Method for monitoring epitaxial fill rate of deep trench super junction MOSFET products

Abstract

The present invention discloses a method for monitoring the epitaxial filling rate of a deep trench super junction MOSFET product, which comprises the following steps: the deep trench super junction MOSFET product uses a (100) crystal phase silicon substrate, and before epitaxial filling, a first characteristic dimension of a specific test unit position is measured by a CD measuring machine; according to the coordinates of the specific test unit, a physical radius of the specific test unit from the center of the epitaxial wafer is calculated; epitaxial filling is performed, and after the epitaxial filling, a second characteristic dimension of the specific test unit position is tested by a CD measuring machine to obtain the height of the epitaxial overfilling part; and a graph is drawn based on the calculated physical radius of the specific test unit from the center of the epitaxial wafer and the height of the epitaxial overfilling part to obtain the relationship between the physical radius of the specific test unit from the center of the epitaxial wafer and the height of the epitaxial overfilling part. The present invention can quantitatively and intuitively describe the epitaxial filling rate of the deep trench super junction MOSFET product, and can also monitor the epitaxial filling rate at different positions within the product surface.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for monitoring the epitaxial filling rate of a deep trench super junction (SuperJunction) MOSFET product. Background Art

[0002] Deep trench super junction MOSFET products are widely used in cloud servers, UPS uninterruptible power management, LED lighting, smart bicycles, mobile terminals and other fields due to their ultra-low on-resistance, ultra-fast switching speed, low internal resistance, low power consumption, high efficiency and small chip size. The application range covers various products from 200-1000V, and the product types are complex and diverse.

[0003] With the continuous upgrading of deep trench super junction MOSFET products, the pitch size is getting smaller and smaller, and the requirements for uniformity of epitaxial filling surface are getting higher and higher. Since the epitaxial growth of MOSFET products is directly grown on single crystal silicon, it is impossible to directly measure the film thickness to monitor the epitaxial filling rate. The previous method has always been to judge the distribution of epitaxial filling surface through optical microscope photos. Optical microscope photos under different experimental conditions can only express the epitaxial filling rate situation in the surface through subjective and non-quantifiable descriptions such as underfill, overfill, and severe overfill. Summary of the invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a method for monitoring the epitaxial filling rate of a deep trench super junction MOSFET product.

[0005] The present invention solves the above technical problems through the following technical solutions: a method for monitoring the epitaxial filling rate of deep trench super junction MOSFET products, characterized in that it comprises the following steps:

[0006] Step 1: Deep trench super junction MOSFET products use (100) crystalline silicon substrates to perform epitaxial filling in the deep trench. Step 1: Deep trench super junction MOSFET products use (100) crystalline silicon substrates to measure the first characteristic dimension CD1 of a specific test unit position by a CD measurement machine before epitaxial filling.

[0007] Step 2: Calculate the physical radius R of the specific test unit from the center of the epitaxial wafer according to the coordinates of the specific test unit;

[0008] Step 3, epitaxial filling is performed. After the epitaxial filling, the second characteristic dimension CD2 of the specific test unit position is tested by a CD measurement machine. The height H of the epitaxial overfilling part can be obtained by the principle of epitaxial growth: H = (CD2-CD1) / 2;

[0009] Step 4: Draw a graph based on the calculated physical radius R of the specific test unit from the center of the epitaxial wafer and the height H of the epitaxial overfill portion to obtain the relationship between the physical radius R of the specific test unit from the center of the epitaxial wafer and the height H of the epitaxial overfill portion, that is, the relative epitaxial filling rate distribution within the physical radius R.

[0010] Preferably, an optical microscope and a scanning electron microscope are installed on the CD measuring machine.

[0011] Preferably, the physical radius R in step 1 adopts the following formula:

[0012]

[0013] X is the abscissa of the specific test unit, and Y is the ordinate of the specific test unit.

[0014] Preferably, the step 2 is to draw a map according to the coordinates of the specific test unit to obtain a distribution map of epitaxial filling rates on the wafer surface.

[0015] Preferably, the step 4 uses the following formula to obtain the epitaxial filling rate v:

[0016]

[0017] T is the epitaxial filling time.

[0018] The positive progressive effect of the present invention is that the present invention can quantitatively and intuitively describe the epitaxial filling rate of deep trench super junction MOSFET products by measuring the characteristic dimension CD of a specific test key, and can also monitor the epitaxial filling rate at different positions within the product surface, thereby providing a new monitoring means for adjusting the epitaxial filling rate within the surface of deep trench super junction MOSFET products. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0021] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0022] like Figure 1 As shown, the method for monitoring the epitaxial filling rate of a deep trench super junction MOSFET product of the present invention comprises the following steps:

[0023] Step 1: The deep trench super junction MOSFET product uses a (100) crystal phase silicon substrate, and measures the first characteristic dimension CD1 of a specific test unit position by a CD measurement machine before epitaxial filling;

[0024] Step 2: Calculate the physical radius R of the specific test unit from the center of the epitaxial wafer according to the coordinates of the specific test unit, that is, the distance R between the physical position of the specific test unit in the epitaxial wafer surface and the center of the epitaxial wafer;

[0025] Step 3, epitaxial filling is performed. After the epitaxial filling, the second characteristic dimension CD2 of the specific test unit position is tested by a CD measurement machine. The height H of the epitaxial overfilling part can be obtained by the principle of epitaxial growth: H = (CD2-CD1) / 2;

[0026] Step 4: Based on the calculated physical radius R of the specific test unit from the center of the epitaxial wafer and the height H of the epitaxial overfill portion, a graph is drawn to obtain the relationship between the physical radius R of the specific test unit from the center of the epitaxial wafer and the height H of the epitaxial overfill portion, that is, the relative epitaxial filling rate distribution within the physical radius R. Based on this relationship, the epitaxial filling rate within the specific radius range of the deep trench super junction MOSFET product can be quantitatively described.

[0027] The CD measuring machine is equipped with an optical microscope and a scanning electron microscope to facilitate scanning inspection and improve measurement accuracy.

[0028] The physical radius R in step 1 is calculated using the following formula (1):

[0029]

[0030] X is the abscissa of the specific test unit, and Y is the ordinate of the specific test unit.

[0031] Step 2: Draw a map based on the coordinates of the specific test unit to obtain the epitaxial filling rate distribution map on the wafer surface, which is easy to use.

[0032] Step 4: Use the following formula (2) to obtain the epitaxial filling rate v:

[0033]

[0034] T is the epitaxial filling time.

[0035] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0036] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for monitoring the epitaxial filling rate of a deep trench super junction MOSFET product, characterized in that: It includes the following steps: Step 1: The deep trench super junction MOSFET product uses a (100) crystal phase silicon substrate, and measures the first characteristic dimension CD1 of a specific test unit position by a CD measurement machine before epitaxial filling; Step 2: Calculate the physical radius R of the specific test unit from the center of the epitaxial wafer according to the specific test unit coordinates; Draw a graph according to the specific test unit coordinates to obtain an epitaxial filling rate distribution graph on the wafer surface; Step 3, epitaxial filling is performed. After the epitaxial filling, the second characteristic dimension CD2 of the specific test unit position is tested by a CD measurement machine. The height H of the epitaxial overfilling part can be obtained by the principle of epitaxial growth: H = (CD2-CD1) / 2; Step 4: Use the following formula to get the epitaxial filling rate v: T is the epitaxial filling time; The relationship between the physical radius R of the specific test unit from the center of the epitaxial wafer and the height H of the epitaxial overfill portion is obtained by plotting the calculated physical radius R of the specific test unit from the center of the epitaxial wafer and the height H of the epitaxial overfill portion.

2. The method for monitoring the epitaxial filling rate of a deep trench super junction MOSFET product according to claim 1, characterized in that: An optical microscope and a scanning electron microscope are installed on the CD measuring machine.

3. The method for monitoring the epitaxial filling rate of a deep trench super junction MOSFET product according to claim 1, characterized in that: The physical radius R of step 1 is calculated using the following formula: X is the abscissa of the specific test unit, and Y is the ordinate of the specific test unit.

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