diagram of uniformity parameters between the sequence adjustment and the non-sequence adjustment in Example 1;

[0038] Figure 6 A comparison diagram of uniformity parameters between the sequence adjustment and the non-sequence adjustment in Example 2;

[0039] Figure 7 This is a comparison chart of uniformity parameters with and without sequence adjustment in Example 3.

[0040] Among them, in the attached drawings:

[0041] 100-furnace tube; 200-heating device;

[0042] 10- First crystal boat;

[0043] 20- Second crystal boat;

[0044] 30- The third crystal boat;

[0045] 40-The fourth crystal boat. DETAILED DESCRIPTION

[0046] The method for improving the uniformity of film thickness proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0047] As used in the present invention, the singular forms "one", "an" and "the" include plural objects, the term "or" is usually used to include the meaning of "and / or", the term "several" is usually used to include the meaning of "at least one", and the terms "at least two" or "multiple" are usually used to include the meaning of "two or more". In addition, the terms "first", "second" and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" and "third" can explicitly or implicitly include one or at least two of the features. In addition, as used in the present invention, "installed", "connected", "connected", and one element "set" on another element should be understood in a broad sense, usually only indicating that there is a connection, coupling, matching or transmission relationship between the two elements, and the connection, coupling, matching or transmission between the two elements can be direct or indirect through an intermediate element, and cannot be understood as indicating or implying the spatial position relationship between the two elements, that is, one element can be in any orientation such as inside, outside, above, below or on one side of another element, unless the content clearly indicates otherwise. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, directional terms such as above, below, up, down, upward, downward, left, right, etc. are used with respect to the exemplary embodiments as they are shown in the figures, with the upward or upper direction toward the top of the corresponding figure, and the downward or lower direction toward the bottom of the corresponding figure.

[0048] Combination Figure 1 As shown, the existing furnace tube 100 is usually a vertical structure, the interior of the furnace tube 100 is a cylindrical structure, and the axial direction of the furnace tube 100 extends vertically. A batch of wafers are arranged in the furnace tube along the vertical direction of the furnace tube, and the wafer boats of the batch are placed in multiple wafer boats respectively. Figure 1 As shown, in this embodiment, a batch of wafers are placed in four wafer boats, namely the first wafer boat 10, the second wafer boat 20, the third wafer boat 30 and the fourth wafer boat 40. Each wafer boat can store multiple wafers. The four wafer boats carry the wafers and are placed in the furnace tube 100 in sequence in the vertical direction, so that the wafers of this batch are arranged in the furnace tube 100 in the vertical direction. A heating device 200 is arranged on the periphery of the furnace tube 100. The heating device 200 is used to heat the furnace tube 100. The reaction gas is introduced into the top of the furnace tube 100 to form a thin film layer on the surface of the wafer.

[0049] Since the temperature field and gas concentration field formed in the furnace tube vary with the height of the furnace body, the uniformity of the thin film layer of a batch of wafers after production will eventually vary with the furnace height gauge, that is, the thickness uniformity of the wafers in each wafer boat is different, and the thickness uniformity of each wafer in the same wafer boat is also different.

[0050] Please refer to Figure 2 and Figure 3 As shown, this embodiment provides a method for improving the uniformity of film thickness, comprising the following steps:

[0051] S1: placing the wafer boats carrying the wafers in the furnace tube according to the set arrangement order;

[0052] S2: performing a deposition growth process of a thin film layer;

[0053] S3: After the deposition growth process is completed, check whether the first inter-wafer thickness uniformity of all wafers is less than the inter-wafer thickness uniformity threshold; inter-wafer thickness uniformity is to calculate the thickness uniformity of the thin film for multiple wafers, and inter-wafer thickness uniformity is used to calibrate the difference in film thickness between each wafer. The first inter-wafer thickness uniformity here is the data calculated based on all wafers in the furnace tube (the second inter-wafer thickness uniformity in the following is the data calculated based on the wafers in a single wafer boat), and the inter-wafer thickness uniformity threshold here can be manually set based on process requirements.

[0054] If the first inter-sheet thickness uniformity is less than the inter-sheet thickness uniformity threshold, the thickness uniformity of the thin film layer meets the process requirements, and the process can be terminated at this time; if the first inter-sheet thickness uniformity is not less than the inter-sheet thickness uniformity threshold, the thickness uniformity of the thin film layer does not meet the process requirements, and the method is continued;

[0055] S4: Adjust the arrangement order of each wafer boat in the furnace tube, adjust the arrangement order of each wafer in the wafer boat, specifically, rearrange each wafer in the wafer boat in the reverse order of the existing order. Re-place each wafer boat in the furnace tube according to the adjusted arrangement order, and execute step S2 (i.e., execute the next deposition growth process).

[0056] When performing each deposition growth process, by adjusting the placement position of the wafer boat in the furnace, and then adjusting the placement order of the wafers, it is helpful to unify the thickness uniformity between each wafer, and it is also helpful to improve the thickness uniformity within the wafer of the deposition process, and improve the device process stability and yield. Compared with the existing method of improving thickness uniformity through technological innovation or hardware upgrade, the improvement method of the present invention does not need to rely on hardware upgrade to achieve improvement of uniformity, which helps to reduce the improvement cost when improving uniformity.

[0057] In order to clearly illustrate the above method steps, in this embodiment Figure 2 As an example to further illustrate.

[0058] Figure 2In the embodiment, there are four wafer boats in the furnace tube 100, namely, a first wafer boat 10, a second wafer boat 20, a third wafer boat 30 and a fourth wafer boat 40. Twenty-five wafers are placed in each wafer boat, and each wafer in each wafer boat is numbered in the order of 1-25 from bottom to bottom.

[0059] Figure 2 When the first deposition growth process is performed, the order of the wafer boats from top to bottom in the furnace tube 100 is the first wafer boat 10 , the second wafer boat 20 , the third wafer boat 30 and the fourth wafer boat 40 .

[0060] After the first deposition growth process is performed, the order of the first wafer boat 10 and the second wafer boat 20 and the order of the wafers in the two wafer boats are adjusted.

[0061] The order of the wafers in the first wafer boat 10 is adjusted from 101-125 to 125-101 from bottom to top, so that the wafers are rearranged in reverse order of the initial order. Similarly, the order of the wafers in the second wafer boat 20 is adjusted from 201-225 to 225-201 from bottom to top, so that the wafers are rearranged in reverse order of the initial order. Then the positions of the first wafer boat 10 and the second wafer boat 20 are swapped, and all the wafer boats are re-placed in the furnace tube 100 according to the adjusted order to perform the second deposition growth process. At this time, the order of the wafer boats in the furnace tube 100 from top to bottom is the second wafer boat 20, the first wafer boat 10, the third wafer boat 30 and the fourth wafer boat 40.

[0062] Figure 2 In other alternative embodiments, the specific order adjustment method of the wafer boats can be flexibly adjusted based on the actual calculated data of the thickness uniformity between the first wafers, for example, the four wafer boats can be arranged in reverse order to perform the next deposition growth process.

[0063] Figure 2 In the process of performing the sequencing, the order of the wafers in the wafer boat is firstly adjusted, and then the order of the wafer boats is adjusted. In other alternative embodiments, the order of the wafer boats may be adjusted first, and then the order of the wafers in the wafer boats may be adjusted, and the sequencing priority of the wafer boats and the wafers may be determined based on the actual process operation.

[0064] In the above embodiment, the uniformity of thin film generation is improved by adjusting the order of the wafer boats and the wafers in each wafer boat. In other alternative embodiments, only the order of the wafer boats may be adjusted to improve the uniformity of thin film generation. Specifically, whether to adjust the order of the wafers in the wafer boat may be selected based on the uniformity of the specific thin film after each deposition growth process.

[0065] Please refer to Figure 3As shown, before executing step S1, the wafer boat that needs to be sequenced can also be marked. This mark is used to distinguish the wafer boat that does not need to be sequenced, for the case of incomplete sequencing. When there is no need to improve the uniformity of the wafers, there is no need to sequence the wafer boat. This operation can be manually specified in advance. When a wafer boat that does not need to be sequenced is identified, the wafer boat will skip the sequencing step and wait for the remaining wafer boats to complete the sequencing before the nth process preparation.

[0066] In this embodiment, when step S2 is executed, it is also possible to identify whether there is a wafer boat that needs to be sequenced based on the actually calculated uniformity parameters. If there is no need to sequence the wafer boat and wafers due to some special needs, the above-mentioned sequencing step can be skipped to execute or prepare for the next deposition growth process.

[0067] In this embodiment, the number of sequence adjustments is at least 1 and at most n, and n is preferably not greater than 2, so that the process number threshold is less than or equal to 3 to ensure that the wafer uniformity requirements are met in a fewer number of deposition growth processes.

[0068] In this embodiment, there are two sequencing strategies, namely, a first sequencing method and a second sequencing method;

[0069] The first sequencing method is adjusted based on the second inter-wafer thickness uniformity of the wafers in each wafer boat;

[0070] In the second sequencing method, the position of at least a portion of the wafer boat is specified to remain unchanged in each deposition growth process, so that the wafers in the wafer boat with unchanged position meet special uniformity requirements.

[0071] Therefore, before adjusting the order of the wafer boats, a sequencing method needs to be determined. Specifically, a sequencing method is determined between the first sequencing method and the second sequencing method to adjust the arrangement order of the wafer boats. After the wafer boats that need to be sequenced are identified, the determined sequencing method is identified, and the sequencing of the wafer boats is performed by the machine according to the method.

[0072] In this embodiment, the first sequencing method is used as automatic sequencing, and the second sequencing method is used as designated sequencing. After marking the wafer boat that needs sequencing, the sequencing times and the sequencing method are marked. The sequencing method can be determined as automatic sequencing (determining the specific sequencing method through the actual uniformity parameters after the deposition growth process) and designated sequencing (a sequencing method that specifies a part of the wafer boat position remains unchanged). Designated sequencing is a sequencing method set to meet special needs, and automatic sequencing is used to distinguish sequencing set for special needs. When there is a high demand for improvement in wafer uniformity, the best furnace position needs to be specified for the wafer. At this time, designated sequencing is used to make the specified wafer in the best position. When it is identified that wafer boat sequencing is required, it is prioritized to identify whether the required sequencing method is the first sequencing method or the second sequencing method, and then the sequencing strategy is executed based on the corresponding sequencing method.

[0073] In this embodiment, the first sequencing method is used as automatic sequencing. Specifically, the arrangement order of each wafer boat is adjusted in the first sequencing method including:

[0074] Step S4-1: Calculate the second inter-wafer thickness uniformity of the wafers in each wafer boat. The second inter-wafer thickness uniformity is the data calculated based on the wafers in a single wafer boat. Each wafer boat can calculate a corresponding second inter-wafer thickness uniformity. The wafer boats are arranged in the order of the second inter-wafer thickness uniformity (from large to small or from small to large), and the arrangement order is U1, U2...Un, Un is the second inter-wafer thickness uniformity of the wafer boat, and n is the number of wafer boats;

[0075] Step S4-2: Replace the order of the wafer boats corresponding to the second wafer-to-wafer thickness uniformity of Ux and Un+1-x, where x is a positive integer less than or equal to n. The order adjustment method is to replace the positions of the wafer boats with the largest and smallest second wafer-to-wafer thickness uniformity, replace the positions of the wafer boats with the second largest and second smallest second wafer-to-wafer thickness uniformity, and so on. In this way, in the second process, the positions of the wafer boats with the best and worst uniformity are complementary before and after the order adjustment, so that the final wafer-to-wafer thickness uniformity after the wafer process is completed can be converged and improved.

[0076] In this embodiment, the second sequencing method is used as the designated sequencing method. Specifically, the arrangement order of each wafer boat is adjusted in the second sequencing method including:

[0077] Step S4-1': Calculate the second-wafer-to-wafer thickness uniformity of the wafers in each wafer boat. The positions of the wafer boats corresponding to the smallest m second-wafer-to-wafer thickness uniformities remain unchanged in each deposition growth process, where m is a positive integer less than n, for example, m is 1 or 2. The second-wafer thickness uniformity corresponding to the several wafer boats that remain unchanged is the best, and this position is assumed to be the best. The above-mentioned wafer boat positions remain unchanged in each subsequent deposition growth process to meet special needs. The remaining wafer boats are arranged in the order of the size of the second-wafer thickness uniformity (from large to small or from small to large), and the arrangement order is Um+1, Um+2...Un, Un is the second-wafer thickness uniformity of the wafer boat, and n is the number of wafer boats;

[0078] Step S4-2': Replace the order of the wafer boats corresponding to the second wafer-to-wafer thickness uniformity of Um+y and Un+1-y, where y is a positive integer less than or equal to nm. The order adjustment method is to replace the remaining wafer boats according to the positions of the wafer boats with the largest and smallest second wafer-to-wafer thickness uniformity, replace the positions of the wafer boats with the second largest and second smallest second wafer-to-wafer thickness uniformity, and so on. In this way, in the second process, the positions of the remaining wafer boats with the best and worst uniformity are complementary before and after the order adjustment, so that the final wafer-to-wafer thickness uniformity completed by the wafer process can be converged and improved.

[0079] After the corresponding adjustment method is determined and the wafer boats are reordered through the above steps, the positions of the wafer boats can be adjusted by the machine work instructions.

[0080] In addition, before the wafer boats are re-placed in the furnace tube according to the adjusted arrangement order in the above step S4, the following steps are also included:

[0081] Calculate the intra-wafer thickness uniformity of each wafer in the two wafer boats that are replaced with each other, and sort all the wafers in the two wafer boats in the order of the same intra-wafer thickness uniformity. If the arrangement order of the wafers in the two wafer boats is not opposite, rearrange the wafers in the two wafer boats in the reverse order of the existing order.

[0082] Intra-wafer thickness uniformity is the thickness uniformity of a thin film calculated for a single wafer. This indicator is used to indicate the difference in film thickness at various locations on the wafer.

[0083] by Figure 2 Take the wafers in the first wafer boat 10 and the second wafer boat 20 as an example. If the wafers in the first wafer boat 10 are sorted from small to large according to the thickness uniformity within the wafer, they are 101, 102, ... 125, then the wafers in the second wafer boat 20 are sorted from small to large according to the thickness uniformity within the wafer. If the sorting is the same as that of the first wafer boat 10, the wafers are sorted as 201, 202, ... 215. That is, the thickness uniformity of each wafer in the first wafer boat 10 and the second wafer boat 20 increases from top to bottom. When the order is the same, if the position of the wafer is not adjusted at this time, after the positions of the first wafer boat 10 and the second wafer boat 20 are exchanged, wafer 101 is located at the position of wafer 201. Similarly, wafer 125 is located at the position of wafer 205. That is, the positions with the best and worst uniformity in the two wafer boats remain unchanged before and after the adjustment. Therefore, if the wafer positions are not replaced, the thickness uniformity between the wafers in the wafer boat will become more dispersed.

[0084] Ideally, the wafers are sorted according to the uniformity of thickness within the wafer. Only when the arrangement order of the wafers in the two wafer boats is completely opposite, a complete complementary relationship can be formed without adjusting the wafer order.

[0085] In the actual process, the thickness uniformity of each wafer is greatly affected by the temperature field and the gas concentration field. Therefore, the arrangement order of each wafer in the two wafer boats is actually very uncertain when the wafers are sorted according to the thickness uniformity of the wafer. Therefore, the strategy adopted in the present invention is to rearrange the wafers in the reverse order of the existing order when the arrangement order of each wafer in the two wafer boats is not opposite. After actual verification, this order adjustment method will form a complementary effect between the worse position and the better position, so that the thickness uniformity between wafers can be converged.

[0086] In the above wafer sequencing, the wafers are directly arranged in reverse order according to the existing order. The wafer conveyor of the machine takes out the wafers at one time, flips them 180 degrees and reloads them into the wafer boat to achieve reverse order. The actual operation is relatively simple and is conducive to improving process efficiency. At the same time, the above wafer sequencing method also simplifies the process sequencing process.

[0087] Before executing step S2 in step S4, the following steps are also included:

[0088] Calculate the number of deposition growth processes executed; if the number of deposition growth processes is equal to the process number threshold, end the process; if the number of deposition growth processes is less than the process number threshold, continue to execute. The process number threshold is not greater than 3, preferably equal to 2, at which time at most two deposition growth processes are performed, and one sequencing is performed. This step is preferably located before step S4, that is, determining whether to end the process before executing the sequencing strategy, for example, this step is located between step S2 and step S3, or between step S3 and step S4.

[0089] By calculating the thickness uniformity between the first slices and the number of processes, the abnormality of the process can be monitored in real time. For example, when the number of deposition growth processes is equal to the process number threshold, the thickness uniformity between the first slices still does not meet the requirements, then the entire process is considered abnormal, and it needs to be shut down for inspection or maintenance.

[0090] In order to fully illustrate the above-mentioned wafer sequencing effect of the present invention, a mathematical model is introduced for explanation. At the same time, the actual effect can also be predicted based on the model.

[0091] In a mature process technology, the average thickness at different heights in the furnace body is the same, so the heights at different positions are all Ta. The present invention takes 100 positions of a wafer as an example.

[0092] Combined with Table 1 to Table 3, where:

[0093] U is the thickness uniformity between wafers, U = (Tmax-Tmin) / (2*Ta), Tmax is the maximum film thickness in each wafer, Tmin is the minimum film thickness in each wafer, and Ta is the average thickness; when the calculation object is all the wafers in each wafer boat, the obtained U value is the first thickness uniformity between wafers; when the calculation object is the wafers carried in a wafer boat, the obtained U value is the second thickness uniformity between wafers;

[0094] U1 is the thickness uniformity between sheets after the first process;

[0095] U2 is the thickness uniformity between sheets after the second process without sequence adjustment;

[0096] U2R is the thickness uniformity between sheets after the second process of sequencing;

[0097] R is the in - wafer thickness uniformity, R = THKmax–THKmin, where THKmax is the maximum local film thickness of the wafer and THKmin is the minimum local film thickness of the wafer.

[0098] Since the film thickness parameters of the wafers in the furnace body usually show an asymmetric U - shaped distribution, so R i≠R(101 - i);

[0099] If R i corresponding to wafer #i is the maximum value, then:

[0100] U2R = (R i+R(101 - i)) / 2Ta / 2 < Ri / Ta / 2 = U2max

[0101] If R i corresponding to wafer #i is the minimum value, then:

[0102] U2R = (R i+R(101 - i)) / 2Ta / 2 > Ri / Ta / 2 = U2min

[0103] Therefore, U2min < U2R < U2max must hold, that is, the inter - wafer thickness uniformity after re - ordering is more convergent. At the same time, the wafers with excessive uniformity are improved (U2R < U2max);

[0104] U2 is part of the data without re - ordering in the second process. Through data fitting, the mathematical formula of U at different heights of the entire furnace body is obtained:

[0105] U2R = (U2+U2(101 - i)) / 2 = 0.0005i^2 - 0.0505i + 3.5154;

[0106] where i is the position number at different heights of the furnace body;

[0107] Table 1 First - process parameters

[0108]

[0109]

[0110] Table 2 Second - process parameters without re - ordering

[0111] Wafer number Wafer location Mean thickness Thickness uniformity within the sheet U2 #01 100 2Ta 2R1 R1 / Ta / 2 #02 99 2Ta 2R2 R2 / Ta / 2 #03 98 2Ta 2R3 R3 / Ta / 2 #04 97 2Ta 2R4 R4 / Ta / 2 …… …… 2Ta …… …… #i 100-i 2Ta 2Day Ri / Ta / 2 …… …… 2Ta …… …… #100 1 2Ta R100 R100 / Ta / 2

[0112] Table 3 Second - process parameters after re - ordering

[0113]

[0114] Combined with Table 4 and Figure 3As shown in Figure 1, the theoretical U parameter of the second process sequence adjustment is predicted based on the sequence adjustment model. It can also be clearly seen from the predicted curve that the uniformity of U2R is more convergent and the maximum value is significantly suppressed.

[0115] Table 4 Comparison of parameters between the second process without sequence adjustment and with sequence adjustment

[0116]

[0117]

[0118] The present invention further illustrates the technical effect of improving the thickness uniformity between sheets through the following three embodiments.

[0119] Embodiment 1:

[0120] The first embodiment corresponds to two deposition growth processes and one complete sequence adjustment.

[0121] This embodiment adjusts the placement positions of the wafers in the furnace body to unify the thickness uniformity between each wafer, thereby improving the thickness uniformity between wafers.

[0122] In the sequencing method used in this embodiment, all wafer boats are arranged in reverse order, and all wafers in each wafer boat are arranged in reverse order.

[0123] The parameters after the first deposition growth process are shown in Table 5.

[0124] The parameters after the second deposition growth process without sequence adjustment are shown in Table 6.

[0125] The parameters of the second deposition growth process after the sequence adjustment are shown in Table 7.

[0126] Table 5 First process parameters

[0127]

[0128]

[0129] Table 6 Parameters of the second process without sequence adjustment

[0130] Wafer number Wafer location Mean thickness Thickness uniformity within the sheet U2 #01 100 600.0 13 1.08 #05 96 600.0 12.4 1.03 #10 91 600.0 11.6 0.97 #15 86 600.0 9.6 0.80 #20 81 600.0 9.2 0.77 #25 76 600.0 9 0.75 #30 71 600.0 8.4 0.70 #35 66 600.0 8.8 0.73 #40 61 600.0 8.2 0.68 #45 56 600.0 8 0.67 #50 51 600.0 7.6 0.63 #55 46 600.0 7.8 0.65 #60 41 600.0 7.2 0.60 #65 36 600.0 6.4 0.53 #70 31 600.0 6 0.50 #75 26 600.0 5.8 0.48 #80 21 600.0 6.2 0.52 #85 16 600.0 7.2 0.60 #90 11 600.0 7 0.58 #95 6 600.0 8.4 0.70 #100 1 600.0 9 0.75

[0131] Table 7 Second process adjustment parameters

[0132]

[0133]

[0134] Depend on Figure 6 and Figure 7 By comparison, Figure 7The maximum difference in thickness uniformity between sheets after the adjustment is 0.32. Figure 6 The maximum thickness uniformity difference between the unadjusted slices is 0.60. Figure 5 As shown in the figure, the thickness uniformity distribution between sheets after the adjustment is more convergent.

[0135] Embodiment 2:

[0136] This embodiment corresponds to two deposition growth processes, one of which is incomplete sequencing.

[0137] This embodiment adjusts the placement positions of the wafers in the furnace body to unify the thickness uniformity between each wafer, thereby improving the thickness uniformity between wafers.

[0138] In the sequencing method used in this embodiment, the position of one wafer boat remains unchanged, and the order of wafers in the wafer boat remains unchanged, while other wafer boats are arranged in reverse order, and the wafers in the wafer boats are also arranged in reverse order.

[0139] The parameters after the first deposition growth process are shown in Table 8.

[0140] The parameters after the second deposition growth process without sequence adjustment are shown in Table 9.

[0141] The parameters of the second deposition growth process after the sequence adjustment are shown in Table 10.

[0142] Table 8 First process parameters

[0143]

[0144]

[0145] Table 9 Parameters of the second process without sequence adjustment

[0146] Wafer number Wafer location Mean thickness Thickness uniformity within the sheet U2 #01 1 600.0 13 1.08 #05 5 600.0 12.4 1.03 #10 10 600.0 11.6 0.97 #15 15 600.0 9.6 0.80 #20 20 600.0 9.2 0.77 #25 25 600.0 9 0.75 #30 30 600.0 8.4 0.70 #35 35 600.0 8.8 0.73 #40 40 600.0 8.2 0.68 #45 45 600.0 8 0.67 #50 50 600.0 7.6 0.63 #55 55 600.0 7.8 0.65 #60 60 600.0 7.2 0.60 #65 65 600.0 6.4 0.53 #70 70 600.0 6 0.50 #75 75 600.0 5.8 0.48 #80 80 600.0 6.2 0.52 #85 85 600.0 7.2 0.60 #90 90 600.0 7 0.58 #95 95 600.0 8.4 0.70 #100 100 600.0 9 0.75

[0147] Table 10 Second process adjustment parameters

[0148]

[0149]

[0150] As shown in Table 10, through the incomplete sequencing method, except for the wafer boat that did not participate in the sequencing, the thickness uniformity difference between the wafers of the remaining wafer boats that passed the sequencing was 0.2; as shown in Table 9, the thickness uniformity between the wafers of the products that did not undergo sequencing was 0.27. Figure 6 As shown, it is obvious that the thickness uniformity distribution between sheets after adjustment is more convergent.

[0151] Embodiment 3

[0152] This embodiment corresponds to three deposition growth processes and two incomplete sequencing processes.

[0153] This embodiment adjusts the placement positions of the wafers in the furnace body to unify the thickness uniformity between each wafer, thereby improving the thickness uniformity between wafers.

[0154] In the first adjustment of the sequence of this embodiment, the position of one wafer boat remains unchanged, and the order of wafers in the wafer boat remains unchanged, and the other wafer boats are arranged in reverse order, and the wafers in the wafer boats are also arranged in reverse order. In the second adjustment of the sequence, the position of one wafer boat remains unchanged, and the order of wafers in the wafer boat remains unchanged, and the other wafer boats are arranged in reverse order, and the wafers in the wafer boats are also arranged in reverse order.

[0155] The parameters after the first deposition growth process are shown in Table 11.

[0156] The parameters after the second deposition growth process without sequence adjustment are shown in Table 12.

[0157] The parameters after the third deposition growth process without sequence adjustment are shown in Table 13.

[0158] The parameters of the second deposition growth process after sequencing are shown in Table 14.

[0159] The parameters after the third deposition growth process after sequencing are shown in Table 15.

[0160] in:

[0161] U3 is the thickness uniformity between sheets after the third process without sequence adjustment; U3r is the thickness uniformity between sheets after the third process with sequence adjustment;

[0162] Table 11 First process parameters

[0163]

[0164] Table 12 Parameters of the second process without sequence adjustment

[0165]

[0166]

[0167] Table 13 Parameters of the third process without sequence adjustment

[0168] Wafer number Wafer location Mean thickness Thickness uniformity within the sheet U3 #01 1 900.0 19.5 1.08 #05 5 900.0 18.6 1.03 #10 10 900.0 17.4 0.97 #15 15 900.0 14.4 0.80 #20 20 900.0 13.8 0.77 #25 25 900.0 13.5 0.75 #30 30 900.0 12.6 0.70 #35 35 900.0 13.2 0.73 #40 40 900.0 12.3 0.68 #45 45 900.0 12 0.67 #50 50 900.0 11.4 0.63 #55 55 900.0 11.7 0.65 #60 60 900.0 10.8 0.60 #65 65 900.0 9.6 0.53 #70 70 900.0 9 0.50 #75 75 900.0 8.7 0.48 #80 80 900.0 9.3 0.52 #85 85 900.0 10.8 0.60 #90 90 900.0 10.5 0.58 #95 95 900.0 12.6 0.70 #100 100 900.0 13.5 0.75

[0169] Table 14 Second process adjustment parameters

[0170]

[0171]

[0172] Table 15 The third process adjustment parameters

[0173] Wafer number Wafer location Mean thickness Thickness uniformity within the sheet U3R #01 75 900.0 15.5 0.86 #05 70 900.0 14.6 0.81 #10 65 900.0 13.7 0.76 #15 60 900.0 12.5 0.69 #20 55 900.0 11.7 0.65 #25 100 900.0 11.2 0.62 #30 95 900.0 13.7 0.76 #35 90 900.0 13.8 0.77 #40 85 900.0 13.5 0.75 #45 80 900.0 12.7 0.71 #50 25 900.0 12.2 0.68 #55 20 900.0 11 0.61 #60 15 900.0 11.3 0.63 #65 10 900.0 11.1 0.62 #70 5 900.0 11.4 0.63 #75 1 900.0 11.9 0.66 #80 50 900.0 11.6 0.64 #85 45 900.0 12 0.67 #90 40 900.0 12.5 0.69 #95 35 900.0 13.4 0.74 #100 30 900.0 13.9 0.77

[0174] As shown in Table 14, the thickness uniformity difference between wafers after the first adjustment is 0.55. As shown in Table 15, the thickness uniformity difference between wafers after the second adjustment is 0.25. As shown in Table 13, the thickness uniformity between wafers of the three batches of products without adjustment is 0.60. Figure 7 As shown, it is obvious that the thickness uniformity distribution between sheets can be further converged by multiple adjustments.

[0175] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0176] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for improving the uniformity of film thickness, characterized in that: The following steps are involved: S1: placing the wafer boats carrying the wafers in the furnace tube according to the set arrangement order; S2: performing a deposition growth process of a thin film layer; S3: After the deposition growth process is completed, detect whether the first inter-wafer thickness uniformity of all wafers is less than the inter-wafer thickness uniformity threshold; if it is less than the inter-wafer thickness uniformity threshold, end the process; if it is not less than the inter-wafer thickness uniformity threshold, continue to execute; S4: adjusting the arrangement order of each of the wafer boats, and re-placing each of the wafer boats in the furnace tube according to the adjusted arrangement order, and executing step S2.

2. The method for improving the uniformity of film thickness according to claim 1, characterized in that: In the step S4, before re-placing each wafer boat in the furnace tube according to the adjusted arrangement sequence, the step also includes: adjusting the arrangement sequence of each wafer in each wafer boat.

3. The method for improving the uniformity of film thickness according to claim 2, characterized in that: The arrangement order of the wafers in the wafer boat is adjusted by the following steps: The wafers are rearranged in the reverse order of their existing sequence.

4. The method for improving film thickness uniformity according to claim 1, characterized in that: The adjusting the arrangement sequence of each wafer boat includes a first adjustment method and a second adjustment method; In the first sequencing method, the adjustment is performed based on the second inter-wafer thickness uniformity of the wafers in each wafer boat; In the second sequencing method, the position of at least a portion of the wafer boats is designated to remain unchanged.

5. The method for improving film thickness uniformity according to claim 4, characterized in that: The first sequencing method includes: Step S4-1: calculating the second inter-wafer thickness uniformity of the wafers in each wafer boat, and arranging the wafer boats in the order of the second inter-wafer thickness uniformity, in the order of U1, U2...Un, where Un is the second inter-wafer thickness uniformity of the wafer boat, and n is the number of wafer boats; Step S4-2: Replace the order of the wafer boats corresponding to the second wafer-to-wafer thickness uniformity of Ux and Un+1-x, where x is a positive integer less than or equal to n.

6. The method for improving the uniformity of film thickness according to claim 4, characterized in that: The second sequencing method includes: Step S4-1': Calculate the second inter-wafer thickness uniformity of the wafers in each wafer boat, the wafer boat positions corresponding to the smallest m second inter-wafer thickness uniformities remain unchanged in each deposition growth process, and the remaining wafer boats are arranged in the order of the size of the second inter-wafer thickness uniformity, and the arrangement order is Um+1, Um+2...Un, Un is the second inter-wafer thickness uniformity of the wafer boat, and n is the number of wafer boats; Step S4-2': replace the order of the wafer boats corresponding to the second inter-wafer thickness uniformity of Um+y and Un+1-y, where y is a positive integer less than or equal to nm.

7. The method for improving film thickness uniformity according to claim 4, characterized in that: Before adjusting the arrangement order of each wafer boat, the method further includes the following steps: A sequencing method is determined between the first sequencing method and the second sequencing method to adjust the arrangement order of the wafer boats.

8. The method for improving the uniformity of film thickness according to any one of claims 5 or 6, characterized in that: Before the wafer boats are re-placed in the furnace tube according to the adjusted arrangement order in step S4, the following steps are also included: Calculate the intra-wafer thickness uniformity of each wafer in the two wafer boats that are replaced with each other, and sort all the wafers in the two wafer boats in the order of the same intra-wafer thickness uniformity. If the arrangement order of the wafers in the two wafer boats is not opposite, rearrange the wafers in the two wafer boats in the reverse order of the existing order.

9. The method for improving film thickness uniformity according to claim 1, characterized in that: Before executing step S2 in step S4, the following steps are also included: The number of deposition growth processes executed is calculated; if the number of deposition growth processes is equal to a process number threshold, the process is terminated; if the number of deposition growth processes is less than the process number threshold, the process is continued.

10. The method for improving the uniformity of film thickness according to claim 9, characterized in that: The process number threshold is less than or equal to 3.

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