CN102565143B - On-line Testing Structure of Residual Stress of Polysilicon Material - Google Patents

Abstract

The invention discloses an on-line test structure for polysilicon material residual stress. The test structure includes three polysilicon deflection pointers with the same basic structure. The three polysilicon deflection pointers are placed in the shape of "品". The control of the initial deflection direction under the action of residual stress makes the spacing maintenance and spacing change can effectively reflect the magnitude and nature of the residual stress; the manufacturing process of the test structure is simple, and there is no special processing requirement; the test is driven by heat, and the measurement parameters are thermal The resistance of the driven beam before and after driving. During the use of the present invention, although the principle of thermal expansion is adopted, the thermal expansion coefficient is not required for measurement and calculation, which avoids the influence of errors during online testing of the thermal expansion coefficient on the measurement results. The invention has the advantages of simple test structure, convenient loading and measurement of electrical signals, stable calculation method and the like.

Description

On-line Testing Structure of Residual Stress of Polysilicon Material

technical field

The invention relates to an on-line testing structure for polysilicon material residual stress, and belongs to the technical field of on-line testing of micro-electromechanical systems (MEMS) material parameters.

Background technique

The performance of microelectromechanical devices is closely related to material parameters. Due to the influence of processing, some material parameters will change. These uncertain factors caused by processing technology will make device design and performance prediction uncertain and unstable. Case. The purpose of online testing of material parameters is to measure the material parameters of MEMS devices manufactured by a specific process in real time, monitor the stability of the process, and feed back the parameters to the designer so that the design can be corrected. Therefore, online testing without leaving the processing environment and using general-purpose equipment has become a necessary means of process monitoring. The online test structure usually adopts the method of electrical excitation and electrical measurement, and the physical parameters of the material are obtained through the electrical quantity value and targeted calculation methods.

Polysilicon is an important and basic material for the manufacture of micro-electromechanical device structures, and is usually produced by chemical vapor deposition (CVD). Polysilicon material will generate internal stress during the manufacturing process, that is, residual stress exists. Residual stress is divided into compressive stress and tensile stress. When the MEMS structure is released, the residual stress will lead to the initial deformation of the structure or have an impact on other material parameters, resulting in the deviation of the actual performance from the design performance.

Contents of the invention

Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides an online testing structure for polysilicon material residual stress.

Technical solution: In order to achieve the above object, a polysilicon material residual stress online testing structure of the present invention includes three polysilicon deflection pointers, and the three polysilicon deflection pointers respectively include a polysilicon drive beam, a polysilicon pointer and an anchor area; three polysilicon deflection pointers It is placed in the shape of "品", and the polysilicon pointers point to the center; the structure of the polysilicon deflection pointer at the lower left and the lower right is exactly the same, and the vertical center line of the test structure mirrors left and right. The upper polysilicon deflection pointer is at the center, and the direction of the pointer is the same as The left and right polysilicon deflection pointers in the lower part are opposite; the entire test structure is fabricated on an insulating substrate, except for the anchor region and the metal electrodes on it. Free expansion and deflection.

The distance between the ends of the left, middle and right pointers is affected by the polysilicon residual stress differently, the distance between the left-middle pointer ends is not affected by the polysilicon residual stress, and the distance between the middle-right pointer ends changes with the size and nature of the polysilicon residual stress .

In the lower left polysilicon deflection pointer, metal electrodes are formed on the anchor area at one end of the drive beam and the anchor area at one end of the pointer; in the lower right polysilicon deflection pointer, the anchor area at one end of the drive beam and the anchor area at one end of the pointer Metal electrodes are made respectively; in the upper polysilicon deflection pointer, the metal electrode is only made on the anchor area at one end of the pointer.

The polysilicon driving beams of the three polysilicon deflection pointers have equal lengths.

Beneficial effects: the polysilicon material residual stress online testing structure of the present invention arranges three polysilicon deflection pointers with the same basic structure in the shape of a "pin", and utilizes the same characteristic that these pointers are affected by the polysilicon residual stress to make the residual stress The size and properties of can be effectively measured. The test method is to use current to heat the driving beam of the deflection pointer to make it expand, and then push the pointer to deflect, and measure the influence of residual stress on the deflection. Using the invention to test the residual stress of polysilicon, the method is simple, the requirements for testing equipment are low, the processing process is synchronized with micro-electromechanical devices, there is no special processing requirement, and it fully meets the requirements of on-line testing. The calculation method in the present invention is limited to simple mathematical formulas. Although the principle of thermal expansion is adopted, the thermal expansion coefficient is not required for measurement and calculation, which avoids the influence of errors on the measurement results when the thermal expansion coefficient is tested online, and has the advantages of simple test structure, electrical signal loading and It has the advantages of simple measurement and stable calculation method.

Description of drawings

Fig. 1 is the schematic diagram of polysilicon material residual stress online test structure of the present invention;

FIG. 2 is a cross-sectional view along line A-A of FIG. 1 .

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Fig. 1 and Fig. 2, the polysilicon material residual stress on-line testing structure of the present invention comprises three deflection pointers with the same basic structure, each deflection pointer comprising a horizontal drive beam 101, 103, 105, a drive beam connected to the drive beam 101, 103, 105 are composed of vertical pointers 102, 104, 106 and two anchor regions fixed on the substrate. one end. The main body of the test structure is fabricated from polysilicon material.

The three polysilicon deflection pointers are placed in the shape of "pin", and the pointers 102, 104, and 106 all point to the center; the upper polysilicon deflection pointer includes the driving beam 101, the pointer 102, the anchor areas 107, 108 and the metal electrodes on the anchor area 108 118; the polysilicon deflection pointer on the lower left includes a drive beam 103, pointer 104, anchor regions 109, 110 and metal electrodes 113, 114 on the anchor region; the polysilicon deflection pointer on the lower right includes a drive beam 105, pointer 106, anchor regions 111, 112 and metal electrodes 115, 116 on the anchor region. The polysilicon deflection pointers at the lower left and lower right are exactly the same, and are placed symmetrically with respect to the center line of the pointer 102, which is the vertical center line of the entire test structure. The whole test structure is made on the insulating substrate 117, except the anchor region and the metal electrodes on it, after the structure is released, the drive beams 101, 103, 105 and pointers 102, 104, 106 are all in a suspended state, so that these Partial release of residual stress and free expansion and deflection.

The lengths of the driving beams 101, 103, 105 are all _L2 . After the structure is released, the beams will initially expand and contract due to the residual stress, and then push the pointers 102, 104, and 106 to deflect around their rotation axes. Because the basic structures are the same, the The deflection angle due to residual stress is the same. The distance from the vertical centerline of the drive beams 101 , 103 , 105 to the corresponding anchoring areas 108 , 110 , 111 is L ₅ .

The lengths of pointers 104 and 106 are both L ₁ ; the length of pointer 102 is equal to L ₁ +L ₄ , and L ₄ is the overlapping length of pointer 102 and pointers 104 and 106 in the vertical direction, which is much smaller than L ₁ . The head of the pointer 102 is a rectangle with a larger width, and the purpose of increasing the width is to maintain a larger distance between the anchor regions 110 and 111 to facilitate the use of test probes.

The designed spacing between the pointers 102 and 104 is g ₁ , and the designed spacing between the pointers 102 and 106 is g ₂ .

Metal electrodes 118, 113, 114, 115 and 116 are fabricated on the anchor regions 108, 109, 110, 111 and 112 respectively, wherein the metal electrode 114 extends to the driving beam 103, and the metal electrode 115 extends to the driving beam 105. On the above, when the heating drive works, the effective heating area length is L ₂ -L ₃ .

The polysilicon material residual stress on-line testing structure of the present invention, principle is as follows:

Because the residual stress existing in the polysilicon will cause the driving beams 101, 103 to produce an initial length change after the structure is released, and then cause the pointers 102, 104 to initially deflect. However, because the pointers 102 and 104 are deflected in opposite directions around the axis and have the same deflection angle under the action of residual stresses of the same nature and magnitude, the distance between the pointer ends can remain unchanged, which is still g ₁ . Similarly, the residual stress will cause the drive beam 105 to undergo an initial change in length after the structure is released, thereby causing an initial deflection of the pointer 106 in a direction opposite to that of the pointer 104 . Because pointer 102 and pointer 106 rotate in the same direction, the actual distance deviates from the design value g ₂ due to residual stress. If the residual stress is compressive stress, the actual distance is less than g ₂ . If the residual stress is tensile stress, the actual The spacing is greater than g ₂ .

The invention adopts the working mode of heat-driven deflection pointer rotation. A current is applied between the metal electrode 113 and the metal electrode 114, so that the part _L2 - _L3 in the drive beam 103 undergoes thermal expansion, and the pointer 104 is pushed to deflect clockwise. When the tip of the pointer 104 contacts the pointer 102, the tip of the pointer 104 clockwise The hour hand is deflected by a distance g ₁ . A current is applied between the metal electrode 115 and the metal electrode 116, so that the part _L2 - _L3 in the driving beam 105 undergoes thermal expansion, and the pointer 106 is pushed to deflect counterclockwise. The actual distance deflected counterclockwise is g. Obviously, due to the effect of residual stress, the deflection distance g of the tip of 106 will not be equal to g ₂ . If it happens that g is equal to _g2 , it means that the residual stress is 0.

The test structure of the present invention is completed by basic micro-electro-mechanical processing technology, and the manufacturing process of the test structure will be described below with a typical two-layer polysilicon micro-electro-mechanical surface processing process.

Select an N-type semiconductor silicon wafer, thermally grow a silicon dioxide layer with a thickness of 100 nanometers, and deposit a layer of silicon nitride with a thickness of 500 nanometers by a low-pressure chemical vapor deposition process to form an insulating substrate 117 . A layer of 300nm polysilicon is deposited by a low-pressure chemical vapor deposition process and N-type heavy doping is performed to make the layer of polysilicon a conductor, and a part of the anchor region is formed by etching by a photolithography process. Phospho-silicate glass (PSG) was deposited with a thickness of 2000 nm using a low-pressure chemical vapor deposition process, and the pattern of the anchor region was formed by a photolithography process. A layer of polysilicon with a thickness of 2000 nanometers is deposited by low-pressure chemical vapor deposition process, N-type heavy doping is carried out on the polysilicon, and the photolithography process forms the online test structure pattern of the residual stress of the polysilicon material. The thickness of the anchor area is the sum of the thickness of the two polysilicons. . A metal electrode pattern is formed on the anchor region by a lift-off process. Finally the structure is released by etching the phosphosilicate glass.

The test method of the present invention is simple, adopts simple variable current source as excitation source, adopts common multimeter to monitor whether two pointers touch, adopts resistance meter to measure resistance, and specific process is as follows:

1), test process

The testing process is carried out in several stages:

1. measure the resistance between metal electrode 113 and metal electrode 114 (or metal electrode 115, metal electrode 116) at room temperature, denoted as R _∞ ;

② Apply a slowly increasing current between the metal electrode 113 and the metal electrode 114, and monitor the resistance between the metal electrode 118 and the metal electrode 114. When the resistance changes from infinite to finite, it indicates that the pointer 104 and the pointer 102 have Contact, stop the increase of heating current;

③ Measure the resistance between the metal electrode 113 and the metal electrode 114 when the pointer 102 and the pointer 104 are in contact, denoted as R _TL , close the current between the metal electrode 113 and the metal electrode 114, and make the pointer 104 rotate away from the pointer 102;

④ Apply a slowly increasing current between the metal electrode 115 and the metal electrode 116, and monitor the resistance between the metal electrode 108 and the metal electrode 115. When the resistance changes from infinite to finite, it indicates that the pointer 106 and the pointer 102 have Contact, stop the increase of heating current;

⑤ measure the resistance between the metal electrode 115 and the metal electrode 116 when the pointer 106 and the pointer 102 are in contact, denoted as R _TR , close the current between the metal electrode 113 and the metal electrode 114, and make the pointer 106 rotate away from the pointer 102;

2), calculate the thermal expansion coefficient of polysilicon material

The relationship between the resistance R _TL of the polysilicon drive beam 103 with a length of L ₂ -L ₃ and the average temperature change ΔT _L on it is:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; TL</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{<span\; class="notranslate">\; \&infin;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

where a ₁ and a ₂ are the temperature coefficients of polysilicon resistance, and the average temperature change ΔT _L is the difference between the average temperature of L ₂ -L ₃ on the thermally driven beam 103 and the room temperature when the pointers 102 and 104 are in contact.

From the basic thermal expansion relationship, the length change of the thermally driven beam 103 ΔL _L =(L ₂ −L ₃ )·α·ΔT _L , where α is the thermal expansion coefficient of the polysilicon material, so:

$\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Delta;\; L</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&Delta;T</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}$

Similarly, the relationship between the resistance R _TR of the polysilicon drive beam 105 with a length of L ₂ -L ₃ and the average temperature change ΔT _R on it is:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; TR</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{<span\; class="notranslate">\; \&infin;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

In the formula, ΔT _R is the difference between the average temperature of the part L ₂ -L ₃ on the thermally driven beam 105 and the room temperature when the pointer 102 and the pointer 106 are in contact. and have:

$\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&Delta;T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}$

Solve:

Existing studies have shown that the temperature coefficients a ₁ and a ₂ of polysilicon resistance can be obtained by measurement, therefore, a ₁ and a ₂ are treated as known quantities.

Substitute the measured R _∞ and R _TL into the resistance formula, and get the root formula of the quadratic equation:

${\mathrm{\&Delta;T}}_L=\frac{-a_1\&PlusMinus;\sqrt{{a_1}^2+{4a}_2{k}_L}}{2a_2},$ In the formula, $k_L=\frac{R_{\mathrm{TL}}-R_{\&infin;}}{R_{\&infin;}}.$

When the polysilicon resistance has a negative temperature coefficient, take the "-" sign before the root sign; when the polysilicon resistance has a positive temperature coefficient, take the "+" sign before the root sign;

The length change _ΔL of the driving beam 103 is obtained by the geometric relationship:

${\mathrm{<span\; class="notranslate">\; \&Delta;L</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; g</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}$

Similarly, the measured R _∞ and R _TR are substituted into the resistance formula, and obtained from the root-finding formula of the quadratic equation:

${\mathrm{\&Delta;T}}_R=\frac{-a_1\&PlusMinus;\sqrt{{a_1}^2+{4a}_2{k}_R}}{{2a}_2},$ In the formula, $k_R=\frac{R_{\mathrm{TR}}-R_{\&infin;}}{R_{\&infin;}}.$

When the polysilicon resistance has a negative temperature coefficient, take the "-" sign before the root sign; when the polysilicon resistance has a positive temperature coefficient, take the "+" sign before the root sign;

The length change ΔL _R of the driving beam 105 is obtained from the geometric relationship:

式中，g是指针106尖端逆时针实际偏转的距离。

In the formula, g is the actual counterclockwise deflection distance of the tip of the pointer 106 .

According to the relational formula of thermal expansion coefficient, we get:

${\mathrm{<span\; class="notranslate">\; \&Delta;\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Delta;T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&Delta;\; L</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}{{\mathrm{<span\; class="notranslate">\; \&Delta;T</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}$

So there are:

$\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&Delta;T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&Delta;\; L</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&Delta;T</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}$

The variable in the formula is either a geometric dimension, or a measured and calculated value that can be obtained. Therefore, the actual counterclockwise deflection distance g of the tip of the pointer 106 can be calculated by the above formula.

ΔL _R can be obtained from the g value, therefore, the strain ε produced by the residual stress in the drive beam is:

$\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Delta;\; L</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Delta;\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

The residual stress σ is:

σ＝E·ε

E is the Young's modulus of the polysilicon material.

If ε=0, it means that there is no residual stress in polysilicon; if ε>0, it means that the residual stress of polysilicon is compressive stress; if ε<0, it means that the residual stress of polysilicon is tensile stress.

The present invention controls the initial deflection direction of the pointer under the action of residual stress so that the distance maintenance and distance change can effectively reflect the magnitude and nature of the residual stress; the manufacturing process of the test structure is simple and there is no special processing requirement; , the measured parameter is the resistance of the driven beam before and after thermal actuation. During the use of the present invention, although the principle of thermal expansion is adopted, the thermal expansion coefficient is not required for measurement and calculation, which avoids the influence of errors during online testing of the thermal expansion coefficient on the measurement results.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also possible. It should be regarded as the protection scope of the present invention.

Claims (3)

1. An online test structure for residual stress of polysilicon material, characterized in that it includes three polysilicon deflection pointers, and the three polysilicon deflection pointers respectively include polysilicon drive beams (101, 103, 105) and polysilicon pointers (102, 104, 106) and the anchor area; the three polysilicon deflection pointers are placed in the shape of "pin", and the pointers (102, 104, 106) all point to the center; the structure of the lower left polysilicon deflection pointer and the lower right polysilicon deflection pointer is exactly the same, to test the vertical center of the structure The line mirrors left and right, the center line of the upper polysilicon deflection pointer is the vertical center line of the entire test structure, and the direction of the pointer (102) is opposite to that of the lower left and right polysilicon deflection pointers (104, 106); the entire test structure is made on an insulating On the substrate (117), after the structure is released, the drive beams (101, 103, 105) and pointers (102, 104, 106) are in a suspended state, so as to release residual stress and freely expand and deflect. 2. The polysilicon material residual stress on-line test structure according to claim 1, characterized in that: in the polysilicon deflection pointer at the lower left part, the anchor area (109) at one end of the drive beam (103) and the anchor at one end of the pointer (104) Metal electrodes (113, 114) are made on the area (110), and the metal electrode (114) on the anchor area (110) at one end of the pointer (104) extends to the driving beam (103); the lower right polysilicon In the deflection pointer, the anchor area (112) at one end of the drive beam (105) and the anchor area (111) at one end of the pointer (106) are respectively made with metal electrodes (116, 115), and the anchor area at one end of the pointer (106) ( 111) on the metal electrode (115) has been extended to the drive beam (105). 3 . The on-line testing structure for polysilicon material residual stress according to claim 1 , characterized in that: the driving beams ( 101 , 103 , 105 ) of the three polysilicon deflection pointers are equal in length. 4 .

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