CN101651086B

CN101651086B - Method for monitoring ion implantation angle

Info

Publication number: CN101651086B
Application number: CN2008101346745A
Authority: CN
Inventors: 许义全; 王冬晶
Original assignee: Hejian Technology Suzhou Co Ltd
Current assignee: Hejian Technology Suzhou Co Ltd
Priority date: 2008-08-15
Filing date: 2008-08-15
Publication date: 2011-02-02
Anticipated expiration: 2028-08-15
Also published as: CN101651086A

Abstract

The invention relates to a method for monitoring an ion implantation angle, which comprises the following steps: 1, providing a monitoring wafer; 2, introducing ions of predetermined dosage into the monitoring wafer at a predetermined depth by using an ion implanter, wherein the implanted incident angle is 0 degree; and 3, measuring the damaged degree of the surface of the monitoring wafer finished by ion implantation in step 2, and judging the accuracy of the incident angle according to the symmetry of measured graphs. The method can accurately monitor the ion implantation angle based on the unchanged prior equipment so as to ensure that the ion implantation angle is in a set range, ensure the performance of a device and improve the qualification rate of the wafer.

Description

A kind of method of monitoring ion implantation angle

Technical field

The present invention relates to the ion implantation technique in the semiconductor fabrication process, particularly relate to a kind of method of monitoring ion implantation angle.

Background technology

It is a kind of very important technology that modern integrated circuits is made that ion injects, it utilizes ion implantor to realize semi-conductive doping, is about to specific foreign atom and injects its conductive characteristic of change and the final transistor arrangement that forms in the silicon semiconductor crystal in the mode of ion acceleration.

The accurate location of impurity is the key factor that guarantees the advanced device optimal operational condition.Inject for ion, dosage, energy and ion beam angle all need correct control.Yet people only know the importance of dosage and energy control for a long time, and people recognize that just ion beam angle also can influence device performance up to date.Ion incidence angle difference will cause ion to inject that the degree of depth changes and the electrical quantity that influence device, therefore, and to the unusual necessity of the control of ion beam incident angle.Important implanted layer such as light dope seepage (LDD) layer or bag (PKT) implanted layer inject angle control especially responsively to ion in some advanced technologies, and this moment, the ion beam angle error can cause negative effect to drive current (ION) and cut-off leakage current (IOFF).

In traditional batch processing formula (Batch type) ion implantor, because the target disc (Disk) that ion implantor self is used for supporting wafers is designed to the pot shape shown in Figure 1A, when ion is injected into wafer, will there be certain difference in the incidence angle of center wafer and the incidence angle of Waffer edge.If target disc itself or ion beam exist and depart from, not vertical incidence when the incident center wafer, incidence angle at Waffer edge will become bigger like this, and the implanted layer important in some advanced technologies that departs from of this incidence angle (as LDD, PKT) is not allowed to.Therefore, need the angle of monitoring ion injection termly to be within the setting range to guarantee it.And in existing batch processing formula (Batch type) ion implantor, there is no such monitoring mechanism and go to monitor the true incidence angle of ion beam on wafer.

Summary of the invention

At defective of the prior art, the objective of the invention is to propose a kind of method of monitoring ion implantation angle, by accurate monitoring, guarantee that it is in setting range, thereby guarantee device performance ion implantation angle, improve wafer passing rate.

In order to reach above-mentioned and other purposes of the present invention, the present invention proposes a kind of method of monitoring ion implantation angle, it is characterized in that, comprises the steps:

Step 1, provide monitoring wafer;

Step 2, in above-mentioned monitoring wafer, utilize ion implantor to introduce the ion of predetermined close in desired depth, the incidence angle of its injection is 0 degree;

Step 3, measurement step 2 intermediate ions inject the destroyed degree of finishing in monitoring wafer surface, according to the symmetry of institute's mapping shape, judge the accuracy of incident angle.

As preferably, use the heat wave instrument to measure in the step 3.

As preferably, the symmetric process of the judgement institute mapping shape in the step 3 comprises:

Step 31 is determined the raceway groove center of wafer;

Step 32 determines that the raceway groove center is along two line segments that arrive the wafer two ends perpendicular to the direction of raceway groove;

Step 33 is divided by the length value of article one line segment and second line segment, then subtracts each other and takes absolute value with 1, obtains symmetry value, and this symmetry value is directly proportional with the accuracy of incident angle.

As preferably, the monitoring wafer in the above-mentioned steps 1 is a N type silicon wafer.

As preferably, above-mentioned ion is the boron ion.

As preferably, the injection energy range of the ion implantor in the above-mentioned steps 2 is 50～80 kiloelectron-volts, and preferably 70 kiloelectron-volts, the dosage range of the boron ion of injection is 1E13～5E13.

Adopt method of the present invention, can on the basis that does not change existing equipment, ion implantation angle be monitored accurately, thereby guarantee that ion implantation angle is in setting range, guarantee device performance, improve wafer passing rate.

Description of drawings

Figure 1A is the front view of the target disc of supporting wafers in the traditional ion implantor;

Figure 1B is the lateral plan of the target disc of supporting wafers in the traditional ion implantor;

The symmetric determination methods schematic diagram of the figure that Fig. 2 measures out for the heat wave instrument;

Fig. 3 is the schematic diagram according to the method for a kind of monitoring ion implantation angle of the present invention.

Embodiment

For a more detailed description below in conjunction with accompanying drawing to the specific embodiment of the present invention.

Referring to Fig. 3, a kind of method of monitoring ion implantation angle comprises the steps:

Step 1, provide monitoring wafer, the material of this monitoring wafer can be any suitable material, in the present embodiment, use N type silicon wafer, for example N type (110) silicon wafer is as monitoring wafer, select for use the reason of this wafer to be that its channelling effect is comparatively remarkable, this monitoring wafer can be according to the chip type decision of actual manufacturing.

Step 2, in above-mentioned monitoring wafer, utilize ion implantor to introduce the ion of predetermined close in desired depth.The type of this ion, desired depth and predetermined close can be according to the needed degree of depth of reality and dosage decisions, in the present embodiment, what introduce is the boron ion of predetermined close, it injects the energy decision of the degree of depth by ion implantor, the energy range of this ion implantor is 50～80 kiloelectron-volts (Kev), and preferably 70 kiloelectron-volts, the dosage range of introducing the boron ion is 1E13～5E13,5E13 preferably, the incidence angle of the injection of this boron ion is 0 degree.Adopt the advantage of above-mentioned energy and dosage range to be, the destroyed degree of chip surface is comparatively suitable in this energy dose scope, if energy dose is too big, then chip surface is destroyed more serious; If energy dose is too little, then chip surface is destroyed slighter, all is unfavorable for the accurate measurement of heat wave instrument.

Step 3, inject the destroyed degree in monitoring wafer surface finish with heat wave instrument measurement step 2 intermediate ions, the symmetry of the figure that measures out according to the heat wave instrument is judged the accuracy of incident angle.

Referring to Fig. 2, line segment among the figure or closed curve are equipotential lines, and promptly the heat wave value (Thermal Wave value) that measures out of the heat wave instrument on the same line section or the curve equates.The method of the accuracy of judgement incident angle is specific as follows in the above-mentioned steps 3:

Step 31 is determined the raceway groove center of wafer, and line segment among the figure two or closed curve are equipotential lines, "-" number then expression, and the outer heat wave value of equipotential lines is less than the value on the equipotential lines, and is far away more apart from equipotential lines, represents that then the heat wave value is more little; And the i.e. axis of symmetry (being line segment 3) of closed curve among the figure two in heat wave value minimum place, channelling effect has taken place in this place of expression, the minimum place of heat wave value, surperficial destroyed degree minimum, and promptly this place is exactly the raceway groove center, and ion implantation angle is " 0 ";

Step 32 determines that the raceway groove center arrives two line segments at wafer two ends along the direction that is basically perpendicular to raceway groove;

At first, vertical score is distinguished to the wafer leftmost side and the rightmost side in the raceway groove center (stain on the line segment 3 shown in Figure 2) that measures figure from wafer, obtains line segment 1 and line segment 2; Secondly, measure the length of line segment 1 and line segment 2, deduct the absolute value representation symmetry of the length of line segment 1 divided by the length of line segment 2 with 1; At last, according to the accuracy of symmetry judgement incident angle, symmetry is more little, and the expression incident angle is accurate more, and symmetry is big more, and the expression incident angle departs from big more.

Preferred embodiment of the present invention and effect thereof have more than been described; certainly; the present invention also can have other embodiment; under the situation of spirit that does not deviate from the present invention and essence; the person of ordinary skill in the field works as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of claim of the present invention.

Claims

1. the method for a monitoring ion implantation angle is characterized in that, comprises the steps:

Step 1, provide monitoring wafer;

Step 3, measurement step 2 intermediate ions inject the destroyed degree of finishing in monitoring wafer surface, calculate according to survey numerical value doing mathematics, judge the accuracy of incident angle,

Wherein, step 3 specifically comprises: utilize the heat wave instrument to measure whole wafer, be judged to be the raceway groove center in the place of measuring value minimum, determine that then the raceway groove center is along two line segments that arrive the wafer two ends perpendicular to the direction of raceway groove; The length value of article one line segment and second line segment is divided by, then subtracts each other and take absolute value with 1, obtain symmetry value, this symmetry value is directly proportional with the accuracy of incident angle.

2. the method for a kind of monitoring ion implantation angle according to claim 1 is characterized in that, the monitoring wafer in the above-mentioned steps 1 is a N type silicon wafer.

3. the method for a kind of monitoring ion implantation angle according to claim 2 is characterized in that, above-mentioned ion is the boron ion.

4. the method for a kind of monitoring ion implantation angle according to claim 1 is characterized in that, the injection energy range of the ion implantor in the above-mentioned steps 2 is 50～80 kiloelectron-volts, and the dosage range of the boron ion of injection is 1E13～5E13.